A device and method for reducing the emission of heavy metals in smelting flue gas

Abstract

The present invention discloses a device and method for reducing the amount of heavy metals discharged from smelting flue gas, belonging to the field of environmental protection management technology, and includes a cooling and pressure reduction device, a membrane tube filter device and a spray tower arranged in sequence along the flow direction of the smelting flue gas; the cooling and pressure reduction device includes at least one flue gas ascending flue connected in sequence and a flue gas descending flue correspondingly connected to the flue gas ascending flue, the flue gas descending flue at the tail end of the cooling and pressure reduction device is connected to the smoke inlet of the membrane tube filter device, the air outlet of the membrane tube filter device is connected to the air inlet of the spray tower, an alkaline solution spray pipe is arranged in the spray tower, and the alkaline solution sprayed from the alkaline solution spray pipe is opposite to the flow direction of the flue gas. Through the above device, the present invention finally recovers and processes 99.9% of the heavy metal dust in the flue gas, so that the heavy metals in the flue gas discharged meet the emission standards, improves environmental protection efficiency, and has significant social benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection management, and in particular to a device and method for reducing the emission of heavy metals in smelting flue gas. Background Art

[0002] In recent years, with the increasing requirements for environmental management, people's awareness of environmental protection has been strengthened, and non-ferrous metal smelting enterprises have gradually improved their flue gas environmental protection treatment technology. However, smelting enterprises always rely on some environmental protection equipment units to contract and implement flue gas treatment, and have not really thought about how to achieve "zero" emissions of heavy metals in flue gas. The traditional treatment ideas for smelting flue gas almost all rely on dust collection equipment, including electric dust collection, bag dust collection, cyclone dust collection, etc. These methods mainly have problems such as high flue gas and dust temperature, fast flow rate, fine particle size, large amount of accumulation, and weak automation level. Problems, which can easily cause excessive accumulation of dust on the electrodes during the electrostatic precipitator process, untimely cleaning, poor electrical efficiency, etc., so that a large amount of dust is discharged into the atmosphere along with the flue gas; the bag dust collector has the problem that the temperature is too high and the bags are easy to catch fire and burn the bags, and the flue gas temperature must be carefully controlled. The meticulous operation is labor-intensive, and the bag strength is poor. Individual bags are damaged and difficult to replace, and they need to be replaced during centralized shutdowns and overhauls, which affects production efficiency. It is also easy for smoke ash in the flue gas to pass through the damaged bags, causing subsequent difficulties in management; the cyclone dust collector can only collect a small part of the large and heavy flue gas dust, and the equipment efficiency is low, and the operation and maintenance are inconvenient. In response to the above problems, the present invention conducts in-depth research on the characteristics of smelting flue gas, focusing on the analysis and detection of heavy metal dust in the flue gas, and then solves the problems of high temperature, fast flow rate, fine particle size, metal chemistry, etc., so as to improve the efficiency of environmental protection management and ensure 100% compliance with emission standards. Summary of the invention

[0003] In view of the shortcomings of the above problems, the present invention provides a device and method for reducing the emission of heavy metals in smelting flue gas, the device comprising:

[0004] A cooling and pressure reducing device, a membrane tube filtration device and a spray tower are sequentially arranged along the flow direction of the smelting flue gas;

[0005] Among them, the cooling and pressure reducing device includes at least one flue gas ascending duct connected in sequence and a flue gas descending duct correspondingly connected to the flue gas ascending duct, the flue gas descending duct at the tail end of the cooling and pressure reducing device is connected to the smoke inlet of the membrane tube filter device, the air outlet of the membrane tube filter device is connected to the air inlet of the spray tower, an alkaline solution spray pipe is provided in the spray tower, and the alkaline solution sprayed by the alkaline solution spray pipe is opposite to the flow direction of the flue gas.

[0006] Preferably, the temperature and pressure reduction device further comprises a collection bin arranged at the tail end of the smoke descending flue, and the collection bin is connected to the smoke inlet of the membrane tube filtering device.

