Particle measurement and brine chemistry at the Salton Sea Deep Well

The Advanced Brine Chemistry Project, a part of the US Department of Energy's Geothermal Energy Program, is addressing operating problems associated with scaling and corrosion at geothermal power plants. Under this project, Pacific Northwest Laboratory conducted a series of tests at the Salton Sea Deep Well, which has one of the highest solids contents in the world. The purpose of the tests was to evaluate monitoring instrumentation under field conditions and relate particulate formation to the brine chemistry. The instrumentation, was evaluated under scaling geothermal conditions using two different principles: ultrasonic reflection and laser light scattering. The following conclusions were drawn from the instrumentation testing and brine chemistry and particulate analyses. (1) Using reflected ultrasonic impulses to detect suspended particles has been demonstrate for on-line application in a geothermal brine with strong scaling tendencies. Advantages over laser light scattering include improved high-temperature durability for the transducer and longer operation with less maintenance. (2) Counting and sizing particles using laser light scattering requires constant maintenance in geothermal applications. (3) Silica is the dominant scale species and appears in amounts orders of magnitude greater than other minor species such as barium sulfate. (4) The silica that formed at high temperatures and shortmore » residence times is very gelatinous and difficult to filter out of the brine. (5) Correlation of instrument readings with particle collection data was difficult because conditions on the filter (i.e., temperature, flowrate, and pressure) could not be maintained constant for long enough intervals to obtain comparable information. 5 refs., 27 figs., 2 tabs.« less