Numerical Simulation And Design Optimization Of Large Diameter Vacuum Steam Piping System Flow Field

In order to content the increasing demand of electricity market,and respond positively to the enforcement of nation,working to develop more efficient and more energy conservation and environmental protection of large capacity thermal power unit is imminently.However,the key technologies of direct air-cooling system monopolized by foreign companies,and domestic air cooling faces many technical embarrassment,as well as the calculation method of conventional hard for this complex flow field calculation.Therefore,it is necessary to simulate the flow field of large diameter vacuum steam pipe to determine flow resistance.Through the collection and analysis of simulation results and learn the total pressure drop of each exhaust pipe flow and the distribution of the entire pipeline system,and guide optimal design of exhausted pipe.The thesis set a model for a direct air-cooling unit exhausted steam pipe,and the flow distribution in finned tubes of the unit under the THA(Turbine Heat Acceptance)condition.The flowing filed of steam in direct air cooling exhausted duct for power generating unit is simulated via Computational Fluid Dynamics(CFD) software,comes distribution about flow rate and pressure drop in each distribution pipe.Numerical simulation is carried out in the exhausted pipe with different angle of chamfering in the back,studying on distribution about flow rate and pressure drop in each distribution pipe installed before and after back chamfering,try to find the influence of different back angle of flow and pressure drop.Proposing the best arrangement of piping through analysis and researching the simulation results,and provide help for further optimization design of large diameter pressure steam piping system.The measurement result indicated that the flowing distribution each pipeline uneven flow distribution,and the total pressure drop also vary in the THA,and incorporate is: the flow assigned to the branch pipe 10 is the largest,which the branch pipe 1 has smallest flow,both differ within 1.5%-2.0%,other branch flow distribution is uniform,the difference of flowing rate maximum is not exceeding 7%,otherwise the total pressure drop will be 368.164366.143 -Pa Pa. The different influence of steam flows with piping with 30°,45°,60°,75°,105°angle on the back of large diameter exhaust negative pipe.In the best case of chamfering angle,the steam flows through each distribution pipe with balanced flow under the condition of chamfering angle of 30 °and the pressure is much lower than before,at the same time reducing the pressure on local area rise phenomenon,it lay a solid foundation for the development of large scale thermal power air-cooled exhaust piping system.