Multiple effect evaporators efficiently utilize heat from steam for evaporation and therefore finds use in sugar mills. These evaporators find use in industries like pharmaceutical, textile, paper and others that generate toxic effluents having over limits of BOD, TS, COD and TDS level with black effluent with an odour.
Working principle:
Multiple-effect evaporator involves water boiling in a number of vessels, where each vessel is held at lower pressure compared to the previous one
As the pressure decreases, the boiling temperature decreases
As vapors are transferred from one vessel to another, only first vessel (at highest pressure) needs external heat source support
Though in theory, evaporators can be made with a large number of stages, it is rarely evaporators with over four stages are rarely practical.
Manufacturing range:
The evaporator system heats surface areas according to defined process requirements
This system can be supplied within general range of 100 m2 to 4000 m2
The SS tubes are available within range of 3 m to 6 m length
Design Features:
Steel evaporators come in vertical tubular construction
Supported by SS pipes that come fixed along its length
All pipes and joints coming high pressure are tested to achieve maximum heating and process efficiency
Efficiently distributes steam with baffle plates
Optimally removes non-condensable gases, thus allows for better heat transfer
Less space is needed due to its long tube design
Allows for less inversion losses because of its less retention time of juice at high temperatures
Calendria designed with annular space and providing tangential steam entry of exhaust and exit of non-condensate gases from centre
Umbrella provided above top tube plate to prevent carry over juice particles through vapor
Enables attaining high brix of syrup
Applications:
Multiple effect evaporator finds application for -
Increasing solid contents
Concentrating dilute liquid
Reducing volume of evaporating liquid
It is utilized for concentration of liquids in three different forms-