A built-in flap valve of a circulating fluidized bed boiler and an SCR denitration system thereof

Abstract

The present application belongs to the technical field of circulating fluidized bed boiler, and discloses an inner built flap valve and an SCR denitration system thereof, which solves the problems of traditional flap valve, such as easy deformation, poor sealing, easy ash accumulation in shaft sleeve, unadjustable counterweight torque and single function. The inner built flap valve comprises a valve body, a flap block, a valve shaft assembly and a counterweight assembly. The valve shaft assembly supports the flap block and the counterweight assembly at both ends to realize linkage overturning. The flap block is of an integrated thick wall structure and is internally provided with an evaporation zone and the like. The high temperature is used to realize the evaporation of the reducing agent through the heat storage column, and the sealing performance is improved through the two side arc surfaces. The valve shaft assembly adopts a combined anti-ash shaft sleeve to actively discharge ash and prevent jamming. The counterweight assembly can flexibly adjust the counterweight torque to adapt to multiple working conditions. The SCR denitration system uses the flap valve as an evaporator to simplify the structure and reduce the energy consumption. The present application improves the stability and sealing performance of the flap valve, adapts to multiple working conditions, and ensures the stable operation of the boiler and the denitration standard.

Description

Technical Field

[0001] This invention belongs to the field of circulating fluidized bed boiler technology, specifically relating to a built-in flap valve for a circulating fluidized bed boiler and its SCR denitrification system. Background Technology

[0002] In the high-temperature flue gas or fly ash system of a circulating fluidized bed boiler (CFB), the flap valve is mainly used for airlocking, ash discharge, and preventing backflow of high-temperature flue gas. It is a key component to ensure the airtightness and stable operation of the system, and its performance directly affects the high-temperature flue gas treatment efficiency, fly ash conveying stability, and the operation effect of the subsequent denitrification system. The normal operation of the flap valve depends on the precise matching of the flap and the counterweight torque to achieve flexible flap rotation under appropriate pressure, balancing the dual requirements of airlock sealing and ash discharge flow.

[0003] Currently, the traditional flap valves used in the high-temperature flue gas or fly ash systems of circulating fluidized bed boilers have several shortcomings: First, to ensure flexible flap rotation and facilitate the flow of high-temperature flue gas and smooth discharge of fly ash, the flaps are usually designed to be thin, making them prone to deformation and resulting in poor sealing when closed. Second, the sealing performance between the bushing and the valve shaft is insufficient, allowing fly ash and flue gas dust generated during boiler operation to easily enter the bushing, causing wear and jamming, and hindering flap rotation. Third, the counterweight torque of the flap valve is designed as a fixed structure, making it impossible to adjust the counterweight torque and resulting in extremely poor adaptability: when flue gas pressure and fly ash flow fluctuate within the system, the fixed counterweight torque cannot adapt to changes in operating conditions in a timely manner. Either the torque is too large, causing the flap to fail to open properly, resulting in fly ash accumulation and pipe blockage; or the torque is too small, causing the flap to close loosely, exacerbating air and ash leakage problems, and failing to meet the precise requirements for airlocking and ash discharge under different operating conditions.

[0004] Furthermore, with increasingly stringent environmental protection requirements, nitrogen oxides (NOx) are becoming more prevalent. x Emission control has become a crucial performance indicator for coal-fired boiler operation. Selective catalytic reduction (SCR), currently the most mature and efficient denitrification technology, has been widely applied in flue gas denitrification treatment of circulating fluidized bed boilers. Its core principle is to precisely deliver a reducing agent (commonly ammonia water) to the reaction zone, where, under the action of a catalyst, nitrogen oxides are converted into harmless nitrogen and water, achieving denitrification and compliant emissions. Traditional flap valves cannot utilize the heat from high-temperature flue gas or fly ash to achieve the evaporation and vaporization of ammonia water.

[0005] In view of this, the inventors aim to design an optimized built-in flap valve for a circulating fluidized bed boiler and its SCR denitrification system. Summary of the Invention

