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 .
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 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.
Claims 1-11, 12, 13, and 16-18 are rejected under 35 U.S.C. 103 as being unpatentable over Birmingham (US-Pub 2011/0303135) in view of Huang C (CN108469036A).
Regarding claim 1, Birmingham discloses an air preheater (100, fig 2) for a solid fuel-fired power plant (148, fig 2), comprising: a housing (114, fig 1) having (a) a flue gas inlet (124, fig 1) and a flue gas outlet (126, fig 1) adapted for directing a flue gas stream (224,226, fig 1) through the housing and (b) an air inlet (130, fig 1)and an air outlet (132, fig 1) adapted for directing an air stream (230, 232, fig 1)through the housing; a rotary regenerative heating element (112, fig 1) received in the housing and adapted to transfer heat from the flue gas stream to the air stream; a plurality of flow control valves (163 and 164, fig 3) in the air stream upstream of the rotary regenerative heating element; and a controller (158, fig 2) adapted to independently open and close each valve of the plurality of flow control valves in order to provide an air flow shadow extending downstream over a selected portion of the rotary regenerative heating element to restrict flow of cooling air over the selected portion while simultaneously maintaining an air flow over a remainder of the rotary regenerative heating element to support operation of the solid fuel-fired power plant (fig 3, when they are closed, the area behind 164 and 163 would form an air flow shadow, while the open space 165 would form an open portion maintaining airflow), and reducing the surface area of the preheater exposed to air such that a specific section of the preheater will have its temperature increased such that acids will not form on the preheater and any ash is removed from the preheater (par. 0046), wherein the area without damping assemblies can be made smaller (par. 0053)
Birmingham does not explicitly disclose where controller operation of blocking certain sections of a heat exchanger to increase its relative heat will burn off previously deposited ammonium bisulfate, and said plurality of flow control valves being adapted to control all flow of the air stream to the rotary regenerative heating element.
Huang C has an air preheater (1, fig 1) for a solid fuel-fired power plant with a plurality of flow control valves (7, fig 1) which are adapted to control all flow of the air stream to the rotary regenerative heating element (fig 1, the flow control valves fully cover the entrance when they are all closed), which restrict flow of cooling air over a selected portion of the heating element in the same manner as Birmingham, whereby any ammonium bisulfate previously deposited on the selected portion is decomposed to loose dry ash (page 2, par. 2 NH4HSO4 is Ammonium Bisulfate). This means that during operation, the control system of blocking flow area to increase temperature would allow for the decomposition of ammonium bisulfate and the regenerative heating element may be kept free of ammonium bisulfate in its entirety.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the area with no damping assembly disclosed by Birmingham having the whole entrance be covered with louvres to control the flow over the whole entrance based on the teachings of Huang C. One of ordinary skill in the art would recognize that dampers to cover the entrance completely are regularly used to prevent contamination when not running and to suppress fires in case of emergency.
Regarding claim 2, Birmingham discloses wherein the controller is configured to (a) maintain all of the plurality of air flow control valves in an open state in response to a first load state of the solid fuel-fired power plant and (b) close a first number of valves of the plurality of air flow control valves in response to the second load state of the solid fuel-fired power plant (par. 0045, the first load state when all the valves are open, the second load state where one of 163 and 164 are open).
Regarding claim 3, Birmingham discloses wherein the controller is further configured to close a second number of the plurality of air flow control valves (where both 163 and 164 are closed, leaving only the open space in 165 for airflow) in response to the third load state of the solid fuel-fired power plant wherein the second number is greater than the first number (par. 0059).
Regarding claim 4, Birmingham discloses wherein the first load state is between 70-100% of full load (par. 0057, at 100% of full load there is no need to close any valves, so the first load state is where they are all open).
Regarding claim 5, Birmingham discloses wherein the second load state is between 50-70% of full load (par. 0035, boiler can be set running at 60% load).
Regarding claim 6, Birmingham discloses wherein the third load state is between 25-50% of full load (table 1, 30% load case).
Regarding claim 7, Birmingham as modified by Huang discloses wherein the controller is adapted to periodically open any closed valves and close at least one different valve of the plurality of air flow valves to extend a new air flow shadow downstream over a different selected portion of the rotary regenerative heating element (par. 0055) whereby the ammonium bisulfate previously deposited on the different selected portion of the rotary regenerative heating element is decomposed to loose dry ash.
