This also produces hydrogen, which is useful in other refinery processes. Recently, efforts have concentrated on converting refinery residues into usable products. Residues may also be processed by removing carbon, which is the basis of many coking techniques which yield coke for burning as a fuel. The techniques used in a refinery depend on the types of crude to be processed and the requirements of the market. More than a hundred different crudes are internationally traded and a modern refinery may have to process as many as 20 grades during the course of a year.
Different markets require different products.
Markets are constantly changing as people conserve energy or switch to other fuels. In recent years, many refineries have invested considerably in conversion facilities, installed computers to process refinery operations and introduced energy management schemes, all measures designed to enhance their flexibility, enabling them to meet market demands. Freight rates, product quantities and distances between distribution points and customers all have to be taken into account in selecting the best ways to transport products. The main uses for oil products are transportation, heating, lighting and power generation. The petrochemical industry, too, provides us with innumerable products of great value to industry and to our daily lives.