Pressurized fluidized-bed gasification experiments with wood, peat and coal at VTT in 1991-1992: Part 1. Test facilities and gasification experiments with sawdust

Esa Kurkela, Pekka Ståhlberg, Jaana Laatikainen

Research output: Book/ReportReport

Abstract

Fluidized-bed air gasification of Finnish pine saw dust was studied in the PDU-scale test facilities of VTT to support the development of simplified integrated gasification combined-cycle processes by providing new information on the formation and behaviour of different gas impurities in wood gasification. The gasifier was operated at 4 - 5 bar pressure and at 880 - 1020 oC. Product gas was cleaned by ceramic candle filters operated at 490 - 715 oC. Concentrations of tars, fixed nitrogen species and vapour-phase alkali metals were determined in different operating conditions. Carbon conversion exceeded 95 % in all test periods although the gasifier was operated without recycling the cyclone or filter fines back to the reactor. However, at the gasification temperature of 880 - 900 oC more than 5 % of the wood carbon was converted to tars. The tar concentrations seemed to be clearly dependent on temperature at most of the set points. The total concentration of tars (compounds heavier than benzene) was reduced from 6 000 to 3 000 mg/m3n by increasing the gasification temperature from 880 oC to 1 000 oC. The expected catalytic effects of calcium on tar decomposition could not be achieved in these experiments by feeding coarse dolomite into the bed. The use of sand or aluminium oxide as an inert bed material did neither lead to any decrease in tar concentrations. However, the tar concentrations were dramaticly reduced in the cogasification experiments, when a mixture of approximately 50%/50% wood and coal was used as the feedstock. Moreover, the concentrations of the most problematic high-molecular weight polyaromatics were <50 mg/m3n in the cogasification experiments, while >1 000 mg/m3 concentrations were typical of sawdust gasification alone. Wood nitrogen was mainly converted into ammonia, while the concentrations of HCN and organic nitrogen containing compounds were very low. The vapour-phase concentrations of alkali metals were determined both for the hot raw gas before gas filtration and for the cooled and filtered product gas. The total concentration of vapour-phase alkalis was reduced close to the target level of 0.1 ppm-wt by carrying out the filtration at <500 oC. The operation of the ceramic filter unit with saw dust derived product gas was, however, more problematic than the filtration of peat or coal derived gas. In the early experiments, where the filter unit was operated at 700 oC, the pressure drop was increased very rapidly resulting in almost complete blinding of the filters in less than 5 hours. Later tests were carried out at <600 oC, with face velocities of 1.9 - 2.6 cm/s and either dolomite or coal was added to the gasifier. In these conditions the pressure drop of the filter remained more stable and longer test periods could be operated without filter blinding.
Original languageEnglish
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages66
ISBN (Print)951-38-4399-8
Publication statusPublished - 1993
MoE publication typeNot Eligible

Publication series

SeriesVTT Publications
Number161
ISSN1235-0621

Fingerprint

tar
peat
coal
filter
gas
experiment
alkali metal
pressure drop
ceramics
dolomite
organic nitrogen compound
dust
temperature
nitrogen
carbon
test
gasification
sawdust
aluminum oxide
cyclone

Keywords

  • wood
  • peat
  • coal
  • fluidized beds
  • gasification
  • saw dust
  • sampling
  • analysis
  • particulates
  • gases
  • tar
  • nitrogen compounds
  • sulfur compounds alkali metals
  • filtration

