Yellow phosphorus tail gas recycling system with multi-stage purification

Abstract

The utility model discloses a kind of yellow phosphorus tail gas recycling systems with multistage purification, including primary purification unit, energy utilization unit, secondary purification unit and tertiary purification unit, primary purification unit includes cyclone dust collector, catalytic reactor, deacidification reaction tower and cloth bag dust collector, secondary purification unit includes liquid accumulation tower and waste heat recovery mechanism, tertiary purification unit includes purification tower;The utility model primary purification unit, energy utilization unit, secondary purification unit and tertiary purification unit are used in combination, yellow phosphorus tail gas after primary dry-type treatment is used for boiler heating to carry out energy utilization, then secondary condensation recovery is carried out to acidic substance in flue gas after combustion and the waste heat in flue gas is recovered, tertiary liquid phase filtration, can effectively remove trace acidic gas possibly remaining in the first two stages and new-born particulate matter produced by combustion.Energy in yellow phosphorus tail gas is not only effectively utilized, and the cleanliness of gas finally discharged is extremely high, meet environmental protection emission standard.

Description

Technical Field

[0001] This utility model relates to the field of yellow phosphorus tail gas treatment technology, specifically to a yellow phosphorus tail gas recovery and utilization system with multi-stage purification. Background Technology

[0002] Yellow phosphorus exhaust contains waste gases such as carbon monoxide, sulfur dioxide, carbon dioxide, phosphine, and hydrogen sulfide. Unorganized emissions of yellow phosphorus exhaust can lead to an increase in the concentration of harmful gases in the surrounding air, which has an adverse impact on the environment.

[0003] Currently, yellow phosphorus is generally treated by water washing or alkaline washing. Although water washing and alkaline washing can remove most of the dust and particulate matter in the exhaust gas and reduce the pollution of the exhaust gas to the environment, the usable energy and substances in the exhaust gas are not effectively recovered and utilized, resulting in the waste of resources.

[0004] In addition, existing exhaust gas recovery technologies suffer from insufficient purification precision and serious residues of toxic gases. Existing water washing / alkali washing technologies can only remove about 2 / 3 of the dust and some sulfur dioxide, but cannot remove gaseous elemental phosphorus, phosphine, hydrogen fluoride and hydrogen sulfide combined in the exhaust gas.

[0005] Secondly, existing technologies have limited effectiveness in removing acidic substances such as sulfuric acid and phosphoric acid produced after exhaust gas combustion, and these components easily corrode the inner walls of equipment. At the same time, the waste heat of the flue gas after combustion is directly emitted, causing heat loss and leading to the direct diffusion of acidic gases produced by combustion, resulting in secondary environmental pollution.

[0006] Furthermore, in the existing water washing / alkaline washing process, phosphorus-containing compounds such as phosphine and phosphoric acid mist in the exhaust gas are discharged with the wastewater without being collected separately, which wastes phosphorus resources and increases wastewater treatment costs. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a yellow phosphorus tail gas recovery and utilization system that can reduce environmental pollution and incorporate multi-stage purification.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a yellow phosphorus tail gas recovery and utilization system with multi-stage purification, comprising a primary purification unit, an energy utilization unit, a secondary purification unit, and a tertiary purification unit.

[0009] The primary purification unit includes a cyclone dust collector, a catalytic reactor, a deacidification reaction tower, and a bag filter. The air inlet of the cyclone dust collector is connected to the exhaust pipe of the tail gas after water-vapor separation and drying treatment. The catalytic reactor is located on one side of the cyclone dust collector, and its inlet is connected to the air outlet of the cyclone dust collector. The air inlet of the deacidification reaction tower is connected to the outlet of the catalytic reactor. The dust gas inlet of the bag filter is connected to the air outlet of the acid reaction tower. An induced draft fan is also installed on the clean gas outlet of the bag filter.

