A cooling system and method for producing liquid sulfur dioxide

Abstract

The present invention discloses a cooling system and method for liquid sulfur dioxide production, including the following equipment: an analytical tower, a sulfur dioxide cooler, a buffer tank, a sulfur dioxide drying tower, a drying circulation tank, a screw compressor, a gas-liquid separation tank, an evaporative condenser, and a sulfur dioxide storage tank. The wet sulfur dioxide gas at the outlet of the analytical tower is mixed with liquid sulfur dioxide and cooled through a sulfur dioxide cooler to separate most of the water in the wet sulfur dioxide. The cooled sulfur dioxide gas enters a buffer tank for buffering and then enters a drying tower. After drying, it enters a screw compressor. The sulfur dioxide gas enters an evaporative condenser after being pressurized and liquefied into a sulfur dioxide storage tank. The present invention utilizes the heat absorption principle of sulfur dioxide vaporization and uses sulfur dioxide as a refrigerant to replace circulating water, thereby greatly reducing the safety risks caused by cooler leakage.

Description

Technical Field

[0001] The invention relates to the technical field of sulfur dioxide production, in particular to a new cooling device and method in the sulfur dioxide production process. Background Art

[0002] Sulfur dioxide is a common inorganic compound and is widely used in industrial production processes. Currently, the demand in the market is increasing. The main methods for producing sulfur dioxide include oxidation method, freezing method and sodium citrate absorption method. The sodium citrate absorption method has the advantages of large operational flexibility and low cost, and is well received at home and abroad. However, there are problems such as the strong corrosiveness of wet sulfur dioxide gas, the large amount of dry waste acid, and the high frequency of equipment maintenance.

[0003] In the production process of industrialized sodium citrate absorption method for sulfur dioxide, reducing the leakage rate of equipment has a great impact on the safe and stable operation of the device, and reducing the amount of dry waste acid produced has a great impact on the production cost. At present, the main way to remove water from wet sulfur dioxide gas in China is to use a tubular heat exchanger to exchange heat between wet sulfur dioxide gas and cooling medium. This method does not fundamentally solve the problems caused by the strong corrosion of wet sulfur dioxide gas, such as high frequency of equipment maintenance, high risk of leakage, and cooling and water removal effect affected by cooling medium, which brings inconvenience to production and causes system fluctuations.

[0004] This device utilizes the principle of sulfur dioxide's easy vaporization and heat absorption, and uses the existing product sulfur dioxide as a refrigerant to mix with wet sulfur dioxide gas, eliminating the safety risks caused by the contact between the two media due to leakage. At the same time, it can independently adjust the cooling effect and has high heat exchange efficiency, low production of dry waste acid, no need for other cooling media to participate in heat exchange, and strong stability. Summary of the invention

[0005] The purpose of the present invention is to reduce the safety risk caused by cooler leakage, improve the heat exchange effect, and reduce the dry waste acid produced by the drying tower. It is a more economical and safe process method and provides a cooling system and method for liquid sulfur dioxide production.

[0006] A cooling system for liquid sulfur dioxide production, comprising the following equipment: a desorption tower, a sulfur dioxide cooler, a buffer tank, a sulfur dioxide drying tower, a gas-liquid separation tank, a drying circulation tank, a screw compressor, an evaporative condenser and a sulfur dioxide storage tank;

[0007] One side of the sulfur dioxide cooler is connected with a sulfur dioxide storage tank branch pipe introduced from the sulfur dioxide storage tank. Sulfur dioxide is introduced into the sulfur dioxide cooler through a solenoid valve for atomization, and is mixed with wet sulfur dioxide gas at the outlet of the analysis tower in the sulfur dioxide cooler. The atomized liquid sulfur dioxide absorbs heat and cools down during the vaporization process. After cooling down, water molecules in the mixed gas are liquefied, and the liquefied water returns to the inlet of the rich liquid pump through a reflux pipe and returns to the system for reuse. The sulfur dioxide mixed gas enters the buffer tank for buffering and then enters the drying tower. After being dried in the drying tower, it enters the screw compressor. The dry sulfur dioxide gas enters the evaporative condenser after being pressurized and liquefied and enters the sulfur dioxide storage tank.

