Denitration reactor and method for flue gas denitration

Abstract

This invention relates to the field of environmental protection technology and discloses a denitrification reactor and a method for flue gas denitrification. The denitrification reactor includes an outer shell and an inner liner. Superheated steam is introduced between the outer shell and the inner liner to heat the inner liner. The inner liner is further divided into a baffled mixing zone and a catalytic reaction zone. The flue gas is first heated to the temperature required for the catalytic reaction in the baffled mixing zone, and then enters the catalytic reaction zone to react. The catalytic reaction zone is always at a high temperature, which prevents the formation of ammonium salts that cover and block the fiber pores of the tube wall during the denitrification process. Furthermore, the heat utilization is more efficient. The three processes of flue gas heating, denitrification reaction, and dust removal can be completed with a single device. It can simply and quickly heat, denitrate, and remove dust from the flue gas to meet emission requirements. The operation is simpler, the denitrification index is stable, and the equipment has a long service life, making it more suitable for industrial applications.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, specifically to a denitrification reactor and a method for flue gas denitrification. Background Technology

[0002] With the continuous development of modern society, people's demand for energy is increasing dramatically. This energy consumption also generates many pollutants, causing varying degrees of harm to ecosystems and organisms. After the implementation of total emission control, nitrogen oxides have become a top priority in air pollution control. Not only are nitrogen oxides monitored, but control targets for particulate matter are also becoming increasingly stringent.

[0003] In recent years, researchers have been continuously exploring technologies to reduce nitrogen oxide emissions, including combustion control and flue gas emission control. Controlling nitrogen oxide formation at its source is considered the most effective method. Currently, methods for controlling nitrogen oxide emissions include adsorption, absorption, oxidative absorption, and catalytic reduction. Among catalytic reduction methods, selective catalytic reduction (SCR) and selective non-catalytic reduction (SNR) are the main processes for reducing nitrogen oxides and are also the most effective methods for eliminating nitrogen oxides in industry.

[0004] In existing technologies, selective non-catalytic reduction (SNR) involves high reaction temperatures, complex processes, and high consumption of reducing agents, thus it is not widely used. Selective catalytic reduction (SCR), on the other hand, is widely used for nitrogen oxide (NOx) removal due to its lower reaction temperatures and simpler operation. However, this technology is more suitable for clean flue gas. For flue gas with high dust content, dust adheres to the catalyst surface, causing catalyst deactivation. Therefore, a flue gas dust removal facility is often required before NOx removal. Furthermore, SCR has strict temperature requirements; regardless of whether a medium-low or medium-high temperature catalyst is used, the flue gas needs to be preheated to a specified temperature. This necessitates both a pre-dust removal facility and a pre-heating facility, making the equipment complex. Currently, many industrial plants face the predicament of NOx and particulate matter content in their exhaust gases failing to meet standards, urgently requiring a simpler and more efficient equipment that can achieve both NOx removal and dust removal. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of existing technologies, such as the inability to simultaneously achieve denitrification and dust removal in a single device, complex processes, and catalyst deactivation caused by dust. This invention provides a denitrification reactor and a method for flue gas denitrification. The denitrification reactor has two parts: an outer shell and an inner liner. Superheated steam is introduced through the gap between the two parts, keeping the reaction zone in the inner liner at a high temperature, thus maximizing heat utilization. A single device can complete the three processes of flue gas heating, denitrification reaction, and dust removal. This allows for simple and rapid heating, denitrification, and dust removal of flue gas, ensuring compliance with emission requirements. The operation is simpler, the denitrification performance is stable, and it is more suitable for industrial applications.

[0006] To achieve the above objectives, the present invention provides a denitrification reactor comprising an outer shell and an inner liner. The outer shell is arranged around the outer periphery of the inner liner to form an annular heating zone. The lower end of the inner liner is provided with a flue gas inlet, and the upper end is provided with a flue gas outlet. The inner cavity of the inner liner is arranged from bottom to top as a baffle mixing zone and a catalytic reaction zone. The baffle mixing zone is provided with a plurality of baffles, and the catalytic reaction zone is provided with one or more layers of fiber reaction tubes. Flue gas enters the tube from the outer wall of the fiber reaction tube and reacts with the sulfur-resistant denitrification catalyst inside the tube. The reacted flue gas is output from the top of the fiber reaction tube.

