Biomass Fly Ash Deposition in an Entrained Flow Reactor

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Fly ash deposition on boiler surfaces is a major operational problem encountered in biomass-fired boilers. Understanding deposit formation, and developing modelling tools, will allow improvements in boiler efficiency and availability. In this study, deposit formation of a model biomass ash species (K2Si4O9) on steel tubes, was investigated in a lab-scale Entrained Flow Reactor. K2Si4O9 was injected into the reactor, to form deposits on an air-cooled probe, simulating deposit formation on superheater tubes in boilers. The influence of flue gas temperature (589 – 968°C), probe surface temperature (300 – 550°C), flue gas velocity (0.7 – 3.5 m/s), fly ash flux (10,000 – 40,000 g/m2h), and probe residence time (up to 60 min) was investigated. The results revealed that increasing flue gas temperature and probe surface temperature increased the sticking probability of the fly ash particles, thereby increasing the rate of deposit formation. However, increasing flue gas velocity resulted in a decrease in the deposit formation rate, due to increased particle rebound. Furthermore, the deposit formation rate increased with probe residence time and fly ash flux. Inertial impaction was the primary mechanism of deposit formation, forming deposits only on the upstream side of the steel tube. A mechanistic model was developed for predicting deposit formation in the reactor. Deposit formation by thermophoresis and inertial impaction was incorporated into the model, and the sticking probability of the ash particles was estimated by accounting for energy dissipation due to particle deformation. The model reasonably predicted the influence of flue gas temperature and fly ash flux on the deposit formation rate.
Original languageEnglish
JournalProceedings of the Combustion Institute
Volume37
Issue number3
Pages (from-to)2689-2696
ISSN1540-7489
DOIs
Publication statusPublished - 2019

Keywords

  • Biomass
  • Fly ash
  • Deposit formation
  • Fouling
  • Ash sticking probability

Cite this

@article{63fe34d130b34ba3928eea92ea69f4be,
title = "Biomass Fly Ash Deposition in an Entrained Flow Reactor",
abstract = "Fly ash deposition on boiler surfaces is a major operational problem encountered in biomass-fired boilers. Understanding deposit formation, and developing modelling tools, will allow improvements in boiler efficiency and availability. In this study, deposit formation of a model biomass ash species (K2Si4O9) on steel tubes, was investigated in a lab-scale Entrained Flow Reactor. K2Si4O9 was injected into the reactor, to form deposits on an air-cooled probe, simulating deposit formation on superheater tubes in boilers. The influence of flue gas temperature (589 – 968°C), probe surface temperature (300 – 550°C), flue gas velocity (0.7 – 3.5 m/s), fly ash flux (10,000 – 40,000 g/m2h), and probe residence time (up to 60 min) was investigated. The results revealed that increasing flue gas temperature and probe surface temperature increased the sticking probability of the fly ash particles, thereby increasing the rate of deposit formation. However, increasing flue gas velocity resulted in a decrease in the deposit formation rate, due to increased particle rebound. Furthermore, the deposit formation rate increased with probe residence time and fly ash flux. Inertial impaction was the primary mechanism of deposit formation, forming deposits only on the upstream side of the steel tube. A mechanistic model was developed for predicting deposit formation in the reactor. Deposit formation by thermophoresis and inertial impaction was incorporated into the model, and the sticking probability of the ash particles was estimated by accounting for energy dissipation due to particle deformation. The model reasonably predicted the influence of flue gas temperature and fly ash flux on the deposit formation rate.",
keywords = "Biomass, Fly ash, Deposit formation, Fouling, Ash sticking probability",
author = "Yashasvi Laxminarayan and Jensen, {Peter Arendt} and Hao Wu and {Jappe Frandsen}, Flemming and Bo Sander and Peter Glarborg",
year = "2019",
doi = "10.1016/j.proci.2018.06.039",
language = "English",
volume = "37",
pages = "2689--2696",
journal = "Proceedings of the Combustion Institute",
issn = "1540-7489",
publisher = "Elsevier",
number = "3",

}

Biomass Fly Ash Deposition in an Entrained Flow Reactor. / Laxminarayan, Yashasvi; Jensen, Peter Arendt; Wu, Hao; Jappe Frandsen, Flemming; Sander, Bo; Glarborg, Peter.

