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Title: Co-combustion of sludge with coal or wood

Abstract

There are several options for co-combustion of biomass or waste with coal. In all cases the fuel properties are decisive for the success of the arrangement: contents of volatile matter and of potential emission precursors, such as sulphur, nitrogen, chlorine, and heavy metals. The content of alkali in the mineral substance of the fuel is important because of the danger of fouling and corrosion. Research activities at Chalmers University of Technology include several aspects of the related problems areas. An example is given concerning emissions from co-combustion in circulating fluidized beds with coal or wood as base fuels, and with sewage sludge as additional fuel. Two aspects of the properties of sludge are studied: emissions of nitrogen and sulphur oxides as well as of chlorine, because the contents of the precursors to these emissions are high. The possibility of utilizing the phosphorus in sludge as a fertilizer is also discussed. The results show that emissions can be kept below existing emission limits if the fraction of sludge is sufficiently small but the concentration of trace elements in the sludge ash prevents the sludge from being used as a fertilizer. 15 refs., 9 figs., 2 tabs.

Authors:
;  [1]
  1. Chalmers University of Technology, Goeteborg (Sweden). Dept. of Energy Conversion
Publication Date:
OSTI Identifier:
20490071
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Power and Energy Systems; Journal Volume: 24; Journal Issue: 3; Conference: International conference on co-utilization of domestic fuels, Gainesville, FL (United States), 5-6 Feb 2003; Other Information: energy.conversion@entek.chalmers.se
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 09 BIOMASS FUELS; 60 APPLIED LIFE SCIENCES; 32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; COCOMBUSTION; COAL; WOOD; FUEL PELLETS; SEWAGE SLUDGE; CIRCULATING SYSTEMS; FLUIDIZED-BED COMBUSTION; FLUIDIZED BED BOILERS; NITROGEN OXIDES; NITRIC OXIDE; NITROUS OXIDE; SULFUR DIOXIDE; CADMIUM; PHOSPHORUS; FERTILIZERS; WASTE PRODUCT UTILIZATION; EMISSION; HYDROCHLORIC ACID