[0007] Preferably, the denitrification reactor further includes a flue gas inlet pipe connected to the flue gas inlet, and the flue gas inlet pipe is equipped with a spray device for spraying in a reducing agent.

[0008] Preferably, the spraying direction of the spraying device is opposite to the flow direction of the flue gas in the flue gas inlet pipe, so that the reducing agent sprayed through the spraying device mixes with the flue gas in a countercurrent manner.

[0009] Preferably, in each layer of fiber reaction tubes, a plurality of fiber reaction tubes are disposed within the inner liner via a reaction tube distributor.

[0010] Preferably, the catalytic reaction zone is provided with 1-3 layers of fiber reaction tubes.

[0011] Preferably, the number of baffles in the flow mixing zone is 3-6.

[0012] Preferably, the upper part of the outer casing is provided with a steam inlet, and the lower part is provided with a steam outlet.

[0013] Preferably, there are 3 to 10 steam inlets, which are arranged around the upper part of the housing.

[0014] Preferably, each steam inlet is provided with a steam nozzle, and the spray angle of the steam nozzle is 90-150°.

[0015] Preferably, the outer shell is made of thermal insulation material.

[0016] A second aspect of the present invention provides a method for flue gas denitrification, wherein the method uses the denitrification reactor described above to treat the flue gas for denitrification. The method includes: injecting a mixture containing flue gas and a reducing agent into the inner cavity of the inner liner through the flue gas inlet, further mixing the mixture containing flue gas and a reducing agent in the baffle mixing zone and adjusting the temperature to 180°C or above, and then entering the catalytic reaction zone for denitrification reaction, and discharging the reacted flue gas through the flue gas outlet.

[0017] Preferably, the temperature is adjusted as follows: when the initial temperature of the flue gas is below 180°C, superheated steam is introduced into the annular gap heating zone to heat the material inside the inner liner; when the initial temperature of the flue gas is above 180°C, superheated steam is not introduced into the annular gap heating zone.

[0018] Preferably, the concentration of nitrogen oxides in the flue gas is 80-200 mg / m³. 3 The concentration of particulate matter is 20-50 mg / m³. 3 .

[0019] Preferably, the flow rate of the flue gas is 5000-10000 m³ / h. 3 / h.

[0020] Preferably, the reducing agent is at least one of ammonia, urea, liquid ammonia, and ammonia water.

[0021] Preferably, the molar ratio of nitrogen in the reducing agent to the molar ratio of nitrogen in the flue gas is (1-2):1.

[0022] Preferably, the temperature of the superheated steam is 230-400°C.

[0023] Through the above technical solution, superheated steam is introduced between the outer shell and the inner liner of the denitrification reactor to heat the inner liner. The inner liner is divided into two parts: a baffle mixing zone and a catalytic reaction zone. The flue gas is first further mixed and heated to the temperature required for the denitrification reaction in the baffle mixing zone, and then enters the catalytic reaction zone to react. The catalytic reaction zone is always in a high-temperature zone, which will not form ammonium salts to cover and block the fiber pores of the tube wall during the denitrification process. Moreover, the heat utilization is more efficient. The three processes of flue gas heating, flue gas denitrification reaction and flue gas dust removal can be completed by one device. It can simply and quickly heat, denitrate, and remove dust from the flue gas to meet the emission requirements. The operation is simpler, the denitrification index is stable, and the equipment has a long service life, making it more suitable for industrial applications. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the internal structure of the denitrification reactor described in this invention;

[0025] Figure 2 This is a top view of the internal structure of the denitrification reactor described in this invention;

[0026] Figure 3 This is a schematic flowchart of the flue gas denitrification method described in this invention.

