CHEMICAL REACTOR CHARATERIZATION GOALS Outline basic concepts Review reaction chemistr Develop basic definitions of performance Identify important reactor variables o Review reaction thermodynamics /2099 Chemical reactor Characterization
9/20/99 Chemical Reactor Characterization 1 CHEMICAL REACTOR CHARATERIZATION GOALS: u Outline basic concepts u Review reaction chemistry u Develop basic definitions of performance u Identify important reactor variables u Review reaction thermodynamics
PURPOSE OF A CHEMICAL REACTOR The purpose of a chemical reactor is to convert less desirable feed components more desirable output components. Q Convert a cheap raw material into a more valuable products, e.g., natural gas into ammonia, ethylene into polyethylene, etc Convert hazardous compounds into ones that are environmentally benign, e.g., hydrogen sulfide into sulfur, carbon monoxide into carbon dioxide. PCB's into C02 H20 and HCl /2099 Chemical reactor Characterization
9/20/99 Chemical Reactor Characterization 2 PURPOSE OF A CHEMICAL REACTOR The purpose of a chemical reactor is to convert less desirable feed components into more desirable output components. uConvert a cheap raw material into a more valuable products, e.g., natural gas into ammonia, ethylene into polyethylene, etc. uConvert hazardous compounds into ones that are environmentally benign, e.g., hydrogen sulfide into sulfur, carbon monoxide into carbon dioxide, PCB’s into CO2, H2O, and HCl
CHEMICAL REACTIONS o a chemical reaction is an exact recipe for converting raw materials into products or byproducts o The key concept is that of the stoichiometric coefficient o The stoichiometric coefficient ai specifies the mols of the ith component produced per mol of the jth reaction. Reactions take place in mols, not mass!! /2099 Chemical reactor Characterization
9/20/99 Chemical Reactor Characterization 3 CHEMICAL REACTIONS u A chemical reaction is an exact recipe for converting raw materials into products or byproducts u The key concept is that of the stoichiometric coefficient u The stoichiometric coefficient aij specifies the mols of the ith component produced per mol of the jth reaction. u Reactions take place in mols, not mass!!
EXAMPLE #1 CH4+202->C02+2H20 CH4+11202-C0+2H20 i Componen CH4 02 2-1.5 C02 CO 5H20 22 /2099 Chemical reactor Characterization
9/20/99 Chemical Reactor Characterization 4 EXAMPLE #1 1) CH4 + 2 O2 --> CO2 + 2 H2O 2) CH4 + 1 1/2 O2 --> CO + 2 H2O i Component ai1 ai2 1 CH4 -1 -1 2 O2 -2 -1.5 3 CO2 1 0 4 CO 0 1 5 H2O 2 2
CONVERSION AND SELECTIVITY o Conversion is that fraction of component entering a reactor that is converted to products and byproducts o Conversion is generally based on one or more independent key components of primary interest in the reaction system o The selectivity of a key component with respect to a specified product is the fraction of that component converted to the specified product divided by the total conversion of the key component. /2099 Chemical reactor Characterization 5
9/20/99 Chemical Reactor Characterization 5 CONVERSION AND SELECTIVITY u Conversion is that fraction of component entering a reactor that is converted to products and byproducts u Conversion is generally based on one or more independent key components of primary interest in the reaction system u The selectivity of a key component with respect to a specified product is the fraction of that component converted to the specified product divided by the total conversion of the key component