Studies On The Utilization Of The FCC Slurry

Currently, FCC slurry, which is the byproduct obtained from FCC unit, is mainly burnt out as low-value heavy fuel oil, wasting of resource. Under some circumstances, it has a great value for exploitation and utilization based on the characteristics of composition. From the viewpoint of energy conservation, it is meaningful to take full advantage of FCC slurry resource to make it a new economic growth point of refineries. In this paper, we discussed the utilizations of two slurries from different FCC units according to their property and composition.This paper has analyzed the properties and compositions of FCC slurry from MIP-CGP units. The results showed that the slurry contains 87.37% aromatics and less than 6% saturates. It is a good feedstock for producing rubber softener. Slurry was separated into a series of fractions by vacuum distillation and the properties of both narrow and wide fractions were studied. By comparison the 400~500℃fraction was chosen to be used as rubber softener. The application results showed that in the process of producing tire tread rubber, this fraction could improve the processing performances apparently and made the physical-mechanical properties of vulcanized rubber better with less heat, more anti-abrasion and anti-oxidation. Therefore, the 400~500℃fraction of MIP-CGP slurry is an excellent rubber softener.Changqing FCC slurry contains about 41% saturates, which can be easily cracked in an FCC system. In order to find out the premium feedstock fit for catalytic cracking, the catalytic cracking experiments with different feedstocks obtained from slurry with different pretreatments were carried out in a confined fluidized-bed reactor system. The results showed that: without pretreatment, FCC slurry was somewhat inferior feedstock to cracking, which was characterized by hydrogen-deficient and high aromatics content, thus resulting in low conversion and poor product distribution after catalytic cracking. Solvent extraction using NMP and furfural as solvent removed large amounts of heterocyclic compounds and polynuclear aromatics from FCC slurry, the raffinate oils exhibited better qualities than untreated FCC slurry. The better removal of aromatic hydrocarbons was achieved by using NMP as solvent. Both the conversion and product distribution showed improvements during the two raffinate oils cracking. The topped light FCC slurry, which obtained from vacuum distillation, contained more aromatics than FCC slurry,but the aromatics were mainly light-aromatics and middle-aromatics. Compared to FCC slurry, cracking topped light FCC slurry resulted in increase in light oil yield and decrease in coke yield clearly. The catalytic cracking experiments of narrow fractions of slurry showed that the saturate content was low in each cut leading to low conversion, and the CCR increased shapely as the cuts became heavier, causing higher coke yields in heavier cuts. Therefore, all narrow cuts were not suitable for FCC cracking.