阅读说明：本技术 玻璃电炉尾气氮氧化物净化装置 (Glass electric furnace tail gas nitrogen oxide purifier ) 是由 张德恩 于洋 耿延庆 王素红 朱民强 刘恋 陈琛 张军 许小滔 赵世磊 于 2019-11-04 设计创作，主要内容包括：本发明涉及一种玻璃电炉尾气氮氧化物净化装置,包括烟气净化塔、氧气吸收塔、还原吸收塔、末端吸收塔和烟气缓冲器,烟气缓冲器的进气口与进风管连通,烟气缓冲器的出气口通过风管与烟气净化塔的进风口连通,烟气净化塔侧面上端的出风口通过连接风管、离心通风机与氧气吸收塔的进风口连通,氧气吸收塔顶部的出风口通过连接风管与还原吸收塔的进风口连通,还原吸收塔顶部的出风口通过连接风管与末端吸收塔的进风口连通,末端吸收塔顶部的出风口与排气筒连通。本使用新型对于氮氧化物的净化效率为90％-95％,使用本发明净化后电炉尾气氮氧化物的排放浓度可低于400mg/m<Sup>3</Sup>。(The invention relates to a glass electric furnace tail gas nitrogen oxide purification device, which comprises a flue gas purification tower, an oxygen absorption tower, a reduction absorption tower, a tail end absorption tower and a flue gas buffer, wherein the air inlet of the flue gas buffer is communicated with an air inlet pipe, the air outlet of the flue gas buffer is communicated with the air inlet of the flue gas purification tower through an air pipe, and the air outlet at the upper end of the side surface of the flue gas purification tower is communicated with the air inlet of the flue gas purification tower through a connecting air pipeThe core ventilator is communicated with an air inlet of the oxygen absorption tower, an air outlet at the top of the oxygen absorption tower is communicated with an air inlet of the reduction absorption tower through a connecting air pipe, an air outlet at the top of the reduction absorption tower is communicated with an air inlet of the tail-end absorption tower through a connecting air pipe, and an air outlet at the top of the tail-end absorption tower is communicated with the exhaust funnel. The purifying efficiency of the novel furnace tail gas nitrogen oxide purifying device is 90-95%, and the emission concentration of the nitrogen oxide in the tail gas of the electric furnace after purification by the novel furnace tail gas nitrogen oxide purifying device can be lower than 400mg/m 3 。)

1. The utility model provides a glass electric stove tail gas nitrogen oxide purifier, includes gas cleaning tower (1), oxygen absorption tower (2), reduction absorption tower (3), terminal absorption tower (4) and flue gas buffer (6), its characterized in that: the air inlet and the air-supply line (7) intercommunication of flue gas buffer (6), the air outlet of flue gas buffer (6) passes through the air intake intercommunication of tuber pipe and flue gas purification tower (1), the air outlet of flue gas purification tower (1) side upper end is through connecting tuber pipe (8), the air intake intercommunication of centrifugal fan (9) and oxygen absorption tower (2), the air outlet at oxygen absorption tower (2) top passes through the air intake intercommunication of connecting tuber pipe (8) and reduction absorption tower (3), the air outlet at reduction absorption tower (3) top passes through the air intake intercommunication of connecting tuber pipe (8) and terminal absorption tower (4), the air outlet and aiutage (5) intercommunication at terminal absorption tower (4) top.

2. The glass electric furnace tail gas nitrogen oxide purification device according to claim 1, characterized in that: the flue gas purification tower (1) be equipped with barrel, filter bag (11), compressed air blowback deashing system (12) and add dust system (13) in advance, filter bag (11) set up in the body chamber of flue gas purification tower (1) barrel, compressed air blowback deashing system (12) set up in flue gas purification tower (1) upper end, add dust system (13) setting in flue gas purification tower (1) bottom in advance.

3. The glass electric furnace tail gas nitrogen oxide purification device according to claim 2, characterized in that: the compressed air back-blowing ash-cleaning system (12) comprises a compressed air pipeline (121), a pressure reducing valve (122), a pulse control valve (123) and a pulse spray pipe (124), wherein the pulse spray pipe (124) is arranged above a filter bag (11) in a cylinder body cavity of the flue gas purification tower (1).

