JP2008063174A - Chlorine production method, chlorine production apparatus, and heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy-saving chlorine production method, a chlorine production apparatus, and a heat exchanger in a process for producing gaseous chlorine by oxidizing a hydrogen chloride gas. <P>SOLUTION: The chlorine production method is a chlorine production method for producing gaseous chlorine by oxidizing a hydrogen chloride gas and comprises a mixed gas production step of producing a mixed gas containing chlorine and oxygen by oxidizing the hydrogen chloride gas, a chlorine purification step of introducing the mixed gas into a chlorine rectification tower 106 where the mixed gas is distilled to be separated into liquid chlorine and impurity gases, and a vaporization step of vaporizing the liquid chlorine, wherein in the vaporization step, a single heat exchanger 200 performs heat exchange between two of the heat sources used in the method for producing the liquid chlorine and the chlorine. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a chlorine production method, a chlorine production apparatus, and a heat exchanger.

  It is known that chlorine is useful as a raw material for vinyl chloride, phosgene and the like, and is obtained by oxidation of hydrogen chloride. As a method for producing chlorine used in such applications, for example, hydrochloric acid oxidation in which chlorine is produced by the hydrochloric acid oxidation method described in Soda Handbook 1998 (Non-patent Document 1) or JP-A-2005-306715 (Patent Document 1). A method for producing chlorine by a process is mentioned.

  FIG. 3.173 on page 315 of Non-Patent Document 1 discloses that purified liquid chlorine discharged from a chlorine rectification column is used for cooling an inlet gas introduced into the chlorine purification column. .

  Patent Document 1 discloses that the purified liquid chlorine discharged from the chlorine purification tower is an external refrigerant necessary for liquefying chlorine in the gas obtained in the drying step, liquid CFC precooling, and chlorine purification tower. It is disclosed that it is used for cooling the reflux liquid.

According to the said nonpatent literature 1 and patent document 1, the energy saving of the hydrochloric acid oxidation process can be aimed at by heat-exchanging the refined liquid chlorine discharged | emitted from a chlorine purification tower with another heat source. However, in the said nonpatent literature 1, since the liquid chlorine discharged | emitted from a chlorine purification tower is heat-exchanged only with 1 type of heat source, there is still room for improvement in the energy saving of hydrochloric acid oxidation process. Moreover, in the said patent document 1, since it is not disclosed concretely about heat exchange with this liquid chlorine, there also exists a problem that practical use cannot be aimed at.
JP-A-2005-306715 "Soda Handbook 1998" Japan Soda Industry Association, p314-315

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and in a process for producing gaseous chlorine by oxidizing hydrogen chloride gas, a chlorine production method and chlorine production for achieving energy saving. An apparatus and a heat exchanger are provided.

  The chlorine production method of the present invention is a chlorine production method for producing gaseous chlorine by oxidizing hydrogen chloride gas, and includes a mixed gas production step, a chlorine purification step, and a vaporization step. In the mixed gas production process, hydrogen chloride gas is oxidized to produce a mixed gas containing chlorine and oxygen. In the chlorine purification step, the mixed gas is introduced into a chlorine purification tower and separated into liquid chlorine and impurity gas by distillation. In the vaporizing step, liquid chlorine is vaporized. The vaporization step is characterized in that heat is exchanged between liquid chlorine and two kinds of heat sources used in the method for producing chlorine by one heat exchanger.

  According to the method for producing chlorine of the present invention, in the vaporization step, heat is exchanged between liquid chlorine and two kinds of heat sources with one heat exchanger, so that the liquid can be obtained without increasing the number of heat exchangers. The latent heat of vaporization of chlorine can be recovered efficiently. Therefore, energy saving can be achieved in the process of producing gaseous chlorine by oxidizing hydrogen chloride gas.

  Preferably, in the chlorine production method, the two heat sources are two heat sources selected from a mixed gas, an impurity gas, a refrigerant for cooling the impurity gas, and a heat medium used in the mixed gas production process. It is a feature.

  These heat sources require cooling in the process of oxidizing hydrogen chloride gas to produce gaseous chlorine. Therefore, in the process of producing gaseous chlorine by oxidizing hydrogen chloride gas, it is possible to further save energy by exchanging heat with liquid chlorine.

  The chlorine production apparatus of the present invention is a chlorine production apparatus that oxidizes hydrogen chloride gas to produce gaseous chlorine, and includes a mixed gas production apparatus, a chlorine purification tower, and a heat exchanger. The mixed gas production apparatus oxidizes hydrogen chloride gas to produce a mixed gas containing chlorine and oxygen. The chlorine purification tower separates the mixed gas into liquid chlorine and impurity gas by distillation. The heat exchanger includes a first heat transfer tube group that causes a first fluid used in a chlorine production apparatus to flow therein, and a second heat transfer tube that causes a second fluid used in the chlorine production apparatus to flow therein. And a cylindrical body for accommodating therein a first heat transfer tube group connected to one end and projecting inward and a second heat transfer tube group connected to the other end and projecting inward. Yes. The heat exchanger is characterized in that liquid chlorine is exchanged with the first and second fluids.

  According to the chlorine production apparatus of the present invention, heat exchange can be performed between liquid chlorine and two kinds of heat sources with one heat exchanger. Therefore, the latent heat of vaporization of liquid chlorine can be efficiently recovered without increasing the number of heat exchangers. Therefore, energy saving can be achieved in the process of producing gaseous chlorine by oxidizing hydrogen chloride gas.

