Boiler flue gas purification device and method for reducing nitrogen oxide through secondary return air combustion

Abstract

The invention discloses a boiler flue gas purification device and a method for reducing nitric oxide through secondary return air combustion, and particularly relates to the technical field of boiler flue gas purification and recycling. The boiler flue gas purification device comprises a base, a flow guide treatment assembly is arranged on the base and comprises a supporting frame arranged on the top of the base, and a supporting plate is arranged on one side of the top of the supporting frame; the top of the supporting frame is provided with a driving motor through a bolt. Appropriate adjustment is easily carried out according to the flue gas air volume condition, the backflow phenomenon is avoided, the blocking frame moves up and down so that different first through holes, second through holes and flow dividing holes can be communicated with one another in the mixing cavity, flue gas can easily flow through the second through holes in the pressurizing treatment barrel, and the efficiency is improved. The treatment medium and the flue gas can be conveniently mixed together, so that the emission of pollutants in the flue gas is reduced, and the environment-friendly effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of boiler flue gas purification and recovery, and more specifically to a boiler flue gas purification device and a method for reducing nitrogen oxides by secondary return air combustion. Background Art

[0002] Boiler flue gas is the waste gas generated during the combustion of boiler fuel, mainly including particles, gases and water vapor generated by combustion. Boiler flue gas contains a large amount of heat energy and substances that may pollute the environment, such as sulfur dioxide, nitrogen oxides and dust. Boiler flue gas contains a large amount of heat energy. Through secondary recovery technology, this part of heat energy can be reused in boilers or other production links, thereby improving the energy efficiency of the entire system. For example, the boiler hot air secondary recovery technology can recover the high-temperature hot air in the exhaust gas through the waste heat recovery device and send it back to the boiler for combustion, reducing dependence on new fuels; During the operation of the circulating fluidized bed boiler, the load of the boiler can be effectively adjusted by adjusting the ratio of the primary and secondary air, and the change of the combustion share can be effectively controlled. In the lower part of the circulating fluidized bed boiler, that is, the dense phase area, the fluidization form of the material is basically in a turbulent fluidization state, and it gradually transitions to a rapid fluidization state in the middle and upper part of the furnace, that is, the dilute phase area. Due to the addition of the secondary air volume, the flue gas flow rate above the secondary air nozzle is significantly increased, so that more materials participate in the circulation inside and outside the furnace, and more circulating materials with low temperature return to the dense phase area, absorb heat in the dense phase area, take away the heat released by combustion, and exchange heat with the water-cooled wall in the middle and upper part of the furnace, improve the heat transfer coefficient and transfer energy, maintain the bed temperature in the dense phase area, and increase the boiler load. In the early stage of the operation of a certain factory boiler, due to poor slag discharge, there are many large particles in the furnace bottom, and the fluidization is not good, the primary air can only be increased to maintain a reasonable excess air coefficient and reduce the opening of the secondary air. Due to the small secondary air volume, the combustion share of the dense phase area is reduced, the combustion share of the dilute phase area is increased, and the concentration of the upper material is increased, which not only aggravates the wear of the upper water-cooled wall. At the same time, due to the insufficient secondary air volume for combustion, there is a serious afterburning phenomenon in the boiler high-temperature separator, that is, some combustibles are burned in the high-temperature separator, resulting in an increase in the flue gas temperature at the separator outlet, an increase in the inlet and outlet temperature difference, and when the coal particle size changes, the cyclone separator outlet temperature reaches 1000℃, and the temperature difference even reaches about 80℃. The afterburning of coal causes the flue gas temperature to rise, which increases the heat transfer of the flue gas to the tail convection heating surface, causes the superheater to overheat, and increases the amount of boiler cooling water, which seriously affects the safety of the heating surface.

