Device for low-temperature dry dust removal of trapped phosphorus furnace gas

Abstract

This invention discloses a low-temperature dry dust removal device for phosphorus furnace gas, comprising: two sets of series-connected metal felt filter screens, filter screen electric heaters, a backflushing system, a dust collection funnel, a spiral dust collector, and a fan. The outlet pipe of the yellow phosphorus furnace gas is connected to the inlet of the series-connected metal felt filter screens. Each metal felt filter screen is equipped with an electric heater. The backflushing system achieves dust removal by adjusting the valve switch to reverse the gas flow. The filter cake outlet of the metal felt filter screen is connected to the inlet of the dust collection funnel. The outlet of the metal felt filter screen is connected to the inlet of the fan. The dust outlet at the bottom front side of the metal felt filter screen and the dust collection funnel are sealed and connected to the dust inlet of the closed spiral dust collector. The outlet of the fan is the exhaust port of the device. This device can solve the problem of yellow phosphorus furnace gas condensation clogging and corrosion of equipment, achieve low-temperature and high-efficiency dust removal of yellow phosphorus furnace gas, and improve filtration efficiency and phosphorus yield.

Description

Technical Field

[0001] This invention relates to the field of energy conservation and emission reduction technology in yellow phosphorus production, and in particular to a device for low-temperature dry dust removal of phosphorus furnace gas by interception. Background Technology

[0002] Yellow phosphorus is an essential raw material for the preparation of high-purity polyphosphoric acid, lithium batteries, pesticides, and phosphorus-based drugs, and is an indispensable chemical product. Currently, the most common method is to use a phosphorus electric furnace. This involves a reduction reaction of phosphate rock (fluorapatite), a reducing agent (anthracite or coke), and a flux (SiO2) heated by a high-temperature electric arc at an acidity value (SiO2+Al2O3) / CaO of 0.85-1.1. The furnace gas discharged from the yellow phosphorus electric furnace at 130-180℃ contains 80-90 wt% CO and only about 300-350 g / m³ of gaseous elemental phosphorus. 3 As the high-temperature reaction gas rises in the phosphorus furnace, it carries particulate mineral materials. Side reactions also produce a certain amount of reactive substances such as HF, SiF4, H2S, COS, PH3, AsH3, HCN, and tar. After cooling, these substances agglomerate to form condensed dust, with a content ranging from approximately 40 to 120 g / m³. 3 Statistics show that the production of each ton of yellow phosphorus generates 2500-3000 cubic meters of tail gas as a byproduct. 3 Phosphorus-containing wastewater 20~40m 3 250 kg of mud phosphorus. Mud phosphorus is a major hazardous solid waste in the production of yellow phosphorus and a source of pollution that causes headaches for enterprises.

[0003] If the phosphorus furnace gas enters the spray tower for phosphorus recovery without undergoing dry dust removal, dust and harmful impurities in the gas will be absorbed and adhered to by liquid droplets, collecting in the phosphorus receiving tank at the bottom of the tower. SiF4 hydrolyzes into fluorosilicic acid precipitate, and dust, fluorosilicic acid, tar, etc., are mixed with yellow phosphorus to form phosphorus sludge, reducing the yield and purity of yellow phosphorus and increasing the burden of subsequent phosphorus sludge treatment. The resulting phosphorus-containing solid waste will cause significant environmental damage. Therefore, dry dust removal of the phosphorus furnace gas is necessary to reduce the production of phosphorus sludge. Currently, the mainstream dry dust removal methods include electrostatic precipitators and bag filters. Electrostatic precipitators are industrially used in Yuntianhua's 30k tons / year large phosphorus furnace (phosphorus furnace gas outlet temperature reaches 350~500℃), with a dust removal efficiency of 70~80%. When used in small to medium-sized phosphorus furnaces, where the furnace gas temperature is generally below 200℃, phosphorus vapors in the furnace gas are more prone to condensation on the surface of the settling stage compared to large furnaces. Tar in the furnace gas also adheres to the settling stage, causing insurmountable defects in the production process. Furthermore, the lack of insulation on the filter bags inside the baghouse dust collector leads to phosphorus vapor condensation and tar adhesion, making cleaning impossible and causing shutdown. Additionally, the furnace gas temperature can reach over 280℃ during abnormal operation, easily burning out the filter bags.

