Tail gas treatment process

Abstract

The invention discloses a tail gas treatment process which comprises the following steps: introducing nitrogen oxide-containing tail gas into an oxidation absorption tower body, introducing a hydrogen peroxide oxidation liquid into an oxidation filler unit, introducing a urea absorption liquid into an absorption filler unit, and treating the nitrogen oxide-containing tail gas through the oxidation filler unit, tail gas containing nitrogen oxide is treated by the absorption filler unit and is discharged from an outlet of the oxidation absorption tower body; and introducing into a molecular sieve adsorption and desorption device to adsorb nitrogen oxides, and introducing into a tail gas treatment device to obtain discharged tail gas. The tail gas treatment process realizes safe, efficient, stable and continuous treatment of nitrogen oxide-containing tail gas, improves the removal rate of nitrogen oxide, realizes the dual-carbon target of green and low emission, and combines oxidation absorption and molecular sieve adsorption technologies. In the oxidation absorption tower, nitrogen oxides are gradually oxidized and absorbed under the circulating action of an oxidation filler unit and an absorption filler unit.

Description

Technical Field

[0001] This invention belongs to the field of chemical treatment technology, specifically relating to a process for treating exhaust gas. Background Technology

[0002] Nitrogen oxides (NOx) are a class of compounds formed by the reaction of nitrogen and oxygen, including nitric oxide (NO), nitrogen dioxide (NO2), and nitrogen oxides (N2O). The presence of these compounds in the atmosphere has adverse effects on humans and the natural environment, such as acid rain, photochemical smog, and ozone layer depletion. Therefore, the control of nitrogen oxides has become an important part of environmental protection and a crucial link in industrial production. Currently, selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) are widely used in the field of nitrogen oxide absorption. However, both reactions occur in the gas phase. SCR suffers from high investment and operating costs, insufficient catalyst activity and lifespan, and high price; SNCR suffers from incomplete NH3 reaction leading to "ammonia breakthrough," and incomplete NOx reduction producing toxic N2O. Before 1990, Hydro, a company at its nitric acid phosphate fertilizer plant in Borsgren, Norway, used urea solution to remove NOx from the tail gas of its atmospheric nitric acid unit, while simultaneously slowing down the formation of nitrogen oxides. In urea, some of the nitrogen is converted into ammonium nitrate, and the remainder is converted into nitrogen gas. The urea absorption-decomposition-reduction method is a purely consumable waste gas treatment method. After absorption, the waste liquid can be reused after replenishing with urea solution, without producing polluted wastewater and causing secondary pollution. It avoids the problems of acidic water pollution, numerous side reactions, and difficult-to-recover byproducts associated with traditional processes such as water washing, alkaline absorption, and selective catalytic ammonia reduction. Therefore, it is more in line with environmental protection requirements, and the use of urea in controlling NOx emissions is constantly increasing. However, for low concentrations of nitrogen oxides (<5000 mg / m³)... 3 Urea absorption is ineffective, and with increasingly stringent nitrogen oxide emission standards, primary treatment is unlikely to meet emission standards. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a process for treating exhaust gas, thereby achieving safe, efficient, stable and continuous treatment of nitrogen oxide exhaust gas, improving the removal rate of nitrogen oxides and achieving the "dual carbon" goal of green and low emissions.

[0004] The technical solution adopted to solve the technical problem of this invention is to provide a process for treating exhaust gas, including the following steps:

[0005] The oxidation absorption tower includes an oxidation absorption tower body, an oxidation packing unit, and an absorption packing unit. The oxidation packing unit and the absorption packing unit are disposed within the oxidation absorption tower body. The oxidation absorption tower body includes an oxidation absorption tower body inlet and an oxidation absorption tower body outlet. Nitrogen oxide-containing tail gas is introduced into the oxidation absorption tower body through the oxidation absorption tower body inlet. The nitrogen oxide-containing tail gas contains nitrogen oxides. Hydrogen peroxide oxidizing solution is introduced into the oxidation packing unit, and urea absorbent solution is introduced into the absorption packing unit. The nitrogen oxide-containing tail gas is treated by hydrogen peroxide oxidizing solution through the oxidation packing unit and by urea absorbent solution through the absorption packing unit. The treated nitrogen oxide-containing tail gas is discharged from the oxidation absorption tower body outlet.

[0006] The treated nitrogen oxide-containing exhaust gas is passed into a molecular sieve adsorption and desorption device to adsorb nitrogen oxides through molecular sieves, and then enters the exhaust gas treatment device to obtain the exhaust gas to be emitted.

[0007] The exhaust gas treatment device is a packed tower, the same size as the oxidation absorption tower, and contains a 10% sodium hydroxide solution.

[0008] Preferably, the oxidation packing unit is at least two-stage oxidation packing units, and the absorption packing unit is at least two-stage absorption packing units, and the number of oxidation packing units and absorption packing units is the same. Each oxidation packing unit and each absorption packing unit are arranged alternately along the axial direction of the oxidation absorption tower body.

[0009] Preferably, the oxidation absorption tower further includes an oxidation liquid centrifugal pump, which is located outside the oxidation absorption tower. All oxidation packing units are connected in sequence, and the oxidation liquid centrifugal pump is connected to two oxidation packing units at both ends respectively.

[0010] Preferably, the oxidation absorption tower also includes an absorbent centrifugal pump, which is located outside the oxidation absorption tower. All the absorption packing units are connected in sequence, and the absorbent centrifugal pump is connected to two absorption packing units at both ends.

[0011] Preferably, the exhaust gas treatment process further includes the following steps:

[0012] The nitrogen oxide-containing tail gas adsorbed by the molecular sieve adsorption and desorption device is desorbed and desorbed, and the desorbed nitrogen oxide-containing tail gas is then fed into the oxidation absorption tower for further treatment.

[0013] Preferably, the desorption pressure of the molecular sieve adsorption and desorption device is 5-12 kPa.

[0014] Preferably, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa.

[0015] Preferably, the composition of the urea absorption solution includes:

[0016] The weight percentage of CO(NH2)2 is 5%-25%, the weight percentage of HNO3 is 0-1%, and the balance is water.

