The industrial use of geothermal energy for process heating in New Zealand is anticipated to double, and possibly treble, over the next 15 years. The forest processing industries are likely to remain the largest users, as maturing exotic forests exist close to the known geothermal fields.

DSIR engineers have recognized the need to improve the technology used in these geothermal energy supply plants. Development projects are aimed at raising the thermal efficiency and reducing the environmental impact of the existing single-flash recovery system. Projects implemented include performance monitoring of production geothermal heat exchangers, field testing of an experimental heat exchanger, and demonstration of silica and arsenic removal processes to treat geothermal water.

Future advances are illustrated by a simple model for a process steam generation plant which would be a common operation for any industrial user. Flow sheets are presented to compare the merits of multiflash, total flow, and cascade heat exchanger systems combined with both reinjection and surface disposal methods for the geothermal effluents.

End_of_Article - Last_Page 965------------