Plasma washing type waste gas treatment equipment

Abstract

The utility model discloses plasma water washing type waste gas treatment equipment which comprises a Y-shaped reaction chamber, a gas conveying pipeline and a cleaning chamber, and a plurality of through holes for gas to pass through are formed in an intersection of a Y-shaped structure of the Y-shaped reaction chamber; the periphery of the Y-shaped reaction chamber is provided with a funnel structure, the upper end of the funnel structure is connected with the intersection of the Y-shaped structure and is communicated with the Y-shaped reaction chamber through the through hole, the lower end of the funnel structure is provided with an opening, and the opening is positioned below the Y-shaped reaction chamber; a gas spray head is arranged in the gas conveying pipeline, is communicated with an oxygen inlet pipe and is used for forming a gas curtain wall; the cleaning chamber includes an alkali wash chamber for alkali wash of the exhaust gas. According to the utility model, waste gas is circularly combusted and fully oxidized, and alkali wash is added, so that emission of nitrogen oxides is eliminated.

Description

Technical Field

[0001] The utility model relates to the technical field of tail gas treatment equipment, in particular to a plasma water-washing type waste gas treatment equipment. Background Art

[0002] With the rapid development of the pan-semiconductor industry, the problem of waste gas treatment generated in the semiconductor manufacturing process has become increasingly prominent. Taking the semiconductor industry as an example, the waste gas generated by the semiconductor industry includes acidic waste gas, alkaline waste gas, organic waste gas, and waste gas discharged from the general exhaust system (General Exhaust System, GEX), etc. Among them, the waste gas discharged from the general exhaust system is pollution-free and plays a role in exhausting and dissipating heat.

[0003] Acidic waste gas comes from cleaning, sputtering, wet etching, wet stripping and process waste gas treated by waste gas treatment equipment (Local Scrubber). Its main components are HF, HCl, Cl2, H2SO4, SO2, etc.; alkaline waste gas mainly comes from cleaning, wet etching, photolithography, stripping, chemical-mechanical polishing (CMP) and other processes, and its main components are NH3, NaOH, etc.; organic waste gas mainly comes from cleaning, chemical vapor deposition (CVD), photolithography, wet etching, stripping and diffusion and other processes, and its main components are isopropyl alcohol, acetone, propylene glycol monomethyl ether acetate, ethyl lactate, butyl acetate, heavy aromatics, etc.

[0004] The above waste gas contains a variety of hazardous gases, which not only pose a serious threat to the environment, but also may cause safety accidents such as fire and explosion. In order to effectively treat these waste gases and protect the environment and personnel safety, the semiconductor, panel, photovoltaic and other industries generally use waste gas treatment equipment technology.

[0005] There are many brands of waste gas treatment equipment on the market. According to the treatment principle, they can be divided into electric heating water washing, combustion water washing, water washing, dry adsorption, plasma water washing, etc. Among them, plasma water washing waste gas treatment equipment is considered to be the preferred technology for future hazardous waste gas treatment because of its high temperature and reducing characteristics, which can achieve the perfect combination of organic gasification and inorganic melting.

[0006] Plasma water-washing waste gas treatment equipment drives an arc torch through a DC power supply to generate high-temperature plasma to decompose waste gas. This technology has the advantages of high energy density, fast reaction speed, and high treatment efficiency. It can achieve harmless treatment of solid waste gas and is applicable to almost all types of waste gas. However, in practical applications, plasma water-washing waste gas treatment equipment may produce nitric oxide (NO) during high-temperature reactions. NO is difficult to dissolve in water, causing emission problems of equipment, especially NO, leading to environmental pollution and reduced equipment performance. Literature research shows that the optimal thermal decomposition temperature of NO is 600℃~1000℃. Within this temperature range, NO can be decomposed into nitrogen (N2) and oxygen (O2), but when the temperature exceeds 1300℃, nitrogen (N2) and oxygen (O2) will react to generate NO. However, in practice, in order to achieve the highest treatment efficiency, plasma water-washing waste gas treatment equipment usually needs to increase the temperature to 3000K (about 2727℃), which is far beyond the optimal decomposition temperature of NO and cannot effectively remove NO.

[0007] Therefore, it is urgent to optimize the plasma water-washing waste gas treatment equipment to solve the problem of its emission of harmful gas NO. Utility Model Content

[0008] The purpose of the utility model is to optimize the plasma water-washing waste gas treatment equipment to achieve the maximum elimination of nitrogen monoxide. The improvement plan includes one or more of circulating combustion, full oxidation and adding alkaline washing to the waste gas to ensure that the waste gas after plasma treatment does not contain harmful substances and meets environmental emission standards.

