Method and device for treating tail gas generated in production of electronic-grade organic cleaning agent solution

Abstract

The invention discloses a treatment method and device for electronic-grade organic cleaning agent solution production tail gas, and the method comprises the steps of tail gas separation, acid adsorption, alkaline adsorption, oxidation treatment and physical adsorption, the tail gas subjected to oxidation treatment and physical adsorption can be directly discharged. According to the method, macromolecular organic substances, acidic substances and alkaline substances in the electronic-grade organic cleaning agent solution production tail gas are separately treated, the macromolecular organic substances are oxidized and adsorbed to obtain clean air which can be directly discharged, and the acidic substances and the alkaline substances are adsorbed by acid and alkali to obtain tail gas which can be returned to a reactor to be recycled, so that the tail gas is recycled. And the pollution to the environment is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of organic cleaning agent production, and in particular relates to a method and a device for treating tail gas produced by electronic-grade organic cleaning agent solution. Background Art

[0002] Since silicon wafers may be contaminated during transportation, the surface cleanliness is not very high, which can have a great impact on the upcoming corrosion and etching. Therefore, a series of cleaning operations must be performed on the surface of the silicon wafer first. The general idea of ​​cleaning is to first remove organic contamination on the surface, and then dissolve the oxide film, because the oxide layer is a "contamination trap" that will cause epitaxial defects; then remove particles, metals, etc., and passivate the surface of the silicon wafer. Silicon wafer cleaning agents are often used in this process. With the development of the chip industry and the improvement of preparation accuracy, the demand and quality of electronic-grade silicon wafer cleaning agents required in the silicon wafer preparation process have increased year by year. However, during the trial production process, it was found that the raw salt used in the production of silicon wafer cleaning agents contained a large amount of metal impurities, and most raw materials could not meet the requirement of metal less than 1ppb. Therefore, the prepared silicon wafer cleaning agent could not meet the electronic grade requirements, which seriously affected the cleaning effect of the silicon wafer. Therefore, at present, the improvement method for the excessively high content of metal impurities in raw salt is to use more primary raw materials to synthesize raw salt independently; and in order to avoid the introduction of impurities, the process is strictly controlled, and the product is required to be generated in one step, and the production process of raw salt needs to be neutralized with high-quality acid and / or alkali, which is volatilized during the feeding and production process. Therefore, a large amount of organic matter will be generated in the production process of raw salt and the tail gas containing acid or alkali will be released periodically. If the tail gas is not treated and directly discharged, it will seriously pollute the environment. For example, a preparation system and process of electronic-grade ammonium fluoride disclosed in Chinese patent CN112058199A, wherein the production process of electronic-grade ammonium fluoride is to mix industrial-grade 49% high-purity hydrofluoric acid with ammonia and fully react to form ammonium fluoride, wherein ammonia is heated by liquid ammonia. In the production process of electronic-grade ammonium fluoride, volatile hydrofluoric acid, ammonia, ammonium fluoride and other gases will be periodically generated as the reaction proceeds. Since hydrofluoric acid, ammonia, etc. are easily soluble in water and can react with many alkaline substances to form salts, water or alkali solution is generally used to absorb and treat tail gas. However, this method is only applicable to the treatment of ammonium fluoride tail gas. For tail gas containing organic matter and periodically containing acid and alkali produced in the production process of other electronic-grade raw salts, the treatment efficiency is poor, and the treated tail gas cannot be recycled. Therefore, it is necessary to provide a tail gas treatment method and device to achieve the treatment of tail gas with complex components and periodic changes. Summary of the invention

[0003] In view of the above technical problems, the present invention provides a method and device for treating exhaust gas produced by electronic-grade organic cleaning solution, which can separately treat the macromolecular organic substances and acidic substances and alkaline substances in the exhaust gas produced by electronic-grade organic cleaning solution. The clean air obtained by oxidation and adsorption of the macromolecular organic substances can be directly discharged, while the exhaust gas obtained by acidic substances and alkaline substances after acid and alkali adsorption can be returned to the reactor for reuse, thereby reducing pollution to the environment.

