Abstract:

Based on the property of forming rotating flow field around the valve cover after gas passing through valve, rotary float valve is applied to aeration tank to improve its oxygenation performance. By assigning evenly 6 bubble stones around the rotary float valve, a rotary float valve-bubble stone composite aerator is formed. The aeration performances of the composite aerator were experimentally characterized in an organic glass aeration tank with an inner length, width and height of 800mm×600mm×910mm, by using an air-water system. In order to investigate the effect of the rotating flow field formed by the rotary float valve, the typical column internal unit F1 float valve and the common bubble stone aerator were introduced as experimental controls. The experimental results showed that the dissolved oxygen concentrations at the central and the boundary measuring points of the rotary float valve-bubble stone composite aerator were closer than those of F1 float valve-bubble stone composite aerator. The oxygenation uniformity index of the former was lower than that of the later. It was shown that the rotary float valve could promote the distribution uniformity of bubbles and decrease the dead zone for mass transfer. The rotary float valve - bubble stone composite aerator can improve the oxygen transfer coefficient, oxygen transfer rate, oxygen transfer efficiency and aeration efficiency compared with the F1 float valve-bubble stone composite aerator. The rotary float valve-bubble stone composite aerator can improve the oxygen transfer coefficient, oxygen transfer rate, and reduce oxygen transfer efficiency and aeration efficiency compared with the bubble stone aerator. Computational fluid dynamics (CFD) was introduced to simulate the flow field distribution and explicate the generation of rotary flow field and the reasons for the improvement of oxygen aeration capacity of rotary flow field in the aeration tank.

Key words: rotary float valve, aeration, numerical simulation, oxygenation uniformity index, CFD

摘要：

基于气体通过阀片后能在阀盖四周形成旋转流场的特点，本文将旋转浮阀应用于曝气池中，以提高其充氧性能。在旋转浮阀四周均匀排布6个气泡石，即旋转浮阀-气泡石复合曝气器；在长宽高为800mm×600mm×910mm的透明有机玻璃池内，以空气-清水为体系，进行曝气实验。为了考察旋转浮阀形成的旋转流场对曝气的影响，以塔内件领域常见的F1浮阀以及气泡石为基准进行实验比较。结果表明，与F1浮阀-气泡石复合曝气器相比，旋转浮阀-气泡石复合曝气器的中心测量点与边界测量点的溶解氧浓度更接近，充氧均匀性指数也更小，说明了旋转浮阀能促进气泡分布均匀，减少传质死区。相比于F1浮阀-气泡石复合曝气器，旋转浮阀气泡石复合曝气器提高了氧总传质系数、氧传质速率、氧传质效率和曝气效率；相比于气泡石曝气器，旋转浮阀-气泡石复合曝气器提高了氧总传质系数、氧传质速率，但降低了氧传质效率和曝气效率。本文还利用CFD模拟流场分布，解释了旋转流场的产生及其提高曝气充氧能力的原因。

关键词: 旋转浮阀, 曝气, 数值模拟, 充氧均匀性指数, 计算流体力学