With the motto “there is nothing that one can not improve” the engineers from Donaldson intensively worked on advancing the Boreas series. These energy saving refrigerant compressed air dryers for medium to high volume flows now use even less energy. The new generation of Boreas dryers are equipped with the new innovative Variopulse control.
This electronic control on microprocessor basis sequentially measures the data of the sensors, which give information on the current status of the refrigerant compressed air dryer, evaluates these signals with the dryer-specific parameters and on the basis of this evaluation sends out control signals, with which among other things the refrigeration agent and the fans are controlled. The substantial advantage of this very accurate control is that one can do without a hot-gas bypass, which from an energy as well as economical point of view only destroys energy and causes operating costs.
With the smallest sizes of the Boreas series, which are presented in a new, clearly more compact housing, the Variopulse control makes use of an energy saving suction pressure control. This always guarantees that only approximately as much refrigerant agent is compressed, as is needed for the safe, reliable operation and generation of the defined pressure dew point.
For the smallest sizes with flow rates from 1.800 to 2.800 m3/h the suction pressure control proves to be the most efficient concept. For all other sizes up to flow rates of 28.500 m3/h the principal known to compressed air compressors of speed control by using a frequency converter is used. One of the desiccant compressors operating as peak load compressor is equipped with an adjustable transmission (according to series up to 3 refrigerant compressors can be installed in one dryer). Thus, the refrigerating capacity of the compressed air dryer is no longer lowered or increased in gradations, but is continuously adjusted to the actual demand.
On the permanently lit up display of the Variopulse control, the operator can read off all data and information important for the dryer operation. Apart from this, the Donaldson service or the in-house maintenance department can, with a laptop, pick out all data over the standard CAN-bus interface. All relevant information e.g. the stored pressures and temperatures as well as the adjusted parameters can in this way be viewed and/or documented. If a disturbance arises, the Variopulse has a self-diagnostic system, which indicates the error code in the display. Errors e.g. lack of refrigerant agent or defective sensors can directly be recognised. Optionally the control can also be integrated into a remote electronic data transmission network.
First practical applications of the new Boreas Variopulse dryers clearly demonstrate the advantages of the new control concept: The pressure dew point is constant at +3°C without any dew point peaks, in the part and zero-load ranges the capacity sinks to around 90% in comparison to electrical capacity at nominal load, and because of the lit up display the operability has been improved considerably.
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