[0017] Preferably, the composition of the urea absorption solution includes:

[0018] The weight percentage of CO(NH2)2 is 5%-25%, the weight percentage of HNO3 is 0.1-1%, and the balance is water.

[0019] Preferably, the composition of the urea absorbent includes: 20% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water.

[0020] Preferably, the hydrogen peroxide oxidizing solution comprises:

[0021] The weight percentage of H2O2 is 5%-15%, with the balance being water.

[0022] Preferably, the hydrogen peroxide oxidizing solution comprises:

[0023] The weight percentage of H2O2 is 1%, with the remainder being water.

[0024] Preferably, the circulation rate of the hydrogen peroxide oxidizing solution is 0.9-2.2 m³ / h. 3 / h.

[0025] Preferably, the circulation rate of the hydrogen peroxide oxidizing solution is 2.2 m³. 3 / h.

[0026] Preferably, the circulation rate of the urea absorption solution is 0.9-2.2 m³. 3 / h.

[0027] Preferably, the circulation volume of the urea absorption solution is 2.2 m³. 3 / h.

[0028] Preferably, the inlet flow rate of nitrogen oxide-containing tail gas into the oxidation absorption tower is 4-24 L / min.

[0029] Preferably, the residence time of the nitrogen oxide-containing exhaust gas in the oxidation absorption tower is 10s-30s.

[0030] Preferably, the residence time of the nitrogen oxide-containing exhaust gas in the oxidation absorption tower is 30 seconds.

[0031] Preferably, the exhaust gas treatment process further includes the following steps:

[0032] Before the nitrogen oxide-containing tail gas is introduced into the oxidation absorption tower, the nitrogen oxide-containing tail gas is heated to 40-50℃.

[0033] Preferably, the exhaust gas treatment process further includes the following step: when the nitrogen oxide-containing exhaust gas is introduced into the oxidation absorption tower, air is introduced into the oxidation absorption tower.

[0034] Preferably, the concentration of nitrogen oxides in the nitrogen oxide-containing exhaust gas after mixing with air is 5000-20000 mg / m³. 3 .

[0035] Preferably, the concentration of nitrogen oxides in the nitrogen oxide-containing exhaust gas is 16000 mg / m³. 3 .

[0036] Preferably, the air flow rate introduced into the oxidation absorption tower is 90–180 Nm³. 3 / h.

[0037] Preferably, the air flow rate introduced into the oxidation absorption tower is 90 Nm³. 3 / h.

[0038] Preferably, the packing material of the oxidation absorption tower is DN25 or DN16.

[0039] Preferably, the packing material of the oxidation absorption tower is DN16.

[0040] The exhaust gas treatment process in this invention achieves safe, efficient, stable, and continuous treatment of nitrogen oxide-containing exhaust gas, improving the nitrogen oxide removal rate and realizing the "dual carbon" goal of green and low emissions. It combines oxidation absorption and molecular sieve adsorption technologies. In the oxidation absorption tower, the oxidation and absorption packing units work in a cycle to progressively oxidize and absorb nitrogen oxides. Compared to traditional single-treatment methods, this approach can more comprehensively address nitrogen oxides in different states, significantly improving nitrogen oxide removal efficiency. The molecular sieve adsorption and desorption device further adsorbs the gas after treatment in the oxidation absorption tower, capturing nitrogen oxides that were not completely removed during the oxidation absorption process, achieving deep purification and ensuring an overall extremely high nitrogen oxide removal rate. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the exhaust gas treatment system in Embodiment 2 of the present invention.

[0042] In the diagram: 1-Oxidation absorption tower, 2-Molecular sieve adsorption and desorption device, 3-Gas mass flow control device, 4-Pipeline electric heating device, 5-Absorbent liquid storage tank, 6-Oxidation liquid storage tank, 7-Absorbent liquid centrifugal pump, 8-Oxidation liquid centrifugal pump, 9-Gas detection device, 10-Tail gas treatment device, 11-Rise pipe, 12-Liquid distributor, 13-Oxidation packing unit, 14-Absorbent packing unit, 15-Oxidation absorption tower body, 16-Oxidation absorption tower body inlet, 17-Oxidation absorption tower body outlet, 18-Fan, 19-Adsorption tank A, 20-Adsorption tank B, 21-Second fan. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] The embodiments of this patent are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this patent, and should not be construed as limiting this patent.

[0045] In the description of this patent, it is important to understand that the terms "center," "upper," and "center" are used interchangeably.

[0046]

[0047] The orientation or positional relationship indicated by terms such as "top," "bottom," "inner," and "outer" is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the purpose of facilitating the description of this patent and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this patent.

[0048] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0049] Example 1

[0050] This embodiment provides a process for treating exhaust gas, including the following steps:

[0051] The oxidation absorption tower includes an oxidation absorption tower body, an oxidation packing unit, and an absorption packing unit. The oxidation packing unit and the absorption packing unit are disposed within the oxidation absorption tower body. The oxidation absorption tower body includes an oxidation absorption tower body inlet and an oxidation absorption tower body outlet. Nitrogen oxide-containing tail gas is introduced into the oxidation absorption tower body through the oxidation absorption tower body inlet. The nitrogen oxide-containing tail gas contains nitrogen oxides. Hydrogen peroxide oxidizing solution is introduced into the oxidation packing unit, and urea absorbent solution is introduced into the absorption packing unit. The nitrogen oxide-containing tail gas is treated by hydrogen peroxide oxidizing solution through the oxidation packing unit and by urea absorbent solution through the absorption packing unit. The treated nitrogen oxide-containing tail gas is discharged from the oxidation absorption tower body outlet.

[0052] The treated nitrogen oxide-containing exhaust gas is passed into a molecular sieve adsorption and desorption device to adsorb nitrogen oxides through molecular sieves, and then enters the exhaust gas treatment device to obtain the exhaust gas to be emitted.

