I have a need to determine the adiabatic temperature and pressure of a runaway polymerization (emulsion) reaction for worst-case scenario evaluations for relief design of a batch reaction. The main constituents can be assumed to be water, ethyl acrylate, and methyl methacrylate, at a ratio of 1.5/1/0.53.
Given a known quantity and heats of polymerization, I've calculated the total heat evolved from the reaction. I've also estimated the heat capacity of the emulsion during the process (a bit tricky, as the heat capacity changes slightly when going from monomer -> polymer), and estimated a final temperature of the solution.
This estimation was done assuming a small vapor space, such that the enthalpy of vaporization did not absorb very much of the overall heat generated.
My problem comes when trying to estimate vapor pressure. EA and MMA are poorly soluble in water, so I don't think typical fugacity calculations apply. All three components have similar vapor pressures (MMA and EA boil at 1 atm at 213 F and 211 F, respectively).
I also don't think Raoult's law would apply, as it assumes a mixture of components, i.e. P = x1*psat1 +x2*psat2 + ...
I'm thinking this system may behave like the following: it would be as if each component were separated into individual containers with a shared vapor space, and are heated up to the same temperature. The EA and MMA would be in one container, such that "P(sat of EA and MMA) = x1*psat1 +x2*psat2" applies", and water in the other container.
Edit: Looked at VLLE calculations (doh!), and for pure, insoluble components, it does seem like like the sum of the vapor pressures are correct (activity coefficients are near 1 due to insolubility).
So, for this system, all components have near equal vapor pressure at 100 C. Thus the total pressure of the system at 100 C would be ~30 psig. Am I missing something?
Edited by Na3BrO, 14 June 2018 - 11:41 AM.