In the context of low-carbon and circular economy, current work aimed to develop a method for the production of biofuels rich in hydrogen, using exclusively waste materials as energy sources or beneficial additives. Selected materials... more
In the context of low-carbon and circular economy, current work aimed to develop a method for the production of biofuels rich in hydrogen, using exclusively waste materials as energy sources or beneficial additives. Selected materials were forest and agricultural wastes as feedstocks, as well as demolition wastes from construction activities and red mud waste from aluminum industry as a novel CO2 sorbent and catalyst, respectively. The experiments were carried out in a fixed bed gasification system under steam atmosphere and a thermogravimetric-mass spectrometric (TG-MS) unit. The effects of temperature, sorbent/fuel ratio and catalyst loading on final conversion, product gas composition and heating value, hydrogen yield and energy recovery were examined and optimum conditions were determined. At 750°C, Ca/C=1 and red mud loading 20-30% wt, the amount of CO2 captured by the building demolition waste sorbent was 76.5-81.2%, the molar fraction of hydrogen in the product gas 74.8-77.1% mol (raised up to 77% as compared to reaction without sorbent or catalyst), the hydrogen yield 1.31-2.08 m3/kg, the higher heating value of gas 13.4-13.6 MJ/m3 and fuel conversion 71-100%. For same proportions of sorbent and catalyst at 850°C, 64.3-77.8% of CO2 was captured, the hydrogen concentration in product gas was 76.6-79.8% mol and the yield 1.5-2.35 m3/kg, the higher heating value of gas 12.4-13.2 MJ/m3, while conversion of organic matter was 88.1-100%.
LIU Chunzhao N a t i o n a l K e y L a b o r a t o r y o f Biochemical Engineering, Chinese Academy of Sciences, China
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... of Crete, during both fixed and fluidized bed combustion and their environmental impact upon disposal. ... the most secure basis for decision making, if used in conjunction with pilot plant testing. ... with the use of fertilizers in... more
... of Crete, during both fixed and fluidized bed combustion and their environmental impact upon disposal. ... the most secure basis for decision making, if used in conjunction with pilot plant testing. ... with the use of fertilizers in agriculture and has been found in wood ash from other ...
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In the context of exploitation of urban wastes for recycling, valorification, or energy production, present study aimed at investigating the environmental impact and potential uses of ashes produced from co-combustion of such wastes with... more
In the context of exploitation of urban wastes for recycling, valorification, or energy production, present study aimed at investigating the environmental impact and potential uses of ashes produced from co-combustion of such wastes with an olive byproduct in a fluidized bed unit. Bottom and fly ashes were characterized by physical, chemical and mineralogical analyses. Column leaching tests, simulating field conditions, were conducted and key parameters of soil/ash leachate solutions were measured. The results showed that fly and bottom ashes were alkaline, with low electrical conductivity and cation exchange capacity and enriched in Ca, Si, P, K, Mn, Zn, Sr and Cr. The principal mineral phases identified were calcite, quartz, fairchildite, hydroxyapatite and whitlockite magnesian. The elements with higher mobility leached through a soil of quarzitic nature were Na, Mg, Cr and Sr. However, none of the measured values exceeded legislation limits for land disposal. All ashes could be used as secondary building materials, liming agents or soil ameliorants in blends with other byproducts.
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Embodiment of biomass combustion technologies in the Cretan energy system will play an important role and will contribute to the local development. The main biomass fuels of Crete are the agricultural residues olive kernel and olive tree... more
Embodiment of biomass combustion technologies in the Cretan energy system will play an important role and will contribute to the local development. The main biomass fuels of Crete are the agricultural residues olive kernel and olive tree wood. Future applications of these biofuels may create, among others, operational problems related to ash effects. In this regard, the thermal behavior of the ashes during lab-scale fluidized bed combustion tests was examined, in terms of slagging/fouling and agglomeration of bed material. Control methodologies for mitigating ash problems were applied, such as leaching the raw fuels with water and using different mineral additives during combustion. The ashes and the bed material were characterized in terms of mineralogical, chemical and morphological analyses and the slagging/fouling and agglomeration propensities were determined. The results showed that fly ashes were rich in Ca, Si and Fe minerals and contained substantial amounts of alkali, falling within the range of "certain or probable slagging/fouling". Leaching of the raw fuels with water resulted in a significant reduction of the problematic elements K, Na, Cl and S in the fly ashes. The use of fuel additives decreased the concentrations of alkali and iron minerals in the fly ashes. With clay additives calcium compounds were enriched in the bottom ash, while with carbonate additives they were enriched in the fly ash. Fuel additives or water leaching reduced the slagging/fouling potential due to alkali. Under the conditions of the combustion tests, no signs of ash deposition or bed agglomeration were noticed.
