Prosecution Insights
Last updated: April 19, 2026
Application No. 18/004,678

WET AIR OXIDATION SYSTEM WITH SHELL AND TUBE HEAT EXCHANGER

Final Rejection §103
Filed
Jan 09, 2023
Examiner
CHIU, TAK LIANG
Art Unit
1777
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Lummus Technology LLC
OA Round
2 (Final)
53%
Grant Probability
Moderate
3-4
OA Rounds
3y 8m
To Grant
90%
With Interview

Examiner Intelligence

Grants 53% of resolved cases
53%
Career Allow Rate
17 granted / 32 resolved
-11.9% vs TC avg
Strong +37% interview lift
Without
With
+37.2%
Interview Lift
resolved cases with interview
Typical timeline
3y 8m
Avg Prosecution
37 currently pending
Career history
69
Total Applications
across all art units

Statute-Specific Performance

§101
1.4%
-38.6% vs TC avg
§103
42.3%
+2.3% vs TC avg
§102
17.6%
-22.4% vs TC avg
§112
37.1%
-2.9% vs TC avg
Black line = Tech Center average estimate • Based on career data from 32 resolved cases

Office Action

§103
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 . Priority Applicant’s claim for the benefit of a prior-filed application (has PRO 63058055, filed on 29 July 2020; is 371 of PCT/US2021/042687, filed on 22 July 2021) under 35 U.S.C. 119(e) or under 35 U.S.C. 120, 121, 365(c), or 386(c) is acknowledged. Claim Objections Claim 11 objected to because of the following informalities: The term “pre-heated” in line 3 and the 3rd last wherein clause should be corrected to read “preheated” to maintain consistent terminology within the claim set. Appropriate correction is required. 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 text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: Determining the scope and contents of the prior art. Ascertaining the differences between the prior art and the claims at issue. Resolving the level of ordinary skill in the pertinent art. Considering objective evidence present in the application indicating obviousness or nonobviousness. Claims 1-5, 11, 13-15 are rejected under 35 U.S.C. 103 as being unpatentable over FELCH et al. (US20050171390A1, hereinafter FELCH) in view of BAHARUDDIN et al. (US20180258033A1, hereinafter BAHARUDDIN). Regarding Claim 1, FELCH discloses a wet oxidation system and process (¶[0003]). FIG. 1 illustrates a wet oxidation system including a pump 14 that conveys an aqueous material from a source 12 and an oxygen-containing gas from an oxidant source 16 into a conduit 18 upstream of a heat exchanger 20. The aqueous material and oxygen-containing gas form a two-phase mixture that is heated across the heat exchanger 20 and introduced into a reactor vessel 24 through an inlet 38. The reactor vessel 24 oxidizes the mixture under elevated temperature and pressure, producing a hot oxidized fluid that exits through an outlet 26 and is returned across the heat exchanger 20 before entering a gas–liquid separator 32 (¶[0023]). PNG media_image1.png 769 1204 media_image1.png Greyscale FIG 1. From US20050171390 However, FELCH does not explicitly disclose that the heat exchanger is a shell and tube heat exchanger including a plurality of tubes extending along a long axis in a nonhorizontal direction, and a shell surrounding the tubes. BAHARUDDIN discloses a process where a urea synthesis solution is placed under reduced pressure to provide a gas–liquid mixture, and the gas–liquid mixture is then heated in a heating step using a decomposed gas. In the heating step, the decomposed gas is introduced into a tube side of a shell and tube heat exchanger while the gas–liquid mixture is introduced into a shell side of the shell and tube heat exchanger (¶¶[0018]–[0019]). In the heating step, the gas liquid mixture is introduced into the shell side of the shell and tube heat exchanger while the decomposed gas is introduced into the tube side. Supplying the high pressure decomposed gas into the shell side would require setting the design pressure of the entire shell and tube heat exchanger high, so the decomposed gas is supplied into the tube side. The shell and tube heat exchanger is preferably a vertical type, and the decomposed gas is introduced to heat the gas liquid mixture and then discharged, with introduction through an upper nozzle preferred from the viewpoint of heating efficiency (¶¶[0031]–[0032]). Advantageously, the vertical shell and tube heat exchanger disclosed by BAHARUDDIN routes the high-pressure stream through the tube side to avoid requiring the design pressure of the entire shell and tube heat exchanger to be set high. The vertical type is compact and can be installed in a smaller area (¶¶[0031]–[0032]). In view of FELCH’s wet oxidation system using a general heat exchanger to preheat the two-phase mixture, a person skilled in the art would incorporate BAHARUDDIN’s vertical shell and tube heat exchanger with high pressure decomposed gas on the tube side and two-phase gas liquid mixture on the shell side to achieve lower equipment design pressure and cost along with compact installation. Regarding a plurality of tubes