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The influence of flow rate of the gas in the combustion chamber on oxy-combustion process of coal in atmospheric furnace with circulating fluidized bed

Jankowska S., Czakiert T., Krawczyk G., Jesionowski Ł., Borecki P., Nowak W.

Archivum Combustionis

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2015

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Vol. 35 nr 1

41--50

EN

Studies on combustible matter conversion during oxy-fuel combustion in circulating fluidized bed (CFB) environment are presented. A small pilot-scale CFB facility has been retrofitted to be ready for operation in an oxy-fuel regime, which means elevated partial pressure of oxygen in a gaseous atmosphere of O2/CO2. Maximum thermal load of the unit is estimated at 0.1MW. The unit is fired with polish bituminous coal. The paper is focused on carbon, combustible sulfur and fuel-N behavior in combustion chamber that runs under oxy-fuel CFB conditions. The analysis is based on in-furnace sampling of flue gas and on calculations of carbon, sulfur and nitrogen conversion ratios. The flow rate of the gas in the combustion chamber was the variable parameter of the process. The parameter change influenced distribution of particle concentration in fluidized bed material and the temperature distribution (along) the combustion chamber. Furthermore, it influenced the residence time of fuel particles in the combustion zone, and finally was reflected in the composition of flue gases. Measurement of flue gas composition was carried out on four levels of the combustion chamber, allowing to track the progress of the conversion of elemental carbon, sulfur combustible and fuel-nitrogen along the height of the combustion chamber. The described investigations are a part of the core work scheduled in the project “Advanced Technologies for Energy Generation: Oxy-combustion technology for PC and FBC boilers with CO2 capture” funded by the National Centre for Research & Development in Poland as well as supported by power industry.

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The Effect of Oxygen Staging on Nitrogen Conversion in Oxy-Fuel CFB Environment

Jankowska S., Czakiert T., Krawczyk G., Borecki P., Jesionowski Ł., Nowak W.

Chemical and Process Engineering

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2014

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Vol. 35, nr 4

489--496

EN

This paper presents a study on nitrogen conversion in oxy-fuel coal combustion in a pilot scale CFB 0.1 MWth facility. The paper is focused on fuel-N behaviour in the combustion chamber when the combustion process is accomplished under oxy-fuel CFB conditions. The analysis is based on infurnace sampling of flue gas and calculations of the conversion ratios of fuel-nitrogen (fuel-N) to NO, NO2, N2O, NH3 and HCN. For the tests, O2/CO2 mixtures with the oxygen content of 21 vol.% (primary gas) and with the oxygen content varied from 21 to 35 vol.% (secondary gas), were used as the fluidising gas. Measurements were carried out in 4 control points located along the combustion chamber: 0.43 m, 1.45 m, 2.50 m and 4.88 m. Results presented below indicate that an increased oxygen concentration in the higher part of the combustion chamber has strong influence on the behaviour of fuel based nitrogen compounds.

3

Analiza procesu współspalania węgla i peletów ze słomy w warunkach cyrkulacyjnej warstwy fluidalnej w skali pilotowej

Czakiert T., Borecki P., Krawczyk G., Jesionowski Ł., Jankowska S., Nowak W.

Archiwum Spalania

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2012

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Vol. 12, nr 3

127--135

PL

W pracy zostały przedstawione wyniki badań w zakresie współspalania węgla brunatnego z peletem ze słomy. Pomiary prowadzone były w skali małejpilotowej, na instalacji z cyrkulacyjną warstwą fluidalną. Szczegółowej analizie poddano wyniki emisji zanieczyszczeń gazowych (SO2, NO, NO2, N2O, CO oraz HCl i HF). Dużą uwagę skupiono również na przebiegu procesu odsiarczania spalin, prowadzonym z wykorzystaniem mączki kamienia wapiennego. Odniesiono się również do wykonanych analiz chemicznych popiołu. Ponadto, omówiono warunki procesowe, w tym szczególnie warunki termiczne panujące w komorze paleniskowej. Ostatecznie, uzyskane wyniki badań zostały skonfrontowane z wynikami pomiarów przeprowadzonych podczas spalania samego węgla, które w dyskusji nad zebranym materiałem potraktowane zostały jako punkt odniesienia. Stwierdzono między innymi istotne zmniejszenie emisji SO2, przy jednoczesnym spadku zapotrzebowania na sorbent. Najsilniejszy wpływ dodatku peletów na parametry emisyjne odnotowano dla N2O. Pozostałe wyniki nie wskazują jednoznacznie na ryzyko wystąpienia większych problemów natury eksploatacyjnych, podczas fluidalnego współspalania obu paliw w analizowanych proporcjach.

EN

This paper presents study on co-firing of brown coal with straw pellet. Measurements were conducted in a small pilot-scale, on circulating fluidized bed (CFB) facility. Detailed analysis was carried out on flue gas emissions (SO2, NO, NO2, N2O, CO, HCl and HF). Attention was also focused on desulphurization process, which runs with the use of limestone. Chemical analyses of ash were also referred to. Furthermore, the operating conditions were described, where the emphasis was put on thermal conditions inside combustion chamber. Finally, obtained results were compared with the results of coal combustion, which were treated as a reference point in this study. Significant decrease in SO2 emission was observed, along with the drop of sorbent demand. The strongest influence of pellets addition on emission was observed for N2O. Further results do not unequivocally indicate the risk with boiler operation, while combustion of both fuels in analyzed ratio under CFB conditions.