Methyl Chloride Synthesis System

Abstract

The present application provides a chloromethane synthesis system, wherein the high-temperature chloromethane synthesis gas from the reactor passes through a methanol vaporizer and an acid preheater, and then passes through a cooling tower to cool down to 25-35°C; after passing through a first scrubber and a second scrubber, the methanol, hydrogen chloride and water-soluble impurities in the synthesis gas are removed; the synthesis gas is then input into a third scrubber to further remove the acidic substances in the synthesis gas; the water-containing chloromethane synthesis gas output from the third scrubber enters a drying tower for drying and dehydration, and finally dry and clean chloromethane is obtained, which is collected and stored. In the present application, the high-temperature chloromethane synthesis gas is used to heat and vaporize methanol, which can replace the low-pressure steam used to heat and vaporize methanol in the original production, thereby saving the use of low-pressure steam in the chloromethane production process, and has the advantages of reducing production costs and energy conservation and emission reduction.

Description

Technical Field

[0001] The present application relates to methyl chloride synthesis technology, and in particular to a methyl chloride synthesis system. Background Art

[0002] Methyl chloride, also known as methyl chloride, is a colorless, easily liquefied gas. It is an important chemical raw material, mostly used in the production of methylchlorosilane, tetramethyl lead, methyl cellulose, etc. It can also be used to produce quaternary ammonium compounds, pesticides, etc. It is used as a solvent in the production of butyl rubber. The existing methods for producing methyl chloride generally include methane chlorination, methanol chlorination, photochlorination, oxychlorination, etc.; methyl chloride is also produced as a by-product in some industrial processes, such as the production processes of trichlorfon, trichloroacetaldehyde, natural gas chlorination to produce carbon tetrachloride and phosphamide.

[0003] Among them, methanol chlorination is a widely used method at present. In this method, methanol is vaporized by steam heating and then introduced into a reactor to react with hydrogen chloride under the condition of zinc chloride as a catalyst to generate methyl chloride. In the process of generating methyl chloride, a large amount of reaction waste heat is generated, which cannot be used and causes a large amount of energy waste.

[0004] At present, most of the research on the process of synthesizing methyl chloride from methanol-hydrogen chloride is concentrated in the fields of production efficiency improvement, equipment maintenance, and methyl chloride refining, while there is less research on process energy-saving technology in the production of methyl chloride. Summary of the invention

[0005] The present application provides a methyl chloride synthesis system, which is used to solve the problem that a large amount of reaction waste heat generated in the above-mentioned methyl chloride process cannot be utilized and is wasted.

[0006] The present application provides a chloromethane synthesis system, comprising a reactor, wherein the reactor is sequentially connected in series with a methanol vaporizer, an acid preheater, a cooling tower, a first washing tower, a second washing tower, a third washing tower and a drying tower along the output direction of the chloromethane.

[0007] The methyl chloride output port of the reactor is connected to the tube side input port of the methanol vaporizer, the tube side output port of the methanol vaporizer is connected to the tube side input port of the acid preheater, and the tube side output port of the acid preheater is connected to the input port of the cooling tower.

[0008] The shell side input port of the methanol vaporizer is connected to a methanol storage tank, and the shell side output port of the methanol vaporizer is connected to the methanol input port of the reactor.

[0009] The shell side input port of the acid preheater is connected to a hydrochloric acid storage tank, the shell side output port of the acid preheater is connected to the input port of a hydrochloric acid analysis device, and the output port of the hydrochloric acid analysis device is connected to the hydrogen chloride input port of the reactor.

[0010] Optionally, a relay heater is further provided between the shell side output port of the methanol vaporizer and the methanol input port of the reactor.

[0011] Optionally, the system of the present application also includes a methanol preheater, a methanol storage tank is connected to the shell side input port of the methanol preheater, and the shell side output port of the methanol preheater is connected to the shell side input port of the methanol vaporizer; the tube side output port of the acid preheater is connected to the tube side input port of the methanol preheater, and the tube side output port of the methanol preheater is connected to the input port of the cooling tower.

