Operation method of reactive monomer storage tank

Abstract

A method of operating a reactive monomer storage tank includes supplying a lower discharge stream of the storage tank containing a liquid reactive monomer and a polymerization inhibitor to a first heat exchanger, cooling the lower discharge stream, and then refluxing the lower discharge stream to a liquid phase region of the storage tank; and supplying an upper discharge stream of the storage tank containing a gaseous reactive monomer to a second heat exchanger by means of a pressurizing device, cooling the upper discharge stream, and then refluxing the upper discharge stream to the gas phase region of the storage tank.

Description

Technical Field

[0001] Cross-references to related applications This application claims priority and benefit to Korean Patent Application No. 10-2024-0119625, filed on September 3, 2024, the entire contents of which are incorporated herein by reference as part of the specification.

[0002] This disclosure relates to an operating method for a reactive monomer storage tank, and more specifically to an operating method for stably suppressing polymerization in a storage tank storing reactive monomers even under changing external environmental conditions. Background Technology

[0003] In reactive monomer production plants, reactive monomers are transferred, stored, managed, and shipped to storage tanks. Sometimes, polymerization within the storage tanks before product shipment leads to an increase in polymer content, resulting in product specification deviations and sales disruptions.

[0004] Furthermore, in specific environments with high temperatures or a lack of polymerization inhibitors, the polymerization of reactive monomers can occur at rates much faster than usual. Polymerization is an exothermic reaction, releasing a large amount of heat during the polymerization process, which can lead to runaway polymerization due to heat. Additionally, due to the rapid rate of heat release, monomers or flammable substances heated above their boiling point evaporate to form explosive vapor clouds, which could lead to explosions if an ignition source is present.

[0005] Representative examples of such reactive monomers can include styrene monomers (SM). Styrene monomers are a major base oil component of petrochemical products used as raw materials for the synthesis of plastics such as polystyrene (PS), SBR, and ABS. The double bonds (vinyl groups) in the structure of styrene monomers are readily polymerized by light, heat, peroxides, catalysts, etc., making them suitable as polymer synthesis raw materials. However, due to their high reactivity, styrene monomers can induce unintended polymerization, i.e., self-polymerization, in storage tanks during storage and transportation. Regular monitoring of the temperature of the styrene monomer, the polymerization inhibitors in the styrene monomer, and the polymer concentration in the styrene monomer to appropriately control self-polymerization is crucial for product management.

[0006] In plants producing and managing reactive monomers such as styrene monomer, the temperature inside storage tanks and the concentration of polymerization inhibitors are critical factors in management and operation. However, unexpected temperature rises can occur due to external environmental influences. When temperature changes occur due to external factors, polymerization may occur, potentially leading to polymer formation. This can result not only in economic losses but also serious accidents. Furthermore, when gaseous reactive monomers generated at high temperatures condense on the inner walls of storage tanks and remain stagnant due to external environmental factors such as external temperature, problems may arise in the formation of solid polymers (oxides).

[0007] Therefore, it is necessary to develop a technology that can stably suppress polymerization and prevent polymer formation even when the external environment changes during the operation of tanks storing reactive monomers. Summary of the Invention

[0008] Technical issues The problem to be solved in this disclosure is to provide a method for suppressing the polymerization of reactive monomers and preventing polymer formation by stably operating a storage tank for storing reactive monomers in response to changes in the external environment, thereby solving the problems described in the background art above.

[0009] However, the problems to be addressed by this disclosure are not limited to those described above. That is, other issues not mentioned will be readily apparent to those skilled in the art based on the following disclosure.

[0010] Technical solution In one general aspect, a method of operating a reactive monomer storage tank includes: supplying a lower discharge stream of the tank, comprising liquid reactive monomer and polymerization inhibitor, to a first heat exchanger to cool the lower discharge stream, and then returning the lower discharge stream to a liquid phase region of the tank; and supplying an upper discharge stream of the tank, comprising gaseous reactive monomer, to a second heat exchanger via a pressurization device to cool the upper discharge stream, and then returning the upper discharge stream to a gas phase region of the tank.

[0011] Beneficial effects According to the operating method of the reactive monomer storage tank of this disclosure, reactive monomers can be stably stored by controlling the temperature, pressure and / or oxygen concentration of the liquid phase region and the gas phase region in response to changes in the external environment.

[0012] More specifically, by inhibiting the polymerization of liquid reactive monomers in the storage tank to prevent runaway polymerization due to heat, and by inhibiting the formation of solid polymers through the condensation of evaporated gaseous reactive monomers on the inner wall of the storage tank, accidents such as vapor leaks and explosions can be prevented.

