An automatic control system and method for the coolant temperature of a hydroquinone product rectification column

Abstract

The application discloses a kind of catechol product rectifying column refrigerant temperature automatic control system and method, including refrigerant tank, circulating pump, overhead condenser, air cooler, rectifying column, refrigerant tank is connected with circulating pump by pipeline, circulating pump is connected with overhead condenser by pipeline, overhead condenser is connected with air cooler and rectifying column by pipeline respectively, air cooler is connected with refrigerant tank by refrigerant temperature control system, the bottom of refrigerant tank is connected with refrigerant tank automatic blowdown system, the top of refrigerant tank is connected with vent line, the refrigerant system closed cycle of the present application is not consumed water resources, realizes refrigerant temperature accurate, automatic control, not influenced by environment climate, does not need manual intervention, overcome the traditional circulating water as refrigerant condenser temperature difference too large, condensate temperature is not easy to control, even condenser supercooling pipe blockage, circulating water hardness high condenser shell is easy to scale and block, unstable operation and is greatly influenced by environmental temperature and other problems.

Description

Technical Field

[0001] This invention relates to the field of pesticide production technology, specifically to an automatic control system and method for the refrigerant temperature of a distillation column for hydroquinone products. Background Technology

[0002] Hydroquinone is an important organic raw material, mainly used in developing agents, rubber antioxidants, rubber adhesives, plastics, synthetic resins, synthetic fibers, preservatives, stabilizers, and antioxidants. It can also be used as a reagent and disinfectant.

[0003] The main methods for synthesizing hydroquinone are as follows:

[0004] 1: Catechol:

[0005] 1.1: o-Dichlorobenzene Method: This method involves placing o-dichlorobenzene in a high-pressure reactor, using copper oxide, barium chloride, and sodium acetate as catalysts, and performing alkaline fusion with sodium hydroxide. The reaction product is then acidified, filtered, and the organic matter is extracted with butyl acetate. After separation, catechol and a small amount of resorcinol are obtained. The butyl acetate can be recycled after separation. This method has a long process flow, severe equipment corrosion, many by-products, low yield, large amount of waste, and high production costs, and has now been phased out.

[0006] 1.2: o-Chlorophenol Alkaline Dissolution Method: This method involves placing o-chlorophenol in an autoclave, using copper sulfate and sodium bisulfate as catalysts, and performing alkaline fusion with sodium hydroxide. After neutralization and filtration, the reaction product is extracted with butyl acetate. The filter residue and wastewater are treated separately. The organic extract is sent to a continuous distillation column to recover butyl acetate and recycle it. The bottom liquid is redistilled to obtain catechol and o-chlorophenol, with the o-chlorophenol being recycled. This method is a traditional production method for catechol, with advantages such as lower production costs and higher yield than the o-dichlorobenzene method. However, it has disadvantages such as a long process flow, severe equipment corrosion, high toxicity of raw materials and intermediate products, large amounts of wastewater and waste residue, and poor product quality. It has been phased out abroad, but most manufacturers in my country currently use this method for production.

[0007] 2: Hydroquinone:

[0008] 2.1: Aniline Oxidation Method: This method has advantages such as mature technology, easy reaction control, high yield, and high product purity. However, due to high raw material consumption, the production process generates a large amount of manganese sulfate, ammonium sulfate waste liquid, and iron sludge, causing serious environmental pollution. Furthermore, due to the corrosion of the reaction solution by dilute sulfuric acid, equipment costs are high, and the recovery rate of manganese resources is low. This method has been basically phased out abroad.

[0009] 2.2: p-Diisopropylbenzene Peroxidation Method: The p-diisopropylbenzene peroxidation method first synthesizes p-diisopropylbenzene by alkylating benzene with propylene in the presence of an acidic catalyst (diatomaceous earth phosphate or AlCl3). The para- and meta-isomers are then separated and transposed to p-isopropylbenzene. The separated p-diisopropylbenzene reacts with pure oxygen to form diisopropyl peroxide, which is then decomposed into hydroquinone and acetone in the presence of an acidic catalyst (such as sulfuric acid). The products are neutralized, extracted, separated, and purified to obtain the final product. The hydroquinone yield is approximately 80% based on p-diisopropylbenzene. Compared to the aniline method, this method has advantages such as lower overall cost (approximately 30% lower) and less pollution. However, due to the large number and complex composition of byproducts, product separation is relatively difficult.

