INHIBITION OF COKE FORMATION IN ETHYLENE DI CHLORIDE CRACKING FURNACE TO IMPROVE SERVICE LIFE

Abstract

The cracking of ethylene dichloride to vinyl chloride monomer is a very important process as it eventually produces polymers used in plastics. They have a very diverse function hence the polymer plant can be very beneficial if made cost effective. This can be achieved by an efficient cracking procedure in the furnace. A thermal cracking furnace is used by Engro Polymer which cracks the feed at high temperature into VCM. As a result of this high temperature, coke deposition inside the furnace takes place which not only decreases the production but also damages the furnace tubes. We need to avoid the coke deposition. In order to do so, a number of different mechanisms can be used. Changing the type of cracking can be incorporated; it would not only reduce coke deposition but may also improve the quality of the process. A disadvantage of changing the cracking type is that it would increase the cost. A number of other mechanisms for inhibition of coke like introduction of phosphine groups in the feed, application of Sulphide groups on the tube walls and purification of the input stream can also be used. The modification we suggest is changing the burner design of the furnace to remove the flame impingement points. Needle flame is changed to flower flame which improves the flux distribution inside the furnace and reduces coke. A burner and furnace design with its 3-D model is shown. This improves the production and increases the service life of the tubes.