Regarding claim 8, Birmingham as modified by Huang discloses wherein the controller is adapted to periodically open any closed valves and close at least one different valve of the plurality of air flow valves to extend a new air flow shadow downstream over a different selected portion of the rotary regenerative heating element (par. 0055) whereby the ammonium bisulfate previously deposited on the different selected portion of the rotary regenerative heating element is decomposed to loose dry ash.
Regarding claim 9, Birmingham discloses wherein each of the valves of the plurality of flow control valves include louvers (163, fig 3) controlled by actuators (166, fig 3) connected to and controlled by the controller.
Regarding claim 10, Birmingham discloses an air blower (188, fig 2) adapted for blowing the air stream through the housing.
Regarding claim 12, Birmingham discloses A method of decomposing and removing ammonium bisulfate from a rotary regenerative heating element of an air preheater (100, fig 2) for a solid fuel-fired power plant (148, fig 2), comprising: restricting air flow over a selected portion of the rotary regenerative heating element while simultaneously maintaining air flow over a remainder of the rotary regenerative heating element to support operation of the solid fuel-fired power plant (par. 0041) such that a selected portion of the preheater will have its temperature increased such that acids will not form on the preheater (par. 0046); and subsequently directing flue gas over the selected portion to sweep the loose fly ash from the selected portion of the rotary regenerative heating element (par. 0038), wherein the area without damping assemblies can be made smaller (par. 0053)
Birmingham does not explicitly disclose where the method of blocking certain sections of a heat exchanger to increase its relative heat will burn off previously deposited ammonium bisulfate, and said plurality of flow control valves being adapted to control all flow of the air stream to the rotary regenerative heating element.
Huang C has an air preheater (1, fig 1) for a solid fuel-fired power plant with a plurality of flow control valves (7, fig 1) which are adapted to control all flow of the air stream to the rotary regenerative heating element (fig 1, the flow control valves fully cover the entrance when they are all closed), which restrict flow of cooling air over a selected portion of the heating element in the same manner as Birmingham, whereby any ammonium bisulfate previously deposited on the selected portion is decomposed to loose dry ash (page 2, par. 2 NH4HSO4 is Ammonium Bisulfate). This means that during operation, the method of blocking flow area to increase temperature would allow for the decomposition of ammonium bisulfate.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the area with no damping assembly disclosed by Birmingham having the whole entrance be covered with louvres to control the flow over the whole entrance based on the teachings of Huang C. One of ordinary skill in the art would recognize that dampers to cover the entrance completely are regularly used to prevent contamination when not running and to suppress fires in case of emergency.
Regarding claim 13, Birmingham as modified by Huang discloses periodically restricting air flow over a different selected portion of the rotary regenerative heating element (par. 0055) whereby ammonium bisulfate previously deposited on the different selected portion is decomposed to the loose, dry ash while maintaining air flow over a different remainder of the rotary regenerative heating element to support operation of the solid fuel-fired power plant; and subsequently directing flue gas over the different selected portion to sweep the loose, dry ash from the different selected portion of the rotary regenerative heating element (the controller transfers which dampers are opened and closed meaning that a different section will receive air each time).
Regarding claim 16, Birmingham discloses maintaining air flow over all of the rotary regenerative heating element when the solid fuel-fired power plant is operating at first percentage of full load (par. 0057).
Regarding claim 17, Birmingham discloses closing a first number of air flow valves (closing one of 163 and 164, fig 3) to restrict air flow over the selected portion of the rotary regenerative heating element when the solid fuel-fired power plant is operating at the second percentage of full load wherein the second percentage is lower than the first percentage (table 1, 70% load).
Regarding claim 18, Birmingham discloses closing a second number of air flow valves to restrict air flow over the selected portion of the rotary regenerative heating element when the solid fuel-fired power plant is operating at the third percentage of full load (when both 163 and 164 are closed, fig 3), wherein the second number of air flow valves is greater than the first number of air flow valves and the third percentage is lower than the second percentage (table 1, 30% load).
Claims 11, 14, and 15 are rejected under 35 U.S.C. 103 as being unpatentable over Birmingham as modified by Huang C, in view of Huang G (CN 107883392)
Regarding claim 11, Birmingham discloses monitoring temperature at multiple locations around the rotary regenerative heating element (par. 0046), including the temperature of the flue gas stream downstream from the selected portion of the rotary regenerative heating element after the selected portion of the regenerative heating element has been rotated into the flue gas stream (par. 0046, the controller receives temperature readings at various locations from downstream of the heating element in the flue gas stream, which means as the preheater rotates temperature would be taken as it has been rotated into the flue gas stream).
Birmingham does not disclose a temperature sensor is located downstream of the flue gas stream.