[0010] The energy utilization unit includes a steam boiler, which is a horizontal water tube boiler structure and is located on the clean air outlet side of the bag filter. The fuel pipe of the steam boiler is connected to the induced draft fan on the clean air outlet of the bag filter. The bottom of the furnace of the steam boiler is provided with a drain channel that is inclined towards the tail outlet of the steam boiler. The drain channel has an inverted trapezoidal structure, and its inner wall surface is covered with an acid-resistant and corrosion-resistant lining. The bottom surface is fixed to the bottom of the furnace, and the top edge is sealed to the side wall of the furnace.

[0011] The secondary purification unit includes a liquid collection tower and a waste heat recovery mechanism. The inner wall of the liquid collection tower is covered with an acid-resistant and corrosion-resistant lining. An exhaust pipe is provided at the top of the tower, and the bottom is a conical tower base. A drain pipe is installed at the midpoint of the tower base, and the drain pipe is connected to an acid collection tank located below it. The middle and lower part of the liquid collection tower is connected to the tail outlet of the steam boiler through a conveying pipe. The waste heat recovery mechanism is a heat exchange module composed of multiple finned tubes. The waste heat recovery mechanism is installed in the upper middle part of the liquid collection tower. Its inlet pipe and outlet pipe extend outside the tower. The inlet pipe is connected to a cold water pool, and the outlet pipe is connected to a hot water usage point.

[0012] The three-stage purification unit includes a purification tower. The purification tower has an inlet pipe in the middle and a drain pipe at the bottom. The tower is filled with a weakly alkaline aqueous solution, and the liquid level is at least one-third of the tower body. An air supply pipe is provided on one side of the inlet pipe. The air supply pipe's inlet end is connected to the air outlet pipe of the liquid collection tower. The air outlet end of the air supply pipe enters the weakly alkaline aqueous solution in the purification tower. An air distributor is also installed on the air outlet end. The air distributor disperses the gas into a large number of fine bubbles, allowing them to fully contact the purified liquid. A demister is also installed in the upper part of the purification tower.

[0013] Preferably, to facilitate the catalytic conversion of gaseous elemental phosphorus and phosphine mixed in the exhaust gas into solid phosphorus pentoxide particles, the catalytic reactor is a tower structure. An inlet pipe is installed at the top of the tower, with a yellow phosphorus exhaust gas inlet and an air supply port for introducing air. An outlet pipe is installed at the bottom, and a discharge pipe is installed at the top. The inner wall of the tower is lined with an acid-resistant heat-insulating layer. A catalyst bed is installed in the middle of the tower. The catalyst bed includes a metal screen, inert alumina ceramic balls placed on the metal screen, and porous granular catalyst above the inert alumina ceramic balls. The tower of the catalytic reactor has corresponding sampling ports and catalyst loading / unloading ports for analyzing purification efficiency and loading catalyst. When the exhaust gas passes through the catalyst bed, under the action of the catalyst, the elemental phosphorus and phosphine in the exhaust gas are selectively oxidized into solid phosphorus pentoxide particles that fall to the bottom of the tower for collection, so that they can be subsequently removed for secondary utilization.

[0014] Furthermore, to ensure that the yellow phosphorus tail gas from upstream and the supplemented air can enter the catalyst bed evenly, a gas distributor is installed on the outlet end of the gas inlet pipe of the catalytic reactor, and is located at the top of the catalytic reactor, above the catalyst bed.

[0015] Preferably, to facilitate the adsorption and collection of acidic gases such as hydrogen fluoride and hydrogen sulfide mixed in the exhaust gas into particulates, the deacidification reaction tower is a vertical cylindrical steel tower with a conical bottom and an acid-resistant and corrosion-resistant layer on the inner wall. An exhaust pipe is installed at the top of the tower, an ash discharge pipe is installed at the bottom, and an air inlet pipe is installed in the middle of the tower. An injection hole is installed on the side opposite to the air inlet pipe, and the installation height of the injection hole is lower than that of the air inlet pipe. An adsorbent injection mechanism is provided at the injection hole. After the exhaust gas enters the deacidification reaction tower, the adsorbent injection mechanism sprays powdered adsorbent (such as activated alumina) into the tower. The adsorbent reacts chemically with the acidic gases such as hydrogen fluoride and hydrogen sulfide in the exhaust gas, adsorbing them into particulates that fall to the bottom of the tower for collection, so that they can be taken out for secondary use later. Finally, the bag filter efficiently traps and collects a small amount of phosphorus pentoxide particles mixed in the exhaust gas and acidic particles adsorbed after the reaction on the surface of the filter bag, so that the purified clean gas is discharged from the clean gas outlet.

