Production of 200MTPD of Methyl Chloride by Chlorination of Methane

تاریخ : جنوری ۲۰۱۷ - جولائی ۲۰۱۷

<p>Highly purified methane (99%) and chlorine are charged separately into the reactor(R-201). In the reactor temperature is maintained at 350 oC and pressure of 3 atm. Here conversion of methane 65 % and all amount of chlorine is consumed. The reactore here is multitubular plug flow reactor in which gases are passed in the tube side. As the reaction is exothermic so in order to control the temperature some cooling water is provided in the shell side.</p> <p>From the reactor the products chloromethanes (CH3Cl, CH2Cl2, CHCl3, CCl4), HCl, N2, CO2, along with unconverted methane are passed through cooler (E-201). Here temperature of the product stream is reduced from 350 to 200 oC. here water is used as cooling media.</p> <p>Now from cooler the products chloromethanes are partially condensed in a partial condenser (E-202). Here two streams are obtained at 30 oC. From here the uncondensible components(CH3Cl, CH4, HCl, N2, CO2) are entered into the bottom of absorption column (D-201). And the liquid stream containing mixture of CH2Cl2, CHCl3, and CCl4 is carried out into tubular exchanger(E-203).Here temperature of liquid stream is reduced to 15 oC by using brine solution and sent into the storage tank ( F-301).</p> <p>In the absorption column most of the chloromethanes are absorbed from un-reacted methane and by-product HCl. About 99% CH3Cl, 10 % HCl, and almost all havier chloromethanes are absorbed by using a chilled cooled crude mixture of chloroform and carbon tetrachloride along with some amount of methylene chloride.</p> <p>The bottom product of absorption column is passed through pre heater(E-205) to increase the temperature of stream to 35 oC. After passing through pre heater chloromethane are entered at the top of the stripper(D-102).</p> <p>Here chloromethane are separated containing over head product of methyl chloride,  HCl and some higher boiling chloromethane. And the bottom containing CH2Cl2, CHCl3, and CCl4 stripper here is plate type.</p> <p>Now the streams from top of stripper are fed into HCl scrubber (D-203) where 60 % HCl is absorbed in hot water at 80 oC.</p> <p>Streams from top of HCl scrubber containing CH3Cl, CH2Cl2, CHCl3 and HCl are sent  into caustic scrubber(D-104). Where NaOH is used to neutralized HCl. The bottom of HCl scrubber is sent into another HCl scrubber (D-206).</p> <p>Top product of caustic scrubber (D-204) is sent into dryer column (D-205) where traces of water are removed by using 98 % H2SO4, using as a dehydrating agent.</p> <p>Form dryer D-205 the mixture of methyl chloride and methylene chloride is sent into compressor. Where mixture is compressed to 9 atm. After compressing the mixture is sent into the partial condenser E- 205, where all amount of methylene chloride and some amount of methyl chloride is condensed.</p> <p>The streams coming from top of absorption column containing unconverted methane, inter, and HCl is sent into HCl scrubber D-206. where 32 % by weight of HCl is produced and sent into storage tank F-102.</p> <p>Product from top of HCl scrubber is again sent into caustic scrubber D-206 to neutralize remaining HCl.</p> <p>Top product from neutralizer D-207 is sent into the dryer column D-208 where the traces of water are removed and unconverted methane is sent into recovery section.</p>