[0008] Preferably, the upper side wall of the drying tower is connected to a gas-liquid separation tank via a pipeline, the bottom of the gas-liquid separation tank is connected to a drying circulation tank, and the drying circulation tank is connected to the bottom of the drying tower.

[0009] The present invention utilizes the heat absorption principle of sulfur dioxide vaporization and uses sulfur dioxide as a refrigerant to replace circulating water, greatly reducing the safety risk caused by cooler leakage. The sulfur dioxide gas at the outlet of the sulfur dioxide cooler has a lower temperature and less water content, which greatly reduces the dry waste acid generated by the sulfur dioxide drying tower, and is a more economical and safe cooling method.

[0010] Preferably, the system further includes a pressure gauge, a thermometer, a solenoid valve, a liquid level gauge and a medium pipeline.

[0011] The sulfur dioxide cooler changes the traditional heat exchange mode from indirect heat exchange through heat exchange tubes to mixed cooling. The product sulfur dioxide is used as the cooling medium, and no other cooling medium needs to be introduced. The mixture is directly mixed and contacted in the sulfur dioxide heat exchanger to cool down, eliminating the risk of leakage and contact between two different media.

[0012] Preferably, the sulfur dioxide cooler has a lower temperature of the sulfur dioxide gas after mixing, a better cooling effect, and a better water removal efficiency.

[0013] A cooling method for liquid sulfur dioxide production, comprising the following steps:

[0014] Step S1: The temperature of the sulfur dioxide gas at the outlet of the analysis tower is controlled at 85-90°C and enters the sulfur dioxide cooler;

[0015] Step S2: Turn on the screw compressor and control the pressure at the top of the analytical tower to 0-10KPa through the compressor inverter control;

[0016] Step S3: A sulfur dioxide storage tank branch pipe is introduced from the sulfur dioxide storage tank, and mist sulfur dioxide is sprayed into the sulfur dioxide cooler through the solenoid valve adjustment, mixed with the sulfur dioxide gas at the outlet of the analysis tower and cooled to 5-10°C. After cooling, the water molecules in the mixed gas are liquefied and returned to the rich liquid pump of the sulfur dioxide absorption tower through the reflux pipe. After the gas is buffered in the buffer tank, it enters the sulfur dioxide drying tower for further drying. The dried sulfur dioxide gas enters the screw compressor and enters the evaporative condenser after pressurization to obtain finished sulfur dioxide and enter the sulfur dioxide storage tank.

[0017] By increasing the amount of liquid sulfur dioxide injected and utilizing the heat absorption principle of sulfur dioxide vaporization, the outlet gas temperature of the sulfur dioxide cooler can be lowered, thereby reducing the water content in the outlet gas and reducing the amount of waste acid generated in the subsequent drying tower.

[0018] The liquid sulfur dioxide injection rate increased from 0 to 236.8KG / H, the outlet gas temperature of the sulfur dioxide cooler changed from 40℃ to 0℃, the water content in the outlet gas decreased from 176KG / H to 16.7KG / H, and the waste acid production in the drying tower decreased from 580.8KG / H to 53.7KG / H.

[0019] The gas parameters at the outlet of the secondary cooler are shown in Table 1:

[0020] Table 1

[0021] Temperature C° Water volume KG / H Waste acid volume KG / H SO2 vaporization amount KG / H 40 176 580.8 0 20 59.8 190.3 118.2 10 32.4 104.4 177.3 5 23.4 78.2 206.5 0 16.7 53.7 236.8

[0022] The industrial production of sulfur dioxide by sodium citrate absorption method belongs to continuous production. The stability of the cooler has a great influence on the stability of the system. If the sulfur dioxide cooler leaks frequently, it will affect the safe and stable operation of the device and may even cause process accidents. The present invention uses sulfur dioxide as the cooling medium, directly mixes the same medium, and eliminates the heat exchange tube. While improving the heat exchange effect, it fundamentally solves the safety risks brought by the contact between the two media after leakage. It can also reduce the dependence on the cooling system of public auxiliary facilities and ensure the stability of production.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Wet sulfur dioxide gas is highly corrosive, and has high requirements on the material of sulfur dioxide cooler. In addition, there is a safety risk caused by the contact of two different media after the acid cooler leaks. In the present invention, the same medium is used as the cooling medium, and directly mixed and heat exchanged, eliminating the possibility of safety risks caused by leakage.

