Device and method for removing NOx in flue gas by utilizing CO generated by boiler combustion

Abstract

The embodiment of the invention provides a device for removing NOx in flue gas through CO generated by boiler combustion. The device comprises a carbon dioxide reduction generator, a mixer and SCR denitration equipment. The carbon dioxide reduction generator communicates with the boiler and the mixer. The carbon dioxide reduction generator is used for catalytically reducing carbon dioxide in flue gas desulfurized by the boiler into carbon monoxide; the mixer is used for mixing carbon monoxide generated by the carbon dioxide reduction generator with air; the SCR denitration equipment comprises a denitration flue, and a reducing agent spraying and mixing part and a CO-SCR denitration catalysis part which are arranged in the flue denitration flue; the denitration flue is communicated with the boiler; the reducing agent spraying and mixing part is communicated with the output end of the mixer and is used for supplementing mixed gas of carbon monoxide and air to the denitration flue; and the CO-SCR denitration catalysis part is used for carrying out denitration treatment on NOx components in the flue gas by utilizing the flue gas generated by the boiler and carbon monoxide in the mixed gas supplemented by the mixer.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the technical field of flue gas denitrification, and specifically relate to a device and method for removing NOx from flue gas by using CO generated by boiler combustion. Background Art

[0002] Ammonia SCR technology (NH3-SCR) using ammonia or urea as a reducing agent is the most widely used selective catalytic reduction NOx technology in industry. At present, almost 95% of coal-fired units have achieved ultra-low NOx emissions. A large number of units have excessive ammonia escape caused by unreasonable denitrification flow field design, guide plate wear, catalyst wear and other reasons, as well as the formation of ammonium bisulfate and subsequent clogging of air preheaters. Therefore, controlling ammonia escape increases the operating difficulty and cost of this technology. On the other hand, traditional coal-fired units need to increase their deep peak-shaving capabilities to release space for new energy construction. In this case, the flue gas temperature of the catalyst of a considerable number of units under low-load conditions is usually lower than the minimum ammonia injection temperature, so that NOx cannot meet emission standards. Therefore, many scholars are also studying alternative technologies for NH3-SCR denitrification.

[0003] CO is a common incomplete combustion product. CO and NOx are almost always present in the flue gas of carbon-based fuel combustion equipment, such as power station boilers, industrial boilers, diesel engines and gasoline engines. CO has strong reducibility, and it is very feasible to use it as a reductant to catalyze the removal of NOx (CO-SCR), especially in the field of flue gas purification such as power station boilers, industrial boilers and steelmaking industries. Therefore, the idea of ​​"controlling harm with harm" and achieving the removal of CO and NOx at the same time has great economic and environmental characteristics. Summary of the invention

[0004] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art, and provide a device and method for removing NOx from flue gas by using CO generated by boiler combustion.

[0005] In a first aspect of an embodiment of the present disclosure, there is provided a device for removing NOx from flue gas by using boiler combustion to generate CO, the device comprising a carbon dioxide reduction generator, a mixer and an SCR denitrification device;

[0006] The carbon dioxide reduction generator is connected to the boiler and the mixer respectively; the carbon dioxide reduction generator is used to catalytically reduce the carbon dioxide in the flue gas after boiler desulfurization into carbon monoxide; the mixer is used to mix the carbon monoxide generated by the carbon dioxide reduction generator with air;

[0007] The SCR denitration equipment includes a denitration flue, and a reducing agent spraying and mixing part and a CO-SCR denitration catalytic part arranged in the flue denitration; the denitration flue is connected with the boiler, and is used to pass the flue gas of the boiler into the CO-SCR denitration catalytic part; the reducing agent spraying and mixing part is connected with the output end of the mixer, and is used to supplement the denitration flue with a mixed gas of carbon monoxide and air;

[0008] The CO-SCR denitration catalyst utilizes the flue gas generated by the boiler and the carbon monoxide in the mixed gas supplemented by the mixer to denitrate the NOx components in the flue gas.

