SCR (Selective Catalytic Reduction) denitration reactor

Abstract

The utility model discloses an SCR (Selective Catalytic Reduction) denitration reactor which comprises a tank body, a plurality of spray gun mounting ports which are distributed in a staggered manner are uniformly distributed on the opposite surfaces of the side wall of the tank body along the axial direction of the tank body at intervals, and a heating insulating layer is arranged on the side wall; the heating body is embedded in the heating insulating layer; the spiral guide plate is vertically fixed in the middle of the bottom in the tank body and spirally upwards along the axial direction of the tank body; the spray gun is fixed on the spray gun mounting opening; the preheating coil pipe is arranged in the heating insulating layer, spirally ascends around the side wall of the tank body and comprises a spiral pipe and a straight pipe, an air outlet of the spiral pipe is communicated with an air inlet of the straight pipe, and an air outlet of the straight pipe is communicated with the bottom of the tank body; the temperature sensors are arranged at the bottom, the middle part and the upper part of the tank body; and the programmable temperature control meter is connected with the heating body. According to the denitration reactor, the residence time of gas in the tank body can be prolonged, the stroke of gas flow can be improved by more than five times, the reaction time is greatly prolonged, and the denitration effect is greatly improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of denitration, and particularly relates to an SCR denitration reactor. Background Art

[0002] Coal-fired power plants and various industrial boilers emit a large amount of nitrogen oxides (NO x ), which seriously pollute the environment and endanger human health. Removing nitrogen oxides from combustion flue gas to prevent environmental pollution has been sharply raised as a worldwide problem. Currently, the relatively mainstream processes in the world are divided into: SCR (Selective Catalytic Reduction) and SNCR (Selective Non-Catalytic Reduction). Except that the reaction temperature of SCR is lower than that of SNCR due to the use of a catalyst, SCR not only has high-efficiency denitration ability, but also has a simple structure and will not cause a large burden on flue gas denitration. In SCR for flue gas denitration, under the action of a catalyst (such as alkali metals like iron, vanadium, chromium, etc.), by injecting ammonia or other reducing agents, high-efficiency NO x reduction can be achieved in the temperature range of 200~450°C. Since NH3 is selective, it mainly reacts with NO x and generates non-toxic and pollution-free N2 and H2O, without reacting with O2, so it is selective catalytic reduction denitration. The applicable temperature of SNCR in thermal power plants is 850°C~1100°C, and it needs to be controlled by professional operators to prevent excessive temperature from generating excess NO x . SNCR is only applied to flue gas denitration with low conditional selectivity. In some thermal power plants, SNCR is used to make up for the deficiencies in SCR flue gas purification in flue gas denitration, and it has gradually developed into an auxiliary means to improve the standard of flue gas denitration technology in thermal power plants.

[0003] Selective Catalytic Reduction (SCR) is currently the most widely studied and applied NO x emission control technology. The denitration device adopted by SCR includes the evaporation of ammonia, the mixing with dilution air or flue gas, and the injection of it into the flue gas upstream of the SCR reactor through an ammonia injection grid.

[0004] With the development of technology, there is currently also a technology for denitration using a liquid catalyst, and the catalytic reaction of the liquid catalyst is used to treat NO x , and the liquid catalytic denitration technology integrates technologies such as absorption and catalytic reaction, and mainly converts NO x into H2O and N2, without secondary pollution.

[0005] A reaction device for SCR, such as an environmental protection denitration dilution fan heating device disclosed in Chinese Patent CN215962940U. A fan is provided in its reaction tank, which can spray ammonia water into the interior of the reaction tank. At the same time, the fan generates a large amount of heat, providing a large amount of heat for the reaction of ammonia water, making it easier for ammonia water to react. Through the arrangement of spiral blades, the fan blows the spiral blades to rotate, enabling the flue gas and ammonia water inside the reaction tank to react fully. However, the heat generated by the fan is limited, and the flue gas is directly introduced from the bottom of the tank body, making it difficult to reach the temperature required for the reaction. In addition, although spiral blades are provided, they only play a stirring role, and the denitration efficiency of the entire device is low.

[0006] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Utility Model

[0007] The purpose of the present utility model is to provide an SCR denitration reactor, which solves the problems that the flue gas in the existing device is difficult to reach the reaction temperature and the contact time in the reaction tank is short and cannot react fully. It can preheat the flue gas sufficiently and extend the contact time between the flue gas and the SCR reaction mixture, greatly improving the denitration effect.