[0004] To address the aforementioned issues, CN103708432A and CN103523762A disclose a "method, equipment, and dedicated phosphorus collection device for recovering yellow phosphorus from electric furnace phosphorus production gas" and a "yellow phosphorus production method and equipment," requiring an operating temperature of 187.5-280℃. CN217698338U and CN218188616U both require partial combustion of phosphorus furnace tail gas to ensure phosphorus vapor does not condense. Using the combustion of yellow phosphorus tail gas to indirectly supply dust removal equipment for insulation is energy-intensive, inefficient, and the phosphorus and fluorine impurities in the yellow phosphorus tail gas cause significant corrosion to the equipment. CN112156600A discloses a "method and device for preventing blockage and dust removal in pipelines transporting yellow phosphorus furnace gas," aiming to maintain the phosphorus furnace gas temperature at 240-275℃ by setting up an insulation layer and adding electric heating equipment. These inventions all require heating the filtered furnace gas to above the freezing point of yellow phosphorus, which increases energy consumption. Furthermore, the high-temperature phosphorus furnace gas entering subsequent spray tower equipment increases water consumption and reduces yellow phosphorus recovery efficiency. CN211462443U discloses a "dry dust removal and filtration system for yellow phosphorus furnace gas," which uses a multi-stage plate and frame filter press to trap dust from the phosphorus furnace gas. The patent does not mention the operating temperature. Due to the dust collection box, high-temperature operation requires heating, increasing energy consumption, while low-temperature operation causes yellow phosphorus agglomeration, increasing dust content, reducing yellow phosphorus yield, and increasing the burden of mud phosphorus treatment.

[0005] Dry dust removal technology for yellow phosphorus furnace gas is technically challenging and poses numerous safety hazards. Phosphorus furnace gas is flammable and explosive, and condensed dust or yellow phosphorus can spontaneously combust upon contact with air. Therefore, dry dust removal of yellow phosphorus furnace gas is more difficult than that for coke oven gas, blast furnace gas, and ore kiln gas, requiring careful consideration of the safety design of the dust removal process. Summary of the Invention

[0006] The technical problem to be solved by the present invention is how to provide a device for low-temperature dry dust removal of yellow phosphorus furnace gas that can solve the problem of condensation, blockage and corrosion of yellow phosphorus furnace gas, achieve low-temperature and high-efficiency dust removal of yellow phosphorus furnace gas, and improve filtration efficiency and phosphorus yield.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a device for low-temperature dry dust removal of phosphorus furnace gas, comprising: two sets of metal felt interception filters connected in series, filter electric heaters, a back-blowing system, a dust collection funnel, a spiral dust collector, and a fan. The outlet pipe of the yellow phosphorus electric furnace gas is connected to the inlet of the series-connected metal felt interception filters. Each metal felt interception filter is equipped with an electric heater. The back-blowing system achieves dust removal by adjusting the valve switch to reverse the gas flow. The filter cake outlet of the metal felt interception filter is connected to the inlet of the dust collection funnel. The outlet of the metal felt interception filter is connected to the inlet of the fan. The dust outlet at the bottom front side of the metal felt interception filter and the dust collection funnel are sealed and connected to the dust inlet of the closed spiral dust collector. The air outlet of the fan is the exhaust port of the device.

[0008] A further technical solution is that the metal felt inside the metal felt interception filter is made of 316 or 310S stainless steel and is woven from 316 or 310S steel fibers; the surface pores of the metal felt are less than 1mm, and the disordered interweaving inside can achieve the interception of dust particles with a particle size greater than 0.01-0.001mm.

