Fluorine-containing waste gas treatment system

Abstract

The utility model discloses a fluorine-containing waste gas treatment system which comprises a spraying device, a waste gas inlet is formed in the lower end of the spraying device, a first annular spray head is arranged at the upper end in the spraying device, and a first filler is arranged in an area between the waste gas inlet and the annular spray head; a first waste liquid outlet is formed in the lower end of the spraying device; the upper end of the chemical absorption device is provided with a dosing port for carbide slag, a calcium chloride solution and a polyacrylamide solution, the inner upper end of the chemical absorption device is provided with a reaction tank, the inner middle end of the chemical absorption device is provided with a filter pressing device, and the inner lower end of the chemical absorption device is provided with an acid solution dosing pipe and a neutralizing device; a second waste liquid outlet, a first waste liquid reflux inlet and a second waste liquid reflux inlet are formed in the lower end of the chemical absorption device; a first water inlet is formed in the upper end of the water tank, and a second water inlet and a water outlet are formed in the lower end.

Description

Technical Field

[0001] The utility model relates to the technical field of waste gas treatment, in particular to a fluorine-containing waste gas treatment system. Background Art

[0002] The emission of fluorine-containing waste gases poses potential risks to ecosystems and human health. In recent years, solar cells, as a key component of the photovoltaic industry, have experienced rapid development. The solar cell production process typically includes wafer cleaning, texturing, pickling, phosphorus diffusion, edge etching, plasma chemical vapor deposition (PECVD), screen printing, dry sintering, testing, and packaging. Hydrofluoric acid is widely used in these production processes, and the solar cell production process generates large amounts of fluorine-containing waste gases such as HF, CF4, SiF4, and Cl2. Fluorine-containing waste gases are highly toxic, with a pungent odor and strong corrosive effects. For example, silicon tetrafluoride is an asphyxiating gas that can cause significant harm to the human body upon inhalation, with harm levels 20 times greater than those of sulfur dioxide gas. The further spread and transfer of fluorine-containing waste gases can also lead to air, soil, and water pollution, corrode buildings and equipment in the external environment, and, more seriously, damage the ozone layer.

[0003] There are two common methods for removing fluorine from waste gas: dry and wet. The principle of dry adsorption is to use solid alkaline substances to adsorb fluorine-containing waste gas, and then a chemical reaction will occur on the surface layer of the alkaline substance to achieve the purpose of removing the waste gas. Usually, solid-phase adsorbents such as Al2O3 (γ-type), CaO, and CaCO3 are used. The calcium fluoride, aluminum fluoride, or cryolite generated by the reaction between the waste gas and the adsorbent can be recycled as raw materials or sold as by-products. The advantages are that the equipment is corrosion-free, the cost is low, and there is no wastewater discharge. However, there are problems such as the inability to absorb continuously and the need to reprocess the fluorine-containing compounds after absorption. Wet spraying is used to treat fluoride in waste gas, and a reasonable concentration of absorption liquid is required. If the concentration of the absorption liquid is too high, the fluoride in the waste gas can be removed, but the treatment cost will increase. If the concentration of the absorption liquid is too low, the absorption efficiency of fluoride in the waste gas will be low, affecting the treatment effect of the system. Utility Model Content

[0004] In view of this, an embodiment of the present invention provides a fluorine-containing waste gas treatment system to solve the problem that the wet method for removing fluorine from waste gas in the prior art cannot further improve the waste gas treatment efficiency while controlling the waste gas treatment cost.

[0005] The present invention provides a fluorine-containing waste gas treatment system, comprising:

[0006] The spray device has an exhaust gas inlet at its lower end, a first annular nozzle at its inner upper end, and a first filler at the area between the exhaust gas inlet and the annular nozzle; and a first waste liquid outlet at its lower end.

