DETAILED ACTION
Claim Rejections - 35 USC § 103
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.
Claims 15, 17, 18, 21-23, 27, 28 is/are rejected under 35 U.S.C. 103 as being unpatentable over Gangoli (US 9657945 B2) in view of Khinkis (US 5725366 A).
Regarding claim 15, Gangoli discloses a method for combusting a fuel gas with an oxidant by using a burner assembly comprising a burner block (Fig. 5, 12), a burner (one of the burners 20; e.g., top burner 20 of Fig. 2B) and a lance (another one of the burners 20, e.g., bottom burner 20 of Fig. 2B), the method comprising:
providing via a burner (one of the burners 20; e.g., top burner 20 of Fig. 2B) a main gas flow for a combustion in a furnace (abstract; see Fig. 10 showing combustion, i.e., flame 142/152, in the furnace), wherein the main gas flow comprises conducting a main part of a fuel gas (fuel F1 entering the valve 23) and a first part of an oxidant (oxidant F2 entering the valve 28) through a channel (Fig. 2B: bottom channel 24; note: there are four channels total, as shown by Fig. 3) in the burner and through the burner block (Fig. 1B; 12) to an outlet area (outlet of the channel) for the combustion; and
providing via a lance (another one of the burners 20, e.g., bottom burner 20 of Fig. 2B) a staging gas flow for the combustion in the furnace, wherein the staging gas flow is adjustable (Fig. 2B: via valves or by adjustment of the fuel supply F1) and comprises supplying an auxiliary part of the fuel gas (split portion of F1 just downstream the valve 23) from the main part of the fuel gas into the lance, and a second part of the oxidant (split portion of F2 just downstream the valve 28) into the lance for conducting the auxiliary part of the fuel gas and the second part of the oxidant from the lance through another channel (Fig. 2B: top channel 24) through the burner block to another outlet area (outlet of the another channel) for the combustion, and preheating the main gas flow in the burner block and the staging gas flow in the burner block before being provided to the combustion in the furnace (see comment 1);
wherein the main part of the fuel gas is larger than the auxiliary part of the fuel gas, and wherein the auxiliary part of the fuel gas provided via the lance is selected from the group consisting of not more than 20% of the total fuel gas provided to the combustion, not more than 10% of the total fuel gas provided to the combustion, not more than 5% of the total fuel gas provided to the combustion, and not more than 2% of the total fuel gas provided to the combustion (see comment 2 below)
Comment 1.
Each burner/lance 20 is always in the state of combusting fuel (col. 2, lines 53-55 and col. 8, line 54 – col. 9, line 6), and the heat of the combustion is so hot that it is “sufficient to maintain combustion in each burner element 20, so as to provide a mechanism for immediate ignition when a burner element 20 is switched from a passive state to the active state” (col. 9, lines 1-6). This means that the burner 20 is always hot (~1100 deg. F for natural gas ignition temperature), and would preheat the fuel gas and oxidant flowing separately through the burner, before mixing and igniting outside the burner 20.
Comment 2. Fig. 3 shows an example firing sequence where, at any one instance, one burner is in an active state and the other three burners are in a passive state (col. 12, lines 21-28). Each burner can be in an active state or a passive state. A burner in the active state receives between 5- 40 times the fuel of a burner in the passive state (col. 4, lines 4-10). In other words, the auxiliary part of the fuel gas (i.e., the fuel flow rate of a single burner in a passive state), is about 2.3% – 12.5 % of the total fuel gas.
Moreover, the exact percentage is a matter of optimization. Gangoli discloses that the passive flow rate (auxiliary flow) must be greater than zero, and must be “sufficient to maintain combustion in each burner element 20, so as to provide a mechanism for immediate ignition when a burner element 20 is switched from the passive state to the active state” (col. 9, lines 3-6). The passive flow rate must also be sufficient to protect the nozzle 22 from entry of foreign materials (col. 9, lines 6-8).
Gangoli fails to disclose:
where the burner passes the main gas flow and oxidant for precombustion in the channel; and
where the lance passes the auxiliary part of the fuel gas and the second part of the oxidant for precombustion, thereby precombusting the auxiliary part of the fuel gas with the second part of the oxidant before providing the staging gas flow via the burner block to the combustion in the furnace.
