Advanced Application of Excess Enthalpy Combustion Technology to Boiler Systems

Excess enthalpy combustion causes flame temperature to rise, with any BTU fuel. The method uses high temperature air for combustion which is obtained from a heat-recirculation method. A practical method of excess enthalpy combustion, called High cycle Regenerative combustion System(HRS), was applied to a small water tube boiler having a steam production rate of 700 kg/h. The results of field tests provided a thermal efficiency of 97% and NOx emission levels of approximately 100 ppm, corrected for 0% O2 using natural gas as the fuel. These results were with an air inlet temperature of 900 °C using enthalpy extraction from the flue gases and modified fuel-staged combustion technique. The application of excess enthalpy flame to a conventional boiler system demonstrated an overall increase in the time averaged value of heat flux in the radiative section of the boiler. Furthermore, the results also showed that it was possible to increase the amount of heat transfer by passing part of flue gases to the convective section of the chamber. Thus, the advantage of the whole system was not only an increase in boiler efficiency, but also the improved heat transfer efficiency. The HRS boiler systems provide significant compactness. Further advantages include significant reduction in the energy usage and boiler heating-up time. The HRS can be applied to almost all types of practical power systems and in all cases significant energy savings, system cost and pollutants emission reduction occurs