CN110255506A - A kind of apparatus and method of electronic-grade sulfuric acid production - Google Patents

Abstract

The invention discloses a device and method for producing electronic grade sulfuric acid. The sulfur trioxide raw material storage tank is connected to the vaporizer through the raw material pump, the top of the vaporizer is connected to the demister, the top of the demister is connected to the top of the cooler, the bottom of the cooler is connected to the buffer tank, and the buffer tank is connected to the feed pump It is connected with vaporizer 2, vaporizer 2 is connected with absorption tower, the bottom of absorption tower is connected with buffer tank 2, the bottom of buffer tank 2 is connected with cooler 2 through circulating acid pump, cooler 2 is connected with stripping tower, and the stripping tower is connected to electronic grade sulfuric acid storage tank. Transport sulfur trioxide to vaporizer 1, the vaporized sulfur trioxide enters cooler 1, condenses into a liquid state and then enters buffer tank 1, the sulfur trioxide in buffer tank 1 is transported to vaporizer by feed pump, and enters absorption tank after being vaporized again In the absorption tower, ultra-pure water is used for cyclic absorption, and the secondary product of the cooler is produced stably through the pipeline. After subsequent aeration treatment, the quality of the sulfuric acid product reaches the SEMI‑C12 level.

Description

A device and method for producing electronic grade sulfuric acid

technical field

The invention belongs to the field of electronic chemicals, in particular to a device and method for producing electronic-grade sulfuric acid.

Background technique

Electronic grade sulfuric acid, also known as ultra-pure sulfuric acid, is an ultra-clean and high-purity reagent. It is the most widely used wet electron chemistry in the industry. It is mainly used for cleaning, photolithography, corrosion of silicon wafers, corrosion and cleaning of printed circuit boards, and can effectively remove impurities, inorganic residues and carbon deposits on the wafer. Electronic grade sulfuric acid has been used for cleaning silicon wafers for over 40 years. It is an indispensable key basic chemical reagent in the semiconductor industry. Its purity directly affects the yield of integrated circuits.

The main production methods of electronic grade sulfuric acid are industrial sulfuric acid rectification method or direct absorption method of sulfur trioxide gas; rectification method can be divided into atmospheric rectification and vacuum rectification. Higher, generally expensive quartz glass is used; the temperature of vacuum distillation is generally 175-190°C, the pressure is 1.33-2.67kPa, and the device can use cheaper borosilicate glass and fluoropolymer materials. Restricted by equipment and energy, distillation is suitable for small-scale production. This method is difficult to achieve large-scale production of high-purity electronic-grade sulfuric acid.

At present, some domestic enterprises use the direct absorption method of sulfur trioxide gas to produce electronic-grade sulfuric acid, but they still face problems such as the difference in the purity of sulfur trioxide raw materials, the difficulty of separating impurities, and the fragility of lining equipment, which is easy to be damaged when improperly operated. Product quality is difficult to further breakthrough. The invention makes innovations in production equipment, production and control methods, solves the problems of raw material purity differences and difficulty in impurity separation, and protects production devices at the same time.

Contents of the invention

The object of the present invention is to provide a device and method for producing electronic grade sulfuric acid, which has reliable process and stable product quality, and can reach SEMI-C12 level (metal concentration ≤ 0.1 μg/L).

The invention discloses a device for producing electronic-grade sulfuric acid, which comprises a sulfur trioxide raw material storage tank, a vaporizer one, a demister, a cooler one, a buffer tank one, a vaporizer two, an absorption tower, a buffer tank two, a cooler two, The stripping tower, the sulfur trioxide raw material storage tank is connected to the vaporizer through the raw material pump, the top of the vaporizer is connected to the demister, the top of the demister is connected to the top of the cooler, the bottom of the cooler is connected to the buffer tank, and the buffer tank The feed pump is connected to the second vaporizer, the second vaporizer is connected to the absorption tower, the bottom of the absorption tower is connected to the buffer tank two, the bottom of the buffer tank two is connected to the second cooler through the circulating acid pump, the second cooler is connected to the stripping tower, and the gas stripping The column is connected to an electronic grade sulfuric acid storage tank.

Cooler 2 is connected to the absorption tower and to the sprayer in the absorption tower. The upper part of the absorption tower is provided with at least two stages of trays, and a liquid collection tray is provided under the trays, and holes are arranged on the collection tray. Circular holes are arrayed on the liquid collection tray, which can eliminate the "wall flow" effect and avoid high temperature damage to the lower tray of the absorption tower due to lack of liquid; the middle part of the absorption tower is equipped with an ultrapure water feeding pipe.

