Post-Harvest Processing Methods for Reduction of Silica and Alkali Metals in Wheat Straw

Thompson, David N.; Shaw, P. G.; Lacey, Jeffrey A.

doi:10.1385/abab:105:1-3:205

Cited by 20 publications

(11 citation statements)

References 3 publications

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“…Table 3 shows the full set of leaching results using water and dilute-acid at temperatures between 25 and 90ºC at 98 wt%, 95 wt% and 90 wt% aqueous. These results are comparable to those observed in previous work using various feedstocks including switchgrass, corn stover and bark [12][13][14][15][16]36], with respect to the effects of conditions on ash removal and the order-of-magnitude of removal for various ash species. However, studies under similar conditions using corn stover are lacking, as the majority of dilute-acid leaching work at relatively mild conditions has focused on woody feedstocks for ash removal.…”

Section: -Effect Of Dilute-acid Leaching On the Ash Composition Of Multi-pass Corn Stoversupporting

confidence: 89%

“…In addition to inhibiting pyrolysis, potassium and silica may contribute to slag formation during combustion by forming K2SiO4, a eutectic with a low melting point. This low-melting point may lead to glass formation that will cause slagging, and may trap corrosives such as chloride on a reactor surface [36,37].…”

Section: -Ash Composition Of Untreated Multi-pass Corn Stovermentioning

confidence: 99%

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Performance assessment of dilute-acid leaching to improve corn stover quality for thermochemical conversion

Aston

Thompson

Westover

2016

Fuel

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Lignocellulosic biomass is a sustainable energy source that can help meet the increasing demand for biofuels in the United States. However, the quality and availability of such feedstocks greatly affect their suitability for downstream conversion. This work reports the effects of dilute-acid leaching at various aqueous loadings, temperatures and catalyst loadings (sulfuric acid) on the quality of a traditional biochemical feedstock, corn stover, as a potential feedstock for thermochemical conversions.At 95 wt% aqueous, dilute-acid leaching was observed to effectively remove 97.3% of the alkali metals and alkaline earth metals that can negatively affect degradation pathways during pyrolysis and result in greater yield of non-condensable gases. In addition, up to 98.4% of the chlorine and 88.8% of the phosphorus, which can cause equipment corrosion and foul upgrading catalysts, respectively, were removed. At 25°C in the absence of the acid catalyst, only 6.8% of the alkali metals and alkaline earth metals were removed; however, 88.0% of chloride was still removed.The ratio of alkaline/acidic ash species has been suggested to proportionately relate to slagging in combustion applications. The initial alkali/acid ratio of the ash species present in the untreated corn stover was 0.38 (significant slagging risk). At 95 wt% aqueous, this ratio was decreased to 0.18 (moderate slagging risk) at 0 wt% catalyst and 90°C, and was decreased to 0.07, 0.08 and 0.06 at 0.5 wt% catalyst at 25°C, 50°C and 90°C, respectively (low slagging risk). Increasing the catalyst loading to 1.0% slightly decreased the measured alkali/acid ratio of remaining ash.The results presented here show that a water wash or a dilute-acid preprocessing step can improve corn stover quality for pyrolysis, hydrothermal liquefaction and combustion.

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Section: -Effect Of Dilute-acid Leaching On the Ash Composition Of Multi-pass Corn Stoversupporting

confidence: 89%

Section: -Ash Composition Of Untreated Multi-pass Corn Stovermentioning

confidence: 99%

Performance assessment of dilute-acid leaching to improve corn stover quality for thermochemical conversion

Aston

Thompson

Westover

2016

Fuel

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“…Ӧhman et al (2000) revealed that the alkali metals and their related compounds can form furnace slag or agglomeration samples in the forms of gaseous phases and fly ash particles, which further causes the fouling, slagging, and corrosion problems on the surfaces of thermo-chemical equipment. Additionally, Thompson et al (2003) went into some amount of detail discussing the importance of speciation and ratios of ash species as it pertained to ash slagging by alkali metals. Thus, based on the above analysis, CCA is inferred to be more likely to cause the fouling, slagging, and corrosion because it contained a higher content of alkali metals than RHA and RSA, and the damage on the heat exchanging surface of thermo-chemical equipment caused by CCA could be much greater than that caused by other ashes.…”

