Automatic Operation three-effect sodium hydroxide evaporative concentration (chemical products)
Multiple Effect Evaporation
Multiple Effect Evaporation remains one of the popular methods used for the concentration of aqueous solutions.
The chief factor influencing the economy of an evaporator system is the number of effects.
By increasing the number of effects we can increase the economy of an evaporator system.
The first effect of a multiple effect evaporator is the effect to which the raw steam is fed.
Vapors obtained from first effect act as a heating medium for another effect.
TVR or MVR is used in Multiple Effect Evaporators to use the dead vapors.
For an evaporator maximum boiling temp is 80℃ in first stage and 40℃ in the last.
Structure and performance characteristics
The evaporator consists of a heating chamber and a vapor-liquid separation chamber. The evaporating unit is composed of more than two evaporators, heat pump, inlet and outlet pumps of each effect, vacuum device, detection instrument, pipeline and valve. The heating chamber is mainly composed of shell, tube bundle distributing device and connecting pipe, while the vapor-liquid separation chamber is mainly composed of shell and foam thrower.
a. The unit can adopt the downstream continuous feeding method, or the countercurrent or mixed feeding method. The flow direction of the solution is the same as that of the heating steam, and the raw material is preheated to the boiling point by the preheater before entering the first effect. Since the boiling point of the pre effect solution is higher than that of the post effect solution, the material will become superheated and evaporate by itself when it enters the post effect solution. Meanwhile, part of the pre effect condensate can also evaporate by itself when it enters the post effect solution, so more secondary steam can be generated. In counter current feeding, the raw material is fed by the third effect and discharged by the first effect after the second effect. When mixing and feeding, the raw materials are fed by the third effect and discharged by the second effect after the first effect.
b. With the help of adiabatic compression, the saturation temperature of some primary and secondary steam in steam jet heat pump increases, and then returns to the primary heating chamber as heating steam, so as to improve the economy of steam.
c. The static distributor makes the material flow evenly and effectively in the inner wall of the tube after entering the feeding tube from the top of the heating chamber, so the heat transfer coefficient is greatly improved. At the same time, the temperature loss caused by the static head of the liquid column can be ignored, so the effective temperature difference of the falling film evaporator is large under the same conditions.
d. The residence time of the solution in the evaporator is short, so it is especially suitable for the evaporation of heat sensitive materials.
Multiple Effect Evaporators are widely used in the following areas as per the requirement.
Effluent Treatment: Industries like Chemical, Pharmaceutical, Textile, Dyeing, Breweries, Automobiles, Milk, Food industries etc, generates process effluents which are harmful to the environment. These effluents generally consist of water in huge amount and waste(contaminants). By evaporating the water from the effluent using MEE system results in the recycling of water.
Desalination: Reject of RO (Reverse Osmosis) have a huge amount of water. With MEE the water can be recycled.
Chemical Industry/ Pharma Industry: For the production of product the desired concentration is required or desired material need to be separated. Using MEE system desired concentration is achieved.
Milk Industry: Milk can be concentrated in the MEE system.
Sugar Industry: Sugar cane juice can be concentrated with MEE system.
Food industries: Tomato juice concentration, Sausages, Fruit juice concentration can be done in MEE system.
Advantages: Evaporation can be achieved with low consumption of heat source.
Typical three effect falling film evaporator specifications and technical parameters:
Vacuum degree of
Evaporation temperature of
Steam pressure for
|Solid content in feed(％)
|6-7(Corn pulp example)
|Solid content outlet(％)
|42-48(Corn pulp example)
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