Effects of ash removal by agitated aqueous washing and sedimentation on the physico-chemical characteristics and fast pyrolysis of trommel fines

Jude A. Onwudili, Joseph E. Eke

Research output: Contribution to journalArticle

Abstract

A pre-treated trommel fines feedstock (DPT) with 35.1 wt% ash content and particle size range of 0.5–2 mm was processed through two (100% distilled water and 1% surfactant in distilled water) aqueous agitated washing and sedimentation procedures for ash reduction prior to fast pyrolysis in a bubbling fluidized bed reactor. The washing process led to more than 36% reduction in the ash/inorganic contents of the DPT feedstock and yielded about 78 wt% of organic-rich feedstocks denoted as WPT1 and WPT2. Characterisation and fast pyrolysis of all three feedstocks was carried out to evaluate the effect of the washing process on their physico-chemical characteristics and yields of fast pyrolysis products. Results showed that the ash reduction led to increase in the volatile matter contents of the washed feedstocks by 20%, while reducing nitrogen contents. In addition, fast pyrolysis of the feedstocks showed improved yield of liquid and gas products, with a dramatic reduction of reaction water, indicating that the ash removal reduced the catalytic effect of the ash on water formation during the fast pyrolysis process. The major organic compounds in the liquid products included phenols and furans from biogenic fraction of the feedstock as well as aromatic hydrocarbons such as those obtained from pyrolysis of plastics. More importantly, the overall energy yields from the fast pyrolysis process increased by over 35% after washing the feedstock, with washing with only distilled water alone giving the highest energy yield of 93%. Hence, coupling the water-washing ash reduction process with fast pyrolysis appeared to be a suitable technology for valorising feedstocks with high ash contents such as trommel fines for energy and chemicals.

Original languageEnglish
Pages (from-to)312-323
Number of pages12
JournalJournal of the Energy Institute
Volume93
Issue number1
Early online date6 Mar 2019
DOIs
Publication statusPublished - Feb 2020

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Ashes
fines
washing
ashes
Sedimentation
Washing
Feedstocks
pyrolysis
Pyrolysis
water
Water
products
furans
liquids
Aromatic hydrocarbons
organic compounds
Liquids
phenols
Organic compounds
energy

Bibliographical note

© 2019 Published by Elsevier Ltd on behalf of Energy Institute. CC BY-NC-ND.

Keywords

  • Agitated washing
  • Ash removal
  • Energy recovery
  • Fast pyrolysis
  • Pre-treated trommel fines

Cite this

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title = "Effects of ash removal by agitated aqueous washing and sedimentation on the physico-chemical characteristics and fast pyrolysis of trommel fines",
abstract = "A pre-treated trommel fines feedstock (DPT) with 35.1 wt{\%} ash content and particle size range of 0.5–2 mm was processed through two (100{\%} distilled water and 1{\%} surfactant in distilled water) aqueous agitated washing and sedimentation procedures for ash reduction prior to fast pyrolysis in a bubbling fluidized bed reactor. The washing process led to more than 36{\%} reduction in the ash/inorganic contents of the DPT feedstock and yielded about 78 wt{\%} of organic-rich feedstocks denoted as WPT1 and WPT2. Characterisation and fast pyrolysis of all three feedstocks was carried out to evaluate the effect of the washing process on their physico-chemical characteristics and yields of fast pyrolysis products. Results showed that the ash reduction led to increase in the volatile matter contents of the washed feedstocks by 20{\%}, while reducing nitrogen contents. In addition, fast pyrolysis of the feedstocks showed improved yield of liquid and gas products, with a dramatic reduction of reaction water, indicating that the ash removal reduced the catalytic effect of the ash on water formation during the fast pyrolysis process. The major organic compounds in the liquid products included phenols and furans from biogenic fraction of the feedstock as well as aromatic hydrocarbons such as those obtained from pyrolysis of plastics. More importantly, the overall energy yields from the fast pyrolysis process increased by over 35{\%} after washing the feedstock, with washing with only distilled water alone giving the highest energy yield of 93{\%}. Hence, coupling the water-washing ash reduction process with fast pyrolysis appeared to be a suitable technology for valorising feedstocks with high ash contents such as trommel fines for energy and chemicals.",
keywords = "Agitated washing, Ash removal, Energy recovery, Fast pyrolysis, Pre-treated trommel fines",
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AU - Onwudili, Jude A.