Section: Chemical Composition Analysismentioning

confidence: 99%

The Influence of Ashing Temperature on Ash Fouling and Slagging Characteristics during Combustion of Biomass Fuels

Yao

Yan

et al. 2017

BioResources

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Three typical biomass fuels-rice husk, rice straw, and corn cobs-were combusted to understand the effects of ashing temperature on ash fouling and slagging characteristics. The ashes generated from combustion at 600 °C and 815 °C were characterized thoroughly with regard to their chemical composition. The systematic slagging/fouling indices of biomass were used to study the effects of ashing temperature on ash fouling and slagging propensities. The results showed that ashing temperature had a remarkable influence on ash composition, particle size distribution, ash morphology, ash fusibility, and thermal properties. Increased ashing temperature resulted in the expansion of ash particles together with the volatilization of alkali metals in the form of inorganic salts. Morphology analysis indicated that high ashing temperatures promoted biomass ash slagging. Ash fusion points increased at elevated ashing temperatures, while the ash content decreased. As a result of the volatilization and decomposition of biomass ash, a four-step mechanism of weight loss was clearly identified by thermal analysis. All prepared biomass ashes resulted in slagging and fouling problems at different levels during the thermochemical conversion of biomass.

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“…High concentrations of these inorganic fractions, despite having a catalytic role during thermochemical conversion, are problematic due to their low melting points [33,34]. Biomass washing using diluted acid has been recommended [35] as one of the possible solutions to leach out alkali minerals. This process may support blending and co-firing biomass with coal by supplying a catalyzing co-ingredient while minimizing ash agglomeration which is likely occur when cellulosic biomass is fired alone.…”

Section: Biochar Moisture and Volatile Solids Contents As Influenced mentioning

confidence: 99%

Characterization of Biochar from Switchgrass Carbonization

et al. 2014

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Switchgrass is a high yielding, low-input intensive, native perennial grass that has been promoted as a major second-generation bioenergy crop. Raw switchgrass is not a readily acceptable feedstock in existing power plants that were built to accommodate coal and peat. The objective of this research was to elucidate some of the characteristics of switchgrass biochar produced via carbonization and to explore its potential use as a solid fuel. Samples were carbonized in a batch reactor under reactor temperatures of 300, 350 and 400 °C for 1, 2 and 3 h residence times. Biochar mass yield and volatile solids decreased from 82.6% to 35.2% and from 72.1% to 43.9%, respectively, by increasing carbonization temperatures from 300 °C to 400 °C and residence times from 1 h to 3 h. Conversely, biochar heating value (HV) and fixed carbon content increased from 17.6 MJ kg and from 22.5% to 44.9%, respectively, under the same conditions. A biomass discoloration index (BDI) was created to quantify changes in biochar colors as affected by the two tested parameters. The maximum BDI of 77% was achieved at a carbonization temperature of 400 °C and a residence time of 3 h. The use of this index could be expanded to quantify biochar characteristics as affected by thermochemical treatments. Carbonized biochar could be considered a high quality solid fuel based on its energy content. OPEN ACCESSEnergies 2014, 7 549

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Post-Harvest Processing Methods for Reduction of Silica and Alkali Metals in Wheat Straw

Cited by 20 publications

References 3 publications

Performance assessment of dilute-acid leaching to improve corn stover quality for thermochemical conversion

Performance assessment of dilute-acid leaching to improve corn stover quality for thermochemical conversion

The Influence of Ashing Temperature on Ash Fouling and Slagging Characteristics during Combustion of Biomass Fuels

Characterization of Biochar from Switchgrass Carbonization

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