[0003] Among them, the patent publication number CN220119408U discloses a boiler flue gas waste heat recovery heat pipe heat exchanger, including a boiler and a recovery heat pipe heat exchanger; When this structure is in use, the boiler flue gas is first heat recovered by first passing through the square tubes arranged side by side in the first-stage heat exchanger and the flue gas and cooling water in the tubes flowing in the opposite direction, and then a hexagonal tube for circulating flue gas is fully wrapped by multiple hexagonal tubes for circulating cold air in the second-stage heat exchanger for secondary heat recovery, thereby completing sufficient heat recovery of the boiler flue gas in a compact structure. However, the flue gas is mixed with a large amount of pollutants such as particulate matter, sulfur dioxide, nitrogen oxides and dust, and direct emission will have a serious impact on the environment. It is not easy to treat harmful particulate matter in the flue gas, and it is not easy to adjust the airflow, resulting in poor recovery and treatment effect. Summary of the invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a boiler flue gas purification device and a method for reducing nitrogen oxides by secondary return air combustion, aiming to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: A boiler flue gas purification device comprises a base, on which a flow diversion processing component is arranged; The diversion processing component includes a support frame arranged on the top of the base, a support plate is arranged on one side of the top of the support frame, a driving motor is installed on the top of the support frame by bolts, a crankshaft is fixedly arranged at the output end of the driving motor, and an eccentric disk is fixedly arranged at one end of the crankshaft.

[0006] A boost treatment cylinder is installed on the top of the support plate by bolts, and a mixed gas treatment chamber is installed on one side of the surface of the boost treatment cylinder by bolts, a partition is installed between the mixed gas treatment chamber and the boost treatment cylinder by bolts, and a plurality of diversion holes are penetrated by the partition, a first through hole is penetrated by the side of the boost treatment cylinder facing the partition, and a second through hole is provided on the top and bottom of the first through hole, a sealing frame located on one side of the partition is provided in the mixed gas treatment chamber, and a mixing chamber is provided on the sealing frame, an atomization joint is inserted on one side of the surface of the boost treatment cylinder, and the atomization joint is connected to the first through hole, an electric butterfly valve is inserted on the mixed gas treatment chamber, an elastic conical filter is provided at the bottom of the inner cavity of the boost treatment cylinder, and a one-way valve extending to the middle of the elastic conical filter is inserted at the bottom of the support plate.

[0007] It can be seen that in the above technical solution, the high-temperature flue gas is transported to the electric butterfly valve through the pump and the conduit, and the liquid medium for purifying the flue gas is transported through the atomizing joint, and the size of the airflow transported to the mixing treatment chamber is adjusted by the electric butterfly valve. When the blocking frame moves upward, the first through hole and the second through hole at the top of the first through hole are connected with the corresponding diversion hole, and the blocking frame moves downward, so that the first through hole and the second through hole at the bottom of the first through hole are connected with the corresponding diversion hole. It is easy for the atomizing joint to atomize the purified liquid medium and then transport it to the mixing chamber through the first through hole to mix it with the flue gas, so as to reduce the emission of pollutants in the flue gas and achieve an environmental protection effect. By moving the piston up and down, the flue gas mixed in the mixing chamber is extracted into the boost treatment cylinder through the second through hole, and the flue gas is squeezed by the downward displacement of the piston and filtered through the elastic conical filter before being discharged through the one-way valve.