[0025] 2. In the present invention, sulfur dioxide is used as a coolant. The boiling point of sulfur dioxide is -10°C, which is lower than the temperature of conventional circulating water. The cooling effect is better, the moisture entering the drying tower is lower, and the amount of drying acid used in the drying tower can be greatly reduced, thereby achieving the purpose of saving production costs.

[0026] 3. The present invention utilizes the product of the device as a cooling medium, thereby reducing dependence on the cooling system of public auxiliary facilities and ensuring the stability of production.

[0027] 4. The temperature of sulfur dioxide at the outlet of the sulfur dioxide cooler of the present invention can be reduced to 5-10°C. After entering the drying tower, the drying tower circulation system can eliminate the drying acid cooling facility, thereby eliminating production fluctuations caused by leakage of the acid cooler of the drying system and ensuring stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the system structure of the present invention.

[0030] In the figure: analytical tower 1, sulfur dioxide cooler 2, sulfur dioxide storage tank branch pipe 201, reflux pipe 202, buffer tank 3, sulfur dioxide drying tower 4, gas-liquid separation tank 5, drying circulation tank 6, screw compressor 7, evaporative condenser 8, sulfur dioxide storage tank 9. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 described embodiments 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] Reference Figure 1 , a cooling system for liquid sulfur dioxide production, using the following equipment: an analytical tower 1, a sulfur dioxide cooler 2, a buffer tank 3, a sulfur dioxide drying tower 4, a gas-liquid separation tank 5, a drying circulation tank 6, a screw compressor 7, an evaporative condenser 8 and a sulfur dioxide storage tank 9;

[0034] One side of the sulfur dioxide cooler 2 is connected with a sulfur dioxide storage tank branch pipe 201 introduced from the sulfur dioxide storage tank 9. Sulfur dioxide is introduced into the sulfur dioxide cooler 2 through a solenoid valve for atomization, and is mixed with the wet sulfur dioxide gas at the outlet of the analysis tower 1 in the sulfur dioxide cooler 2. The atomized liquid sulfur dioxide absorbs heat and cools down during the vaporization process. After cooling down, the water molecules in the mixed gas are liquefied, and the liquefied water returns to the inlet of the rich liquid pump through the reflux pipe 202 and returns to the system for reuse. The sulfur dioxide mixed gas enters the buffer tank 3 for buffering and then enters the drying tower 3. After drying in the drying tower 3, it enters the screw compressor 7. The dry sulfur dioxide gas enters the evaporative condenser 8 after being pressurized and liquefied and enters the sulfur dioxide storage tank 9.

[0035] The upper side wall of the drying tower 3 is connected to a gas-liquid separation tank 5 through a pipeline, the bottom of the gas-liquid separation tank 5 is connected to a drying circulation tank 6, and the drying circulation tank 6 is connected to the bottom of the drying tower 3.

[0036] The present invention utilizes the heat absorption principle of sulfur dioxide vaporization and uses sulfur dioxide as a refrigerant to replace circulating water, greatly reducing the safety risk caused by cooler leakage. The sulfur dioxide gas at the outlet of the sulfur dioxide cooler has a lower temperature and less water content, which greatly reduces the dry waste acid generated by the sulfur dioxide drying tower, and is a more economical and safe cooling method.

[0037] Example 2

[0038] A cooling method for liquid sulfur dioxide production, comprising the following steps:

[0039] Step S1: The temperature of the sulfur dioxide gas at the outlet of the desorption tower is controlled at 85°C and enters the sulfur dioxide cooler;

[0040] Step S2: Turn on the screw compressor and control the pressure at the top of the analytical tower to 1 KPa through the compressor inverter control;

[0041] Step S3: Introduce a liquid sulfur dioxide from the sulfur dioxide storage tank, adjust it through the solenoid valve, spray mist sulfur dioxide into the sulfur dioxide cooler, mix it with the sulfur dioxide gas at the outlet of the analysis tower and cool it to 5°C. After cooling, the water molecules in the mixed gas are liquefied and returned to the rich liquid pump of the sulfur dioxide absorption tower. After the gas is buffered in the buffer tank, it enters the sulfur dioxide drying tower for further drying. The dried sulfur dioxide gas enters the screw compressor and enters the evaporative condenser for liquefaction after being pressurized to obtain the finished sulfur dioxide and enter the sulfur dioxide storage tank.

