GB874440A - Improvements in or relating to the preparation of petroleum coke - Google Patents

Abstract

Petroleum coke suitable for conversion into graphite for use in nuclear reactors is made by coking a residue obtained from a light petroleum distillate by subjecting the light petroleum distillate to a thermal cracking treatment at a temperature between 500 DEG and 600 DEG C. and a pressure of at least 50 kg./cm.2 and separating the cracked product by distillation into a normally gaseous fraction, a fraction which is recycled to be recracked having a final boiling point and preferably a boiling range corresponding to the feed, and a residue to be coked which has an initial boiling point not lower than the final boiling point of the feed minus 10 DEG C. The residue from the distillation of the cracked product may be separated into two or more fractions and may be subjected to a second thermal cracking before the coking proper. The coking of the residue may be carried out by passing the residue through a pipe still, heated to a temperature between 450 DEG and 525 DEG C., preferably between 475 DEG and 510 DEG C. and discharging the residue into a coking chamber where the petroleum coke is formed, the residence time in the pipe still being such that no coke is deposited therein and the pressure at the outlet of the pipe still is between 7 and 35 atm. gauge, preferably 10-25 atm. gauge. Alternatively the residue may be contacted with petroleum coke particles for between 5 and 60 seconds at a temperature between 450 DEG and 650 DEG C. The coke thus produced is then preferably calcined at between 1100 DEG and 1400 DEG C. before being mixed with a binder, shaped and graphitized. The raw shaped pieces are first heated to between 300 DEG and 500 DEG C. to remove volatile matter and then finally at between 2500 DEG and 3000 DEG C. for 2 to 5 days. Specification 862,221 is referred to.