The refinery includes all the processes required for the production of fuels, starting from petroleum. Typical products are gasoline, diesel, LPG, kerosene. Crude oil must first be cleaned from sulfur (which is then recovered) and from other substances that can alter its quality; through various heating processes (at temperatures generally around 360 ° -370 °) in the distillation columns, heavy products are converted into lighter products, which are qualitatively more important products. Hydrocarbon chains are broken and the crude oiis transformed into LPG, gasoline, oil, kerosene and various gasoline through the cracking process. The residual substances of these processes are again burned at even higher temperatures (visbreaking at about 450 ° C) to obtain new usable products. Each singe product passes through other specific processes (reforming, alkylation, esterification).