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wbourcier

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About wbourcier

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  1. Has anyone used GWB to model electrochemical processes (driven by externally applied voltage)? Can you swap in e- for O2(aq) and use e- as a reactant? Or do mass balance using e- as a proxy for current into or out of the system? I have tried and gotten error messages, but maybe there are workarounds? I am trying to model chemical reactions in a CO2 reduction reaction. Thanks for any help or advice! Bill
  2. wbourcier

    mass problem with Pitzer model

    Thanks. I am guessing one would only see a change in component masses (vs change in distribution of species) when starting with a system that is constrained in a kind of unusual manner (typical for pickup files). I have never noticed this for input files where I specifically constrain component masses. Thanks for your analysis! bill
  3. wbourcier

    mass problem with Pitzer model

    script attached below I will send dataset via email FIRST STEP- REACT Na-CARBONATE CAPTURE SOLUTION WITH CO2 Temperature is 25 C Thermo dataset: C:\Program Files\Gwb\Gtdata\thermo_da0ypfR2.wlbrev9.dat Working directory: c:\users\bourcier1\desktop\nahcolitetests\katherinepapercalcs Options: H-M-W Basis is: H2O 1 free kg CO3-- (swapped for HCO3-) 1.935 molal Na+ 3.87 molal OH- (swapped for H+) charge balance Reactants: Slide fugacity of CO2(g) to .1 Elemental composition In fluid Sorbed total moles moles mg/kg moles mg/kg ------------------------------------------------------------------------------- Carbon 3.771 1.176 1.322e+04 Hydrogen 111.0 108.4 1.023e+05 Oxygen 64.99 57.21 8.570e+05 Sodium 3.870 1.274 2.743e+04 Pickup system and re-run to confirm masses remain the same Elemental composition In fluid Sorbed total moles moles mg/kg moles mg/kg ------------------------------------------------------------------------------- Carbon 3.771 1.176 1.322e+04 Hydrogen 111.0 108.4 1.023e+05 Oxygen 64.99 57.21 8.570e+05 Sodium 3.870 1.274 2.743e+04 Fix CO2 fugacity and re-run Elemental composition In fluid Sorbed total moles moles mg/kg moles mg/kg ------------------------------------------------------------------------------- Carbon 3.771 1.176 1.322e+04 Hydrogen 111.0 108.4 1.023e+05 Oxygen 64.99 57.21 8.570e+05 Sodium 3.870 1.274 2.743e+04 Now add temperature path starting at 25 C – here the masses have changed Elemental composition In fluid Sorbed total moles moles mg/kg moles mg/kg ------------------------------------------------------------------------------- Carbon 3.842 1.247 1.394e+04 Hydrogen 111.1 108.5 1.018e+05 Oxygen 65.21 57.42 8.552e+05 Sodium 3.953 1.357 2.905e+04 verbatim input commands: React> show Temperature is 25 C Thermo dataset: C:\Program Files\Gwb\Gtdata\thermo_da0ypfR2.wlbrev9.dat Working directory: c:\users\bourcier1\desktop\nahcolitetests\katherinepapercalcs Options: H-M-W Basis is: H2O 1 free kg CO3-- (swapped for HCO3-) 1.935 molal Na+ 3.87 molal OH- (swapped for H+) charge balance Reactants: Slide fugacity of CO2(g) to .1 React> go React> pickup system React> show Temperature is 25 C Thermo dataset: C:\Program Files\Gwb\Gtdata\thermo_da0ypfR2.wlbrev9.dat Working directory: c:\users\bourcier1\desktop\nahcolitetests\katherinepapercalcs Options: H-M-W Basis is: H2O .9670762346433 free kg guess = 53.58010637651 HCO3- 1.175844707556 mol guess = 1.108927423502 Nahcolite (swapped for Na+) 2.595535888509 free mol guess = 3.87 CO2(g) (swapped for H+) .1 fugacity guess = -.09861940394104 No reactants specified. React> bal HCO3- React> go React> fix fug CO2(g) React> go React> temp start 25 end 110 React> go React> show Initial temperature is 25 C, final is 110 C Thermo dataset: C:\Program Files\Gwb\Gtdata\thermo_da0ypfR2.wlbrev9.dat Working directory: c:\users\bourcier1\desktop\nahcolitetests\katherinepapercalcs Options: H-M-W Basis is: H2O .9670762346433 free kg guess = 53.58010637651 HCO3- 1.175844707556 mol guess = 1.108927423502 (charge balance species) Nahcolite (swapped for Na+) 2.595535888509 free mol guess = 3.87 CO2(g) (swapped for H+) .1 fugacity guess = -.09861940394104 Reactants: Fix fugacity of CO2(g) Other "show" options: type "show show" React>