[0013] The effects achievable through this disclosure are not limited to those described above. That is, based on the following description, those skilled in the art to which this disclosure pertains will readily understand other effects not described. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of the operation method of a reactive monomer storage tank according to one embodiment of the present disclosure.

[0015] Figure 2 This is a process flow diagram of the operation method of a reactive monomer storage tank according to one embodiment of the present disclosure.

[0016] Figure 3 This is a process flow diagram based on the conventional operation method of the reactive monomer storage tank of the comparative example. Detailed Implementation

[0017] The terms and words used in this specification and claims should not be interpreted in their general or dictionary sense, but rather based on the principle that inventors can appropriately define the concepts of terms in order to describe their own inventions in the best possible way, and should be interpreted as meanings and concepts that satisfy the technical concept of this disclosure.

[0018] Throughout the accompanying drawings, similar or related components will be indicated by similar reference numerals.

[0019] Unless the relevant context clearly specifies otherwise, the singular form of the noun corresponding to an item may include one or more of the items mentioned.

[0020] In this disclosure, each phrase such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B or C” can include any one of the items listed together in the corresponding phrases of these phrases or all possible combinations thereof.

[0021] The term "and / or" includes a combination of components of a plurality of related descriptions or any one of the components of a plurality of related descriptions.

[0022] Terms such as “first” and “second” can be used simply to distinguish one component from another without limiting the component in other ways (e.g., importance or order).

[0023] Furthermore, the terms “front,” “rear,” “top,” “bottom,” “side,” “left,” “right,” “upper,” “lower,” etc., used in this disclosure are defined based on the accompanying drawings, and the shape and position of each component are not limited by these terms.

[0024] It should be understood that the terms “comprising” or “having” specify the presence of features, numbers, steps, operations, components, parts or combinations thereof mentioned in this disclosure, but do not exclude the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0025] When a component is "connected", "coupled", "supported", or "in contact" with another component, this includes not only cases where the components are directly connected, coupled, supported, or in contact, but also cases where they are indirectly connected, coupled, supported, or in contact through a third component.

[0026] When one component is "on" another component, this includes not only situations where the component is in contact with another component, but also situations where there is another component between the two components.

[0027] Furthermore, the terms “about,” “substantially,” etc., used throughout this disclosure refer to figures and near figures corresponding to manufacturing and material tolerances specific to the stated meaning, and are intended to prevent unscrupulous misuse of figures that are not precisely or absolutely described to aid in understanding this disclosure.

[0028] In this disclosure, the term "flow" can refer to the flow of fluid in a process, and can also refer to the fluid itself flowing in a pipe. Specifically, flow can refer to the fluid itself and the flow of fluid within the pipes connecting each device. Furthermore, the fluid can include any at least one component of gas, liquid, and solid.

[0029] Unless otherwise stated, the term "upper part" as used in this disclosure refers to a height point of 0% to 20% downward from the top of the device, and may specifically refer to the uppermost part (top). Conversely, the term "lower part" refers to a height point of 80% to 100% downward from the uppermost part of the device, and may specifically refer to the lowermost end (bottom).

[0030] Furthermore, the term "pressure" as used in this disclosure refers to gauge pressure measured based on atmospheric pressure.

[0031] The operation of the reactive monomer storage tank of this disclosure will be described below with reference to the accompanying drawings, but the drawings are exemplary and the scope of the operation of the reactive monomer storage tank is not limited thereto.

[0032] This disclosure relates to an operating method for a storage tank for storing reactive monomers. Figure 1 and Figure 2 The process flow of operating a storage tank according to one embodiment of the present disclosure is shown.

[0033] Figure 3 The process flow diagram for a conventionally operating reactive monomer storage tank is shown. (Refer to...) Figure 3 Conventionally, to prevent accidents caused by runaway polymerization of reactive monomer M during storage, the following methods are typically used: supplying an inert gas IG, such as nitrogen, to the gas phase region 12 of the storage tank 10 for covering treatment, controlling the vent valve to control the pressure inside the storage tank 10, using a heat exchanger 21 to prevent the temperature of the liquid reactive monomer from rising, and injecting a polymerization inhibitor and managing the amount of dissolved oxygen to suppress polymer production.