An ultrapure water inlet pipe is arranged on the upper part of the absorption tower; an air inlet pipe is arranged on the stripping tower.

In the above scheme, the bottom of the sulfur trioxide raw material storage tank is connected to the raw material pump through pipelines and connected to vaporizer one; the bottom of buffer tank one is connected to the feed pump through pipelines and connected to vaporizer two.

In the above scheme, there are two stages of wire mesh packing in the demister, and the material is PP, PE or PTFE wire mesh;

The demister is provided with two-stage wire mesh packing, which is made of PP, PE or PTFE wire mesh.

The first vaporizer and the second vaporizer are made of 316L, 316 or 304 stainless steel, and the upper ends of the vaporizers are provided with PFA or PTFE wire mesh. Its purpose is to intercept trace mist droplets in sulfur trioxide gas.

In the above scheme, the top of the absorption tower is equipped with a circulating acid sprayer, and the upper end of the absorption tower is equipped with a liquid collection tray under the two-stage tray, and the liquid collection tray is arrayed with circular holes. Such a structure can eliminate the "wall flow" effect and avoid The lower tray of the absorption tower is damaged by high temperature due to lack of liquid.

In the above scheme, there is an ultrapure water feeding pipeline in the middle of the absorption tower; a finished product extraction pipeline is installed at the second outlet of the cooler; and a high-purity air feeding pipeline is installed at the bottom of the gas tower.

In the above scheme, the absorption tower, cooler, and stripping tower are any one of PFA, PTFE, and HDPE in 316L stainless steel or 304 stainless steel, and the amount of metal ion precipitation is ≤30w/ ^10-12 ; There is packing in the column, and the packing is Pall ring and Raschig ring packing made of PFA.

A kind of electronic grade sulfuric acid production method of the present invention selects above-mentioned electronic grade sulfuric acid production device for use, comprises the following steps:

(1) The sulfur trioxide in the sulfur trioxide raw material storage tank is transported to the vaporizer 1 through the raw material pump, and the sulfur trioxide in the vaporizer 1 is evaporated, and the gas-liquid separator is carried out in the demister to remove the sulfur trioxide of mist impurities The air is condensed into a liquid state in the cooler one and enters the buffer tank one;

(2) The sulfur trioxide in the buffer tank 1 passes through the vaporizer 2 for gas-liquid separation, and then is transported to the absorption tower by the feed pump, and is fed into ultrapure water for absorption. The absorption liquid enters the bottom buffer tank 2, and the sulfur trioxide in the buffer tank 2 The sulfuric acid is transported to the second cooler through the circulating acid pump, and part of the cooled sulfuric acid is returned to the absorption tower for circular absorption, and part of the sulfuric acid is extracted to the stripping tower;

(3) The sulfuric acid entering the stripping tower is aerated with high-purity compressed air, and then enters the sulfuric acid storage tank to obtain SEMI-C12 electronic grade sulfuric acid (metal concentration ≤ 0.1μg/L).

In the above method, the temperature of the sulfur trioxide storage tank and buffer tank 1 is controlled at 32°C to 40°C.

In the above method, the vaporizer is heated by coiled hot water or heat transfer oil. The temperature of vaporizer 1 is controlled at 50°C-70°C, and the temperature of vaporizer 2 is controlled at 40°C-55°C. There is a temperature difference between vaporizer 1 and vaporizer 2. Vaporization at a higher temperature can remove most of the liquid impurities. The temperature of the second vaporizer is lower, and the fog droplets brought in by vaporization are less, which can be intercepted by the non-screen mesh on the second vaporizer to ensure the quality of sulfur trioxide entering the absorption tower.

In the above method, cooler one uses air as the cooling medium, and the discharge temperature of sulfur trioxide is controlled at 32°C to 40°C, which can reduce the safety risk after the failure of the heat exchanger; the discharge temperature of sulfur trioxide is controlled at 32°C to 40°C. ℃, to ensure that sulfur trioxide is liquid.