[0006] This invention addresses the shortcomings of traditional flap valves in terms of structural design and functional adaptation, namely, easy deformation of the flap, poor sealing performance, inability to adjust the counterweight torque, easy ash ingress into the bushing, and limited functionality. It designs a built-in flap valve and its SCR denitrification system that can ensure flexible flap rotation and improved sealing performance, while also enabling adjustable counterweight torque, optimized bushing structure, and linkage with the SCR denitrification system for efficient delivery of reducing agent. This ensures stable and efficient operation of circulating fluidized bed boilers and compliance with denitrification emission standards.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: This invention provides a built-in flap valve for a circulating fluidized bed boiler, comprising a valve body, a flap plate, a valve shaft assembly, and a counterweight assembly. Two valve shaft assemblies are symmetrically installed on the valve body. The two valve shaft assemblies support the flap plate at one end inside the valve body and support the counterweight assembly at the other end outside the valve body, thereby achieving synchronous linkage and flipping of the flap plate and the counterweight assembly. The flapper plate is a one-piece thick-walled structure, with an evaporation zone and a liquid inlet zone and an outlet zone located on both sides of the evaporation zone. The evaporation zone is divided into an upper gas guide chamber and a lower heating chamber by a gas-liquid separation baffle. The upper gas guide chamber is connected to the outlet zone, and the lower heating chamber is connected to the liquid inlet zone. The lower heating chamber is equipped with a demister mesh on the side near the gas-liquid separation baffle to intercept liquid reducing agent droplets and prevent unevaporated reducing agent from entering the subsequent system with the flue gas. Several heat storage columns are evenly distributed in the area of ​​the flapper plate in the liquid inlet zone, penetrating the gas-liquid separation baffle. The heat storage columns are used to absorb the heat of high-temperature flue gas or fly ash and transfer it to the lower heating chamber to achieve efficient evaporation of the reducing agent. The flapper plate has symmetrical stepped through holes on both sides, which are connected to the liquid inlet zone and the outlet zone respectively, for the valve shaft assembly to pass through and realize the introduction of reducing agent and the export of evaporated gas.

[0008] Furthermore, the upper side of the flap plate is provided with a grid-shaped heat-conducting surface to increase the contact area between the flap plate and high-temperature flue gas and fly ash, thereby improving heat storage and heat conduction efficiency; the front and rear ends of the flap plate are respectively provided with a first arc surface and a second arc surface, both of which are rotated around the axis of the stepped through hole, for use in conjunction with the valve body to achieve precise sealing and avoid air and ash leakage.

[0009] Furthermore, the valve body is a rectangular structure with an internal material flow channel. The upper side of the valve body in the material flow channel has a chamfered surface to guide the ash material to slide smoothly and avoid ash material accumulation. The valve body has symmetrical bushing mounting holes on both sides for installing valve shaft assemblies. The front and rear inner sidewalls of the valve body in the material flow channel are respectively provided with a first sealing surface that fits and conforms to the first arc surface and a second sealing surface that fits and conforms to the second arc surface, improving the sealing performance when the flapper plate is closed. A limiting protrusion is formed between the first sealing surface and the chamfered surface to prevent the flapper plate from over-flipping upwards, avoiding collision damage between the flapper plate and the valve body, and limiting the maximum opening angle of the flapper plate.

[0010] Furthermore, the valve shaft assembly includes a support shaft tube, a liquid guide slip ring, a flow guide tube, and a combined anti-ash-entry bushing. One end of the support shaft tube is rotatably connected to the flow guide tube via the liquid guide slip ring, enabling dynamic delivery of the reducing agent without affecting the rotation of the support shaft tube. The other end of the support shaft tube is inserted and fixed in the stepped through hole corresponding to the flip plate, rotating synchronously with the flip plate. A torque transmission key is provided on the shaft body outside the bushing mounting hole of the support shaft tube for transmitting torque. A combined anti-ash-entry bushing is fitted on the outer side of the shaft body inside the bushing mounting hole of the support shaft tube to prevent fly ash and flue gas dust from entering the bushing mounting hole, thus avoiding jamming and wear of the valve shaft assembly.

[0011] Furthermore, the combined anti-ash-ingress bushing consists of a fixed bushing and a movable bushing. The fixed bushing is fixedly installed in the bushing mounting hole and is located near the outer side of the valve body. One side of the movable bushing is provided with an anti-detachment ring, which is rotatably limited within the fixed bushing to prevent the movable bushing from moving axially. The outer side of the movable bushing is provided with an ash-discharging screw blade, the outer diameter of which matches the inner diameter of the bushing mounting hole. An internal gear ratchet mechanism is provided between the movable bushing and the support shaft tube. Driven by the internal gear ratchet mechanism, the movable bushing rotates intermittently in one direction. During the rotation, the fly ash and flue gas dust entering the bushing mounting hole are discharged outward through the ash-discharging screw blade, thus achieving active anti-blocking and anti-ash-ingress.

[0012] Furthermore, the internal gear ratchet mechanism consists of an internal ratchet groove, a receiving groove, a pawl, a pin, a cam, and a compression spring; the inner wall of the moving shaft sleeve is uniformly provided with multiple internal ratchet grooves along the circumference; the outer side of the support shaft tube is provided with a receiving groove; one end of the pawl is rotatably connected to one end of the receiving groove via a pin, and the other end is a free end; a cam is fixedly installed at the other end of the receiving groove, and the cam is elastically connected to the free end of the pawl via a compression spring, so that the pawl is always engaged with the internal ratchet groove; when the support shaft tube drives the pawl to rotate, the engagement between the pawl and the internal ratchet groove drives the moving shaft sleeve to achieve intermittent unidirectional rotation.