[0009] In order to achieve the above-mentioned purpose, the utility model provides a plasma water-washing waste gas treatment equipment for eliminating nitrogen oxides, comprising a "Y"-shaped reaction chamber, a quenching chamber, a circulating alkali liquid tank, a gas delivery pipeline, a cleaning chamber and an exhaust pipeline, wherein the quenching chamber is arranged around the periphery of the "Y"-shaped reaction chamber; the circulating alkali liquid tank is located below the quenching chamber and is connected to the bottom outlet of the quenching chamber, the gas delivery pipeline is connected to the side wall of the quenching chamber, the gas delivery pipeline, the cleaning chamber and the exhaust pipeline are connected in sequence,

[0010] The intersection of the "Y"-shaped structure of the "Y"-shaped reaction chamber includes a plurality of through holes for gas to pass through; a funnel structure is provided on the periphery of the "Y"-shaped reaction chamber, the upper end of the funnel structure is connected to the intersection of the "Y"-shaped structure, and is connected to the "Y"-shaped reaction chamber through the through holes, and an opening is provided at the lower end of the funnel structure, and the opening is located below the "Y"-shaped reaction chamber.

[0011] Furthermore, a gas nozzle is provided in the gas delivery pipeline, the gas nozzle is connected to the oxygen inlet pipe, and the gas nozzle is used to form a gas curtain wall in the internal section of the gas delivery pipeline.

[0012] Furthermore, the cleaning chamber comprises an alkali washing chamber for alkali washing the exhaust gas.

[0013] Furthermore, the gas delivery pipeline further includes a venturi tube after the gas nozzle.

[0014] Furthermore, the gas nozzle is any one of an impact ring nozzle, a spray nozzle, a fan nozzle or a rotating nozzle.

[0015] Furthermore, the gas nozzle is an impact annular nozzle.

[0016] Furthermore, the alkaline liquid in the alkaline washing chamber contains sodium hydroxide with a volume fraction greater than 5%.

[0017] Furthermore, the alkaline liquid in the alkaline washing chamber is alkaline waste liquid generated after the circulating alkaline liquid tank absorbs the waste gas.

[0018] Compared with the prior art, the utility model has at least the following beneficial effects:

[0019] (1) The utility model includes a gas collecting chamber formed by a funnel structure, the upper end of the funnel structure is connected to the intersection of the "Y"-shaped structure of the "Y"-shaped reaction chamber, and the lower end opening is located below the "Y"-shaped reaction chamber. Since the lower end diameter of the funnel structure is small, part of the exhaust gas can be collected in the gas collecting chamber; a plurality of through holes are provided at the intersection of the "Y"-shaped structure, and the exhaust gas in the gas collecting chamber can enter the "Y"-shaped reaction chamber through the through holes. The utility model enables the exhaust gas after high-temperature decomposition to be re-transported to the intersection of the "Y"-shaped structure for multiple times, and utilizes the low-temperature tail flame (about 700°C) of the plasma flame to circulate and burn NO in the exhaust gas, thereby achieving sufficient decomposition of nitrogen oxides.

[0020] (2) In the utility model, an impact ring nozzle is installed in the gas delivery pipeline of the equipment, and the impact ring nozzle is connected to the oxygen (O2) inlet pipe to form an annular O2 curtain wall in the gas delivery pipeline, so that O2 and NO can fully contact and undergo oxidation reaction, thereby further eliminating NO; a Venturi tube is also installed after the impact ring nozzle to accelerate the exhaust gas and reduce the impact of the annular O2 curtain wall on the gas flow.

[0021] (3) In the present invention, the cleaning chamber of the equipment is further equipped with an alkaline cleaning chamber, which utilizes alkaline liquid to absorb nitrogen dioxide (NO2) generated in the O2 curtain wall, thereby achieving complete elimination of nitrogen oxides.

[0022] (4) In the present invention, no additional alkaline liquid is required, and the alkaline wastewater generated by the circulating alkaline liquid tank in the equipment can be directly utilized, thereby saving costs and space.

[0023] (5) In the present invention, there is no need to make major changes to the equipment, and there is no need to add large-scale nitrogen oxide treatment equipment. The equipment can self-decompose nitrogen oxides to the greatest extent and reduce nitrogen oxide emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of the plasma water washing type waste gas treatment equipment of the present utility model.

