Q1: Use of raschig rings in place of crushed stones as packing in packed beds (other things being same)

ANS:C - decreases pressure drop, increases surface area.

The use of Raschig rings in place of crushed stones as packing in packed beds, while keeping other factors constant, will result in increased pressure drop and increased surface area. Raschig rings are cylindrical ceramic or metal rings commonly used as packing material in packed beds for various chemical engineering applications. Compared to crushed stones, Raschig rings have a larger surface area per unit volume due to their cylindrical shape and internal surface area. This increased surface area promotes greater contact between the gas and liquid phases, enhancing mass transfer efficiency. However, the cylindrical shape of Raschig rings also increases the tortuosity of flow paths within the packed bed, leading to increased pressure drop compared to crushed stones. The irregular shape of crushed stones allows for easier flow through the packed bed, resulting in lower pressure drop. Therefore, using Raschig rings instead of crushed stones as packing in packed beds will result in increased pressure drop and increased surface area.