[0007] Preferably, the smoke ascending duct is arranged obliquely with the furnace, the smoke descending duct is arranged obliquely with the collecting bin, and the smoke ascending duct and the smoke descending duct are connected at a certain angle.

[0008] Preferably, the smoke ascending flue and the smoke descending flue are integrally formed as a corrugated flue, and the corrugated flue is made of stainless steel.

[0009] Preferably, the temperature and pressure reduction device comprises at least two groups of the corrugated flues, and the corrugated flues are connected in parallel or in series.

[0010] Preferably, the membrane tube filtration device comprises a box body and a filtration membrane tube, the box body is divided into an air outlet chamber, a filtration chamber and a collection chamber from top to bottom, the filtration membrane tube is arranged in the filtration chamber and one end thereof is connected to the air outlet chamber;

[0011] Wherein, a partition is provided between the air outlet chamber and the filter chamber, the filter chamber and the collection chamber are communicated, the corrugated flue is communicated with the filter chamber, and the spray tower is communicated with the air outlet chamber.

[0012] Preferably, the membrane tube filtration device further comprises a back-blowing and cleaning pipeline correspondingly connected to the filtration membrane tube, one end of the back-blowing and cleaning pipeline is connected to an external wind source, and the other end at least partially extends into the filtration membrane tube.

[0013] Preferably, the spray tower further comprises a spray head arranged on the spray pipe, and the spray head sprays the alkaline solution from bottom to top to form a mist.

[0014] The present invention also provides an external discharge method of the above device, comprising:

[0015] The fan extracts the smelting flue gas from the furnace and conveys it into the flue;

[0016] The smelting flue gas flows along the flue, and its flow direction is first upward and then downward;

[0017] The smelting flue gas after passing through the flue passes through a membrane tube filter device. In the process of the smelting flue gas passing through the membrane tube filter device, the smoke dust containing heavy metals is filtered and blocked on the outer wall of the membrane tube;

[0018] The filtered smelting flue gas is sent to a spray tower, and an alkaline solution flows in the spray tower. After the smelting flue gas and the alkaline solution are fully contacted in the spray tower, the heavy metals in the smelting flue gas are removed.

[0019] Preferably, the membrane tube filtration device is provided with at least two groups of filtration membrane tubes, and each group of filtration membrane tubes is correspondingly connected to a back-blowing dust cleaning pipeline;

[0020] A group of the filter membrane tubes are started alternately at a set time, and when the filter membrane tubes stop working, compressed air is blown off the smoke and dust gathered on the outer wall of the tube through the back-blowing cleaning pipe.

[0021] Preferably, a spray pipe is provided in the spray tower, and a nozzle is provided on the spray pipe. The smelting fume flows into the spray pipe from top to bottom, and the alkaline solution is sprayed from bottom to top through the nozzle to form a mist, so that the alkaline solution is in full contact with the smelting fume.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Through the device of the present invention, 99.9% of the heavy metal dust in the final flue gas is recovered and processed, so that the heavy metals in the exhaust flue gas meet the emission standards, the environmental protection efficiency is improved, and the social benefits are remarkable. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural diagram of a device for reducing the amount of heavy metals discharged from smelting flue gas according to the present invention;

[0025] Figure 2 This is a structural diagram of the membrane tube filtering device in the device for reducing the external emission of heavy metals in smelting flue gas according to the present invention.

[0026] Reference numerals

[0027] 1. Furnace; 2. Corrugated flue; 21. Ascending flue; 22. Descending flue; 3. Collecting bin; 4. Membrane tube filtration device; 41. Air outlet chamber; 42. Filter chamber; 43. Collecting chamber; 44. Filter membrane tube; 5. Spray tower; 6. Back-blowing cleaning pipeline. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. 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] The following is combined with Figure 1 The present invention is described in further detail:

[0032] like Figure 1 As shown, the present invention provides a device and method for reducing the emission of heavy metals in smelting flue gas, the device comprising: a temperature reduction and pressure reduction device, a membrane tube filtration device 4 and a spray tower 5 which are sequentially arranged along the flow direction of the smelting flue gas;

