Combining hydrogen production and oxyfuel systems for energy stability and direct usage of produced oxygen. Experimental study on oxygen enriched combustion in conventional boilers

Renewable energy integration is changing the energy mix in many countries. At the same time, grid stability and security of supply must be ensured. A promising solution may be the development of systems to connect the natural gas network and the electricity grid. This study proposes a bi-directional system in which the natural gas grid, the electricity grid, a hydrogen production facility, and a natural gas boiler are looped together. This system consists of the H2 injection into the gas grid by electrolysis and subsequent combustion of this mixture in an oxyfuel boiler. Both systems are connected through oxygen from electrolysis and water from combustion usage. This research experimentally studies oxygen-enriched combustion in a 33 kW conventional burner and simulates its operation in oxy-enrichment combustion. This article therefore investigates the energy contained in the exhaust gases, the heat transfer to the heating fluid, and the pollutant emissions resulting from oxy-enrichment combustion. Results show that oxygen enrichment from electrolysis improves combustion properties, especially the combustion temperature. However, from 28.5 % O2, the exhaust gas temperature decreased again. At the same time, the oxygen enrichment process allowed CO emissions to be almost zero at 26.1 % O2. In the second part of the study, the scenario in which the CO2 emissions were recirculated back to the boiler was analyzed numerically. In this case, it was observed that adding CO2 significantly reduced the flame temperature.