[0013] Furthermore, the counterweight assembly includes a torque transmission sleeve, a support tube sleeve, a counterweight torque tube sleeve, a counterweight frame, a counterweight block, fasteners, and an adjusting push rod. The torque transmission sleeve is sleeved and installed on the outside of the support shaft tube, and its inner wall has a torque transmission keyway that matches and engages with the torque transmission key, realizing synchronous rotation between the torque transmission sleeve and the support shaft tube. The support tube sleeve is fixedly connected to the outside of the torque transmission sleeve, and the counterweight torque tube sleeve is slidably sleeved on the outside of the support tube sleeve. The outer ends of the two counterweight torque tube sleeves are fixedly installed with a counterweight frame, and the counterweight frame is detachably installed with a counterweight block by fasteners, which facilitates adjustment of the total weight of the counterweight. The adjusting push rod is located inside the support tube sleeve, and its cylinder is fixed on the adjacent torque transmission sleeve. Its movable end is fixedly connected to the counterweight frame. By adjusting the extension and retraction of the adjusting push rod, the counterweight frame is driven to move axially along the support tube sleeve, thereby adjusting the counterweight torque of the counterweight to adapt to different working conditions.

[0014] Furthermore, the counterweight torque sleeve has an internal groove that matches the shape of the support sleeve, allowing the counterweight torque sleeve to slide smoothly along the support sleeve; the outer end plate of the counterweight torque sleeve has a positioning hole; the counterweight frame is a slotted frame structure, and the outer ends of its two side plates are provided with positioning blocks that can be inserted into the positioning holes, realizing precise positioning and fixing of the counterweight frame and the counterweight torque sleeve; the web plate of the slotted frame has a row of fastening holes along its length, which facilitates adjusting the number of counterweight blocks installed on the counterweight frame through fasteners.

[0015] Furthermore, the valve body and the flapper plate are both installed inside the high-temperature flue gas duct of the circulating fluidized bed boiler, and the counterweight assembly is installed on the outside of the high-temperature flue gas duct to avoid the influence of high temperature on the counterweight assembly; the high-temperature flue gas duct has symmetrical perforations on both sides, and the support shaft tube in the valve shaft assembly extends through the perforations to the outside of the duct. A shaft seal is installed at the perforation to seal the gap between the support shaft tube and the perforation to prevent high-temperature flue gas leakage.

[0016] This invention also provides an SCR denitrification system, including a reducing agent supply unit, an ammonia injection mixing unit, and an SCR reactor. The reducing agent supply unit consists of a liquid ammonia storage tank, an evaporator, and a buffer tank. The buffer tank is connected to the ammonia injection mixing unit. The ammonia injection mixing unit and the SCR reactor are located in the low-temperature flue gas pipeline where the economizer is located. The evaporator adopts the aforementioned circulating fluidized bed boiler built-in flap valve, which utilizes the heat from the high-temperature flue gas or fly ash absorbed by the flap plate to achieve efficient evaporation and gasification of ammonia water, replacing the traditional independent evaporator, simplifying the system structure, reducing equipment costs, and simultaneously achieving the linkage and synergy between the flap valve's airlock and ash discharge and the SCR denitrification reducing agent evaporation, thereby improving denitrification efficiency.

[0017] The beneficial effects of this invention are: 1. The flapping plate adopts an integrated thick-walled structure. The first and second arc surfaces on both sides of the flapping plate are adapted and fitted to the first and second sealing surfaces on the inside of the valve body. The limiting protrusion on the valve body can also limit the maximum opening angle of the flapping plate, further realizing the precise balance between air-lock sealing and ash discharge flow, greatly reducing air and ash leakage problems, and ensuring the operational stability of the boiler high-temperature flue gas or fly ash system.

[0018] 2. The flap valve is internally configured with an evaporation zone, a liquid inlet zone, and a gas outlet zone. It absorbs the heat from the high-temperature flue gas or fly ash through a heat storage column and transfers it to the lower heating chamber. Combined with a demister mesh to intercept liquid reducing agent droplets, it can efficiently achieve the evaporation and vaporization of reducing agents such as ammonia water, and prevent unevaporated reducing agents from entering the subsequent system with the flue gas. At the same time, this invention uses the flap valve as the evaporator of the denitrification system, replacing the traditional independent evaporator, simplifying the structure of the denitrification system, reducing equipment investment costs, and making full use of the heat from the boiler's own high-temperature flue gas and fly ash to achieve waste heat recovery and utilization, reduce the overall energy consumption of the system, and improve denitrification efficiency.

[0019] 3. The valve shaft assembly adopts a combined anti-ash-ingress bushing. The fixed bushing is fixedly installed in the bushing mounting hole, and the moving bushing is axially limited by an anti-detachment ring. The ash discharge screw on the outside of the moving bushing is adapted to the inner diameter of the bushing mounting hole. At the same time, the internal gear ratchet mechanism drives the moving bushing to rotate intermittently in one direction. During the rotation, the ash discharge screw actively discharges the fly ash and dust that have entered the bushing mounting hole, effectively preventing fly ash and flue gas dust from entering the bushing, avoiding jamming and wear of the valve shaft assembly, and reducing maintenance costs and downtime losses.