[0008] The top of the pressurizing treatment cylinder is installed with a guide rod by bolts, and the guide rod is slidably connected with a sliding rod, and both ends of the sliding rod are rotatably connected to the first traction member, the bottom of the first traction member extends to the eccentric disk and is movably connected to the eccentric disk through an axle pin, a limited seat is provided at the bottom of the mixing gas treatment chamber, and the limited seat is installed on the supporting plate by bolts, a second traction member is rotatably connected in the first traction member, one end of the second traction member is movably connected to the third traction member through an axle pin, and one end of the third traction member is sleeved on the crankshaft and rotatably connected to the crankshaft, a piston extending into the pressurizing treatment cylinder is installed on the sliding rod by bolts, and a pull rod extending to the sealing frame is installed on the second traction member by bolts; It can be seen that in the above technical solution, the crankshaft is driven to rotate by the driving motor. When the crankshaft rotates, the third traction member is pulled to drive the second traction member to rotate along the axis point of the connection between the second traction member and the limit seat, and then the pull rod drives the sealing frame to move up and down in the mixed gas treatment chamber. When the crankshaft rotates, it can also drive the eccentric disk to rotate, so that the first traction member drives the sliding rod to slide on the guide rod through the torque when the eccentric disk rotates, and then the piston moves up and down in the boost treatment cylinder. When the piston is pressed down, the elastic conical filter is deformed due to the airflow pressure, which not only filters impurities in the airflow on the elastic conical filter, but also shakes off the impurities on its surface through the amplitude generated by the elastic reset of the elastic conical filter itself, so as to avoid impurities clogging the elastic conical filter and reducing the airflow conveying efficiency.

[0009] A method for reducing nitrogen oxides by secondary return air combustion, using a boiler flue gas purification device, comprises the following steps: Step 1: The boiler flue gas purification device is installed at one end of the recirculating flue gas duct, and the other end of the recirculating flue gas duct is connected to the flue gas recirculation fan. The flue gas flows to the recirculating flue gas duct through the boiler flue gas purification device, and moves along the flue gas recirculation fan to two groups of primary fans, which are divided into A primary fans and B primary fans, and flows into the furnace of the combustion chamber along the primary fans; Step 2, initial combustion stage: the fuel is decomposed by heat in the combustion chamber, releasing combustible gases, which are mixed with the air entering through the primary air inlet, undergo preliminary combustion, and release heat; Step 3, secondary combustion stage: As the primary combustion proceeds, the temperature and oxygen concentration gradually increase, and the secondary air enters the combustion chamber from the secondary air inlet and mixes with the incompletely burned fuel to form secondary combustion, so that the fuel can be fully burned; Step 4: The primary fan B is arranged to enter from the short direction of the furnace to form a strong air flow injected into the furnace combustion chamber with a speed of more than 50m / s, which supplements the air required for fuel combustion and strengthens the back mixing of materials, adjusts the distribution of the temperature field in the furnace, and makes the flue gas temperature distribution more uniform; Step 5, during the operation of the circulating fluidized bed boiler, the load of the boiler is effectively adjusted by adjusting the ratio of the two sets of primary fans. In the lower part of the circulating fluidized bed boiler, i.e., the dense phase zone, the fluidization form of the material is in a turbulent fluidization state, and in the middle and upper part of the furnace, i.e., the dilute phase zone, it gradually transitions to a fast fluidization state. Due to the addition of the secondary air volume, the flue gas flow velocity above the secondary air nozzle is increased, so that more materials participate in the circulation inside and outside the furnace, and the circulating materials with low temperature return to the dense phase zone, absorb heat in the dense phase zone, take away the heat released by combustion, and exchange heat with the water-cooled wall in the middle and upper part of the furnace, so as to improve the heat transfer coefficient and transfer energy, maintain the bed temperature in the dense phase zone, and increase the boiler load; Step 6: Treatment of organic waste gas: The organic waste gas contained in the flue gas generated after the combustion of the biomass boiler is transported to the recirculating flue gas duct through the induced draft fan, transported by the flue gas recirculation fan, and treated by the cyclone separator; The flue gas treated by the cyclone separator recovers the heat energy in the exhaust gas through the tail flue, is continuously transported by the flue gas, and the dust in the flue gas is filtered out by the dust collector and discharged through the chimney to achieve the purpose of purifying the flue gas.

