Zofia Kalicka

The Effect of Combustion of Natural Gas With 21–29% O2/CO2/N2Mixtures on Emission of Carbon Monoxide

Abstract Natural gas combustion was carried out in air enriched with oxygen in the amount of 25 and 29% with addition of CO2 in place of part of nitrogen. The research was carried out at different flow rates of gas and oxygen excess ratios. The concentration of CO and NOx was analyzed. It has not been proved that the increased oxygen concentration influences significantly the CO concentration. However, the addition of CO2 caused a substantial variability of CO concentration in the exhaust gas, in contrast to the concentration of NOx which decreased monotonically. Model calculations, performed with use of FactSage, indicate an increase in the concentration of CO not only for the air enriched with oxygen, but after adding CO2 too, as well Streszczenie Przeprowadzono spalanie gazu ziemnego w powietrzu wzbogaconym w tlen w ilości 25 i 29% z dodatkiem CO2 w miejsce części azotu. Badania prowadzono przy różnych przepływach gazu i współczynnikach nadmiaru tlenu. Analizowano stężenie CO oraz NOx. Nie stwierdzono, by zwiększone stężenie tlenu wpłynęło w sposób znaczący na stężenie CO. Natomiast dodatek CO2 spowodował znaczną zmienność stężenia CO w spalinach, w przeciwieństwie do stężenia NOx, które spadało monotonicznie. Obliczenia modelowe, przeprowadzone przy pomocy FactSage, wskazują na wzrost stężenia CO nie tylko dla powietrza wzbogaconego w tlen, ale także po dodaniu CO2

Co-combustion of biomass and bituminous coal in a fluidized two-bed reactor

ABSTRACT The combustion of hazelnut shells and bituminous coal was studied in a novel reactor with two disks, supporting two fluidized beds located one above the other. The reactor allows for the study of the impact of the fuels’ vertical arrangement in the combustion zone on SO2 emission. The biomass and coal were combusted in separate beds or as a mixture. The gas species concentrations were measured. A major drop in the SO2 coal emission was observed when the coal was combusted underneath the biomass bed, and a minor one, when above.

Retention of S with Lignite Using Cedarnut Shell in the Co-combustion Process Performed in a Fluidized Bed Combustor

ABSTRACT The mix of high-sulfur lignite with cedarnut shell of high K2O content in ash was combusted in a fluidized bed reactor. When grain size distribution was identical, SO2 emission was the same as in the case of lignite alone. Under the same conditions, co-combustion of bituminous coal with cedarnut shells showed a significant drop of the SO2 emission. Reduction of SO2 emission was obtained by increasing the lignite grain size in order to extend the process of its combustion. When the lignite grain size was three times larger than the biomass grain size, the SO2 emission was 50% of the previous value, when six times larger it was 30%. This means that S retention takes place when SO2 released during lignite combustion is in direct contact with the biomass mineral residues. The most significant SO2 emission reduction occurred when lignite was combusted with biomass ash, not with raw biomass.

Comparison of hazelnut and peanut shells combustion in bubbling fluidized-bed combustor

ABSTRACT The combustion of peanut and hazelnut shells was studied in an atmospheric bubbling fluidized bed. The impact of the enrichment of air with oxygen and the flow rate of fluidizing gas on CO2 and CO concentrations was analyzed. It was stated that in air enriched with oxygen up to 25% the mole ratios of CO2 to CO were improved by 15–30%, depending on the flow rate used. For the peanut shell the combustion of volatiles with a hematite as an oxygen carrier was also studied. The effects were observed above ~ 450°C.

The Chemical-Looping Combustion of Propane with Iron (III) Oxide as an Oxygen Carrier

ABSTRACT The chemical-looping combustion of propane with the use of hematite and alumina-supported hematite carriers was studied in a fixed-bed reactor at 960°C, 910°C, and 870°C. In multiple cycles of the reduction/oxidation process, the concentrations of CO2 and CO in outlet gases were measured. The reactivity of the carriers was lowest in the first cycle. The conversion of propane was getting worse when the flow rate of propane was too high. The samples of the hematite carrier in the reduction stage were examined by X-ray diffraction (XRD) and thermogravimetric analysis (TGA) methods. Wustite and magnetite were detected as reduced forms of hematite. The theoretical analysis of the reduction paths of hematite by the propane decomposition products to Fe3O4, FeO, and Fe were conducted to investigate the pattern of the CO2 curve.