DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 9/19/2025 has been entered.
Status of Claims
Claims 1 and 4-22 are pending. Claims 14-17 are withdrawn from consideration.
Response to Arguments
Applicant’s arguments, see Remarks, filed 9/19/2025, with respect to the prior art rejections have been fully considered but they are not persuasive.
Applicant’s Remarks note the declaration filed by Inventor. Regarding said declaration, Applicant asserts that “Mr. Mollerhoj [the inventor] is an expert in the field of chemical engineering and his Second Expert Declaration is objective evidence that the Office must consider.” Examiner respectfully disagrees with the assertion that the declaration amounts to objective evidence. Rather, a declaration amounts to an opinion testimony.
Although factual evidence is preferable to opinion testimony, such testimony is entitled to consideration and some weight so long as the opinion is not on the ultimate legal conclusion at issue. While an opinion as to a legal conclusion is not entitled to any weight, the underlying basis for the opinion may be persuasive. In re Chilowsky, 306 F.2d 908, 134 USPQ 515 (CCPA 1962) (expert opinion that an application meets the requirements of 35 U.S.C. 112 is not entitled to any weight; however, facts supporting a basis for deciding that the specification complies with 35 U.S.C. 112 are entitled to some weight); In re Lindell, 385 F.2d 453, 155 USPQ 521 (CCPA 1967) (Although an affiant’s or declarant’s opinion on the ultimate legal issue is not evidence in the case, “some weight ought to be given to a persuasively supported statement of one skilled in the art on what was not obvious to him.” 385 F.2d at 456, 155 USPQ at 524 (emphasis in original)).
(MPEP 716.01(c)III).
The declaration has been considered and given appropriate weight in accordance with its status as opinion testimony. Examiner responds to the declaration filed 9/19/2025 as follows:
Regarding paragraphs 1-5 of the declaration:
Examiner acknowledges the contents of paragraphs 1-5. No further comments on these paragraphs are considered necessary at this time.
Regarding paragraph 6 of the declaration:
Applicant states that “The Office appears to presume that a recycle stream is the only or best way to further improve concentration”. With respect, Examiner does not presume that use of a recycle stream is either the only way or the best way to improve concentration. Regardless, it is unnecessary that a particular modification be the only way of achieving affecting an improvement for said particular modification to be obvious to one of ordinary skill in the art.
Applicant asserts that the Office “offers no evidence that Schoubye’s process requires enhancement or that a recycle stream would provide such.” Examiner respectfully disagrees. The 103 rejections as set forth in the 4/9/2025 Final Rejection and maintained below offer evidence of both. For example, see the 103 rejection of claim 1 on pages 16-19 of the 4/9/2025 Final Rejection.
Applicant asserts that “offers no evidence that “Schoubye does not mention acid recycling as a way to further improve the performance of the acid concentrator; there are reasons for that”. Examiner acknowledges that Schoubye does not mention acid recycling. However, the fact that a reference does not teach or suggest that a particular feature could be incorporated to improve a disclosed invention does not, in and of itself, amount to evidence of non-obviousness.
Regarding paragraph 7 of the declaration:
Applicant asserts that “There is no automatic advantage of recycling by itself”. Insofar as Applicant is broadly asserting that recycling will not always prove to be advantageous, Examiner agrees. However, Examiner maintains that a person having ordinary skill in the art would recognize that certain advantages can be obtained by adding an acid recycle loop to Schoubye (See 103 rejections below for details).
Applicant asserts that there is no thermodynamic advantage of acid recycling and that power consumption increases with acid recycling. Examiner acknowledges Applicant’s position on this matter and the evidentiary support for said position, as provided in the 5/28/2024 Declaration. However, Examiner maintains that acid recycling also has advantages. Namely, acid recycling can be leveraged to yield a more highly concentrated sulfuric acid product. For the reasons detailed in the 103 rejections maintained below, a person having ordinary skill in the art would recognize that acid recycling could yield such an advantage.
Considering that acid recycling yields certain benefits, the fact that it also carries certain disadvantages is not sufficient to show non-obviousness.
Regarding paragraph 8 of the declaration:
Applicant asserts that there are certain challenges and/or difficulties associated with recycling hot concentrated sulfuric acid. The fact that there are challenges and/or difficulties associated with the implementation of a particular feature is insufficient to establish non-obviousness. Indeed, almost any engineering decision is bound to bring with it certain challenges and/or difficulties.
Regarding paragraph 9 of the declaration:
Applicant asserts that, in the process of Schoubye, the desired sulfuric concentration of 98-98.8 wt% can be obtained with a single pass design, i.e. without sulfuric acid recycling. Examiner agrees that the process of Schoubye is capable of attaining a concentration of 98-98.8 wt% with a single pass.
However, as explained in the 103 rejections set forth in the previous Office Action and maintained below, Schoubye’s disclosure at least suggests that there are scenarios in which said process is not capable of attaining the maximum theoretical concentration. Specifically, Schoubye teaches that, in the process thereof, the sulfuric acid concentrator column 21 produces a concentrated sulfuric acid stream having a concentration in the range of 95-98.7% (Figure 1, claim 1, column 1 Lines 50-60, see annotated Figure 1 below). Furthermore, the teachings of Schoubye indicate that the maximal achievable concentration of sulfuric acid product is determined in part by the concentration of acid received at the top of the concentrator column (Column 3 Lines 45-62). These teachings would indicate to one of ordinary skill in the art that Schoubye’s method is only capable of achieving the theoretical azeotropic maximum
concentration in instances where certain conditions are met.
Because Schoubye is only capable of concentrating sulfuric acid to the maximum theoretical concentration under certain conditions, a person having ordinary skill in the art would recognize that a single pass design will not always be sufficient to achieve a desired concentration. For at least this reason, a person having ordinary skill in the art would expect that Schoubye would benefit from a means for further increasing the concentration of the product obtained from the sulfuric acid concentrator column 21.
It is Examiner’s understanding that Applicant attributes the ability of Schoubye concentrate sulfuric acid to 98-98.8 wt% to the notion that the initial concentration of sulfuric acid entering the concentrator 21 is “usually around 97-98%”. Examiner does not see where the disclosure of Schoubye supports the assertion that the concentration of the sulfuric acid entering the concentrator is usually 97-98 wt%. Rather, Examiner’s understanding of Schoubye is that the concentration of acid entering the concentrator 21 ranges from 92-98%, with a concentration of 94% being typical (Column 3 Lines 38-45). Regardless, it appears that Examiner and Applicant broadly agree that, the initial sulfuric acid concentration must be sufficiently high in order for Schoubye to attain a desired product concentration.
Regarding paragraph 10:
Applicant asserts that Schoubye’s disclosure indicates that increasing the flow and/or temperature of the stripping medium will allow for high product concentrations to be reached. On this basis, Applicant argues that a person having ordinary skill in the art seeking to increase the stripping capabilities of Schoubye would do so by increasing the temperature and/or flow rate of the stripping medium. Though it is not expressly stated in paragraph 10, Examiner believes that Applicant is implicitly arguing that a person having ordinary skill in the art would increase stripping medium flow rate and/or temperature instead of implementing a recycle loop.
Examiner agrees that Schoubye teaches or at least suggests that stripping capabilities can be improved by increasing the flow rate and/or temperature of the stripping medium. Examiner also agrees that a person having ordinary skill in the art would have found it obvious to increase stripping medium temperature and flow rate to increase the stripping capabilities of Schoubye. However, this does not change that it would also be obvious to one of ordinary skill in the art to increase the stripping capabilities using an acid recycle loop.
Regarding paragraphs 11-12:
Applicant has argued that the purpose for recycling acid in their invention is more “to mitigate the risk of hot air bypassing the concentrator and coming into contact with polymer materials downstream of the acid concentrator which can then be damaged due to overheating”.
The fact that the inventor has recognized another advantage which would flow naturally from following the suggestion of the prior art cannot be the basis for patentability when the differences would otherwise be obvious. See Ex parte Obiaya, 227 USPQ 58, 60 (Bd. Pat. App. & Inter. 1985).
Regarding paragraphs 13-15:
Applicant has argued that reliance on Fox is improper because Fox is related to a generic stripping process wherein water is the less volatile component of the solution being stripped, whereas in Schoubye, water is the more volatile component. Applicant concludes that there is thus “no predictable guidance provided by Fox to give reason to incorporate a stripping column into Schoubye” and that “Fox can only provide guidance that is too generic; guidance that fails once the specifics of the process of Schoubye are considered. Examiner respectfully disagrees.
Regarding a person having ordinary skill in the art, MPEP 2141.03 I states the following:
“A person of ordinary skill in the art is also a person of ordinary creativity, not an automaton.” KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 421, 82 USPQ2d 1385, 1397 (2007). “[I]n many cases a person of ordinary skill will be able to fit the teachings of multiple patents together like pieces of a puzzle.” Id. At 420, 82 USPQ2d 1397. Office personnel may also take into account “the inferences and creative steps that a person of ordinary skill in the art would employ.” Id. At 418, 82 USPQ2d at 1396.
Furthermore, the test for obviousness is not that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981).
With the forgoing in mind, Examiner respectfully asserts that although Fox does not expressly teach the use of a recycle stream in any stripping process, or specifically sulfuric acid stripping processes, a person having ordinary skill in the art would nevertheless recognize the general applicability of Fox’s teachings regarding the recycle stream.
To elaborate, a person having ordinary skill in the art of distillation (which includes stripping) will recognize that in every distillation process, at least one more volatile component is separated from at least one less volatile component. Accordingly, in considering Fox’s teachings to the use of a recycle stream in a stripping process to enhance separation of water and volatile constituents achieved by a stripping column, a person having ordinary skill in the art would have at least a reasonable expectation that a recycle stream could be used in any stripping column to enhance separation between some more volatile component and some less volatile component.
In primary reference Schoubye (US 6,090,364) a stripping column (concentrating tower) 21 is used to concentrate sulfuric acid by separating at least one volatile contaminant (Figure 1, Column 3). Please note that in the context of this discussion, Examiner uses the term “at least one volatile contaminant” to refer to one or more substances which are more volatile than sulfuric acid. Though Schoubye does not explicitly teach the identity of the volatile contaminant, a person having ordinary skill in the art would recognize that the more volatile component is water. Water is understood to be more volatile than sulfuric acid as evidenced by the well-known fact that water boils at 100 °C whereas sulfuric acid boils at 337 °C. Regardless, whatever the identity of the at least one volatile contaminant, it is understood that said at least one volatile contaminant is, in fact, more volatile than sulfuric acid, as evidenced by the fact that the stripping column 21 yields a concentrated sulfuric acid stream as a liquid bottom product while discharging an off gas (which is understood to contain volatile contaminants stripped from the sulfuric acid in stripping column 21) as an overhead product in line 24/28 (Figure 1, Column 3 Lines 30-62).
