Prof. Gary T. Rochelle CPE 5.462, 2 MS, 8 PhD Projects/funding for MS or PhD Technology Area CO 2 Capture from Flue Gas ( to address Global Climate Change) By Aqueous Absorption/Stripping Fundamental Areas Mass Transfer with Reaction in the Boundary Layer Applied Aqueous Solution Chemistry Aqueous Thermodynamics Aqueous Reaction Kinetics Applied Process Simulation

System for CO 2 Sequestration BoilerESP Flyash FGD CaSO 4 CaCO 3 Abs/Str Disposal Well Power 30 psia Steam CO 2 Coal Net Power

Absorb 50°C 1 atm Steam 30 psia CO 2 Strip 117°C 2 atm SO 2, HCl, NO 10% CO 2 5% O 2 12% H 2 O 30% MEA Lean Rich H2OH2O Purge to Reclaim MEA Absorption/Simple Stripping   C

Practical Problems Energy = 20-40% of power plant output –Steam for stripping –Gas pressure drop –CO 2 Compression Amine degradation –10% of cost –Environmental impact Capital Cost –5 x 50 ft diameter absorbers and strippers –50 ft packing

Approaches to Practical Problems Better Solvents –Faster: promote by piperazine (PZ) –Evolve: Monoethanolamine (MEA)/ PZ –Lower  H: K 2 CO 3 /PZ –Oxygen scavengers Better Processes –Vacuum Stripping or Vapor recompression –CaSO 4 /K 2 SO 4 Precipitation Better contacting –Packing to get G/L area

Fundamental Problems Model Thermo with high salt (K + ) & amine –Electrolyte NRTL model –Maximize solvent and CO 2 concs Measure Mass transfer with chemical reaction –Find feasible solvent with faster rates Measure oxidative degradation/corrosion –Cu ++ inhibits corrosion, catalyzes degradation

Applied Problems Identify Packing with max area at min cost –Characterize and model wetted area Innovate flowsheets to minimize Q –Simulate multistage contacting –Simulate Vacuum stripping Control complex chemistry to minimize Q

Laboratory Projects Mass Transfer with chemical rxn – K 2 CO 3 /EDA –Wetted Wall Column –NMR Degradation –Oxidative of Ethylenediamine –Thermal of MEA/PZ Solvent Reclaiming –Evaporation of PZ/MEA –Crystallization of CaSO 4 or K 2 SO 4

Pilot Plant Projects Validate Models for MEA/PZ –16.8-inch x 20 ft Absorber/stripper Test and Develop Innovative Packing –16.8-inch x 10 ft PVC Absorber –Low gas velocity Demonstrate Process Innovations –Vacuum Stripping –Multistage contacting

Modeling Projects Fundamental models for K 2 CO 3 /EDA –Thermodynamics/VLE/Speciation –Mass transfer with Chemical Reaction Integrated Absorber and System Models –MEA/PZ –Vacuum Stripping –Multistage stripper System optimization/integration –Integrate with Power Cycle

Solvent Alternatives Functions –Capacity by reversible reaction Thermodynamics and stoichiometry –Fast mass transfer: kinetics at interface Three types of chemistry –CO 3 = + CO 2 +H2O <> 2 HCO 3 -  H=5 kcal/gmol, very slow –R 3 N + CO2 + H 2 O <> HCO R 3 NH +  H=14 kcal/gmol, slow –2R 2 NH + CO 2 <> R 2 N-COO - + R 2 NH 2 +  H=22 kcal/gmol, fast

Reaction Chemistry… + ++ …For Potassium Species …For Piperazine Species 2 + System Solvent — 3.6 m K 2 CO 3 /0.6 m PZ

Mass Transfer Report as normalized flux—k g ´ Extract rate constants –Use in conjunction with NMR data –Limited by knowledge of the interface

Wetted Wall Column Gas in Liquid in Gas out Liquid out ParaffinOil

CO 2 Absorption at 60 o C

NMR Speciation Analysis PZ(COO - ) 2 PZ/H + PZCOO - /H m K 2 CO 3 /0.6 m PZ, T = 333K

Degradation Experiment

Oxidative Degradation By Oxygen in flue gas –Monethanolamine make ammonia –Piperazine makes ethylenediamine Dissolved metal catalyze –Fe ++ –Corrosion inhibitors: Cu ++, V +5 Strip O 2, add chelating agents, add oxygen scavengers

Lean Solvent Blower TI Distributor Recycle CO 2 Makeup CO 2 Air Vent/ makeup C.W. 15 o C CO 2 Analyzer Rich Solvent Pilot Absorber 16.8-inch ID, 20 ft of packing, SS 40 – 60 o C 1 atm Storage

Pilot Stripper 16.8-inch ID, 20 ft packing, CS Lean Solvent Steam Distributor Steam Rich Solvent CO 2 Recycle Reflux CW C.W. 15 o C Storage

System Modeling in AspenPlus Rate-Based contacting: RATEFRAC Electrolyte Thermodynamics Mass Transfer with Chemical Rxn Simultaneous Heat Transfer Flexible configuration and conditions