Research On Operation Optimization Of Cold End System In Direct Air Cooled Unit

Due to the lack of water resources in Three North area of China,traditional wet cooling units can't be built normally because of the high consumption of water.Thus,direct air cooling technology attracts more and more attention currently.However,there are also some disadvantages.Because the cool air is used to replace circulating cooling water as the cold source of cold end system,axial flow fan needs to provide enough air to meet the cooling load of the condenser.This process would introduce the fan load.Besides,direct air cooling unit operation process is affected by working condition and environment multiply,leading the large range of the back pressure,pollution of the heat exchange surface,and so forth,which will influence the safe and economic operation of the unit severely.This work establishes the distributed model of direct air cooling island first and verifies the accuracy by actual operation data.Then,the research of variable condition features is proceeded based on the model to reveal the main factors that influence air cooling condenser pressure.And through the analysis of soot formation influence for flow and heat transfer characteristics of air outside the finned tube,this work attains the influence of dust for condenser pressure characteristics.So in order to guide the dust cleaning of condenser,this research builds the condenser pressure constant pattern model to quantify the degree of soot formation and propose the method to determine dust cleaning cycle.At last,economic back pressure and fan operation optimization research are carried out by calculating the mild-increase characteristics of output and the fan power consumption under the different benchmark conditions.Based on the economic calculation after optimization,the proposed approach can create enormous benefits.