Hydrocracking Technologies – Maximising utilisation via process integration


Many refiners have been increasing profits by further integrating the hydrocracker with other processing units (delayed coker, solvent deasphalter, FCC, and so on) to maximise the yield of high quality products as refiners choose to increase complexity to enhance profitability. Several companies are looking to reduce capital investment and operating costs by fully integrating hydrotreating and hydrocracking. The opportunity for enhanced integration will be found in new grassroots designs and through the retrofitting of existing units. The goals of these integrated vessels are to lower construction costs by reducing material requirements and to minimise energy and hydrogen demand during operation. Implementing an optimised heat exchanger network and cascading hydrogen through the unit will save a significant amount of energy and improve the overall profitability of the operation. A reduction in CO2 emissions will also be accomplished as a result of the savings in energy.

In an example, Shell revamped an existing vacuum distillation unit (VDU) to install new separation technologies on the unit while also integrating the VDU with an existing hydrocracker to raise the amount of VGO available as feed to the hydrocracker. The new separation technologies would also increase the cycle length of the VDU as the timeframe for decoking would be extended. The VDU revamp increased VGO available for the hydrocracker by about 2% while extending the cycle length of the VDU from three to four years. The refiner estimated that the payback period for the revamp was less than a year.

As a way to overcome the limited conversions (~65%) associated with ebullated bed resid hydrocracking units, both Axens and CLG have proposed integrating their ebullated bed resid hydrocracking technology with solvent deasphalting (SDA) to boost unit conversion. Axens says its H-OilRC ebullated bed resid hydrocracking process may be combined with its Solvahl SDA technology in various ways to boost unit conversion to 85-95 wt% based on the specific goals of a refinery based n feedstock, product requirements, and site constraints. CLG has introduced its LC-Max resid hydrocracking scheme which combines its ebullated bed resid hydrocracking technology LC-Fining with SDA to provide 85+% conversion of vacuum residue to VGO and other light products.

Source: PTQ Q1 2018

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