[0012] Optionally, a methanol collector is further arranged between the pipe side outlet of the methanol preheater and the inlet of the cooling tower, the methanol collector comprising a methanol collector body and a grid plate arranged inside the methanol collector body, and the bottom of the methanol collector body is an inverted cone.

[0013] Optionally, a gas filter is connected to the output port of the drying tower.

[0014] Optionally, the washing medium in the first washing tower and the second washing tower is water, and the washing medium in the third washing tower is one or more of saturated sodium carbonate aqueous solution, saturated sodium bicarbonate aqueous solution, saturated potassium carbonate aqueous solution, and saturated potassium bicarbonate aqueous solution.

[0015] Optionally, the drying medium in the drying tower is one or more of concentrated sulfuric acid, highly absorbent resin, and anhydrous calcium chloride.

[0016] Optionally, the gas filter is filled with one or more of asbestos filter media, paper filter media, carbon fiber filter media, and polyamide filter media.

[0017] Optionally, the drying tower is provided with at least two stages.

[0018] Optionally, the hydrochloric acid analysis method in the hydrochloric acid analysis device is a constant boiling analysis method or a total analysis method.

[0019] In the system of the present application, the high-temperature synthesis gas generated in the reactor enters the tube side of the methanol vaporizer, and the methanol input into the shell side of the methanol vaporizer from the methanol storage tank is heated and vaporized, thereby realizing the first-stage waste heat utilization of the synthesis gas; after the synthesis gas is output from the tube side of the methanol vaporizer, it enters the tube side of the acid preheater again, and the hydrochloric acid input into the shell side of the acid preheater from the hydrochloric acid storage tank is heated, thereby realizing the second-stage waste heat utilization of the synthesis gas.

[0020] The synthesis gas output from the tube side of the acid preheater is cooled to 25-35°C through a cooling tower, and then passes through the first washing tower and the second washing tower to remove methanol, hydrogen chloride and water-soluble impurities in the synthesis gas; the synthesis gas is input into the third washing tower to further remove acidic substances in the synthesis gas.

[0021] The water-containing methyl chloride synthesis gas output from the third washing tower enters the drying tower for drying and water removal, and finally obtains dry and clean methyl chloride for collection and storage.

[0022] The liquid methanol flowing through the shell side of the methanol vaporizer is heated and vaporized, and then enters the reactor to react with hydrogen chloride. The hydrochloric acid flowing through the shell side of the acid preheater is heated, and then enters the hydrochloric acid analysis device to release hydrogen chloride gas. The released hydrogen chloride gas enters the reactor to react with the vaporized methanol.

[0023] The chloromethane synthesis system of the present application uses the high-temperature chloromethane synthesis gas from the reactor through a methanol vaporizer and an acid preheater to complete two-stage waste heat utilization. After the chloromethane synthesis gas undergoes two-stage waste heat utilization, the chloromethane synthesis gas is cooled to 25-35°C through a cooling tower, and then passes through the first washing tower and the second washing tower to remove methanol, hydrogen chloride and water-soluble impurities in the synthesis gas; the synthesis gas is input into the third washing tower to further remove acidic substances in the synthesis gas. The water-containing chloromethane synthesis gas output from the third washing tower enters the drying tower for drying and dehydration, and finally obtains dry and clean chloromethane for collection and storage. In the present application, the use of high-temperature chloromethane synthesis gas to heat and vaporize methanol can replace the use of low-pressure steam to heat and vaporize methanol in the original production, thereby saving the use of low-pressure steam in the chloromethane production process, which has the positive effects of saving energy, reducing production costs, saving energy and reducing emissions, and improving the production efficiency of the enterprise.

