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Polyvinyl alcohol (PVA) is produced from vinyl acetate (VAc) via hydrolysis with sodium hydroxide. Within this process, methanol is used as a solvent and is continously reprocessed by means of distillation. As part of a capacity expansion of a polyvinyl alcohol plant in germany, the process engineers were looking for ways to increase the energy efficiency of the process.
The main problem is: One cannot see what is actually happening inside the columns and piping. All process information is based on the data retrieved from the measuring instruments installed in the system.

In order to gain a better understanding of the processes taking place inside the methanol distillation column, the plant engineers commissioned FLEXIM with a measuring service which involved the recording of the flow rates on various measuring points. The findings gained with the portable FLUXUS clamp-on ultrasonic flow meter proved so useful, that the plant operator decided to continuously monitor two measuring points at the bottom of the column with a permanently installed FLUXUS meter.
Of course, the measuring points were set up during ongoing operation without any impact on production. Based on the measurements, the heat transition coefficient (K-value) of the natural circulation evaporator could be improved by making an operational adjustment to the column. Thus, the investment costs for the measuring technology could be amortised in a very short period of time.


  • Accurate and reliable flow measurement from the pipe wall outside
  • No risk of toxic and highly flammable medium leaking
  • No wear and tear - virtually maintenance free
  • Easy to retrofit during ongoing operation - complete plant availability
  • No pressure loss
  • Rapid amortisation through effective optimisation of the process