Behavior of chlorine and enrichment of risky elements in bubbling fluidized bed combustion of biomass and waste assisted by additives

Beatrice Coda (Corresponding Author), Martti Aho, Roland Berger, Klus Hein

Research output: Contribution to journalArticleScientificpeer-review

65 Citations (Scopus)

Abstract

High contents of chlorine and alkalies restrict the use of biomass in energy production. Alkali chlorides vaporize during combustion. Chlorine tends to produce corrosive deposits and unacceptably high emissions of HCl and dioxins. Chlorine recovery and enrichment of Cl, Na, K, Ca, Al, and Si in coarse and fine fly ash were studied experimentally with two electrically stabilized bubbling fluidized bed (BFB) reactors capable of reproducing the particle residence times existing in full-scale BFB plants. Feedstocks were fir (mixture of heartwood and bark), paper sludge, and blends of fir with agricultural waste or plastic waste. Sulfur concentrations of feed components were low (<0.5 wt %), while chlorine and potassium concentrations ranged widely (0.02−3.2 wt % for Cl and 0.07−3.1 wt % for K). Aluminum-containing additives (kaolin, bauxite and fly ash from a pulverized coal plant) and limestone were added to the feedstocks at various dosages to evaluate their influence on Cl behavior and enrichment of the elements of interest. HCl was measured by FTIR and wet-absorption methods. Different ash samples (bed, cyclone and filter ash) were characterized for their Cl content and the major ash-forming constituents. Cl was completely volatilized from bed ash and recovered only in coarse (cyclone) and fine (filter) fly ash fractions. Al-containing additives increased HCl formation and decreased Cl concentration in the fly ash. In the case of Al−Si based additives, evidence was found of the formation of alkali aluminum silicates from alkali chlorides. The aluminum silicates were transferred mainly to the coarse fly ash fraction. Al-based additives also seemed to liberate Cl from alkali chlorides with reactions forming water-soluble alkali compounds. Limestone had the opposite effect to the Al-containing additives by binding Cl from gas phase to fly ash, but mainly to the coarse fly ash fraction. The results will be useful in optimizing the behavior of chlorine in bubbling bed combustion of Cl- and alkali-containing biomass.
Original languageEnglish
Pages (from-to)680-690
Number of pages11
JournalEnergy & Fuels
Volume15
Issue number3
DOIs
Publication statusPublished - 2001
MoE publication typeA1 Journal article-refereed

Fingerprint

Coal Ash
Fluidized bed combustion
Ashes
Chlorine
Alkalies
Fly ash
Biomass
Aluminum Silicates
Chlorides
Calcium Carbonate
Limestone
Aluminum
Fluidized beds
Feedstocks
Silicates
Kaolin
Caustics
Agricultural wastes
Dioxins
Aluminum Oxide

Keywords

  • fluidized beds
  • biomass
  • bioenergy
  • biofuels
  • wastes
  • residues
  • combustion
  • emissions
  • heavy metals
  • chlorine compounds
  • fluidized bed combustion
  • potassium
  • sodium
  • aluminum
  • agricultural wastes
  • plastics

Cite this

Coda, Beatrice ; Aho, Martti ; Berger, Roland ; Hein, Klus. / Behavior of chlorine and enrichment of risky elements in bubbling fluidized bed combustion of biomass and waste assisted by additives. In: Energy & Fuels. 2001 ; Vol. 15, No. 3. pp. 680-690.
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abstract = "High contents of chlorine and alkalies restrict the use of biomass in energy production. Alkali chlorides vaporize during combustion. Chlorine tends to produce corrosive deposits and unacceptably high emissions of HCl and dioxins. Chlorine recovery and enrichment of Cl, Na, K, Ca, Al, and Si in coarse and fine fly ash were studied experimentally with two electrically stabilized bubbling fluidized bed (BFB) reactors capable of reproducing the particle residence times existing in full-scale BFB plants. Feedstocks were fir (mixture of heartwood and bark), paper sludge, and blends of fir with agricultural waste or plastic waste. Sulfur concentrations of feed components were low (<0.5 wt {\%}), while chlorine and potassium concentrations ranged widely (0.02−3.2 wt {\%} for Cl and 0.07−3.1 wt {\%} for K). Aluminum-containing additives (kaolin, bauxite and fly ash from a pulverized coal plant) and limestone were added to the feedstocks at various dosages to evaluate their influence on Cl behavior and enrichment of the elements of interest. HCl was measured by FTIR and wet-absorption methods. Different ash samples (bed, cyclone and filter ash) were characterized for their Cl content and the major ash-forming constituents. Cl was completely volatilized from bed ash and recovered only in coarse (cyclone) and fine (filter) fly ash fractions. Al-containing additives increased HCl formation and decreased Cl concentration in the fly ash. In the case of Al−Si based additives, evidence was found of the formation of alkali aluminum silicates from alkali chlorides. The aluminum silicates were transferred mainly to the coarse fly ash fraction. Al-based additives also seemed to liberate Cl from alkali chlorides with reactions forming water-soluble alkali compounds. Limestone had the opposite effect to the Al-containing additives by binding Cl from gas phase to fly ash, but mainly to the coarse fly ash fraction. The results will be useful in optimizing the behavior of chlorine in bubbling bed combustion of Cl- and alkali-containing biomass.",
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author = "Beatrice Coda and Martti Aho and Roland Berger and Klus Hein",
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doi = "10.1021/ef000213+",
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Behavior of chlorine and enrichment of risky elements in bubbling fluidized bed combustion of biomass and waste assisted by additives. / Coda, Beatrice (Corresponding Author); Aho, Martti; Berger, Roland; Hein, Klus.