4. The glass electric furnace tail gas nitrogen oxide purification device according to claim 2, characterized in that: the pre-dust-adding system (13) comprises an automatic feeder (131), a blowing pipe (132), a blowing fan (133) and a dust storage hopper (134), wherein the dust storage hopper (134) is arranged at the bottom of the cylinder of the flue gas purification tower (1), and the bottom of the dust storage hopper (134) is communicated with the upper end of the side surface of the dust storage hopper (134) through the automatic feeder (131), the blowing pipe (132) and the blowing fan (133).

5. The glass electric furnace tail gas nitrogen oxide purification device according to claim 1, characterized in that: the oxygen absorption tower (2) is provided with a cylinder, a packing layer (21), a liquid storage tank (22) and a spraying system (23), the oxygen absorption tower (2) is connected with a liquid supplementing system (24) and a waste liquid collecting system (25), the packing layer (21) is arranged in the cavity of the cylinder of the oxygen absorption tower (2), and the liquid storage tank (22) is arranged at the lower end of the oxygen absorption tower (2).

6. The glass electric furnace tail gas nitrogen oxide purification device according to claim 1, characterized in that: the reduction absorption tower (3) is provided with a cylinder, a packing layer (21), a liquid storage tank (22) and a spraying system (23), the reduction absorption tower (3) is connected with a liquid supplementing system (24) and a waste liquid collecting system (25), the packing layer (21) is arranged in the cavity of the cylinder of the reduction absorption tower (3), and the liquid storage tank (22) is arranged at the lower end of the reduction absorption tower (3).

7. The glass electric furnace tail gas nitrogen oxide purification device according to claim 1, characterized in that: the tail-end absorption tower (4) is provided with a cylinder body, a packing layer (21), a liquid storage tank (22) and a spraying system (23), the tail-end absorption tower (4) is connected with a liquid supplementing system (24) and a waste liquid collecting system (25), the packing layer (21) is arranged in the cavity of the cylinder body of the tail-end absorption tower (4), and the liquid storage tank (22) is arranged at the lower end of the tail-end absorption tower (4).

8. The apparatus for purifying nitrogen oxides in tail gas of a glass electric furnace according to any one of claims 5 to 7, characterized in that: the spraying system (23) comprises a spraying pipe (231), a spraying head (232) and a spraying pump (233), the spraying head (232) is arranged in the cavity of the cylinder body, one end of the spraying pump (233) is connected with the liquid storage tank (22) through the spraying pipe (231), and the other end of the spraying pump (233) is connected with the spraying head (232) through the spraying pipe (231).

9. The glass electric furnace tail gas nitrogen oxide purification device according to claim 1, characterized in that: the height of the discharge port of the exhaust funnel (5) from the ground is 16 m.

Technical Field

The invention relates to a glass electric furnace tail gas nitrogen oxide purification device, and belongs to the technical field of waste gas purification.

Background

Nitrogen oxides are a significant source of photochemical smog formation, which can reduce air visibility, stimulate eyes and respiratory tracts, and damage the health of people and animals and plants. Nitrogen oxides are also one of the important causes of acid rain formation. In view of the serious harmful effects of nitrogen oxides on the environment and human health, how to effectively eliminate nitrogen oxides is an important issue in environmental protection at present. The tail gas generated by the glass electric furnace contains a large amount of nitrogen oxides and flue gas, the existing nitrogen oxide treatment method has advantages and disadvantages, and the automation degree and the purification efficiency are generally low.

Disclosure of Invention

According to the defects in the prior art, the technical problems to be solved by the invention are as follows: provides a glass electric furnace tail gas nitrogen oxide purification device to solve the defects.

The invention relates to a glass electric furnace tail gas nitrogen oxide purification device which comprises a flue gas purification tower, an oxygen absorption tower, a reduction absorption tower, a tail end absorption tower and a flue gas buffer, wherein an air inlet of the flue gas buffer is communicated with an air inlet pipe, an air outlet of the flue gas buffer is communicated with an air inlet of the flue gas purification tower through an air pipe, an air outlet at the upper end of the side surface of the flue gas purification tower is communicated with an air inlet of the oxygen absorption tower through a connecting air pipe and a centrifugal fan, an air outlet at the top of the oxygen absorption tower is communicated with an air inlet of the reduction absorption tower through a connecting air pipe, an air outlet at the top of the reduction absorption tower is communicated with an air inlet of the tail end absorption tower through a.

Preferably, the flue gas purification tower is provided with a cylinder, a filter bag, a compressed air back-blowing ash removal system and a pre-dust addition system, wherein the filter bag is arranged in a body cavity of the cylinder of the flue gas purification tower, the compressed air back-blowing ash removal system is arranged at the upper end of the flue gas purification tower, and the pre-dust addition system is arranged at the bottom of the flue gas purification tower. The flue gas is mixed with pre-added dust in the flue gas purification tower to absorb the components of the flue gas.

