SCR (Selective Catalytic Reduction) denitration ammonia spraying device for controlling ammonia escape
By employing a double-layer sleeve structure and a spray gun mechanism with a gradient porosity gasification heat absorption core in the SCR denitrification ammonia injection unit, the problems of ammonia escape and catalyst poisoning at low temperatures were solved, achieving efficient ammonia gasification and mixing under low temperature and variable load conditions, thus ensuring ammonia escape rate and denitrification efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-27
- Publication Date
- 2026-03-31
AI Technical Summary
Existing SCR denitrification ammonia injection units suffer from excessive ammonia slip and catalyst poisoning under low temperature and variable load conditions. In particular, at flue gas temperatures of 200-300℃, droplets are difficult to vaporize, leading to the formation of ammonium bisulfate, which clogs the catalyst and lacks self-adaptive capability.
The spray gun mechanism adopts a double-layer sleeve structure, with a heat tracing chamber formed between the inner and outer tubes. The inner tube is equipped with a vaporization heat absorption core and a valve core structure. The liquid ammonia water is heated by the heat tracing chamber to vaporize it, and the vaporization heat absorption core with gradient porosity and the adaptive valve core are used to control the spray to ensure that the gaseous ammonia water is sprayed out. Combined with the Venturi rectifier, the mixing efficiency is improved.
The problem of ammonia slip and catalyst poisoning was completely solved at low temperatures, ensuring that the ammonia slip rate was controlled below 3 ppm, adapting to load changes, and improving denitrification efficiency and mechanical life of the unit.
Smart Images
Figure CN121755043A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of environmental protection equipment technology, specifically to an SCR denitrification ammonia injection device for controlling ammonia escape. Background Technology
[0002] Currently, SCR (Selective Catalytic Reduction) denitrification technology is widely used in flue gas treatment of industrial furnaces such as annealing furnaces for high-quality steel products. Taking an annealing furnace in a steel plant as an example, its flue gas emissions have the following significant characteristics: after waste heat recovery or leakage control, the temperature of the flue gas entering the SCR reactor is usually maintained at 200-300℃. Within this low-temperature range, if 20% ammonia water is used as the reducing agent, it is extremely difficult for directly injected droplets to achieve complete heat absorption and vaporization over a short distance. At the same time, the operation of the periodic annealing furnace is intermittent, and the flue gas volume and flow field fluctuate drastically with the opening and closing of the furnace door and the adjustment of the variable frequency induced draft fan. Under low-temperature and variable-load conditions, it is still necessary to ensure a denitrification efficiency of ≥80% and an ammonia slip rate controlled below 3ppm.
[0003] However, existing dual-fluid spray guns or conventional grid spray systems have significant shortcomings when dealing with the above-mentioned operating conditions: First, incomplete low-temperature vaporization. At flue gas temperatures of 200-300℃, ammonia droplets sprayed from ordinary nozzles often do not have enough time to vaporize before contacting the flue wall or catalyst. Unvaporized droplets not only cause excessive ammonia escape but also readily react with sulfur oxides in the flue gas to form ammonium bisulfate (ABS), leading to micropore blockage and poisoning of the low-temperature catalyst, shortening the catalyst's chemical and mechanical lifespan. Second, a lack of adaptability to varying loads. When the cyclic furnace is operating at low load, the ammonia injection rate decreases accordingly. Fixed-opening nozzles result in reduced injection pressure, deteriorated atomization, and the appearance of "flowing" phenomena; while at high loads, penetrating escape is prone to occur. Summary of the Invention
[0004] To address the aforementioned issues, an SCR denitrification ammonia injection device is provided for controlling ammonia escape. By configuring a heat tracing chamber and a vaporization heat absorption core, a forced heat exchange environment is created. This ensures that the injected fluid is always in a high-pressure gaseous state, completely resolving the ammonia escape and catalyst poisoning problems caused by direct droplet injection under low-temperature conditions.
