Research On Steam Distribution Of Air Cooling Island In1000MW Power Plant

Along with our country gradually setting up a scientific concept of development ofconservation-minded society, the development of the energy field is full ofopportunities and challenges. As a basis of energy consumption industry, the electricpower industry is the lifeblood in the development of national economy at the sametime, so to solve the problem of reasonable use of resources is the top priority. As a newcooling technology, direct air-cooling technology in power plants has been researchedand applied for50years, and achieved great success. But in actual operation, thecomplexity of the structure of exhaust steam pipelines and the pressure loss will lead tothe uneven steam flow distribution, this could not only cause steam turbine backpressure fluctuating, but also make the rotating speed of fans more difficult to beadjusted, so uneven steam distribution in air-cooling island should to be solved as soonas possible.This thesis set a model for a1000MW direct air-cooling unit exhaust steam pipe,simulated steam flow distribution from mother pipeline to branch pipelines, leveldistributing pipelines to the air-cooling unit, and the flow distribution in finned tubes ofthe unit under the TMCR (Turbine Maximum Continue Rate) condition, putted forwardtwo improving measures; According to the calculation of pressure loss in exhaust steampipeline, this thesis analyzed how the pressure influenced the steam distribution, andcalculated the optimal proportion of fan rotating speed to steam flow rate based on theresult of steam distribution in every unit.The results of the study showed that, steam flow distribution from mother pipelineto five branch pipelines is almost uniform, mass flow rate and the pressure loss areinversely-proportional; Due to the effect of the guide vanes, reducing pipeline, andconvex slots structure, steam can’t flow steady at these positions, resulting in biggerdifference of the steam distribution from level distributing pipelines to the air-coolingunits; When steam flow from level distributing pipelines into finned tubes, verticalcohesion of the convex slots can cause vortex district, which influences the steamflowing into finned tubes and leads to the uncondensed steam flowing back to finnedtubes. By using the presented guiding slots, the steam flows smoothly, and the massflow rate to every finned tube is reasonable; According to the simulating results of thesteam flow rate and the output of the fan, the best fan rotating speed was determined,which saves fan energy consumption, and improves the economical operatingperformance of the power plant.