[0034] Despite this management of operating conditions for tank 10, the temperature of the gaseous region 12 within tank 10 exhibits a similar trend to the external temperature. Consequently, reactive monomers repeatedly evaporate and condense due to daily temperature variations, and the absence of polymerization inhibitors in the gaseous region 12 increases the risk of explosion, as the amount of gaseous reactive monomers increases with temperature, and the reactive monomers condensed on the inner wall of the tank form dead zones where they stagnate without flow, leading to the formation of solid polymers (oxides). Furthermore, when polymers form on the inner wall of tank 10 or at openings for vapor (gas) or liquid inlets and outlets, pressure or temperature control becomes difficult, potentially degrading the operational stability of the tank.

[0035] To address this problem, this disclosure aims to improve the operational stability of reactive monomer storage tanks by controlling the temperatures of the liquid phase region and the gas phase region in addition to conventional operating methods.

[0036] An operating method for a reactive monomer storage tank according to one embodiment of the present disclosure includes: supplying a lower discharge stream of a storage tank 10 containing liquid reactive monomer M and a polymerization inhibitor to a first heat exchanger 21, cooling the lower discharge stream, and then returning the lower discharge stream to the liquid phase region 11 of the storage tank; and supplying an upper discharge stream of a storage tank containing gaseous reactive monomer to a second heat exchanger 22 via a pressurizing device 30, cooling the upper discharge stream, and then returning the upper discharge stream to the gas phase region 12 of the storage tank.

[0037] Reference Figure 1 The lower discharge stream of the tank containing the liquid reactive monomer M and the polymerization inhibitor is supplied to the first heat exchanger 21 for cooling, and then returned to the liquid phase region 11 of the tank. Furthermore, the lower discharge stream of the tank 10 can be partially branched and discharged as needed, and newly received reactive monomer M can be incorporated into the cooled lower discharge stream and injected into the tank.

[0038] Reactive monomer M is a material that is readily polymerized by light, heat, catalysts, etc., and is mainly used as a polymer feedstock. It may also undergo self-polymerization during storage and transportation. Examples of reactive monomers include styrene, acrylonitrile, butadiene, etc.

[0039] Furthermore, most reactive monomers can exist in the liquid phase in the storage tank 10, and some can exist in the gas phase. Here, based on the liquid level of the reactive monomers, the interior of the storage tank 10 can be divided into a liquid phase region 11 and a gas phase region 12.

[0040] In one embodiment, styrene monomer is a colorless or pale yellow flammable liquid with a pungent odor and is used as a monomer for the polymerization of certain polymer compounds such as polystyrene (PS) resin, ABS resin, unsaturated polyester resin, and synthetic rubber (SBR) raw materials. Styrene monomer can be polymerized using various initiators such as free radical, cationic, anionic, and coordination mechanisms, and polymerization can occur thermally if there are no impurities. Furthermore, when the inhibitor is in an appropriate ratio or less, styrene monomer may autopolymerize, and the temperature and pressure of the corresponding equipment may increase due to the heat generated during polymerization. In addition, styrene monomer reacts with oxidants, peroxides, strong acids, etc., and copper and copper alloys should be avoided, as rust may promote polymerization. Furthermore, styrene monomer has the property of releasing pungent vapors during thermal polymerization and producing carbon monoxide during incomplete combustion.

[0041] Polymerization inhibitors can prevent polymerization by reacting with the free radicals of the growth chain initiated by the reactive monomer to deactivate the free radicals, or by acting as antioxidants to inhibit polymerization by reacting with oxides generated within the reactive monomer. For example, polymerization inhibitors may include 4-tert-butylcatechol (TBC), p-tert-butylcatechol, etc. As an example, TBC can be added to prevent the formation of polymers due to oxidative degradation and polymerization of styrene during transportation and storage.

[0042] Furthermore, based on the total amount of reactive monomers contained in the liquid phase region of the storage tank, the content of the polymerization inhibitor can be from 0.0005% by weight to 0.5% by weight, preferably from 0.001% by weight to 0.002% by weight, and more preferably from 0.001% by weight to 0.0015% by weight. By satisfying this content range, the polymerization of reactive monomers can be reduced.

[0043] Tank 10 is a large-capacity storage facility for reactive monomers, and preferably, its internal upper structure is small and made of a smooth material to minimize the space available for polymer formation. For example, tanks with minimized internal beams, pipes, and gaps are preferred, providing space for the accumulation and polymerization of condensed reactive monomer vapors. Furthermore, the tank should be made of a material that does not react with reactive monomers or polymerization inhibitors. For example, materials such as copper or copper alloys may react with polymerization inhibitors, resulting in the formation of green contaminants and scale, which can act as catalysts for the reactive monomers.