[0042] By increasing the injection amount of liquid sulfur dioxide and utilizing the heat absorption principle of sulfur dioxide vaporization, the outlet gas temperature of sulfur dioxide cooler 2 is lowered, thereby reducing the water content in the outlet gas and reducing the amount of waste acid generated in the subsequent drying tower.

[0043] When the injection rate of liquid sulfur dioxide is 0KG / H, the outlet gas temperature of sulfur dioxide cooler 2 is 40°C, the water content in the outlet gas is 176KG / H, and the amount of waste acid generated in the drying tower is 580.8KG / H.

[0044] Example 3

[0045] A cooling method for liquid sulfur dioxide production, comprising the following steps:

[0046] Step S1: The temperature of the sulfur dioxide gas at the outlet of the analysis tower is controlled at 88°C and enters the sulfur dioxide cooler;

[0047] Step S2: Turn on the screw compressor and control the pressure at the top of the analytical tower to 3 KPa through the compressor inverter control;

[0048] Step S3: Introduce a liquid sulfur dioxide from the sulfur dioxide storage tank, adjust it through the solenoid valve, spray mist sulfur dioxide into the sulfur dioxide cooler, mix it with the sulfur dioxide gas at the outlet of the analysis tower and cool it to 8°C. After cooling, the water molecules in the mixed gas are liquefied and returned to the rich liquid pump of the sulfur dioxide absorption tower. After the gas is buffered in the buffer tank, it enters the sulfur dioxide drying tower for further drying. The dried sulfur dioxide gas enters the screw compressor and enters the evaporative condenser for liquefaction after being pressurized to obtain the finished sulfur dioxide and enter the sulfur dioxide storage tank.

[0049] By increasing the injection amount of liquid sulfur dioxide and utilizing the heat absorption principle of sulfur dioxide vaporization, the outlet gas temperature of sulfur dioxide cooler 2 is lowered, thereby reducing the water content in the outlet gas and reducing the amount of waste acid generated in the subsequent drying tower.

[0050] When the injection rate of liquid sulfur dioxide is 118.2KG / H, the outlet gas temperature of sulfur dioxide cooler 2 is 20°C, the water content in the outlet gas is 59.8KG / H, and the amount of waste acid generated in the drying tower is 190.3KG / H.

[0051] Example 4

[0052] A cooling method for liquid sulfur dioxide production, comprising the following steps:

[0053] Step S1: The temperature of the sulfur dioxide gas at the outlet of the analysis tower is controlled at 90°C and enters the sulfur dioxide cooler;

[0054] Step S2: Turn on the screw compressor and control the pressure at the top of the analytical tower to 5 KPa through the compressor inverter control;

[0055] Step S3: Introduce a liquid sulfur dioxide from the sulfur dioxide storage tank, adjust it through the solenoid valve, spray mist sulfur dioxide into the sulfur dioxide cooler, mix it with the sulfur dioxide gas at the outlet of the analysis tower and cool it to 5°C. After cooling, the water molecules in the mixed gas are liquefied and returned to the rich liquid pump of the sulfur dioxide absorption tower. After the gas is buffered in the buffer tank, it enters the sulfur dioxide drying tower for further drying. The dried sulfur dioxide gas enters the screw compressor and enters the evaporative condenser for liquefaction after being pressurized to obtain the finished sulfur dioxide and enter the sulfur dioxide storage tank.

[0056] By increasing the injection amount of liquid sulfur dioxide and utilizing the heat absorption principle of sulfur dioxide vaporization, the outlet gas temperature of sulfur dioxide cooler 2 is lowered, thereby reducing the water content in the outlet gas and reducing the amount of waste acid generated in the subsequent drying tower.

