Labyrinth Control Valve

Labyrinth Control Valve
Research and development have addressed a series of issues—such as cavitation, erosion, vibration, and noise—caused by high-velocity fluid flow in traditional single-seat control valves operating under high-pressure-drop conditions. These valves are suitable for demanding applications involving high pressure drops, such as high-pressure boiler feedwater pump recirculation [1], steam turbine desuperheating and pressure-reducing bypass systems [2], high-temperature and high-pressure steam venting [3], and process gas venting.

The labyrinth flow path is the critical structural element enabling the valve to achieve staged pressure reduction. Although labyrinth flow paths were adopted earlier in fields like labyrinth gas seals [4] and agricultural drip irrigation [5], their research and application in valves began relatively late. Determining the number of stages for labyrinth flow paths under high-pressure steam conditions represents both a key aspect and a significant challenge in the structural design of these valves. In this field, the US-based company CCI holds a leading position; meanwhile, domestic Chinese enterprises—such as Chongqing Chuanyi Control Valve, Beijing Aerospace Petrochemical Equipment, and Wuxi Yadi Fluid—have actively developed labyrinth valves by drawing on foreign designs, achieving substantial progress. Academia has also conducted relevant research. While literature [6–8] provides formulas for calculating the number of stages under various operating conditions, the results often deviate significantly from actual values, indicating a need for further refinement and improvement. Kwon et al. [2] utilized computational fluid dynamics (CFD) and finite element analysis (FEA) to design a labyrinth steam bypass control valve for power plants. Wang Ruoyu et al. [9] demonstrated through numerical simulation that, for a given number of stages and steam conditions, a higher expansion coefficient results in higher flow velocity and greater flow capacity within the labyrinth path; however, an excessively high expansion coefficient can trigger strong vortices at the flow path outlet, leading to severe erosive damage. Wang et al. [1] used water as the working medium to verify that series-parallel flow path configurations offer superior control over flow velocity and allow for reduced valve dimensions.