Overview of Process Design

1
Overview of Process Design

• Chapter 4
• Terry A. Ring
• ChE

2
Where is Design used in Industry?
3
Where is Design used in Industry?

• De Novo Designs
• Known Plants but different location or larger
  size
• Plant Improvement
• Debottlenecking Plant
• Increase Plant Capacity
• Increase Plant Efficiency
• Decrease Costs
• Pollution Minimization

4
Importance of Process Design

• In Preliminary Process Design
• 98 Operating Costs Committed
• 80 Capital Costs Committed
• Less than 10 Spent
• Design is Very Important
• But why is this so?

5
How is Design Practiced
Stage Gate Management

• Process Conception
• Preliminary Design
• Process Concepts
• Process Economics
• Management decision to go forward
• Intermediate Design
• PIDs
• Ask vendors for prices major pieces of equipment
• Reactor, Separators, HX, Utilities, tank farms
• Process Economics
• Management decision to go forward
• Detailed Design
• Mechanical Engineering
• Equipment Supports
• Where are all the nuts and bolts
• Piping elevation
• Electrical/Power Engineering
• Utilities
• Process Economics

6
Process Creation

• Chemical Reaction Routes
• Preliminary Database
• MSDS (Health and safety info.)
• Raw Materials
• Reaction Products and Intermediates
• Thermo/phys properties (Expts and Predictions)
• Heats of Formation
• VLE data, solubilities, etc.
• Chemical Prices (Chemical Market Reporter)

7
Operating costs

• Selection of Raw Materials
• Selection of Reaction Path to Product
• Determine Gross Profitability of Process
• Examples
• Vinyl Chloride Manufacture (part of PVC plant)
• Example in your book
• Octane Manufacture (part of refinery)

8
Process Economics-I

• Macro View
• Possible Reactions for vinyl chloride
• 1) C2H4 (ethylene) Cl2 ? C2H3Cl (vinyl
  Chloride) HCl
• 2) C2H2 (acetylene) HCl ? C2H3Cl
• 3) C2H4 Cl2 ? C2H4Cl2 ? C2H3Cl HCl
• 4) C2H2 2HCl ½ O2? C2H4Cl2H2O
• C2H4Cl2? C2H3Cl H2O
• C2H2 2HCl ½ O2?C2H3Cl H2O
  (overall)
• 5) C2H4 Cl2 ? C2H4Cl2
• C2H2 2HCl ½ O2? C2H4Cl2 H2O
• 2 C2H4Cl2? 2C2H3Cl 2HCl
• 2C2H4 Cl2 ½ O2? 2C2H3Cl H2O
  (overall)

9
Gross Profitability Analysis-1

• Start With Raw Material Costs and Product Prices

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Gross Profitability Analysis-1

• For Each Reaction Determine the Profit to be made
• Gross Profit is
• 22/lb(1) 18/lb (0.583)-18/lb(0.449)-11/lb(1.1
  34)11.94 /lb

11
Gross Profitability Analysis-2

• Overview of Various Reactions
• Reaction 3 is most profitable!
• How much do we make? Market Volume?

http//nexant.ecnext.com/coms2/summary_0255-3041_I
TM
12
Example of Market Information
http//www.ceramics.org/ASSETS/574195312DA14992880
5FFEA1242FECF/MaterialsReview_08_08.pdf
13
Process Synthesis-1

• Reaction 3
• Direct Chlorination
• Pyrolysis

14
Consider Separations

• VLE data
• Boiling Points
• Flash HCl from Rxn Products

15
Process Synthesis-1

• Separation System

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Process Synthesis-3

• Task Integration
• Reactor Condenser
• Separations

17
Onion Model of Process Design
18
Overall Process
19
Octane Reaction

• 2C2H4 C4H10 ? C8H18
• P 5 psi, T93C, X98 Conversion

20
Preliminary Flow Sheet
Flash ?P 2 psi Distillation Purge Stream
21
With Heat Integration
Without Heat Integration
22
What else can be done?

• Where is the heat duty for the Flash vessel
  coming from?
• Heat Exchanger coupling reactor feed to reactor
  product.
• Do we really need the flash vessel?
• Let distillation column do all the separation.
• Reactor heat duty
• Exo or Endo reaction?
• Where does it come from?

23
Onion Model of Process Design
24
Importance of Process Design

• In Preliminary Process Design
• 98 Operating Costs Committed
• 80 Capital Costs Committed
• Less than 10 Spent
• Design is Very Important
• But why is this so?

25
Why

• In Preliminary Design
• Decide on Raw Materials Operating Costs
• Decide Process
• Reactor System Capital Costs
• Separation System Capital Costs
• Recycle System Capital Costs
• Heat Integration Scheme Capital Costs
• Utilities Operating Costs