倒吊桶先导式蒸汽疏水阀的设计与数值模拟

针对高温高压大排量下先导式蒸汽疏水阀噪声高、导阀承压能力低的问题,设计并研制了一种新型超大排量倒吊桶先导式蒸汽疏水阀,建立了其数学模型,并基于节流降压原理设计了两级节流套筒式消声器.以连续性方程、三维雷诺平均N-S方程和基于各向同性涡黏性理论的k-ε方程组成疏水阀内部流动数值模拟的控制方程组,采用结构与非结构网格相结合的有限体积法对控制方程组进行离散,应用CFD软件Fluent对阀内流动进行三维湍流数值模拟计算.结果表明：该先导式蒸汽疏水阀采用倒吊桶疏水阀作为导阀,使导阀最大承压能力由目前的6.3MPa提高到10 MPa以上,最高工作压力8 MPa,排量可达30 t/h.通过对比分析可知：加消声器后,阀内流场变得均匀,实现了压力的渐变,有效防止了空化现象的发生,最大压降由247.7 kPa减小到190.8 kPa,总压降增大了165.6 kPa,压降比由0.18提高到0.56,降噪量为33 dB（A）.

Design and numerical simulation of inverted bucket pilot-operated steam traps

Since the pilot-operated 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 pilot-operated stream trap, which is in shape of inverted bucket and is applicable for ultra-high flow rate, was designed and developed in the paper. A Mathematical model was set up for the valve, and a two-stage throttle sleeve muffler was designed according to the throttling principles of flow. A numerical simulation of three-dimensional, turbulent flow in the valve was conducted by using the CFD code Fluent based on Reynolds time-averaged 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 pilot- operated 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 pilot-operated 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 pilot-operated steam trap.