Refinery Processes
Distillation The process of turning crude oil into finished petroleum products is an important stage of the oil supply chain. The crude oil is split up by distillation processes into its component parts - gas, light ends (such as gasoline and naphtha), middle distillates (such as kerosene and diesel oil), heavy fuel oil and miscellaneous other products. The precise outcome of distillation is governed by the crude's original chemical composition (see separate table on quality and yields), though it is possible, by adjusting distillation plant operation and blending, to alter yields of each product group by 2%.
Upgrading After distillation, it is then possible by the use of more sophisticated processes to make further changes in the proportions and quality of products produced (see table below). Depending upon the equipment of a given refinery, and the manner in which it is operated, substantial alterations can be made in the yield from a given crude - usually with the intention of producing more of the valuable distillate products. By this means, the average 50% yield of distillate products from first distillation can be increased to close to 90% in a really sophisticated American refinery, and even in Europe up to 75% can often be achieved.
Refining Costs Refining costs are a significant item in the total cost of the oil supply chain, but the major proportion of these are fixed costs incurred in constructing and staffing the refinery. Reforming and cracking units are substantially more expensive than distillation facilities, but once in place the variable costs of operating all units are relatively small. Whether a unit is operated or not usually affects only marginal power consumption and chemical/catalyst costs. Even the most sophisticated refineries rarely have a marginal total cost per tonne of throughput of more than $2.50 ($0.35/barrel), whereas fixed costs may be as much as $20/tonne ($2.75/barrel) or more, depending on type of plant, date of construction and financial treatment. |