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Lignite plays a dominant role for energy production in Greece, covering over 30% of the demand for electricity generation. Increased energy demand requires, additionally to alternative energy sourc...
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ABSTRACT Cake residues derived from seed crops after oil extraction could be used as fuel to cover a part of heat or power demands of such a procedure. These can be accomplished effectively via thermochemical processing, such as... more
ABSTRACT Cake residues derived from seed crops after oil extraction could be used as fuel to cover a part of heat or power demands of such a procedure. These can be accomplished effectively via thermochemical processing, such as gasification. Contrary to the gasification of woody materials which has been investigated extensively, there is fewer data on gasification applications of residues from newly introduced oil crops after their oil extraction. In this work, seed cake residues of sunflower and Jatropha were gasified. Air gasification tests of these cakes were conducted in a 100 kWth, atmospheric, circulating fluidized bed (CFB). The effect of temperature and bed material on the composition of product gas and tar formation from was compared to willow. Experimental results show that the Carbon Conversion Efficiency (CCE) and cold gas efficiency (CGE) were higher in the case of cakes, especially for sunflower. On the other hand, tar levels were also higher compared to willow. Pilot scale tests were carried out using either olivine and quartz as bed materials. The examination of bed material particles revealed that potassium and calcium derived from the ash accumulated inside the olivine structure, which was not apparent in the case of silica sand where a calcium external layer was observed. Since the biomass ash content and speciation affects the operability of the gasifier, after the end of each trial, fly ash samples from the removal system of particulates, as well as bed ash samples were collected. Various characterization techniques such as X-ray Fluorescence (XRF), Thermogravimetric Analysis (TGA), Ash Fusion Temperature (AFT) and Scanning Electron Microscopy (SEM)/Energy Dispersive X-ray Spectroscopy (EDS) were performed to determine the physicochemical properties of each fuel ash in detail, as well as the fate of inorganic elements initially contained in it.
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A one-dimensional, steady-state model for an entrained flow coal gasifier is developed, incorporating thermogravimetric analysis data on a bituminous coal. The model is based on mass and energy balances, heterogeneous reaction rates and... more
A one-dimensional, steady-state model for an entrained flow coal gasifier is developed, incorporating thermogravimetric analysis data on a bituminous coal. The model is based on mass and energy balances, heterogeneous reaction rates and homogeneous gas-phase equilibria. The resulting set of non-linear mixed ordinary differential-implicit algebraic equations was solved by a modified Euler method in conjunction with a non-linear algebraic equation solver. Temperature, reaction rate and composition profiles in a tubular gasifier were predicted at 0.1 and 2 MPa operating pressures, at constant feed rates. Realistic conversions of carbon could not be predicted if the devolatilization reaction and the heterogeneous surface reactions between the coal and oxygen and steam were assumed to proceed sequentially. The model showed that as the combustion was much faster than the gasification, temperature maxima for both the particles and the gas occurred at the point of final consumption of oxygen. The gasification proceeded only in the absence of oxygen.
