Industrial tail gas recycling treatment method and recycling treatment system

Abstract

The present invention discloses a method for recycling and treating industrial tail gas. The industrial tail gas (i.e., flue gas) to be purified is passed through a purification tower for pollutant removal treatment. When the flue gas after removal treatment does not meet emission standards, a portion of the flue gas discharged from the purification tower is switched through two circulation pipelines and recirculated into the purification tower for pollutant removal treatment. One circulation pipeline recirculates the flue gas from the upper part of the purification tower's exhaust outlet into the lower part of the purification tower's flue gas inlet. The other circulation pipeline recirculates the flue gas from the lower part of the purification tower's exhaust outlet into the upper part of the purification tower's flue gas inlet. When one circulation pipeline is recirculating the flue gas, the connection between the other circulation pipeline and the outlet and inlet of the purification tower is closed. The present invention utilizes the switching of the circulation pipelines to recirculate and purify the flue gas, further reducing the emission of pollutants such as sulfur dioxide and nitrogen oxides.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial tail gas purification, and particularly relates to an industrial tail gas recycling treatment process. Background Art

[0002] Industrial exhaust gases from industries such as steel, chemical, and power generation contain atmospheric pollutants such as sulfur dioxide and nitrogen oxides. The resulting secondary pollutants, such as sulfuric acid fumes and photochemical smog, are seriously harmful to humans, buildings, and materials. National and local governments have strict standards and regulations for exhaust emissions from various industries. Existing technologies for treating industrial exhaust pollutants have certain technical defects. On the one hand, due to the performance of the degassing agent or the structure of the degassing tower, the degassing agent and exhaust gas do not flow well in the degassing tower, and the degassing agent and pollutants cannot fully participate in the decontamination reaction, resulting in waste of degassing agent and poor pollutant removal rate. On the other hand, new degassing agents need to be added to remove existing pollutants in the exhaust gas. For example, in the selective catalytic reduction denitrification technology, ammonia spraying is required, and new degassing agents that do not participate in the reaction will cause secondary pollution. Summary of the Invention

[0003] The purpose of the present invention is to solve the defects in the prior art and provide a treatment process which has a simple structure and does not require the addition of new removal agents while being able to achieve efficient removal of pollutants in tail gas and meet emission standards.

[0004] In order to achieve the above-mentioned purpose, the present invention provides an industrial exhaust gas circulation treatment method, in which the industrial exhaust gas (i.e., flue gas) to be purified is subjected to pollutant removal treatment through a purification tower; when the flue gas emission after removal treatment does not meet the standards, a part of the flue gas discharged from the purification tower is switched through two circulation pipelines and recycled into the purification tower for pollutant removal treatment; one of the circulation pipelines recirculates the flue gas from the upper part of the purification tower exhaust port into the lower part of the purification tower flue gas inlet; the other circulation pipeline recirculates the flue gas from the lower part of the purification tower exhaust port into the upper part of the purification tower flue gas inlet; when one circulation pipeline is recycling the flue gas, the connection between the other circulation pipeline and the exhaust port and inlet of the purification tower is closed.

[0005] The flue gas is recirculated and purified using a circulating pipeline, eliminating the need to add new decontamination agents. Two switching paths are set up simultaneously. By opening and closing each pipeline during the switching process, the flow of flue gas in the purification tower is improved, preventing inadequate purification of flue gas in certain areas of the tower, and facilitating the complete removal of pollutants in the flue gas.

[0006] Furthermore, baffle doors are respectively provided at the upper and lower ends of the two circulation pipelines corresponding to the flue gas inlet of the purification tower, and the pipeline sections of the two circulation pipelines connected to the flue gas inlet of the purification tower are respectively provided with switch valves, and the two circulation pipelines are switched by opening and closing the corresponding baffle doors and switch valves; the pipeline sections connected to the flue gas outlet of the purification tower are respectively provided with regulating valves; and circulation fans are respectively provided on the two circulation pipelines; and the recirculating flue gas flow rate of each circulation pipeline is adjusted by the regulating valves and circulation fans.