[0020] 4. The counterweight assembly drives the counterweight frame to move axially along the support tube sleeve by adjusting the extension and retraction of the push rod, which can flexibly adjust the counterweight torque of the counterweight; at the same time, the counterweight blocks can be detachably installed on the counterweight frame by fasteners, and the total weight can be changed by adjusting the number of counterweight blocks installed, so as to meet the precise requirements of airlock and ash unloading under different working conditions.

[0021] Of course, any product implementing this invention does not necessarily need to achieve all of the above advantages at the same time. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of the flap valve of the present invention; Figure 2 This is a schematic diagram showing the installation position of the flap valve of the present invention; Figure 3 This is a schematic diagram of the structure of the flip plate in this invention; Figure 4 This is a top view of the flip-up plate in this invention; Figure 5 This is a schematic diagram of the front view of the flip-up plate in this invention; Figure 6 This is a schematic diagram of the structure of the present invention with the flip-up plates omitted; Figure 7 This is a half-sectional schematic diagram of the valve body in this invention; Figure 8 This is a schematic diagram of the valve shaft assembly in this invention; Figure 9 This is a half-sectional schematic diagram of the combined anti-dust bushing in this invention; Figure 10 This is a schematic diagram of the internal gear ratchet mechanism in this invention; Figure 11 This is a schematic diagram of the counterweight component in this invention; Figure 12 This is an exploded view of the counterweight component in this invention; Figure 13 This is a schematic diagram of the structure of the torsion sleeve and the support sleeve in this invention; Figure 14 This is a schematic diagram of the assembly of the support sleeve and the counterweight torque sleeve in this invention; Figure 15 This is a schematic diagram of the structure of the counterweight frame in this invention; In the attached diagram, the components represented by each number are as follows: 1-Valve body, 101-Material flow channel, 102-Chamfered surface, 103-Sleeve mounting hole, 104-First sealing surface, 105-Second sealing surface; 2-Flip plate, 2a-Evaporation zone, 2b-Liquid inlet zone, 2c-Gas outlet zone, 201-Gas-liquid separation baffle, 202-Upper gas guide chamber, 203-Lower heating chamber, 204-Defoaming mesh, 205-Heat storage column, 206-Stepped through hole, 207-First arc surface, 208-Second arc surface, 209-Grid-shaped heat conduction surface; 3-Valve shaft assembly, 31-Support shaft tube, 311-Torque transmission key, 312-Receiving groove, 313-Pin, 314-Pawl, 315-Protruding rod, 316-Compression spring, 32-Liquid guide ring, 33-Flow guide tube, 34-Fixed shaft sleeve, 35-Moving shaft sleeve, 351-Anti-detachment ring, 352-Inner ratchet groove, 353-Ash discharge screw blade; 4-Counterweight assembly, 41-Torque transmission sleeve, 42-Support sleeve, 43-Counterweight torque sleeve, 431-Slide groove, 432-Positioning hole, 44-Flag frame, 441-Positioning block, 442-Fastening hole, 45-Flag block, 46-Fastener, 47-Adjusting push rod; 5-High-temperature flue gas duct. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 Figure 1 and Figure 6 As shown, this embodiment provides a built-in flap valve for a circulating fluidized bed boiler, including a valve body 1, a flap plate 2, a valve shaft assembly 3, and a counterweight assembly 4.

[0026] like Figure 7 As shown, the valve body 1 is a rectangular structure with an internal material flow channel 101. The upper side of the material flow channel 101 has an integrally formed chamfered surface 102, which can guide the ash material to slide smoothly. The left and right sides of the valve body 1 are symmetrically provided with bushing mounting holes 103. The front and rear inner sidewalls of the material flow channel 101 are respectively machined with a first sealing surface 104 and a second sealing surface 105. A limiting protrusion is integrally formed between the first sealing surface 104 and the chamfered surface 102. The limiting protrusion is used to prevent the flip plate 2 from flipping excessively upward.

[0027] like Figures 3-5 As shown, the flap plate 2 is a one-piece thick-walled structure, internally processed with an evaporation zone 2a, a liquid inlet zone 2b, and a gas outlet zone 2c. The liquid inlet zone 2b is located to the left of the evaporation zone 2a, and the gas outlet zone 2c is located to the right of the evaporation zone 2a. The evaporation zone 2a is divided into an upper gas guide chamber 202 and a lower heating chamber 203 by a gas-liquid separation baffle 201. The upper gas guide chamber 202 is connected to the gas outlet zone 2c, and the lower heating chamber 203 is connected to the liquid inlet zone 2b. The side of the lower heating chamber 203 closest to the gas-liquid separation baffle 201 is welded... The plate 2 is equipped with a demister mesh 204; the plate 2 is located in the liquid inlet zone 2b and is evenly distributed with 6 heat storage columns 205 that penetrate the gas-liquid separation baffle 201. The heat storage columns 205 are made of ceramic material and have a diameter of 8-10 mm. They are used to absorb the heat of high-temperature flue gas or fly ash and transfer it to the lower heating chamber 203; the left and right sides of the plate 2 are symmetrically provided with stepped through holes 206. The stepped through holes 206 are respectively connected to the liquid inlet zone 2b and the gas outlet zone 2c, and are used for the valve shaft assembly 3 to pass through.