[0009] A further technical solution is as follows: the electric heater is used in the form of an inner resistance wire or an electromagnetic heater, depending on the conditions and operating conditions, and has a built-in temperature detection and control system to keep the filter screen temperature above 350-450℃. The fluid passes through the high-temperature metal felt interception filter screen, causing the phosphorus-containing droplets to be rapidly vaporized and pass through the filter screen with the gas phase bulk, so that the yellow phosphorus does not adhere to the filter screen. There are adsorption, interception, collision and electrostatic effects between dust particles. Through the interception effect of the metal felt interception filter screen with electric heater, the condensed phosphorus adhering to the dust particles is vaporized and enters the gas phase bulk, keeping the dust dry and facilitating the desorption of dust during reverse blowing.

[0010] A further technical solution is as follows: the inlet pipe of the backflush system is connected to the outlet pipe of the yellow phosphorus electric furnace gas. A first airflow valve is installed on the inlet pipe of the backflush system. The outlet end of the inlet pipe of the backflush system is divided into two paths. The first path connects to the inlet of the outer cavity of the first filter electric heater via a second pipe. A third airflow valve is located on the second pipe. One end of a fifth airflow valve is connected to the second pipe between the third airflow valve and the first filter electric heater. The other end of the fifth airflow valve connects to the outlet of the backflush system via the third pipe. The outlet of the outer cavity of the first filter electric heater is connected via... The fourth pipeline is connected to the air inlet of the cavity outside the second filter electric heater; the first pressure drop detector is connected in parallel to both ends of the cavity outside the first filter electric heater; the second path of the outlet end of the backflush system's air inlet pipe is connected to the air inlet of the cavity outside the second filter electric heater via the fifth pipeline; the fourth airflow valve is located on the fifth pipeline; one end of the sixth airflow valve is connected to the fifth pipeline between the fourth airflow valve and the second filter electric heater; the other end of the sixth airflow valve is connected to the air outlet of the backflush system via the sixth pipeline; and the second pressure drop detector is connected in parallel to both ends of the cavity outside the second filter electric heater.

[0011] The beneficial effects of adopting the above technical solution are as follows: 1) Dry dust removal and purification are achieved, reducing the load on subsequent bleached phosphorus and mud phosphorus recovery and treatment, and increasing the yield of yellow phosphorus. Bleached phosphorus and mud phosphorus recovery are one of the main pollution sources in yellow phosphorus production. Through the device described in this invention, phosphorus vapor and dust are separated before entering the condensation process, and mud phosphorus is no longer generated in the subsequent process. This eliminates the energy consumption and pollution of bleached phosphorus and mud phosphorus recovery, reduces the production cost of yellow phosphorus, and saves the hot water (or steam) supplied for bleached phosphorus and the phosphorus furnace tail gas for mud phosphorus recovery.

[0012] 2) Energy saving. The furnace gas control temperature of the metal felt interception filter equipment in the device described in this invention is not higher than 220℃, which is low temperature and low energy consumption.

[0013] 3) Provide heat energy to the metal felt filter screen to ensure that phosphorus vapor does not adhere and effectively vaporize and separate the yellow phosphorus adhering to the dust particles.

[0014] 4) The present invention adopts a combination of metal felt interception filter and spiral ash discharge, so that the fluid linear velocity does not change significantly, reducing the residence time of the fluid in the dust removal process, improving the dust removal efficiency and reducing the further coagulation and gelatinization of yellow phosphorus at low temperature.

[0015] 5) Two sets of dust removal filters are connected in series and combined with reverse blowing to remove tiny particles larger than 1μm. The optimized reverse blowing system can update the metal felt filter in time, prevent pressure head loss, and ensure a slight positive pressure throughout the dust removal process. Attached Figure Description

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0017] Figure 1 This is a schematic diagram of the structure of the device described in the embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the backflushing system in the device described in the embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the structure of the metal felt filter and electric heater in the device described in the embodiment of the present invention;

