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).