[0009] Optionally, the denitrification flue includes an SCR horizontal flue, an SCR inlet flue, an SCR reactor and an SCR outlet flue; the SCR horizontal flue, the SCR inlet flue, the SCR reactor and the SCR outlet flue are connected in sequence;

[0010] The SCR horizontal flue is connected to the boiler and is used to pass the flue gas of the boiler into the denitrification flue; the reducing agent spray mixing part is arranged in the inlet flue; and the CO-SCR denitrification catalytic part is arranged in the reactor.

[0011] Optionally, also include:

[0012] The guide part is arranged in the denitrification flue, and is used to guide the flue gas so that the flue gas can flow in the denitrification flue at a more uniform speed.

[0013] Optionally, there are multiple guide parts, and the multiple guide parts are arranged in the denitrification flue at intervals.

[0014] Optionally, there are multiple guide parts, and the multiple guide parts are arranged in the denitrification flue at intervals; the raw agent spray mixing part is arranged between two adjacent guide parts.

[0015] Optionally, there are multiple CO-SCR denitration catalyst parts, and the multiple CO-SCR denitration catalyst parts are arranged at intervals in the denitration flue.

[0016] Furthermore, it also includes a flow regulating valve and a CO flow meter;

[0017] The flow regulating valve and the CO flow meter are arranged between the carbon dioxide reduction generator and the mixer; wherein the carbon dioxide reduction generator, the flow regulating valve, the CO flow meter and the mixer are connected in sequence.

[0018] Further, it also includes a dilution fan and an air flow meter;

[0019] The dilution fan, the air flow meter and the mixer are connected in sequence.

[0020] Optionally, the denitrification flue inlet is connected to the economizer outlet flue at the rear of the boiler.

[0021] A second aspect of the embodiments of the present disclosure provides a method for removing NOx from flue gas by generating CO through boiler combustion. The method is implemented according to the above-mentioned device, comprising:

[0022] The carbon dioxide in the boiler desulfurization flue gas is catalytically reduced to carbon monoxide using a carbon dioxide reduction generator;

[0023] mixing the carbon monoxide produced by the carbon dioxide reduction generator with air through a mixer;

[0024] The flue gas generated by the boiler and the carbon monoxide in the mixed gas supplemented by the mixer are used to react with the CO-SCR denitration catalyst to denitrate the NOx components in the flue gas.

[0025] The beneficial effects of the embodiments of the present disclosure include:

[0026] In the present disclosure, on the one hand, the denitration reducing agent (CO) required by the CO-SCR denitration catalyst is directly derived from the boiler flue gas. On the other hand, the CO2 reduction generator is used to generate CO from the boiler flue gas after desulfurization. 2 The catalytic oxidation into CO can supplement the denitrification reducing agent required by the CO-SCR denitrification catalyst in the denitrification flue, thereby providing sufficient denitrification reducing agent for the denitrification treatment of the CO-SCR denitrification catalyst. Furthermore, the two CO sources are combined to remove NO and NO in the flue gas. 2 The purpose is to oxidize CO to CO 2 , achieving the simultaneous removal of pollutants, realizing the idea of ​​"controlling harm with harm", and has great economic and environmental protection characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of a device for removing NOx from flue gas by using CO generated by boiler combustion according to an embodiment of the present disclosure;

[0028] Figure 2 This is a schematic flow chart of a method for removing NOx from flue gas by generating CO through boiler combustion according to another embodiment of the present disclosure.

[0029] In the figure, 1. dilution fan; 2. air flow meter; 3. carbon dioxide reduction generator; 4. flow regulating valve; 5. CO flow meter; 6. mixer; 7. reducing agent spray mixing section; 8. economizer outlet flue; 9. SCR horizontal flue; 10. guide section; 11. SCR inlet flue; 12. SCR reactor; 13. CO-SCR denitrification catalyst section; 14. SCR outlet flue. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0031] The following is a further detailed description of the implementation methods of the present application in conjunction with the accompanying drawings and examples. The detailed descriptions and drawings of the following examples are used to illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments. In the description of the present application, it should be noted that, unless otherwise specified, the meaning of "multiple" is more than two; the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "inside", "outside", etc. is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the error tolerance range. "Parallel" is not parallel in the strict sense, but within the error tolerance range.