In: Energy & Fuels, Vol. 15, No. 3, 2001, p. 680-690.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Behavior of chlorine and enrichment of risky elements in bubbling fluidized bed combustion of biomass and waste assisted by additives

AU - Coda, Beatrice

AU - Aho, Martti

AU - Berger, Roland

AU - Hein, Klus

PY - 2001

Y1 - 2001

N2 - High contents of chlorine and alkalies restrict the use of biomass in energy production. Alkali chlorides vaporize during combustion. Chlorine tends to produce corrosive deposits and unacceptably high emissions of HCl and dioxins. Chlorine recovery and enrichment of Cl, Na, K, Ca, Al, and Si in coarse and fine fly ash were studied experimentally with two electrically stabilized bubbling fluidized bed (BFB) reactors capable of reproducing the particle residence times existing in full-scale BFB plants. Feedstocks were fir (mixture of heartwood and bark), paper sludge, and blends of fir with agricultural waste or plastic waste. Sulfur concentrations of feed components were low (<0.5 wt %), while chlorine and potassium concentrations ranged widely (0.02−3.2 wt % for Cl and 0.07−3.1 wt % for K). Aluminum-containing additives (kaolin, bauxite and fly ash from a pulverized coal plant) and limestone were added to the feedstocks at various dosages to evaluate their influence on Cl behavior and enrichment of the elements of interest. HCl was measured by FTIR and wet-absorption methods. Different ash samples (bed, cyclone and filter ash) were characterized for their Cl content and the major ash-forming constituents. Cl was completely volatilized from bed ash and recovered only in coarse (cyclone) and fine (filter) fly ash fractions. Al-containing additives increased HCl formation and decreased Cl concentration in the fly ash. In the case of Al−Si based additives, evidence was found of the formation of alkali aluminum silicates from alkali chlorides. The aluminum silicates were transferred mainly to the coarse fly ash fraction. Al-based additives also seemed to liberate Cl from alkali chlorides with reactions forming water-soluble alkali compounds. Limestone had the opposite effect to the Al-containing additives by binding Cl from gas phase to fly ash, but mainly to the coarse fly ash fraction. The results will be useful in optimizing the behavior of chlorine in bubbling bed combustion of Cl- and alkali-containing biomass.

AB - High contents of chlorine and alkalies restrict the use of biomass in energy production. Alkali chlorides vaporize during combustion. Chlorine tends to produce corrosive deposits and unacceptably high emissions of HCl and dioxins. Chlorine recovery and enrichment of Cl, Na, K, Ca, Al, and Si in coarse and fine fly ash were studied experimentally with two electrically stabilized bubbling fluidized bed (BFB) reactors capable of reproducing the particle residence times existing in full-scale BFB plants. Feedstocks were fir (mixture of heartwood and bark), paper sludge, and blends of fir with agricultural waste or plastic waste. Sulfur concentrations of feed components were low (<0.5 wt %), while chlorine and potassium concentrations ranged widely (0.02−3.2 wt % for Cl and 0.07−3.1 wt % for K). Aluminum-containing additives (kaolin, bauxite and fly ash from a pulverized coal plant) and limestone were added to the feedstocks at various dosages to evaluate their influence on Cl behavior and enrichment of the elements of interest. HCl was measured by FTIR and wet-absorption methods. Different ash samples (bed, cyclone and filter ash) were characterized for their Cl content and the major ash-forming constituents. Cl was completely volatilized from bed ash and recovered only in coarse (cyclone) and fine (filter) fly ash fractions. Al-containing additives increased HCl formation and decreased Cl concentration in the fly ash. In the case of Al−Si based additives, evidence was found of the formation of alkali aluminum silicates from alkali chlorides. The aluminum silicates were transferred mainly to the coarse fly ash fraction. Al-based additives also seemed to liberate Cl from alkali chlorides with reactions forming water-soluble alkali compounds. Limestone had the opposite effect to the Al-containing additives by binding Cl from gas phase to fly ash, but mainly to the coarse fly ash fraction. The results will be useful in optimizing the behavior of chlorine in bubbling bed combustion of Cl- and alkali-containing biomass.

KW - fluidized beds

KW - biomass

KW - bioenergy

KW - biofuels

KW - wastes

KW - residues

KW - combustion

KW - emissions

KW - heavy metals

KW - chlorine compounds

KW - fluidized bed combustion

KW - potassium

KW - sodium

KW - aluminum

KW - agricultural wastes

KW - plastics

U2 - 10.1021/ef000213+

DO - 10.1021/ef000213+

M3 - Article

VL - 15

SP - 680

EP - 690

JO - Energy & Fuels

JF - Energy & Fuels

SN - 0887-0624

IS - 3

ER -