[0016] Furthermore, the adsorbent injection mechanism includes an installation platform, a Venturi injector, a storage silo, and an air compressor. The installation platform is connected to the outer wall of the deacidification reaction tower. The mixed fluid outlet of the Venturi injector is connected to the injection hole through a pipe. The discharge port of the storage silo is connected to the agent inlet of the Venturi injector through a rotary feed valve. The air port of the air compressor is connected to the power fluid inlet of the Venturi injector.

[0017] Beneficial effects: ①. This utility model combines a primary purification unit, an energy utilization unit, a secondary purification unit, and a tertiary purification unit. The primary dry treatment of the yellow phosphorus tail gas allows for energy utilization through boiler heating. The secondary stage condenses and recovers acidic substances and residual heat from the combustion flue gas. The tertiary liquid-phase filtration effectively removes any trace amounts of acidic gases that may remain from the first two stages, as well as newly generated particulate matter. This not only effectively utilizes the energy within the yellow phosphorus tail gas but also results in extremely high gas cleanliness, meeting environmental emission standards.

[0018] ②. This utility model uses a dry adsorption method to remove recyclable substances from the exhaust gas and uses the combustible gas in the exhaust gas for boiler heating. This removes phosphorus, fluorine, sulfur, and dust mixed in with the exhaust gas before combustion, effectively preventing boiler corrosion and scaling, significantly extending boiler life, and improving thermal efficiency. At the same time, the acidic substances produced after combustion are condensed and recycled for secondary use, reducing environmental pollution. Moreover, this utility model uses a dry process, which does not produce wastewater, avoiding the water treatment problems caused by wet purification.

[0019] ③. This utility model also catalytically adsorbs substances such as phosphorus mixed in the exhaust gas into high-value-added chemical products such as phosphorus pentoxide, turning waste into treasure and creating additional economic benefits. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of this utility model.

[0021] Figure 2 This is a schematic diagram of the catalytic reactor in this invention.

[0022] Figure 3 This is a schematic diagram of the deacidification reaction tower in this utility model.

[0023] Figure 4 This is a schematic diagram of the steam boiler, liquid collection tower, and waste heat recovery mechanism in this utility model.

[0024] Figure 5 This is a schematic diagram of the purification tower in this utility model.

[0025] In the diagram: 1. Cyclone dust collector; 2. Catalytic reactor; 3. Deacidification reaction tower; 4. Bag filter dust collector; 5. Steam boiler; 6. Drainage channel; 7. Liquid collection tower; 8. Waste heat recovery mechanism; 9. Purification tower; 10. Air distributor; 11. Demister; 12. Metal screen; 13. Inert alumina ceramic balls; 14. Granular catalyst; 15. Gas distributor; 16. Mounting platform; 17. Venturi ejector; 18. Storage silo; 19. Air compressor. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Identical components are represented by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. Furthermore, the accompanying drawings are all in a very simplified form, using non-precise ratios, and are only used to facilitate and clearly illustrate the purpose of the embodiments of this utility model.

[0028] like Figure 1-5 As shown in the figure, this embodiment discloses a yellow phosphorus tail gas recovery and utilization system with multi-stage purification, including a primary purification unit, an energy utilization unit, a secondary purification unit and a tertiary purification unit.

[0029] from Figure 1 As can be seen, the primary purification unit includes a cyclone dust collector 1, a catalytic reactor 2, a deacidification reaction tower 3, and a bag filter 4. The air inlet of the cyclone dust collector 1 is connected to the exhaust pipe of the tail gas after water-vapor separation and drying treatment. The catalytic reactor 2 is located on one side of the cyclone dust collector 1, and the inlet of the catalytic reactor 2 is connected to the air outlet of the cyclone dust collector 1. (See [reference]) Figure 2 The catalytic reactor 2 is a tower structure. An air inlet pipe is installed at the top of the tower, with a yellow phosphorus tail gas inlet and an air supply port on the air inlet pipe. An air outlet pipe is installed at the bottom, and a discharge pipe is installed at the top. The inner wall of the tower is lined with an acid-resistant heat insulation layer. A catalyst bed is installed in the middle of the tower. The catalyst bed includes a metal screen 12, inert alumina ceramic balls 13 placed on the metal screen 12, and porous granular catalyst 14 above the inert alumina ceramic balls 13. The tower of the catalytic reactor 2 is provided with corresponding sampling ports and catalyst loading and unloading ports.

