(351am) Exploration of the Gas-Liquid Vibration Mechanism for Industrial Float Valve Tray

Gas-liquid vibration is a unique operating phenomenon caused by the flowing of gas and liquid phases when the distillation tray is operating at an extremely low gas load. The mechanical fatigue is easily caused when the distillation column is operating under the condition of gas-liquid vibration for quite a long time. It is easy to induce the occurrence of equipment resonance when the frequency of gas-liquid vibration is close to the natural frequency of the equipment. At the same time, the high energy of vibration can easily cause mechanical damage, even cause major safety accidents such as explosions and fires. Therefore, it is essential to carry out research work on the gas-liquid vibration phenomenon of distillation columns.

In this paper, the mechanism and hydraulic characteristics of gas-liquid vibration have been investigated in detail based on an industrial-scale two-pass rectangular simulator (6400×800 mm²) with the air/water system combining with multiple-point pressure measurement. The main results are as follows:

â‘  Based on the energy analysis of gas-liquid phases in the VCFC model of the float valve tray and combined with the principle of minimum energy, and it is concluded that the continuous bubbling and weeping region cannot be able to exist stably at the stage of gas-liquid vibration but change with the time being. At the same time, it is proved that zero hydraulic gradient on the tray is one of the necessary conditions for the occurrence of gas-liquid vibration.

â‘¡ It is confirmed that the formation of the large size of bubbles with low-frequency is the second necessary condition for the occurrence of gas-liquid vibration through the experimental research on the Glitsch V1 float valve and Super V1 float valve.

â‘¢ The specific reason that the gas and liquid phase fluctuated and the formation process of gas-liquid vibration are explored by analyzing the fluctuation pressure signal and the process of energy conversion of gas-liquid phases.

â‘£ By setting the vibration experiments on the counter-flow column, it is proved that the essence of gas-liquid vibration is the interaction between the liquid layer pressure on the tray and the gas chamber pressure below the tray, at the same time, the liquid that jumps through the downcomer intermittently owning to vibration has little effect on vibration characteristics.

⑤ The experimental results show that the liquid height on the tray and weeping fraction in each section are distributed homogeneously due to gas-liquid vibration. However, the uniformity of distribution of liquid height and weeping fraction on industrial float valve tray becomes worse under the conditions of high weir height and high liquid flow intensity compared with the experimental results of the small-scale float valve tray, which is the scale-up effect also exists in the region of gas-liquid vibration. Furthermore, the heterogeneity of hydraulic characteristics becomes more evident with the increase in the number of valves and liquid flow intensity.