What is backward feed?

In the forward feed, the flow of the solution to be concentrated is parallel to the steam/vapour flow. In the backward feed, the flow of the solution to be concentrated is in opposite direction to that of steam/vapour (counter current).

What are the different modes of feed in multiple-effect evaporator?

Explanation: The different modes of feed in multiple effect evaporators are forward feed arrangement, backward feed arrangement, mixed feed and parallel feed arrangement.

What do you mean 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.

What is parallel feed evaporator?

Parallel feed in multiple-effect evaporators involves the adding of fresh feed and the withdrawal of concentrated product from each effect. The vapor from each effect is still used to heat the next effect.

What is backward feed evaporator?

A multiple-effect evaporator can also operate in the backward-feed arrangement, in which steam and sugar juice flow in opposite directions.

What are the advantages of backward feed triple effect evaporator?

Backward feed is advantageous and gives higher capacity than the forward feed when the concentrated liquid is viscous, because the viscous fluid is at higher temperature being in the first effect. However, this arrangement provides lower economy as compared to forward feed arrangement.

Why backward feed operation is used when the concentrated product is highly viscous?

(b) . Backward feed is advantageous and gives higher capacity than the forward feed when the concentrated liquid is viscous, because the viscous fluid is at higher temperature being in the first effect.

How does a multiple effect evaporator work?

In a multiple effect evaporator, water is boiled in a sequence of vessels, each of which is at a lower pressure than the last. As the boiling point of the water decreases with pressure, the vapor produced in one vessel can be used to heat the next vessel. Only the first vessel requires a source of external heat.

What is the difference between single effect evaporator and multiple effect evaporator?

Economy calculations are determined using enthalpy balances. The economy of a single effect evaporator is always less than 1.0. Multiple effect evaporators have higher economy but lower capacity than single effect. The thermal condition of the evaporator feed has an important impact on economy and performance.

What is single effect evaporator?

A conventional evaporator is heated by steam which condenses and transmits heat energy to the solution to be evaporated. As this solution boils it in turn releases vapor which may: – Either be condensed in a condenser, in which case the process is known as “single effect” 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.

Which principle is used in concentration of juice by using multiple effect evaporator?

Steam economy dictates the application of the multiple effect principle. An appropriate installation makes use of a quadruple or quintuple effect arrangement with sufficient capacity to evaporate the water and is so designed to provide vapor for juice heating and vacuum pan operation.

What are the advantages of backward feed multiple effect evaporator?

Advantage of Backward Feed Multiple Effect Evaporator : – This method of reverse feed is advantageous when the feed is cold since a smaller amount of fresh cold, liquid must be heated to the higher temperatures in the second and first effects.

What is multiple effect evaporator?

Application of Parallel Feed Multiple Effect Evaporator : – This method of operation is mainly used when the feed is almost saturated and solid crystals are the product, as in the evaporation of brine to make salt. fConclusion : The multiple effect evaporation process can be configured in forward, backward, or parallel feed.

What is backwarded feed?

Backwarded Feed The backward feed arrangement is very common arrangement. In this arrangement the dilute liquid is fed to the last effect and then pumped through the successive effects to the first effect. The method requires additional pumps (generally one pump in between two effects) as shown in the fig. 9.6.

What is a parallel feed evaporator?

Parallel Feed Another common evaporator arrangements, which is more common in crystallization is parallel feed where feed is admitted individually to all the effects. The vapor from each effect is still used to heat the next effect.