[0010] 2.3: Bisphenol A Method: Phenol and acetone react with concentrated hydrochloric acid to produce bisphenol A. Bisphenol A then undergoes catalytic decomposition to isopropylphenol and phenol. Isopropylphenol is oxidized to hydroquinone and acetone. The phenol and acetone produced in the reaction are recycled back to produce bisphenol A. This process route produces no waste, no byproducts, and has a high yield, thus offering good economic benefits.

[0011] 2.4: Phenol Hydroxylation Method: This method uses phenol and hydrogen peroxide as raw materials, and phosphates, potassium oxide, etc. as catalysts, to directly induce hydroxylation reactions at the ortho and para positions on phenol, producing catechol, hydroquinone, and resorcinol. These products are then purified by distillation. This method uses inexpensive and readily available raw materials, has a short process, simple technology, produces less waste, has low cost, mild operating conditions, high product yield, and advanced technology, making it suitable for large-scale industrial continuous production. However, it is technically demanding, uses high concentrations of hydrogen peroxide in production, and has high safety requirements.

[0012] Currently, both domestically and internationally, the condenser medium in the top condenser of the hydroquinone product production tower using the phenol hydroxylation process described above is usually direct condensation with circulating water. This makes it difficult to control the temperature of the condensate, often resulting in overcooling that causes blockage of the condenser tubes and the shell side of the circulating water to easily form scale, affecting heat exchange. In severe cases, it can even lead to safety accidents, significantly impacting the stable operation of the product tower, preventing automated operation, and compromising product quality. Therefore, an automatic control system and method for the refrigerant temperature of the hydroquinone product distillation tower is provided. Summary of the Invention

[0013] The purpose of this invention is to address the deficiencies of the prior art by providing an automatic control system and method for the refrigerant temperature of a hydroquinone product distillation column, thereby solving the problems mentioned in the background art.

[0014] To achieve the above objectives, the present invention provides the following technical solution: an automatic control system for refrigerant temperature in a distillation column for hydroquinone products, comprising a refrigerant tank, a circulating pump, a top condenser, an air cooler, and a distillation column. The refrigerant tank is connected to the circulating pump via pipelines, and the circulating pump is connected to the top condenser via pipelines. The top condenser is connected to both the air cooler and the distillation column via pipelines. The air cooler is connected to the refrigerant tank via the refrigerant temperature control system. An automatic refrigerant tank drainage system is connected to the bottom of the refrigerant tank, and a venting pipeline is connected to the top of the refrigerant tank. A refrigerant level automatic control system and a refrigerant tank auxiliary heating system are connected to the refrigerant tank.

[0015] As a preferred embodiment of the present invention, the top of the tower top condenser is connected to a vacuum system pipeline, and the bottom of the tower top condenser is connected to a reflux pipeline.

[0016] As a preferred embodiment of the present invention, a bypass regulating valve is installed on the connecting pipeline between the tower top condenser and the air cooler, and the bypass regulating valve is connected to the refrigerant temperature control system.

[0017] As a preferred embodiment of the present invention, a regulating valve, a flow meter, a pressure gauge, and a condenser outlet thermometer are installed on the connecting pipeline between the circulating pump and the condenser at the top of the tower.

[0018] As a preferred embodiment of the present invention, the refrigerant tank is equipped with a refrigerant tank conductivity monitor, a high-level switch, a steam trap, a level gauge, a thermometer, and a heating inner coil.

[0019] As a preferred embodiment of the present invention, the refrigerant tank is a vertical cylindrical storage tank made of SUS304; the tower top condenser is a horizontal fixed tube sheet type shell and tube heat exchanger made of SUS304.

[0020] The top condenser has tube boxes installed at both ends, and one tube box has a partition in the middle, which divides the tube box into upper and lower chambers.

[0021] As a preferred technical solution of the present invention, the air cooler is provided with finned heat exchange tubes, two side tube boxes and refrigerant inlet and outlet, variable frequency fan, air guide duct and equipment support.

[0022] As a preferred technical solution of the present invention, the refrigerant temperature control system consists of a variable frequency regulating fan, a subcooling bypass regulating valve, a thermometer, and a DCS automatic control system.

[0023] The refrigerant level control system consists of a refrigerant tank level gauge L, a level switch LS, a replenishment valve, and a DCS automatic control system.