[0025] Description of the accompanying drawings:

[0026] An air intake pipe 10, a "Y"-shaped reaction chamber 20, a quenching chamber 30, a circulating alkali solution tank 40, a gas delivery pipe 50, an exhaust pipe 60, an oxygen intake pipe 70, a cleaning chamber 80, a through hole 21, a funnel structure 31, a gas nozzle 51, a Venturi tube 52, a water washing chamber 81, an alkali washing chamber 82, and a plasma water washing type waste gas treatment device 100. DETAILED DESCRIPTION

[0027] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] In the description of the present invention, it should be noted that the terms "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.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" 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; 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.

[0030] like Figure 1 As shown, the plasma water-washing waste gas treatment equipment includes an air intake pipe 10 , a “Y”-shaped reaction chamber 20 , a quenching chamber 30 , a circulating alkali solution tank 40 , a gas delivery pipe 50 and an exhaust pipe 60 .

[0031] The air inlet pipe 10 is connected to the top of the "Y"-shaped reaction chamber 20. Exhaust gas from the semiconductor process is introduced into the "Y"-shaped reaction chamber 20 through the air inlet pipe 10 for ionization and decomposition treatment.

[0032] The "Y"-shaped reaction chamber 20 includes a plasma generator (not shown), which includes an arc torch driven by direct current. Through a direct current power supply, under the action of strong positive and negative currents, the working gas (N2) is ionized into plasma, and a huge flame is instantly generated. Under the action of plasma, the waste gas molecules (such as Cl2, F2, SF6, CF4, NF3, etc.) are ionized, bombarded and decomposed at high temperature, and converted into various active particles. The active particles combine to generate acidic gases soluble in water and / or neutral gases that can be directly discharged for subsequent treatment. Among them, the acidic gas includes hydrogen chloride, fluorine-containing gas, etc., and the neutral gas includes carbon dioxide, nitrogen, etc.

[0033] The quenching chamber 30 is arranged around the periphery of the "Y"-shaped reaction chamber 20. The "Y"-shaped reaction chamber 20 and the quenching chamber 30 form a nested structure. The inner wall of the quenching chamber 30 and the outer wall of the "Y"-shaped reaction chamber 20 form a cavity, and the bottom outlet of the "Y"-shaped reaction chamber 20 is connected with the "Y"-shaped reaction chamber 20. The waste gas after the reaction in the "Y"-shaped reaction chamber 20 flows downward along the inner wall of the "Y"-shaped reaction chamber 20 to reach the bottom of the "Y"-shaped reaction chamber 20. A part of the waste gas enters the quenching chamber 30 and flows from bottom to top along the outer wall of the "Y"-shaped reaction chamber 20. The quenching chamber 30 includes a multi-layer spray system (not shown in the figure), which performs the first water washing on the waste gas from top to bottom to fully convert the acidic gas (such as hydrogen chloride) into an acidic liquid (such as hydrochloric acid).

[0034] The circulating alkali liquid tank 40 is located below the quenching chamber 30 and is connected to the bottom outlet of the quenching chamber 30. A portion of the exhaust gas from the bottom of the "Y"-shaped reaction chamber 20 directly enters the circulating alkali liquid tank 40 for alkali washing; the solid products (such as sulfates and nitrites) generated from the "Y"-shaped reaction chamber 20 directly fall into the circulating alkali liquid tank 40; the acidic liquid from the quenching chamber 30 flows downward into the circulating alkali liquid tank 40 for alkali washing, and a neutralization reaction occurs during the process to achieve the purpose of removing pollutants. The circulating alkali liquid tank 40 contains an alkaline liquid, and the alkaline liquid contains a NaOH solution with a volume fraction greater than 5%.

[0035] The gas delivery pipeline 50 is in communication with the side wall of the quenching chamber 30 to output the escaped gas insoluble in water or the alkaline solution in the quenching chamber 30 for further treatment. A cleaning chamber 80 is also provided between the gas delivery pipeline 50 and the exhaust pipeline 60. The cleaning chamber 80 includes a water washing chamber 81, which performs a second water washing on the remaining exhaust gas from the quenching chamber 30 to further remove the remaining pollutants.

[0036] In the existing plasma water-washing waste gas treatment equipment, the waste gas is discharged into the atmosphere after the above-mentioned high-temperature ionization and decomposition, the first water washing, the alkali washing and the second water washing.

[0037] However, there is a problem of NO generation in the Y-shaped reaction chamber 20. The working gas of the plasma generator is nitrogen (N2), which will be ionized into positively charged ions (N2 + ), N2 + Can combine with oxygen to generate NO: N2 + +O2→2NO. The reaction of nitric oxide with oxygen is an exothermic reaction, so under high-temperature discharge reaction conditions, nitric oxide will not further react to form nitrogen dioxide.