  The heat exchanger of the present invention includes a first heat transfer tube group, a second heat transfer tube group, and a cylindrical body. The first heat transfer tube group causes the first fluid to flow inside. The second heat transfer tube group causes the second fluid to flow inside. The cylindrical body accommodates therein a first heat transfer tube group that is connected to one end portion and protrudes inward, and a second heat transfer tube group that is connected to the other end portion and protrudes inward. The cylindrical body includes an inlet portion that allows the third fluid to flow into the heat exchanger, and an outlet portion that allows the third fluid to flow out of the heat exchanger.

  According to the heat exchanger of the present invention, the third fluid is caused to flow into the heat exchanger, so that in one heat exchanger, the two heat sources that are the first and second fluids are simultaneously heated. Exchanges can be made. Therefore, energy saving can be achieved in the heat exchanger.

  In the above heat exchanger, preferably, the first heat transfer tube group and the second heat transfer tube group are arranged symmetrically about the center in the extending direction of the cylindrical body.

  Thereby, heat exchange with the 3rd fluid introduced outside the 1st and 2nd heat exchanger tube group and the 1st and 2nd fluid can be performed equally, respectively. Therefore, management becomes easy.

  In the heat exchanger, preferably, the length of the first heat transfer tube group and the second heat transfer tube group is less than ½ of the length in the extending direction of the cylindrical body.

  Thereby, heat exchange with the 3rd fluid introduced outside the 1st and 2nd heat exchanger tube group and the 1st and 2nd fluid can be performed equally, respectively. Therefore, management becomes easy.

  The chlorine production method, chlorine production apparatus, and heat exchanger of the present invention can save energy in the process of producing gaseous chlorine by oxidizing hydrogen chloride gas.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
With reference to FIG. 1, the heat exchanger in Embodiment 1 of this invention is demonstrated. The heat exchanger in the first embodiment includes a first heat transfer tube group 210, a second heat transfer tube group 220, and a cylindrical body 230. The first heat transfer tube group 210 causes the first fluid to flow inside. The second heat transfer tube group 220 causes the second fluid to flow inside. The cylindrical body 230 accommodates therein a first heat transfer tube group 210 connected to one end portion 231 and protruding inward, and a second heat transfer tube group 220 connected to the other end portion 232 and protruding inward. To do. The cylindrical body 230 includes an inlet portion 233 through which the third fluid flows into the heat exchanger 200 and an outlet portion 234 through which the third fluid flows out of the heat exchanger 200. FIG. 1 is a diagram showing a heat exchanger according to Embodiment 1 of the present invention, (A) is a sectional view along the direction in which the heat exchanger extends, and (B) is a heat exchanger. It is sectional drawing along the direction perpendicular | vertical to the extending direction. Note that FIG. 1B is a cross-sectional view taken along line I (B) -I (B) in FIG.

  Specifically, as shown in FIGS. 1A and 1B, the heat exchanger 200 includes a first heat transfer tube group 210, a second heat transfer tube group 220, a cylindrical body 230, 1 connection part 240 and the 2nd connection part 250 are provided.

  The first heat transfer tube group 210 causes the first fluid to flow inside. The first heat transfer tube group 210 is accommodated in the cylindrical body 230, is connected to one end 231 of the cylindrical body 230, and protrudes inward.

  The second heat transfer tube group 220 causes the second fluid to flow inside. The second heat transfer tube group 220 is accommodated in the cylindrical body 230, connected to the other end 232 of the cylindrical body 230, and protrudes inward.

  The first and second heat transfer tube groups 210 and 220 include a plurality of U-shaped heat transfer tubes connected to the upper side and the lower side of the one end 231 and the other end 232 of the cylindrical body 230.

  The first heat transfer tube group 210 and the second heat transfer tube group 220 are preferably arranged symmetrically about the center X in the direction in which the cylindrical body 230 extends (left-right direction in FIG. 1A). .

  The lengths of the first heat transfer tube group 210 and the second heat transfer tube group 220 may be less than ½ of the length in the direction in which the cylindrical body 230 extends (the left-right direction in FIG. 1A). preferable. That is, as shown in FIG. 1 (A), the first and second heat transfer tube groups 210 and 220 are arranged in respective regions divided into two regions by an axis connecting the center X in the extending direction of the cylindrical body 230. It is preferred that

  The “length of the first heat transfer tube group 210 and the second heat transfer tube group 220” refers to the inward direction of the cylindrical body 230 among the heat transfer tubes of the first and second heat transfer tube groups 210 and 220. It means the length of the longest part protruding in

  The cylindrical body 230 includes a third inlet 233 and a third outlet 234. The third inlet 233 is a member that allows the third fluid to flow into the heat exchanger 200. The third outlet 234 is a member that causes the third fluid to flow out of the heat exchanger 200. The third inlet portion 233 is preferably disposed relatively below the heat exchanger 200, and the third outlet portion 234 is preferably disposed relatively above the heat exchanger 200. This is because, when the third fluid is a liquid, the third fluid evaporates into a gas by receiving heat from the heat transfer tube groups 210 and 220 when the third fluid is a liquid. In the first embodiment, the third inlet 233 corresponds to the lowermost surface in the vertical direction of the cylindrical body 230 of the heat exchanger 200 and is provided at one location in the substantially central part of the cylindrical body 230 in the horizontal direction. . The third outlet 234 corresponds to the uppermost surface of the cylindrical body 230 of the heat exchanger 200 in the vertical direction, and is provided at one location in the substantially central part of the cylindrical body 230 in the horizontal direction.