[0024] The refrigerant tank auxiliary heating system consists of a refrigerant tank thermometer, an auxiliary heating switch valve, and a DCS automatic control system.

[0025] The refrigerant tank automatic sewage discharge system consists of a refrigerant tank conductivity monitor, a sewage discharge switch valve, and a DCS automatic control system.

[0026] The following are the specific steps for using an automatic control system for the refrigerant temperature in a hydroquinone product distillation column:

[0027] S1: Set the automatic control logic through the DCS control system and gradually implement automatic control;

[0028] S2: The refrigerant level control system of the DCS refrigerant tank sets the upper and lower limits of the liquid level L to 40-80%. When it is below 40%, the liquid replenishment switch valve of the refrigerant level control system automatically opens to inject soft water. When the liquid level reaches the set level of 80%, the liquid replenishment switch valve closes. After automatic operation is put into operation, the liquid level is automatically controlled and regulated.

[0029] S3: Under the condition of step S2, the circulation pump is automatically started by setting the DCS. The inner loop of the DCS cascade control system tracks the circulation flow rate and the outer loop tracks the temperature T2, so as to realize automatic adjustment of flow rate and temperature.

[0030] S4: The refrigerant tank temperature T1 is set through the DCS, and the auxiliary heating switch valve of the refrigerant tank auxiliary heating system is controlled by the following logic: when the temperature is below 50℃, the auxiliary heating switch valve is opened to heat the refrigerant; when the set temperature of 70℃ is reached, the auxiliary heating switch valve is closed. The initial temperature control of the refrigerant is achieved through the auxiliary heating system to meet the operating conditions for the distillation column to start.

[0031] S5: The refrigerant tank temperature T1 is set via DCS. The automatic control system, consisting of the fan frequency converter and bypass regulating valve, automatically starts the fan motor when the temperature is above 80°C, and the frequency converter automatically adjusts the frequency to track the temperature difference, achieving a temperature close to the set lower limit of 80°C. If the distillation column heat load is low or the winter environment is extremely cold, and the temperature of T1 is still below 80°C even with all fan motors shut down, the bypass regulating valve automatically opens, directly short-circuiting the higher-temperature hot water back to the refrigerant tank to reduce the flow into the air cooler. If the temperature of T1 continues to drop below 50°C, the refrigerant tank auxiliary heating system automatically starts as described in step S4.

[0032] S6: The DCS sets up an automatic control system consisting of a refrigerant tank conductivity monitor. According to the water quality requirements, the upper and lower limits of conductivity are set. If the conductivity is higher than the upper limit, the drain valve of the refrigerant tank automatic drain system is opened for automatic draining. If the conductivity is lower than the lower limit, the drain valve is closed for automatic conductivity control. The refrigerant level control system is automatically put into operation as described in step S2 until the conductivity reaches the set value.

[0033] S7: The high-level switch of the refrigerant tank is interlocked with the drain valve of the automatic drain system of the refrigerant tank through the DCS: when the high-level switch is closed, the drain valve is automatically opened, and when the liquid level drops to 80%, the drain valve is closed to realize the high-level control logic. This drain valve closing control logic takes step S6 as the priority condition.

[0034] S8: The vent line is usually in the open state to keep the refrigerant tank system at atmospheric pressure.

[0035] Compared with existing technologies, the advantages of this invention are: This invention achieves fully automatic control by adjusting the frequency of the air cooler's fan inverter to regulate the heat load of the air cooler, thereby controlling the refrigerant temperature and subsequently the material temperature of the top condenser. The controlled temperature is precise and stable, and can be operated with a single button via program control, achieving fully automatic operation of the refrigerant system. From initial liquid replenishment, circulation system startup, auxiliary heating to temperature self-control, automatic sewage discharge, and liquid replenishment, all are programmed through the DCS system without human intervention. This overcomes the problems of traditional methods that use circulating water as the condensing medium, such as easy overcooling and pipe blockage of the condenser, difficulty in controlling the material temperature of the top condenser, scaling and blockage of the condenser shell side, unstable operation, and failure to guarantee product quality.