[0033] Among them, the cooling and depressurizing device includes at least one flue gas ascending flue 21 connected in sequence and a flue gas descending flue 22 correspondingly connected to the flue gas ascending flue 21. The flue gas descending flue 22 at the tail end of the cooling and depressurizing device is connected to the smoke inlet of the membrane tube filter device 4. The gas outlet of the membrane tube filter device 4 is connected to the gas inlet of the spray tower 5. The spray tower 5 is provided with an alkaline solution spray pipe, and the alkaline solution sprayed by the alkaline solution spray pipe is opposite to the flow direction of the flue gas. The above device sequentially connects and connects the cooling and depressurizing device, the membrane tube filter device 4 and the spray tower 5 in series, changing the traditional flue gas cooling method using boilers, electric dust collection or bag dust collection, reducing equipment and material costs, and controlling the operation simply and efficiently. It fundamentally solves the problem of heavy metals in the exhaust flue gas, and saves production costs and personnel operations. The service life of the facilities is increased by more than 4 times, and all automatic control is achieved, which is simple and efficient; the final exhaust flue gas can contain various heavy metals up to 0.005mg / m 3 Below, nearly 10 times lower than the national standard.

[0034] Furthermore, the temperature and pressure reduction device also includes a collection bin 3 arranged at the tail end of the smoke descending flue 22, and the collection bin 3 is connected to the smoke inlet of the membrane tube filtering device 4. The smoke ascending flue 21 is arranged obliquely with the furnace 1, and the smoke descending flue 22 is arranged obliquely with the collection bin 3, and the smoke ascending flue 21 and the smoke descending flue 22 are connected at a certain angle.

[0035] In this embodiment, the flue gas ascending flue 21 and the flue gas descending flue 22 are integrally formed into a corrugated flue, and the material of the corrugated flue is stainless steel. Through this arrangement, the flue gas passes through the ups and downs of the corrugated flue and the resistance of the turning point of the trough to reduce the flue gas pressure, and the corrugated flue is arranged outside, and its material is stainless steel, which can quickly cool down, and the stainless steel effectively plays an anti-corrosion effect, thereby increasing the service life of the corrugated flue.

[0036] Furthermore, the temperature and pressure reduction device also includes a collection bin 3 arranged at the end of each group of corrugated flues, and the collection bin 3 is used to collect the heavy metal-containing smoke dust falling from the smelting flue gas. Through this arrangement, a large amount of smoke dust with larger particles coming out of the furnace 1 is accumulated in the flue gas ascending flue 21, and is partially blocked and falls back into the furnace 1; through the flue turning point, the smoke dust containing heavy metals in the flue gas slides into the collection bin 3 here. The collected heavier flue gas and smoke dust, which contains a higher concentration of valuable heavy metals, can be returned to the smelting production for use, realizing resource recycling.

[0037] In this embodiment, it can be installed after calculation according to the actual production conditions of smelting production, or it can be divided into at least two groups of corrugated flues after coming out of the main flue. One can be used in series to reduce the floor space, and the other can be used in parallel, one for use and one for backup, to achieve maintenance without stopping production and improve production efficiency.

[0038] Reference Figure 2 The membrane tube filtration device 4 includes a box body and a filter membrane tube 44. The box body is divided into an air outlet chamber 41, a filter chamber 42 and a collection chamber 43 from top to bottom. The filter membrane tube 44 is arranged in the filter chamber 42 and one end thereof is connected to the air outlet chamber.

[0039] There is a partition between the gas outlet chamber 41 and the filter chamber 42, the filter chamber 42 is connected to the collection chamber 43, the corrugated flue is connected to the filter chamber 42, and the spray tower 5 is connected to the gas outlet chamber 41. For better collection, the collection chamber 43 is set to an inverted cone.

