Pure Ammonia-Fueled Roller Kiln for the Production of Ceramic Tiles: A First Demonstration

The implementation of zero-carbon fuels, such as hydrogen and ammonia derived from renewable sources, is a promising strategy for achieving the goals of carbon peaking and carbon neutrality in industrial sectors, where traditional hydrocarbon fuels still dominate. This paper discusses the recent successful application of 100% ammonia as both a fuel and a DeNOx (denitrification) agent in a ceramic roller kiln. First, the design of the ammonia burner is discussed. Stable, efficient, and low-NOx combustion of ammonia is achieved through the implementation of swirling combustion and air-stage combustion technologies. The combustion efficiency of ammonia can reach as high as 99.99%. It has been observed that the NOx emissions from the ammonia burner decrease from 400 ppm during single-staged combustion to 79 ppm during two-staged combustion at 18% O2. Furthermore, diagnostic methods, fuel supply systems, and emission control strategies are demonstrated. A three-level NOx suppression strategy is proposed, which includes air-staged combustion, selective noncatalytic reduction (SNCR), and selective catalytic reduction (SCR). Ultralow NOx emissions (single-digit ppm) can be achieved by using SCR while avoiding ammonia slip. Finally, the effects of replacing the fuel with ammonia in ceramic tile production are discussed. It is concluded that ammonia combustion does not significantly alter the color of the tiles or negatively impact the properties of the ceramic tile. This is the world’s first demonstration of a pure ammonia-fueled ceramic roller kiln aimed at achieving carbon-free production of ceramic tiles.