Aruba – pre-TVC MED, 1959, Netherlands Antilles

Multi-effect distillation is a long-established technology, but was limited in efficiency and scope before the advent of vapour compression. In the 1950s, as MSF was being developed, Weir delivered these submerged-tube six-effect units to Aruba in the (then) Netherlands Antilles.

The array of submerged-tube six-effect distillers supplied to Aruba by Weir. – Jim Birkett

They were not exactly a runaway success; according to Jim Birkett: 'They worked sort of OK but had scaling problems and were energy inefficient. Aruba also needed larger, higher capacity units which were difficult to fabricate.'

Total plant capacity was 10,175m³/d, with 14 separate units – which certainly illustrates the problem with size of unit. Despite it proving a bit of an evolutionary dead end, the government was keen enough to issue a commemorative stamp showing the plant.

Meanwhile low-temperature MED, with thermo-vapour compressors (TVC), has had continued popularity in the Caribbean in a range of applications.