Comparison of thermal hydrocracking with thermal cracking of Athabasca bitumen at low conversions

Abstract

The thermal hydrocracking process involves hydrogen addition as opposed to carbon removal in the thermal cracking process. Upgrading of Athabasca bitumen by thermal hydrocracking has been studied in the Energy Research Laboratory of CANMET for several years. This process allows flexibility in controlling pitch conversions, and at high conversions it produces more distillable oil than do coking processes. Low-conversion thermal hydrocracking is also important from the viewpoint of transporting the product through pipelines. The present investigation deals with low-conversion thermal aspects of hydrocracking. A comparison is made with data from thermal cracking or visbreaking. Tests were conducted with Athabasca bitumen feed in a 1-barrel /day high pressure pilot plant. Properties of products such as viscosity, gravity, sulphur, nitrogen, saturates, olefins, aromatics, benzene insolubles and asphaltenes were analyzed. Data on hydrogen consumption and hydrocarbon gas-make were also obtained. The thermal hydrocracking process was found to produce less naphtha and hydrocarbon gases than thermal cracking for the low-conversion conditions. The hydrocracked distillates contained less olefin than those from thermal cracking. The viscosity results indicated that pitch conversion of about 50% was sufficient to meet pipeline viscosity specifications. This showed that the hydrocracking process is more flexible than coking because the bitumen can be transported with minimum upgrading.