[0007] A chemical absorption device, wherein the upper end of the device is provided with a dosing port for carbide slag, calcium chloride solution and polyacrylamide solution; the upper end of the interior of the chemical absorption device is a reaction tank; the middle end of the interior of the chemical absorption device is provided with a filter press device; the lower end of the interior of the chemical absorption device is provided with an acid solution dosing pipe and a neutralization device; the lower end of the chemical absorption device is provided with a second waste liquid discharge port, a first waste liquid reflux port and a second waste liquid reflux port;

[0008] a water tank having a first water inlet at its upper end and a second water inlet and a water outlet at its lower end;

[0009] Among them, the water outlet of the water tank is connected to the nozzle of the spray device through a first conduit and a first water pump; the second water inlet of the water tank is connected to the first waste liquid reflux port of the chemical absorption device through a second conduit and a second water pump; the first waste liquid discharge port of the spray device is connected to the reaction tank of the chemical absorption device through a third conduit and a third water pump; the upper end of the spray device is connected to the chemical absorption device through an air guide pipe extending into the reaction tank; the neutralization device and the reaction tank are connected through a fourth conduit and a fourth water pump.

[0010] Optionally, a second annular nozzle and a second filler are provided at the inner middle end of the spraying device.

[0011] Optionally, the first annular nozzle and the second annular nozzle are respectively controlled to pump water through two water pumps.

[0012] Optionally, it further includes: a first stirring paddle, which is arranged in the reaction tank of the chemical absorption device.

[0013] Optionally, the method further comprises: a second stirring paddle, which is arranged in the neutralization device of the chemical absorption device.

[0014] Optionally, the filter press device includes: a filter press pump and a filter press.

[0015] Optionally, it further includes: a first fluorine-resistant pH electrode, arranged in the reaction tank.

[0016] Optionally, it further includes: a second fluorine-resistant pH electrode and a fluoride ion electrode, which are arranged in the neutralization device.

[0017] Beneficial effects of the utility model:

[0018] The embodiment of the present utility model provides a fluorine-containing waste gas treatment system, including a spray device, a chemical absorption device, a filter press device, a neutralization device and a water tank, etc. The left side of the water tank is connected to the water inlet pipe, and the right side is connected to the spray device through a conduit with a pump, so that the water in the water tank is pumped into the spray device. The lower end of the spray device is connected to the waste gas inlet, and the upper end of the interior is provided with an annular nozzle and filler. The sprayed water mist and the waste gas are countercurrent, which increases the contact area and time of the reaction and makes the gas and the liquid solvent fully contact; the upper and lower ends of the spray device are respectively connected to the chemical absorption device through conduits. The utility model adopts an aqueous solution of calcium carbide slag as an absorption liquid, treats waste with waste, reduces the treatment cost of fluorine-containing waste gas, and has high absorption efficiency. In addition, the fluorine-containing waste gas treatment device provided by the embodiment of the present utility model can reuse most of the wastewater generated, saves the amount of water used for spraying, reduces costs, and improves work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

[0020] Figure 1 The figure shows a structural diagram of a fluorine-containing waste gas treatment system in an embodiment of the present utility model. DETAILED DESCRIPTION

[0021] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions 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 embodiments described 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0022] The present invention provides a fluorine-containing waste gas treatment system. Figure 1 As shown, it includes: a spray device 1, a chemical absorption device 2 and a water tank, wherein the lower end of the spray device 1 is provided with a waste gas inlet 101, the upper end of the interior of the spray device 1 is provided with an annular nozzle 102, and a filler 103 is provided in the area between the waste gas inlet 101 and the annular nozzle 102; the lower end of the spray device is provided with a first waste liquid discharge outlet.

[0023] The chemical absorption device 2 has a dosing port 201 for carbide slag, calcium chloride solution and polyacrylamide (PAM) solution at its upper end, a reaction tank at the internal upper end of the chemical absorption device 2, a filter press device 210 at the internal middle end of the chemical absorption device 2, an acid solution dosing pipe 202 and a neutralization device 220 at the internal lower end of the chemical absorption device 2; and a second waste liquid discharge port 203, a first waste liquid reflux port and a second waste liquid reflux port at the lower end of the chemical absorption device 2.

[0024] The water tank 3 has a first water inlet 301 at its upper end and a second water inlet and a water outlet at its lower end.

[0025] Among them, the water outlet of the water tank 3 is connected to the nozzle of the spray device 1 through a first conduit and a first water pump 501; the second water inlet of the water tank 3 is connected to the first waste liquid reflux port of the chemical absorption device 2 through a second conduit and a second water pump 502; the first waste liquid discharge port of the spray device 1 is connected to the reaction tank of the chemical absorption device 2 through a third conduit and a third water pump 503; the upper end of the spray device 1 is connected to the chemical absorption device 2 through an air duct extending into the reaction tank; the neutralization device 220 and the reaction tank are connected through a fourth conduit and a fourth water pump 504.