In the above method, the sulfur trioxide gas strip enters from the bottom of the absorption tower, and the ultrapure water is sprayed from under the first tray of the absorption tower (from top to bottom); the temperature inside the absorption tower is controlled at 70°C to 110°C, and the temperature If the temperature is too high, the equipment will be damaged; the acid temperature of the disulfuric acid discharged from the cooler should be controlled at 40°C to 70°C. If the temperature is too low, the subsequent aeration effect will be affected.

In the above method, the ultrapure water is ultrapure water with a resistivity ≥ 18MΩ*cm at 25°C.

In the above method, sulfuric acid enters from the top of the stripping tower, and high-purity air enters from the lower part of the stripping tower; the aeration rate of the stripping tower is controlled at 450 L/min to 650 L/min, and the concentration of easy oxides in the product is controlled within 2 ppm ;

The operating principle of a device for producing electronic-grade sulfuric acid in the present invention is that the liquid sulfur trioxide in the sulfur trioxide storage tank is transported to the vaporizer one through the sulfur trioxide raw material pump, and is heated and vaporized in the vaporizer one, and the gaseous sulfur trioxide is vaporized in the vaporizer one. The gas-liquid separation is carried out in the demister, the sulfur trioxide gas enters the cooler 1 and is cooled into a liquid state, and the liquid sulfur trioxide flows from the cooler to the buffer tank 1, and the liquid sulfur trioxide in the buffer tank 1 is transported to the vaporizer through the feed pump 2. After re-vaporization, gaseous sulfur trioxide enters the absorption tower to react with ultrapure water to produce sulfuric acid. The sulfuric acid in the absorption tower enters the stripping tower after being cooled by cooler 2, and is aerated with high-purity air in the gas tower to remove sulfur dioxide. Finally into the finished product storage tank.

The innovations of the present invention include as follows:

(1) The upper part of the vaporizer used in the present invention is provided with a PFA screen, which can remove the liquid foam in the vaporized sulfur trioxide to achieve the purpose of removing impurities in the sulfur trioxide;

(2) The present invention adopts two-stage vaporization, vaporizer one vaporizes at a higher temperature, and then removes a large amount of impurities through a demister, vaporizer two vaporizes at a lower temperature, and brings in less mist droplets to be removed through the upper wire mesh of the vaporizer, Guarantee the quality of incoming sulfur trioxide, and get SEMI-C12 electronic grade sulfuric acid after absorption;

(3) The sulfur trioxide cooler of the present invention uses air as the cooling medium, which is safer than condensed water for heat exchange;

(4) There is a liquid accumulation tray under the two-stage tray at the upper end of the absorption tower of the present invention, and a circular hole is arrayed on the accumulation tray. This structure can eliminate the "wall flow" effect and avoid the high temperature of the lower tray of the absorption tower due to lack of liquid. damage;

(5) The equipment pipelines used in the present invention are all made of 316L stainless steel or 304 stainless steel lined with polytetrafluoroethylene plastic, which completely isolates the acidic medium from the stainless steel and prevents product quality from being polluted by micro-corrosion of the equipment.

Description of drawings

Fig. 1 is the device diagram of a kind of electronic grade sulfuric acid production of the present invention.

Figure 2 is a schematic diagram of the structure of the sprinkler.

Among them, 1. Sulfur trioxide raw material storage tank, 2. Raw material pump, 3. Vaporizer 1, 4. Demister, 5. Cooler 1, 6. Buffer tank 1, 7. Feed pump, 8. Vaporizer 2, 9. Absorption tower, 10. Sprinkler, 11. Fluid tray, 12. Buffer tank 2, 13. Circulating acid pump, 14. Cooler 2, 15. Stripping tower, 16. Tray, 17. Hole.

Detailed ways

The present invention will be further described below in conjunction with the examples, but it should not be understood that the scope of the subject of the present invention is limited to the following examples. Without departing from the above-mentioned technical ideas of the present invention, various replacements and changes made according to common technical knowledge and conventional means in this field shall be included in the protection scope of the present invention.

Example 1

A device for producing electronic-grade sulfuric acid, comprising sulfur trioxide raw material storage tank 1, vaporizer one 3, demister 4, cooler one 5, buffer tank one 6, vaporizer two 8, absorption tower 9, buffer tank two 12, Cooler 2 14, stripping tower 15, sulfur trioxide raw material storage tank 1 communicates with vaporizer 1 3 via raw material pump 2, the top of vaporizer 1 3 is connected with demister 4, and the top of demister 4 is connected with the top of cooler 1 5 , the bottom of the cooler one 5 is connected with the buffer tank one 6, the buffer tank one 6 is connected with the vaporizer two 8 through the feed pump 7, the vaporizer two 8 is connected with the absorption tower 9, the bottom of the absorption tower 9 is connected with the buffer tank two 12, and the buffer tank The bottom of the second 12 is connected to the second cooler 14 through the circulating acid pump 13, the second cooler 14 is connected to the stripping tower 15, and the stripping tower 15 is connected to an electronic-grade sulfuric acid storage tank.

