Design and numerical simulation of inverted bucket pilot operated steam traps
LI Shu-Xun1,2, XU Deng-Wei1, LI Que1, WANG Chao-Fu1
(1. School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China; 2. Center of Engineering and Research for Pumps and Special Valves in Machinery Industry, Lanzhou, Gansu 730050, China)
Since the pilotoperated steam trap is subject to a high level of noise and a poor bearing capacity of pressure when it is operated under high temperature, high pressure and high flow rate condition, a new type pilotoperated stream trap, which is in shape of inverted bucket and is applicable for ultrahigh flow rate, was designed and developed in the paper. A Mathematical model was set up for the valve, and a twostage throttle sleeve muffler was designed according to the throttling principles of flow. A numerical simulation of threedimensional, turbulent flow in the valve was conducted by using the CFD code Fluent based on Reynolds timeaveraged N-S equations, the SIMPLEC scheme and the standard k-ε turbulence model. The results show that the maximum pressure, that the pilot valve can bear, is increased to more than 10 MPa from 6.3 MPa, the maximum working pressure of the pilotoperated steam trap is 8 MPa and its mass flow rate is as high as 30 t/h. By comparison and analysis, it is obtained that the internal flow field in the inverted bucket pilotoperated valve with a muffler is more uniform and the pressure is changed gradually; in consequence, cavitation is avoided effectively. The maximum pressure drop is decreased to 190.8 kPa from 247.7 kPa; accordingly, the total pressure drop is increased by 165.6 kPa and the pressure drop ratio rise to 0.56 from 0.18, further the level of noise is lowered by 33 dB(A). As a result, the result in the paper can provide a reference for the design of inverted bucket pilotoperated steam trap.
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