[0005] To address the problems of existing technologies, this invention provides an SCR denitrification ammonia injection device for controlling ammonia escape, comprising a spray gun mechanism disposed inside a flue, the spray gun mechanism including an inner tube extending axially and an outer tube sleeved around the outer periphery of the inner tube; the internal space of the inner tube is divided along the fluid flow direction into a filling cavity disposed upstream and an installation cavity disposed downstream; a heat tracing cavity is formed between the outer tube and the inner tube, covering the filling cavity and the installation cavity area, for the flow of a high-temperature heating medium; a vaporization heat absorption core is disposed inside the filling cavity, and the outer periphery of the vaporization heat absorption core is... The circumferential surface is tightly fitted to the inner wall of the inner tube; the vaporization heat absorption core is a porous medium structure used to convert liquid ammonia into a gaseous working fluid; a constricted injection port is provided at the connection between the mounting cavity and the filling cavity; a valve core that can slide along the axial direction of the inner tube and an elastic element for applying a restoring force to the valve core are provided in the mounting cavity; the valve core is configured to overcome the restoring force of the elastic element and slide away from the filling cavity along the axial direction under the fluid pressure in the mounting cavity, thereby forming a connected injection channel between the outer surface of the valve core and the injection port.
[0006] Preferably, the vaporization heat absorption core is a gradient porosity sintered metal structure; the porosity of the vaporization heat absorption core is gradient distributed in the radial section, wherein the porosity in the region near the central axis of the inner tube is greater than the porosity in the region near the inner wall of the inner tube; the small pore layer located in the inner wall region forms a high capillary liquid absorption layer, which is configured to laterally draw the liquid ammonia flowing in the central region to the heated wall surface of the inner tube.
[0007] Preferably, a guide frame extending axially is fixedly disposed inside the mounting cavity; a guide rod is disposed on the valve core, and the guide rod is slidably engaged with the guide frame; the elastic element is sleeved on the guide rod, and both ends of the elastic element are respectively connected to the valve core and the guide frame.
[0008] Preferably, the valve core has a conical sealing surface at one end near the injection port, and a plurality of spiral guide grooves are formed on the conical sealing surface; the spiral guide grooves are configured such that when the valve core slides outward to open the injection channel, the gaseous working fluid flowing through the gap between the outer surface of the valve core and the injection port is forced to rotate, thereby forming a rotating umbrella-shaped air curtain.
[0009] Preferably, the guide frame includes a streamlined rectifier housing fixed in the mounting cavity; an annular side plate is provided on the valve core near the guide frame, and the annular side plate is sleeved on the outer periphery of the streamlined rectifier housing and forms a sliding fit with it.
[0010] Preferably, the heat tracing cavity is provided with a spiral guide rib; the spiral guide rib is wound around and fixed on the inner wall of the outer tube, forcing the high-temperature heating medium to flow along the spiral path in the heat tracing cavity, so as to increase the residence heat exchange time of the heating medium in the periphery of the filling cavity and the mounting cavity.
[0011] Preferably, the inner diameter of the mounting cavity is greater than or equal to the inner diameter of the filling cavity, and the mounting cavity has a tapered transition section that tapers near the injection port; the mounting cavity forms a pressure-stabilizing buffer space for the gaseous working fluid, which is used to eliminate pressure pulsations generated during the vaporization process and ensure that the fluid driving force acting on the valve core is stable.
[0012] Preferably, a Venturi shroud is provided at one end of the spray gun mechanism near the mounting cavity; the neck sidewall of the Venturi shroud is provided with an inclined air intake hole, the axis of the inclined air intake hole forms an acute angle with the fluid spray direction, which is used to use the negative pressure of the spray to draw in external smoke into the shroud and mix with the gaseous working fluid.
[0013] Preferably, the inclined intake port has a smooth-transition rounded corner at the inlet edge of the outer wall of the Venturi shroud to reduce the flow resistance when external flue gas is drawn in and to prevent fly ash accumulation.
[0014] Preferably, a distributor is provided at one end of the spray gun mechanism near the filling cavity; the distributor is configured to uniformly disperse the liquid ammonia water entering the inner tube into the cross-section of the vaporization heat absorption core; the outer tube is respectively provided with a heating medium inlet and a heating medium outlet that connect to the heat tracing cavity.
