vinyl chloride waste gas high temperature pyrolysis method 6 kinds. With the strengthening of 

human environmental awareness, acetaldehyde and carbon disulfide method has been eliminated; 

China is mainly methane method as the main mode of production, methane chlorination, include-

-ing four kinds of methyl chloride, including a bunch of mixtures, according to the difference in boiling point Can be easily through the ordinary fractionation technology to separate and purification; and the development of the West are basically the use of methanol preparation of dichloromethane. Methanol process and methane process process is roughly the same, by comparison, the use of methanol production process requirements of the equipment is relatively low, a small amount of by-product, a high utilization of raw materials, the higher the yield of dichloromethane, so The production of dichloromethane is a more suitable option for the methanol process.

（2） process to determine

  The whole process is mainly composed of five parts: the hydrogenation reaction section, the chlorination reaction section, the refining section, the absorption and desorption section and the treatment section. In addition, it is equipped with auxiliary equipment such as acid-base storage unit, steam and condensate recovery unit The A certain proportion of methanol and hydrochloric acid are reacted with zinc chloride as a catalyst in a hydrochlorination reactor to produce methylene chloride, unreacted methanol and HCl to form a methanol-containing acidic solution in a washing and cooling column. Of the methanol recycled, washed with methyl chloride in the drying tower with sulfuric acid washing the reaction process of dimethyl ether, and drying of methyl chloride, pure methyl chloride by the compressed to 0.758MPa sent to the chlorinator. Chloromethane reacts with chlorine in a chlorinator to produce dichloromethane, Trichlorometh-

ane and carbon tetrachloride. By varying the feed ratio, different product yields can be obtained. The gas is cooled in a quench tower and the separation of most of the HCl, unseparated HCl and Cl2 is separated in the HCl stripping column, the HCl is dehydrochlorinated and the unreacted Cl2 is returned to the chlorinator. Methane chlorides are fed to the distillation column and are purified to give methyl chloride, dichloromethane, trichloromethane and carbon tetrachloride.

3.Technical parameters

（1）Production capacity: 7800h / year 40,000 tons of dichloromethane;

（2）Ingredients: CH3OH 97.0%; HCl 96.0%;

（3）Reactor feed ratio (molar ratio) CH3OH: HCl = 1.0: 1.2;

the ratio of the reactor to the reactor CH2Cl2: CHCl3 = 1: 0.4 (mass ratio);

（4）(CHCl3 + CCl4) / CH2Cl2 = 0.45 (molar ratio);

（5）operating pressure 0.12MPa (gauge pressure);

（6）Reactor inlet gas temperature: 65℃;

                          Outlet temperature: 130℃.

4. Design principles

The design principles include: product quality control indicators, safety, ease of operation, Invest-

-ment, easy to install and so on.

In this design through the access to the relevant literature, to determine the dichloromethane synthesis process and production processes; and then with an annual output of 40,000 tons of dichloromethane synthesis of the design tasks related to the material balance and heat balance Calculate and complete the design and selection of major equipment such as hydrochlorination reactor, chlorination reactor, dichloromethane absorption tower and dichloromethane drying tower. On the basis of complete selection, AUTOCAD software is used to draw the flow chart with the control point, the layout of the workshop equipment, the design plan and the elevation plan of the dichloromethane absorption tower, and compile and write the design specification.