  The first connection portion 240 is connected to one end portion 231 of the cylindrical body 230. The second connection part 250 is connected to the other end 232 of the cylindrical body 230. The first and second connection portions 240 and 250 include first and second inlet portions 241 and 251, first and second inlet inflow portions 242 and 252, and first and second outlet outflow portions 243. 253 and first and second outlet portions 244,254. The first and second inlet portions 241 and 251 allow the first and second fluids to flow into the first and second heat transfer tube groups 210 and 220. The first and second inlet inflow portions 242 and 252 temporarily retain (or flow) the first and second fluids flowing in from the first and second inlet portions 241 and 251, and thereby This is a member forming a region for flowing into the heat transfer tube groups 210 and 220. The first and second outlet outlets 243 and 253 form a region for temporarily retaining (flowing) the first and second fluids flowing out from the first and second heat transfer tube groups 210 and 220. It is a member. The first and second outlet portions 244 and 254 cause the first and second fluids flowing out from the first and second outlet outlet portions 243 and 253 to flow out of the heat exchanger 200.

  Next, the operation of the heat exchanger 200 in the first embodiment will be described. First, the third fluid is caused to flow into the heat exchanger 200. Then, the first fluid is caused to flow into the first heat transfer tube group 210. Then, the second fluid is caused to flow into the second heat transfer tube group 220.

  Specifically, the third fluid is caused to flow into the heat exchanger 200 from the third inlet 233, and the third fluid is stored in the heat exchanger 200 at a certain liquid level. Further, the first and second heat transfer tube groups 210 and 220 are connected to the first and second inlet portions 241 and 251 and the first and second inlet inflow portions 242 and 252. Let the fluid flow. Then, the first and second fluids are caused to flow out of the heat exchanger 200 through the first and second outlet outlet portions 243 and 253 and the first and second outlet portions 244 and 254. Thereby, heat exchange between the first and second fluids and the third fluid is performed via the heat transfer tube groups 210 and 220. When heat exchange is performed, the third fluid evaporates and gasifies inside the heat exchanger 200 and flows out of the heat exchanger 200 from the third outlet portion 234.

  The first and second fluids may flow in the first and second heat transfer tube groups 210 and 220 at the same time, or only one of them may flow temporarily as necessary. good. In addition, the first, second, and third fluids that flow into the heat exchanger 200 are not particularly limited as long as they are different types of fluids.

  As described above, according to the heat exchanger 200 in the first embodiment, the first heat transfer tube group 210 that causes the first fluid to flow inside, and the second heat transfer that causes the second fluid to flow inside. The heat tube group 220, the first heat transfer tube group 210 connected to the one end 231 and protruding inward, and the second heat transfer tube group 220 connected to the other end 232 and protruding inward are accommodated therein. The cylindrical body 230 is a heat exchanger including an inlet part (third inlet part 233) for allowing the third fluid to flow into the heat exchanger 200, and the third fluid for heat exchange. And an outlet part (third outlet part 234) for flowing out from the vessel 200. By causing the third fluid to flow into the heat exchanger 200, the first and second fluids flowing inside the first and second heat transfer tube groups 210 and 220 in one heat exchanger 200. Two kinds of heat sources and the third fluid can be subjected to heat exchange at the same time. Therefore, energy saving can be achieved in the heat exchanger 200.

  In the heat exchanger, preferably, the first heat transfer tube group 210 and the second heat transfer tube group 220 are arranged symmetrically about the center X in the extending direction of the cylindrical body 230. . Thus, heat exchange between the third fluid introduced to the outside of the first and second heat transfer tube groups 210 and 220 and the first and second fluids can be performed equally. Therefore, management of heat exchange in the heat exchanger 200 is facilitated.

  In the heat exchanger, preferably, the lengths of the first heat transfer tube group 210 and the second heat transfer tube group 220 are less than ½ of the length in the direction in which the cylindrical body 230 extends. Thus, heat exchange between the third fluid introduced to the outside of the first and second heat transfer tube groups 210 and 220 and the first and second fluids can be performed equally. Therefore, management of heat exchange in the heat exchanger 200 is facilitated.

(Embodiment 2)
With reference to FIG. 1 and FIG. 2, the chlorine manufacturing apparatus in embodiment of this invention is demonstrated. The chlorine production apparatus in the second embodiment is a chlorine production apparatus that oxidizes hydrogen chloride gas to produce gaseous chlorine. In addition, FIG. 2 is a figure for demonstrating the chlorine manufacturing apparatus in embodiment of this invention.

  As shown in FIG. 2, the chlorine production apparatus includes a mixed gas production apparatus, a chlorine purification tower 106, and a heat exchanger 200. The mixed gas production apparatus oxidizes hydrogen chloride gas to produce a mixed gas containing chlorine and oxygen. The chlorine purification tower 106 separates the mixed gas into liquid chlorine and impurity gas by distillation. The heat exchanger 200 includes a first heat transfer tube group that causes the first fluid used in the chlorine production apparatus to flow therein, and a second heat transfer pipe that causes the second fluid used in the chlorine production apparatus to flow inside. A heat tube group, a first heat transfer tube group, a second heat transfer tube group, a first heat transfer tube group connected to one end and projecting inward, and a second heat tube connected to the other end and projecting inward. And a cylindrical body that accommodates the heat transfer tube group therein. The heat exchanger 200 is characterized in that liquid chlorine is exchanged with the first and second fluids.

  The chlorine production apparatus in the second embodiment includes a pretreatment tower 101, a reactor 102, an absorption tower 103, a drying tower 104, a mixed gas production apparatus including a compressor 105, a chlorine purification tower 106, A liquid salt drum 107 and a heat exchanger 200 are provided.