Khinkis teaches a method for combusting fuel gas with an oxidant by using a burner assembly, the method comprising:
precombusting (Fig. 1, 20) a portion the fuel gas (23a) with a portion of oxidant (24a) in a channel of the burner (and in the channel defined by the burner block) before providing the gas flow via the burner block to the outlet (outlet of the channel in the burner block), and then to the combustion zone (22).
Khinkis teaches that this feature produces a high heat transfer, low NOx flame (see abstract and col. 2, lines 38-54).
It would have been obvious to a person skilled in the art at the time of effective filing of the application where each of Gangoli’s four burners/lances (20) (i.e., the burners located in the burner block) are modified to have a configuration similar to the one shown in Fig. 1 of Khinkis. The motivation to combine is to provide a burner assembly that produces a high heat transfer, low NOx flame, as taught by Khinkis.
The resulting modification discloses where the burner passes the main gas flow and oxidant through a channel in the burner for precombustion in the channel and through the burner block to an outlet area for the combustion; and where the lance passes the auxiliary part of the fuel gas and the second part of the oxidant through another channel in the burner/lance for precombustion and through the burner block to another outlet area for the combustion, thereby precombusting the auxiliary part of the fuel gas with the second part of the oxidant before providing the staging gas flow via the burner block to the combustion in the furnace.
The precombustion in each of the burner and lance would also preheat the main gas flow in the burner and the staging gas flow in the burner block before being provided to the combustion in the furnace (see Fig. 1 of Khinkis; the precombustion chamber 20 would preheat the gas and oxygen flow circulating around the precombustion chamber 20)
Regarding claim 17, Gangoli discloses wherein the first part of the oxidant provided via the burner is selected from the group consisting of not more than 95% of the total oxidant provided to the combustion, not more than 90% of the total oxidant provided to the combustion, not more than 80% of the total oxidant provided to the combustion, not more than 70% of the total oxidant provided to the combustion, and not more than 60% of the total oxidant provided to the combustion (For the Fig. 1B/2B embodiment, oxygen is divided up equally among the four burners; therefore, the active burner would receive about 25% of the total oxygen).
Regarding claim 18, Gangoli discloses wherein the second part of the oxidant provided via the lance is selected from the group consisting of at least 5% of the total oxidant provided to the combustion, at least 10% of the total oxidant provided to the combustion, at least 20% of the total oxidant provided to the combustion, at least 30% of the total oxidant provided to the combustion, and at least 40% of the total oxidant provided to the combustion (For the Fig. 1B/2B embodiment, oxygen is divided up equally among the four burners; therefore, the passive burner would receive about 25% of the total oxygen)
Regarding claim 21, Gangoli discloses wherein an amount of the auxiliary part of the fuel gas in the staging gas flow is adjustable (via valves 23 and 26).
