文档介绍：DESIGN METHODOLOGY II: INPUT-OUTPUT DECISIONS GOAL -- Choose the process chemistry and feedstock most appropriate to the plant to be designed and determine the associated economic potential. 11/19/99 Input-Output Structure 1 BASIC LEVEL II DECISIONS u Choice of reaction chemistry u Choice of raw material feedstocks u Determination of need for vapor recycle u Evaluation of economic potential for process 11/19/99 Input-Output Structure 2 CHOICE OF REACTION CHEMISTRY The choice of reaction chemistry involves the following considerations: u Source of the chemistry to be employed ð Developed in-house ð Freely available (patents expired) ð Available only through a license u Availability of feed stocks u Choice of process type u Environmental considerations 11/19/99 Input-Output Structure 3 EXAMPLE #1 Chemistries available to manufacture Vinyl chloride (from Seider et al, Process Design Principles) uDirect chlorination of Ethylene C2H4 + Cl2 --> C2H3Cl + HCl (Only half the Cl2 converted to vinyl chloride) u Thermal cracking of Dichloroethane via Oxychlorination of Ethyelene C2H4 + 2HCl + 1/2 O2 --> C2H4Cl2 + H2O C2H4Cl2 --> C2H3Cl + HCl (Uses HCl instead of Cl2, but requires two reaction steps) 11/19/99 Input-Output Structure 4 EXAMPLE #1 (Cont’d.) u Balanced Process for Chlorination of of Ethylene C2H4 + Cl2 --> C2H4Cl2 C2H4 + 2HCl + 1/2 O2 --> C2H4Cl2 + H2O 2 C2H4Cl2 --> 2 C2H3Cl +2 HCl (Converts all Cl atoms to Vinyl Chloride) 11/19/99 Input-Output Structure 5 EXAMPLE #2 Chemistries available for the manufacture of maleic anhydride: u From benzene C6H6 + 3 1/2 O2 --> <(.CHCO)2>O + 2 CO + 2 H2O C6H6 + 4 1/2 O2 --> 6 CO2 + 3 H2O u From butane C4H10 + 3 1/2 O2 --> <(.CHCO)2>O + 4 H2O C4H10 + 4 1/2 O2 --> 4 CO + 5 H2O C4H10 + 6 1/2 O2 --> 4 CO2 + 5 H2O 11/19/99 Input-Output Structure 6 EXAMPLE #2 (Cont’d.) u Maleic Anhydride from Benzene ð High selectivity at plete conversion - no recy