JP2014025674A - Heat exchange system and operation method of heat exchange system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchange system including means which promptly and easily detects the mixture of a process liquid when water is used as a heat medium.SOLUTION: A heat exchange system conducts heat exchange between a process liquid which includes hydrogen chloride and/or chlorine and a heat medium which circulates in a heat medium passage and is composed of a gaseous or liquid water in a non contact manner. The heat exchange system includes a measuring apparatus for measuring a hydrogen ion concentration or electric conductivity of condensed water generated by condensing the gaseous water or the liquid water.

Description

  The present invention relates to a heat exchange system between a process fluid and a heat medium and an operation method thereof, and more particularly to a heat exchange system capable of detecting mixing of a process fluid on the heat medium side and an operation method thereof.

  A system for producing chlorine by using hydrogen chloride gas as a raw material and reacting it with oxygen in the gas phase in the presence of a catalyst (hydrochloric acid oxidation system), for example, a raw material gas containing hydrogen chloride and oxygen in the presence of a catalyst. A reactor to be reacted, a quenching tower for obtaining chlorine by absorbing unreacted hydrogen chloride by removing it by water or hydrochloric acid water by bringing the reaction gas after the reaction into contact with water or hydrochloric acid water, and the like are provided. The reaction in the reactor is usually carried out under high pressure and high temperature and is exothermic.

  The hydrochloric acid oxidation system heats the raw material gas in advance, removes reaction heat generated from the reaction gas in the reactor, and cools the reaction gas after the reaction. A heat exchange system is provided for heating, removing heat or cooling a process fluid (raw gas, reaction gas during reaction, reaction gas after reaction) containing hydrogen chloride or chlorine.

  In such a heat exchange system for heating, heat removal or cooling, heat exchange is usually performed through a heat conductor without directly contacting the process fluid and the heat medium. As the heat medium, depending on the temperature of the process fluid, for example, in addition to molten salt, gaseous water such as steam, liquid water such as hot water and cold water, and these gaseous and liquid A mixture of water is used.

  In such a heat exchange system, when a problem occurs in the flow path through which the process fluid flows and the process fluid is mixed into the heat medium side, it is necessary to quickly detect this. Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-83833) describes a method for detecting mixing of a process fluid by detecting a gas component generated by contact between a heat medium and the mixed process fluid. Yes. Patent Document 2 (Japanese Patent Laid-Open No. 2012-47616) describes detecting the mixing of a process fluid on the heat medium side by detecting oxygen gas at a gas phase portion in the heat medium flow path. .

JP 2003-83833 A JP 2012-47616 A

  Patent Documents 1 and 2 do not specifically describe the case where gaseous or liquid water is used as the heat medium, and the method described in Patent Documents 1 and 2 is used as it is when the heat medium is water. Could not be applied. An object of this invention is to provide the heat exchange system provided with the means which can detect mixing of a process fluid quickly and simply when a heat carrier is water, and its operating method.

  The present invention provides heat exchange that performs heat exchange without direct contact between a process fluid containing hydrogen chloride and / or chlorine and a heat medium that circulates in the heat medium flow path and is composed of gaseous or liquid water. It is an exchange system, and is a heat exchange system provided with a measuring device for measuring the hydrogen ion concentration or electrical conductivity of the condensed water in which the gaseous water is condensed or the liquid water.

  The present invention also provides heat exchange without direct contact between a process fluid containing hydrogen chloride and / or chlorine and a heat medium that circulates in the heat medium flow path and is composed of gaseous or liquid water. An operation method of a heat exchange system to be performed, the heat exchange system comprising a measuring device for measuring the hydrogen ion concentration or electrical conductivity of the condensed water condensed with the gaseous water or the liquid water, A mixing detection step for detecting the mixing of the process fluid into the heat medium based on the measurement value of the measuring device, and an operation stopping step for stopping the operation of the heat exchange system when mixing is detected by the mixing detection step; It is the operating method of the heat exchange system which has this.

  In the operation method of the heat exchange system of the present invention, the operation stop step may include a supply stop step for stopping supply of the process fluid into the process fluid flow path.

  In the operation method of the heat exchange system of the present invention, the operation stop step includes mixing all the process fluid in the process fluid flow path to a detoxification facility that detoxifies hydrogen chloride and / or chlorine and releases it to the atmosphere. It can be set as the form containing a time detoxification process process.

