Ash vaporization in circulating fluidized bed coal combustion

Terttaliisa Lind, Esko Kauppinen, Willy Maenhaut, Anup Shah, Frank Huggins

Research output: Contribution to journalArticleScientificpeer-review

24 Citations (Scopus)

Abstract

In this work, the vaporization of the ash forming constituents in circulating fluidized bed combustion (CFBC) in a full-scale 80 MWth unit was studied. Ash vaporization in CFBC was studied by measuring the fly ash aerosols in a full-scale boiler upstream of the electrostatic precipitator (ESP) at the flue gas temperature of 125°C. The fuel was a Venezuelan bituminous coal, and a limestone sorbent was used during the measurements. The fly ash number size distributions showed two distinct modes in the submicrometer size range, at particle diameters 0.02 and 0.3 μm. The concentration of the ultrafine 0.02-μm mode showed a large variation with time and it decreased as the measurements advanced. The concentration of the 0.02-μm mode was two orders of magnitude lower than in the submicrometer mode observed earlier in the bubbling FBC and up to three orders of magnitude lower than in the pulverized coal combustion. Scanning electron micrographs showed few ultrafine particles. The intermediate mode at 0.3 μm consisted of particles irregular in shape, and hence in this mode the particles had not been formed via a gas to particle route. We propose that the 0.3-μm mode had been formed from the partial melting of the very fine mineral particles in the coal. The mass size distribution in the size range 0.01–70 μm was unimodal with maximum at 20 μm. Less than 1% of the fly ash particles was found in the submicrometer size range. Ninety percent of Mg in coal was organically bound, and it was found to react with quartz and aluminosilicate minerals inside the coal particle. No Mg was found to be released to the gas phase and Mg mass fraction size distribution was size independent. A fraction of halogens CI, Br and I were found to be in the gas phase after the combustion.
Original languageEnglish
Pages (from-to)135-150
Number of pages16
JournalAerosol Science and Technology
Volume24
Issue number3
DOIs
Publication statusPublished - 1996
MoE publication typeA1 Journal article-refereed

Fingerprint

Ashes
Fluidized bed combustion
Coal
vaporization
Coal combustion
Coal Ash
Vaporization
Fly ash
Coal ash
ash
Gases
Minerals
Electrostatic precipitators
Bituminous coal
Aluminosilicates
fly ash
range size
Sorbents
Limestone
Flue gases

Keywords

  • fluidized beds

Cite this

Lind, T., Kauppinen, E., Maenhaut, W., Shah, A., & Huggins, F. (1996). Ash vaporization in circulating fluidized bed coal combustion. Aerosol Science and Technology, 24(3), 135-150. https://doi.org/10.1080/02786829608965359
Lind, Terttaliisa ; Kauppinen, Esko ; Maenhaut, Willy ; Shah, Anup ; Huggins, Frank. / Ash vaporization in circulating fluidized bed coal combustion. In: Aerosol Science and Technology. 1996 ; Vol. 24, No. 3. pp. 135-150.
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abstract = "In this work, the vaporization of the ash forming constituents in circulating fluidized bed combustion (CFBC) in a full-scale 80 MWth unit was studied. Ash vaporization in CFBC was studied by measuring the fly ash aerosols in a full-scale boiler upstream of the electrostatic precipitator (ESP) at the flue gas temperature of 125°C. The fuel was a Venezuelan bituminous coal, and a limestone sorbent was used during the measurements. The fly ash number size distributions showed two distinct modes in the submicrometer size range, at particle diameters 0.02 and 0.3 μm. The concentration of the ultrafine 0.02-μm mode showed a large variation with time and it decreased as the measurements advanced. The concentration of the 0.02-μm mode was two orders of magnitude lower than in the submicrometer mode observed earlier in the bubbling FBC and up to three orders of magnitude lower than in the pulverized coal combustion. Scanning electron micrographs showed few ultrafine particles. The intermediate mode at 0.3 μm consisted of particles irregular in shape, and hence in this mode the particles had not been formed via a gas to particle route. We propose that the 0.3-μm mode had been formed from the partial melting of the very fine mineral particles in the coal. The mass size distribution in the size range 0.01–70 μm was unimodal with maximum at 20 μm. Less than 1{\%} of the fly ash particles was found in the submicrometer size range. Ninety percent of Mg in coal was organically bound, and it was found to react with quartz and aluminosilicate minerals inside the coal particle. No Mg was found to be released to the gas phase and Mg mass fraction size distribution was size independent. A fraction of halogens CI, Br and I were found to be in the gas phase after the combustion.",
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Lind, T, Kauppinen, E, Maenhaut, W, Shah, A & Huggins, F 1996, 'Ash vaporization in circulating fluidized bed coal combustion', Aerosol Science and Technology, vol. 24, no. 3, pp. 135-150. https://doi.org/10.1080/02786829608965359

Ash vaporization in circulating fluidized bed coal combustion. / Lind, Terttaliisa; Kauppinen, Esko; Maenhaut, Willy; Shah, Anup; Huggins, Frank.

