Ammonia has the advantage of high energy density and easy liquefaction, but on the other hand it has not been recognized as a fuel because of the disadvantage that it is more difficult to ignite and lower burning speed compared to conventional fuels. By expecting the possibility of realizing feature of ammonia as the carbon free fuel, we examined its combustion characteristics using a newly constructed more accurate detailed reaction mechanism. As the result, we were able to find out the appropriate operating conditions that can achieve the stable combustion accompanied by the hydrogen formation and low NOx formation within the range of fuel (ammonia) rich condition.
　Based on these findings, we would like to propose a unique concept of combined cycle power generation system coupled with the exhaust gas recirculation module under the fuel rich condition. By using the predicted efficiency and power output calculated by the thermodynamic model, a preliminary economic evaluation is shown too. It’s obvious that the proposed direct combusted ammonia-rich combined cycle can produce the power output equivalent to that of a hydrogen turbine power generation system under an economically advantageous or equivalent condition. Further development work on ammonia direct combustion power generation system should be carried out because it is well known that there is superiority to the hydrogen power generation system from the viewpoint of realizing low NOx combustion and ease of handling and so on.