  According to the heat exchange system of the present invention, in the heat exchange system in which the heat medium is water, the mixing of the process fluid on the heat medium side can be detected quickly and easily.

  According to the operation method of the heat exchange system of the present invention, in the heat exchange system in which the heat medium is water, mixing of the process fluid can be detected quickly and simply, and when mixing of the process fluid is detected, It is safe because the operation of the heat exchange system is stopped.

It is the schematic which shows the heat exchange system which is one Embodiment of this invention.

  The present invention provides heat exchange that performs heat exchange without direct contact between a process fluid containing hydrogen chloride and / or chlorine and a heat medium made of gaseous or liquid water flowing in the heat medium flow path. Regarding the exchange system.

  The process fluid means a gas or liquid subjected to a heat exchange process with a heat medium or a mixture thereof. The heat exchange process in the present invention may be accompanied by a reaction of the process fluid as well as heat exchange between the process fluid and the heat medium, or may be a process in which only heat exchange is performed. In the former case, the process fluid is a raw material, intermediate, product, by-product of the reaction, or a mixture of two or more thereof.

  The heat exchanger used in the heat exchange process between the process fluid and the heat medium is not particularly limited as long as the process fluid and the heat medium exchange heat through a partition such as a tube or a flat plate. Heat exchange reactors such as multitubular catalyst-filled reactors when the heat exchange process involves reaction of process fluids, multitubular cylindrical heat exchangers that are simply bulkhead heat exchangers that perform heat exchange, plate type A heat exchanger, a spiral heat exchanger, a block heat exchanger, etc. are mentioned.

The process fluid is not particularly limited as long as it contains hydrogen chloride and / or chlorine. As a preferred example of the process fluid involving a reaction, chlorine is produced by oxidizing hydrogen chloride gas with oxygen gas. ) Reaction (hydrochloric acid oxidation reaction):
2HCl + 1 / 2O ₂ → Cl ₂ + H ₂ O + 58.6 kJ / mol Formula (1)
And process fluids.

  The process fluid in the heat exchange system involving the reaction of the formula (1) is a raw material gas containing hydrogen chloride gas and oxygen gas; a reaction product gas containing chlorine, unreacted hydrogen chloride and unreacted oxygen obtained by hydrochloric acid oxidation reaction; It can be a solution containing hydrogen chloride and water obtained by contacting the reaction product gas with an absorbing solution consisting of water or aqueous hydrochloric acid; a gas obtained by removing hydrogen chloride from the reaction product gas; or a mixture thereof. These process fluids may contain inert gases such as nitrogen, carbon dioxide, and argon in addition to the components described above.

  As the process fluid in the heat exchange system involving the reaction of the formula (1), a preferable heat medium is selected according to the temperature of the target process fluid, etc., and heat is not directly in contact between the heat medium and the process fluid. By exchanging, the process fluid is heated or cooled. For example, in a process in which hydrogen chloride is removed from a product gas containing chlorine by bringing the product gas into contact with a solution containing hydrogen chloride and water to dissolve the hydrogen chloride, the solution for absorbing hydrogen chloride is By circulating while cooling by the cooler, hydrogen chloride in the reaction product gas can be absorbed without supplying new absorbed water or reducing the supply amount of new absorbed water. As a heat medium in such a cooler, cooling water is preferably used.

  Heat exchange between the process fluid and the cooling water is performed without contact. However, in the heat exchanger, if a malfunction occurs such that a hole is opened in the heat medium flow path or the process fluid flow path for some reason, the process fluid may be mixed into the heat medium flow path. It is desirable to detect such a malfunction early and appropriately deal with it early.

  In the heat exchange system of the present invention, the heat medium may be gaseous or liquid water, and may be a mixture of gaseous water and liquid water. The heat exchange system of the present invention is a measurement for measuring the hydrogen ion concentration or electrical conductivity of condensed water condensed from gaseous water used as a heat medium or liquid water used as a heat medium. Equipped with a bowl. When a process fluid containing hydrogen chloride and / or chlorine is mixed in a heat medium that is water, the hydrogen ion concentration and electrical conductivity of condensed water and liquid water both increase. Therefore, by measuring the hydrogen ion concentration or electric conductivity of condensed water or liquid water, it is possible to quickly and accurately detect the mixing of the process fluid into the heat medium. A measuring device for measuring the hydrogen ion concentration or electrical conductivity of condensed water or liquid water is preferably provided at a position in the heat medium flow path through which the heat medium after heat exchange with the process fluid passes. .

