Study On The Quick Prediction Of Shot Coke Formation

Shot coke formed during delayed coking makes damage to the coking unit and workers. It is time-consuming to predict shot coke formation with the traditional method, the paper presents new methods to predict shot coke formation quickly.Generally speaking, compared with heavy oil forming normal coke(normal coke oil), heavy oil forming shot coke (shot coke oil) has higher content of asphaltene and releases more heat, the paper collects kinds of heavy oils from the scene and does research on the toluene insoluble content,trip time and product distribution of constant temperature experiment and the ratio of carbon residue to asphaltene among kinds of heavy oil under the determined conditions. The results indicate: (1) The toluene insoluble content of shot coke oil is more than that of normal coke oil under the 4 investigated conditions, furthermore, the gap is biggest under the condition of 420℃-40min; (2)Time consumed by normal coke oil is longer than that consumed by shot coke oil, but the gap does not differ much, moreover, carbon residue of shot coke oil is more than that of normal coke oil; (3) Micro-carbon residue of shot coke oil is higher than that of normal coke oil, Besides, when the ratio of micro-carbon residue to asphaltene is less than or equal to 2.0, it is likely to generate shot coke. Additionally, in view of the deficiency of the thermal process unit, a new micro-device is designed to predict shot coke formation quickly.It takes about 1 day to predict shot coke formation with the traditional method, however, new methods presented by the paper only take 3~12 hours, which is much less than the traditional method, furthermore, it can accurately and timely predict shot coke formation, and present guidance for the production as soon as possible.