Multiple-effect evaporators Parallel feed

Parallel-feed multiple-effect evaporators. 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. 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. 

Patterns of liquor flow in multiple..effect evaporators (rz) forward feed b) backward feed (c) mixed feed d) parallel feed, (omn) Liquor streams. (-) Steam and vapor condensate streams. 

The feed to a multiple-effect evaporator is usually transferred from one effect to another in series so that the final product concentration is achieved in only one effect. In forward feed operation, raw feed is introduced in the first effect and passed from effect to effect parallel to the steam flow. The concentration of the liquid increases from the first effect to the last and product is withdrawn from the last effect. Forward feed operation is advantageous when... 

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