Regarding cooling tower fans
Thread Content
At what temperature of the circulating water should the fan be stopped? Middle and Lower Reaches of the Yangtze River
Generally, it should be below 30 degrees; the design for circulating water is usually set at 32 degrees. The fans can be made variable-frequency to enable automatic temperature adjustment
Thank you for your reply. Here’s the situation. Our fans are not variable frequency. If the fan is turned on and the circulating water temperature is low, the chiller always shuts down due to low pressure. If the fan is turned off, it will cause the exhaust pressure of the refrigeration unit to rise, resulting in an increase in power consumption. The fan has a power of 132 KW; when the fan is turned off, the power consumption of the refrigeration unit increases to around 300-400 KW. Obviously, it’s not as cost-effective as turning on the fan. So at what temperature does the fan shut down? At a design temperature of 32°C, this temperature will not be reached on such a day. Currently, the water leaving the cooling tower is at around 10°C, while the return water is at around 25°C.
Based on the provided circulating water temperature data, the flow rate of the circulating water appears to be low, resulting in a large temperature difference between the inlet and outlet； Improvement method: Without turning on the fan, increase the circulation volume of the circulating water to reduce the temperature difference; as the return temperature of the circulating water drops, it is also possible to reduce the load on the refrigeration unit.
The start and stop of the fan can be linked to the pressure of the unit: it starts when the pressure reaches a certain level, and stops when the pressure drops to another certain level
Part of the water goes up to the tower, while another part returns directly to the water tank without going up the tower; you need to determine the exact amount of water used to adjust the water temperature.
Thank you; we are currently using the method you mentioned. The weather has been too cold lately, so I can’t turn on the fan. The chiller can operate normally even with a low load; the exhaust pressure is slightly low, but it is sufficient for liquid supply.
Generally, two fans are installed at the top of a cooling tower; one fan is turned off when the temperature is below 27°C, and both fans are turned off when the temperature is below 25°C