PURPOSE: To enhance the operating efficiency by monitoring the consumed wind quantity in case the number of compressors is controlled according to change in the load, comparing the quantity with the suppliable wind quantity, and commanding rank down or rank up according its magnitude.
CONSTITUTION: An arrangement in which a plurality of compressors 1 (11, 12,..., 1N) are driven by drive motors 21, 22,..., 2N, and discharged air from the compressors 1 is stored once in a receiver tans 7 to then be supplied to the loads 9a, 9b,..., is equipped with a pressure sensor 10 to sense the discharge pressure and ones 101, 102,..., 10N to sense the suction pressure of the compressors 1. On the basis of signals therefrom, the consumed wind quantity and suppliable wind quantity are calculated by a number-of-compressors control device 40, and the two wind quantities are compared. When the consumed wind quantity changes up or down from the suppliable wind quantity specified at the current rank, a rank below or above the current rank is selected to perform control of the number-of-compressors.
NAGANO KATSUHIKO
MORITA HIROMI
KAMIYA HIROYUKI
FUJIWARA YOSHIAKI
SHIMOYU YOSHIO
OTANI MIKIO
KOBE STEEL LTD