[0028] The upper side of the flap plate 2 is machined with a grid-shaped heat-conducting surface 209 to increase the contact area between the flap plate 2 and the high-temperature flue gas and fly ash. The front and rear ends of the flap plate 2 are respectively machined with a first arc surface 207 and a second arc surface 208. The first arc surface 207 and the second arc surface 208 are both rotated around the axis of the stepped through hole 206. The first arc surface 207 is adapted to fit the first sealing surface 104 on the inner side of the valve body 1, and the second arc surface 208 is adapted to fit the second sealing surface 105 to achieve precise sealing.

[0029] like Figure 8 As shown, the valve shaft assembly 3 includes a support shaft tube 31, a liquid guide slip ring 32, a flow guide tube 33, and a combined anti-ash bushing. One end of the support shaft tube 31 is rotatably connected to the flow guide tube 33 through the liquid guide slip ring 32, which can realize the dynamic delivery of the reducing agent without affecting the rotation of the support shaft tube 31. The other end of the support shaft tube 31 is welded and fixed in the stepped through hole 206 corresponding to the flip plate 2, and rotates synchronously with the flip plate 2. A torque transmission key 311 is integrally formed on the shaft body of the support shaft tube 31 located outside the bushing mounting hole 103 for transmitting torque. A combined anti-ash bushing is sleeved on the outer side of the shaft body of the support shaft tube 31 located inside the bushing mounting hole 103.

[0030] During the flipping process, the support shaft tube 31 drives the pawl 314 to rotate. The engagement between the pawl 314 and the inner ratchet groove 352 drives the moving shaft sleeve 35 to rotate intermittently in one direction. When the moving shaft sleeve 35 rotates, the ash discharge screw 353 discharges the fly ash and flue gas dust that have entered the shaft sleeve mounting hole 103 to the outside, thus achieving active anti-blocking and anti-ash entry. The discharged fly ash can be cleaned periodically.

[0031] like Figure 9 As shown, the combined anti-ash bushing consists of a fixed bushing 34 and a moving bushing 35. The fixed bushing 34 is interference-fitted into the bushing mounting hole 103 and is located near the outer side of the valve body 1. An anti-detachment ring 351 is integrally formed on one side of the moving bushing 35. The anti-detachment ring 351 is rotatably limited within the fixed bushing 34 to prevent the moving bushing 35 from moving axially. An ash discharge screw blade 353 is integrally formed on the outer side of the moving bushing 35. The outer diameter of the ash discharge screw blade 353 matches the inner diameter of the bushing mounting hole 103.

[0032] like Figure 10As shown, an internal gear ratchet mechanism is provided between the moving bushing 35 and the support shaft tube 31. The internal gear ratchet mechanism consists of an internal ratchet groove 352, a receiving groove 312, a pawl 314, a pin 313, a protruding rod 315, and a compression spring 316. The inner wall of the moving bushing 35 has internal ratchet grooves 352 evenly distributed circumferentially. The outer side of the support shaft tube 31 has a receiving groove 312. One end of the pawl 314 is rotatably connected to one end of the receiving groove 312 via the pin 313, while the other end is free. One end; the other end of the receiving groove 312 is welded with a protruding rod 315, which is elastically connected to the free end of the pawl 314 through a compression spring 316, so that the pawl 314 is always engaged with the inner ratchet groove 352; when the support shaft tube 31 drives the pawl 314 to rotate, the engagement between the pawl 314 and the inner ratchet groove 352 drives the drive shaft sleeve 35 to rotate intermittently in one direction. During the rotation, the fly ash and flue gas dust that have entered the shaft sleeve mounting hole 103 are discharged to the outside through the ash discharge screw blade 353.

