Packing Height in Packed Tower

The packing height in a packed tower is determined by the NTU (Number of Transfer Units) multiplied by the HETP (Height Equivalent to a Theoretical Plate). The correct answer is option 'B', which states that the packing height is equal to NTU multiplied by HETP.

Explanation:

1. Packed Tower and its Purpose:
- A packed tower is a common equipment used in chemical engineering for various separation and absorption processes.
- It consists of a column filled with a packing material, which provides a large surface area for mass transfer between the liquid and gas phases.

2. Number of Transfer Units (NTU):
- NTU is a dimensionless parameter used to quantify the effectiveness of mass transfer in a packed tower.
- It is defined as the ratio of the driving force of mass transfer to the resistance to mass transfer.
- NTU is calculated using the equation: NTU = (Driving Force of Mass Transfer) / (Resistance to Mass Transfer).

3. Height Equivalent to a Theoretical Plate (HETP):
- HETP is a measure of the efficiency of a packed tower in terms of mass transfer.
- It represents the height of packing required to achieve the same separation as a theoretical plate.
- HETP is typically expressed in units of length (e.g., meters or feet) and is determined experimentally.

4. Packed Tower Design:
- In the design of a packed tower, the packing height is an important parameter.
- The packing height is the height of the column required to achieve the desired separation or absorption.
- It is calculated by multiplying the NTU by the HETP, as stated in the question.

5. Significance of NTU and HETP:
- NTU represents the efficiency of mass transfer in a packed tower.
- A higher NTU value indicates a more effective mass transfer process.
- HETP represents the efficiency of the packing material in terms of mass transfer.
- A lower HETP value indicates a more efficient packing material.

6. Importance of the Correct Answer:
- Option 'B' correctly states that the packing height is equal to NTU multiplied by HETP.
- It emphasizes the relationship between NTU and HETP in determining the packing height.
- This understanding is crucial for the design and optimization of packed towers in various chemical engineering applications.