The direct observation of alkali vapor species in biomass combustion and gasification

French, Richard J.; Dayton, David; Milne, T.A.

doi:10.2172/10115003

Cited by 16 publications

(29 citation statements)

References 20 publications

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“…Baseline Screening of Alkali Release at 11 ooa C in 20% 0 2 in Helium Alkali release and speciation during biomass combustion was investigated by examining the mass spectral results recorded during biomass combustion in a 20% 0 2 in helium atmosphere at 11 ooo C. As discussed in the literature [French, Dayton, and Milne, 1994;Dayton, French, and Milne, 1995], biomass combustion occurred in three distinct phases: the devolatilization phase, the char combustion phase, and the ash cooking phase.…”

Section: Resultsmentioning

confidence: 99%

“…Alkali metal vapor released during the combustion of 23 different feedstocks was investigated using a direct sampling, molecular beam mass spectrometer (MBMS) system [Evans and Milne, 1987a,b] in conjunction with a high temperature quartz-tube reactor which has been described in detail in the literature Milne, 1994 andMilne, 1995] This set of feedstocks can be divided into various classes of biomass identified as woody feedstocks, herbaceous feedstocks, grasses, agricultural residues, and waste feedstocks. It will become apparent that the varying nature of the feedstock compositions results in unique differences in terms of alkali metal release during combustion.…”

Section: Methodsmentioning

confidence: 99%

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Laboratory Measurements of Alkali Metal Containing Vapors Released during Biomass Combustion

Dayton

Milne

1996

Applications of Advanced Technology to Ash-Related Problems in Boilers

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Alkali metals, in particular potassium, have been implicated as key ingredients for enhancing fouling and stagging of heat transfer surfaces in power generating facilities that convert biomass to electricity. When biomass is used as a fuel in boilers, the deposits formed reduce efficiency, and in the worst case lead to unscheduled plant downtime. Blending biomass with other fuels is often used as a strategy to control fouling and stagging problems. Depending on the combustor, sorbents can be added to the fuel mixture to sequester alkali metals. Another possibility is to develop methods of hot gas cleanup that reduce the amount of alkali vapor to acceptable levels. These solutions to fouling and stagging, however, would greatly benefit from a detailed understanding of the mechanisms of alkali release during biomass combustion. Identifying these alkali vapor species and understanding how these vapors enhance deposit formation would also be beneficial.Our approach is to directly sample the hot gases liberated from the combustion of small biomass samples in a variable-temperature quartz-tube reactor employing a molecular beam mass spectrometer (MBMS) system. We have successfully used this experimental technique to identify alkali species released during the combustion of selected biomass feedstocks used in larger scale combustion facilities. Multiple combustion conditions have been investigated to target those conditions that minimize alkali metal release. The results of these laboratory studies indicate that initial feedstock composition has the most pronounced effect on alkali metal released during combustion. Four mechanisms of alkali metal release have been identified depending on the feedstock composition. Primary alkali metal release in the combustion of relatively low alkali metal containing woody feedstocks is through the vaporization or decomposition of alkali sulfates. Alkali metal chlorides are the primary alkali metal species released during combustion of herbaceous feedstocks, grasses, and straws with high alkali metal and chlorine contents. For feedstocks with high alkali metal and low chlorine content, alkali metal hydroxides are the most abundant alkali vapor released. If a high alkali content is coupled with high levels of fuel-bound nitrogen, the dominant form of alkali metal vapor is the alkali cyanate. In general, the chlorine content of biomass has been identified as an important parameter that facilitates alkali release.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Laboratory Measurements of Alkali Metal Containing Vapors Released during Biomass Combustion

Dayton

Milne

1996

Applications of Advanced Technology to Ash-Related Problems in Boilers

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“…The addition of minor amounts of alkali materials to cellulose feedstock has been shown to shift the final product from levuglucosan to glycolaldehyde [118][119][120]. These materials with counter ions in solution including oxalates, silicates, carbonates, phosphates, chlorides, and sulfates are important considerations even after pyrolysis [121][122][123]. The char and inorganic compounds have been reported to catalyze polymerization reactions during bio-oil storage, resulting in increases in viscosity and average molecular weights [120].…”

Section: Inorganic Compoundsmentioning

confidence: 99%

Catalytic Pyrolysis of Biomass and Polymer Wastes

et al. 2018

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Oil produced by the pyrolysis of biomass and co-pyrolysis of biomass with waste synthetic polymers has significant potential as a substitute for fossil fuels. However, the relatively poor properties found in pyrolysis oil—such as high oxygen content, low caloric value, and physicochemical instability—hampers its practical utilization as a commercial petroleum fuel replacement or additive. This review focuses on pyrolysis catalyst design, impact of using real waste feedstocks, catalyst deactivation and regeneration, and optimization of product distributions to support the production of high value-added products. Co-pyrolysis of two or more feedstock materials is shown to increase oil yield, caloric value, and aromatic hydrocarbon content. In addition, the co-pyrolysis of biomass and polymer waste can contribute to a reduction in production costs, expand waste disposal options, and reduce environmental impacts. Several promising options for catalytic pyrolysis to become industrially viable are also discussed.

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“…An analysis of ash compositions of six different types of biomass is shown in Table 1 [6]. Ash quantity and composition varies widely depending on the type of fuel with coal typically having higher ash content than biomass [7]. The major alkali metal found in coal ash is Na while the alkali metal in biomass ash is primarily K [7].…”

Section: Figure 1: Schematic Diagram Of the Air Blown Fluidized Bed Gmentioning

confidence: 99%

“…Different types of biomass contain different amounts of alkali and alkali earth metals such as sodium (Na), K, calcium (Ca), and magnesium (Mg) [6]. Historically the presence of alkali metals during gasification has been viewed as detrimental because they can cause fouling and damage to boiler tubes, turbine blades, and gas clean up equipment [7]. However, more recent research by Brown et al, Godavarty et al, suggest that alkali metals can increase process efficiency.…”

Section: Chapter 1 Ge Eral I Troductio Introductionmentioning

confidence: 99%

Investigations into the fate and behavior of selected inorganic compounds during biomass gasification

Meehan

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The direct observation of alkali vapor species in biomass combustion and gasification

Cited by 16 publications

References 20 publications

Laboratory Measurements of Alkali Metal Containing Vapors Released during Biomass Combustion

Laboratory Measurements of Alkali Metal Containing Vapors Released during Biomass Combustion

Catalytic Pyrolysis of Biomass and Polymer Wastes

Investigations into the fate and behavior of selected inorganic compounds during biomass gasification

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