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Equipment Design and Costs for Separating Homogeneous Mixtures.

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Presentation on theme: "Equipment Design and Costs for Separating Homogeneous Mixtures."— Presentation transcript:

1 Equipment Design and Costs for Separating Homogeneous Mixtures

2 1. Distillation

3 Design Procedures for Columns with Sieve Trays 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

4 Design Procedures for Columns with Sieve Trays (cont’d) Determination of number of equilibrium stages Underwood equation for minimum reflux Minimum number of stages from Fenske equation Number of equilibrium stages, N as a function of and (Gilliand equation)

5 Design Procedures for Columns with Sieve Trays (cont’d) Selection of column internals

6 Design Procedures for Columns with Sieve Trays (cont’d) Determination of column diameter

7 Design Procedures for Columns with Sieve Trays (cont’d) Efficiency: Tray Spacing: 0.46 to 0.61 m (0.3 and 0.91 m are also used) Column height

8 Design Procedures for Columns with Sieve Trays (cont’d) Sieve Tray Geometry Hole dia: m Fractional free area: m2 Fractional downcomer area: m2 Pitch/hole dia ratio: Tray spacing: m Weir height: m

9 Design Procedures for Columns with Random Packing 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

10 Design Procedures for Columns with Random Packing (cont’d) Heights of columns HTU method

11 Design Procedures for Columns with Random Packing (cont’d) HETP method

12 Design Procedures for Columns with Structured Packing

13 Design Procedures for Columns with Structured Packing (cont’d) Diameter Height HETP: Rule of thumb

14 Other Distillation Processes Batch distillation: Food, pharmaceuticals and biotechnolgy industries Rayleigh equation

15 Other Distillation Processes (cont’d) Azeotropic distillation

16 Cost Estimation

17 Cost Estimation (cont’d) Costs of distillation column 25 trays50 trays

18 Cost Estimation (cont’d) Costs of sieve tray

19 Cost Estimation (cont’d)

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23 2. Absorption and Stripping

24 Gas Treatment with Solvent Recovery

25 Design Procedures 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

26 Design Procedures (cont’d) Stage efficiency and column height Overall efficiency Column height: Tray spacing/HTU/HETP

27 3. Membrane Separation

28 Selection of Membranes Fabricated from natural and synthetic polymers Membrane modules Plate and Frame ($ /m2) Spiral-wound ($25-100/m2) Hollow fiber ($10-20/m2) Tubular ($ /m2) Capillary ($25-100/m2) Ceramic ($ /m2)

29 Concentration Profile across Membranes

30 Design Parameter Permeance: porosity, solubility or partition coefficient Separation factor/selectivity Purity and yield

31 Flow Patterns

32 4. Adsorption

33 Selection of Adsorbent Activated Carbon Molecular Sieve Zeolites Silica gel Activated Alumina

34 Basic Adsorption Cycles Temperature Swing cycle Cycle time: few hours Capacity: 1 kg per 100 kg of adsorbent

35 Basic Adsorption Cycles (cont’d) 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

36 Basic Adsorption Cycles (cont’d) Pressure Swing cycle Cycle time: few minutes Capacity: 1 to 2 kg per 100 kg adsorbent


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