| 摘要 |
PURPOSE:To operate a cooling tower at a high temperature and to prevent freezing of the cooling tower, by controlling the speed of rotation and the balde angle of a fan such that the temperature of cooling water is controlled to a set value given as a function of the wet-bulb temperature of air introduced into the cooling tower, and keeping the temperature of a filler material higher than a prescribed value. CONSTITUTION:The output of a proportional integration controller 12 gives a set value for the temperature tc of cooling water in a cooling tower, and the deviation of the actual temperature tc of cooling water from the set value is detected by a succeeding subtracter 13. A second proportional integration controller 14 operates to control the deviation to zero, and the output of the controller 14 is furnished via a lower signal selector 17 to a rotational speed controller 18 which is adapted for controlling the speed of rotation of a fan driving motor. The controller 18 thus operates to control the speed of rotation and the blade angle of a fan for the cooling tower. Further, through detection of the deviation between the detected temperature tf of a filler material and the lower- limit value of the filler material determined by a lower-limit temperature setting means 15, a third proportional integration controller 16 operates to control the deviation to zero. |
