Rapid Phase Transition

There is a lot of documentation on LNG and water, as an example of Rapid Phase Transition (RPT). We have a scenario where solvent is inadvertantly added to a reactor/kettle of hot resin. When I look at this scenario using Aspen Plus (RBatch) there is rarely an indication of overpressure potential. I think this is because Aspen uses perfect, instantaneous mixing in the calculations. In the virtual simulation world, the volatile solvent is instantly distributed throughout the initial charge of hot resin and the concentration is so dilute Rauolt’s law predicts a low, slow build-up of total pressure. In reality, the hot resin is viscous (> 1,000 cP) and it is not uncommon to see solvent pooling on top of the resin before it can get mixed in. So, I’m wondering if this system can RPT. Does anyone know/have any literature that explains RPT in general nomenclature and doesn’t rely so heavily on the LNG/water pair? Something I could apply to my resin/solvent system(s). Thank you.

Not knowing anything about RPT, I did some Googling. While I don’t think I found a definite solution, I ran across these:

Understand_LNG_Rapid_Phase_Transitions_RPT.pdf (1.1 MB)

The PDF source is a discussion with LNG and water, but it presented an analysis method that may be applicable to your situation. The journal article discussed multiple system types (at least that’s what the abstract indicates).

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Those references look good. Thanks! I wonder if @don1980 has an opinion on this subject and those references.

Well, I’m very late to the game - sorry. This is an interesting topic (RPT). RPT can occur when a hot fluid (or surface) exceeds the superheat-limit temperature (SLT) of the “cold” fluid (e.g. water coming in contact with hot oil). If the hot fluid is > SLT of the cold fluid, then vaporization can occur in microseconds, a timeframe that is analogous to a detonation. This rapid phase change can produce shock waves, just like those of detonations. When the SLT of the cold fluid is exceeded, a PSV can’t provide protection, because it can’t get open fast enough.

When evaluating the cases in which this type RPT is possible, look up the SLT of the cold fluid and compare that to the hot fluid temperature. If the hot fluid is greater than the SLT, then recognize that other forms of protection (other than PSVs) are needed. this generally means a design change to minimize to possibility of the two fluids coming into contact.

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Yes, very interesting. From my self-studies, it seems this is a developing field. At present, the approaches do not seem fully consistent to me. I see the mechanisms explained using the Leidenfrost point, the homogeneous nucleation temperature (Tsl) and the superheat-limit temperature (SLT) of the “cold” fluid. Are these all synomous or closely related? I do have a lot of questions. Would a rupture disk be fast enough to releave a RPT? I see the risk of a RPT is calculable, but are RPT’s consistent enough such that their relief rate is calculable? Or, is their relief handled differently? I did make some notes (14.1 KB) from one or more of the references I’ve collected. It’s a work in progress.