Research On Optimization Of Compressed Air Drying System In Coal-fired Power Plant

Compressed air is an important power source and is widely used in the pharmaceutical,power,chemical,food and other industrial fields.The compressed air system is an indispensable public system in the thermal power plant,compressed air is required for systems such as heat engine,thermal control,ash removal,and desulfurization,to some extent,to ensure the safety of the compressed air system,that is to ensure the safety of the entire plant power production.During the purification process of compressed air,the removal of water is a necessary step,how to effectively remove the moisture contained in the compressed air is of great significance for the safe and economic operation of the fire unit.The conventional ash-removing air drying system uses the micro-heat-absorbing dryer to dry the compressed air,in northern China,the winter rain and snow weather is longer and the air humidity is increased,leaded to increase the load of the micro-heat regenerative dryer and the dehumidification capacity of the dryer has decreased,so it was easy to cause problems such as ice blockage in outdoor gas pipelines and affect the safe operation of the unit.In this paper,combining the characteristics of low winter ambient temperature in northern China,based on the principle of cooling and dewatering of wet air,outdoor cold air was used to cool down the compressed air,and a compressed air condensation heat transfer drying optimization system was proposed.A typical 2×300 MW unit was selected,based on the analysis of the unit ash removal gas purification and drying system,builded an optimization model for condensation heat transfer system.After analyzing the characteristics of the condensing heat transfer,the regenerator and the condensing heat exchanger in the condensation heat exchange system selected all-welded plate heat exchanger and the heat exchanger plate selected an ultra-wide channel drum package sheet,the numerical simulation study was carried out on the selected heat exchanger plates.On the basis of numerical simulation research,the design calculation of condensation heat transfer system was carried out.After the condensation heat transfer optimization system was put into the engineering field application,combined with the actual heat transfer conditions of the site,based on the average temperature difference calculation method,the calculation model of the coupled variable working condition of the condensation heat transfer system was built,calculated the working conditions of the partial operating data and discussed the causes of the data errors.The results showed that the calculation results are in good agreement with the actual operating parameters,and the feasibility of the condensation heat transfer system was verified.From the field operation data analysis,the condensation heat transfer system was stable in winter,more than 80%of the water is effectively removed,meeting the water requirement of the ash removal gas,the dehumidification effect is good,and the temperature after the compressed air is reheated is between 23? and 27?,far away from the pressure dew point,to meet the design requirements,to ensure the safety of the gas pipeline and gas system.The research results of this paper provide a new idea for the gas purification and drying system of thermal power unit for ash removal,and have practical application value.