High-temperature SCR (Selective Catalytic Reduction) denitration system of biomass incinerator

Abstract

A high-temperature SCR (Selective Catalytic Reduction) denitration system of a biomass incinerator relates to the technical field of denitration of biomass incinerators, and is characterized in that an SCR reactor is arranged between a boiler body superheater and a high-temperature economizer, and flue gas generated by the biomass incinerator is directly heated by the superheater and then enters the SCR reactor for denitration; an alkali metal detection system and a catalyst cleaning system are arranged to prevent catalyst alkali metal ion poisoning, in addition, a pre-desulfurizer is arranged in front of the SCR reactor for desulfurization treatment to prevent denitration catalyst sulfur poisoning, and meanwhile, a multi-tube dust remover is arranged between the pre-desulfurizer and the SCR reactor to improve the purification rate of smoke dust and particulate matter. According to the invention, heat compensation and temperature rise are not needed, the system resistance loss is small, the comprehensive energy consumption of flue gas desulfurization and denitration can be reduced, and the denitration catalyst alkali poisoning can be effectively prevented.

Description

Technical Field

[0001] The invention relates to the technical field of biomass incinerator denitrification, and in particular to a high-temperature SCR denitrification system of a biomass incinerator. Background Art

[0002] Biomass is becoming an effective supplement and alternative fuel for coal. However, although biomass boilers are less polluting than coal boilers, they still produce particulate dust and sulfur dioxide (SO 2 ), nitrogen oxides (NO x ), acidic gases, etc., and the dust and exhaust gas generated need to be treated to meet the exhaust gas emission standards. With the continuous advancement of "ultra-low emissions" of coal-fired boilers, biomass that lacks its own emission standards often needs to face the same "ultra-low" test, and the research on ultra-low emission technology of biomass boiler tail gas is urgent.

[0003] At present, in order to avoid the influence of alkali metals and ammonium bisulfate on the catalyst, biomass boilers generally use low-temperature SCR denitrification, that is, the process of denitrification after dust removal and desulfurization is adopted: the low-temperature flue gas after dust removal and desulfurization is heated by flue gas heat exchanger (GGH) heater and other methods, and then denitrification is carried out by conventional SCR catalyst. This method has very high investment and operation costs. In addition, the concentration of alkali metals in the flue gas of biomass power plants is several orders of magnitude higher than that of coal-fired power plants, which is easy to make V 2 O 5 -WO 3 / TiO 2 The catalyst is severely deactivated, reducing the denitrification rate. Summary of the invention

[0004] In view of the problems and shortcomings in the prior art, the present invention provides a high-temperature SCR denitrification system for a biomass incinerator.

[0005] The technical solution of the present invention is as follows:

[0006] A high-temperature SCR denitrification system for a biomass incinerator, comprising a superheater, a high-temperature economizer, an air preheater, a desulfurization tower and a dust collector; characterized in that a pre-desulfurizer, a multi-tube dust collector and an SCR reactor are sequentially connected between the superheater and the high-temperature economizer;

[0007] The SCR reactor is provided with an alkali metal detection system and a catalyst cleaning system. The alkali metal detection system includes a number of detectors arranged on each catalyst for detecting the alkali metal content and a control device connected to the detectors in communication;

[0008] The catalyst cleaning system includes a de-alkali agent storage tank, a cleaning pipeline and an automatic spray assembly. The de-alkali agent storage tank includes a first de-alkali agent storage tank and a second de-alkali agent storage tank, which are connected to the automatic spray assembly through a first flushing pipeline and a second flushing pipeline respectively;

[0009] The first flushing pipeline includes a first main pipe and a plurality of first branch pipes connected in parallel with the first main pipe, and a spray assembly connected at the end of the first branch pipe; a first main control valve is provided on the first main pipe, and a first sub-control valve is provided on the first branch pipe; the second flushing pipeline includes a second main pipe and a plurality of second branch pipes connected in parallel with the second main pipe, and a spray assembly connected at the end of the second branch pipe; a second main control valve is provided on the second main pipe, and a second sub-control valve is provided on the second branch pipe;