[0008] To achieve the above purpose, the present utility model provides an SCR denitration reactor, which comprises: a tank body, on the opposite surfaces of its side wall, a plurality of spray gun mounting openings are arranged at intervals along the axial direction of the tank body, and the spray gun mounting openings on the two surfaces are arranged in a staggered manner. A heating and heat preservation layer is also provided on its side wall, a sewage discharge port is provided at its bottom, and a tank cover is sealed at its top. An exhaust port for discharging denitrated gas is provided in the middle or on the side of the tank cover; a heating element, which is embedded in the heating and heat preservation layer and is used to heat the tank body; a spiral guide plate, which is vertically and detachably fixed in the middle of the inner bottom of the tank body, spirals upward along the axial direction of the tank body, and there is a gap between its outer side and the inner wall of the reactor tank body; a spray gun, which is fixed on the spray gun mounting opening and is used to spray the SCR reaction mixture; a preheating coil, which is arranged on one side of the heating and heat preservation layer close to the side wall of the tank body, and comprises: a spiral pipe and a straight pipe. The spiral pipe of the preheating coil spirals upward along the axial direction of the tank body. One end of the intake port of the spiral pipe passes through the side wall of the tank body and is outside the tank body. The outlet of the spiral pipe is communicated with the intake port of the straight pipe, and the outlet of the straight pipe is communicated to the bottom of the tank body. The intake port of the spiral pipe is used to introduce the flue gas to be treated, and the outlet of the straight pipe is used to discharge the preheated flue gas; a temperature sensor, which is arranged at the bottom, middle and upper part of the tank body, and is used to monitor the temperature of the preheated gas at the bottom of the tank body, the temperature of the tank body and the temperature of the heating and heat preservation layer respectively; and a programmable temperature control meter, which is connected to the heating element through a bus and is used to control the temperature adjustment of the heating element.

[0009] Preferably, the tank body and the tank cover adopt a detachable connection method.

[0010] Preferably, the tank body and the tank cover are connected by a flange.

[0011] Preferably, the space between the flange of the tank body and the flange of the tank cover is sealed with graphite packing.

[0012] Preferably, the reactor further comprises a support frame for fixing the tank body.

[0013] Preferably, the tank body, the spiral baffle plate, and the preheating coil are all made of high-temperature resistant stainless steel, and the heating and insulation layer is made of inorganic ceramic fiber.

[0014] The SCR denitration reactor of the present utility model has the following advantages:

[0015] (1) In the SCR denitration reactor of the present utility model, the preheating coil is arranged inside the tank body and spirally rises along the side wall of the tank body, increasing the travel of the flue gas inside the preheating coil, and being able to better preheat the flue gas;

[0016] (2) In the SCR denitration reactor of the present utility model, through the design of the spiral baffle plate, the gas can rise in a spiral manner, prolonging the residence time of the gas inside the tank body, increasing the travel of the gas flow by more than 5 times, and greatly improving the denitration effect. Moreover, the spiral baffle plate is designed to be flexibly removable, facilitating the cleaning of deposits;

[0017] (3) In the SCR denitration reactor of the present utility model, the spray gun installation openings on the tank body adopt a staggered rising and plane-symmetrical arrangement, avoiding the interference between multiple spray guns on the same horizontal plane, and at the same time reducing the number of openings in the heating and insulation layer, avoiding excessive complexity of the reactor;

[0018] (4) In the SCR denitration reactor of the present utility model, a heating and insulation layer is provided on the side wall of the tank body, the heating element is embedded in the heating and insulation layer, the heating element is connected to the programmable temperature control meter through a bus, the programmable temperature control meter controls the current of the heating circuit through a power regulation module to adjust the heating power, and the resistance wire can quickly heat up the tank body. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the SCR denitration reactor of the present utility model.

[0020] Figure 2 It is a schematic structural diagram of the spiral baffle plate of the present utility model. Detailed Embodiments

[0021] The technical solutions in the embodiments of the present utility model will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0022] It should be noted that the features mentioned in the present utility model can be combined arbitrarily as long as there is no contradiction in the combination of these features, and all possible combinations should be considered to be within the scope described in this specification. Each feature disclosed in the specification can be replaced by any alternative feature that can provide the same, equivalent or similar purpose. Therefore, unless otherwise specifically stated, the disclosed features are only general examples of equivalent or similar features.

