How is the height of packing required in a tower calculated?

The correct approach to calculating the height of packing required in a tower is based on the relationship between the number of stages, the height per stage, and packing efficiency. The formula that captures this relationship states that the required height of packing can be determined by taking the total number of stages and multiplying it by the height of packing per stage. This product is then divided by the packing efficiency.

When considering the process of mass transfer in packed towers, packing efficiency reflects how effectively a tower facilitates the exchange of mass (typically gas and liquid). As a result, the actual height of packing needed increases if the packing efficiency is lower because more height is required to achieve the desired level of mass transfer.

In summary, the correct formula emphasizes that to achieve the desired process performance, the number of stages multiplied by the height per stage must be accounted for using packing efficiency, which modifies the actual height needed. Thus, using this relationship gives a reliable estimate for the height of packing in a tower.