Open channel flow in flash chambers is characteristic for the Multistage Flash Distillation (MSF) process. The flash chamber is rather simple, but an open point is still 'the optimal' orifice design. The orifice must ensure the pressure difference between adjacent chambers and its design is vital with respect to the evaporation/desuperheating of the brine. This should be as complete as possible, that means the deviation from the vapor liquid equilibrium should be as small as possible at the chamber exit. The deviation is called non-equilibrium temperature loss. Since non-equilibrium losses decrease the thermodynamical efficiency of the MSF-unit, they should be minimized. Based on a discussion of the essential process and design parameters influencing non-equilibrium temperature losses in MSF distillers and based on data collected from three different sources two empirical correlations have been developed and tested. The equations allow a reliable prediction of the non-equilibrium temperature loss and, even more important, show the impact of important design parameters such as stage length and weir load on the temperature loss. The equations are valid in the temperature range of 19 deg C < T < 58 deg C (24 deg C < T < 46 deg C for weir design). In the temperature range T > 58 deg C (46 deg C) experiments or data under real conditons are required. These equations are by far more accurate than other correlations proposed in the literature.
Improved equations for the calculation of non-equilibrium temperature loss in MSF
Verbesserte Gleichungen zur Berechnung des ungleichgewichtigen Temperaturverlustes in Mehrstufenentspannungsverdampfern
1996
9 Seiten, 7 Bilder, 3 Tabellen, 15 Quellen
Aufsatz (Konferenz)
Englisch
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