  For example, a glass electrode pH meter can be used as the hydrogen ion concentration measuring device. As an electrical conductivity measuring device, a cell having two flat platinum electrodes of the same shape can be used, and by filling the sample which is a heat medium and measuring the electrical resistance, Electrical conductivity can be determined.

  The operation method of the heat exchange system of the present invention includes a mixing detection step of detecting mixing of the process fluid into the heat medium based on the measurement value of the measuring instrument. In the contamination detection process, the hydrogen ion concentration or electrical conductivity of condensed water condensed from gaseous water used as a heat medium or liquid water used as a heat medium has exceeded a predetermined value. In some cases, mixing of the process fluid into the heat medium is detected. It is preferable to have an operation stop process for stopping the operation of the heat exchange system when mixing is detected by the above-described mixing detection process. This operation stop process is safe because the operation of the heat exchange system is quickly stopped.

  In one form of the operation method of the heat exchange system according to the present invention, when the mixing of the process fluid into the heat medium is detected by the above-described mixing detection step, the supply of the process fluid into the process fluid channel is stopped. It has a supply stop process. The method for stopping the supply of the process fluid into the process fluid flow path is not limited, but can be stopped by closing the supply path, for example. With such an operation method, even if the process fluid is mixed into the heat medium side, the amount of mixed process fluid can be suppressed, and safety can be ensured.

  Further, in the above operation method, mixing is detected by the mixing detection step, supply of the process fluid into the process fluid channel is stopped by the supply stop step, and the process fluid existing in the process fluid channel is It is preferable to have a detoxification process step at the time of mixing leading to detoxification equipment. Here, the detoxification facility is a device for detoxifying hydrogen chloride and / or chlorine and releasing it into the atmosphere. By having such a detoxification process at the time of mixing, even if hydrogen chloride, chlorine, etc. are contained in the process fluid, they are not released into the atmosphere as they are, but are rendered harmless in the atmosphere. It is safe because it is discharged.

  In one form of the operation method of the heat exchange system according to the present invention, in the heat exchange system in which heat is exchanged using water as a heat medium and heat exchange is carried out using a molten salt, a process is performed by the above-described mixing detection step. When mixing of the fluid into the heat medium is detected, there is a mixed salt cooling step for cooling the molten salt. The method for cooling the molten salt in the molten salt channel is not particularly limited. For example, in the heat exchange in the chlorine production process by hydrochloric acid oxidation reaction, a molten salt whose temperature is adjusted to 280 to 400 ° C. is preferably used. In the molten salt cooling step at the time of mixing, a method of adjusting the temperature of the molten salt to, for example, 200 to 250 ° C. is exemplified. With such an operation method, the temperature of the entire heat exchange system can be lowered, so that various reactions can be suppressed and safety can be ensured. In addition, the form which performs the said supply stop process and the said molten salt cooling process at the time of mixing simultaneously may be sufficient.

In the hydrochloric acid oxidation reaction, the molten salt used for heat exchange with the process fluid preferably contains nitrite (NaNO ₂ or the like), and preferably further contains nitrate (NaNO ₃ , KNO ₃ or the like). From the viewpoint of handleability, the melting point is preferably about 100 to 200 ° C. Specific examples of the molten salt preferably used include a composition (melting point 142 ° C.) composed of NaNO ₂ (40% by mass), NaNO ₃ (7% by mass) and KNO ₃ (53% by mass); NaNO ₂ (34% by mass) , NaNO ₃ (13 mass%) and KNO ₃ (53 mass%) (melting point 152 ° C.); NaNO ₂ (50 mass%) and KNO ₃ (50 mass%) (melting point 139 ° C.) It is.

Among them, as a molten salt used for heat exchange with the process fluid in the hydrochloric acid oxidation reaction, a molten salt composed of NaNO ₂ (50 mass%) and KNO ₃ (50 mass%) from the viewpoint of the reaction temperature of the process fluid, etc. Is preferably used. Hereinafter, the present invention will be described in more detail by showing specific embodiments.