Preferably, the compressed air blowback ash removal system comprises a compressed air pipeline, a pressure reducing valve, a pulse control valve and a pulse spray pipe, wherein the pulse spray pipe is arranged above the filter bag in the body cavity of the flue gas purification tower. The compressed air back-blowing ash removal system is used for blowing dust from the filter bag to the ash storage hopper.

Preferably, add dust system in advance includes automatic glassware, jetting pipe, jetting fan and ash storage bucket down, and ash storage bucket sets up in gas cleaning tower barrel bottom, and the bottom of ash storage bucket is through automatic glassware, jetting pipe, jetting fan and the side upper end intercommunication of ash storage bucket down. The pre-dust can be recycled, and when the color of the pre-dust is changed, new dust is replaced.

Preferably, the oxygen absorption tower is provided with a cylinder, a packing layer, a liquid storage tank and a spraying system, the oxygen absorption tower is connected with the liquid supplementing system and the waste liquid collecting system, the packing layer is arranged in a body cavity of the cylinder of the oxygen absorption tower, and the liquid storage tank is arranged at the lower end of the oxygen absorption tower. The flue gas converts most of nitric oxide into nitrogen dioxide in the oxygen absorption tower so as to increase the absorption rate of the nitrogen oxide in the reduction absorption tower.

Preferably, the reduction absorption tower is provided with a cylinder, a packing layer, a liquid storage tank and a spraying system, the reduction absorption tower is connected with the liquid supplementing system and the waste liquid collecting system, the packing layer is arranged in a body cavity of the cylinder of the reduction absorption tower, and the liquid storage tank is arranged at the lower end of the reduction absorption tower. The main function of the reduction absorption tower is to absorb nitrogen oxides in the flue gas.

Preferably, the tail end absorption tower is provided with a cylinder, a packing layer, a liquid storage tank and a spraying system, the tail end absorption tower is connected with the liquid supplementing system and the waste liquid collecting system, the packing layer is arranged in a body cavity of the cylinder of the tail end absorption tower, and the liquid storage tank is arranged at the lower end of the tail end absorption tower. The absorption liquid used by the tail end absorption tower is mainly clear water, nitrate produced by the front 2 towers, unreacted oxidation liquid and reduction absorption liquid are washed in the tail end absorption tower, and if the concentration of sulfur dioxide in the flue gas produced in the production process is high, the absorption liquid used by the absorption tower can be changed into 5-10% of sodium hydroxide solution to react with the sulfur dioxide to generate sodium sulfate.

Preferably, the spraying system comprises a spraying pipe, a spraying head and a spraying pump, the spraying head is arranged in the cavity of the cylinder body, one end of the spraying pump is connected with the liquid storage tank through the spraying pipe, and the other end of the spraying pump is connected with the spraying head through the spraying pipe. The absorption liquid is recycled under the action of the spraying system, and the absorption liquid is recovered and replaced after the absorption liquid is invalid.

Preferably, the discharge port of the exhaust funnel is 16 m high from the ground.

The working principle and the process are as follows:

the flue gas of the electric furnace is sucked into the flue gas purification tower by the centrifugal fan, is fully mixed with the dust which enters the flue gas purification tower by the pre-dust adding system, adsorbs the flue gas components to the pre-added dust particles, and is filtered by the filter bag, thereby achieving the purpose of purifying the flue gas. The dust adhered to the filter bag is cleaned from the filter bag by a high-pressure pulse dust cleaning device, settled in a dust storage hopper at the lower part of the flue gas purification tower, added to a blowing system for pre-adding dust by an automatic feeder at the bottom of the dust storage hopper, blown into the flue gas purification tower and mixed with the flue gas to adsorb components of the flue gas. The pre-added dust is recycled and replaced periodically.

After the flue gas is purified by the flue gas purification tower, the gas still contains nitric oxide and nitrogen dioxide with higher concentration, wherein the nitric oxide is not easy to absorb and needs to be oxidized into the nitrogen dioxide so as to increase the absorption efficiency of the reduction absorption tower on the nitrogen oxide. The main component of the oxidation absorption liquid is sodium chlorite, and the main chemical reaction is as follows:

4NO+3NaCLO₂+2H₂O→4HNO₃+3NaCL

HNO₃+NaOH→NaNO₃+2H₂O

the oxidation absorption liquid is conveyed into the tower by a pump and sprayed by a nozzle, and the flue gas is fully contacted with the oxidation liquid in the oxidation absorption tower to carry out chemical reaction to generate sodium chloride and sodium nitrate. The spraying liquid falls into a liquid storage tank at the bottom of the tower and is pumped out by a pump for spraying, and the oxidizing liquid is recycled.