  Specifically, the pretreatment tower 101 removes impurities in a gas containing hydrogen chloride, which is a chlorine raw material. The pretreatment tower 101 is filled with, for example, activated carbon or zeolite. Note that the pretreatment tower 101 may be omitted.

  The reactor 102 oxidizes the gas containing hydrogen chloride from which impurities have been removed in the pretreatment tower 101 with a gas containing oxygen to generate a gas mainly composed of chlorine, water, unreacted hydrogen chloride, and unreacted oxygen. To do. The reactor 102 is filled with a catalyst containing, for example, ruthenium and / or a ruthenium compound, and a gas containing oxygen is introduced.

  The absorption tower 103 collects a solution mainly composed of hydrogen chloride and water from the gas mainly composed of chlorine, water, unreacted hydrogen chloride and unreacted oxygen obtained in the reactor 102, and unreacted with chlorine. A mixed gas mainly containing oxygen is generated. Specifically, in the absorption tower 103, water and / or hydrochloric acid water is introduced. Then, a gas mainly composed of chlorine, water, unreacted hydrogen chloride and unreacted oxygen is brought into contact with water and / or hydrochloric acid and / or cooled.

  The drying tower 104 removes moisture in the mixed gas. The drying tower 104 is introduced or filled with, for example, sulfuric acid, calcium chloride, magnesium perchlorate, zeolite, or the like. The drying tower 104 is preferably introduced with sulfuric acid because it can be easily discharged after use.

  The compressor 105 compresses the mixed gas from which moisture has been removed and sends it to the chlorine purification tower 106. Any compressor 105 can be used. The compressor 105 may be omitted.

  The chlorine purification tower 106 separates the mixed gas into liquid chlorine and impurity gas by distillation. The liquid salt drum 107 stores the purified liquid chlorine.

  As the heat exchanger 200, the heat exchanger 200 of Embodiment 1 shown in FIGS. 1A and 1B is used. The third fluid in the first embodiment is chlorine generated in the chlorine purification tower 106 in the second embodiment. Part or all of the liquid chlorine introduced into the heat exchanger 200 is vaporized by the heat exchanger 200.

  In the heat exchanger 200, liquid chlorine is introduced as the third fluid. Therefore, in order to reduce the risk of chlorine leakage, heat exchange with two types of heat sources (first and second fluids) is performed with one heat exchanger. It is set as the structure which performs. Specifically, it is the same as the heat exchanger 200 in the first embodiment.

  The chlorine production apparatus may include a vaporizer that vaporizes liquid chlorine in addition to the heat exchanger 200. For example, similar to the heat exchanger 200 capable of exchanging heat with two kinds of heat sources between the heat exchanger 200 and the chlorine purification tower 106 and / or between the heat exchanger 200 and a pipe fed as product chlorine. And / or one or more heat exchangers capable of exchanging heat with one kind of heat source.

  As described above, the chlorine production apparatus according to Embodiment 2 of the present invention is a chlorine production apparatus that oxidizes hydrogen chloride gas to produce gaseous chlorine, and oxidizes hydrogen chloride gas. A mixed gas production apparatus for producing a mixed gas containing chlorine and oxygen, a chlorine purification tower 106 for separating the mixed gas into liquid chlorine and impurity gas by distillation, and a first fluid used in the chlorine production apparatus. The first heat transfer tube group 210 that flows inside, the second heat transfer tube group 220 that flows the second fluid used in the chlorine production apparatus, and one end 231 are connected and protrudes inward. A heat exchanger 200 including a first heat transfer tube group 220 and a cylindrical body 230 that accommodates the second heat transfer tube group 220 connected to the other end 232 and projecting inward. In 200, liquid chlorine and first Beauty and the second fluid is characterized in that it is heat-exchanged. Thereby, heat exchange can be performed between liquid chlorine and two kinds of heat sources with one heat exchanger 200. Therefore, the latent heat of vaporization of liquid chlorine can be efficiently recovered without increasing the number of heat exchangers. Therefore, energy saving can be achieved in the process of producing gaseous chlorine by oxidizing hydrogen chloride gas.

  Further, since the heat exchanger 200 can exchange heat with two types of heat sources with one heat exchanger, it does not require the space of the two heat exchangers necessary for exchanging heat with the two types of heat sources. Therefore, even in a case where the installation space is narrow and heat exchange with only one conventional heat source is possible, two heat sources can be obtained by installing one heat exchanger 200 in the second embodiment. And heat exchange. Therefore, energy saving can be achieved. In addition, the entire chlorine production apparatus can be reduced in size.

  Furthermore, even if liquid chlorine having the property of being easily corroded is introduced into the heat exchanger 200, the inside inspection is easy and the maintenance is easy. Moreover, since the structure is simple, it is easy to manufacture. Therefore, the chlorine production apparatus in the second embodiment can be put into practical use.

(Embodiment 3)
With reference to FIG. 1 and FIG. 2, the manufacturing method of chlorine in Embodiment 3 of this invention is demonstrated. The chlorine production method in Embodiment 3 is a chlorine production method (catalytic gas phase oxidation method) in which gaseous chloride is produced by oxidizing hydrogen chloride gas. In the third embodiment, chlorine is manufactured using the chlorine manufacturing apparatus in the second embodiment.

  The method for producing chlorine in Embodiment 3 basically includes a reaction process, an absorption process, a drying process, a purification process, and a vaporization process. The mixed gas production process for producing a mixed gas containing chlorine and oxygen by oxidizing hydrogen chloride gas includes a reaction process, an absorption process, a drying process, and a compression process, and preferably a pretreatment process. In addition.