[0015] The advantages of this invention compared to the prior art are:
[0016] 1. This invention constructs a forced heat exchange environment by setting up a heat tracing chamber covering both the filling cavity and the installation cavity, in conjunction with a porous vaporization heat-absorbing core within the filling cavity. After liquid ammonia enters the spray gun, it must first undergo a phase change within the vaporization heat-absorbing core, transforming into a gaseous working fluid before entering the downstream installation cavity. Simultaneously, an adaptive mechanical structure composed of a valve core and an elastic element is used to set a gas phase opening threshold. Only when the pressure of the vaporized working fluid reaches a level sufficient to overcome the restoring force of the elastic element will the valve core slide outward to open the injection channel; if the pressure is insufficient, the valve core automatically closes the injection port under the action of the restoring force. This ensures that the ejected fluid is always a high-pressure gaseous state, completely solving the problems of ammonia escape and catalyst poisoning caused by direct droplet injection under low-temperature conditions.
[0017] 2. The vaporization endothermic core of this invention adopts a gradient pore structure, with high porosity in the central region and low porosity in the inner wall region. Utilizing the powerful capillary force generated by the micropores, the low-temperature liquid ammonia in the central flow channel is actively and forcefully drawn laterally to the high-temperature wall surface of the inner tube. Furthermore, the metal skeleton physically punctures any vapor film that may form on the liquid surface, forcing the liquid to maintain a wetted contact with the hot wall surface. This not only eliminates the liquid core phenomenon in the central fluid but also significantly improves vaporization efficiency, enabling the device to adapt to larger flow rate load changes. Attached Figure Description
[0018] Figure 1A three-dimensional structural diagram of an SCR denitrification ammonia injection device for controlling ammonia escape. Figure 1 .
[0019] Figure 2 A three-dimensional structural diagram of an SCR denitrification ammonia injection device for controlling ammonia escape. Figure 2 .
[0020] Figure 3 This is a schematic diagram of the cross-sectional structure of an SCR denitrification ammonia injection device when the injection port is open, used to control ammonia escape.
[0021] Figure 4 A schematic diagram of the three-dimensional cross-sectional structure of an SCR denitrification ammonia injection device when the injection port is open, used to control ammonia escape. Figure 1 .
[0022] Figure 5 A schematic diagram of the three-dimensional cross-sectional structure of an SCR denitrification ammonia injection device when the injection port is open, used to control ammonia escape. Figure 2 .
[0023] Figure 6 This is a three-dimensional structural diagram of a valve core in an SCR denitrification ammonia injection device used to control ammonia escape.
[0024] Figure 7 A schematic diagram of a three-dimensional cross-sectional structure of an SCR denitrification ammonia injection device with the injection port closed, used to control ammonia escape. Figure 1 .
[0025] Figure 8 yes Figure 7 Enlarged view of point A in the middle.
[0026] Figure 9 This is an exploded view of the spray gun mechanism and Venturi shroud in an SCR denitrification ammonia spraying device used to control ammonia escape.
[0027] Figure 10 This is a three-dimensional structural diagram of the Chinese-made Churi rectifier shroud of an SCR denitrification ammonia injection device used to control ammonia escape.
[0028] The following are the labels in the diagram: 1. Spray gun mechanism; 11. Inner tube; 111. Outer tube; 112. Filling cavity; 1121. Vaporization heat absorption core; 113. Mounting cavity; 1131. Injection port; 1132. Valve core; 11321. Elastic element; 11322. Guide rod; 11323. Conical sealing surface; 11324. Spiral guide groove; 11325. Annular side plate; 1133. Guide frame; 11331. Rectifier shell; 114. Heat tracing cavity; 1141. Spiral guide rib; 115. Flow divider; 12. Venturi rectifier; 121. Intake port. Detailed Implementation
[0029] To further understand the features, technical means, and specific objectives and functions achieved by the present invention, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.
