Tail gas self-circulation white feather eliminating device and method

Abstract

The invention relates to a tail gas self-circulation white feather eliminating device and a tail gas self-circulation white feather eliminating method, and solves the problems of poor white feather eliminating effect and high cost of the existing industrial tail gas. Comprising a quench tower, an absorption tower, a gas-gas heat exchanger, an electric precipitator and a tail gas suction fan, during use, dry high-temperature tail gas enters a heat exchange pipe in the gas-gas heat exchanger for indirect heat exchange, and the tail gas subjected to heat exchange enters the quench tower and is in countercurrent contact with quench water from the quench tower; the washed and condensed tail gas is discharged to the lower part of the absorption tower from the top of the quench tower under the action of the circulating fan, and the dried tail gas enters the electrostatic dust collector to be purified after being absorbed and filtered by the absorption filtering device from the absorption circulating pump, and then enters the shell of the gas-gas heat exchanger to be subjected to indirect heat exchange; the purified tail gas is heated by the unpurified tail gas and then is discharged into the environment, namely the tail gas is heated to an unsaturated state by the heat of the tail gas, so that the aim of eliminating white feather of the tail gas is fulfilled, and the production cost is low.

Description

Technical Field

[0001] The invention relates to the field of industrial tail gas treatment, and in particular to a tail gas self-circulation white plume elimination device and method. Background Art

[0002] "White plume" is also called "white smoke plume". During the industrial production process, the exhaust gas discharged from the chimney mixes with the ambient cold air. During the cooling process, the water vapor contained in the exhaust gas condenses to saturation. The water mist produced by condensation appears like white feathers under the refraction and scattering of light, thus called "white plume". In the existing petrochemical and chemical production, more than 80% of the process requires the use of catalysts. Catalyst preparation mainly includes five processes: colloid synthesis, spray drying, high-temperature roasting, filtration and water washing, and airflow drying. A certain amount of high-temperature dust-containing gas will be generated during spray drying, high-temperature roasting and airflow drying. This part of the gas needs to be purified and absorbed before it can be discharged into the atmosphere. Among them, the spray drying process (150~180℃) and the airflow drying process (140~150℃) produce a large flow rate of exhaust gas, high dust content, and the most serious tailing phenomenon. Whether this problem can be effectively solved is also the most urgent. At present, the treatment methods for dry exhaust gas at home and abroad mainly include washing, washing + electrostatic precipitator combination technology, etc. After washing and dust removal, the temperature of the dry exhaust gas drops to about 40℃~50℃ and then is discharged into the atmosphere. Since the dry exhaust gas discharged into the atmosphere is in a saturated state, when the ambient temperature is low, the exhaust gas enters the surrounding environment through the external discharge port, and the water vapor quickly condenses into small droplets, and a "white smoke area" appears above the exhaust gas external discharge port, commonly known as "white feather". Compared with single washing technology, the combination of washing + electrostatic precipitator technology has better dust removal and demisting effects, and reduces the moisture content of exhaust gas. However, in areas with cold climatic conditions, especially in winter, the "white feather" phenomenon still exists.

[0003] At present, many countries, including foreign countries, have adopted electrostatic precipitator and mist removal technology, which has been widely used in chemical, metallurgical, atmospheric governance and other industries. Although this technology has a good mist removal effect, it still cannot achieve the purpose of eliminating "white feathers". At the same time, this technology has the disadvantages of high investment and high production cost. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing industrial tail gas "white plume" elimination effect is poor and the cost is high.

[0005] The technical solution adopted to solve the technical problem proposed by the present invention is: The self-circulating white-feather elimination device for tail gas of the present invention comprises a quenching tower and an absorption tower, wherein the quenching tower is provided with a quenching and cooling device, and the absorption tower is provided with an absorption and filtering device. The white-feather elimination device also comprises an air-to-air heat exchanger, an electrostatic precipitator and an exhaust gas suction fan. The air-to-air heat exchanger comprises a sealed heat exchanger shell and a heat exchange pipe arranged in the heat exchanger shell, the air inlet end of the heat exchange pipe is connected with the exhaust gas discharge port, the air outlet end of the heat exchange pipe is connected with the air inlet of the quenching tower, a quenching water nozzle is provided in the quenching tower, and the quenching water nozzle is arranged above the air inlet of the quenching tower, a circulating fan is arranged between the air outlet of the quenching tower and the air inlet of the absorption tower, the air outlet of the absorption tower is connected with the air inlet of the electrostatic precipitator, the air outlet of the electrostatic precipitator is connected with the air inlet of the exhaust gas suction fan, a circulating air inlet connected with the air outlet of the exhaust gas suction fan is provided on the heat exchanger shell, and an external exhaust gas outlet is also provided on the heat exchanger shell.