[0027] Explanation of reference numerals in the attached figures

[0028] 1. Outer shell; 2. Inner liner; 3. Baffle plate; 4. Fiber reaction tube; 5. Reaction tube distributor; 6. Steam inlet; 7. Annular gap heating zone; 8. Baffle mixing zone; 9. Nozzle; 10. Flue gas inlet; 11. Flue gas outlet; 12. Steam outlet; 13. Spray device; 14. Reducing agent regulating valve; 15. Steam regulating valve. Detailed Implementation

[0029] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0030] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0031] In the description of this application, terms such as “center,” “horizontal,” “up,” “down,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer” that indicate orientation or positional relationship are based on the orientation or relative positional relationship shown in the accompanying drawings. They are only for the purpose of simplifying the description of this application and do not indicate that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0032] Furthermore, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0033] like Figure 1 and 2 As shown, the denitrification reactor of the present invention includes an outer shell 1 and an inner liner 2. The outer shell 1 is arranged around the outer periphery of the inner liner 2 to form an annular heating zone 7. The lower end of the inner liner 2 is provided with a flue gas inlet 10 and the upper end is provided with a flue gas outlet 11. The inner cavity of the inner liner 2 is arranged from bottom to top as a baffle mixing zone 8 and a catalytic reaction zone. The baffle mixing zone 8 is provided with a plurality of baffle plates 3. The catalytic reaction zone is provided with one or more layers of fiber reaction tubes 4. Flue gas enters the tube from the outer wall of the fiber reaction tube 4 and reacts with the sulfur-resistant denitrification catalyst inside the tube. The reacted flue gas is output from the top of the fiber reaction tube 4. The denitrification reactor of this invention heats the inner liner by introducing superheated steam between the outer shell and the inner liner. The inner liner is divided into two parts: a baffle mixing zone 8 and a catalytic reaction zone. This allows the flue gas to be further mixed and heated to the temperature required for the denitrification reaction in the baffle mixing zone 8 before entering the catalytic reaction zone to react. This fully utilizes the heat and makes it simpler and faster to heat, denitrify, and remove dust from the flue gas to meet emission requirements.

[0034] In a preferred embodiment, the denitrification reactor of the present invention further includes a flue gas inlet pipe connected to the flue gas inlet, and the flue gas inlet pipe is provided with a spray device 13 for spraying a reducing agent.

[0035] More preferably, the spraying direction of the spray device 13 is opposite to the flow direction of the flue gas in the flue gas inlet duct, so that the reducing agent sprayed through the spray device 13 mixes countercurrently with the flue gas. This countercurrent mixing allows the flue gas and reducing agent to mix thoroughly in the flue gas inlet duct, resulting in a better effect for the subsequent catalytic reaction.

[0036] In the denitrification reactor of the present invention, in each layer of fiber reaction tubes 4, a plurality of fiber reaction tubes are disposed in the inner liner 2 through a reaction tube distributor 5.

[0037] In the denitrification reactor of the present invention, 1-3 layers of fiber reaction tubes 4 are arranged in the catalytic reaction zone. The reaction tube distributor 5 has openings arranged according to the outer diameter of the fiber reaction tubes 4, and the arrangement can be an equilateral triangle or a grid pattern. In one specific embodiment, the length of the fiber reaction tubes 4 is 1-4 meters, and they are evenly distributed on the reaction tube distributor 5.

[0038] In the denitrification reactor of the present invention, the number of baffles 3 in the baffle mixing zone 8 is 3-6. By configuring the baffles 3, on the one hand, the turbulent mixing of the flue gas and the reducing agent can be enhanced, and on the other hand, the residence time of the flue gas can be extended, so that the flue gas and the reducing agent mixture entering the baffle mixing zone 8 can be further fully mixed. Furthermore, by controlling the injection of superheated steam in the annular heating zone 7, the temperature of the flue gas can be adjusted to the temperature required for the denitrification reaction, and the denitrification reaction will subsequently occur in the catalytic reaction zone.

