SNCR (selective non-catalytic reduction) device and method

Abstract

The invention provides an SNCR device and method, and belongs to the technical field of waste gas treatment.The SNCR device comprises an ammonia gas detector, a nitrogen oxide concentration analyzer and an ammonia water vaporizer, the ammonia water vaporizer comprises a straight pipe section, a top inlet is formed in the top of the straight pipe section, the top inlet is connected with an ammonia water liquid inlet device, and a middle inlet is formed in the middle of the straight pipe section; the middle inlet is connected with a steam inlet device, the bottom of the straight pipe section is provided with a necking section, the bottom of the necking section is provided with a throat part, the bottom of the throat part is provided with a flaring section, the bottom of the flaring section is provided with a bottom outlet, and the bottom outlet is connected with a steam outlet device; according to the invention, the concentration of nitrogen oxide and the concentration of ammonia escape can be adjusted in real time, steam and ammonia water are fully atomized and gasified, and then are rotationally sprayed into flue gas, so that the denitration efficiency is greatly improved, the denitration ammonia consumption and the ammonia escape are reduced, and the denitration reaction temperature interval can be reduced to 750-1100 DEG C.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and in particular to a SNCR device and method. Background Art

[0002] SNCR (Selective Non-Catalytic Reduction) denitrification technology, that is, selective non-catalytic reduction technology, is a mature commercial NOx emission control and treatment technology. The basic principle is to spray an amino-containing reducing agent (such as ammonia water, urea solution, etc.) into the furnace temperature area of ​​850~1050 ℃. The reducing agent is rapidly thermally decomposed into NH3, and under specific temperature and oxygen conditions, it selectively reacts with NOx in the flue gas to produce harmless gases such as N2, CO2 and H2O.

[0003] The current SNCR denitrification technology has the following common problems: (1) Narrow denitrification reaction temperature range: The denitrification reaction temperature in the existing technology is 850~1050 ℃, and the reaction temperature window is narrow. It is difficult to denitrify efficiently under low-load conditions of the boiler. In the scenario where the furnace temperature of the biomass / waste incineration boiler is low, the SNCR denitrification efficiency is low; (2) Low denitrification efficiency: Generally 30%~50%, it is impossible to achieve ultra-low emissions of nitrogen oxides; (3) Large consumption of denitrification reductant: The ammonia nitrogen molar ratio (NSR) is ≥1.5, and ammonia escape is large, which not only pollutes the atmosphere, but also causes blockage of the air preheater due to the formation of (NH4)2SO4 when burning sulfur-containing fuels; (4) Commonly used SNCR technology sprays ammonia water or urea solution into the flue gas. The solution evaporates and absorbs heat, which will cause local cooling, resulting in a shortened reaction time between ammonia and nitrogen oxides, resulting in reduced denitrification efficiency. Summary of the invention

