The Bi-Provincial Upgrader Complex: is designed to produce 7310 m3/cd of synthetic crude and 1270 m3/cd of asphalt from 8590 m3/cd of a 65/35 volumetric blend of Lloydminster and Cold Lake heavy oils. The Complex will consist of the existing Lloydminster refinery and the Bi-Provincial Upgrader.
The Bi-Provincial Upgrader is a new facility which will be located in Saskatchewan about 8km from the existing Husky refinery. The refinery is a 3975 m3/sd unit whose primary function is to produce asphalt from heavy oil. After start-up of the Upgrader the refinery will continue to produce asphalt, naphtha, which is recycled 10 the production fields for use as a diluents, and a combined gas oil stream. This gas oil stream will be hydrotreated in the Upgrader.
The process configuration and some of the more important considerations in the process design of the Upgrader are reviewed in this paper.
There is a wide variety of potential processes available for upgrading heavy crude oil. These processes range from simple "vis breaking"--a mild thermal cracking which reduces the viscosity 10 allow easier pipelining of the crude--to complete refining to finished transportation fuels.
For the Bi-Provincial Upgrader the objective is to produce synthetic crude which can be easily processed in existing Canadian refineries into premium transportation fuels that meet current specifications. The main synthetic crude quality targets are therefore:
nitrogen content of naphtha
smoke point and aromatics of the jet fuel fraction
cetane number of mid-dislillates
nitrogen and polynuclear aromatics in the cat cracker feed fraction.
The properties of the heavy crude oil feedstocks are shown in Table 1 and the primary synthetic crude quality targets in Table 3.
The principal goal in a heavy oil upgrader are to increase the hydrogen to carbon ratio of the heavy crude oil feedstock, achieved by means of the primary upgrading technology, and to reduce the sulphur and nitrogen, achieved by secondary upgrading (hydrotreating). Typically, reduction of the metals content is also accomplished in the primary upgrading step. The selection of an upgrader process configuration is therefore not merely based on the comparison of one primary upgrading technology with another, but also includes a comparison of the facilities required to support the primary technology considered.
Between 1976 and 1982, Husky was involved in various studies pertaining to the application of heavy oil upgrading processes to Lloydminster and Cold Lake area crudes. Engineering studies and pilot plant work were also conducted by engineering contractors, licensors and consultants. By 1983, based on the results from these studies, we had narrowed our primary upgrading process selection options to two: Flexicoking3 and ebullated bed hydrocracking. Flexicoking3 was the preferred primary upgrading technology because, at that time, the technical risk of achieving the design conversion rates at acceptable operating costs was lower than that associated with the ebullated bed hydrocracking process. However, because of the higher liquid yields and the potential for better financial performance with hydrocracking, Husky decided to conduct further pilot plant work and engineering studies to gamer additional information prior to final process selection.