[0044] According to one embodiment, the liquid discharge stream from the lower part of the storage tank is cooled by a first heat exchanger 21 and returned to the liquid phase region, thereby maintaining the temperature of the liquid phase region within the range of -8°C to 35°C, preferably 0°C to 24°C, and more preferably 3°C to 21°C. By maintaining the temperature of the liquid phase region within the above range, the polymerization of reactive monomers can be suppressed.

[0045] The first heat exchanger 21 is a heat exchanger capable of liquid-liquid heat exchange, and can be, for example, a refrigeration unit, whose refrigerant can be Freon, ammonia, propylene, cooling water, etc.

[0046] According to one embodiment, the transfer of the lower discharge stream of storage tank 10 can be carried out by a circulation pump installed in the pipeline. In this case, when the lower discharge stream of the liquid phase is circulated and injected into the gas phase region 12, there is a possibility of explosion due to electrostatic discharge. Therefore, in order to prevent electrostatic discharge, it is preferable to provide an inlet for the liquid stream to be injected at the bottom of the storage tank, so that the lower discharge stream of the liquid phase only flows back to the liquid phase region 11.

[0047] In addition, an ejector (not shown) can be installed at the inlet through which the lower discharge stream of the liquid phase flows back. When an ejector is installed, it can help mix within the liquid phase region 11 of the tank, thereby improving temperature uniformity. Furthermore, mixing in the liquid phase region 11 can be promoted when the outlet and inlet of the lower discharge stream of the liquid phase are set in opposite directions.

[0048] Reference Figure 1 The upper discharge stream of the storage tank containing the gaseous reactive monomer is supplied to the second heat exchanger 22 via a pressurization device 30, cooled, and then returned to the gaseous region 12 of the storage tank. In this case, the pressure and temperature of the gaseous region 11 of the storage tank 10 can be monitored in real time by a pressure measuring sensor P and a temperature measuring sensor T, respectively, and the refrigerant of the second heat exchanger 22 can be a liquid such as water.

[0049] If necessary, the upper discharge stream of the storage tank can be branched, with some of the upper discharge stream flowing back to the storage tank 10 without passing through the second heat exchanger 22, while the rest can be cooled by the second heat exchanger 22 and then flow back to the storage tank 10.

[0050] According to one embodiment, the upper exhaust flow of the gas phase from the storage tank can be cooled by the second heat exchanger 22 and returned to the gas phase region 12, thereby maintaining the temperature of the gas phase region within a range of 0°C to 35°C, preferably 0°C to 30°C, and more preferably 0°C to 25°C. By maintaining the temperature of the gas phase region within the above range, the evaporation of liquid reactive monomers within the storage tank can be prevented, and thus the formation of solid polymers (oxides) from reactive monomers condensed on the inner wall of the storage tank due to influences such as external temperature can be suppressed.

[0051] Additionally, the upper discharge stream of the gas phase from storage tank 10 can be supplied by pressurization device 30. In this case, when the upper discharge stream of the gas phase circulates and is injected into the liquid phase region 11, vapor may move from the liquid phase region 11 to the gas phase region 12, causing droplet splashing and agglomeration due to droplet entrainment. Therefore, it is preferable to return the upper discharge stream of the gas phase only to the gas phase region 12 of the storage tank.

[0052] Additionally, the pressure in the gas phase zone 12 can be controlled by a pressurizing device 30 and / or a vent valve located at the top of the storage tank to discharge vapor. For example, the pressure in the gas phase zone can be maintained within the range of 0 mmH2O to 200 mmH2O, preferably 0 mmH2O to 50 mmH2O, and more preferably 10 mmH2O to 20 mmH2O. By maintaining the pressure in the gas phase zone within the aforementioned range, the temperature of the gas phase zone can be controlled, and the stability of the facility can be improved. The pressurizing device 30 can be, for example, a blower or a compressor, and the vent valve can be designed to minimize vapor discharge.

[0053] In addition, to prevent electrostatic accidents, inert gas IG can be injected into the gas phase zone 12 of the storage tank for covering. Specifically, refer to... Figure 1 An inert gas IG can be injected into the upper discharge stream of the storage tank and supplied to the gas phase region 12 of the storage tank. For example, the inert gas may include nitrogen (N2), carbon dioxide (CO2), etc., and the amount of inert gas injected can be very small.

