CN111943804B - Methyl chloride synthesis reaction heat gradient comprehensive utilization process - Google Patents
Methyl chloride synthesis reaction heat gradient comprehensive utilization process Download PDFInfo
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- CN111943804B CN111943804B CN202010736518.7A CN202010736518A CN111943804B CN 111943804 B CN111943804 B CN 111943804B CN 202010736518 A CN202010736518 A CN 202010736518A CN 111943804 B CN111943804 B CN 111943804B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
- C07C17/16—Preparation of halogenated hydrocarbons by replacement by halogens of hydroxyl groups
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/38—Separation; Purification; Stabilisation; Use of additives
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/584—Recycling of catalysts
Abstract
The invention discloses a chloromethane synthesis reaction heat gradient comprehensive utilization process. The high-temperature synthesis gas discharged from the methyl chloride synthesis kettle is subjected to heat exchange through a primary vaporizer, a secondary vaporizer and a water cooler in sequence, unreacted components (hydrogen chloride or methanol) in reaction products are recycled, and liquid methanol is vaporized, so that the consumption of public works is greatly reduced. Compared with the prior art, the process realizes cascade utilization of heat of the high-temperature synthesis gas, greatly reduces consumption of process steam and circulating water, and reduces material consumption by recycling unreacted components. On the other hand, the process can better adapt to various working conditions deviating from the design point, such as reaction speed fluctuation, methanol or hydrogen chloride feeding quantity fluctuation, gas phase composition temperature fluctuation and the like, has high automation degree and strong reliability, and is easy for industrial application.
Description
Technical Field
The invention belongs to the field of chloromethane synthesis, and particularly relates to a technology for gradient comprehensive utilization of chloromethane synthesis reaction heat.
Background
Methyl chloride is an important raw material for products such as organic silicon, pesticides and the like. At present, the chloromethane synthesis method mainly comprises a homogeneous gas phase method, a gas-solid catalysis method and a gas-liquid method. Wherein, the gas-liquid method has mild reaction conditions and high reaction selectivity, and is most widely applied in the actual production process. However, in the conventional gas-liquid process, the raw material methanol is usually vaporized by low-pressure steam heating and then enters a methyl chloride synthesis kettle together with hydrogen chloride gas to react under the catalysis of zinc chloride solution to generate methyl chloride. Cooling the high-temperature synthesis gas (about 150 ℃) discharged from the reaction kettle to 30-40 ℃ by using circulating water, and then entering a downstream purification section. The consumption of low-pressure steam and circulating cooling water in the production process is very large. Chinese patents CN206308285U and CN207347430U provide a device for heating methanol by waste heat of a methyl chloride synthesis kettle, respectively, and energy coupling is realized by heat exchange between synthesis gas and liquid methanol, thereby reducing the consumption of public works. However, the above device has the disadvantages that on the one hand, complete vaporization of methanol under fluctuating conditions cannot be guaranteed, and on the other hand, the method does not take into account the problems of synthesis gas condensate and recovery of liquid catalyst carried over due to gas entrainment. In addition, the synthesis gas in the device adopts first-stage gas-liquid separation, the condensate amount cannot be controlled, process conditions are limited, the condensate cannot be completely returned to the kettle for reaction, and if the condensate recycling is considered, the problem of catalyst loss also exists.
Disclosure of Invention
The invention aims to provide a methyl chloride synthesis reaction heat gradient comprehensive utilization process. The method provided by the invention can be used for carrying out cascade utilization on the heat of the high-temperature synthesis gas, greatly reduces the consumption of public works in a chloromethane synthesis section, and simultaneously can ensure that the methanol is completely vaporized under the fluctuation working condition. On the other hand, the invention can effectively control the temperature of the reactor, prevent the temperature runaway phenomenon and ensure the production safety. In addition, the method can also improve the conversion rate in the reaction process and reduce the material consumption in the reaction process.
The technical scheme of the invention is as follows: key equipment of the process comprises a primary vaporizer, a secondary vaporizer, a superheater, a primary gas-liquid separator, a secondary gas-liquid separator, a tertiary gas-liquid separator, a water cooler and a reaction liquid recovery tank.
