Appendix C. Unit Conversions and Physical Constants
by Phillip C. Wankat
Separation Process Engineering: Includes Mass Transfer Analysis, Fourth Edition
- About This E-Book
- Title Page
- Copyright Page
- Dedication Page
- Contents
- Preface
- Acknowledgments
- About the Author
- Nomenclature
- Chapter 1. Introduction to Separation Process Engineering
- Chapter 2. Flash Distillation
- 2.0 Summary—Objectives
- 2.1 Basic Method of Flash Distillation
- 2.2 Form and Sources of Equilibrium Data
- 2.3 Graphical Representation of Binary VLE
- 2.4 Binary Flash Distillation
- 2.5 Multicomponent VLE
- 2.6 Multicomponent Flash Distillation
- 2.7 Simultaneous Multicomponent Convergence
- 2.8 Three-Phase Flash Calculations
- 2.9 Size Calculation
- 2.10 Using Existing Flash Drums
- References
- Homework
- Chapter 2. Appendix A. Computer Simulation of Flash Distillation
- Chapter 2 Appendix B. Spreadsheets for Flash Distillation
- Chapter 3. Introduction to Column Distillation
- Chapter 4. Binary Column Distillation: Internal Stage-by-Stage Balances
- 4.0 Summary—Objectives
- 4.1 Internal Balances
- 4.2 Binary Stage-by-Stage Solution Methods
- 4.3 Introduction to the McCabe-Thiele Method
- 4.4 Feed Line
- 4.5 Complete McCabe-Thiele Method
- 4.6 Profiles for Binary Distillation
- 4.7 Open Steam Heating
- 4.8 General McCabe-Thiele Analysis Procedure
- 4.9 Other Distillation Column Situations
- 4.10 Limiting Operating Conditions
- 4.11 Efficiencies
- 4.12 Simulation Problems
- 4.13 New Uses for Old Columns
- 4.14 Subcooled Reflux and Superheated Boilup
- 4.15 Comparisons Between Analytical and Graphical Methods
- References
- Homework
- Chapter 4 Appendix A. Computer Simulation of Binary Distillation
- Chapter 4 Appendix B. Spreadsheets for Binary Distillation
- Chapter 5. Introduction to Multicomponent Distillation
- 5.0 Summary—Objectives
- 5.1 Calculational Difficulties
- 5.2 Profiles for Multicomponent Distillation
- 5.3 Stage-by-Stage Calculations for CMO
- References
- Homework
- Chapter 5 Appendix A. Simplified Spreadsheet for Stage-by-Stage Calculations for Ternary Distillation
- Chapter 5 Appendix B. Automated Spreadsheet with VBA for Stage-by-Stage Calculations for Ternary Distillation
- Chapter 6. Exact Calculation Procedures for Multicomponent Distillation
- 6.0 Summary—Objectives
- 6.1 Introduction to Matrix Solution for Multicomponent Distillation
- 6.2 Component Mass Balances in Matrix Form
- 6.3 Initial Guesses for Flow Rates and Temperatures
- 6.4 Temperature Convergence
- 6.5 Energy Balances in Matrix Form
- 6.6 Introduction to Naphtali-Sandholm Simultaneous Convergence Method
- 6.7 Discussion
- References
- Homework
- Chapter 6 Appendix. Computer Simulations for Multicomponent Column Distillation
- Chapter 7. Approximate Shortcut Methods for Multicomponent Distillation
- Chapter 8. Introduction to Complex Distillation Methods
- 8.0 Summary—Objectives
- 8.1 Breaking Azeotropes with Other Separators
- 8.2 Binary Heterogeneous Azeotropic Distillation Processes
- 8.3 Steam Distillation
- 8.4 Pressure-Swing Distillation Processes
- 8.5 Complex Ternary Distillation Systems
- 8.6 Extractive Distillation
- 8.7 Azeotropic Distillation with Added Solvent
- 8.8 Distillation with Chemical Reaction
- References
- Homework
- Chapter 8 Appendix A. Simulation of Complex Distillation Systems
- Chapter 8 Appendix B. Spreadsheet for Residue Curve Generation
- Chapter 9. Batch Distillation
