Research On The Freezing Influencing Factors Of Indirect Air Cooling In Coal Fired Unit

With the increasing awareness of energy conservation and environmental protection,the indirect air cooling technology has developed rapidly in areas rich in coal and poor in water of our country.However,the performance of the indirect air cooling unit is greatly influenced by the environmental factors.The main problem is the air cooling radiator is easy to be freezing and the anti-freezing measures in use lack of basic theoretical guidance.In this thesis,the 300 MW indirect air cooling unit in Handan is studied theoretically under different operation conditions in winter.The anti-freezing models are set up for the indirect air cooling system.In addition,the FORTRAN software is used in the thesis.The change regulations of the anti-freezing parameters including anti-freezing back pressure of the steam turbine,the anti-freezing flow of the circulating cooling water and the freezing time of the cooling unit under the shutdown condition are studied emphatically.The factors such as unit load,ambient temperature,cooling water cycle ratio,shutter opening and the number of exiting sectors are considered in the model set up in the thesis.According to the calculation results,the main conclusions are as follows:(1)The influence of different factors on the anti-freezing back pressure and anti-freezing flow is obtained;(2)The time variation rule and range of water discharge under the condition of shutdown in winter is obtained.For the units under study,the suggestion that the time of water discharge in winter should be controlled in 100 s is given.These results can provide theoretical guidance for the safety and economic operation of 300 MW indirect air cooling unit in winter.