[0030] like Figures 1 to 8 As shown: An SCR denitrification ammonia injection device for controlling ammonia escape includes a spray gun mechanism 1 disposed inside a flue. The spray gun mechanism 1 includes an inner tube 11 extending axially and an outer tube 111 sleeved around the outer periphery of the inner tube 11. The internal space of the inner tube 11 is divided along the fluid flow direction into a filling cavity 112 disposed upstream and an installation cavity 113 disposed downstream. A heat tracing cavity 114 is formed between the outer tube 111 and the inner tube 11, covering the areas of the filling cavity 112 and the installation cavity 113, for the flow of a high-temperature heating medium. A vaporization heat absorption core 1121 is disposed in the filling cavity 112, and the outer peripheral surface of the vaporization heat absorption core 1121 is in close contact with the inner wall of the inner tube 11. The vaporization heat-absorbing core 1121 has a porous medium structure and is used to convert liquid ammonia into a gaseous working fluid. A constricted injection port 1131 is provided at the connection between the mounting cavity 113 and the filling cavity 112. A valve core 1132 that can slide along the axial direction of the inner tube 11 and an elastic element 11321 for applying a restoring force to the valve core 1132 are provided in the mounting cavity 113. The valve core 1132 is configured to overcome the restoring force of the elastic element 11321 and slide away from the filling cavity 112 along the axial direction under the fluid pressure in the mounting cavity 113, thereby forming a connected injection channel between the outer surface of the valve core 1132 and the injection port 1131.
[0031] In existing SCR denitrification systems, the spray guns typically function merely as simple liquid delivery pipes, lacking precise control over the physical state of the ammonia solution. Especially at lower flue gas temperatures, such as 200-300°C, directly sprayed droplets struggle to vaporize instantly, easily forming liquid films on the flue's inner wall or catalyst surface, leading to severe ammonia escape and crystallization blockage. To address these issues, the core component of this embodiment is a spray gun mechanism 1 housed within the flue. Structurally, the spray gun mechanism 1 employs a double-layered casing configuration, including an axially extending inner tube 11 and an outer tube 111 sleeved around the inner tube 11. A heat tracing chamber 114 is formed between the outer tube 111 and the inner tube 11. This heat tracing chamber 114 is crucial, as it facilitates the flow of high-temperature heating media, such as hot air or steam, thereby creating a constant-temperature shield enveloping the entire spray gun mechanism 1, ensuring the internal working fluid remains in a suitable heat-absorbing environment. The internal space of the inner tube 11 is functionally divided into two independent regions along the fluid flow direction: a filling cavity 112 located upstream and an installation cavity 113 located downstream. The working logic of this invention follows the principle of vaporization followed by injection.
[0032] Liquid ammonia is first uniformly injected into the filling cavity 112. Within the filling cavity 112, the liquid ammonia does not flow directly but is forced into the vaporization heat absorber core 1121, which is tightly fitted to the inner wall of the inner tube 11. This vaporization heat absorber core 1121 employs a porous media structure, serving as a temporary carrier and heat exchange medium for the liquid ammonia. Heat from the heat tracing cavity 114 is transferred through the wall of the inner tube 11 to the metal skeleton of the vaporization heat absorber core 1121. The liquid ammonia is heated and undergoes a phase change within the porous medium, rapidly expanding in volume and transforming into a gaseous working fluid. Subsequently, the generated high-pressure gaseous working fluid flows from the filling cavity 112 into the downstream mounting cavity 113. A constricted injection port 1131 is provided at the connection between the mounting cavity 113 and the filling cavity 112, serving as the only barrier for the gaseous working fluid to reach the outside. At this time, the air pressure accumulated in the mounting cavity 113 acts on the valve core 1132, which can slide along the axis of the inner tube 11. When the air pressure overcomes the restoring force of the elastic element 11321, the valve core 1132 moves to open the channel, and the gaseous working fluid is ejected.
[0033] The ammonia injection device in this embodiment can directly replace the existing dual-fluid spray gun and be applied to the SCR denitrification system of the annealing furnace. During actual operation, the heat tracing chamber 114 interface of the outer pipe 111 can be connected to a high-temperature hot air or steam pipeline in the plant area as a heat source. Liquid ammonia water can be precisely delivered to the inner pipe 11 via a metering pump. When the PLC control system increases the ammonia injection rate based on the NOx concentration feedback from the online monitoring CEMS, the metering pump speed increases, the pressure of the ammonia water entering the filling chamber 112 increases, the vaporization rate accelerates, the air pressure in the mounting chamber 113 rises, driving the valve core 1132 to move outward and increase its opening, spraying out a gas curtain with a larger flow rate and higher swirling intensity. Conversely, when the system commands a reduction in the ammonia injection rate, the valve core 1132 automatically reduces its opening under the action of the elastic element 11321. This precise liquid supply from the metering pump combined with the adaptive adjustment of the spray gun solves the problems of denitrification lag and ammonia escape caused by large fluctuations in the flue gas volume of the cycle furnace, ensuring that the ammonia escape rate is always controlled below 3ppm within the low-temperature window of 200-300℃.
