What is meant by multiple-effect evaporator?

What is meant by multiple-effect evaporator?

A multiple-effect evaporator, as defined in chemical engineering, is an apparatus for efficiently using the heat from steam to evaporate water. In a multiple-effect evaporator, water is boiled in a sequence of vessels, each held at a lower pressure than the last.

Which of the following arrangements is used in multiple effect evaporation?

Explanation: Multiple effect evaporation usually uses sensible heat in the condensate to preheat liquor to be evaporated. Hence as the pressure drops significantly in subsequent effects, the feed is always flashed into these effects, thus the flash system is predominant. 8.

Which multi effects evaporator arrangement feed is introduced in intermediate effect moves forward and backward to first effects and steam introduced in first effect?

11. Mixed Feed arrangement  Feed is introduced in intermediate effect moves forward and then backward to effect-1 and steam introduced in first effect.

In which effect the product concentration will lowest for a backward feed triple effect evaporator?

Backward feed : The pressure in the first evaporator is highest and that in the last effect is lowest. If the solution is very viscous then we have to adopt a backfeed arrangement as the temperature of the first effect is highest and thus the corresponding viscosity of the solution will be less. Fig.

Why multiple-effect evaporator is required?

Introduction: Multiple Effect Evaporator (MEE) is a system used widely for many applications in industries to achieve evaporation and obtain desired concentration as output by using an efficient amount of heat source. The concentrate from the first effect is fed to the next effect to achieve further evaporation.

What is the advantage of multiple-effect evaporator?

Major Advantages of RDG Multi-effect systems: Reduced energy required to run full system. Reduced condensing load with additional effects (less cooling water needed) Liquor flow control. Convenient foul condensate collection and processing.

What are the advantages of multiple-effect evaporator over single effect evaporator?

Explanation: Advantages of multiple effect evaporators are suitable for large scale and for continuous operation. It is highly economical when compared to single effect. Multiple effects are used to minimize the energy input required to evaporate undesirable water content.

What is multi-effect?

Definition of multiple-effect : relating to or consisting of a series of evaporators in which the pressure decreases progressively from one to the next so that the vapor from each unit except the last heats the liquid in the next unit.

What are the disadvantages of multiple-effect evaporator?

Disadvantages are:

  • high head-room requirements.
  • higher pressure drop through the tubes than in a falling film evaporator.
  • hydrostatic head at the bottom of the tubes may increase product temperature and cause temperature-sensitivity problems.

What is multi effect evaporation?

Multi Effect Evaporation:- Multiple Effect Evaporation remains one of the popular methods used for the concentration of aqueous solutions. Water is removed from a solution by boiling the liquor in an evaporator and withdrawing the vapour.

How do you Calculate evaporation from two different effects?

1. Assume values for the temperatures of the first and second effects. 2. By means of heat-balance equations across each effect, determine the evaporation in each effect. 3.

How much water can be evaporated from a 7 stage evaporator?

‒ In seven stage evaporator, it is possible to evaporate 12kg of water with 1kg steam. No of effects Steam used /kg water evaporated Steam used /kg water evaporated (if TVR used) Single 1.2kg ————- Double 0.6kg 0.45kg Triple 0.4kg 0.25kg

How to calculate the heat transfer coefficient of evaporator?

Q= UA (Ts- T1) = Ms * Hs – MS* Hc = Ms * λ U=Overall heat transfer coefficient, W/M2K q=rate of heat transfer, W Steam Economy= MV/ Ms 21.  Assume area of all calendria same as A , & if no heat loss:  Steam Economy: [ Mv1 + Mv2 + Mv3 ] / Ms  Typical value of steam economy for a single effect evaporator is between to 2-3.