[0040] Furthermore, the membrane tube filtering device 4 also includes a back-blowing cleaning duct 6 correspondingly connected to the filter membrane tube 44, one end of the back-blowing cleaning duct 6 is connected to an external wind source, and the other end at least partially extends into the filter membrane tube 44. Through the above setting, a group of filter membrane tubes 44 are alternately started in sequence at a set time. When the filter membrane tube 44 stops working, compressed wind is blown off the smoke and dust gathered on the outer wall of the tube through the back-blowing cleaning duct 6.

[0041] Specifically, after working for a certain period of time, a group of membrane tube filtration systems is closed, and the program automatically opens the back-blowing valve, and high-pressure compressed air is used to enter the membrane tube from the back-blowing cleaning pipeline 6 to perform back-blowing. The smoke and dust blocked on the outer wall of the membrane tube are blown into the collection chamber at the bottom by the high-pressure wind; the device recycles and processes the fine smoke and dust.

[0042] In this embodiment, the spray tower 5 also includes a nozzle arranged on the spray pipe, which sprays the alkaline solution from bottom to top to form a mist. The smelting flue gas flows into the spray pipe from top to bottom, and the alkaline solution is dispersed by the rotating nozzle to form a liquid mist to seal the middle and lower part of the spray pipe. The alkaline solution and the upper flue gas form a pressure balance contact surface in the middle and upper part of the spray pipe. The wastewater mixed with smoke dust after full contact reaction falls back into the solution middle tank at the bottom of the spray pipe. After the gradual circulation reaction, the mud containing smoke dust accumulated at the bottom is sent to the belt filter system for solid-liquid separation. The flue gas after wet spray washing finally reaches the standard for external discharge, and is far lower than the national air pollution environmental protection emission standard.

[0043] The present invention also provides an external discharge method of the above device, comprising:

[0044] The fan extracts the smelting flue gas in the furnace 1 and transmits it into the flue;

[0045] The smelting flue gas flows along the flue, first upward and then downward, so that the temperature and pressure of the smelting flue gas gradually decrease;

[0046] The smelting flue gas after being cooled and reduced in pressure passes through the membrane tube filter device 4. In the process of the smelting flue gas passing through the membrane tube filter device 4, the smoke dust containing heavy metals is filtered and blocked on the outer wall of the membrane tube;

[0047] The filtered smelting flue gas is sent to the spray tower 5, and an alkaline solution flows in the spray tower 5. After the smelting flue gas and the alkaline solution are fully contacted in the spray tower 5, the heavy metals in the smelting flue gas are removed, ensuring that the heavy metal content in the smelting flue gas meets the emission standards.

[0048] Furthermore, the membrane tube filtering device 4 is provided with at least two groups of filtering membrane tubes 44, and each group of filtering membrane tubes 44 is correspondingly connected to a back-blowing dust cleaning pipeline 6;

[0049] A group of filter membrane tubes 44 are started alternately at set time. When the filter membrane tubes 44 stop working, the compressed air is blown off the smoke and dust gathered on the outer wall of the tube through the back-blowing cleaning pipeline 6.

[0050] Furthermore, a spray pipe is provided in the spray tower 5, and a nozzle is provided on the spray pipe. The smelting flue gas flows into the spray pipe from top to bottom, and the alkaline solution is sprayed from bottom to top through the nozzle to form a mist, so that the alkaline solution is fully in contact with the smelting flue gas.

[0051] Continue to refer to Figure 1 In this embodiment, two sets of corrugated flues are used, each of which is 50m long, DN800mm in diameter, with an up and down inclination angle of 45° and made of stainless steel.

