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Determination of Amine Volatility for CO 2 Capture. Thu Nguyen January 10, 2008 The University of Texas at Austin Professor Gary Rochelle. Outline Scope of Present Work – determine MDEA and PZ volatility Experimental Apparatus – introduce FTIR setup & operation
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Determination of Amine Volatility for CO2 Capture Thu Nguyen January 10, 2008 The University of Texas at Austin Professor Gary Rochelle
Outline Scope of Present Work – determine MDEA and PZ volatility Experimental Apparatus – introduce FTIR setup & operation Theory – use Raoult’s Law to measure volatility: partial pressure & activity coefficient) Results – explore volatility in terms of loading, temperature, & amine concentration Future Work -- outline of activities planned
Scope of Present Work • Determine PZ and MDEA volatility in blends of varying amine concentrations • Explore volatility in terms of Partial Pressure and Activity Coefficient • Ask how do these parameters behave with • i. CO2 loading • ii. Temperature • iii. Varying amine concentration • 3) Run experiments at 40ºC and 60ºC
Experimental Apparatus – Stirred Reactor Coupled with FTIR Analysis
-apparatus allows simultaneous measurements of CO2 solubility and amine volatility -sample line & FTIR are both kept at elevated operating temperature (180ºC) to eliminate condensation / adsorption of vapor amine to surface -FTIR is capable of performing multi-component analysis -gas is returned back to reactor at ~55ºC higher than reactor temp. to avoid rapid condensation / loss of amine species
Theory -activity coefficient is calculated using modified Raoult’s law yi P =γi * xi * Po yi : vapor phase mole fraction of species i (FTIR) P : total pressure at equilibrium (reactor pressure) γi : activity coefficient of species i (to be determined) xi : liquid phase mole fraction of species i (Amine Titration) Po: vapor pressure of species i (DIPPR database)
Vapor Pressure Equation (DIPPR Thermodynamic Database) Pvap (Pa) = exp [A + B/T + C(ln T) + DTE] where T is in Kelvin Pvap = exp [70.5 -7914/T – 6.65(ln T) + 5.21e-18(T)6 for PZ Pvap = exp [253.1 -18378/T – 34(ln T) + 2.34e-5(T)2 for MDEA model confirmed to provide good consistent estimates of vapor pressures within 283K – 785K range (includes experimental temperatures)
Conclusions PZ Partial Pressure ~2.2-19.3 ppm (40ºC) 15-66 ppm (60ºC) MDEA Partial Pressure ~5.2-6.9 ppm (40ºC) 24.8-28.6 ppm (60ºC)
Future Work -Continue amine volatility measurements for: -other blends of varying amine concentrations -focus on volatility in absorber lean & wash water stream -focus on volatility at stripper unit -ROC16 solution -Modeling experimental results to obtain activity coefficient prediction models -NMR Analysis -Heat Capacity Measurements