Huang G teaches regenerative heating element (fig 1) using a plurality of temperature sensors (outlet temperature sensor, page 5, lines 41-54) provided downstream from the regenerative heating element in the flue gas stream and adapted to measure temperature of the flue gas stream downstream from the selected portion so that both the hot and cold areas of a flue gas exit area can be measured (page 5, lines 41-54).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified temperature sensing system disclosed by Birmingham by using temperature sensors to measure the temperature of the outlet of the flue gas at both hot and cold locations based on the teachings of Huang G. One of ordinary skill in the art would recognize that having multiple temperature probes located around the flue gas outlet would allow for greater control over the operation of the preheater.
Regarding claim 14, Birmingham discloses including rotating the rotary regenerative heating element through a flue gas sector and an air sector (this is well known in the art as the function of a rotary heat exchanger) of the air preheater and monitoring a flue gas temperature at multiple locations throughout the air preheater (par. 0046).
Birmingham does not disclose a temperature sensor located downstream from a selected portion after the selected portion has been rotated.
Huang G teaches a rotary regenerative heating element (fig 1) using a plurality of temperature sensors (outlet temperature sensor, page 5, lines 41-54) provided downstream from the regenerative heating element in the flue gas stream and adapted to measure temperature of the flue gas stream downstream from the selected portion so that both the hot and cold areas of a flue gas exit area can be measured (page 5, lines 41-54), which, when combined with Birmingham, would mean the selected portion of Birmingham after it has been rotated would be measured (the hot and cold regions are both measured, meaning that during rotation the temperatures from each selected portion would be measured).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified temperature sensing system disclosed by Birmingham by using temperature sensors to measure the temperature of the outlet of the flue gas at both hot and cold locations based on the teachings of Huang G. One of ordinary skill in the art would recognize that having multiple temperature probes located around the flue gas outlet would allow for greater control over the operation of the preheater.
Regarding claim 15, Birmingham as discloses rotating the rotary regenerative heating element through a flue gas sector and an air sector of the air preheater (this is well known as the function of a rotary heat exchanger) and monitoring the flue gas temperature at multiple places throughout the rotary heat exchanger (par. 0046).
Birmingham does not disclose a temperature sensor located downstream from a different selected portion after the selected portion has been rotated.
Huang G teaches a rotary regenerative heating element (fig 1) using a plurality of temperature sensors (outlet temperature sensor, page 5, lines 41-54) provided downstream from the regenerative heating element in the flue gas stream and adapted to measure temperature of the flue gas stream downstream from the selected portion so that both the hot and cold areas of a flue gas exit area can be measured (page 5, lines 41-54), which, when combined with Birmingham, would mean the different selected portion of Birmingham would be measured (the hot and cold regions are both measured, meaning that during rotation the temperatures from each selected portion would be measured).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified temperature sensing system disclosed by Birmingham by using temperature sensors to measure the temperature of the outlet of the flue gas at both hot and cold locations based on the teachings of Huang G. One of ordinary skill in the art would recognize that having multiple temperature probes located around the flue gas outlet would allow for greater control over the operation of the preheater.
Response to Arguments
Applicant's arguments filed 12/22/2025 have been fully considered but they are not persuasive. Applicant argues that Birmingham and Huang C do not disclose wherein the regenerative heating element may be kept free of ammonium bisulfate in its entirety, as Birmingham does not disclose wherein the regenerative heating element can be covered completely. Applicants arguments are not persuasive for a plurality of reasons. Firstly, the newly added limitation represents intended use, not a change in structure, and the structure of Birmingham as modified by Huang C is the same as that claimed, meaning it performs the claimed function. Second, Birmingham states that the increase in air velocity by closing dampers also removes fouling (par. 0034), this means that even without covering the whole thing, areas exposed to the higher velocity air aka not covered by dampers, would meet the limitation as those areas also have ammonium bisulfate removed. Thirdly, as stated in the rejection, Birmingham states that the area of the opening may be reduced, and in the rejection Birmingham is modified by Huang C to have the entire heating element be covered by Dampers, making the argument moot. Lastly, the heat exchanger is a rotary heat exchanger, this means that as the parts rotate, the heat exchanger will alternatively be covered by dampers and not depending on where it is in the rotation cycle.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to SEAN V MEILLER whose telephone number is (571)272-9229. The examiner can normally be reached 7am-5pm.
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/SEAN V MEILLER/Examiner, Art Unit 3741 /DEVON C KRAMER/Supervisory Patent Examiner, Art Unit 3741