Waste heat recovery

Increased number of effects in evaporation systems

The most effective way to lower steam consumption in evaporation systems is to increase the number of effects. Steam is recovered one extra time, reducing the need for fresh steam.

Example

Caustic soda evaporation

This example is taken from a 600 tpd caustic soda plant. Increasing the number of effects from two to three means the steam consumption is reduced by 6.5 tph (14,330 lb/h).

Rebuilding the preheaters reduces the steam consumption by another ton per hour. The total steam saving potential adds up to 7.5 tph (16,530 lb/h), equalling a 35%-40% reduction of fresh steam.

The total suggested investment amounts to approximately 2 million euro.

 

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Results

Evaporation systems

Payback period

Going from two to three evaporation effects

Payback period when improving preheating and increasing the number of effects from two to three in a caustic soda plant.

Payback period (years)

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