[0024] Furthermore, in order to ensure the smooth operation of the chloromethane synthesis system of the present application, a relay heater is provided in the system of the present application; in order to make more effective use of the waste heat of the chloromethane synthesis gas, a methanol preheater is also provided in the system of the present application; in order to reduce the waste of resources in production, a methanol trap is provided in the system of the present application; in order to further improve the cleanliness of the chloromethane, a gas filter is provided in the system of the present application.

[0025] In summary, the system of the present application, on the basis of making full use of the waste heat of methyl chloride synthesis gas, is also provided with a device for recovering reaction raw materials and a device for improving the cleanliness of methyl chloride gas of the present application. Therefore, the system of the present application has the advantages of energy saving and emission reduction, saving production resources, reducing production costs, and improving enterprise benefits and efficiency, and the setting of some devices has the function of ensuring the efficient and reasonable operation of the system of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 A schematic diagram of a chloromethane synthesis system provided in one embodiment of the present application;

[0028] Figure 2 A schematic diagram of a chloromethane synthesis system provided in another embodiment of the present application;

[0029] Figure 3 A schematic diagram of a chloromethane synthesis system provided in yet another embodiment of the present application;

[0030] Figure 4 A schematic diagram of a chloromethane synthesis system provided in yet another embodiment of the present application;

[0031] Figure 5 A schematic diagram of a chloromethane synthesis system provided in yet another embodiment of the present application;

[0032] Figure 6 A schematic diagram of the structure of a methanol trap provided in one embodiment of the present application;

[0033] Figure 7 A schematic diagram of a chloromethane synthesis system is provided for yet another embodiment of the present application.

[0034] Description of reference numerals:

[0035] 1. Reactor;

[0036] 2. Methanol vaporizer;

[0037] 3. Acid preheater;

[0038] 4. Hydrochloric acid analysis device;

[0039] 5. Cooling tower;

[0040] 6. The first washing tower;

[0041] 7. Second washing tower;

[0042] 8. The third washing tower;

[0043] 9. Drying tower;

[0044] 10. Hydrochloric acid storage tank;

[0045] 11. Methanol storage tank;

[0046] 12. Relay heater;

[0047] 13. Methanol preheater;

[0048] 14. Methanol trap;

[0049] 1401, methanol trap body;

[0050] 1402, grid plate;

[0051] 15. Gas filter. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work also fall within the scope of protection of the present application.

[0053] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0054] like Figure 1 As shown, the present application provides a chloromethane synthesis system, including a reactor 1, wherein the reactor 1 is connected in series with a methanol vaporizer 2, an acid preheater 3, a cooling tower 5, a first washing tower 6, a second washing tower 7, a third washing tower 8 and a drying tower 9 in sequence along the output direction of the chloromethane.

[0055] The methyl chloride output port of the reactor 1 is connected to the tube side input port of the methanol vaporizer 2 , the tube side output port of the methanol vaporizer 2 is connected to the tube side input port of the acid preheater 3 , and the tube side output port of the acid preheater 3 is connected to the input port of the cooling tower 5 .

[0056] The shell side input port of the methanol vaporizer 2 is connected to the methanol storage tank 11 , and the shell side output port of the methanol vaporizer 2 is connected to the methanol input port of the reactor 1 .

[0057] The shell side input port of the acid preheater 3 is connected to the hydrochloric acid storage tank 10 , the shell side output port of the acid preheater 3 is connected to the input port of the hydrochloric acid analysis device 4 , and the output port of the hydrochloric acid analysis device 4 is connected to the hydrogen chloride input port of the reactor 1 .

[0058] In the embodiment of the present application, methanol vapor (temperature is 90-100° C.) and hydrogen chloride react with the catalyst in the reactor 1 to generate methyl chloride:

[0059] CH3OH+HCl→CH3Cl+H2O.