The process is implemented by the following steps:
1) raw material liquid methanol is divided into two parts from a tank area and respectively enters a first-stage vaporizer and a second-stage vaporizer for heat exchange;
2) the high-temperature synthesis gas comes from a methyl chloride synthesis kettle, firstly enters a first-stage vaporizer, exchanges heat with liquid methanol in the first-stage vaporizer, the methanol out of the first-stage vaporizer is completely vaporized and sent to a methanol feeding working section, the synthesis gas out of the first-stage vaporizer is in a gas-liquid two-phase state, and enters a first-stage gas-liquid separation tank;
3) in the first-stage gas-liquid separation tank, liquid mainly comprises unreacted materials and liquid catalyst carried by gas, the unreacted materials and the liquid catalyst are circulated to a methyl chloride synthesis kettle for reaction, and the synthesis gas out of the first-stage gas-liquid separation tank enters a second-stage vaporizer, so that the catalyst carried by the gas and the liquid can be recycled, the conversion rate of reactants is improved, a heat transfer effect can be achieved, and the temperature runaway of the reactor is prevented;
4) in the secondary vaporizer, the high-temperature synthesis gas further exchanges heat with liquid methanol, the synthesis gas out of the secondary vaporizer enters a secondary gas-liquid separation tank, and the methanol out of the secondary vaporizer enters a superheater; under the normal working condition, the methanol entering the superheater is in a gas phase, and at the moment, the superheater does not work; when the working condition fluctuates, the methanol entering the superheater is in a gas-liquid two-phase state, at the moment, the superheater works, and the methanol is sent to a methanol feeding working section after being completely vaporized;
5) in the second-stage gas-liquid separation tank, condensate generated after heat exchange of the synthesis gas enters a reaction liquid recovery tank for resource utilization, and the synthesis gas out of the second-stage gas-liquid separation tank enters a water cooler for further cooling and then enters a third-stage gas-liquid separation tank;
6) in the third-stage gas-liquid separation tank, the liquid phase carried by the synthesis gas enters a reaction liquid recovery tank after separation, and the gas phase out of the third-stage gas-liquid separation tank is sent to a downstream purification section for treatment.
Compared with the prior art, the chloromethane synthesis reaction heat gradient comprehensive utilization process has the following unique features:
1) the multistage vaporizer is arranged to carry out cascade utilization on the heat of the high-temperature synthesis gas, so that the consumption of low-pressure steam and circulating cooling water in a synthesis section is reduced, and simultaneously, the methanol is completely vaporized under a fluctuation working condition, the device is easy to realize automatic control, and the reliability is high;
2) set up multistage gas-liquid branch jar, can effective control condensate quantity, the catalyst that will not react methyl alcohol or hydrogen chloride and gas clamp are taken out circulates to methyl chloride synthesis cauldron in the liquid phase form further reaction, improved the conversion rate of raw materials on the one hand, the catalyst loss problem that disposable condensation caused has been solved, process material consumption has been reduced, on the other hand through the circulation volume effective control methyl chloride synthesis cauldron's of adjusting reactor condensate temperature, prevent that the reaction process from taking place "temperature runaway" phenomenon, thereby guarantee production safety.
Drawings
FIG. 1 is a process diagram of the stepwise comprehensive utilization of the heat of the synthesis reaction of methyl chloride.
Reference numerals: the system comprises a methyl chloride synthesis kettle 1, a primary vaporizer 2, a primary gas-liquid separation tank 3, a secondary vaporizer 4, a secondary gas-liquid separation tank 5, a superheater 6, a water cooler 7, a tertiary gas-liquid separation tank 8 and a reaction liquid recovery tank 9.
Detailed Description
The process and apparatus operating characteristics of the present invention will be further described with reference to the accompanying drawings.
As shown in fig. 1, key equipment of the process for gradient comprehensive utilization of methyl chloride synthesis reaction heat comprises a methyl chloride synthesis kettle 1, a first-stage vaporizer 2, a first-stage gas-liquid separation tank 3, a second-stage vaporizer 4, a second-stage gas-liquid separation tank 5, a superheater 6, a water cooler 7, a third-stage gas-liquid separation tank 8 and a reaction liquid recovery tank 9.
Example 1
The liquid methanol comes from a storage tank, enters a device area at the temperature of 25 ℃, is divided into two equal parts, and respectively enters a first-stage vaporizer 2 and a second-stage vaporizer 4. The temperature of the high-temperature synthesis gas is 150 ℃, and the high-temperature synthesis gas is extracted from the methanol synthesis kettle 1 and enters the first-stage vaporizer 2 to exchange heat with methanol. The methanol out of the first-stage vaporizer 2 is totally vaporized and sent to a methanol feeding working section. The synthesis gas out of the first-stage vaporizer 2 enters a first-stage gas-liquid separation tank 3 for separation.