[0053] The exhaust gas treatment process in this embodiment achieves safe, efficient, stable, and continuous treatment of nitrogen oxide exhaust gas, improving the nitrogen oxide removal rate and realizing the "dual carbon" goal of green and low emissions. It combines oxidation absorption and molecular sieve adsorption technologies. In the oxidation absorption tower, the oxidation and absorption packing units work in a cycle to gradually oxidize and absorb nitrogen oxides. Compared to traditional single-treatment methods, this approach can more comprehensively address nitrogen oxides in different states, significantly improving nitrogen oxide removal efficiency. The molecular sieve adsorption and desorption device further adsorbs the gas after treatment in the oxidation absorption tower, capturing nitrogen oxides that were not completely removed during the oxidation absorption process, achieving deep purification and ensuring an overall extremely high nitrogen oxide removal rate.

[0054] Example 2

[0055] This embodiment provides a process for treating exhaust gas, including the following steps:

[0056] The oxidation absorption tower 1 includes an oxidation absorption tower body 15, an oxidation packing unit 13, and an absorption packing unit 14. The oxidation packing unit 13 and the absorption packing unit 14 are disposed inside the oxidation absorption tower body 15. The oxidation absorption tower body 15 includes an oxidation absorption tower body inlet 16 and an oxidation absorption tower body outlet 17. The nitrogen oxide-containing tail gas is introduced into the oxidation absorption tower body 15 through the oxidation absorption tower body inlet 16. The nitrogen oxide-containing tail gas contains nitrogen oxides. Hydrogen peroxide oxidizing liquid is introduced into the oxidation packing unit 13, and urea absorbent liquid is introduced into the absorption packing unit 14. The nitrogen oxide-containing tail gas is treated by the hydrogen peroxide oxidizing liquid through the oxidation packing unit 13, and is treated by the urea absorbent liquid through the absorption packing unit 14. The treated nitrogen oxide-containing tail gas is discharged from the oxidation absorption tower body outlet 17.

[0057] The treated nitrogen oxide-containing exhaust gas is fed into the molecular sieve adsorption and desorption device 2, where the nitrogen oxides are adsorbed by the molecular sieve. The treated exhaust gas meets emission standards. The nitrogen oxide exhaust gas desorbed by the molecular sieve is then fed into the inlet 16 of the oxidation absorption tower via the blower 18 for recycling. Specifically, in this embodiment, the outlet of the oxidation absorption tower is located at the top of the tower.

[0058] The exhaust gas treatment device 10 is a packed tower with the same dimensions as the oxidation absorption tower 1, and contains a 10% sodium hydroxide solution.

[0059] The molecular sieve adsorption and desorption device 2 primarily removes low concentrations of nitrogen oxides. Gases after multi-stage oxidation and absorption are adsorbed by the molecular sieve and, if they meet the standards, are released into the atmosphere. The exhaust gas treatment device 10 is used to prevent system malfunctions from causing substandard exhaust gas and air pollution.

[0060] Preferably, the oxidation packing unit 13 is at least a two-stage oxidation packing unit 13, and there are at least two oxidation packing units 13. The absorption packing unit 14 is at least a two-stage absorption packing unit 14, and there are at least two absorption packing units 14. The number of oxidation packing units 13 and absorption packing units 14 is the same. Each oxidation packing unit 13 and each absorption packing unit 14 are arranged alternately in the axial direction of the oxidation absorption tower body 15.

[0061] Preferably, the oxidation absorption tower 1 further includes an oxidation liquid centrifugal pump 8, which is located outside the oxidation absorption tower body 15. All oxidation packing units 13 are connected in sequence, and the oxidation liquid centrifugal pump 8 is connected to two oxidation packing units 13 at both ends respectively. A loop is formed through the pipeline connection and the circulation of the oxidation liquid centrifugal pump 8.

[0062] Preferably, the oxidation absorption tower 1 further includes an absorption liquid centrifugal pump 7, which is located outside the tower body 15 of the oxidation absorption tower. All absorption packing units 14 are connected in sequence, and the absorption liquid centrifugal pump 7 is connected to two absorption packing units 14 at both ends respectively. A loop is formed through pipeline connection and circulation via the absorption liquid centrifugal pump 7.

[0063] The nitrogen oxide-containing tail gas enters through the inlet 16 at the bottom of the oxidation absorption tower and exits through the outlet 17 at the top. It first enters the oxidation packing unit 13, then passes through the absorption packing unit 14. The oxidation absorption tower 1 is an N-stage oxidation absorption tower 1, and this cycle repeats through N oxidation packing units 13 and N absorption packing units 14. The tail gas from the oxidation absorption tower 1 then enters the molecular sieve adsorption and desorption device 2 for adsorption. When adsorption reaches saturation, a desorption operation is performed. The desorbed gas, along with the inlet nitrogen oxide-containing tail gas, is returned to the oxidation absorption tower 1 for further oxidation and absorption. This process achieves highly efficient removal of nitrogen oxides from the nitrogen oxide-containing tail gas, ensuring that the emitted gas meets industrial emission standards and guaranteeing the stability and reliability of the process.

[0064] Preferably, the exhaust gas treatment process further includes the following steps:

[0065] The nitrogen oxide-containing tail gas adsorbed by the molecular sieve adsorption and desorption device 2 is desorbed and desorbed, and the desorbed nitrogen oxide-containing tail gas is then fed into the oxidation absorption tower 1 for further treatment.

[0066] Preferably, the desorption pressure of the molecular sieve adsorption and desorption device 2 is 5-12 kPa.

[0067] Preferably, the desorption pressure of the molecular sieve adsorption and desorption device 2 is 10 kPa.

[0068] Preferably, the composition of the urea absorption solution includes:

[0069] The weight percentage of CO(NH2)2 is 5%-25%, the weight percentage of HNO3 is 0-1%, and the balance is water.

[0070] Preferably, the composition of the urea absorption solution includes:

[0071] The weight percentage of CO(NH2)2 is 5%-25%, the weight percentage of HNO3 is 0.1-1%, and the balance is water.

[0072] Preferably, the composition of the urea absorbent includes: 20% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water.

