Oil desalting plants

Oil extraction is constantly accompanied by formation water (from 1 till 80–90% by weight), which is dispersed in oil and forms water-in-oil emulsion types (dispersion phase is oil, and internal phase is water). Their generation and stabilization are fostered by oil natural emulsifying agents (asphaltenes, naphthenes, gums) and dispersed mechanical impurities (clay, sand, limestone and metal particles). Formation water, as a rule, is substantially mineralized by chlorides Na, Mg and Ca (up to 2500 mg/l of salts even if oil water content is only 1%) and also by sulphates and hydrocarbonates and contains mechanical impurities.

Presence of the above substances and mechanical impurities in oil has a negative influence on refinery equipment operation:

• At large water content pressure in oil refining plants rises up, their capacity is reduced and energy consumption is increased
• Salt deposition in furnace and heat exchanger pipes requires their frequent cleaning, reduces coefficient of heat transfer, causes heavy corrosion (chlorides Ca and Mg are hydrolyzed with HCl formation); moreover, salts and mechanical impurities, cumulating in residual oil products (black oil and tar), worsen their quality.

Oil dehydration is made by means of breaking of oil-water emulsion with use of demulsifiers — various surface active agents, which are adsorbed in interphase boundary and thus facilitate droplet (globules) breakup of the water dispersed in oil. However even at deep oil dehydration with formation water content up to 0,1–0,3% (which is technologically complicated), due to its high mineralization residual chlorides content is high enough: 100–300 mg/l (in terms of NaCl), and it goes higher when oil comprises crystalline salts.

Therefore for preparation of oil refining works of most oil fields the only dehydration itself is not enough. Residual salts and water are deleted from oil with the help of another process — oil desalting — which principally does not differ from oil dehydration very much. The process lies in mixing oil with fresh water, breaking of formed emulsion and further separation of flushing water (containing salts and mechanical admixtures having passed over to it) from oil.

A differential characteristic of the units is the combination technology of alternative and direct currents in the oil separation process, which considerably increases separation range and the plant efficiency per unit of volume.

Advanced updated design of separate units.

Inlet sleeves are made with double sealing which excludes oil leakage, and metal-to-metal thread levels down its stripping.

Up-to-date insulation materials having higher thermal characteristics and lower weight allow considerably decreasing weight load upon the unit, reducing its weight and increasing its operation life. Due to application of new insulation materials plant vapour cleaning becomes possible.

Max. salt content in oil at the plant outlet is 5 mg/l.