<Pretreatment process>
First, in the pretreatment tower 101, it is preferable to carry out a pretreatment process for removing impurities of a gas containing hydrogen chloride which is a raw material of chlorine. In the pretreatment step, for example, a gas containing hydrogen chloride is introduced into the pretreatment tower, and impurities such as aromatic compounds, chlorinated aliphatic hydrocarbons, chlorinated aromatic hydrocarbons, and high-boiling inorganic compounds are previously removed. . As the pretreatment method, generally known methods can be employed, and examples thereof include adsorption treatment with activated carbon, zeolite, and the like. Further, a gas containing hydrogen chloride may be absorbed in water or dilute hydrochloric acid, and hydrogen chloride gas may be diffused from the obtained absorbent to remove an inert gas component or a high-boiling point component (for example, JP 2000-34105 A). ). Note that the pretreatment process may be omitted.

  As the gas containing hydrogen chloride, any gas containing hydrogen chloride generated in the thermal decomposition reaction or combustion reaction of a chlorine compound, the phosgenation reaction or chlorination reaction of an organic compound, the combustion of an incinerator, or the like can be used. The concentration of hydrogen chloride in the gas containing hydrogen chloride is 10% by volume or more, preferably 50% by volume or more, and more preferably 80% by volume or more. When the concentration of hydrogen chloride is lower than 10% by volume, the concentration of oxygen in the impurity gas mainly composed of unreacted oxygen obtained in the purification process described later is low, and is supplied to the reaction process in the circulation process described later. In some cases, it is necessary to reduce the amount of the impurity gas.

  Components other than hydrogen chloride in the gas containing hydrogen chloride include chlorinated aromatic hydrocarbons such as orthodichlorobenzene and monochlorobenzene, aromatic hydrocarbons such as toluene and benzene, and vinyl chloride and 1,2-dichloroethane. , Chlorinated hydrocarbons such as methyl chloride, chlorine tetrachloride, ethyl chloride, and hydrocarbons such as methane, acetylene, ethylene, propylene, and nitrogen, argon, carbon dioxide, carbon monoxide, phosgene, hydrogen, carbonyl sulfide, sulfide Examples include inorganic gases such as hydrogen and sulfur dioxide. In the reaction of hydrogen chloride and oxygen, chlorinated aromatic hydrocarbons and chlorinated hydrocarbons are oxidized to carbon dioxide and water, carbon monoxide is oxidized to carbon dioxide, and phosgene is oxidized to carbon dioxide and chlorine. .

<Reaction process>
Next, as shown in FIG. 1, a gas containing hydrogen chloride is oxidized with a gas containing oxygen in a reactor 102 under a catalyst to contain chlorine, water, unreacted hydrogen chloride, and unreacted oxygen as main components. A reaction step for obtaining a gas is performed.

In the reaction step (S12), a gas containing oxygen is introduced into the reactor 102 together with the gas containing hydrogen chloride from which impurities have been removed in the pretreatment step (S11). In the reactor 102, hydrogen chloride is oxidized by oxygen according to the following reaction formula to generate chlorine.
4HCl + O ₂ → 2Cl ₂ + 2H ₂ O
As the gas containing oxygen, oxygen or air is used. Preferably, the oxygen concentration is 80% by volume or more, more preferably 90% by volume or more. When the oxygen concentration is less than 80% by volume, the oxygen concentration in the impurity gas mainly composed of unreacted oxygen obtained in the purification step described later is low, and the oxygen gas supplied to the reaction step in the circulation step described later is supplied. It may be necessary to reduce the amount of impurity gas. A gas containing oxygen having an oxygen concentration of 80% by volume or more can be obtained by an ordinary industrial method such as an air pressure swing method or a cryogenic separation. Examples of components other than hydrogen chloride in a gas containing oxygen include nitrogen (N ₂ ) and argon (Ar).

  Although the theoretical molar amount of oxygen with respect to 1 mol of hydrogen chloride is 0.25 mol, it is preferable to supply more than the theoretical amount, and it is further preferable to supply 0.25 to 2 mol of oxygen with respect to 1 mol of hydrogen chloride. preferable. If the amount of oxygen is too small, the conversion rate of hydrogen chloride may be low. On the other hand, if the amount of oxygen is excessive, it may be difficult to separate generated chlorine and unreacted oxygen.

  In the reaction step, it is preferable to oxidize hydrogen chloride with oxygen in the presence of a catalyst containing ruthenium and / or a ruthenium compound to obtain a gas mainly composed of chlorine, water, unreacted hydrogen chloride and unreacted oxygen. By using ruthenium and / or a ruthenium compound as a catalyst, troubles of clogging of piping due to volatilization or scattering of the catalyst component can be prevented, and a treatment process for the volatilized or scattered catalyst component becomes unnecessary. Furthermore, since chlorine can be produced at a more advantageous temperature from the viewpoint of chemical equilibrium, subsequent steps such as an absorption step, a drying step and a purification step, which will be described later, can be simplified, and equipment costs and operation costs can be suppressed low.

  Examples of the catalyst containing ruthenium and / or ruthenium compound include known catalysts (for example, JP-A-9-67103, JP-A-10-182104, JP-A-10-194705, JP-A-10-338502). And those described in JP-A-11-180701.

  In the reaction step, it is preferable to generate chlorine gas by reacting hydrogen chloride gas with oxygen gas using a catalyst containing ruthenium oxide. When a catalyst containing ruthenium oxide is used, there is an advantage that the conversion rate of hydrogen chloride is remarkably improved. The content of ruthenium oxide in the catalyst is preferably in the range of 0.1 to 20% by mass. If the amount of ruthenium oxide is less than 0.1% by mass, the catalytic activity may be low and the conversion rate of hydrogen chloride may be low. On the other hand, if the amount of ruthenium oxide is more than 20% by mass, the catalyst price is low. May be higher. The conversion rate of hydrogen chloride is preferably 85% or more.