[0004] In order to achieve the above object, the present invention provides a method for treating tail gas produced by electronic grade organic cleaning agent solution, comprising the following steps: (1) Tail gas separation: The tail gas generated by the reactor is collected and separated using a gas separation membrane in a separation tower. The tail gas with a molecular weight ≥500 is precipitated and condensed to obtain a macromolecular solution, and the tail gas with a molecular weight ≤100 is collected and raised to obtain an acid-base mixed tail gas; (2) Acid adsorption: The acid-base mixed tail gas is absorbed by the acid spray tower to obtain acid tail gas; (3) Alkaline adsorption: The acidic tail gas is absorbed by the alkaline spray tower to obtain the recovered gas, which is then recycled; (4) Oxidation treatment: The macromolecular solution is oxidized in an oxidation tower to produce oxidized tail gas; (5) Physical adsorption: The oxidized exhaust gas is adsorbed by an activated carbon adsorption device to obtain clean exhaust gas.

[0005] Preferably, when the content of harmful substances in the clean tail gas in step (5) is ≥40 mg / m 3 When the content of harmful substances in the clean exhaust gas is less than 40 mg / m 3 When, directly discharge.

[0006] More preferably, the harmful substance is one or more of HF, organic amine and organic ammonia.

[0007] Preferably, the tail gas in step (1) comprises 2-5% organic amine, 1-3% acid and 1-5% alkali; and the pore size of the gas separation membrane is 5-250 nm.

[0008] Preferably, the acid spray tower described in step (2) contains an acidic solution, wherein the acidic solution is sulfuric acid or phosphoric acid, with a mass fraction of 5-10%; the flow rate of the acid-base mixed tail gas is 0.5 m / s; and the spray flow rate of the acidic solution in the acid spray tower is 0.4-0.6 m / s.

[0009] Preferably, the alkaline spray tower in step (3) contains an alkaline solution, wherein the alkaline solution is KOH or NaOH with a mass fraction of 5-10%; the flow rate of the acidic tail gas is 0.5 m / s; and the spray flow rate of the alkaline solution in the alkaline spray tower is 0.4-0.6 m / s.

[0010] Preferably, the oxidation tower in step (4) contains a strong oxidizing acid, and the strong oxidizing agent is HNO 3 Or potassium permanganate, mass fraction is 5-10%.

[0011] The present invention also provides a device for treating tail gas produced by electronic-grade organic cleaning agent solution, wherein the reactor is connected to the separation tower via a tail gas pipe, the separation tower is connected to the acid spray tower via a gas transmission pipe, the acid spray tower is connected to the alkaline spray tower via an acid gas pipeline, and the alkaline spray tower is connected to the reactor via a recovery gas channel; The separation tower is connected to the oxidation tower via a liquid infusion pipe, the oxidation tower is connected to the activated carbon adsorption tower via a waste gas pipe, and the activated carbon adsorption tower is connected to the exhaust tower via a clean air duct.

[0012] Preferably, a gas separation membrane is provided in the separation tower; the liquid infusion pipe is a double U-shaped structure; the bottom of the acid spray tower is connected to an acid circulation pump, and the acid circulation pump is connected to the top of the acid spray tower through an acid sprayer; an acid atomization module is provided on the acid sprayer; The bottom of the alkaline spray tower is connected to an alkaline circulation pump, and the alkaline circulation pump is connected to the top of the alkaline spray tower via an alkaline sprayer; an alkaline atomization module is arranged on the alkaline sprayer.

[0013] Preferably, a harmful gas detection device is provided on the activated carbon adsorption tower; the activated carbon adsorption tower is connected to the oxidation tower via a reflux pipe; the activated carbon adsorption tower is connected to the oxidation tower via a reflux pipe; a reflux control valve is provided on the reflux pipe.

[0014] The beneficial effects of the present invention are: 1. The tail gas produced by the electronic-grade organic cleaning agent production is separated to obtain acid-base mixed tail gas and macromolecular solution. The acid-base mixed tail gas is sprayed and absorbed by acidic solution and alkaline solution to obtain recovered tail gas, which can be returned to the production reactor for recycling. The macromolecular solution is oxidized and adsorbed to produce tail gas with extremely low content of harmful substances, which can be directly discharged. Targeted treatment of tail gas of different components is achieved, so that the treated tail gas can be recycled or directly discharged, reducing the negative impact on the environment.

[0015] 2. Use a spray tower, a circulation pump, a sprayer and an atomization module to evenly spray the solution inside the spray tower, fully contacting it with the gas, accelerating the reaction while making the exhaust gas treatment more complete.

[0016] 3. A double U-shaped infusion pipe and an oxidation tower are set at the bottom of the separation tower. The macromolecular solution separated by the separation tower is deposited in the infusion pipe to prevent the tail gas generated by oxidation from returning to the separation tower and affecting the separation effect. At the same time, other gas components are avoided from being introduced into the recovered tail gas, thereby reducing the impact on the production process.