[0004] The object of the present invention is to provide a SNCR device and method to overcome the problems existing in the prior art. Firstly, the steam flow rate can be adjusted according to a fixed ratio according to the ammonia flow rate, and the ammonia flow rate can be adjusted according to the tail nitrogen oxide concentration and the ammonia escape concentration, so that the nitrogen oxide concentration and the ammonia escape concentration are stabilized below the set concentration; secondly, the ammonia water is first fully atomized and gasified by the ammonia water vaporizer, and converted into a gas phase mixture of ammonia gas and water vapor, thereby realizing efficient, rapid and sufficient heat exchange between steam and ammonia water; then, the gas flow can be rotated and injected by engraving rifling in the main gas pipe of the gas spray gun, which greatly improves the problems of poor penetration and poor mixing effect of the gas flow beam of the traditional single-phase spray gun, and further improves the denitration efficiency of the SNCR; in addition, the present invention expands the SNCR reaction temperature window, and can reduce the denitration reaction temperature range to 750-1100°C, thereby avoiding the heat absorption of the reducing agent in the flue gas, greatly improving the denitration efficiency, and reducing the denitration ammonia consumption and ammonia escape.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: An SNCR device comprises an upper tail flue, the upper tail flue is equipped with an ammonia detector, the upper tail flue is connected to the lower tail flue through an air preheater, the lower tail flue is equipped with a nitrogen oxide concentration analyzer; and also comprises an ammonia vaporizer, the ammonia vaporizer comprises a straight pipe section, a top inlet is installed at the top of the straight pipe section, the top inlet is connected to an ammonia liquid inlet device, a middle inlet is installed at the middle of the straight pipe section, the middle inlet is connected to a steam air inlet device, a constricted section is installed at the bottom of the straight pipe section, a throat is installed at the bottom of the constricted section, an expanding section is installed at the bottom of the throat, a bottom outlet is installed at the bottom of the expanding section, and the bottom outlet is connected to an air outlet device; The steam intake device comprises a pressure reducing device, the pressure reducing device is connected to a steam buffer tank through an intake pipe, the steam buffer tank is sequentially connected to a vortex flowmeter, a flow regulating valve and a steam manual valve through a plurality of steam outlet pipes, and the steam manual valve is connected to a middle inlet through a steam intake pipe; The ammonia liquid inlet device comprises an ammonia inlet pipeline, through which an ammonia flow meter, an ammonia flow regulating valve, an ammonia manual valve and a top inlet are sequentially connected; The gas outlet device comprises a gas outlet pipeline, the bottom outlet is connected to a distributor through the gas outlet pipeline, the side of the distributor is connected to a plurality of spray gun valves through a plurality of distribution ports, each spray gun valve is connected to a gas spray gun through a hose, and the bottom of the distributor is connected to a steam trap; Furthermore, the angle between the steam inlet pipe and the straight pipe section is 90°; Further, the pressure reducing device comprises a manual valve and a plurality of pressure reducing valves connected in sequence through an air intake pipe; Furthermore, a pressure-stabilizing exhaust valve is installed on the top of the steam buffer tank, and a drain valve is connected to the lower part of the steam buffer tank through a drain pipe; Further, the gas spray gun comprises a main gas pipe, an air inlet pipe is installed at one end of the main gas pipe, a handle is installed on the air inlet pipe, and an anti-wear nozzle is installed at the other end of the main gas pipe; a cooling sleeve is sleeved on the main gas pipe, an insulation layer is installed on the cooling sleeve, a compressed air pipe is also connected to the cooling sleeve, and a compressed air interface is opened at one end of the compressed air pipe; a plurality of riflings are arranged on the inner side of the main gas pipe, and the riflings are composed of negative lines and positive lines arranged alternately in a spiral shape; Further, the spray gun valve is connected to the gas spray gun via an air inlet pipe; Furthermore, the surface of the rifling is plated with chrome; the width of the negative line is greater than or equal to the width of the positive line; A SNCR denitrification method, based on the above-mentioned SNCR device, comprises the following steps: (1) Steam is introduced into the air inlet pipe, and the steam is introduced into the steam buffer tank through the pressure reducing device; (2) When the steam pressure in the steam buffer tank exceeds the upper limit of the working pressure, the steam continues to flow into the steam intake device and then into the ammonia vaporizer after the pressure is released to within the working pressure range; When the steam pressure in the steam buffer tank does not exceed the upper limit of the working pressure, the steam continues to be introduced into the steam intake device and then into the ammonia vaporizer; (3) Ammonia water is introduced into the ammonia inlet pipeline, and the steam flow rate and the ammonia water flow rate are controlled by a flow control valve. The ammonia water flows through the ammonia water flow control valve and the ammonia water manual valve and enters the ammonia water vaporizer. The ammonia water flow control valve adjusts the ammonia water injection amount according to the nitrogen oxide emission concentration and ammonia escape concentration detected by the nitrogen oxide concentration analyzer and the ammonia gas detector; (4) Atomizing and vaporizing steam and ammonia in the straight pipe section of the ammonia vaporizer to obtain a gas phase mixture, and the gas phase mixture is passed into the distributor through the gas outlet pipe; (5) The distributor distributes the mixed gas to each gas spray gun. The spray gun valve adjusts the opening according to the position of the gas spray gun and the distribution of flue gas flow. The gas spray gun sprays the gas phase mixture into the flue gas to achieve SNCR denitrification. Furthermore, the step of (1) via a pressure reducing device specifically includes: reducing the steam pressure to 0.05-0.5 MPa via a pressure reducing device; the upper limit of the working pressure in (2) is 0.5 MPa; the mass ratio of the ammonia flow rate to the steam flow rate in (3) is controlled to be 1:(2-20); the flue gas temperature in (5) is 750-1100°C; Furthermore, the ammonia flow regulating valve in (3) adjusts the ammonia injection amount according to the nitrogen oxide emission concentration and ammonia escape concentration detected by the nitrogen oxide concentration analyzer and the ammonia detector: When the nitrogen oxide emission concentration is greater than 50 mg / m 3 When the ammonia flow rate is increased to a nitrogen oxide emission concentration of less than 45 mg / m 3 ; When the ammonia escape concentration is >8 mg / m 3 When the ammonia flow rate is reduced to ammonia escape concentration of less than 8 mg / m 3 , while maintaining nitrogen oxide emission concentration <45 mg / m 3 .

[0006] The above technical solution has the following advantages or beneficial effects: The present invention provides an SNCR device. Firstly, the steam pressure is stabilized within a certain range through a pressure reducing device and a steam buffer tank, so that the steam pressure tends to be stable, which is convenient for adjusting the steam flow rate during the operation of the high-efficiency SNCR and improving the reliability of the denitration operation. Then, the steam flow rate can be measured in real time through a vortex flowmeter, and the steam flow rate and the ammonia flow rate entering the ammonia water vaporizer can be controlled by a flow regulating valve to be adjusted in proportion. At the same time, the ammonia water flow regulating valve is used to adjust the ammonia water injection amount according to the nitrogen oxide emission concentration and ammonia escape concentration detected by a nitrogen oxide concentration analyzer and an ammonia gas detector, so that the nitrogen oxide concentration and the ammonia escape concentration are stabilized below the set concentration, thereby reducing the ammonia consumption and ammonia escape of denitration. Secondly, the ammonia water is converted into water vapor and ammonia gas by steam through the ammonia water vaporizer. The gas phase mixture is specifically prepared by preliminarily mixing ammonia water and steam through the top inlet and the middle inlet, performing an ammonia water evaporation reaction in the straight pipe section, and fully mixing ammonia gas and steam in the expanded section. Then, the ammonia water is fully atomized by the shearing effect brought by the high flow rate of steam, and then, accompanied by intense heat exchange, the ammonia water is quickly vaporized, which greatly accelerates the vaporization rate of ammonia water and improves the denitrification efficiency. In addition, the gas phase mixture is sprayed into the flue gas through a gas spray gun, which not only reduces the evaporation heat absorption of ammonia water in the flue gas, prolongs the residence time of ammonia gas in the SNCR reaction temperature window, and improves the denitrification efficiency, but also increases the local water vapor content, catalyzes the SNCR denitrification reaction, and expands the SNCR reaction temperature window downward, so that the denitrification reaction temperature range is reduced to 750~1100 ℃, thereby improving the SNCR denitrification efficiency at lower temperatures.

[0007] Furthermore, the angle of 90° between the steam inlet pipe and the straight pipe section helps to form a better mixing effect between the steam and the ammonia water when entering the straight pipe section, and can cause turbulence when the steam flow hits the inner wall of the straight pipe section, thereby increasing the contact area between the steam and the ammonia water and promoting the vaporization process; by precisely controlling the flow ratio of steam and ammonia water, the accuracy and stability of the vaporization process can be ensured, thereby improving the vaporization quality.

