Vinyl Chloride Production from Ethylene Dichloride

The process under analysis comprises three major sections: (1) Thermal Cracking; (2) VCM Purification; and (3) EDC Recovery.

Thermal Cracking. The EDC from the EDC Tank is mixed with recycled EDC and is preheated, vaporized and subsequently cracked in a pyrolysis furnace heated by fuel combustion. The cracking reaction is endothermic and generates VCM, HCl, by-products of various chemical structures and coke. The furnace operates at temperatures above 480 °C and pressure of about 16 bar. Cracking rates of up to 60% are achieved, with selectivity to VCM greater than 98%.

VCM Purification. The output from the pyrolysis furnace, containing the VCM produced, is quenched to minimize coke formation. The overhead from the quench is sent to the HCl Column. Hydrogen chloride stream recovered in column overhead is sent to a section, where acetylene impurity is hydrogenated. After, it is sent to the consumer. The column bottoms, comprising unconverted EDC and VCM, are fed to a VCM column, where VCM is separated from unconverted EDC. Residual HCl present in VCM stream is removed in a stripper and recycled to the first column, while VCM product is stored.

EDC Recovery. Unreacted EDC is fed to the High-Boil column, for high-boiling compounds removal. The bottom product from the High-Boil column and the bottom product from quench are fed to the Vacuum Column, where more EDC is recovered. EDC streams are recycled to cracking, while heavies is sent to a waste disposal system.