Analysis Of Operation Characteristics For Direct Dry Cooling And Wet Cooling Combined System

There are two methods of cooling system for thermal power generation, dry cooling and wet cooling. Direct dry cooling system has the advantages of simple equipment, good heat transfer effect, no needs of large cooling tower area, flexible operation and good anti freezing performance, but the direct dry cooling system greatly affected by environment conditions, with a high electric power consumption, high back pressure in summer time. Wet cooling system has good cooling effects, but the consumption of water and equipment investment is large. Dry cooling and wet cooling have obviously advantages and shortcomings. Combined cycle system has both advantages and not only can be used in water-shortage north area, but also can be used in relatively water-abundant southern area.This paper firstly introduces the definition and classification of power plant cooling system and their operation characteristics, according to their respective advantages and disadvantages identified separated combined cooling system as the main research object. Separated combined cooling system consists of direct air cooling and wet cooling, according to the empirical formula of condense system of power plant(including steam turbine, air condenser, fan, wet condenser, circulating water pump, cooling tower) in mathematical modeling and analyzes the main influence factors of condenser pressure, puts forward the calculation principle of condensers and their process of iterative calculation, then regards water consumption of cooling tower as a major economic calculation.Then taking the 600MW unit as the research object, scale and rated dry cooling and wet cooling system operating conditions as a reference value. The typical environment conditions were selected, determine the optimal operating condition of each scale, and with the minimum annual cost method as a measure to ensure the best scale. Finally put forward scale design methods for different distribution flow rate, draw the different sizes of condensers and tower. With the minimum annual cost method as an economy measure, obtains the different condenser and cooling tower investment cost’s design.This study issue sub separated direct dry cooling and wet cooling combined cycle system as the research object. Through mathematical calculation of different water and electricity price, investment cost, to obtain the optimal operating conditions and the size of annual share the cost minimum, provide the reference for the optimal operation of combined cooling power plant.