[0008] Furthermore, the steam pressure can be stabilized by the pressure reducing valve, which facilitates the adjustment of steam flow during the operation of the efficient SNCR process and improves the reliability of denitrification operation; the manual valve can be manually closed to isolate the system when an unexpected situation such as power failure or short circuit occurs in the automatic control system, thereby improving safety.

[0009] Furthermore, when the steam pressure in the steam buffer tank increases to exceed the set pressure upper limit, the pressure-stabilizing exhaust valve will automatically open to reduce the steam pressure to within the set working pressure range, further ensuring the stability of the pressure during the operation of the device, improving the reliability of denitrification while also ensuring the safety of the device operation; by regularly opening the drain valve to discharge the condensed water accumulated in the steam buffer tank, the accumulation and blockage of condensed water in the outlet pipe can be effectively prevented.

[0010] Furthermore, the gas spray gun is designed with rifling, and the airflow is in a rotating state when it is sprayed out, which can more effectively penetrate the smoke layer and fully contact the nitrogen oxides in the smoke. The rotating airflow helps to promote the mixing of the reducing agent and the smoke, improve the reaction efficiency of the reducing agent and the nitrogen oxides, and thus improve the denitrification efficiency of the SNCR; compressed air is introduced into the cooling sleeve through the compressed air interface for cooling, ensuring that the temperature of the main air pipe is maintained below 700°C; the compressed air flows in the cooling sleeve, which can take away the heat generated by the high-temperature reaction of the gas inside the spray gun, effectively lowering the operating temperature of the spray gun, reducing the wear of the spray gun due to high temperature and other related effects, preventing damage or performance degradation due to overheating, and extending the service life of the spray gun; by setting an anti-wear nozzle, the spray gun can be protected to prevent the spray gun from wearing at high temperature, reducing the wear problem caused by long-term operation.

[0011] Furthermore, during the SNCR denitrification process, the rifling needs to withstand the scouring of high-speed airflow and the impact of particulate matter for a long time. Chrome plating can significantly improve the hardness of the rifling surface, thereby enhancing its ability to resist wear; by setting the width of the negative line to be greater than or equal to the width of the positive line, the airflow forms a non-uniform flow in the rifling, thereby enhancing the rotation effect of the airflow, which helps to improve the mixing efficiency and penetration of SNCR denitrification, allowing the reducing agent to more fully contact and react with the nitrogen oxides in the flue gas.

[0012] The present invention also provides an SNCR denitration method, which stabilizes the steam pressure within a certain range so that the steam pressure tends to be stable, facilitates the adjustment of the steam flow rate during the operation of the high-efficiency SNCR, and improves the reliability of the denitration operation; then, the ammonia flow regulating valve is used to control the ammonia escape concentration to be stabilized below the set concentration, thereby reducing the denitration ammonia consumption and ammonia escape; and then, through an ammonia gasifier and a gas spray gun, not only can the heat absorption of ammonia evaporation in the flue gas be reduced, the residence time of ammonia in the SNCR reaction temperature window be prolonged, and the denitration efficiency be greatly improved, but also the local water vapor content can be increased, catalyzing the SNCR denitration reaction, downwardly expanding the SNCR reaction temperature window, improving the SNCR denitration efficiency at a lower temperature, and reducing the denitration reaction temperature range to 750-1100°C.

[0013] Furthermore, setting an appropriate steam pressure helps to optimize the SNCR reaction conditions and thus improve the denitrification efficiency; by precisely controlling the flow ratio of steam to ammonia water, it can be ensured that the SNCR reaction is carried out under optimal conditions, thereby improving the denitrification efficiency.

[0014] Furthermore, through continuous monitoring and adjustment, the nitrogen oxide emission concentration can be maintained at a low level, the denitrification efficiency can be improved, the denitrification ammonia consumption and ammonia escape can be reduced, and the denitrification process can be made environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the structure of an SNCR device of the present invention; Figure 2 A side view of an SNCR device of the present invention; Figure 3 This is a schematic diagram of the structure of an ammonia gasifier of a SNCR device of the present invention; Figure 4 A schematic diagram of the structure of a gas spray gun of a SNCR device of the present invention; Figure 5 A cross-sectional view of a gas spray gun of a SNCR device of the present invention; Figure 6 A cross-sectional view of a main air pipe of an SNCR device of the present invention; Figure 7 A schematic diagram of the installation of a gas spray gun for a SNCR device of the present invention; Figure 8 A schematic diagram of a SNCR denitration method of the present invention; In the figure, 1-manual valve; 2-pressure reducing valve; 3-steam buffer tank; 4-pressure stabilizing exhaust valve; 5-intake pipe; 6-steam outlet pipe; 7-drain pipe; 8-drain valve; 9-vortex flowmeter; 10-flow regulating valve; 11-steam manual valve; 12-ammonia vaporizer; 12-1-straight pipe section; 12-2-narrowing section; 12-3-throat; 12-4-expanding section; 12-5-top inlet; 12-6-middle inlet; 12-7-bottom outlet; 13-ammonia flowmeter; 14-ammonia manual valve; 15-ammonia flow Regulating valve; 16-steam inlet pipe; 17-outlet pipe; 18-ammonia inlet pipe; 19-distributor; 20-spray gun valve; 21-gas spray gun; 21-1-inlet pipe; 21-2-main gas pipe; 21-3-cooling jacket; 21-4-rifling; 21-5-anti-wear nozzle; 21-6-handle; 21-7-compressed air interface; 21-8-compressed air pipe; 21-9-insulation layer; 21-10-negative line; 21-11-positive line; 22-nitrogen oxide concentration analyzer; 23-ammonia detector; 24-trap. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it. In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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 should fall within the scope of protection of the present invention. It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0017] Embodiment 1: The present invention provides a SNCR device, such as Figure 7 As shown, it includes a furnace, a separator, an upper tail flue, an air preheater, a lower tail flue, a nitrogen oxide concentration analyzer 22, and an ammonia detector 23; a plurality of gas spray guns 21 are respectively installed on the furnace and at the entrance of the separator, the ammonia detector 23 is installed in the upper tail flue, the upper tail flue is connected to the lower tail flue through the air preheater, and the nitrogen oxide concentration analyzer 22 is installed in the lower tail flue.

