Dryer Flow Schematic
Left Desiccant in
Regeneration
Dryer Valve |
Regeneration
Blower
Regeneration
Filter Insulated
Drying
Hopper
Regeneration
Heaters
Regeneration
Exhaust
Process
Heater
Process |
Filter |
Left Desiccant
Right Desiccant
Process
Blower
Sequence of Operation
When the dryer is started, the main air valve rotates 360º and then moves to place the last successfully regenerated desiccant bed online. If the dryer was powered off using the main power disconnect or
If the closed loop regeneration option is enabled, the regeneration closed loop valve moves to the open loop position. The system always begins the cooling phase for a regeneration cycle using ambient (open loop) air. The closed loop regeneration valve is allowed a period of time to move from the closed to the open loop position and a “Closed Loop Valve” alarm is generated if the valve fails to reach the commanded position within this time. This alarm will disable the regeneration circuit but does not stop the process air system or drying hoppers.
Once the main air valve and closed loop regeneration valve are in place, the process air blower starts. The system monitors the process air blower’s overload, starter auxiliary contact feedback and air pressure. Loss of any of these items when the process air blower is running will cause the process air blower and the drying hopper’s process heaters to shut down.
The process air heaters will turn on after a delay to allow the process air blower to accelerate the operating speed.
During normal operation, one set of desiccant beds is connected to the process air circuit while the other set is being regenerated. When the offline beds are done regenerating, they will be switched into the process air circuit and the other beds will be regenerated. The default bed switch setting is based on time. If the Dewpoint Switch option is enabled, the beds will switch when the process air dewpoint reaches the dewpoint switch point. The dewpoint option will automatically disable itself and an alarm will be generated if the dewpoint sensor or related electronics fail.
Large Dehumidifying Dryers | Functional Description | 14 |
