Chemical Reaction Engineering Reactor Design Pam Kubinski, Bethany Schmid, Joe Haupt

Overview Project Specifications Background Reactor Designs Results Optimization Comparison

Project Specifications Formation of Maleic anhydride from n-butane Fixed bed reactor design 40,000 Mtons/yr Reactor Designs Single reaction kinetics Isothermal, isobaric Isothermal including pressure drop Kinetics from literature Multiple Reactions-isothermal Multiple Reactions-including energy balance

Background of Maleic Anhydride Produced from oxidation of: N-butane Benzene N-butene Used in manufacture of Resins Lubricant Additives Surface Coatings Plasticizers Maleic Anhydride We are way better than benzene and butene 63% resin Butane 0.50 $/L Maleic Anhydride 1.70 $/kg

Fixed Bed Technology http://www.huntsman.com/performance_products/eng/Home/Maleic_Anhydride/Maleic_Anhydride/index.cfm?PageID=5727

Isothermal-Isobaric Reactor Design Reaction and Kinetics C4H10 + 3.5 O2 → C4H2O3 + 4H20 Added Constraints 80% Conversion No side reactions Bulk Density 900 kg/m3 Inlet Conditions 220 kPa 1.7 mol % Butane 400 C

Results As inlet temperature increases conversion of butane increases Conversion Profiles for Various Isotherms 63000 kg catalyst As inlet temperature increases conversion of butane increases

Pressure Drop Reactor Design Additional Constraints Used Ergun Equation Evaluated 5 mm particles 7 mm Particles ε = 0.44 www.andinst.com/dairy-pressure-products.php

Conversion Profiles Solid lines- isobaric Increased catalyst to account for pressure drop 63000 kg to 66150 kg (73 m3) Solid lines- isobaric Dotted lines- including pressure drop

Pressure Drop Results Held reactor volume constant 73.5 m3 66,150 kg Held reactor volume constant Varied tube diameter

Pressure Drop Results Held reactor volume constant Varied reactor length

Multiple Reaction Kinetics 1 2 3 C4H10 + 3.5 O2 → C4H2O3 + 4H2O C4H2O3 + O2 → 4CO + CO2 + H2O C4H10 + 5.5O2 → 2CO + 2CO2 + 5H2O

Molar Flow Profile Flows excluding inert

Isothermal Results

Including Energy Balance Additional Specifications Constant coolant temperature - 400 C Constant heat capacities- low Δ T Overall Heat Transfer Constant - 107 J/(m2-s-K) Multi-tubular Reactor

Coolant Temperature Results Hot Spot! Ta Selectivity 693 0.293 673 0.326 653 0.442 Talk about hot spot

Inlet Temperature Results

Optimal Reactor Design Optimization Results Optimal Reactor Design Inlet temperature 703 K Reactor Volume 253.5 m3 Number of Tubes 76,535 Conversion 0.860 Pressure Drop 9.97% Selectivity 0.319 Hot spot temperature 733.3 K Within pressure Increased inlet temperature Minimized reactor volume

Comparison Variable Final Design Optimized Inlet Temperature (C) 400 430 Conversion 0.803 0.860 Catalyst Weight (kg) 503,000 228,175 Reactor Length 9.85 5.94 Percent Pressure Drop 8.54 9.97 Heat Gain (coolant) 1.27 1.66 Selectivity 0.326 0.319 Hmm catalyst weight or volume

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