[0018] like Figure 1 and Figure 2As shown, it also includes a steam intake device, an ammonia liquid intake device, an exhaust device and an ammonia vaporizer 12; the steam intake device includes a pressure reducing device, a steam buffer tank 3, an intake pipe 5, a steam outlet pipe 6, a vortex flowmeter 9, a flow regulating valve 10, a steam manual valve 11 and a steam intake pipe 16; the pressure reducing device includes a manual valve 1 and a pressure reducing valve 2, and the manual valve 1 is used to manually close the valve and isolate the system when an unexpected situation such as power failure or short circuit occurs in the automatic control system; the steam buffer tank 3 includes a pressure-stabilizing exhaust valve 4, a drain pipe 7 and a drain valve 8; the ammonia liquid intake device includes an ammonia flowmeter 13, an ammonia manual valve 14, an ammonia flow regulating valve 15 and an ammonia intake pipe 18; the exhaust device includes an exhaust pipe 17, a distributor 19, a spray gun valve 20, a gas spray gun 21 and a drain valve 24; The steam intake device includes a pressure reducing device, which includes a manual valve 1 and a plurality of pressure reducing valves 2 connected in sequence through an intake pipe 5. The pressure reducing device is connected to a steam buffer tank 3 through an intake pipe 5. A pressure stabilizing exhaust valve 4 is installed on the top of the steam buffer tank 3. When the steam pressure in the steam buffer tank 3 increases to exceed the set pressure upper limit, the pressure stabilizing exhaust valve 4 is automatically opened to reduce the steam pressure to within the set working pressure range. The lower part of the steam buffer tank 3 is connected to a drain valve 8 through a drain pipe 7. The drain valve 8 is opened regularly to discharge the condensed water accumulated in the steam buffer tank 3. The steam pressure at the outlet of the steam buffer tank 3 is maintained at 0.05~0.5 MPa, and the temperature is greater than 150 ℃, the steam buffer tank 3 is connected to a vortex flowmeter 9, a flow regulating valve 10 and a steam manual valve 11 in sequence through a plurality of steam outlet pipes 6, the vortex flowmeter 9 is used to measure the steam flow in real time, the flow regulating valve 10 is used to control the mass ratio of the ammonia flow rate to the steam flow rate entering the ammonia vaporizer 12 to be 1: (2~20), the steam manual valve 11 is connected to the middle inlet 12-6 through the steam intake pipe 16; the ammonia liquid inlet device includes an ammonia inlet pipe 18, which is connected to an ammonia flowmeter 13, an ammonia flow regulating valve 15, an ammonia manual valve 14 and a top inlet 12-5 in sequence through the ammonia inlet pipe 18, the ammonia flowmeter 13 measures the ammonia flow in real time, the ammonia manual valve 14 is used to manually close the ammonia pipe to block the inflow of ammonia when the automatic control system fails, and the ammonia flow regulating valve 15 is used to manually close the ammonia pipe according to the nitrogen oxide concentration analyzer 22 and The ammonia detector 23 detects the nitrogen oxide emission concentration and ammonia escape concentration to adjust the ammonia injection amount. When the nitrogen oxide concentration is greater than the set concentration, the opening of the ammonia flow regulating valve 15 is increased to increase the ammonia flow rate, so that the nitrogen oxide concentration is stabilized below the set concentration. When the ammonia escape concentration is greater than the set concentration, the opening of the ammonia flow regulating valve 15 is reduced to reduce the ammonia flow rate, so that the ammonia escape concentration is stabilized below the set concentration; the gas outlet device includes an outlet pipe 17, and the bottom outlet 12-7 is connected to the distributor 19 through the outlet pipe 17. The side of the distributor 19 is connected to a plurality of spray gun valves 20 through a plurality of distribution ports. Each spray gun valve 20 is connected to a gas spray gun 21 through a hose. The spray gun valve 20 is used to adjust the valve opening according to the installation position of each spray gun 21 and the denitrification requirements, and adjust the flow of the mixed gas into the spray gun. The bottom of the distributor 19 is connected to a steam trap 24; Preferably, the number of the pressure reducing valves 2 is 2; Preferably, the pressure reducing valve 2 can be a self-operated pressure reducing valve or an electric pressure reducing valve, and can be composed of a single-stage or multi-stage pressure reducing valve according to the incoming steam pressure.

[0019] like Figure 3As shown, the ammonia vaporizer 12 includes a straight pipe section 12-1, a constricted section 12-2, a throat 12-3, a flared section 12-4, a top inlet 12-5, a middle inlet 12-6 and a bottom outlet 12-7; the straight pipe section 12-1 performs an ammonia evaporation reaction, a top inlet 12-5 is installed at the top of the straight pipe section 12-1, and the top inlet 12-5 is connected to an ammonia liquid inlet device, a middle inlet 12-6 is installed in the middle of the straight pipe section 12-1, and the middle inlet 12-6 is connected to a steam air inlet device, a constricted section 12-2 is installed at the bottom of the straight pipe section 12-1, a throat 12-3 is installed at the bottom of the constricted section 12-2, a flared section 12-4 is installed at the bottom of the throat 12-3, a bottom outlet 12-7 is installed at the bottom of the flared section 12-4, and the bottom outlet 12-7 is connected to an air outlet device; Preferably, the angle between the steam inlet pipe 16 and the straight pipe section 12 - 1 is 90°; Preferably, the steam pressure reducing and stabilizing valve 2 controls the pressure of the incoming steam to 0.05-0.8 MPa; Preferably, the flow regulating valve 10 sets the mass ratio of the ammonia flow rate to the steam flow rate entering the ammonia vaporizer to 1: (2-20); Preferably, the length of the straight pipe section 12-1 is 100-1000 mm; the length of the constricted section 12-2 is 100 mm; the length of the throat 12-3 is 200 mm; the length of the expanded section 12-4 is 200-2000 mm; Preferably, the angle between the necking section 12-2 and the throat section 12-3 is 5° to 20°; Preferably, the angle between the expansion section 12-4 and the throat 12-3 is 5° to 30°.

