Comparing modelled and measured precipitation from depressurized supercritical water vapor

• In the calculations and the experiments discussed, silica solids are formed by depressurizing supercritical water vapor from 350 bar and 500 °C through an isenthalpic valve to superheated steam of pressures ranging from 60 bar to 140 bar, flowing through a straight pipe. The results show promising correlation between the predicted and measured results and several improvement options are explored. • The sensitivities analyzed, thermophoresis, initial particle size, interfacial free energy and stability, improve understanding of the key factors that influence accuracy. • The model shows promising potential when it comes to prediction of silica deposition from depressurized supercritical steam in a straight pipeline. • Thermophoresis and electrophoresis can likely influence the deposition of these particles significantly and can thus be used to manipulate deposition in certain areas of a system. • The large amount of small solid particles generated in the second after a sudden increase in supersaturation, as seen in these cases, can be used to rid the system of most of these minerals. This work presents a comparison between experimentally determined silica deposition from depressurized supercritical steam and numerical predictions combining classical nucleation theory, agglomeration and deposition onto the surface. The research is relevant to mineral rich pressurized supercritical or superheated water where particle generation and deposition will occur rapidly upon depressurization. The purpose is to mathematically relate measured mass deposits to particle formation behavior, and to tune and validate the model for silica deposition under these conditions. The knowledge is critical to geothermal energy production from supercritical reservoirs where the silica content is significant and where scaling in certain areas of the system needs to be avoided. Direct use of high enthalpy supercritical sources can allow for significantly better power utilization than is commonly experienced in conventional geothermal systems. In the calculations and the experiments discussed, silica solids are formed by depressurizing supercritical water vapor from 350 bar and 500 °C through an isenthalpic valve to superheated steam of pressures ranging from 60 bar to 140 bar, flowing through a straight pipe. The results show promising correlation between the predicted and measured results and several improvement options are explored. The sensitivities analyzed improve understanding of the key factors that influence accuracy.