The Experts below are selected from a list of 1044 Experts worldwide ranked by ideXlab platform
Patricia Cordoba - One of the best experts on this subject based on the ideXlab platform.
-
status of flue gas desulphurisation fgd systems from Coal fired power plants overview of the physic chemical control processes of wet limestone fgds
Fuel, 2015Co-Authors: Patricia CordobaAbstract:This paper presents a general review of the Flue Gas Desulphurisation (FGD) technologies used to abate sulphur emissions from Coal-fired power plants, and exposes the major physic-chemical processes occurring during wet limestone FGD. The abatement capacity of major, minor, and trace elements and the fate of trace pollutants during wet limestone FGD, as well as the features of wet limestone FGD by-products are discussed. It can be stated that wet limestone FGD system is the FGD process most widely used because of its high desulphurisation performance and low operating cost. Among control parameters evaluated in this review, pH range > limestone reactivity and SO2 concentration > efficiency of particulate control devices > water re-circulation to the scrubber > entrainment of particles by the OUT-FGD gas, are the key factors of wet limestone FGDs. It is noted that, the enrichment of inorganic trace pollutants in FGD waters because of the re-circulation of water to the scrubber from gypsum slurry filtration, and the entrainment of accumulated fly ash particles in gypsum sludge, those of unreacted limestone, and the particles and droplets from gypsum slurry by the outgoing FGD (OUT-FGD) gas reduce considerably the desulphurisation efficiency and the abatement capacity of trace pollutants by wet limestone FGDs. The paper concludes with a number of issues to be investigated in depth in view of the worldwide FGD market growth and the forthcoming implementation of one of the most promising technologies to reduce CO2 emissions, oxy-fuel Combustion, in Pulverised Coal Combustion (PCC)–FGD processes at an industrial scale.
Alan Williams - One of the best experts on this subject based on the ideXlab platform.
-
les modelling of air and oxy fuel Pulverised Coal Combustion impact on flame properties
Proceedings of the Combustion Institute, 2011Co-Authors: P J Edge, Sreenivasa Rao Gubba, Mohamed Pourkashanian, R Porter, Alan WilliamsAbstract:Abstract Large eddy simulations (LES) are used in a CFD model to simulate air- and oxy-fired Pulverised Coal Combustion in a 0.5 MWth Combustion test facility. Simulations are carried out using two different burners, namely, a triple-staged low-NOx wall fired burner and an IFRF Aerodynamically Air-Staged Burner (AASB). Non-gray radiation is considered in order to deal with the spectral nature of absorption and emission by high levels of Combustion products in oxy-fuel Combustion. Predictions using LES are compared with Reynolds-averaged Navier–Stokes (RANS) calculations using variants of the k-e model for turbulence and against available experimental measurements. The results suggest that LES can offer improvements over RANS in predicting recirculation zones and flame properties of the Pulverised Combustion systems investigated. Flame flickering frequencies from the LES simulations are calculated and validated against available measurements. The work presented demonstrates the potential importance of using LES turbulence models for Coal Combustion.
-
les modelling of air and oxy fuel Pulverised Coal Combustion impact on flame properties
Proceedings of the Combustion Institute, 2011Co-Authors: P J Edge, Sreenivasa Rao Gubba, Mohamed Pourkashanian, R Porter, Alan WilliamsAbstract:Abstract Large eddy simulations (LES) are used in a CFD model to simulate air- and oxy-fired Pulverised Coal Combustion in a 0.5 MWth Combustion test facility. Simulations are carried out using two different burners, namely, a triple-staged low-NOx wall fired burner and an IFRF Aerodynamically Air-Staged Burner (AASB). Non-gray radiation is considered in order to deal with the spectral nature of absorption and emission by high levels of Combustion products in oxy-fuel Combustion. Predictions using LES are compared with Reynolds-averaged Navier–Stokes (RANS) calculations using variants of the k-e model for turbulence and against available experimental measurements. The results suggest that LES can offer improvements over RANS in predicting recirculation zones and flame properties of the Pulverised Combustion systems investigated. Flame flickering frequencies from the LES simulations are calculated and validated against available measurements. The work presented demonstrates the potential importance of using LES turbulence models for Coal Combustion.
