Coke Gasification - A Solution to Excess Coke Capacity and High Energy Costs

Abstract

United States crude slate is becoming heavier and generally higher in sulfur. At the same time demand of distillate products is increasing. Refiners are reworking their plans to include resid conversion via coking and approximately 230,000 BPD of new coking capacity is either under construction or announced. Even if 50 percent of the coke produced is exported, there will be an excess capacity of coke selling at less than $30/ton depending upon the sulfur content. This coke can be gasified effectively to produce medium-Btu (300 Btu/scf) gas which, in turn, can fuel the refinery furnaces to replace natural gas. Coke gasification should prove economical with natural gas price decontrol and the average price projected to rise to over $14.0 per million Btu in 1990.

The paper will discuss three gasifiers - Gesellschaft fur Kohle-Technologie Gmbh (GKT), Texaco and Westinghouse which may be used for the production of medium-Btu gas from coke. The design parameters, which for coke gasification may be different from coal gasification because of the difference in physical and chemical characteristics of coke and coal, will be evaluated. Conceptual design will be performed based upon normal fuel requirements of about 20 billion Btu per day for a typical 50,000 BPD refinery. Adaptability of coke derived gas to refinery fuel systems will be discussed in terms of flame temperatures, flue gas volumes, derating and required furnace modifications. Estimates of capital and operating costs will be obtained to calculate the gas cost using the new tax laws. Finally, the GKT gasifier will be compared to the developing Texaco and Westinghouse gasifiers to assess the effect of second generation gasifiers on the economics of coke gasification.