Measures to reduce chlorine in deposits: Application in a large-scale circulating fluidised bed boiler firing biomass

Kassman, Håkan; Broström, Markus; Berg, Mats; Åmand, Lars-Erik

doi:10.1016/j.fuel.2010.12.005

Cited by 87 publications

(55 citation statements)

References 45 publications

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“…Major elements were found in larger amounts using SEM-EDS, which is possibly derived from the precision and accuracy of the techniques. Infrared absorption spectroscopy is used primarily to identify organic compounds, especially gases [3,4,19,22]. FTIR is not typically used for the determination of inorganic compounds, as these components vibrate at wavenumbers less than 400 cm −1…”

Section: Comparison Between Elemental Techniquesmentioning

confidence: 99%

“…[6,7,9,12,[14][15][16][17][18]. Many researches have focused on minimizing or removing these problems using methods such as co-firing with other types of fuel, such as different coals [9][10][11]13,[19][20][21] or blends of various biomass species [14,22], and the use of additives such as phosphoric acid [3], ammonium sulfate [19], kaolin [14], halloysite [23], titanium oxide [24], Ca-based additives [25] and others [26][27][28]. Therefore, the knowledge on the composition of the ash and fouling material is crucial to understand the mechanisms behind fouling formation and to provide a method to combat it.…”

Section: Introductionmentioning

confidence: 99%

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A Comparative Study of Fouling and Bottom Ash from Woody Biomass Combustion in a Fixed-Bed Small-Scale Boiler and Evaluation of the Analytical Techniques Used

et al. 2015

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Abstract:In this work, fouling and bottom ash were collected from a low-power boiler after wood pellet combustion and studied using several analytical techniques to characterize and compare samples from different areas and determine the suitability of the analysis techniques employed. TGA results indicated that the fouling contained a high amount of organic matter (70%). The XRF and SEM-EDS measurements revealed that Ca and K are the main inorganic elements and exhibit clear tendency in the content of Cl that is negligible in the bottom ash and increased as it penetrated into the innermost layers of the fouling. Calcite, magnesia and silica appeared as the major crystalline phases in all the samples. However, the bottom ash was primarily comprised of calcium silicates. The KCl behaved identically to the Cl, preferably appeared in the adhered fouling samples. This salt, which has a low melting point, condenses upon contact with the low temperature tube and played a crucial role in the early stages of fouling formation. XRD was the most useful technique applied, which provided a semi-quantitative determination of the crystalline phases. FTIR was proven to be inadequate for this type of sample. The XRF and SEM-EDS, techniques yield similar results despite being entirely different.

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Section: Comparison Between Elemental Techniquesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Comparative Study of Fouling and Bottom Ash from Woody Biomass Combustion in a Fixed-Bed Small-Scale Boiler and Evaluation of the Analytical Techniques Used

et al. 2015

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“…Various technologies for reducing ash deposition as well as corrosion have been studied. These include: (1) [10,20,41,[60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76]; (2) co-firing bio-fuels with low fouling-tendency fuels [8,55,[77][78][79][80][81]; (3) pretreatment of the feedstock to reduce the alkali metals [82,83], and (4) modification of the boiler (e.g., modification of the re-heater and super-heater in order to allow for larger spacing, more soot-blowing and a decrease in the live steam temperature to less than 500 °C, etc.) [60].…”

Section: Technologies For Reducing Ash Deposition and Corrosionmentioning

confidence: 99%

“…Theoretically, a minimum value of 0.5 of S fg /Cl would be required to complete the sulphation of all alkali chlorides, but the least S fg /Cl could be reduced with the amounts of available aluminosilicates in fuel-ash. Furthermore, Kassman et al [74][75][76] applied ammonium sulphate as a combustion additive in full-scale biomass combustion. They found that gaseous SO 3 decomposed from (NH 4 ) 2 SO 4 during combustion was more efficient than gaseous SO 2 to react with KCl, even at a low S/Cl molar ratio (~1.0).…”

Section: Addition Of Combustion Additivesmentioning

confidence: 99%

Ash Deposition in Biomass Combustion or Co-Firing for Power/Heat Generation

et al. 2012

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This paper presents a concise overview of ash deposition in combustion or co-firing of biomass (woody biomass, agricultural residues, peat, etc.) with other fuels for power/heat generation. In this article, the following five research aspects on biomass combustion ash deposition are reviewed and discussed: influence of biomass fuel characteristics, deposit-related challenges, ash deposition monitoring and analysis of ash deposits, mechanisms and chemistry of fly ash deposition, and key technologies for reducing ash deposition and corrosion in biomass-involved combustion.

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“…Coal, peat and municipal sewage sludge (MSS) are among the sulphur-containing fuels suitable for co-combustion with biomass [6][7][8][9][10]. In [7,[10][11][12][13] results are presented from experiments when using elemental sulphur (S) and/or ammonium sulphate (AS, (NH 4 ) 2 SO 4 ). These additives were evaluated in [13] for sulphation of gaseous KCl.…”

Section: Introductionmentioning

confidence: 99%

The effect of oxygen and volatile combustibles on the sulphation of gaseous KCl

Kassman

Normann

Åmand

2013

Combustion and Flame

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a b s t r a c tSulphur/sulphate containing additives, such as elemental sulphur (S) and ammonium sulphate (NH 4 ) 2 SO 4 ), can be used for sulphation of KCl during biomass combustion. These additives convert KCl to an alkali sulphate and a more efficient sulphation is normally achieved for ammonium sulphate compared to sulphur. The presence of SO 3 is thus of greater importance than that of SO 2 . Oxygen and volatile combustibles could also have an effect on the sulphation of gaseous KCl. This paper is based on results obtained during co-combustion of wood chips and straw pellets in a 12 MW circulating fluidised bed (CFB) boiler. Ammonium sulphate was injected at three positions in the boiler i.e. in the upper part of the combustion chamber, in the cyclone inlet, and in the cyclone. The sulphation of KCl was investigated at three air excess ratios (k = 1.1, 1.2 and 1.4). Several measurement tools were applied including IACM (on-line measurements of gaseous alkali chlorides), deposit probes (chemical composition in deposits collected) and gas analysis. The position for injection of ammonium sulphate had a great impact on the sulphation efficiency for gaseous KCl at the different air excess ratios. There was also an effect of oxygen on the sulphation efficiency when injecting ammonium sulphate in the cyclone. Less gaseous KCl was reduced during air excess ratio k = 1.1 compared to the higher air excess ratios. The optimal position and conditions for injection of ammonium sulphate were identified by measuring KCl with IACM. A correlation was observed between the sulphation of gaseous KCl and reduced chlorine content in the deposits. The experimental observations were evaluated using a detailed reaction mechanism. It was used to model the effect of volatile combustibles on the sulphation of gaseous KCl by SO 3 . The calculations supported the proposition that the presence of combustibles at the position of SO 3 injection (i.e. AS) causes reduction of SO 3 to SO 2 .

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Measures to reduce chlorine in deposits: Application in a large-scale circulating fluidised bed boiler firing biomass

Cited by 87 publications

References 45 publications

A Comparative Study of Fouling and Bottom Ash from Woody Biomass Combustion in a Fixed-Bed Small-Scale Boiler and Evaluation of the Analytical Techniques Used

A Comparative Study of Fouling and Bottom Ash from Woody Biomass Combustion in a Fixed-Bed Small-Scale Boiler and Evaluation of the Analytical Techniques Used

Ash Deposition in Biomass Combustion or Co-Firing for Power/Heat Generation

The effect of oxygen and volatile combustibles on the sulphation of gaseous KCl

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