Optimization Analysis For Delayed Coking Fractionator And Absorption-Stabilization System

As a secondary oil refining process, delayed coking occupies an important position in the oil industry. Because its process is simple and the technology is mature, it has a broad interest. Nowadays, the sulfur content, nitrogen content and metalliferous is increasingly high in the crude oil. The trend of poor quality of the crude oil is obvious. Due to the increase of sulfur and nitrogen content, which easy to make catalyst poisoned, so the application of the catalytic cracking process is limited, and the delayed coking process gets more and more obvious advantages.The delayed coking process is divided into two parts of the reaction and the separation, the study of the reaction portion is to analyze the effect of the reaction temperature, reaction pressure, the circulation ratio and the kind of raw materials on the delayed coking products. The separation part includes the main fractionator and absorption-stabilization system, on the main fractionator research is to analyze the effect of the cycle taking the heat in the paragraphs cycle and rich absorption oil back to the tower temperature on the energy recycle and the yield and quality of product, on absorption-stabilization system research is to analyze the absorption amount and temperature and the way of feed on the oil product quality and other operation conditions.This paper was guided by a refinery’s data, the all process model of the separation part in delayed coking was established by Aspen plus process simulation software, the thermodynamic method of Grayson-Streed was selected in the main fractionators, and the thermodynamic method of RKS was mainly selected in absorption-stabilization system. The simulation results were consistent with the production data, which has verified the right of the model. Base on the right of the model, the main fractionator and absorption-stabilization system were optimized and analysed, the analysis results show that the main fractionator’s rich absorption oil return tower temperature without heating and directly into the main fractionators, then the thermal efficiency is the highest, when the case of other conditions is unchanged. Increasing refluxed on heat lower in lower part, the thermal efficiency will be improved effectively. When the return tower temperature and the top vapor flow rate are constant, the dry point of gasoline and diesel can be adjusted by regulating the circulation amount of the top cycle and middle cycle, the absorber column with an intermediate condenser can abviously improve the absorb result. The desorber column with an intermediate reboiler can effectively improve thermal efficiency. The way of different feeds in desorber column also have a larger effect on the thermal efficiency, and the results show that the hot feed’s thermal efficiency is the highest. Meanwhile, the two stage feed’s thermal efficiency is greater than the single-stage feed. The27th feed stage of stablizer can improve the seperation effeciency. The amount increase and the temperature decrease of absorption agent can reduce the C3and above component content in dry gas. The results of optimize and analysis have an important guiding significance in the engineering and produce operations.