[0007] Through the regulating valve and circulating fan, the recirculating flue gas flow rate can be adjusted according to the changes in the pollutant content in the inlet flue gas (industrial exhaust gas to be purified), ensuring the purification effect of the outlet flue gas pollutants and saving the operating energy consumption of the flue gas circulation pipeline.

[0008] Furthermore, when the two circulation pipelines are switched, the switch valve of the circulation pipeline to be switched is opened first, and then the regulating valve and circulation fan of the circulation pipeline being operated are closed. Then, the damper door and switch valve at the flue gas inlet corresponding to the circulation pipeline to be switched are opened, and at the same time, the damper door and switch valve at the flue gas inlet corresponding to the circulation pipeline being operated are closed. Finally, the regulating valve and circulation fan of the circulation pipeline to be switched are opened, thereby realizing the switching operation of the two circulation pipelines.

[0009] During the switching and alternating operation of the two circulation pipelines, by gradually opening or closing the switch valves on the branch pipes of the flue gas input pipeline and the flue gas output pipeline, the baffle door of the air intake manifold, the regulating valves and circulation fans on each circulation pipeline, while ensuring the qualified pollutant emissions, it also reduces the adjustment disturbance during the alternating operation of the circulation pipelines, ensuring the stable operation of the system.

[0010] Furthermore, the interval time for switching between the two circulation pipelines is consistent with the time required for the pollutants and the removal agent in the purification tower to fully react.

[0011] The present invention also provides a circulation treatment system for the above-mentioned industrial exhaust gas circulation treatment method, which adopts a purification tower; the flue gas inlet and the flue gas outlet of the purification tower are respectively connected through two circulation pipelines arranged on the outside; the two circulation pipelines respectively connect the upper part of the flue gas inlet and the lower part of the flue gas outlet, and the lower part of the flue gas inlet and the upper part of the flue gas outlet; each circulation pipeline is respectively provided with a circulation fan and a regulating valve.

[0012] Furthermore, the circulation treatment system also includes a flue gas input collection pipeline, a flue gas input pipeline branch pipeline, a flue gas output collection pipeline and a flue gas output pipeline branch pipeline; the flue gas input pipeline branch pipeline and the flue gas output pipeline branch pipeline are respectively provided with two; the industrial exhaust gas to be purified is divided into two paths through the flue gas input collection pipeline, and enters the upper and lower parts of the flue gas inlet of the purification tower through the two flue gas input pipeline branch pipelines respectively, and is respectively connected to the two circulation pipelines; the flue gas after removal treatment by the purification tower is respectively discharged from the lower and upper parts of the flue gas outlet of the purification tower through the two flue gas output pipeline branch pipelines; the two flue gas output pipeline branch pipelines are respectively connected to the corresponding two circulation pipelines.

[0013] Furthermore, an air intake manifold is provided at the flue gas inlet of the purification tower; two flue gas input pipeline branch pipes are respectively connected to the upper and lower parts of the air intake manifold; and baffle doors are respectively provided at the upper and lower parts of the connection between the air intake manifold and the purification tower.

[0014] Furthermore, an air outlet manifold is provided at the flue gas outlet of the purification tower; the upper and lower parts of the air outlet manifold are respectively connected to the branch pipes of the corresponding two flue gas output pipelines.

[0015] Furthermore, switch valves are respectively provided on the front ends of the branch pipes of the two flue gas input pipelines and the places where they are connected with the circulation pipeline.

[0016] Furthermore, switch valves are respectively provided on the rear ends of the branch pipes of the two flue gas output pipelines and the connections with the circulation pipeline.

[0017] The circulation fan adopts a variable frequency fan.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The present invention utilizes a circulation pipeline to recirculate, remove and purify the flue gas, thereby further reducing the emission of pollutants such as sulfur dioxide and nitrogen oxides.