[0010] Technical effects and advantages of the present invention: In the present invention, high-temperature flue gas is transported to the electric butterfly valve through a pump and a conduit, and the liquid medium for purifying the flue gas is transported through an atomizing joint. The size of the air flow transported to the mixed gas treatment chamber is adjusted by the electric butterfly valve, and it is easy to make appropriate adjustments according to the flue gas volume to avoid backflow. In the present invention, when the blocking frame moves upward, the first through hole and the second through hole at the top of the first through hole are connected with the corresponding diversion hole, and when the blocking frame moves downward, the first through hole and the second through hole at the bottom of the first through hole are connected with the corresponding diversion hole, so that the atomization joint can transport the purified liquid medium into the mixing chamber through the first through hole after atomization, so that the liquid medium is mixed with the flue gas, thereby reducing the emission of pollutants in the flue gas and achieving an environmental protection effect. The present invention uses a piston up and down displacement mode to allow the smoke mixed in the mixing chamber to be drawn into the pressurized treatment cylinder through the second through hole, and the smoke is squeezed by the piston downward displacement and filtered through the elastic conical filter screen before being discharged through the one-way valve. The pressurization mode not only facilitates the flow of excess air through the second through hole, but also facilitates the rapid discharge of air flow, and also ensures that the medium for treating the smoke can be fully mixed with the smoke. When the piston of the present invention is pressed down, the elastic conical filter screen is deformed due to the airflow pressure, not only filtering the impurities in the airflow on the elastic conical filter screen, but also shaking off the impurities on the surface of the elastic conical filter screen due to the amplitude generated by the elastic reset of the elastic conical filter screen itself, thereby preventing the impurities from clogging the elastic conical filter screen and causing the airflow transmission efficiency to be reduced; To summarize, the size of the airflow delivered to the mixed air treatment chamber is regulated by the electric butterfly valve, and it is easy to make appropriate adjustments according to the flue gas volume to avoid backflow, and the up and down displacement of the sealing frame enables different first through holes, second through holes and diversion holes to be interconnected in the mixing chamber, which makes it easy for the flue gas to flow through the second through holes in the pressurized treatment cylinder, and facilitates the mixing of the treatment medium and the flue gas, which is used to reduce the emission of pollutants in the flue gas to achieve environmental protection effects, and the elastic conical filter is deformed due to the airflow pressure, which not only filters impurities in the airflow on the elastic conical filter, but also shakes off impurities on its surface due to the amplitude generated by the elastic reset of the elastic conical filter itself, thereby avoiding impurities clogging the elastic conical filter and reducing the airflow delivery efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the present invention, the following briefly introduces the drawings required to be used in some embodiments of the present invention. Obviously, the drawings described below are only drawings of some embodiments of the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams, and are not limitations on the actual size of the product involved in the embodiments of the present invention, the actual process of the method, the actual timing of the signal, etc.

[0012] Figure 1 It is a schematic diagram of the principle of the flue gas heat cycle secondary combustion of the present invention.

[0013] Figure 2It is a schematic diagram of the overall structure of the present invention.

[0014] Figure 3 It is a side view of the overall structure of the present invention.

[0015] Figure 4 It is a cross-sectional view of the pressurized treatment cylinder, the gas mixing treatment chamber, the partition plate and the second through hole of the present invention.

[0016] Figure 5 It is a stereoscopic diagram of the driving motor, crankshaft, eccentric disc, third traction member, second traction member and first through hole of the present invention.

[0017] Figure 6 It is a stereoscopic diagram of the pressurized treatment cylinder, the gas mixing treatment chamber, the atomizing joint and the electric butterfly valve of the present invention.

[0018] Figure 7 It is a stereoscopic diagram of the guide rod, the piston, the first traction member and the slide rod of the present invention.

[0019] Figure 8 For the present invention Figure 5 Exploded diagram.

