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This series operate on the "Pressure Swing" Principle. Pressure swing dryers regenerate desiccant bed by expanding a portion of dried air to atmospheric pressure. This swing in pressure when passed through the desiccant, picks up moisture from the desiccant pores which were loaded with moisture in the previous adsorption cycle.

Internally Heated Dryer.

These are heat regenerative dryers. Heater is installed in the desiccant bed. Wet inlet air is directed through the drying tower where moisture is absorbed on the desiccant. A small portion of the dry outlet air is diverted to the regenerating tower. It flows the dry outlet air is diverted to the regenerating tower. It flows downward over the heater and then upward through the bed where it collects moisture from the desiccant. Wet air is exhausted to atmosphere through the purge valve.

Blower Reactivated Dryers.

Wet air form compressor is passed through one of the bed which is in adsorption mode and thus dries the air.

For regeneration, normally atmospheric air is used, through the blower. (Regeneration at pressure in closed loop is also possible.

Blower starts and the air is passed through heater, where it gets heated up to the designed temperature and then enters the bed. After regeneration moisture laden air is exhausted to the atmospheric through silencer.

When the regeneration temperature is reached at outlet of the bed, then heater will be switched off and blower now continues blowing air through the same tower to cool down the reactivated desiccant.

These can also be designed for counter current heating and co-current cooling.

The compressed air coming from compressor is split into two different streams.

Regeneration flow is the fixed, calculated flow. With the help of flow transmitter, required regeneration flow is maintained, irrespective of the demand.

Regeneration air is then passes over an electric heater and this hot air is diverted to pass through the bed, in counter current mode where it picks up moisture from the bed and the same is passed separated out of the cooler and separator.

Then this air gets mixed up with the other stream and then enters the tower which is in adsorption mode. The moisture is adsorbed and dry air goes out to the net.

During cooling the heater is switched off and the air is diverted to enter bed in co-current mode.

These can also be designed for counter current heating and co-current cooling.

Heat of Compression Dryer.

In this type of dryers hot air from the last stage of compressor is fed to one of the towers (May be partially or fully depending on the design.), which desorbs the previously loaded bed, and the same is passed through the properly sized intermediate cooler and high efficiency separator.

The air in case of full flow system, goes straight to other tower, gets dried and goes to the systems.

In Case of partial flow, only a part of air goes through the regeneration bed, and after cooling, it gets mixed up with the main incoming air.

Control of this dryer has to be perfect one, as no preset time is taken for regeneration; moreover the regeneration depends on compressed air demand and hence in each cycle, the flow has to be measured and the cycle time has to extended proportionately, in case flow required per unit time is lower than the design flow.