[0023] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model; the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0024] Embodiment 1

[0025] A SCR denitration reactor, see Figures 1 - 2, the reactor comprises: a tank body 10, a heating element, a spiral guide plate 20, a spray gun 30, a preheating coil 40, a temperature sensor and a programmable temperature control meter. Among them, a plurality of spray gun mounting openings are arranged at intervals along the axial direction of the tank body 10 on the opposite surfaces of the side wall of the tank body 10, and the spray gun mounting openings on the two surfaces are arranged in a staggered manner. The spray gun 30 is fixed on the spray gun mounting openings and is used for spraying the SCR reaction mixture. By adopting the arrangement of staggered rising and plane symmetry, the situation that multiple spray guns 30 on the same horizontal plane interfere with each other is avoided, and at the same time, the number of openings in the heating and heat preservation layer 11 is reduced, avoiding the excessive complexity of the reactor. A heating and heat preservation layer 11 is provided on the side wall of the tank body 10, and the heating element is embedded in the heating and heat preservation layer 11. The heating element is connected to the programmable temperature control meter through a bus. The programmable temperature control meter controls the current of the heating circuit through a power regulation module to realize the regulation of the heating power, and the resistance wire can realize the rapid heating of the tank body 10. A sewage discharge port 12 is provided at the bottom of the tank body 10 for discharging the solids inside the tank body 10. The top of the tank body 10 is sealed with a tank cover 13, and an exhaust port 14 is provided in the middle or on the side of the tank cover 13 for discharging the gas after denitrification. The spiral guide plate 20 is vertically and detachably fixed in the middle of the inner bottom of the tank body 10. The spiral guide plate 20 spirally rises along the axial direction of the tank body 10. There is a gap between the outer side of the spiral guide plate 20 and the inner wall of the reactor tank body 10. The spiral guide plate 20 can make the gas rise and flow in a spiral manner, extending the residence time of the gas in the tank body 10, increasing the travel of the gas flow by more than 5 times, and greatly improving the reaction time and the denitrification effect. The spiral guide plate 20 is designed to be flexibly removable for convenient cleaning of the deposits. The preheating coil 40 is arranged on one side of the heating and heat preservation layer 11 close to the side wall of the tank body 10, and it includes: a spiral tube and a straight tube. The spiral tube of the preheating coil 40 spirally rises along the axial direction of the tank body 10. One end of the air inlet 41 of the spiral tube passes through the side wall of the tank body 10 and is outside the tank body 10. The air outlet of the spiral tube is communicated with the air inlet of the straight tube, and the air outlet 42 of the straight tube is communicated to the bottom of the tank body 10. The air inlet 41 of the spiral tube is used for introducing the flue gas to be treated, and the air outlet 42 of the straight tube is used for discharging the preheated flue gas. Temperature sensors are arranged at the bottom, middle and upper part of the tank body 10, and are respectively used for monitoring the temperature of the preheated gas at the bottom of the tank body 10, the temperature of the tank body 10 and the temperature of the heating and heat preservation layer 11.

[0026] Exemplarily, the heating element is vertically embedded in the heating and heat preservation layer 11. The resistance wire is wired with two-phase 380V. The programmable temperature control meter adopts a PID temperature control meter, which is usually composed of three parts: proportional (P), integral (I) and derivative (D) controllers. The P controller is responsible for outputting a control signal according to the difference between the target temperature and the actual temperature. The I controller is used to eliminate the cumulative effect of the temperature deviation. The D controller improves the accuracy and stability of the temperature control through the feedback control of the temperature change rate.

[0027] Exemplarily, the gap between the outer side of the spiral deflector 20 and the inner wall of the reactor tank body 10 is as small as possible.

[0028] According to a specific embodiment of the present invention, the tank body 10 and the tank cover 13 are detachably connected, for example, by flange connection, which is convenient for disassembly.

[0029] According to a specific embodiment of the present invention, the flange between the tank body 10 and the tank cover 13 is sealed with graphite packing.

[0030] According to a specific embodiment of the present invention, the materials of the tank body 10, the spiral deflector 20, and the preheating coil 40 are all high-temperature resistant stainless steel, and the material of the heating and insulation layer 11 is inorganic ceramic fiber.

[0031] Exemplarily, the materials of the tank body 10, the spiral deflector 20, and the preheating coil 40 are all high-temperature resistant 310s stainless steel.

[0032] According to a specific embodiment of the present invention, the reactor further includes: a support frame for fixing the tank body 10.

[0033] The usage method and working principle of the SCR denitration reactor of the present invention are specifically as follows:

[0034] During use, first control the heating of the heating element through a programmable temperature control meter to preheat the tank body 10 and the preheating coil 40. After reaching the required reaction temperature conditions (the reaction temperature of SCR is 850 - 1100 o °C), the flue gas to be treated is introduced. The flue gas enters the preheating coil 40 and spirally rises along the preheating coil 40 around the tank body 10. During the rising process, the flue gas is heated. Since the preheating coil 40 spirally rises around the tank body 10, the residence time of the flue gas in the reactor is extended, and the flue gas can be fully heated. When the flue gas rises to the highest point of the spiral pipe, it is diverted down by the straight pipe and enters the bottom of the tank body 10. At this time, the spraying of the SCR reaction mixture is started. The spray guns 30 arranged alternately on the opposite side walls of the tank body 10 can spray the SCR reaction mixture simultaneously on multiple planes at different heights, and the flue gas slowly rises spirally along the spiral deflector 20, so that the sprayed SCR reaction mixture can fully contact and react with the flue gas.

