| 1. |
- Hustad, J.E., et al.
(författare)
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Reactivity measurements of coke particles in five different flow reactors
- 1990
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Ingår i: Rivista dei Combustibili. - 0370-5463. ; 44:10, s. 257-267
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Experiments on reactivity of 128 μm coke particles in the gas temperature range from 1150 K to 1370 K have been performed in five different flow reactors in the Nordic countries and all the results were calculated by the shrinking particle model. The activation energy is found to be 25 kcal/mol indicating combustion control by the combined effects of chemical kinetic and pore diffusion (zone II combustion). The overall apparent reaction order was found to be 1.0
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| 2. |
- Johnsson, Jan-Erik, et al.
(författare)
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Modelling of NOx Formation in a Circulating Fluidized Bed Boiler
- 1990
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Ingår i: Proceedings 3rd International Conference on Circulating Fluidized Beds held October 15-18, 1990 in Nagoya, Japan.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A detailed kinetic model for the oxidation of NH3 and reduction of NO in FBC is used to model the NO concentration profile in an 8 MW CFB. Three different fuels were burned in the full scale tests: Bituminous coal, brown coal and petroleum coke. Kinetics were measured in a laboratory reactor using samples of char and bed material from the boiler. The simulation results show that char is an important catalyst for the oxidation of NH3 and reduction of NO when burning bituminous coal and petroleum coke. The char content in the brown coal bed is low and very active bed material with a high ash content is the important catalyst in this case. Homogeneous gas phase reactions were found to have only a minor influence. The levels of NO concentration calculated are in agreement with the experimental results. It is concluded that modelling the fuel-N conversion using kinetics measured for the specific chars and bed materials is a considerable step towards a better understanding of the formation and reduction of NO in FBC.
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| 3. |
- Leckner, Bo G, 1936, et al.
(författare)
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Emissions from the 40 MWth circulating fluidized bed boiler in Nyköping
- 1990
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Ingår i: Wirbelschichtsysteme 1990. ; :V10, s. 1-20
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Measurements of the emissions of NO, SO2 and CO as function of bed temperature and addition of limestone (the molar ration of Ca/S) were carried out on the 40 MWth circulating fluidized bed boiler in Nyköping. Also the possibility of reducing NO by ammonia injection were studied.
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| 4. |
- Leckner, Bo G, 1936
(författare)
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Heat transfer in circulating fluidized bed boilers
- 1990
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Ingår i: Proc. of the 3rd International conference on circulating fluidized beds. - 9780080405087 ; 3, s. PL5-1 to 9
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Conditions of significance for heat transfer in circulating fluidized bed boilers, such as the shap of the heat receiving surfaces, particle concentrations, and some characteristics of the thermal boundary layers are described. Simplified boundary layer equations are formulated and are related to published work. It is stated that radiationand heat transport by particles across the boundary layer are the principal mechanisms of heat transfer in circulating fluidized bed boilers. On the basis of this general survey of the heat transfer situation, published work during the past few years is briefly reviewed.
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| 5. |
- Leckner, Bo G, 1936, et al.
(författare)
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Nitrogen Oxides Emissions from Fluidized Bed Combustion of Different Fuels
- 1990
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Ingår i: Proceedings of the 2nd Topic Oriented Technical Meeting held in May 1990 in Rueil Malmaison, France.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The emission of NO from FB boilers depends largely on design and operation parameters. However, the content of fuel volatiles do play a role which can be qualitatively described. Until more kinetic data for all the different materials in the bed and catalytic reactions are available a thorough kinetic investigation in the laboratory is necessary before quantative modelling of the fuel nitrogen in a given fluidized bed combustor is possible. A step in this direction has been taken.
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| 6. |
- Åmand, Lars-Erik, 1957, et al.
(författare)
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Formation of N2O in Circulating Fluidized Bed Boilers
- 1990
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Ingår i: Proceedings 2:a Nordiska Konferensen om Svaveldioxid och Kväveoxidbegränsning vid Förbränning av Fasta Bränslen, Danmarks Tekniska Högskola, Lyngby, november 1990.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The N2O formation in circulating fluidized bed boilers is assumed to be influenced by two formation routes, either by char or by hydrogen cyanide originating from the fuel volatiles. A test program has been carried out with the purpose to better understand the formation routes. The test program consists of step response tests in a 12 MW circulating fluidized bed boiler. Concentration profiles of O2, CO2, CO, NO, HCN, NH3 and C1 to C3 hydrocarbons in the combustion chamber of the boiler were also measured in order to support the conclusions from the step response tests. The importance of the two routes is discussed but no conclusions can be made about their magnitude.
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| 7. |
- Åmand, Lars-Erik, 1957, et al.
(författare)
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N2O from Circulating Fluidized Bed Boilers - Present Status
- 1990
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Ingår i: Proceedings of the European Workshop on N2O Emissions, held in Lisbon, Portugal, 6-9 June 1990. ; :Paper No 27, s. 171-179
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Several conclusions can be made about the N2O emissions from CFB boilers, for instance: - Much more of the fuel nitrogen leaves with the flue gases in the form of N20 than NO.- The N2O emission decreases with increasing bed temperature, unlike the NO emission.- The N2O emission decreases with decreasing excess air, similar to the NO emission.- High volatile fuels result in lower N20 emission than low volatile fuels.- The N20 concentration increases in the vertical direction of the combustion chamber.
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| 8. |
- Åmand, Lars-Erik, 1957, et al.
(författare)
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Oxidation of Volatile Nitrogen Compounds During Combustion in Circulating Fluidized Bed Boilers
- 1990
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Ingår i: Proceedings 2:a Nordiska Konferensen om Svaveldioxid och Kväveoxidbegränsning vid Förbränning av Fasta Bränslen, Danmarks Tekniska Högskola, Lyngby, november 1990.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In circulating fluidized bed boilers, the volatile nitrogen species of the fuel are mostly oxidized to NO. This is shown in a test programme where the effect of batch supply of fuel on the NO emission has been carried out in two different commercial-type fluidized bed boilers. Measurements of gas concentration profiles of CO, NO HCN, NHa and C1 to Ca hydrocarbons in the boilers support the conclusions from the batch supply tests.
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| 9. |
- Åmand, Lars-Erik, 1957, et al.
(författare)
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The Role of Fuel Volatiles for the Emission of Nitrogen Oxides from Fluidized Bed Boilers - A Comparison Between Designs
- 1990
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Ingår i: Proccedings of the Twenty-Third Symposium (International) on Combustion/The Combustion Institute. ; , s. 927-933
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Konferensbidrag (refereegranskat)abstract
- The nitrogen oxides formed during fluidized bed combustion of solid fuels originate from fuel nitrogen in both char and volatiles. In the course of combustion these fuel constituents not only contribute to the production but also take part in the reduction of the emission. In order to study the role of the nitrogen-containing volatiles for the production and reduction of nitrogen oxides in fluidized bed boilers a series of tests has been carried out with fuels having different contents of volatiles in a range from anthracite to wood in two types of boiler, a circulating and a stationary fluidized bed boiler. It was found that the different designs of boilers result in different behaviours of the nitrogen-containing volatiles. In stationary fluidized bed boilers the volatiles tend to reduce the emissions of NO comparable to what takes place in a pulverized coal flame, whereas in circulating fluidized bed boilers the volatiles do not have the same beneficial effect. In circulating fluidized bed boilers the emission of NO tends to increase with an increasing content of volatiles in the fuel, whereas the emission decreases from the stationarry fluidized bed type of boiler burning fuels with a larger amount of volatiles.
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