Corrosion Rate in a steam condensate system

Company: Hynix Semiconductor, South Korea

Description of the problem and its negative consequences

In the process to manufacture microchips a lot of steam is needed. This steam is produced central in several big steam boilers, and is distributed to separate buildings of the plant. The condensate is  brought back to the boilers and reused to produce steam. Unfortunatelly the condesate system is build from low quality of carbon steel pipes.  The condensate system at Hynix is several kilometres long and has started to  have corrosion. Measurements of the condensate have shown an average of 2,5ppm iron. The internal quality requires feed water for the boilers with an iron content of less than 0,1ppm. Having higher iron content in the feed water of a boiler bears the risk of accelerating the corrosion in the boilers itself. This has to be avoided, as the boilers are a very expensive asset and cruical to the operation of the plant.
Due to this fact, the condensate which has already a high purity and temperature couldn't be reused in the boilers. So several 100m3 condensate per day couldn't be reused, and has to be dumped.

The solution

Merus was installed at several strategic places throughout the condensate system, as it is hardly possible to install Merus ring at each and every steam trap. During the trail, where several more places located where more Merus rings has to be installed in order to get a satisfying result.

In which way the customer checked the results of the trial

The iron content in the condensate was regularly checked by the laboratory of the client. The first weeks after the installation, not so much difference could be seen. All of a sudden, the iron content has increased very much. During several month of operation the iron in the condensate got less and less, until the value has stabilized at an average of 0,05ppm iron.
The client is now again able to reuse the condensate to produce new steam. It is not only a lot of water saved, but as well the expensive chemical preparation and the energy for heating fresh water.