Combustion of fuels, including renewable fuels and thermal treatment of waste (CFCs, pesticides), is associated with emissions of pollutants including halogens. The reversible process of sorption/desorption of HCl, in a fluidized (bubbling) bed reactor (BFB), during co-combustion of Cl-materials, was carried out. The thermal decomposition of methylene chloride (DCM, CH2Cl2) in an inert sand bed with the addition of the hydroxyapatite sorbent (HAp, Ca5(PO4)3(OH)) was investigated. The process parameters were as follows: temperature - 930 °C, the air excess - 1.3, stream rate of CH2Cl2 - 50 cm3/h. The concentration of HCl, CCl4, CHCl3, CH2Cl2, CH3Cl, COCl2 in the exhaust gases were monitored online with FTIR spectroscopy. The main chlorine product was hydrogen chloride. Samples of unprocessed HAp, taken from the bed during the process, and solid apatite residues were analyzed by X-ray diffraction (XRD). The content of chlorapatite (Ca5(PO4)3Cl) in the analyzed samples was respectively 11, 53 and 19 %. X-ray fluorescence (XRF) analysis showed the molar ratio of Ca:P:Cl was: 1.00:0.36:0.01, 1.00:0.36:0.09, 1.00:0.37:0.04 respectively. The HAp could be used as an sorbent of the HCl(g) during combustion of materials containing chlorine.
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W artykule zaprezentowano wstępne wyniki badań właściwości fizykochemicznych popiołów pochodzących ze spalania biomasy drzewnej z dodatkiem słomy lub łupin orzecha kokosowego w kotle fluidalnym. Przedstawiono skład chemiczny, gęstość nasypową, rozkład frakcyjny, topografię i heterogeniczność powierzchni popiołów, rozkład poszczególnych pierwiastków w odpadzie oraz wyniki analizy termograwimetrycznej.
EN
The preliminary results of the physicochemical properties of the fly ash from the combustion of woody biomass with the addition of straw or palm kern shell in a fluidized bed were estimated. The chemical composition, bulk density, fractional distribution, and heterogeneity of the surface topography as well as the distribution of the individual elements in the waste and thermo-gravimetric analyses were shown.
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Solidification of industrial sludge in concrete matrices has been examined. The concrete mixes in which galvanic sewage sludge was immobilised were prepared with the use of two binder types: Portland-fly ash cement CEM II/B-V, and a binder composed of Portland cement (60%) and fly ash obtained from fluidized bed combustion of fuels (40%). Leaching of heavy metals (Cr, Cd, Zn, Ni, Cu, Pb, V) was observed from solidification matrices which had been exposed to various aqueous media (distilled water, sea water, sulfate solution) over a long period of time. Features of concrete were also studied which could directly influence the release of heavy metals, i.e. their microstructures and microporosity. Moreover, the effect of sewage sludge addition was shown on physical and mechanical properties of concrete, i.e. compression strength, water absorbability and water penetration depth were analysed. The research programme covered the periods of 1 year and 2 years, during which the concrete samples were stored in various aqueous environments. The stability parameters of the matrix which contained fly-ash from fluidized bed combustion of fuels were found not to be much different from the parameters for the matrix which was based on the Portland-fly ash cement. Leachability of heavy metals was demonstrated to increase in the aggressive aqueous medium as compared to the level obtained when the samples were stored in distilled water.
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The subject of the research was the influence of N2O on propane combustion in a fluidized bed reactor with active and chemically inert beds. It was determined that CaO has a significant influence on shifting the area in which the reaction is most intensive deeper into the bed and on the combustion result. It was also observed that adding nitrous oxide causes a decrease in VOC and CO concentration in exhaust gas. It was established that N2O, when added, is the determining factor of NOx creation, which takes place in a similar manner as via the prompt mechanism.
Zaprezentowano wyniki szeregu prób spalania metanu, propanu, metanolu 1-propanolu, benzenu oraz m-ksylenu, w niekatalitycznym pęcherzowym złożu fluidalnym. Wykazano, że ze względu na niską zawartość CO, NOx oraz związków organicznych w spalinach reaktor fluidyzacyjny może być brany pod uwagę jako nowe i bardzo efektywne rozwiązanie techniczne z zakresu dopalania lotnych substancji organicznych. Przedstawiono definicję indeksu toksyczności jako bezwymiarowego parametru do oceny toksyczności spalin. Wykazano, że może on być stosowany do oceny toksyczności spalin pochodzących z różnych urządzeń lub powstajacuych w różnych warunkach technologicznych. Spełnia też wymogi stawiane zmiennym służącym do optymalizowania procesów spalania, szczególnie z punktu widzenia oddziaływania na środowisko.
EN
The paper presents the results from several series of tests on the combustion of methane, propane, methanol, 1-propanol, benzene and m-xylene in a non-catalytic bubbling fluidised bed. It is shown that the flue gas concentrations of CO, NOx and volatile organic compounds can be low and thus fluidised bed reactors could be employed for cleaning gas streams carrying a wide range of organic pollutants. A dimensionless toxicity index is defind for the flue gases and it is demonstrated that it can be used for comparing the effectiveness of different combustion technologies. The index can be used as one of the variables used in optimising the combustion process, from the point of view of its environmental impact.
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