- 9.0 Summary—Objectives
- 9.1 Introduction to Batch Distillation
- 9.2 Batch Distillation: Rayleigh Equation
- 9.3 Simple Binary Batch Distillation
- 9.4 Constant-Mole Batch Distillation
- 9.5 Batch Steam Distillation
- 9.6 Multistage Binary Batch Distillation
- 9.7 Multicomponent Simple Batch Distillation
- 9.8 Operating Time
- References
- Homework
- Chapter 9 Appendix A. Spreadsheet for Simple Multicomponent Batch Distillation, Constant Relative Volatility
- Chapter 10. Staged and Packed Column Design
- 10.0 Summary—Objectives
- 10.1 Staged Column Equipment Description
- 10.2 Tray Efficiencies
- 10.3 Column Diameter Calculations
- 10.4 Balancing Calculated Diameters
- 10.5 Sieve Tray Layout and Tray Hydraulics
- 10.6 Valve Tray Design
- 10.7 Introduction to Packed Column Design
- 10.8 Packings and Packed Column Internals
- 10.9 Height of Packing: HETP Method
- 10.10 Packed Column Flooding and Diameter Calculation
- 10.11 Economic Trade-Offs for Packed Columns
- 10.12 Choice of Column Type
- References
- Homework
- Chapter 10 Appendix. Tray and Downcomer Design with Computer Simulator
- Chapter 11. Economics and Energy Conservation in Distillation
- 11.0 Summary—Objectives
- 11.1 Equipment Costs
- 11.2 Basic Heat Exchanger Design
- 11.3 Design and Operating Effects on Costs
- 11.4 Changes in Plant Operating Rates
- 11.5 Energy Conservation in Distillation
- 11.6 Synthesis of Column Sequences for Almost Ideal Multicomponent Distillation
- 11.7 Synthesis of Distillation Systems for Nonideal Ternary Systems
- References
- Homework
- Chapter 12. Absorption and Stripping
- 12.0 Summary—Objectives
- 12.1 Absorption and Stripping Equilibria
- 12.2 McCabe-Thiele Solution for Dilute Absorption
- 12.3 Stripping Analysis for Dilute Systems
- 12.4 Analytical Solution for Dilute Systems: Kremser Equation
- 12.5 Efficiencies
- 12.6 McCabe-Thiele Analysis for More Concentrated Systems
- 12.7 Column Diameter
- 12.8 Dilute Multisolute Absorbers and Strippers
- 12.9 Matrix Solution for Concentrated Absorbers and Strippers
- 12.10 Irreversible Absorption and Cocurrent Cascades
- References
- Homework
- Chapter 12 Appendix. Computer Simulations of Absorption and Stripping
- Chapter 13. Liquid-Liquid Extraction
- 13.0 Summary—Objectives
- 13.1 Extraction Processes and Equipment
- 13.2 Dilute, Immiscible, Countercurrent Extraction
- 13.3 Dilute Fractional Extraction
- 13.4 Immiscible Single-Stage and Cross-Flow Extraction
- 13.5 Concentrated Immiscible Extraction
- 13.6 Immiscible Batch Extraction
- 13.7 Extraction Equilibrium for Partially Miscible Ternary Systems
- 13.8 Mixing Calculations and the Lever-Arm Rule
- 13.9 Partially Miscible Single-Stage and Cross-Flow Systems
- 13.10 Countercurrent Extraction Cascades for Partially Miscible Systems
- 13.11 Relationship Between McCabe-Thiele and Triangular Diagrams for Partially Miscible Systems
- 13.12 Minimum Solvent Rate for Partially Miscible Systems
- 13.13 Extraction Computer Simulations
- 13.14 Design of Mixer-Settlers
- References
- Homework
- Chapter 13 Appendix. Computer Simulation of Extraction
- Chapter 14. Washing, Leaching, and Supercritical Extraction
- 14.0 Summary—Objectives
- 14.1 Generalized McCabe-Thiele and Kremser Procedures
- 14.2 Washing
- 14.3 Leaching with Constant Flow Rates
- 14.4 Leaching with Variable Flow Rates
- 14.5 Introduction to Supercritical Fluid Extraction