[0032] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0033] Related CO removal of NO and NO in flue gas 2 In the application of the technology, there are the following problems: on the one hand, CO-SCR catalyst is currently in the research stage. On the other hand, the CO content produced by the combustion of coal-fired units is relatively low (if the CO content is too high, the boiler combustion will be unstable and water-cooled wall corrosion and other problems will easily occur), which cannot meet the application requirements.

[0034] In view of the above problems, the present invention provides Figure 1As shown, a device for removing NOx from flue gas by using CO generated by boiler combustion includes a carbon dioxide reduction generator 3, a mixer 6 and an SCR denitrification device.

[0035] The carbon dioxide reduction generator 3 is connected to the boiler and the mixer 6 respectively. The carbon dioxide reduction generator 3 is used to catalytically reduce the carbon dioxide in the flue gas after boiler desulfurization into carbon monoxide. The mixer 6 is used to mix the carbon monoxide generated by the carbon dioxide reduction generator 3 with air.

[0036] The SCR denitration equipment includes a denitration flue, and a reducing agent spraying and mixing section 7 and a CO-SCR denitration catalytic section 13 arranged in the flue denitration. The denitration flue is connected to the boiler, and is used to pass the flue gas of the boiler into the CO-SCR denitration catalytic section 13. The reducing agent spraying and mixing section 7 is connected to the output end of the mixer 6, and is used to supplement the denitration flue with a mixed gas of carbon monoxide and air.

[0037] The CO-SCR denitration catalytic unit 13 utilizes the carbon monoxide in the flue gas generated by the boiler and the mixed gas supplemented by the mixer 6 to perform denitration treatment on the NOx components in the flue gas.

[0038] In the present disclosure, on the one hand, the denitration reducing agent (CO) required by the CO-SCR denitration catalytic unit 13 is directly derived from the boiler flue gas. On the other hand, the carbon dioxide reduction generator 3 is used to generate CO from the boiler flue gas after desulfurization. 2 The catalytic oxidation into CO is used to supplement the denitration reducing agent required by the CO-SCR denitration catalyst section 13 in the denitration flue, thereby providing sufficient denitration reducing agent for the denitration treatment of the CO-SCR denitration catalyst section 13. Furthermore, the two CO sources are combined to remove NO and NO in the flue gas. 2 The purpose is to oxidize CO to CO 2 , achieving the simultaneous removal of pollutants, realizing the idea of ​​"controlling harm with harm", and has great economic and environmental protection characteristics.

[0039] In some embodiments, the denitrification flue includes an SCR horizontal flue 9, an SCR inlet flue 11, an SCR reactor 12 and an SCR outlet flue 14, and the SCR horizontal flue 9, the SCR inlet flue 11, the SCR reactor 12 and the SCR outlet flue 14 are connected in sequence.

[0040] The SCR horizontal flue 9 is connected to the boiler and is used to pass the flue gas of the boiler into the denitrification flue. The raw agent spray mixing part is arranged in the inlet flue, and the CO-SCR denitrification catalytic part 13 is arranged in the reactor.

[0041] In some embodiments, a guide part 10 is further included. The guide part 10 is arranged in the denitrification flue and is used to guide the flue gas so that the flue gas flows more evenly in the denitrification flue. In some embodiments, the guide part 10 includes a guide plate, which is specifically a flue gas equalizing plate.

[0042] In some embodiments, there are multiple guides 10, and multiple guides 10 are arranged in the denitrification flue at intervals. In one embodiment, multiple guides 10 are arranged in the denitrification flue at equal intervals. In another embodiment, multiple guides 10 are arranged in the denitrification flue at unequal intervals. Arranging the Dole guide 10 in the denitrification flue can effectively make the flue gas velocity more uniform, which is conducive to the denitrification reaction.

