GB766761A - Process for calcining coke - Google Patents

Abstract

766,761. Coking. ESSO RESEARCH & ENGINEERING CO. Feb. 16, 1955 [March 22,1954; March 22, 1954], No. 4676/55. Class 55(1). A process for calcining petroleum coke comprises coking a heavy oil by contact with fluidized coke particles, which are heated by recycling a portion through a separate burning zone, passing some particles from this zone at high velocity through a conduit burning zone with combustible gas and oxygen-containing gas and calcining the thus heated particles at a still higher temperature of 2000-2700‹ F. for from 5 minutes to 8 hours. A bed of coke particles preheated to establish a temperature of 1000‹ F. is fluidized in a coking vessel 1 by steam &c., and oil is admitted through a pipe 2; product vapours pass off through a separator 6 and a stream of solid particles are transported through a line 8 by air &c. to a burner vessel 10 together with secondary air from a line 11. A gas such as carbon monoxide or a part of the coke is burnt to raise the temperature of the particles to 100-300‹ F. higher than that in vessel 1 to which a part is returned through a line 9. The net make coke removed through a line 17 is transported through a transfer line preheater 18 at e.g. 50 ft. per second by hot flue gases from a transfer line burner 22 to which the particles are then delivered. Here the coke is subjected to 2200‹ F. for 0.2 seconds whilst transported by a burning stream of carbon monoxide from a calciner 32 and air &c. admitted through an inlet 29. From a separator 25 the particles pass to the calciner operating at e.g. 2400‹ F. in which they are fluidized by air &c. either a portion being burnt to provide the increased temperature, or natural gas or fuel oil being added in lieu. The coke is retained in the vessel for e.g. 20 minutes to reduce the volatile content at 950‹ C. to 0.3 per cent or less. More than one calciner-soaker may be used for batchwise operation and a number of superposed beds may be provided. The preheating and burner units may comprise a single line. In a modification coke is heated in a transfer line burner to 2300-2600‹ F, and then fluidized in a calciner by inert gas such as nitrogen or carbon dioxide. Coke may be activated in the soaker and used to desulphurize or otherwise improve the quality of the naphtha, gas oil or light hydrocarbons from the coking vessel.