Type of tower

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1. Bubble column: The main component on the tray is the bubble. It is a bell-shaped cover supported on a tray, with elongated or oval-shaped small holes along its lower edge, or arranged in a toothed pattern, maintaining a certain distance from the surface of the tray. The cover is fitted with a short rise pipe, the upper end of which is higher than the hole or gap at the lower edge of the cover. The gas beneath the tower enters the hood through the rising pipe, then bends downward to reach the annular space between the station hood and the pipe, and subsequently disperses into gas bubbles through small holes or gaps at the bottom of the hood to enter the liquid layer on the plate. 2. Tray tower: The difference between a tray and a bubble cap tray is that the bubble caps and lift pipes are omitted, and instead many small-diameter holes are made directly in the tray ； During operation, the gas rises at high speed through the small holes, while the liquid flows to the next layer of plates via the downcomer. The gas dispersed into bubbles turns the liquid layer on the plate into a highly turbulent foam layer. 3. Floating valve tower: The floating valve tower combines the advantages of the bubble column and the tray column. Valve holes are arranged in an equilateral triangle pattern on the tray, with a valve plate placed above each hole. When the gas velocity reaches a certain level, the valve plate is pushed upward; however, due to the restriction of the foot hooks, it cannot move out of the valve hole even when pushed to the highest position. As the gas velocity decreases, the valve plate drops back onto the tray, supported by three protrusions at its bottom, while still maintaining a distance of about 2.5 mm from the tray surface. The number of open valve holes on the tray varies depending on the gas flow rate. Therefore, the linear velocity of the gas discharged from the floating valve remains relatively constant, allowing the bubbling performance to stay consistent, which gives the floating valve a high degree of operational flexibility. The diameter of the floating valve is smaller than that of the bubble, allowing them to be arranged more compactly on the tray, thereby increasing the open area of the tray. Since the liquid enters the liquid layer horizontally, this reduces the amount of liquid foam carried away while increasing the gas-liquid contact time. As a result, the gas flow rate can be increased, enhancing production capacity; the tray efficiency also improves, and the pressure drop is lower compared to bubble towers. Structurally, it is simpler than a bubble column but more complex than a sieve tray column. The disadvantage of this structure is that, due to the movement of the valve disc, it may become loose or stuck during use, resulting in abnormal flow of gas and liquid at the valve opening. To prevent the valve disc from rusting and sticking to the tray, thereby blocking the valve opening and preventing it from moving, both the floating valve and the tray are made of stainless steel. Additionally, viscous liquids can easily stick to the valve disc, and solid particles in the liquid can cause the valve disc to get stuck; therefore, these materials are not suitable for use. 4. Tongue-plate trays and floating tongue-plate trays: Tongue-tray plates are made by stamping many upward-turning tongue-shaped protrusions onto a flat plate. After the tabs project out from the tray, the holes that remain are also in the shape of tabs. The gas rising from the lower tray is ejected almost horizontally between these tabs and holes, at a speed of 20–30 m/s, toward the liquid layer, thereby breaking the liquid into droplets or streams. This jetting effect greatly enhances the contact between the two phases, thereby improving mass transfer. Since the direction of gas emission is roughly consistent with that of the liquid flow, the former exerts a pushing effect on the latter, increasing the liquid flow rate without increasing the liquid level drop. The thin liquid layer on the plate reduces the resistance of the tray, as well as minimizing liquid mist entrainment. The main component on the floating tongue plate is the combination of the tongue and the floating valve; this allows gas to enter the liquid layer in a jetted manner, and it also enables the opening degree of the tongue valve to change in response to load variations, thereby keeping the jetting speed more or less constant. Therefore, compared with fixed-lip plates, this type of tray offers more stable operation, greater operational flexibility, higher efficiency, and a lower pressure drop. 5. Cross-flow sieve tray towers and cross-flow grating tray towers: The trays of cross-flow sieve tray towers have small holes in them, while the trays of cross-flow grating tray towers have linear slits. No downcomer is provided between the plates; the liquid flows downward along the perimeter of the holes or gaps, while the gas flows upward in the center of those holes or gaps. The obstruction of the liquid flow by the gas flow maintains a certain thickness of liquid layer on the plate, allowing gas bubbles to pass through. The foam layer height on the plate is relatively low, so the pressure drop is small; as a result, the efficiency of the plate is slightly lower than that of a bubble cap plate.