[0043] In some embodiments, there are multiple flow guides 10, and the multiple flow guides 10 are arranged at intervals in the denitrification flue, and the reducing agent spray mixing part 7 is arranged between two adjacent flow guides 10. In one embodiment provided by the present disclosure, the SCR inlet flue 11 is provided with at least two flow guides 10 arranged at intervals, wherein the reducing agent spray mixing part 7 is arranged between two flow guides 10, which is used to uniformly spray the mixed gas of carbon monoxide and air in the mixer 6 into the denitrification flue to supplement the denitrification reducing agent (CO) required by the CO-SCR denitrification catalytic part 13.

[0044] In some embodiments, the reducing agent spraying and mixing portion 7 is a CO spraying grid having a plurality of nozzles.

[0045] In some embodiments, there are multiple CO-SCR denitration catalyst units 13, and multiple CO-SCR denitration catalyst units 13 are arranged in the denitration flue at intervals. Specifically, the CO-SCR denitration catalyst unit 13 has a CO-SCR denitration catalyst. Providing multiple numbers of CO-SCR denitration catalyst units 13 can effectively denitrate the NOx components in the flue gas.

[0046] In some embodiments, a flow regulating valve 4 and a CO flow meter 5 are further included. The flow regulating valve 4 and the CO flow meter 5 are arranged between the carbon dioxide reduction generator 3 and the mixer 6, wherein the carbon dioxide reduction generator 3, the flow regulating valve 4, the CO flow meter 5 and the mixer 6 are connected in sequence. The flow regulating valve 4 and the CO flow meter 5 are arranged to adjust the flow of CO.

[0047] In some embodiments, a dilution fan 1 and an air flow meter 2 are further included. The dilution fan 1, the air flow meter 2 and the mixer 6 are connected in sequence.

[0048] In some embodiments, the inlet of the denitrification flue is connected to the economizer outlet flue 8 at the tail of the boiler. Specifically, the SCR horizontal flue 9 of the denitrification flue is connected to the economizer outlet flue 8.

[0049] Specifically, the tail flue gas after boiler desulfurization contains a large amount of CO 2 , CO 2 The carbon dioxide reduction generator 3 (which is equipped with CO 2 The CO is then measured by a flow control valve 4 and a CO flow meter 5 before entering a mixer 6.

[0050] The air enters the air flow meter 2 through the dilution fan 1 to measure the volume flow, and then enters the mixer 6 to mix with CO. The mixed gas of CO and air is sprayed into the SCR inlet flue 11 through the CO spray grid, fully mixed with NOx in the flue gas, and enters the SCR reactor 12. Among them, the CO generated by boiler combustion is also mixed with NOx in the flue gas through the economizer outlet flue 8, and enters the SCR reactor 12 through the SCR inlet flue 11.

[0051] Furthermore, a CO-SCR denitration catalyst is installed in the SCR reactor 12. CO in the flue gas undergoes a reduction reaction with NOx in the flue gas on the surface of the CO-SCR denitration catalyst to generate harmless N 2 and CO 2 In the present disclosure, the carbon dioxide reduction generator 3 is used to generate CO from the flue gas after boiler desulfurization. 2 The catalytic oxidation to CO can effectively supplement the denitration reducing agent (CO) required by the CO-SCR denitration catalyst unit 13 in the denitration flue, making up for the problem of insufficient CO in the boiler flue gas, thereby providing sufficient denitration reducing agent for the denitration treatment of the CO-SCR denitration catalyst unit 13, so that the entire denitration reaction process does not require the introduction of additional CO gas source. 2 The CO generated after catalytic reduction and the gas after the reaction is completed are free of CO and NOx, achieving the purpose of treating harm with harm and no NH 3 The purpose of denitrification.

[0052] Specifically, the dilution fan 1 is used to extract air, and the air flow meter 2 is used to measure the volume flow of the air drawn in. The carbon dioxide reduction generator 3 is used to reduce the CO in the tail flue gas after desulfurization of the coal-fired unit boiler. 2 Catalytic reduction to CO, wherein the carbon dioxide reduction generator 3 has the ability to convert CO 2 Catalyst for the catalytic reduction of CO.