[0020] like Figure 4 , Figure 5 and Figure 6 As shown, the gas spray gun 21 includes an air inlet pipe 21-1, a main air pipe 21-2, a cooling sleeve 21-3, rifling 21-4, an anti-wear nozzle 21-5, a handle 21-6, a compressed air interface 21-7, a compressed air pipe 21-8, an insulation layer 21-9, a negative line 21-10 and a positive line 21-11; the air inlet pipe 21-1 is installed at one end of the main air pipe 21-2, the handle 21-6 is installed on the air inlet pipe 21-1, and the other end of the main air pipe 21-2 is installed on the handle 21-6. An anti-wear nozzle 21-5 is installed at the end; a cooling sleeve 21-3 is sleeved on the main air pipe 21-2, and an insulation layer 21-9 is installed on the cooling sleeve 21-3. The cooling sleeve 21-3 is also connected to a compressed air pipe 21-8, and a compressed air interface 21-7 is opened at one end of the compressed air pipe 21-8; a plurality of rifling grooves 21-4 are arranged on the inner side of the main air pipe 21-2, and the rifling grooves 21-4 are composed of negative lines 21-10 and positive lines 21-11 arranged alternately in a spiral shape; Preferably, the gas spray gun 21 is a pure gas spray gun, which can convert the gas into a high momentum jet in the spray gun and spray it into the flue gas; Preferably, the spray gun valve 20 is connected to the gas spray gun 21 through the air inlet pipe 21-1; Preferably, the surface of the rifling 21 - 4 is plated with chrome, and the thickness of the chrome plating is 10 to 500 μm; Preferably, the scale of the rifling 21-4 can be adjusted according to the on-site smoke flow field conditions and is made of 316L stainless steel; Preferably, the total length of the rifling 21-4 is 100-1000 mm, and the twist pitch is 100-1000 mm; Preferably, the number of rifling lines 21-4 is 1 to 8; Preferably, the depth of the rifling 21-4 is 1% to 10% of the diameter of the main air pipe 21-2. The larger the diameter of the anti-wear nozzle 21-5, the smaller the depth ratio of the rifling 21-4 to the diameter of the main air pipe 21-2. Preferably, the width of the negative line 21 - 10 is greater than or equal to the width of the positive line 21 - 11, and the width ratio of the negative line 21 - 10 to the positive line 21 - 11 is (1~5):1.

[0021] Embodiment 2: like Figure 8 As shown, the present invention provides a SNCR denitrification method, based on the above-mentioned SNCR device, comprising the following steps: (1) Steam is introduced into the air inlet pipe 5, and the steam is decompressed to 0.05-0.5 MPa through the pressure reducing valve 2 of the pressure reducing device, and then introduced into the steam buffer tank 3 after decompression; (2) When the steam pressure in the steam buffer tank 3 exceeds the upper limit of the working pressure of 0.5 MPa, the pressure-stabilizing exhaust valve 4 automatically opens, and after the pressure is released to within the working pressure range, the steam continues to flow into the steam intake device and then into the ammonia vaporizer 12; When the steam pressure in the steam buffer tank 3 does not exceed the upper limit of the working pressure of 0.5 MPa, the steam continues to be introduced into the steam intake device and then into the ammonia vaporizer 12; (3) Ammonia water is introduced into the ammonia inlet pipeline 18, and the mass ratio of the ammonia water flow rate to the steam flow rate is controlled by the flow control valve 10 to be 1: (2-20). The ammonia water flows through the ammonia water flow control valve 15 and the ammonia water manual valve 14 and enters the ammonia water vaporizer 12. The ammonia water flow control valve 15 adjusts the ammonia water injection amount according to the nitrogen oxide emission concentration and ammonia escape concentration detected by the nitrogen oxide concentration analyzer 22 and the ammonia gas detector 23, specifically: When the nitrogen oxide emission concentration is greater than 50 mg / m 3 When the ammonia flow rate is increased to a nitrogen oxide emission concentration of less than 45 mg / m 3 ; When the ammonia escape concentration is >8 mg / m 3 When the ammonia flow rate is reduced to ammonia escape concentration of less than 8 mg / m 3 , while maintaining nitrogen oxide emission concentration <45 mg / m 3 ; (4) The steam and ammonia water are fully atomized in the straight pipe section 12-1 in the ammonia water vaporizer 12 and rapidly vaporized with intense heat exchange to obtain a gas phase mixture, which is then passed into the distributor 19 through the gas outlet pipe 17; (5) The distributor 19 distributes the mixed gas to each gas spray gun 21. The spray gun valve 20 adjusts the opening according to the position of the gas spray gun 21 and the distribution of the flue gas flow. The gas spray gun 21 sprays the gas phase mixture into the flue gas at 750-1100 °C to achieve SNCR denitrification. The internal reaction of the gas spray gun 21 is as follows: compressed air is introduced from the compressed air interface 21-7, the compressed air enters the cooling sleeve 21-3 for cooling, and the ammonia-containing gas enters the spray gun through the air inlet pipe 21-1. When passing through the main air pipe 21-2, the gas begins to rotate under the action of the rifling 21-4, and finally the gas is sprayed into the flue gas through the anti-wear nozzle 21-5 at a certain rotation speed. The rotating airflow can be quickly mixed with the flue gas through the suction effect in the flue gas.

[0022] Embodiment 3: like Figure 7 As shown, taking a fluidized bed boiler as an example, a group of 6 gas spray guns 21 as group A is installed on the top of the furnace, and a group of 4 gas spray guns 21 as group B is installed at the inlet of the separator. On this basis, the high-efficiency SNCR device and its implementation method of the present invention are carried out.