In: Aerosol Science and Technology, Vol. 24, No. 3, 1996, p. 135-150.

Research output: Contribution to journalArticleScientificpeer-review

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T1 - Ash vaporization in circulating fluidized bed coal combustion

AU - Lind, Terttaliisa

AU - Kauppinen, Esko

AU - Maenhaut, Willy

AU - Shah, Anup

AU - Huggins, Frank

N1 - Project code: K5SU00213

PY - 1996

Y1 - 1996

N2 - In this work, the vaporization of the ash forming constituents in circulating fluidized bed combustion (CFBC) in a full-scale 80 MWth unit was studied. Ash vaporization in CFBC was studied by measuring the fly ash aerosols in a full-scale boiler upstream of the electrostatic precipitator (ESP) at the flue gas temperature of 125°C. The fuel was a Venezuelan bituminous coal, and a limestone sorbent was used during the measurements. The fly ash number size distributions showed two distinct modes in the submicrometer size range, at particle diameters 0.02 and 0.3 μm. The concentration of the ultrafine 0.02-μm mode showed a large variation with time and it decreased as the measurements advanced. The concentration of the 0.02-μm mode was two orders of magnitude lower than in the submicrometer mode observed earlier in the bubbling FBC and up to three orders of magnitude lower than in the pulverized coal combustion. Scanning electron micrographs showed few ultrafine particles. The intermediate mode at 0.3 μm consisted of particles irregular in shape, and hence in this mode the particles had not been formed via a gas to particle route. We propose that the 0.3-μm mode had been formed from the partial melting of the very fine mineral particles in the coal. The mass size distribution in the size range 0.01–70 μm was unimodal with maximum at 20 μm. Less than 1% of the fly ash particles was found in the submicrometer size range. Ninety percent of Mg in coal was organically bound, and it was found to react with quartz and aluminosilicate minerals inside the coal particle. No Mg was found to be released to the gas phase and Mg mass fraction size distribution was size independent. A fraction of halogens CI, Br and I were found to be in the gas phase after the combustion.

AB - In this work, the vaporization of the ash forming constituents in circulating fluidized bed combustion (CFBC) in a full-scale 80 MWth unit was studied. Ash vaporization in CFBC was studied by measuring the fly ash aerosols in a full-scale boiler upstream of the electrostatic precipitator (ESP) at the flue gas temperature of 125°C. The fuel was a Venezuelan bituminous coal, and a limestone sorbent was used during the measurements. The fly ash number size distributions showed two distinct modes in the submicrometer size range, at particle diameters 0.02 and 0.3 μm. The concentration of the ultrafine 0.02-μm mode showed a large variation with time and it decreased as the measurements advanced. The concentration of the 0.02-μm mode was two orders of magnitude lower than in the submicrometer mode observed earlier in the bubbling FBC and up to three orders of magnitude lower than in the pulverized coal combustion. Scanning electron micrographs showed few ultrafine particles. The intermediate mode at 0.3 μm consisted of particles irregular in shape, and hence in this mode the particles had not been formed via a gas to particle route. We propose that the 0.3-μm mode had been formed from the partial melting of the very fine mineral particles in the coal. The mass size distribution in the size range 0.01–70 μm was unimodal with maximum at 20 μm. Less than 1% of the fly ash particles was found in the submicrometer size range. Ninety percent of Mg in coal was organically bound, and it was found to react with quartz and aluminosilicate minerals inside the coal particle. No Mg was found to be released to the gas phase and Mg mass fraction size distribution was size independent. A fraction of halogens CI, Br and I were found to be in the gas phase after the combustion.

KW - fluidized beds

U2 - 10.1080/02786829608965359

DO - 10.1080/02786829608965359

M3 - Article

VL - 24

SP - 135

EP - 150

JO - Aerosol Science and Technology

JF - Aerosol Science and Technology

SN - 0278-6826

IS - 3

ER -