[0010] The automatic spray assembly includes a spray head arranged above the catalyst, and an X-direction moving mechanism and a Y-direction moving mechanism for driving the spray head to move to the position of the catalyst to be cleaned, the spray head is connected with the first branch pipe and the second branch pipe through a bellows, and moves linearly along the Y direction under the drive of the Y-direction moving mechanism, the X-direction moving mechanism is connected with the Y-direction moving mechanism and moves linearly along the X direction under the drive of the X-direction moving mechanism, and the moving directions of the X-direction moving mechanism and the Y-direction moving mechanism are perpendicular to each other;

[0011] The control device can control the on / off status of the first main control valve, the first sub-control valve, the second main control valve, and the second sub-control valve according to the results of the detector to achieve the following flushing:

[0012] When the alkali metal content on the catalyst is greater than 0.1-0.3%, the control device controls the first main control valve to be connected, and at the same time controls the first sub-control valve connected to the spray assembly above the corresponding catalyst to be connected. After the first de-alkali agent is sprayed on the catalyst through the first flushing pipeline for 150-220 minutes, the first main control valve and the first sub-control valve are controlled to be disconnected, and the second main control valve is controlled to be connected to the second sub-control valve connected to the spray assembly above the corresponding catalyst. After the second de-alkali agent is sprayed on the catalyst through the second flushing pipeline for 60-150 minutes, the second main control valve and the corresponding second sub-control valve are controlled to be disconnected.

[0013] According to a specific embodiment, the X-axis moving mechanism includes a hydraulic cylinder and a guide beam.

[0014] The hydraulic cylinder includes a fixed end and a free end. The fixed end is connected to the SCR reactor. The free end extends horizontally into the SCR reactor along the X-axis direction and the end is slidably connected to the Y-axis linear moving mechanism, on which a displacement sensor is provided. The guide beam is arranged in the SCR reactor in a direction parallel to the moving direction of the free end of the hydraulic cylinder, and there are two guide beams in total and distributed on both sides of the hydraulic cylinder.

[0015] The Y-axis moving mechanism includes a connecting beam and a linear moving module.

[0016] The connecting beam is vertically and slidably mounted on the two guide beams, and its extension direction is along the Y-axis direction; the linear motion module includes a lead screw, a slide and a drive assembly, the lead screw is fixed on the connecting beam in parallel, passes through the guide beam, and is located on the side opposite to the hydraulic cylinder, one end of the lead screw is connected to the motor, and the other end is connected to the displacement sensor; one side of the slide is slidably matched with the lead screw, and the other side is fixedly connected to the sprinkler head.

[0017] According to a specific embodiment, the pre-desulfurizer includes a desulfurization chamber, a cleaning chamber, a crystallization chamber, and an independently arranged activated carbon storage tank; the desulfurization chamber is connected to the cleaning chamber through a third control valve, the cleaning chamber is connected to the crystallization chamber through a fourth control valve, and a filter is provided at the outlet of the fourth control valve; the lower part of the desulfurization chamber is provided with a flue gas inlet, and the top is provided with a flue gas outlet, an activated carbon feed port, and a desulfurizer feed port; the upper part of one side of the cleaning chamber is provided with a water inlet pipe, and the lower part of the other side is connected to the activated carbon storage tank through a pipeline, and a conveying mechanism for conveying activated carbon to the activated carbon storage tank is provided inside; a drying device is provided inside the activated carbon storage tank, and its discharge port is connected to the activated carbon feed port through a material conveying device. In a specific implementation, the activated carbon can be granular activated carbon.

[0018] Specifically, the desulfurizer feed port is connected to the sodium bicarbonate powder storage tank through a feed pipeline, and is used to spray sodium bicarbonate powder from the top of the desulfurization chamber into the interior of the desulfurization chamber, thereby reacting with sulfur dioxide in the flue gas to remove sulfur in the flue gas.

[0019] In order to make the flue gas fully contact with the activated carbon and sodium bicarbonate powder sprayed on the top of the desulfurization chamber, a steam nozzle is provided in the desulfurization chamber, which is located above the flue gas inlet. A plurality of steam nozzles are evenly arranged along the circumference of the inner wall of the desulfurization chamber, and the outlets thereof are upward and inclined to the inner wall of the desulfurization chamber, and the angle between the steam nozzles and the inner wall of the desulfurization chamber is 50°-70°.