[0053] The flow regulating valve 4 is used to adjust the flow rate of CO gas generated by catalytic reduction in the carbon dioxide reduction generator 3, and the CO flowmeter 5 measures the volume flow rate of CO gas, wherein CO and air extracted by the dilution fan 1 are evenly mixed in the mixer 6.

[0054] The CO spray grid sprays the mixed gas of CO and air evenly into the SCR inlet flue 11, and the boiler tail economizer outlet flue 8 is connected to the SCR horizontal flue 9 to introduce flue gas into the denitrification flue. A guide plate is provided in the denitrification flue, wherein the guide plate is a flue gas equalizing plate, which can make the flue gas velocity distribution more uniform. The SCR horizontal flue 9, the SCR inlet flue 11, the SCR reactor 12 and the SCR outlet flue 14 are connected in sequence, wherein the CO-SCR denitrification catalyst 13 is provided in the SCR reactor 12, and the CO-SCR denitrification catalyst 13 has a CO-SCR denitrification catalyst.

[0055] Furthermore, the flue gas in the economizer outlet flue 8 at the tail of the boiler contains a portion of CO, NO and NO 2 , this part of CO and NO, NO 2 The gas passes through the SCR horizontal flue 9 and the SCR inlet flue 11 and enters the SCR reactor 12. In the SCR reactor 12, a denitration reaction occurs under the action of the CO-SCR denitration catalyst to generate CO 2 and N 2 And discharged through the SCR outlet flue 14, and enter the subsequent device. Because the CO content inside the economizer outlet flue 8 is low, it may not be able to remove NO and NO in the flue gas. 2 In the present disclosure, the CO to be supplemented is obtained by removing part of the CO in the tail flue gas after the boiler is desulfurized. 2 The product is catalytically reduced to CO, which is then injected into the SCR inlet flue 11 through the CO injection grid to react with part of the NO and NO in the flue gas. 2 After being evenly mixed, the mixture enters the SCR reactor 12, where a denitration reaction occurs under the action of the CO-SCR denitration catalyst to generate CO 2 and N 2 The CO2 is then transported to the subsequent device through the SCR outlet flue 14. That is, the present invention combines two CO sources to remove NO and NO in the flue gas. 2 The purpose is to oxidize CO to CO 2 , achieving simultaneous removal of pollutants.

[0056] like Figure 2 As shown, the second aspect of the embodiment of the present disclosure provides a method for removing NOx from flue gas by generating CO through boiler combustion. The method is implemented according to the above-mentioned device, comprising:

[0057] S101, using the carbon dioxide reduction generator 3 to catalytically reduce the carbon dioxide in the boiler desulfurization flue gas into carbon monoxide.

[0058] S102, mixing the carbon monoxide generated by the carbon dioxide reduction generator 3 with air through the mixer 6.

[0059] S103, utilizing the flue gas generated by the boiler and the carbon monoxide in the mixed gas supplemented by the mixer 6 to react with the CO-SCR denitration catalyst 13 to denitrate the NOx components in the flue gas.

[0060] In the present disclosure, on the one hand, the denitration reducing agent (CO) required by the CO-SCR denitration catalytic unit 13 is directly derived from the boiler flue gas. On the other hand, the carbon dioxide reduction generator 3 is used to generate CO from the boiler flue gas after desulfurization. 2 The catalytic oxidation into CO is used to supplement the denitration reducing agent required by the CO-SCR denitration catalyst section 13 in the denitration flue, thereby providing sufficient denitration reducing agent for the denitration treatment of the CO-SCR denitration catalyst section 13. Furthermore, the two CO sources are combined to remove NO and NO in the flue gas. 2 The purpose is to oxidize CO to CO 2 , achieving the simultaneous removal of pollutants, realizing the idea of ​​"controlling harm with harm", and has great economic and environmental protection characteristics.