Cooler 2 14 is connected with absorption tower 9 and is connected with sprayer 10 in absorption tower 9, and described absorption tower 9 top is provided with at least two-stage tray 16, and tray is provided with liquid accumulation pan 11, and accumulation liquid Holes 17 are arrayed on the disc 11 .

The upper part of the absorption tower 9 is provided with an ultrapure water inlet pipe; the stripping tower 15 is provided with an air inlet pipe.

The invention also discloses a method for producing electronic-grade sulfuric acid: industrial-grade sulfur trioxide is unloaded to a raw material storage tank, and transported to vaporizer 1 by a raw material pump, and the vaporized sulfur trioxide enters a mist eliminator to remove impurities. The sulfur trioxide in the cooler 1 is condensed into a liquid state and enters the buffer tank 1. The sulfur trioxide in the buffer tank 1 is transported to the vaporizer 2 through the feed pump, and enters the absorption tower after being vaporized again. Circular absorption, controlling the concentration of the absorption liquid, and stable production of the secondary product in the cooler, after the subsequent aeration treatment, the quality of the sulfuric acid product reaches the SEMI-C12 level (metal concentration ≤ 0.1μg/L).

The demister is provided with two-stage wire mesh packing, and the material is PP, PE or PTFE wire mesh;

The first vaporizer and the second vaporizer are made of 316L, 316 or 304 stainless steel, and the upper ends of the vaporizers are provided with PFA or PTFE wire mesh.

The top of the absorption tower is provided with a circulating acid sprayer, and the upper end of the absorption tower is provided with a liquid accumulation tray under the two-stage tray, and a circular hole is arrayed on the liquid accumulation tray;

The middle part of the absorption tower is provided with an ultrapure water feeding pipe; the second outlet of the cooler is provided with a product extraction pipe; the bottom of the gas tower is provided with a high-purity air feeding pipe.

The absorption tower, cooler one, cooler two, and stripping tower are any one of PFA, PTFE, and HDPE in 316L stainless steel or 304 stainless steel, and the amount of metal ion precipitation is ≤30w/ ^10-12 ; the absorption tower and gas There is packing in the column, and the packing is Pall ring and Raschig ring packing made of PFA.

The cooler one uses air as the cooling medium, and the discharge temperature of sulfur trioxide is controlled at 32°C to 40°C; the discharge temperature of sulfur trioxide is controlled at 32°C to 40°C;

The sulfur trioxide stripping enters from the bottom of the absorption tower, and the ultrapure water is sprayed from under the first tray of the absorption tower (from top to bottom); the temperature in the absorption tower is controlled at 70°C to 110°C; the cooler The acid temperature of the disulfuric acid output is controlled at 40°C to 70°C;

The ultrapure water is ultrapure water with a resistivity ≥ 18MΩ*cm at 25°C.

The sulfuric acid enters from the top of the stripping tower, and the high-purity air enters from the bottom of the stripping tower; the aeration rate of the stripping tower is controlled at 450 L/min～650 L/min;

A kind of electronic grade sulfuric acid production method of the present embodiment selects above-mentioned electronic grade sulfuric acid production device for use, comprises the following steps:

(1) The sulfur trioxide in the raw material storage tank is transported to the vaporizer 1 through the raw material pump, and the liquid sulfur trioxide is vaporized in the vaporizer through the hot water of the barrel coil or heat transfer oil, and the heating temperature is controlled at 65°C; the sulfur trioxide in the vaporizer After evaporation, it enters the mist eliminator to remove impurities. The sulfur trioxide after removal enters cooler 1, condenses into a liquid state in cooler 1, and enters buffer tank 1. The cooling medium is cooling water or air, and the discharge temperature of sulfur trioxide is Control at 38°C, the temperature of buffer tank 1 is controlled at 38°C;