[0020] The accompanying drawings are marked as follows: 1. Base; 101. Support frame; 102. Driving motor; 103. Crankshaft; 104. Support plate; 105. Eccentric disc; 2. Pressurized treatment cylinder; 201. Mixed gas treatment chamber; 202. Partition plate; 203. Diverter hole; 204. First through hole; 205. Second through hole; 206. Blocking frame; 207. Mixing chamber; 208. Atomizing joint; 209. Electric butterfly valve; 210. Elastic conical filter; 211. One-way valve; 3. Guide rod; 301. Sliding rod; 302. First traction member; 303. Limiting seat; 304. Second traction member; 305. Third traction member; 306. Piston; 307. Pull rod. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The terms "first", "second", "third" in the embodiments of the present application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second", "third" can expressly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] As attached Figure 2-Figure 8 The boiler flue gas purification device shown in the figure, through the flow guide processing component set on the base 1, adjusts the size of the airflow delivered to the mixed gas processing chamber 201 through the electric butterfly valve 209, which is easy to make appropriate adjustments according to the flue gas air volume to avoid the phenomenon of backflow, and the blocking frame 206 moves up and down so that different first through holes 204, second through holes 205 and diversion holes 203 can be interconnected in the mixing chamber 207, which is easy for the flue gas to flow through the second through holes 205 in the booster treatment cylinder 2, and it is convenient for the treatment medium to mix with the flue gas, which is used to reduce the emission of pollutants in the flue gas to achieve environmental protection effects, and the elastic conical filter 210 is deformed due to the airflow pressure, not only filtering impurities in the airflow on the elastic conical filter 210, but also shaking off impurities on its surface through the amplitude generated by the elastic reset of the elastic conical filter 210 itself, so as to avoid impurities blocking the elastic conical filter 210 and causing the airflow transmission efficiency to decrease, and the specific structure of the component is set as follows; The diversion treatment component includes a support frame 101 arranged on the top of the base 1, a support plate 104 is arranged on one side of the top of the support frame 101, a driving motor 102 is installed on the top of the support frame 101 by bolts, a crankshaft 103 is fixedly arranged at the output end of the driving motor 102, and an eccentric disk 105 is fixedly arranged at one end of the crankshaft 103.

[0025] The top of the support plate 104 is bolted with a booster treatment cylinder 2, a surface side of the booster treatment cylinder 2 is bolted with a mixed gas treatment chamber 201, a partition 202 is bolted between the mixed gas treatment chamber 201 and the booster treatment cylinder 2, a plurality of diversion holes 203 are formed through the partition 202, a first through hole 204 is formed through the side of the booster treatment cylinder 2 facing the partition 202, a second through hole 205 is formed at the top and bottom of the first through hole 204, and the mixed gas treatment chamber 201 is provided with a plurality of diversion holes 203. A sealing frame 206 is provided in 201 and is located on one side of the partition 202. A mixing chamber 207 is opened on the sealing frame 206. An atomizing joint 208 is inserted on one side of the surface of the boost treatment cylinder 2. The atomizing joint 208 is connected to the first through hole 204. An electric butterfly valve 209 is inserted on the mixed gas treatment chamber 201. An elastic conical filter screen 210 is provided at the bottom of the inner cavity of the boost treatment cylinder 2. A one-way valve 211 extending to the middle of the elastic conical filter screen 210 is inserted at the bottom of the support plate 104.

[0026] A guide rod 3 is installed on the top of the boost treatment cylinder 2 by bolts, and a slide rod 301 is slidably connected to the guide rod 3. Both ends of the slide rod 301 are rotatably connected to the first traction member 302, and the bottom of the first traction member 302 extends to the eccentric disk 105 and is movably connected to the eccentric disk 105 by an axle pin. A limited seat 303 is arranged at the bottom of the mixing gas treatment chamber 201, and the limited seat 303 is installed on the support plate 104 by bolts. The second traction member 304 is rotatably connected in the first traction member 302, and one end of the second traction member 304 is movably connected to the third traction member 305 by an axle pin, and one end of the third traction member 305 is sleeved on the crankshaft 103 and is rotatably connected to the crankshaft 103, a piston 306 extending into the boost treatment cylinder 2 is installed on the slide rod 301 by bolts, and a pull rod 307 extending to the sealing frame 206 is installed on the second traction member 304 by bolts.

