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This study focuses on the indirect co-firing CFD simulations of reductions in NOx emissions relative to the coal combustion. For the given biomass-derived syngas composition and 15% syngas heat input, two arrangements of nozzles dedicated to the syngas injection into the furnace of an older PC-fired boiler of type OP-230 with low-emission burners on the front wall were chosen to investigate the impact of their location on the reduction in NOx emissions. It was shown that the highest reduction achieved by means of the improvement of the air staging via the dual-fuel technique can reach up to 40% (Case 1: nozzles at the elevation of the bottom row of burners) and up to 32% (Case 2: nozzles above the upper level of the burners). The modelling results also showed that one can meet the requirements for co-firing of coal with waste derived syngas. The boiler can be retrofitted for the fulfilment of the prospective environmental protection regulations relating to levels of NOx emissions by combining the described technology with SNCR methods. It is also very important that the indirect co-firing enables reduction of carbon dioxide emissions proportionally to the syngas heat input.

Syngas co-firing in coal fired boilers can be one of the prospective technologies which may help to retrofit some of still functioning older boilers. This study focuses on the results of CFD simulations of wood biomass-derived syngas co-firing with coal in an older mid-sized tangential PC-fired boiler of type OP-230. The design and the implementation of the combustion process predispose the boiler to the connection with the biomass gasifier in which low calorific syngas from solid raw biomass gasification can be produced and next used as a supplemental fuel in the coal furnace. The simulations were performed to predict the influence of the improvement of the air staging via the dual-fuel technique based on the indirect co-firing technology on both the reductions in NOx emissions relative to the baseline (no syngas) and the residence time of syngas particles in a zone with the temperature higher than 1123K. This way one can determine whether the boiler can be recommended to indirect co-firing of syngas derived from agricultural residues biomass or SRF gasification containing such troublesome components as chlorine and alkali.

This study focuses on a CFD modelling of biomass-derived syngas co-firing with coal in an older mid-sized PC-fired boiler of type OP-230 with low-emission burners on the front wall. The simulations were performed to determine whether the boiler can be retrofitted for the fulfilment of the prospective environmental protection regulations relating to levels of NOX emissions. The improvement of the air staging via the dual-fuel technique was based on the indirect co-firing technology. The impact of two arrangements of dedicated syngas nozzles (below and above the existing coal burners), two syngas compositions and two heat replacements (5% and 15%) on the course of thermal processes in a furnace was tested. The reductions in NOX emissions were predicted relative to the baseline when only coal is combusted. The highest reduction of about 38% was achieved with the syngas nozzles below the existing coal burners and 15% heat replacement. This arrangement of nozzles offers the residence time sufficient to co-fire coal with waste derived syngas. A lower reduction in NOX emissions was obtained with the nozzles above the burners as the enlargement of local fuel rich zone near syngas injection becomes significant for 15% heat replacement. Results provide for the decreasing impact of methane content along with the increase of syngas heat input. The avoided CO2 emissions through the syngas indirect co-firing with coal in the boiler are linear function of heat replacements. [ABSTRACT FROM AUTHOR]

The paper presents a description of the mathematical formalism for blending to obtain ternary formed fuels from waste. The methodology assures obtaining fuels of required technological properties that result, for example, in a limited gram fraction of chlorine in dry mass of fuel, and an appropriate calorific value in the working state. The procedure results makes it possible to determine mass fractions of particular components of produced formed fuels, which in turn creates a possibility of performing stoichiometric calculations for both total and complete combustion. The modeling of both technological as well as calorific and emission properties of fuels from waste at their initial formation stage can have a significant importance for the implementation of new technologies of thermal waste processing, i.e. the production of synthetic fuels for power industry. [ABSTRACT FROM AUTHOR]