[0054] Simultaneously, for the polymerization inhibitor to function effectively within the reactive monomer, sufficient oxygen should be dissolved within the reactive monomer, and even when storing the reactive monomer by covering it with an inert gas, a sufficient oxygen concentration should be maintained. In this regard, refer to... Figure 2 By injecting air (AIR) into the upper exhaust stream of the storage tank and returning the upper exhaust stream to the gas phase region 12 of the storage tank, the dissolved oxygen concentration in the liquid phase region 11 and the oxygen concentration in the gas phase region 12 of the storage tank can be controlled. In this case, an oxygen concentration measuring sensor (C... g C l The dissolved oxygen concentration in the liquid phase region 11 and the oxygen concentration in the gas phase region 12 are monitored in real time. Furthermore, the dissolved oxygen concentration in the liquid phase region 11 and the oxygen concentration in the gas phase region 12 can be controlled by adjusting the amount of air (AIR) supplied to the storage tank 10 in real time based on the oxygen concentration in each region as confirmed by the oxygen concentration measurement sensor. For example, when air (AIR) is supplied to the gas phase region of the storage tank and the oxygen concentration in the gas phase region 12 increases, the dissolved oxygen concentration in the liquid phase region 11 can also increase.

[0055] For example, the dissolved oxygen concentration in the liquid phase region 11 can be controlled to be 5 ppm to 30 ppm, preferably 10 ppm to 25 ppm, and more preferably 15 ppm to 20 ppm. Furthermore, the oxygen concentration in the gas phase region can be controlled to be 2 vol% to 10 vol%, preferably 3 vol% to 8 vol%, and more preferably 5 vol% to 7 vol%. When the dissolved oxygen concentrations in the liquid phase region 11 and the gas phase region 12 are maintained within the above-mentioned ranges, the polymerization inhibitor can effectively suppress polymer formation. For example, when the oxygen concentration in the gas phase region 12 decreases below the lower limit, the dissolved oxygen concentration in the liquid phase region 11 decreases below a suitable range; therefore, the effect of the polymerization inhibitor on the liquid reactive monomer ceases, and polymerization can then proceed.

[0056] Furthermore, air (AIR) is supplied to the gas phase region 12 of the storage tank after passing through the second heat exchanger 22 together with the gaseous upper exhaust flow, thereby minimizing the temperature change of the gas phase region.

[0057] In this disclosure, additional devices such as valves, sensors, pumps, and mixers may be used if desired.

[0058] The operation of the reactive monomer storage tank according to this disclosure has been shown in the specification and accompanying drawings above; however, the drawings and descriptions above only describe and illustrate the necessary components for understanding this disclosure. In addition to the processes and apparatus shown in the above description and drawings, processes and apparatus not separately described and shown may be suitably applied and used to implement the operation of the reactive monomer storage tank according to this disclosure.

[0059] [Example] Example 1 according to Figure 1 The process flow shown operates a storage tank 10 containing styrene monomer M and uses 4-tert-butylcatechol (15 ppm) as a polymerization inhibitor.

[0060] Specifically, refer to Figure 1 The lower discharge stream from the tank containing the liquid reactive monomer M and the polymerization inhibitor is supplied to the first heat exchanger 21 for cooling, and then returned to the liquid phase region 11 of the tank, thereby controlling the temperature of the liquid phase region. Furthermore, the upper discharge stream from the tank containing the gaseous reactive monomer is supplied to the second heat exchanger 22 via a pressurization device 30 for cooling, and then returned to the gas phase region 12 of the tank, thereby controlling the temperature and pressure of the gas phase region. In addition, nitrogen is supplied to the gas phase region 12 of the tank for covering, and the pressure of the gas phase region is further controlled via a vent valve at the top of the tank.

[0061] When the storage tank is operated according to Embodiment 1 above, even after a long period of time, the temperature of the liquid phase region 11 of the storage tank remains within the range of -8°C to 35°C, the gas phase region 12 can maintain a target constant temperature within the range of 0°C to 35°C, and the pressure remains within the range of 0 mmH2O to 200 mmH2O. Therefore, the operational stability of the storage tank can be ensured, and polymer formation on the inner wall of the storage tank can be suppressed.

[0062] Example 2 according to Figure 2 The process flow shown operates a storage tank 10 containing styrene monomer M and uses 4-tert-butylcatechol (15 ppm) as a polymerization inhibitor.

