with Manoj Kumar, CSIR, Indian Institute of Petroleum
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Fluid Catalytic Cracking (FCC) is one of the versatile processes in modern petroleum refining industry. The product slate of FCC includes LPG, gasoline, diesel and slurry oil. The slurry oil is a lowest value product coming out from FCC unit because it is predominantly rich in polynuclear aromatics (PNA).
Upgradation of slurry oil into transportation fuels through catalytic processes is also not practically possible because PNA are resistant to ‘cracking’ and act as ‘coke precursors’. Generally, petroleum refiners dispose slurry oil by partially recycling it to FCC unit along with fresh feed and sending the rest of slurry oil to ‘fuel oil pool’. The recycling of slurry oil results in deterioration of fresh feed quality and causes gradual coke build-up on catalyst leading to decrease in conversion and yield of distillate products. Therefore, the quantity of recycling of slurry oil to FCC unit is limited to maximum 15% by vol. on FCC feed basis. The blending of slurry oil to ‘fuel oil pool’ also does not contribute towards any value-addition to refiners.
CSIR-IIP offers a technology to enhance refinery margins by producing premium refinery products from FCC slurry oil. This technology is based on an innovative concept of combining two different disciplines i.e. ‘solvent extraction’ and ‘catalytic cracking’. This technology provides a unique solution for processing of low-value FCC slurry oil using liquid-liquid-extraction with a tailor made solvent, thereby producing two premium streams, one raffinate which is a recyclable premium quality additional de-aromatized feed for the FCC unit and the other aromatic rich high BMCI extract which qualifies as a premium quality Carbon Black Feedstock (CBFS).
Some of the salient features of this innovative technology are: It provides addition quantity of improved quality feed stock (density 0.8447–0.8510 g/ml) containing lower aromatics as compared to fresh FCC feed (density 0.8921 g/ml) which results in reduction in coke lay down on cracking catalyst and consequently increased life of cracking catalyst. The technology also results in increasing yields of FCC products (LPG 4.76 Wt%/Gasoline 17.10 wt%) and reduction (4.47 wt %) in FCC slurry oil production. The aromatic extract of 142+ BMCI co-produced in this process is a premium quality, high value CBFS. Further valorization of aromatic extract can be achieved by converting it into high-value ‘mesophase pitch’ – a precursor for various industrial/advanced carbon materials.
This technology has been implemented successfully in one of the Indian Refineries. After, implementation, refinery reported the enhancement in gross refinery margin (GRM) leading to increased profitability of the refinery to the tune of nearly US$ 15 million per annum.