[0057] When the injection rate of liquid sulfur dioxide is 177.3KG / H, the outlet gas temperature of sulfur dioxide cooler 2 is 10°C, the water content in the outlet gas is 32.4KG / H, and the amount of waste acid generated in the drying tower is 104.4KG / H.

[0058] Example 5

[0059] A cooling method for liquid sulfur dioxide production, comprising the following steps:

[0060] Step S1: The temperature of the sulfur dioxide gas at the outlet of the analysis tower is controlled at 90°C and enters the sulfur dioxide cooler;

[0061] Step S2: Turn on the screw compressor and control the pressure at the top of the analytical tower to 8KPa through the compressor inverter control;

[0062] Step S3: Introduce a liquid sulfur dioxide from the sulfur dioxide storage tank, adjust it through the solenoid valve, spray mist sulfur dioxide into the sulfur dioxide cooler, mix it with the sulfur dioxide gas at the outlet of the analysis tower and cool it to 8°C. After cooling, the water molecules in the mixed gas are liquefied and returned to the rich liquid pump of the sulfur dioxide absorption tower. After the gas is buffered in the buffer tank, it enters the sulfur dioxide drying tower for further drying. The dried sulfur dioxide gas enters the screw compressor and enters the evaporative condenser for liquefaction after being pressurized to obtain the finished sulfur dioxide and enter the sulfur dioxide storage tank.

[0063] By increasing the injection amount of liquid sulfur dioxide and utilizing the heat absorption principle of sulfur dioxide vaporization, the outlet gas temperature of sulfur dioxide cooler 2 is lowered, thereby reducing the water content in the outlet gas and reducing the amount of waste acid generated in the subsequent drying tower.

[0064] When the injection rate of liquid sulfur dioxide is 206.5KG / H, the outlet gas temperature of sulfur dioxide cooler 2 is 5°C, the water content in the outlet gas is 23.4KG / H, and the amount of waste acid generated in the drying tower is 78.2KG / H.

[0065] Example 6

[0066] A cooling method for liquid sulfur dioxide production, comprising the following steps:

[0067] Step S1: The temperature of the sulfur dioxide gas at the outlet of the analysis tower is controlled at 90°C and enters the sulfur dioxide cooler;

[0068] Step S2: Turn on the screw compressor and control the pressure at the top of the analytical tower to 10 KPa through the compressor inverter control;

[0069] Step S3: Introduce a stream of liquid sulfur dioxide from the sulfur dioxide storage tank, adjust the solenoid valve, spray mist sulfur dioxide into the sulfur dioxide cooler, mix with the sulfur dioxide gas at the outlet of the analysis tower and cool to 10°C. After cooling, the water molecules in the mixed gas are liquefied and returned to the rich liquid pump of the sulfur dioxide absorption tower. After the gas is buffered in the buffer tank, it enters the sulfur dioxide drying tower for further drying. The dried sulfur dioxide gas enters the screw compressor and enters the evaporative condenser for liquefaction after being pressurized to obtain the finished sulfur dioxide and enter the sulfur dioxide storage tank.

[0070] By increasing the injection amount of liquid sulfur dioxide and utilizing the heat absorption principle of sulfur dioxide vaporization, the outlet gas temperature of sulfur dioxide cooler 2 is lowered, thereby reducing the water content in the outlet gas and reducing the amount of waste acid generated in the subsequent drying tower.

[0071] When the injection rate of liquid sulfur dioxide is 236.8KG / H, the outlet gas temperature of sulfur dioxide cooler 2 is 0°C, the water content in the outlet gas is 16.7KG / H, and the amount of waste acid generated in the drying tower is 53.7KG / H.

[0072] The present invention adopts sulfur dioxide as the cooling medium, directly mixes the same medium, and eliminates the heat exchange tube, thereby improving the heat exchange effect and fundamentally solving the safety risks brought about by the contact of the two mediums after leakage, while reducing the dependence on the cooling system of public auxiliary facilities and ensuring the stability of production.