Cite this

Kurkela, E., Ståhlberg, P., & Laatikainen, J. (1993). Pressurized fluidized-bed gasification experiments with wood, peat and coal at VTT in 1991-1992: Part 1. Test facilities and gasification experiments with sawdust. Espoo: VTT Technical Research Centre of Finland. VTT Publications, No. 161
Kurkela, Esa ; Ståhlberg, Pekka ; Laatikainen, Jaana. / Pressurized fluidized-bed gasification experiments with wood, peat and coal at VTT in 1991-1992 : Part 1. Test facilities and gasification experiments with sawdust. Espoo : VTT Technical Research Centre of Finland, 1993. 66 p. (VTT Publications; No. 161).
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abstract = "Fluidized-bed air gasification of Finnish pine saw dust was studied in the PDU-scale test facilities of VTT to support the development of simplified integrated gasification combined-cycle processes by providing new information on the formation and behaviour of different gas impurities in wood gasification. The gasifier was operated at 4 - 5 bar pressure and at 880 - 1020 oC. Product gas was cleaned by ceramic candle filters operated at 490 - 715 oC. Concentrations of tars, fixed nitrogen species and vapour-phase alkali metals were determined in different operating conditions. Carbon conversion exceeded 95 {\%} in all test periods although the gasifier was operated without recycling the cyclone or filter fines back to the reactor. However, at the gasification temperature of 880 - 900 oC more than 5 {\%} of the wood carbon was converted to tars. The tar concentrations seemed to be clearly dependent on temperature at most of the set points. The total concentration of tars (compounds heavier than benzene) was reduced from 6 000 to 3 000 mg/m3n by increasing the gasification temperature from 880 oC to 1 000 oC. The expected catalytic effects of calcium on tar decomposition could not be achieved in these experiments by feeding coarse dolomite into the bed. The use of sand or aluminium oxide as an inert bed material did neither lead to any decrease in tar concentrations. However, the tar concentrations were dramaticly reduced in the cogasification experiments, when a mixture of approximately 50{\%}/50{\%} wood and coal was used as the feedstock. Moreover, the concentrations of the most problematic high-molecular weight polyaromatics were <50 mg/m3n in the cogasification experiments, while >1 000 mg/m3 concentrations were typical of sawdust gasification alone. Wood nitrogen was mainly converted into ammonia, while the concentrations of HCN and organic nitrogen containing compounds were very low. The vapour-phase concentrations of alkali metals were determined both for the hot raw gas before gas filtration and for the cooled and filtered product gas. The total concentration of vapour-phase alkalis was reduced close to the target level of 0.1 ppm-wt by carrying out the filtration at <500 oC. The operation of the ceramic filter unit with saw dust derived product gas was, however, more problematic than the filtration of peat or coal derived gas. In the early experiments, where the filter unit was operated at 700 oC, the pressure drop was increased very rapidly resulting in almost complete blinding of the filters in less than 5 hours. Later tests were carried out at <600 oC, with face velocities of 1.9 - 2.6 cm/s and either dolomite or coal was added to the gasifier. In these conditions the pressure drop of the filter remained more stable and longer test periods could be operated without filter blinding.",
keywords = "wood, peat, coal, fluidized beds, gasification, saw dust, sampling, analysis, particulates, gases, tar, nitrogen compounds, sulfur compounds alkali metals, filtration",
author = "Esa Kurkela and Pekka St{\aa}hlberg and Jaana Laatikainen",
note = "Project code: POV3008",
year = "1993",
language = "English",
isbn = "951-38-4399-8",
series = "VTT Publications",
publisher = "VTT Technical Research Centre of Finland",
number = "161",
address = "Finland",

}

Kurkela, E, Ståhlberg, P & Laatikainen, J 1993, Pressurized fluidized-bed gasification experiments with wood, peat and coal at VTT in 1991-1992: Part 1. Test facilities and gasification experiments with sawdust. VTT Publications, no. 161, VTT Technical Research Centre of Finland, Espoo.

Pressurized fluidized-bed gasification experiments with wood, peat and coal at VTT in 1991-1992 : Part 1. Test facilities and gasification experiments with sawdust. / Kurkela, Esa; Ståhlberg, Pekka; Laatikainen, Jaana.

Espoo : VTT Technical Research Centre of Finland, 1993. 66 p. (VTT Publications; No. 161).

Research output: Book/ReportReport

TY - BOOK

T1 - Pressurized fluidized-bed gasification experiments with wood, peat and coal at VTT in 1991-1992