AU - Eke, Joseph E.

N1 - © 2019 Published by Elsevier Ltd on behalf of Energy Institute. CC BY-NC-ND.

PY - 2020/2

Y1 - 2020/2

N2 - A pre-treated trommel fines feedstock (DPT) with 35.1 wt% ash content and particle size range of 0.5–2 mm was processed through two (100% distilled water and 1% surfactant in distilled water) aqueous agitated washing and sedimentation procedures for ash reduction prior to fast pyrolysis in a bubbling fluidized bed reactor. The washing process led to more than 36% reduction in the ash/inorganic contents of the DPT feedstock and yielded about 78 wt% of organic-rich feedstocks denoted as WPT1 and WPT2. Characterisation and fast pyrolysis of all three feedstocks was carried out to evaluate the effect of the washing process on their physico-chemical characteristics and yields of fast pyrolysis products. Results showed that the ash reduction led to increase in the volatile matter contents of the washed feedstocks by 20%, while reducing nitrogen contents. In addition, fast pyrolysis of the feedstocks showed improved yield of liquid and gas products, with a dramatic reduction of reaction water, indicating that the ash removal reduced the catalytic effect of the ash on water formation during the fast pyrolysis process. The major organic compounds in the liquid products included phenols and furans from biogenic fraction of the feedstock as well as aromatic hydrocarbons such as those obtained from pyrolysis of plastics. More importantly, the overall energy yields from the fast pyrolysis process increased by over 35% after washing the feedstock, with washing with only distilled water alone giving the highest energy yield of 93%. Hence, coupling the water-washing ash reduction process with fast pyrolysis appeared to be a suitable technology for valorising feedstocks with high ash contents such as trommel fines for energy and chemicals.

AB - A pre-treated trommel fines feedstock (DPT) with 35.1 wt% ash content and particle size range of 0.5–2 mm was processed through two (100% distilled water and 1% surfactant in distilled water) aqueous agitated washing and sedimentation procedures for ash reduction prior to fast pyrolysis in a bubbling fluidized bed reactor. The washing process led to more than 36% reduction in the ash/inorganic contents of the DPT feedstock and yielded about 78 wt% of organic-rich feedstocks denoted as WPT1 and WPT2. Characterisation and fast pyrolysis of all three feedstocks was carried out to evaluate the effect of the washing process on their physico-chemical characteristics and yields of fast pyrolysis products. Results showed that the ash reduction led to increase in the volatile matter contents of the washed feedstocks by 20%, while reducing nitrogen contents. In addition, fast pyrolysis of the feedstocks showed improved yield of liquid and gas products, with a dramatic reduction of reaction water, indicating that the ash removal reduced the catalytic effect of the ash on water formation during the fast pyrolysis process. The major organic compounds in the liquid products included phenols and furans from biogenic fraction of the feedstock as well as aromatic hydrocarbons such as those obtained from pyrolysis of plastics. More importantly, the overall energy yields from the fast pyrolysis process increased by over 35% after washing the feedstock, with washing with only distilled water alone giving the highest energy yield of 93%. Hence, coupling the water-washing ash reduction process with fast pyrolysis appeared to be a suitable technology for valorising feedstocks with high ash contents such as trommel fines for energy and chemicals.

KW - Agitated washing

KW - Ash removal

KW - Energy recovery

KW - Fast pyrolysis

KW - Pre-treated trommel fines

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VL - 93

SP - 312

EP - 323

JO - Journal of the Energy Institute

JF - Journal of the Energy Institute

SN - 0144-2600

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ER -