| Title | EVALUATION OF PERFORMANCE PROBLEMS OF CALCITE INHIBITORS |
|---|---|
| Authors | L. Muller, M. Bluemle, X. Li |
| Year | 2018 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Calcite inhibitor, scaling, inhibitor improvement |
| Abstract | This is a research project aimed at improving the efficiency, effectiveness and cost of calcite inhibition for the geothermal industry. It is aimed at providing updated data and support to the developing geothermal industry technologies of recent years including binary and Enhanced Geothermal System (EGS). It is common knowledge that many inhibitors used in Geothermal are borrowed from a range of other industries that include the paint industry, paper, boiler, cooling water and mining. Variable results and reports from industry users have flagged the need for some geothermal specific R&D into calcite inhibition. In the last eight years there have been advancements in calcite inhibition and modelling. Whilst presented to the geothermal industry as improvements there are common mismatches between modelled dose rates and rates that geothermal sites actually need to use and in instances, some catastrophic performance failures causing plant shut downs. It became apparent that little work had been done outside of the basic NACE test screening to understand what geothermal specific conditions can impact calcite inhibition performance in the geothermal world. Phase one of the research project screened 14 inhibitors using standard NACE testing without deaeration at 250 °C and 300 °C. The tests were then repeated with small amounts of cations added to the synthetic brines used in the NACE test that are commonly found in geothermal brines. These included: Fe, Mn, As, Sb, and Al. Results varied from product to product but demonstrated that some experienced a 90% drop in performance explaining the results in the field. These results are reported in this paper. Phase two of the project is to qualify what inhibitors work best in the presence of some of the cations tested in order to enable more accurate modelling and prediction of what would be best suited to any particular brine chemistry. Phase three of the project is to find or develop additives that mitigate the negative impacts of the interfering substances. |