Developments in the Nanostructured Calcium Silicate Technology for Preventing Silica Deposition and Opening New Business Opportunities

摘要

The precipitation of silica from separated geothermal brine supersaturated in dissolved silica, and the formation of silica sinter deposits in pipes, heat exchangers and reinjection wells, remains a major problem in geothermal resource utilisation worldwide. The sinter compromises the heat energy recoverable in binary cycle electricity generation and increases equipment and field maintenance. Current approaches used to address the problem are not wholly satisfactory. In most cases the sinter formation persists. We are turning this major problem into an attractive operational and business opportunity. We are developing a proprietary technology to precipitate the dissolved silica species as a nanostructured calcium silicate hydrate (CaSil) material. The particle morphology and surface chemistry are distinctly different from silica and desirably the CaSil particles do not deposit on metal surfaces, thus preventing silica deposition and sinter formation. The technology has the potential to enable lower steam/water separation temperatures and lower brine exit temperatures in binary plant heat exchangers to be used, thereby enabling more heat energy to be extracted and hence electricity generated from a geothermal resource. There is no further propensity for silica to deposit in process equipment or in reinjection wells. This provides the opportunity for increased revenue and reduced maintenance costs for a geothermal resource owner and operator, and similarly increased revenue for an electricity generating company utilizing the resource. In addition, the inherent high surface area, pore volume, absorbent/adsorbent properties and surface reactivity for different CaSil products, facilitate the development of multiple potential applications and hence new CaSil-based business opportunities. These include "green fertilizers", environmental remediation of polluted surface, mine and industrial water streams, and performance enhanced printing paper and building products.