1. Introduction

The complete range of processes undertaken in the minerals processing industry was outlined in CF 255. This combustion file gives more specific detail of the processes in use for the manufacture of [GLOSS]dead burnt[/GLOSS] petroleum [GLOSS]coke[/GLOSS].

2. Dead Burnt Petroleum Coke

Petroleum coke is the bottom [GLOSS]crude oil[/GLOSS] product from a modern oil refinery.   The heavy fuel oil fractions are cracked to produce more profitable lighter (white) oil products, and the residual is a ‘green’ coke containing approximately 5-15% (very heavy molecular weight) volatiles and 85% ‘pure’ carbon.   This is sold commercially on the open market as a cheaper solid fuel competitor to [GLOSS]coal[/GLOSS], and is widely burnt in [GLOSS]rotary kiln[/GLOSS]s.  The coke is contaminated with abrasive catalyst fines (alumina) and is the sink for most of the heavy metals in the crude oil (e.g. vanadium); thus it is only suitable as a fuel for a number of limited applications.   However, if the green coke is further heated under reducing conditions in a rotary kiln, the remaining volatiles are driven off and a high purity carbon is produced.  This material is used for the production of electrodes etc. and it is the highest value product produced by the refinery.

The rotary kiln burner, which is used to raise the temperature of the coke bed to ~1100^oC, is fired by [GLOSS]refinery gas[/GLOSS] or green petroleum coke dust (fines). Staged air is introduced in modern kilns by fans along the kiln to burn off the volatiles from the coke bed.  The exhaust gases from the kiln pass into an incinerator to burn the remaining volatiles and carried over coke dust.

Sources

[1] European Minerals Yearbook

[2] Industrial Minerals Handy Book