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Dryers Taking Flash Drying to the next (Temperature) Level

Editor: Dominik Stephan

With ever–increasing energy prices, it is an economic and ecological necessity to reduce the footprint of energy intensive drying processes. Sometimes, non-thermal, mechanical drying, can be used to remove liquids first before thermal drying.

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Especially the combination of lowering the inlet moisture, together with the increased inlet temperature can save up to 75% of the energy cost.
Especially the combination of lowering the inlet moisture, together with the increased inlet temperature can save up to 75% of the energy cost.
(Picture: Hosokawa Micron)

Although the combination of mechanical and thermal drying is optimal from an energy point of view, it is a very demanding challenge for the thermal dryer. Here the Hosokawa Micron Dryer has proven its worth over more than half a century to dry mechanically pre–dried products in a consistency. The Micron is classified as a direct flash dryer, meaning the product is in direct contact with the drying medium (normally air). One of the disadvantages of direct dryers is that the drying medium is leaving the dryer at a higher temperature than ambient. These losses are normally referred to as 'stack losses'.

How to Avoid Stack Losses With Dryers

There are a few ways to reduce these stack losses: One method is to cool the gasses going to the chimney by preheating the air flow into the dryer – a method which is commonly used in heater boilers for households. A more evident way to reduce the stack losses is to reduce the amount of air to be used in the dryer. The only way this can be done without reducing the evaporating capacity, is by increasing the inlet temperature. In recent applications an inlet temperature of 650°C has been applied, thus saving more than 25% of the energy required compared to more moderate inlet temperatures.

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A Combination of Methods

Especially the combination of lowering the inlet moisture, together with the increased inlet temperature can save up to 75% of the energy cost. The amount of savings on the variable cost is evident from that. An extra bonus is not only a dryer with a unprecedented high energy efficiency level, but maybe even more important, the dryer size with it’s peripherals that can be smaller.

A smaller dryer with the associated ancillaries can be up to 30% less in investment level for the owner of the dryer.

Powtech: Hall 7, stand: 260.

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