[0061] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A device for removing NOx from flue gas by using CO generated by boiler combustion, characterized in that: The device includes a carbon dioxide reduction generator, a mixer and an SCR denitrification device; The carbon dioxide reduction generator is connected to the boiler and the mixer respectively; the carbon dioxide reduction generator is used to catalytically reduce the carbon dioxide in the flue gas after boiler desulfurization into carbon monoxide; the mixer is used to mix the carbon monoxide generated by the carbon dioxide reduction generator with air; The SCR denitration equipment includes a denitration flue, and a reducing agent spraying and mixing part and a CO-SCR denitration catalytic part arranged in the flue denitration; the denitration flue is connected with the boiler, and is used to pass the flue gas of the boiler into the CO-SCR denitration catalytic part; the reducing agent spraying and mixing part is connected with the output end of the mixer, and is used to supplement the denitration flue with a mixed gas of carbon monoxide and air; The CO-SCR denitration catalyst utilizes the flue gas generated by the boiler and the carbon monoxide in the mixed gas supplemented by the mixer to denitrate the NOx components in the flue gas.

2. The device for removing NOx from flue gas by using CO generated by boiler combustion according to claim 1, characterized in that: The denitrification flue comprises an SCR horizontal flue, an SCR inlet flue, an SCR reactor and an SCR outlet flue; the SCR horizontal flue, the SCR inlet flue, the SCR reactor and the SCR outlet flue are connected in sequence; The SCR horizontal flue is connected to the boiler and is used to pass the flue gas of the boiler into the denitrification flue; the reducing agent spray mixing part is arranged in the inlet flue; and the CO-SCR denitrification catalytic part is arranged in the reactor.

3. A device for removing NOx from flue gas by using CO generated by boiler combustion according to claim 1 or 2, characterized in that: Also includes: The guide part is arranged in the denitrification flue, and is used to guide the flue gas so that the flue gas can flow in the denitrification flue at a more uniform speed.

4. The device for removing NOx from flue gas by using CO generated by boiler combustion according to claim 3 is characterized in that: There are multiple guide parts, and the multiple guide parts are arranged in the denitrification flue at intervals.

5. The device for removing NOx from flue gas by using CO generated by boiler combustion according to claim 3 is characterized in that: There are multiple flow guides, and the multiple flow guides are arranged in the denitrification flue at intervals; the raw agent spray mixing part is arranged between two adjacent flow guides.

6. The device for removing NOx from flue gas by using CO generated by boiler combustion according to claim 1, characterized in that: There are multiple CO-SCR denitration catalyst parts, and the multiple CO-SCR denitration catalyst parts are arranged at intervals in the denitration flue.

7. The device for removing NOx from flue gas by using CO generated by boiler combustion according to claim 1, characterized in that: It also includes a flow regulating valve and a CO flow meter; The flow regulating valve and the CO flow meter are arranged between the carbon dioxide reduction generator and the mixer; wherein the carbon dioxide reduction generator, the flow regulating valve, the CO flow meter and the mixer are connected in sequence.

8. The device for removing NOx from flue gas by using CO generated by boiler combustion according to claim 1, characterized in that: It also includes a dilution fan and an air flow meter; The dilution fan, the air flow meter and the mixer are connected in sequence.

9. The device for removing NOx from flue gas by using CO generated by boiler combustion according to claim 1, characterized in that: The denitrification flue inlet is communicated with the economizer outlet flue at the rear of the boiler.

10. A method for removing NOx from flue gas by using CO generated by boiler combustion, the method being implemented by the device according to any one of claims 1 to 9, characterized in that: include: The carbon dioxide in the boiler desulfurization flue gas is catalytically reduced to carbon monoxide using a carbon dioxide reduction generator; mixing the carbon monoxide produced by the carbon dioxide reduction generator with air through a mixer; The flue gas generated by the boiler and the carbon monoxide in the mixed gas supplemented by the mixer are used to react with the CO-SCR denitration catalyst to denitrate the NOx components in the flue gas.

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