[0006] The method for eliminating white plume by self-circulating tail gas using the tail gas self-circulating white plume eliminating device of the present invention comprises the following steps: Step A: The dry high-temperature exhaust gas enters the heat exchange tube in the gas-to-gas heat exchanger for indirect heat exchange. The heat exchange tube passes through the shell of the gas-to-gas heat exchanger, and the heat exchange tube and the shell of the gas-to-gas heat exchanger form an independent sealed space; Step B: The tail gas after heat exchange enters the quenching tower and is countercurrently contacted with the quenching water from the quenching tower. Part of the dust and water vapor carried in the tail gas is washed and condensed, and a small part of the gas dissolved in water is absorbed; Step C: The tail gas after washing and condensation is discharged from the top of the quenching tower to the bottom of the absorption tower under the action of the circulating fan. The dry tail gas and the air from the absorption circulating pump are absorbed and filtered by the absorption and filtering device, and the harmful gases carried in the dry tail gas are absorbed; Step D: The dry tail gas after absorption treatment then enters the electrostatic precipitator to further remove solid particles and other substances therein; Step F: The dry exhaust gas after electrostatic dust removal enters the shell of the air-to-air heat exchanger under the action of the exhaust gas suction fan, and the purified exhaust gas exchanges heat with the unpurified exhaust gas in the heat exchange tube. The purified exhaust gas is heated by the unpurified exhaust gas and then discharged into the environment.

[0007] The technical solutions for further limiting the present invention include: The white feather elimination device also includes a quenching tower circulation pump. A quenching tower water tank is provided at the bottom of the quenching tower. The water inlet of the quenching tower circulation pump is connected to the bottom of the quenching tower water tank, and the water outlet of the quenching tower circulation pump is connected to the quenching water nozzle.

[0008] The water outlet of the quench tower circulation pump is connected to the quench tower sewage outlet.

[0009] The rapid cooling device is a water-cooling ring pipe arranged in the shell wall of the rapid cooling tower.

[0010] The white feather elimination device also includes an absorption tower circulation pump. The absorption and filtration device is arranged at the upper part of the absorption tower. The absorption and filtration device includes a packing layer, a spray pipe and a demister. The spray pipe is arranged above the corresponding packing layer. The demister is arranged at the top of the absorption tower. The bottom of the absorption tower is provided with an absorption tower water tank. The water inlet of the absorption tower circulation pump is connected to the bottom of the absorption tower water tank, and the water outlet of the absorption tower circulation pump is connected to the spray pipe.

[0011] The demister is a mesh cover arranged on the top of the absorption tower, and the air outlet of the absorption tower is arranged corresponding to the top of the mesh cover.

[0012] The water outlet of the absorption tower circulation pump is connected with the absorption tower sewage outlet.

[0013] In step B, a quenching tower water tank is provided at the bottom of the quenching tower, and a quenching tower circulation pump draws quenching water in the quenching tower water tank to the quenching water nozzle for spraying, thereby forming circulating water in the quenching tower, and the quenching tower circulation pump discharges sewage through a quenching tower sewage outlet connected to the quenching tower circulation pump.

[0014] In step C, an absorption tower water tank is provided at the bottom of the absorption tower, and the absorption and filtering device includes a packing layer, a spray pipe and a demister. The absorption tower circulation pump draws water in the absorption tower water tank to the spray pipe and sprays it onto the packing layer. The dry tail gas contacts the packing layer after spraying. The harmful gas dissolved in water in the dry tail gas is absorbed by the packing layer and then passes through the demister. The demister deflects the droplets in the tail gas. The absorption tower circulation pump discharges the sewage through the absorption tower sewage outlet connected to the absorption tower circulation pump.

