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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 10/9/2025 has been entered.
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) from the burner through a channel (Fig. 2B: bottom channel 24; note: there are four channels total, as shown by Fig. 3) in the burner block to an outlet area (outlet of the channel); 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) in the burner block to another outlet area (outlet of the another channel), 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 explicitly state:
where the burner passes the main gas flow and oxidant for precombustion; 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 in the burner block 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 block (the burner block is shown by the hash lines) (Fig. 1 shows where the burner/lance is located within the burner block, and where the precombustion zone 20 is inside 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 block for precombustion to an outlet area; 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 block for precombustion to another outlet area, thereby precombusting the auxiliary part of the fuel gas with the second part of the oxidant in the burner block 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, and a staging gas flow channel leading to another outlet area;
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 burner block;
a lance for providing a staging gas flow to the staging gas flow channel for the combustion in the furnace, 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 from the lance through the staging gas flow channel for precombustion to the another outlet area, thereby precombusting the auxiliary part of the fuel gas with the second part of the oxidant in the burner block before providing the staging gas flow via the burner block to the combustion in the furnace, 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;
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 in the furnace (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:
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Examiner’s response:
Gangoli discloses a burner system suitable for a glass melting furnace (col. 1, lines 33-35). Khinkis also teaches that the method is suitable for a glass melting furnace (see “Description of Prior Art”). Khinkis teaches precombusting a portion of the fuel and oxygen to produce a luminous high heat transfer low NOx flame (see col. 2, lines 38-54). A person skilled in the art would have been motivated to make the proposed modification, where each of the four burners 20 of Gangoli have a configuration similar to Fig. 1 of Khinkis, so that each of the burners in Gangoli can output a luminous high heat transfer low NOx flame. As it relates to the claims, one of the four burners can be the claimed burner and another one of the four burners can be the claimed lance. Moreover, all four of the burners are located within the burner block (Fig. 5A of Gangoli; 12).
Conclusion
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/JASON LAU/Primary Examiner, Art Unit 3762