[0033] like Figures 11-15 As shown, the counterweight assembly 4 includes a torque transmission sleeve 41, a support tube sleeve 42, a counterweight torque tube sleeve 43, a counterweight frame 44, a counterweight block 45, a fastener 46, and an adjusting push rod 47. The torque transmission sleeve 41 is sleeved and installed on the outside of the support shaft tube 31, and its inner wall has a torque transmission keyway that matches and engages with the torque transmission convex key 311, so as to realize the synchronous rotation of the torque transmission sleeve 41 and the support shaft tube 31. The support tube sleeve 42 is welded to the outside of the torque transmission sleeve 41, and the counterweight torque tube sleeve 43 is slidably sleeved on the outside of the support tube sleeve 42. The inside of the counterweight torque tube sleeve 43 has a sliding groove 431 that matches the shape of the support tube sleeve 42, so that the counterweight torque tube sleeve 43 can slide smoothly along the support tube sleeve 42. The outer end plate of the counterweight torque tube sleeve 43 has a positioning hole 432. The two counterweight torque tube sleeves 43... The outer ends are all fixedly mounted with a counterweight frame 44 by bolts. The counterweight frame 44 is a channel-shaped frame structure. The outer ends of its two side plates are integrally formed with positioning blocks 441 that can be inserted into positioning holes 432 to achieve precise positioning of the counterweight frame 44 and the counterweight torque sleeve 43. The web of the channel-shaped frame has multiple fastening holes 442 along the length direction, which facilitates the adjustment of the number of counterweight blocks 45 installed by fasteners 46. The counterweight blocks 45 are detachably mounted on the counterweight frame 44 by fasteners 46. The adjusting push rod 47 is set inside the support sleeve 42. Its cylinder is fixed to the adjacent torque transmission sleeve 41 by bolts. The movable end is fixedly connected to the counterweight frame 44 by bolts. By adjusting the extension and retraction of the adjusting push rod 47, the counterweight frame 44 is driven to move axially along the support sleeve 42, thereby adjusting the counterweight torque of the counterweight.

[0034] The assembly process of the counterweight components is as follows: The torque transmission sleeve 41 is fitted onto the outside of the support shaft tube 31 and engaged with the torque transmission key 311 via the torque transmission keyway; the support tube sleeve 42 is welded and fixed to the torque transmission sleeve 41; the counterweight torque tube sleeve 43 is slidably fitted onto the outside of the support tube sleeve 42, and then the positioning block 441 of the counterweight frame 44 is inserted into the positioning hole 432 of the counterweight torque tube sleeve 43 and fixedly connected by bolts; according to the initial working conditions of the boiler, the counterweight block 45 is installed on the fastening hole 442 of the counterweight frame 44 using fasteners 46; the cylinder of the adjusting push rod 47 is fixed on the torque transmission sleeve 41, and the movable end is fixedly connected to the counterweight frame 44, thus completing the assembly of the counterweight assembly 4.

[0035] like Figure 2 As shown, valve body 1 and flap plate 2 are both installed inside the high-temperature flue gas duct 5 of the circulating fluidized bed boiler. Valve body 1 is fixedly connected to the inner wall of high-temperature flue gas duct 5 by welding. Counterweight assembly 4 is installed on the outside of high-temperature flue gas duct 5 to avoid the influence of high temperature on counterweight assembly 4. Symmetrical perforations are opened on both sides of high-temperature flue gas duct 5. The support shaft tube 31 in valve shaft assembly 3 extends to the outside of the duct through the perforation. A shaft seal is installed at the perforation. The shaft seal is made of high-temperature resistant ceramic fiber material and is used to seal the gap between the support shaft tube 31 and the perforation to prevent high-temperature flue gas leakage.

[0036] The installation process of the flap valve in this embodiment is as follows: The valve body 1 is welded to a designated position inside the high-temperature flue gas duct 5 of the circulating fluidized bed boiler, ensuring that the material flow channel 101 of the valve body 1 is aligned with the flue gas flow direction of the high-temperature flue gas duct 5; the fixed shaft sleeve 34 of the combined anti-ash bushing is interference-fitted into the bushing mounting hole 103 of the valve body 1; the support shaft tube 31 is passed through the bushing mounting hole 103 and the through hole of the high-temperature flue gas duct 5, so that one end of the support shaft tube 31 is interference-fitted into the stepped through hole 206 of the flip plate 2. The other end extends out of the outside of the high-temperature flue gas duct 5; the moving shaft sleeve 35 is fitted onto the outside of the support shaft tube 31, and the rotation limit between the moving shaft sleeve 35 and the fixed shaft sleeve 34 is achieved by the anti-detachment ring 351; the internal gear ratchet mechanism is assembled so that the pawl 314 meshes with the internal ratchet groove 352; the liquid guide slip ring 32 is installed at one end of the support shaft tube 31 that extends out of the valve body 1, and then the guide pipe 33 is connected; after all the components of the valve shaft assembly 3 are assembled, the shaft seal is installed at the perforation of the high-temperature flue gas duct 5.

[0037] Example 2 This example provides an SCR denitrification system, including a reducing agent supply unit, an ammonia injection mixing unit, and an SCR reactor. The reducing agent supply unit consists of a liquid ammonia storage tank, an evaporator, and a buffer tank. The liquid ammonia storage tank is connected to the liquid inlet of the evaporator through a pipeline, and the gas outlet of the evaporator is connected to the buffer tank through a pipeline. The buffer tank is connected to the ammonia injection mixing unit. The ammonia injection mixing unit and the SCR reactor are located in the low-temperature flue gas pipeline where the economizer is located.

