DETAILED ACTION
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 July 2026 has been entered.
Response to Amendment
Amendment to claim 1 and cancelation of claim 8 are noted.
Response to Arguments
Applicant's arguments filed 10 March 2026 (as entered with RCE filed 9 July) have been fully considered but they are not persuasive.
Applicant argues that: (1) Wijnja discloses pre-heating the feedstock within the convection bank, not outside the cracker; (2) Purola appears to provide the streams used for pre-heating from utilities typically available at chemical/refining plants and does not teach the effluent containing olefins may be used to provide several types pressurized steam which may be used in the pre-heating of the feed stream outside the cracker furnace.
These arguments are not found persuasive.
Wijnja discloses that the feedstock may be subjected to initial preheating before entering a high temperature coil of the convection section (see [0012]; [0017]-[0018]), but does not disclose the specifics thereof. Purola provides the motivation for specifics regarding heating a cracker feed before its entry into the convection section, namely that flue gas stack temperature may be reduced, improving thermal efficiency in the furnace. The office maintains this position.
With respect to the newly added limitations, these are addressed in the updated rejection below.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-7 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Claim 1 has been amended to recite that “the effluent containing olefins may be used to provide several types of pressurized steam which may be used in said pre-heating of the feed stream containing hydrocarbons outside the cracker furnace,” the scope of which is not supported by the specification as originally filed.
The office notes that the specification describes the effluent containing olefins exchanging heat with water in a transfer line exchanger (TLE) to provide a stream containing superheated steam. This superheated stream is then sent back to a bank in the convection section for further heating and then provided to a steam turbine. Stages of the steam turbine generate high pressure steam, medium pressure steam, low pressure steam, etc. (see Fig. 2; p. 28, lines 8-33). In other words, it is the turbine stages that are responsible for creating “several different types of steam”, not the effluent containing olefins. The effluent containing olefins is disclosed as creating one type of steam – superheated steam. Thus, the claim limitation is broader in scope than what is supported in the specification.
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1-7 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Regarding claim 1, by recitation of “may be used” it is unclear whether or not the limitations which follow are required by the claimed embodiment.
Regarding claims 4 and 5, it is unclear how the limitations therein relate to the newly added limitations to claim 1, in particular with respect to the heat exchange in the first TLE to provide pressurized steam and the generating pressurized steam from the pre-heated utility water through indirect heat exchange, respectively. Is Applicant intending to further specify the nature of the flow of effluent containing olefins and the providing of steam (refer to the rejection of claim 1 under 35 USC 112(a) above, denoting the office’s understanding of the process flow of reaction effluent and water/steam)? This interpretation has been adopted for the purpose of examination.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1-7 are rejected under 35 U.S.C. 103 as being unpatentable over Wijnja et al (US 2022/0372377) in view of Purola (US 2021/0171836).
Regarding claims 1, 3, 5 and 7, Wijnja discloses a process for producing olefins from a feed stream containing hydrocarbons by pyrolytic cracking of the hydrocarbons in a cracker furnace 40, comprising (see Abstract; Fig. 1; [0041]-[0042]):
pre-heating the feed stream outside of the cracker furnace (see [0012]; [0017]-[0018]);
feeding the pre-heated feed stream to a tube (high temperature coil 26) in a convection section 20 of the furnace;
further pre-heating the pre-heated feed stream in the convection section;
feeding the further pre-heated feed stream to a tube 11 in a radiant section 10 of the cracker furnace;
pre-heating an oxygen containing stream (combustion air 6 in preheater 27 of the convection section);
contacting the pre-heated oxygen containing stream with a fuel gas 5 in a burner 12 in the radiant section;
pyrolytic cracking the feed stream in the radiant section resulting in an effluent containing olefins;
pre-heating utility water 3 outside the cracker furnace (in steam drum 33); and
generating pressurized steam from the pre-heated utility water through indirect heat exchange with effluent from the radiant section (in TLE 36).
Furthermore, steam from TLE 36 thereafter flows through steam drum 33 to generate saturated high pressure steam 4, and super heater 25 to generate superheated steam (see [0041]), considered to teach the limitation of the cracker effluent being used to provide several types of pressurized steam.
Wijnja discloses initial steps of pre-heating the feedstock prior to entry into a first high temperature coil of the convection section (see [0006]; [0012]; [0017]-[0018]), as discussed above, but does not explicitly disclose the specifics thereof, i.e., wherein the pre-heating outside the cracker furnace is performed before feeding the feed stream to a tube in the convection section of the cracker furnace for the first time, as claimed.
Purola, like Wijnja, is directed to pyrolysis and heat integration thereof (see Abstract; [0039]). In particular, Purola discloses pre-heating the feed to a furnace inlet temperature in a heat exchanger prior to passing into the convection section of the furnace because it enables reduction of flue gas stack temperature, which, in turn, accounts for improved thermal efficiency in the furnace. Streams used for pre-heating include low pressure steam (i.e., pressurized steam used in the pre-heating of the feed stream outside of the cracker furnace) (see [0122]; [0154]).
It would have been obvious to a person of ordinary skill in the art at the time of filing the instant claimed invention to modify the process of Wijnja by pre-heating the feedstock by exchange with low pressure steam prior to entry into the convection section, as suggested by Purola, in order to allow for reduction of flue gas stack temperature and improve thermal efficiency of the furnace. Specific selection of steam source(s) readily available in the process flow of Wijnja to carry out the function of pre-heating the feed, as suggested by Purola, would have been obvious to and required nothing more than routine experimentation for a person of ordinary skill in the art.
Regarding claim 2, Wijnja discloses wherein the feed stream containing hydrocarbons is pre-heated outside the cracker furnace to a temperature up to 550°C, e.g., around 555°C (see [0021], outlet temperature on the cold side of the TLE is kept to around 550°C; [0043]), overlapping the claimed range.
Regarding claim 4, Wijnja discloses two TLEs 35, 36 arranged in series, where effluent from the radiant section passes through the first and then the second in series. In the first TLE, the effluent exchanges heat with the feed stream and, in the second, the effluent exchanges heat with utility water to provide pressurized steam (see [0041]). Thus, while Wijnja discloses the same types of heat exchange with the effluent, the order is reversed. Nevertheless, selection of any order of performing process steps is prima facie obvious in the absence of new or unexpected results. In re Burhans, 154 F.2d 690, 69 USPQ 330 (CCPA 1946).
Regarding claim 6, Wijnja does not explicitly disclose the temperature to which the oxygen containing stream is pre-heated. However, the reference discloses that the pre-heating step functions to raise the adiabatic flame temperature and make the firebox more efficient (see [0042]). A person of ordinary skill in the art would optimize, by routine experimentation, the temperature to which the oxygen containing stream is preheated which is associated with efficient operation of the firebox (burner). Absent a showing of criticality or unexpected results, the claimed preheating temperature is not considered to patentably distinguish the instant claims over the cited prior art.
Conclusion
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/Renee Robinson/Primary Examiner, Art Unit 1772
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