[0034] like Figures 3 to 8 As shown: The vaporization heat absorption core 1121 is a gradient porosity sintered metal structure (illustrated only in the figure); the porosity of the vaporization heat absorption core 1121 on the radial cross section is gradient distributed, wherein the porosity in the region near the central axis of the inner tube 11 is greater than the porosity in the region near the inner wall of the inner tube 11; the small pore layer located in the inner wall region forms a high capillary liquid absorption layer, which is configured to laterally draw the liquid ammonia flowing in the central region to the heated wall surface of the inner tube 11.
[0035] Ordinary homogeneous porous media often face a dilemma when dealing with large-flow-rate liquids at the center: if the pores are too small, the axial flow resistance is too high, preventing the liquid from entering; if the pores are too large, the capillary suction is too weak, preventing the liquid from adhering to the walls. To address this, the vaporization endothermic core 1121 in this embodiment employs a gradient-pore sintered metal structure, constructing a composite fluid management mechanism that combines axial transport with radial suction. Specifically, the porosity of the vaporization endothermic core 1121 exhibits a gradient distribution in its radial cross-section, with higher porosity near the central axis of the inner tube 11. This is equivalent to establishing a high-speed channel in the core region, allowing liquid ammonia to flow rapidly axially with extremely low flow resistance, preventing fluid accumulation or blockage at the inlet. Conversely, the porosity near the inner wall of the inner tube 11 is lower. This utilizes the strong capillary force generated by the micropores to form a continuously operating suction pump. Regardless of fluctuations in the flow rate of liquid ammonia in the central region, the microporous layer at the edge utilizes the significant capillary potential energy difference to actively and powerfully draw, tear apart, and distribute the large droplets from the center radially onto the heated wall surface of the inner tube 11. This eliminates the liquid core phenomenon: forcing the liquid to leave the low-temperature central region and contact the high-temperature edge region, avoiding the heat exchange dead zone of cold water flowing in the center and dry burning of the tube wall. At high temperatures, droplets are usually suspended by the vapor layer they generate, a phenomenon known as the Leidenfrost phenomenon, leading to deterioration in heat exchange. In this design, the porous medium's metal framework acts like countless hands, physically pressing down on the droplets, piercing the vapor film, and forcing the droplets to maintain contact with the high-temperature wall surface. Through this mechanism, it is ensured that every drop of ammonia completes the entire process of adsorption, distribution, and phase change the instant it flows through the filling cavity 112.
[0036] like Figures 3 to 8 As shown: A guide frame 1133 extending axially is fixedly installed inside the mounting cavity 113; a guide rod 11322 is provided on the valve core 1132, and the guide rod 11322 is slidably engaged with the guide frame 1133; the elastic element 11321 is sleeved on the guide rod 11322, and both ends of the elastic element 11321 are respectively connected to the valve core 1132 and the guide frame 1133.
[0037] To prevent the valve core 1132 from deflecting or jamming under the impact of high-speed airflow and to ensure the uniformity of the injection channel opening, a guide frame 1133 extending axially is fixedly installed inside the mounting cavity 113. Correspondingly, a guide rod 11322 is provided on the valve core 1132, forming a precise sliding fit with the guide frame 1133. An elastic element 11321 is sleeved on the guide rod 11322, and both ends of the elastic element 11321 are connected to the valve core 1132 and the guide frame 1133, respectively. This central guide rail configuration ensures that the valve core 1132 can still perform pure linear reciprocating motion along the axis under high temperature and high frequency vibration conditions, improving the mechanical life and operational accuracy of the mechanism.
[0038] like Figures 3 to 8 As shown: The valve core 1132 has a conical sealing surface 11323 at one end near the injection port 1131. The conical sealing surface 11323 has several spiral guide grooves 11324. The spiral guide grooves 11324 are configured such that when the valve core 1132 slides outward to open the injection channel, it forces the gaseous working fluid flowing through the gap between the outer surface of the valve core 1132 and the injection port 1131 to generate a rotational motion, thereby forming a rotating umbrella-shaped air curtain.
