Wairaki corrosion cut

Press, 19 May 1981, Page 19

Wairaki corrosion cut

PA Wellington A corrosion inhibitor which costs $5O a week has averted ,a refit of the Wairakei geothermal, power station, which would have cost $9 million, according to the Electricity Division. Earthquakes in the area have increased concentrations of Carbon dioxide and other gases in steam drawn from the field for generation. The gases have been corroding pipelines to the power house. ; A. thermal scientist with the division, Mr D. Nicholson; said, that the problem had been becoming urgent and could have required an ex-

pensive replacement of the pipelines. He said, “But we have now got a simple corrosion inhibitor costing $5O a week that takes care of the extra car- . bon • (dioxide from. • earth--quakes.” During the last year there had been between 10 and 12 significant earthquakes. Aci- • dity had increased after each one to about 5.4ph for about a week compared with the normal acidity level of 7.5ph. . The station is expected to continue generation for about 15 more years and is being prepared to handle hotter bore water from the nearby Te Mihi field.

The heat content of the Wairakei field has dropped from about 250 deg in the mid-1960s to about 225 deg. Three Te Mihi wells are close to 240 deg and studies which aire expected to be completed by mid-1983 or 1984 are paving the way for a 2km pipe which will'connect the field with the station. . Estimates in the mid-1960s suggested that the Te Mihi field had sufficient steam for a 150 MW power station. It had previously been regarded as uneconomic to tap the field with the 140 MW Wairakei-station.