Demonstration of 0.1 MWth pilot-scale pressurized oxy-fuel combustion for unpurified natural gas without CO2 dilution

The pressurized oxy-fuel combustion system is renowned for its compatibility with carbon capture and storage technologies. This study aims to investigate the characteristics and potential of the pressurized oxy-fuel combustion system using unpurified natural gas and pure oxygen without CO2 dilution to decrease the cost of the purification process and the penalty of plant efficiency. The pilot-scale pressurized oxy-fuel combustion system was successfully demonstrated to study the characteristics of combustion, heat transfer, and NOx emission. For a given heat input, the mean temperature decreased, despite an increase in the adiabatic flame temperature due to pressurization. The heat recovery rate of the coolant in all the tested cases was approximately 84-86%. The radiative heat transfer was enhanced by the flue gas that was mainly composed of H2O and CO2 at high pressures. The NOx concentration decreased with the reduction in mean temperature, which suppressed the formation of thermal NO. The proportion of NO2 in NOx was approximately 25-28% at a pressure of 10 bar with respect to various N-2 fractions. With respect to the high pressure and heat input, the NOx concentration of the lower momentum burner was decreased via the reduction of hot-spots and peak temperature. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study investigated the characteristics and potential of the pressurized oxy-fuel combustion system using unpurified natural gas and pure oxygen, demonstrating successful pilot-scale testing of the system. The heat recovery rate was around 84-86% in all tested cases, and radiative heat transfer was enhanced by flue gas composed mainly of H2O and CO2 at high pressures. Furthermore, the reduction in mean temperature led to decreased NOx concentration, suppressing the formation of thermal NO.