  In particular, for example, as described in JP-A-10-338502, the content of ruthenium oxide is 0.1 to 20% by mass, and the center diameter of ruthenium oxide is 1.0 to 10.0 nanometers. A supported ruthenium oxide catalyst or a ruthenium oxide composite oxide type catalyst is also preferably used.

  The catalyst used in the reaction step (S12) is preferably used by being supported on a carrier such as silicon dioxide, graphite, rutile type or anatase type titanium dioxide, zirconium dioxide, or aluminum oxide. In particular, it is preferable to use ruthenium oxide supported on a carrier selected from these compounds.

  As a reaction method of the reaction step, for example, a fixed bed gas phase circulation method using a fixed bed reactor can be applied. As the fixed-bed reactor, for example, a method in which temperature control of at least two reaction zones among the reaction zones is performed by a heat exchange method by a method described in JP-A-2000-272907 can be used. In such a reactor with two or more reaction zones, two first-stage reaction zones are prepared. Before the second and subsequent stages are poisoned, the first stage is switched alternately. If used, problems can be substantially avoided. However, preparing two expensive reactors is also disadvantageous from the viewpoint of cost.

  Examples of the fixed bed type reactor include a single fixed bed or a plurality of fixed bed reaction tubes connected in series and having a jacket portion outside the reaction tube. The temperature in the reaction tube is controlled by the heat medium in the jacket portion. The reaction heat generated by the reaction can be recovered by generating steam through the heat medium. Examples of the heat medium include a molten salt, an organic heat medium, and a molten metal, but a molten salt is preferable in terms of heat stability and ease of handling. Examples of the composition of the molten salt include a mixture of 50% by weight of potassium nitrate and 50% by weight of sodium nitrite, and a mixture of 53% by weight of potassium nitrate, 40% by weight of sodium nitrite and 7% by weight of sodium nitrate. Examples of the material used for the reaction tube include metal, glass, and ceramic. Examples of the metal material include Ni, SUS316L, SUS310, SUS304, Hastelloy B, Hastelloy C, and Inconel. Among them, Ni is preferable, and Ni having a carbon content of 0.02% by weight or less is particularly preferable.

  Moreover, it is preferable that the sulfur component density | concentration in the inlet part of the reactor 102 is 1000 volppb or less, and it is more preferable that it is 500 volppb or less. If the sulfur component concentration at the inlet of the reactor 102 exceeds 1000 volppb, it is possible to avoid sulfur poisoning by replacing only the poisoned catalyst instead of the entire catalyst. This is because there is a possibility that a very complicated operation may be required. If the sulfur component concentration at the inlet portion of the reactor 102 is 1000 volppb or less, it can be operated substantially without any problem, and a sulfur component concentration that is much higher than the conventional one can be tolerated. It is not necessary to completely remove the sulfur component with complicated operations. Therefore, the operation can be continued for a long time without refilling the catalyst. The sulfur component concentration at the inlet of the reactor 102 can be measured, for example, by gas chromatography.

<Absorption process>
Next, in the absorption tower 103, the gas mainly composed of chlorine, water, unreacted hydrogen chloride and unreacted oxygen obtained in the reaction step is brought into contact with water and / or hydrochloric acid water, and / or By performing cooling, a solution containing hydrogen chloride and water as main components is collected, and an absorption step is performed to obtain a mixed gas containing chlorine and unreacted oxygen as main components. In the absorption step, the contact temperature is 0 to 100 ° C. and the pressure is 0.05 to 1 MPa. The concentration of hydrochloric acid to be contacted is preferably 25% by weight or less. In order to prevent precipitation of chlorine hydrate, it is preferable to employ the method described in JP-A-2003-261306.

  The obtained solution is used as it is or after removing chlorine contained in the solution by heating and / or bubbling with an inert gas such as nitrogen, and then adjusting the pH of the electrolytic cell, neutralizing boiler field water, and aniline. It can be used as a raw material for condensation transition reaction of formalin, hydrochloric acid water electrolysis, food addition and the like. Further, as described in FIG. 3.173 of Soda Handbook 1998, p315, all or part of hydrochloric acid is diffused to obtain HCl gas, and the chlorine yield as a reaction raw material can be increased. It is also possible to reduce the yield of chlorine to almost 100% by removing water from the residual hydrochloric acid after release by the method described in JP-A-139305.

<Drying process>
Next, a drying step for obtaining a dried mixed gas is performed by removing moisture in the mixed gas obtained in the absorption step. The moisture in the gas after the drying step is 0.5 mg / l or less, preferably 0.1 mg / l or less. Examples of the compound that removes moisture in the mixed gas include sulfuric acid, calcium chloride, magnesium perchlorate, and zeolite. Among them, sulfuric acid is preferable because it can be easily discharged after use. As a method for removing moisture in the mixed gas, there is a method in which a mixed gas mainly composed of chlorine and unreacted oxygen obtained in the absorption step is brought into contact with sulfuric acid.

  In the drying step, the concentration of sulfuric acid added is preferably 90% by weight or more. If the sulfuric acid concentration is less than 90% by weight, water in the mixed gas may not be sufficiently removed. The contact temperature is 0 to 80 ° C. and the pressure is 0.05 to 1 MPa.

