Effect of spray nozzle orientations on the performance of the flash evaporator of LTTD desalination plant

Abstract

This work discusses the influence of spray or feeder nozzle orientation on the production rate, non-equilibrium temperature difference (NETD), water quality, and flash efficiency of the evaporator of 100 m3/d capacity low-temperature thermal desalination plant. To investigate this, the flash evaporator of the Kavaratti LTTD plant was taken for the study which is located at UT Lakshadweep Islands. This plant is being operated continuously for supplying potable drinking water to the local Island community. In the present work totally three different nozzle orientations (upward, downward, horizontal) were tested for the performance analysis of the flash evaporation. Experimental studies were conducted for different operating conditions and relevant data were collected for comparative analysis. It was observed that the orientation of the feeder or spray nozzle significantly influences the production rate, NETD, product water quality, and flash efficiency in the evaporator, and the mechanism responsible for variation in the performance of flash evaporation with respect to feeder orientation is also discussed. Upward nozzle delivers a good performance of up to 1.4 times the evaporation rate, 85%–90% flash efficiency, and lowest thermal loss (NETD) of 0.69°C to 0.75°C compared to horizontal and downward nozzle orientations. As far as product water quality is concerned, the downward-facing nozzle gives better quality or low salinity product water than the other two nozzle orientations.