[0038] The evaporator described above uses the built-in flap valve of the circulating fluidized bed boiler described in Example 1. The liquid inlet zone 2b of the flap plate 2 is connected to the liquid ammonia storage tank through a pipeline, and the gas outlet zone 2c is connected to the buffer tank through a pipeline. The flap plate 2 absorbs the heat of the high-temperature flue gas or fly ash in the high-temperature flue gas pipeline 5 and performs efficient evaporation and gasification of the ammonia water entering the lower heating chamber 203. After the evaporated ammonia gas is defoamed by the defoaming wire mesh 204, it is transported to the buffer tank through the gas outlet zone 2c. Then, it is mixed with the flue gas by the ammonia injection mixing unit and sent to the SCR reactor. Under the action of the catalyst, the nitrogen oxides are converted into harmless nitrogen and water, achieving denitrification and emission standards.

[0039] The operation process of this embodiment is as follows: When the circulating fluidized bed boiler is started, high-temperature flue gas and fly ash flow in the material flow channel 101. The grid-shaped heat-conducting surface 209 of the tilting plate 2 and the heat storage column 205 absorb the heat from the high-temperature flue gas and fly ash and transfer it to the lower heating chamber 203. Ammonia water in the liquid ammonia storage tank is sent to the liquid inlet area 2b of the tilting plate 2 through the guide pipe 33 and the support shaft pipe 31, and then enters the lower heating chamber 203 to be heated and evaporated into ammonia gas. After the ammonia gas is defoamed by the demister mesh 204, it is transported to the buffer tank through the gas outlet area 2c. When the boiler... When the flue gas pressure and fly ash flow rate fluctuate in the furnace system, the counterweight frame 44 is moved axially along the support sleeve 42 by adjusting the extension and retraction of the push rod 47 to adjust the counterweight torque, or the number of counterweight blocks 45 is increased or decreased to make the turning torque of the tipping plate 2 adapt to the changes in working conditions, ensuring a precise balance between airlock sealing and ash discharge flow; the ammonia gas in the buffer tank is mixed with the flue gas by the ammonia injection mixing unit and then sent to the SCR reactor to complete the denitrification reaction, and the nitrogen oxides are converted into harmless nitrogen and water before being discharged.

[0040] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementation methods. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A built-in flap valve for a circulating fluidized bed boiler, characterized in that, It includes a valve body, a flapping plate, a valve shaft assembly, and a counterweight assembly. Two valve shaft assemblies are symmetrically installed on the valve body. The two valve shaft assemblies support the flapping plate at one end inside the valve body and support the counterweight assembly at the other end outside the valve body, so as to realize the synchronous linkage and flipping of the flapping plate and the counterweight assembly. The flapper plate is a one-piece thick-walled structure, with an evaporation zone and a liquid inlet zone and a gas outlet zone located on both sides of the evaporation zone. The evaporation zone is divided into an upper gas guide chamber and a lower heating chamber by a gas-liquid separation baffle. The upper gas guide chamber is connected to the gas outlet zone, and the lower heating chamber is connected to the liquid inlet zone. The lower heating chamber is equipped with a defoaming mesh on the side near the gas-liquid separation baffle. Several heat storage columns that penetrate the gas-liquid separation baffle are evenly distributed in the area of ​​the flapper plate in the liquid inlet zone. The heat storage columns are used to absorb the heat of high-temperature flue gas or fly ash and transfer it to the lower heating chamber. The flapper plate has symmetrical stepped through holes on both sides, which are connected to the liquid inlet zone and the gas outlet zone respectively, for the valve shaft assembly to pass through and realize the introduction of reducing agent and the exhaust of gas after evaporation.

2. The built-in flap valve of a circulating fluidized bed boiler according to claim 1, characterized in that, The upper side of the flip plate is provided with a grid-shaped heat-conducting surface; the front and rear ends of the flip plate are respectively provided with a first arc surface and a second arc surface, and the first arc surface and the second arc surface are both rotated around the axis of the stepped through hole.

3. The built-in flap valve of a circulating fluidized bed boiler according to claim 2, characterized in that, The valve body is a rectangular structure with an internal material flow channel. The upper side of the valve body in the material flow channel has a chamfered surface. The valve body has symmetrical bushing mounting holes on both sides. The front and rear inner walls of the valve body in the material flow channel are respectively provided with a first sealing surface that fits and conforms to a first arc surface and a second sealing surface that fits and conforms to a second arc surface. A limiting protrusion is formed between the first sealing surface and the chamfered surface.

4. The built-in flap valve of a circulating fluidized bed boiler according to claim 3, characterized in that, The valve shaft assembly includes a support shaft tube, a liquid guide slip ring, a flow guide tube, and a combined anti-ash-ingress bushing. One end of the support shaft tube is rotatably connected to the flow guide tube via the liquid guide slip ring, and the other end of the support shaft tube is inserted and fixed in the stepped through hole corresponding to the flip plate, rotating synchronously with the flip plate. A torque transmission key is provided on the shaft body of the support shaft tube located outside the bushing mounting hole. A combined anti-ash-ingress bushing is fitted on the outer side of the shaft body of the support shaft tube located inside the bushing mounting hole.

