Production device of methane chloride

Abstract

The utility model discloses a production device of monochloromethane. The production device comprises a preheating gas holder for gasifying methanol, a mixed gas holder for mixing methanol gas and monochlorodifluoromethane tail gas, a chlorination reactor, a cooler, a water scrubber, a compression condensing tower and a rectifying tower which are connected in sequence, the lower part of the cooler is connected with a water and methanol collector, the lower part of the water scrubber is connected with a hydrochloric acid collector, the top of the compression condensing tower is connected with a trifluoromethane collector, and the top of the rectifying tower is connected with a finished product collector. According to the device disclosed by the utility model, hydrogen chloride in the monochlorodifluoromethane tail gas is utilized, and trifluoromethane is effectively separated. The purity of the trifluoromethane separated by the device disclosed by the utility model is more than 99.99%, and the trifluoromethane becomes a chemical product which can be further utilized; and the purity of the prepared methane chloride finished product also reaches 99.99% or above. According to the utility model, the pressure for treating trifluoromethane and fluorine-containing hydrogen chloride in an environment-friendly manner is reduced, the production cost is reduced, and the effects of sustainable development and co-production are achieved.

Description

Technical Field

[0001] The utility model relates to a chemical production device, in particular to a methyl chloride production device, belonging to the field of chemical equipment. Background Art

[0002] Methyl chloride, also known as chloromethane or methyl chloride, has a boiling point of -23.73°C. It is mainly used in the field of organosilicon as a raw material to prepare methylchlorosilane monomers, and is also an important raw material for preparing methylcellulose, quaternary ammonium compounds, pesticides, solvents for organic compounds, emulsifiers, and pharmaceutical anesthetics. It is also an intermediate of methane chlorides. In recent years, with the rapid development of the organosilicon and methane chloride industries, the demand for methyl chloride has been increasing continuously. At present, there are mainly two production methods for methyl chloride in China.

[0003] One method is methane chlorination: Methane is chlorinated by passing chlorine at high temperature. The chlorination products are absorbed by water to remove hydrogen chloride, and then, after compression and condensation to separate unreacted methane, the finished product methyl chloride and poly-chlorides are obtained by fractional distillation.

[0004] The second method is methanol chlorination: Using hydrogen chloride and methanol in a certain proportion as raw materials, the reaction is carried out under the action of a catalyst of metal iron, zinc or aluminum chloride or oxide to produce a single crude methyl chloride product, which is dried, compressed and condensed to obtain the finished product. Methanol chlorination can be further divided into a liquid phase method and a gas phase method. The liquid phase method is to mix gaseous methanol and hydrogen chloride and enter a reaction kettle equipped with a liquid catalyst for liquid phase reaction. The gas phase method is that gaseous methanol and hydrogen chloride react in a fixed bed reactor equipped with a catalyst. The reaction is an exothermic reaction, and the reaction heat is removed by a heat medium. From the analysis of the process route, the reaction mechanisms of the gas phase method and the liquid phase method are exactly the same, but the difference in catalyst selection leads to the difference in the reaction system. The medium temperature and medium pressure environment of the gas phase method are conducive to the quench liquid absorbing excessive hydrogen chloride. The liquid phase method is more suitable for removing excessive hydrogen chloride by low-temperature absorption method at normal pressure and relatively low temperature. The main differences between the gas phase method and the liquid phase method technologies are in aspects such as raw material specifications, operating conditions, product quality, and methanol conversion rate.

[0005] In the production of chlorodifluoromethane, due to the change in the activity of the catalyst, in addition to the target product, trifluoromethane (boiling point -84°C), dichlorofluoromethane (boiling point 8.9°C), and hydrogen chloride (boiling point -85°C) will also be produced during the reaction process. The separation of dichlorofluoromethane is relatively simple. Since the boiling points of trifluoromethane and hydrogen chloride are close, further separation or waste gas treatment is required, which increases the cost and wastes fluorine resources. Summary of the Utility Model

[0006] The technical problem to be solved by the present utility model is to provide a production device for methyl chloride, which can directly utilize the tail gas (a mixture of trifluoromethane and hydrogen chloride) produced in the production of chlorodifluoromethane as the source of hydrogen chloride, and effectively separate the products after the reaction to obtain high-purity methyl chloride products and trifluoromethane.

[0007] To solve the above technical problems, the present utility model discloses a production device for methyl chloride, which includes a preheating gas holder for gasifying methanol, a mixing gas holder for mixing methanol gas and chlorodifluoromethane tail gas, a chlorination reactor, a cooler, a water washing tower, a compression condensation tower, and a rectification tower, which are connected in sequence; the lower part of the cooler is connected to a water and methanol collector, the lower part of the water washing tower is connected to a hydrochloric acid collector, the top of the compression condensation tower is connected to a trifluoromethane collector, and the top of the rectification tower is connected to a finished product collector.

[0008] Further, the chlorination reactor is a horizontal coil reactor heated by heat-conducting oil.

[0009] Further, the coil diameter of the horizontal coil reactor is 3 cm and the length is 64 m.

[0010] Further, a solid catalyst for preparing methyl chloride is loaded in the coil of the horizontal coil reactor.

[0011] Further, the pipe diameter of the cooler is 60 cm, the length is 2.8 m, and the heat exchange area is 40 m 2 .

[0012] Further, the shell side of the cooler is connected to a tap water circulation system.