[0023] The steam of the steam buffer tank 3 is connected to two groups of ammonia vaporizers 12 and the steam intake pipe 16. The ammonia vaporizer 12 of group A is connected to the distributor 19 through the outlet pipe 17. The distributor 19 is connected to 6 gas spray guns 21 through a hose, i.e., the intake pipe 21-1. The ammonia vaporizer 12 of group B is connected to the distributor 19 through the outlet pipe 17. The distributor 19 is connected to 4 gas spray guns 21 through a hose, i.e., the intake pipe 21-1; the two-stage pressure reducing valve 2 is installed at the intake pipe 5 in front of the steam buffer tank 3, the drain valve 8 is installed on the drain pipe 7, the vortex flowmeter 9 is installed on the steam intake pipe 16, the flow regulating valve 10 is installed on the steam intake pipe 16, the ammonia flow regulating valve 15 and the ammonia flowmeter 13 are installed on the ammonia pipe 18, the spray gun valve 20 is installed at the distribution port of the distributor 19, and the nitrogen oxide concentration analyzer 22 and the ammonia detector 23 are installed at the tail flue; The steam extracted from the intermediate pressure cylinder of the steam turbine first passes through the pressure reducing valve 2. The two-stage self-operated pressure reducing valve 2 adjusts the valve opening according to the incoming steam pressure to reduce the steam pressure to 0.1~0.5 MPa, and then the steam enters the steam buffer tank 3. The steam buffer tank 3 divides the steam into the group A ammonia vaporizer 12 and the group B ammonia vaporizer 12; under the low load condition of the boiler, the group A ammonia vaporizer 12 is in operation, and the position of the group B gas spray gun 21 corresponding to the group B ammonia vaporizer 12 is not put into operation due to the low flue gas temperature. The ammonia flow regulating valve 15 of the group A ammonia vaporizer 12 adjusts the amount of ammonia injected according to the nitrogen oxide concentration and ammonia escape concentration detected by the nitrogen oxide concentration analyzer 22 and the ammonia detector 23. When the nitrogen oxide emission concentration is greater than 50 mg / m 3 When the ammonia flow rate is increased, the nitrogen oxide emission concentration is stabilized to less than 45 mg / m 3 ; When the nitrogen oxide emission concentration is stable <45 mg / m 3 、Ammonia escape>8 mg / m 3 Reduce the ammonia flow rate to ammonia escape < 8 mg / m 3 At the same time, the nitrogen oxide emission concentration is stable <45mg / m 3 The flow regulating valve 10 of the group A ammonia vaporizer 12 adjusts the opening according to the ammonia flow rate, and adjusts the steam flow entering the group A ammonia vaporizer 12 in real time according to the mass ratio of the ammonia flow rate to the steam flow rate of 1:10. The steam in the group A ammonia vaporizer 12 converts the ammonia into a gaseous mixture of water vapor and ammonia. The gaseous mixture is passed into the distributor 19, and the distributor 19 distributes the gaseous mixture to 6 group A gas spray guns 21. The spray gun valve 20 adjusts the opening according to the position of the group A gas spray gun 21 and the flue gas flow rate. Under the action of the group A gas spray gun 21, the gaseous mixture is sprayed into the temperature area of ​​750-760 ° C in the flue gas to achieve high-efficiency SNCR denitrification; Under the medium and high load conditions of the boiler, the ammonia vaporizer 12 of group A and the ammonia vaporizer 12 of group B operate simultaneously, and the ammonia flow regulating valve 15 adjusts the amount of ammonia injected according to the nitrogen oxide concentration and ammonia escape concentration detected by the nitrogen oxide concentration analyzer 22 and the ammonia detector 23. The ammonia flow ratio of the ammonia vaporizer 12 of group A and the ammonia vaporizer 12 of group B is 6:4. Under the regulation of the flow regulating valve 10, the steam enters the ammonia vaporizers 12 of group A and group B according to the mass ratio according to the ammonia flow in the ammonia vaporizers 12 of group A and group B. The gas phase mixture is distributed to the gas spray guns 21 of group A and group B by the action of the distributor 19. Under the action of the gas spray guns 21 of group A and group B, the gas phase mixture is sprayed into the temperature area of ​​750~760℃ in the flue gas to complete the high-efficiency SNCR denitrification.

[0024] Embodiment 4: Taking a fluidized bed boiler as an example, a group of three gas spray guns 21 as group A is installed on the top of the furnace, and a group of two gas spray guns 21 as group B is installed at the inlet of the separator. On this basis, the implementation method of the high-efficiency SNCR device of the present invention is carried out.