[0039] In the denitrification reactor of the present invention, a steam inlet 6 is provided at the upper part of the outer shell 1, and a steam outlet 12 is provided at the lower part. Preferably, there are 3-10 steam inlets 6, which are arranged around the upper part of the outer shell 1. More preferably, each steam inlet 6 is provided with a steam nozzle 9, and the spray angle of the steam nozzle 9 is 90-150°.

[0040] In the denitrification reactor described in this invention, the height of the steam inlet 6 on the outer shell 1 is above the reaction tube distributor 5 of the highest layer of the inner liner 2. Superheated steam can be injected into the annular heating zone 7 at 90-150° through the steam nozzle 9. After heat exchange, the steam (i.e., the cooled steam) is discharged from the steam outlet 12 at the lower end. This ensures that all fiber reaction tubes 4 are at high temperature, which can improve the effect of catalytic denitrification reaction on the one hand, and prevent the flue gas from forming ammonium salts that cover and block the fiber pores of the tube wall during the denitrification reaction. This makes the equipment last longer, more stable and more efficient.

[0041] In the denitrification reactor described in this invention, the outer shell 1 is made of thermal insulation material. Using thermal insulation material to insulate the entire outer shell of the equipment allows for higher heat utilization of the superheated steam.

[0042] The internal structure of the denitrification reactor described in this invention is as follows: Figure 1As shown, in some embodiments, the denitrification reactor comprises an outer shell 1 and an inner liner 2. A flue gas outlet 11 is provided at the top of the inner liner 2, and a flue gas inlet 10 is provided at the bottom. The flue gas enters the inner liner 2 from bottom to top, first passing through a baffle mixing zone 8. The baffle mixing zone 8 is distributed with 3-6 baffles 3. The baffles 3 prolong the residence time of the flue gas in the baffle mixing zone 8, thereby raising the temperature to the temperature required for the denitrification reaction. Then it rises to the catalytic reaction zone, in which 1-3 layers of fiber reaction tubes 4 are distributed. Each layer of fiber reaction tubes 4 is evenly distributed and fixed on the reaction tube distributor 5. Above, the heated flue gas enters the fiber reaction tube 4 from the outer wall and reacts with the sulfur-resistant denitrification catalyst inside the tube. The reacted flue gas is output from the top of the fiber reaction tube 4 and finally discharged through the flue gas outlet 11 at the top of the inner liner 2. In the outer shell 1, 3-10 steam inlets 6 are arranged around the upper end of the outer shell 1, and the height of the steam inlets 6 is higher than the uppermost reaction tube distributor 5 in the inner liner 2. A steam outlet 12 is provided at the lower end of the outer shell 1. The gap between the outer shell 1 and the inner liner 2 is an annular heating zone 7, and the diameter of the annular heating zone 7 is greater than 250mm.

[0043] The internal top view structure of the denitrification reactor described in this invention is as follows: Figure 2 As shown, 3-10 steam inlets 6 are arranged around the outer shell 1 of the denitrification reactor, and each steam inlet 6 is equipped with a steam nozzle 9, and the spray angle of the steam nozzle 9 is 90-150°.

[0044] According to the flue gas denitrification method of the present invention, the denitrification reactor described above is used to treat the flue gas for denitrification. The method specifically includes: injecting a mixture containing flue gas and a reducing agent into the inner cavity of the inner liner 2 through the flue gas inlet; further mixing the mixture in the baffled mixing zone 8 and adjusting the temperature to 180°C or higher; then entering the catalytic reaction zone for denitrification reaction; and finally discharging the reacted flue gas through the flue gas outlet. The method described in this invention can not only denitrify nitrogen oxides in flue gas and reduce particulate matter, but also has a certain reduction effect on sulfur dioxide.

