Description of WPE Oil Distillation System
Refineries separate crude oil into many different hydrocarbon products. Among them are kerosene, gasoline, asphalt, fuel oil and various flammable gases. A refinery distills the incoming crude oil to break it down into each usable component; a process commonly referred to as fractional distillation.
Each required hydrocarbon component has a different boiling point.In a fractional distillation process, the incoming crude is heated until it begins to vaporize. The vapor flows into the distillation tower and begins to separate out. Heavier hydrocarbon molecules with longer carbon chains settle towards the bottom of the tower. Lighter hydrocarbon molecules with less carbon atoms float to the top.
Crude oil also contains undesirable non-hydrocarbon components including water, salts of sulfur, chloride, ammonia and various metals. The contaminants tend to concentrate in the upper part of the tower together with a substantial amount of water vapor. The vapors from the top of the tower pass to a condenser (turning liquid)and then to a unit that separates the oil from the water. As the contaminants are more soluble in water than oil, they tend to collect the separated water, turning it acidic. The hydrocarbons return to the tower for further processing (or travel on to another distillation tower).
Refining of crude oils or petroleum essentially consists of primary separation processes and secondary conversion processes. The petroleum refining process is the separation of the different hydrocarbons present in the crude oil into useful fractions and the conversion of some of the hydrocarbons into products having higher quality performance. Atmospheric and vacuum distillation of crude oils is the main primary separation processes producing various straight run products, e.g., gasoline to lube oils/vacuum gas oils (VGO). These products, particularly the light and middle distillates, i.e., gasoline, kerosene and diesel are more in demand than their direct availability from crude oils, all over the world.
Crude oil distillation consists of atmospheric and vacuum distillation. The heavier fraction of crude oil obtained from atmospheric column requires high temperature. In order to avoid cracking at higher temperature the heavier fraction are fractional under vacuum.
Typical flow-diagram of crude oil distillation is given in Figure D-1. Various Streams from Atmospheric And Vacuum Distillation Column is given in Table D-2.