Application Of Thermo-Economics Theory In Economy Analysis Of Air-Cooled And Condensing Unit

Air-cooled systems in power station where air is used as cooling medium are applied widely in some low cost mining and cold regions of rich coal and water shortage because they can economize a great deal of cooling water. With the above advantage of water-saving exceeding 65%, development of air-cooled unit in power station is extensive in the future at the wide region where primary energy is rich and water is lack. However, the cooling function of air-cooled system is subjected to the environment seriously, particularly the motion of the environment temperature causes scope of steam turbine backing pressure to be bigger and lowers economy and safety of unit. This urgently requests the research and engineering personnel to study how the environment influences air-cooled unit machanics.The paper investingates three kinds of air-cooled units in the domestic and international power station,generalizes structure,technique,craft, economic, characteristics etc. about three kinds of air-cooled units, carries on comparing their merits and demerits from multiangle,and points out proper condition. It is systematically introduced that example of three kinds of air-cooled systems that applied in the paper,and particularly according to weather,resources and region characteristics,the power station adopted the special design structure and operational way,technique standard etc. During the course of analysis of operational data for many years, some domestic air-cooled units still exist a lot of problems currently,economic index sign of its main technique of air-cooled unit can not reach the equal capacity wet unit,their margin is obvious, the main respresetation is high rate of plant consumption,high power feed coal consumption, low stream turbine efficiency,low vacuum etc.,and there is bigger margin than that of the foreign of the same kind. In all kinds of evaluation systems of air-cooled unit economy,almost all analytical methods base on traditional thermodynamics theory and have never considered the function of the economy factor, so their conclusions is unilateral, not perfect, some even fal se. To develop the air-cooled unit strongly, it is necessarily to lower the coal consumption possibly at the time of the saving water. To make in fact now economic operation,evaluation systems of air-cooled unit economy must be carried on research urgently.The paper generalizes the concrete contents, purpose, function, domestic and international development condition and trend of the thermo-economics researches. It elaborats the thermo-economics analysis method systematically and the matrix mode theory of the thermoeconomics method particularly. It explains the basic concept of the thermoeconomicsand clarifies some mutually repeat and contradictory concept. It improves the establishment principle of cost allocation equation and makes it adapt pratical situation more. It proves the closeness of thermoeconomics equation and makes a clean sweep of the theories obstacle for building up the matrix equation of thermoeconomics.With thermo-economics analysis method, the paper uses its standpoint to list the matrix equation of three air-cooled units,solves exergy cost of exery energy flow. It analyses how environment temperature and load of unit influence on internal energy flows of unit and output works exergy cost of each cylinder. It compares the environment temperature and unit load how to influence degrees of three kinds of air-cooled units. Theanalysis result indicates that operational cost and exergy cost of output work about direct air-cooled unit is lower than indirect air-cooled unit, and various exergy cost of surface air-cooled unit is better than mixed air-cooled unit. Therefore, the policy to develop strongly direct air-cooled unit agrees with theory and also is completely right at present.