[0030] from Figure 2 It can be seen that a gas distributor 15 is installed on the gas outlet end of the gas inlet pipe of the catalytic reactor 2, and is located at the top of the catalytic reactor 2, above the catalyst bed.

[0031] See Figure 1 and Figure 3 The inlet pipe of the deacidification reaction tower 3 is connected to the outlet of the catalytic reactor 2. The deacidification reaction tower 3 is a vertical cylindrical steel tower with a conical bottom and an acid-resistant and anti-corrosion layer on the inner wall. An exhaust pipe is installed at the top of the tower body, an ash discharge pipe is installed at the bottom, an inlet pipe is installed in the middle of the tower body, and an injection hole is installed on the side opposite to the inlet pipe. The installation height of the injection hole is lower than that of the inlet pipe, and an adsorbent injection mechanism is provided at the injection hole.

[0032] See Figure 3The adsorbent injection mechanism includes an installation platform 16, a Venturi injector 17, a storage silo 18, and an air compressor 19. The installation platform 16 is connected to the outer wall of the deacidification reaction tower 3. The mixed fluid outlet of the Venturi injector 17 is connected to the injection hole through a pipe. The discharge port of the storage silo 18 is connected to the material inlet of the Venturi injector 17 through a rotary feed valve. The air port of the air compressor 19 is connected to the power fluid inlet of the Venturi injector 17.

[0033] See Figure 1 The dust inlet of the bag filter 4 is connected to the outlet pipe of the acid reaction tower, and an induced draft fan is also installed on the clean gas outlet of the bag filter 4.

[0034] See Figure 1 and Figure 4 The energy utilization unit includes a steam boiler 5, which is a horizontal water tube boiler structure and is located on the clean gas outlet side of the bag filter 4. The fuel pipe of the steam boiler 5 is connected to the induced draft fan on the clean gas outlet of the bag filter 4. The bottom of the furnace of the steam boiler 5 is provided with a drain channel 6 that is inclined towards the tail outlet of the steam boiler 5. The drain channel 6 is an inverted trapezoidal structure, and its inner wall surface is covered with an acid-resistant and corrosion-resistant lining. The bottom surface is fixed to the bottom of the furnace, and the top edge is sealed to the side wall of the furnace.

[0035] from Figure 4 As can be seen, the secondary purification unit includes a liquid collection tower 7 and a waste heat recovery mechanism 8. The inner wall surface of the liquid collection tower 7 is covered with an acid-resistant and corrosion-resistant lining. The top of the tower is equipped with an exhaust pipe, and the bottom is a conical tower bottom. A drain pipe is installed at the midpoint of the tower bottom, and the drain pipe is connected to an acid collection tank located below it. The middle and lower part of the liquid collection tower 7 is connected to the tail outlet of the steam boiler 5 through a conveying pipe. The waste heat recovery mechanism 8 is a heat exchange module composed of multiple finned tubes. The waste heat recovery mechanism 8 is installed in the upper middle part of the liquid collection tower 7. Its inlet pipe and outlet pipe extend out of the tower. The inlet pipe is connected to the cold water pool, and the outlet pipe is connected to the hot water usage point.

[0036] See Figure 1 and Figure 5 The three-stage purification unit includes a purification tower 9. The purification tower 9 has an inlet pipe in the middle and a drain pipe at the bottom. The tower is filled with a weakly alkaline aqueous solution, and the liquid level is at least one-third of the tower body. An air supply pipe is provided on one side of the inlet pipe. The air supply pipe's inlet end is connected to the air outlet pipe of the liquid collection tower 7. The air outlet end of the air supply pipe enters the weakly alkaline aqueous solution in the purification tower 9. An air distributor 10 is also installed on the air outlet end. The air distributor 10 disperses the gas into a large number of fine bubbles, so that they can fully contact the purification liquid. A demister 11 is also installed in the upper part of the purification tower 9.