  4. I get an unexpected change in elemental masses after using "pickup" command and starting a polythermal simulation. I also hold a gas fugacity constant. if I run the picked-up system without a temperature change I get one result, if I add the temperature path I get another (both at the starting condition) Using Pitzer option ----------------------------------- Model loading of sodium carbonate with CO2 during flue gas CO2 capture The problem is that in using “pickup” command and fix fug command, the system changes composition React> pickup system React> show Temperature is 25 C Thermo dataset: C:\Program Files\Gwb\Gtdata\thermo_da0ypfR2.wlbrev9.dat Working directory: c:\users\bourcier1\desktop\nahcolitetests\katherinepapercalcs Options: H-M-W Basis is: H2O .9670762346433 free kg guess = 53.58010637651 HCO3- 1.175844707556 mol guess = 1.108927423502 Nahcolite (swapped for Na+) 2.595535888509 free mol guess = 3.87 CO2(g) (swapped for H+) .1 fugacity guess = -.09861940394104 No reactants specified. React> HCO3- bal (system will not converge unless I change charge balance species – common issue with pickup command) React> go Step # 0 Xi = 0.0000 Temperature = 25.0 C Pressure = 1.013 bars pH = 8.561 Ionic strength = 1.422313 Activity of water = 0.962599 Solvent mass = 0.967076 kg Solution mass = 1.067985 kg Solution density = 1.058 g/cm3 Chlorinity = 0.000000 molal Dissolved solids = 94485 mg/kg sol'n Hardness = 0.00 mg/kg sol'n as CaCO3 carbonate = 0.00 mg/kg sol'n as CaCO3 non-carbonate = 0.00 mg/kg sol'n as CaCO3 Rock mass = 0.218043 kg Carbonate alkalinity= 59724.18 mg/kg sol'n as CaCO3 Water type = Na-HCO3 Minerals in system moles log moles grams volume (cm3) ---------------------------------------------------------------------------- Nahcolite 2.596 0.414 218.0 100.2 _____________ _____________ (total) 218.0 100.2 Aqueous species molality mg/kg sol'n act. coef. log act. --------------------------------------------------------------------------- Na+ 1.318 2.743e+04 0.5367 -0.1504 HCO3- 1.109 6.127e+04 0.4848 -0.2696 CO3-- 0.1045 5676. 0.0878 -2.0378 CO2(aq) 0.002488 99.17 1.3651 -2.4689 OH- 5.320e-06 0.08193 0.6653 -5.4511 (only species > 1e-8 molal listed) Mineral saturation states log Q/K log Q/K ---------------------------------------------------------------- Nahcolite 0.0000 sat Na2CO3:7H2O -2.0257 Natron -1.7754 Thermonatrite -2.8964 Trona -1.9490 (only minerals with log Q/K > -3 listed) Gases fugacity log fug. ----------------------------------------------- CO2(g) 0.1000 -1.000 H2O(g) 0.03045 -1.516 In fluid Sorbed Kd Original basis total moles moles mg/kg moles mg/kg L/kg ------------------------------------------------------------------------------- H+ -0.0986 -0.0986 -93.1 H2O 53.7 53.7 9.05e+05 HCO3- 3.77 1.18 6.72e+04 Na+ 3.87 1.27 2.74e+04 Elemental composition In fluid Sorbed total moles moles mg/kg moles mg/kg ------------------------------------------------------------------------------- Carbon 3.771 1.176 1.322e+04 Hydrogen 111.0 108.4 1.023e+05 Oxygen 64.99 57.21 8.570e+05 Sodium 3.870 1.274 2.743e+04 Now heat the system holding PCO2 constant – first step should reproduce the output file from above React> fix fug CO2(g) React> temp start 25 end 110 React> go Since the starting temperature has not changed I expect to see the same output at step 0 But elemental composition has changed (see blue highlight below) PCO2 is at 0.1 bars in both cases, temperature is 25 C in both cases Step # 0 Xi = 0.0000 Temperature = 25.0 C Pressure = 1.013 bars pH = 8.581 Ionic strength = 1.520600 Activity of water = 0.960372 Solvent mass = 0.967076 kg Solution mass = 1.074209 kg Solution density = 1.061 g/cm3 Chlorinity = 0.000000 molal Dissolved solids = 99732 mg/kg sol'n Hardness = 0.00 mg/kg sol'n as CaCO3 carbonate = 0.00 mg/kg sol'n as CaCO3 non-carbonate = 0.00 mg/kg sol'n as CaCO3 Rock mass = 0.218043 kg Carbonate alkalinity= 63244.90 mg/kg sol'n as CaCO3 Water type = Na-HCO3 moles moles grams cm3 Reactants remaining reacted reacted reacted ---------------------------------------------------------------------------- CO2(g) -- fixed fugacity buffer -- Minerals in system moles log moles grams volume (cm3) ---------------------------------------------------------------------------- Nahcolite 2.596 0.414 218.0 100.2 _____________ _____________ (total) 218.0 100.2 Aqueous species molality mg/kg sol'n act. coef. log act. --------------------------------------------------------------------------- Na+ 1.404 2.905e+04 0.5331 -0.1259 HCO3- 1.170 6.426e+04 0.4778 -0.2526 CO3-- 0.1169 6317. 0.0837 -2.0095 CO2(aq) 0.002486 98.48 1.3932 -2.4606 OH- 5.422e-06 0.08301 0.6666 -5.4420 (only species > 1e-8 molal listed) Mineral saturation states log Q/K log Q/K ---------------------------------------------------------------- Nahcolite 0.0000 sat Na2CO3:7H2O -2.0318 Natron -1.7844 Thermonatrite -2.8765 Trona -1.8217 (only minerals with log Q/K > -3 listed) Gases fugacity log fug. ----------------------------------------------- CO2(g) 0.1000 -1.000 H2O(g) 0.03012 -1.521 In fluid Sorbed Kd Original basis total moles moles mg/kg moles mg/kg L/kg ------------------------------------------------------------------------------- H+ -0.111 -0.111 -104. H2O 53.7 53.7 9.00e+05 HCO3- 3.84 1.25 7.08e+04 Na+ 3.95 1.36 2.91e+04 Elemental composition In fluid Sorbed total moles moles mg/kg moles mg/kg ------------------------------------------------------------------------------- Carbon 3.842 1.247 1.394e+04 Hydrogen 111.1 108.5 1.018e+05 Oxygen 65.21 57.42 8.552e+05 Sodium 3.953 1.357 2.905e+04 Elemental composition has changed – but I did not change it!
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