Patent ID: 7614613

Claim:
In a gravity fed cooling tower liquid return system wherein said cooling tower system contains a plurality of cooling cells, each said cell being fed heated return liquid by way of an individual sub-header, each said sub-header being in fluid communication with a common header having a vertical height, at least one but not all of said sub-headers being connected to said header at a location higher on said vertical height of said header than the remaining at least one lower sub-header, said at least one higher sub-header carrying manually controlled valves, each said sub-header having a liquid carrying cross-sectional interior area, the improvement comprising providing a distributed control system and an open riser on each of said sub-headers, said risers being in fluid communication with said interior areas of their respective sub-headers, each said riser carrying a liquid level detector/transmitter for determining the height of the liquid level in each said sub-header and transmitting same to said distributed control system, each said at least one lower sub-header carrying an actuator operated valve, each of said liquid level detector/transmitters associated with said at least one lower sub-header being in operative communication with its corresponding actuator valve on its sub-header, sensing said liquid level in said interior of each of said sub-headers, in said distributed control system comparing said liquid levels in said at least one higher sub-header with said liquid levels in said at least one lower sub-header, and controlling by way of said at least one lower sub-header and associated actuator valve said liquid levels in said at least one lower sub-header to be approximately the same as said liquid level in said at least one higher sub-header, whereby said liquid carrying cross-sectional area in said sub-headers is essentially balanced.