extending along a long axis in a nonhorizontal direction and a shell surrounding the tubes, BAHARUDDIN discloses the shell and tube heat exchanger is vertical, and it inherently includes a plurality of tubes extending along a long axis in a nonhorizontal direction and a shell surrounding the tubes. Regarding all of the wherein clauses within the claim, based on FELCH’s wet oxidation system and BAHARUDDIN’s vertical shell and tube heat exchanger with the hot stream routed through the tube side and the two-phase stream routed through the shell side, a person skilled in the art would understand the clauses as describing the plumbing and flow paths that necessarily result from that structure and stream routing. Regarding “configured to enhance mixing of the two-phase process fluid within the shell and reduce corrosion,” BAHARUDDIN discloses a vertical shell and tube heat exchanger in which the gas–liquid mixture is introduced into the shell side while the heating stream is introduced into the tube side, which provides the claimed structural configuration of the two-phase process fluid flowing through the shell while the hot stream flows through the tubes, such that this limitation is inherently satisfied by virtue of that structure and stream routing. Therefore, it would have been obvious to a person having ordinary skill in the art, prior to the effective filing date of the claimed invention, to incorporate a vertical shell and tube heat exchanger, as disclosed by BAHARUDDIN, into the heat exchanger of the wet oxidation system by FELCH. Regarding Claim 2, modified FELCH makes obvious a wet oxidation system of Claim 1. BAHARUDDIN discloses the shell and tube heat exchanger is preferably a vertical type (¶[0032]). Regarding Claim 3, modified FELCH makes obvious the wet air oxidation system of claim 1. FELCH discloses that the two-phase process fluid includes an aqueous material combined with an oxygen-containing gas upstream of the heat exchanger (¶[0023]). The aqueous material contains organo-sulfur compounds that are oxidized during the wet oxidation process to convert carbon–sulfur bonds into sulfate (¶[0020]). The limitation “the two-phase process fluid includes a liquid that contains reactive sulfides and a gas that contains oxygen” merely recites the material worked upon by the apparatus. As such, it carries no patentable weight (In re Otto, 312 F.2d 937, 940; 1963; In re Casey, 370 F.2d 576, 580; 1967). Regarding Claim 4, modified FELCH makes obvious the wet air oxidation system of Claim 1. FELCH discloses that the heated feed mixture enters reactor vessel 24 at inlet 38, where the bulk of the oxidation reaction occurs. The oxidized aqueous mixture and oxygen-depleted gas mixture exit the reactor through conduit 26 as the hot oxidized effluent, which then traverses heat exchanger 20 (¶[0023]). It is reasonably interpreted that the oxidation reaction in reactor vessel 24 is exothermic, because FELCH describes the reactor outlet stream as hot oxidized effluent after the feed mixture is heated and introduced into the reactor. Regarding Claim 5, modified FELCH makes obvious the wet air oxidation system of Claim 1. FELCH discloses an air compressor 16 that supplies a pressurized oxygen-containing gas, which is mixed with the aqueous mixture in conduit 18 to form a two-phase mixture upstream of the heat exchanger (¶[0023]). Regarding Claim 11, FELCH discloses a wet oxidation system and process (¶[0003]). FIG. 1 illustrates a wet oxidation system including a pump 14 that conveys an aqueous material from a source 12 and an oxygen-containing gas from an oxidant source 16 into a conduit 18 upstream of a heat exchanger 20. The aqueous material and oxygen-containing gas form a two-phase mixture that is heated across the heat exchanger 20 and introduced into a reactor vessel 24 through an inlet 38. The reactor vessel 24 oxidizes the mixture under elevated temperature and pressure, producing a hot oxidized fluid that exits through an outlet 26 and is returned across the heat exchanger 20 before entering a gas–liquid separator 32 (¶[0023]). However, FELCH does not explicitly disclose that the heat exchanger is a shell and tube heat exchanger having a plurality of tubes extending parallel to a long axis, with the hot oxidized fluid flowing through the tubes and the two-phase process fluid flowing through the shell. BAHARUDDIN discloses a process where a urea synthesis solution is placed under reduced pressure to provide a gas–liquid mixture, and the gas–liquid mixture is then heated in a heating step using a decomposed gas. In the heating step, the decomposed gas is introduced into a tube side of a shell and tube heat exchanger while the gas–liquid mixture is introduced into a shell side of the shell and tube heat exchanger (¶¶[0018]–[0019]). In the heating step, the gas liquid mixture is introduced into the shell side of the shell and tube heat exchanger while the decomposed gas is introduced into the tube side. Supplying the high