In the primary gas-liquid separation tank 3, the synthesis gas exiting the primary gas-liquid separation tank 3 enters the secondary vaporizer 4. The main components of the liquid phase from the first-stage gas-liquid separation tank 3 are hydrochloric acid, byproducts and the catalyst carried by the synthesis gas, the hydrochloric acid, the byproducts and the catalyst are circulated to the methyl chloride synthesis kettle 1 for reaction, and meanwhile, the temperature of the reaction kettle can be effectively controlled by adjusting the circulation amount, so that the phenomenon of temperature runaway in the reaction process is effectively prevented, and the safety and reliability of the production process are guaranteed.
In the secondary vaporizer 4, the methanol and the synthesis gas are further heat exchanged. The methanol in the secondary vaporizer 4 is totally vaporized and enters the superheater 6. At this time, the superheater 6 is not operated, and the gaseous methanol stream is directly fed to the feed section through the superheater 6. The synthesis gas out of the secondary vaporizer 4 enters a secondary gas-liquid separation tank 5 for separation.
In the second-stage gas-liquid separation tank 5, condensate enters a reaction liquid recovery tank 9 for resource utilization, gas phase enters a water cooler for cooling and then enters a third-stage gas-liquid separation tank 8 for gas-liquid separation, condensate is extracted to the reaction liquid recovery tank 9, and the gas phase is mainly chloromethane gas and is sent to a purification section for treatment.
Through technical improvement, the chloromethane synthesis section realizes no steam consumption in the normal operation process, and the consumption of cooling water is reduced by more than 46%.
Example 2
The liquid methanol comes from a storage tank, the temperature is 25 ℃, the liquid methanol enters a device area, and the liquid methanol is divided into two unequal strands which respectively enter a first-stage vaporizer 2 and a second-stage vaporizer 4. The high-temperature synthesis gas is extracted from the methanol synthesis kettle 1 and enters a primary vaporizer 2 to exchange heat with methanol. The methanol out of the first-stage vaporizer 2 is completely vaporized at the temperature of 90 ℃ and is sent to a methanol feeding section. The synthesis gas out of the first-stage vaporizer 2 enters a first-stage gas-liquid separation tank 3 for separation.
In the primary gas-liquid separation tank 3, the synthesis gas exiting the primary gas-liquid separation tank 3 enters the secondary vaporizer 4. The main components of the liquid phase from the first-stage gas-liquid separation tank 3 are methanol, water, byproducts and catalyst carried by synthesis gas, the catalyst is circulated to the methyl chloride synthesis kettle 1 for reaction, and meanwhile, the temperature of the reaction kettle can be effectively controlled by adjusting the circulation amount, so that the phenomenon of temperature runaway in the reaction process is effectively prevented, and the safety and reliability of the production process are guaranteed.
In the secondary vaporizer 4, the methanol and the synthesis gas are further heat exchanged. The methanol out of the secondary vaporizer 4 enters a superheater 6. At this time, since the heat load of the secondary vaporizer 4 is insufficient, the superheater 6 operates to vaporize methanol and then raise the temperature, and then send the vaporized methanol to the feeding section. The synthesis gas out of the secondary vaporizer 4 enters a secondary gas-liquid separation tank 5 for separation.
In the second-stage gas-liquid separation tank 5, condensate enters a reaction liquid recovery tank 9 for resource utilization, gas phase enters a water cooler for cooling and then enters a third-stage gas-liquid separator 8 for gas-liquid separation, the condensate is extracted to the reaction liquid recovery tank 9, and the gas phase is mainly methyl chloride gas and is sent to a purification section for treatment.
Compared with the traditional process, the technology has the advantages that the consumption of steam is reduced by more than 95%, and the consumption of cooling water is reduced by more than 45%.
The methyl chloride synthesis reaction heat gradient comprehensive utilization process provided by the invention is described by the implementation case, and the related technical personnel can obviously modify the structure and the equipment described herein and appropriately change and combine the structure and the equipment to realize the invention without departing from the content, the spirit and the scope of the invention. It is expressly intended that all such alterations and modifications which are obvious to those skilled in the art are included in the spirit, scope and content of this invention.