Because the Schoubye’s process uses a stripping column to separate a more volatile component (the at least one volatile contaminant discussed above) from a less volatile component (sulfuric acid), the teachings of Fox would suggest to a person having ordinary skill in the art that a recycle stream could be used to enhance the separation obtained by the stripping column of Schoubye.
Regarding paragraphs 16-22:
The contents of paragraphs 16-22 appear to amount to an argument alleging additional potential drawbacks and/or pitfalls associated with the use of an acid recycle loop. The fact that there are potential drawbacks and/or pitfalls associated with the implementation of a particular feature is insufficient to establish non-obviousness. Indeed, almost any engineering decision is bound to bring with it certain potential drawbacks and/or pitfalls.
Regarding paragraph 23:
Examiner acknowledges the contents of paragraphs 1-5. No further comments on these paragraphs are considered necessary at this time.
Applicant’s arguments concerning Schoubye (see Pages 3-6 of the 9/19/2025 Remarks) have been fully considered:
Said arguments are substantially identical in scope to those set forth in paragraphs 6-12 of the declaration. Thus, said arguments are unpersuasive for substantially the same reasons described above with respect to paragraph 6-12 of the declaration.
Applicant’s arguments concerning Fox (see Page 7of the 9/19/2025 Remarks) have been fully considered:
Said arguments are substantially identical in scope to those set forth in paragraphs 13-15 of the declaration. Thus, said arguments are unpersuasive for substantially the same reasons described above with respect to paragraph 13-15 of the declaration.
Applicant’s arguments concerning Shah (see Pages 7-10 of the 9/19/2025 Remarks) have been fully considered:
Concerning the 103 rejections’ reliance on secondary reference Shah (US 3,789,902), Applicant has made the following argument (emphasis is Applicant’s):
Furthermore, an ordinarily skilled artisan would not have looked to Shah for guidance on modifying the process in Schoubye. Shah is concerned with concentrating dilute acidic solutions. Shah uses a water-heavy system, and focuses on evaporating water without forming acid mist. In stark contrast, Schoubye is concerned with concentrating very concentrated acidic solutions (with concentrations of 90% to 98% -- see Schoubye, Abstract), and thus is concerned with fine-tuning the acidity of the output with precision. An ordinarily skilled artisan would not have viewed Shah as relevant.
Examiner respectfully disagrees.
In the 103 rejections of record, Shah is merely relied upon to show that it is known in the art of sulfuric acid concentration to recycle concentrated sulfuric acid streams to concentration processes. Shah teaches a sulfuric acid concentration process wherein concentrated sulfuric acid is recycled to a concentrator (venturi concentrator) 10/11/16/17 via line 6 (abstract, Figure 1, Column 2). Accordingly, a person having ordinary skill in the art in possession of Shah’s teachings would have a reasonable expectation that a recycle stream could be successfully implemented in a sulfuric acid concentration process.
Note: Examiner is ultimately of the position that a person having ordinary skill in the art would, by default, have a reasonable expectation that a recycle stream could be successfully implemented in any concentration process absent strong evidence to the contrary. Regardless, the teachings of Shah unequivocally show that it was known in the art before Applicant’s effective filing date that a recycle stream can be successfully integrated into a sulfuric acid concentration process.
While the acid solutions in Shah and Schoubye are of different strengths, it remains that both Shah and Schoubye are directed to the concentration of sulfuric acid (Shah: Column 1 Lines 5-17; Schoubye: Column 1 Lines 50-60). There is nothing in the prior art of record which suggests that principles applicable to the concentration of sulfuric acid from dilute starting solutions would be somehow inapplicable to concentration of sulfuric acid from highly concentrated starting solutions. More specifically relevant to the rejections’ reliance on Shah, there is nothing in the prior art of record which suggests that Shah’s clear showing to the workability of recycle streams in sulfuric acid concentration processes is, in any way, inapplicable to concentration processes carried out on already highly concentrated sulfuric acid streams. Accordingly, Examiner maintains the teachings of Shah provide a reasonable expectation that a recycle stream could be successfully implemented in sulfuric acid concentration processes, including sulfuric acid concentration processes carried out on already highly concentrated sulfuric acid streams.
In view of the above, Examiner maintains that ordinarily skilled artisan would have viewed Shah as relevant, and would have looked to Shah for guidance on modifying the process in Schoubye.
Applicant’s further arguments against Shah repeat the contents of paragraphs 16-22 of the Declaration and then conclude that, “Accordingly, Shah does not provide predictable guidance to give reason to modify Schoubye in a manner to arrive at the claimed subject matter”.
Examiner finds this argument unpersuasive.
Shah is merely relied upon to show that it is known in the art of sulfuric acid concentration to recycle concentrated sulfuric acid streams to concentration processes so as to establish that a person having ordinary skill in the art in possession of Shah’s teachings would have a reasonable expectation that a recycle stream could be successfully implemented in a sulfuric acid concentration process. The arguments set forth in paragraphs 16-22 of the Declaration and reproduced in Applicant’s remarks (pages 8-10 thereof) fail to provide sufficient evidence or reasoning to the contrary.
Any additional arguments against Shah contained in the content reproduced from paragraphs 16-22 of the declaration are unpersuasive for substantially the same reason(s) described above with respect to paragraphs 16-22 of the declaration.
Applicant’s arguments made in Summary (see Page 10 of the 9/19/2025 Remarks) have been fully considered:
Applicant has argued that “Fox is inapplicable because its disclosure is far afield from the concentration of suphuric acid, and does not provide specific, meaningful guidance to predictably modify Schoubye in a manner to arrive at the presently claimed subject matter,” (page 10 of Remarks).
Examiner respectfully disagrees.
For the purposes of a 103 rejection, a reference is applicable if it is “analogous art” (see MPEP 2141.01(a)I). “A reference is analogous art to the claimed invention if: (1) the reference is from the same field of endeavor as the claimed invention (even if it addresses a different problem); or (2) the reference is reasonably pertinent to the problem faced by the inventor (even if it is not in the same field of endeavor as the claimed invention),” (MPEP 2141.01(a)I).
A particular problem with which Applicant is concerned is the use of a recycle stream to increase the concentration of a sulfuric acid product obtained from a stripping column. Evidence that Applicant is concerned with this particular problem can be found in Applicant’s Abstract which discloses the following:
In a process for increasing the sulfuric acid concentration of 90-98 wt% sulfuric acid, comprising stripping water from the sulfuric acid by contacting it with hot stripping media in a sulfuric acid concentrator column to increase the con- centration of the acid leaving the column, the concentration of the acid is increased further by recycling a fraction of the acid, which is leaving the column, through an acid recirculation loop back to the inlet of the column, and the acid is optionally heated during its passage through the acid recirculation loop.
Fox teaches a stripping column (stripping tower) 12 for removing volatile constituents (hydrocarbons) from a liquid (water) using air as a stripping gas, the column comprising a pump 32 and pipe 34 for providing a recycle stream of liquid (abstract, Figure 1, Column 2 Line 50-Column 4 Line 30). In operation of the stripping column 12, liquid is recycled/recirculated repeatedly to the top 24 of the tower 12 to “enhance separation and disposal of the volatile components,” (Figure 1, Column 3 Line 63-Column 4 Line 30). Thus, Fox teaches or at least suggests the use of a recycle stream with a stripping column for the purpose of enhancing separation in said stripping column, and consequently increasing the concentration (purity) of products obtained from said stripping column.
Though the mixture separated/concentrated in the stripping column of Fox and the mixture separated/concentrated in Applicant’s stripping column are different, both Applicant and Fox seek to enhance separation/concentration obtained from the stripping column in the same way, i.e. through the use of a recycle stream. On this basis, Fox is reasonably pertinent to the particular problem with which Applicant was concerned, i.e. to the use of a recycle stream to increase the concentration of a sulfuric acid product obtained from a stripping column. Therefore, Fox is analogous art.
Because Fox is analogous art, it is applicable to the present invention and the 103 rejections of record.
As for the allegation that Fox “does not provide specific, meaningful guidance to predictably modify Schoubye in a manner to arrive at the presently claimed subject matter,” Examiner finds this argument unpersuasive.
Regarding a person having ordinary skill in the art, MPEP 2141.03 I states the following:
“A person of ordinary skill in the art is also a person of ordinary creativity, not an automaton.” KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 421, 82 USPQ2d 1385, 1397 (2007). “[I]n many cases a person of ordinary skill will be able to fit the teachings of multiple patents together like pieces of a puzzle.” Id. At 420, 82 USPQ2d 1397. Office personnel may also take into account “the inferences and creative steps that a person of ordinary skill in the art would employ.” Id. At 418, 82 USPQ2d at 1396.
Furthermore, the test for obviousness is not that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981).
With the forgoing in mind, Examiner respectfully asserts that although Fox does not expressly teach the use of a recycle stream in any stripping process, or specifically sulfuric acid stripping processes, a person having ordinary skill in the art would nevertheless recognize the general applicability of Fox’s teachings regarding the recycle stream. Thus, to a person having ordinary skill in the art, Fox would provide sufficient guidance to allow said person to predictably modify Schoubye in a manner to arrive at the presently claimed subject matter.
Applicant has argued that “Shah is inapplicable to the concentration of suphuric acid in non-dilute acidic solutions, and is not analogous to the present invention,” (page 10 of Remarks). Examiner respectfully disagrees.
“A reference is analogous art to the claimed invention if: (1) the reference is from the same field of endeavor as the claimed invention (even if it addresses a different problem); or (2) the reference is reasonably pertinent to the problem faced by the inventor (even if it is not in the same field of endeavor as the claimed invention),” (MPEP 2141.01(a)I).
In this case, Shah is Applicant’s field of endeavor, said field of endeavor being the concentration of sulfuric acid.
In addition, Shah is reasonably pertinent to a particular problem faced by Applicant. A particular problem with which Applicant is concerned is the use of a recycle stream to increase the concentration of a sulfuric acid product obtained from a stripping column. Evidence that Applicant is concerned with this particular problem can be found in Applicant’s Abstract which discloses the following:
In a process for increasing the sulfuric acid concentration of 90-98 wt% sulfuric acid, comprising stripping water from the sulfuric acid by contacting it with hot stripping media in a sulfuric acid concentrator column to increase the con- centration of the acid leaving the column, the concentration of the acid is increased further by recycling a fraction of the acid, which is leaving the column, through an acid recirculation loop back to the inlet of the column, and the acid is optionally heated during its passage through the acid recirculation loop.
