Drying is a highly energy intensive process – something that had been taken into account even when energy prices were only a fraction of the current prices (during the 1970-80es)- so it is imperative to have optimum control over drying as performed by the DNSZ moisture control device produced by us.
It is very important that the grain leaving the dryer should not contain more water than the moisture content with which it can be safely stored but it should not be drier either because over-drying causes significant loss.
Moisture value is checked in practice by small rapid moisture meters used with the towers, and occasionally exsiccator is also used to establish the moisture content of the grain.
The traditional controlling method is as follows: sample is taken on the bottom of the drying tower from the discharged grain in the volume of 100-200 g as needed for measuring. The result of the measurement is used for the calculation of the dryer parameters (flame, discharging) while the performance of the dryer is 10-30 r/hour. It is obvious that the volume of checked sample is negligible compared to the actually dried quantity.
Another problem is that the representative features of the sample depend also on whether the sample is taken at the beginning or end of the discharging process (in case of dryer with intermittent operation) and from which place the sample is drawn.
Moreover measurement takes place when the grain already left the tower, which means that intervention takes place subsequently, with delay.