Selection of the initial distillation tower and flash tower

1. For ordinary crude oil, the initial distillation tower possesses greater capabilities and flexibility compared to the flash tower in terms of pre-dehydration, hydrogen sulfide removal, and preventing overpressure in the atmospheric distillation column； 2. However, from a process perspective, the initial distillation tower process is more complex and requires higher investment. However, if a light recovery unit is installed in the atmospheric and vacuum distillation unit, the compressor can be omitted, **reducing the total investment for the entire unit. 3. The light gasoline, which is the product from the initial distillation tower, is generally used as feed for catalytic reforming units. Due to the arsenic-containing organic substances in crude oil, which decompose and vaporize as the temperature of the crude oil rises, the arsenic content in the gasoline from the initial distillation column is low, whereas the arsenic content in the gasoline from the atmospheric distillation column is very high. Arsenic is a harmful substance for reforming catalysts; therefore, crude oils with high arsenic content used to produce reforming feedstocks generally employ a fractional distillation tower. 4. The initial distillation tower shares part of the processing load of the atmospheric tower, while the flash tower does not. Please add or correct!

Currently, the pre-vaporization process of crude oil is widely used abroad for processing light crude oil; meanwhile, compressors are installed on the overhead gas stream to recover the light hydrocarbons in the crude oil. The feature of this approach is that the lighter components in crude oil are vaporized in a crude oil flash tower and then directly introduced to an appropriate section of the atmospheric distillation column for fractionation. This reduces the temperature of the oil at the bottom of the flash tower, improves heat exchange efficiency, and decreases the flow rate of oil entering the atmospheric furnace, thereby saving energy. Additionally, a compressor is used to compress the non-condensable gases from the top of the atmospheric column; these gases are then absorbed by a portion of the oil from that column. The condensed oil and the oil from the top of the column are pumped to a stabilizer unit where light hydrocarbons are recovered. The non-condensable gases after compression, as well as those from the top of the stabilizer unit, are sent to a coking unit for desulfurization treatment. This method enables the recovery of straight-run liquefied gas from the atmospheric and vacuum distillation units, while also helping to protect the environment. Simple process, easy operation, low energy consumption, and low investment cost.