High Temperature Calculations in Geothermal Development
The large scale development of geothermal resources usually involves low to medium pressure steam separation from production wells where flashing to steam and water also occurs within the wells themselves. The temperature changes due to such flashing processes and the pH changes attendant on gas removal in the steam phase are the principal processes leading to mineral deposition in wells, separator plants, and waste water disposal pipelines or channels. In this chapter we will examine the Chemistry of waters resulting from steam (+ gas) separation with special reference to the common problems of silica and calcite scaling. In earlier chapters the effects of boiling on the deposition of metals and metal sulfides were examined. We shall also briefly touch on the calculation of the pH and composition of steam condensate; these data are frequently required in geothermal development studies where problems of pipeline corrosion, disposal of condensate or control of H<sub>2</sub>S emission are under consideration.