[0045] In the method described in this invention, the temperature is adjusted as follows: when the initial temperature of the flue gas is below 180°C, superheated steam is introduced into the annular gap heating zone 7 to heat the material inside the inner liner 2; when the initial temperature of the flue gas is above 180°C, superheated steam is not introduced into the annular gap heating zone 7.

[0046] In the method described in this invention, the concentration of nitrogen oxides in the flue gas can be 80-200 mg / m³. 3 The concentration of particulate matter can be 20-50 mg / m³. 3After flue gas denitrification using the method described in this invention, the denitrification efficiency of the discharged flue gas can reach over 80%, and the concentration of particulate matter in the denitrified flue gas is below 5 mg / m³. 3 The concentration of nitrogen oxides is less than 15 mg / m³. 3 .

[0047] In the method described in this invention, the flow rate of the flue gas is 5000-10000 m³ / h. 3 / h. Controlling the flue gas flow rate can maximize the efficiency of this method. When the flue gas flow rate is too low, it will cause energy loss and low heat utilization efficiency; when the flue gas flow rate is too high, it will affect the final flue gas denitrification efficiency and the catalytic reaction will be incomplete.

[0048] In the method described in this invention, the reducing agent can be a nitrogen-containing reducing agent commonly used in the art, preferably at least one of ammonia, urea, liquid ammonia, and ammonia water.

[0049] In the method described in this invention, the molar ratio of nitrogen in the reducing agent to nitrogen in the flue gas can be (1-2):1, preferably (1.2-1.5):1.

[0050] In the method described in this invention, the sulfur-resistant denitrification catalyst in the fiber reaction tube 4 can be a sulfur-resistant denitrification catalyst commonly used in the art, preferably at least one of medium-low temperature sulfur-resistant denitrification catalyst and medium-high temperature denitrification catalyst.

[0051] In the method described in this invention, the temperature of the superheated steam is 230-400℃. Using superheated steam for counter-current heat exchange with flue gas is more environmentally friendly and safer.

[0052] In the method described in this invention, the flue gas denitrification process is as follows: Figure 3 As shown, the reducing agent regulating valve 14 is opened, and the reducing agent is introduced into the flue gas pipeline in a countercurrent flow using the spray device 13, so that the flue gas and reducing agent achieve a homogeneous distribution in the pipeline. Then, it is introduced into the flue gas through the lower flue gas inlet 10 of the aforementioned denitrification reactor and completes a series of processes including heating, denitrification, and dust removal within the denitrification reactor, and then discharged from the upper flue gas outlet 11. The heating process includes: when the initial temperature of the flue gas is below 180°C, the steam regulating valve 15 is opened, and superheated steam at a temperature of 230-400°C is introduced into the steam inlet 6 above the outer shell 1 of the denitrification reactor. After countercurrent heat exchange with the flue gas, it is discharged from the steam outlet below the outer shell 1; when the initial temperature of the flue gas is above 180°C, the steam regulating valve 15 is closed.

[0053] In the method described in this invention, the length of the pipe is not less than 8m, preferably 8-10m.

[0054] In a specific implementation, the flue gas denitrification method is as follows: The reducing agent regulating valve 14 is opened, and the reducing agent is introduced into the flue gas pipeline in reverse flow using the spray device 13, so that the flue gas and reducing agent achieve a homogeneous distribution in the pipeline. Then, the flue gas is introduced from the lower flue gas inlet 10 of the inner liner 2 of the denitrification reactor. The flue gas first passes through the baffle mixing zone 8, in which 3-6 baffles 3 are distributed. The baffles 3 prolong the residence time of the flue gas in the baffle mixing zone 8, thereby raising the temperature to the temperature required for the catalytic reaction. The flue gas then moves upward to the catalytic reaction zone, in which 1-3 layers of fiber reaction tubes 4 are distributed. Each layer of fiber reaction tubes 4 is evenly distributed and fixed in the reaction tube distribution. In the reactor 5, the heated flue gas enters the fiber reaction tube 4 from the outer wall and reacts with the sulfur-resistant denitrification catalyst inside the tube. The reacted flue gas is then discharged from the top of the fiber reaction tube 4 and finally exits through the flue gas outlet 11 at the top of the inner liner 2. Simultaneously, when the initial temperature of the flue gas is below 180°C, the steam regulating valve 15 is opened, and superheated steam at a temperature of 230-400°C is introduced from the steam inlet 6 above the outer shell 1 of the denitrification reactor into the annular heating zone 7. After countercurrent heat exchange with the flue gas, the steam is discharged from the steam outlet below the outer shell 1. When the initial temperature of the flue gas is above 180°C, the steam regulating valve 15 is closed.

