PURPOSE: To control the concn. of the liq. concentrate in the evaporator constant by measuring the driving power for rotating a spiral heat exchanger and adjusting the discharges of feed and discharge pumps to fix the driving power.
CONSTITUTION: A pulley 14 for rotating a spiral heat exchanger 4a is rotated by a driving motor 4d through a power transmitter 4c such as a belt. A current is applied to the motor 4d from a power source 11 through a current signal converter 9. A controller 10 receives a signal from the converter 9 and adjusts the discharges of the liq. feed of discharge pumps 2 and 7. Meanwhile, a level sensor 12 is provided in the evaporator 4, and the discharges of the pumps 2 and 7 are adjusted based on the signal to make the level in the evaporator constant. Since there is a positive correlation between the driving power for the heat exchanger rotating in the liq. and the liq. viscosity, the concn. of the liq. concentrate in the evaporator is controlled constant by controlling the amt. of liq. to be fed or discharged to fix the driving power.
SATO AKIRA
FUJIOKA YUICHI