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The entrained flow gasification model developed in Part 1 was used for parametric studies to provide a better understanding of the reactor performance in terms of coal conversion, product gas composition, calorific value and temperature... more
The entrained flow gasification model developed in Part 1 was used for parametric studies to provide a better understanding of the reactor performance in terms of coal conversion, product gas composition, calorific value and temperature profiles throughout the reactor under various operating conditions (feed flow rate, particle size and system pressure). The results suggest that the critical parameters in gasification
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The main agricultural residues of Crete are considered to be of premium importance for local energy production through combustion. The thermal behaviour of ashes was predicted by chemical, mineralogical, microscopical and thermal... more
The main agricultural residues of Crete are considered to be of premium importance for local energy production through combustion. The thermal behaviour of ashes was predicted by chemical, mineralogical, microscopical and thermal analyses, while the removal of troublesome elements to reduce slagging and fouling in furnaces was tested by leaching these biomass fuels with water. Deposition tendencies were predicted through
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Research Interests: Engineering, Chemistry, Coal, Fouling, Quartz, and 6 moreFly Ash, CHEMICAL SCIENCES, Lignite, Energy and Fuels, Ash, and anhydrite
Research Interests: Chemical Engineering, Environmental Science, Chemistry, Fluorescence Spectroscopy, Biomass, and 15 moreLeaching, Coal, Alternative Fuels, Management Strategies, Environmental Impact, Differential Thermal Analysis, Cement Industry, Engineering Chemical, Bituminous Coal, Coal Industry, Environment, Biomass Ashes, Coal ash, Ash, and Leaching Test
The carbon dioxide gasification performance of low-quality lignite-agroindustrial/forest waste blends was investigated in terms of reactivity, conversion, cold gas efficiency, product gas composition and heating value. The experiments... more
The carbon dioxide gasification performance of low-quality lignite-agroindustrial/forest waste blends was investigated in terms of reactivity, conversion, cold gas efficiency, product gas composition and heating value. The experiments were conducted in a fixed bed unit and a thermal analysis mass spectrometer system. Raw materials, chars, liquids and gases were quantitatively analyzed and their energy content was determined. Synergetic effects and the role of minerals were examined, the latter through chemical and fusibility analyses of the ashes. Ahlada lignite (AL) was of low quality, with a calorific value of 8.9 MJ/kg. The biomass materials, ginning cotton waste (GCW) and pine needles (PN) had calorific values 16.6 MJ/kg and 20.1 MJ/kg, respectively. The slagging/fouling propensity of AL ash was low, whereas that of biomass wastes was medium to high. Thermal treatment of the samples and their blends prior to gasification produced upgraded fuels. A Boudourd reaction occurred abov...
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Different biomass waste materials were gasified by steam up to 850 °C, employing a fixed bed reactor and a thermal analysis-mass spectrometer unit. Raw fuels and biochars were characterized, while bio-oil, pyrolysis gas and syngas were... more
Different biomass waste materials were gasified by steam up to 850 °C, employing a fixed bed reactor and a thermal analysis-mass spectrometer unit. Raw fuels and biochars were characterized, while bio-oil, pyrolysis gas and syngas were quantitatively analyzed. Gasification efficiency and energy potential of all solid, liquid and gaseous products were determined. The higher heating value of biochar particles, bio-oil and pyrolysis gas ranged between 16-28 MJ/kg, 21.4-33.4 MJ/kg and 10.2-13.5 MJ/m3, respectively. Organic matter was almost completely converted to syngas and lower quantities of CO2, CH4 and hydrocarbons upon steam gasification, with H2 yield reaching values up to 60%. The higher heating value of syngas produced varied between 9.8 MJ/m3and 11.4 MJ/m3.
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The combustion and carbon dioxide gasification behavior of lignite/corn cobs mixtures through thermal analysis experiments was investigated. A simple and accurate model was developed to provide and compare the kinetics of these processes.... more
The combustion and carbon dioxide gasification behavior of lignite/corn cobs mixtures through thermal analysis experiments was investigated. A simple and accurate model was developed to provide and compare the kinetics of these processes. The characteristic parameters of combustion and gasification, such as decomposition temperature, reaction rate and reactivity, were correlated to the pore structure of the fuels, the composition of ash and mutual interactions between blend components. Combustion of fuels studied occurred in two distinct stages. The reactivity of corn cobs was much higher. When this material was blended with the lignite it improved its combustion efficiency and the mixture presented an additive behavior. The gasification process of chars took place between 750 °C and 950 °C. Corn cobs char exhibited a higher rate. The percentage of this material in the blend was quite low to influence the reactivity of the lignite. The independent parallel reactions model fitted the...
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... the entrained solids and constant quality oil with almost constant content of solids and water has been ... Related to fast pyrolysis of biomass, Unión Elèctrica Fenosa has developed, built and operated a pilot ... a 200 t d −1 unit... more
... the entrained solids and constant quality oil with almost constant content of solids and water has been ... Related to fast pyrolysis of biomass, Unión Elèctrica Fenosa has developed, built and operated a pilot ... a 200 t d −1 unit was installed at Guelph, Ontario, to produce bio-oil from ...