[0017] 4. The process and structure of the present invention are simple, and it can be applied to the treatment of tail gas with complex components and dynamically changing components, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the overall structure of the exhaust gas treatment device constructed in Example 1.

[0019] Figure 2 A cross-sectional view of a separation tower.

[0020] Figure 3 A cross-sectional view of the acid spray tower.

[0021] Figure 4 It is a schematic diagram of the structure of the spray device, in which A is an acid spray device and B is an alkaline spray device.

[0022] In the figure, 1 is a tail gas pipe, 2 is a separation tower, 3 is a gas pipe, 4 is a liquid infusion pipe, 5 is an acid spray tower, 6 is an acid gas pipeline, 7 is an alkaline spray tower, 8 is a recovery gas duct, 9 is an oxidation tower, 10 is an exhaust gas pipe, 11 is an activated carbon adsorption tower, 12 is a harmful gas detection device, 13 is a clean air duct, 14 is an exhaust tower, 15 is a gas separation membrane, 16 is an acid sprayer, 17 is an acid circulation pump, 18 is an acid atomization module, 19 is an alkaline sprayer, 20 is an alkaline circulation pump, 21 is an alkaline atomization module, 22 is a reactor, 23 is a reflux pipeline, and 24 is a reflux control valve. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be understood as limiting the present invention. The protection scope of the present invention shall be based on the contents recorded in the claims. Any modification or replacement made by those skilled in the art to the technical solution of the present invention without creative work shall fall within the protection scope of the present invention.

[0024] Example 1 like Figure 1-4The invention shows a device for treating tail gas produced by electronic-grade organic cleaning agent solution, wherein a reactor 16 is connected to a separation tower 2 via a tail gas pipe 1, the separation tower 2 is connected to an acid spray tower 5 via a gas pipeline 3, the acid spray tower 5 is connected to an alkaline spray tower 7 via an acid gas pipeline 6, and the alkaline spray tower 7 is connected to the reactor 16 via a recovery gas channel 8; gases with different molecular weights in the tail gas are separated, and gas substances with smaller molecular weights are collected in the upper part of the separation tower 2, and then transported to the acid spray tower 5 via the gas pipeline 3 for acid adsorption, and the remaining acid gas after adsorption is completed is transported to the alkaline spray tower 7 via the acid gas pipeline 6 for alkaline adsorption, and the recovered tail gas obtained by adsorption treatment can be returned to the reactor 16 for recycling.

[0025] The separation tower 2 is connected to the oxidation tower 9 via the infusion pipe 4, the oxidation tower 9 is connected to the activated carbon adsorption tower 11 via the exhaust pipe 10, and the activated carbon adsorption tower 11 is connected to the exhaust tower 14 via the clean air duct 13; gas substances with larger molecular weight gather at the bottom of the separation tower 2, condense to obtain a macromolecular solution, and store it in the infusion pipe 4. When the highest liquid level of the infusion pipe 4 exceeds its U-shaped structure, the liquid inside the infusion pipe 4 will enter the oxidation tower 9 for oxidation and absorption according to the principle of communicating vessels. Oxidized tail gas is generated during the oxidation process, which is transported to the activated carbon adsorption tower 11 through the exhaust pipe 10 for filtration and adsorption, and the clean gas is discharged through the exhaust tower 14.

[0026] Preferably, a gas separation membrane 15 is provided in the separation tower 2 for separating gaseous substances with different molecular weights; the liquid infusion tube 4 is a double U-shaped structure for temporarily storing condensed macromolecular solutions and preventing gas backflow.

[0027] Preferably, the bottom of the acid spray tower 5 is connected to an acid circulation pump 17, and the acid circulation pump 17 is connected to the top of the acid spray tower 5 via an acid sprayer 16; an acid atomization module 18 is provided on the acid sprayer 16; the acid solution is circulated and sprayed into the acid spray tower 5 for acid adsorption.

[0028] Preferably, the bottom of the alkaline spray tower 7 is connected to the alkaline circulation pump 20, and the alkaline circulation pump 20 is connected to the top of the alkaline spray tower 7 through the alkaline sprayer 19; the alkaline sprayer 19 is provided with an alkaline atomization module 21; the alkaline solution is circulated and sprayed into the alkaline spray tower 7 for alkaline adsorption.

