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This paper reviews the costs and technologies involved in an integrated system for the production of electricity from biomass in general and wood in particular. It first examines the economics of gasification, showing that the potential for this form of renewable energy lies in either processing low-cost wastes or relying on some sort of fiscal incentive, even at relatively large scales of operation...
Studies on wood and twelve other types of biomass showed that in general, deashing increased the volatile yield, initial decomposition temperature and rate of pyrolysis. However, coir pith, groundnut shell and rice husk showed an increase in char yield on deashing, which is attributed to their high lignin, potassium and zinc contents. These results were supported by studies on salt-impregnated, acid-soaked...
Studies on wood and twelve other types of biomass showed that in general, deashing increased the volatile yield, initial decomposition temperature and rate of pyrolysis. However, coir pith, groundnut shell and rice husk showed an increase in char yield on deashing, which is attributed to their high lignin, potassium and zinc contents. These results were supported by studies on salt-impregnated,...
The composition of oils derived from the on-line, low pressure zeolite upgrading of biomass pyrolysis oils from a fluidized bed pyrolysis unit have been investigated in relation to the regeneration of the zeolite catalyst. The catalyst used was H-ZSM-5 zeolite. The gases were analysed by packed column gas chromatography. The composition of the oils before catalysis and after catalyst upgrading were...
The composition of oils derived from the on-line, low pressure zeolite upgrading of biomass pyrolysis oils from a fluidized bed pyrolysis unit have been investigated in relation to the regeneration of the zeolite catalyst. The catalyst used was H-ZSM-5 zeolite. The gases were analysed by packed column gas chromatography. The composition of the oils before catalysis and after catalyst upgrading...
Rapid pyrolysis of biomass, wood and agricultural residues was studied using a free-fall reactor with which the effects of heating rate, temperature, particle size and residence time on the product distribution, gas composition and char reactivity could be determined. Interest was focused on the effect of the rapid pyrolysis conditions on the reactivity of the char. Formation of low yields of char...
Biomass samples were submitted to thermoanalytical investigation to evaluate their thermal behaviour in both oxidizing and inert atmospheres. The trend of the t.g.a. and d.t.g. curves in air or He were evaluated to obtain information on reactivity of the samples and some correlations with their analytical characteristics. In particular, evaluation of lignin content was found to be useful to predict...
Biomass pyrolysis studies were conducted using both a thermogravimetric analyser and a packed-bed pyrolyser. Each kind of biomass has a characteristic pyrolysis behaviour which is explained based on its individual component characteristics. Studies on isolated biomass components as well as synthetic biomass show that the interactions among the components are not of as much significance as the composition...
Biomass in the form of mixed wood waste was pyrolysed in a fluidized bed reactor at 400, 450, 500 and 550°C. The char, liquid and gas products were analysed to determine their elemental composition and calorific value. In particular, the liquid products were analysed in detail to determine the concentration of environmentally hazardous polycyclic aromatic hydrocarbons (PAH) and potentially high-value...
Fixed-bed pyrolysis and hydropyrolysis experiments at different temperatures, heating rates and pressures have been conducted on a sample of Euphorbia rigida to investigate the product yields and characteristics. In hydrogen at 15 MPa and 550°C, the trends in yield and product composition markedly differ from those found previously for coals and oil shales; also the oil yield of 41.5 wt% is more than...
Co-firing of biofuels and coal in power plants is considered by the Danish utilities as a potential tool in reducing CO 2 emissions. To test this, full-scale measurements were carried out for 1 week on a 250 MW e pulverized coal fired unit using 10-20% straw (thermal basis). With an increased fraction of straw in the fuel, a net decrease in NO x and SO 2 emissions...
Studies conducted on the heating value of various types of biomass components and their pyrolysis products such as char, liquids and gases are presented. Heating values of chars are comparable with those of lignite and coke; heating values of liquids are comparable with those of oxygenated fuels such as methanol and ethanol, which are much lower than those of petroleum fuels. Heating values of gases...
The effect of combustion of biomass on soot aggregates and polynuclear aromatic compounds (PACs) has been studied. Conditions similar to those in typical residential space heating systems used to burn wood have been simulated in a laboratory furnace. The biomass fuels used included (1) paper-mill residue, (2) hard pine-wood, and (3) particle board, typically used in the construction of indoor furniture...
The volatility of mercury can cause large errors during quantification when methods based on acid digestion are applied. In this study, mercury levels in coals have been determined by an atomic-absorption- based instrument hitherto not used with coals or coal-derived materials. The results have been compared with ?certified? values of reference materials. The instrument is relatively easy to use:...
The volatility of mercury can cause large errors during quantification when methods based on acid digestion are applied. In this study, mercury levels in coals have been determined by an atomic-absorption- based instrument hitherto not used with coals or coal-derived materials. The results have been compared with 'certified' values of reference materials. The instrument is relatively easy to use:...
Utilization of biomass-pyrolysis char for adsorption purposes is of bonus advantage and importance considering the ubiquitous need for a cheap source of carbon adsorbent for various small-scale industries for waste water treatment. Experimental studies were conducted in this context, to characterize the biomass-pyrolysis char to explain their specificity as conditioned by their individual adsorptive...
The aim of this work is to study the influence of initial pressure on the limiting oxygen concentration for a biomass dust. Atmospheric tests were carried out in the 20-1 sphere. Hyperbaric tests at 0.5, 1.2 and 1.8 MPa were developed in a 1-m 3 spherical vessel. This study used unusually high initial testing pressures, and it was performed with a renewable material with great potential...
This paper describes a series of explosion tests carried out with biomass at high initial pressures. Atmospheric tests were developed in a 20 1 sphere, and a hyperbaric series at 1 and 1.5 MPa in a 1 m 3 sphere. Depending on concentration, one or two points of dispersion were used and the injection impulse varied from 2.0 to 3.5 MPa, achieving different levels of turbulence. Both the great...
The present study was undertaken to clarify the purpose of using reactive gases during the thermochemical processing of biomass. Conversions observed during pyrolysis (He) have been compared directly with gasification in H 2 , CO 2 and steam-helium mixtures. Experiments have been carried out at pressures between 1 and 20 bar, in a fixed-bed hot-rod reactor, operating at a relatively...
This investigation involved the hydropyrolysis of biomass (eucalyptus globulus) and the immediate catalytic hydrocracking of pyrolytic oils in the second stage of the reactor. The effects of temperature, pressure and the catalyst ageing time on the final product tar have been studied using the catalyst Zeolite H-ZSM5. The catalytically hydrocracked tar/oil products were characterised and compared...
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