[0015] Through the above technical scheme, the beneficial effects of the present invention are as follows: when the tail gas self-circulation white feather elimination device of the present invention is used, the dry high-temperature tail gas enters the heat exchange tube in the gas-to-gas heat exchanger for indirect heat exchange, the tail gas after heat exchange enters the quenching tower, and is countercurrently contacted with the quenching water from the quenching tower, part of the dust and water vapor carried in the tail gas is washed and condensed, a small part of the gas dissolved in water is absorbed, and the tail gas after washing and condensation is discharged from the top of the quenching tower to the lower part of the absorption tower under the action of the circulating fan, and the dry tail gas and the water from the absorption circulation pump are absorbed and filtered. After absorption and filtration by the device, the harmful gases carried in the dry exhaust gas are absorbed, and the dry exhaust gas after absorption treatment then enters the electrostatic precipitator to further remove solid particles and other substances therein; the dry exhaust gas after electrostatic precipitator enters the shell of the air-to-air heat exchanger under the action of the exhaust gas suction fan, and the purified exhaust gas exchanges heat with the unpurified exhaust gas in the heat exchange tube, and the purified exhaust gas is heated by the unpurified exhaust gas and then discharged into the environment, that is, the exhaust gas is heated to a non-saturated state using its own heat, thereby achieving the purpose of exhaust gas white plume removal, thereby low production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the side structure of a tail gas self-circulation white plume elimination device of the present invention. DETAILED DESCRIPTION

[0017] The structure of the present invention is further described below in conjunction with the accompanying drawings.

[0018] Reference Figure 1 In this embodiment, the method for eliminating white plume from tail gas in the catalyst preparation industry is used for illustration. When it is implemented specifically, it is not limited to eliminating white plume from tail gas in the catalyst industry, but can also be applied to other industrial fields, such as the elimination of white plume from tail gas in the fields of petrochemical, chemical, metallurgical and coal chemical industries. In this embodiment, the dry tail gas in the catalyst preparation industry is mainly composed of nitrogen, oxygen, carbon dioxide, water vapor, a small amount of dust, hydrogen chloride, etc., and the temperature is 150-180°C.

[0019] A tail gas self-circulation white plume elimination device comprises a quenching tower 1 and an absorption tower 2, wherein a quenching cooling device is arranged in the quenching tower, an absorption filtering device 21 is arranged in the absorption tower 2, and the white plume elimination device also comprises an air-to-air heat exchanger 3, an electrostatic precipitator 4 and an tail gas suction fan 5, the air-to-air heat exchanger 3 comprises a sealed heat exchanger shell 31 and a heat exchange tube 32 arranged in the heat exchanger shell, an air inlet end 321 of the heat exchange tube is connected to the tail gas outlet, and an air outlet end 322 of the heat exchange tube is connected to the air inlet of the quenching tower, the air-to-air heat exchanger can adopt different types such as shell and tube heat exchanger and fin tube heat exchanger, unpurified tail gas is introduced into the heat exchange tube of the air-to-air heat exchanger, and the high-temperature gas in the tube exchanges heat with the purified gas in the heat exchanger shell outside the heat exchange tube through the heat exchange tube, thereby heating the purified gas in the heat exchanger shell, thereby heating by its own heat, saving costs. The quenching tower 1 is provided with a quenching water nozzle 11, which is arranged above the air inlet 12 of the emergency cooling tower. The quenching water sprayed by the quenching water nozzle cools and washes the tail gas, and some dust and water vapor carried in the tail gas are washed and condensed. In this embodiment, the white feather elimination device also includes a quenching tower circulation pump 6. A quenching tower water tank 13 is provided at the bottom of the quenching tower 1. A water inlet can be arranged above the quenching tower water tank to discharge water into the quenching tower water tank. The water inlet 61 of the quenching tower circulation pump is connected to the bottom of the quenching tower water tank, and the water outlet 62 of the quenching tower circulation pump is connected to the quenching water nozzle. The quenching and cooling device is a water-cooling loop pipe arranged in the wall of the quenching tower shell. The circulating quenching water in the water-cooling loop pipe quenches and cools the quenching tower shell. The quenching tower shell can be made of glass fiber reinforced plastic, and the water-cooling loop pipe and the quenching water nozzle can be made of polytetrafluoroethylene to prevent the corrosion of acidic and alkaline substances to the equipment. The quench tower circulation pump draws water from the water tank to the quench water nozzle and sprays it out. The water falls into the quench tower water tank and is then recycled by the quench tower circulation pump, saving resources. The water outlet 62 of the quench tower circulation pump is connected to the quench tower sewage outlet 63. When sewage needs to be discharged, the quench water nozzle is closed, and the sewage is discharged from the quench tower sewage outlet through the quench tower circulation pump. In this embodiment, the quench water nozzle is a Venturi structure nozzle. The water pressure of the quench water spray can be increased, thereby quickly cooling the tail gas.

