Thermodynamic Effects on Scale Inhibitors Performance at Multiflash and Combined Cycle Geothermal Power Systems

Abstract

In water-dominated reservoirs, binary and single flash cycle geothermal power systems are widely used for power generation around the world and the reservoirs temperatures generally indicate moderate or moderate-high temperatures at depth. In these systems, controlling and understanding the effects of pressure and temperature changes on geothermal fluids much easier than advanced geothermal systems. Depending on geothermal reservoir rocks, water-rock interaction can be explained and expected scale types can be determined easily and suitable inhibitors may be determined with short term field tests before start up process. Although energy efficiency higher than binary and single flash systems, power generation from multiflash (double, triple) and combine (flash systems+binary) systems are still limited in the world. In these systems, reservoir temperatures are observed quite high and water- steam (with gas) phases separated more than one time. It concludes that pressure and temperature dramatically drops after each separation system when geothermal fluids reach to surface. This time the types and compositions of scales may show differences beginning of the production; high pressure separation to low pressure separation station. The power system may require that different scale inhibitors and different inhibitor dosage points to protect itself.