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The combustion of coal in a mixture of pure O 2 and recycled flue gas is one variant of a novel combustion approach called oxy-fuel combustion. With the absence of N 2 , this approach leads to a flue gas stream highly enriched in CO 2 . For many applications, this flue gas stream can then be compressed and sequestered without further separation. As a result, oxy-fuel combustion...
The charged fraction of submicrometer and ultrafine particles generated during bench scale coal combustion and the subsequent penetration of particles through a cylindrical-wire electrostatic precipitator (ESP) in O 2 –CO 2 and O 2 –N 2 environments were measured. In all combustion environments, natural particle charging within the combustor was not adequate for high...
Combustion tests were undertaken in a vertical pilot-scale furnace (1.2MWt) at the IHI test facility in Aioi, Japan, to compare the performance of an air fired swirl burner retrofitted to oxy fired pf coal combustion with the oxy fired feed conditions established to match the furnace heat transfer for the air fired case. A turn down test at a reduced load was also conducted to study the impact on...
Experimental investigation of the combustion of an air-dried Victorian brown coal in O 2 /N 2 and O 2 /CO 2 mixtures was conducted in a lab-scale drop-tube furnace (DTF). In situ diagnostics of coal burning transient phenomena were carried out with the use of high-speed camera and two-colour pyrometer for photographic observation and particle temperature measurement,...
The ignition temperatures of a Loy Yang brown coal and a Datong bituminous coal were investigated in a wire-mesh reactor where the secondary reactions of the evolved volatiles were minimised. An increase in the average particle ignition temperature of 21°C was observed for the brown coal when air (21% O 2 +79% N 2 ) was replaced with a mixture of 21% O 2 +79% CO 2 ...
Combustion of a Chinese bituminous coal was carried out in a laboratory-scale drop tube furnace (DTF) to clarify the variation of ash properties with bulk gas composition. The combustion conditions tested include three bulk gases, air, 21% O 2 /79% CO 2 and 27% O 2 /73% CO 2 , two furnace/gas temperatures close to the fluidized bed reactor temperature range, 1073K and...
In this paper, a comprehensive computational fluid dynamics (CFD) modelling study was undertaken by integrating the combustion of pulverized dry lignite in several combustion environments. Four different cases were investigated: an air-fired and three different oxy-fuel combustion environments (25vol.% O 2 concentration (OF25), 27vol.% O 2 concentration (OF27), and 29vol.% O 2...
In order to investigate the role of combustion chemistry and radiation heat transfer in oxy-fuel combustion modeling, a computational fluid dynamics (CFD) modeling study has been performed for two different oxy-fuel furnaces. One is a lab-scale 0.8MW oxy-natural gas flame furnace whose detailed in-flame measurement data are available; the other is a conventional 609MW utility boiler which is assumed...
Sulphur capture by calcium-based sorbents is a process highly dependent on the temperature and CO 2 concentration. In oxy-fuel combustion in fluidised beds (FB), CO 2 concentration in the flue gas may be enriched up to 95%. Under so high CO 2 concentration, different from that in conventional coal combustion with air, the calcination and sulphation behaviour of the sorbent...
Increased CO 2 and H 2 O concentrations in oxy-fuel combustion promote radiation compared to conventional air based technologies. Spectral radiation models are necessary to calculate the radiative properties of CO 2 and H 2 O. In the present study, the wide band correlated-k method (WBCK) is evaluated for non-grey radiative transfer calculations in oxy-fuel combustion...
The pyrolysis and combustion behaviour of a petroleum coke (petcoke), an indigenous lignite and their 70/30wt.% blend in air and oxy-fuel conditions were investigated by using non-isothermal thermo-gravimetric method (TGA) coupled with Fourier transform infrared (FTIR) spectrometer. Blend samples were prepared by mixing lignite, which has low calorific value, high ash and moisture contents with petcoke...
We report on an experimental investigation of oxy-fuel combustion carried out in a co-axial, horizontally-fired swirl-stabilized burner. Retrofitting possibilities and flame extinction have been investigated with methane or liquefied petroleum gas (LPG) as fuel and mixtures of oxygen (O 2 )–carbondioxide (CO 2 ) or air as oxidant. Temperature profile measurements show that a higher...
Pulverized coal-fired (PC) power plants are the major technology used to generate electricity for power generation around the world. These processes are generally considered to make a significant contribution to global climate change since they have high CO 2 emissions, with the exception of those coal-fired power plants that employ CO 2 capture and storage (CCS) technology.With regard...
Oxy-fuel combustion technique is a viable option to reduce several types of greenhouse gases (GHGs) emissions from the pulverized coal (PC) combustion systems. In this paper, a computational fluid dynamics (CFD) modelling study has been developed in order to investigate the Victorian brown coal combustion in a 550MW utility boiler under the air-fired (reference case) and three oxy-fuel-fired scenarios...
The mechanisms governing the behaviour of limestone for in-furnace desulphurisation during oxy-fuel combustion have been investigated in this paper. Apart from the use of pure limestone, the mixtures of limestone with a brown coal (i.e., lignite) at different mass ratios have also been examined to address the influence of ash on the behaviour of limestone. The combustion experiments were conducted...
The characteristics of oxy-methane flames in atmospheric conditions (298K and 1bar) were studied in a lab-scale slot burner. As a diagnostic tool, OH ∗ , CH ∗ , and C2∗ measurements were used to analyze the flame structure. To estimate the flame stabilization, the flow velocity was varied from u F =7–50m/s for methane gas and u Ox =10–170m/s for oxygen gas. From the...
The thermogravimetric characteristics of tire rubber (TR), rubber mattress (RM) and polyvinyl chloride (PVC), representing the rubber and plastic materials of municipal solid waste (MSW) were compared under 80N 2 /20O 2 and 80CO 2 /20O 2 atmospheres. Replacement of N 2 by CO 2 reduced the weight loss rate of most peaks below 600°C, postponed the location...
Stefan flow occurring at the surface of char and CO oxidation in the boundary layer are often neglected in the conventional pulverized-coal air combustion. In this work, effects of Stefan flow and CO oxidation in the oxy-fuel burning are investigated numerically and experimentally. A mathematical model is firstly developed for the combustion of a carbon particle. Comparisons with the experiment data...
Oxy-fuel combustion is a promising technology for the cogeneration of electricity and a rich stream of CO 2 subjected to direct sequestration. The combination with renewable fuels as biomass could contribute to a large extent in CO 2 reduction in comparison with fossil fuels and therefore, to reduce the greenhouse effect.In this study, the analysis of thermodynamical equilibrium calculations...
The modeling through computational fluid dynamics of oxy-natural-gas combustion experimental tests in a 3MW semi-industrial furnace equipped with a low NOx burner is discussed. Since the complex geometry of the burner and the size of the furnace, a modeling strategy has been adopted to diminish the computational time and thus to make the simulations affordable. The model aims at validating different...
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