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Evaporation is the thermal separation process that is used for the concentration of various liquids in the form of suspensions, solutions, and emulsions. Evaporators or evaporation units use this principle for the treatment of process water, waste water and water based waste. The typical liquid treated is a water waste with organic and inorganic pollutants. Evaporators are defined as machines used to change liquids into gases in order to treat the water and make it less or uncontaminated. Evaporators are also used for treating scalding liquids or concentrated acids and corrosive liquids. They use heat pump, hot water or steam, or Mechanical Vapor Recompression (MVR), with natural or forced circulation methods for treating water. These machines may be fuelled by electricity, oil, natural gas, liquid propane or steam.
Functioning of Evaporators: Evaporators are machines built and designed on the principle of evaporation. Evaporators follow the process by which steam is first created and after that the evaporator machine collects the contaminants, and reconverts the steam into fresh uncontaminated water. The process begins with the liquid being collected in a holding tank, where it is pumped into the evaporator as it is being gradually heated to a boiling point. As steam is released more liquid is being fed into the evaporator through the holding tank, creating a continuous stream of liquid and steam release process. The steam created is then blown out through the mist eliminator, producing high quality distilled water which is then re-circulated through the system.
Application of Evaporators: Evaporators are used to separate water from concentrated saline solutions, oil emulsions for recovering oil, bilge waters. Evaporators are also used in fishing industries, aluminum and paper mills, steel mills, chemical and fertilizer industries, textile finishing and synthetic fibre plants. Evaporators are put to use for crystallization, volume reduction, and water/solvent recovery. It is useful in situations where wastewater disposal is a problem, whether it is a company or residence. Indicators of such problems include paying too much for waste water disposal, having difficulty in keeping wastewater within specific limits, or being in an area which lacks proper sewage disposal mechanisms. Evaporators have a wide variety of uses in a number of industries. These units are used in processing alcohol, chemicals and foods. Some of these devices are used in the petroleum industry for recovering gas, recycling of liquids and off shore drilling. Evaporators are also used in the production of plastics, in the pharmaceutical industry, in pulp and paper manufacturing plants, Evaporators find utility in food and agricultural processing industries to reduce the moisture content of a dilute liquid product to a more concentrated product.
Types of Evaporators: There are five main types of Evaporators namely, Falling Film Evaporators, Rising Film Evaporators, Plate Evaporators, Forced Circulation Evaporators and Thermal and Mechanical Vapour Recompression.
Water Evaporators: Water Evaporators are machines designed to efficiently evaporate the water content from most non-volatile water-based liquids. A power exhaust system releases the moisture safely into the air leaving only a small residue requiring disposal. There are many well designed machines in the market that help in this process of massive reduction in the volume of liquids and economizing by reducing the storage area requirements, time and frequency of disposals. These machines are designed to operate simply and efficiently and constructed of quality material. Its use is found on ships where there is frequent need to make pure water out of seawater. The process involves boiling the brine cooling it to condense out purified, distilled water. The water thus obtained is used not only for drinking and but also for consumption by ship`s boilers, which make steam that powers the turbines.
Wastewater Evaporators: Wastewater Evaporators are used to solve the problem of waste water disposal. The technology offered through machines is based on boiling the waste water and the water once distilled is reused in the production. The contaminant can be disposed off at relatively low cost. The product to be distilled is sucked into the evaporator with the help of the vacuum circuit. The cooling cycle equipped with a heating pump is able to get heat the liquid in treatment and to cool the vapours produced in the boiling phase. Distilled liquid and the processed residue are then unloaded at the end of the distillation process.
Industrial Evaporators: Evaporators installed for treating industrial waste and waste water are usually heavy units. The manufacturers have come out with machines that are energy efficient and environmentally friendly. There are two types of heavy duty evaporators. These are electrically driven Mechanical Vapor Compression Heavy Duty Evaporator and Thermal Vapor Compression Heavy Duty Evaporator driven by pressure steam. These units are used for industrial plant effluent treatment, waste water reclamation and recycling of water in industrial plants. Their application is required in pulp and paper industries, chemical process industries, textile plants and oil fields.
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