[0013] The present utility model directly connects to the chlorodifluoromethane tail gas, uses the hydrogen chloride in the chlorodifluoromethane tail gas to react with methanol to generate methyl chloride, removes the generated water and unreacted methanol completely through a cooler, then removes the unreacted hydrogen chloride through a water washing tower, removes the trifluoromethane that does not participate in the reaction in the tail gas through a compression condensation tower, and finally obtains high-purity methyl chloride finished products through rectification. It not only utilizes the hydrogen chloride in the chlorodifluoromethane tail gas but also effectively separates the trifluoromethane. The purity of the trifluoromethane separated by the device of the present utility model reaches more than 99.99% and becomes a chemical product that can be further utilized; the purity of the obtained methyl chloride finished products also reaches more than 99.99%. The present utility model reduces the pressure of environmental protection treatment of trifluoromethane and fluorine-containing hydrogen chloride, reduces the production cost, and achieves the effects of sustainable development and co-production. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the present utility model.

[0015] Reference numerals in the figure: 1 - preheating gas holder; 2 - mixed gas holder; 3 - chlorination reactor; 3.1 - coil; 4 - cooler; 5 - water washing tower; 6 - compression condensation tower; 7 - rectification tower. Detailed implementation mode

[0016] The present invention will be further explained below in conjunction with embodiments. The following embodiments are only used to illustrate the present utility model, but do not limit the implementation scope of the present utility model.

[0017] Embodiment 1

[0018] As Figure 1 shown, the production device of methyl chloride of the present utility model includes a preheating gas holder 1, a mixed gas holder 2, a chlorination reactor 3, a cooler 4, a water washing tower 5, a compression condensation tower 6 and a rectification tower 7 which are connected in sequence through pipelines. Some conventional valves in the pipelines, as well as necessary pressure gauges, thermometers, etc. for each component, although not shown in the figure, are still included.

[0019] Specifically, methanol enters from the lower part of the preheating gas holder 1, is preheated and vaporized and then led out from the upper part of the preheating gas holder 1 and enters the bottom of the mixed gas holder 2. At the same time, the tail gas of difluorochloromethane (a mixture of trifluoromethane and hydrogen chloride) enters from the lower part of the mixed gas holder 2. Gaseous methanol and the tail gas of difluorochloromethane are mixed into a mixed gas in the mixed gas holder 2, and the mixed gas is led out from the top of the mixed gas holder 2 and enters the chlorination reactor 3.

[0020] The chlorination reactor 3 is a horizontal coil reactor. The diameter of the coil 3.1 is 3 cm and the length is 64 m. The inside is filled with a catalyst of chloride or oxide of metal iron, zinc or aluminum. The outside of the coil 3.1 is heated by heat-conducting oil, and the heating temperature is 150 - 200 °C. Methanol and hydrogen chloride in the mixed gas undergo a catalytic chlorination reaction in the chlorination reactor 3 to generate methyl chloride and water. The crude gas after the reaction enters from the bottom of the cooler 4.

[0021] The pipeline diameter of the cooler 4 is 600 mm, the length is 2800 mm, and the heat exchange area is 40 m 2 , and the material to be cooled passes through the tube side, and the shell side is connected to the tap water circulation system. Through the reflux at the top of the cooling tower 4, the temperature of the crude gas coming out of the chlorination reactor 3 can be effectively reduced to 25 - 30 °C. The cooled water and methanol enter the water and methanol collector from the lower part of the cooler 4, and can be separately collected or the methanol solution can be collected as needed.

[0022] The mixed gas cooled by the cooler 4 is led out from the top of the cooler 4 and enters from the bottom of the water washing tower 5. In the water washing tower 5, it is washed with water to absorb the unreacted hydrogen chloride to form hydrochloric acid, which is discharged from the lower part of the water washing tower 5 and collected by the hydrochloric acid collector.

[0023] The mixed gas after washing is led out from the top of the water washing tower 5 and enters from the bottom of the compression and condensation tower 6. After condensation and separation, trifluoromethane is discharged from the top of the compression and condensation tower 6 and enters the trifluoromethane collector, or is directly used for other reactions. The pressure in the compression and condensation tower 6 is 20 MPa and the temperature is -10 °C. The purity of trifluoromethane reaches over 99.99%.

[0024] The crude methyl chloride after being treated by the compression and condensation tower 6 is led out from its lower part, enters from the bottom of the rectification tower 7, and after rectification treatment, is discharged from the top of the rectification tower 7 and enters the methyl chloride collector. The purity of methyl chloride reaches over 99.99%.

Claims

1. A production device for methyl chloride, characterized in that: The device includes a preheating gas holder (1) for gasifying methanol, a mixed gas holder (2) for mixing methanol gas and dichlorofluoromethane tail gas, a chlorination reactor (3), a cooler (4), a water washing tower (5), a compression and condensation tower (6) and a rectification tower (7) which are connected in sequence; the lower part of the cooler (4) is connected to a water and methanol collector, the lower part of the water washing tower (5) is connected to a hydrochloric acid collector, the top of the compression and condensation tower (6) is connected to a trifluoromethane collector, and the top of the rectification tower (7) is connected to a finished product collector.

2. The production device of methyl chloride according to claim 1, characterized in that: The chlorination reactor (3) is a horizontal coil reactor heated by heat transfer oil.

3. The production device of methyl chloride according to claim 2, characterized in that: The coil (3.1) of the horizontal coil reactor has a diameter of 3 cm and a length of 64 m.

4. The production device of methyl chloride according to claim 2 or 3, characterized in that: The coil (3.1) of the horizontal coil reactor is loaded with a solid catalyst for preparing methyl chloride.

5. The production device of methyl chloride according to claim 1, characterized in that: The pipe diameter of the cooler (4) is 60 cm, the length is 2.8 m, and the heat exchange area is 40 m 2 .

6. The production device of methyl chloride according to claim 1 or 5, characterized in that: The shell side of the cooler (4) is connected to a tap water circulation system.

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