Antiscalant for MED Units - Lw - Light Water solution - Proven Experience in Water Treatment and Process Chemicals

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Antiscalant for MED Units



In the MED process, distillation takes place in a series of chambers, or effects, operating at progressively lower pressures. Within each effect, cool seawater is sprayed over a heat exchanger tube bundle while steam flowing through the tubes is condensed into pure product water. Outside the tubes, the thin seawater film boils as it absorbs heat from the steam. The resulting vapour is introduced into the tubes in the next effect. The process is repeated through the length of the plant. The efficiency of the MED process can be increased with the introduction of vapour compression to energise low pressure steam going into the evaporator.

Plant Information

A Public company, owned for 75 % by private company (leader in services for water management) and for 25 % by Public Authority, is managing the biggest MED (Multiple Effect Distillation) built in EU producing 36,000-m3/d using the technology of thermal vapour compression. The system has been treated with an antiscalant supplied by a multinational firm since the start up of the units (1998).

 Customer Challenge

The client was looking  to find  an alternative supplier able to provide same or better technical results but increasing the site service support since one of the main task was to reduce manpower. The solution offered has to be reached without increasing the costs.

LW Solution

LW has in place a distribution agreement with BASF in supplying SOKALAN PM antiscalant, thanks to the business relationship between the two companies, LW proposed and agreed with the client the following plan:

  • SOKALAN PM15I, the product to be tested;
  • Field trial to be in place for two months;
  • Shutdown of the unit every two weeks for inspection;
  • Perfomance evaluation based on TBT, G.O.R (Gained Output Ratio);

The results commonly agreed by the parties have been:

  • SOKALAN PM 15I  was able to maintain clean all heat exchanger surfaces;
  • GOR was always in the range of 13,5-15;
  • Product SOKALAN PM15I was showing an improvement on plant efficiency average (GOR) in the range of  3-5 % respect to previous chemical treatment use;


LW was able to reach all the targets requested and agreed by the customer, after the trial LW has been awarded as the best supplier and till now LW is  working on this site  on continuous basis enlarging the supplying and services  to other utilities.