SEP Salt & Evaporation Plants Ltd. products
Multiple Effect Evaporation (MEE)
MEE is used when a large amount of water has to be evaporated and steam is inexpensive. The first effect is steam-heated, and vapour from the first evaporator heats the following (second) effect. The second effect vapour heats the third effect, and so on. By utilizing MEE, the specific energy consumption falls significantly. The number of effects ranges from 2 to 10, and is typically limited by the temperature difference between the heating and cooling media on the one hand and the optimum between investment cost vs. energy savings on the other.
Mechanical Vapour Recompression (MVR)
MVR technology utilises compression of the vapours generated in the evaporator to a higher pressure/temperature level, and are subsequently reused as the heating medium. High-speed centrifugal compressors, or a number of fans (operating in series at significantly lower speed than compressors) provide the compression.
Flash Evaporation / Crystallisation
Flash evaporation or crystallisation is used to cool a hot brine (and precipitate a compound) without heat exchangers coming into contact with the process liquid or slurry. It provides longer operation cycles for the evaporator or crystalliser, as the scale formation in equipment is reduced substantially. Feedstock is exposed to low pressure, and flashes (boils) under controlled conditions. The flash generates vapour is condensed separately. The removal of water concentrates and cools the feed and leads to precipitation of product crystals. Forced Circulation or Draft Tube Crystallisers are used for this operation as well as Flash vessels.
Recrystallisation
Recrystallisation is a purification process, in which impure crystals are dissolved in a clean solvent, and then recrystallized, to produce crystals that are significantly purer (10X or better) than those used for the feedstock. The actual method of crystallisation can be that of evaporation or cooling, depending upon the solubility of the product; usually the recrystallisation operation is a repetition of the first crystallisation unit. Recrystallisation is typically used for products that require high levels of purity (usually >99.9%), such as pharmaceutical grade or reagent grade components.