[Heat exchange system]
FIG. 1 is a schematic diagram showing a heat exchange system according to an embodiment of the present invention. In the heat exchange system shown in FIG. 1, chlorine is produced by an oxidation process in which hydrogen chloride is oxidized with oxygen, and the reaction product gas containing chlorine, unreacted hydrogen chloride and unreacted oxygen obtained by the hydrochloric acid oxidation reaction is converted into water. Alternatively, hydrogen chloride is removed from the reaction product gas by an absorption step in contact with an absorption liquid comprising hydrochloric acid water, and a solution containing hydrogen chloride and water is obtained, and the solution is circulated to the absorption step while being cooled.

  The heat exchange system shown in FIG. 1 includes a multitubular fixed-bed catalyst reactor 1 that is a heat exchanger that performs an oxidation process, a molten salt storage drum 2 that stores molten salt, and unreacted chloride in a reaction product gas. A quenching tower 3 that performs an absorption step of absorbing hydrogen gas into water or hydrochloric acid water, a heater 4 that heats the raw material gas supplied to the oxidation step, a cooler 5 that cools the reaction product gas, and a reaction product gas A cooler 6 for cooling the solution containing unreacted hydrogen chloride and a cooler 7 for cooling the molten salt. The multi-tube fixed bed catalyst reactor 1 includes a plurality of reaction tubes (not shown) that are process fluid flow paths and a jacket (not shown) that is a molten salt flow path. The molten salt storage drum 2 includes a gas phase portion 22 and a liquid phase portion 21 made of a molten salt.

  In the heat exchange system shown in FIG. 1, the process fluid flow path includes a line 11, a process fluid flow path in the multitubular fixed bed catalyst reactor 1, and the process fluid is rapidly cooled from the multitubular fixed bed catalyst reactor 1. A line 12 leading to the tower 3, a line 13 leading the process fluid containing chlorine gas from the quenching tower 3 to the chlorine drying step, a line 14 leading the process fluid from the quenching tower 3 to the detoxification facility, and the quenching tower 3 being discharged. And a line 15 for circulating the process fluid containing hydrogen chloride and water to the quenching tower 3 while being cooled by the cooler 6. When the process fluid flowing through the line 15 becomes excessive, the excess is sent to the step of reusing hydrogen chloride.

  In the process fluid flow path, the raw material gas is guided to the multitubular fixed bed catalyst reactor 1 via the line 11. The line 11 includes a valve 31 and switches supply / stop of the source gas to the process fluid flow path by switching the open / closed state of the valve 31. The line 11 includes a heater 4, and the raw material gas supplied to the multitubular fixed bed catalyst reactor 1 is heated by the heater 4. In the multi-tubular fixed bed catalyst reactor 1, hydrochloric acid oxidation reaction in the process fluid and heat exchange between the process fluid and the molten salt are performed, and a reaction product gas in the hydrochloric acid oxidation reaction is passed through a line 12 to a quenching tower. Led to 3. The line 12 includes the cooler 5 and the reaction product gas is cooled. In the quenching tower 3, a solution containing hydrogen chloride and water flows down from the vicinity of the top of the tower, absorbs unreacted hydrogen chloride in the process fluid, and separates it from a gas mainly composed of chlorine and oxygen. The sewage is extracted from the bottom of the column and led to the line 15. A gas mainly composed of chlorine and oxygen is extracted from the top of the column.

  The line 15 includes a pump 32 and circulates a solution containing hydrogen chloride and water. The line 15 includes a cooler 6, and the cooler 6 cools the process fluid circulating in the line 15 with cooling water that is a heat medium. In the cooler 6, the process fluid is preferably cooled to 0 ° C. to 100 ° C. from the viewpoint of avoiding the absorption of hydrogen chloride in water and avoiding the dissolution of gas components in the aqueous hydrochloric acid solution as much as possible. In the heat medium flow path of the cooling water used in the cooler 6, regarding the heat medium after heat exchange with the process fluid, condensed water condensed from gaseous water used as the heat medium or used as the heat medium A measuring device 47 is provided for measuring the hydrogen ion concentration or electrical conductivity of the liquid water. Based on the measurement value of the measuring device 47, the mixing of the process fluid into the heat medium flow path of the cooler 6 is detected.

