MT 1

1.Material balance for distillation column

1.Overhead section of distillation column
Material balance across the overhead section of a distillation column

2.Feed, top product and bottom product
Material balance between feed, distillate and bottom product in
distillation column

3.Solute balance
Solute balance in mass transfer operation

2.Mass transfer coefficient

1.Mole fraction and pressure based mass transfer coefficients
Relation between mole fraction based mass transfer coefficient and pressure based mass transfer coefficient

2.Individual and overall mass transfer coefficients
Relation between individual and overall mass transfer coefficients


1.Rate of drying (In relation to mass transfer coefficient)
Drying rate in constant drying rate period (when mass transfer coefficient is given)

2.Total time of drying
Total time of drying is given by

3.Total time of drying in falling rate region
Total time of drying in falling rate region is given by

4.Rate of drying (In relation to partial pressures)
Drying rate in constant rate period when partial pressures are given

5.Rate of drying (In relation to heat of vaporization)

1. Percentage humidity

2.Dew point humidity
At dew point humidity is 100%


4.Molar saturation humidity

5.Calculating wet bulb temperature
Finding wet bulb temperature: Heat flux = Mass flux * latent heat (λ)

6.Relative saturation
Ratio of partial pressure to vapour pressure

5.Chilton-Colburn analogy
Chilton-coulburn analogy between heat, mass and momentum transfer. The analogy is valid for fully developed turbulent flow in conduits with Re > 10000, 0.7 < Pr < 160, and tubes where L/d > 60 (the same constraints as the Sieder–Tate correlation)

6.Mass transfer flux

1.Total molar flux
Total molar flux of component A

2.Mass transfer flux and humidity
Relationship between mass transfer flux and relative humidity

7.Fick’s law
1. Fick’s first law
First Law: Steady state equation

Second Law: Unsteady state equation

1. Flash distillation

 Relationship between feed flow, overhead vapour flow and bottom liquid flow in flash distillation

2.Feed line equation
Feed line equation for distillation column

Where q is amount of liquid added in bottom product per mole of feed. If feed is a mixture of liquid and vapour, q is the fraction that is liquid.

3.Rectifying and stripping section equation

4.Minumum number of plates
Fensky equation for minimum number of plates, i.e., under the conditions of total reflux

In this equation 1 is subtracted for reboiler. Nm is actual number of plates excluding reboiler.
5. Underwood equation for minimum reflux

6.Rayleigh equation for batch distillation

7.Relative Volatility

8.Minimum reflux and composition of distillate and equilibrium fractions
Relationship between minimum reflux and composition of distillate and equilibrium fractions

9.Steam distillation

9.Logarithmic mean concentration difference

Overall volumetric coefficient (Kca) for mass transfer is given by

HTU – height of transfer unit is given by

10.Unit Conversion
1. Kilogram per cubic meter to ppm

Solubilities at different temperatures
Given solubility S1, cm3/atm at 298oK and 1atm, then solubility at 2.5atm pressure S2.5 = S1 * 2.5, and solubility at STP

1. Operating line of absorption

2.Equal slope of equilibrium line and operating line

tray in absorber, the equilibrium line and operating line are parallel. Slope of operating line = L/V
Slope of equilibrium line = m

3.Mass balance

For L/G to be minimum x1 will attain equilibrium value.

4.Height of packing
For packed bed absorption tower, height of packing = HTU x NTU

5.Height Z, of absorption tower

For dilute solution, i.e. when operating line and equilibrium line are straight