5. A built-in flap valve for a circulating fluidized bed boiler according to claim 4, characterized in that, The combined anti-ash-entry bushing consists of a fixed bushing and a movable bushing. The fixed bushing is fixedly installed in the bushing mounting hole and is located near the outer side of the valve body. An anti-detachment ring is provided on one side of the movable bushing, and the anti-detachment ring is limited to rotation within the fixed bushing. An ash-discharging screw is provided on the outer side of the movable bushing, and the outer diameter of the ash-discharging screw matches the inner diameter of the bushing mounting hole. An internal gear ratchet mechanism is provided between the movable bushing and the support shaft tube. The movable bushing rotates intermittently in one direction under the drive of the internal gear ratchet mechanism. During the rotation, the fly ash and flue gas dust that have entered the bushing mounting hole are discharged to the outside through the ash-discharging screw.

6. A built-in flap valve for a circulating fluidized bed boiler according to claim 5, characterized in that, The internal gear ratchet mechanism consists of an internal ratchet groove, a receiving groove, a pawl, a pin, a cam, and a compression spring. Multiple internal ratchet grooves are evenly distributed circumferentially on the inner wall of the moving shaft sleeve. A receiving groove is provided on the outer side of the support shaft tube. One end of the pawl is rotatably connected to one end of the receiving groove via a pin, while the other end is free. A cam is fixedly installed at the other end of the receiving groove, and the cam is elastically connected to the free end of the pawl via a compression spring, ensuring that the pawl is always engaged with the internal ratchet groove. When the support shaft tube drives the pawl to rotate, the engagement between the pawl and the internal ratchet groove drives the moving shaft sleeve to achieve intermittent unidirectional rotation.

7. A built-in flap valve for a circulating fluidized bed boiler according to claim 6, characterized in that, The counterweight assembly includes a torque transmission sleeve, a support tube sleeve, a counterweight torque tube sleeve, a counterweight frame, a counterweight block, fasteners, and an adjusting push rod. The torque transmission sleeve is sleeved and installed on the outside of the support tube, and its inner wall has a torque transmission keyway that matches and engages with the torque transmission key, enabling synchronous rotation of the torque transmission sleeve and the support tube. The support tube sleeve is fixedly connected to the outside of the torque transmission sleeve, and the counterweight torque tube sleeve is slidably sleeved on the outside of the support tube sleeve. The outer ends of the two counterweight torque tube sleeves are fixedly installed with a counterweight frame, and the counterweight block is detachably installed on the counterweight frame by fasteners. The adjusting push rod is located inside the support tube sleeve, and its cylinder is fixed on the adjacent torque transmission sleeve. Its movable end is fixedly connected to the counterweight frame. By adjusting the extension and retraction of the adjusting push rod, the counterweight frame is driven to move axially along the support tube sleeve, thereby adjusting the counterweight torque of the counterweight.

8. A built-in flap valve for a circulating fluidized bed boiler according to claim 7, characterized in that, The counterweight torque sleeve has an internal groove that matches the shape of the support sleeve, and the outer end plate of the counterweight torque sleeve has a positioning hole; the counterweight frame is a slotted frame structure, and the outer ends of its two side plates are provided with positioning blocks that can be inserted into the positioning holes to achieve precise positioning and fixation of the counterweight frame and the counterweight torque sleeve; the web plate of the slotted frame has a row of fastening holes along its length to facilitate adjustment of the number of counterweight blocks installed on the counterweight frame by fasteners.

9. A built-in flap valve for a circulating fluidized bed boiler according to claim 8, characterized in that, The valve body and the flap plate are both installed inside the high-temperature flue gas duct of the circulating fluidized bed boiler, and the counterweight assembly is installed on the outside of the high-temperature flue gas duct. Symmetrical perforations are provided on both sides of the high-temperature flue gas duct, and the support shaft tube in the valve shaft assembly extends through the perforations to the outside of the duct. A shaft seal is installed at the perforation.

10. An SCR denitrification system, comprising a reducing agent supply unit, an ammonia injection mixing unit, and an SCR reactor, wherein the reducing agent supply unit consists of a liquid ammonia storage tank, an evaporator, and a buffer tank, the buffer tank being connected to the ammonia injection mixing unit, and the ammonia injection mixing unit and the SCR reactor being disposed in a low-temperature flue gas duct containing an economizer, characterized in that, The evaporator adopts the built-in flap valve of the circulating fluidized bed boiler as described in any one of claims 1-9, and utilizes the heat of high-temperature flue gas or fly ash absorbed by the flap plate to achieve efficient evaporation and gasification of ammonia water.

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