  When sulfuric acid is used as the desiccant, it is preferable to remove the sulfuric acid mist immediately after the drying step. For example, a blink eliminator or a method described in JP-A No. 2003-181235 can be applied.

<Compression process>
Next, a step of compressing the mixed gas by introducing the dried mixed gas obtained in the drying step into the compressor 105 is performed.

<Chlorine purification process>
Next, a mixed gas is introduced into the chlorine refining tower 106, and a chlorine refining process for separating liquid chlorine and impurity gas by distillation is performed. In the chlorine refining step, liquid chlorine is obtained by separating the dried mixed gas obtained in the drying step into liquid chlorine mainly composed of chlorine and impurity gas mainly composed of unreacted oxygen.

  As a method of separating the liquid or gas mainly containing chlorine and the gas mainly containing unreacted oxygen, a method of compressing and / or cooling and / or a known method (for example, JP-A-3-262514). And Japanese National Publication No. 11-500954). For example, by compressing and / or cooling the mixed gas obtained in the drying step, the liquid chlorine is separated from the impurity gas mainly composed of unreacted oxygen. The liquefaction of chlorine is performed within a range where chlorine specified by pressure and temperature can exist in a liquid state. The lower the temperature, the lower the compression pressure, so the compression power can be reduced. However, industrially, due to problems with equipment, the compression pressure and cooling temperature take into account the optimal economic conditions within this range. Can be decided. In normal operation, the compression pressure for liquefaction of chlorine is 0.5 to 5 MPa, and the cooling temperature is −70 to 40 ° C.

  Then, the liquid chlorine purified by the chlorine purification process is stored in the liquid salt drum 107. On the other hand, the impurity gas separated by the chlorine purification process is discharged. At this time, it is preferable to discharge the impurity gas from the top of the chlorine purification tower 106. Since the impurity gas is mainly composed of unreacted oxygen gas, its boiling point is lower than that of chlorine. Therefore, since the distilled impurities become gas, the impurity gas is discharged from the top of the chlorine purification tower 106.

<Vaporization process>
Next, the vaporization process which vaporizes the liquid chlorine obtained by a chlorine purification process and manufactures gaseous chlorine is implemented. In the vaporization step, heat is exchanged between liquid chlorine and two types of heat sources used in the chlorine production method using one heat exchanger 200. In the vaporization step in the third embodiment, the heat exchanger 200 in the first embodiment is used.

  Specifically, as shown in FIGS. 1 (A) and 1 (B), a part or all of the liquid chlorine staying in the liquid salt drum 107 from the third inlet 233 of the heat exchanger 200. Is introduced into the heat exchanger 200. In addition, as shown in FIG. 2, a chilled water stock solution that is a raw material of chilled water flows into the first heat transfer tube group 210 of the heat exchanger 200 as a first fluid to obtain chilled water. The mixed gas compressed by the compressor 105 flows into the second heat transfer tube group 220 of the heat exchanger 200 as the second fluid.

  Inside the heat exchanger 200, the liquid chlorine staying below exchanges heat with the first and second fluids flowing through the first and second heat transfer tube groups 210 and 220, and the liquid chlorine Part or all of it becomes gaseous chlorine.

  In the present specification, “two types of heat sources” mean two different types of media among the media used in the process of producing chlorine.

  The two types of heat sources that are the first and second fluids introduced into the heat exchanger 200 are not particularly limited, but include a mixed gas, a refrigerant for cooling the impurity gas, and a heat medium used in the mixed gas manufacturing process. The selected two heat sources are preferable. As the mixed gas, it is more preferable to use a mixed gas after the drying process because it contains less moisture, and it is even more preferable to use a mixed gas that is further compressed and discharged by the compressor 105 after the drying process. The impurity gas includes a non-condensed gas discharged as impurities from the chlorine purification tower 106 by distillation, and a condensed gas mainly composed of chlorine to which the impurity gas is refluxed by condensation. The condensed gas is a condensed liquid. It may be included. The impurity gas is more preferably a tower top gas discharged from the top of the chlorine purification tower 106. Moreover, the refrigerant | coolant for cooling impurity gas is a cooling water etc., for example. In addition, examples of the heat medium used in the mixed gas production process include liquid chlorofluorocarbon, cooling water, circulating water, hot water, and chilled water. These heat media are used, for example, for cooling a material whose temperature rises in the process (for example, chilled water used for cooling the mixed gas discharged from the compressor 105).

  In the vaporization step, before and after liquid chlorine is introduced into the heat exchanger 200, a heat exchanger similar to the heat exchanger 200 capable of exchanging heat with two types of heat sources and / or heat exchange capable of exchanging heat with one type of heat source. It may further include a step of vaporizing liquid chlorine with a vessel.

  Gaseous chlorine obtained by vaporizing liquid chlorine in the vaporization step is sent as product chlorine.

<Circulation process>
In Embodiment 3, a step of supplying a part or all of the impurity gas mainly composed of unreacted oxygen obtained in the chlorine purification step to the reaction step is performed. In the method for producing chlorine in the third embodiment, when the impurity gas containing sulfuric acid mist is circulated in the reaction step, the sulfur component concentration at the inlet of the reactor 102 is 1000 volppb or less as described above. Is preferred. Note that the circulation step may be omitted.

<Detoxification process>
In the chlorine production method according to Embodiment 3, the impurity gas mainly containing unreacted oxygen obtained in the chlorine purification process or the impurity gas not supplied to the reaction process in the circulation process is contained in the impurity gas. After removing, drain out of the system. In addition, the abatement process may be omitted.

