Cooling Tower Power Failure

Cooling Tower Pumps Failure.

The cooling tower has a thermal capacity of 52200 kW. The temperature of the hot water is 38°C, the cold water is 28°C.

The total flow with 3 pumps is 4500 m3/h, 1 pump is stand-bye. The rated flow of a pump is 2500 m3/h, the TDH is 25 m WC.

Non-return or check valves are installed in the piping system at the discharge side of each pump to prevent the reverse flow of the water.

Of the possible choice of valves very slow closing valves specially designed (hydraulic dampened)to eliminate water hammer are chosen.

On the main at the pressure side op the pumps a vented air vessel is installed. During normal operation the air pressure in the air chamber is equal to the pump delivery head. When pumping stops, water flows out of the air chamber and the air pressure reduces. The greater the volume of the air the smoother the process. The system can be suitably dampened by throttling the chamber at the flow inlet.

A disadvantage of the air chamber is the necissity of providing a compressor to replace the air which is dissolved in the water and carried away in the pipeline. (see fig. below).

The first 2video's shows the results of the surge analysis with fast closing check valves. These are biased by means of spring loading.

The third video shows the result with very slow closing (hydraulic damped) check valves.