[0025] The steam extracted from the intermediate pressure cylinder of the steam turbine first passes through the pressure reducing valve 2. The two-stage self-operated pressure reducing valve 2 adjusts the valve opening according to the incoming steam pressure to reduce the steam pressure to 0.05~0.1 MPa, and then the steam enters the steam buffer tank 3. The steam buffer tank 3 divides the steam into the group A ammonia vaporizer 12 and the group B ammonia vaporizer 12; under the low load condition of the boiler, the group A ammonia vaporizer 12 is in operation, and the position of the group B gas spray gun 21 corresponding to the group B ammonia vaporizer 12 is not put into operation due to the low flue gas temperature. The ammonia flow regulating valve 15 of the group A ammonia vaporizer 12 adjusts the amount of ammonia injected according to the nitrogen oxide concentration and ammonia escape concentration detected by the nitrogen oxide concentration analyzer 22 and the ammonia detector 23. When the nitrogen oxide emission concentration is greater than 50 mg / m 3 When the ammonia flow rate is increased, the nitrogen oxide emission concentration is stabilized to less than 45 mg / m 3 ; When the nitrogen oxide emission concentration is stable <45mg / m 3 、Ammonia escape>8 mg / m 3 Reduce the ammonia flow rate to ammonia escape < 8 mg / m 3 At the same time, the nitrogen oxide emission concentration is stable <45 mg / m 3 The flow regulating valve 10 of the group A ammonia vaporizer 12 adjusts the opening according to the ammonia flow rate, and adjusts the steam flow entering the group A ammonia vaporizer 12 in real time according to the mass ratio of the ammonia flow rate to the steam flow rate of 1:2. In the group A ammonia vaporizer 12, the steam converts the ammonia into a gaseous mixture of water vapor and ammonia. The gaseous mixture is passed into the distributor 19, and the distributor 19 distributes the gaseous mixture to three group A gas spray guns 21. The spray gun valve 20 adjusts the opening according to the position of the group A gas spray gun 21 and the flue gas flow rate. Under the action of the group A gas spray gun 21, the gaseous mixture is sprayed into the temperature area of ​​750-900°C in the flue gas to achieve efficient SNCR denitrification. Under the medium and high load conditions of the boiler, the ammonia vaporizer 12 of group A and the ammonia vaporizer 12 of group B operate simultaneously, and the ammonia flow regulating valve 15 adjusts the amount of ammonia injected according to the nitrogen oxide concentration and ammonia escape concentration detected by the nitrogen oxide concentration analyzer 22 and the ammonia detector 23. The ratio of the ammonia flow of the ammonia vaporizer 12 of group A to that of the ammonia vaporizer 12 of group B is 6:4. Under the regulation of the flow regulating valve 10, the steam enters the ammonia vaporizers 12 of group A and group B according to the mass ratio according to the ammonia flow in the ammonia vaporizers 12 of group A and group B. The gas phase mixture is distributed to the gas spray guns 21 of group A and group B under the action of the distributor 19. Under the action of the gas spray guns 21 of group A and group B, the gas phase mixture is sprayed into the temperature area of ​​750~900℃ in the flue gas to complete the high-efficiency SNCR denitrification.

[0026] Embodiment 5: Taking a fluidized bed boiler as an example, a group of 8 gas spray guns 21 as group A is installed on the top of the furnace, and a group of 4 gas spray guns 21 as group B is installed at the inlet of the separator. On this basis, the implementation method of the high-efficiency SNCR device of the present invention is carried out.

[0027] The steam extracted from the intermediate pressure cylinder of the steam turbine first passes through the pressure reducing valve 2. The two-stage self-operated pressure reducing valve 2 adjusts the valve opening according to the incoming steam pressure to reduce the steam pressure to 0.1~0.5 MPa, and then the steam enters the steam buffer tank 3. The steam buffer tank 3 divides the steam into the group A ammonia vaporizer 12 and the group B ammonia vaporizer 12; under the low load condition of the boiler, the group A ammonia vaporizer 12 is in operation, and the position of the group B gas spray gun 21 corresponding to the group B ammonia vaporizer 12 is not put into operation due to the low flue gas temperature. The ammonia flow regulating valve 15 of the group A ammonia vaporizer 12 adjusts the amount of ammonia injected according to the nitrogen oxide concentration and ammonia escape concentration detected by the nitrogen oxide concentration analyzer 22 and the ammonia detector 23. When the nitrogen oxide emission concentration is greater than 50 mg / m 3 When the ammonia flow rate is increased, the nitrogen oxide emission concentration is stabilized to less than 45 mg / m 3 ; When the nitrogen oxide emission concentration is stable <45 mg / m 3 、Ammonia escape>8 mg / m 3 Reduce the ammonia flow rate to ammonia escape < 8 mg / m 3 At the same time, the nitrogen oxide emission concentration is stable <45mg / m 3The flow regulating valve 10 of the group A ammonia vaporizer 12 adjusts the opening according to the ammonia flow rate, and adjusts the steam flow entering the group A ammonia vaporizer 12 in real time according to the mass ratio of the ammonia flow rate to the steam flow rate of 1:20. In the group A ammonia vaporizer 12, the steam converts the ammonia into a gaseous mixture of water vapor and ammonia. The gaseous mixture is passed into the distributor 19, and the distributor 19 distributes the gaseous mixture to 8 group A gas spray guns 21. The spray gun valve 20 adjusts the opening according to the position of the group A gas spray gun 21 and the flue gas flow rate. Under the action of the group A gas spray gun 21, the gaseous mixture is sprayed into the temperature area of ​​900-1100 ° C in the flue gas to achieve high-efficiency SNCR denitrification; Under the medium and high load conditions of the boiler, the ammonia vaporizer 12 of group A and the ammonia vaporizer 12 of group B operate simultaneously, and the ammonia flow regulating valve 15 adjusts the amount of ammonia injected according to the nitrogen oxide concentration and ammonia escape concentration detected by the nitrogen oxide concentration analyzer 22 and the ammonia detector 23. The ratio of the ammonia flow of the ammonia vaporizer 12 of group A to that of the ammonia vaporizer 12 of group B is 6:4. Under the regulation of the flow regulating valve 10, the steam enters the ammonia vaporizers 12 of group A and group B according to the mass ratio according to the ammonia flow in the ammonia vaporizers 12 of group A and group B. The gas phase mixture is distributed to the gas spray guns 21 of group A and group B by the action of the distributor 19. Under the action of the gas spray guns 21 of group A and group B, the gas phase mixture is sprayed into the temperature area of ​​900~1100℃ in the flue gas to complete the high-efficiency SNCR denitrification.

