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Advanced air staging techniques to improve fuel flexibility, reliability and emissions in fluidized bed co-combustion

Abstract

A joint research project between the Technical University of Hamburg-Harburg and Chalmers Technical University. For operation under co-combustion the following results should be considered: The high ash content of the sewage sludge results in significantly increased ash flows. Although high alkali metal concentrations are found in the sewage sludge ash, no critical concentrations were reached and tendencies to fouling were not observed. The trace metal input rises with increased sludge fraction. However, emissions of metal compounds were well below legal limits. The trace metals tend to accumulate on the fly ash. In general, very low fuel nitrogen conversions to NO and N{sub 2}O of 2 - 4 % are achievable. With coal as a base fuel alternative air staging with secondary air supply after solids separation attains even lower NO emissions than normal staging without strongly affecting CO and SO{sub 2} emissions. Alternative staging also reduces N{sub 2}O emissions. An optimum for the excess air ratio in the riser of 1.05 was found for a total excess air ratio of 1.2. The higher the volatile content of the fuel is, the less effective the NO reduction due to air staging becomes. The measurements suggest that the optimum gas residence time  More>>
Authors:
Aamand, Lars-Erik; Leckner, Bo; [1]  Luecke, Karsten; Werther, Joachim [2] 
  1. Chalmers Technical Univ., Goeteborg (Sweden)
  2. Technical Univ. of Hamburg-Harburg (Germany)
Publication Date:
Dec 01, 2001
Product Type:
Technical Report
Report Number:
SVF-756
Resource Relation:
Other Information: 61 figs, 13 tabs. (with a 12 p. summary in German); PBD: Dec 2001
Subject:
09 BIOMASS FUELS; 20 FOSSIL-FUELED POWER PLANTS; STAGED COMBUSTION; FLUIDIZED-BED COMBUSTION; RELIABILITY; SEWAGE SLUDGE; COAL; CIRCULATING SYSTEMS; NITROGEN OXIDES; CARBON MONOXIDE; SULFUR OXIDES
OSTI ID:
20247210
Research Organizations:
Vaermeforsk, Stockholm (Sweden)
Country of Origin:
Sweden
Language:
English
Other Identifying Numbers:
Other: Project Vaermeforsk-P9-607; ISSN 0282-3772; TRN: SE0207163
Availability:
Available from: Vaermeforsk Service AB, SE-101 53 Stockholm, Sweden; Available to ETDE participating countries only(see www.etde.org); commercial reproduction prohibited; OSTI as DE20247210
Submitting Site:
SWD
Size:
108 pages
Announcement Date:

Citation Formats

Aamand, Lars-Erik, Leckner, Bo, Luecke, Karsten, and Werther, Joachim. Advanced air staging techniques to improve fuel flexibility, reliability and emissions in fluidized bed co-combustion. Sweden: N. p., 2001. Web.
Aamand, Lars-Erik, Leckner, Bo, Luecke, Karsten, & Werther, Joachim. Advanced air staging techniques to improve fuel flexibility, reliability and emissions in fluidized bed co-combustion. Sweden.
Aamand, Lars-Erik, Leckner, Bo, Luecke, Karsten, and Werther, Joachim. 2001. "Advanced air staging techniques to improve fuel flexibility, reliability and emissions in fluidized bed co-combustion." Sweden.
@misc{etde_20247210,
title = {Advanced air staging techniques to improve fuel flexibility, reliability and emissions in fluidized bed co-combustion}
author = {Aamand, Lars-Erik, Leckner, Bo, Luecke, Karsten, and Werther, Joachim}
abstractNote = {A joint research project between the Technical University of Hamburg-Harburg and Chalmers Technical University. For operation under co-combustion the following results should be considered: The high ash content of the sewage sludge results in significantly increased ash flows. Although high alkali metal concentrations are found in the sewage sludge ash, no critical concentrations were reached and tendencies to fouling were not observed. The trace metal input rises with increased sludge fraction. However, emissions of metal compounds were well below legal limits. The trace metals tend to accumulate on the fly ash. In general, very low fuel nitrogen conversions to NO and N{sub 2}O of 2 - 4 % are achievable. With coal as a base fuel alternative air staging with secondary air supply after solids separation attains even lower NO emissions than normal staging without strongly affecting CO and SO{sub 2} emissions. Alternative staging also reduces N{sub 2}O emissions. An optimum for the excess air ratio in the riser of 1.05 was found for a total excess air ratio of 1.2. The higher the volatile content of the fuel is, the less effective the NO reduction due to air staging becomes. The measurements suggest that the optimum gas residence time regarding the emissions in CFB combustors is around 6 to 7 s. These times are achieved in commercial scale plants due to their large cyclones that perhaps partly can replace a large afterburner chamber. The circulating fluidized bed boiler can be operated in a very flexible way with various fuel mixtures up to an energy fraction of sludge of 25% without exceeding legal emission limits.}
place = {Sweden}
year = {2001}
month = {Dec}
}