Skip to main content
SpringerLink
Log in

Compositional and structural study of ash deposits spatially distributed in superheaters of a large biomass-fired CFB boiler

  • Research Article
  • Published:
Frontiers in Energy Aims and scope Submit manuscript

Abstract

Recognizing the nature and formation progress of the ash deposits is essential to resolve the deposition problem hindering the wide application of large-scale biomass-fired boilers. Therefore, the ash deposits in the superheaters of a 220 t/h biomass-fired CFB boiler were studied, including the platen (PS), the high-temperature (HTS), the upper and the lower low-temperature superheaters (LTS). The results showed that the deposits in the PSs and HTSs were thin (several millimeters) and compact, consisting of a yellow outer layer and snow-white inner layer near the tube surface. The deposits in the upper LTS appeared to be toughly sintered ceramic, while those in the lower LTS were composed of dispersive coarse ash particles with an unsintered surface. Detailed characterization of the cross-section and the initial layers in the deposits revealed that the dominating compositions in both the PSs and the HTSs were Cl and K (approximately 70%) in the form of KCl. Interestingly, the cross-section of the deposition in the upper LTS exhibited a unique lamellar structure with a major composition of Ca and S. The contents of Ca and Si increased from approximately 10% to approximately 60% in the deposits from the high temperature surfaces to the low temperature ones. It was concluded that the vaporized mineral matter such as KCl played the most important role in the deposition progress in the PS and the HTS. In addition, although the condensation of KCl in the LTSs also happened, the deposition of ash particles played a more important role.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

Abbreviations

CFB:

Circulating fluidized bed

PS:

Platen superheater

HTS:

High-temperature superheater

LTS:

Low-temperature superheater

EPMA:

Electron probe microanalyzer

IC:

Ion chromatography

XRF:

X-ray fluorescence

XRD:

X-ray diffraction

References

  1. Demirbas A. Potential applications of renewable energy sources, biomass combustion problems in boiler power systems and combustion related environmental issues. Progress in Energy and Combustion Science, 2005, 31(2): 171–192

    Article  Google Scholar 

  2. Saidur R, Abdelaziz E A, Demirbas A, et al. A review on biomass as a fuel for boilers. Renewable & Sustainable Energy Reviews, 2011, 15(5): 2262–2289

    Article  Google Scholar 

  3. Alam M T, Dai B, Wu X, et al. A critical review of ash slagging mechanisms and viscosity measurement for low-rank coal and bio-slags. Frontiers in Energy, 2020, online, doi: https://doi.org/10.1007/s11708-020-0807-8

  4. Khan A A, De Jong W, Jansens P J, et al. Biomass combustion in fluidized bed boilers: potential problems and remedies. Fuel Processing Technology, 2009, 90(1): 21–50

    Article  Google Scholar 

  5. Capablo J. Formation of alkali salt deposits in biomass combustion. Fuel Processing Technology, 2016, 153: 58–73

    Article  Google Scholar 

  6. Niu Y, Tan H, Hui S. Ash-related issues during biomass combustion: alkali-induced slagging, silicate melt-induced slagging (ash fusion), agglomeration, corrosion, ash utilization, and related countermeasures. Progress in Energy and Combustion Science, 2016, 52: 1–61

    Article  Google Scholar 

  7. Bryers R W. Fireside slagging, fouling, and high-temperature corrosion of heat-transfer surface due to impurities in steam-raising fuels. Progress in Energy and Combustion Science, 1996, 22(1): 29–120

    Article  Google Scholar 

  8. Nielsen H P, Frandsen F J, Dam-Johansen K. Lab-scale investigations of high-temperature corrosion phenomena in straw-fired boilers. Energy & Fuels, 1999, 13(6): 1114–1121

    Article  Google Scholar 

  9. Nielsen H P, Frandsen F J, Dam-Johansen K, et al. The implications of chlorine-associated corrosion on the operation of biomass-fired boilers. Progress in Energy and Combustion Science, 2000, 26(3): 283–298

    Article  Google Scholar 

  10. Nunes L, Matias J, Catalão J. Biomass combustion systems: a review on the physical and chemical properties of the ashes. Renewable & Sustainable Energy Reviews, 2016, 53: 235–242

    Article  Google Scholar 

  11. Wang W, Wen C, Li C, et al. Emission reduction of particulate matter from the combustion of biochar via thermal pre-treatment of torrefaction, slow pyrolysis or hydrothermal carbonisation and its co-combustion with pulverized coal. Fuel, 2019, 240: 278–288