[0029] Preferably, a harmful gas detection device 12 is provided on the activated carbon adsorption tower 11 for detecting the composition of the gas in the activated carbon adsorption tower 11; the activated carbon adsorption tower 11 is connected to the oxidation tower 9 via a reflux pipe 17, so as to facilitate the transportation of unqualified gas to the oxidation tower 9 for secondary treatment.

[0030] Preferably, the activated carbon adsorption tower 11 is connected to the oxidation tower 9 via a reflux pipe 23, and the unqualified gas is refluxed into the oxidation tower 9 for secondary oxidation treatment until the gas meets the emission standards; a reflux control valve 24 is provided on the reflux pipe 23, which is interlocked with the harmful gas detection device 12 to control the reflux of the gas.

[0031] Example 2 A method for treating tail gas produced by electronic grade organic cleaning agent solution comprises the following steps: (1) Tail gas separation: the tail gas generated in the reactor 16 is collected and transported to the separation tower 2 through the tail gas pipe 1 for separation. Specifically, after the tail gas enters the separation tower 2, the tail gas with a molecular weight ≤100 passes through the gas separation membrane 15 (particle size is 5-250nm) and is collected upward to the top of the separation tower 2. The tail gas is an acid-base mixed tail gas; the tail gas with a molecular weight ≥500 cannot pass through the gas separation membrane 15 and is enriched and condensed into a solution at the bottom of the separation tower 2. The solution is a macromolecular solution. The flow rate of the tail gas entering the separation tower 2 is 0.5m / s. (2) Acid adsorption: The acid-base mixed tail gas collected at the top of the separation tower 2 is transported to the bottom of the acid spray tower 5 through the gas transmission pipe 4, and is sprayed and absorbed by the acid solution in the acid spray tower 5 to obtain the acid tail gas enriched in the upper part of the acid spray tower 5; wherein the spray flow rate of the acid solution is 0.5 m / s, and the flow rate of the acid-base mixed tail gas is 0.5 m / s; (3) Alkaline adsorption: The acidic tail gas is transported to the bottom of the alkaline spray tower 7 through the acid gas pipeline 6, and after being sprayed and absorbed by the alkaline solution therein, the recovered tail gas is enriched in the upper part of the alkaline spray tower 7. The recovered tail gas is collected through the recovery gas channel 8 and returned to the reactor 16 for recycling. The spray flow rate of the acid solution is 0.5 m / s, and the flow rate of the acid-base mixed tail gas is 0.5 m / s. At this time, the pH value of the recovered tail gas is 6-8, and the organic matter content is less than 40 mg / m 3 ; (4) Oxidation treatment: The macromolecular solution enriched and condensed in the separation tower 2 is collected in the infusion pipe 4. When the highest liquid level of the macromolecular solution exceeds the highest position of the infusion pipe 4, the excess macromolecular solution in the infusion pipe 4 is transported to the oxidation tower 9 according to the communicating vessel principle, mixed with the strong oxidant solution (5-10%) therein, and an oxidation reaction occurs to generate oxidized tail gas, which is enriched at the top of the oxidation tower 9; (5) The oxidized tail gas is transported to the top of the activated carbon adsorption tower 11 through the exhaust pipe 10, and then filtered and adsorbed by the activated carbon and then detected by the harmful gas detection device 12 at the bottom. When the harmful gas content is less than 40 mg / m 3 The gas is transported to the exhaust tower 14 through the clean air duct 13 for discharge. The gas meets the GB 37822-2019 standard during discharge. When the harmful gas content is ≥40mg / m 3The oxidized gas is then refluxed to the bottom of the oxidation tower 9 through the reflux pipe 17 for secondary oxidation treatment.

[0032] Preferably, the tail gas in step (1) comprises 2-5% organic amine, 1-3% acid and 1-5% alkali.

[0033] Preferably, the acidic solution in step (2) is sulfuric acid or phosphoric acid, with a mass fraction of 5-10%.

[0034] Preferably, the alkaline solution in step (3) is KOH or NaOH, with a mass fraction of 5-10%.

[0035] Preferably, the strong oxidant solution in step (4) is HNO 3 Or potassium permanganate, mass fraction is 5-10%.