[0037] Working Principle: The exhaust gas generated by the yellow phosphorus electric furnace, after passing through an external water-vapor separation device, enters the cyclone dust collector 1 to remove large dust particles. Subsequently, the exhaust gas enters the catalytic oxidation reactor, while air is simultaneously supplied through the air inlet. Under the action of the catalyst, as the exhaust gas passes through the catalyst bed, elemental phosphorus and phosphine in the exhaust gas are selectively oxidized into solid phosphorus pentoxide particles, which fall to the bottom of the tower for collection. Then, the exhaust gas enters the deacidification reaction tower 3, where powdered adsorbent (such as activated alumina) is sprayed into the tower by the adsorbent injection mechanism. The adsorbent reacts chemically with the acidic gases in the exhaust gas, adsorbing them into particles that fall to the bottom of the tower for collection. The exhaust gas continues to enter the pulse-jet bag filter 4, where the bag filter 4 efficiently traps a small amount of phosphorus pentoxide particles mixed in the exhaust gas and acidic particles adsorbed after the reaction on the surface of the filter bags for collection. The dust accumulated in the ash hopper of the bag filter 4 can be periodically discharged for recycling. The purified clean gas is discharged from the clean gas outlet and sent to the gas boiler for combustion and steam production by an induced draft fan.

[0038] After the exhaust gas enters the steam boiler 5, the carbon monoxide in the exhaust gas is burned as fuel in the steam boiler 5. During combustion, the remaining impurities in the exhaust gas, such as hydrogen sulfide, phosphine, hydrogen fluoride and other flammable gases, as well as sulfur, phosphorus and other impurity compounds, are converted into acidic substances during the combustion process. At this time, the acidic substances are dissolved in the flue gas in the boiler in the form of "superheated steam" and will not condense. When the flue gas flows through the waste heat recovery mechanism 8, the temperature drops below the acid dew point. The sulfuric acid, phosphoric acid and other substances dissolved in the flue gas will quickly condense on the heating surface tube wall to form combustion acid liquid. The formed acid liquid drips into the liquid collection tower 7 for collection. The acid liquid formed in the steam boiler 5 will enter the liquid collection tank through the liquid discharge channel 6 on the furnace.

[0039] Finally, the flue gas enters the weakly alkaline aqueous solution in the purification tower 9. The flue gas passes through the liquid layer in a bubbling form via the air distributor 10. During this process, the gas is further cooled, and any trace acidic oxides or dust that may remain are captured and absorbed by the liquid for the last time. After passing through this final barrier, the gas is considered to be clean gas that can be safely discharged.