    Article  Google Scholar 

  12. Baxter L L, Miles T R, Miles T R Jr, et al. The behavior of inorganic material in biomass-fired power boilers: field and laboratory experiences. Fuel Processing Technology, 1998, 54(1–3): 47–78

    Article  Google Scholar 

  13. Knudsen J N, Jensen P A, Dam-Johansen K. Transformation and release to the gas phase of Cl, K, and S during combustion of annual biomass. Energy & Fuels, 2004, 18(5): 1385–1399

    Article  Google Scholar 

  14. Xu Y, Liu X, Qi J, et al. Characterization of fine particulate matter generated in a large woody biomass-firing circulating fluid bed boiler. Journal of the Energy Institute, 2021, 96: 11–18

    Article  Google Scholar 

  15. Li B, Sun Z, Li Z, et al. Post-flame gas-phase sulfation of potassium chloride. Combustion and Flame, 2013, 160(5): 959–969

    Article  Google Scholar 

  16. Nielsen H P, Baxter L L, Sclippab G, et al. Deposition of potassium salts on heat transfer surfaces in straw-fired boilers: a pilot-scale study. Fuel, 2000, 79(2): 131–139

    Article  Google Scholar 

  17. Chen S, Li S, Marshall J S. Exponential scaling in early-stage agglomeration of adhesive particles in turbulence. Physical Review Fluids, 2019, 4(2): 024304

    Article  Google Scholar 

  18. Niu Y, Zhu Y, Tan H, et al. Experimental study on the coexistent dual slagging in biomass-fired furnaces: alkali- and silicate melt-induced slagging. Proceedings of the Combustion Institute, 2015, 35 (2): 2405–2413

    Article  Google Scholar 

  19. Miles T R, Miles T R Jr, Baxter L L, et al. Boiler deposits from firing biomass fuels. Biomass and Bioenergy, 1996, 10(2–3): 125–138

    Article  Google Scholar 

  20. Namkung H, Xu L, Lin K, et al. Relationship between chemical components and coal ash deposition through the DTF experiments using real-time weight measurement system. Fuel Processing Technology, 2017, 158: 206–217

    Article  Google Scholar 

  21. Aho M, Paakkinen K, Taipale R. Quality of deposits during grate combustion of corn stover and wood chip blends. Fuel, 2013, 104: 476–487

    Article  Google Scholar 

  22. Garba M U, Ingham D B, Ma L, et al. Prediction of potassium chloride sulfation and its effect on deposition in biomass-fired boilers. Energy & Fuels, 2012, 26(11): 6501–6508

    Article  Google Scholar 

  23. Niu Y, Tan H, Wang X, et al. Study on deposits on the surface, upstream, and downstream of bag filters in a 12 MW biomass-fired boiler. Energy & Fuels, 2010, 24(3): 2127–2132

    Article  Google Scholar 

  24. Liu H, Tan H, Liu Y, et al. Study of the layered structure of deposit in a biomass-fired boiler (case study). Energy & Fuels, 2011, 25(6): 2593–2600

    Article  Google Scholar 

  25. Niu Y, Tan H, Ma L, et al. Slagging characteristics on the superheaters of a 12 MW biomass-fired boiler. Energy & Fuels, 2010, 24(9): 5222–5227

    Article  Google Scholar 

  26. Hansen L A, Nielsen H P, Frandsen F J, et al. Influence of deposit formation on corrosion at a straw-fired boiler. Fuel Processing Technology, 2000, 64(1–3): 189–209

    Article  Google Scholar 

  27. Huang Z, Deng L, Che D. Development and technical progress in large-scale circulating fluidized bed boiler in China. Frontiers in Energy, 2020 14(4): 699–714

    Article  Google Scholar 

  28. Liu Z, Li J, Zhu M, et al. Effect of oil shale semi-coke on deposit mineralogy and morphology in the flue path of a CFB burning Zhundong lignite. Frontiers in Energy, 2020, doi:https://doi.org/10.1007/s11708-020-0668-1

  29. Hupa M. Ash-related issues in fluidized-bed combustion of biomasses: recent research highlights. Energy & Fuels, 2012, 26 (1): 4–14

