Research On Change Law Of Water Loss And Method Of Water-saving In Cooling Towers

The evaporation loss is an important part of water loss in cooling tower and also is the maximum water consumption in thermal power plants. Evaporation loss not only brings great economic loss to thermal power plants but also pollutes the environment by forming white fog on the top of cooling tower. Therefore research on the change law of evaporation loss and measure to reduce the evaporation loss is of much practical significance.This paper takes a certain natural draft counter-flow wet cooling tower of 300MW generating unit for example and studies the change law of evaporation loss with inlet water temperature and inlet water flow on most summer condition and on most winter condition by the calculation model of evaporation loss. Following laws are concluded from the calculation results. Firstly, when inlet water temperature decreases and the other parameters keep constant, the evaporation loss decreases both on summer condition and on winter condition, evaporation loss rate per unit heat dissipating capacity increases on most summer condition, evaporation loss rate per unit heat dissipating capacity decreases on most winter condition. Secondly, when inlet water flow decreases and inlet water temperature keeps constant, the evaporation loss decreases both on summer condition and on winter condition, evaporation loss rate per unit heat dissipating capacity increases on most summer condition, evaporation loss rate per unit heat dissipating capacity decreases on most winter condition.In the common cold end system, when the load of condenser keeps constant, evaporation loss does not change with circulating water flow. It is impossible to reduce the evaporation loss by adjusting the circulating water flow. Both changing inlet water temperature and changing inlet water flow can change the inlet water heat. This paper studies the change law of evaporation loss with inlet water heat. It finds that the evaporation loss decreases when inlet water heat decreases. So, this paper proposes that it recycles and reuses the waste heat in circulating water by heat pump in order to reduce the evaporation loss. This method saves both water and energy. This paper studies the law of water saving with heat load of evaporator and the influence to the cooling temperature.This paper analyzes the economic benefit of heat pump-warm air heater and heat pump-low pressure heater. This paper analyzes the condition that the system of heat pump-warm air heater can save the coal. It will save coal and water to apply the system of heat pump-warm air heater on a certain 300MW generating unit. This paper analyzes the condition that the system of heat pump-low pressure heater can save the coal. Under present technology, it will not save coal to apply the system of heat pump-low pressure heater on a certain 300MW generating unit.Research results of this subject lay a theoretical foundation for water-saving of cooling tower. The method that it recycles and reuses the waste heat in circulating water by heat pump in order to reduce the evaporation loss points the direction of water-saving in thermal power plants.