New Method for Designing an Energy-Saving Tray and Its Hydrodynamic Aspects:  Temperature Distribution and Efficiency of Deflected Tray-95

Abstract

A series of well-designed deflectors were placed on the tray-95 to improve the flow pattern. A phenomenon of multiple plug flow was observed in each liquid flow channel between two deflectors on the deflected tray-95. In compliance with the theoretical prediction, temperature profiles of the liquid layer on the tray were measured both vertically and horizontally by resistive thermal detectors. An oxygen desorption experiment was carried out, and the oxygen concentrations in the inlet and outlet liquids were detected by iodometry. Then the liquid-phase Murphree tray efficiencies (E ML ) were calculated. The results show that the well-designed and well-placed deflectors can obviously increase the tray efficiency by almost 30% under the same operating conditions.

The impact of valve tray geometry on the interfacial area of mass transfer

“…Thus plug flow, an ideal flow pattern, was roughly approached, as having been proved in our previous work. 18 Owing to the plug liquid flow being realized on the tray, the liquid residence time Dt can thus be expressed as…”

“…Four ideal deflectors were placed on the trays for distributing and regulating the liquid flow, so as to form a plug-flow pattern. 18 Three types of valves, Glitsch V-1 valve (V1), rhombic valve (RV), and double rhombic valve (DRV), as shown in Figure 3, were equipped and tested. The RV and DRV valves were invented and developed in our lab.…”

A nonequilibrium model for distillation processes

“…The EGR comes from the thermal conduction that takes place mainly in the gas and liquid bulks, thus To calculate σ q , the profile of temperature gradients on the industrial tray should be known. The temperature gradients are generated mainly along two directions13: the vertical direction, in which gas bubbles pass through the liquid layer, producing a temperature gradient of ∇ T ver ; and the horizontal direction, in which the liquid flows, generating a temperature gradient of ∇ T hor . According to the law of vector addition, the square of magnitude of the total temperature gradient can be written as …”

“…Similarly, the EGR in the liquid bulk (Θ) can also be formulated as Given that plug flow conditions are assumed for the liquid phase, ∇ T ver and ∇ T hor are constants13 that can be expressed as where h f is the froth height and l f is the distance from the inlet to the vertical section. Provided that the coefficient of heat conductivity λ on each stage is constant, the EGR for a stage resulting from ▿ T can be written as …”

Computational Fluid Dynamics Modeling of Hydrodynamics of a New Type of Fixed Valve Tray

“…Mass transfer tray column is an important type of gas–liquid contact equipment widely used in the oil refining and chemical industries, as it has features of easy maintainability, low cost, convenient feed, and side withdrawing. − Fixed valve tray, one of the major research and industrial interests recently, draws more attention as a hybrid of floating valve tray and sieve tray. In industrial practice, however, the performance of the trays always suffers from a loss of separation ability due to maldistributed or abnormal flow regime, for example, liquid phase circulation, which occurs frequently on a tray. − It has been long established that the prediction of distillation tray hydrodynamics is necessary for the separation efficiency and overall performance. ,,− Besides, the understanding of these two-phase hydrodynamic phenomena on trays is helpful for the fine-tuning and optimization of modern tray design. − The hydrodynamics of fixed valve tray is significantly influenced by the configuration and type of the valves, and the operating conditions, which, in turn, affect the product properties. − …”