[0020] Furthermore, in order to increase the intensity of the spraying air flow, the steam spray pipe adopts a Venturi tube, and its inlet is connected to the outlet of the superheater through a pipeline.

[0021] The conveying mechanism is a screw conveyor, and the drying device includes a chain plate screw conveyor for conveying materials and a hot air blower arranged under the chain plate to blow hot air to the materials on the chain plate. Thus, the activated carbon particles after being rinsed and filtered in the cleaning chamber are conveyed to the activated carbon storage tank.

[0022] According to a specific embodiment, the first de-alkali agent is a mixture of sulfuric acid, ammonium fluoride, polyethylene glycol, a nonionic surfactant and deionized water, wherein the content of sulfuric acid is 0.1-1wt%, the content of ammonium fluoride is 0.2-0.5wt%, the content of polyethylene glycol is 1-1.5wt%, and the content of nonionic surfactant is 1-1.8wt%. The second de-alkali agent is a mixture of ammonium chloride, ammonium bicarbonate, oxalic acid and deionized water; the content of ammonium chloride is 0.5-1wt%, the content of ammonium bicarbonate is 0.2-0.5wt%, and the content of oxalic acid is 0.05-0.1wt%.

[0023] The beneficial effects of the present invention are:

[0024] 1) The blast furnace hot blast stove flue gas desulfurization and denitrification system and method provided in the embodiment of the present invention can make full use of the waste heat of the blast furnace hot blast stove flue gas itself. Compared with the post-SCR denitrification technology in the conventional post-desulfurization and denitrification technology, it does not require heat supplementation and temperature rise, the system resistance loss is small, and the comprehensive energy consumption of flue gas desulfurization and denitrification can be reduced; at the same time, there is no need to configure subsystem equipment such as heating furnaces and GGH heat exchangers, and the failure points are greatly reduced, thereby greatly reducing its impact on the main process.

[0025] 2) An alkali metal detection system and a catalyst cleaning system are set up in the SCR reactor to monitor the alkali metal content in the catalyst online. When the alkali metal content in the catalyst of one of the units reaches a proportion that will poison the catalyst, the spray component in the catalyst cleaning system moves to the top of the corresponding catalyst and controls the corresponding control valve to open, and the poisoned catalyst is cleaned online to prevent catalyst alkali poisoning, increase the service life of the catalyst, reduce maintenance time, and thus improve system operation efficiency.

[0026] 3) A pre-desulfurizer is set before the SCR reactor to reduce the smoke and sulfur content in the flue gas through activated carbon and sodium bicarbonate powder, thereby reducing the sulfur entering the SCR reactor and the alkali metals carried by the smoke, reducing the risk of catalyst poisoning and increasing the service life of the catalyst; at the same time, the activated carbon can be reused to reduce the system operating cost, and the reaction by-products can be recycled after crystallization to reduce resource waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A system connection diagram of the present invention;

[0028] Figure 2 It is a structural schematic diagram of the SCR reactor;

[0029] Figure 3 It is a structural schematic diagram of the automatic spray assembly;

[0030] Figure 4 It is a structural schematic diagram of a pre-desulfurizer;

[0031] 1. Superheater; 2. Multi-tube dust collector; 3. Pre-desulfurizer; 4. SCR reactor; 5. High-temperature economizer; 6. Air preheater; 7. Desulfurization tower; 8. Dust collector; 31. Desulfurization chamber; 32. Steam nozzle; 33. Third control valve; 34. Cleaning chamber; 35. Fourth control valve; 36. Crystallization chamber; 37. Activated carbon storage tank; 38. Sodium bicarbonate powder storage tank; 41. First de-alkali agent storage tank; 411. First main control valve; 41 2. First main pipe; 413. First branch pipe; 414. First sub-control valve; 42. Second de-alkali agent storage tank; 421. Second main control valve; 422. Second main pipe; 423. Second branch pipe; 424. Second sub-control valve; 43. Spray assembly; 431. Hydraulic cylinder; 432. Guide beam; 433. Connecting beam; 434. Lead screw; 435. Slide; 436. Spray head; 437. Motor; 44. Catalyst; 45. Detector. DETAILED DESCRIPTION

[0032] The technical means adopted to achieve the predetermined inventive objectives of the present invention will be further described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0033] See also Figure 1 , Figure 1 This is a connection diagram of a high-temperature SCR denitrification system for a biomass incinerator provided in a specific embodiment of the present invention.