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The reactivity and combustion performance of mixtures of lignite with peach kernel and cardoon were investigated, through thermal analysis experiments, for assessing the potential impacts of these wastes as co-firing fuels. Additionally,... more
The reactivity and combustion performance of mixtures of lignite with peach kernel and cardoon were investigated, through thermal analysis experiments, for assessing the potential impacts of these wastes as co-firing fuels. Additionally, a control method was applied to reduce problematic elements from biomass ashes, in order to mitigate deposition phenomena in co-firing units. The results showed that combustion performance of raw fuels followed the order cardoon>peach kernel>lignite, however in case of blends this order was reversed lignite/peach kernel>lignite/cardoon, revealing synergistic effects between component fuels. The combustion performance of lignite was improved by blending it with the biomass fuels. Deposition problems should be expected in boilers firing peach kernel and cardoon fuels above 900˚C. After alkalis leaching, the reactivity and efficiency of woody materials and mixtures with lignite were enhanced, while the slagging/fouling propensity was reduced.
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ABSTRACT An innovative combustion unit was designed and implemented, aiming at the production of thermal energy, using different types of biomass fuels. The unit was made out of conventional materials, had a nominal capacity of 65 kWth... more
ABSTRACT An innovative combustion unit was designed and implemented, aiming at the production of thermal energy, using different types of biomass fuels. The unit was made out of conventional materials, had a nominal capacity of 65 kWth and comprised a silo, a continuous feedstock supply system, a desiccator, a cutting mill, and a cross flow boiler. Among the two residues tested, olive kernels produced a higher thermal efficiency and lower CO, SO2, and NOx emissions. A series of experiments, conducted at different biomass/air feed rates, showed that at a feedstock mass flow of 14.4 kg/h improved combustion conditions and heat recovery were obtained. Gaseous emissions were kept below the threshold limits and system efficiency was 81.3%. The unit needs to be optimized in terms of air supply and optimal parameters control systems.
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Summarization: Background: Urban and industrial wastes can play an important role in heat and power generation, substituting a large part of conventional fuels. However, combustion of these materials may create operational and... more
Summarization: Background: Urban and industrial wastes can play an important role in heat and power generation, substituting a large part of conventional fuels. However, combustion of these materials may create operational and environmental problems related to their inorganic constituents. Methods: In this work, the slagging/fouling propensities of ashes from municipal and animal wastes were determined through the use of a combination of techniques, such as X-ray diffractometry, ultraviolet and visible spectroscopy, atomic absorption spectroscopy, inductive coupled plasma-mass spectroscopy and fusibility analysis. Control methodologies for mitigating deposition tendency in boilers were applied, i.e. leaching of raw fuels with water and blending them with higher quality woody residues. Results: The results showed that urban and industrial waste ashes were enriched in Ca, P, Si and Mg minerals and micronutrients Cu and Zn. Their alkali-induced slagging/fouling potential was high. For systems operating below 1000 o C, no deposition problems were anticipated. Mixing these waste materials with an agricultural residue led to the production of ashes with melting behaviour and deposition tendency between those of the individual samples. Conclusion: Leaching of raw materials with water resulted in a significant decrease of problematic elements K, Na, P, S, and Cl in ashes and consequently in a great reduction of their slagging/fouling propensity.Παρουσιάστηκε στο: Recent Innovations in Chemical Engineerin
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Research Interests: Environmental Science, BIOCHAR, Resources, Fertilizer, Compost, and 3 moreAmendment, Soil Water, and husk
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ABSTRACT Five energy plants from different regions of the world were pyrolyzed by non-isothermal thermogravimetry and effluent gases were detected through a mass spectrometer. Thermal decomposition characteristics, quantification of... more
ABSTRACT Five energy plants from different regions of the world were pyrolyzed by non-isothermal thermogravimetry and effluent gases were detected through a mass spectrometer. Thermal decomposition characteristics, quantification of emissions, reactivity, and process kinetics were determined. Among the fuels tested, miscanthus was the most reactive, while jatropha was more heterogeneous. A first-order parallel reactions model fitted the experimental results with great accuracy. Miscanthus and willow can be characterized as high-quality fuels and produced higher amounts of carbon oxides and lighter hydrocarbons at lower temperatures. For jatropha, cardoon, and sunflower co-gasification or co-firing is suggested, in order to avoid nitrogenous emissions.