Process for the production of needle coke

摘要

A process is disclosed for producing needle coke from heavy atmospheric distillation residues having sulfur no more than 0.7 wt %, which process involves the steps of heating the feedstock to a temperature in the range of 460 to 540° C. for thermal cracking in a soaking column under pressure in the range of 1 to 10 kg/cm² to separate the easily cokable material, separating the cracked products in a quench column and a distillation column and then subjecting the hydrocarbon fraction from the bottom of the quench column and a heavy gas oil fraction having 10% true boiling point more than 370° C. and 90% true boiling point not less than 480° C. from the distillation column and/or any other suitable heavier hydrocarbon streams in a definite ratio depending on certain characteristic parameters to thermal cracking in a second soaking column at a temperature of 440 to 520° C., pressure in the range of 2 to 20 kg/cm² in presence of added quantity of steam for formation of a mesophase carbonaceous structure which on steam stripping and cooling forms a solid crystalline coke suitable for manufacturing of graphite electrode of large diameter having co-efficient of thermal expansion lower than 1.1x10^-6/° C. measured on graphite artifact in the temperature range of 25 to 525° C.