Energy self-sufficiency of a supercritical water oxidation system with an improved cooled-wall reactor for power generation

Abstract

Transpiring and cooled-wall reactors are widely used to overcome the corrosion and salt plugging problems in the supercritical water oxidation (SCWO) process. However, energy consumption will significantly increase because the energy grade of the reactor effluent is decreased. In this study, an SCWO system with an inverse cool-wall reactor is proposed and simulated using Aspen Plus 8.2. With the improved cool-wall reactor and corresponding system, the energy consumption can be greatly reduced because the energy recovered from the reactor effluent is upgraded for power generation. High energy output and less exergy input and loss are present, resulting in high exergy efficiency and low energy consumption. The increase in the outlet temperature of the working fluid or feed concentration contributes to achieving energy self-efficiency. However, high reaction temperatures are present at high feed concentrations, and long reactor lengths or additional heat transfer areas are needed at high feed concentrations to cool the reactive fluids. The results of economic analysis show that the SCWO system with a cool-wall reactor is economically competitive.