(2) The sulfur trioxide in the buffer tank 1 is transported to the absorption tower through the feed pump, and passed into the ultrapure water for absorption, the absorption liquid enters the bottom buffer tank 2, and the sulfuric acid in the buffer tank 2 is transported to the cooling tower through the circulating acid pump. In the second device, part of the sulfuric acid after cooling is returned to the absorption tower for circular absorption, and part of the sulfuric acid is extracted to the stripping tower; the temperature inside the absorption tower is controlled at 95°C; the acid temperature of the disulfuric acid discharged from the cooler is controlled at 65°C;

(3) The sulfuric acid entering the stripping tower is aerated with high-purity compressed air. The volume of high-purity air is controlled at 560L/min, and the aerated product enters the finished product storage tank.

After testing, the metal ions in electronic grade sulfuric acid are <80ppt, the anion concentration is <100ppb, the easy oxide concentration is <2ppm, and the sulfuric acid concentration is 96%-97%.

Example 2

With reference to Fig. 1,2, the implementation steps of embodiment 2 are as follows:

(1) The sulfur trioxide in the raw material storage tank is transported to the vaporizer 1 through the raw material pump, and the liquid sulfur trioxide is vaporized in the vaporizer through the hot water of the barrel coil, and the heating temperature is controlled at 60°C; the sulfur trioxide in the vaporizer evaporates and enters The mist eliminator removes impurities, and the sulfur trioxide after removal enters cooler 1, condenses into a liquid state in cooler 1, and enters buffer tank 1. The cooling medium is cooling water or air, and the sulfur trioxide output temperature is controlled at 38 ℃, the buffer tank temperature is controlled at 36 ℃;

(2) The sulfur trioxide in the buffer tank 1 is transported to the absorption tower through the feed pump, and passed into the ultrapure water for absorption, the absorption liquid enters the bottom buffer tank 2, and the sulfuric acid in the buffer tank 2 is transported to the cooling tower through the circulating acid pump. In the second device, part of the sulfuric acid after cooling is returned to the absorption tower for circular absorption, and part of the sulfuric acid is extracted to the stripping tower; the temperature in the absorption tower is controlled at 90°C; the acid temperature of the disulfuric acid discharged from the cooler is controlled at 60°C;

(3) The sulfuric acid entering the stripping tower is aerated with high-purity compressed air. The volume of high-purity air is controlled at 520L/min, and the aerated product enters the finished product storage tank.

After testing, the metal ion in electronic grade sulfuric acid is <70ppt, the concentration of anion is <100ppb, the concentration of easy oxide is <2ppm, and the concentration of sulfuric acid is 96%~97%.

Example 3

With reference to Fig. 1,2, the implementation steps of embodiment 3 are as follows:

(1) The sulfur trioxide in the raw material storage tank is transported to the vaporizer 1 through the raw material pump, and the liquid sulfur trioxide is vaporized in the vaporizer through the hot water of the barrel coil, and the heating temperature is controlled at 55°C; the sulfur trioxide in the vaporizer evaporates and enters The mist eliminator removes impurities, and the sulfur trioxide after removal enters cooler 1, condenses into a liquid state in cooler 1, and enters buffer tank 1. The cooling medium is cooling water or air, and the sulfur trioxide discharge temperature is controlled at 38 ℃, the buffer tank temperature is controlled at 36 ℃;

(2) The sulfur trioxide in the buffer tank 1 is transported to the absorption tower, and passed into the ultrapure water for absorption, the absorption liquid enters the bottom buffer tank 2, and the sulfuric acid in the buffer tank 2 is transported to the cooler 2 through the circulating acid pump, and cooled The final part of the sulfuric acid is returned to the absorption tower for circular absorption, and part of the sulfuric acid is extracted to the stripping tower; the temperature inside the absorption tower is controlled at 85°C; the acid temperature of the disulfuric acid discharged from the cooler is controlled at 55°C;

(3) The sulfuric acid entering the stripping tower is aerated with high-purity compressed air. The volume of high-purity air is controlled at 480L/min, and the aerated product enters the finished product storage tank.

After testing, the metal ions in electronic grade sulfuric acid are <60ppt, the anion concentration is <100ppb, the easy oxide concentration is <2ppm, and the sulfuric acid concentration is 96%-97%.

