as we mentioned in previous articles, it is required to remove water and salts from crude oil for its bad effects on oil treatment equipment and processes, and we said that wet crude has to be dehydrated and desalted in Wet Crude Treatment Plant and talked lengthily about Optimizing Wet Crude Treatment and how to get better results in this type of treatment by using heat, electricity, wash water ratio and Pressure Differential through Mixing Valve.
for further information about this topic see Emulsion Treating Part 1 & Emulsion Treating Part.2 .
wet crude treatment is a very accurate process, and need a lot of attention to achieve better results, we have to understand this process in every detail to overcome the operation problems in this process.
and here is a full explanation about each operation problem, its causes and how to deal with:
——————————————————————————————-
High Oil Content in Wet Crude Outlet Stream.
Primary Causes:
– high wash water ratio, i.e; injecting too much water into wet crude stream.
– high water content in crude oil inlet stream, i.e; greater than the design limit.
how to solve:
– reduce the wash water ratio.
– increase demulsifier dose.
– you have to decrease the water content in crude inlet stream.
other cause:
– High Interface level.
solve: reduce the interface level, ensure that the produced water valve is working ptoperly.
other cause:
– irregularity in desalter level.
Solve: check the control valves, calibrate them if required.
High Salt Content in Wet Crude Outlet Stream.
1st cause:
– very high salt content in the crude inlet stream.
– low wash water ratio.
Solve:
– reduce the salt content in crude inlet stream.
– increase wash water ratio.
2nd Cause:
– crude oil flowrate is greater than the design limits.
Solve: reduce the flowrate to reach the design limits.
3rd Cause:
– no enough mixing between wet crude and wash water.
Solve: increase pressure drop across the mixing valve.
the Existence of Oil Droplets in Produced Water Stream.
1st Cause:
– thick emulsion interface.
Solve: increase demulsifier dose and drain all the emulsion.
2nd Cause:
– very low interface level.
Solve: increase the interface level, and check this level by manual level valves located along the vessel.
3rd Cause:
– Low crude temperature.
Solve: increase the crude temperature.
and finally check the wash water quality.
Transformer Current Fluctuating:
Cause: damage in the bushing used in isolating the cable coming from the transformer to the grids.
Solve: shut down the vessel, then replace the bushing.
High Transformer Current:
Causes: high water level.
Solve: decrease the water level.