What is vacuum evaporation
Evaporation is the change of state from the liquid to the gaseous state which, in the presence of a vacuum, takes place at temperatures lower than the boiling temperature at atmospheric pressure, thus making it possible to benefit from considerable energy savings. Through this technique a non-volatile component is separated from a solution, thus obtaining demineralised water and a final product more concentrated in the other components.
Vacuum evaporation plants are intended for low-temperature concentration of heat-labile diluted solutions or for the treatment and purification of polluting wastewater generated in the various processing stages of industrial companies.
Through vacuum evaporation it is possible in many cases to recover precious raw materials from the wastewater, reduce disposal costs by concentrating the wastewater to be disposed of and create zero discharge plants, ZLD Zero Liquid Discharge.
Choose the type of evaporator
Choosing the type of ievaporation plant most suitable for each individual need must take into account various factors. The nature of the product to be treated determines the choice of version (with immersed or forced circulation exchanger, with scraped exchanger, with jacketed exchanger...) as well as the choice of the most suitable construction material.
The next choice must be made considering the most suitable energy supply by evaluating energy costs and the availability of low-cost heat sources.
It is possible to choose between an exclusively electric power supply which, by applying the so-called "heat pump" system, allows for extremely simple installation, or using any hot water or steam flows already available in the company, perhaps exploiting thermal waste by recovering heat from the production process.
Both systems, electric or thermal, can be made in single, double or triple effect versions allowing for significant energy savings.
Special features of heat exchangers
A peculiar feature of the ECO ETW evaporators is undoubtedly the adoption of a particular construction conformation of the heat exchangers which simplifies their cleaning operations.
The heat exchangers, being the hottest point and therefore subject to frequent deposits of possible incrustations and dirt, are subject to periodic maintenance operations to restore their optimal operating conditions. The classic immersed coil or shell and tube heat exchangers have the limitation of having a very limited space between the different components and do not allow easy cleaning of the exchange surfaces.
ECO ETW evaporators adopt "immersed plate" heat exchangers which have the characteristic of having a free space between one plate and another of about 4 cm. Through a large front hatch it is easy to access the exchangers to carry out periodic washing operations and restore the heat exchange efficiency through a simple washing with a pressure lance.
Each exchanger is also made providing for the possibility of being able to easily carry out any disassembly and extraction operations.