[0063] Specifically, refer to Figure 2 The storage tank is operated in the same manner as in Example 1, except that an oxygen concentration measurement sensor (C) is used. l C g While monitoring the dissolved oxygen concentration in the liquid phase region 11 and the oxygen concentration in the gas phase region 12 in real time, air (AIR) is supplied to the gas phase region 12 of the storage tank.

[0064] When the storage tank is operated according to Embodiment 2 above, even after a long period of time, the liquid phase region 11 of the storage tank can maintain a temperature in the range of -8°C to 35°C and a dissolved oxygen concentration in the range of 5ppm to 30ppm, while the gas phase region 12 can maintain a target constant temperature in the range of 0°C to 35°C, a pressure in the range of 0mmH2O to 200mmH2O, and an oxygen concentration in the range of 2% to 10% by volume. Therefore, the operational stability of the storage tank can be ensured, and the formation of polymers on the inner wall of the storage tank can be suppressed.

[0065] Comparative Example 1 according to Figure 3 The process flow shown operates a storage tank 10 containing styrene monomer M and uses 4-tert-butylcatechol (15 ppm) as a polymerization inhibitor.

[0066] Specifically, refer to Figure 3 The storage tank is operated in the same manner as in Example 1, except that the process of cooling the upper discharge stream of the storage tank containing gaseous reactive monomers is not performed because the pressurization device 30 and the second heat exchanger 22 are not provided.

[0067] When the storage tank was operated according to Comparative Example 1, the liquid phase region 11 of the tank was maintained at a temperature ranging from -8°C to 35°C. However, the gas phase region 12 was greatly affected by the external temperature, making it difficult to maintain the target constant temperature. Specifically, the temperature of the gas phase region tended to be similar to the external temperature, resulting in low operational stability and difficulty in rapid temperature control.

[0068] Exemplary embodiments of this disclosure have been described above, but this disclosure is not limited thereto, and those skilled in the art will understand that various changes and modifications are possible within the concept and scope of the claims set forth below.

[0069] [Explanation of reference numerals in the attached figures] 10: Storage tank 11: Liquid phase region of the storage tank 12: Vapor phase region of the storage tank 21: First heat exchanger 22: Second heat exchanger 30: Pressurization device P: Pressure sensor T: Temperature measurement sensor C g Oxygen concentration measurement sensor in the gas phase region C l Dissolved oxygen measurement sensor in the liquid phase region M: Reactive monomer IG: Inert gas

Claims

1. An operating method for a reactive monomer storage tank, comprising: The lower discharge stream of the tank containing liquid reactive monomers and polymerization inhibitors is supplied to a first heat exchanger to cool the lower discharge stream, and then the lower discharge stream is returned to the liquid phase region of the tank. as well as The upper discharge stream of the tank containing the gaseous reactive monomer is supplied to a second heat exchanger via a pressurization device to cool the upper discharge stream, and then the upper discharge stream is returned to the gas phase region of the tank.

2. The operating method of the reactive monomer storage tank according to claim 1, comprising: Air is injected into the upper discharge stream of the storage tank to control the dissolved oxygen concentration in the liquid and gas phase regions of the storage tank.

3. The operating method of the reactive monomer storage tank according to claim 2, in, The dissolved oxygen concentration in the liquid phase region of the storage tank is controlled to be between 5 ppm and 30 ppm. The oxygen concentration in the gas phase region of the storage tank is controlled to be between 2% and 10% by volume.

4. The operating method of the reactive monomer storage tank according to claim 1, in, The temperature of the liquid phase region of the storage tank is maintained within the range of -8°C to 35°C. The temperature of the gas phase region of the storage tank is maintained within the range of 0°C to 35°C.

5. The operating method of the reactive monomer storage tank according to claim 1, in, The pressure in the gas phase region of the storage tank is maintained within the range of 0 mmH2O to 200 mmH2O.

6. The operating method of the reactive monomer storage tank according to claim 1, comprising: An inert gas is injected into the upper discharge stream of the storage tank and supplied to the gas phase region of the storage tank.

7. The operating method of the reactive monomer storage tank according to claim 6, in, The inert gas includes at least one selected from nitrogen and carbon dioxide.

8. The operating method of the reactive monomer storage tank according to claim 1, in, The reactive monomers are selected from styrene, acrylonitrile, and butadiene.

9. The operating method of the reactive monomer storage tank according to claim 1, in, The polymerization inhibitor includes at least one selected from 4-tert-butylcatechol and p-tert-butylcatechol.

10. The operating method of the reactive monomer storage tank according to claim 1, in, The pressurizing device is a blower or a compressor.

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