[0036] Compared with traditional tower top condensers that use circulating water for condensation, this invention achieves a closed-loop refrigerant system that does not consume water resources, enables precise and automatic control of refrigerant temperature, is unaffected by environmental climate, and requires no manual intervention. It overcomes the problems of traditional condensers using circulating water as refrigerant, such as excessive temperature difference, difficulty in controlling condensate temperature, even condenser overcooling and pipe blockage, high hardness of circulating water leading to scaling and blockage in the condenser shell side, unstable operation, and great susceptibility to environmental temperature. Attached Figure Description

[0037] Figure 1 This is a process flow diagram of the present invention.

[0038] In the diagram: 1. Refrigerant tank; 2. Circulating pump; 3. Tower top condenser; 4. Air cooler; 5. Refrigerant temperature control system; 6. Refrigerant level automatic control system; 7. Refrigerant tank auxiliary heating system; 8. Refrigerant tank automatic sewage discharge system; 9. Distillation column; 10. Reflux line; 11. Control valve; 12. Flow meter; 13. Vent line; 14. Steam trap; 15. Refrigerant tank conductivity monitor; 16. High-level switch; 17. Bypass control valve; 18. Vacuum system line. Detailed Implementation

[0039] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0040] Example: Please refer to Figure 1 This invention provides a technical solution: an automatic control system for refrigerant temperature in a distillation column for hydroquinone products, comprising a refrigerant tank 1, a circulating pump 2, a top condenser 3, an air cooler 4, and a distillation column 9. The refrigerant tank 1 is connected to the circulating pump 2 via pipelines, and the circulating pump 2 is connected to the top condenser 3 via pipelines. The top condenser 3 is connected to both the air cooler 4 and the distillation column 9 via pipelines. An automatic drain system 8 is connected to the bottom of the refrigerant tank 1, and a venting pipeline 13 is connected to the top of the refrigerant tank 1. A refrigerant temperature control system 5, a refrigerant level control system 6, and a refrigerant tank auxiliary heating system 7 are connected to the refrigerant tank 1.

[0041] The top of the tower top condenser 3 is connected to a vacuum system line 18, and the bottom of the tower top condenser 3 is connected to a reflux line 10.

[0042] A bypass regulating valve 17 is installed on the connecting pipeline between the top condenser 3 and the air cooler 4. The bypass regulating valve 17 is connected to the refrigerant temperature control system 5.

[0043] A regulating valve 11, a flow meter 12, a pressure gauge, and a condenser outlet thermometer are installed on the connecting pipeline between the circulating pump 2 and the condenser 3 at the top of the tower.

[0044] The refrigerant tank 1 is equipped with a refrigerant tank conductivity monitor 15, a high-level switch 16, a steam trap 14, a level gauge, a thermometer, and an inner heating coil.

[0045] The refrigerant tank 1 is a vertical cylindrical storage tank made of SUS304. Different refrigerants can be selected according to the temperature requirements of the refrigerant in the different distillation towers of hydroquinone: softened water is usually used when the temperature is controlled below 100℃; high-boiling-point media such as T55 heat transfer oil are usually used when the temperature is controlled above 100℃ but below 200℃. In this invention, softened water is used as an example, and the temperature control range is 95℃ to 80℃.

[0046] The top condenser 3 is a horizontal fixed tube sheet heat exchanger made of SUS304. The high-temperature gaseous material from the distillation column is introduced into the upper part of the shell side. After passing through multiple baffles, it undergoes full heat exchange with the refrigerant in the tube side, becoming condensate. It flows into the lower downcomer on the other side of the shell side and enters the reflux tank. The vacuum system is connected above the downcomer of the condenser.

[0047] The top condenser 3 has tube boxes installed at both ends. One tube box has a partition in the middle, which divides the tube box into upper and lower chambers. The refrigerant is introduced from the lower part of the lower chamber, passes through the tube side and enters the other tube box, turns back to the upper part of the upper chamber of the previous tube box and is led out. It fully exchanges heat with the material in the shell side, and the temperature rises before entering the air cooler.

[0048] The air cooler 4 is equipped with finned heat exchange tubes, two side tube boxes and refrigerant inlet and outlet, variable frequency fan, air guide duct and equipment support. The part in contact with the refrigerant is made of SUS304 and the support is made of Q235 or 20# steel.

