A steady state model of gas-char reactions in a downdraft biomass gasifier

Giltrap, Donna; McKibbin, Robert; Barnes, G.R.G.

doi:10.1016/s0038-092x(03)00091-4

Cited by 158 publications

(106 citation statements)

References 2 publications

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“…The under or over-prediction of methane is quite a common problem for modellers; the product gas of fluidised bed gasifiers generally contains tar, which is not considered in equilibrium models, and much more hydrocarbons (especially methane) than predicted [38]. Also, the model done by Giltrap et al [39] which is a steady state model of a biomass downdraft gasifier, overpredicts CH 4 by a substantial amount. The low operating temperature (991 K) results in high CH 4 content and the CH 4 content decreases rapidly with temperature (at ~870 °C the model predicts virtually zero CH 4 ).…”

Section: Model Validationmentioning

confidence: 99%

The effect of air preheating in a biomass CFB gasifier using ASPEN Plus simulation

Doherty¹,

Reynolds²,

Kennedy³

2009

Biomass and Bioenergy

256

113

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Section: Model Validationmentioning

confidence: 99%

The effect of air preheating in a biomass CFB gasifier using ASPEN Plus simulation

Doherty¹,

Reynolds²,

Kennedy³

2009

Biomass and Bioenergy

256

113

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“…The gasification of coal and biomass (Gerum et al, 2008;Giltrap et al, 2003;Zainal et al, 2001;Porciúncula et al, 2009) is also a method to obtain hydrogen. However, the reaction products consist of a mixture of several gases other than hydrogen, such as methane, carbon dioxide and monoxide, sulfur and nitrogen compounds.…”

Section: Introductionmentioning

confidence: 99%

Production of hydrogen in the reaction between aluminum and water in the presence of NaOH and KOH

Porciúncula¹,

Marcílio²,

Tessaro³

et al. 2012

Braz. J. Chem. Eng.

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-The objective of this work is to investigate the production of hydrogen as an energy source by means of the reaction of aluminum with water. This reaction only occurs in the presence of NaOH and KOH, which behave as catalysts. The main advantages of using aluminum for indirect energy storage are: recyclability, nontoxicity and easiness to shape. Alkali concentrations varying from 1 to 3 mol . L -1 were applied to different metallic samples, either foil (0.02 mm thick) or plates (0.5 and 1 mm thick), and reaction temperatures between 295 and 345 K were tested. The results show that the reaction is strongly influenced by temperature, alkali concentration and metal shape. NaOH commonly promotes faster reactions and higher real yields than KOH.

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“…The gasification process can be broken down into several stages as it progresses from the entry to the exit of the gasifier: thermal decomposition, or pyrolysis, in which the volatiles are driven off producing pyrolysis vapors and tars; char oxidation, in which char remnants from the pyrolysis zone react with remaining oxygen and other gases and are gasified in both endothermic and exothermic reactions; and char reduction, in which remaining carbon content is consumed through primarily endothermic reactions (Buekens et al 1984;Gasification 2011). While the exact chemistry of this process is highly complex, there are several principal reactions vital to the formation of the syngas products that are well agreed upon and used commonly when mathematically modeling biomass gasification (Buekens et al 1984;Priyadarsan et al 2004;Giltrap et al 2003;Wang et al 1993 The gas produced with the downdraft, air-oxidation gasifier is 'low joule' or 'low energy' gas, relative to other methods of gasification or pure pyrolysis, and is best employed in a 'closely coupled' arrangement for immediate use to preserve efficiency (Beenackers et al 1984;Reed 1981). This arrangement would be ideally suited in preparing potentially harmful fuels, specifically poultry litter, for use in a cement kiln and, therefore, is the focus of the current study.…”

Section: Gasificationmentioning

confidence: 99%

Alternative Fuel for Portland Cement Processing

Schindler¹,

Duke²,

Burch³

et al. 2012

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The production of cement involves a combination of numerous raw materials, strictly monitored system processes, and temperatures on the order of 1500 °C. Immense quantities of fuel are required for the production of cement. Traditionally, energy from fossil fuels was solely relied upon for the production of cement. The overarching project objective is to evaluate the use of alternative fuels to lessen the dependence on non-renewable resources to produce portland cement. The key objective of using alternative fuels is to continue to produce high-quality cement while decreasing the use of non-renewable fuels and minimizing the impact on the environment.Burn characteristics and thermodynamic parameters were evaluated with a laboratory burn simulator under conditions that mimic those in the preheater where the fuels are brought into a cement plant. A drop-tube furnace and visualization method were developed that show potential for evaluating time-and space-resolved temperature distributions for fuel solid particles and liquid droplets undergoing combustion in various combustion atmospheres. Downdraft gasification has been explored as a means to extract chemical energy from poultry litter while limiting the throughput of potentially deleterious components with regards to use in firing a cement kiln. Results have shown that the clinkering is temperature independent, at least within the controllable temperature range. Limestone also had only a slight effect on the fusion when used to coat the pellets. However, limestone addition did display some promise in regards to chlorine capture, as ash analyses showed chlorine concentrations of more than four times greater in the limestone infused ash as compared to raw poultry litter.A reliable and convenient sampling procedure was developed to estimate the combustion quality of broiler litter that is the best compromise between convenience and reliability by means of statistical analysis.Multi-day trial burns were conducted at a full-scale cement plant with alternative fuels to examine their compatibility with the cement production process. Construction and demolition waste, woodchips, and soybean seeds were used as alternative fuels at a full-scale cement production facility. These fuels were co-fired with coal and waste plastics. The alternative fuels used in this trial accounted for 5 to 16 % of the total energy consumed during these burns. The overall performance of the portland cement produced during the various trial burns performed for practical purposes very similar to the cement produced during the control burn. The cement plant was successful in implementing alternative fuels to produce a consistent, high-quality product that increased cement performance while reducing the environmental footprint of the plant. The utilization of construction and demolition waste, woodchips and soybean seeds proved to be viable replacements for traditional fuels. The future use of these fuels depends on local availability, associated costs, and compatibility with a facility's p...

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A steady state model of gas-char reactions in a downdraft biomass gasifier

Cited by 158 publications

References 2 publications

The effect of air preheating in a biomass CFB gasifier using ASPEN Plus simulation

The effect of air preheating in a biomass CFB gasifier using ASPEN Plus simulation

Production of hydrogen in the reaction between aluminum and water in the presence of NaOH and KOH

Alternative Fuel for Portland Cement Processing

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