In some petroleum refining plants, preflash drums are placed in between the desalters and the atmospheric columns as part of the crude distillation unit. Located in the preheat train of the distillation column, a preflash drum system separates the vapors generated by preheating before entering the heater or main column. This prevents higher heater firing or pressure drops and reduces vapor loading of the column to avoid flooding. Using preflash drums can also increase crude capacity when revamping and make the desalting process more efficient.
Magnetrol® has produced an applications brochure for the petroleum refining industry detailing measurement challenges and solutions for each step of the refining process. This blog post is part of an occasional series exploring each application in detail.
Level Measurement Challenges and Considerations
Preflash drums create moderate foam that can affect measurement accuracy of liquid levels and decrease distillate production in the atmospheric column. Instruments used in preflash drums must be able to accurately and consistently monitor level despite this foam.
In addition, level must be precisely monitored in the preflash drum. Too low of a preflash drum level will cause pump cavitation of the flashed crude. Too high of a level will cause liquid carryover to the distillation column. Only the most reliable level instrumentation should be installed in preflash drums.
Level Measurement Solutions
MAGNETROL has produced level measurement solutions to protect preflash drums and monitor them accurately:
For point level:
Series 3 float-actuated external cage level switch
For continuous level:
Eclipse® Model 706 guided wave radar transmitter or E3 Modulevel® displacer-actuated transmitter
For visual indication:
Atlas™ or Aurora® magnetic level indicators can be supplied with switches or transmitters
For more information on level solutions for preflash drums and other petroleum refining applications, download the petroleum refining brochure.