[0055] The following examples further illustrate the denitrification reactor and flue gas denitrification method of the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0056] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0057] In the following embodiments, the denitrification reactor is configured as follows: The denitrification reactor comprises an outer shell 1 and an inner liner 2. A flue gas outlet 11 is provided at the top of the inner liner 2, and a flue gas inlet 10 is provided at the bottom. Below the inner liner 2 is a baffle mixing zone 8, in which 3-6 baffle plates 3 are distributed. Above the baffle is a catalytic reaction zone, in which 1-3 layers of fiber reaction tubes 4 are distributed. Each layer of fiber reaction tubes 4 is evenly distributed and fixed on a reaction tube distributor 5. In the outer shell 1, 3-10 steam inlets 6 are arranged around the upper end of the outer shell 1, and the height of the steam inlets 6 is higher than the uppermost reaction tube distributor 5 in the inner liner 2. A steam outlet 12 is provided at the lower end of the outer shell 1, and the gap between the outer shell 1 and the inner liner 2 is an annular heating zone 7.

[0058] Example 1

[0059] The flue gas flow rate used in this embodiment is 7000 m³ / h. 3 / h, temperature 40℃, nitrogen oxide concentration in flue gas 90mg / m³ 3 The particulate matter concentration was 30 mg / m³. 3 .

[0060] Open the reducing agent regulating valve 14, and use the spray device 13 to reverse-flow ammonia gas with a concentration of 0.0252 mol / h into an 8-m long flue gas pipe, so that the flue gas and ammonia gas are homogeneously distributed in the pipe. Then, it is introduced from the flue gas inlet 10 below the inner liner 2 of the denitrification reactor. The flue gas first passes through the baffle mixing zone 8, which has 3 baffles 3. The baffles 3 prolong the residence time of the flue gas in the baffle mixing zone 8, thereby raising the temperature to 180°C. Then it goes up to the catalytic reaction zone, which has a layer of 4-meter-long fiber reaction tubes. 4. The heated flue gas enters the fiber reaction tube 4 from the outer wall and reacts with the sulfur-resistant denitrification catalyst inside the tube. The reacted flue gas exits from the top of the fiber reaction tube 4 and is finally discharged through the flue gas outlet 11 at the top of the inner liner 2. Simultaneously, the steam regulating valve 15 is opened, and superheated steam at 350°C is introduced into the annular heating zone 7 at an angle of 110° through the six steam inlets 6 above the outer shell 1 of the denitrification reactor. After countercurrent heat exchange with the flue gas, the steam temperature drops to 250°C and is discharged from the steam outlet below the outer shell 1. The temperature of the flue gas exiting the denitrification reactor after the reaction is 220°C, and the nitrogen oxide concentration is <15mg / m³. 3 Particulate matter concentration <5mg / m³ 3 The denitrification efficiency is shown in Table 1.

[0061] Example 2

[0062] The flow rate of the flue gas used in this embodiment is 10000 m³ / h. 3 / h, temperature is 120℃, nitrogen oxide concentration in flue gas is 200mg / m³ 3 The particulate matter concentration was 30 mg / m³. 3 .