pressure decomposed gas into the shell side would require setting the design pressure of the entire shell and tube heat exchanger high, so the decomposed gas is supplied into the tube side. The shell and tube heat exchanger is preferably a vertical type, and the decomposed gas is introduced to heat the gas liquid mixture and then discharged, with introduction through an upper nozzle preferred from the viewpoint of heating efficiency (¶¶[0031]–[0032]). Advantageously, the vertical shell and tube heat exchanger disclosed by BAHARUDDIN routes the high-pressure stream through the tube side to avoid requiring the design pressure of the entire shell and tube heat exchanger to be set high. The vertical type is compact and can be installed in a smaller area (¶¶[0031]–[0032]). In view of FELCH’s wet oxidation system using a general heat exchanger to preheat the two-phase mixture, a person skilled in the art would incorporate BAHARUDDIN’s vertical shell and tube heat exchanger with high pressure decomposed gas on the tube side and two-phase gas liquid mixture on the shell side to achieve lower equipment design pressure and cost along with compact installation. Regarding a plurality of tubes extending along a long axis in a nonhorizontal direction and a shell surrounding the tubes, BAHARUDDIN discloses the shell and tube heat exchanger is vertical, and it inherently includes a plurality of tubes extending along a long axis in a nonhorizontal direction and a shell surrounding the tubes. Regarding “configured to enhance mixing of the two-phase process fluid within the shell and reduce corrosion,” BAHARUDDIN discloses a vertical shell and tube heat exchanger in which the gas–liquid mixture is introduced into the shell side while the heating stream is introduced into the tube side, which provides the claimed structural configuration of the two-phase process fluid flowing through the shell while the hot stream flows through the tubes, such that this limitation is inherently satisfied by virtue of that structure and stream routing. Therefore, it would have been obvious to a person having ordinary skill in the art, prior to the effective filing date of the claimed invention, to incorporate a vertical shell and tube heat exchanger, as disclosed by BAHARUDDIN, into the heat exchanger of the wet oxidation system by FELCH. Regarding Claim 13, modified FELCH makes obvious a wet oxidation system of Claim 11. BAHARUDDIN discloses the shell and tube heat exchanger is vertical (¶¶[0031]–[0032]). Regarding Claim 14, modified FELCH makes obvious the wet air oxidation system of Claim 11. FELCH discloses that the two-phase process fluid includes an aqueous material combined with an oxygen-containing gas upstream of the heat exchanger (¶[0023]), and that the aqueous material contains organo-sulfur compounds that are oxidized during the wet oxidation process to convert carbon–sulfur bonds into sulfate (¶[0020]). The limitation “the two-phase process fluid includes a liquid that contains reactive sulfides and a gas that contains oxygen” merely recites the material worked upon by the apparatus. As such, it carries no patentable weight (In re Otto, 312 F.2d 937, 940; 1963; In re Casey, 370 F.2d 576, 580; 1967). Regarding Claim 15, modified FELCH makes obvious the wet air oxidation system of Claim 11. FELCH discloses that the heated feed mixture enters reactor vessel 24 at inlet 38, where the bulk of the oxidation reaction occurs. The oxidized aqueous mixture and oxygen-depleted gas mixture exit the reactor through conduit 26 as the hot oxidized effluent, which then traverses heat exchanger 20 (¶[0023]). It is reasonably interpreted that the oxidation reaction in reactor vessel 24 is exothermic, because FELCH describes the reactor outlet stream as hot oxidized effluent after the feed mixture is heated and introduced into the reactor. Response to Arguments Applicant’s arguments with respect to claim(s) 1–5 and 11–15 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument. Conclusion Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). 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 TAK L. CHIU whose telephone number is (703)756-1059. The examiner can normally be reached M-F: 9:00am - 6:00pm (CST). Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, PREM C. SINGH can be reached at (571)272-6381. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /TAK L. CHIU/ Examiner, Art Unit 1777 /KRISHNAN S MENON/ Primary Examiner, Art Unit 1777
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Prosecution Timeline

Jan 09, 2023
Application Filed
Aug 22, 2025
Non-Final Rejection — §103
Nov 20, 2025
Response Filed
Feb 14, 2026
Final Rejection — §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

3-4
Expected OA Rounds
53%
Grant Probability
90%
With Interview (+37.2%)
3y 8m
Median Time to Grant
Moderate
PTA Risk
Based on 32 resolved cases by this examiner. Grant probability derived from career allow rate.

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