In: Proceedings of the Combustion Institute, Vol. 37, No. 3, 2019, p. 2689-2696.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Biomass Fly Ash Deposition in an Entrained Flow Reactor

AU - Laxminarayan, Yashasvi

AU - Jensen, Peter Arendt

AU - Wu, Hao

AU - Jappe Frandsen, Flemming

AU - Sander, Bo

AU - Glarborg, Peter

PY - 2019

Y1 - 2019

N2 - Fly ash deposition on boiler surfaces is a major operational problem encountered in biomass-fired boilers. Understanding deposit formation, and developing modelling tools, will allow improvements in boiler efficiency and availability. In this study, deposit formation of a model biomass ash species (K2Si4O9) on steel tubes, was investigated in a lab-scale Entrained Flow Reactor. K2Si4O9 was injected into the reactor, to form deposits on an air-cooled probe, simulating deposit formation on superheater tubes in boilers. The influence of flue gas temperature (589 – 968°C), probe surface temperature (300 – 550°C), flue gas velocity (0.7 – 3.5 m/s), fly ash flux (10,000 – 40,000 g/m2h), and probe residence time (up to 60 min) was investigated. The results revealed that increasing flue gas temperature and probe surface temperature increased the sticking probability of the fly ash particles, thereby increasing the rate of deposit formation. However, increasing flue gas velocity resulted in a decrease in the deposit formation rate, due to increased particle rebound. Furthermore, the deposit formation rate increased with probe residence time and fly ash flux. Inertial impaction was the primary mechanism of deposit formation, forming deposits only on the upstream side of the steel tube. A mechanistic model was developed for predicting deposit formation in the reactor. Deposit formation by thermophoresis and inertial impaction was incorporated into the model, and the sticking probability of the ash particles was estimated by accounting for energy dissipation due to particle deformation. The model reasonably predicted the influence of flue gas temperature and fly ash flux on the deposit formation rate.

AB - Fly ash deposition on boiler surfaces is a major operational problem encountered in biomass-fired boilers. Understanding deposit formation, and developing modelling tools, will allow improvements in boiler efficiency and availability. In this study, deposit formation of a model biomass ash species (K2Si4O9) on steel tubes, was investigated in a lab-scale Entrained Flow Reactor. K2Si4O9 was injected into the reactor, to form deposits on an air-cooled probe, simulating deposit formation on superheater tubes in boilers. The influence of flue gas temperature (589 – 968°C), probe surface temperature (300 – 550°C), flue gas velocity (0.7 – 3.5 m/s), fly ash flux (10,000 – 40,000 g/m2h), and probe residence time (up to 60 min) was investigated. The results revealed that increasing flue gas temperature and probe surface temperature increased the sticking probability of the fly ash particles, thereby increasing the rate of deposit formation. However, increasing flue gas velocity resulted in a decrease in the deposit formation rate, due to increased particle rebound. Furthermore, the deposit formation rate increased with probe residence time and fly ash flux. Inertial impaction was the primary mechanism of deposit formation, forming deposits only on the upstream side of the steel tube. A mechanistic model was developed for predicting deposit formation in the reactor. Deposit formation by thermophoresis and inertial impaction was incorporated into the model, and the sticking probability of the ash particles was estimated by accounting for energy dissipation due to particle deformation. The model reasonably predicted the influence of flue gas temperature and fly ash flux on the deposit formation rate.

KW - Biomass

KW - Fly ash

KW - Deposit formation

KW - Fouling

KW - Ash sticking probability

U2 - 10.1016/j.proci.2018.06.039

DO - 10.1016/j.proci.2018.06.039

M3 - Journal article

VL - 37

SP - 2689

EP - 2696

JO - Proceedings of the Combustion Institute

JF - Proceedings of the Combustion Institute

SN - 1540-7489

IS - 3

ER -