Equipment Design and Costs for Separating Homogeneous Mixtures

Download Presentation

Equipment Design and Costs for Separating Homogeneous Mixtures

Loading in 2 Seconds...

- 76 Views
- Uploaded on
- Presentation posted in: General

Equipment Design and Costs for Separating Homogeneous Mixtures

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Equipment Design and Costs for Separating Homogeneous Mixtures

1. Distillation

- Designation of design bases
- Composition and physical properties of feed and product
- Special limitations: maximum temperature and pressure drop restrictions, presence of reactive materials or toxic components etc

- Selection of design variables: operating pressure, reflux ratio, feed condition
- Establishment of physical equilibria data
- data for binary pairs are combined with a model (Wilson, NRTL and UNIQUAC) to predict multi-component behavior; UNIFAC model is used for prediction based on functional group

- Determination of number of equilibrium stages
- Underwoodequation for minimum reflux
- Minimum number of stages from Fenske equation
- Number of equilibrium stages, N as a function of and (Gilliand equation)

- Selection of column internals

- Determination of column diameter

- Efficiency:
- Tray Spacing: 0.46 to 0.61 m (0.3 and 0.91 m are also used)
- Column height

- Sieve Tray Geometry
- Hole dia: 0.005-0.025 m
- Fractional free area: 0.06-0.16 m2
- Fractional downcomer area: 0.05-0.3 m2
- Pitch/hole dia ratio: 2.5-4.0
- Tray spacing: 0.305-0.915 m
- Weir height: 0.025-0.075 m

- Determination of diameter
- Vapor velocity is 70 to 90 % of flooding velocity
- Recommended pressure drop
- 400 to 600 Pa/m for atmospheric and high-pressure separation
- 4 to 50 Pa/m for vacuum operations
- 200 to 400 Pa/m for absorption and stripping column

- Heights of columns
- HTU method

- HETP method

- Diameter
- Height
- HETP: Rule of thumb

- Batch distillation:
- Food, pharmaceuticals and biotechnolgy industries
- Rayleigh equation

- Azeotropic distillation

- Costs of distillation column

25 trays

50 trays

- Costs of sieve tray

2. Absorption and Stripping

- Column diameter: 70 to 90% of the flooding velocity, Larger of the top or bottom diameter is used
- Number of equilibrium stages: Modified Kremser equation

Solute fraction absorbed

Solute fraction stripped

- Stage efficiency and column height
- Overall efficiency
- Column height: Tray spacing/HTU/HETP

3. Membrane Separation

- Fabricated from natural and synthetic polymers
- Membrane modules
- Plate and Frame ($250-400/m2)
- Spiral-wound ($25-100/m2)
- Hollow fiber ($10-20/m2)
- Tubular ($250-400/m2)
- Capillary ($25-100/m2)
- Ceramic ($1000-1600/m2)

- Permeance: porosity, solubility or partition coefficient
- Separation factor/selectivity
- Purity and yield

4. Adsorption

- Activated Carbon
- Molecular Sieve Zeolites
- Silica gel
- Activated Alumina

- Temperature Swing cycle
- Cycle time: few hours
- Capacity: 1 kg per 100 kg
of adsorbent

- Inert Purge cycle
- Regeneration is done by purging inert gas and lowering the partial pressure of the adsorbate
- Cycle times are only a few minutes
- Capacity 1 to 2 kg adsorbate per 100 kg adsorbent

- Pressure Swing cycle
- Cycle time: few minutes
- Capacity: 1 to 2 kg per
100 kg adsorbent