[0020] The components include: 1. Metal felt filter screen; 101. Outlet pipe for yellow phosphorus electric furnace gas; 102. Filter screen temperature indicator; 103. Metal felt filter screen jacket; 2. Filter screen electric heater; 3. Backflushing system; 301. First airflow valve; 302. Second airflow valve; 303. Third airflow valve; 304. Fourth airflow valve; 305. Fifth airflow valve; 306. Sixth airflow valve; 307. First pressure drop detector; 308. Second pressure drop detector; 4. Ash collection funnel; 5. Spiral ash discharge machine; 6. Fan. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0023] like Figure 1 As shown in the figure, this invention discloses a device for low-temperature dry dust removal of phosphorus furnace gas, including a metal felt intercepting filter screen 1, a filter screen electric heater 2, a back-blowing system 3, a dust collection funnel 4, a spiral dust collector 5, and a fan 6. The outlet pipe 101 of the yellow phosphorus electric furnace gas is connected to the inlet of the series-connected metal felt intercepting filter screen 1. Each metal felt intercepting filter screen is equipped with an electric heater 2. The back-blowing system 3 uses pressure drop detectors 307-308 to determine the flow direction and adjust the valve switch to perform gas flow back-blowing to achieve dust removal. The filter cake outlet of the metal felt intercepting filter screen 1 is connected to the inlet of the dust collection funnel 4, and the outlet of the metal felt intercepting filter screen 1 is connected to the inlet of the fan 6. The dust outlet at the bottom front side of the metal felt intercepting filter screen 1, the dust collection funnel 4, and the dust inlet of the sealed spiral dust collector 5 are sealed and connected. The air outlet of the fan 6 is the exhaust port of the device.

[0024] like Figure 2-3 As shown, the metal felt intercepting filter 1 is equipped with an electric heater 2. The electric heater 2 can be in the form of an inner resistance wire or an electromagnetic heater, depending on the conditions and operating conditions. It also has a built-in temperature detection and control system to keep the filter temperature above 350-450℃. When the fluid passes through the high-temperature metal felt intercepting filter 1, the phosphorus-containing droplets are rapidly vaporized and pass through the filter with the gas phase, preventing yellow phosphorus from adhering to the filter. There are adsorption, interception, collision and electrostatic effects between dust particles. Through the interception effect of the metal felt intercepting filter 1 with electric heater 2, the condensed phosphorus adhering to the dust particles is vaporized and enters the gas phase, keeping the dust dry and facilitating the desorption of dust during reverse blowing. The desorbed dust enters the closed spiral dust discharge machine 5 through the dust collection funnel 4 and is discharged.

[0025] like Figure 2As shown, the inlet pipe of the backflush system 3 is connected to the outlet of the outlet pipe 101 of the yellow phosphorus electric furnace gas. A first airflow valve 301 is installed on the inlet pipe of the backflush system 3. The outlet end of the inlet pipe of the backflush system 3 is divided into two paths. The first path is connected to the air inlet of the outer cavity of the first filter electric heater 2 via the second pipe. A third airflow valve 303 is located on the second pipe. One end of a fifth airflow valve 305 is connected to the second pipe between the third airflow valve 303 and the first filter electric heater. The other end of the fifth airflow valve 305 is connected to the outlet of the backflush system 3 via the third pipe. The outlet of the outer cavity of the first filter electric heater 2 is connected to the fourth pipe. The first pressure drop detector 307 is connected in parallel to both ends of the cavity outside the first filter electric heater 2; the second path of the outlet end of the backflush system 3 is connected to the inlet of the cavity outside the second filter electric heater 2 via the fifth pipeline; the fourth airflow valve 304 is located on the fifth pipeline; one end of the sixth airflow valve 306 is connected to the fifth pipeline between the fourth airflow valve 304 and the second filter electric heater; the other end of the sixth airflow valve 306 is connected to the outlet of the backflush system 3 via the sixth pipeline; and the second pressure drop detector 308 is connected in parallel to both ends of the cavity outside the second filter electric heater 2.

[0026] like Figure 2 As shown, the third airflow valve 303 and the sixth airflow valve 306 are opened, while the fourth airflow valve 304 and the fifth airflow valve 305 remain closed. Gas flows clockwise within the pipe, purging one side of the metal felt filter screen. After a period of operation, by detecting the pressure difference across the filter screen and confirming the accumulation of filter cake, the third airflow valve 303 and the sixth airflow valve 306 are closed, and the fourth airflow valve 304 and the fifth airflow valve 305 are opened. The airflow then flows counter-clockwise within the system, purging the other side of the metal felt filter screen. This change in gas flow direction prevents filter cake formation on the filter screen.