Shah is drawn to a process for the concentration of sulfuric acid wherein the process makes use of a recycle stream 6 of concentrated sulfuric acid (abstract, Column 2). Though it is not explicitly taught, it is understood that by providing the recycle stream 6 of concentrated sulfuric acid, the process of Shah will yield a sulfuric acid product having a concentration higher than that which would be obtained were the recycle stream 6 omitted.
Because the particular problem with which Applicant is concerned involves the concentration of sulfuric acid, the fact that Shah relates to the concentration of sulfuric acid, on its own, makes Shah reasonably pertinent to the problem faced by Applicant.
Regardless, the particular problem with which Applicant is concerned is specifically the use of a recycle stream to increase the concentration of a sulfuric acid product obtained from a stripping column. Shah is drawn to a sulfuric acid concentration process which makes use of a concentrated sulfuric acid recycle stream and therefore, is reasonably pertinent to the particular problem faced by Applicant.
Because Shah is analogous art, it is applicable to the present invention and the 103 rejections of record.
Examiner Acknowledges Applicant’s position that Shah is inapplicable/nonanalogous on the basis that Shah concentrates a sulfuric acid which is less concentrated than that concentrated by Applicant’s invention. Examiner respectfully disagrees and maintains that Shah is analogous art, and thus applicable, for all of the reasons discussed above.
Applicant has argued that “Schoubye does not otherwise provide motivation for modification to yield the same subject matter wherein "a fraction of the sulfuric acid product stream is recycled back to a position upstream of the column via an acid recirculation loop," (page 10 of Remarks).
Examiner understands this as an argument that there is no motivation in the prior art of record to modify Schoubye so as to make use of a recycle stream, and that the rejections’ conclusion that there is motivation to modify Schoubye is made solely on the basis of impermissible hindsight.
Examiner respectfully disagrees.
It has been established that an explicit teaching of a motivation to modify (combine) is not required to establish a Prima Facie Case of obviousness (see MPEP 2143 and MPEP 21143.01). The examiner recognizes that obviousness may be established by combining or modifying the teachings of the prior art to produce the claimed invention where there is some teaching, suggestion, or motivation to do so found either in the references themselves or in the knowledge generally available to one of ordinary skill in the art. See In re Fine, 837 F.2d 1071, 5 USPQ2d 1596 (Fed. Cir. 1988), In re Jones, 958 F.2d 347, 21 USPQ2d 1941 (Fed. Cir. 1992), and KSR International Co. v. Teleflex, Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007).
In this case, A person having ordinary skill in the art would be motived to modify Schoubye to make use of the recycle stream in order to “obtain a method wherein the sulfuric acid concentrator column is better able to yield a highly concentrated sulfuric acid product, i.e. a method wherein the sulfuric acid concentrator column is able to yield sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % across a wider range of embodiments,” (page 6 of the 9/17/2024 Non-Final Rejection). Put differently, a person having ordinary skill in the art would be motivated to modify Schoubye so as to make use of a recycle stream out of a desire to improve the stripping column 21 with respect to its ability to concentrate sulfuric acid. Said motivation can be found implicitly in the combined disclosures of Schoubye, Fox, and Shah.
To elaborate, in any process of concentrating a target substance there exists implicit motivation to concentrate the target substance to the maximum extent possible (absent any clear teaching or suggestion to the contrary). The disclosure of Schoubye provides clear indication that the maximum concentration of sulfuric acid which can be obtained with the stripping column 21 is the “theoretical, azeotropic maximum of 98.7-98.8% H2SO4” (Column 3 lines 59-62). Schoubye does not provide any clear teaching or suggestion that one should intentionally avoid concentrating the sulfuric acid to the theoretical, azeotropic maximum of 98.7-98.8%. On the contrary, Schoubye clearly envisions embodiments wherein the sulfuric acid is concentrated to 98.8% (abstract, claim 1). Therefore, a person ordinary skill in the art would find implicit motivation in the disclosure of Schoubye to concentrate the sulfuric acid to the “theoretical, azeotropic maximum of 98.7-98.8% H2SO4”.
As discussed in the 103 rejections maintained below, Schoubye teaches that the sulfuric acid concentrator column 21 produces a concentrated sulfuric acid stream having a concentration in the range of 95-98.7% (Figure 1, claim 1, column 1 Lines 50-60, see annotated Figure 1 below). The teachings of Schoubye further indicate that the maximal achievable concentration of sulfuric acid product is determined in part by the concentration of acid received at the top of the concentrator column (Column 3 Lines 45-62). These teachings of Schoubye at least suggest that, in some embodiments of Schoubye’s process, e.g. when sulfuric acid concentration the concentration of stream 22 fed to the stripping column 21 is lower than a certain threshold, the stripping column 21 is incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 %. Because a person ordinary skill in the art would find implicit motivation in the disclosure of Schoubye to concentrate the sulfuric acid to the theoretical, azeotropic maximum, the suggestion that Schoubye’s process is, in some embodiments, incapable of achieving the azeotropic maximum would further motivate a person having ordinary skill in the art to improve the process of Schoubye such that it were capable of yielding maximally concentrated sulfuric acid across a wider range of embodiments.
Fox teaches a stripping column (stripping tower) 12 for removing volatile constituents (hydrocarbons) from a liquid (water) using air as a stripping gas, the column comprising a pump 32 and pipe 34 for providing a recycle stream of liquid (abstract, Figure 1, Column 2 Line 50-Column 4 Line 30). In operation of the stripping column 12, liquid is recycled/recirculated repeatedly to the top 24 of the tower 12 to “enhance separation and disposal of the volatile components,” (Figure 1, Column 3 Line 63-Column 4 Line 30).
Shah teaches a sulfuric acid concentration process wherein concentrated sulfuric acid recycle stream is recycled to a concentrator (venturi concentrator) 10/11/16/17 via line 6 (abstract, Figure 1, Column 2).
The combined teachings of Fox and Shah would give a person having ordinary skill in the art a reasonable expectation that the concentrator column 21 of Schoubye could be successfully provided with a recycle stream for the purpose of improving the concentrator column’s ability to yield highly concentrated sulfuric acid product.
As discussed above, the disclosure of Schoubye would motivate a person having ordinary skill in the art to improve the process of Schoubye such that it were capable of yielding maximally concentrated sulfuric acid across a wider range of embodiments. Because a person having ordinary skill in the art would be so motivated by the disclosure of Schoubye, and because the combined teachings of Fox and Shah would give a person having ordinary skill in the art a reasonable expectation that the concentrator column 21 of Schoubye could be improved by providing it with a recycle stream, the combination of Schoubye, Fox, and Shah would motivate one of ordinary skill in the art to provide the concentrator column 21 of Schoubye with a recycle stream.
As for the allegation that the 103 rejections’ conclusion that there is motivation to modify Schoubye is made solely on the basis of impermissible hindsight, Examiner respectfully disagrees.
It must be recognized that any judgment on obviousness is in a sense necessarily a reconstruction based upon hindsight reasoning. But so long as it takes into account only knowledge which was within the level of ordinary skill at the time the claimed invention was made, and does not include knowledge gleaned only from the applicant's disclosure, such a reconstruction is proper. See In re McLaughlin, 443 F.2d 1392, 170 USPQ 209 (CCPA 1971).
Examiner respectfully asserts that the 103 rejections over Schoubye in view of Fox and Shah only take into account knowledge which was made expressly available by the teachings of Schoubye, Fox, and Shah and knowledge which a person having ordinary skill in the art would have gleaned from the combined teachings of Schoubye, Fox, and Shah. Said rejections do not rely on any knowledge which can only be gleaned from Applicant’s disclosure.
With respect to the motivation for modifying Schoubye to include a recycle stream, it is believed that forgoing discussion regarding the source of said motivation shows how one of ordinary skill in the art would have gleaned such motivation from the combined teachings of Schoubye, Fox, and Shah, thereby establishing that said motivation was within the level of ordinary skill at the time the claimed invention was made.
Applicant’s arguments concerning the dependent claims (see Page 11 of the 9/19/2025 Remarks) have been fully considered:
Applicant has argued that the dependent claims are allowable over the prior art for the same alleged reasons as the independent claims. This argument is moot, as the independent claims are not presently allowable over the prior art.
Claim Interpretation
Claim 21 recites “wherein the sulfuric acid concentrator column is an Integrated Sulfuric Acid Concentrator.” On the topic of an “Integrated Sulfuric Acid Concentrator”, Applicant’s disclosure recites the following:
“Another solution, which can be used to increase the concentration of the product acid from a wet-type sulfuric acid plant, is to include a so-called Integrated Sulfuric Acid Concentrator (ISAC) in the design of the sulfuric acid plant. The ISAC can be mounted at the liquid outlet of the sulfuric acid condenser, in which sulfuric acid condenses from the gas phase by direct or indirect cooling of the process gas containing sulfuric acid and water vapor,” (paragraph [0009] of published application, i.e. PG Pub US 2020/0062594).
“’Integrated’ means that the liquid inlet of the ISAC is in fluid communication with the liquid outlet of the sulfuric acid condenser, and the hot air leaving the ISAC column is in contact with the gas inlet to the sulfuric acid condenser,” (paragraph [0010] of published application, i.e. PG Pub US 2020/0062594).
Thus, the claimed term “Integrated Sulfuric Acid Concentrator” has been interpreted as a sulfuric acid concentrator column that is in fluid communication with a liquid outlet of a sulfuric acid condenser and disposed such that stripping gas exiting the concentrator column enters the sulfuric acid condenser.
The rejections are maintained from the previous Office Action.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claim(s) 1, 4-12, and 18-22 is/are rejected under 35 U.S.C. 103 as being unpatentable over Schoubye (US 6,090,364) in view of Fox (US 5,259,931) and Shah et al. (US 3,789,902), hereafter referred to as Shah.
With regard to claim 1: Schoubye teaches a process for increasing the concentration of sulfuric acid in a sulfuric acid feed stream 22, wherein the sulfuric acid feed stream is already concentrated (Figure 1, Column 3 Lines 10-62), the process comprising:
A step of stripping water from the sulfuric acid feed stream 22 by contacting the sulfuric acid feed stream with a stripping media in a sulfuric acid concentrator column 21 to increase a concentration of a sulfuric acid product stream leaving the column 21 (Figure 1, Column 3 Lines 10-62).
Wherein the stripping media is air (Figure 1, Column 3 Lines 10-62).
Schoubye is silent to a fraction of the sulfuric acid product stream column 21 being recycled back to a position upstream of the column via an acid recirculation loop.