[0027] The method of reducing nitrogen oxides by secondary return air combustion is to use boiler flue gas purification equipment, such as Figure 1 As shown, the following steps are included.

[0028] Step 1: The boiler flue gas purification device is installed at one end of the recirculating flue gas duct, and the other end of the recirculating flue gas duct is connected to the flue gas recirculation fan. The flue gas flows to the recirculating flue gas duct through the boiler flue gas purification device, and moves along the flue gas recirculation fan to two groups of primary fans, which are divided into A primary fans and B primary fans, and flows into the furnace of the combustion chamber along the primary fans; Step 2, primary combustion stage: The fuel is decomposed by heat in the combustion chamber, releasing combustible gases. These combustible gases are mixed with the air entering through the primary air inlet, and are initially burned to release heat. Due to insufficient air supply, part of the fuel is not completely burned, generating a large amount of pollutants; Step 3, secondary combustion stage: As the primary combustion proceeds, the temperature and oxygen concentration gradually increase, and the secondary air enters the combustion chamber from the secondary air inlet and mixes with the incompletely burned fuel to form secondary combustion, so that the fuel can be fully burned, reducing the emission of pollutants. With the rapid increase in temperature and oxygen concentration, the complete combustion of the fuel is further promoted, releasing more heat and less pollutants; Step 4: The primary fan B is arranged to enter from the short direction of the furnace to form a strong air flow injected into the furnace combustion chamber with a speed of more than 50m / s, which supplements the air required for fuel combustion and strengthens the back mixing of materials, adjusts the distribution of the temperature field in the furnace, and makes the flue gas temperature distribution more uniform; Step 5, during the operation of the circulating fluidized bed boiler, the load of the boiler is effectively adjusted by adjusting the ratio of the two sets of primary fans. In the lower part of the circulating fluidized bed boiler, i.e., the dense phase zone, the fluidization form of the material is in a turbulent fluidization state, and in the middle and upper part of the furnace, i.e., the dilute phase zone, it gradually transitions to a fast fluidization state. Due to the addition of the secondary air volume, the flue gas flow velocity above the secondary air nozzle is increased, so that more materials participate in the circulation inside and outside the furnace, and the circulating materials with low temperature return to the dense phase zone, absorb heat in the dense phase zone, take away the heat released by combustion, and exchange heat with the water-cooled wall in the middle and upper part of the furnace, so as to improve the heat transfer coefficient and transfer energy, maintain the bed temperature in the dense phase zone, and increase the boiler load; Step 6: Treatment of organic waste gas: The organic waste gas contained in the flue gas generated after the combustion of the biomass boiler is transported to the recirculating flue gas duct through the induced draft fan, transported by the flue gas recirculation fan, and treated by the cyclone separator; The flue gas treated by the cyclone separator recovers the heat energy in the exhaust gas through the tail flue, is continuously transported by the flue gas, and the dust in the flue gas is filtered out by the dust collector and discharged through the chimney to achieve the purpose of purifying the flue gas.

[0029] When in use according to the above structure, the flue gas is transported to the electric butterfly valve 209 through the pump and the conduit, and the liquid medium for purifying the flue gas is transported through the atomizing joint 208, and is transported to the mixed gas treatment chamber 201 after the air flow is adjusted by the electric butterfly valve 209. The drive motor 102 is started to drive the crankshaft 103 to rotate, and the second traction member 304 is deflected so that the pull rod 307 drives the sealing frame 206 to move up and down in the mixed gas treatment chamber 201. When the crankshaft 103 rotates, it can also drive the eccentric disk 105 to rotate, so that the first traction member 302 drives the sliding rod 301 to slide on the guide rod 3, and then the piston 306 moves up and down in the boost treatment cylinder 2.