[0073] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A cooling system for liquid sulfur dioxide production, characterized in that: The device comprises the following equipment: a desorption tower (1), a sulfur dioxide cooler (2), a buffer tank (3), a sulfur dioxide drying tower (4), a gas-liquid separation tank (5), a drying circulation tank (6), a screw compressor (7), an evaporative condenser (8) and a sulfur dioxide storage tank (9); One side of the sulfur dioxide cooler (2) is connected to a sulfur dioxide storage tank branch pipe (201) introduced from the sulfur dioxide storage tank (9). The sulfur dioxide is introduced into the sulfur dioxide cooler (2) through a solenoid valve for atomization and mixed with the wet sulfur dioxide gas at the outlet of the analysis tower (1) in the sulfur dioxide cooler (2). The atomized liquid sulfur dioxide absorbs heat and cools down during the vaporization process. After cooling down, the water molecules in the mixed gas are liquefied. The liquefied water returns to the inlet of the rich liquid pump through the reflux pipe (202) and is reused in the system. The sulfur dioxide mixed gas enters the buffer tank (3) for buffering and then enters the drying tower (3). After drying in the drying tower (3), it enters the screw compressor (7). The dry sulfur dioxide gas enters the evaporative condenser (8) after being pressurized and liquefied and enters the sulfur dioxide storage tank (9).

2. A cooling system for liquid sulfur dioxide production according to claim 1, characterized in that: The upper side wall of the drying tower (3) is connected to a gas-liquid separation tank (5) via a pipeline, the bottom of the gas-liquid separation tank (5) is connected to a drying circulation tank (6), and the drying circulation tank (6) is connected to the bottom of the drying tower (3).

3. The cooling system for liquid sulfur dioxide production according to claim 1, characterized in that: The sulfur dioxide cooler (2) changes the traditional heat exchange mode from indirect heat exchange through heat exchange tubes to mixed cooling.

4. The cooling system for liquid sulfur dioxide production according to claim 1, characterized in that: The system also includes a pressure gauge, a thermometer, a solenoid valve, a liquid level gauge and a medium pipeline.

5. A method for cooling liquid sulfur dioxide during production, using a cooling system for liquid sulfur dioxide during production as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: Step S1: The sulfur dioxide gas at the outlet of the desorption tower (1) is controlled at a temperature of 85-90° C. and enters the sulfur dioxide cooler (2); Step S2: Turn on the screw compressor (7) and control the pressure at the top of the analytical tower (1) to be between 0 and 10 KPa by means of the compressor inverter; Step S3: A sulfur dioxide storage tank branch pipe (201) is introduced from the sulfur dioxide storage tank (9), and mist sulfur dioxide is sprayed into the sulfur dioxide cooler (2) through the adjustment of the electromagnetic valve, and mixed with the sulfur dioxide gas at the outlet of the analysis tower (1) and cooled to 5-10° C. After cooling, the water molecules in the mixed gas are liquefied and returned to the rich liquid pump of the sulfur dioxide absorption tower through the reflux pipe (202). After the gas is buffered in the buffer tank (3), it enters the sulfur dioxide drying tower (4) for further drying. The dried sulfur dioxide gas enters the screw compressor (7), and after being pressurized, enters the evaporative condenser (8) for liquefaction to obtain finished sulfur dioxide and enter the sulfur dioxide storage tank (9).

6. The cooling method for liquid sulfur dioxide production according to claim 5, characterized in that: By increasing the amount of liquid sulfur dioxide injected, the outlet gas temperature of the sulfur dioxide cooler (2) is reduced by utilizing the heat absorption principle of sulfur dioxide vaporization, thereby reducing the water content in the outlet gas and reducing the amount of waste acid generated in the subsequent drying tower.

7. A cooling method for liquid sulfur dioxide production according to claim 6, characterized in that: The liquid sulfur dioxide injection rate was increased from 0 to 236.8 KG / H, the outlet gas temperature of the sulfur dioxide cooler (2) was changed from 40°C to 0°C, the water content in the outlet gas was reduced from 176 KG / H to 16.7 KG / H, and the amount of waste acid generated in the drying tower was reduced from 580.8 KG / H to 53.7 KG / H.

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