  The gas component in the process fluid extracted from the top of the quenching tower 3 is led to a chlorine drying step via a line 13 or led to a detoxification facility via a line 14. The line 13 includes a valve 33 and switches whether the process fluid is conducted to the chlorine drying process by switching the open / closed state of the valve 33. The line 14 includes a valve 34, and switches whether the process fluid can be conducted to the detoxification facility by switching the open / closed state of the valve 34.

  In the heat exchange system shown in FIG. 1, the molten salt flow path includes a first circulation path, a second circulation path, a third circulation path, and a fourth flow path. In the first circulation path, the molten salt is led from the molten salt storage drum 2 to the molten salt flow path in the multitubular fixed bed catalyst reactor 1 via the line 41, and the multitubular fixed bed catalyst reactor. 1 functions as a heat medium for exchanging heat with the process fluid. Thereafter, the molten salt is returned to the molten salt storage drum 2 via the line 42. In the second circulation path, the molten salt is led from the molten salt storage drum 2 to the heater 4 via the line 41, and the raw material gas supplied to the multitubular fixed bed catalyst reactor 1 in the heater 4 is supplied to the molten salt. Functions as a heating medium for heating. Thereafter, the molten salt is returned to the molten salt storage drum 2 via the line 43. In the third circulation path, the molten salt is led to the cooler 5 via the line 41 and functions as a heat medium for cooling the reaction product gas sent from the multi-tubular fixed bed catalyst reactor 1 in the cooler 5. To do. Thereafter, the molten salt is returned to the molten salt storage drum 2 via the line 45.

  The line 41 includes a pump 8 and circulates the molten salt in the first to third circulation paths. The line 41 includes a cooler 7 and cools the molten salt to adjust the temperature of the molten salt. In the line 41, the flow path that passes through the cooler 7 or the flow path that avoids the cooler 7 is appropriately switched so that the temperature of the molten salt becomes a desired temperature. Although the configuration of the cooler 7 is not particularly limited, the cooler 7 shown in FIG. 1 is a steam generator in which water is supplied and water is changed into steam by recovering the heat of the molten salt, and steam is discharged. . The steam discharged from the cooler 7 can be used, for example, for preliminary heating of the process fluid subjected to the reaction.

  The fourth flow path is composed of a line 46 capable of communicating the gas phase part 22 of the molten salt storage drum 2 with a detoxification facility for detoxifying hydrogen chloride and / or chlorine. Gas is discharged outside. Nitrogen gas is supplied to the gas phase part 22 of the molten salt storage drum 2 via a line 51, and the gas phase part of the molten salt channel is sealed by the nitrogen gas. By providing the line 46 for discharging the gas of the part to the outside, the nitrogen gas for sealing the gas phase part of the molten salt flow path can be discharged to the outside, for example, a harmless facility.

  Examples of the catalyst used in the hydrochloric acid oxidation reaction process include, but are not limited to, a ruthenium oxide catalyst and a chromium oxide catalyst. In the hydrochloric acid oxidation reaction process, a measuring means for constantly measuring the temperature of the catalyst layer may be provided, and the temperature of the catalyst layer can be controlled by such a measuring means so that the optimization of the reaction and the temperature runaway can be detected at an early stage. The reaction temperature, reaction pressure, and temperature control method of the catalyst layer in the multitubular fixed-bed catalyst reactor 1 are not particularly limited, but in the hydrochloric acid oxidation reaction, the heat exchange with a molten salt adjusted to a temperature of 280 to 400 ° C. is carried out to 280 to 400 ° C. It is preferable to react hydrogen chloride and oxygen in an atmosphere adjusted to a temperature of 400 ° C.

  The material of the equipment used in the heat exchange system of FIG. 1 is not particularly limited, but nickel is usually used for a portion in contact with the process gas, for example, a reaction tube of the multi-tubular fixed bed catalytic reactor 1, and a molten salt For example, carbon steel is usually used for the parts that come into contact with, for example, the jacket of the multi-tubular fixed bed catalytic reactor 1 and the molten salt storage drum 2, and the reaction temperature control and reaction heat are controlled so that the reaction temperature does not exceed about 450 ° C. Is preferably removed. Further, a fluororesin such as tantalum or Teflon (registered trademark), carbon, or the like is used for a portion of the quenching tower 3 that comes into contact with a solution composed of hydrogen chloride and water.

