Overview of Process Design Chapter 4 Terry A. Ring ChE

Where is Design used in Industry?

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

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?

How is Design Practiced Stage Gate Management Process Conception Preliminary Design Process Concepts Process Economics Management decision to go forward Intermediate Design P&ID’s Ask vendors for prices major pieces of equipment Reactor, Separators, HX, Utilities, tank farms Detailed Design Mechanical Engineering Equipment + Supports Where are all the nuts and bolts Piping elevation Electrical/Power Engineering Utilities

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)

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)

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 C2H4Cl2+H2O 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)

Gross Profitability Analysis-1 Start With Raw Material Costs and Product Prices

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(1.134)=11.94 ¢/lb

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_ITM

Example of Market Information http://www.ceramics.org/ASSETS/574195312DA149928805FFEA1242FECF/MaterialsReview_08_08.pdf

Process Synthesis-1 Reaction 3 Direct Chlorination Pyrolysis

Consider Separations VLE data Boiling Points Flash HCl from Rxn Products

Process Synthesis-1 Separation System

Process Synthesis-3 Task Integration Reactor & Condenser Separations

Onion Model of Process Design

Overall Process

Octane Reaction 2C2H4 + C4H10  C8H18 P= 5 psi, T=93C, X=98% Conversion

Preliminary Flow Sheet Flash ΔP= 2 psi Distillation Purge Stream

With Heat Integration Without Heat Integration

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?

Onion Model of Process Design

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?

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