However, it is known in the art to provide concentrator columns with a recycle stream in order to increase the concentration of a product obtained from said column. For example, Fox teaches a stripping column (stripping tower) 12 for removing volatile constituents (hydrocarbons) from a liquid (water) using air as a stripping gas, the column comprising a pump 32 and pipe 34 for providing a recycle stream of liquid (abstract, Figure 1, Column 2 Line 50-Column 4 Line 30). In operation of the stripping column 12, liquid is recycled/recirculated repeatedly to the top 24 of the tower 12 to “enhance separation and disposal of the volatile components,” (Figure 1, Column 3 Line 63-Column 4 Line 30).
Furthermore, it is known in the art of sulfuric acid concentration to recycle concentrated sulfuric acid streams to concentration processes. For example, Shah teaches a sulfuric acid concentration process wherein concentrated sulfuric acid is recycled to a concentrator (venturi concentrator) 10/11/16/17 via line 6 (abstract, Figure 1, Column 2).
In addition, the disclosure of Schoubye would suggest to one of ordinary skill in the art that, in at least some embodiments, the process of Schoubye would benefit from a means for further increasing the concentration of the product obtained from the sulfuric acid concentrator column 21. Specifically, Schoubye teaches that, in the process thereof, the sulfuric acid concentrator column 21 produces a concentrated sulfuric acid stream having a concentration in the range of 95-98.7% (Figure 1, claim 1, column 1 Lines 50-60, see annotated Figure 1 below). By this teaching, Schoubye at least suggests that some embodiments of the process therein are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % (see Column 3 Lines 59-62 of Schoubye).
Further still, the teachings of Schoubye indicate that the maximal achievable concentration of sulfuric acid product is determined in part by the concentration of acid received at the top of the concentrator column (Column 3 Lines 45-62). These teachings would indicate to one of ordinary skill in the art that Schoubye’s method is only capable of achieving the theoretical azeotropic maximum concentration in instances where certain conditions are met. Thus, said teachings would at least reinforce the suggestion that Schoubye’s method has embodiments which are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 %.
In view of the above, a person having ordinary skill in the art would have a reasonable expectation that: i) the concentrator column 21 of Schoubye could be successfully provided with a recycle stream for the purpose of improving the concentrator column’s ability to yield highly concentrated sulfuric acid product; and ii) the concentrator column 21 in Schoubye would benefit from the inclusion of such a recycle stream.
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It would have been obvious to one of ordinary skill in the art before the effective filing date to modify Schoubye in view of Fox and Shah by adding a step of recycling, via an acid recirculation loop, a fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mixing it with the sulfuric acid feed stream 22 before it enters the column 21, in order to obtain a method wherein the sulfuric acid concentrator column is better able to yield a highly concentrated sulfuric acid product, i.e. a method wherein the sulfuric acid concentrator column is able to yield sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % across a wider range of embodiments.
Modified Schoubye is silent to the embodiment relied upon (i.e. that of Figure 1) using a process gas comprising water and sulfur trioxide as the stripping medium.
However, Schoubye teaches that hot process gas comprising water and sulfur trioxide can be used as the stripping medium in the alternative to air (abstract, Column 2 Lines 28-55, Figure 2, Column 3 Line 63-Column 4 Line 5). This teaching by Schoubye would give a person having ordinary skill in the art a reasonable expectation that the stripping medium could be replaced with a stripping medium in the form of a process gas comprising water and sulfur trioxide as the stripping medium. Furthermore, it can be seen from the embodiment of Figure 2 in Schoubye, which is an embodiment which uses such a process gas, that the process gas 33/34 need not be heated by a heater after exiting the reactor 32 and prior to entering the concentrator column 21 (Figure 2, Column 3 Line 63-Column 4 Line 5). This would suggest to one of ordinary skill in the art that using such a process gas could save energy by circumventing the need for heating an incoming air stream to the temperatures required for use as the stripping media.
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye by using a process gas comprising water and sulfur trioxide, in order to obtain a predictably functional method in accordance with the suggestions of Schoubye, and in order to obtain a method which saves energy by circumventing the need to heat an incoming air stream for use as the stripping media.
With regard to claim 4: Modified Schoubye is silent to the process gas used for stripping having a water concentration that is no greater than 4.5% higher than the concentration of sulfur trioxide in said stream.
However, Schoubye teaches that “the strength of the concentrated acid that can be obtained in the evaporating tower is limited by the content of water vapor in the hot gas used for the concentration,” (column 2 Lines 48-50). This teaching would serve as a clear indication to one of ordinary skill in the art that 1) the water content in the stripping media is a result effective variable, and 2) the water content in the stripping media is preferably as low as possible. "[When] the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation," (see MPEP 2144.05 II A).
Furthermore, Schoubye teaches that it is not preferable to use the process gas as the stripping medium when the gas contains more than about 5% water after hydration of its content of SO3 into sulfuric acid vapor (Column 2 Lines 50-55). This disclosure would suggest to one of ordinary skill in the art that, if the process gas is to be used as the stripping media, the water content of the process gas should be no more than 5% greater than the sulfur trioxide content thereof. The claimed water content of a concentration no greater than 4.5% higher than the concentration of sulfur trioxide lies within the suggested water content range of no more than 5% greater than the sulfur trioxide content.
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye by optimizing the water content of the process gas used as the stripping media to be no more than 4.5% greater than the concentration of sulfur trioxide in said process gas, in order to obtain a process gas which has a desirably low content of water, wherein said desirably low content of water is low enough to make said process gas desirable for use as the stripping medium in accordance with the suggestions of Schoubye.
With regard to claims 6 and 7: Modified Schoubye is silent to the fraction of the sulfuric acid product stream being heated to a temperature of 200-270 °C by heat exchange during its passage through the acid recirculation loop.
Modified Schoubye is silent to the recirculation loop comprising an acid heater configured to heat the fraction of the sulfuric acid product stream to a temperature of 200-270 °C.
However, a person having ordinary skill in the art would recognize that temperature conditions (including but not limited to feed temperature) are result effective variables in vapor liquid separations such as the stripping carried out in the concentrator column 21 of Schoubye. In particular, a person having ordinary skill in the art would recognize that if temperature conditions in a vapor liquid separation process such as stripping are too high or too low, then the necessary vapor liquid equilibrium conditions within the process will not be achieved, nor will the desired separation(s). Therefore, a person having ordinary skill in the art would recognize that the temperature of the feed to the concentration column of Schoubye is a result effective variable.
As discussed in the rejection of claim 1 above, the fraction of the sulfuric acid product stream leaving the column and being recirculated through the recirculation loop is combined with the sulfuric acid feed stream 22. Said sulfuric acid feed stream 22 has a temperature of 180-270°C (Schoubye: Figure 1, Column 3 Lines 10-62). A person having ordinary skill in the art would recognize that, when recirculating the fraction of the sulfuric acid product stream, said recirculated fraction, when combined with the sulfuric acid feed stream 22 will affect the temperature of the feed to the concentrator column 21, i.e. if the temperature of the recirculated fraction is higher or lower than the feed stream 22, then upon mixing, it will raise or lower the temperature of said feed stream, thus altering the temperature of the feed to the concentrator column 21. Because a person having ordinary skill in the art would recognize that: 1) the temperature of the feed to the concentrator column 21 is a result effective variable, and 2) the temperature of the recirculated fraction will affect the temperature of the feed to the concentrator column 21, a person having ordinary skill in the art would further recognize that the temperature of the recirculated fraction is a result effective variable as well. In particular, a person having ordinary skill in the art would recognize that, when recirculating the fraction of the sulfuric acid product stream, said fraction would need to be brought to the same temperature as the sulfuric acid feed stream 22 in order to ensure that the feed to the concentration column 21 maintains the temperature conditions taught in base Schoubye. "[When] the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation," (see MPEP 2144.05 II A).
Furthermore, the sulfuric acid product stream leaving the concentrator column 21 is cooled by the cooler 27 (Schoubye: Figure 1, Column 3 Lines 10-62). This would indicate to one of ordinary skill in the art that the fraction of the sulfuric acid product stream leaving the column and being recirculated through the recirculation loop would need to be heated during its recirculation to be brought to the same temperature as the sulfuric acid feed stream 22, i.e. said fraction would need to be heated to a temperature of 180-270 °C to be brought to the same temperature as the sulfuric acid feed stream 22. It is noted that the claimed temperature range to which the fraction is heated (200-270 °C) lies inside the taught temperature range for the sulfuric acid feed stream. “In the case where the claimed ranges ‘overlap or lie inside ranges disclosed by the prior art’ a prima facie case of obviousness exists,” (MPEP 2144.05 I).
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye by providing the acid recirculation loop with a heater configured to heat the fraction of the sulfuric acid product stream to a temperature of 200-270 °C by heat exchange during its passage through the acid recirculation loop, in order to heat said fraction to a temperature equal to that of the sulfuric acid feed stream 22, so as to maintain the temperature conditions of the feed to the concentrator column within the range taught to be acceptable by base Schoubye.
With regard to claim 8: The sulfuric acid feed stream 22 is a condenser effluent, i.e. an effluent from condenser 15 (Schoubye: Figure 1, Column 3 Lines 10-62).
With regard to claim 9: The concentration of the sulfuric acid feed stream 22 is 92-98 wt% (Schoubye: Figure 1).
With regard to claim 10: The concentration of the sulfuric acid product stream leaving the column is 95-98.7 wt% (Schoubye: Figure 1).
Modified Schoubye is silent to the concentration of the sulfuric acid product stream leaving the column being 95-98.6 wt%.
However, said claimed concentration range lies within the range of concentrations for the sulfuric acid product stream leaving the column as taught by Schoubye. Furthermore, said claimed range is nearly identical to that taught by Schoubye, i.e. the claimed range differs from the taught range only in that the upper limit of the claimed range is 0.1 wt% lower than the taught range. “In the case where the claimed ranges ‘overlap or lie inside ranges disclosed by the prior art’ a prima facie case of obviousness exists,” (MPEP 2144.05 I).
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye by carrying out the process so as to obtain a sulfuric acid product leaving the column having a concentration in the range of 95-98.6 wt%, in order to obtain a predictably functional method which produces a sulfuric acid product (i.e. a sulfuric acid product stream leaving the column) having a concentration in accordance with the sulfuric acid product concentration taught by Schoubye.
With regard to claim 11: Modified Schoubye is silent to the fraction of the sulfuric acid product stream being fed directly to a liquid distributor in the sulfuric acid concentrator column.
However, a person having ordinary skill in the art would recognize that, in order to mix the recirculated fraction with the sulfuric acid feed stream 22 as discussed in the rejection of claim 1 above, said fraction would need to be fed into a portion of the system containing the flow of said sulfuric acid feed stream. A person having ordinary skill in the art would recognize that the portions of Schoubye which contain the flow of said already concentrated sulfuric acid are: the bottom of the condenser 15 from which said sulfuric acid feed stream 22 originates, the liquid distributor within the concentrator column 21 for distributing the sulfuric acid feed stream 22 therein (said distributor is pictured in Figure 1 at the top of the concentrator column 21), and the pipes/conduits connecting the bottom of the condenser 15 to said distributor (Schoubye: Figure 1, Column 3 Lines 10-62).