[0020] The connection between the circulation pipeline and the purification tower promotes the full reaction between the decontaminant and the pollutants in various parts of the flue gas purification tower, improves the utilization rate of the decontaminant, and reduces the consumption of the decontaminant. The size of the purification tower required to treat the same amount of flue gas pollutants is reduced, saving system construction costs.

[0021] At the same time, the multi-channel design of the flue gas circulation pipeline utilizes the changes in the opening and closing of each flue gas circulation pipeline to improve the flow of flue gas in the tower, prevent insufficient local flue gas purification in the tower, and is conducive to the complete removal of flue gas pollutants.

[0022] The present invention does not require the addition of new removal agents to participate in the pollutant removal reaction, thereby preventing the escape of pollutants and causing secondary pollution.

[0023] The circulation pipeline is equipped with a circulation fan and a regulating valve. According to the changes in the content of inlet flue gas pollutants, the flue gas flow in the flue gas circulation pipeline is adjusted to ensure the purification effect of outlet flue gas pollutants and save the operating energy consumption of the flue gas circulation pipeline.

[0024] During the alternating operation of the flue gas circulation pipeline, by gradually opening or closing the switch valves on the branch pipes of the flue gas input pipeline and the flue gas output pipeline, the baffle door of the air intake manifold, the regulating valves and the circulation fans on each circulation pipeline, while ensuring the qualified discharge of pollutants, it also reduces the adjustment disturbance during the alternating operation of the circulation pipeline, ensuring the stable operation of the system.

[0025] An air intake manifold is set at the flue gas inlet of the purification tower. By timely opening and closing the upper baffle doors of the air intake manifold, the flue gas is prevented from staying in the purification tower for insufficient time during the alternating operation of the circulation pipeline, thereby affecting the flue gas purification effect.

[0026] The circulation treatment system of the present invention has a simple structure, a short construction period, low cost, and wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of the circulation treatment system of the present invention;

[0028] Figure 2 for Figure 1 System flue gas flow diagram when the middle circulation pipeline 3 is running;

[0029] Figure 3 for Figure 1 System flue gas flow diagram when the middle circulation pipeline 4 is running;

[0030] Figure 4 for Figure 1 Flue gas flow diagram in the purification tower when the intermediate circulation pipeline 3 is in operation;

[0031] Figure 5 for Figure 1 Schematic diagram of the flue gas flow direction during the conversion operation of the intermediate circulation pipeline 3 to the circulation pipeline 4;

[0032] Figure 6 for Figure 1 Schematic diagram of flue gas flow direction when the intermediate circulation pipeline 4 is in operation.

[0033] In the figure, 1-flue gas input collection pipeline, 2-flue gas output collection pipeline, 1-1, 1-2, 2-1, 2-2-switch valves, 3, 4-flue gas circulation pipelines, 3-1, 4-1-regulating valves, 3-2, 4-2 circulation fans, 5-purification tower body, 6-air inlet manifold, 7, 8-baffle doors, 9-air outlet manifold. DETAILED DESCRIPTION

[0034] like Figure 1 As shown, the industrial tail gas recycling treatment system of the present invention includes a flue gas input pipeline, a flue gas purification tower 5, a flue gas output pipeline, and flue gas circulation pipelines 3 and 4. The flue gas input pipeline and the flue gas output pipeline are respectively composed of a collection pipeline (flue gas input collection pipeline 1 and flue gas output collection pipeline 2) and a branch pipeline, each branch pipeline is equipped with a switch valve 1-1, 1-2, 2-1, and 2-1; the flue gas purification tower includes an air inlet manifold 6, a purification tower body 5, and an air outlet manifold 9, wherein the air inlet manifold 6 is equipped with baffle doors 7 and 8 corresponding to each flue gas input pipeline branch pipeline; each flue gas circulation pipeline is equipped with an adjustable opening regulating valve 3-1 and 4-1 and a variable frequency circulation fan 3-2 and 4-2.

