Operating experience and performance data of an advanced barge-mounted VTE/VC seawater desalination plant

The floating desalination demonstration plant “MEDA” presents an advanced concept to produce fresh water from seawater with low energy consumption. At first step of ts demonstration phase, MEDA was operated at Helgoland in the North-Sea at its design capacity of 5000 m³/day and a performance ratio of 22 to 1 kg/kg. The 24 effect VTE evaporator combined with two vapor compression topping effects operated at a max. feed temperature of 135 °C with sulphuric acid pretreatment. High heat transfer rates were obtained using foamy upflow in double-fluted evaporator tubes without inter-effect pumps. Data were obtained for an alternative pretreatment system for feed make-up using a fluidized bed ion exchanger system operating in the countercurrent mode. Calcium ion content in the feedwater was demonstrably reduced by more than 90 %. This paper presents and analyses the above performance results.