Optimization of circulating water pump settings
Thread Content
This post was last edited by A sword rainbow on 2015-9-23 at 15:39. There is now a cooling tower system consisting of three separate cooling towers; one of these towers has a processing capacity of 400 m3/h, while the other two have a processing capacity of 200 m3/h each. In normal operation, the cooling tower with a processing capacity of 400 m3/h remains operational at all times ； Most of the time each day, one cooling tower with a capacity of 200 m3/h needs to be in operation; for a short period, two such cooling towers must be used simultaneously. There are also about 3 hours per day when neither of the 200 m3/h cooling towers is needed. How can the circulating water pump system for a cooling pool be configured to minimize investment costs and energy consumption? 1) Install three circulation water pumps with a capacity of 400 m3/h each; two of these pumps shall be equipped with frequency converters to meet the requirements of a cooling tower system with a processing capacity of 600 m3/h ； 2) Install two 400 m3/h circulation pumps and two 200 m3/h circulation pumps ； ......
It’s not necessary to use the variable frequency setting very often; the other two options involve ordinary pumps. Generally, the normal capacity requirement for a cooling tower is 600 m3, with a maximum of 800 m3 and a minimum of 400 m3. A temperature sensor is installed on the return water pipe, with interlocking connections to the other two pumps. When the return water temperature exceeds the set value, the second pump is activated; if the temperature still doesn’t drop, the third pump is turned on as well. A control circuit can be established for the flow rate of the third pump in relation to the temperature. When the return water temperature drops to the interlock value, the third pump is shut down; the same applies to the second pump.
It is recommended to install 4 pumps; for systems requiring 400 cubic meters of capacity, one pump in operation and one as a backup are needed, while for the other systems with 200 cubic meters of capacity, one pump per system is sufficient. No frequency converter is required
Two at power frequency, two at variable frequency; one frequency converter is used to control the two pumps, along with a PLC automatic controller equipped with a touch screen
Install 5–6 pumps with a flow rate of 200, arranged in the pipeline in a manner that allows for flexible switching and combination; they can also serve as backup pumps, with interchangeable spare parts. The use of variable frequency is not recommended; reducing the frequency lowers both the flow rate and the head, which may fail to meet the operational requirements.