Selection dilemmas between plate towers and packed towers

All using trays, or the butane column uses packing M250.Y

This is probably related to the processing capacity of the sea area; the deethanization towers I’ve seen have a segmented tray structure.

Factors to consider when selecting a tower type include: the properties of the material, operating conditions, the performance of the tower equipment, as well as its manufacturing, installation, transportation, and maintenance. a. Factors related to physical properties: (1) For systems that tend to form bubbles, it is advisable to use a packed tower when the processing volume is not large. Because the packing can cause the foam to break, it easily leads to flooding in plate towers. (2) For corrosive media, a packed tower can be used. If a tray tower must be employed, it is advisable to choose a sieve tray tower, a cross-flow tray tower, or a tongue-shaped tray tower with a simple structure and low cost, so as to allow for easy replacement. (3) For materials that are thermosensitive and require operation under reduced pressure to prevent decomposition or polymerization due to overheating, tower types with a smaller pressure drop should be used, such as towers equipped with regularly packed packing or wet-wall towers. When a lower degree of vacuum is required, sieve plate towers and floating valve towers are suitable. (4) For systems with high viscosity, larger-sized fillers can be used. The mass transfer efficiency of the plate tower is too poor. (5) For materials containing suspended solids, a tower type with larger fluid flow channels should be selected, with a plate tower being the preferred choice. Bubble column towers, floating valve column towers, tray columns, tongue-shaped column towers, and tray columns with larger pore sizes can be used. Small fillers should not be used. (6) For systems with heat effects during operation, a plate tower is appropriate. Due to the liquid layer on the tray, heat exchange tubes can be placed therein for effective heating or cooling. b. Factors related to operating conditions: (1) If the gas-phase mass transfer resistance is high (i.e., in gas-phase control processes such as the distillation of low-viscosity liquids or air humidification), a packed tower is suitable, as the gas phase in the packed layer flows turbulently while the liquid phase flows in a film-like manner. Conversely, for systems controlled by the liquid phase, a plate tower is suitable, as the liquid phase in a plate tower is turbulent, with gas being bubbled through the liquid layer. (2) For high liquid loads, a packed tower can be used; if a tray tower is employed, it is advisable to choose a type with co-current gas-liquid flow (such as jet trays) or a type with low liquid flow resistance across the trays (such as sieve trays and floating valve trays). Furthermore, both guided sieve tray trays and multi-downcomer sieve tray trays can handle high liquid loads. (3) With a low liquid load, packed towers are generally not suitable. Because packed towers require a certain level of spray density, while mesh packings can be used in applications with low liquid loads. (4) Suitability to liquid-gas ratio fluctuations: plate towers are superior to packed towers; therefore, plate towers should be used when the liquid-gas ratio fluctuates significantly. (5) Operational flexibility: plate towers have greater operational flexibility than packed towers, with floating valve towers having the highest level and bubble cap towers being next in line; generally speaking, cross-flow towers have less operational flexibility. c. Other reasons: (1) In most cases, when the tower diameter is greater than 800 mm, a plate tower is preferable; when it is less than 800 mm, a packed tower is more suitable. However, there are exceptions; the use of Pall rings and certain new types of packing in large towers can yield better results than those in plate towers. Similarly, plate towers are also used when the tower diameter is less than 800 mm. (2) Generally, packed towers are heavier than tray towers. (3) Plate towers are relatively inexpensive to construct. Since the price of the packing is approximately proportional to the volume of the tower, the price per unit area for plate towers decreases as the tower diameter increases.