Wojciech Jerzak

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.

Equilibrium calculations of As, Pb, and Hg speciations during coal combustion in atmospheres 21O2/79N2 and 30O2/70CO2

ABSTRACT The research of this paper investigated the influence of a coal combustion atmosphere, pressure, and temperature on the equilibrium speciation of As, Pb, and Hg. The input data for calculations in the FactSage were the results of coal from the mine “Bogdanka”. A change in the combustion atmosphere from air to 30%O2/70%CO2 results in an increase in the mole fractions of As, Pb, and Hg species that occur in the gaseous phase, i.e. AsO, AsO2, PbO, PbCl2, HgCl2, and Hg. At temperatures below 900°C, almost all arsenic moves to solid species in the form of salts derived from arsenic acid (V).

Thermogravimetric and mass spectrometric analysis of powdered pine bark

ABSTRACT Using thermal analysis and mass spectrometry, this study examined samples of powdered pine bark by subjecting them to: (a) complete combustion, (b) partial combustion, and (c) pyrolysis. For each of the examined samples, which heated at the rate of 30°C min−1, temperature regions corresponded to moisture loss and the degassing process. Global and local maximum values of ionic currents representing H2O, CO2, CO, and additionally for hydrocarbons such as CH4, C2H4, and C2H5 for pyrolysis were identified. Based on the recorded values of ionic currents of hydrocarbons in the helium atmosphere, C2H5 dominance was determined at T ≤ 415°C, and CH4 dominance was determined at T > 415°C. Assuming first-order kinetics, thermogravimetric data were analyzed by the Arrhenius type model, and kinetic parameters were determined.

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.

The effect of combustion temperature on the composition of the ash and gas from cedar nut shell combustion

ABSTRACT The aim of this study is to examine the distribution of K, Mg, Si, Ca, and P to the ash and combustion gas during the combustion of ground cedar nut shells in an air atmosphere. The cedar shell combustion process took place in a furnace at a temperature of 830 ± 25°C. The composition of the ash obtained from cedar shell combustion was assayed using a Thermo iCAP 6500 Duo ICP plasma spectrometer. Potassium oxide had the largest share of ash (32.6 wt%). The presented results of equilibrium calculations in the temperature range of 800–1200°C represent the use of cedar shells as a fuel for the circulating fluidized-bed furnace. Based on computation made in the FactSage 6.3 program, it has been demonstrated that only potassium vaporizes in the form of the KOH(g), K2SO4(g), and KCl(g) compounds. Most silicon and magnesium are contained in the ash in the form of Mg2SiO4(s) in the temperature range of 800–1200°C. Calcium passes into the ash exclusively in the form of Ca3HP3O13 (hydroxyapatite), if T≤860°C, or calcium orthophosphate(V) – above 860°C. Phosphorus is present in the ash in the form of many compounds, such as Mg3(PO4)2(s), Ca5HP3O13(s), Ca3(PO4)2(s), and Na3PO4(s).

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.