1 reply to this topic

[chem55]

Dear All,

I searched on internet that there are various arrangements for desalter such as:

1) single stage desalter
2) dehydrator and desalter in series
3) two desalters in series

http://www.gastechen...alters_more.php

Question 1: When to use heater upstream of the desalter? I learnt from internet that target viscosity for desalter is between 5-7 cP. Doest it mean if the crude viscosity is between 5-7cP, heater is not required?

Question 2: When to use dehydrator and desalter in series arrangement? As far as i understand, most of the water is removed in three phase separator located upstream of dehydrator/desalter arrangement. If most of the water is removed, why dehydrator is required? Also again water is injected between dehydrator and desalter. I understand that this additional water is required for desalter but then what is the purpose of dehydrator if water being injected again after dehydrator?

Thank you..

[Zauberberg]

1. Heating upstream of desalter is required in order to achieve optimum conditions for emulsion breaking and liquid-liquid phase separation. This normally does not happen at low temperatures. Depending on the type of crude oil processed and operating pressure of the desalter, this temperature varies from 100-150 degC. Optimum separation conditions are usually determined during field/laboratory tests, and this provides more accurate information than the viscosity comparison.

2. Dehydrators cannot break water-oil emulsions, and they are used when significant amount of free water is present in the oil. The purpose of desalter is to remove the emulsified water and to extract inorganic salts (water-soluble) from crude oil, which cannot be done in single-stage dehydrators.

Two desalters in series are used when extremely efficient salt removal is required, for protection of the equpment downstream.
NATCO website can provide you with some additional information.

Attached Files

•  How to buy and operate desalters.pdf   1.05MB   140 downloads