Claims (8)

1. A device for electronic-grade sulfuric acid production, characterized in that it comprises a sulfur trioxide raw material storage tank (1), vaporizer one (3), demister (4), cooler one (5), buffer tank one ( 6), vaporizer two (8), absorption tower (9), buffer tank two (12), cooler two (14), stripping tower (15), sulfur trioxide raw material storage tank (1) through the raw material pump (2 ) is connected with vaporizer one (3), the top of vaporizer one (3) is connected with mist eliminator (4), the top of mist eliminator (4) is connected with the top of cooler one (5), and the bottom of cooler one (5) is connected with buffer Tank 1 (6) is connected, buffer tank 1 (6) is connected to vaporizer 2 (8) via feed pump (7), vaporizer 2 (8) is connected to absorption tower (9), and the bottom of absorption tower (9) is connected to buffer tank Two (12) are connected, the bottom of the buffer tank two (12) is connected to the cooler two (14) through the circulating acid pump (13), the cooler two (14) is connected to the stripping tower (15), and the stripping tower (15) Connects to electronic grade sulfuric acid storage tank. 2. The device for producing electronic-grade sulfuric acid according to claim 1, characterized in that the second cooler (14) is connected to the absorption tower (9) and connected to the sprayer (10) in the absorption tower (9), The upper part of the absorption tower (9) is provided with at least two stages of trays (16), and a liquid collection tray (11) is provided under the trays, and holes (17) are arranged on the liquid collection tray (11). 3. The device for producing electronic-grade sulfuric acid according to claim 1, characterized in that, the upper part of the absorption tower (9) is provided with an ultrapure water inlet pipe; the stripping tower (15) is provided with an air into the tube. 4. A method for producing electronic grade sulfuric acid, adopting the device for producing electronic grade sulfuric acid as claimed in any one of claims 1 to 3, comprising the following steps: (1) The sulfur trioxide in the sulfur trioxide raw material storage tank is transported to the vaporizer 1 through the raw material pump, and the sulfur trioxide in the vaporizer 1 evaporates and enters the demister, then goes through the gas-liquid separator, and the gaseous sulfur trioxide enters the cooler 1 Condensate into a liquid state and enter the buffer tank 1; (2) The sulfur trioxide in the buffer tank 1 passes through the vaporizer 2 for gas-liquid separation, and then is transported to the absorption tower by the feed pump, and is fed into ultrapure water for absorption. The absorption liquid enters the bottom buffer tank 2, and the sulfur trioxide in the buffer tank 2 The sulfuric acid is transported to the second cooler through the circulating acid pump, and part of the cooled sulfuric acid is returned to the absorption tower for circular absorption, and part of the sulfuric acid is extracted to the stripping tower; (3) The sulfuric acid entering the stripping tower is aerated with high-purity compressed air, and then enters the sulfuric acid storage tank to obtain SEMI-C12 electronic grade sulfuric acid. 5. the method for electronic grade sulfuric acid production as claimed in claim 4 is characterized in that, in the step (1), the temperature of sulfur trioxide raw material storage tank, buffer tank one is controlled at 32 ℃～40 ℃; Vaporizer adopts coil hot water Or heating with heat-conducting oil, the temperature of vaporizer 1 is controlled at 50°C-70°C, and the temperature of vaporizer 2 is controlled at 40°C-55°C. There is a temperature difference between vaporizer 1 and 2. The purpose is to vaporize at a higher temperature in vaporizer 1, which can remove most of the fog. The second vaporizer has a lower temperature and less mist droplets brought into the vaporization to ensure the quality of sulfur trioxide entering the absorption tower; cooler one uses cooling water or air as the cooling medium, and the sulfur trioxide output temperature is controlled at 32°C ~40°C. 6. the method for electronic-grade sulfuric acid production as claimed in claim 4, is characterized in that, step (2) sulfur trioxide gas enters from the absorption tower bottom, and ultrapure water is sprayed into from the first piece tray of absorption tower top; The temperature in the absorption tower is controlled at 70°C to 110°C; the acid temperature of the disulfuric acid discharged from the cooler is controlled at 40°C to 70°C. 7. The method for producing electronic-grade sulfuric acid as claimed in claim 4, wherein the ultrapure water is ultrapure water with a resistivity of ≥18MΩ*cm at 25°C. 8. the method for electronic-grade sulfuric acid production as claimed in claim 4, is characterized in that, step (3) sulfuric acid enters from stripper top, and high-purity air enters from stripper bottom; Stripper aeration rate is controlled at 450 L/min～650L/min.