-
MODELLING Pulverised Coal Combustion USING A DETAILED Coal Combustion MODEL
Combustion Science and Technology, 2006Co-Authors: R I Backreedy, Mohamed Pourkashanian, L. M. Fletcher, Alan WilliamsAbstract:ABSTRACT The ability to assess the Combustion behaviour of internationally traded Coals and accurately predict flame characteristics, stable species concentration, unburned carbon and pollutant emissions is of importance to the power generating industry. Despite recent advances in Coal Combustion modelling detailed understanding is still lacking on the exact role of the Coal maceral content on the Combustion process. Here, a CFD-based Coal Combustion model that includes these effects has been developed to try to improve the predictive capability. A computational simulation of a 1 MW (thermal), Pulverised fuel Combustion test furnace, which was designed to replicate the time-temperature history of a full-scale furnace, was performed. This furnace also contained a triple-staged low-NOx swirl burner. A number of simulations were made using a number of Coals in order to calculate NOx and the unburned carbon-in-ash, the latter being a sensitive test for the accuracy of the char Combustion model.
-
approaches to modelling heterogeneous char no formation destruction during Pulverised Coal Combustion
Carbon, 1999Co-Authors: Jenny M. Jones, Mohamed Pourkashanian, P M Patterson, Alan WilliamsAbstract:Abstract Emissions of nitrogen oxides during Combustion pose a major environmental problem and hence there is considerable interest in reducing the NO x levels encountered during Pulverised Coal Combustion. The chemically bound nitrogen in the fuel is known to account for up to 80% of total NO x . Whilst the homogeneous production pathways of NO x from the nitrogen present in the Coal volatiles are relatively well known, the heterogeneous conversion of the nitrogen retained in the char to NO is less well understood. As part of an ongoing project to develop an advanced Coal model to describe the Combustion process in Pulverised Coal flames this study examines the possible mechanisms involved in both nitric oxide formation and reduction at the char surface for a more accurate prediction of char–NO interactions. The use of a model to predict the partition of Coal nitrogen between volatiles and char has also been explored. Various mechanisms of NO x production/destruction at the char surface are discussed and it is concluded that the best approach for computational modelling is to treat the formation and reduction pathways separately. The rate of NO formation is related to that of the char oxidation by the molar ratio of carbon to nitrogen in the char. The rate of NO reduction at the char surface is represented by R NO =2.6·10 4 exp −15 900 T A E P NO mol s −1 , where A E is the external area of the char (m 2 g −1 ) and P NO is the partial pressure of NO (atm).
T F Wall - One of the best experts on this subject based on the ideXlab platform.
-
sulphur impacts during Pulverised Coal Combustion in oxy fuel technology for carbon capture and storage
Progress in Energy and Combustion Science, 2011Co-Authors: Rohan Stanger, T F WallAbstract:The oxy-fuel process is one of three carbon capture technologies which supply CO2 ready for sequestration – the others being post-Combustion capture and IGCC with carbon capture. As yet no technology has emerged as a clear winner in the race to commercial deployment. The oxy-fuel process relies on recycled flue gas as the main heat carrier through the boiler and results in significantly different flue gas compositions. Sulphur has been shown in the study to have impacts in the furnace, during ash collection, CO2 compression and transport as well as storage, with many options for its removal or impact control. In particular, the effect of sulphur containing species can pose a risk for corrosion throughout the plant and transport pipelines. This paper presents a technical review of all laboratory and pilot work to identify impacts of sulphur impurities from throughout the oxy-fuel process, from Combustion, gas cleaning, compression to sequestration with removal and remedial options. An economic assessment of the optimum removal is not considered. Recent oxy-fuel pilot trials performed in support of the Callide Oxy-fuel Project and other pilot scale data are interpreted and combined with thermodynamic simulations to develop a greater fundamental understanding of the changes incurred by recycling the flue gas. The simulations include a sensitivity analysis of process variables and comparisons between air fired and oxy-fuel fired conditions - such as Combustion products, SO3 conversion and limestone addition.
