Delayed coking of coal tar

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Abstract: Feasibility exploration experiments on the delayed coking of coal tar produced by coal gasification plants were conducted to investigate the product distribution and properties of coal tar after delayed coking, as well as the appropriate process conditions for processing coal tar. Coal gasification plants produce coal tar as a by-product while generating gas. China has a considerable amount of coal tar, accounting for about 2% to 9% of the total amount of gasified coal. In terms of its nature, scale, and quantity, it is sufficient to serve as a resource for industrial use. To make full use of this resource and explore technically and economically viable processing methods, feasibility studies on delayed coking of coal tar were conducted. This experiment adopted a single-pass process for delayed coking, and under process conditions of a furnace exit temperature of 450–510°C and a feed oil preheating temperature of 320–360°C, studies were conducted to optimize the operational parameters at different pressures, thereby obtaining appropriate process conditions as well as data on product distribution for the delayed coking of coal tar. A true boiling point apparatus was used to separate the oil produced by delayed coking into a gasoline fraction with a temperature below 180°C, a diesel fraction with a temperature between 180°C and 350°C, and a heavy oil fraction with a temperature above 350°C. Oil quality analyses were conducted on each fraction to determine whether their quality met the specified requirements. The research results show that when coal tar is processed under conventional delayed coking conditions (compared to operation at high pressure), the yield of light oils is slightly higher, while the yields of gases and coke are lower ； When operating at higher pressures, not only does the liquid yield decrease, but the yields of gas and coke also increase significantly. The various technical parameters of the gasoline and diesel fractions produced under the two process conditions do not meet the specified requirements, and further treatment is necessary