Regarding claim 22, modified Gangoli discloses (see citations and modification made for the rejection of claim 15, unless otherwise noted) a burner assembly for combusting a fuel gas with an oxidant, the burner assembly comprising:
a burner block comprising a main gas flow channel leading to an outlet area at a combustion zone (Gangoli discloses a main gas flow channel, defined by the burner block 12, for the burner 20; Khinkis also discloses a main gas flow channel in the burner block, which is defined by the burner block), and a staging gas flow channel leading to another outlet area at the combustion zone (in the combination, the staging gas flow channel has the same structure as the main gas flow channel);
a burner for providing a main gas flow to the main gas flow channel for a combustion in a furnace, wherein the main gas flow comprises a main part of a fuel gas and a first part of an oxidant for precombustion in the main gas flow channel and through to the outlet area before being provided to the combustion zone (see Fig. 1 of Khinkis teaching a precombustion zone 20 located inside the main gas flow channel);
a lance for providing a staging gas flow to the staging gas flow channel (the staging gas flow channel is equivalent to the “another channel in the lance” in claim 15), wherein the staging gas flow is adjustable and comprises supplying an auxiliary part of the fuel gas from the main part of the fuel gas into the lance, and a second part of the oxidant into the lance, the lance constructed and arranged to conduct the auxiliary part of the fuel gas and the second part of the oxidant for another precombustion through the staging gas flow channel and through the burner block to the another outlet area for combustion before being provided to the combustion zone (Khinkis teaches precombustion 20 through the staging gas flow channel/main gas flow channel and through the burner block);
an injection element (Fig. 1 of Khinkis: injector for fuel from inlet 23a) for injecting the auxiliary part of the fuel gas to the second part of the oxidant (Fig. 1 of Khinkis: oxygen from inlet 24a) in the lance before providing the staging gas flow via the staging gas flow channel in the lance to the combustion zone (Fig. 1 of Khinkis: 22) (note: this feature is part of the combination made for the rejection of claim 15); and
wherein the main part of the fuel gas is larger than the auxiliary part of the fuel gas, and wherein the auxiliary part of the fuel gas provided via the lance is selected from the group consisting of not more than 20% of the total fuel gas provided to the combustion, not more than 10% of the total fuel gas provided to the combustion, not more than 5% of the total fuel gas provided to the combustion, and not more than 2% of the total fuel gas provided to the combustion.
Regarding claim 23, Gangoli discloses control means (23 or 26) for adjusting an amount of the auxiliary part of the fuel gas in the staging gas flow (note: the control means are interpreted under 112f to be a computing unit, a control unit, or a valve).
Regarding claim 27, Figs. 1A/1B of Gangoli fails to disclose wherein the burner comprises a flat flame burner. However, Figs. 5A(e) and 5B(e) of Gangoli show flat flame burners (20).
It would have been obvious to a person skilled in the art at the time of effective filing of the application to modify the Fig. 1A or 1B embodiment of Gangoli to have flat flame burners to enhance heat transfer while reducing NOx emissions (see col. 2, lines 22-30 US Pat. No. 5611682, which was referenced in col. 15, lines 10-11 of Gangoli).
Regarding claim 28, modified Gangoli discloses a furnace comprising the burner assembly according to claim 22 (Gangoli, abstract).
Claim 25 is/are rejected under 35 U.S.C. 103 as being unpatentable over Gangoli (US 9657945 B2) in view of Khinkis (US 5725366 A), as applied to claim 22, and as evidenced by Joshi (US 5725367 A).
Regarding claim 25, Gangoli discloses wherein the outlet area (20) and the another outlet area each comprise a substantially rectangular shape (Fig. 5A - C) EXCEPT wherein a ratio of width to height is selected from the group consisting of at least 3:1, at least 4:1, at least 5:1, at least 6:1, and at least 6.5:1.
However, it has been held that “[w]here 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) (quoting In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). It has been further held that "[a] particular parameter must first be recognized as a result-effective variable, i.e. a variable which achieves a recognized result, before determination of the optimum or workable ranges of said variable might be characterized as routine experimentation. Refer to MPEP §2144.05(II)(B)(quoting In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977).
In this case, the size and shape of the opening determines the shape of the flame (see Figs. 2-4, 6 of Joshi). Joshi teaches that the shape of the flame affects the heat distribution, fuel and oxidant velocities, fuel efficiency, and more (col. 1, lines 12- 15 and col. 3, line 18- col. 4, line 9). Therefore, the claimed ratio is a matter of optimizing one or more of the aforementioned variables.
Response to Arguments
Applicant asserts the following on page(s) of the 4/22/2026 Remarks:
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Examiner’s response:
The Examiner respectfully disagrees that the amended claims require precombustion in the different channels before the burner block. The claims permit that the precombustion occurs in both the different channels and inside the burner block simultaneously.
Further, the combination discloses four separate precombusting streams and these precombusting streams would come into contact with each other for the first time outside the burner block, inside the combustion zone of the furnace.
Conclusion
THIS ACTION IS MADE FINAL. 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 JASON LAU whose telephone number is (571)270-7644. The examiner can normally be reached Mon-Fri 9:00-6:00.
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/JASON LAU/Primary Examiner, Art Unit 3762