[0020] A circulating fan 7 is provided between the gas outlet 13 of the quenching tower and the gas inlet 22 of the absorption tower, and the circulating fan draws the gas cooled and purified in the quenching tower into the absorption tower. In this embodiment, the absorption tower is mainly used to absorb hydrogen chloride gas dissolved in water. In specific implementation, different absorption and filtering devices can be provided as needed to perform targeted absorption and purification.

[0021] In this embodiment, the white feather elimination device also includes an absorption tower circulation pump 8, an absorption and filtering device is arranged at the upper part of the absorption tower, an absorption and filtering device 21 includes a packing layer, a spray pipe and a demister, the spray pipe is arranged above the corresponding packing layer, the demister is arranged at the top of the absorption tower, an absorption tower water tank 23 is arranged at the bottom of the absorption tower 2, the water inlet 81 of the absorption tower circulation pump is connected to the bottom of the absorption tower water tank, and the water outlet 82 of the absorption tower circulation pump is connected to the spray pipe. The absorption tower circulation pump pumps the water in the absorption tower water tank to the spray pipe for spraying, the spray pipe wets the packing layer, and the wetted packing layer absorbs the hydrogen chloride in the tail gas, and further filters the tail gas. The spray water falls into the absorption tower water tank and is recycled by the absorption tower circulation pump to save resources. In this embodiment, the water outlet of the absorption tower circulation pump 8 is connected to the absorption tower sewage outlet 83. When sewage needs to be discharged, the spray pipe is closed, and the sewage is discharged from the absorption tower sewage outlet through the absorption tower circulation pump. In this embodiment, the demister is a mesh cover arranged at the top of the absorption tower, and the outlet of the absorption tower is arranged above the mesh cover. The mesh cover spreads and deflects the droplets in the tail gas to purify it again. The absorption tower shell can be made of glass fiber reinforced plastic, and the packing layer, spray pipe and mesh cover can all be made of polytetrafluoroethylene to prevent acidic and alkaline substances from corrosive to the equipment.

[0022] The air outlet 24 of the absorption tower is connected to the air inlet of the electrostatic precipitator 4. When the tail gas enters the electrostatic precipitator, the dust particles are charged during the ionization process of the tail gas through the high-voltage electric field, and the dust particles are deposited on the dust accumulator under the action of the electric field force, thereby further removing the fine dust particles in the tail gas. The air outlet of the electrostatic precipitator is connected to the air inlet of the tail gas suction fan 5. The heat exchanger shell 31 is provided with a circulating air inlet 311 connected to the air outlet of the tail gas suction fan, and the heat exchanger shell is also provided with an external exhaust gas outlet 312. The tail gas suction fan sucks the purified tail gas into the heat exchanger shell, and the unpurified high-temperature tail gas in the heat exchange tube of the gas-to-gas heat exchanger heats the purified gas in the heat exchanger shell, thereby heating it through its own heat.

[0023] The method for eliminating white plume by self-circulating tail gas using the tail gas self-circulating white plume eliminating device of the present invention comprises the following steps: Step A: The dry high-temperature exhaust gas, which is mainly composed of nitrogen, oxygen, carbon dioxide, water vapor and a small amount of dust, hydrogen chloride, etc., has a temperature of 150-180°C. The dry high-temperature exhaust gas enters the heat exchange tube in the gas-to-gas heat exchanger for indirect heat exchange. The heat exchange tube passes through the shell of the gas-to-gas heat exchanger, and the heat exchange tube and the shell of the gas-to-gas heat exchanger form an independent sealed space; the exhaust gas in the heat exchange tube is cooled to 110-130 degrees after heat exchange.