[0030] When the blocking frame 206 is displaced, the first through hole 204 and the second through hole 205 at the top of the first through hole 204 are connected together with the corresponding diversion hole 203, and the downward displacement of the blocking frame 206 makes the first through hole 204 and the second through hole 205 at the bottom of the first through hole 204 connected together with the corresponding diversion hole 203, so that the atomization joint 208 can atomize the purified liquid medium and then transport it to the mixing chamber 207 through the first through hole 204, and the piston 306 can be moved up and down to make the flue gas mixed in the mixing chamber 207 be drawn into the pressurized treatment cylinder 2 through the second through hole 205, and the flue gas is squeezed by the downward displacement of the piston 306 and filtered through the elastic conical filter 210 and then discharged through the one-way valve 211, and when the piston 306 is pressed down, the elastic conical filter 210 is deformed, and the amplitude generated by the elastic reset of the elastic conical filter 210 shakes off the impurities on its surface.

[0031] Different from the prior art, the present application discloses a boiler flue gas purification device and a method for reducing nitrogen oxides by secondary return air combustion. The size of the airflow delivered to the mixing treatment chamber 201 is adjusted by an electric butterfly valve 209, which is easy to make appropriate adjustments according to the flue gas volume to avoid backflow. The sealing frame 206 moves up and down so that different first through holes 204, second through holes 205 and diversion holes 203 can be interconnected in the mixing chamber 207, which makes it easy for the flue gas to flow through the second through holes 205 in the boost treatment cylinder 2, and facilitates the mixing of the treatment medium and the flue gas, so as to reduce the emission of pollutants in the flue gas and achieve environmental protection effects. The elastic conical filter 210 is deformed due to the airflow pressure, which not only filters the impurities in the airflow on the elastic conical filter 210, but also shakes off the impurities on its surface through the amplitude generated by the elastic reset of the elastic conical filter 210 itself, so as to avoid impurities clogging the elastic conical filter 210 and causing a decrease in the airflow delivery efficiency.

[0032] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A boiler flue gas purification device, comprising a base (1), characterized in that: The base (1) is provided with a flow diversion processing component; The diversion processing assembly comprises a support frame (101) arranged on the top of the base (1), and a support plate (104) is arranged on one side of the top of the support frame (101); A boost treatment cylinder (2) is installed on the top of the support plate (104) by means of bolts, a mixed gas treatment chamber (201) is installed on one side of the surface of the boost treatment cylinder (2) by means of bolts, a partition (202) is installed between the mixed gas treatment chamber (201) and the boost treatment cylinder (2) by means of bolts, a plurality of diversion holes (203) are penetrated through the partition (202), a first through hole (204) is penetrated through the side of the boost treatment cylinder (2) facing the partition (202), a second through hole (205) is provided at the top and bottom of the first through hole (204), a sealing frame (206) is provided in the mixed gas treatment chamber (201) and is located on one side of the partition (202), and a mixing chamber (207) is provided on the sealing frame (206).

2. The boiler flue gas purification device according to claim 1, characterized in that: A driving motor (102) is mounted on the top of the support frame (101) by means of bolts, a crankshaft (103) is fixedly disposed at the output end of the driving motor (102), and an eccentric disk (105) is fixedly disposed at one end of the crankshaft (103).

3. The boiler flue gas purification device according to claim 2, characterized in that: A guide rod (3) is installed on the top of the pressurized treatment cylinder (2) via bolts, a slide rod (301) is slidably connected to the guide rod (3), and both ends of the slide rod (301) are rotatably connected to a first traction member (302).

4. The boiler flue gas purification device according to claim 3, characterized in that: The bottom of the first traction member (302) extends onto the eccentric disk (105) and is movably connected to the eccentric disk (105) via a shaft pin.

5. The boiler flue gas purification device according to claim 4, characterized in that: A limit seat (303) is provided at the bottom of the gas mixing processing chamber (201); the limit seat (303) is mounted on the support plate (104) via bolts; and a second traction member (304) is rotatably connected inside the first traction member (302).