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye by configuring the recirculation loop to feed the fraction of the sulfuric acid product stream directly to the liquid distributor in the sulfuric acid concentrator column 21, in order to feed said fraction to a location containing the flow of the sulfuric acid feed stream 22, so as to successfully combine said streams for feeding into the concentrator column.
With regard to claim 12: Modified Schoubye is silent to the fraction of the sulfuric acid product stream being fed to a bottom of the sulfuric acid condenser.
However, a person having ordinary skill in the art would recognize that, in order to mix the recirculated fraction with the sulfuric acid feed stream 22 as discussed in the rejection of claim 1 above, said fraction would need to be fed into a portion of the system containing the flow of said sulfuric acid feed stream. A person having ordinary skill in the art would recognize that the portions of Schoubye which contain the flow of said already concentrated sulfuric acid are: the bottom of the condenser 15 from which said sulfuric acid feed stream 22 originates, the liquid distributor within the concentrator column 21 for distributing the sulfuric acid feed stream 22 therein (said distributor is pictured in Figure 1 at the top of the concentrator column 21), and the pipes/conduits connecting the bottom of the condenser 15 to said distributor (Schoubye: Figure 1, Column 3 Lines 10-62).
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye by configuring the recirculation loop to feed the fraction of the sulfuric acid product stream to the bottom of the condenser 15, in order to feed said fraction to a location containing the flow of the sulfuric acid feed stream 22, so as to successfully combine said streams for feeding into the concentrator column.
With regard to claim 18: The concentration of the sulfuric acid product stream leaving the column is 95-98.7 wt% (Schoubye: Figure 1).
With regard to claim 5: Schoubye teaches a process for increasing the concentration of sulfuric acid in a sulfuric acid feed stream 22, wherein the sulfuric acid feed stream is already concentrated (Figure 1, Column 3 Lines 10-62), the process comprising:
A step of stripping water from the sulfuric acid feed stream 22 by contacting the sulfuric acid feed stream with a stripping media in a sulfuric acid concentrator column 21 to increase a concentration of a sulfuric acid product stream leaving the column 21 (Figure 1, Column 3 Lines 10-62).
Wherein the stripping media is air (Figure 1, Column 3 Lines 10-62).
And wherein the stripping media has a temperature of 350-700 °C (Figure 1, Column 3 Lines 10-62), which anticipates the claimed temperature range of 350-700 °C.
Schoubye is silent to a fraction of the sulfuric acid product stream column 21 being recycled back to a position upstream of the column via an acid recirculation loop.
However, it is known in the art to provide concentrator columns with a recycle stream in order to increase the concentration of a product obtained from said column. For example, Fox teaches a stripping column (stripping tower) 12 for removing volatile constituents (hydrocarbons) from a liquid (water) using air as a stripping gas, the column comprising a pump 32 and pipe 34 for providing a recycle stream of liquid (abstract, Figure 1, Column 2 Line 50-Column 4 Line 30). In operation of the stripping column 12, liquid is recycled/recirculated repeatedly to the top 24 of the tower 12 to “enhance separation and disposal of the volatile components,” (Figure 1, Column 3 Line 63-Column 4 Line 30).
Furthermore, it is known in the art of sulfuric acid concentration to recycle concentrated sulfuric acid streams to concentration processes. For example, Shah teaches a sulfuric acid concentration process wherein concentrated sulfuric acid is recycled to a concentrator (venturi concentrator) 10/11/16/17 via line 6 (abstract, Figure 1, Column 2).
In addition, the disclosure of Schoubye would suggest to one of ordinary skill in the art that, in at least some embodiments, the process of Schoubye would benefit from a means for further increasing the concentration of the product obtained from the sulfuric acid concentrator column 21. Specifically, Schoubye teaches that, in the process thereof, the sulfuric acid concentrator column 21 produces a concentrated sulfuric acid stream having a concentration in the range of 95-98.7% (Figure 1, claim 1, column 1 Lines 50-60, see annotated Figure 1 below). By this teaching, Schoubye at least suggests that some embodiments of the process therein are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % (see Column 3 Lines 59-62 of Schoubye).
Further still, the teachings of Schoubye indicate that the maximal achievable concentration of sulfuric acid product is determined in part by the concentration of acid received at the top of the concentrator column (Column 3 Lines 45-62). These teachings would indicate to one of ordinary skill in the art that Schoubye’s method is only capable of achieving the theoretical azeotropic maximum concentration in instances where certain conditions are met. Thus, said teachings would at least reinforce the suggestion that Schoubye’s method has embodiments which are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 %.
In view of the above, a person having ordinary skill in the art would have a reasonable expectation that: i) the concentrator column 21 of Schoubye could be successfully provided with a recycle stream for the purpose of improving the concentrator column’s ability to yield highly concentrated sulfuric acid product; and ii) the concentrator column 21 in Schoubye would benefit from the inclusion of such a recycle stream.
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It would have been obvious to one of ordinary skill in the art before the effective filing date to modify Schoubye in view of Fox and Shah by adding a step of recycling, via an acid recirculation loop, a fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mixing it with the sulfuric acid feed stream 22 before it enters the column 21, in order to obtain a method wherein the sulfuric acid concentrator column is better able to yield a highly concentrated sulfuric acid product, i.e. a method wherein the sulfuric acid concentrator column is able to yield sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % across a wider range of embodiments.
With regard to claim 19: Schoubye teaches a process for increasing the concentration of sulfuric acid in a sulfuric acid feed stream 22, wherein the sulfuric acid feed stream is already concentrated (Figure 1, Column 3 Lines 10-62), the process comprising:
A step of stripping water from the sulfuric acid feed stream 22 by contacting the sulfuric acid feed stream with a stripping media in a sulfuric acid concentrator column 21 to increase a concentration of a sulfuric acid product stream leaving the column 21 (Figure 1, Column 3 Lines 10-62).
Wherein the stripping media is air (Figure 1, Column 3 Lines 10-62).
Schoubye is silent to a fraction of the sulfuric acid product stream column 21 being recycled back to a position upstream of the column via an acid recirculation loop.
However, it is known in the art to provide concentrator columns with a recycle stream in order to increase the concentration of a product obtained from said column. For example, Fox teaches a stripping column (stripping tower) 12 for removing volatile constituents (hydrocarbons) from a liquid (water) using air as a stripping gas, the column comprising a pump 32 and pipe 34 for providing a recycle stream of liquid (abstract, Figure 1, Column 2 Line 50-Column 4 Line 30). In operation of the stripping column 12, liquid is recycled/recirculated repeatedly to the top 24 of the tower 12 to “enhance separation and disposal of the volatile components,” (Figure 1, Column 3 Line 63-Column 4 Line 30).
Furthermore, it is known in the art of sulfuric acid concentration to recycle concentrated sulfuric acid streams to concentration processes. For example, Shah teaches a sulfuric acid concentration process wherein concentrated sulfuric acid is recycled to a concentrator (venturi concentrator) 10/11/16/17 via line 6 (abstract, Figure 1, Column 2).
In addition, the disclosure of Schoubye would suggest to one of ordinary skill in the art that, in at least some embodiments, the process of Schoubye would benefit from a means for further increasing the concentration of the product obtained from the sulfuric acid concentrator column 21. Specifically, Schoubye teaches that, in the process thereof, the sulfuric acid concentrator column 21 produces a concentrated sulfuric acid stream having a concentration in the range of 95-98.7% (Figure 1, claim 1, column 1 Lines 50-60, see annotated Figure 1 below). By this teaching, Schoubye at least suggests that some embodiments of the process therein are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % (see Column 3 Lines 59-62 of Schoubye).
Further still, the teachings of Schoubye indicate that the maximal achievable concentration of sulfuric acid product is determined in part by the concentration of acid received at the top of the concentrator column (Column 3 Lines 45-62). These teachings would indicate to one of ordinary skill in the art that Schoubye’s method is only capable of achieving the theoretical azeotropic maximum concentration in instances where certain conditions are met. Thus, said teachings would at least reinforce the suggestion that Schoubye’s method has embodiments which are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 %.
In view of the above, a person having ordinary skill in the art would have a reasonable expectation that: i) the concentrator column 21 of Schoubye could be successfully provided with a recycle stream for the purpose of improving the concentrator column’s ability to yield highly concentrated sulfuric acid product; and ii) the concentrator column 21 in Schoubye would benefit from the inclusion of such a recycle stream.
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It would have been obvious to one of ordinary skill in the art before the effective filing date to modify Schoubye in view of Fox and Shah by adding a step of recycling, via an acid recirculation loop, a fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mixing it with the sulfuric acid feed stream 22 before it enters the column 21, in order to obtain a method wherein the sulfuric acid concentrator column is better able to yield a highly concentrated sulfuric acid product, i.e. a method wherein the sulfuric acid concentrator column is able to yield sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % across a wider range of embodiments.
Modified Schoubye does not explicitly teach that the striping media air has a water concentration of below 0.8%.
However, Schoubye does that “the strength of the concentrated acid that can be obtained in the evaporating tower is limited by the content of water vapor in the hot gas used for the concentration,” (column 2 Lines 48-50). This teaching would serve as a clear indication to one of ordinary skill in the art that 1) the water content in the stripping media is a result effective variable, and 2) the water content in the stripping media is preferably as low as possible. "[When] the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation," (see MPEP 2144.05 II A).
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye by utilizing as the stripping media air, air that has a water concentration below 0.8%, in order to obtain a method wherein the water content in the stripping media is very low so as not to limit the strength of the concentrated acid that can be obtained.
With regard to claim 20: By virtue of having such a low water content, i.e. below 0.8% as described in the 103 rejection of claim 19 above, the air in modified Schoubye is necessarily “dried air”.
With regard to claim 21: Schoubye teaches a process for increasing the concentration of sulfuric acid in a sulfuric acid feed stream 22, wherein the sulfuric acid feed stream is already concentrated (Figure 1, Column 3 Lines 10-62), the process comprising:
A step of stripping water from the sulfuric acid feed stream 22 by contacting the sulfuric acid feed stream with a stripping media in a sulfuric acid concentrator column 21 to increase a concentration of a sulfuric acid product stream leaving the column 21 (Figure 1, Column 3 Lines 10-62).
Wherein the stripping media is air (Figure 1, Column 3 Lines 10-62).
