| Electric power, the basic of modern industry, plays an important role in national economy. It's significant to research the power plant set and its components. As the main tool to generate electricity, Steam turbine have an important impact on the efficiency of energy consumption level and the economic indicators of the plant. This paper analyze the problems found (heat consumption deviate from the design values) in the operation of a 600MW steam turbine which is manufactured by Japan's Toshiba. We found that import efficiency in high, medium and low-pressure cylinder is lower, which lead the heat consumption is higher than its design value. We will target the reasons for the low efficiency of low-pressure cylinder, Focus on the inlet air flow field and their organization's performance in this regard were analyzed.First of all, by using the ANSYS CFX software, the paper carries out a three-dimensional calculation on the steam flow in low pressure cylinder, getting to know the flow field distribution, and the coefficient of drag, the loss of pressure and the velocity of flow in some situation will come to a result. In addition, a numerical simulation is also carried into the inlet parts of the low pressure cylinder respectively designed by Westinghouse and Siemens company. By giving numerical simulation to these three low-pressure steam system manufactured by three different company, and compare them to analyze its aerodynamic performance of design principles,which can make a structural improvements to the Toshiba model program.Based on the above analysis, we conducted a top-down improvements of the Toshiba structural model. By using CFD numerical simulation method to calculate the flow field of various programs, we find the key factors that have impact on the efficiency of the section of the flow field . For example ,we have added a baffle in the inlet pipe, added a smooth flow channel into the steam pipe in the corner at right angles,all these improment project can improve the flow status of the region with varying degrees of success. Finally, we will be screening the various improvement programs, and then chose the best one that is feasible.The study work of this paper provide some constructive advice in a way to the structure designed of inlet system of the low-pressure cylinder. In the design, we can optimize the structure, improve the aerodynamic performance of the inlet path of low-pressure cylinder, make the pressure losses drop,improve the efficiency of the first stage of low-pressure cylinder, reaching the purpose of energy saving, so that economic benefits have also been greatly improved . Work in this area for exploration, not only provide an effective way theoretical and experimental basis for new product development, improvement of existing products, but also have great reference value for the economics of power plants. |