    Article  Google Scholar 

  30. Arjunwadkar A, Basu P, Acharya B. A review of some operation and maintenance issues of CFBC boilers. Applied Thermal Engineering, 2016, 102: 672–694

    Article  Google Scholar 

  31. Scala F. Particle agglomeration during fluidized bed combustion: mechanisms, early detection and possible countermeasures. Fuel Processing Technology, 2018, 171: 31–38

    Article  Google Scholar 

  32. Valmari T, Lind T M, Kauppinen E I, et al. Field study on ash behavior during circulating fluidized-bed combustion of biomass. 2. Ash deposition and alkali vapor condensation. Energy & Fuels, 1999, 13(2): 390–395

    Article  Google Scholar 

  33. Li L, Yu C, Huang F, et al. Study on the deposits derived from a biomass circulating fluidized-bed boiler. Energy & Fuels, 2012, 26 (9): 6008–6014

    Article  Google Scholar 

  34. Sandberg J, Karlsson C, Fdhila R B A. 7-year long measurement period investigating the correlation of corrosion, deposit and fuel in a biomass fired circulated fluidized bed boiler. Applied Energy, 2011, 88(1): 99–110

    Article  Google Scholar 

  35. Wei B, Tan H, Wang Y, et al. Investigation of characteristics and formation mechanisms of deposits on different positions in full-scale boiler burning high alkali coal. Applied Thermal Engineering, 2017, 119: 449–458

    Article  Google Scholar 

  36. Xu Y, Liu X, Wang H, et al. Influences of in-furnace Kaolin addition on the formation and emission characteristics of PM2.5 in a 1000 MW coal-fired power station. Environmental Science & Technology, 2018, 52(15): 8718–8724

    Article  Google Scholar 

  37. Xu Y, Liu X, Zhang P, et al. Role of chlorine in ultrafine particulate matter formation during the combustion of a blend of high-Cl coal and low-Cl coal. Fuel, 2016, 184: 185–191

    Article  Google Scholar 

  38. Xu Y, Liu X, Zhang Y, et al. A novel Ti-based sorbent for reducing ultrafine particulate matter formation during coal combustion. Fuel, 2017, 193: 72–80

    Article  Google Scholar 

  39. Jenkins B, Baxter L L, Miles T R Jr, et al. Combustion properties of biomass. Fuel Processing Technology, 1998, 54(1–3): 17–46

    Article  Google Scholar 

  40. Wang Y, Tan H, Wang X, et al. The condensation and thermodynamic characteristics of alkali compound vapors on wall during wheat straw combustion. Fuel, 2017, 187: 33–42

    Article  Google Scholar 

  41. Christensen K A, Stenholm M, Livbjerg H. The formation of submicron aerosol particles, HCl and SO2 in straw-fired boilers. Journal of Aerosol Science, 1998, 29(4): 421–444

    Article  Google Scholar 

  42. Johansson L S, Leckner B, Tullin C L, et al. Properties of particles in the fly ash of a biofuel-fired circulating fluidized bed (CFB) boiler. Energy & Fuels, 2008, 22(5): 3005–3015

    Article  Google Scholar 

  43. Wang X, Xu Z, Wei B, et al. The ash deposition mechanism in boilers burning Zhundong coal with high contents of sodium and calcium: a study from ash evaporating to condensing. Applied Thermal Engineering, 2015, 80: 150–159

    Article  Google Scholar 

Download references

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant Nos. 51806075 and 51922045), and the Analytical and Testing Center of Huazhong University of Science and Technology.

Author information

Authors and Affiliations

  1. State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, 430074, China

    Yishu Xu, Xiaowei Liu, Jiuxin Qi, Tianpeng Zhang & Minghou Xu

  2. School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China

    Yishu Xu

  3. Guangdong Yudean Zhanjiang Biomass Power Plant, Zhanjiang, 524300, China

    Fangfang Fei & Dingqing Li

Authors
  1. Yishu Xu
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Xiaowei Liu
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Jiuxin Qi
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Tianpeng Zhang
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Minghou Xu
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Fangfang Fei
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Dingqing Li
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Xiaowei Liu.

Supplementary information

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Xu, Y., Liu, X., Qi, J. et al. Compositional and structural study of ash deposits spatially distributed in superheaters of a large biomass-fired CFB boiler. Front. Energy 15, 449–459 (2021). https://doi.org/10.1007/s11708-021-0734-3

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11708-021-0734-3

Keywords

Search

Navigation