[0049] The refrigerant temperature control system 5 consists of a variable frequency drive fan, a subcooling bypass regulating valve, a thermometer, and a DCS automatic control system. It sets the refrigerant tank temperature; when the temperature exceeds the set value, the frequency of the inverter increases, increasing the fan throughput and heat dissipation, thereby lowering the refrigerant temperature passing through the air cooler. Conversely, it lowers the temperature when the temperature is below the set value. Typically, there are multiple fans; some can be set to operate at a fixed frequency, while the others operate at a frequency automatically adjusted to match the refrigerant tank temperature, thus reducing the inverter's adjustment range and making the adjustment more stable.

[0050] A lower limit for refrigerant tank temperature control is set. When the temperature falls below the set lower limit, the subcooling bypass regulating valve is activated to return the high-temperature refrigerant from the distillation column condenser outlet directly to the refrigerant tank, reducing the heat load on the air cooler and ensuring the refrigerant temperature in the tank remains within the set range. The program is set to open the temperature subcooling bypass regulating valve only when the distillation column heat load is low, all fans have stopped operating, and the lower limit temperature still cannot be maintained.

[0051] The refrigerant level control system 6 consists of a refrigerant tank level gauge L, a level switch LS, a replenishment valve, and a DCS automatic control system. It sets the upper and lower limits of the liquid level and achieves automatic control through the replenishment switch. When the liquid level is lower than the set value, the replenishment switch automatically opens to replenish the liquid and automatically closes when the liquid level is reached.

[0052] The refrigerant tank auxiliary heating system 7 consists of a refrigerant tank thermometer, an auxiliary heating switch valve, and a DCS automatic control system. A lower limit temperature for the refrigerant tank is set; if the temperature falls below this limit, the auxiliary heating switch valve automatically opens to heat the refrigerant, and closes once the set value is reached. The program is set to activate the auxiliary heating switch valve only when the distillation column's heat load is low, all fans are stopped or not running, and the lower limit temperature cannot be maintained, even after opening the subcooling bypass regulating valve.

[0053] The refrigerant tank automatic drain system 8 consists of a refrigerant tank conductivity monitor 15, a drain valve, and a DCS automatic control system. The drain control system strictly controls the refrigerant hardness index and sets a conductivity value. If the conductivity value is higher than the set value, the drain valve will automatically open to drain the refrigerant, accurately ensuring the soft water index in the refrigerant tank, so as to ensure safe operation and reduce scaling in the circulation system. When the drain reaches the set liquid level, the replenishment valve will automatically open until the conductivity reaches the set value, and then close the drain valve.

[0054] In the distillation process of hydroquinone, the overhead condenser uses refrigerant to condense high-temperature gaseous materials. To achieve heat balance, accurately control the refrigerant temperature, and prevent overcooling, blockage, and scaling in the condenser tubes, thus ensuring stable operation of the distillation column, a system was designed to automatically control key parameters such as refrigerant temperature, liquid level, and hardness through a DCS system. This completely overcomes the drawbacks of using circulating water for condensation, such as scaling, overcooling, corrosion, and water consumption. It provides the basic engineering conditions for refined operation of the distillation column, stabilizes the operation of the distillation system, and improves product quality and yield to a certain extent.

[0055] The following are the specific steps for using an automatic control system for the refrigerant temperature in a hydroquinone product distillation column:

[0056] S1: Set the automatic control logic through the DCS control system and gradually implement automatic control;

[0057] S2: The refrigerant level control system 6 of the DCS refrigerant tank sets the upper and lower limits of the liquid level L to 40-80%. When it is below 40%, the liquid replenishment switch valve of the refrigerant level control system 6 automatically opens to inject soft water. When the liquid level reaches the set level of 80%, the liquid replenishment switch valve closes. After automatic operation is put into operation, the liquid level is automatically controlled and regulated.

[0058] S3: Under the condition of step S2, the circulation pump 2 is automatically started by setting the DCS. The regulating valve 11 of the DCS cascade regulation system tracks the circulation flow rate in the inner loop and the temperature T2 in the outer loop to achieve automatic regulation of flow rate and temperature.

[0059] S4: The refrigerant tank temperature T1 is set by the DCS, and the auxiliary heating switch valve of the refrigerant tank auxiliary heating system 7 is controlled by the following logic: when the temperature is below 50℃, the auxiliary heating switch valve is opened to heat the refrigerant; when the set temperature of 70℃ is reached, the auxiliary heating switch valve is closed. The initial temperature control of the refrigerant is achieved through the auxiliary heating system to meet the operating conditions for the distillation column to start up.