[0073] Preferably, the hydrogen peroxide oxidizing solution comprises:

[0074] The weight percentage of H2O2 is 5%-15%, with the balance being water.

[0075] Preferably, the hydrogen peroxide oxidizing solution comprises:

[0076] The weight percentage of H2O2 is 1%, with the remainder being water.

[0077] Preferably, the circulation rate of the hydrogen peroxide oxidizing solution is 0.9-2.2 m³ / h. 3 / h.

[0078] Preferably, the circulation rate of the hydrogen peroxide oxidizing solution is 2.2 m³. 3 / h.

[0079] Preferably, the circulation rate of the urea absorption solution is 0.9-2.2 m³. 3 / h.

[0080] Preferably, the circulation volume of the urea absorption solution is 2.2 m³. 3 / h.

[0081] Preferably, the inlet flow rate of nitrogen oxide-containing tail gas into the oxidation absorption tower body 15 is 4-24 L / min.

[0082] Preferably, the residence time of the nitrogen oxide-containing exhaust gas in the oxidation absorption tower body 15 is 10s-30s.

[0083] Preferably, the residence time of the nitrogen oxide-containing exhaust gas in the oxidation absorption tower body 15 is 30 seconds.

[0084] Preferably, the exhaust gas treatment process further includes the following steps:

[0085] Before the nitrogen oxide-containing tail gas is introduced into the oxidation absorption tower body 15, the nitrogen oxide-containing tail gas is heated to 40-50℃.

[0086] Preferably, the exhaust gas treatment process further includes the following steps: when the nitrogen oxide-containing exhaust gas is introduced into the oxidation absorption tower 1, air is introduced into the oxidation absorption tower 1.

[0087] Preferably, the concentration of nitrogen oxides in the nitrogen oxide-containing exhaust gas after mixing with air is 5000-20000 mg / m³. 3 .

[0088] Preferably, the concentration of nitrogen oxides in the nitrogen oxide-containing exhaust gas is 16000 mg / m³. 3 .

[0089] Preferably, the air flow rate introduced into the oxidation absorption tower 1 is 90–180 Nm³. 3 / h.

[0090] Preferably, the air flow rate introduced into the oxidation absorption tower 1 is 90 Nm³. 3 / h.

[0091] Preferably, the packing size of the oxidation absorption tower 1 is DN25 or DN16.

[0092] Preferably, the packing material of the oxidation absorption tower 1 is DN16.

[0093] Hydrogen peroxide oxidizing solution oxidizes NO in nitrogen oxides in nitrogen oxide-containing exhaust gas to NO2, which in turn generates more nitrous acid, further reacting with urea in urea absorbent solution to produce N2. The reaction between HNO2 and urea in urea absorbent solution removes nitrogen oxides and improves the mass transfer driving force.

[0094] like Figure 1 As shown, this embodiment provides an exhaust gas treatment system used in an exhaust gas treatment process, comprising:

[0095] An oxidation absorption tower 1 includes an oxidation absorption tower body 15, oxidation packing units 13, and absorption packing units 14. The oxidation packing units 13 and absorption packing units 14 are disposed within the oxidation absorption tower body 15. The oxidation absorption tower body 15 includes an oxidation absorption tower inlet 16 and an oxidation absorption tower outlet 17. There are at least two oxidation packing units 13 and at least two absorption packing units 14. The number of oxidation packing units 13 and absorption packing units 14 is the same. Each oxidation packing unit 13 and each absorption packing unit 14 is arranged alternately along the axial direction of the oxidation absorption tower body 15.

[0096] The oxidation absorption tower 1 also includes: an oxidation liquid centrifugal pump 8, which is located outside the tower body 15 of the oxidation absorption tower. All oxidation packing units 13 are connected in sequence, and the oxidation liquid centrifugal pump 8 is connected to the upper oxidation packing unit 13. The oxidation absorption tower 1 also includes: an oxidation liquid storage tank 6, which is used to store hydrogen peroxide oxidation liquid. The oxidation liquid storage tank 6 is connected to the inlet of the oxidation liquid centrifugal pump and the outlet of the lower oxidation packing unit.

[0097] The oxidation absorption tower 1 also includes: an absorption liquid centrifugal pump 7, which is located outside the tower body 15 of the oxidation absorption tower. All absorption packing units 14 are connected in sequence, and the absorption liquid centrifugal pump 7 is connected to the upper absorption packing unit 14. The oxidation absorption tower 1 also includes: an absorption liquid storage tank 5, which is used to store urea absorption liquid. The absorption liquid storage tank 5 is connected to the inlet of the absorption liquid centrifugal pump and the outlet of the lower absorption packing unit, respectively.

[0098] Molecular sieve adsorption and desorption device 2 has its inlet connected to the outlet 17 of the oxidation absorption tower. A third sampling port is installed on the inlet pipe of molecular sieve adsorption and desorption device 2, and a fourth sampling port is installed on the outlet pipe. Both the third and fourth sampling ports are connected to a gas detection device 9, which detects the nitrogen oxide concentration in the collected gas. The gas detection device 9 includes a dryer, a dynamic gas mixer, and a nitrogen oxide analyzer connected in sequence. Molecular sieve adsorption and desorption device 2 includes two adsorption tanks. Two adsorption tanks are connected in parallel, namely adsorption tank A19 and adsorption tank B20. When one adsorption tank A19 is saturated, the system automatically switches to the other adsorption tank B20 for desorption. The saturated adsorption tank A19 is then desorbed. The gas generated by desorption is reintroduced into the oxidation absorption tower 1 along with the raw material gas for further removal. The molecular sieve adsorption and desorption device 2 also includes a second blower 21, which is connected to the inlet and outlet of the adsorption tank, respectively. The second blower 21 is also connected to a second air duct, which is used to introduce air.

[0099] The pipeline electric heating device 4 is connected to the outlet of the molecular sieve adsorption and desorption device 2. The pipeline electric heating device 4 is used to heat the nitrogen oxide-containing tail gas to a preset temperature. The pipeline electric heating device 4 is also connected to the raw material gas pipeline, which is used to introduce the nitrogen oxide-containing tail gas to be treated.