[0024] Step B: the tail gas after heat exchange enters the quenching tower, and the quenching tower circulation pump draws the quenching water in the quenching tower water tank to the quenching water nozzle for spraying, and the tail gas is in countercurrent contact with the quenching water from the quenching tower, and part of the dust and water vapor carried in the tail gas are washed and condensed, and a small part of the gas dissolved in water is absorbed. The tail gas after washing and condensation is about 40~50℃; when sewage needs to be discharged, the quenching water nozzle is closed, and the quenching tower circulation pump discharges the sewage through the quenching tower sewage outlet connected to the quenching tower circulation pump.

[0025] Step C: The tail gas after washing and condensation is discharged from the top of the quenching tower to the lower part of the absorption tower under the action of the circulating fan. The dry tail gas and the air from the absorption circulation pump are absorbed and filtered by the absorption and filtering device, and the harmful gases carried in the dry tail gas are absorbed; in specific implementation, different absorption and filtering devices are set according to the harmful gases that need to be absorbed. In this embodiment, an absorption tower water tank is provided at the bottom of the absorption tower, and the absorption and filtering device includes a packing layer, a spray pipe and a demister. The absorption tower circulation pump draws water in the absorption tower water tank to the spray pipe and sprays it onto the packing layer. The dry tail gas contacts the packing layer after spraying. The hydrogen chloride gas dissolved in water in the dry tail gas is absorbed by the packing layer and then passes through the demister. The demister deflects the droplets in the tail gas. When sewage needs to be discharged, the spray pipe is closed, and the absorption tower circulation pump discharges the sewage through the absorption tower sewage outlet connected to the absorption tower circulation pump.

[0026] Step D: The dry exhaust gas after absorption treatment then enters the electrostatic precipitator to further remove solid particles and other substances therein; the exhaust gas is ionized by the high-voltage electric field in the electrostatic precipitator, so that the dust particles are charged, and the dust particles are deposited on the dust collector under the action of the electric field force, thereby further removing the fine dust particles in the exhaust gas.

[0027] Step F: The dry tail gas after electrostatic dust removal enters the shell of the gas-to-gas heat exchanger under the action of the tail gas suction fan, and the purified tail gas exchanges heat with the unpurified tail gas in the heat exchange tube. The purified tail gas is heated to 60-80°C by the unpurified tail gas and then discharged into the environment. Thus, the tail gas is heated to an unsaturated state by utilizing the heat of the tail gas itself, achieving the purpose of eliminating white plume in the tail gas, thereby reducing the production cost.

[0028] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0030] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0032] Although the specific embodiments of the present invention are described in detail in conjunction with the accompanying drawings, it should not be understood as limiting the scope of protection of the present invention. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still belong to the scope of protection of the present invention.

Claims

1. A tail gas self-circulation white plume elimination device, comprising a quenching tower and an absorption tower, wherein the quenching tower is provided with a quenching and cooling device, and the absorption tower is provided with an absorption and filtering device, characterized in that: The white feather elimination device also includes an air-to-air heat exchanger, an electrostatic precipitator and an exhaust gas suction fan. The air-to-air heat exchanger includes a sealed heat exchanger shell and a heat exchange tube arranged in the heat exchanger shell. The air inlet end of the heat exchange tube is connected to the exhaust gas outlet, and the air outlet end of the heat exchange tube is connected to the air inlet of the quenching tower. A quenching water nozzle is provided in the quenching tower, and the quenching water nozzle is arranged above the air inlet of the quenching tower. A circulating fan is provided between the air outlet of the quenching tower and the air inlet of the absorption tower. The air outlet of the absorption tower is connected to the air inlet of the electrostatic precipitator, and the air outlet of the electrostatic precipitator is connected to the air inlet of the exhaust gas suction fan. A circulating air inlet connected to the air outlet of the exhaust gas suction fan is provided on the heat exchanger shell, and an external exhaust gas outlet is also provided on the heat exchanger shell.

