(121b) CFD Analysis of Supercritical Water Reactor for Flow Back and Produced Water Treatment

Shale deposits have the potential of unlocking a vast reserve of energy resources across the United States. However, the current water intensity and wastewater generated from shale wells needs to be addressed. OHIO is developing a supercritical water (SCW)-based process for the treatment and reuse of flowback and produced water generated by shale wells.   Of the components in the process, the Supercritical Water Reactor (SCWR) will be responsible in the treatment of the major salt constituents and remaining hydrocarbons. The purpose of this work was to utilize CFD analysis, using ANSYS Fluent (Fluent), to investigate the heat transfer and fluid flow in the SCWR, at different inlet temperatures (350° C and 390° C) and operating pressures (23 MPa and 26 MPa).

A user-defined SCW property database and model were developed in Fluent, which was later compared to existing experimental data from literature and implemented to evaluate SCWR operation.  Temperature and density contours along with flow patterns within the SCWR are presented. The estimated salt solubility in the SCWR were estimated based upon fluid density. It was observed that at higher operating pressures, SCW could be heated to a higher temperature compared to pressures around the supercritical point (P_critical = 22.064 MPa). However, the minimum SCW density increases operating pressure, resulting in an increased salt solubility. As a result, ideal operating conditions will be a balance between the inlet temperature of the wastewater and the operating pressure of the system.