[0035] The operation process of the circulation treatment system of the present invention:

[0036] 1. When the flue gas circulation pipeline is closed and the flue gas emissions meet the standards, the on-off valve 1-1 (or on-off valve 1-2) on the branch pipe of the flue gas input pipeline is opened, the damper door 8 (or damper door 7) on the air intake manifold 6 is opened, the on-off valve 2-1 (or on-off valve 2-2) on the branch pipe of the flue gas output pipeline is opened, the regulating valve 3-1 and regulating valve 4-1 on the flue gas circulation pipeline are closed, and the circulation fans 3-2 and 4-2 on the flue gas circulation pipeline are turned off. Flue gas enters the flue gas input and collection pipeline 1, passes through the on-off valve 1-1 (or on-off valve 1-2) on the branch pipe of the flue gas input pipeline, flows through the damper door 8 (or damper door 7) on the air intake manifold 6 of the flue gas purification tower, enters the flue gas purification tower body 5 for purification, and then flows into the flue gas purification tower's outlet manifold 9. It then passes through the on-off valve 2-1 (or on-off valve 2-2) on the branch pipe of the flue gas output pipeline and is discharged from the flue gas output and collection pipeline 2.

[0037] 2. When the flue gas circulation pipeline is closed and the flue gas emission does not meet the standard, the switch valve 1-1 (or switch valve 1-2) on the branch pipe of the flue gas input pipeline is opened, the baffle door 8 (or baffle door 7) on the air inlet manifold 6 is opened, the switch valve 2-1 (or switch valve 2-2) on the branch pipe of the flue gas output pipeline is opened, the regulating valve 3-1 (or regulating valve 4-1) on the flue gas circulation pipeline is opened, and the circulation fan 3-2 (or circulation fan 4-2) on the flue gas circulation pipeline is started. The flue gas enters from the flue gas input collection pipeline 1, passes through the switch valve 1-1 (or switch valve 1-2) on the branch pipeline of the flue gas input pipeline, flows through the baffle door 8 (or baffle door 7) on the flue gas purification tower air inlet manifold 6, is purified by the flue gas purification tower body 5, and flows into the flue gas purification tower air outlet manifold 9. After the flue gas flows out of the air outlet manifold 9, a part of it is introduced by the circulation fan 3-2 (or circulation fan 4-2), flows through the regulating valve 3-1 (or regulating valve 4-1), and enters the branch pipeline of the flue gas input pipeline behind the switch valve 1-1 (or switch valve 1-2). The other part flows through the switch valve 2-1 (or switch valve 2-2) on the branch pipeline of the flue gas output pipeline and is discharged from the flue gas output collection pipeline 2. Figure 2 (or Figure 3 ) as shown.

[0038] (1) During the operation of the flue gas circulation pipeline 3 (or the circulation pipeline 4), when the concentration of pollutants in the flue gas increases (or decreases), the opening of the regulating valve 3-1 (or the regulating valve 4-1) can be increased (or decreased) and the frequency of the circulation fan 3-2 (or the circulation fan 4-2) can be increased (or decreased) to increase (or decrease) the amount of flue gas in the flue gas circulation pipeline. This ensures that the pollutant emissions meet the standards while maintaining the economic efficiency of energy consumption.

[0039] (2) When the operation time of the flue gas circulation pipeline 3 (or circulation pipeline 4) is close to the time for the pollutants and the remover to react completely in the flue gas purification tower body 5, the flue gas circulation pipeline 3 and the circulation pipeline 4 need to be operated alternately. Taking the flue gas circulation switching from the circulation pipeline 3 to the circulation pipeline 4 as an example, the flue gas flow situation when the flue gas circulation pipeline 3 is in operation is as follows: Figure 4 When the circulation pipeline 3 is replaced by the circulation pipeline 4, the switch valve 1-2 on the branch pipeline connected to the circulation pipeline 4 on the flue gas input pipeline is opened first, and the flue gas flow is as follows. Figure 5 As shown in Figure (a); then close the regulating valve 3-1 and the circulating fan 3-2 on the circulating pipeline 3, and the flue gas flow direction is as follows Figure 5 As shown in Figure (b); then open the damper door 7 on the air intake manifold 6 and the switch valve 2-2 on the branch pipe of the smoke output pipeline, and at the same time close the damper door 8 on the air intake manifold 6 and the switch valve 1-1 on the branch pipe of the smoke input pipeline. The smoke flow is as follows Figure 5 As shown in Figure (c); Finally, open the regulating valve 4-1 and the circulating fan 4-2 on the circulation pipeline 4. After completion, the flue gas flow direction is as follows Figure 6 As shown, the process of circulating line 4 replacing circulating line 3 is completed.

