(367e) New Technology of the Ammonia Co-Firing with Pulverized Coal to Reduce the NOx Emission

Ammonia is recognized as the new energy carrier and it is expected to be introduced into the society in a short time, since the infrastructures related to the ammonia, such as the mass production, transportation and storage are already introduced to produce the fertilizer for the agriculture.

There is one technical issue, to use the ammonia in the direct combustion as the fuel for the electric power generation. It is the increase of the NO concentration in the exhaust gas. Ammonia contains the large amount of the nitrogen, comparing with any other fuels that human being has ever treated. Nitrogen from the ammonia can be easily oxidized unless there are any technical considerations to inject it into the combustion chamber.

In this study, injection method of the ammonia into the pulverized coal fired boiler was investigated experimentally and numerically. And it succeeded to reduce the NO concentration to be in the same degree with the conventional boiler.

Since the coal fired boiler originally has the countermeasure to deal with the tinny amount of the ammonia contained in the coal, the concept of such low NO technology can be easily diverted into the ammonia co-firing.

In this study, ammonia is injected into the reduction zone where the oxidization of the ammonia is restrained and the thermal cracking is promoted. In some test cases, it was experimentally observed that NO concentration in the ammonia co-firing is lower than that in the coal firing. By the numerical study, the reason for it could be seen that some part of the injected ammonia contribute to the denitrification.

According to this study, it can be mentioned that the ammonia has high possibility to be a fuel for the electric power generation and has compatibility with other fuels.