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What is the solution for water carry-over from the feed tank to the desalters?
 
Answers
19/07/2010 A: Jayaraj Jayam, Chennai Petroleum Corporation Limited, njayaraj@gmail.com
While receiving crude to your crude tank, keep the mixers of the tank on, so that water particle will not get trapped in sludge layer. It is obvious that the crude tanks will accumulate sludge in due course. After complete the receipt switch off the side mixers, allow the tank content to settle at least for 24 hours without disturbing and then drain water in controlled manner. That is drain water from the tank by pinching the drain valve to minimum. The last layer of water can be drained by keeping the drain valve by one or half of a turn opening. Drain till little crude issues through drain. Don't violate environmental regulations. Drain only to water oil sewer system.
Check sample from the suction level for any free water. If you operate in cold country, keep the steam coil or heating coil on before drain water. Ensure that rain water is not entering your tank through leaky roof drain. Even after these much of preparations, you receive free water in the feed, plan for clean the tank because sludge accumulation in the tank might be very high.
09/04/2010 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
1. Is it a "running tank" instead of a "still tank"? Should be the latter. Not enough time between filling and pumping out?
2. Pumping the tank too low?
3. Swing line set too low?
09/04/2010 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
You need to either have a rigorous program to draw water off of the tank bottoms to prevent slugs of water getting into the crude charge or to use tank mixers so that any water in the tank stays mixed in with the crude. Putting an online water analyzer in the crude feed line can be useful at detecting slugs of water before they hit the desalter. It doesn't stop anything but it does give some advance warning so that you can take early countermeasures to minimize the duration and extent of any problems caused by a slug of water.