[0052] First, turn on the environmental protection fan, and then turn on the smelting furnace 1. The smelting flue gas is extracted from the smelting furnace 1 by the negative pressure of the fan. The flue gas negative pressure is -2000Pa, the temperature is 560℃, the flue gas flow rate is 3m / s, and the flue gas volume is 30000m 3 / h, the flue gas outlet of the smelting furnace 1 is connected to an ascending flue 21 with an upward inclination of 45°. The first section of the corrugated flue gas duct extends out of the factory building. A large amount of large-particle smoke from the furnace 1 accumulates here and is partially blocked from entering the furnace 1. The smoke passes through the descending section of the descending flue 22 with a downward inclination of 45°. A cylindrical collection bin 3 with a diameter of DN1500mm and a volume of 2m is installed at the bottom of the flue. 3 , the smoke dust containing heavy metals in the flue gas slides into the collection bin 3 here; the corrugated flue is made of stainless steel, and the flue gas contains corrosive substances, which can effectively play an anti-corrosion effect and increase the service life of the corrugated flue. The flue gas pressure loss is 100-300Pa every time it passes through the upper and lower sections of the corrugated flue. The diameter of each flue section is 800mm and the length is about 10m, which can reduce the flue gas temperature by 20-50℃ and the flue gas pressure to about -1000Pa; the corrugated flue can collect about 6t of smoke dust in the flue gas every day, which contains a high concentration of valuable heavy metals, which can be returned to the smelting production for use, realizing resource recycling; the device separates part of the smoke dust containing heavy metals from the flue gas, which can reduce the amount of heavy metals discharged from the flue gas by one third;

[0053] The flue gas cooled and depressurized by the corrugated flue is sent into the membrane tube filter device 4. The filter membrane tubes 44 are divided into five groups, each group has 200 membrane tubes, and the membrane tubes are Ф100mm×3m. The bottom of each group of filter membrane tubes 44 is an inverted cone collection chamber. When the flue gas enters the membrane tube filter device 4, the flue gas enters the membrane tube from the outside of the membrane tube, and the heavy metal dust larger than 0.1-0.5μm is blocked on the outer wall of the membrane tube. When the smoke accumulates to 10-20mm, the internal pressure of the membrane tube gradually approaches the positive pressure, a group of membrane tube filter systems is closed, and the program automatically opens the back-blowing valve. Compressed air with a pressure of 0.6MPa enters the 200 membrane tubes from the back-blowing cleaning pipeline 6 for back-blowing. The smoke blocked on the outer wall of the membrane tube is blown down to the collection chamber at the bottom by the high-pressure wind; the membrane tube filter device 4 recycles the fine smoke dust to reduce the smoke dust containing heavy metals in the smelting flue gas to about two-thirds of the total amount;

[0054] The filtered flue gas is transported into the spray tower 5 and into the spray pipe with a diameter of 1000mm and a length of 8000mm. The wet spray alkaline liquid delivery pump is first turned on at a flow rate of 1000m 3 / h conveying speed, lift is 40m, alkaline liquid PH is 12, it is transported from bottom to top through the middle nozzle at the bottom of the spray pipe, the flue gas pressure is about 500Pa positive pressure, and it enters the spray pipe with a diameter of 1000mm from top to bottom. The alkaline liquid is broken up by the rotating nozzle with an angle of 27° to form a liquid mist, and the middle and lower part of the spray pipe is sealed at 3-6m. The alkali liquid and the upper flue gas form a pressure balance contact surface in the middle and upper part of the spray pipe. The wastewater mixed with smoke and dust after full contact reaction falls back to the middle tank with a diameter of 3.6m and a height of 5m at the bottom of the spray pipe. When the pH value of the solution in the middle tank drops to 7 for recycling, the slurry containing smoke and dust accumulated at the bottom after the recycling reaction is gradually sent to the filter system with a filter for solid-liquid separation. The filtered solution is returned for recycling. The flue gas flow rate after spray washing is 5.5m / s, containing 3.12mg / m 3 , containing nickel 2.19×10 -4 mg / m 3 , copper content 0.015mg / m 3 , lead 3.12×10 -4 mg / m 3 , and ultimately achieve environmentally friendly emissions that are far below the national air pollution emission standards.

