The Method of Designing Multiple Overflow Trays by Equal Residence Time Method

Abstract

The invention relates to a method designing a multi-overflow tray by an equal residence time method, which is intended to raise tray mass transfer efficiency and processing capability, and alleviate amplification effect of equipment. The method is defined by residence time of the liquid on a tray bubbling zone, integrates advantages using an equal channel length method and an equal bubbling area method, takes regard of a contraction effect of a tower wall to a liquid flow and influence of physical property condition on the flow, and provides a calculating formula of the channel length in the tray bubbling zone under the equal residence time. Downcomer weirs on the edge at two sides of the tray are in a backswept weir structure, in order to increase overflow circumference length of the downcomer at two sides. A lower edge of an eccentric downcomer uses an arc or tooth-form structure, in order to balance a bottom gap outlet area of the downcomer. A liquid distribution plate is arranged in a liquid accepting plate, in order to balance liquid flow distribution at two sides of the downcomer. The method enables the liquid flow on each tray bubbling zone to have similar residence time and mass transfer efficiency, and achieves effects of reasonably distributing liquid, promoting gas and liquid uniform distribution and alleviating amplification effect of the tower equipment. The method is particularly suitable for large-scale tower equipment with high gas-liquid phase load.

Description

technical field [0001] The invention relates to a method for designing multi-overflow trays by an equal residence time method, belonging to the technical field of petroleum and chemical processing industries. Background technique [0002] Tower equipment is a commonly used vapor-liquid mass transfer equipment, which is widely used in petroleum and chemical processing industries. At present, plate towers are generally used in large-scale industrial installations. The plate column usually adopts the form of vapor-liquid two-phase cross-flow contact, figure 1 A schematic diagram of the vapor-liquid contact in the tower. Generally, there is a liquid level drop along the liquid flow direction between the inlet of the tray and the outlet weir, which will cause uneven distribution of the height of the liquid layer on the plate. With the expansion of the scale of the tower equipment, due to the increase of the liquid-holding inertial force on the plate and the increase of the numb...

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Problems solved by technology

In comparison, the equal channel length method is more reasonable in terms of design because the residence time of the liquid in each bubbling area is close, the flow is more uniform, and it has higher mass transfer efficiency and is conducive to the stability of the operation. However, the area of ​​the edge bubbling area on both sides is much smaller than the central bubbling area, which will affect the flow pattern on the tray and the distribution of vapor and liquid in the edge area.

The equal bubbling zone area method has a relatively uniform vapor-liquid distribution due to the equal area of ​​each bubbling zone, but the liquid residence time in the central zone is short, which affects the mass transfer efficiency

Moreover, whether it is the equal bubbling area method or the equal flow channel length method, the problem of uneven distribution of the liquid flow of the eccentric downcomer mentioned above and the influence of the shrinkage coefficient of the tower wall have not been solved.

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