[0034] A high-temperature SCR denitrification system for a biomass incinerator comprises a superheater 1, a high-temperature economizer 5, an air preheater 6, a desulfurization tower 7 and a dust collector 8. A pre-desulfurizer 3, a multi-tube dust collector 2 and an SCR reactor 4 are connected in sequence between the superheater 1 and the high-temperature economizer 5.

[0035] In the high-temperature SCR denitrification system of the present invention, the SCR reactor 4 is arranged between the boiler body superheater 1 and the high-temperature economizer 5. The superheater 1 is directly used to heat the flue gas generated by the biomass incinerator to make the flue gas temperature reach 300-400°C. The heated high-temperature flue gas directly enters the SCR reactor 4 for denitrification reaction. The flue gas temperature can meet the reaction requirements of the high-temperature catalyst 44, and there is no need to add heating equipment such as GGH, etc., avoiding the large amount of cost required for heating in the low-temperature denitrification method, thereby effectively reducing the system cost.

[0036] However, the high-temperature flue gas coming out of the biomass boiler body contains a large amount of sulfur and alkali metal ions, which directly enter the SCR reactor 4 for reaction, which is easy to cause poisoning of the catalyst 44. For this reason, the present invention arranges a pre-desulfurizer 3 and a multi-tube dust collector 2 before the SCR reactor 4, and removes sulfur in the flue gas and alkali ions attached to the flue dust through the pre-desulfurizer 3, and further removes dust through the multi-tube dust collector 2, so that the flue gas after preliminary purification enters the SCR reactor 4 for high-temperature denitrification.

[0037] In addition, in order to prevent the accumulation of alkali ions in the flue gas in the catalyst 44 and thus poisoning the catalyst 44, an alkali metal detection system and a catalyst 44 cleaning system are provided in the SCR reactor 4, see Figure 2 As shown, Figure 2 4 is a schematic diagram of the structure of the SCR reactor 4 . The alkali metal detection system includes a plurality of detectors 45 arranged on each catalyst block 44 for detecting the alkali metal content, and a control device connected to the detectors 45 for communication.

[0038] The catalyst 44 cleaning system includes a de-alkali agent storage tank, a cleaning pipeline and an automatic spray assembly 43. The de-alkali agent storage tank includes a first de-alkali agent storage tank 41 and a second de-alkali agent storage tank 42, which are connected to the automatic spray assembly 43 through a first flushing pipeline and a second flushing pipeline respectively.

[0039] Among them, the first flushing pipeline includes a first main pipe 412 and a plurality of first branch pipes 413 connected in parallel with the first main pipe 412, and a spray assembly 43 connected to the end of the first branch pipe 413; a first main control valve 411 is provided on the first main pipe 412, and a first sub-control valve 414 is provided on the first branch pipe 413; the second flushing pipeline includes a second main pipe 422 and a plurality of second branch pipes 423 connected in parallel with the second main pipe 422, and a spray assembly 43 connected to the end of the second branch pipe 423; a second main control valve 421 is provided on the second main pipe 422, and a second sub-control valve 424 is provided on the second branch pipe 423.

[0040] See also Figure 3 As shown, Figure 3 It is a structural schematic diagram of the automatic spraying component 43.

[0041] The automatic spray assembly 43 includes a spray head 436 arranged above the catalyst 44, and an X-direction moving mechanism and a Y-direction moving mechanism for driving the spray head 436 to move to the position of the catalyst 44 to be cleaned. The spray head 436 is connected to the first branch pipe 413 and the second branch pipe 423 through a bellows, and moves linearly along the Y direction under the drive of the Y-direction moving mechanism. The X-direction moving mechanism is connected to the Y-direction moving mechanism and moves linearly along the X direction under the drive of the X-direction moving mechanism. The X-direction moving mechanism and the Y-direction moving mechanism can realize vertical movement with the moving directions being perpendicular to each other.