[0055] The advantages of the present invention are as follows: the corrugated flue cooling and pressure reduction dust removal method has the advantages of high cooling and pressure reduction efficiency, simple operation, long service life, high safety performance, etc. Compared with the traditional boiler circulating water cooling and cooling measures, the facilities are complex, frequent inspections are required to ensure safe operation, and the boiler cost is relatively high; compared with electric dust collectors, bag dust collectors and other methods, the membrane tube filtration dust removal method has a long service life, high temperature resistance, and efficient filtration and dust removal effect, and is simple to operate, not easy to damage, and saves production costs; the spray washing dust removal adopts an aerosol alkaline solution to form a sealed washing, and the dust reduction efficiency is very high. Compared with the ordinary absorption tower spray washing, it has the advantages of efficient facilities, outstanding indicators, and circular economy. It adapts to the latest environmental protection standards for the development and progress of environmental protection, improves the environment around the factory, and has obvious social benefits.

[0056] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A device for reducing the emission of heavy metals from smelting flue gas, characterized in that: The temperature and pressure reduction device, membrane tube filtration device and spray tower are arranged in sequence along the flow direction of the smelting flue gas; The temperature-reducing and pressure-reducing device comprises at least one flue gas ascending duct and a flue gas descending duct connected in sequence with the flue gas ascending duct, the flue gas descending duct at the tail end of the temperature-reducing and pressure-reducing device is connected with the smoke inlet of the membrane tube filter device, the air outlet of the membrane tube filter device is connected with the air inlet of the spray tower, an alkaline solution spray pipe is arranged in the spray tower, and the alkaline solution sprayed by the alkaline solution spray pipe is opposite to the flow direction of the flue gas; The smoke ascending flue is arranged obliquely with the furnace, the smoke descending flue is arranged obliquely with the collecting bin, and the smoke ascending flue and the smoke descending flue are connected at a certain angle; The membrane tube filtration device comprises a box body and a filter membrane tube, wherein the box body is divided into an air outlet chamber, a filter chamber and a collection chamber from top to bottom, the filter membrane tube is arranged in the filter chamber and one end of the filter membrane tube is connected to the air outlet chamber; a partition is arranged between the air outlet chamber and the filter chamber, the filter chamber is connected to the collection chamber, the corrugated flue is connected to the filter chamber, and the spray tower is connected to the air outlet chamber; The smoke ascending flue and the smoke descending flue are integrally formed into a corrugated flue, and the material of the corrugated flue is stainless steel; The temperature and pressure reduction device comprises at least two groups of the corrugated flues, which are connected in parallel or in series; The membrane tube filtering device also includes a back-blowing and dust-cleaning pipeline correspondingly connected to the filtering membrane tube, one end of the back-blowing and dust-cleaning pipeline is connected to an external wind source, and the other end at least partially extends into the filtering membrane tube; The spray tower further comprises a spray head disposed on the spray pipe, and the spray head sprays the alkaline solution from bottom to top to form a mist; First, turn on the environmental protection fan, then turn on the smelting furnace. The smelting flue gas is extracted from the smelting furnace through the negative pressure of the fan. The flue gas negative pressure is -2000Pa, the temperature is 560℃, the flue gas flow rate is 3m / s, and the flue gas volume is 30000m 3 / h, the flue gas outlet of the smelting furnace is connected to an ascending flue with an upward inclination of 45°. The first section of the corrugated flue gas duct extends out of the factory building. A large amount of large-particle smoke from the furnace accumulates here and is partially blocked from entering the furnace. The smoke passes through the descending flue with a downward inclination of 45°. A cylindrical collection bin with a diameter of DN1500mm and a volume of 2m is installed at the bottom of the flue. 3 , the smoke dust containing heavy metals in the flue gas slides into the collection bin here; the corrugated flue is made of stainless steel, and the flue gas contains corrosive substances, which effectively prevents corrosion and increases the service life of the corrugated flue. The flue gas pressure loss is 100-300Pa every time it passes through the upper and lower sections of the corrugated flue. The diameter of each flue section is 800mm and the length is 10m, which can reduce the flue gas temperature by 20-50℃ and the flue gas pressure to about -1000Pa; the corrugated flue collects 6t of smoke dust in the flue gas every day, which contains a high concentration of valuable heavy metals and is returned to the smelting production for use, realizing resource recycling; the device separates part of the smoke dust containing heavy metals from the flue gas, reducing the amount of heavy metals discharged from the flue gas by one third; The flue gas cooled and depressurized by the corrugated flue is sent to the membrane tube filter device. The filter membrane tubes are divided into five groups, each group has 200 membrane tubes, and the membrane tubes are Ф100mm×3m. The bottom of each group of filter membrane tubes is an inverted cone collection chamber. When the flue gas enters the membrane tube filter device, the flue gas enters the membrane tube from the outside of the membrane tube, and the heavy metal dust larger than 0.1-0.5μm is blocked on the outer wall of the membrane tube. When the dust accumulates to 10-20mm, the internal pressure of the membrane tube gradually approaches the positive pressure, and a group of membrane tube filter systems is closed. The program automatically opens the back-blowing valve, and the compressed air with a pressure of 0.6MPa enters the 200 membrane tubes from the back-blowing cleaning pipeline for back-blowing. The dust blocked on the outer wall of the membrane tube is blown down to the collection chamber at the bottom by the high-pressure wind; the membrane tube filter device recycles the fine dust to reduce the dust containing heavy metals in the smelting flue gas to two-thirds of the total amount; The filtered flue gas is transported into the spray tower and into the spray pipe of 1000mm in diameter and 8000mm in length. The wet spray alkaline liquid delivery pump is first turned on at a flow rate of 1000m 3 / h conveying speed, lift is 40m, alkaline liquid PH is 12, it is transported from bottom to top through the middle nozzle at the bottom of the spray pipe, the flue gas pressure is about 500Pa positive pressure, and it enters the spray pipe with a diameter of 1000mm from top to bottom. The alkaline liquid is broken up into liquid mist by the rotating nozzle with an angle of 27°, and the middle and lower part of the spray pipe is sealed at 3-6m. The alkali liquid and the upper flue gas form a pressure balance contact surface in the middle and upper part of the spray pipe. The wastewater mixed with smoke and dust after full contact reaction falls back to the middle tank with a diameter of 3.6m and a height of 5m at the bottom of the spray pipe. When the pH value of the solution in the middle tank drops to 7 for recycling, the slurry containing smoke and dust accumulated at the bottom after the recycling reaction is gradually sent to the filter system with a filter for solid-liquid separation, and the filtered solution is returned for recycling. The flue gas flow rate after spray washing is 5.5m / s, containing 3.12mg / m 3 , containing nickel 2.19×10-4mg / m 3 , copper content 0.015mg / m 3 , lead content 3.12×10-4mg / m 3 , and ultimately achieve environmentally friendly discharge standards.