2. The exhaust gas self-circulation white plume elimination device according to claim 1, characterized in that: The white feather elimination device also includes a quenching tower circulation pump. A quenching tower water tank is provided at the bottom of the quenching tower. The water inlet of the quenching tower circulation pump is connected to the bottom of the quenching tower water tank, and the water outlet of the quenching tower circulation pump is connected to the quenching water nozzle.

3. The exhaust gas self-circulation white plume elimination device according to claim 2, characterized in that: The water outlet of the quench tower circulation pump is connected to the quench tower sewage outlet.

4. The exhaust gas self-circulation white plume elimination device according to claim 2, characterized in that: The rapid cooling device is a water-cooling ring pipe arranged in the shell wall of the rapid cooling tower.

5. The exhaust gas self-circulation white plume elimination device according to claim 1, characterized in that: The white feather elimination device also includes an absorption tower circulation pump. The absorption and filtration device is arranged at the upper part of the absorption tower. The absorption and filtration device includes a packing layer, a spray pipe and a demister. The spray pipe is arranged above the corresponding packing layer. The demister is arranged at the top of the absorption tower. The bottom of the absorption tower is provided with an absorption tower water tank. The water inlet of the absorption tower circulation pump is connected to the bottom of the absorption tower water tank, and the water outlet of the absorption tower circulation pump is connected to the spray pipe.

6. The exhaust gas self-circulation white plume elimination device according to claim 5, characterized in that: The demister is a mesh cover arranged on the top of the absorption tower, and the air outlet of the absorption tower is arranged corresponding to the top of the mesh cover.

7. The exhaust gas self-circulation white plume elimination device according to claim 5, characterized in that: The water outlet of the absorption tower circulation pump is connected with the absorption tower sewage outlet.

8. A method for eliminating white plume by self-circulating exhaust gas using the exhaust gas self-circulating white plume elimination device as claimed in any one of claims 1 to 7, characterized in that: The steps include: Step A: The dry high-temperature exhaust gas enters the heat exchange tube in the gas-to-gas heat exchanger for indirect heat exchange. The heat exchange tube passes through the shell of the gas-to-gas heat exchanger, and the heat exchange tube and the shell of the gas-to-gas heat exchanger form an independent sealed space; Step B: The tail gas after heat exchange enters the quenching tower and is countercurrently contacted with the quenching water from the quenching tower. Part of the dust and water vapor carried in the tail gas is washed and condensed, and a small part of the gas dissolved in water is absorbed; Step C: The tail gas after washing and condensation is discharged from the top of the quenching tower to the bottom of the absorption tower under the action of the circulating fan. The dry tail gas and the air from the absorption circulating pump are absorbed and filtered by the absorption and filtering device, and the harmful gases carried in the dry tail gas are absorbed; Step D: The dry tail gas after absorption treatment then enters the electrostatic precipitator to further remove solid particles and other substances therein; Step F: The dry exhaust gas after electrostatic dust removal enters the shell of the air-to-air heat exchanger under the action of the exhaust gas suction fan, and the purified exhaust gas exchanges heat with the unpurified exhaust gas in the heat exchange tube. The purified exhaust gas is heated by the unpurified exhaust gas and then discharged into the environment.

9. A method for eliminating white plume by self-circulating tail gas as claimed in claim 8, characterized in that: In step B, a quenching tower water tank is provided at the bottom of the quenching tower, and a quenching tower circulation pump draws quenching water in the quenching tower water tank to the quenching water nozzle for spraying, thereby forming circulating water in the quenching tower, and the quenching tower circulation pump discharges sewage through a quenching tower sewage outlet connected to the quenching tower circulation pump.

10. A method for eliminating white plume by self-circulating tail gas as claimed in claim 8, characterized in that: In step C, an absorption tower water tank is provided at the bottom of the absorption tower, and the absorption and filtering device includes a packing layer, a spray pipe and a demister. The absorption tower circulation pump draws water in the absorption tower water tank to the spray pipe and sprays it onto the packing layer. The dry tail gas contacts the packing layer after spraying. The harmful gas dissolved in water in the dry tail gas is absorbed by the packing layer and then passes through the demister. The demister deflects the droplets in the tail gas. The absorption tower circulation pump discharges the sewage through the absorption tower sewage outlet connected to the absorption tower circulation pump.

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