[0042] The control device can control the on / off states of the first main control valve 411, the first sub-control valve 414, the second main control valve 421, and the second sub-control valve 424 through the results of the detector 45 to achieve the following flushing: when the alkali metal content on the catalyst 44 is greater than 0.1-0.3%, the control device controls the first main control valve 411 to be connected, and at the same time controls the first sub-control valve 414 connected to the spray assembly 43 above the corresponding catalyst 44 to be connected, and the first main control valve 411 and the first sub-control valve 414 are controlled to be disconnected after the first alkali-removing agent is used to spray the catalyst 44 through the first flushing pipeline for 150-220 minutes, and the second main control valve 421 is controlled to be connected to the second sub-control valve 424 connected to the spray assembly 43 above the corresponding catalyst 44, and the second main control valve 421 and the corresponding second sub-control valve 424 are controlled to be disconnected after the second alkali-removing agent is used to spray the catalyst 44 through the second flushing pipeline for 60-150 minutes.

[0043] Specifically, the detector 45 can be a flame photometer, and the control device is a control module integrated in the main control unit of the system, which is mainly connected with the detector 45, the first main control valve 411, the first sub-control valve 414, the second main control valve 421, and the second sub-control valve 424. The first de-alkali agent is a mixture of sulfuric acid, ammonium fluoride, polyethylene glycol, a non-ionic surfactant and deionized water, wherein the content of sulfuric acid is 0.1-1wt%, the content of ammonium fluoride is 0.2-0.5wt%, the content of polyethylene glycol is 1-1.5wt%, and the content of non-ionic surfactant is 1-1.8wt%. The second de-alkali agent is a mixture of ammonium chloride, ammonium bicarbonate, oxalic acid and deionized water; the content of ammonium chloride is 0.5-1wt%, the content of ammonium bicarbonate is 0.2-0.5wt%, and the content of oxalic acid is 0.05-0.1wt%.

[0044] Before the alkali metal ion content in the catalyst reaches poisoning, the catalyst is promptly rinsed with the first de-alkali agent and the second de-alkali agent to reduce the alkali ion content, thereby reducing the possibility of catalyst poisoning, extending the online use time of the catalyst, and reducing system costs. In addition, other solvents that can reduce the alkali ion content in the catalyst can also be used for rinsing, not limited to the above-mentioned de-alkali agents.

[0045] According to a specific embodiment, the X-direction moving mechanism and the Y-direction moving mechanism refer to Figure 3 shown.

[0046] The X-axis moving mechanism includes a hydraulic cylinder 431 and a guide beam 432 .

[0047] The hydraulic cylinder 431 includes a fixed end and a free end. The fixed end is connected to the SCR reactor 4, and the free end extends horizontally into the SCR reactor 4 along the X-axis direction and the end is slidably connected to the Y-axis linear motion mechanism, on which a displacement sensor is provided; the guide beam 432 is arranged in the SCR reactor 4 in a direction parallel to the moving direction of the free end of the hydraulic cylinder 431, and there are two guide beams in total and distributed on both sides of the hydraulic cylinder 431.

[0048] The Y-axis moving mechanism includes a connecting beam 433 and a linear moving module.

[0049] The connecting beam 433 is vertically and slidably mounted on the two guide beams 432, and extends in the Y-axis direction; the linear motion module includes a lead screw 434, a slide 435 and a drive assembly, the lead screw 434 is fixed in parallel to the connecting beam 433, passes through the guide beam 432, and is located on the side opposite to the hydraulic cylinder 431, one end of which is connected to the motor 437, and the other end is connected to the displacement sensor; one side of the slide 435 is slidably matched with the lead screw 434, and the other side is fixedly connected to the sprinkler head 436.