2. The device for reducing the emission of heavy metals from smelting flue gas according to claim 1, characterized in that: The temperature and pressure reduction device also includes a collection bin arranged at the tail end of the smoke descending flue, and the collection bin is connected to the smoke inlet of the membrane tube filtering device.

3. A method for reducing the discharge of heavy metals from smelting flue gas according to any one of claims 1 to 2, characterized in that: include: The fan extracts the smelting flue gas from the furnace and conveys it into the flue; The smelting flue gas flows along the flue, and its flow direction is first upward and then downward; The smelting flue gas after passing through the flue passes through a membrane tube filter device. In the process of the smelting flue gas passing through the membrane tube filter device, the smoke dust containing heavy metals is filtered and blocked on the outer wall of the membrane tube; The filtered smelting flue gas is sent to a spray tower, and an alkaline solution flows in the spray tower. After the smelting flue gas is fully contacted with the alkaline solution in the spray tower, heavy metals in the smelting flue gas are removed.

4. The method for reducing the emission of heavy metals from smelting flue gas according to claim 3, characterized in that: The membrane tube filtration device is provided with at least two groups of filtration membrane tubes, and each group of filtration membrane tubes is correspondingly connected to a back-blowing dust cleaning pipeline; A group of the filter membrane tubes are started alternately at set time, and when the filter membrane tubes stop working, compressed air is blown off the smoke and dust gathered on the outer wall of the tube through the back-blowing cleaning pipeline.

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