[0100] The blower 18 is connected to the inlet 16 of the oxidation absorption tower body. The blower 18 is also connected to the first air duct, which is used to introduce air. The blower 18 is used to introduce nitrogen oxide tail gas and air into the oxidation absorption tower 1.

[0101] Gas mass flow control device 3, the inlet of gas mass flow control device 3 is connected to pipeline electric heating device 4, the outlet of gas mass flow control device 3 is connected to oxidation absorption tower body inlet 16, gas mass flow control device 3 is used to control the mass flow of nitrogen oxide-containing tail gas.

[0102] The gas detection device 9 is provided with a first sampling port in the inlet pipe of the oxidation absorption tower inlet 16 and a second sampling port in the outlet pipe of the oxidation absorption tower outlet 17. The first sampling port and the second sampling port are respectively connected to the gas detection device 9, and the gas collected is detected by the gas detection device 9.

[0103] The exhaust gas treatment device 10 is connected to the outlet of the molecular sieve adsorption and desorption device 2, and the outlet of the exhaust gas treatment device 10 is connected to the atmosphere.

[0104] In this embodiment, the raw gas is heated to a preset temperature by the pipeline electric heating device 4, and then a certain flow rate of raw gas and a certain flow rate of air are mixed and mixed by the gas mass flow control device 3 and enter the oxidation absorption tower 1. The oxidation absorption tower 1 is composed of multiple oxidation packing units 13 and absorption packing units 14. The mixed gas enters the oxidation absorption tower 1 and first passes through the oxidation packing unit 13, and then through the absorption packing unit 14. This cycle continues until the gas exits from the outlet 17 of the oxidation absorption tower at the top of the tower and enters the molecular sieve adsorption and desorption device 2. The gas is adsorbed by the molecular sieve adsorption and desorption device 2. The adsorbed gas is discharged as air after passing through the tail gas treatment device 10. The molecular sieve adsorption and desorption device 2 is composed of two adsorption tanks. When one adsorption tank is saturated, the system automatically switches to the other adsorption tank for desorption. The saturated adsorption tank is desorbed, and the gas generated by desorption re-enters the oxidation absorption tower 1 with the raw gas for further removal. The urea absorbent in the absorbent storage tank 5 consists of a certain weight fraction of CO(NH2)2 and HNO3. It is transported at a certain flow rate by the absorbent centrifugal pump 7 to the absorbent packing layer of the absorbent packing unit 14 in the oxidation absorption tower 1. A liquid distributor 12 is installed at the upper end of the absorbent packing layer, and a gas riser 11 is installed at the lower end. The absorbent packing layers of the absorbent packing unit 14 at different locations are connected by stainless steel pipes, so that the liquids in the absorbent packing layers at different locations are interconnected. The hydrogen peroxide oxidant in the oxidation storage tank 6 consists of a certain weight fraction of hydrogen peroxide. It is transported to the oxidation packing layer of the oxidation tower by the oxidation centrifugal pump 8. A liquid distributor 12 is installed at the upper end of the oxidation packing layer, and a gas riser 11 is installed at the lower end. The oxidation packing layers at different locations are connected by stainless steel pipes, so that the liquids in the oxidation packing layers at different locations are interconnected. Sampling ports are provided at the inlet and outlet of oxidation absorption tower 1, at different locations on the tower, and at the inlet and outlet of molecular sieve adsorption and desorption device 2. These ports are connected to gas detection device 9 for detecting nitrogen oxide concentration. A liquid sampling port is provided at the bottom of oxidation absorption tower 1 for analyzing urea concentration, ionic composition, and pH value. The urea concentration at the bottom of oxidation absorption tower 1 is the same as the urea concentration at the outlet of the absorption packing unit.

[0105] Specifically, this embodiment provides a nitrogen oxide treatment process (tail gas treatment process) integrating multi-stage oxidation absorption and molecular sieve adsorption technologies, including the following steps: using the above-mentioned tail gas treatment system, the packing of the oxidation absorption tower 1 is DN16, the raw gas is heated to 40°C by the pipeline electric heating device 4, and then the flow rate of the nitrogen oxide-containing tail gas of the raw gas is controlled to 4L / min and 90Nm by the gas mass flow control device 3. 3 / h of air is mixed to form a concentration of 5000 mg / m³ 3The mixed gas of nitrogen oxides enters the N-stage oxidation absorption tower 1, with a residence time of 30 seconds. The N-stage oxidation absorption tower 1 consists of multiple oxidation packing units 13 and absorption packing units 14. The mixed gas first passes through the oxidation packing units 13, then through the absorption packing units 14, and so on until the gas exits from the top of the tower and enters the molecular sieve adsorption and desorption device 2. The gas is adsorbed in the molecular sieve adsorption and desorption device 2, and the adsorbed gas is discharged as air after passing through the tail gas treatment device 10. The molecular sieve adsorption and desorption device 2 consists of two adsorption tanks. When one adsorption tank is saturated, the system automatically switches to the other adsorption tank for desorption operation at a desorption pressure of 10 kPa. The saturated adsorption tank continues to desorb, and the gas generated by desorption is reintroduced into the N-stage oxidation absorption tower 1 along with the raw gas for further removal. The gases generated by desorption include NO2, NO, N2O3, N2O4, HNO2, HNO3, and H2O. The absorbent storage tank 5 contains 20% CO(NH2)2 by weight and 0.125% HNO3 by weight. The absorbent is then pumped by centrifugal pump 7 at a speed of 2.2 m³ / min. 3 A flow rate of / h is transported to the N-stage oxidation absorption tower's absorption packing layer. A liquid distributor 12 is installed at the upper end of the absorption packing layer, and a riser pipe 11 is installed at the lower end. Absorption packing layers at different locations are connected by stainless steel pipes. The oxidation liquid storage tank 6 contains 1% H2O2 by weight, with water as the balance. The solution is then pumped by an oxidation liquid centrifugal pump 8 at a flow rate of 2.2m... 3 The flow rate is transported to the oxidation packing layer of the N-stage oxidation absorption tower. A liquid distributor 12 is installed at the upper end of the oxidation packing layer, and a gas riser 11 is installed at the lower end. The oxidation packing layers at different locations are connected by stainless steel pipes. Sampling ports are provided at the inlet and outlet of the N-stage oxidation absorption tower 1, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device 2. These ports are connected to a gas detection device 9 to detect the concentration of nitrogen oxides. A liquid sampling port is provided at the bottom of the tower to analyze the urea concentration. The results are recorded in Table 2.

