Volatility of MEA and Piperazine

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1 Volatility of MEA and Piperazine Department of Chemical Engineering The University of Texas at Austin Austin, Texas USA Marcus Hilliard, John M c Lees, Dr. Gary T. Rochelle June 16, 2006 This presentation was prepared with the support of the U.S. Department of Energy, under Award No. DE- FC26-02NT However, any opinions, findings, conclusions, or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the DOE or other sponsors.

2 Outline Background Method: Multi-component VLE Analysis: FT-IR Modeling: NRTL Results: Amine Volatility and γ i

3 Background Why is Amine Volatility Important in CO 2 Capture? What is the Motivation for Studying Amine Volatility in Blended Amine Systems?

4 Absorption/Stripping Process Condenser 2-4 mol H 2 O/mol CO 2 Clean Gas 1% CO 2 Absorber o C 1 atm Stripper o C 1-2 atm Flue Gas 10% CO 2 Rich Solvent Lean Solvent Reboiler

5 Solvent - CO 2 Capture 30 wt% MEA - Mature technology K 2 CO 3 /PZ MEA/PZ Increased in capacity and faster rates Hilliard (2005) Aspen Plus ENRTL Model Motivation for Modeling Capacity Heat of Desorption Complex MT with Chemical Reactions Speciation Cost of Amine Make-up or Recovery - Amine Volatility

6 Apparatus for Vapor Speciation Operating Conditions: 1 atm o C Setpoint - Equilibrium hr

7 FT-IR Analysis transmission spectrum subtracted standardized spectrum N 2 reference spectra H 2 O (vol%) 4, 6, 8, 10, 12, 24, 26, 28, 30 MEA (ppm v ) 100, 500, 1000, 2000, 5000, 10000, background spectrum x f 1 x f 2 absorbance spectrum Beer-Lambert Law difference is minimized measured values

8 100 Experimental Apparatus Benchmark - DIPPR Partial Pressure of H 2 O [kpa] 10 e H O 2 ~ 4.4% DIPPR Kell et al. (1984) This work Temperature ( o C)

9 Experimental Apparatus Benchmark MEA Study 10 Partial Pressure of MEA [kpa] e ~ 14.6% DIPPR Matthews et al. (1950) Engineering Sciences Data (1979) This work Temperature ( o C)

10 Aspen Plus - NRTL Model c ion 0: ENRTL reduces to NRTL Developed by Renon and Prausnitz (1968) E α21τ 21 α12τ 12 G τ 21e τ12e = x1x2 + α τ α τ RT x1 + x2e x2 + x1e lnγ e Bij τ ij = A ij + +Cij lnt + DijT τ ii = τ jj = 0 T α12τ 12 α21τ = x 1 τ τ α12τ 12 x2 + x1e x x e e ( α ) 21τ = H 2 O 2 = Amine

Aspen s Data Regression Package - Maximum Likelihood Principle Determining the parameter values were carried out using an algorithm derived by Britt and Luecke (1973) Objective function based on the

11 Aspen s Data Regression Package - Maximum Likelihood Principle Determining the parameter values were carried out using an algorithm derived by Britt and Luecke (1973) Objective function based on the following assumptions: Where all variables are adjusted and weighted by the standard deviation (i.e. experimental data are not error free) Not Simple least squares regression. Q 2 N N i j U j, adj U j, obs = WU j σ i j U where the summation is over all of the measured variables, N i, for all of the data points, N j. j

12 Absolute Average Relative Deviation for the H 2 O-MEA-PZ systems MEA/H 2 O: 3 parameters A B PZ/H 2 O: 4 parameters MEA/PZ/H 2 O: 2 parameters A A A A A H O / MEA H O / MEA 2 2 MEA / H O H O / PZ H O / PZ H O / PZ PZ / H O 2 MEA / PZ PZ / MEA B C No. Name Data type # Papers AARD (%) 1 MEA/H 2 O TPx Y MEA This work 17.6* Y H2O 10.6* T f H mix C p PZ/H 2 O Y PZ This work 23.0* Y H2O 5.4* TPx MEA/PZ/H 2 O Y MEA This work 11.1* Y PZ 13.0* Y H2O 3.0*

13 Measured multi-component VLE MEA-H 2 O Study 3.5, 7, 23.8 m MEA PZ-H 2 O Study 0.9, 1.8, 2.5, 3.6, 5.0 m PZ MEA-PZ-H 2 O Study 3.5, 7 m MEA + 1.8, 3.6 m PZ

14 0.1 Experimental Results for 7 m MEA m PZ Study Partial Pressure of Species i [kpa] 0.01 e MEA / PZ ~ 11.9% e MEA ~ 27.1% e MEA / PZ ~ 11.2% ~ 22.4% PZ (7/3.6) MEA (7/3.6) Aspen PZ (7/3.6) Aspen MEA (7/3.6) PZ (3.6) MEA (7) Aspen PZ (3.6) Aspen MEA (7) e PZ Temperature [ o C]

15 Regressed Results for MEA/H 2 O Activity Coefficient for MEA at Infinite Dilution o C This work Posey (1996) Austgen (1991) /T (1/K)

16 Excess Enthalpy (kj/mol) for MEA at Infinite Dilution in Water γ MEA E d ln H = R d 1/ T o For a temperature range from 25 to 80 C: H E Source Touhara (1982) Kim et al. (1987) to Austgen (1991) to Posey (1996) to This work

17 0 Predicted Results for MEA/H 2 O Excess Enthalpy [J/kmol] Touhara et al. (1982) Posey (1996) 120 o C e Posey ~ 8.52% e Touhara ~ 5.63% Mole Fraction of MEA

18 10 2 Regressed Results for PZ/H 2 O Study Hilliard (2005) - UNIFAC This work Piperazine Activity Coefficient o C o C Mole Fraction of Piperazine

19 Excess Enthalpy (kj/mol) for PZ at Infinite Dilution in Water ( ) = = E H H sol Hdis H fus γ PZ E d ln H = R d 1/ T o For a temperature range from 25 to 80 C: H E Source to H dis - H fus to Hilliard (2005) to This work

Conclusions Relative Volatility of MEA & PZ is ~ unity PZ activity coefficients are 567% lower than UNIFAC predictions Simultaneous regression may help improve Sequentially regressed parameters In 7

20 Conclusions Relative Volatility of MEA & PZ is ~ unity PZ activity coefficients are 567% lower than UNIFAC predictions Simultaneous regression may help improve Sequentially regressed parameters In 7 m MEA/3.6 m PZ at 40 o C P PZ = Pa P MEA = Pa H E at Infinite Dilution from 25 to 80 o C PZ: kj/mole MEA: to kj/mole Confident in this apparatus to generate new VLE data

21 Thank you for your attention. Any questions?

Py x P P P. Py x P. sat. dq du PdV. abs Q S. An Innovative Approach in the G U TS PV P P G U TS PV T H U PV H U PV. abs. Py x P. sat.

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