Research On Characteristics Of Internal Flow In300MW Direct Air-cooled Condenser

In recent years, direct air cooling unit has been widely used in some of ourregions in where the coal is rich and water is shortage. Due to the structure ofdirect air-cooled condenser is large and working medium has a phase transition，resulting in uneven flow distribution of each condenser unit，the difficulty ofrunning adjustment is increasing and have a great impact on the operation of unitsafety and economy. Therefore, the study of each unit condenser steam flowdistribution has important significance for the evaluation of the performance ofthe condenser.Based on the method of hydrodynamic calculations，and collating of theresearch achievements and experience formula in pipe process steam condensationprocess and gas-liquid stratified flow，establish a method only for researching theflow characteristics in direct air-cooled condenser. A300MW direct air coolingunit in Shanxi as an example, using hydrodynamic calculations, and using Fortranlanguage，a flow resistance algorithm about different pipe is established. Theinternal flow model of direct air cooled condenser was built using the method ofmodularization on the platform of IMMS. Based on the model, the distribution ofexhaust steam and heat exchanger was reveal under different load and heat conditions.This paper studies the flow characteristics of a row of direct air-cooledcondenser when the flow, heat transfer coefficient of every unit has a change. Whenheat transfer coefficient of the first unit increasing, the flow of the first unit alsohas an increase, the others would reduce. Adjusting that of the third, there willhave a same tendency. And the flow of the fourth has a huge change. So it shouldbe slowly to adjust the heat transfer coefficient of third unit to prevent the flow infourth unit is too little which will threat the safety of crew.The differences among each column’s flow distribution of air-cooledcondenser were analyzed. The structural difference of main exhaust pipe is animportance reason. It proposed that the differences of flow distribution in thecolumns can be substantially eliminated by adjusting the functioning of the fanreasonably. But at the same time, the unreasonable way of adjustment is an important factor that causes the differences.