[0050] Specifically, the hydraulic cylinder 431 is driven by a hydraulic pump to move the free end linearly relative to the fixed end, thereby driving the connecting beam 433 to move along the X-axis direction, and a displacement sensor is arranged on it to obtain and feed back the precise X-direction moving distance to the control device. In order to improve the stability of the movement of the connecting beam 433 and reduce the linear error when it moves along the X-axis direction, a guide beam 432 is arranged, and two guide beams 432 are arranged and symmetrically distributed on both sides of the hydraulic cylinder 431. The connecting beam 433 is slidably matched with the guide beam 432 through a sliding bearing or a copper sleeve, and can reciprocate along the length direction of the guide beam 432. The lead screw 434 is fixed to the connecting beam 433 in parallel through a bearing seat, and is driven to rotate by a motor 437. The slide 435 cooperates with the lead screw 434 and reciprocates along its axial straight line, and drives the spray head 436 connected thereto to move. In order to obtain the moving distance of the spray head 436 along the Y direction, a displacement sensor is provided on the lead screw 434. Specifically, a potentiometer or a photoelectric switch can be used to measure the moving distance of the slide 435 by detecting the number of rotations of the lead screw 434. In addition, in order to enable the spray head 436 to move freely, the spray head 436 is connected to the first branch pipe 413 or the second branch pipe 423 through a bellows.

[0051] According to a specific embodiment, see Figure 4 As shown, Figure 4 It is a schematic diagram of the structure of the pre-desulfurizer 3.

[0052] The pre-desulfurizer 3 includes a desulfurization chamber 31, a cleaning chamber 34, a crystallization chamber 36, and an independently arranged activated carbon storage tank 37, which are vertically integrated from top to bottom; the desulfurization chamber 31 and the cleaning chamber 34 are connected through a third control valve 33, and the cleaning chamber 34 and the crystallization chamber 36 are connected through a fourth control valve 35, and a filter is provided at the outlet of the fourth control valve 35.

[0053] The lower part of the desulfurization chamber 31 is provided with a flue gas inlet for connecting with the flue gas outlet pipe of the boiler, and the top is provided with a flue gas outlet, an activated carbon feed port and a desulfurizer feed port, wherein the flue gas outlet is used to connect with the SCR reactor 4, the activated carbon inlet is used to spray activated carbon particles into the desulfurization chamber 31, and the desulfurizer feed port is used to communicate with the sodium bicarbonate powder storage tank 38 through the feed pipe, and is used to spray sodium bicarbonate powder from the top of the desulfurization chamber 31 into the desulfurization chamber 31, so as to react with sulfur dioxide in the flue gas and remove sulfur in the flue gas. In a specific implementation, the activated carbon can be granular activated carbon, which is sprayed into the desulfurization chamber 31 from the top of the desulfurization chamber 31 at the same time as the sodium bicarbonate powder, so as to fully contact with the flue gas entering from the bottom of the desulfurization chamber 31.

[0054] A water inlet pipe is provided at the upper part of one side of the cleaning chamber 34 for spraying water into the cleaning chamber 34 to wash the activated carbon. The lower part of the other side is connected to the activated carbon storage tank 37 through a pipeline. A conveying mechanism for conveying the activated carbon to the activated carbon storage tank 37 is provided inside, and specifically the conveying mechanism is a screw conveyor.

[0055] The activated carbon storage tank 37 is provided with a drying device for drying the activated carbon after washing for reuse, and its discharge port is connected to the activated carbon feed port through the material conveying device pump. The drying device includes a chain plate type screw conveying mechanism for conveying materials and a hot air blower arranged under the chain plate to blow hot air to the materials on the chain plate. Thus, the activated carbon particles washed and filtered in the cleaning chamber 34 are conveyed to the activated carbon storage tank 37.

[0056] A refrigeration system is provided in the crystallization chamber 36 for cleaning the reaction product which is dissolved in the cleaning chamber 34 after the reaction and then filtered through the fourth control valve 35 and the filter screen and enters the clean room to produce by-products, wherein the main recovered product is sodium sulfite.