- 14.6 Application of McCabe-Thiele and Kremser Methods to Other Separations
- References
- Homework
- Chapter 15. Introduction to Diffusion and Mass Transfer
- 15.0 Summary–Objectives
- 15.1 Molecular Movement Leads to Mass Transfer
- 15.2 Fickian Model of Diffusivity
- 15.3 Values and Correlations for Fickian Binary Diffusivities
- 15.4 Linear Driving-Force Model of Mass Transfer for Binary Systems
- 15.5 Correlations for Mass Transfer Coefficients
- 15.6 Difficulties with Fickian Diffusion Model
- 15.7 Maxwell-Stefan Model of Diffusion and Mass Transfer
- 15.7.1 Introductory Development of the Maxwell-Stefan Theory of Diffusion
- 15.7.2 Maxwell-Stefan Equations for Binary Nonideal Systems
- 15.7.3 Determining Independent Fluxes Nj,z
- 15.7.4 Maxwell-Stefan Difference Equation Formulations
- 15.7.5 Relationship between Maxwell-Stefan and Fickian Diffusivities
- 15.7.6 Ideal Ternary Systems
- 15.7.7 Ternary Mass Transfer to Expanding or Contracting Objects
- 15.7.8 Nonideal Ternary Systems
- 15.8 Advantages and Disadvantages of Different Diffusion and Mass Transfer Models
- References
- Homework
- Chapter 15 Appendix. Spreadsheets Examples 15-10 and 15-11
- Chapter 16. Mass Transfer Analysis for Distillation, Absorption, Stripping, and Extraction
- 16.0 Summary—Objectives
- 16.1 HTU-NTU Analysis of Packed Distillation Columns
- 16.2 Relationship of HETP and HTU
- 16.3 Mass Transfer Correlations for Packed Towers
- 16.4 HTU-NTU Analysis of Concentrated Absorbers and Strippers
- 16.5 HTU-NTU Analysis of CoCurrent Absorbers
- 16.6 Prediction of Distillation Tray Efficiency
- 16.7 Mass Transfer Analysis of Extraction
- 16.8 Rate-Based Analysis of Distillation
- References
- Homework
- Chapter 16 Appendix. Computer Rate-Based Simulation of Distillation
- Chapter 17. Crystallization from Solution
- 17.0 Summary–Objectives
- 17.1 Basic Principles of Crystallization from Solution
- 17.2 Continuous Cooling Crystallizers
- 17.3 Evaporative and Vacuum Crystallizers
- 17.4 Sieve Analysis
- 17.5 Introduction to Population Balances
- 17.6 Crystal Size Distributions for MSMPR Crystallizers
- 17.7 Seeding
- 17.8 Batch and Semibatch Crystallization
- 17.9 Precipitation
- References
- Homework
- Chapter 17 Appendix. Spreadsheets
- Chapter 18. Introduction to Membrane Separation Processes
- Chapter 19. Introduction to Adsorption, Chromatography, and Ion Exchange
- 19.0 Summary—Objectives
- 19.1 Sorbents and Sorption Equilibrium
- 19.2 Solute Movement Analysis for Linear Systems: Basics and Applications to Chromatography
- 19.3 Solute Movement Analysis for Linear Systems: Temperature and Pressure Swing Adsorption and Simulated Moving Beds
- 19.4 Nonlinear Solute Movement Analysis
- 19.5 Ion Exchange
- 19.6 Mass and Energy Transfer in Packed Beds
- 19.7 Mass Transfer Solutions for Linear Systems
- 19.8 LUB Approach for Nonlinear Sorption Systems
- 19.9 Checklist for Practical Design and Operation
- References
- Homework
- Chapter 19 Appendix. Aspen Chromatography Simulator
- Appendix A. Aspen Plus Troubleshooting Guide for Separations
- Appendix B. Instructions for Fitting VLE and LLE Data with Aspen Plus
- Appendix C. Unit Conversions and Physical Constants
- Appendix D. Data Locations
- Answers to Selected Problems
- Index
- Code Snippets
Appendix C. Unit Conversions and Physical Constants
Unit Conversions1
1Source: Green and Perry, Perry’s Chemical Engineers’ Handbook, 8th ed., Tables 1-4 and 1-7, 2008.