And wherein the sulfuric acid concentrator is an Integrated Sulfuric Acid Concentrator, i.e. a sulfuric acid concentrator column that is in fluid communication with a liquid outlet of a sulfuric acid condenser 15 via the line containing the sulfuric acid feed stream and is disposed such that stripping gas exiting the concentrator column 21 enters the sulfuric acid condenser 15 via lines 28, 24, and 14 (Figure 1, Column 3 Lines 10-62).
Schoubye is silent to a fraction of the sulfuric acid product stream column 21 being recycled back to a position upstream of the column an acid recirculation loop.
However, it is known in the art to provide concentrator columns with a recycle stream in order to increase the concentration of a product obtained from said column. For example, Fox teaches a stripping column (stripping tower) 12 for removing volatile constituents (hydrocarbons) from a liquid (water) using air as a stripping gas, the column comprising a pump 32 and pipe 34 for providing a recycle stream of liquid (abstract, Figure 1, Column 2 Line 50-Column 4 Line 30). In operation of the stripping column 12, liquid is recycled/recirculated repeatedly to the top 24 of the tower 12 to “enhance separation and disposal of the volatile components,” (Figure 1, Column 3 Line 63-Column 4 Line 30).
Furthermore, it is known in the art of sulfuric acid concentration to recycle concentrated sulfuric acid streams to concentration processes. For example, Shah teaches a sulfuric acid concentration process wherein concentrated sulfuric acid is recycled to a concentrator (venturi concentrator) 10/11/16/17 via line 6 (abstract, Figure 1, Column 2).
In addition, the disclosure of Schoubye would suggest to one of ordinary skill in the art that, in at least some embodiments, the process of Schoubye would benefit from a means for further increasing the concentration of the product obtained from the sulfuric acid concentrator column 21. Specifically, Schoubye teaches that, in the process thereof, the sulfuric acid concentrator column 21 produces a concentrated sulfuric acid stream having a concentration in the range of 95-98.7% (Figure 1, claim 1, column 1 Lines 50-60, see annotated Figure 1 below). By this teaching, Schoubye at least suggests that some embodiments of the process therein are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % (see Column 3 Lines 59-62 of Schoubye).
Further still, the teachings of Schoubye indicate that the maximal achievable concentration of sulfuric acid product is determined in part by the concentration of acid received at the top of the concentrator column (Column 3 Lines 45-62). These teachings would indicate to one of ordinary skill in the art that Schoubye’s method is only capable of achieving the theoretical azeotropic maximum concentration in instances where certain conditions are met. Thus, said teachings would at least reinforce the suggestion that Schoubye’s method has embodiments which are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 %.
In view of the above, a person having ordinary skill in the art would have a reasonable expectation that: i) the concentrator column 21 of Schoubye could be successfully provided with a recycle stream for the purpose of improving the concentrator column’s ability to yield highly concentrated sulfuric acid product; and ii) the concentrator column 21 in Schoubye would benefit from the inclusion of such a recycle stream.
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It would have been obvious to one of ordinary skill in the art before the effective filing date to modify Schoubye in view of Fox and Shah by adding a step of recycling, via an acid recirculation loop, a fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mixing it with the sulfuric acid feed stream 22 before it enters the column 21, in order to obtain a method wherein the sulfuric acid concentrator column is better able to yield a highly concentrated sulfuric acid product, i.e. a method wherein the sulfuric acid concentrator column is able to yield sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % across a wider range of embodiments.
Modified Schoubye is silent to the embodiment relied upon (i.e. that of Figure 1) using a process gas comprising water and sulfur trioxide as the stripping medium.
However, Schoubye teaches that hot process gas comprising water and sulfur trioxide can be used as the stripping medium in the alternative to air (abstract, Column 2 Lines 28-55, Figure 2, Column 3 Line 63-Column 4 Line 5). This teaching by Schoubye would give a person having ordinary skill in the art a reasonable expectation that the stripping medium could be replaced with a stripping medium in the form of a process gas comprising water and sulfur trioxide as the stripping medium. Furthermore, it can be seen from the embodiment of Figure 2 in Schoubye, which is an embodiment which uses such a process gas, that the process gas 33/34 need not be heated by a heater after exiting the reactor 32 and prior to entering the concentrator column 21 (Figure 2, Column 3 Line 63-Column 4 Line 5). This would suggest to one of ordinary skill in the art that using such a process gas could save energy by circumventing the need for heating an incoming air stream to the temperatures required for use as the stripping media.
Examiner notes that the sulfuric acid concentrator column 21 in the embodiment of Figure 2 is also an Integrated Sulfuric Acid Concentrator, i.e. a sulfuric acid concentrator column that is in fluid communication with a liquid outlet of a sulfuric acid condenser 41 via the line containing the sulfuric acid feed stream and is disposed such that stripping gas exiting the concentrator column 21 enters the sulfuric acid condenser 41 via lines 28 and 43 (Figure 2, Column 3 Line 63-Column 4 Line 5).
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye by using a process gas comprising water and sulfur trioxide, in order to obtain a predictably functional method in accordance with the suggestions of Schoubye, and in order to obtain a method which saves energy by circumventing the need to heat an incoming air stream for use as the stripping media.
With regard to claim 22: Schoubye teaches a process for increasing the concentration of sulfuric acid in a sulfuric acid feed stream 22, wherein the sulfuric acid feed stream is already concentrated (Figure 1, Column 3 Lines 10-62), the process comprising:
A step of stripping water from the sulfuric acid feed stream 22 by contacting the sulfuric acid feed stream with a stripping media in a sulfuric acid concentrator column 21 to increase a concentration of a sulfuric acid product stream leaving the column 21 (Figure 1, Column 3 Lines 10-62).
Wherein the stripping media is air (Figure 1, Column 3 Lines 10-62).
And wherein the sulfuric acid concentrator is an Integrated Sulfuric Acid Concentrator, i.e. a sulfuric acid concentrator column that is in fluid communication with a liquid outlet of a sulfuric acid condenser 15 via the line containing the sulfuric acid feed stream and is disposed such that stripping gas exiting the concentrator column 21 enters the sulfuric acid condenser 15 via lines 28, 24, and 14 (Figure 1, Column 3 Lines 10-62).
Schoubye is silent to a fraction of the sulfuric acid product stream column 21 being recycled back to a position upstream of the column an acid recirculation loop.
However, it is known in the art to provide concentrator columns with a recycle stream in order to increase the concentration of a product obtained from said column. For example, Fox teaches a stripping column (stripping tower) 12 for removing volatile constituents (hydrocarbons) from a liquid (water) using air as a stripping gas, the column comprising a pump 32 and pipe 34 for providing a recycle stream of liquid (abstract, Figure 1, Column 2 Line 50-Column 4 Line 30). In operation of the stripping column 12, liquid is recycled/recirculated repeatedly to the top 24 of the tower 12 to “enhance separation and disposal of the volatile components,” (Figure 1, Column 3 Line 63-Column 4 Line 30).
Furthermore, it is known in the art of sulfuric acid concentration to recycle concentrated sulfuric acid streams to concentration processes. For example, Shah teaches a sulfuric acid concentration process wherein concentrated sulfuric acid is recycled to a concentrator (venturi concentrator) 10/11/16/17 via line 6 (abstract, Figure 1, Column 2).
In addition, the disclosure of Schoubye would suggest to one of ordinary skill in the art that, in at least some embodiments, the process of Schoubye would benefit from a means for further increasing the concentration of the product obtained from the sulfuric acid concentrator column 21. Specifically, Schoubye teaches that, in the process thereof, the sulfuric acid concentrator column 21 produces a concentrated sulfuric acid stream having a concentration in the range of 95-98.7% (Figure 1, claim 1, column 1 Lines 50-60, see annotated Figure 1 below). By this teaching, Schoubye at least suggests that some embodiments of the process therein are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % (see Column 3 Lines 59-62 of Schoubye).
Further still, the teachings of Schoubye indicate that the maximal achievable concentration of sulfuric acid product is determined in part by the concentration of acid received at the top of the concentrator column (Column 3 Lines 45-62). These teachings would indicate to one of ordinary skill in the art that Schoubye’s method is only capable of achieving the theoretical azeotropic maximum concentration in instances where certain conditions are met. Thus, said teachings would at least reinforce the suggestion that Schoubye’s method has embodiments which are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 %.
In view of the above, a person having ordinary skill in the art would have a reasonable expectation that: i) the concentrator column 21 of Schoubye could be successfully provided with a recycle stream for the purpose of improving the concentrator column’s ability to yield highly concentrated sulfuric acid product; and ii) the concentrator column 21 in Schoubye would benefit from the inclusion of such a recycle stream.
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It would have been obvious to one of ordinary skill in the art before the effective filing date to modify Schoubye in view of Fox and Shah by adding a step of recycling, via an acid recirculation loop, a fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mixing it with the sulfuric acid feed stream 22 before it enters the column 21, in order to obtain a method wherein the sulfuric acid concentrator column is better able to yield a highly concentrated sulfuric acid product, i.e. a method wherein the sulfuric acid concentrator column is able to yield sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % across a wider range of embodiments.
As discussed above, the recirculation loop of modified Schoubye supplies the fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mixes it with the sulfuric acid feed stream 22 before it enters the column 21. Thus, it is implicit that the acid recirculation loop of modified Schoubye includes a pipe which directs the fraction of the sulfuric acid product to a position upstream of the concentrator column, as a pipe (i.e. some conduit which supports liquid flow) is necessary to convey the fraction of the sulfuric acid product in such a manner.
In the unlikely alternative, a person having ordinary skill in the art would recognize that the recirculation loop of modified Schoubye would require a pipe (i.e. some conduit which supports liquid flow) is necessary to convey the fraction of the sulfuric acid to a position upstream of the column 21.
In the event it were not already present in modified Schoubye, it would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye by providing the acid recirculation loop with a pipe which directs the fraction of the sulfuric acid product to a position upstream of the concentrator column, in order to provide the recirculation loop with a conduit necessary to support liquid flow.
Modified Schoubye is silent to the recirculation loop comprising an acid heater configured to heat the fraction of the sulfuric acid product stream to a temperature of 200-270 °C.
However, a person having ordinary skill in the art would recognize that temperature conditions (including but not limited to feed temperature) are result effective variables in vapor liquid separations such as the stripping carried out in the concentrator column 21 of Schoubye. In particular, a person having ordinary skill in the art would recognize that if temperature conditions in a vapor liquid separation process such as stripping are too high or too low, then the necessary vapor liquid equilibrium conditions within the process will not be achieved, nor will the desired separation(s). Therefore, a person having ordinary skill in the art would recognize that the temperature of the feed to the concentration column of Schoubye is a result effective variable.
