Desulfurization of dry gas and liquefied gas

For many counter-current contact processes, both packed towers and plate towers can be used. Each type of tower has its own advantages and disadvantages; the choice should be made based on a comprehensive consideration of the system involved. 　　⑴The operating range of a packed tower is limited, and it is particularly sensitive to changes in the liquid load. 　　⑵Packed towers are not suitable for treating materials that are prone to polymerization or contain solid suspensions. 　　⑶When cooling is required during gas-liquid contact to remove reaction heat or heat of dissolution, packed towers are not suitable. Additionally, when there is side-draw discharge, packed towers are less convenient than plate towers. 　　⑷The diameter of a packed tower can be very small, but the diameter of a plate tower is generally not less than 0.6 m. 　　⑸Design data for plate towers is more readily available and more reliable, allowing for smaller safety factors. 　　⑹When the tower diameter is not very large, the cost of a packed tower is low. 　　⑺For systems prone to foaming, a packed tower is more suitable. 　　⑻For corrosive systems, a packed tower is more suitable. 　　⑼For thermosensitive systems, a packed tower is preferable. 　　⑽The pressure drop of a packed tower is lower than that of a plate tower, making it more suitable for vacuum operation. The above information was found online; the following are my own opinions: 1. For dry gas desulfurization, either plate-type or packed columns can be used; the choice can be made based on the aforementioned factors. 2. Desulfurization of liquefied gas can only be carried out using packed towers; liquefied gas and alkaline solution are separated by means of their density difference, and it seems impossible to achieve this using tray towers.

Packed towers are not used for dry gas, mainly because the dew point of dry gas is very low; using liquid-liquid contact would require a significant increase in volume, resulting in energy waste. Conversely, liquid hydrocarbons are very easy to liquefy; if a plate column is used, the liquid reflux rate becomes too high, affecting the purity and separation of the absorbent at the bottom of the column.

Both towers here are tray towers; previously, packed towers were used, but they tend to get clogged and it’s difficult to deal with corrosion on the tower walls. Operation is smooth now, and the regeneration tower is a packed tower

Overall, it seems that trays are a better choice for coking liquefied gas; after all, the problem of coke powder is difficult to resolve, and gas flow rates experience significant fluctuations during the switching between coke towers