[0027] like Figure 3 As shown, the metal felt of the metal felt filter screen 1 is made of 316 or 310S stainless steel and is woven from 316 or 310S stainless steel fibers; the surface pores of the metal felt 31 are less than 1mm, and the disordered interweaving inside can achieve the interception of dust particles with a particle size greater than 0.01-0.001mm.

[0028] The yellow phosphorus furnace gas discharged from the yellow phosphorus electric furnace is fed into a back-flushing system containing a metal felt retaining filter 1 for dust removal. The metal felt retaining filter 1 removes dust particles larger than 1μm from the yellow phosphorus furnace gas. The outer wall of the pipe of the back-flushing system 3 is insulated and heated with steam, and the metal felt retaining filter 1 is insulated and heated with an inner lining of resistance wire or an electromagnetic induction heater to prevent condensable gases from condensing. The yellow phosphorus furnace gas after dust removal and purification is directly discharged as yellow phosphorus product through the outlet of the blower 6. The dust generated by the metal felt retaining filter 1 and the dust collection funnel 4 is discharged into a closed spiral ash discharge machine 5.

[0029] Furthermore, the pressure drop through the dust collection device should not exceed 0.8-1.5 atm. When the pressure drop detector shows a pressure drop greater than or equal to 1.5 atm, the valve switch is changed to form a back-flushing process to remove the filter cake dust on the metal felt filter screen, ensuring the smooth flow of fluid and helping the entire dust collection device to operate under a slightly positive pressure condition, preventing backflow of outside air.

[0030] Heating can be achieved by lining the metal felt filter with resistance wire or by using a non-contact electromagnetic induction heater; further, it can be described that one set of metal felt trapping filters can be disassembled and replaced without stopping operation.

[0031] Furthermore, when the filtration velocity of the metal felt filter is 0.2~0.8 m / s, the dust concentration in the phosphorus-containing furnace gas after passing through the metal felt filter is less than 5 mg / Nm³. 3 When the filtration velocity is 0.8~1.5m / s, the dust concentration in the phosphorus-containing furnace gas is less than 10mg / Nm³ after passing through the metal felt filter. 3 .

[0032] Furthermore, the series of metal felt intercepting filters removes dust particles larger than 1μm from the yellow phosphorus furnace gas. The outer wall of the back-flushing system pipes is insulated and heated with steam, and the metal felt intercepting filters are insulated and heated with resistance wire or electromagnetic induction heaters to prevent condensable gases from condensing. The dust-purified yellow phosphorus furnace gas directly produces yellow phosphorus products through the blower outlet. The dust generated by the two sets of metal felt intercepting filters and the dust collection funnel is discharged into the closed spiral ash discharge machine.

[0033] Furthermore, by heating the pipe walls of the backflushing system with steam, the pipe wall temperature in the dry dust removal section is maintained at 140-150℃.

[0034] The method of using the above device is as follows:

[0035] First, pass through the inert gas N2. The 0.6 MPa conveying pipeline delivers inert gas to the low-temperature dry dust removal device. At this time, the metal felt retaining filter 1 and its bypass pipeline are fully open to ensure that the air in the tank is completely replaced by nitrogen. The heater and back-blowing switch valve are tested, the pipeline is inspected to prevent leaks, and the temperature and pressure display instruments are checked. Then, the nitrogen replacement valve 302 is slowly closed, and the feed gas is switched to phosphorus furnace gas from the phosphorus electric furnace. The electric heating equipment is run, and the fluid temperature rise at the rear end of the metal felt retaining filter 1 is checked and controlled at about 10~30℃. During the operation of the dust removal equipment, the gas pressure drop at both ends of the key filter is monitored by the pressure drop detector. When the pressure drop reaches 0.8-1.5 atm, the purging system valve switch is quickly changed to back-blow the filter. The phosphorus furnace gas after two-stage gas dust removal is drawn into the post-treatment device by the fan. The dust knocked off by the back-blowing is discharged through the ash collection funnel and the spiral ash discharger. When a set of metal felt filters needs to be disassembled for manual cleaning or replacement, the bypass is opened to maintain the normal operation of the system.

