Abstract
With regard to non-equilibrium temperature difference NETD generated in flash evaporation in multi-stage flash evaporators, a comparison was made between the empirical equations for empty stages proposed so far and the actually measured values obtained in empty stages so far. There was introduced the mean residence time of liquid in each stage in consideration of the difference in stage length.
The empirical equation of BLH Eq.(6') chowod the beet correlation with the measured values obtained in empty stages longer than 3.45m, but it showed the least correlation with the measured values obtained in empty stages shorter than 2.13m because of the effect from varied flow pattern of liquid.
For the purpose of pursuing the effects of various types of flash enhancers installed in each stage, another comparison was made between the measured values obtained in stages with enhancers and the empirical equation of BLH chosen as the base reference.
In case an enhancer was installed in a comparatively long stage, it made little contribution to the reduction of NETD, but in case it was installed in a short stage, it caused a conspicuous decrease in NETD, reducing NETD as low as those obtained in the case of long empty stages.
