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There has been an increase in the use of biomass for power generation by means of co-firing with coal as well as by the combustion of 100% biomass. Despite the advantages of biomass in reducing carbon emissions from the electricity sector, the co-firing of high percentages of biomass can potentially aggravate ash related problems in the boiler. In order to develop mitigation strategies for the formation...
During the combustion of coal and biomass blends, ash particles are deposited on the furnace wall, or on the heat transfer surfaces, and gradually they become sintered and harder. This makes it difficult to remove the deposits by soot blowing, and therefore manual cleaning is often required. In this paper, a computational fluid dynamics (CFD) model that predicts the deposition rates in boilers has...
One of the most promising technologies for carbon capture and storage (CCS) is oxy-fuel combustion. This study uses a commercial computational fluid dynamics (CFD) code to simulate the firing of coal and biomass under air and oxy-fuel conditions in an existing full-scale 500MW e coal-fired utility boiler. Results are presented for conventional air–coal combustion that corresponds well against...
Operational issues, such as slagging, fouling and corrosion of boilers during co-firing are yet to be fully understood. A numerical slagging index (NSI) to predict the slagging potential of coals and coal blends has been developed by some of the present authors, and this has been successfully validated with some Australian bituminous coals. In this paper, the NSI has been modified in order to predict...
At this time, the correlation between the existing coal slagging indices and the actual observations made in most conventional boilers is poor. Some of the conventional coal slagging test procedures and the empirical relations they generated, such as, coal fusibility, ash viscosity, silica ratio, percentage of iron oxide in ash, and the ratio of basic to acidic oxides, frequently offer misleading...
The slagging of heat transfer surfaces during the combustion of pulverized coal in power stations is a major problem as power generators strive to improve the efficiency of their plants. In this paper, a numerical model to predict ash deposition rates in boilers has been developed. The deposition model is based on the sticking tendency of ash particles on impaction on boiler walls. A numerical slagging...
Co-firing of biomass and coal can be beneficial in reducing the carbon footprint of energy production. Accurate modelling of co-fired furnaces is essential to discover potential problems that may occur during biomass firing and to mitigate potential negative effects of biomass fuels, including lower efficiency due to lower burnout and NOx formation issues. Existing coal combustion models should be...
A CFD model that simulates the combustion of biomass in existing pf coal fired furnaces has been developed and model results for the combustion of a typical wood in a 1MW industrial test facility have been presented. The model is primarily based on coal combustion submodels using an Eulerian–Lagrangian frame of reference. Biomass specific constants that define the submodels have been investigated...
Romanian lignite presents utilization problems since it is one of the lowest grade coals in the world. In order to improve the performance of pulverized lignite combustors and to reduce the environmental impact there is interest in predicting NO x emission characteristics and carbon burnout. The application of CFD modeling for this purpose has been widely used for pulverized bituminous coal...
Coal blends are now widely used by the power generation industry and the general characteristics are well known. Attention is still directed to the emission of NO x , which is subject to more stringent regulation, and to the amount of carbon in ash. The latter is increased when low NO x burners are employed, which is the norm now. It is also increased as a result of additional air...
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