Tag Archives: NOx

Ryuichi Murai*, Ryohei Omori, Takahiro Kitano, Hidetaka Higashino, Noriaki Nakatsuka, Fumiteru Akamatsu, Osaka University, Japan; Yuya Yoshizuru, UBE Industries, Japan; Jun Hayashi, Kyoto University, Japan

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

There are severe issues on increasing amount of carbon dioxide (CO2) emission in the world. Many studies are devoted to alternative fuels. One of promising candidates is the utilization of ammonia which is zero emission of CO2, a hydrogen energy carrier, and also can be burned directly as a fuel.

For direct combustion of ammonia in industrial furnaces, there were two issues which were weaker radiative heat flux and a huge amount of NOx emission compared with the combustion of methane. We already have reported [1] the solution of the former issue by using the oxygen enriched combustion.

The objective of this research is to study the reduction mechanism of NOx emissions in the ammonia / methane co-combustion in an industrial furnace both experimentally and numerically. Experimentally we measured the radiation spectra and the total radiative thermal flux under the condition of the ammonia fuel burned in a 10 kW furnace with a coaxial jet flame and additional two oxidizer inlets for the staging combustion. The spectrum measurement results show that the amount of NOx emission was in reverse proportion with the intensity of N2O spectrum in the downstream of the reaction zone in the furnace. This indicates that N2O, which is one of main intermediate species of NH3, reacts with NOx as a reduction reactant to nitrogen molecule. Continue reading →

Akihiro Hayakawa*, K.D. Kunkuma A. Somarathne, Masaaki Tsukamoto, Taku Kudo, Hideaki Kobayashi, Tohoku University, Japan

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

Ammonia is expected not only as a hydrogen energy carrier but also as a carbon free fuel. Recently, ammonia fueled gas turbine combustor was successfully demonstrated. However, large amount of NOx was produced when ammonia burns because ammonia includes nitrogen atom in the ammonia molecule. In addition, unburnt ammonia concentration in exhaust gas also needs to be reduced. In this study, we proposed a combustion concept in order to reduce NO and unburnt ammonia concentrations in the exhaust gas simultaneously in a gas turbine like model swirl combustor. In this concept, two stage (rich – lean) combustion was employed. Two stage (rich – lean) combustion has been already employed in hydrocarbon fueled gas turbine combustors in order to reduce thermal NOx. However, the two stage combustion for ammonia fuel is different from that of hydrocarbon because production path of NO is different each other, i.e., NOx is generated via fuel NOx path in the ammonia flame. Continue reading →

Osamu Kurata*, Norihiko Iki, Takahiro Inoue, Takayuki Matsunuma, National Institute of Advanced Industrial Science and Technology (AIST), Japan; Taku Tsujimura, Hirohide Furutani, Fukushima Renewable Energy Institute, AIST (FREA), Japan; Masato Kawano, Keisuke Arai, Toyota Energy Solutions, Japan; Ekenechukwu C. Okafor, Akihiro Hayakawa, Hideaki Kobayashi, Tohoku University, Japan

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

A massive influx of renewable energy is required in order to mitigate global warming. Although hydrogen is a renewable media, its storage and transportation in large quantity is difficult. Ammonia, however, is a hydrogen energy carrier, and its storage and transportation technology is already established. Although ammonia fuel combustion was studied in the 1960s in the USA, the development of an ammonia fuel gas turbine had been abandoned because combustion efficiency was unacceptably low [1]. Recent demand for hydrogen energy carrier revives the usage of ammonia fuel. The National Institute of Advanced Industrial Science and Technology (AIST) in Japan, in collaboration with Tohoku University successfully realized ammonia-kerosene gas turbine power generation in 2014, and ammonia fuel gas turbine power generation in 2015 by using 50-kWe class gas turbine [2, 3].

The drawback of the facility is that it requires a large-size selective catalytic reduction (SCR) to decrease the high concentrations of NOx. In order to promote the widespread of ammonia combustion gas turbine system, it is necessary to downsize SCR NOx reduction. In other words, it is important to reduce NOx emission from ammonia gas turbine combustor. AIST has begun developing low-NOx combustors by using a combustor test rig. Simultaneously, fundamental research was carried out at Tohoku Univ. It was found at Tohoku Univ. that rich-lean two-stage combustion method and a control of equivalence ratio of the primary combustion zone to around the value of 1.1 to 1.2 significantly decreases NO emissions in gas-turbine swirl combustor [4, 5]. Continue reading →