[0035] The SCR reaction mixture is a mixture of a reducing agent and a catalyst raw material solution (such as ammonia water, urea, and a metal salt solution for generating a nano-scale catalyst). Under the condition of ammonia water, the metal salt solution forms hydrates and complexes. At high temperatures, the metal salt in the SCR reaction mixture forms a surface highly active nano-scale metal oxide catalyst. Under the action of the metal oxide catalyst, NO → N2 is rapidly converted, and the conversion rate is extremely high (close to 95%), and it is less affected by dust.

[0036] The catalyst reaction (SCR) in the tank body 10 is: 6NO + 4NH3 = 5N2 + 6H2O, which has a faster reaction rate than 4NO + 4NH3 + O2 = 4N2 + 6H2O, preventing the conversion of NO → NO2. NO2 will consume a large number of activated ammonia molecules (6NO2 + 8NH3 = 7N2 + 12H2O), improving the effective reaction of the reducing agent NH3 and increasing the NO x →N2 conversion rate to achieve denitrification, while reducing the ammonia water usage (volume) by at least 30% and decreasing the ammonia slip value.

[0037] The tail gas after the denitrification reaction of the flue gas to be treated is discharged from the top of the tank body 10 through the exhaust port 14 of the tank cover 13, and the discharged gas can meet the emission standards (NO x <50mg / m 3 and ammonia slip < 10ppm). The solid catalyst after the reaction can be discharged through the blowdown port 12.

[0038] Although the content of the present utility model has been introduced in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation to the present utility model. After those skilled in the art have read the above content, various modifications and substitutions to the present utility model will be obvious. Therefore, the protection scope of the present utility model should be defined by the appended claims.

Claims

1. An SCR denitration reactor, characterized in that: The SCR denitrification reactor comprises: A tank body (10) has a plurality of spray gun mounting openings arranged at intervals on opposite surfaces of the side wall along the axial direction of the tank body (10), and the spray gun mounting openings on the two surfaces are arranged in a staggered manner, a heating and heat-insulating layer (11) is also provided on the side wall, a sewage outlet (12) is provided at the bottom, and a tank cover (13) is sealed at the top, and an exhaust port (14) for discharging denitrification gas is provided in the middle or on the side of the tank cover (13); A heating element, which is embedded in the heating and heat-insulating layer (11) and is used to heat the tank body (10); A spiral guide plate (20) is vertically and detachably fixed in the middle of the bottom of the tank body (10), spirally extending upward along the axial direction of the tank body (10), with a gap between its outer side and the inner wall of the reactor tank body (10); A spray gun (30) fixed to the spray gun mounting port and used for spraying the SCR reaction mixture; A preheating coil (40) is arranged in the heating and heat-insulating layer (11) on a side close to the side wall of the tank body (10), and comprises: a spiral tube and a straight tube, wherein the spiral tube of the preheating coil (40) rises in a spiral shape along the axial direction of the tank body (10), one end of the air inlet (41) of the spiral tube passes through the side wall of the tank body (10) and is located outside the tank body (10), the air outlet of the spiral tube is connected to the air inlet of the straight tube, and the air outlet (42) of the straight tube is connected to the bottom of the tank body (10), the air inlet (41) of the spiral tube is used to introduce the flue gas to be treated, and the air outlet (42) of the straight tube is used to discharge the preheated flue gas; Temperature sensors are arranged at the bottom, middle and top of the tank body (10), and are used to monitor the temperature of the preheating gas at the bottom of the tank body (10), the temperature of the tank body (10) and the temperature of the heating and insulation layer (11); and A programmable temperature control meter is connected to the heating element via a bus and is used to control the temperature regulation of the heating element.

2. The SCR denitration reactor according to claim 1, characterized in that: The tank body (10) and the tank cover (13) are connected in a detachable manner.

3. The SCR denitration reactor according to claim 2, characterized in that: The tank body (10) and the tank cover (13) are connected by flanges.

4. The SCR denitration reactor according to claim 1, characterized in that: A graphite packing seal is provided between the flange of the tank body (10) and the flange of the tank cover (13).

5. The SCR denitration reactor according to claim 1, characterized in that: The reactor further comprises: a support frame, wherein the support frame is used to fix the tank body (10).

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