As discussed above, the fraction of the sulfuric acid product stream leaving the column and being recirculated through the recirculation loop is combined with the sulfuric acid feed stream 22. Said sulfuric acid feed stream 22 has a temperature of 180-270°C (Schoubye: Figure 1, Column 3 Lines 10-62). A person having ordinary skill in the art would recognize that, when recirculating the fraction of the sulfuric acid product stream, said recirculated fraction, when combined with the sulfuric acid feed stream 22 will affect the temperature of the feed to the concentrator column 21, i.e. if the temperature of the recirculated fraction is higher or lower than the feed stream 22, then upon mixing, it will raise or lower the temperature of said feed stream, thus altering the temperature of the feed to the concentrator column 21. Because a person having ordinary skill in the art would recognize that: 1) the temperature of the feed to the concentrator column 21 is a result effective variable, and 2) the temperature of the recirculated fraction will affect the temperature of the feed to the concentrator column 21, a person having ordinary skill in the art would further recognize that the temperature of the recirculated fraction is a result effective variable as well. In particular, a person having ordinary skill in the art would recognize that, when recirculating the fraction of the sulfuric acid product stream, said fraction would need to be brought to the same temperature as the sulfuric acid feed stream 22 in order to ensure that the feed to the concentration column 21 maintains the temperature conditions taught in base Schoubye. "[When] the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation," (see MPEP 2144.05 II A).
Furthermore, the sulfuric acid product stream leaving the concentrator column 21 is cooled by the cooler 27 (Schoubye: Figure 1, Column 3 Lines 10-62). This would indicate to one of ordinary skill in the art that the fraction of the sulfuric acid product stream leaving the column and being recirculated through the recirculation loop would need to be heated during its recirculation to be brought to the same temperature as the sulfuric acid feed stream 22, i.e. said fraction would need to be heated to a temperature of 180-270 °C to be brought to the same temperature as the sulfuric acid feed stream 22. It is noted that the claimed temperature range to which the fraction is heated (200-270 °C) lies inside the taught temperature range for the sulfuric acid feed stream. “In the case where the claimed ranges ‘overlap or lie inside ranges disclosed by the prior art’ a prima facie case of obviousness exists,” (MPEP 2144.05 I).
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye by providing the acid recirculation loop with a heater configured to heat the fraction of the sulfuric acid product stream to a temperature of 200-270 °C by heat exchange during its passage through the acid recirculation loop, in order to heat said fraction to a temperature equal to that of the sulfuric acid feed stream 22, so as to maintain the temperature conditions of the feed to the concentrator column within the range taught to be acceptable by base Schoubye.
Modified Schoubye is silent to the acid recirculation loop comprising an acid pump fed with the fraction of the sulfuric acid product stream.
As discussed above, the recirculation loop of modified Schoubye supplies the fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mixes it with the sulfuric acid feed stream 22 before it enters the column 21. The sulfuric acid product stream in modified Schoubye leaves the bottom of the column 21, whereas the acid feed stream 22 enters the top of the column. Therefore, it is understood that, in order to supply the fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mix it with the sulfuric acid feed stream 22 before it enters the column 21, the recirculation loop must move the said acid product stream to a higher elevation.
It is well understood that in order to induce fluid flow uphill, i.e. to a higher elevation, through a pipe, a pressure gradient is required, i.e. it is understood that fluid must be pressurized to flow to a higher elevation through a pipe. Pumps are notoriously well-known means of generating a pressure gradient to induce fluid flow.
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye by adding, to the acid recirculation loop, a pump which is fed with the fraction of the sulfuric acid and which pressurizes the fraction of the sulfuric acid product, in order to provide the recirculation loop with necessary means of supplying the acid to a higher elevation, as is required to supply the fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mix it with the sulfuric acid feed stream 22 before it enters the column 21.
The pump of the acid recirculation loop is necessarily an acid pump in that it pumps acid, i.e. the fraction of the sulfuric acid product stream.
Claim(s) 13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Schoubye in view of Fox, Shah, and Dunham (US 2,113,130).
With regard to claim 13: Schoubye teaches a process for increasing the concentration of sulfuric acid in a sulfuric acid feed stream 22, wherein the sulfuric acid feed stream is already concentrated (Figure 1, Column 3 Lines 10-62), the process comprising:
A step of stripping water from the sulfuric acid feed stream 22 by contacting the sulfuric acid feed stream with a stripping media in a sulfuric acid concentrator column 21 to increase a concentration of a sulfuric acid product stream leaving the column 21 (Figure 1, Column 3 Lines 10-62).
Wherein the stripping media is air (Figure 1, Column 3 Lines 10-62).
And wherein the stripping media is heated by indirect heat exchange with a flue gas in heat exchanger 4 (Figure 1, Column 3 Lines 10-62).
Schoubye is silent to a fraction of the sulfuric acid product stream column 21 being recycled back to a position upstream of the column via an acid recirculation loop.
However, it is known in the art to provide concentrator columns with a recycle stream in order to increase the concentration of a product obtained from said column. For example, Fox teaches a stripping column (stripping tower) 12 for removing volatile constituents (hydrocarbons) from a liquid (water) using air as a stripping gas, the column comprising a pump 32 and pipe 34 for providing a recycle stream of liquid (abstract, Figure 1, Column 2 Line 50-Column 4 Line 30). In operation of the stripping column 12, liquid is recycled/recirculated repeatedly to the top 24 of the tower 12 to “enhance separation and disposal of the volatile components,” (Figure 1, Column 3 Line 63-Column 4 Line 30).
Furthermore, it is known in the art of sulfuric acid concentration to recycle concentrated sulfuric acid streams to concentration processes. For example, Shah teaches a sulfuric acid concentration process wherein concentrated sulfuric acid is recycled to a concentrator (venturi concentrator) 10/11/16/17 via line 6 (abstract, Figure 1, Column 2).
In addition, the disclosure of Schoubye would suggest to one of ordinary skill in the art that, in at least some embodiments, the process of Schoubye would benefit from a means for further increasing the concentration of the product obtained from the sulfuric acid concentrator column 21. Specifically, Schoubye teaches that, in the process thereof, the sulfuric acid concentrator column 21 produces a concentrated sulfuric acid stream having a concentration in the range of 95-98.7% (Figure 1, claim 1, column 1 Lines 50-60, see annotated Figure 1 below). By this teaching, Schoubye at least suggests that some embodiments of the process therein are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % (see Column 3 Lines 59-62 of Schoubye).
Further still, the teachings of Schoubye indicate that the maximal achievable concentration of sulfuric acid product is determined in part by the concentration of acid received at the top of the concentrator column (Column 3 Lines 45-62). These teachings would indicate to one of ordinary skill in the art that Schoubye’s method is only capable of achieving the theoretical azeotropic maximum concentration in instances where certain conditions are met. Thus, said teachings would at least reinforce the suggestion that Schoubye’s method has embodiments which are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 %.
In view of the above, a person having ordinary skill in the art would have a reasonable expectation that: i) the concentrator column 21 of Schoubye could be successfully provided with a recycle stream for the purpose of improving the concentrator column’s ability to yield highly concentrated sulfuric acid product; and ii) the concentrator column 21 in Schoubye would benefit from the inclusion of such a recycle stream.
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It would have been obvious to one of ordinary skill in the art before the effective filing date to modify Schoubye in view of Fox and Shah by adding a step of recycling, via an acid recirculation loop, a fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mixing it with the sulfuric acid feed stream 22 before it enters the column 21, in order to obtain a method wherein the sulfuric acid concentrator column is better able to yield a highly concentrated sulfuric acid product, i.e. a method wherein the sulfuric acid concentrator column is able to yield sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % across a wider range of embodiments.
Modified Schoubye is silent to heating of the stripping media by indirect heat exchange with saturated or superheated steam, molten heat transfer salt, heat transfer oil, or any combination thereof.
However, as discussed above, In Schoubye the stripping media is heated by indirect heat exchange with a flue gas in heat exchanger 4 (Schoubye: Figure 1, Column 3 Lines 10-62). Said heat exchanger 4 is an indirect heat exchanger which uses a flue gas as a heat transfer fluid. Absent evidence to the contrary, a person having ordinary skill in the art would expect that said heat exchanger 4 would remain capable of heating the stripping media by indirect heat exchange if the flue gas were replaced with some other heat transfer fluid.
Furthermore, Saturated and superheated steam, molten heat transfer salts, and heat transfer oil are all notoriously well-known heat transfer fluids. For example, steam is used commonly used as a heat transfer fluid for heating distillation column reboilers. As evidence, Examiner points to Dunham which teaches the use of steam as a heat transfer fluid in a pair of distillation column reboilers 16 and 21 (Figure 1, Page 1 Right Column Line 50-Page 2 Left column line 11, Page 2 Left columns lines 30-36). It is noted that said reboilers 16 and 21 are indirect contact heat exchangers (Figure 1, Page 1 Right Column Line 50-Page 2 Left column line 11, Page 2 Left columns lines 30-36). It is well established that it would be obvious to one of ordinary skill in the art to substitute one known prior art element for another in order to obtain predictable results (MPEP 2143).
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye in view of Dunham by substituting superheated steam in place of the flue gas for use as the heat transfer fluid for heating the stripping media in the heat exchanger 4, in order to obtain a method wherein the stripping media is indirectly heated in the heat exchanger 4 with predictable success.
Note: This rejection is NOT proposing that the flue gas in Schoubye be entirely replaced with steam. Rather, said rejection is merely proposing use of steam instead of the flue gas as the heat transfer fluid in the heat exchanger 4.
Claim(s) 13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Schoubye in view of Fox, Shah, and Cap et al. (US 201//0048006), hereafter referred to as Cap.
With regard to claim 13: Schoubye teaches a process for increasing the concentration of sulfuric acid in a sulfuric acid feed stream 22, wherein the sulfuric acid feed stream is already concentrated (Figure 1, Column 3 Lines 10-62), the process comprising:
A step of stripping water from the sulfuric acid feed stream 22 by contacting the sulfuric acid feed stream with a stripping media in a sulfuric acid concentrator column 21 to increase a concentration of a sulfuric acid product stream leaving the column 21 (Figure 1, Column 3 Lines 10-62).
Wherein the stripping media is air (Figure 1, Column 3 Lines 10-62).
And wherein the stripping media is heated by indirect heat exchange with a flue gas in heat exchanger 4 (Figure 1, Column 3 Lines 10-62).
Schoubye is silent to a fraction of the sulfuric acid product stream column 21 being recycled back to a position upstream of the column via an acid recirculation loop.
