#### Stripping Columns: Screencasts

Describes a stripping column, demonstrates mass balances, and shows how to calculate the number of equilibrium stages

We suggest that after watching this screencast, you list the important points as a way to increase retention.

Demonstrates how mass balances and an equilibrium equation are used to count stages graphically on a y versus x diagram (gas-phase solute concentration versus liquid-phase solute concentration) for a stripping column.

We suggest that after watching this screencast, you list the important points as a way to increase retention.

##### Important Equations:

Solute mole balance for stage 1 to stage n (where n is any integer from 1 to N, where N is the total number of stages)

\[x_0 L + y_{n+1} V = x_n L + y_1 V\]

\(y_{n+1} = \frac{L}{V} (x_n – x_0) + y_1\) (operating line on y versus x plot)

where \(L\) = liquid molar flow rate, \(V\) = gas molar flow rate, the mole ratios of solute are for the following streams:

\(x_0\): liquid feed to column (stage 1)

\(y_1\): gas stream leaving column (stage 1)

\(y_{n+1}\): gas stream entering stage n

\(x_n\): liquid stream leaving stage n

Solute mole balance around stage n

\[x_{n-1}L + y_{n+1}V = x_n L + y_n V\]

where the mole ratios of solute are for the following streams

\(x_{n-1}\): liquid entering stage n

\(y_n\): gas leaving stage n

The streams leaving stage n (\(x_n\) and \(y_n\)) are in equilibrium

\(y_n = \frac{H}{P} x_n\) (Henry’s Law)

where \(H\) = Henry’s constant (atm) and \(P\) = pressure (atm)

\[H = H^0 exp \left( -\frac{E}{R} \left( \frac{1}{T} – \frac{1}{T_0} \right) \right) \]

where \(H^0\) = Henry’s constant at \(T_0\) (298 K), \(E\) = activation energy, \(R\) = ideal gas constant, and \(T\) = temperature (K).