[0039] To overcome the shortcomings of traditional direct-jet airflow, which has strong penetration but small diffusion area, the valve core 1132 has a conical sealing surface 11323 near the injection port 1131, and several spiral guide grooves 11324 are finely formed on this conical sealing surface 11323. When the valve core 1132 is pressed and slides outward to open the injection channel, the high-pressure gaseous working fluid is forced to flow through these spiral guide grooves 11324. The guiding effect of the grooves forces the airflow to generate a violent rotational motion, so that when it leaves the injection port 1131, it expands rapidly due to centrifugal force, forming a rotating umbrella-shaped air curtain. This swirling structure greatly increases the contact surface area between ammonia and flue gas, and shortens the mixing distance.
[0040] like Figures 3 to 8 As shown: the guide frame 1133 includes a streamlined rectifier housing 11331 fixed in the mounting cavity 113; an annular side plate 11325 is provided on the side of the valve core 1132 near the guide frame 1133, and the annular side plate 11325 is sleeved on the outer periphery of the streamlined rectifier housing 11331 and forms a sliding fit with it.
[0041] When fluid flows through fixed components such as the guide frame 1133, wake vortices are easily generated behind the components, leading to local pressure loss and flow field turbulence. Therefore, this embodiment optimizes the aerodynamic fit between the guide frame 1133 and the valve core 1132. The guide frame 1133 includes a streamlined rectifying housing 11331 fixed within the mounting cavity 113, for example, in a streamlined teardrop shape. Simultaneously, the valve core 1132 is connected to an annular side plate 11325 extending towards the guide frame 1133. This annular side plate 11325 is fitted around the outer periphery of the streamlined rectifying housing 11331 and forms a sliding fit with it. Regardless of whether the valve core 1132 is closed or open, the outer contour of the valve core 1132 and the outer contour of the streamlined rectifying housing 11331 can always be joined together axially to form a continuously transitioning teardrop or spindle-shaped structure. This biomimetic streamlined shape can guide the airflow to smoothly pass over the guide frame 1133 and the valve core 1132, effectively eliminating the wake vortex that may be generated when the gaseous working fluid flows through the connection between the guide frame 1133 and the valve core 1132, reducing flow resistance and ensuring jet kinetic energy.
[0042] like Figures 3 to 8 As shown: a spiral guide rib 1141 is provided in the heat tracing cavity 114; the spiral guide rib 1141 is wound and fixed on the inner wall of the outer tube 111, forcing the high-temperature heating medium to flow along the spiral path in the heat tracing cavity 114, so as to increase the residence heat exchange time of the heating medium in the periphery of the filling cavity 112 and the mounting cavity 113.
[0043] To prevent the high-temperature heating medium from short-circuiting out of the heat tracing cavity 114 and causing insufficient heat exchange, a spiral guide rib 1141 is provided inside the heat tracing cavity 114. The spiral guide rib 1141 is wound around and fixed to the inner wall of the outer tube 111 or between the outer wall of the inner tube 111 and the inner wall of the outer tube 111. This structure forces the high-temperature heating medium entering the heat tracing cavity 114 to flow along a spiral path instead of directly to the outlet. This significantly increases the flow path length and residence heat exchange time of the heating medium around the filling cavity 112 and the mounting cavity 113, thereby greatly improving the heat transfer efficiency to the inner tube 11 without increasing the flow rate of the heating medium, ensuring that the vaporized heat absorption core 1121 obtains sufficient enthalpy.
[0044] like Figures 3 to 8 As shown: the inner diameter of the mounting cavity 113 is greater than or equal to the inner diameter of the filling cavity 112, and the mounting cavity 113 has a tapered transition section near the injection port 1131; the mounting cavity 113 forms a pressure-stabilizing buffer space for the gaseous working fluid, which is used to eliminate pressure pulsation generated during the vaporization process and ensure that the fluid driving force acting on the valve core 1132 is stable.