[0057] In order to make the flue gas fully contact with the activated carbon and sodium bicarbonate powder sprayed on the top of the desulfurization chamber 31, a steam nozzle 32 is provided in the desulfurization chamber 31 and is located above the flue gas inlet. A plurality of steam nozzles 32 are evenly arranged along the circumference of the inner wall of the desulfurization chamber 31, and the outlets thereof are upward and inclined to the inner wall of the desulfurization chamber 31, and the angle between the steam nozzles 32 and the inner wall of the desulfurization chamber 31 is 50°-70°.

[0058] Furthermore, in order to increase the intensity of the injected air flow, the steam nozzle 32 adopts a Venturi tube, and its inlet is connected to the outlet of the superheater 1 through a pipeline.

[0059] See also Figure 1 In order to further purify the pretreated flue gas and prevent activated carbon particles and sodium bicarbonate powder from entering the SCR reactor 4, a multi-tube dust collector 2 is arranged between the pretreatment device and the SCR reactor 4 to process the smoke or other solid impurities.

[0060] The above is a preferred embodiment of the present invention, but the present invention is not limited to the above embodiments and examples. Various changes, equivalent substitutions, improvements, etc. made within the scope of knowledge of those skilled in the art without departing from the concept of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-temperature SCR denitrification system for a biomass incinerator, comprising a superheater (1), a high-temperature economizer (5), an air preheater (6), a desulfurization tower (7) and a dust collector (8); characterized in that: A pre-desulfurizer (2), a multi-tube dust collector (3) and an SCR reactor (4) are connected in sequence between the superheater (1) and the high-temperature economizer (5); The SCR reactor (4) is provided with an alkali metal detection system and a catalyst cleaning system, wherein the alkali metal detection system comprises a plurality of detectors (45) arranged on each catalyst (44) for detecting the alkali metal content and a control device connected to the detectors in communication; The catalyst cleaning system comprises a de-alkali agent storage tank, a cleaning pipeline and an automatic spray assembly (43), wherein the de-alkali agent storage tank comprises a first de-alkali agent storage tank (41) and a second de-alkali agent storage tank (42), which are connected to the automatic spray assembly (43) through a first flushing pipeline and a second flushing pipeline respectively; The first flushing pipeline comprises a first main pipe (412) and a plurality of first branch pipes (413) connected in parallel with the first main pipe (412), and the ends of the first branch pipes (413) are connected to a spray assembly (43); the first main pipe (412) is provided with a first main control valve (411), and the first branch pipes (413) are provided with a first sub-control valve (414); The second flushing pipeline comprises a second main pipe (422) and a plurality of second branch pipes (423) connected in parallel with the second main pipe (422), and the ends of the second branch pipes (423) are connected to a spray assembly (43); the second main pipe (422) is provided with a second main control valve (421), and the second branch pipes (423) are provided with a second sub-control valve (424); The automatic spray assembly (43) comprises a spray head (436) arranged above the catalyst, and an X-direction moving mechanism and a Y-direction moving mechanism for driving the spray head to move to a position of the catalyst to be cleaned, the spray head (436) being connected to the first branch pipe (413) and the second branch pipe (423) through a bellows, and being driven by the Y-direction moving mechanism to move linearly along the Y direction, the X-direction moving mechanism being connected to the Y-direction moving mechanism and being driven by the Y-direction moving mechanism to move linearly along the X direction, and the moving directions of the X-direction moving mechanism and the Y-direction moving mechanism being perpendicular to each other; The control device can control the on / off states of the first main control valve (411), the first sub-control valve (414), the second main control valve (421), and the second sub-control valve (424) according to the result of the detector to achieve the following flushing: When the alkali metal content on the catalyst is greater than 0.1-0.3%, the control device controls the first main control valve (411) to be connected, and at the same time controls the first sub-control valve (414) connected to the spray assembly (43) above the corresponding catalyst to be connected. After the first de-alkali agent is sprayed on the catalyst through the first flushing pipeline for 150-220 minutes, the first main control valve (411) and the first sub-control valve (414) are controlled to be disconnected, and the second main control valve (421) is controlled to be connected to the second sub-control valve (424) connected to the spray assembly (43) above the corresponding catalyst. After the second de-alkali agent is sprayed on the catalyst through the second flushing pipeline for 60-150 minutes, the second main control valve (421) and the corresponding second sub-control valve (424) are controlled to be disconnected.

