Reducing superheater corrosion in wood-fired boilers

Henderson, Pamela; Andersson, Christer; Kassman, Håkan; Högberg, Jan

doi:10.1533/9781845694470.3.428

Cited by 17 publications

(21 citation statements)

References 4 publications

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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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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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“…Experience from Swedish power stations fired with 100% wood-based biofuels has shown that conventional superheater steels (low chromium ferritic steels) have to be replaced after about 20,000 hours if the steam temperature is 470 ∘ C or higher [48]. Henderson et al [49] have reported that most biomass fuels have high contents of alkali metals and chlorine, but they contain very little sulphur compared to fossil fuels. The alkali metal of major concern in wood is potassium.…”

Section: Corrosion and Environmental Effect In Biofuel Boilermentioning

confidence: 99%

Corrosion Problems in Incinerators and Biomass-Fuel-Fired Boilers

Mudgal

Singh

Prakash

2014

International Journal of Corrosion

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Incinerators are widely used to burn the municipal waste, biowaste, wood, straw, and biomedical waste. Combustion of these types of waste results in generation of chlorides of sodium and potassium which may attack the metallic part of the incinerator. In biofuel-fired boilers, similar type of highly corrosive environment is present. Attempt has been made to review the corrosion problems and their solutions as per the available literature.

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“…A study by Vattenfall and others [39] exposed a range of alloys in long-term superheater probe tests in two wood-fired boilers with and without sulfating additives. One test boiler was the 540°C (1004°F) steam CHP unit in Nyköping and the other was a 98MW, 480°C (896°F) steam, bark-fired boiler at Munksund, also in Sweden.…”

Section: Use Of Additives That Convert Chloride Ash Deposits To Sulfatesmentioning

confidence: 99%