Silencers for Flashing Geothermal Brine, Thirty Years of Experimenting

Abstract

The process of flashing geothermal brine at atmospheric pressure produces extremely loud noise level. In dealing with this problem, Hitaveita Suðurnesja has operated various types of silencers; the story goes back to the year 1976. In this paper the silencers will be described, emphasizing advantages, disadvantages, and problem solutions. In brine silencers the main problems relate to scaling and corrosion. Additionally, eliminating airborne brine drops, containing silica, is important because the silica opaquefies glass windows in the neighborhood and destroys glossy lacquer on cars. Design methods are described and practical solutions presented. It is important to emphasize that this development is not completed, but an ongoing process. The silencers described here are: round-centrifugal-tangential-inlet silencers, lateral-under-water-injection silencers, horizontal-over-water-inlet silencers, vertical-inlet (in a pool of brine) silencers. Control valves are usually adjacent to the silencer. Control valves, for controlling brine, tend to get stuck because of silica scaling. Some improvements are suggested. The main construction material of silencers is concrete. However, thermal stress causes cracking of the concrete. Different types of concrete and different reinforcements, such as stainless steel fibers and epoxy-coated rebar have been tried and will be described here.