The Study And Design Of The Synthesis Of Methy Chloride With The By-product Hydrogen Chloride Of Chloroacetic Acid

Chloroacetic acid is widely used in many industries such as medicine,pesticides,dyes,food additives,fine chemicals and so on,because it contains two functional groups,that is carboxyl and chlorine atom and can form many organic compounds.At present,most of enterprises of chloroacetic acid in our country adopt the reaction of chlorine and acetic acid in the presence of the sulfur.In the reaction,the by-product hydrogen chloride with sulfur dioxide is also produced except for the chloroacetic acid.Many native factories absorb the hydrogen chloride with water and sell the hydrochloric acid to pickling industry,which not only waste the resource,but also restrict the further expansition of the chloroacetic acid enterprises.Therefore,looking for a suitable hydrogen chloride exhaust cleaning route to expand its application range is of great significance to the development of chloroacetic acid industry.Firstly,the removal process of sulfurous acid in the hydrochloric acid was studied in this paper.Through the study of the nature of the sulfurous acid in the hydrochloric acid,the method of oxidation by oxidant and precipitation by precipitating agents was identified.Based on numerous screening of antioxidants and precipitant,chlorine was determined as oxidant,and barium carbonate as precipitant eventually.The results showed that when the airspeed of chlorine was 1.8-2.4 h-1,the reaction time was 120 minutes,the molar ratio of BaCO3:H2SO4 was 1.1-1.2,the reaction time was 80 minutes,sulfur dioxide could not be examined in the solution,the hydrochloric acid can reach the standards of GB320-2006,which was used for industrial synthesis of hydrochloric acid.Secondly,the removel method of sulfur dioxide in the hydrochloride was discussed in order to synthesis methyl chloride to increase the value of hydrochloride.The route is the solution of by-product hydrochloric acid as reaction system,sodium chlorate as oxidant.The optimum reaction conditions are as follows:n(NaClO3):n(SO2)=1:3,the reactor is towel reactor,the pressure is 0.2MPa.Lastly,the process for the methyl chloride with the annual output of 30000 tons was designed.Material balance and heat balance were firstly carried out for each unit.A selection of major equipments has been made based on calculational results and process design requirements.The specification and type of major equipments were determined and a list of the equipments was formed.Based on the above technological calculation and design requirements,the flow chart of piping and apparatus was designed.