Study On Design Optimization Of Direct Air Cooling System For Coal-fired Power Plant

In this paper, firstly, it discusses the main influencing factors of direct air-cooling unit, and then analyzes the regularity of environmental temperature, wind speed and other environmental factors affecting the environment direct air-cooling unit, And also describes the freezing phenomena of low temperature air-cooling tubes in the winter period,at last analyzes such freezing phenomena reasons, which provide some direction of improving the economics of air-cooling unitsThe optimal design of the Initial Temperature Difference(ITD) plays an important role in improving the economic efficiency of the direct air-cooling system. In view of the two factors of air-cooling unit fixed investment and operating costs, according to principles of thermodynamics and heat economics this paper establishes a minimum target annual cost of the objective function, in addition to considering the air-cooling radiators and the investment costs of fans , the number of years of construction, investment rate of return, engineering, economic life, equipment maintenance costs and the local water are taken into account, This paper studies a case of 600MW of direct air-cooling unit in some area, than optimizes and obtains the best ITD values systematically and the minimum total annual cost. At the same time, the prices of coal, the prices of air-cooled radiator, the cost of electricity, water temperature and the design sensitivity are analyzed, at last following factors are obtained: the prices of coal, the prices of air-cooled radiator, the cost of electricity, the ITD relationship curve when the design temperature and water total cost value change. Graph shows: with the increase in coal prices, the best ITD value decreases, the minimum total annual cost increases; the prices of air-cooled radiator increase, the best ITD values increases, the minimum total annual cost also increases; the lower of designed temperature, the higher of the value of best ITD, corresponding that the minimum total annual costs are lower; With the increase in the cost of electricity, the total cost of air-cooling system increases, the best ITD value also increases; With the price of water increases, the total costs increases, but the best ITD value is less affected, this is mainly because that the water consumption rate of air-cooling unit is low, especially in direct air-cooling unit. this paper has important reference value both in the design and operation of a direct air-cooling system.