In the CDU Desalter can we use one demulsifier for different Crudes. Is it possible to test effectiveness of the Demulsifier in Laboratory?
Answers
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29/03/2014
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A:
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Berthold Otzisk, Kurita Europe GmbH, Berthold.Otzisk@kurita-water.com
Modern demulsifiers are designed to give a good performance over a wide range of different crude oils. It is not a common practice to change each time the demulsifier, when new crude oils are processed. Some refineries switch all 2-3 days to other crudes and such a practice would require a set of different demulsifiers, which is not practicable.
There are several laboratory methods available, which will give an indication of the demulsifier performance.
A simple demulsifier test:
1) Intensively mix 1000 ml crude oil with 50 ml water
2) Put centrifuge glasses into a rack and fill each glass with the crude oil/water mixture
3) Keep one sample as the „Blank“ = no injection of a demulsifier
4) Add 10 ppm demulsifier to the crude oil/water mixture. Same procedure for all demulsifiers, which you would like to test
5) Intensively mix the crude oil/water/demulsifier samples
6) Leave the centrifuge glasses in the rack for 24 hours
7) Compare the demulsifier samples with the blank
A more powerful test is the „Portable Electrical Desalter (PED)“, which uses an electrical field. The test equipment is fixed in a suitcase. It is a static test, but gives more or less realistic results. This test equipment contains a heating block for the centrifuge tubes and electrodes, fixed in the screw cap.
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