[0045] The vaporization process of liquid ammonia is often accompanied by dramatic volume expansion and pressure pulsations. To output a stable jet flow, the inner diameter of the mounting cavity 113 is set to be greater than or equal to the inner diameter of the filling cavity 112, and the mounting cavity 113 has a tapered transition section near the injection port 1131. Thus, the mounting cavity 113 effectively forms a pressure-stabilizing buffer space for the gaseous working fluid. This larger volume can accommodate and attenuate the pressure waves generated during vaporization, acting as an accumulator to eliminate pressure pulsations during vaporization, ensuring a smooth fluid driving force acting on the valve core 1132, and preventing high-frequency chattering of the valve core 1132.
[0046] like Figures 1 to 5 , Figure 9 and Figure 10 As shown: A Venturi shroud 12 is provided at one end of the spray gun mechanism 1 near the mounting cavity 113; an inclined suction hole 121 is provided on the neck side wall of the Venturi shroud 12, and the axis of the inclined suction hole 121 forms an acute angle with the direction of fluid injection, which is used to use the negative pressure of injection to draw external smoke into the shroud and mix it with the gaseous working fluid.
[0047] To further improve the mixing efficiency of ammonia and external flue gas, a Venturi shroud 12 is provided at one end of the spray gun mechanism 1 near the mounting cavity 113. This Venturi shroud 12 has a structure characterized by openings at both ends and a narrowing in the middle. Crucially, the neck sidewall of the Venturi shroud 12 has an inclined suction port 121, with the axis of the inclined suction port 121 forming an acute angle with the fluid injection direction. During operation, the high-speed rotating air curtain ejected from the valve core 1132 enters the Venturi shroud 12. According to Bernoulli's principle, the high-speed fluid forms a strong negative pressure zone inside the shroud. Utilizing this injection negative pressure, and through the guiding effect of the inclined suction port 121, external flue gas can be efficiently drawn into the shroud. The drawn-in flue gas and high-speed ammonia undergo intense impact, shearing, and premixing inside the shroud, thus achieving preliminary homogenization before exiting the shroud, greatly improving the denitrification reaction efficiency.
[0048] like Figures 1 to 5 , Figure 9 and Figure 10 As shown: The inclined air intake 121 has a smooth-transition rounded corner at the inlet edge of the outer wall of the Venturi shroud 12 to reduce the flow resistance when external flue gas is drawn in and to prevent fly ash accumulation.
[0049] Furthermore, the inclined intake port 121 has a smoothly transitioning rounded corner at the inlet edge of the Venturi shroud 12. This not only reduces the flow resistance when external flue gas is drawn in, but more importantly, it eliminates dead angles at the port, effectively preventing fly ash in the flue gas from accumulating and clogging at the intake port 121, thus ensuring long-term maintenance-free operation of the device.
[0050] like Figures 1 to 3 As shown: A distributor 115 is provided at one end of the spray gun mechanism 1 near the filling cavity 112; the distributor 115 is configured to uniformly disperse the liquid ammonia water entering the inner tube 11 into the cross section of the vaporization heat absorption core 1121; the outer tube 111 is provided with a heating medium inlet and a heating medium outlet that connect to the heat tracing cavity 114.
[0051] To prevent the liquid ammonia from flowing out of the inner tube 11 and causing localized overcooling of the vaporization core, a flow divider 115 is provided at one end of the spray gun mechanism 1 near the filling chamber 112. The flow divider 115 is configured to evenly distribute the liquid ammonia entering the inner tube 11 onto the cross-section of the vaporization heat-absorbing core 1121, ensuring maximum utilization of the vaporization core. Simultaneously, the outer tube 111 is provided with a heating medium inlet and a heating medium outlet connecting to the heat tracing chamber 114 to maintain heat tracing circulation.
[0052] The above embodiments only illustrate one or more implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the appended claims.
Claims
1. An SCR denitrification ammonia injection device for controlling ammonia escape, comprising a spray gun mechanism disposed inside a flue, characterized in that, The spray gun mechanism includes an inner tube extending axially and an outer tube sleeved around the outer periphery of the inner tube. The internal space of the inner tube is divided into a filling cavity located upstream and an installation cavity located downstream along the fluid flow direction. A heat tracing cavity is formed between the outer tube and the inner tube, covering the filling cavity and the mounting cavity area, for the flow of high-temperature heating medium; A vaporization heat absorption core is provided inside the filling cavity, and the outer peripheral surface of the vaporization heat absorption core is in close contact with the inner wall of the inner tube. The vaporization heat absorption core has a porous medium structure and is used to convert liquid ammonia water into a gaseous working fluid. The connection between the mounting cavity and the filling cavity is provided with a constricted injection port. The mounting cavity is provided with a valve core that can slide along the axis of the inner tube and an elastic element for applying a reset force to the valve core. The valve core is configured to slide away from the filling cavity along the axial direction under the fluid pressure in the mounting cavity, overcoming the restoring force of the elastic element, thereby forming a communicating injection channel between the outer surface of the valve core and the injection port.