[0036] After the electric furnace is started, the phosphorus furnace gas enters a backflushing system containing a metal felt filter to remove dust particles larger than 1μm. To ensure that the metal felt filter is not blocked by substances below the dew point, the pipe walls of the backflushing system are insulated and heated. The metal felt filter is insulated and heated by an internal resistance wire lining or an electromagnetic induction heater. The dust filtered by the metal felt filter enters a closed spiral ash discharge system through a collection funnel at the bottom of the filter. To save energy, all equipment and pipelines involved in the dry purification of yellow phosphorus furnace gas must be insulated to reduce heat exchange between the furnace gas and the outside environment. Example 1

[0037] The furnace gas temperature at the outlet of the phosphorus furnace is 110℃. It enters a backflushing system containing a metal felt filter to remove dust particles larger than 1μm. The surface temperature of the metal felt filter is controlled at 120-130℃. The phosphorus-containing furnace gas after dust separation enters a yellow phosphorus condensation system to produce finished yellow phosphorus. The dust filtered through the metal felt filter enters a closed spiral ash discharge system through a lower ash collection funnel. Example 2

[0038] The furnace gas temperature at the outlet of the phosphorus furnace is 130℃. It enters a backflushing system containing a metal felt filter to remove dust particles larger than 1μm. The surface temperature of the metal felt filter is controlled at 140-150℃. The phosphorus-containing furnace gas after dust separation enters a yellow phosphorus condensation system to produce finished yellow phosphorus. The dust filtered through the metal felt filter enters a closed spiral ash discharge system through a lower ash collection funnel. Example 3

[0039] The furnace gas temperature at the outlet of the phosphorus furnace is 145℃. It enters a backflushing system containing a metal felt filter to remove dust particles larger than 1μm. The surface temperature of the metal felt filter is controlled at 150℃. The phosphorus-containing furnace gas after dust separation enters a yellow phosphorus condensation system to produce finished yellow phosphorus. The dust filtered through the metal felt filter enters a closed spiral ash discharge system through a lower ash collection funnel.

Claims

1. A device for low-temperature dry dust removal of phosphorus furnace gas by interception, characterized in that... include: Two sets of metal felt interception filters (1), filter electric heaters (2), back-blowing system (3), ash collection funnel (4), spiral ash discharge machine (5) and fan (6) are connected in series. The outlet pipe (101) of the yellow phosphorus electric furnace gas is connected to the inlet of the metal felt interception filters (1) connected in series. Each metal felt interception filter (1) is equipped with a filter electric heater (2). The back-blowing system (3) achieves ash removal by adjusting the valve switch to back-blowing the gas flow. The filter cake outlet of the metal felt interception filter (1) is connected to the inlet of the ash collection funnel (4). The outlet of the metal felt interception filter (1) is connected to the inlet of the fan (6). The dust outlet at the bottom front side of the metal felt interception filter (1), the ash collection funnel (4) and the dust inlet of the closed spiral ash discharge machine (5) are sealed and connected. The air outlet of the fan (6) is the exhaust port of the device. The filter screen electric heater (2) is used to adopt the form of inner-lined resistance wire or sleeved electromagnetic heater according to the conditions and working conditions, and has a built-in temperature detection and control system to keep the filter screen temperature higher than 350-450℃. The fluid passes through the high-temperature metal felt interception filter screen (1) to make the phosphorus-containing droplets rapidly vaporize and pass through the filter screen with the gas phase, so that the yellow phosphorus does not adhere to the filter screen. There are adsorption, interception, collision and electrostatic effects between dust particles. Through the interception effect of the metal felt interception filter screen (1) with filter screen electric heater (2), the condensed phosphorus adhering to the dust particles is vaporized and enters the gas phase, keeping the dust dry is conducive to the desorption of dust during reverse blowing. The inlet pipe of the backflushing system (3) is connected to the outlet of the outlet pipe (101) of the yellow phosphorus electric furnace gas. A first airflow valve (301) is installed on the inlet pipe of the backflushing system (3). The outlet end of the inlet pipe of the backflushing system (3) is divided into two paths. The first path is connected to the air inlet of the outer cavity of the first filter electric heater (2) via the second pipeline. The third airflow valve (303) is located on the second pipeline. One end of the fifth airflow valve (305) is connected to the second pipeline between the third airflow valve (303) and the first filter electric heater. The other end of the fifth airflow valve (305) is connected to the outlet of the backflushing system (3) via the third pipeline. The outlet of the outer cavity of the first filter electric heater (2) is connected to the fourth pipeline. The air outlet of the cavity outside the second filter electric heater (2) is connected; the first pressure drop detector (307) is connected in parallel to both ends of the cavity outside the first filter electric heater (2); the second path of the outlet end of the air inlet pipe of the backflush system (3) is connected to the air inlet of the cavity outside the second filter electric heater (2) via the fifth pipeline; the fourth airflow valve (304) is located on the fifth pipeline; one end of the sixth airflow valve (306) is connected to the fifth pipeline between the fourth airflow valve (304) and the second filter electric heater; the other end of the sixth airflow valve (306) is connected to the air outlet of the backflush system (3) via the sixth pipeline; and the second pressure drop detector (308) is connected in parallel to both ends of the cavity outside the second filter electric heater (2).

