Research On Improvement Of Oil Shale Retorting Light End Recovery Rate

Oil shale, from which shale oil can be produced through lowtemperature retorting, can be used as the alternative resource of oil andgas. There are large scales of oil shale deposits in China. According tostatistics, the potential amount of shale oil is12billion tons, which equalsto more than half of the amount of minable regular oil. It can significantlyhelp to relieve the pressure on oil import.At present, the domestic shale oil plants are small in scale, and cannot realize intensive production, so the incondensable gas at the laterstage of the process cannot be made use of completely. For some plants,which are not very small in scale, use the gas to generate power, whoseeconomic profit is not significant. As a result, it is necessary to recoverthe light ends in incondensable gas in order to promote the oil recoveryrate of oil shale retorting and generate more profit for the plants. In thefield of light hydrocarbon recovery, the oil and gas industry has beendevoted in the process development and improvement. At this stage, thelow temperature recovery process is still being widely used, while thesupercold separation technology has been developed to a great extend.The improvement of low temperature recovery process is mainly focusingon lowering the energy consumption and raising the oil recovery rate, forwhich the main methods are: to use expansion machine for energy saving,to replace water cooling with air cooling, to optimize refrigeration plan and operating conditions. In addition, the new light hydrocarbon recoverytechnology has been successfully developed both at home and abroad, forexample, the gas wave machine, vortex tube, membrane separation,pressure swing adsorption(PSA), direct heat exchange(DHX) and so on.The advantages of the new technology lie in two aspects: one israising the light hydrocarbon recovery rate, the other is lowering theenergy consumption, which are also the direction for light hydrocarbonrecovery technology development.The oil shale low temperature retorting process is in the period ofdevelopment. Anyhow, when dividing from the perspective of heat supply,there are two different types, one is supplying heat by solids, and theother is by air. The former one is mainly making use of the combustedshale; the later one is making use of the flue gas produced by retortedsemi-coke combustion. Since the retorting products come out in the formof gas, for the process whose heat is supplied by air, the investment inrecovery equipment and running cost will be relatively increased. It willalso make light hydrocarbon recovery more difficult.Taking the ATP retorting technology as the basis and comparing theexisting vertical retort process of Fushun Mining Group with ATPretorting process, this paper conducted an experiment on the light endsrecovery rate of hydrocarbon. In the case of higher operational pressure,the light hydrocarbon recovery rate will be higher; in the case of lower operational temperature, the light oil recovery rate will be higher; in thecase of recovering light ends by PSA, when the operational pressure rises,the recovery rate of light ends will be lower. When the temperature goeslower, the light end recovery rate will be lower.