Claims

1. A method for treating tail gas produced by electronic grade organic cleaning agent solution, characterized in that: The steps include: (1) Tail gas separation: the tail gas generated by the collection reactor (16) is separated by using the gas separation membrane (15) in the separation tower (2); the tail gas with a molecular weight ≥500 is precipitated and condensed to obtain a macromolecular solution, and the tail gas with a molecular weight ≤100 is raised and collected to obtain an acid-base mixed tail gas; (2) Acid adsorption: The acid-base mixed tail gas is absorbed by the acid spray tower (5) to obtain acid tail gas; (3) Alkaline adsorption: The acidic tail gas is absorbed by the alkaline spray tower (6) to obtain recovered gas, which is then recycled; (4) Oxidation treatment: The macromolecular solution is oxidized in an oxidation tower (9) to generate oxidation tail gas; (5) Physical adsorption: The oxidized tail gas is adsorbed by an activated carbon adsorption tower (11) to obtain clean tail gas.

2. The method for treating tail gas produced by production of an electronic-grade organic cleaning agent solution according to claim 1, characterized in that: When the content of harmful substances in the clean exhaust gas in step (5) is ≥40mg / m 3 When the content of harmful substances in the clean exhaust gas is less than 40 mg / m 3 When, directly discharge.

3. The method for treating tail gas produced by the production of an electronic-grade organic cleaning agent solution according to claim 2, characterized in that: The harmful substances are one or more of HF, organic amines and organic ammonia.

4. The method for treating tail gas produced by production of electronic grade organic cleaning agent solution according to claim 1, characterized in that: The tail gas in step (1) comprises 2-5% organic amine, 1-3% acid and 1-5% alkali; the pore size of the gas separation membrane (15) is 5-250 nm.

5. The method for treating tail gas produced by the production of electronic grade organic cleaning agent solution according to claim 1, characterized in that: The acid spray tower (5) described in step (2) contains an acid solution, wherein the acid solution is sulfuric acid or phosphoric acid with a mass fraction of 5-10%; the flow rate of the acid-base mixed tail gas is 0.5 m / s.

6. The method for treating tail gas produced by the production of electronic grade organic cleaning agent solution according to claim 1, characterized in that: The alkaline spray tower (6) described in step (3) contains an alkaline solution, wherein the alkaline solution is KOH or NaOH with a mass fraction of 5-10%; the flow rate of the acidic tail gas is 0.5 m / s.

7. The method for treating tail gas produced by production of electronic grade organic cleaning agent solution according to claim 1, characterized in that: The oxidation tower (9) described in step (4) contains a strong oxidizing acid, wherein the strong oxidizing agent is HNO3 or potassium permanganate, with a mass fraction of 5-10%.

8. A device for treating tail gas produced by electronic grade organic cleaning agent solution, characterized in that: The reactor (16) is connected to the separation tower (2) via the tail gas pipe (1), the separation tower (2) is connected to the acid spray tower (5) via the gas transmission pipe (3), the acid spray tower (5) is connected to the alkaline spray tower (7) via the acid gas pipeline (6), and the alkaline spray tower (7) is connected to the reactor (16) via the recovery gas duct (8); The separation tower (2) is connected to the oxidation tower (9) via a liquid infusion pipe (4), the oxidation tower (9) is connected to the activated carbon adsorption tower (11) via an exhaust gas pipe (10), and the activated carbon adsorption tower (11) is connected to the exhaust tower (14) via a clean air duct (13).

9. The device for treating tail gas produced by electronic-grade organic cleaning solution according to claim 7, characterized in that: The separation tower (2) is provided with a gas separation membrane (15); the liquid infusion pipe (4) is a double U-shaped structure; The bottom of the acid spray tower (5) is connected to an acid circulation pump (17), and the acid circulation pump (17) is connected to the top of the acid spray tower (5) via an acid sprayer (16); an acid atomization module (18) is provided on the acid sprayer (16); The bottom of the alkaline spray tower (7) is connected to an alkaline circulation pump (20), and the alkaline circulation pump (20) is connected to the top of the alkaline spray tower (7) via an alkaline sprayer (19); an alkaline atomization module (21) is provided on the alkaline sprayer (19).

10. The device for treating tail gas produced by electronic-grade organic cleaning agent solution according to claim 7, characterized in that: The activated carbon adsorption tower (11) is provided with a harmful gas detection device (12); the activated carbon adsorption tower (11) is connected to the oxidation tower (9) via a reflux pipe (17); the activated carbon adsorption tower (11) is connected to the oxidation tower (9) via a reflux pipe (23); and the reflux pipe (23) is provided with a reflux control valve (24).

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