6. The boiler flue gas purification device according to claim 5, characterized in that: One end of the second traction member (304) is movably connected to the third traction member (305) via a shaft pin, and one end of the third traction member (305) is sleeved on the crankshaft (103) and rotatably connected to the crankshaft (103).

7. The boiler flue gas purification device according to claim 6, characterized in that: A piston (306) extending into the pressurized treatment cylinder (2) is mounted on the sliding rod (301) via bolts, and a pull rod (307) extending to the sealing frame (206) is mounted on the second traction member (304) via bolts.

8. The boiler flue gas purification device according to claim 7, characterized in that: An atomizing joint (208) is plugged into one side of the surface of the pressurized treatment cylinder (2); the atomizing joint (208) is connected to the first through hole (204); and an electric butterfly valve (209) is plugged into the gas mixing treatment chamber (201).

9. The boiler flue gas purification device according to claim 8, characterized in that: An elastic conical filter (210) is provided at the bottom of the inner cavity of the pressurized treatment cylinder (2), and a one-way valve (211) extending to the middle of the elastic conical filter (210) is inserted at the bottom of the support plate (104).

10. A method for reducing nitrogen oxides by secondary return air combustion, using the boiler flue gas purification device according to claim 9, characterized in that: The following steps are involved: Step 1: The boiler flue gas purification device is installed at one end of the recirculating flue gas duct, and the other end of the recirculating flue gas duct is connected to the flue gas recirculation fan. The flue gas flows to the recirculating flue gas duct through the boiler flue gas purification device, and moves along the flue gas recirculation fan to two groups of primary fans, which are divided into A primary fans and B primary fans, and flows into the furnace of the combustion chamber along the primary fans; Step 2, initial combustion stage: the fuel is decomposed by heat in the combustion chamber, releasing combustible gases, which are mixed with the air entering through the primary air inlet, undergo preliminary combustion, and release heat; Step 3, secondary combustion stage: As the primary combustion proceeds, the temperature and oxygen concentration gradually increase, and the secondary air enters the combustion chamber from the secondary air inlet and mixes with the incompletely burned fuel to form secondary combustion, so that the fuel can be fully burned; Step 4: The primary fan B is arranged to enter from the short direction of the furnace to form a strong air flow injected into the furnace combustion chamber with a speed of more than 50m / s, which supplements the air required for fuel combustion and strengthens the back mixing of materials, adjusts the distribution of the temperature field in the furnace, and makes the flue gas temperature distribution more uniform; Step 5, during the operation of the circulating fluidized bed boiler, the load of the boiler is effectively adjusted by adjusting the ratio of the two sets of primary fans. In the lower part of the circulating fluidized bed boiler, i.e., the dense phase zone, the fluidization form of the material is in a turbulent fluidization state, and in the middle and upper part of the furnace, i.e., the dilute phase zone, it gradually transitions to a fast fluidization state. Due to the addition of the secondary air volume, the flue gas flow velocity above the secondary air nozzle is increased, so that more materials participate in the circulation inside and outside the furnace, and the circulating materials with low temperature return to the dense phase zone, absorb heat in the dense phase zone, take away the heat released by combustion, and exchange heat with the water-cooled wall in the middle and upper part of the furnace, so as to improve the heat transfer coefficient and transfer energy, maintain the bed temperature in the dense phase zone, and increase the boiler load; Step 6: Treatment of organic waste gas: The organic waste gas contained in the flue gas generated after the combustion of the biomass boiler is transported to the recirculating flue gas duct through the induced draft fan, transported by the flue gas recirculation fan, and treated by the cyclone separator; The flue gas treated by the cyclone separator recovers the heat energy in the exhaust gas through the tail flue, is continuously transported by the flue gas, and the dust in the flue gas is filtered out by the dust collector and discharged through the chimney to achieve the purpose of purifying the flue gas.

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