Experimental Study Regarding The Effects Of Forced Ventilation On The Performance Of Wet Cooling Tower

Natural draft wet cooling tower is widely used in modern thermal power plant. Its performance directly affects the safety and economy of the power plant. With the increasing capacity of new units, the increasing demand of the tower cooling performance is becoming more and more exigent. The cooling tower is becoming large in scale at present, which makes the inlet air distribution inhomogeneous. The impact of the crosswind on the tower cooling performance also turns greater as the tower becoming larger. For thermal power units which have been running for many years, the tower cooling performance deteriorates. It is therefore necessary to employ some appropriate methods to improve the tower cooling performance. For the thermal power units in water shortage area, the cooling performance of the wet cooling tower is relatively low, so some mechanical ventilation cooling towers are also constructed to enhance the cooling performance of the power units.Ventilation is an important thermodynamic parameter in the design and evaluation of wet cooling tower. The tower cooling performance is obviously intensified with the larger ventilation rate. So the forced ventilation method can be used to optimize the performance of the cooling tower, which is valuable in practical application. But at present, there are still no studies on the effect of forced ventilation in the wet cooling tower.Through the thermal physical model of the cooling tower, this paper studied the influence of forced ventilation in wet cooling towers experimental performance in both the windless and crosswind conditions. The main work is as follows:(1) Taking a cooling tower of 1000MW power plant as a prototype, the cooling tower thermal physical model was established based on the similar criteria. The inlet water temperature, circulating water flow, the ambient room temperature and the size and range of simulation crosswind were determined. In the cooling tower model, the outlet atmospheric temperature and humidity measurement points are arranged. The outlet water temperature measurement points are arranged within the sump, the appropriate measuring instruments and data acquisition systems are selected. In order to meet the needs of the experimental research, the model is equipped with a forced ventilation system, a fan of appropriate power and power regulator are selected, the installation location and the length of the blades of the fan are determined.(2) The effects of forced ventilation on the wet cooling tower performance in the windless condition are analyzed.1. The study of the forced ventilation location. This article selected three positions location above the packing、the center of tower, throat of tower. Through the analysis of experimental data, we found that as the installation height increases, the cooling tower performance decreased. The fan installed above the packing is the best choice.2. The effect of compulsorily ventilation quality is studied by changing the fan power. It is found that compulsory ventilation contributes to the cooling ability of cooling tower, which means the more ventilation makes the cooling ability better.3. Two different fan blade lengths are compared. It is found that the longer the fan blades are the better the cooling ability is. The influence law of two kinds of blades on cooling ability is the same.(3)The effect of compulsory ventilation on cooling ability of wet cooling tower under crosswind condition is also studied.1. The effect of various power of the fan on cooling ability under crosswind condition is studied. The correlation of the compulsory ventilation and cooling ability is obtained, the cooling ability under crosswind is better when the power of the fan is higher.2. According to the average status of operation condition, the effect of compulsory ventilation on cooling ability under single crosswind condition is studied. The increase of cooling ability become slower with the increase of fan power, which indicate that there exist an optimum compulsory ventilation. The economy of compulsory ventilation is discussed according to the experiment results.The model tower is based on similar theory, so the result can be applied to the practical application. It is valuable in both academic as well as an industrial point of view.