  As a method for detoxifying chlorine, an impurity gas is an alkali metal hydroxide aqueous solution, an alkali metal thiosulfate aqueous solution, an aqueous solution in which an alkali metal sulfite and an alkali metal carbonate are dissolved, or an alkali metal sulfite. And an aqueous solution in which an alkali metal carbonate is dissolved, or an aqueous solution in which an alkali metal hydroxide and an alkali metal sulfite are dissolved, and a known method for separating and recovering chlorine in a gas No. 3-262514, Japanese Patent Laid-Open No. 10-25102, and Japanese Patent Laid-Open No. 11-500954).

  As described above, according to the method for producing chlorine in Embodiment 3 of the present invention, a chlorine production method for producing gaseous chlorine by oxidizing hydrogen chloride gas, which comprises oxidizing hydrogen chloride gas A mixed gas production process for producing a mixed gas containing chlorine and oxygen, a chlorine purification process for introducing the mixed gas into the chlorine purification tower 106 and separating it into liquid chlorine and impurity gas by distillation, and vaporizing the liquid chlorine The vaporization step is characterized in that heat exchange is performed between liquid chlorine and two types of heat sources used in the method for producing chlorine by one heat exchanger 200. In the vaporization step in the third embodiment, heat exchange is performed between liquid chlorine and two types of heat sources in one heat exchanger 200, so that the latent heat of vaporization of liquid chlorine can be efficiently recovered without increasing the number of heat exchangers. . Therefore, energy saving can be achieved in the process of producing gaseous chlorine by oxidizing hydrogen chloride gas.

  In the process of the third embodiment, the heat exchanger 200 used in the vaporization step can recover heat as high as 80% or more of the latent heat of evaporation of liquid chlorine that is the third fluid.

  Preferably, in the chlorine production method, the two heat sources are two heat sources selected from a mixed gas, a refrigerant for cooling the impurity gas, and a heat medium used in the mixed gas production process. . These heat sources require cooling in the process of oxidizing hydrogen chloride gas to produce gaseous chlorine. Therefore, in the process of producing gaseous chlorine by oxidizing hydrogen chloride gas, it is possible to further save energy by exchanging heat with liquid chlorine.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

It is a figure which shows the heat exchanger in Embodiment 1 of this invention, (A) is sectional drawing along the direction where a heat exchanger is extended, (B) is perpendicular | vertical to the direction where a heat exchanger is extended. It is sectional drawing along a direction. It is a figure for demonstrating the manufacturing apparatus of the chlorine in Embodiment 2 of this invention.

Explanation of symbols

  101 Pretreatment Tower, 102 Reactor, 103 Absorption Tower, 104 Drying Tower, 105 Compressor, 106 Chlorine Purification Tower, 107 Liquid Salt Drum, 200 Heat Exchanger, 210 First Heat Transfer Tube Group, 220 Heat Transfer Tube Group, 230 Cylindrical cylinder, 231 one end, 231 one end, 232 other end, 233 inlet, 234 outlet, 240 first connection, 250 second connection, 241,251 inlet, 242,252 inlet Inflow part, 243,253 Outlet outflow part, 244,254 Outlet part, X center.

Claims (6)

A chlorine production method for producing gaseous chlorine by oxidizing hydrogen chloride gas,
A mixed gas production process for producing a mixed gas containing chlorine and oxygen by oxidizing hydrogen chloride gas;
A chlorine purification step of introducing the mixed gas into a chlorine purification tower and separating it into liquid chlorine and impurity gas by distillation;
A vaporizing step for vaporizing the liquid chlorine,
In the vaporization step, heat exchange is performed between the liquid chlorine and two kinds of heat sources used in the chlorine production method using one heat exchanger.   The two kinds of heat sources are two kinds of heat sources selected from the mixed gas, the impurity gas, a refrigerant for cooling the impurity gas, and a heat medium used in the mixed gas manufacturing process. The method for producing chlorine according to claim 1. A chlorine production apparatus that oxidizes hydrogen chloride gas to produce gaseous chlorine,
A mixed gas production apparatus for producing a mixed gas containing chlorine and oxygen by oxidizing hydrogen chloride gas;
A chlorine purification tower for separating the mixed gas into liquid chlorine and impurity gas by distillation;
A first heat transfer tube group that causes the first fluid used in the chlorine production apparatus to flow inside; a second heat transfer tube group that causes the second fluid used in the chlorine production apparatus to flow inside; Heat exchange including the first heat transfer tube group that is connected to one end portion and protrudes inward and the cylindrical body that accommodates the second heat transfer tube group that is connected to the other end portion and protrudes inward. Equipped with
In the said heat exchanger, the said chlorine and the said 1st and 2nd fluid are heat-exchanged, The manufacturing apparatus of chlorine characterized by the above-mentioned. A first heat transfer tube group for flowing a first fluid therein;
A second heat transfer tube group for flowing a second fluid therein;
A heat provided with a cylindrical body that houses the first heat transfer tube group connected to one end and projecting inward and the second heat transfer tube group connected to the other end and projecting inward. An exchanger,
The cylindrical body includes an inlet portion for allowing a third fluid to flow into the heat exchanger, and an outlet portion for allowing the third fluid to flow out of the heat exchanger.   5. The heat exchange according to claim 4, wherein the first heat transfer tube group and the second heat transfer tube group are arranged symmetrically about the center in the extending direction of the cylindrical body. vessel.   The length of the said 1st heat exchanger tube group and the said 2nd heat exchanger tube group is less than 1/2 of the length in the extending direction of the said cylindrical body, The Claim 4 or 5 characterized by the above-mentioned. Heat exchanger.

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