Sewage sludge as a deposit inhibitor when co-fired with high potassium fuels

Elled, Anna-Lena; Davidsson, Kent; Åmand, Lars-Erik

doi:10.1016/j.biombioe.2010.05.003

Cited by 70 publications

(80 citation statements)

References 24 publications

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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%

“…As kaolinite and other aluminosilicates are abundantly present in most coals [87], it is likely that an alkali absorption mechanism is active during the co-combustion. Moreover, some biofuels such as sewage sludge contain different aluminum silicates, silica and alumina, which could increase biomass ashes sintering temperatures and reduce their fouling deposition in various studies [77][78][79][80].…”

Section: Co-firing Biomass With Low Fouling-tendency Fuelsmentioning

confidence: 99%

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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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Section: Technologies For Reducing Ash Deposition and Corrosionmentioning

confidence: 99%

Section: Co-firing Biomass With Low Fouling-tendency Fuelsmentioning

confidence: 99%

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

et al. 2012

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“…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%

“…The light, which arrives at the receiver, is analysed by a spectrometer. IACM has been used in the present boiler in several previous projects related to alkali chloride issues in which it is described in more detail [8,10,12,13,24,25,30]. IACM is a part of the so-called ChlorOut concept.…”

Section: Measurement Equipmentmentioning

confidence: 99%

“…Sulphur may be introduced either by co-combustion or as an additive, such as elemental sulphur and ammonium sulphate. 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 ).…”

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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A calculation method of biomass slagging rate based on crystallization theory

Niu

Zhu

Tan

et al. 2013

Asia-Pacific J Chem Eng

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Aiming to the vacant research on slagging rate calculation of biomass, a method based on crystallization theory is proposed here. First, KCl-K 2 SO 4 -Na 2 SO 4 ternary eutectic system, as main inducing factor of biomass slagging, is verified by slagging sample analysis, ternary eutectic experiment, and equilibrium calculation of FACTSAGE. Second, we assume that flue gas was solvent; the KCl-K 2 SO 4 -Na 2 SO 4 ternary eutectic system and the refractory components were two solutes supersaturated in the solution. The slagging process is approximated as the combined effect of nucleation and solidification of the KCl-K 2 SO 4 -Na 2 SO 4 eutectic system and the conglutination of the refractory components. Third, on the basis of nucleation rate equation, a formula for the slagging rate calculation is developed as J = k(Δc max ) m , where k defined as slagging constant is the empirical function of fly ash concentration and flue gas velocity, △c max is the concentration difference of KCl + K 3 Na (SO 4 ) 2 in fly ash up and downstream of heating surfaces, and m is defined as slagging order, which is an empirical parameter dependent on the concentrations of KCl and K 3 Na(SO 4 ) 2 . Meanwhile, an example is given on the calculation of m. However, additional experiments are required in order to improve the formulation of functions k and m.

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Sewage sludge as a deposit inhibitor when co-fired with high potassium fuels

Cited by 70 publications

References 24 publications

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

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

A calculation method of biomass slagging rate based on crystallization theory

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