[0106] The exhaust gas treatment process in this embodiment achieves safe, efficient, stable, and continuous treatment of nitrogen oxide exhaust gas, improving the nitrogen oxide removal rate and realizing the "dual carbon" goal of green and low emissions. It combines oxidation absorption and molecular sieve adsorption technologies. In the oxidation absorption tower 1, the oxidation packing unit 13 and the absorption packing unit 14 work together to gradually oxidize and absorb nitrogen oxides. Compared to traditional single-treatment methods, this approach can more comprehensively address nitrogen oxides in different states, significantly improving nitrogen oxide removal efficiency. Under otherwise constant operating conditions, the key factors affecting nitrogen oxide absorption efficiency mainly include the initial gas concentration and its oxidation state. Traditional single-absorption treatment methods often struggle to simultaneously address the conversion characteristics of different forms of nitrogen oxides such as NO, NO2, and their polymers, resulting in limited overall removal rates. In contrast, the multi-stage oxidation absorption tower introduces a step-by-step oxidation reaction during absorption, sustainably maintaining a high oxidation environment, thereby effectively promoting the conversion of NO to more easily absorbed forms such as NO2. This strategy not only expands the reaction range but also significantly enhances the treatment capacity for different forms of nitrogen oxides, ultimately achieving a more efficient synergistic removal effect. The molecular sieve adsorption and desorption device 2 further adsorbs the gas after it has been treated by the oxidation absorption tower 1, and can capture those nitrogen oxides that were not completely removed during the oxidation absorption process, thus achieving deep purification and ensuring that the overall removal rate of nitrogen oxides is extremely high.

[0107] The multi-stage oxidation absorption tower 1 features a well-designed structure, including the tower body 15, oxidation packing unit 13, absorption packing unit 14, riser 11, and liquid distributor 12, ensuring stable mass transfer and reaction between gas and liquid within the tower. The packing layers in the oxidation packing unit 13 and absorption packing unit 14 provide ample contact area for the reaction, while the riser 11 and liquid distributor 12 contribute to the uniform distribution of gas and liquid, thus guaranteeing the stability of the oxidation absorption process. The molecular sieve adsorption and desorption device 2 consists of two adsorption tanks. When one adsorption tank becomes saturated, the system automatically switches to the other adsorption tank for desorption, while the saturated adsorption tank continues desorption. This alternating dual-tank operation ensures uninterrupted adsorption, achieving continuous treatment of nitrogen oxides and guaranteeing the stability of the entire device. The raw gas is heated to a specific temperature by the pipeline electric heating device 4, and then mixed with air by the gas mass flow control device 3 before entering the N-stage oxidation absorption tower 1. This orderly process design ensures that the gas entering the oxidation absorption tower 1 is in a stable state in terms of temperature, flow rate, and composition, which is conducive to the stable progress of the reaction. At the same time, the stable circulation and transportation of the oxidizing liquid and the absorbent liquid to the corresponding packing layer also ensures the stability and continuity of the entire treatment process.

[0108] Precisely control the circulation rate of the oxidation liquid and absorbent liquid within 0.9-2.2 m³. 3 / h (preferably 2.2m) 3 / h), inlet gas volume is 90-180Nm 3 / h (preferably 90Nm) 3 / h), nitrogen oxide concentration in the range of 5000-200000 mg / m³ 3 (Preferred concentration: 16000 mg / m³) 3 The optimized process parameters, such as the residence time within the tower being 10-30 seconds (preferably 30 seconds), ensure sufficient reactants to react with nitrogen oxides within the tower. The optimized inlet gas flow rate and nitrogen oxide concentration allow the reaction to proceed under suitable concentration and flow conditions, while the appropriate residence time provides ample time for the reaction. These optimized parameters collectively promote nitrogen oxide removal. The gas treated by this device is then discharged into the air via the tail gas treatment device 10. The tail gas treatment device 10 provides final treatment for non-compliant tail gas after system failure, ensuring that the tail gas emitted into the atmosphere meets environmental standards, protecting environmental safety and human health. By efficiently removing nitrogen oxides, the emission of this greenhouse gas is reduced, contributing to the achievement of the green and low-emission "dual-carbon" goal.

[0109] Example 3

[0110] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0111] The packing material in the oxidation absorption tower is DN16, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 9L / min, and the air flow rate is 90Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 12000 mg / m³ 3 The residence time inside the tower is 30 seconds, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the composition of the urea absorbent includes: 20% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 2.2 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is as follows: H2O2 accounts for 1% by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 2.2 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0112] Example 4

[0113] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0114] The packing material in the oxidation absorption tower is DN16, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 12L / min, and the air flow rate is 90Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 16000 mg / m³ 3 The residence time inside the tower is 30 seconds, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the composition of the urea absorbent includes: 20% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 2.2 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is as follows: H2O2 accounts for 1% by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 2.2 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0115] Example 5

[0116] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0117] The packing material in the oxidation absorption tower is DN16, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 16L / min, and the air flow rate is 120Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 16000 mg / m³ 3 The residence time inside the tower is 22 s, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the composition of the urea absorbent includes: 20% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 2.2 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is as follows: H2O2 accounts for 1% by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 2.2 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0118] Example 6

[0119] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0120] The packing material in the oxidation absorption tower is DN16, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 24L / min, and the air flow rate is 180Nm. 3 / h, the concentration of nitrogen oxides in the mixed gas is 16000 mg / m³ 3 The residence time inside the tower is 15 s, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the composition of the urea absorbent includes: 20% CO(NH2)2 by weight, 0.63% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 2.2 m³ / s. 3 The hydrogen peroxide oxidation liquid composition is as follows: H2O2 accounts for 1% by weight, with the balance being water. The hydrogen peroxide oxidation liquid circulation rate is 2.2 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0121] Example 7

