KIER Initiates Developing a Pollution-free Ammonia Combustion Technology

Ammonia-air combustion and ammonia-air-coal mixed firing in development by KIER [Photo provided : Korea Institution of Energy Research]

A research team led by Dr. Lee Min-jung of Advanced Combustion Power Research of the Korea Energy Research Institute (Director Kim Jong-nam) has begun to develop combustion technology using 100% hydrous ammonia for the first time in Korea.

* Anhydrous ammonia: It means pure ammonia in a liquid or gaseous state consisting of nitrogen and hydrogen and is named anhydrous ammonia to distinguish it from ammonia water in an aqueous solution

The research team is planning to secure key design technology for the ammonia burner through the institutes basic project ‘Development of low-NOx gas turbine combustion technology for direct use of CO2-free ammonia. In particular the development of combustion technology using only 100% ammonia without mixing with existing fuels is the first attempt in Korea.

Under the ‘Road map for revitalizing the hydrogen economy and the 2050 Carbon Neutral Promotion Strategy hydrogen is expected to be expanded to various industrial sectors which will lead greatly increased demand. Meanwhile the use of ammonia a non-carbon fuel is drawing attention because it can lead the hydrogen economy as a hydrogen carrier and can be used directly through fuel ammonia combustion. In addition compared to hydrogen it has advantages in securing economic feasibility as it has a low risk of explosion has high stability and has related infrastructure as it is now actively used for fertilizer purposes around the world.

Global interest in ammonia combustion technology is also growing. In March this year MHI (Mitsubishi Heavy Industries Japan) began developing 40 MW ammonia gas turbines for the worlds first commercialization in 2025 and in June GE (General Electric U.S.) and IHI (Ishikawajima-harima Heavy Industries Japan) began establishing a road map to enter the Asian gas turbine market through the signing of MOU.

Ammonia has a 50% lower heat level and a 20% lower combustion speed compared to the existing LNG fuel making it difficult to secure combustion stability and has a problem that the nitrogen reactor included in the fuel can increase NOx emissions in a high-temperature combustion environment.

In order to solve this problem the research team wants to secure combustion stability and suppress NOx generation through designing high TDR fuel nozzle ammonia hydrogen decomposition technology using waste heat and staged combustion technology.

* TDR (Turn Down Ratio): The numerically represented ratio of the maximum value (flow or heat load) to the minimum of the range of operation of the burner

Ammonia has a narrow limit of inflammability and a low combustion speed compared to LNG fuel so it is necessary to design a high TDR fuel nozzle to ensure flame stability. To this end through CFD analysis and experiments the research team will secure a fuel nozzle design technology that can properly control flame blow outs or flame extinguishing in consideration of the flow characteristic around the fuel nozzle and the burning property of the flame fleet where the reaction begins.

In addition the researchers apply ammonia partial decomposition technology through fuel preheating as well as conventional combustion air preheating technology using discarded high temperature waste heat. Through preheating the fuel it can improve the thermal efficiency of the combustion system and convert some of the ammonia into reactive hydrogen to improve combustion speed and secure high TDR with mixed fuel of ammonia and hydrogen.

At the same time the important task to overcome in order to directly utilize ammonia as fuel is nitric oxide inhibition. While most ammonia combustion technologies in Japan and the U.K. adopt air staged combustion methods the researcher team supplies primary and secondary fuel for combustion by applying fuel staged combustion technology. It will secure technical differentiation by maximizing the SNCR process by effectively controlling the flow of ammonia in secondary combustion accordingly related patent applications are underway.

* Air staged combustion: Method of spraying air as an oxidizer into several stages. Technology of achieving the efficient reduction of NOx by suppressing combustion reaction through adjusting the mixture of fuel and oxidizer to lower the temperature of the flames hot spot or reduce the residence time in high oxygen concentration regions and high temperature regions.

** SNCR (Selective Non Catalytic Redution): Technology for reducing nitrogen oxides generated during the burning of waste or fuel in incinerators and boilers to harmless nitrogen and water

The development of non-carbon fuel ammonia combustion technology is expected to contribute greatly to the carbon reduction of energy-guzzling devices in the power generation industry said Jeong Hak-geun head of the Energy Efficiency Research Division.

This technology can be applied to the area of carbon-free fuel conversion in the energy sectors fuel combustion system which accounts for 87% of domestic greenhouse gas emissions. In particular it is expected to contribute to reducing carbon emissions in gas turbines thermal power generation steel heating processes petrochemical and oil refining processes and industrial boilers. To that end the Advanced Combustion Power Research Group is developing combustion technologies necessary for the upcoming conversion of non-carbon fuels.

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