[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A SNCR device, characterized in that: The invention comprises an upper tail flue, wherein the upper tail flue is equipped with an ammonia detector (23), the upper tail flue is connected to the lower tail flue through an air preheater, and the lower tail flue is equipped with a nitrogen oxide concentration analyzer (22); and an ammonia vaporizer (12), wherein the ammonia vaporizer (12) comprises a straight pipe section (12-1), a top inlet (12-5) is installed at the top of the straight pipe section (12-1), and the top inlet (12-5) is connected to an ammonia liquid inlet device, and the straight pipe section (12-1 ) is provided with a middle inlet (12-6) in the middle part, the middle inlet (12-6) is connected to a steam intake device, a contraction section (12-2) is provided at the bottom of the straight pipe section (12-1), a throat section (12-3) is provided at the bottom of the contraction section (12-2), an expansion section (12-4) is provided at the bottom of the throat section (12-3), a bottom outlet (12-7) is provided at the bottom of the expansion section (12-4), and the bottom outlet (12-7) is connected to an exhaust device; The steam intake device comprises a pressure reducing device, the pressure reducing device is connected to a steam buffer tank (3) via an intake pipe (5), the steam buffer tank (3) is sequentially connected to a vortex flowmeter (9), a flow regulating valve (10) and a steam manual valve (11) via a plurality of steam outlet pipes (6), and the steam manual valve (11) is connected to a middle inlet (12-6) via a steam intake pipe (16); The ammonia liquid inlet device comprises an ammonia inlet pipeline (18), through which an ammonia flow meter (13), an ammonia flow regulating valve (15), an ammonia manual valve (14) and a top inlet (12-5) are sequentially connected; The gas outlet device comprises a gas outlet pipeline (17), the bottom outlet (12-7) is connected to a distributor (19) via the gas outlet pipeline (17), the side of the distributor (19) is connected to a plurality of spray gun valves (20) via a plurality of distribution ports, each spray gun valve (20) is connected to a gas spray gun (21) via a hose, and the bottom of the distributor (19) is connected to a drain valve (24).

2. The SNCR device according to claim 1, characterized in that: The angle between the steam intake pipe (16) and the straight pipe section (12-1) is 90°.

3. The SNCR device according to claim 1, characterized in that: The pressure reducing device comprises a manual valve (1) and a plurality of pressure reducing valves (2) which are connected in sequence via an air intake pipeline (5).

4. The SNCR device according to claim 1, characterized in that: A pressure-stabilizing exhaust valve (4) is installed on the top of the steam buffer tank (3), and a drain valve (8) is connected to the bottom of the steam buffer tank (3) via a drain pipe (7).

5. The SNCR device according to claim 1, characterized in that: The gas spray gun (21) comprises a main gas pipe (21-2), one end of the main gas pipe (21-2) is equipped with an air inlet pipe (21-1), the air inlet pipe (21-1) is equipped with a handle (21-6), and the other end of the main gas pipe (21-2) is equipped with an anti-wear nozzle (21-5); a cooling sleeve (21-3) is sleeved on the main gas pipe (21-2), a heat insulation layer (21-9) is installed on the cooling sleeve (21-3), a compressed air pipe (21-8) is also connected to the cooling sleeve (21-3), and a compressed air interface (21-7) is opened at one end of the compressed air pipe (21-8); a plurality of rifling grooves (21-4) are arranged on the inner side of the main gas pipe (21-2), and the rifling grooves (21-4) are composed of negative lines (21-10) and positive lines (21-11) arranged alternately in a spiral shape.

6. The SNCR device according to claim 5, characterized in that: The spray gun valve (20) is connected to the gas spray gun (21) via an air inlet pipe (21-1).

7. The SNCR device according to claim 5, characterized in that: The surface of the rifling (21-4) is plated with chrome; the width of the negative line (21-10) is greater than or equal to the width of the positive line (21-11).

8. A SNCR denitrification method, based on a SNCR device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, steam is introduced into the air inlet pipe (5), and the steam is introduced into the steam buffer tank (3) via the pressure reducing device; S2, when the steam pressure in the steam buffer tank (3) exceeds the upper limit of the working pressure, the steam is released to the working pressure range, and then continues to be introduced into the steam intake device and then into the ammonia vaporizer (12); When the steam pressure in the steam buffer tank (3) does not exceed the upper limit of the working pressure, the steam continues to be introduced into the steam intake device and then introduced into the ammonia vaporizer (12); S3, introducing ammonia water into the ammonia inlet pipeline (18), controlling the steam flow rate and the ammonia water flow rate through the flow control valve (10), and the ammonia water flows through the ammonia water flow control valve (15) and the ammonia water manual valve (14), and enters the ammonia water vaporizer (12), wherein the ammonia water flow control valve (15) adjusts the ammonia water injection amount according to the nitrogen oxide emission concentration and the ammonia escape concentration detected by the nitrogen oxide concentration analyzer (22) and the ammonia gas detector (23); S4, atomizing and vaporizing steam and ammonia water in the straight pipe section (12-1) in the ammonia water vaporizer (12) to obtain a gas phase mixture, and the gas phase mixture is passed into the distributor (19) through the gas outlet pipe (17); S5, the distributor (19) distributes the mixed gas to each gas spray gun (21), the spray gun valve (20) adjusts the opening according to the position of the gas spray gun (21) and the distribution of the flue gas flow, and the gas spray gun (21) sprays the gas phase mixture into the flue gas to achieve SNCR denitrification.

9. The SNCR denitration method according to claim 8, characterized in that: The method of using a pressure reducing device in S1 specifically includes: reducing the steam pressure to 0.05-0.5 MPa via a pressure reducing device; the upper limit of the working pressure in S2 is 0.5 MPa; the mass ratio of the ammonia flow rate to the steam flow rate in S3 is controlled to be 1:(2-20); the flue gas temperature in S5 is 750-1100 °C.

10. The SNCR denitration method according to claim 8, characterized in that: The ammonia water flow control valve (15) in S3 adjusts the ammonia water injection amount according to the nitrogen oxide emission concentration and ammonia escape concentration detected by the nitrogen oxide concentration analyzer (22) and the ammonia detector (23): When the nitrogen oxide emission concentration is greater than 50 mg / m 3 When the ammonia flow rate is increased to a nitrogen oxide emission concentration of less than 45 mg / m 3 ; When the ammonia escape concentration is >8 mg / m 3 When the ammonia flow rate is reduced to ammonia escape concentration of less than 8 mg / m 3 , while maintaining nitrogen oxide emission concentration <45 mg / m 3 .

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