[0060] S5: The refrigerant tank temperature T1 is set via DCS. The automatic control system, consisting of the fan frequency converter and bypass regulating valve 17, automatically starts the fan motor when the temperature is above 80°C, and the frequency converter automatically adjusts the frequency to track the temperature difference, achieving a temperature close to the set lower limit of 80°C. If the distillation column heat load is low or the winter environment is extremely cold, and the temperature of T1 is still below 80°C even with all fan motors shut down, the bypass regulating valve 17 automatically opens, directly short-circuiting the higher-temperature hot water back to the refrigerant tank 1, reducing the flow into the air cooler 4. If the temperature of T1 continues to drop below 50°C, the refrigerant tank auxiliary heating system 7 automatically starts operating as described in step S4.

[0061] S6: The DCS sets up an automatic control system consisting of the refrigerant tank conductivity monitor 15. According to the water quality requirements, the upper and lower limits of conductivity are set. If the conductivity is higher than the upper limit, the drain valve of the refrigerant tank automatic drain system 8 is opened for automatic draining. If the conductivity is lower than the lower limit, the drain valve is closed for automatic conductivity control. The refrigerant level control system 6 is automatically put into operation as described in step S2 until the conductivity reaches the set value.

[0062] S7: The high-level switch 16 of the refrigerant tank is interlocked with the drain valve of the automatic drain system 8 of the refrigerant tank through the DCS: when the high-level switch 16 is closed, the drain valve is automatically opened, and when the liquid level drops to 80%, the drain valve is closed to realize the high-level control logic. This drain valve closing control logic takes step S6 as the priority condition.

[0063] S8: Vent line 13 is normally open to keep the refrigerant tank system at atmospheric pressure.

[0064] This invention achieves fully automatic control by adjusting the frequency of the air cooler's fan inverter to regulate the air cooler's heat load, thereby controlling the refrigerant temperature and consequently the material temperature in the top condenser. The controlled temperature is precise and stable, and the system can be operated with a single button via program control, enabling fully automatic operation of the refrigerant system. From initial liquid replenishment, circulation system startup, auxiliary heating to temperature self-control, automatic sewage discharge, and liquid replenishment, all processes are programmed through the DCS system without human intervention. This overcomes the problems of traditional methods that use circulating water as the condensing medium, such as condenser overcooling and pipe blockage, difficulty in controlling the material temperature in the top condenser, scaling and blockage in the condenser shell side, unstable operation, and unreliable product quality.

[0065] Compared with traditional tower top condensers that use circulating water for condensation, this invention achieves a closed-loop refrigerant system that does not consume water resources, enables precise and automatic control of refrigerant temperature, is unaffected by environmental climate, and requires no manual intervention. It overcomes the problems of traditional condensers using circulating water as refrigerant, such as excessive temperature difference, difficulty in controlling condensate temperature, even condenser overcooling and pipe blockage, high hardness of circulating water leading to scaling and blockage in the condenser shell side, unstable operation, and great susceptibility to environmental temperature.

