Preforbrænding

Preforbrænding is a term used in Danish energy technology to describe a stage of combustion carried out before the main combustion event. The concept typically involves burning or preheating a portion of the fuel in a separate stage, often in a dedicated pre-burner, to create hot, partially oxidized gas that enters the main combustion zone. The aim is to improve overall efficiency, stabilize the flame, and reduce emissions such as nitrogen oxides (NOx) and carbon monoxide (CO).

Applications are found in industrial boilers, waste-to-energy plants, and gas-turbine combined-cycle systems, where two-stage or staged combustion is advantageous. In many configurations, the pre-burn stage preheats and partially oxidizes fuel and/or air, producing an intermediate gas that supports more efficient main combustion.

Operation and design: A pre-burner or preheater heats and partially oxidizes the fuel under controlled conditions. The hot, reactive output gas then enters the main chamber where complete combustion occurs. This staged approach can allow lower peak flame temperatures in the main zone, contributing to NOx suppression, while preserving high overall efficiency and flexibility with various fuels.

Benefits and challenges: Benefits include improved thermal efficiency, better fuel flexibility, and reduced emissions, together with enhanced flame stability. Challenges include added system complexity, tighter control requirements, and the need to ensure complete combustion in the overall process to avoid unburned fuel.

Relationships: Preforbrænding is related to staged combustion, premixed or diffusion concepts, and NOx-reduction strategies. The term is used in Danish technical literature and may be encountered in discussions of industrial combustion technologies.