Hydrotreating's Influence On Catalytic Cracking Performance Of Coker Gas Oil

Fluid catalytic cracking(FCC)process is an important oil refining process,it produce most of gasoline and diesel in china.In recent years,the national standards of gasoline and diesel has become increasingly stringent.Limited by the quality of raw material,some of the products come from traditional FCC can't meet the national standard even after modification.To solve this problem,scholars are seeking the better modification methods.Meanwhile a lot of work are done focusing on Pre-treatment and combined processes.This paper focus on the combine of pre-hydrogenation and FCC?Most of the experiment in this paper are carried out on the pilot of China University of Petroleum(East China).Since the structure and reaction conditions of the pilot are different from industrial unit,its product distribution and product properties are not the same with the industry.In this paper,the pilot is used to simulate the industrial production,at the same time a set of empirical correction method are created in order to narrow the difference between the pilot and industrial unit.This method is applicable to this particular pilot that is uesed in this paper,and it can helps us to guide the industry.In this paper,a kind of mixture oil of 16% CGO and 84% VGO and its products after hydrogenation of harsh conditions are used to carry out the simulation of industry.The results of the pilot show that the cracking performance of the feedstock oil is significantly improved after pre-hydrogenation.Most of the properties of the product are improved.After pre-hydrogenation the gasoline yield of mixture oil increased 3.42%.The LPG yield increased 6.70%.However,it is difficult to adjust the distribution of the catalytic cracking product after the hydrogenation,and the heat generated by coke combustion is not enough for the FCC device.Modified under less harsh pre-hydrogenation conditions,the gasoline yield of mixture oil increased by 2.53%,conversion rate increased by 1.59%.The problem is consistent with the hydrogenation under high harsh conditions,beside the FCC products still need further modification.Pre-hydrogenation also improves the catalytic cracking performance and product properties of pure CGO.The results of the pilot show that the gasoline yield is increased by 5.27% and the yield of LPG is increased by 9.02% even after the most moderate hydrogenation.There is also a dramatically drop of miscellaneous elements in gasoline and diesel.The catalytic cracking performance and the properties of the product are further improved after harsher pre-hydrogenation conditions.After the most harsh conditions of pre-hydrogenation,gasoline yield increased by 17.13%,LPG yield increased by 10.36%.After pre-hydrogenation most of the product's properties have also improved significantly except for the composition of the diesel products.The experimental results show that pre-hydrogenation can improve the catalytic cracking performance of CGO and mixture oil,but there are several problems.First of all the yield of coke decreases significantly.Secondly a large part of the hydrogen element is assigned to low-value alkane.Last but not least the ring structure has an adverse effect on the composition of the product.