Seminar - Aspects of the development and operation of a pilot scale process to recover calcium silicate from geothermal water
ECS PhD Proposal
Speaker: Michael Schweig
Time: Friday 5th April 2019 at 02:00 PM - 03:00 PM
Location: Cotton Club, Cotton 350
The calcium silicate technology has been proposed and is being developed as a new and disruptive approach to the mitigation of problematic silica scaling in geothermal power plants. Dissolved silica in the geothermal brine following steam/water flashing is reacted to form a non-sticking nano-structured calcium silicate hydrate material, which flows through pipes and process equipment and is separated as a useful product. The technology also allows for an enhanced energy recovery from the hot geothermal brine, as the operating conditions of geothermal power plants are no longer constrained by having to keep their binary cycle heat exchanger and brine reinjection temperatures above the temperature dependent solubility limit of amorphous silica. This study investigates different aspects of the development and operation of a pilot scale process utilising the NCaSilH technology in a real world operational geothermal environment. First, a scalable model was developed to determine the occurring mass and energy flows of a geothermal power plant utilising the NCaSilH technology. For the solid-liquid separation process a volume-based calculation was developed. This defined a first pass look at the minimal required separation efficiency for the removal of the NCaSilH particles from the brine in order to prevent clogging of the downstream reinjection wells and the geothermal aquifer. The applicability of a cross-current lamella separator was investigated but deemed not to be an effective method of separating NCaSilH particles from geothermal brine. Further research focused on a counter-current approach where two CFD-simulations of industrial separator models were carried out and compared. For the pilot plant, an automation and process value monitoring concept was designed and all necessary components acquired. In order to segment the thesis into thematically separated sections four major research areas were made out and corresponding research questions formed. Additionally, a timeline with research goals is presented.