T2 - Part 1. Test facilities and gasification experiments with sawdust

AU - Kurkela, Esa

AU - Ståhlberg, Pekka

AU - Laatikainen, Jaana

N1 - Project code: POV3008

PY - 1993

Y1 - 1993

N2 - Fluidized-bed air gasification of Finnish pine saw dust was studied in the PDU-scale test facilities of VTT to support the development of simplified integrated gasification combined-cycle processes by providing new information on the formation and behaviour of different gas impurities in wood gasification. The gasifier was operated at 4 - 5 bar pressure and at 880 - 1020 oC. Product gas was cleaned by ceramic candle filters operated at 490 - 715 oC. Concentrations of tars, fixed nitrogen species and vapour-phase alkali metals were determined in different operating conditions. Carbon conversion exceeded 95 % in all test periods although the gasifier was operated without recycling the cyclone or filter fines back to the reactor. However, at the gasification temperature of 880 - 900 oC more than 5 % of the wood carbon was converted to tars. The tar concentrations seemed to be clearly dependent on temperature at most of the set points. The total concentration of tars (compounds heavier than benzene) was reduced from 6 000 to 3 000 mg/m3n by increasing the gasification temperature from 880 oC to 1 000 oC. The expected catalytic effects of calcium on tar decomposition could not be achieved in these experiments by feeding coarse dolomite into the bed. The use of sand or aluminium oxide as an inert bed material did neither lead to any decrease in tar concentrations. However, the tar concentrations were dramaticly reduced in the cogasification experiments, when a mixture of approximately 50%/50% wood and coal was used as the feedstock. Moreover, the concentrations of the most problematic high-molecular weight polyaromatics were <50 mg/m3n in the cogasification experiments, while >1 000 mg/m3 concentrations were typical of sawdust gasification alone. Wood nitrogen was mainly converted into ammonia, while the concentrations of HCN and organic nitrogen containing compounds were very low. The vapour-phase concentrations of alkali metals were determined both for the hot raw gas before gas filtration and for the cooled and filtered product gas. The total concentration of vapour-phase alkalis was reduced close to the target level of 0.1 ppm-wt by carrying out the filtration at <500 oC. The operation of the ceramic filter unit with saw dust derived product gas was, however, more problematic than the filtration of peat or coal derived gas. In the early experiments, where the filter unit was operated at 700 oC, the pressure drop was increased very rapidly resulting in almost complete blinding of the filters in less than 5 hours. Later tests were carried out at <600 oC, with face velocities of 1.9 - 2.6 cm/s and either dolomite or coal was added to the gasifier. In these conditions the pressure drop of the filter remained more stable and longer test periods could be operated without filter blinding.

AB - Fluidized-bed air gasification of Finnish pine saw dust was studied in the PDU-scale test facilities of VTT to support the development of simplified integrated gasification combined-cycle processes by providing new information on the formation and behaviour of different gas impurities in wood gasification. The gasifier was operated at 4 - 5 bar pressure and at 880 - 1020 oC. Product gas was cleaned by ceramic candle filters operated at 490 - 715 oC. Concentrations of tars, fixed nitrogen species and vapour-phase alkali metals were determined in different operating conditions. Carbon conversion exceeded 95 % in all test periods although the gasifier was operated without recycling the cyclone or filter fines back to the reactor. However, at the gasification temperature of 880 - 900 oC more than 5 % of the wood carbon was converted to tars. The tar concentrations seemed to be clearly dependent on temperature at most of the set points. The total concentration of tars (compounds heavier than benzene) was reduced from 6 000 to 3 000 mg/m3n by increasing the gasification temperature from 880 oC to 1 000 oC. The expected catalytic effects of calcium on tar decomposition could not be achieved in these experiments by feeding coarse dolomite into the bed. The use of sand or aluminium oxide as an inert bed material did neither lead to any decrease in tar concentrations. However, the tar concentrations were dramaticly reduced in the cogasification experiments, when a mixture of approximately 50%/50% wood and coal was used as the feedstock. Moreover, the concentrations of the most problematic high-molecular weight polyaromatics were <50 mg/m3n in the cogasification experiments, while >1 000 mg/m3 concentrations were typical of sawdust gasification alone. Wood nitrogen was mainly converted into ammonia, while the concentrations of HCN and organic nitrogen containing compounds were very low. The vapour-phase concentrations of alkali metals were determined both for the hot raw gas before gas filtration and for the cooled and filtered product gas. The total concentration of vapour-phase alkalis was reduced close to the target level of 0.1 ppm-wt by carrying out the filtration at <500 oC. The operation of the ceramic filter unit with saw dust derived product gas was, however, more problematic than the filtration of peat or coal derived gas. In the early experiments, where the filter unit was operated at 700 oC, the pressure drop was increased very rapidly resulting in almost complete blinding of the filters in less than 5 hours. Later tests were carried out at <600 oC, with face velocities of 1.9 - 2.6 cm/s and either dolomite or coal was added to the gasifier. In these conditions the pressure drop of the filter remained more stable and longer test periods could be operated without filter blinding.

KW - wood

KW - peat

KW - coal

KW - fluidized beds

KW - gasification

KW - saw dust

KW - sampling

KW - analysis

KW - particulates

KW - gases

KW - tar

KW - nitrogen compounds

KW - sulfur compounds alkali metals

KW - filtration

M3 - Report

SN - 951-38-4399-8

T3 - VTT Publications

BT - Pressurized fluidized-bed gasification experiments with wood, peat and coal at VTT in 1991-1992

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Kurkela E, Ståhlberg P, Laatikainen J. Pressurized fluidized-bed gasification experiments with wood, peat and coal at VTT in 1991-1992: Part 1. Test facilities and gasification experiments with sawdust. Espoo: VTT Technical Research Centre of Finland, 1993. 66 p. (VTT Publications; No. 161).