Two strategies to reduce gaseous KCl and chlorine in deposits during biomass combustion — injection of ammonium sulphate and co-combustion with peat

Kassman, Håkan; Pettersson, Jesper; Steenari, Britt‐Marie; Åmand, Lars-Erik

doi:10.1016/j.fuproc.2011.06.025

Cited by 134 publications

(111 citation statements)

References 27 publications

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“…S/Cl reflects the excess of sulphur in relation to chlorine and relates to the competition between Cl and S in reacting with K. The risk of corrosion is often considered great at a molar ratio S/Cl less than 2.0 and low at an S/Cl ratio above 4.0. The chlorine content in the deposits could also be a measure of the risk of corrosion and no chlorine was found when sulphur was available in the form of SO 3 instead of SO 2 at a molar ratio S/Cl of 1.0 in [10] and 2.1 in [13]. Thus, the oxidation state of sulphur (i.e.…”

Section: Methodsmentioning

confidence: 99%

“…This boiler is mainly used for research purposes and offers the possibility to perform measurement campaigns in a full scale boiler, while maintaining control over important operation parameters such as load, air supply and composition of the fuel mix. The boiler has been described earlier in several publications including [8,10,13,24,25]. The combustion chamber has a cross-section of approximately 2.25 m 2 and a height of 13.6 m. Fuel is fed from a fuel chute (located at the front of the boiler) to the lower part of the combustion chamber.…”

Section: Research Boiler and Operating Conditionsmentioning

confidence: 99%

“…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%

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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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Section: Methodsmentioning

confidence: 99%

Section: Research Boiler and Operating Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Kassman

Normann

Åmand

2013

Combustion and Flame

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“…Burning biomass and waste results in a more corrosive fireside environment, e.g., it contains more alkali chloride than fossil fuels [1][2][3][4][5][6][7][8][9]. Consequently, the corrosion of critical components in a power boiler, e.g., the superheater tubes, is a major challenge.…”

Section: Introductionmentioning

confidence: 99%

Cyclic Corrosion and Chlorination of an FeCrAl Alloy in the Presence of KCl

et al. 2015

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The KCl-induced corrosion of the FeCrAl alloy Kanthal Ò APMT in an O 2 ? N 2 ? H 2 O environment was studied at 600°C. The samples were pre-oxidized prior to exposure in order to investigate the protective nature of alumina scales in the present environment. The microstructure and composition of the corroded surface was investigated in detail. Corrosion started at flaws in the pre-formed a-alumina scales, i.e. a-alumina was protective in itself. Consequently, KCl-induced corrosion started locally and, subsequently, spread laterally. An electrochemical mechanism is proposed here by which a transition metal chloride forms in the alloy and K 2 CrO 4 forms at the scale/gas interface. Scale de-cohesion is attributed to the formation of a sub-scale transition metal chloride.

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“…This is due to an aggressive environment that contains e.g. alkali salts and water combined with metal temperatures up to *550°C [1][2][3][4][5][6][7][8][9]. At such relatively low temperatures, chromia-forming alloys, such as FeCr and FeCrNi steels, are currently being used [10].…”

Section: Introductionmentioning

confidence: 99%

KCl-Induced Corrosion of an FeCrAl Alloy at 600 °C in O2 + H2O Environment: The Effect of Pre-oxidation

et al. 2014

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The present study investigates the influence of H 2 O and KCl on the high temperature corrosion of an FeCrAl alloy at 600°C. Polished samples were exposed to O 2 or O 2 ? H 2 O and to O 2 ? H 2 O with KCl applied. The samples were investigated using SEM/EDX, XRD, IC, AES and SIMS. It was found that KCl accelerates corrosion and that a rapidly growing iron-rich oxide forms with time. Chromate formation is shown to initiate the formation of a non-protective oxide scale. Pre-oxidising the alloy before exposure in the presence of KCl had a strongly beneficial effect on the corrosion.

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Two strategies to reduce gaseous KCl and chlorine in deposits during biomass combustion — injection of ammonium sulphate and co-combustion with peat

Cited by 134 publications

References 27 publications

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

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

Cyclic Corrosion and Chlorination of an FeCrAl Alloy in the Presence of KCl

KCl-Induced Corrosion of an FeCrAl Alloy at 600 °C in O2 + H2O Environment: The Effect of Pre-oxidation

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