-
the effects of pressure on Coal reactions during Pulverised Coal Combustion and gasification
Progress in Energy and Combustion Science, 2002Co-Authors: T F Wall, Guisu Liu, Daniel G Roberts, Katharine E Benfell, Sushil Gupta, John Lucas, David J HarrisAbstract:Abstract Advanced clean Coal technologies, e.g. power generation from integrated gasification combined cycle (IGCC) and pressurised fluidised bed combustor, have attracted increased interest from the scientific and technological communities over the last few decades. Pressures up to 40 atm have been applied to these technologies, which inherently result in an increase in Coal throughput, a reduction in pollutant emissions and an enhancement in the intensity of reaction. Therefore, fundamental understanding of the effect of operating pressure on Coal reactions is essential to the development of these technologies. In this paper, the pressure effect on a variety of aspects of Coal reactions reported in the open literature has been reviewed. Major emphasis of the paper is given to experimental observations, although some theoretical modelling is reviewed. The pressure has been found to significantly influence the volatiles yield and Coal swelling during devolatilisation, hence the structure and morphology of the char generated. More char particles of high porosity are formed at higher pressures. Char structure appears to play a significant role in burnout of residual char and ash formation. In general, at higher pressures, Coal particles burn quicker and form finer ash particles. Increasing reactant pressure enhances char Combustion and gasification reaction rate, which can be understood by an adsorption–desorption mechanism. These factors have been applied to the understanding of a practical high-pressure gasifier. Most of the work published has been at the lower temperatures (typically
-
mineral matter transformations and ash deposition in Pulverised Coal Combustion
Symposium (International) on Combustion, 1992Co-Authors: T F WallAbstract:During Combustion the inorganic constituents of Coal are transformed into products (including vapors, aerosols and residual ash particles) which may transfer to furnace walls and form deposits which restrict heat transfer. Many of the mechanisms of these transformations have now been identified and are detailed by considering the elements, iron and sodium, which have been associated with slagging and fouling respectively. Developments in the scientific analysis of ash deposition, based on these mechanisms, include techniques for Coal characterisation, control techniques, the development of engineering deposition parameters and mathematical modelling of the processes.
P J Edge - One of the best experts on this subject based on the ideXlab platform.
-
les modelling of air and oxy fuel Pulverised Coal Combustion impact on flame properties
Proceedings of the Combustion Institute, 2011Co-Authors: P J Edge, Sreenivasa Rao Gubba, Mohamed Pourkashanian, R Porter, Alan WilliamsAbstract:Abstract Large eddy simulations (LES) are used in a CFD model to simulate air- and oxy-fired Pulverised Coal Combustion in a 0.5 MWth Combustion test facility. Simulations are carried out using two different burners, namely, a triple-staged low-NOx wall fired burner and an IFRF Aerodynamically Air-Staged Burner (AASB). Non-gray radiation is considered in order to deal with the spectral nature of absorption and emission by high levels of Combustion products in oxy-fuel Combustion. Predictions using LES are compared with Reynolds-averaged Navier–Stokes (RANS) calculations using variants of the k-e model for turbulence and against available experimental measurements. The results suggest that LES can offer improvements over RANS in predicting recirculation zones and flame properties of the Pulverised Combustion systems investigated. Flame flickering frequencies from the LES simulations are calculated and validated against available measurements. The work presented demonstrates the potential importance of using LES turbulence models for Coal Combustion.
-
les modelling of air and oxy fuel Pulverised Coal Combustion impact on flame properties
Proceedings of the Combustion Institute, 2011Co-Authors: P J Edge, Sreenivasa Rao Gubba, Mohamed Pourkashanian, R Porter, Alan WilliamsAbstract:Abstract Large eddy simulations (LES) are used in a CFD model to simulate air- and oxy-fired Pulverised Coal Combustion in a 0.5 MWth Combustion test facility. Simulations are carried out using two different burners, namely, a triple-staged low-NOx wall fired burner and an IFRF Aerodynamically Air-Staged Burner (AASB). Non-gray radiation is considered in order to deal with the spectral nature of absorption and emission by high levels of Combustion products in oxy-fuel Combustion. Predictions using LES are compared with Reynolds-averaged Navier–Stokes (RANS) calculations using variants of the k-e model for turbulence and against available experimental measurements. The results suggest that LES can offer improvements over RANS in predicting recirculation zones and flame properties of the Pulverised Combustion systems investigated. Flame flickering frequencies from the LES simulations are calculated and validated against available measurements. The work presented demonstrates the potential importance of using LES turbulence models for Coal Combustion.
W Nimmo - One of the best experts on this subject based on the ideXlab platform.
-
fuel additive technology nox reduction Combustion efficiency and fly ash improvement for Coal fired power stations
Fuel, 2014Co-Authors: S S Daood, G Ord, T Wilkinson, W NimmoAbstract:Abstract Fuel additive technology is based on the use of a solid, fuel additive (iron, aluminium, calcium and silicon based oxides), to reduce NOx emission, improve the quality of fly ash and result in 1–3% Coal savings for Pulverised Coal Combustion. The findings in this study have been mainly based on extensive experimentation on 100 kWth down fired-Combustion test facility (CTF) and partially on a commercial 260 tons/h steam producing water tube pf boiler. International Innovative Technologies (IIT) developed this additive based technology for the combined effect of reducing NOx from the Combustion of hydrocarbon fuels (mainly Coal) and more specifically to improve the Combustion process of fossil fuels resulting in an ash by product with improved loss on ignition and lower carbon content. The improvement in the Combustion thermal efficiency of the commercial 260 tons/h steam producing boiler has been calculated as per the direct calculation method of EN BS12952-15:2003 standard.
