长庆石化1.2Mt/a加氢裂化装置运行与标定

长庆石化1.2Mt/a加氢裂化装置选用壳牌标准催化剂公司的DN-3551/Z-503/Z-3723/Z-673组合催化剂,开工时利用DMDS干法硫化后未进行液氨钝化,一次开车成功,装置运行平稳,能够满足生产需求。但有些指标未达到设计要求,如氢耗较高、轻质产品占比较大等。标定期间,氢油比为959∶1(体积比),氢分压为10.25MPa,加氢精制反应器和裂化反应器的平均反应温度分别为390.6℃和398.9℃。标定结果显示,加氢精制反应器前后脱硫率为98.1%,脱氮率为97.6%;反应单程转化率为57.38%;轻质油收率为91.78%,尾油收率为7.52%。经核算,得出化学氢耗为2.16%(占原料油质量百分数);反应热为168.46MJ/t原料;装置单位能耗为31.158kg标油/t原料。装置运行主要存在两个瓶颈问题:一是原料为高干点且硫低氮高的单一减压蜡油馏分,反应系统循环气中硫化氢含量不足而氨含量高,存在需要补硫的问题;二是系统压力设计低,而且原料性质较差,造成催化剂选型困难和操作苛刻度较高。

The Operation and Performance Test of 1.2Mt/a Hydrocracking Unit in ChangQing Petrochemical Company

PetroChina Changqing Petrochemical Company′s 1.2Mt/a hydrocracking unit uses Shell Criterion Catalysts Company′s DN-3551/Z-503/Z-3723/Z-673 catalyst combination.When the unit first started operation,DMDS dry vulcanization method was used and no liquid ammonia passivation was carried out.The unit was put into operation successfully on the first try.Its performance was stable and met production requirements.However,some of the indices failed to meet designs.The unit′s hydrogen consumption is high and light products account for a large share of all products produced.Performance tests show that the unit′s hydrogen/oil ratio is 959∶1（by volume）,partial pressure of hydrogen is 10.25MPa and the average reaction temperatures of the hydrotreating reactor and cracking reactor are 390.6℃ and 398.9℃ respectively.The test results show that the rate of desulfurization upstream and downstream of the hydrotreating reactor is 98.1%,the rate of denitrification is 97.6%,the reaction one-way conversion rate is 57.38%,the yield of light oils is 91.78% and that the yield of tail oil is 7.52%.Calculation results show that the unit′s chemical hydrogen consumption is 2.16%（by mass fraction in feed oil）,the reaction heat is 168.46MJ/t of feedstock and that the unit energy consumption is 31.158kg of oil equivalent per ton of feedstock.Two bottlenecks in relation to the operation of the unit are identified.Firstly,the feedstock used is a VGO fraction characterized by high dry point,low sulfur content and high nitrogen content.In the circulating gas of the reaction system,the hydrogen sulfide content is too low and the content of ammonia is relatively high,calling for the replenishment of sulfur.Secondly,the designed pressure of the system is low and the properties of feedstock are poor.Thus,catalyst selection is difficult and operating severity is high.