Abstract: The effect of different injected medium on the product distribution and product properties of delayed coking was investigated. The results of pilot test showed that when the injected medium of 1% steam was replaced by the same amount of methane, ethane or propane, the product distribution was nearly equal under the conditions that the feed rate, furnace outlet temperature, operating pressure, circulation ratio and coking period were basically the same. When the amount of methane injection raised from 1.04% to 1.96% and 4.02%, the yield of coker gas oil increased by 1.16 and 3.44 percentage points, respectively, and the yield of liquid products increased by 0.75 and 2.19 percentage points, respectively. With the increase of methane injection, the properties of coker gasoline and coker diesel were basically the same, but the properties of coker gas oil became worse. The density, residual carbon and asphaltenes content all increased, and its 95% point of the distillation range increased by 21.9 oC. Moreover, when the injection mass of steam and methane was the same, methane was more conducive to retard the furnace tube coking than steam.

Key words: delayed coking, furnace, coking, Injection medium, methane, product property