(45b) Complex Atmospheric Preflash Configurations

Atmospheric distillation is the first major processing step in refining crude oil. Just over half the atmospheric distillation units include some type of preflash drum or preflash tower. Increasing unit capacity is the most common reason for adding a preflash to an existing unit.

Preflash configurations can be very complex. The following configurations are discussed in this paper;

1. Preflash tower with a reboiler.
2. Preflash tower with steam stripping.
3. Preflash tower with a shared overhead system with the atmospheric tower.

Characteristics of each type are presented along with comparisons for different types of crude oils covering the range from 20 to 50 API degrees.

Recommendations on which types to use in different situations are included.