[0038] Given that NO is a harmful gas, and due to its low solubility in water and its non-reaction with water, existing plasma water-washing waste gas treatment equipment has encountered significant challenges in controlling NO emissions.

[0039] In order to solve the problem of the generation and emission of nitrogen oxides by the existing plasma water-washing waste gas treatment equipment, the utility model optimizes the existing plasma water-washing waste gas treatment equipment and provides a plasma water-washing waste gas treatment equipment 100 for eliminating nitrogen oxide emissions, comprising the air intake pipe 10, "Y"-shaped reaction chamber 20, quenching chamber 30, circulating alkali solution tank 40, waste gas delivery pipe 50 and exhaust pipe 60 as described above.

[0040] Continue to see Figure 1In the plasma water-washing waste gas treatment equipment 100 of the utility model, a funnel structure 31 is provided on the periphery of the "Y"-shaped reaction chamber 20, the upper end of the funnel structure 31 is connected to the intersection of the "Y"-shaped structure of the "Y"-shaped reaction chamber 20, and the lower end opening of the funnel structure 31 is located below the "Y"-shaped reaction chamber 20. A gas collecting chamber is formed between the inner wall of the funnel structure 31 and the outer wall of the "Y"-shaped reaction chamber 20.

[0041] The funnel structure 31 is used to collect the waste gas after the reaction inside the "Y"-shaped reaction chamber 20. The opening diameter at the lower end of the funnel structure 31 is small, so part of the waste gas can be gathered to a certain extent in the lower end of the funnel structure 31, forming a large gas pressure, pushing the gas gathered at the lower end of the funnel structure 31 to flow upward between the inner wall of the funnel structure 31 and the outer wall of the "Y"-shaped reaction chamber 20, reaching the intersection of the "Y"-shaped structure, forming the gas collection chamber. Since the lower end of the funnel structure 31 has an opening, the solid product generated in the "Y"-shaped reaction chamber 20 can still fall into the circulating alkali solution tank 40 through the opening.

[0042] A plurality of through holes 21 for gas passage are provided at the intersection of the "Y"-shaped structure, and the gas collection chamber is connected to the "Y"-shaped reaction chamber through the through holes 21. The exhaust gas in the gas collection chamber passes through the through holes 21 and enters the internal chamber at the intersection of the "Y"-shaped structure, and is then reburned by the tail flame of the plasma flame. The intersection of the "Y"-shaped structure is the tail flame area of ​​the plasma flame. Studies have shown that, especially at the intersection of the "Y"-shaped structure, the tail flame temperature of the plasma flame is about 700°C. Given that the decomposition temperature range of NO is 600°C to 1000°C, this temperature condition is sufficient to promote the decomposition of NO into N2 and O2, thereby achieving effective decomposition of NO at the intersection of the "Y"-shaped structure. The exhaust gas can be gathered and re-transported for multiple times, and then directed into the tail flame area of ​​the plasma flame to achieve cyclic combustion, thereby maximizing the decomposition and elimination of NO.

[0043] In the plasma water-washing waste gas treatment equipment 100 provided by the present invention, a cavity for performing the first water washing on the waste gas is still formed between the outer wall of the funnel structure 31 and the inner wall of the quenching chamber 30 .

[0044] Based on the above scheme, in order to further eliminate NO, a gas nozzle 51 is installed inside the gas delivery pipeline 50, and the gas nozzle 51 is connected to the oxygen inlet pipe 70. The gas nozzle 51 is any one of an impact annular nozzle, a spray nozzle, a fan nozzle or a rotating nozzle. Preferably, the gas nozzle 51 is an impact annular nozzle. Oxygen is delivered to the impact annular nozzle, and the supply pressure of the oxygen is 3kg / cm 2 ~6kg / cm 2 , the flow rate is 4LPM to 10LPM (LPM is liters per minute), the impact annular nozzle uses high-speed gas flow to generate impact force, sprays the oxygen to the inner wall of the gas delivery pipeline 50, and forms an annular oxygen curtain wall in the internal section of the gas delivery pipeline 50. At room temperature, when the exhaust gas passes through the annular oxygen curtain wall, it can fully contact with oxygen, and the nitric oxide in the exhaust gas reacts with the oxygen in the annular oxygen curtain wall: 2NO+O2→2NO2. The generated nitrogen dioxide is soluble in water and can be dissolved and absorbed in the subsequent water washing chamber 81, and the reaction formula is: 2NO2+H2O→HNO2+HNO3.

