Duplex overflow weir capable of promoting vapor-liquid separation

Abstract

The invention relates to a duplex overflow weir which is suitable for a segmental downcomer in a plate column. The duplex overflow weir comprises weir plates, open pores, a vapor-liquid channel and an air duct, wherein the weir plates are divided into two or more than two layers and arranged according to a certainty gradient from bottom to top. The structure can distribute and divert the liquid to enter the downcomer, increase the space utilization ratio of the downcomer, avoid forming air pockets, promote vapor-liquid separation and the processing capacity of the downcomer is increased by 10-20%. The weir plates can form a plurality of weirs at different heights, the liquid level heights on the plates can be automatically adjusted according to the liquid quantity, and the design flexibility can be enhanced by 10-15%. The lower edges of the weir plates are irregular, and the fluid can laterally flow along the height difference in the downcomer, thereby facilitating gas escape. The liquid flow distribution on the column plates can be adjusted to relieve a retention region and back mixing and improve the vapor-liquid contact, thereby the mass transfer efficiency is enhanced by 5-15%. The open pores in the weir plates can discharge part of liquid flows to relieve the eddying tendency; and the air duct can lead the entrained air out to relieve the pressure fluctuation. The invention is suitable for high liquid quantity operations.

Description

technical field [0001] The present invention relates to an overflow weir mainly used in tray towers in the petroleum and chemical processing industries. Background technique [0002] The overflow weir is an important internal component of the tray tower. The function of setting the overflow weir on the tray is to maintain a certain thickness of liquid layer on the tray, so that the vapor phase rising through the tray and the liquid phase flowing on the tray can fully contact and transfer mass. The structural size of the overflow weir has a significant impact on the processing capacity of the downcomer and the mass transfer efficiency of the tray. [0003] When the liquid overflows into the downcomer, there is still a considerable amount of unseparated gas in the liquid, which makes the foam layer in the downcomer increase, and the liquid phase processing capacity of the downcomer is restricted by this; and, when the liquid flow When the area of ​​the downcomer is large and...

AI Technical Summary

Problems solved by technology

[0013] Among the above-mentioned weir structures, except the "vapor-liquid contact tray with multiple downcomers" of Shell Company, the other structures are single-layer weir plate structures. As mentioned above, when the liquid overflows through the weir, the weir Air pockets will form behind the plate, reducing downcomer handling capacity

And due to the continuous accumulation of gas in the cavitation, when the pressure is greater than the resistance of the liquid "waterfall", pulse fluctuations will occur, which reduces the operational stability, especially for tower equipment with large liquid volume and pressurized operation

[0014] For the ordinary straight weir structure, in addition to the poor effect of vapor-liquid separation in the downcomer, as mentioned above, there are still liquid retention and back-mixing in the arched areas on both sides of the tray, which will reduce the mass transfer efficiency of the tray; and because of the weir The length is shorter, the liquid flow intensity is greater, and the liquid phase processing capacity is also lower

[0015] Although the "swept-back" or "arc weir" has a significant effect on improving the flow field distribution on the tray plate, it has little effect on the vapor-liquid separation in the downcomer, and the structure must adopt a matching downcomer. The liquid pipe structure is not applicable to the equipment transformation of ordinary downcomers

[0016] Although the "downcomer for layered tower" (Vortex tray) uses centrifugal force to promote the vapor-liquid separation in the downcomer, it cannot completely eliminate cavitation, and the structure of the tray is relatively complex, requiring a relatively stable feed amount. , the use of multiple downcomers will also make the flow field on the tray very complicated, and the weir structure must also use matching downcomers, which is not applicable to the equipment transformation of ordinary downcomers

[0017] "A class of high-performance inlet and outlet weirs" is improved on the basis of ordinary straight weirs and arc-shaped weirs. It can guide the liquid flow on the tray and adjust the flow distribution. It is also suitable for ordinary downcomers. However, the single-layer weir plate does not have a diversion effect on the liquid entering the downcomer, and cannot completely eliminate the cavitation

[0018] Shell's "vapor-liquid contact tray with multiple downcomers" is only suitable for rectangular downcomers, which can play the role of anti-scouring baffles and liquid diversion, but not for ordinary bowed downcomers , and the curved arc of the side baffle should be adapted to the direction of the liquid flow. It is necessary to consider the diameter of the tower equipment, the height of the weir, the width of the downcomer, and the liquid phase handling capacity. The design is more complicated. If it cannot match the liquid flow, it will Block the fluid and increase the inlet resistance of the downcomer

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