[0122] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0123] The packing material in the oxidation absorption tower is DN16, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 12L / min, and the air flow rate is 90Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 16000 mg / m³ 3 The residence time inside the tower is 30 seconds, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the composition of the urea absorbent includes: 20% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 1.8 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is: 1% H2O2 by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 1.8 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0124] Example 8

[0125] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0126] The packing material in the oxidation absorption tower is DN16, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 12L / min, and the air flow rate is 90Nm³.3 / h, the concentration of nitrogen oxides in the mixed gas is 16000 mg / m³ 3 The residence time inside the tower is 30 seconds, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the composition of the urea absorbent includes: 20% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 0.9 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is: 1% H2O2 by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 0.9 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0127] Example 9

[0128] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0129] The packing material in the oxidation absorption tower is DN16, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 12L / min, and the air flow rate is 90Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 16000 mg / m³ 3 The residence time inside the tower is 30 seconds, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the composition of the urea absorbent includes: 10% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 2.2 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is as follows: H2O2 accounts for 1% by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 2.2 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0130] Example 10

[0131] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0132] The packing material in the oxidation absorption tower is DN16, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 12L / min, and the air flow rate is 90Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 16000 mg / m³ 3The residence time inside the tower is 30 seconds, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the composition of the urea absorbent includes: 25% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 2.2 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is: 1% H2O2 by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 2.2 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0133] Example 11

[0134] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0135] The packing material in the oxidation absorption tower is DN16, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 12L / min, and the air flow rate is 90Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 16000 mg / m³ 3 The residence time inside the tower is 30 seconds, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the urea absorbent composition includes: 20% CO(NH2)2 by weight, 1.25% HNO3 by weight, and the balance being water. The urea absorbent circulation rate is 2.2 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is as follows: H2O2 accounts for 1% by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 2.2 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0136] Example 12

[0137] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0138] The packing material in the oxidation absorption tower is DN16, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 12L / min, and the air flow rate is 90Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 16000 mg / m³ 3The residence time inside the tower is 30 seconds, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the composition of the urea absorbent includes: 20% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 2.2 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is: 5% H2O2 by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 2.2 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0139] Example 13

[0140] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0141] The packing material in the oxidation absorption tower is DN25, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 12L / min, and the air flow rate is 90Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 16000 mg / m³ 3 The residence time inside the tower is 30 seconds, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the composition of the urea absorbent includes: 20% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 2.2 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is as follows: H2O2 accounts for 1% by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 2.2 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0142] Table 1 Symbol Table

[0143] name symbol unit Urea mass fraction: W1 W1 ％ <![CDATA[Mass fraction of HNO3: W2]]> W2 ％ <![CDATA[Mass fraction of H2O2: W3]]> W3 ％ Raw material gas flow rate: Q1 Q1 L / min Airflow rate: Q Q2 <![CDATA[m 3 / h]]> Duration of stay: t t s Analysis of pressure: P P Kpa Oxidizing liquid circulation volume L1 <![CDATA[m 3 / h <!-- 11 -->]]> Absorbent circulation volume L2 <![CDATA[m 3 / h]]> Nitrogen oxide concentration at the inlet of the oxidation absorption tower X1 <![CDATA[mg / m 3 ]]> Nitrogen oxide concentration at the outlet of the oxidation absorption tower X2 <![CDATA[mg / m 3 ]]> Nitrogen oxide concentration at the inlet of the adsorption tank X3 <![CDATA[mg / m 3 ]]> Nitrogen oxide concentration at adsorption tank outlet X4 <![CDATA[mg / m 3 ]]> Nitrogen oxide removal rate of oxidation absorption tower Y1 ％ Nitrogen oxide removal rate of oxidation absorption tower Y2 ％

[0144]

[0145] Table 2 shows that the nitrogen oxide treatment system using integrated multi-stage oxidation absorption and molecular sieve adsorption technology and its corresponding process flow can achieve a nitrogen oxide removal rate of over 99%, with the oxidation absorption tower achieving a nitrogen oxide removal rate of over 76%. The system uses DN16 packing material, a raw gas heating temperature of 40℃, a flow rate of 12 L / min, and an air flow rate of 90 Nm³. 3 / h, the mixed gas concentration is 16000 mg / m³ 3The residence time inside the tower is 30 seconds, the desorption pressure is 10 kPa, and the urea absorbent composition includes: 20% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the urea absorbent circulation rate is 2.2 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is as follows: H2O2 1% by weight, water as the balance, and the hydrogen peroxide oxidizing solution circulation rate is 2.2 m³ / h. 3 Under the condition of / h, the nitrogen oxide removal rate of the oxidation absorption tower is 82.62%, and the outlet nitrogen oxide concentration is 3000 mg / m³. 3 The following method utilizes a molecular sieve adsorption and desorption device to reduce the concentration of nitrogen oxides to near 0 mg / m³. 3 Under these conditions, the molecular sieve can work continuously for 10 hours. Each kilogram of molecular sieve can adsorb 0.4 mol of nitrogen oxides, and the maximum desorption pressure can reach 12 kPa.