2. The apparatus for low-temperature dry dust removal of phosphorus furnace gas as described in claim 1, characterized in that: The metal felt in the metal felt interception filter (1) is made of 316 or 310S stainless steel and is woven from 316 or 310S steel fibers; the surface pores of the metal felt are less than 1mm, and the disordered interweaving inside can achieve the interception of dust particles with a particle size greater than 0.01-0.001mm.

3. The apparatus for low-temperature dry dust removal of phosphorus furnace gas as described in claim 1, characterized in that: The backflush system (3) also includes a second airflow valve (302), and the air inlet pipe of the backflush system (3) is connected to the nitrogen storage tank through the second airflow valve.

4. The apparatus for low-temperature dry dust removal of phosphorus furnace gas as described in claim 1, characterized in that: By controlling the back-blowing system (3) to adjust the gas flow direction in a timely manner, the filter screen is self-cleaned. The combined induced draft fan (6) maintains the pressure difference between the two sides of the metal felt filter screen at no higher than 0.8-1.5 atm, and the pressure drop through the interception and dust removal device at no higher than 0.8-1.5 atm. When the pressure drop detector shows that the pressure drop is greater than or equal to 1.5 atm, the valve switch is changed to form a back-blowing process to remove the filter cake dust on the metal felt interception filter screen (1).

5. The apparatus for low-temperature dry dust removal of phosphorus furnace gas as described in claim 1, characterized in that: By controlling the back-purge system (3), the velocity of the fluid flowing through the metal felt interception filter (1) is controlled at 0.2~0.8m / s. At low velocity, the fluid passes through the metal felt interception filter (1) with the filter electric heater (2) and the temperature is raised from 140-180℃ in the yellow phosphorus electric furnace to no higher than 220℃ to achieve low-temperature dust removal.

6. The apparatus for low-temperature dry dust removal of phosphorus furnace gas as described in claim 1, characterized in that: A dust collection funnel (4) is set on the lower side of the metal felt intercepting filter screen (1), and a spiral dust discharge machine (5) is connected to the outlet end of the dust collection funnel (4) to ensure that the fluid gas velocity does not decrease during dust discharge and to prevent the introduction of air into the gas phase.

7. The apparatus for low-temperature dry dust removal of phosphorus furnace gas as described in claim 1, characterized in that: The high-temperature dust of 110-150℃ discharged by the spiral dust collector (5) enters the water pool for cooling and liquid sealing to prevent the high-temperature phosphorus-containing dust from spontaneously combusting in the air.

8. The apparatus for low-temperature dry dust removal of phosphorus furnace gas as described in claim 1, characterized in that: A low-pressure replacement nitrogen gas of 0.6 MPa is connected in parallel to the gas phase passage of the filter device. During equipment maintenance, shutdown, and disassembly and cleaning of the metal felt filter screen (1), nitrogen replacement is used to ensure that the phosphorus furnace gas does not come into contact with the air.

Images