Prosecution Insights
Last updated: April 19, 2026
Application No. 17/745,438

Sulfur Recovery Unit with Fuel Gas Firing

Non-Final OA §112
Filed
May 16, 2022
Examiner
IQBAL, SYED TAHA
Art Unit
1736
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Saudi Arabian Oil Company
OA Round
1 (Non-Final)
80%
Grant Probability
Favorable
1-2
OA Rounds
2y 9m
To Grant
99%
With Interview

Examiner Intelligence

Grants 80% — above average
80%
Career Allow Rate
659 granted / 823 resolved
+15.1% vs TC avg
Strong +22% interview lift
Without
With
+22.2%
Interview Lift
resolved cases with interview
Typical timeline
2y 9m
Avg Prosecution
28 currently pending
Career history
851
Total Applications
across all art units

Statute-Specific Performance

§101
0.6%
-39.4% vs TC avg
§103
40.1%
+0.1% vs TC avg
§102
24.5%
-15.5% vs TC avg
§112
27.1%
-12.9% vs TC avg
Black line = Tech Center average estimate • Based on career data from 823 resolved cases

Office Action

§112
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 . Election/Restrictions Applicant’s election without traverse of Group 1, claims 1-12 in the reply filed on 08/15/2025 is acknowledged. Claim Objections Claim 1 is objected to because of the following informalities: In claim 1, to enhance clarity of the claim, the recitation relating to feeding fuel gas instead of the acid gas should indicate that this step occurs after the feeding acid gas step and the converting step. Appropriate correction is required. Claim Rejections - 35 USC § 112 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 1-12 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. Claims 1 and 8 recite “first air” and “second air”, which lack antecedent basis. The claims talk about adjusting the first air and adjusting the second air as if these elements were already discussed in the claim. It is unclear how a flow rate of a component can be adjusted until it is first introduced into the system. Furthermore, it is unclear if these terms are referring back to previously discussed elements. Claims 2-7 and 9-12 are rejected due to the virtue of their dependence on claims 1 and 8. Allowable Subject Matter Claims 1 and 8 would be allowable if rewritten or amended to overcome the rejection(s) under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), 2nd paragraph, set forth in this Office action. Claims 2-7 and 9-12 would be allowable if rewritten to overcome the rejection(s) under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), 2nd paragraph, set forth in this Office action and to include all of the limitations of the base claim and any intervening claims. The following is a statement of reasons for the indication of allowable subject matter: Claim 1 requires a method of operating an SRU where fuel gas is fed instead of acid gas to the reaction furnace. Additionally, a first air flow rate is adjusted based on the composition of the fuel gas and a second air flow rate is adjusted based on oxygen concentration in the furnace discharge. Claim 8 requires a method of operating an SRU with a first operation mode or ‘normal’ operation where acid gas is converted in a furnace and a second operation more or ‘special’ operation where acid gas is discontinued and fuel gas is fed. Additionally, a first air flow rate is adjusted based on the composition of the fuel gas and a second air flow rate is adjusted based on oxygen concentration in the furnace discharge. O’Connell US10246329, the closest prior art reference, teaches a process for recovering sulfur from hydrogen sulfide (Abstract). The reference teaches a sulfur recovery unit 1 (Col. 5 lines 15-16) with a furnace 10 where hydrogen sulfide is converted (Col. 5, lines 59-61). This reads on a thermal stage of the claimed SRU. The reference further teaches an embodiment with a heat exchanger stage 20 coupled with a catalytic extension section 24 (Col. 6, line 65 thru Col. 7, line 20). This section 24 reads on the catalytic section of the claim. The reference further teaches adjusting a flow rate of air based on the composition of a tail gas (Col. 2, lines 51-55). In essence the reference only teaches a single air feed with the acid gas and does not indicate that the acid gas is stopped at any point in the process where feed gas is supplied without the acid gas. Additionally only a single catalytic stage is taught. However, there is no teaching or suggestion from the prior art for “feeding fuel gas instead of the acid gas to the reaction furnace ;adjusting flow rate of first air fed to the reaction furnace based on composition of the fuel gas”, as required by claim 1. Additionally there is no teaching or suggestion from the prior art for “discontinuing the feeding of the acid gas to the reaction furnace in a special operation comprising a fuel-gas firing mode of the SRU that is not the normal operation; feeding fuel gas to the reaction furnace in the special operation; adjusting flow rate of first air fed to the reaction furnace based on composition of the fuel gas;”, as required by claim 8. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to SYED TAHA IQBAL whose telephone number is (571)270-5857. The examiner can normally be reached M-F; 7-5. 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, Anthony Zimmer can be reached at (571) 270-3591. 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. /SYED T IQBAL/Examiner, Art Unit 1736 /ANTHONY J ZIMMER/Supervisory Patent Examiner, Art Unit 1736
Read full office action

Prosecution Timeline

May 16, 2022
Application Filed
Oct 31, 2025
Non-Final Rejection — §112 (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

1-2
Expected OA Rounds
80%
Grant Probability
99%
With Interview (+22.2%)
2y 9m
Median Time to Grant
Low
PTA Risk
Based on 823 resolved cases by this examiner. Grant probability derived from career allow rate.

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