[0060] The catalyst used in the reaction is zinc chloride solution (concentration of 75-80%). The reaction is an exothermic reaction. After the reaction occurs, methyl chloride is produced and a large amount of heat is released. The temperature of the synthesis gas out of the reactor 1 is 148-153°C. Therefore, the role of the reactor 1 is to provide a reaction site for methanol vapor and hydrogen chloride. Therefore, the reactor 1 needs to have high temperature resistance, acid corrosion resistance, and pressure resistance. In order to avoid the occurrence of "flying temperature phenomenon" during the reaction process (i.e., the system temperature rises violently in a very short time, such as within a few minutes or seconds during the reaction process), the input flow of methanol vapor and hydrogen chloride must be strictly controlled during the reaction process. For safety reasons, the outside of the reactor can be fixedly connected to heat dissipation fins.

[0061] The methanol vaporizer 2 is essentially a shell-and-tube graphite heat exchanger. The high-temperature synthesis gas flowing out of the reactor 1 passes through the tube side of the methanol vaporizer 2 and serves as a heating medium. The liquid methanol from the methanol storage tank 11 passes through the shell side of the methanol vaporizer 2 and is heated into methanol vapor, which is then input into the reactor 1 for reaction. The setting of the methanol vaporizer 2 can be regarded as the first-order utilization of the waste heat of the synthesis gas. The temperature of the synthesis gas output from the methanol vaporizer 2 is 100-110°C.

[0062] Since the composition of the synthesis gas is complex and contains hydrochloric acid gas, in order to reduce the degree of corrosion of the methanol vaporizer 2, the synthesis gas is made to pass through the pipe of the methanol vaporizer 2, which can extend the service life of the methanol vaporizer 2 and also facilitate daily inspection and maintenance.

[0063] The acid preheater 3 is essentially a shell-and-tube heat exchanger, and its function is to preheat the hydrochloric acid from the hydrochloric acid storage tank 10, so that the heated hydrochloric acid can enter the acid analysis device 4 for analysis and release of hydrogen chloride. The acid preheater 3 can be regarded as a second-order utilization of the waste heat of the methyl chloride synthesis gas. At this time, the temperature of the synthesis gas output from the acid preheater 3 is 75-90°C. Since the composition of hydrochloric acid is simpler than that of the synthesis gas, the hydrochloric acid passes through the shell of the acid preheater 3 to facilitate the daily maintenance of the acid preheater 3.

[0064] The hydrochloric acid analysis device 4, the hydrochloric acid heated by the acid preheater 3 enters the device, and releases hydrogen chloride gas by reheating or absorption by a desiccant. The released hydrogen chloride gas enters the reactor 1 to complete a chemical reaction with methanol vapor.

[0065] The setting of the cooling tower 5 can reduce the temperature of the synthesis gas to 25-35° C., and the cooling medium in the cooling tower 5 can be tap water or low-temperature salt water.

[0066] The washing medium in the first washing tower 6 and the second washing tower 7 is water, and the washing method is spray washing. After passing through the first washing tower 6 and the second washing tower 7, methanol, hydrogen chloride and water-soluble impurities in the synthesis gas can be removed.

[0067] The washing medium in the third washing tower 8 is an alkaline solution, which is used to further remove the acidic substances in the synthesis gas. The washing method is spray washing or bubbling washing.

[0068] The drying tower 9 can dry the synthesis gas. After the synthesis gas is washed by the first washing tower 6, the second washing tower 7 and the third washing tower 8, hydrogen chloride, methanol and other substances soluble in water or alkali liquid in the synthesis gas are removed, but moisture is introduced into the synthesis gas. According to the standard requirements of "Industrial Recovery of Monochloromethane" GB / T 26608-2011, the moisture content in the qualified monochloromethane is below 0.05%, so the synthesis gas needs to be dried before it is canned. The drying filler in the drying tower 9 needs to use a desiccant that does not react with chloromethane. Concentrated sulfuric acid is commonly used in industry to spray dry the synthesis gas. The drying tower 9 can be set in multiple stages to obtain a better drying and water removal effect.

