Study On Catalytic Cracing Of Low-Quality Heavh Oil For Maximlzing Light Oil

With the continuous increase of oilfield extraction and the decrease of availableconventional crude oil, the crude oil tends to be heavy and poor quality, while market demandshortage for light oil grows, how to process the crude oil with heavy and poor quality, findingthe appropriate process to achieve maximum light oil and get the clean fuel has been the maindirection of the refineries development. Changqing Petrochemical Company adopts theTRSFCC technology which could process different types of raw materials and obtain a higheryield of light oil. Therefore, this paper conducted a systematic study for the crude oil so that itcould provide some references for the industry production.In this dissertation, The preliminary study of different catalysts and feedstocks werecarried out using a small scale fixed fluidized bed unit. The effect of operating parameters,such as reaction temperature,catalyst oil ratio and residence time on reaction performance ofAR,HCO and slurry was investigated. The results showed that it had good compatibilitybetween LVR-60R catalyst with Y zeolite and heavy oils which was suit to produce light oil.AR with high contents of H and saturation had better cracking performance than HCO andslurry, and the yield of light oil was higher. This optimal reaction temperature, catalyst oilratio and residence time of catalytic cracking were 520℃, 5 and 0.084h, respectively. Theyield of light oil reached 68.03%, the yields of gasoline and diesel were 45.81% and 22.22%,meanwhile it could also achieve a better product distribution. Cracking performance of HCOand slurry were relative lower, the appropriate reaction conditions can still get some light oilyield, the light oil yield for HCO and slurry could reach 40.50% and 36.59% respectively. Incomparison, HCO chose a longer residence time and slurry chose a higher temperature whichcould be more effective to promote cracking reaction and increase light oil yield significantly.In the experimental conditions, the gasoline fraction had a higher quality in which mostof olefin content were below 25%, the contents of aromatics and iso-paraffin were higher, thetotal content of them surpassed 60%, Research octane number was about 92.0. At the sametime, the gasoline RON of HCO and slurry were relatively higher than that of AR, whichmeets the national requirements of olefins in the gasoline which is less than 35%. By studying the spent catalyst using AR as the feedstock, the results showed that cokecontent of spent catalyst was 1.28%, it had still some catalytic activity. Regenerated catalystmixed spent catalyst with lower activity could increase the selectivity and yield of diesel,decrease the yield of coke. Furthermore, it could also raise the yield and selectivity ofpropylene and butylene. In view of the special performance of mixed catalysts, we proposed away to introduce regenerated catalysts into the disengager, then mixed with spent catalysts.The results indicated that spent catalysts with regenerated catalysts could not only strengthenthe catalytic activity and enhance catalytic cracking reaction to raise the yield of light oil, butalso could reduce coke formation in the disengager.