[0045] In this embodiment, since the annular curtain wall will slow down the flow speed of the exhaust gas in the gas delivery pipe 50, a venturi tube 52 is installed after the impact annular nozzle. The venturi tube 52 includes a gradually contracting inlet section, a throat (the narrowest point), and a gradually expanding outlet section. Based on the Venturi effect, the exhaust gas can be accelerated after passing through the venturi tube 52, thereby reducing the influence of the annular curtain wall on the flow of the exhaust gas.

[0046] Furthermore, in order to eliminate nitrogen dioxide generated by the oxidation reaction of nitrogen monoxide, in this embodiment, the cleaning chamber 80 also includes an alkaline cleaning chamber 82, and the alkaline cleaning chamber 82 is located between the gas delivery pipeline 50 and the water washing chamber 81. The alkaline cleaning chamber 82 contains an alkaline liquid. In this embodiment, the alkaline liquid can directly use the alkaline waste liquid generated by the circulating alkaline liquid tank 40 without the need for additional alkaline liquid. The NO2 in the waste gas reacts in the alkaline liquid: NO2+OH - +1 / 2O2→NO3 - +H2O, thereby further effectively eliminating nitrogen oxides in the exhaust gas.

[0047] In summary, the plasma water-washing waste gas treatment equipment provided by the utility model realizes multiple combustion decomposition and elimination of nitric oxide by adding a cyclic combustion process of waste gas in the "Y"-shaped reaction chamber; by adding an oxygen curtain wall in the gas delivery pipeline, nitric oxide is fully oxidized to nitrogen dioxide, thereby further eliminating nitric oxide; and by adding an alkaline washing chamber in the cleaning chamber, nitrogen dioxide is absorbed. Therefore, the utility model integrates the above solutions to maximize the elimination of nitrogen oxides generated inside the plasma water-washing waste gas treatment equipment, and is expected to solve the nitrogen oxide emission problem in the pan-semiconductor industry to the greatest extent.

[0048] Although the content of the utility model has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the utility model. After reading the above content, various modifications and substitutions of the utility model will be obvious to those skilled in the art. Therefore, the protection scope of the utility model should be limited by the attached claims.

Claims

1. A plasma water-washing waste gas treatment device, comprising a "Y"-shaped reaction chamber, a quenching chamber, a circulating alkali liquid tank, a gas delivery pipeline, a cleaning chamber and an exhaust pipeline, wherein the quenching chamber is arranged around the periphery of the "Y"-shaped reaction chamber; the circulating alkali liquid tank is located below the quenching chamber and is connected to the bottom outlet of the quenching chamber, the gas delivery pipeline is connected to the side wall of the quenching chamber, the gas delivery pipeline, the cleaning chamber and the exhaust pipeline are connected in sequence, characterized in that: The intersection of the "Y"-shaped structure of the "Y"-shaped reaction chamber includes a plurality of through holes for gas to pass through; a funnel structure is provided on the periphery of the "Y"-shaped reaction chamber, the upper end of the funnel structure is connected to the intersection of the "Y"-shaped structure, and is connected to the "Y"-shaped reaction chamber through the through holes, and an opening is provided at the lower end of the funnel structure, and the opening is located below the "Y"-shaped reaction chamber.

2. The plasma water washing type waste gas treatment equipment according to claim 1, characterized in that: A gas nozzle is arranged in the gas delivery pipeline, the gas nozzle is communicated with the oxygen inlet pipe, and the gas nozzle is used to form a gas curtain wall in the internal section of the gas delivery pipeline.

3. The plasma water washing type waste gas treatment equipment according to claim 2, characterized in that: The gas delivery pipeline also includes a venturi tube after the gas nozzle.

4. The plasma water washing type waste gas treatment equipment according to claim 2, characterized in that: The gas nozzle is any one of an impact annular nozzle, a spray nozzle, a fan-shaped nozzle or a rotating nozzle.

5. The plasma water washing type waste gas treatment equipment according to claim 4, characterized in that: The gas nozzle is an impact annular nozzle.

6. The plasma water washing type waste gas treatment equipment according to claim 1, characterized in that: The cleaning chamber comprises an alkali washing chamber for alkali washing the exhaust gas.

7. The plasma water washing type waste gas treatment equipment according to claim 6, characterized in that: The alkaline liquid in the alkaline washing chamber contains sodium hydroxide with a volume fraction greater than 5%.

8. The plasma water washing type waste gas treatment equipment according to claim 6, characterized in that: The alkaline liquid in the alkaline washing chamber is the alkaline waste liquid generated after the circulating alkaline liquid tank absorbs the waste gas.

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