[0069] In the system of the present application, the high-temperature synthesis gas generated in the reactor 1 enters the tube side of the methanol vaporizer 2, and the methanol input into the shell side of the methanol vaporizer 2 from the methanol storage tank 11 is heated and vaporized, thereby realizing the first-stage waste heat utilization of the synthesis gas; after the synthesis gas is output from the tube side of the methanol vaporizer 2, it enters the tube side of the acid preheater 3 again, and the hydrochloric acid input into the shell side of the acid preheater 3 from the hydrochloric acid storage tank 10 is heated, thereby realizing the second-stage waste heat utilization of the synthesis gas.

[0070] The synthesis gas output from the tube side of the acid preheater 3 is cooled to 25-35°C by a cooling tower 5, and then passes through a first washing tower 6 and a second washing tower 7 to remove methanol, hydrogen chloride and water-soluble impurities in the synthesis gas; the synthesis gas is input into a third washing tower 8 to further remove acidic substances in the synthesis gas.

[0071] The water-containing methyl chloride synthesis gas output from the third washing tower 8 enters the drying tower 9 to be dried and dehydrated, and finally dry and clean methyl chloride is obtained and collected and stored.

[0072] The liquid methanol flowing through the shell side of the methanol vaporizer 2 is heated and vaporized, and then enters the reactor 1 to react with hydrogen chloride to form methyl chloride. The hydrochloric acid flowing through the shell side of the acid preheater 3 is heated, and then enters the hydrochloric acid analysis device 4 to release hydrogen chloride gas. The released hydrogen chloride gas enters the reactor 1 to react with the vaporized methanol.

[0073] Through the above scheme, the methyl chloride synthesis system provided by the present application utilizes the waste heat generated in the methyl chloride synthesis process in a step-by-step manner, which can reduce the use of low-pressure steam when vaporizing methanol, is beneficial to saving the production cost of the enterprise, saving production resources, and improving production efficiency, and has the advantages of energy saving and emission reduction. In addition, a multi-stage purification device is arranged in the system of the present application so that the methyl chloride gas finally collected is dry and clean, and can meet the requirements of national production standards, thus playing a positive role in improving the production benefits of the enterprise and improving the competitiveness of the enterprise.

[0074] like Figure 2 As shown, optionally, a relay heater 12 is further provided between the shell side output port of the methanol vaporizer 2 and the methanol input port of the reactor 1 .

[0075] The system of the present application is also provided with a relay heater 12 between the shell side output port of the methanol vaporizer 2 and the methanol input port of the reactor 1. The relay heater 12 can prevent the methanol vaporized by the methanol vaporizer 2 from condensing due to the long transportation distance, thereby affecting the transportation efficiency and reaction rate. In addition, the relay heater 12 can be used as a methanol vaporization device when the system is started for the first time. The heat source used by the relay heater 12 can be high-temperature low-pressure steam or waste heat from other sections. Selecting waste heat from other sections can make the relay heater 12 make full use of various waste heat of the factory, play a role in energy conservation and emission reduction, and reduce production costs, and can ensure the efficient and reasonable operation of the system of the present application.

[0076] like Figure 3 and Figure 4 As shown, optionally, the system of the present application also includes a methanol preheater 13, the methanol storage tank 11 is connected to the shell side input port of the methanol preheater 13, and the shell side output port of the methanol preheater 13 is connected to the shell side input port of the methanol vaporizer 2.

[0077] The tube-side output port of the acid preheater 3 is connected to the tube-side input port of the methanol preheater 13 , and the tube-side output port of the methanol preheater 13 is connected to the input port of the cooling tower 5 .