After a period of time, the oxidation liquid is collected into a waste liquid storage tank by a waste liquid collecting system after being invalid. The main components in the waste liquid are sodium chloride and sodium nitrate generated by reaction, and can be used as the components of raw materials, and the diluted waste liquid enters the raw materials for recycling and comprehensive utilization.

After the flue gas is treated by the oxidation absorption tower, the main component is nitrogen dioxide and a small amount of nitric oxide is contained. The main components of the reduction absorption liquid are urea and sodium hydroxide. The urea is decomposed to generate ammonia, the ammonia gas and nitric oxide and nitrogen dioxide in the flue gas generate chemical reaction, and the nitrogen oxide is reduced into nitrogen gas and discharged through an exhaust funnel. The sodium hydroxide in the absorption liquid reacts with nitrogen dioxide to produce sodium nitrate, and the main chemical reaction is as follows:

6NO+4NH₃→5N₂+6H₂O

6NO₂+8NH₃→7N₂+12H₂O

NO₂+2NaOH→NaNO₂+H₂O

the operation mode of the reduction absorption tower is the same as that of the oxidation absorption tower. The reduction absorption liquid is collected into a waste liquid storage tank by a waste liquid collecting system after being used and failed for a period of time. The main component in the waste liquid is sodium nitrate generated by reaction, and can be used as a component of a raw material, and the sodium nitrate is diluted and then enters the raw material to be recycled and comprehensively used.

The absorption liquid used by the tail end absorption tower is mainly clear water, and nitrate generated by the first 2 towers, unreacted oxidation liquid and reduction absorption liquid are washed down. If the flue gas produced in the production process contains high concentration of sulfur dioxide, the absorption liquid used by the absorption tower can be changed into 5-10% sodium hydroxide solution, and reacts with the sulfur dioxide to generate sodium sulfate, and the main chemical reaction is as follows:

SO₂+NaOH→Na₂SO₄+H₂O

the operation mode of the tail end absorption tower is the same as that of the oxidation absorption tower and the reduction absorption tower. The absorption liquid is collected into a waste liquid storage tank by a waste liquid collecting system after being used and failed for a period of time. The main components in the waste liquid are sodium nitrate and sodium sulfate which can be used as the components of raw materials, and the waste liquid is diluted and then enters the raw materials for recycling and comprehensive use.

Compared with the prior art, the invention has the beneficial effects that:

the purification efficiency of the invention to the nitrogen oxide is 90-95%, and the emission concentration of the nitrogen oxide in the tail gas of the electric furnace after the purification by the invention can be lower than 400mg/m³。

Drawings

FIG. 1 is a schematic structural diagram of a tail gas nitrogen oxide purification device of a glass electric furnace;

FIG. 2 is a schematic flow diagram of a purification system;

in the figure: 1. a flue gas purification tower; 11. a filter bag; 12. a compressed air blowback ash removal system; 121. a compressed air conduit; 122. a pressure reducing valve; 123. a pulse control valve; 124. a pulse jet pipe; 13. a pre-dust-feeding system; 131. an automatic feeder; 132. a blowing pipe; 133. an injection fan; 134. a dust storage hopper; 2. an oxygen absorption tower; 21. a filler layer; 22. a liquid storage tank; 23. a spray system; 231. a shower pipe; 232. a spray head; 233. a spray pump; 24. a fluid infusion system; 25. a waste liquid collection system; 3. a reduction absorption tower; 4. a terminal absorber; 5. an exhaust funnel; 6. a flue gas buffer; 7. an air inlet pipe; 8. connecting an air pipe; 9. a centrifugal ventilator.