However, it is known in the art to provide concentrator columns with a recycle stream in order to increase the concentration of a product obtained from said column. For example, Fox teaches a stripping column (stripping tower) 12 for removing volatile constituents (hydrocarbons) from a liquid (water) using air as a stripping gas, the column comprising a pump 32 and pipe 34 for providing a recycle stream of liquid (abstract, Figure 1, Column 2 Line 50-Column 4 Line 30). In operation of the stripping column 12, liquid is recycled/recirculated repeatedly to the top 24 of the tower 12 to “enhance separation and disposal of the volatile components,” (Figure 1, Column 3 Line 63-Column 4 Line 30).
Furthermore, it is known in the art of sulfuric acid concentration to recycle concentrated sulfuric acid streams to concentration processes. For example, Shah teaches a sulfuric acid concentration process wherein concentrated sulfuric acid is recycled to a concentrator (venturi concentrator) 10/11/16/17 via line 6 (abstract, Figure 1, Column 2).
In addition, the disclosure of Schoubye would suggest to one of ordinary skill in the art that, in at least some embodiments, the process of Schoubye would benefit from a means for further increasing the concentration of the product obtained from the sulfuric acid concentrator column 21. Specifically, Schoubye teaches that, in the process thereof, the sulfuric acid concentrator column 21 produces a concentrated sulfuric acid stream having a concentration in the range of 95-98.7% (Figure 1, claim 1, column 1 Lines 50-60, see annotated Figure 1 below). By this teaching, Schoubye at least suggests that some embodiments of the process therein are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % (see Column 3 Lines 59-62 of Schoubye).
Further still, the teachings of Schoubye indicate that the maximal achievable concentration of sulfuric acid product is determined in part by the concentration of acid received at the top of the concentrator column (Column 3 Lines 45-62). These teachings would indicate to one of ordinary skill in the art that Schoubye’s method is only capable of achieving the theoretical azeotropic maximum concentration in instances where certain conditions are met. Thus, said teachings would at least reinforce the suggestion that Schoubye’s method has embodiments which are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 %.
In view of the above, a person having ordinary skill in the art would have a reasonable expectation that: i) the concentrator column 21 of Schoubye could be successfully provided with a recycle stream for the purpose of improving the concentrator column’s ability to yield highly concentrated sulfuric acid product; and ii) the concentrator column 21 in Schoubye would benefit from the inclusion of such a recycle stream.
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It would have been obvious to one of ordinary skill in the art before the effective filing date to modify Schoubye in view of Fox and Shah by adding a step of recycling, via an acid recirculation loop, a fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mixing it with the sulfuric acid feed stream 22 before it enters the column 21, in order to obtain a method wherein the sulfuric acid concentrator column is better able to yield a highly concentrated sulfuric acid product, i.e. a method wherein the sulfuric acid concentrator column is able to yield sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % across a wider range of embodiments.
Modified Schoubye is silent to heating of the stripping media by indirect heat exchange with saturated or superheated steam, molten heat transfer salt, heat transfer oil, or any combination thereof.
However, as discussed above, In Schoubye the stripping media is heated by indirect heat exchange with a flue gas in heat exchanger 4 (Schoubye: Figure 1, Column 3 Lines 10-62). Said heat exchanger 4 is an indirect heat exchanger which uses a flue gas as a heat transfer fluid. Absent evidence to the contrary, a person having ordinary skill in the art would expect that said heat exchanger 4 would remain capable of heating the stripping media by indirect heat exchange if the flue gas were replaced with some other heat transfer fluid.
Furthermore, Saturated and superheated steam, molten heat transfer salts, and heat transfer oil are all notoriously well-known heat transfer fluids. For example, molten heat transfer salts are often used in solar thermal heating instillations, e.g. solar thermal power plants. As evidence, Examiner points to Cap which teaches the use of molten salt as a heat transfer fluid to heat indirect contact heat exchangers 32A, 32B, and 32C (Figure 1, paragraph [0009]). It is well established that it would be obvious to one of ordinary skill in the art to substitute one known prior art element for another in order to obtain predictable results (MPEP 2143).
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye in view of Cap by substituting molten salt in place of the flue gas for use as the heat transfer fluid for heating the stripping media in the heat exchanger 4, in order to obtain a method wherein the stripping media is indirectly heated in the heat exchanger 4 with predictable success.
Note: This rejection is NOT proposing that the flue gas in Schoubye be entirely replaced with molten salt. Rather, said rejection is merely proposing use of molten salt instead of the flue gas as the heat transfer fluid in the heat exchanger 4.
Claim(s) 13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Schoubye in view of Fox, Shah, and Litwin (US 2005/0126170).
With regard to claim 13: Schoubye teaches a process for increasing the concentration of sulfuric acid in a sulfuric acid feed stream 22, wherein the sulfuric acid feed stream is already concentrated (Figure 1, Column 3 Lines 10-62), the process comprising:
A step of stripping water from the sulfuric acid feed stream 22 by contacting the sulfuric acid feed stream with a stripping media in a sulfuric acid concentrator column 21 to increase a concentration of a sulfuric acid product stream leaving the column 21 (Figure 1, Column 3 Lines 10-62).
Wherein the stripping media is air (Figure 1, Column 3 Lines 10-62).
And wherein the stripping media is heated by indirect heat exchange with a flue gas in heat exchanger 4 (Figure 1, Column 3 Lines 10-62).
Schoubye is silent to a fraction of the sulfuric acid product stream column 21 being recycled back to a position upstream of the column via an acid recirculation loop.
However, it is known in the art to provide concentrator columns with a recycle stream in order to increase the concentration of a product obtained from said column. For example, Fox teaches a stripping column (stripping tower) 12 for removing volatile constituents (hydrocarbons) from a liquid (water) using air as a stripping gas, the column comprising a pump 32 and pipe 34 for providing a recycle stream of liquid (abstract, Figure 1, Column 2 Line 50-Column 4 Line 30). In operation of the stripping column 12, liquid is recycled/recirculated repeatedly to the top 24 of the tower 12 to “enhance separation and disposal of the volatile components,” (Figure 1, Column 3 Line 63-Column 4 Line 30).
Furthermore, it is known in the art of sulfuric acid concentration to recycle concentrated sulfuric acid streams to concentration processes. For example, Shah teaches a sulfuric acid concentration process wherein concentrated sulfuric acid is recycled to a concentrator (venturi concentrator) 10/11/16/17 via line 6 (abstract, Figure 1, Column 2).
In addition, the disclosure of Schoubye would suggest to one of ordinary skill in the art that, in at least some embodiments, the process of Schoubye would benefit from a means for further increasing the concentration of the product obtained from the sulfuric acid concentrator column 21. Specifically, Schoubye teaches that, in the process thereof, the sulfuric acid concentrator column 21 produces a concentrated sulfuric acid stream having a concentration in the range of 95-98.7% (Figure 1, claim 1, column 1 Lines 50-60, see annotated Figure 1 below). By this teaching, Schoubye at least suggests that some embodiments of the process therein are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % (see Column 3 Lines 59-62 of Schoubye).
Further still, the teachings of Schoubye indicate that the maximal achievable concentration of sulfuric acid product is determined in part by the concentration of acid received at the top of the concentrator column (Column 3 Lines 45-62). These teachings would indicate to one of ordinary skill in the art that Schoubye’s method is only capable of achieving the theoretical azeotropic maximum concentration in instances where certain conditions are met. Thus, said teachings would at least reinforce the suggestion that Schoubye’s method has embodiments which are incapable of yielding a concentrated sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 %.
In view of the above, a person having ordinary skill in the art would have a reasonable expectation that: i) the concentrator column 21 of Schoubye could be successfully provided with a recycle stream for the purpose of improving the concentrator column’s ability to yield highly concentrated sulfuric acid product; and ii) the concentrator column 21 in Schoubye would benefit from the inclusion of such a recycle stream.
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It would have been obvious to one of ordinary skill in the art before the effective filing date to modify Schoubye in view of Fox and Shah by adding a step of recycling, via an acid recirculation loop, a fraction of the acid product stream (i.e. the concentrated sulfuric acid leaving the column 21) to a position upstream of the column 21 and mixing it with the sulfuric acid feed stream 22 before it enters the column 21, in order to obtain a method wherein the sulfuric acid concentrator column is better able to yield a highly concentrated sulfuric acid product, i.e. a method wherein the sulfuric acid concentrator column is able to yield sulfuric acid which has been maximally concentrated to the theoretical azeotropic maximum concentration of 98.7-98.8 % across a wider range of embodiments.
Modified Schoubye is silent to heating of the stripping media by indirect heat exchange with saturated or superheated steam, molten heat transfer salt, heat transfer oil, or any combination thereof.
However, as discussed above, In Schoubye the stripping media is heated by indirect heat exchange with a flue gas in heat exchanger 4 (Schoubye: Figure 1, Column 3 Lines 10-62). Said heat exchanger 4 is an indirect heat exchanger which uses a flue gas as a heat transfer fluid. Absent evidence to the contrary, a person having ordinary skill in the art would expect that said heat exchanger 4 would remain capable of heating the stripping media by indirect heat exchange if the flue gas were replaced with some other heat transfer fluid.
Furthermore, Saturated and superheated steam, molten heat transfer salts, and heat transfer oil are all notoriously well-known heat transfer fluids. For example, heat transfer oil is often used in solar thermal heating instillations, e.g. solar thermal power plants. As evidence, Examiner points to Litwin which teaches the use of oil as a heat transfer fluid for heating an indirect contact heat exchanger (steam generator) 22 (Figure 1, paragraph [0004]). It is well established that it would be obvious to one of ordinary skill in the art to substitute one known prior art element for another in order to obtain predictable results (MPEP 2143).
It would have been obvious to one of ordinary skill in the art before the effective filing date to further modify Schoubye in view of Litwin by substituting heat transfer oil in place of the flue gas for use as the heat transfer fluid for heating the stripping media in the heat exchanger 4, in order to obtain a method wherein the stripping media is indirectly heated in the heat exchanger 4 with predictable success.
Note: This rejection is NOT proposing that the flue gas in Schoubye be entirely replaced with heat transfer oil. Rather, said rejection is merely proposing use of heat transfer oil instead of the flue gas as the heat transfer fluid in the heat exchanger 4.
Conclusion
All claims are identical to or patentably indistinct from, or have unity of invention with claims in the application prior to the entry of the submission under 37 CFR 1.114 (that is, restriction (including a lack of unity of invention) would not be proper) and all claims could have been finally rejected on the grounds and art of record in the next Office action if they had been entered in the application prior to entry under 37 CFR 1.114. Accordingly, THIS ACTION IS MADE FINAL even though it is a first action after the filing of a request for continued examination and the submission under 37 CFR 1.114. See MPEP § 706.07(b). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JONATHAN "LUKE" PILCHER whose telephone number is (571)272-2691. The examiner can normally be reached Monday-Friday 9am-5pm.
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/JONATHAN LUKE PILCHER/ Examiner, Art Unit 1772