[0078] In the system of the present application, a methanol preheater 13 is also provided, that is, the synthesis gas output from the tube side of the acid preheater 3 enters the tube side of the methanol preheater 13 again, and the methanol output from the methanol storage tank 11 and flowing through the shell side is heated. The provision of the methanol preheater 13 can be regarded as the third-stage utilization of the waste heat of the synthesis gas, and the temperature of the synthesis gas output from the methanol preheater 13 is below 70°C. The provision of the methanol preheater 13 not only realizes the reasonable and full utilization of the heat of the synthesis gas, but also reduces the cooling pressure of the cooling tower 5, and has the effects of energy saving and emission reduction, energy saving, reducing production costs, and improving the utilization efficiency of the waste heat of the synthesis gas.

[0079] like Figure 5 and Figure 6 As shown, optionally, a methanol collector 14 is further arranged between the pipe side outlet of the methanol preheater 13 and the inlet of the cooling tower 5; the methanol collector 14 includes a methanol collector body 1401 and a grid plate 1402 arranged in the methanol collector body 1401; the bottom of the methanol collector body 1401 is an inverted cone.

[0080] In the system of the present application, a methanol collector 14 is also provided between the pipe outlet of the methanol preheater 13 and the cooling tower 5. After the synthesis gas passes through the third stage waste heat utilization of the methanol vaporizer 2, the acid preheater 3 and the methanol preheater 13, the temperature of the synthesis gas will be reduced to below 70°C. At this temperature, the methanol mixed in the synthesis gas will condense. Therefore, the methanol collector 14 is provided to collect the condensed methanol, reduce the waste of resources, and save production costs. The interior of the methanol collector 14 is provided with a grid plate 1402 or a fin structure, so that when the synthesis gas passes through these grid plates 1402 or fin structures, the methanol will condense and be collected by the methanol collector 14, and finally recovered and centralized for treatment, thereby reducing unnecessary waste and saving production costs; the bottom of the inverted cone-shaped methanol collector body 1401 is convenient for collecting condensed methanol.

[0081] like Figure 7 As shown, optionally, a gas filter 15 is connected to the output port of the drying tower 9 .

[0082] In the system of the present application, a gas filter 15 is connected to the output port of the drying tower 9. When the synthesis gas is dried by the desiccant in the drying tower 9 and output from the drying tower 9, it is dry methyl chloride gas, but it may be mixed with trace amounts of desiccant or dust, which requires further filtering and purification of the methyl chloride gas output from the drying tower 9. The gas filter 15 can make the methyl chloride gas clean and pure, and the methyl chloride gas filtered by the gas filter 15 can be directly canned and stored.

[0083] The gas filter 15 is filled with a filter medium that does not react with methyl chloride, such as a paper filter medium, a carbon fiber filter medium, an asbestos filter medium, and the like.

[0084] Optionally, the washing medium in the first washing tower 6 and the second washing tower 7 is water, and the washing medium in the third washing tower 8 is one or more of saturated sodium carbonate aqueous solution, saturated sodium bicarbonate aqueous solution, saturated potassium carbonate aqueous solution, and saturated potassium bicarbonate aqueous solution.

[0085] In the system of the present application, the washing medium in the first washing tower 6 and the second washing tower 7 is water, which can remove water-soluble impurities in the chloromethane synthesis gas, especially methanol and hydrogen chloride; because methanol can be miscible with water in any proportion, after passing through the first washing tower 6 and the second washing tower 7, the methanol in the synthesis gas is almost completely removed, but there may still be a trace amount of hydrogen chloride gas in the synthesis gas, so a third washing tower 8 with an alkaline solution such as a saturated sodium carbonate aqueous solution, a saturated sodium bicarbonate aqueous solution, a saturated potassium carbonate aqueous solution, and a saturated potassium bicarbonate aqueous solution as a washing medium is provided, which can remove hydrogen chloride and other acidic impurities in the synthesis gas, reduce the pressure for subsequent processing steps, enable the purification treatment of the chloromethane synthesis gas to proceed smoothly, and finally collect pure chloromethane gas.