[0026] As an optional embodiment, a second annular nozzle and a second filler are provided at the inner middle end of the spray device to form a secondary spray device.

[0027] As an optional embodiment, the first annular nozzle and the second annular nozzle are respectively controlled by two water pumps to pump water. In actual use, one or two water pumps are selected to be turned on according to the flow rate of the exhaust gas to be treated, so as to reasonably allocate resources.

[0028] As an optional embodiment, the method further includes: a first stirring paddle 204 disposed in the reaction tank of the chemical absorption device.

[0029] As an optional embodiment, the method further includes: a second stirring paddle 205 , which is arranged in the neutralization device of the chemical absorption device.

[0030] As an optional embodiment, the filter press device 210 includes: a filter press pump 2101 and a filter press 2102 .

[0031] As an optional embodiment, it further includes: a first fluorine-resistant pH electrode 206, which is arranged in the reaction tank.

[0032] As an optional embodiment, it further includes: a second fluorine-resistant pH electrode and a fluoride ion electrode 207, which are arranged in the neutralization device.

[0033] The embodiment of the present utility model provides a fluorine-containing waste gas treatment system, including a spray device, a chemical absorption device, a filter press device, a neutralization device and a water tank. The left side of the water tank is connected to the water inlet pipe, and the right side is connected to the spray device through a conduit with a pump, so that the water in the water tank is pumped into the spray device. The lower end of the spray device is connected to the exhaust gas inlet, and the upper end of the interior is provided with an annular nozzle and filler. The sprayed water mist and the exhaust gas are countercurrent, which increases the contact area and time of the reaction and makes the gas and the liquid solvent fully contact; the upper and lower ends of the spray device are respectively connected to the chemical absorption device through a conduit. The upper end of the chemical absorption device is provided with a dosing port for solutions such as calcium carbide slag, calcium chloride, and PAM; the chemical absorption device is provided with a stirring paddle inside to ensure that the solution in the chemical absorption device fully reacts; the chemical absorption device is provided with a fluorine-resistant pH electrode inside to monitor the pH value of the solution in the chemical absorption device; the lower end of the chemical absorption device is connected to the filter press device. The filter press device includes a filter press pump and a filter press; the lower end of the filter press is connected to the neutralization device, and a fluorine-resistant pH electrode is installed inside the neutralization device to monitor the pH of the filtrate to meet the emission standards; a fluoride ion electrode is installed inside the neutralization device to monitor the concentration of fluoride ions in the filtrate. If the standard is met, part of it will be discharged from the waste liquid outlet, and part will enter the water tank for spraying. If the standard is not met, it will enter the chemical absorption device for reaction again.

[0034] As an optional embodiment, a nozzle that is resistant to clogging and has high spray force and fine density is used to enhance the gas-liquid mass transfer efficiency.

[0035] As an optional embodiment, a random bed of plastic ball rings is used as a packing layer.

[0036] The spray device in this utility model is a two-stage spray device, utilizing the double-membrane theory of gas-liquid mass transfer. When fluorine-containing waste gas enters the spray device from the bottom and rises within it, water from a water tank is pumped into the spray device. Water is sprayed evenly from the nozzle from top to bottom, creating countercurrent contact with the fluorine-containing waste gas. The fluorine-containing waste gas flows through the packing layer, ensuring thorough mixing of the gas and liquid, thereby ensuring efficient absorption of the hydrogen fluoride in the fluorine-containing waste gas. Unabsorbed fluorine-containing waste gas is directed through a conduit at the top of the spray device into a chemical absorption device. Fluorine-containing waste water, having absorbed the hydrogen fluoride, flows into the bottom of the spray device and is pumped into the chemical absorption device by a pump. During the stirring process, the unabsorbed fluorine-containing waste gas, fluorine-containing waste water, and carbide slag solution undergo a chemical reaction. The pH of the solution in the chemical absorption device is monitored using a fluorine-resistant pH electrode. By controlling the amount of carbide slag solution added, the pH of the solution in the device is controlled between 6.5 and 9.2, maximizing the conversion of fluoride ions into calcium fluoride. However, the calcium fluoride precipitate particles generated are small and will be in a suspended state, so polyacrylamide (PAM) flocculant needs to be added for flocculation. By taking advantage of the common ion effect of calcium chloride on calcium fluoride, adding calcium chloride to the chemical absorption device can reduce the solubility of calcium fluoride and make the reaction reach final stability. The calcium fluoride suspension generated in the chemical absorption device enters the filter press through the filter press pump, is automatically filtered through the filter press, and the filtrate enters the neutralization device. The amount of HCL added is controlled by a fluorine-resistant pH electrode, and the filtrate is neutral; the fluoride ion electrode is used to monitor the fluoride ion concentration of the filtrate in the neutralization device. If it meets the standard, part of it will be discharged from the waste liquid outlet and part will enter the water tank for spraying. If it does not meet the standard, it will enter the chemical absorption device and react again.

