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Title: Effect of bed pressure drop on performance of a CFB boiler

Abstract

The effect of bed pressure drop and bed inventory on the performances of a circulating fluidized bed (CFB) boiler was studied. By using the state specification design theory, the fluidization state of the gas-solids flow in the furnace of conventional CFB boilers was reconstructed to operate at a much lower bed pressure drop by reducing bed inventory and control bed quality. Through theoretical analysis, it was suggested that there would exist a theoretical optimal value of bed pressure drop, around which the boiler operation can achieve the maximal combustion efficiency and with significant reduction of the wear of the heating surface and fan energy consumption. The analysis was validated by field tests carried out in a 75 t/h CFB boiler. At full boiler load, when bed pressure drop was reduced from 7.3 to 3.2 kPa, the height of the dense zone in the lower furnace decreased, but the solid suspension density profile in the upper furnace and solid flow rate were barely influenced. Consequently, the average heat transfer coefficient in the furnace was kept nearly the same and the furnace temperature increment was less than 17{sup o}C. It was also found that the carbon content in the fly ash decreasedmore » first with decreasing bed pressure drop and then increased with further increasing bed pressure drop. The turning point with minimal carbon content was referred to as the point with optimal bed pressure drop. For this boiler, at the optimum point the bed pressure was around 5.7 kPa with the overall excess air ratio of 1.06. When the boiler was operated around this optimal point, not only the combustion efficiency was improved, but also fan energy consumption and wear of heating surface were reduced. 23 refs., 6 figs., 4 tabs.« less

Authors:
; ; ; ; ;  [1]
  1. Tsinghua University, Beijing (China). Department of Thermal Engineering
Publication Date:
OSTI Identifier:
21240426
Resource Type:
Journal Article
Journal Name:
Energy and Fuels
Additional Journal Information:
Journal Volume: 23; Journal Issue: 6; Journal ID: ISSN 0887-0624
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; FLUIDIZED BED BOILERS; CIRCULATING SYSTEMS; PERFORMANCE; PRESSURE DROP; FLUIDIZATION; FIELD TESTS; FLUIDIZED-BED COMBUSTION; OPTIMIZATION; BURNOUT

Citation Formats

Yang, Hairui, Zhang, Hai, Yang, Shi, Yue, Guangxi, Su, Jun, and Fu, Zhiping. Effect of bed pressure drop on performance of a CFB boiler. United States: N. p., 2009. Web. doi:10.1021/ef900025h.
Yang, Hairui, Zhang, Hai, Yang, Shi, Yue, Guangxi, Su, Jun, & Fu, Zhiping. Effect of bed pressure drop on performance of a CFB boiler. United States. https://doi.org/10.1021/ef900025h
Yang, Hairui, Zhang, Hai, Yang, Shi, Yue, Guangxi, Su, Jun, and Fu, Zhiping. 2009. "Effect of bed pressure drop on performance of a CFB boiler". United States. https://doi.org/10.1021/ef900025h.
@article{osti_21240426,
title = {Effect of bed pressure drop on performance of a CFB boiler},
author = {Yang, Hairui and Zhang, Hai and Yang, Shi and Yue, Guangxi and Su, Jun and Fu, Zhiping},
abstractNote = {The effect of bed pressure drop and bed inventory on the performances of a circulating fluidized bed (CFB) boiler was studied. By using the state specification design theory, the fluidization state of the gas-solids flow in the furnace of conventional CFB boilers was reconstructed to operate at a much lower bed pressure drop by reducing bed inventory and control bed quality. Through theoretical analysis, it was suggested that there would exist a theoretical optimal value of bed pressure drop, around which the boiler operation can achieve the maximal combustion efficiency and with significant reduction of the wear of the heating surface and fan energy consumption. The analysis was validated by field tests carried out in a 75 t/h CFB boiler. At full boiler load, when bed pressure drop was reduced from 7.3 to 3.2 kPa, the height of the dense zone in the lower furnace decreased, but the solid suspension density profile in the upper furnace and solid flow rate were barely influenced. Consequently, the average heat transfer coefficient in the furnace was kept nearly the same and the furnace temperature increment was less than 17{sup o}C. It was also found that the carbon content in the fly ash decreased first with decreasing bed pressure drop and then increased with further increasing bed pressure drop. The turning point with minimal carbon content was referred to as the point with optimal bed pressure drop. For this boiler, at the optimum point the bed pressure was around 5.7 kPa with the overall excess air ratio of 1.06. When the boiler was operated around this optimal point, not only the combustion efficiency was improved, but also fan energy consumption and wear of heating surface were reduced. 23 refs., 6 figs., 4 tabs.},
doi = {10.1021/ef900025h},
url = {https://www.osti.gov/biblio/21240426}, journal = {Energy and Fuels},
issn = {0887-0624},
number = 6,
volume = 23,
place = {United States},
year = {Fri May 15 00:00:00 EDT 2009},
month = {Fri May 15 00:00:00 EDT 2009}
}