[0086] Optionally, the drying medium in the drying tower 9 is one or more of concentrated sulfuric acid, highly absorbent resin, and anhydrous calcium chloride.

[0087] In the system of the present application, the drying tower 9 is filled with concentrated sulfuric acid, highly absorbent resin, anhydrous calcium chloride and other media as desiccants. These media do not react with methyl chloride gas and have a good dehydration and drying effect. In addition, the desiccant used is cheap, easily available, renewable, and can be reused, thereby reducing the production cost of the enterprise and saving resources.

[0088] Optionally, the gas filter 15 is filled with one or more of asbestos filter media, paper filter media, carbon fiber filter media, and polyamide filter media.

[0089] In the system of the present application, the gas filter 15 is filled with asbestos filter media, paper filter media, carbon fiber filter media, and polyamide filter media. These media are chemically inert and will not react with chloromethyl gas. Therefore, it can be ensured that no impurities are introduced after filtering the chloromethyl gas, and the chloromethyl gas is kept clean and pure after being filtered. In addition, the above media are cheap and easy to obtain, which can reduce production costs and improve product quality, and has positive significance for enterprises to produce high-quality chloromethyl gas. In order to ensure a better filtering effect, multiple gas filters 15 can be connected in series.

[0090] Optionally, the drying tower 9 is provided with at least two stages.

[0091] The system of the present application is provided with a multi-stage drying tower 9 to ensure a better drying effect on methyl chloride and improve the quality of methyl chloride gas.

[0092] Optionally, the hydrochloric acid analysis method in the hydrochloric acid analysis device 4 is a constant boiling analysis method or a total analysis method.

[0093] The system of the present application, the azeotropic analysis method is to heat concentrated hydrochloric acid, form a mixed gaseous substance of hydrogen chloride gas and saturated steam of water at the top of the analysis device, form azeotropic acid at the bottom of the analysis device, and remove water from the mixed gaseous substance of hydrogen chloride gas and saturated steam of water by condensation to obtain pure hydrogen chloride gas. In this method, part of the concentrated hydrochloric acid will be wasted after forming azeotropic acid. Therefore, in order to reduce the loss of concentrated hydrochloric acid, a certain amount of calcium chloride is added to the azeotropic acid at the bottom of the analysis device to break the proportion of this azeotropic acid and release more hydrogen chloride. This method can reduce production costs and save resources.

[0094] The full analysis method is to heat concentrated hydrochloric acid and then drip it into a desiccant to absorb the water in the hydrochloric acid and release hydrogen chloride gas. Concentrated sulfuric acid is used as the desiccant. This method can completely release the hydrogen chloride in the hydrochloric acid, and the utilization rate of the hydrochloric acid is high.

[0095] The chloromethane synthesis system of the present application uses the high-temperature chloromethane synthesis gas from the reactor 1 through the methanol vaporizer 2 and the acid preheater 3 to complete the two-stage waste heat utilization. After the chloromethane synthesis gas is used for two stages of waste heat utilization, the chloromethane synthesis gas is cooled to 25-35°C through the cooling tower 5, and then passes through the first washing tower 6 and the second washing tower 7 to remove the methanol, hydrogen chloride and water-soluble impurities in the synthesis gas; then the synthesis gas is input into the third washing tower 8 to further remove the acidic substances in the synthesis gas. The water-containing chloromethane synthesis gas output from the third washing tower 8 enters the drying tower 9 for drying and dehydration, and finally obtains dry and clean chloromethane and collects and stores it. In the present application, the use of high-temperature chloromethane synthesis gas to heat and vaporize methanol can reduce or even replace the use of low-pressure steam to heat and vaporize methanol in the original production, thereby saving the use of low-pressure steam in the chloromethane production process, which has the positive effects of saving energy, reducing production costs, saving energy and reducing emissions, and improving the production efficiency of enterprises.