[0037] The utility model uses carbide slag aqueous solution as the absorption liquid, treating waste with waste, reducing the treatment cost of fluorine-containing waste gas and achieving high absorption efficiency. In addition, the fluorine-containing waste gas treatment device provided by the utility model embodiment can reuse most of the wastewater generated, saving spray water, reducing costs, and improving work efficiency.

[0038] In view of the shortcomings of wet and dry methods in treating fluorine-containing waste gas, the utility model also proposes a fluorine-containing waste gas treatment device, which adopts an aqueous solution of calcium carbide slag as an absorption liquid. When the fluorine-containing waste gas passes through the absorption liquid containing calcium carbide slag, the fluoride (such as HF) in the waste gas will react with the calcium hydroxide in the absorption liquid to generate calcium fluoride precipitate: Ca(OH)2+2HF→CaF2+2H2O, which reduces the treatment cost of the fluorine-containing waste gas and has high absorption efficiency.

[0039] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations shall fall within the scope defined by the appended claims.

Claims

1. A fluorine-containing waste gas treatment system, characterized in that: include: A spray device, wherein the lower end of the spray device is provided with an exhaust gas inlet, the upper end of the interior of the spray device is provided with a first annular nozzle, and the area between the exhaust gas inlet and the annular nozzle is provided with a first filler; the lower end of the spray device is provided with a first waste liquid discharge port; A chemical absorption device, wherein the upper end of the device is provided with a dosing port for carbide slag, calcium chloride solution, and polyacrylamide solution; the upper end of the interior of the chemical absorption device is a reaction tank; the middle end of the interior of the chemical absorption device is provided with a filter press device; the lower end of the interior of the chemical absorption device is provided with an acid solution dosing pipe and a neutralization device; and the lower end of the chemical absorption device is provided with a second waste liquid discharge port, a first waste liquid return port, and a second waste liquid return port; a water tank having a first water inlet at its upper end and a second water inlet and a water outlet at its lower end; In which, the water outlet of the water tank is connected to the nozzle of the spraying device through a first conduit and a first water pump; the second water inlet of the water tank is connected to the first waste liquid reflux port of the chemical absorption device through a second conduit and a second water pump; the first waste liquid discharge port of the spraying device is connected to the reaction tank of the chemical absorption device through a third conduit and a third water pump; the upper end of the spraying device is connected to the chemical absorption device through an air duct extending into the reaction tank; the neutralization device and the reaction tank are connected through a fourth conduit and a fourth water pump.

2. The fluorine-containing waste gas treatment system according to claim 1, characterized in that: A second annular nozzle and a second filler are provided at the inner middle end of the spraying device.

3. The fluorine-containing waste gas treatment system according to claim 2, characterized in that: The first annular nozzle and the second annular nozzle are respectively controlled to pump water through two water pumps.

4. The fluorine-containing waste gas treatment system according to claim 1, characterized in that: Also includes: The first stirring paddle is arranged in the reaction tank of the chemical absorption device.

5. The fluorine-containing waste gas treatment system according to claim 1, characterized in that: Also includes: The second stirring paddle is arranged in the neutralization device of the chemical absorption device.

6. The fluorine-containing waste gas treatment system according to claim 1, characterized in that: The filter press device comprises a filter press pump and a filter press.

7. The fluorine-containing waste gas treatment system according to claim 1, characterized in that: Also includes: The first fluorine-resistant pH electrode is arranged in the reaction tank.

8. The fluorine-containing waste gas treatment system according to claim 1, characterized in that: Also includes: A second fluorine-resistant pH electrode and a fluoride ion electrode are arranged in the neutralization device.

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