Citation Formats

Leckner, B., and Aamand, L.-E. Co-combustion of sludge with coal or wood. United States: N. p., 2004. Web. doi:10.2316/Journal.203.2004.3.203-3413.
Leckner, B., & Aamand, L.-E. Co-combustion of sludge with coal or wood. United States. doi:10.2316/Journal.203.2004.3.203-3413.
Leckner, B., and Aamand, L.-E. Thu . "Co-combustion of sludge with coal or wood". United States. doi:10.2316/Journal.203.2004.3.203-3413.
@article{osti_20490071,
title = {Co-combustion of sludge with coal or wood},
author = {Leckner, B. and Aamand, L.-E.},
abstractNote = {There are several options for co-combustion of biomass or waste with coal. In all cases the fuel properties are decisive for the success of the arrangement: contents of volatile matter and of potential emission precursors, such as sulphur, nitrogen, chlorine, and heavy metals. The content of alkali in the mineral substance of the fuel is important because of the danger of fouling and corrosion. Research activities at Chalmers University of Technology include several aspects of the related problems areas. An example is given concerning emissions from co-combustion in circulating fluidized beds with coal or wood as base fuels, and with sewage sludge as additional fuel. Two aspects of the properties of sludge are studied: emissions of nitrogen and sulphur oxides as well as of chlorine, because the contents of the precursors to these emissions are high. The possibility of utilizing the phosphorus in sludge as a fertilizer is also discussed. The results show that emissions can be kept below existing emission limits if the fraction of sludge is sufficiently small but the concentration of trace elements in the sludge ash prevents the sludge from being used as a fertilizer. 15 refs., 9 figs., 2 tabs.},
doi = {10.2316/Journal.203.2004.3.203-3413},
journal = {International Journal of Power and Energy Systems},
number = 3,
volume = 24,
place = {United States},
year = {Thu Jul 01 00:00:00 EDT 2004},
month = {Thu Jul 01 00:00:00 EDT 2004}
}
  • Co-combustion of sewage sludge can destabilize its combustion profile due to high volatility, which results in unstable flame. We carried out fuel reforming for sewage sludge by way of carbonization at pyrolysis temperature of 300-500 deg. C. Fuel characteristics of carbonized sludge at each temperature were analyzed. As carbonization temperature increased, fuel ratio increased, volatile content reduced, and atomic ratio relation of H/C and O/C was similar to that of lignite. The analysis result of FT-IR showed the decrease of aliphatic C-H bond and O-C bond in carbonization. In the analysis result of TG-DTG, the thermogravimetry reduction temperature of carbonizedmore » sludge (CS400) was proven to be higher than that of dried sludge, but lower than that of sub-bituminous coal. Hardgrove grindability index increased in proportion to fuel ratio increase, where the carbonized sludge value of 43-110 was similar or higher than the coal value of 49-63. As for ash deposits, slagging and fouling index were higher than that of coal. When carbonized sludge (CS400) and coal were co-combusted in 1-10% according to calorific value, slagging tendency was low in all conditions, and fouling tendency was medium or high according to the compositions of coal.« less
  • Biomass and sewage sludge are attracting increasing interest in power plant technology as a source of carbon-dioxide-neutral fuels. A new way to reduce the consumption of fossil fuels could be the co-combustion or co-gasification of coal and biomass or coal and sewage sludge. In both cases, pyrolysis is the first step in the technical process. In order to obtain detailed information about the pyrolysis of coal/biomass and coal/sewage sludge mixtures as well as unblended fuels, the Institut fuer Verfahrenstechnik and Dampfkesselwesen (IVD) at the University of Stuttgart has carried out investigations using an electrically heated entrained flow reactor. The testmore » runs provided information about fuel conversion efficiency, pyrolysis gas and tar yield, and composition of pyrolysis gas and tar. Besides gas and tar analysis investigations regarding the path of trace elements, like heavy metals, alkali, chlorine and nitrogen components, during the pyrolysis process varying different parameters have been carried out. The fuel nitrogen distribution between pyrolysis gas, tar, and char has been analyzed, as well as the ash composition, and, thus, the release of mineral components during pyrolysis.« less
  • The development of a thermophotovoltaic converter that uses combustion of wood powder as energy source has started with development of the combustion source. During the last few months, we have constructed and tested a feeding mechanism and a combustion chamber that seem very promising. We manage to keep a 10 kW flame steadily burning for several minutes at the time, generating a temperature exceeding 1400 K. The plans for continued development of this and other components of the converter are discussed in the paper. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
  • The combustible fraction of the municipal waste is mostly bio-derived. Energy recovery of the wastes that cannot be economically recycled is a key part of sustainable energy policy and waste management. Textile residues have high energy content. When burned alone in a packed bed system, however, their combustion efficiency is low due to the irregular propagation of the ignition front and the low burning rates. In order to achieve more efficient combustion of textile residues, a series of co-combustion tests were carried out for various mixture compositions and air flow rates in a packed bed combustor. The combustion performance ofmore » these materials was evaluated by using quantitative measures such as ignition rate, burning rate and equivalence ratio. Co-combustion of textile residues with cardboard for a textile fraction of up to 30% achieved satisfactorily high burning rate and low unburned carbon content in the bottom ash. The mixture was more resistant to convective cooling by air, which significantly expanded the range of air flow rate for combustion at high burning rates. In co-combustion with a material that has a very low ignition front speed such as waste wood, the propagation of the ignition front was governed by textile residues. Therefore, the co-combustion of textile residues can be better performed with a material having similar ignition front speeds, in which the two materials simultaneously burn at the ignition front. (author)« less
  • Researchers have demonstrated in a pilot-scale test a new technology for co-combusting sewage sludge with MSW in existing WTE combustors. The technology offers municipalities a cost-competitive alternative to land disposal and ocean-dumping of sludge. The key to the new technology is the selective enrichment of the combustion air with oxygen. Oxygen-enrichment enables the combustion of a higher ratio of sludge to MSW than is possible using conventional co-combustion methods. The sludge co-combustion process can be implemented without reducing the unit's MSW processing capacity, and it can provide an opportunity for an additional facility revenue stream.