Crude oil flash tower
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Some plants send crude oil to a flash tower before it enters the atmospheric and vacuum distillation towers, in order to remove some of the gasoline components as well as hydrogen sulfide, thereby increasing the plant’s processing capacity. However, only one-third of the gasoline components are removed; two-thirds of them still come out during atmospheric distillation. Why can’t the temperature of the crude oil entering the flash tower be increased to remove more gasoline components? This would allow for an even greater increase in processing capacity
Function of pre-distillation in crude oil distillation units: It separates the light components that can be vaporized through heat exchange promptly, preventing them from entering the atmospheric pressure furnace; this reduces the thermal load on the heating furnace. It also removes the gaseous hydrocarbons and moisture present in the crude oil before they reach the atmospheric pressure tower, thereby helping to stabilize operation in that tower. Processing crude oil with a high content of light components helps to reduce the load on the atmospheric distillation column.
If heat exchange is used, the temperature can be increased by altering the heat exchange process before sending the material into the flash tower; however, if it’s not possible to use heat exchange and other methods must be employed to raise the temperature, it’s somewhat not worth it!
The gas return line at the top of the flash tower is also connected to the regular tower, which keeps the load on that tower high; now it has been changed to use a distillation column with a separate system at its top