Claims (2)
1. A chloromethane synthesis reaction heat gradient comprehensive utilization process comprises a chloromethane synthesis kettle (1), a primary vaporizer (2), a primary gas-liquid separation tank (3), a secondary vaporizer (4), a secondary gas-liquid separation tank (5), a superheater (6), a water cooler (7), a tertiary gas-liquid separation tank (8) and a reaction liquid recovery tank (9);
the method is characterized by comprising the following steps:
step 1), dividing raw material liquid methanol into two parts, and respectively entering a first-stage vaporizer (2) and a second-stage vaporizer (4) for heat exchange;
step 2) the high-temperature synthesis gas comes from a methyl chloride synthesis kettle (1), firstly enters a first-stage vaporizer (2), exchanges heat with liquid methanol in the first-stage vaporizer, the methanol discharged from the first-stage vaporizer (2) is completely vaporized, and is sent to a methanol feeding working section, the synthesis gas discharged from the first-stage vaporizer (2) is in a gas-liquid two-phase state, and enters a first-stage gas-liquid separation tank (3);
step 3) in the primary gas-liquid separation tank (3), liquid mainly comprises unreacted materials and liquid catalyst carried by gas, the unreacted materials and the liquid catalyst are circulated into the methyl chloride synthesis kettle (1) for reaction, and the synthesis gas out of the primary gas-liquid separation tank (3) enters a secondary vaporizer (4);
step 4) in the secondary vaporizer (4), the high-temperature synthesis gas further exchanges heat with liquid methanol, the synthesis gas out of the secondary vaporizer (4) enters a secondary gas-liquid separation tank (5), and the methanol out of the secondary vaporizer (4) enters a superheater (6); under the normal working condition, the methanol entering the superheater (6) is in a gas phase, and at the moment, the superheater (6) does not work; when the working condition fluctuates, the methanol entering the superheater (6) is in a gas-liquid two-phase state, at the moment, the superheater (6) works, and the methanol is sent to a methanol feeding section after being completely vaporized;
step 5) in the secondary gas-liquid separation tank (5), condensate generated after heat exchange of the synthesis gas enters a reaction liquid recovery tank (9) for resource utilization, and the synthesis gas out of the secondary gas-liquid separation tank (5) enters a water cooler (7) for further cooling and then enters a third-stage gas-liquid separation tank (8);
and 6) in the third-stage gas-liquid separation tank (8), separating the liquid phase carried by the synthesis gas, then feeding the liquid phase into a reaction liquid recovery tank (9), and feeding the gas phase discharged from the third-stage gas-liquid separation tank (8) into a downstream purification section for treatment.
2. The methyl chloride synthesis reaction heat cascade comprehensive utilization process as claimed in claim 1, wherein the installation position of the superheater (6) is selectively installed at the outlet of the primary vaporizer, or at the outlet of the secondary vaporizer, or at both the outlet of the primary vaporizer and the outlet of the secondary vaporizer, or at the manifold of the outlet of the primary vaporizer and the outlet of the secondary vaporizer, according to the ratio of methanol entering the primary vaporizer (2) and the secondary vaporizer (4).
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| CN202010736518.7A CN111943804B (en) | 2020-07-28 | 2020-07-28 | Methyl chloride synthesis reaction heat gradient comprehensive utilization process |
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Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5236604A (en) * | 1975-09-13 | 1977-03-22 | Akio Sasaki | Preparation of methylchloride and its purification process |
| US4922043A (en) * | 1988-12-02 | 1990-05-01 | Vulcan Materials Company | Manufacture of methyl chloride by hydrochlorinating methanol, using a split methanol feed |
| CN106748631A (en) * | 2016-12-15 | 2017-05-31 | 湖北兴瑞化工有限公司 | A kind of monochloro methane energy-saving processing technique and device |
| CN206308285U (en) * | 2016-12-23 | 2017-07-07 | 唐山三友硅业有限责任公司 | Synthesis reactor waste-heat methanol device in chloromethanes synthesis procedure |
| CN106748632B (en) * | 2017-01-10 | 2019-05-10 | 南通科恩化工技术有限公司 | A kind of clean preparation method synthesizing chloromethanes |
| CN207347430U (en) * | 2017-10-13 | 2018-05-11 | 山东金岭化学有限公司 | Organosilicon chloromethanes synthesis reaction vessel waste heat recovery device |
| CN108409526B (en) * | 2018-03-09 | 2020-11-20 | 中国化学赛鼎宁波工程有限公司 | Methane chloride energy-saving production system and method |
| CN110652945A (en) * | 2019-09-23 | 2020-01-07 | 南京蓝胜环保科技有限公司 | Double-phase-change tubular heat exchange equipment and method for utilizing waste heat of chloromethane reaction |
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