Density and Weight
1000.0 g = 1.0 kg
1.0 g/cm3 = 1000.0 kg/m3
1.0 lbm = 0.45359 kg
1.0 lbm/ft3 = 16.01846 kg/m3
Transport Properties: Diffusivity, Viscosity, and Mass Transfer Coefficient
1.0 ft2/s = 0.009290 m2/s
1.0 cm2/s = 0.0001 m2/s
1.0 Pa·s = 1.0 (N s)/m2 = 1.0 kg/(m.s)
1.0 cP = 0.001 Pa·s = 0.01 g/(cm.s)
1.0 lbm/(ft s) = 1.48816 Pa s
1.0 mol/[s m2(mol/L)] = 10.0 m/s
1.0 lbmol/[h ft2(lbmol/ft3)] = 0.00008467 m/s
Energy and Specific Heat
1.0 Btu = 1.055056 kJ
1.0 Btu = 0.0002931 kWh
1.0 cal = 4.184 J
1.0 kcal = 4.184 kJ
1.0 kJ/s = 1.0 kW
1.0 Btu/lbm = 2.3260 kJ/kg
1.0 Btu/(lbm °F) = 1.0 cal/(g °C) = 4184 kJ/(kg K)
1.0 kcal/(kg °C) = 4.184 kJ/(kg K)
Length and Volume
1.0 µm (1.0 micron) = 10–6 m
100.0 cm = 1.0 m
1.0 ft = 0.3048 m
1000.0 liters = 1.0 m3
1.0 ft3 = 7.481 US gal
1.0 US gal = 0.003785 m3
1.0 US gal = 3.785 L
Pressure
100,000 Pa = 100.0 kPa = 1.0 bar
101.3 kPa = 1.013 bar = 1.0 atm
760 mm Hg at 0°C (density 13.5951 g/cm3) = 760.0 torr = 1.0 atm
14.696 psi = 1.0 atm.
33.899 ft water at 3.94°C = 1.0 atm
Temperature
T in °C = (5/9) (T in °F – 32.0)
T in °C = T in K – 273.15
T in K = (5/9) (T in °R)
T in °F = T in °R – 459.7
Time
24.0 h = 1 day
60.0 min = 1.0 h
3600.0 s = 1.0 h
60.0 s = 1.0 min
Ideal Gas Values
R Gas constant, 8.314 J/(mol·K) = 1.9872 cal/(mol·K) = 1.9872 Btu/(lbmol °R) or 8.314 m3 Pa/(mol·K) or 0.008314 m3 kPa/(mol·K) or 82.057 cm3 atm/(mol·K) or 1.314 atm·ft3/(lbmol·K) or 0.7302 atm ft3/(lbmol °R)
22.4 liters of gas = 1.0 mol at STP (1.0 atm and 0°C)
359 ft3 of gas = 1.0 lbmol at STP
Useful Physical Constants
g Acceleration due to gravity at sea level, 9.8066 m2/s = 32.174 ft/s2
gc Conversion factor in English units, 32.2 ft·lbm/(lbf·s2)
kB Boltzmann’s constant, 1.380 J/(K·molecule)
N Avogadro’s number, 6.024 × 1023 molecules/mol
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