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Effects of pressure on the formation of HCN and NH 3 during the pyrolysis and gasification of Loy Yang brown coal in steam were investigated using a pressurised drop-tube/fixed-bed reactor. The NH 3 yield increased with increasing pressure during both pyrolysis and gasification. Increasing pressure selectively favours the formation of NH 3 at the expenses of other N-containing...
The heterogeneous char reaction processes of pulverized coal particle in a hot gas flow with temperature fluctuation are investigated. The instantaneous mass variations and char reaction rates of the particles with initial diameters of 10–50μm are calculated under different conditions. The gas temperature fluctuation has evident influences on the instantaneous char reaction processes of the pulverized...
Biomass fuels come from many varieties of sources resulting in a wide range of physical and chemical properties. In this work, mathematical models of a packed bed system were employed to simulate the effects of four fuel properties on the burning characteristics in terms of burning rate, combustion stoichiometry, flue gas composition and solid-phase temperature. Numerical calculations were carried...
A new empirical formula, based on the surface fractal dimension, the porosity, the botanical composition and the ash content of the precursor is proposed for the assessment of the char yield, Y (wt %) of lignocellulosic materials pyrolysed in a 600–900°C temperature range. The following equation is proposed:Y(wt%)=Dflnɛ[L[0.59−2.74×10−4(t°C−600)]+0.22C+A−0.1E[1+2×10−3(600−t°C)]]where D f ,...
In this paper, particle size effect on pinewood combustion in a stationary packed bed was investigated. Mass loss rate, temperature profile at different bed locations and gas compositions in the out-of-bed flue gases were measured at a fixed primary air flow rate. Pinewood cubes was fired with size ranging from 5 to 35mm. A unique numerical model applicable to thermally thick particles was proposed...
Tests of the unscavenged prechamber ignition system on a 150kW cogeneration engine fed with biogas are presented. The objective was to reach at least 36% in fuel conversion efficiency with exhaust gas emissions lower than the Swiss regulations limits (NO x , CO: 400 and 650mg/Nm 3 , 5% O 2 and 0% relative humidity) without exhaust gas after treatment. With a compression ratio...
Non-oxidative coupling of CH 4 /H 2 mixtures was carried out by means of radio frequency (rf) glow discharges for the first time. A central composite design was employed to determine the best experimental conditions for methane transformation into higher hydrocarbons and to fit the experimental data. rf power was the factor showing the highest effect on the results while CH 4 ...
This paper presents experimental results of a 20kW vertical combustor equipped with a single pf-burner on pulverised coal combustion in air and O 2 /CO 2 mixtures with NO x recycle. Experimental results on combustion performance and NO x emissions of seven international bituminous coals in air and in O 2 /CO 2 mixtures confirm the previous findings of...
This paper deals with the alkaline activation of fly ashes for the production of a novel cementitious material and with the effect of curing conditions on the nature of the reaction products. Curing procedures favouring carbonation process negatively affects the development of mechanical strength of this new alkaline cement. Carbonation of the system involves its pH modification and consequently the...
The search for new energy sources has impulsed hydrocarbon production from methanol and ethanol over ZSM-5 zeolites. Iron incorporation by different methods has led to a variety of chemical applications. Thus, hydrocarbon production from ethanol was studied over a ZSM-5 zeolite modified by ion exchange and impregnation with iron. XRD, FTIR, TPR, nitrogen adsorption, Mössbauer and photoacoustic spectroscopies...
The characteristics of burning pulverized coal motion and the combustion process are investigated by numerical simulation to analyze the relations between the NO x formation and the gas flow and burning pulverized coal moving in a swirl pulverized coal burner. The depth of particle penetration into the IRZ L dav and the effective time of IRZ τ eav are obtained under three swirl...
Field ionization mass spectrometry (FIMS) was investigated to establish a method for clarifying the compositions of hydrocarbons in diesel fuels. Firstly, the influences of reservoir temperature, ion source temperature, emitter current, cathode voltage and ion focusing mode on ion intensities and double bond equivalence value (DBE) distributions were examined to define the analytical conditions for...
Addition of pour point depressants (PPDs) has been proved to be an efficient way to inhibit wax deposition of diesel fuels. However, the complexity of the oil is far beyond current commercial PPD products. So far it mainly depends on syntheses of numerous candidate compounds followed by repeating experimental measurements in order to improve the efficiency of PPDs. In this article, molecular dynamic...
This work presents the results of an experimental and modelling investigation of the ignition of quiescent methane/air mixtures caused by radiation-heated large inert particles. The experimental data indicate that the explosion-delay time is inversely proportional to the radiative power flux. The delay time exhibits a minimum at a methane/air ratio near to stoichiometric. The mathematical model incorporates...
A laboratory-scale capacitively coupled radio frequency (RF) plasma pyrolysis reactor working in reduced pressure has been developed. Experiments have been performed to examine the characteristics of this RF plasma reactor and the products of biomass gasification. It was found that the electrode geometry, input power and reactor pressure were the key parameters affecting the plasma characteristics...
The objective of this work is to study the effect of specific fatty acid methyl esters preset in biofuels on particulate matter emissions. A typical diesel fuel supplied in petrol stations (reference), two biofuels composed of methyl esters from the transesterification process of waste oils with different origins and some blends of biofuels with the reference fuel were tested in a commercial direct...
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