Claims

1. A method for recycling industrial tail gas, wherein the industrial tail gas to be purified is passed through a purification tower for pollutant removal treatment; characterized in that: When the flue gas emissions after removal treatment do not meet the standards, part of the flue gas discharged from the purification tower is switched through two circulation pipelines and recirculated into the purification tower for pollutant removal treatment; The exhaust gas of the gas vents in the exhaust gas fan is passed through the exhaust gas fan of the gas vents in the air filter, and then is exhausted from the exhaust gas inlet of the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents in the gas vents. The two circulation pipelines are switched by opening and closing the damper door and the switch valve; the pipeline sections connected to the flue gas outlet of the purification tower are respectively provided with regulating valves; the two circulation pipelines are respectively provided with circulation fans; the recirculating flue gas flow rate of each circulation pipeline is adjusted by regulating valves and circulation fans; when the two circulation pipelines are switched, first open the switch valve of the circulation pipeline to be switched, then close the regulating valve and circulation fan of the circulation pipeline being run, and then open the damper door at the flue gas inlet of the purification tower corresponding to the circulation pipeline to be switched, and at the same time close the damper door and the switch valve at the flue gas inlet of the purification tower corresponding to the circulation pipeline being run, and finally open the regulating valve and circulation fan of the circulation pipeline to be switched, thereby realizing the switching operation of the two circulation pipelines.

2. The industrial tail gas recycling treatment method according to claim 1, characterized in that: The interval time for switching the two circulation pipelines is consistent with the time it takes for the pollutants and the remover in the purification tower to completely react.

3. A circulating treatment system using the industrial tail gas recycling treatment method according to claim 1 or 2, wherein the circulating treatment system uses a purification tower; characterized in that: The flue gas inlet and the flue gas outlet of the purification tower are respectively connected by two circulation pipelines arranged on the outside; the two circulation pipelines respectively connect the upper part of the flue gas inlet and the lower part of the flue gas outlet, and the lower part of the flue gas inlet and the upper part of the flue gas outlet; a circulation fan and a regulating valve are respectively provided on each circulation pipeline; the circulation treatment system also includes a flue gas input summary pipeline, a flue gas input pipeline branch pipeline, a flue gas output summary pipeline and a flue gas output pipeline branch pipeline; the flue gas input pipeline branch pipeline and the flue gas output pipeline branch pipeline are respectively provided with two; the two flue gas output pipeline branch pipelines are respectively connected to the corresponding two circulation pipelines; an air intake manifold is provided at the flue gas inlet of the purification tower; the two flue gas input pipeline branch pipelines are respectively connected to the upper and lower parts of the air intake manifold; the upper and lower parts of the connection between the air intake manifold and the purification tower are respectively provided with baffle doors.

4. The recycling treatment system according to claim 3, characterized in that: An air outlet manifold is provided at the flue gas outlet of the purification tower; the upper part and the lower part of the air outlet manifold are respectively connected to the branch pipes of the corresponding two flue gas output pipelines.

5. The circulation treatment system according to claim 4, characterized in that: On the two flue gas input pipeline branch pipes, the front ends of the connection points with the circulation pipeline are respectively provided with switch valves; on the two flue gas output pipeline branch pipes, the rear ends of the connection points with the circulation pipeline are respectively provided with switch valves.

6. The recycling treatment system according to claim 5, characterized in that: The circulating fan adopts a variable frequency fan.

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