[0066] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. The method of using the automatic control system for refrigerant temperature in a distillation column for hydroquinone products, characterized in that, The automatic control system for refrigerant temperature of the distillation column of the hydroquinone product includes a refrigerant tank (1), a circulating pump (2), a top condenser (3), an air cooler (4), and a distillation column (9). The refrigerant tank (1) is connected to the circulating pump (2) through a pipeline. The circulating pump (2) is connected to the top condenser (3) through a pipeline. The top condenser (3) is connected to the air cooler (4) and the distillation column (9) through pipelines. The bottom of the refrigerant tank (1) is connected to an automatic sewage discharge system (8). The top of the refrigerant tank (1) is connected to a venting pipeline (13). The refrigerant tank (1) is connected to a refrigerant level automatic control system (6), a refrigerant tank auxiliary heating system (7), and a refrigerant temperature control system (5). A bypass regulating valve (17) is installed on the connecting pipeline between the top condenser (3) and the air cooler (4), and the bypass regulating valve (17) is connected to the refrigerant temperature control system (5); a regulating valve A (11), a flow meter (12), a pressure gauge, and a condenser outlet thermometer are installed on the connecting pipeline between the circulating pump (2) and the top condenser (3); a refrigerant tank conductivity monitor (15), a high-level switch (16), a steam trap (14), a level gauge, a thermometer, and a heating inner coil are installed on the refrigerant tank (1); The air cooler (4) consists of finned heat exchange tubes, two side tube boxes and refrigerant inlet and outlet, variable frequency fan, air guide duct and equipment support; the refrigerant temperature control system (5) consists of variable frequency regulating fan, subcooling bypass regulating valve, thermometer and DCS automatic control system; the refrigerant liquid level automatic control system (6) consists of refrigerant tank liquid level gauge L, liquid level switch LS, liquid replenishment switch valve and DCS automatic control system; the refrigerant tank auxiliary heating system (7) consists of refrigerant tank thermometer, auxiliary heating switch valve and DCS automatic control system; the refrigerant tank automatic sewage discharge system (8) consists of refrigerant tank conductivity monitor (15), sewage discharge switch valve and DCS automatic control system. The specific steps are as follows: S1: Set the automatic control logic through the DCS automatic control system and gradually put it into automatic control; S2: The upper and lower limits of the liquid level L are set to 40-80% through the refrigerant liquid level automatic control system (6) of the refrigerant tank. When it is lower than 40%, the liquid replenishment switch valve of the refrigerant liquid level automatic control system (6) will open automatically to inject soft water. When the liquid level reaches 80%, the liquid replenishment switch valve will close. After automatic operation is put into operation, the liquid level will be automatically controlled and regulated. S3: Under the condition of step S2, the DCS sets the circulation pump (2) to start automatically. Through the regulating valve A (11), the inner loop tracks the circulation flow rate and the outer loop tracks the temperature T2, so as to realize the automatic adjustment of flow rate and temperature. S4: Set the refrigerant tank temperature T1 through DCS, and control the logic of the auxiliary heating switch valve of the refrigerant tank auxiliary heating system (7): when the temperature is below 50℃, the auxiliary heating switch valve is opened to heat the refrigerant; when the set temperature of 70℃ is reached, the auxiliary heating switch valve is closed, and the initial temperature control of the refrigerant is achieved through the auxiliary heating system to meet the distillation column startup conditions. S5: The refrigerant tank temperature T1 is set by DCS. The automatic control system composed of the fan frequency converter and bypass regulating valve (17) will automatically start the fan motor when the temperature is above 80°C. The frequency converter frequency will automatically adjust the frequency to track the temperature difference and achieve an infinitely close lower limit temperature of 80°C. If the heat load of the distillation column is low or the winter environment is extremely cold, and the temperature of T1 is still below 80°C under the premise that all the fan motors are stopped, the bypass regulating valve (17) will be automatically opened to directly short-circuit the hot water at a higher temperature back to the refrigerant tank (1) to reduce the flow into the air cooler (4). If the temperature of T1 continues to drop to below 50°C, the refrigerant tank auxiliary heating system (7) will be automatically started as described in step S4. S6: The DCS sets the automatic control system consisting of the refrigerant tank conductivity monitor (15), and sets the upper and lower limits of conductivity according to the water quality requirements. If the conductivity is higher than the upper limit, the drain valve of the refrigerant tank automatic drain system (8) is opened for automatic draining; if the conductivity is lower than the lower limit, the drain valve is closed for automatic conductivity control. The refrigerant level control system (6) is automatically put into operation as described in step S2 until the conductivity reaches the set value. S7: The high-level switch (16) of the refrigerant tank is interlocked with the drain valve of the automatic drain system (8) of the refrigerant tank through the DCS: when the high-level switch (16) is closed, the drain valve is automatically opened, and when the liquid level drops to 80%, the drain valve is closed to realize the high-level control logic. This drain valve closing control logic takes step S6 as the priority condition. S8: The vent line (13) is usually open to keep the refrigerant tank system at normal pressure.

2. The method of using the automatic control system for refrigerant temperature in the distillation column of hydroquinone product according to claim 1, characterized in that: The top of the tower top condenser (3) is connected to a vacuum system line (18), and the bottom of the tower top condenser (3) is connected to a reflux line (10).

3. The method of using the automatic control system for refrigerant temperature in the distillation column of hydroquinone product according to claim 1, characterized in that, The refrigerant tank (1) is a vertical cylindrical tank made of SUS304; the tower top condenser (3) is a horizontal fixed tube sheet heat exchanger made of SUS304; the tower top condenser (3) has tube boxes installed at both ends, and one tube box has a partition in the middle, which divides the tube box into upper and lower chambers.

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