[0096] Furthermore, in order to ensure the smooth operation of the methyl chloride synthesis system of the present application, a relay heater 12 is provided in the system of the present application; in order to make more effective use of the waste heat of the methyl chloride synthesis gas, a methanol preheater 13 is also provided in the system of the present application; in order to reduce the waste of resources in production, a methanol trap 14 is provided in the system of the present application; in order to further improve the cleanliness of the methyl chloride, a gas filter 15 is provided in the system of the present application.

[0097] In summary, the system of the present application, on the basis of making full use of the waste heat of methyl chloride synthesis gas, is also provided with a device for recovering reaction raw materials and a device for improving the cleanliness of methyl chloride gas of the present application. Therefore, the system of the present application has the advantages of energy saving and emission reduction, saving production resources, reducing production costs, and improving enterprise benefits and efficiency, and the setting of some devices has the function of ensuring the efficient and reasonable operation of the system of the present application.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A chloromethane synthesis system, comprising a reaction kettle (1), characterized in that: The reactor (1) is connected in series in sequence along the output direction of methyl chloride with a methanol vaporizer (2), an acid preheater (3), a methanol preheater (13), a methanol collector (14), a cooling tower (5), a first washing tower (6), a second washing tower (7), a third washing tower (8) and a drying tower (9); the output port of the drying tower (9) is connected to a gas filter (15); The methyl chloride output port of the reaction kettle (1) is connected to the tube side input port of the methanol vaporizer (2), the tube side output port of the methanol vaporizer (2) is connected to the tube side input port of the acid preheater (3), the tube side output port of the acid preheater (3) is connected to the tube side input port of the methanol preheater (13), and the methanol trap (14) is arranged between the tube side output port of the methanol preheater (13) and the input port of the cooling tower (5); The shell side input port of the methanol vaporizer (2) is connected to the shell side output port of the methanol preheater (13), the shell side output port of the methanol vaporizer (2) is connected to the methanol input port of the reactor (1), and the shell side input port of the methanol preheater (13) is connected to the methanol storage tank (11); The shell side input port of the acid preheater (3) is connected to a hydrochloric acid storage tank (10), the shell side output port of the acid preheater (3) is connected to the input port of a hydrochloric acid analysis device (4), and the output port of the hydrochloric acid analysis device (4) is connected to the hydrogen chloride input port of the reaction kettle (1); The methanol trap (14) comprises a methanol trap body (1401) and a grid plate (1402) arranged inside the methanol trap body (1401); the bottom of the methanol trap body (1401) is in an inverted cone shape; The temperature of the synthesis gas output from the reactor (1) is 148-153°C.

2. The methyl chloride synthesis system according to claim 1, characterized in that: A relay heater (12) is also provided between the shell side output port of the methanol vaporizer (2) and the methanol input port of the reactor (1).

3. The methyl chloride synthesis system according to claim 1, characterized in that: The washing medium in the first washing tower (6) and the second washing tower (7) is water, and the washing medium in the third washing tower (8) is one or more of a saturated sodium carbonate aqueous solution, a saturated sodium bicarbonate aqueous solution, a saturated potassium carbonate aqueous solution, and a saturated potassium bicarbonate aqueous solution.

4. The methyl chloride synthesis system according to claim 1, characterized in that: The drying medium in the drying tower (9) is one or more of concentrated sulfuric acid, highly absorbent resin, and anhydrous calcium chloride.

5. The methyl chloride synthesis system according to claim 1, characterized in that: The gas filter (15) is filled with one or more of asbestos filter media, paper filter media, carbon fiber filter media, and polyamide filter media.

6. The methyl chloride synthesis system according to any one of claims 1 to 5, characterized in that: The drying tower (9) is provided with at least two stages.

7. The methyl chloride synthesis system according to any one of claims 1 to 5, characterized in that: The hydrochloric acid analysis method in the hydrochloric acid analysis device (4) is a constant boiling analysis method or a total analysis method.

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