2. The SCR denitrification ammonia injection device for controlling ammonia slip according to claim 1, characterized in that, The vaporization heat absorption core is a gradient porosity sintered metal structure; the porosity of the vaporization heat absorption core is gradient distributed in the radial section, wherein the porosity in the region near the central axis of the inner tube is greater than that in the region near the inner wall of the inner tube; the small pore layer located in the inner wall region forms a high capillary liquid absorption layer, which is configured to laterally draw the liquid ammonia flowing in the central region to the heated wall surface of the inner tube.
3. The SCR denitrification ammonia injection device for controlling ammonia slip according to claim 1, characterized in that, A guide frame extending axially is fixedly installed inside the mounting cavity; a guide rod is provided on the valve core, and the guide rod slides in cooperation with the guide frame; the elastic element is sleeved on the guide rod, and both ends of the elastic element are connected to the valve core and the guide frame respectively.
4. An SCR denitrification ammonia injection device for controlling ammonia slip according to claim 3, characterized in that, The valve core has a conical sealing surface at one end near the injection port, and several spiral guide grooves are formed on the conical sealing surface. The spiral guide grooves are configured such that when the valve core slides outward to open the injection channel, the gaseous working medium flowing through the gap between the outer surface of the valve core and the injection port is forced to rotate, thereby forming a rotating umbrella-shaped air curtain.
5. An SCR denitrification ammonia injection device for controlling ammonia slip according to claim 3, characterized in that, The guide frame includes a streamlined rectifier housing fixed in the mounting cavity; an annular side plate is provided on the valve core near the guide frame, and the annular side plate is sleeved on the outer periphery of the streamlined rectifier housing and forms a sliding fit with it.
6. An SCR denitrification ammonia injection device for controlling ammonia slip according to claim 1, characterized in that, The heat tracing cavity is provided with a spiral guide rib; the spiral guide rib is wound around and fixed on the inner wall of the outer tube, forcing the high-temperature heating medium to flow along the spiral path in the heat tracing cavity, so as to increase the residence heat exchange time of the heating medium in the filling cavity and the periphery of the mounting cavity.
7. An SCR denitrification ammonia injection device for controlling ammonia slip according to claim 1, characterized in that, The inner diameter of the mounting cavity is greater than or equal to the inner diameter of the filling cavity, and the mounting cavity has a tapered transition section that tapers near the injection port; the mounting cavity forms a pressure-stabilizing buffer space for the gaseous working fluid, which is used to eliminate pressure pulsations generated during the vaporization process and ensure that the fluid driving force acting on the valve core is stable.
8. An SCR denitrification ammonia injection device for controlling ammonia slip according to claim 1, characterized in that, A Venturi shroud is provided at one end of the spray gun mechanism near the mounting cavity; the neck side wall of the Venturi shroud is provided with an inclined air intake hole, the axis of which forms an acute angle with the direction of fluid injection, for using the negative pressure of the injection to draw in external smoke into the shroud and mix with the gaseous working fluid.
9. An SCR denitrification ammonia injection device for controlling ammonia slip according to claim 8, characterized in that, The inclined intake port has a smooth-transition rounded corner at the inlet edge of the outer wall of the Venturi shroud to reduce the flow resistance when external flue gas is drawn in and to prevent fly ash accumulation.
10. An SCR denitrification ammonia injection device for controlling ammonia slip according to claim 1, characterized in that, A distributor is provided at one end of the spray gun mechanism near the filling cavity; the distributor is configured to uniformly disperse the liquid ammonia water entering the inner tube into the cross-section of the vaporization heat absorption core; the outer tube is provided with a heating medium inlet and a heating medium outlet that are connected to the heat tracing cavity.