[0146] Example 14

[0147] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0148] The packing material in the oxidation absorption tower is DN25, the feed gas heating temperature is 40℃, the flow rate of the nitrogen oxide-containing tail gas is 12L / min, and the air flow rate is 90Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 5000 mg / m³ 3 The residence time inside the tower is 30 seconds, the desorption pressure of the molecular sieve adsorption and desorption device is 10 kPa, and the composition of the urea absorbent includes: 20% CO(NH2)2 by weight, 0.125% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 2.2 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is as follows: H2O2 accounts for 1% by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 2.2 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0149] Example 15

[0150] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0151] The packing material in the oxidation absorption tower is DN25, the feed gas heating temperature is 45℃, the flow rate of the nitrogen oxide-containing tail gas is 24L / min, and the air flow rate is 160Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 20000 mg / m³ 3 The residence time inside the tower is 10 s, the desorption pressure of the molecular sieve adsorption and desorption device is 5 kPa, and the composition of the urea absorbent includes: 5% CO(NH2)2 by weight, 0.1% HNO3 by weight, and the balance being water. The circulation rate of the urea absorbent is 0.9 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is as follows: H2O2 accounts for 5% by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 1.5 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0152] Example 16

[0153] This embodiment provides an exhaust gas treatment process, using the exhaust gas treatment system in Embodiment 2. The difference between this embodiment and the exhaust gas treatment process in Embodiment 2 is as follows:

[0154] The packing material in the oxidation absorption tower is DN25, the feed gas heating temperature is 50℃, the flow rate of the nitrogen oxide-containing tail gas is 16L / min, and the air flow rate is 100Nm³. 3 / h, the concentration of nitrogen oxides in the mixed gas is 10000 mg / m³ 3 The residence time in the tower is 20 s, the desorption pressure of the molecular sieve adsorption and desorption device is 12 kPa, and the urea absorbent composition includes: 10% CO(NH2)2 by weight, 1% HNO3 by weight, and the balance being water. The urea absorbent circulation rate is 2.0 m³ / s. 3 The hydrogen peroxide oxidizing solution composition is: 15% H2O2 by weight, with the balance being water. The hydrogen peroxide oxidizing solution circulation rate is 0.9 m³ / h. 3 / h. The concentrations of nitrogen oxides at the inlet and outlet of the N-stage oxidation absorption tower, at different locations on the tower, and at the inlet and outlet of the molecular sieve adsorption and desorption device, as well as the concentration of urea at the bottom of the tower, are recorded in Table 2.

[0155] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A process for treating exhaust gas, characterized in that, Includes the following steps: The oxidation absorption tower includes an oxidation absorption tower body, an oxidation packing unit, and an absorption packing unit. The oxidation packing unit and the absorption packing unit are disposed in the oxidation absorption tower body. The oxidation absorption tower body includes an oxidation absorption tower body inlet and an oxidation absorption tower body outlet. The nitrogen oxide-containing tail gas is introduced into the oxidation absorption tower body through the oxidation absorption tower body inlet. The hydrogen peroxide oxidizing liquid is introduced into the oxidation packing unit, and the urea absorbent liquid is introduced into the absorption packing unit. The nitrogen oxide-containing tail gas is treated by the hydrogen peroxide oxidizing liquid through the oxidation packing unit and by the urea absorbent liquid through the absorption packing unit. The treated nitrogen oxide-containing tail gas is discharged from the oxidation absorption tower body outlet. The treated nitrogen oxide-containing exhaust gas is passed into a molecular sieve adsorption and desorption device to adsorb nitrogen oxides through molecular sieves, and then enters the exhaust gas treatment device to obtain the exhaust gas to be emitted.

2. The exhaust gas treatment process according to claim 1, characterized in that, There are at least two oxidation packing units and at least two absorption packing units. The number of oxidation packing units and absorption packing units is the same. Each oxidation packing unit and each absorption packing unit are arranged alternately along the axial direction of the oxidation absorption tower body.

3. The exhaust gas treatment process according to claim 2, characterized in that, The oxidation absorption tower also includes an oxidation liquid centrifugal pump, which is located outside the oxidation absorption tower. All oxidation packing units are connected in sequence, and the oxidation liquid centrifugal pump is connected to two oxidation packing units at both ends.

4. The exhaust gas treatment process according to claim 2, characterized in that, The oxidation absorption tower also includes an absorption liquid centrifugal pump, which is located outside the oxidation absorption tower. All absorption packing units are connected in sequence, and the absorption liquid centrifugal pump is connected to two absorption packing units at both ends.

5. The exhaust gas treatment process according to claim 1, characterized in that, It also includes the following steps: The nitrogen oxide-containing tail gas adsorbed by the molecular sieve adsorption and desorption device is desorbed and desorbed, and the desorbed nitrogen oxide-containing tail gas is then fed into the oxidation absorption tower for further treatment.

6. The exhaust gas treatment process according to claim 5, characterized in that, The desorption pressure of the molecular sieve adsorption and desorption device is 5-12 kPa.

7. The exhaust gas treatment process according to claim 1, characterized in that, The composition of urea absorption solution includes: The weight percentage of CO(NH2)2 is 5%-25%, the weight percentage of HNO3 is 0-1%, and the balance is water.

8. The exhaust gas treatment process according to claim 1, characterized in that, The composition of hydrogen peroxide oxidizing solution includes: The weight percentage of H2O2 is 5%-15%, with the balance being water.

9. The exhaust gas treatment process according to claim 1, characterized in that, The circulation rate of the hydrogen peroxide oxidizing solution is 0.9-2.2 m³ / min. 3 / h.

10. The exhaust gas treatment process according to claim 1, characterized in that, The circulation rate of the urea absorption solution is 0.9-2.2 m³. 3 / h.

11. The exhaust gas treatment process according to claim 1, characterized in that, The inlet flow rate of nitrogen oxide-containing tail gas into the oxidation absorption tower is 4-24 L / min.

12. The exhaust gas treatment process according to claim 1, characterized in that, The residence time of nitrogen oxide-containing exhaust gas inside the oxidation absorption tower is 10s-30s.

13. The exhaust gas treatment process according to claim 1, characterized in that, It also includes the following steps: Before the nitrogen oxide-containing tail gas is introduced into the oxidation absorption tower, the nitrogen oxide-containing tail gas is heated to 40-50℃.

14. The exhaust gas treatment process according to claim 1, characterized in that, It also includes the following steps: When nitrogen oxide-containing exhaust gas is introduced into the oxidation absorption tower, air is introduced into the oxidation absorption tower.

15. The exhaust gas treatment process according to claim 14, characterized in that, The concentration of nitrogen oxides in the exhaust gas after mixing with air is 5000-20000 mg / m³. 3 .

16. The exhaust gas treatment process according to claim 14, characterized in that, The air flow rate introduced into the oxidation absorption tower is 90–180 Nm³. 3 / h.

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