[0063] Open the reducing agent regulating valve 14, and use the spray device 13 to reverse-flow ammonia gas with a concentration of 0.08 mol / h into the 9m long flue gas pipe, so that the flue gas and ammonia gas are homogeneously distributed in the pipe. Then, it is introduced from the flue gas inlet 10 below the inner liner 2 of the denitrification reactor. The flue gas first passes through the baffle mixing zone 8, which has 5 baffles 3. The baffles 3 prolong the residence time of the flue gas in the baffle mixing zone 8, thereby raising the temperature to 180°C. Then it goes up to the catalytic reaction zone, which has two layers of 2.5m long fiber reaction tubes. 4. The heated flue gas enters the fiber reaction tube 4 from the outer wall and reacts with the sulfur-resistant denitrification catalyst inside the tube. The reacted flue gas exits from the top of the fiber reaction tube 4 and is finally discharged through the flue gas outlet 11 at the top of the inner liner 2. Simultaneously, the steam regulating valve 15 is opened, and superheated steam at 300°C is introduced into the annular heating zone 7 at an angle of 120° through the eight steam inlets 6 above the outer shell 1 of the denitrification reactor. After countercurrent heat exchange with the flue gas, the steam temperature drops to 240°C and is discharged from the steam outlet below the outer shell 1. The temperature of the flue gas exiting the denitrification reactor after the reaction is 220°C, and the nitrogen oxide concentration is <20mg / m³. 3 Particulate matter concentration <5mg / m³ 3 The denitrification efficiency is shown in Table 1.

[0064] Example 3

[0065] The flue gas flow rate used in this embodiment is 5000 m³ / h. 3 / h, temperature is 200℃, nitrogen oxide concentration in flue gas is 80mg / m³ 3 The particulate matter concentration was 50 mg / m³. 3 The sulfur-resistant denitrification catalyst used is...

[0066] Open the reducing agent regulating valve 14, and use the spray device 13 to backflow urea at a concentration of 0.01 mol / h into a 10m long flue gas pipe, so that the flue gas and ammonia are homogeneously distributed in the pipe. Then, it is introduced from the flue gas inlet 10 at the bottom of the inner liner 2 of the denitrification reactor. The flue gas first passes through the baffle mixing zone 8, which has 6 baffles 3, and then rises to the catalytic reaction zone, which has three layers of 2-meter-long fiber reaction tubes 4. The heated flue gas enters the pipe from the outer wall of the fiber reaction tube 4 and reacts with the sulfur-resistant denitrification catalyst inside the pipe. The reacted flue gas is output from the top of the fiber reaction tube 4 and finally discharged through the flue gas outlet 11 at the top of the inner liner 2. The temperature of the flue gas exiting the denitrification reactor after the reaction is 190℃, and the nitrogen oxide concentration is <15mg / m³. 3 Particulate matter concentration <10mg / m³ 3 The denitrification efficiency is shown in Table 1.

[0067] Comparative Example 1

[0068] The flue gas denitrification reaction was carried out according to the method of Example 1, except that the denitrification reactor used did not have the annular heating zone 7, the baffle mixing zone 8, and the baffle plate 3, and superheated steam was not introduced. The temperature of the flue gas exiting the denitrification reactor after the reaction was 35°C, and the nitrogen oxide concentration was 85 mg / m³. 3 Particulate matter concentration 20 mg / m³ 3 The denitrification efficiency is shown in Table 1.

[0069] Table 1

[0070]

[0071] As can be seen from the results in Table 1, the denitrification efficiency of the denitrification reactor of this invention is significantly higher. Specifically, the denitrification efficiency and dust removal efficiency of the denitrification reactor of this invention can reach more than 80% simultaneously. This invention introduces superheated steam between the outer shell and the inner liner of the denitrification reactor to heat the inner liner. The inner liner is divided into a baffle mixing zone and a catalytic reaction zone. This allows the introduced flue gas to be heated to the temperature required for the catalytic reaction in the baffle mixing zone before entering the catalytic reaction zone to react. The catalytic reaction zone is always in a high-temperature zone, which makes the heat utilization more efficient and prevents the formation of ammonium salts that cover and block the fiber pores of the tube wall during the denitrification process. The three processes of flue gas heating, denitrification reaction and dust removal can be completed with only one device, which is simpler and faster, and the denitrification index is stable, making it more suitable for industrial applications.