Detailed Description

Embodiments of the invention are further described below with reference to the accompanying drawings:

as shown in fig. 1 and 2, a glass electric furnace tail gas nitrogen oxide purification device, including flue gas purification tower 1, oxygen absorption tower 2, reduction absorption tower 3, terminal absorption tower 4 and flue gas buffer 6, the air inlet and the air-supply line 7 of flue gas buffer 6 communicate, the gas outlet of flue gas buffer 6 communicates through the air intake of tuber pipe and flue gas purification tower 1, the air outlet of flue gas purification tower 1 side upper end is through connecting tuber pipe 8, centrifugal fan 9 communicates with the air intake of oxygen absorption tower 2, the air outlet at oxygen absorption tower 2 top communicates with the air intake of reduction absorption tower 3 through connecting tuber pipe 8, the air outlet at reduction absorption tower 3 top communicates with the air intake of terminal absorption tower 4 through connecting tuber pipe 8, the air outlet and the exhaust stack 5 intercommunication at terminal absorption tower 4 top.

The flue gas purification tower 1 is provided with a cylinder body, a filter bag 11, a compressed air back-blowing ash removal system 12 and a pre-dust addition system 13, wherein the filter bag 11 is arranged in a body cavity of the cylinder body of the flue gas purification tower 1, the compressed air back-blowing ash removal system 12 is arranged at the upper end of the flue gas purification tower 1, and the pre-dust addition system 13 is arranged at the bottom of the flue gas purification tower 1. The flue gas is mixed with pre-added dust in the flue gas purification tower 1 to absorb the components of the flue gas.

The compressed air blowback ash removal system 12 comprises a compressed air pipeline 121, a pressure reducing valve 122, a pulse control valve 123 and a pulse spray pipe 124, wherein the pulse spray pipe 124 is arranged above the filter bag 11 in the body cavity of the flue gas purification tower 1. The compressed air blowback ash removal system 12 is used for blowing dust from the filter bag 11 to the ash storage hopper 134.

The pre-dust-adding system 13 comprises an automatic feeder 131, a blowing pipe 132, a blowing fan 133 and a dust storage hopper 134, wherein the dust storage hopper 134 is arranged at the bottom of the cylinder of the flue gas purification tower 1, and the bottom of the dust storage hopper 134 is communicated with the upper end of the side surface of the dust storage hopper 134 through the automatic feeder 131, the blowing pipe 132 and the blowing fan 133. The pre-dust can be recycled, and when the color of the pre-dust is changed, new dust is replaced.

The oxygen absorption tower 2 is provided with a cylinder, a packing layer 21, a liquid storage tank 22 and a spraying system 23, the oxygen absorption tower 2 is connected with a liquid supplementing system 24 and a waste liquid collecting system 25, the packing layer 21 is arranged in a body cavity of the cylinder of the oxygen absorption tower 2, and the liquid storage tank 22 is arranged at the lower end of the oxygen absorption tower 2. The flue gas converts most of the nitric oxide into nitrogen dioxide in the oxygen absorption tower 2 so as to increase the absorption rate of the nitrogen oxide by the reduction absorption tower 3.

The reduction absorption tower 3 is provided with a cylinder, a packing layer 21, a liquid storage tank 22 and a spraying system 23, the reduction absorption tower 3 is connected with a liquid supplementing system 24 and a waste liquid collecting system 25, the packing layer 21 is arranged in a body cavity of the cylinder of the reduction absorption tower 3, and the liquid storage tank 22 is arranged at the lower end of the reduction absorption tower 3. The main function of the reduction absorption tower 3 is to absorb nitrogen oxides in the flue gas.

The tail end absorption tower 4 is provided with a cylinder body, a packing layer 21, a liquid storage tank 22 and a spraying system 23, the tail end absorption tower 4 is connected with a liquid supplementing system 24 and a waste liquid collecting system 25, the packing layer 21 is arranged in a body cavity of the cylinder body of the tail end absorption tower 4, and the liquid storage tank 22 is arranged at the lower end of the tail end absorption tower 4. The absorption liquid used by the tail end absorption tower 4 is mainly clear water, nitrate produced by the front tower 2, unreacted oxidation liquid and reduction absorption liquid are washed in the tail end absorption tower 4, and if the concentration of sulfur dioxide in flue gas produced in the production process is high, the absorption liquid used by the absorption tower can be changed into 5-10% sodium hydroxide solution to react with the sulfur dioxide to generate sodium sulfate.

The spraying system 23 comprises a spraying pipe 231, a spraying head 232 and a spraying pump 233, the spraying head 232 is arranged in the cavity of the cylinder body, one end of the spraying pump 233 is connected with the liquid storage tank 22 through the spraying pipe 231, and the other end of the spraying pump 233 is connected with the spraying head 232 through the spraying pipe 231. The absorption liquid is recycled under the action of the spraying system 23, and the absorption liquid is recovered and replaced after the absorption liquid is invalid.

