Energy from Waste--clean, efficient, renewable: transitions in combustion efficiency and NOx control

Area of Science:

• Environmental Engineering
• Chemical Engineering
• Combustion Science

Background:

• Traditional Energy from Waste (EfW) plants use reciprocating grates and multi-stage flue gas cleaning.
• Modern EfW combustion involves a two-step process with primary and secondary air, leading to complex gas mixtures.
• Existing post-combustion steps struggle to optimally process diverse gas fractions, impacting efficiency and emissions.

Purpose of the Study:

• To describe modifications for minimizing exhaust gas volumes and noxious gas generation in EfW plants.
• To improve the overall thermal efficiency of EfW plants.
• To couple optimized combustion with innovative Selective Non-Catalytic Reduction (SNCR) for a cleaner system.

Main Methods:

• Implementing an intermediate step to homogenize gas mixtures above the grate.
• Modifying combustion air levels to reduce oxygen concentration (e.g., from 6.0 vol% to 2.6 vol% O(2,)(wet)).
• Utilizing the DyNOR™ (Dynamic NO(x) Reduction) SNCR technology for targeted reduction of nitrogenous oxides (NOx).

Main Results:

• Homogenization of the gas mixture significantly improved combustion quality and allowed for optimized process parameters.
• Reduced oxygen levels led to decreased formation of NOx.
• The DyNOR™ system dynamically adjusted reagent delivery, achieving very low NOx emissions.

Conclusions:

• Optimized combustion homogenization and reduced oxygen levels enhance EfW thermal efficiency and minimize harmful emissions.
• The DyNOR™ SNCR technology effectively reduces NOx in challenging solid fuel combustion environments.
• The integrated system offers a cleaner and more efficient approach to solid waste combustion.