[0072] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A denitrification reactor, characterized in that, The device includes an outer shell (1) and an inner liner (2). The outer shell (1) surrounds the outer periphery of the inner liner (2) and forms an annular heating zone (7). The lower end of the inner liner (2) is provided with a flue gas inlet (10) and the upper end is provided with a flue gas outlet (11). The inner cavity of the inner liner (2) is arranged from bottom to top as a baffle mixing zone (8) and a catalytic reaction zone. The baffle mixing zone (8) is provided with several baffle plates (3). The catalytic reaction zone is provided with one or more layers of fiber reaction tubes (4). The flue gas enters the tube from the outer wall of the fiber reaction tube (4) and reacts with the sulfur-resistant denitrification catalyst inside the tube. The flue gas after the reaction is output from the top of the fiber reaction tube (4).

2. The denitrification reactor according to claim 1, characterized in that, The denitrification reactor also includes a flue gas inlet pipe connected to the flue gas inlet, and the flue gas inlet pipe is equipped with a spray device (13) for spraying in a reducing agent; Preferably, the spraying direction of the spraying device (13) is opposite to the flow direction of the flue gas in the flue gas inlet pipe, so that the reducing agent sprayed through the spraying device (13) mixes with the flue gas in a countercurrent manner.

3. The denitrification reactor according to claim 1 or 2, characterized in that, In each layer of fiber reaction tubes (4), several fiber reaction tubes are arranged in the inner liner (2) through a reaction tube distributor (5).

4. The denitrification reactor according to any one of claims 1-3, characterized in that, The catalytic reaction zone is provided with 1-3 layers of fiber reaction tubes (4).

5. The denitrification reactor according to any one of claims 1-3, characterized in that, In the flow mixing zone (8), the number of baffles (3) is 3-6.

6. The denitrification reactor according to any one of claims 1-5, characterized in that, The upper part of the outer shell (1) is provided with a steam inlet (6), and the lower part is provided with a steam outlet (12); Preferably, the number of steam inlets (6) is 3-10, and these steam inlets are arranged around the upper part of the outer casing (1); Preferably, each steam inlet (6) is provided with a steam nozzle (9), and the spray angle of the steam nozzle (9) is 90-150°.

7. The denitrification reactor according to any one of claims 1-6, characterized in that, The outer shell (1) is made of thermal insulation material.

8. A method for flue gas denitrification, characterized in that, The denitrification reactor according to any one of claims 1-7 is used to denitrify the flue gas. The method includes: injecting a mixture containing flue gas and a reducing agent into the inner cavity of the inner liner (2) through the flue gas inlet, further mixing the mixture containing flue gas and a reducing agent in the baffle mixing zone (8) and adjusting the temperature to 180°C or above, and then entering the catalytic reaction zone for denitrification reaction, and the flue gas after reaction is discharged through the flue gas outlet; The temperature adjustment method is as follows: when the initial temperature of the flue gas is lower than 180°C, superheated steam is introduced into the annular gap heating zone (7) to heat the material in the inner liner (2); when the initial temperature of the flue gas is higher than 180°C, superheated steam is not introduced into the annular gap heating zone (7).

9. The method according to claim 8, characterized in that, In the flue gas, the concentration of nitrogen oxides is 80-200 mg / m 3 , and the concentration of particulate matter is 20-50 mg / m 3 ; Preferably, the flow rate of the flue gas is 5000-10000 m³ / h. 3 / h.

10. The method according to claim 8 or 9, characterized in that, The reducing agent is at least one of ammonia gas, urea, liquid ammonia, and ammonia water; Preferably, the molar ratio of nitrogen in the reducing agent to the molar ratio of nitrogen in the flue gas is (1-2):

1.

11. The method according to any one of claims 8-10, characterized in that, The temperature of the superheated steam is 230-400℃.

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