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[OLD] Flash calculations (two supersaturated fluids)


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From: Ross McCartney

Subject: Flash calculations (two supersaturated fluids)

I want to undertake flash calculations involving two supersaturated fluids and I'm interested in the amount of precipitate that forms when they are mixed. I can add a supersaturated reactant {A} to my second fluid {B} by setting precip=off when generating the reactant {A} pickup file. However, when I undertake the flash calculations, with precip=on and dump=off, the solids precipitated from B at X=0 are kept in the system as solids throughout the flash simulation. They are not removed in proportion with the removal of fluid B as reactant A is added. As a result, when X=1, the system contains all the reactant plus the original B solids. This means that the simulation overestimates the amount of precipitate forming from all mixtures of A and B and from A itself. If I set dump=on, the simulation underestimates the precipitate forming from all mixtures of A and B and B itself. Am I trying to undertake calculations that GWB cannot handle or are there alternatives for modeling deposition resulting from the mixing of two supersaturated fluids from X=0 to X=1?

 

From: Craig Bethke

Subject: Re: Flash calculations (two supersaturated fluids)

To run the path you envision, I suggest using the "react" command. For example, suppose that equilibrating fluid B produces 100 mg of gypsum. Then the command react -100 mg Gypsum will remove ("titrate out") the mineral along with the fluid. (Please note the negative sign in the command). By the way, instead of toggling the "precip" setting, you can do the command "pickup reactants = entire" instead of "pickup reactants = fluid". This might save a little effort.

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