2. The denitration system according to claim 1, characterized in that: The X-direction moving mechanism comprises: A hydraulic cylinder (431) comprising a fixed end and a free end, wherein the fixed end is connected to the SCR reactor (4), and the free end extends horizontally into the SCR reactor (4) along the X-axis direction and the end portion is slidably connected to the Y-axis linear motion mechanism, and a displacement sensor is provided on the free end; The guide beams (432) are arranged in the SCR reactor (4) in a direction of extension parallel to the moving direction of the free end of the hydraulic cylinder (431), and there are two guide beams in total distributed on both sides of the hydraulic cylinder (431).

3. The denitration system according to claim 2, characterized in that: The Y-direction moving mechanism comprises: The connecting beam (433) is vertically and slidably mounted on the two guide beams (432), and extends in the Y-axis direction; A linear motion module comprises a lead screw (434), a slide (435) and a drive assembly. The lead screw (434) is fixed in parallel to a connecting beam (433), passes through a guide beam (432), and is located on a side opposite to a hydraulic cylinder (431). One end of the lead screw is connected to a motor (437), and the other end is connected to a displacement sensor. One side of the slide (435) is slidably matched with the lead screw (434), and the other side is fixedly connected to a sprinkler head (436).

4. The denitration system according to claim 3, characterized in that: The pre-desulfurizer (2) comprises a desulfurization chamber (21), a cleaning chamber (24), a crystallization chamber (26) vertically arranged in an integrated manner, and an activated carbon storage tank (27) arranged independently; the desulfurization chamber (21) is connected to the cleaning chamber (24) via a third control valve (23), the cleaning chamber (24) is connected to the crystallization chamber (26) via a fourth control valve (25), and a filter screen is arranged at the outlet of the fourth control valve (25); a flue gas inlet is arranged at the lower part of the desulfurization chamber (21), and a flue gas outlet, an activated carbon feed port and a desulfurizer feed port are arranged at the top; a water inlet pipe is arranged at the upper part of one side of the cleaning chamber (24), and the lower part of the other side is connected to the activated carbon storage tank (27) via a pipeline, and a conveying mechanism for conveying activated carbon to the activated carbon storage tank is arranged inside; a drying device is arranged inside the activated carbon storage tank (27), and its discharge port is connected to the activated carbon feed port via a material conveying device.

5. The denitration system according to claim 4, characterized in that: The desulfurizing agent feed port is connected to the sodium bicarbonate powder storage tank (28) through a feed pipeline.

6. The denitration system according to claim 5, characterized in that: A steam nozzle (22) is provided in the desulfurization chamber (21) and is located above the flue gas inlet. A plurality of steam nozzles (22) are evenly arranged along the circumference of the inner wall of the desulfurization chamber (21), and their outlets face upward and are inclined to the inner wall of the desulfurization chamber (21), with an angle of 50°-70° with the inner wall of the desulfurization chamber.

7. The denitration system according to claim 6, characterized in that: The steam spray pipe (22) is a venturi tube, and its inlet is connected to the outlet of the superheater (1) through a pipeline.

8. The denitration system according to claim 4, characterized in that: The conveying mechanism is a screw conveyor, and the drying device includes a chain-plate screw conveying mechanism for conveying materials and a hot air blower arranged under the chain plate to blow hot air to the materials on the chain plate.

9. The denitration system according to claim 1, characterized in that: The first de-alkali agent is a mixture of sulfuric acid, ammonium fluoride, polyethylene glycol, a nonionic surfactant and deionized water, wherein the content of the sulfuric acid is 0.1-1wt%, the content of the ammonium fluoride is 0.2-0.5wt%, the content of the polyethylene glycol is 1-1.5wt%, and the content of the nonionic surfactant is 1-1.8wt%.

10. The denitration system according to claim 9, characterized in that: The second de-alkali agent is a mixture of ammonium chloride, ammonium bicarbonate, oxalic acid and deionized water; the content of the ammonium chloride is 0.5-1wt%, the content of the ammonium bicarbonate is 0.2-0.5wt%, and the content of the oxalic acid is 0.05-0.1wt%.

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