GB874439A - Improvements in or relating to the production of petroleum coke - Google Patents

Abstract

Petroleum coke suitable for conversion into graphite for use in nuclear reactors is made by coking an oil obtained by removing asphaltic constituents from a residual oil by extracting the oil with a liquefied normally gaseous hydrocarbon and distilling off the normally gaseous hydrocarbon. Methane, ethane and preferably propane and butane may be used as the extracting hydrocarbon, the extraction being carried out under conditions of temperature and pressure such that the extracting hydrocarbon is in liquid form. The oil obtained by the extraction treatment may, prior to coking, be treated with an oxygen-containing gas, e.g. air, at between 150 DEG and 400 DEG C., preferably 200 DEG and 300 DEG C., and at atmospheric pressure or at elevated pressure, e.g. between 2 and 5 kg/cm2. A proportion of 50 to 175 gms. of oxygen per kilogm of extracted oil is preferably used. The extracted oil may be coked by passing the oil through a pipe still heated to between 450 DEG and 525 DEG C., preferably between 475 DEG and 510 DEG C., the residence time being such that no coke deposits are formed in the still and the outlet pressure being between 7 and 35 atm. gauge, discharge being made into a heated coking chamber in which the coke is produced. Alternatively, the extracted oil may be deposited on petroleum coke particles in a fluidized bed at between 450 DEG and 650 DEG C. under such conditions that the contact time is between 5 and 60 seconds. 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.