**Nomenclature section**


C0 - the concentration of NOx in the flue gases normalized at 0% O2, when the reburning process is not carried on

CFB - circulating fluidized bed

concentration practically to 20 mg/m3. Under the same conditions, the concentration of CO in the third zone is reduced slightly. Only increase the amount of supplied air to this zone caused a significant decrease in the concentration of CO and the simultaneous increase in the con‐

The simulation of the third combustion zone, as a necessary element in the combustion process, reveals that the adjustment of the composition of the flue gases in this way is possible and does not require building of special installations. Most of the oxidation reactions take place at high

Results of presented researches showed that fluidized bed reactors can be applied as a part of the energy unit, where alternative solid fuels are combusted. The problem of high emission of nitrogen oxides, which occurs during thermal utilization of this kind of fuels, is under control through application of reburning process in the zone above the bed (rare zone). This technique of NOx reduction gives a significant reduction of nitrogen oxides concentration, what has been achieved by dosing such amount of reburning fuel at which value of the air excess coefficient in reburning zone has been near, but not lower than 0.9. In course of researches it was proven the rare zone which is created from the sand presented above the fluidized bed shall not prevent the NOx reduction process, but is an additional factor for ensuring transport of the heat from the space above the fluidized bed (reburning zone) in the direction of the fluidized bed. It helps maintain its proper bed temperature, even in conditions of irregular supply of

Despite the fact of satisfyingly low concentration of nitrogen oxides in flue gases from reburning process, CO and volatile organic compounds concentrations in them is at very high level (Figure 4, 5). Their concentration has to be reduced in the additional third combustion zone. The simulations of third combustion zone model revealed that air addition in the area above the reburning zone, which results in final air excess coefficient equal to aprox. 1.05, allows virtually for complete combustion of organic compounds and reduces the CO concen‐

C0 - the concentration of NOx in the flue gases normalized at 0% O2, when the reburning

tration to 70 ppm in the gases leaving the third combustion zone.

speed and the combustion process is almost completed in less than 0.5 seconds.

centration of O2.

270 Advances in Internal Combustion Engines and Fuel Technologies

**5. Conclusions**

solid fuel.

**Nomenclature section**

BE - wasted bleaching earth

process is not carried on

α - stoichiometric coefficient for CO2

β- stoichiometric coefficient for O2 in products

CLA - chemiluminescence technique

Creb - the concentration of NOx in the flue gases normalized at 0% O2, when the reburning process is carried on


nCO, nCO2, nVOCs, nO2 - number of moles of carbon monoxide, carbon dioxide, volatile organic compounds, oxygen

NDIR - non dispersive infrared spectroscopy


yCO, yCO2, yVOCs, yO2 - molar fractions of carbon monoxide, carbon dioxide, volatile organic compounds, oxygen

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http://dx.doi.org/10.5772/54158

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