Tower tray is the main component of plate columns for promoting gas-liquid mass and heat transfer. It mainly consists of gas-liquid contact elements (such as float valves, bubble caps, sieve holes, etc.), liquid receiver, overflow weirs, downcomers (or downcomer plates), tray supports, and fasteners. It allows close contact between the two fluids for heat and mass exchange between the phases, separating liquid mixtures or gas mixture components. It is primarily used in high-pressure distillation operations, aiming to provide efficient separation and stable operation for plate columns.
Movable Valve Tray
It is one of the most commonly used type of tower trays. Its valve sheet can be freely lifted and lowered, and have the features of both bubble cap tray and sieve tray, including high capacity, high separation efficiency, small pressure drop and liquid drop, flexible operation.
Fixed Valve Tray
Its opening is stamped directly on the metal plate, and the projection on the tower tray is trapezoidal. This structure helps to lower the liquid surface gradient, reduce the backmixing of the liquid on the tower tray, and offer excellent anti-fouling capacity.
Bubble Cap Tray
It consists of risers and bubble caps to provide passage for steam passing through the tower tray. It has a wide range of loads, low liquid loads, low gas loads, high efficiency, low leakage rate, and not easily clogged. It is suitable for a wide range of materials.
Sieve Tray
It is a perforated plate tray with circular holes punched in a metal plate, usually 3/16" to 1" in diameter. Compared with movable valve tray and bubble cap tray, it provides good capacity and moderate efficiency, and has simple construction, low maintenance and low fouling tendency.
Dual Flow Tray
Double flow refers to the countercurrent flow of steam and liquid through the perforations. Essentially, it is a tower tray without downcomers. It has greater capacity than the special movable valve tray. Besides, it has good anti-fouling capacity, low pressure drop, relatively low cost, and good mass transfer efficiency.
Baffle Tray
There are two structural forms: disk and ring trays and side-to-side baffles. Steam achieves gas-liquid contact through a liquid curtain flowing down between tower trays. It is suitable for low efficiency and highly fouled applications with high capacity, low pressure drop and low cost.
Tower trays are used for mass transfer operations where pressure drop limitation is not important. They are mainly used for high pressure distillation operations. The plate column, as a graded contact mass transfer device for gas-liquid/liquid-liquid systems, is widely used for distillation and absorption processes in chemical unit operations.