The height of the discharge port of the exhaust funnel 5 from the ground is 16 meters.

The flue gas of the electric furnace is sucked into the flue gas purification tower 1 by the centrifugal fan, is fully mixed with the dust which enters the flue gas purification tower 1 by the pre-dust adding system 13, adsorbs the flue gas components to the pre-added dust particles, and is filtered by the filter bag 11, thereby achieving the purpose of purifying the flue gas. The dust adhered to the filter bag 11 is cleaned from the filter bag 11 by the compressed air back-blowing ash-cleaning system 12, and is settled in the ash storage hopper 134 at the lower part of the flue gas purification tower 1, and is added to the pre-dust-adding blowing system by the automatic feeder 131 at the bottom of the ash storage hopper 134, and is blown into the flue gas purification tower 1 to be mixed with the flue gas, so as to adsorb the components of the flue gas. The pre-added dust is recycled and replaced periodically.

After the flue gas is purified by the flue gas purification tower 1, the gas still contains nitric oxide and nitrogen dioxide with higher concentration, wherein the nitric oxide is not easy to absorb and needs to be oxidized into nitrogen dioxide so as to increase the absorption efficiency of the reduction absorption tower 3 on nitrogen oxides. The main component of the oxidation absorption liquid is sodium chlorite, and the main chemical reaction is as follows:

4NO+3NaCLO₂+2H₂O→4HNO₃+3NaCL

HNO₃+NaOH→NaNO₃+2H₂O

the oxidation absorption liquid is conveyed into the oxidation absorption tower 2 by a pump and is sprayed by a nozzle, and the flue gas is fully contacted with the oxidation liquid in the oxidation absorption tower 2 to carry out chemical reaction to generate sodium chloride and sodium nitrate. The spray liquid falls into a liquid storage tank 22 at the bottom of the tower and is pumped out by a spray pump 233 for spraying, and the oxidizing liquid is recycled.

After a period of use, the spent oxidizing solution is collected by the waste solution collection system 25 into the waste solution storage tank. The main components in the waste liquid are sodium chloride and sodium nitrate generated by reaction, and can be used as the components of raw materials, and the diluted waste liquid enters the raw materials for recycling and comprehensive utilization.

After the flue gas is treated by the oxidation absorption tower 2, the main component is nitrogen dioxide and a small amount of nitric oxide is contained. The main components of the reduction absorption liquid are urea and sodium hydroxide. The urea is decomposed to generate ammonia, the ammonia gas and nitric oxide and nitrogen dioxide in the flue gas generate chemical reaction, and the nitrogen oxide is reduced into nitrogen gas and discharged through an exhaust funnel. The sodium hydroxide in the absorption liquid reacts with nitrogen dioxide to produce sodium nitrate, and the main chemical reaction is as follows:

6NO+4NH₃→5N₂+6H₂O

6NO₂+8NH₃→7N₂+12H₂O

NO₂+2NaOH→NaNO₂+H₂O

the reduction absorption tower 3 operates in the same manner as the oxidation absorption tower 2. The reduction absorption liquid is collected into a waste liquid storage tank by a waste liquid collection system 25 after being used for a period of time and being invalid. The main component in the waste liquid is sodium nitrate generated by reaction, and can be used as a component of a raw material, and the sodium nitrate is diluted and then enters the raw material to be recycled and comprehensively used.

The absorption liquid used by the tail end absorption tower 4 is mainly clear water, and nitrate generated by the first two towers, unreacted oxidation liquid and reduction absorption liquid are washed down. If the flue gas produced in the production process contains high concentration of sulfur dioxide, the absorption liquid used by the absorption tower can be changed into 5-10% sodium hydroxide solution, and reacts with the sulfur dioxide to generate sodium sulfate, and the main chemical reaction is as follows:

SO₂+NaOH→Na₂SO₄+H₂O

the terminal absorption tower 4 operates in the same manner as the oxidation absorption tower 2 and the reduction absorption tower 3. The absorption liquid is collected by the waste liquid collection system 25 into the waste liquid storage tank after being used for a while and being exhausted. The main components in the waste liquid are sodium nitrate and sodium sulfate which can be used as the components of raw materials, and the waste liquid is diluted and then enters the raw materials for recycling and comprehensive use.

The purification efficiency of the invention to the nitrogen oxide is 90-95%, and the emission concentration of the nitrogen oxide in the tail gas of the electric furnace after the purification by the invention can be lower than 400mg/m³。