Flash-Point Measurements and Modeling for Ternary Partially Miscible Aqueous−Organic Mixtures

Abstract

Flash point is the most important variable used to characterize the fire and explosion hazard of liquids. This paper presents the first partially miscible aqueous−organic mixtures flash point measurements and modeling for the ternary type-I mixtures, water + ethanol + 1-butanol, water + ethanol + 2-butanol, and the type-II mixture, water + 1-butanol + 2-butanol. Results reveal that the flash points are constant in each tie line. Handling the non-ideality of the liquid phase through the use of activity coefficient models, the general flash-point model of Liaw et al. extended to partially miscible mixtures predicts the experimental data well when using literature LLE and the VLE activity coefficient model binary parameters to estimate sequentially the span and flash point in each tie line and the flash point in the mutual solubility region, respectively. The constant flash-point behavior in a tie line is also observed and predicted, in agreement with the VLLE tie line property that a single vapor is in equilibrium with all liquid composition on a tie line. For the aqueous−organic mixtures here studied, a deviation between prediction and measurements is observed, arising from the failure of the constant lower flammable limit assumption in the mutual solubility inert-rich region. Potential application for the model concerns the assessment of fire and explosion hazards and the development of inherently safer designs for chemical processes containing partially miscible aqueous−organic mixtures.

The maximum flammable content for binary aqueous–organic mixtures not to flash and their maximum flash points

“…A general model to estimate the flash points of miscible mixtures is reducible for binary aqueous–organic solutions as proposed previously . Another model, developed for partially miscible mixtures, was verified with measured flash point data and is reducible for binary, partially miscible, aqueous–organic solutions . Garland and Malcolm reported that aqueous organic acid mixtures do not flash at a temperature less than 218°F when the water content becomes too high .…”

“…The instrument operation met the ASTM D56 standard and employed a closed cup method. The configuration, options, and operation of the flash point analyzer are described in previous studies . The temperature of 50°C was selected as the expected flash point for the first test, and the measured value was used to adjust the expected flash point in the next test.…”

“…For an aqueous–organic mixture, the flammable components, air, and steam coexist in the vapor phase; the steam inerting effect on the LFL should be taken into account in the flash point estimation of such a mixture. However, the flash point prediction models mentioned above do not take into account the steam inerting effect . A model to estimate the inerting effect on the flammability limits is proposed in our previous study .…”

On the relation between azeotropic behavior and minimum / maximum flash point occurrences in binary mixtures of flammable compounds

“…The operation of the instrument was according to ASTM D56, which is a close cup method. The detailed operational parameters were described in previous studies [3e8, 15,16,25,33,43]. The flash point value of each composition was the average one, measured more than ten times.…”

Flash points measurements and prediction for binary miscible mixtures

“…The main reason maybe attribute to the fact that it costs a lot of manpower, time and material resources to determine the flash points of liquid mixtures by experiment. It may also explain the decision of the EC (European Community) CLP (Classification, Labeling and Packaging) to delay the classification of mixtures until 2015 (Liaw et al, 2010b).…”