[Operation method of heat exchange system]
In the operation when the hydrochloric acid oxidation reaction process of the heat exchange system shown in FIG. 1 is performed, the valve 31 on the line 11 is opened, and the raw material gas is supplied to the multitubular fixed bed catalyst reactor 1. In addition, the valve 33 is opened and the valve 34 is closed so that the reaction product gas containing chlorine gas sent from the quenching tower 3 is led to the chlorine drying step via the line 13. In operation during the execution of the hydrochloric acid oxidation reaction process, mixing of the process fluid into the heat medium flow path of the cooler 6 is detected based on the measured value of the hydrogen ion concentration or electrical conductivity of the cooling water by the measuring device 47. Then, the operation stop process is performed. The operation stop process performs an operation in which one or both of a supply stop process and a mixing heat medium cooling process described below are executed simultaneously.

(Supply stop process)
In the supply stop process, when mixing of the process fluid into the heat medium flow path of the cooler 6 is detected based on the measured value of the hydrogen ion concentration or electrical conductivity of the cooling water by the measuring device 47, the valve 31 is turned on. Switching from the open state to the closed state, the supply of the raw material gas to the multitubular fixed bed catalyst reactor 1 is stopped. In addition, the valve 33 is switched from the open state to the closed state, and the valve 34 is switched from the closed state to the open state, so that the gas components sent from the quenching tower 3 are guided to the harmless equipment via the line 14. By operating in this way, even if the process fluid is mixed into the heat medium flow path, the amount of the process fluid mixed can be suppressed, which is safe, and further, the pressure in the process fluid flow path is reduced to be safe. The heat exchange system can be stopped. Further, the process fluid remaining in the quenching tower 3 from the multitubular fixed bed catalyst reactor 1 can be made harmless by the harmless equipment and can be safely treated. In the supply stop step, the circulation of the solution consisting of hydrogen chloride and water in the quenching tower 3 is preferably continued.

(Cooling process of molten salt when mixed)
In the mixing molten salt cooling step, when mixing of the process fluid into the heat medium flow path of the cooler 6 is detected based on the measured value of the hydrogen ion concentration or electric conductivity of the cooling water by the measuring device 47, The molten salt is cooled by the cooler 7 while continuing the circulation of the molten salt to the first to third circulation paths. Preferably, in the operation when the hydrochloric acid oxidation reaction process is performed, the temperature of the molten salt is maintained at 280 to 400 ° C, and in the mixed salt cooling step when mixed, the temperature of the molten salt is cooled to 200 to 250 ° C. Since the temperature of the heat exchange system as a whole can be lowered by the mixed salt cooling step at the time of mixing, various reactions can be suppressed.

  1 multi-tube fixed bed catalyst reactor, 2 molten salt storage drum, 3 quenching tower, 4 heater, 5, 6, 7 cooler, 8 pump, 11, 12, 13, 14 line through which process fluid flows, 31 33, 34 Valve, 32 Pump, 41, 42, 43, 45 Line through which molten salt flows, 47 Measuring instrument.

Claims (4)

A heat exchange system that exchanges heat without direct contact between a process fluid containing hydrogen chloride and / or chlorine and a heat medium that circulates in the heat medium flow path and is composed of gaseous or liquid water. And
A heat exchange system comprising a measuring device for measuring a hydrogen ion concentration or electrical conductivity of condensed water in which the gaseous water is condensed or the liquid water. Operation of a heat exchange system that exchanges heat without direct contact between a process fluid containing hydrogen chloride and / or chlorine and a heat medium that circulates in the heat medium flow path and is composed of gaseous or liquid water A method,
The heat exchange system includes a measuring device for measuring the hydrogen ion concentration or electrical conductivity of the condensed water in which the gaseous water is condensed or the liquid water,
A mixing detection step for detecting mixing of the process fluid into the heat medium based on the measurement value of the measuring device;
An operation method for a heat exchange system, comprising: an operation stop step for stopping operation of the heat exchange system when contamination is detected by the contamination detection step.   The operation method of the heat exchange system according to claim 2, wherein the operation stop step includes a supply stop step of stopping the supply of the process fluid into the process fluid flow path.   The shutdown step includes a detoxification treatment step when mixing all of the process fluid in the process fluid flow path to a detoxification facility that detoxifies the hydrogen chloride and / or the chlorine and releases it to the atmosphere. The operation method of the heat exchange system according to claim 2.

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