Abstract: An ammonia injection grid for a selective catalytic reduction (SCR) system that provides uniform distribution of ammonia to the SCR catalyst in NOx reduction systems for heat recovery steam generation systems, packaged boilers, simple cycle catalyst systems and fired heaters for superior operational efficiency. The ammonia injection grid includes an injection tube having at least one nozzle for injecting ammonia into a flow of flue gas. The ammonia injection grid also includes a corrugated turbulence enhancer associated with the injection tube to generate turbulent wake to enhance turbulent mixing.

Abstract: An improved burner assembly and process for operating same using a burner design that produces very low levels of undesirable nitrogen oxides is provided. The burner assembly premixes primary fuel and air in a venturi system and recirculates combustion gases back to the burner through a plurality of recirculation conduits where it is mixed with the premix of fuel and air and secondary air prior to combustion in a primary combustion zone. Rapid premixing of the primary fuel and air in the venturi system and the dispersion of the recirculated furnace gases is believed to result in lower peak flame temperatures and therefore minimizing the formation of the pollutants, such as nitrogen oxides.