[0040] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A multi-stage purification system for recovering and utilizing yellow phosphorus tail gas, comprising a primary purification unit, an energy utilization unit, a secondary purification unit, and a tertiary purification unit; characterized in that: The primary purification unit includes a cyclone dust collector (1), a catalytic reactor (2), a deacidification reaction tower (3), and a bag filter (4). The air inlet of the cyclone dust collector (1) is connected to the exhaust gas after water-vapor separation and drying. The catalytic reactor (2) is located on one side of the cyclone dust collector (1). The inlet of the catalytic reactor (2) is connected to the air outlet of the cyclone dust collector (1). The air inlet pipe of the deacidification reaction tower (3) is connected to the outlet of the catalytic reactor (2). The dust gas inlet of the bag filter (4) is connected through the air outlet pipe of the acid reaction tower. An induced draft fan is also installed on the clean gas outlet of the bag filter (4). The energy utilization unit includes a steam boiler (5), which is a horizontal water tube boiler structure and is located on the clean gas outlet side of the bag filter (4). The fuel pipe of the steam boiler (5) is connected to the induced draft fan on the clean gas outlet of the bag filter (4). The bottom of the furnace of the steam boiler (5) is provided with a drain channel (6) that is inclined toward the tail outlet of the steam boiler (5). The drain channel (6) is an inverted trapezoidal structure, and its inner wall surface is covered with an acid-resistant and corrosion-resistant lining. The bottom surface is fixed to the bottom of the furnace, and the top edge is sealed to the side wall of the furnace. The secondary purification unit includes a liquid collection tower (7) and a waste heat recovery mechanism (8). The inner wall surface of the liquid collection tower (7) is covered with an acid-resistant and corrosion-resistant lining. The top of the tower is equipped with an exhaust pipe, and the bottom is a conical tower bottom. A drain pipe is installed at the midpoint of the tower bottom. The drain pipe is connected to an acid collection tank located below it. The middle and lower part of the liquid collection tower (7) is connected to the tail outlet of the steam boiler (5) through a conveying pipe. The waste heat recovery mechanism (8) is a heat exchange module composed of multiple finned tubes. The waste heat recovery mechanism (8) is installed in the middle and above of the liquid collection tower (7). Its inlet pipe and outlet pipe extend out of the tower. The inlet pipe is connected to the cold water pool, and the outlet pipe is connected to the hot water usage point. The three-stage purification unit includes a purification tower (9). The purification tower (9) has an inlet pipe in the middle and a drain pipe at the bottom. The tower is filled with a weakly alkaline aqueous solution with a liquid level at least one-third of the tower body. An air supply pipe is provided on one side of the inlet pipe. The air supply pipe's inlet end is connected to the air outlet pipe of the liquid collection tower (7). The air outlet end of the air supply pipe enters the weakly alkaline aqueous solution in the purification tower (9). An air distribution device (10) is also installed on the air outlet end. The air distribution device (10) disperses the gas into a large number of tiny bubbles, allowing them to fully contact the purification liquid. A demister (11) is also installed in the upper part of the purification tower (9).

2. The yellow phosphorus tail gas recovery and utilization system with multi-stage purification according to claim 1, characterized in that: The catalytic reactor (2) is a tower structure. An air inlet pipe is installed at the top of the tower. The air inlet pipe is equipped with a yellow phosphorus tail gas inlet and an air supply port. An air outlet pipe is installed at the bottom and a discharge pipe is installed at the top. The inner wall of the tower is lined with an acid-resistant heat insulation layer. A catalyst bed is installed in the middle of the tower. The catalyst bed includes a metal screen (12), inert alumina ceramic balls (13) set on the metal screen (12), and porous granular catalyst (14) above the inert alumina ceramic balls (13). The tower of the catalytic reactor (2) is provided with corresponding sampling ports and catalyst loading and unloading ports.

3. The yellow phosphorus tail gas recovery and utilization system with multi-stage purification according to claim 2, characterized in that: A gas distributor (15) is installed on the outlet end of the inlet pipe of the catalytic reactor (2) and is located at the top of the catalytic reactor (2), above the catalyst bed.

4. A yellow phosphorus tail gas recovery and utilization system with multi-stage purification according to claim 1 or 2, characterized in that: The deacidification reaction tower (3) is a vertical cylindrical steel tower with a conical bottom and an acid-resistant anti-corrosion layer on the inner wall. An exhaust pipe is installed at the top of the tower body, an ash discharge pipe is installed at the bottom, an air inlet pipe is installed in the middle of the tower body, and a spray hole is installed on the side opposite to the air inlet pipe. The installation height of the spray hole is lower than that of the air inlet pipe, and an adsorbent spraying component is provided at the spray hole.

5. A yellow phosphorus tail gas recovery and utilization system with multi-stage purification according to claim 4, characterized in that: The adsorbent injection component includes an installation platform (16), a Venturi injector (17), a storage bin (18), and an air compressor (19). The installation platform (16) is connected to the outer wall of the deacidification reaction tower (3). The mixed fluid outlet of the Venturi injector (17) is connected to the injection hole through a pipe. The discharge port of the storage bin (18) is connected to the agent inlet of the Venturi injector (17) through a rotary feed valve. The air port of the air compressor (19) is connected to the power fluid inlet of the Venturi injector (17).

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