On-Line Tests of Organic Additives for the Inhibition of the Precipitation of Silica from Hypersaline Geothermal Brine

摘要

A number of compounds have been screened as potential scale control agents by examining their effect on the precipitation of silica from Magmamax No. 1 brine. The substances were tested using the Lawrence Livermore Laboratory scale-control test system at the Niland, California, test site. Solutions of the test substances were injected into flowing brine at approx. 200 exp 0 C, the brine was flashed at 125 exp 0 C, and then the kinetics of solids and silica precipitation from effluent brine held at 90 exp 0 C were measured. Compounds tested include a variety of cellulose derivatives, ethylene oxide polymers, several polyethoxylated surfactants, and a phosphonate. The ethylene oxide moiety was confirmed as the source of activity in substances that inhibit the precipitation of silica at 90 exp 0 C, and the polyethylene glycols in the molecular weight range of approximately 10,000 to 100,000 are the most effective. A brief, in-plant scaling test with the most promising precipitation inhibitor showed that, although it significantly retarded scaling at 90 exp 0 C, there was no improvement at 125 exp 0 C or higher, and at 125 exp 0 C there may have been a slight increase in scaling rate. (ERA citation 04:036218)