| Fluidized Catalytic Cracking unit(FCC)process is the most important on secondary processing of crude oil in our country,it is a significant technological method to produce diesel oil,but a high content of aromatics and low cetane number in this diesel is one of the problem for oil refining production enterprise,so seeking an economic and reasonable catalyzing diesel oil technology is the key to improve the quality of diesel.A new FCC diesel oil aromatics extraction progress was researched in this paper,a n ew mixed solvent A+B was selected.Extraction and solvent recovery rate were studied based on MS and GC.The FCC diesel oil of containing 75% aromatic and 20% paraffin were selected,results showed that acetonitrile had obvious stratification with low extraction rate,solvent A had higher dissolving ability for aromatics but its selective was low and FCC diesel oil recovery rate was not high.The selective of solvent B was high but it had poor solvent for dissolving.Combined two of acetonitrile,Diethylene glycol,A and B respectively,the separation results of solvent A+B were best.When the ratio of A and B was 1:1,the extraction rate was 45.72% and FCC diesel oil recovery rate was 63.90%.The effects of mixed solvent composition,solvent ratio,temperature,stirring time to extraction results were compared by experiments.The results showed that while the mixed solvent ratio was 1:3,solvent ratio was 7:1,extraction temperature was 50 ℃ and stirring time keeping 20 min,the extraction results were best,the extraction rate was 89.48% and FCC diesel oil recovery rate was 32.10%.In the aromatics extraction process,the influences of extraction methods and extraction stages to extraction effects were not obvious.Although the extraction rate increased slightly in two,three cross-flow and countercurrent extraction,FCC diesel oil recovery rate decreased slightly,the change were not obvious.The increased series mean more solvent consumption and lead to recovery energy increased.Considering the energy consumption,single-stage extraction could be applied in the aromatics extraction process,aromatics extraction rate was more than 89% and FCC diesel oil recovery rate kept more than 32% after single-stage extraction.The recovery of mixed solvent A+B was researched by experiment using washing-vacuum distillation process,the influences of water temperature,phase rate and counter mentioned series to washing effect were studied in this paper.The results showed that water temperature had little effect on the washing process,So the selected temperature is 25℃(room temperature).Phase rate had greater impacts on the washing process,counter mention rate was 0.5% when phase rate was 1:1.By multistage countercurrent reextraction mention counter operation,analyzing the impact of different stages of counter mention on the washing effect,counter mention rate was best at four mention counter,solvent content was below 100 ppm over reverse raffinate phase.By vacuum distillation experiments,the effects of reflux ratio and feed location on the vacuum distillation process were studied,and the reflux ratio of 1.2 along with the theoretical feed position of 30 is appropriate.Under these preferred conditions,tower kettle water content of the composite solvent was below 100 ppm,Composite solvent yield is 99.99%,and the solvent content in the top of the tower is only 75 ppm.In summary,the results of this study on the research and development of FCC diesel oil aromatics extraction process high aromatics extraction rate and high solvent recovery characteristics,the results can provide technical reference for FCC diesel oil refining technology. |
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