Globally coal is, and will continue to be, used in electrical generation and the current imperative is to improve the performance of coal-fired power stations and to reduce emissions. An important element of this drive is to gain a greater understanding of the coal used. Charcoal, formed as a result of wildfires, is common in coal and is often what soils the hands on touch. The aim of this project is to develop methods of reporting charcoal occurrence in coals that will (i) allow cross coal comparison, (ii) be applicable in developing coal specifications for use in industry, forensic science and Geology, (iii) provide a standard and reliable framework for deriving palaeoenvironmental signals from ancient charcoal occurrences and (iv) serve as a predictor of coal behaviour during combustion. Fire is a major Earth System process. Wildfires are influenced by climate and atmospheric oxygen concentrations. Charcoal occurs abundantly in coals and may consist of large pieces or small particles and it may be disseminated within a coal or may occur as discrete bands. Charcoal washed in from a fire outside the peat-forming environment is likely to occur in bands accompanied by sediment. The distribution of charcoal within coals is a powerful tool for understanding peat (precursor to coal) accumulation processes, for interpreting past fire regimes and for recognising climate change, whilst the inert nature and lack of volatiles in charcoal (compared to other coal constituents) influences the combustion and burn out properties and utilisation of coals in an industrial context. However, there is no common scheme for documenting charcoal occurrence in coals and there is minimal data on spatial variation in charcoal distribution or particle size or on the effect this may have on industrial coal utilisation. Selected coals from the Permian (300-250 Million Years ago) of Australia and Russia will be used in this project for the following reasons: (i) they represent peat accumulation in two distinctive vegetation types from different areas thereby testing the wider applicability of results (ii) the peats accumulated at a time of the highest oxygen levels over the past 600 Million Years thereby maximising likely charcoal occurrences, (iii) as expected from ii charcoal is abundant and may make up 40% or more of Permian coal seams and (iv) Permian coals are currently the most important internationally traded coals for electrical generation. The nature of the charcoal deposits will be investigated at Royal Holloway using a variety of microscopic techniques including reflectance microscopy on polished blocks of coal, scanning electron microscopy and maceration of the charcoal from the coal. The in situ distribution and abundance of charcoal will be determined through continuous coal profiles. The abundance data will be compared with those obtained from pulverized sub-samples of the whole coal (as used in industry) and with coal splits. Coal splits that have a variety of charcoal distribution patterns, charcoal clast sources (e.g. wood, fern) and charcoal particle sizes will be investigated for their combustion and burn-out behaviour using a series of experimental rigs based at Npower laboratories. The project will establish the aspects of charcoal distribution, abundance, source and size that prove to be significant in influencing industrial, palaeoecological or geological applications. The relative merits of various investigative techniques will be evaluated. These data will be combined to produce a recommended framework for categorisation of charcoals in coals. New knowledge of charcoals in Permian coals will be applied in palaeoenvironmental reconstruction and used to inform the coal purchasing strategies at Npower.

The power generation industry relies heavily on coal despite the availability of other energy sources. The use of low quality coals, and coal blends from a variety of sources is becoming widespread in power plant for economic and availability reasons. Co-firing coal with biomass on existing coal fired furnaces is recognised as one of the new technologies for reducing CO2 emissions in the UK and the rest of the world. The changes in these fuel supplies have posed significant technical challenges for combustion plant operators and engineers to maintain high combustion efficiency and low atmospheric emissions including CO2, NOx, SOx and particulates. Despite various advances in developing the coal combustion and co-firing technologies, a range of technological issues remain to be resolved due to the inherent differences in the physical and combustion properties between coal and biomass. A typical problem associated with the use of low quality coal and co-firing of coal and biomass is the uncertainty in the combustion characteristics of the fuels, often resulting in poor flame stability, low thermal efficiency, high pollutant emissions, and other operational problems. To meet the stringent standards on energy saving and pollutant emissions, advanced technology for improved understanding of energy conversion, pollutant formation processes and consequent combustion optimisation in coal-biomass fired furnaces have therefore become indispensable.A flame, as the primary zone of the highly exothermic reactions of burning fuels, contains important information relating closely to the quality of the combustion process. Recent study has shown that the combustion process, particularly the pollutant emission formation processes, can be better understood and consequently optimised by monitoring and quantifying radical emissions within the flame zone through spectroscopic imaging and image processing techniques. It is proposed to develop a methodolgy for the monitoring and quantification of the radiative characteristics of free radicals (e.g. OH*, CH*, CN* and C2) within a coal-biomass flame and consquently the estimation of the emission levels in flue gas (e.g. NOx, CO2 and unburnt carbon). A vision-based instrumentation system, capable of detecting the radiative characteristics of the multiple radicals simultaneously and two-dimensionally, will be constructed. Computing algorithms will be developed to analyse the images and quantify the radiative characteristics of the radicals based on advanced signal processing techniques including wavelet analysis. The relationships between the characteristics of the radicals and fuel type and air supplies will be established. The emission levels in flue gas will be estimated based on characteristic features of the flame radicals obtained by the system. All data processing will be performed in an industrial computer system associating with integrated system software including a graphic user-interface. The system developed will be initially tested on a gas-fired combustion rig in University of Kent and then an industrial-scale coal combustion test facility run by RWE npower. A range of combustion conditions will be created during the industrial tests, including different coal-biomass blends and different fuel/air flowrates. The relationships between the emission characteristics of radicals and the chemical/physical properties of the fuels and the pollutant emissions will then examined under realistic industrial conditions.The outcome of this research will provide a foundation for a new area within coal-biomass combustion optimisation in which advanced flame monitoring techniques could help to predict emissions directly from the flame information instead of the flue gas measurement, shortening the control loop for emissions reduction. Such techniques would greatly benefit the power industry by allowing them burning fuels more efficiently and meanwhile reducing harmful emissions to the environment.

Biomass - vegetation such as trees, grasses or straws - is resurging as a source of sustainable, environmentally-friendly fuel for use in power stations. This is because, when grown in a sustainable way, it is almost carbon-neutral - the carbon-doxide emitted when the biomass is burned, is readsorbed from the atmosphere during the photosynthesis of the next crop of biomass. Consequently, there is a great deal of interest in using biomass in coal-fired power stations by substituting a portion of the coal. Today, many power-stations in the UK have adopted this co-firing approach to reduce their carbon (dioxide) emissions. This is a good strategy since the biomass is burned in the very large coal power stations which have a higher efficiency than the small systems needed if the same amount of biomass was to be burned alone. However, in the power stations the coal is crushed to a fine powder in huge mills before being blown into the burners in the boiler. Most biomass does not grind or crush very well because it is springy and fibrous. Consequently, when power generators attempt to powder the biomass in the coal mills it tends to form a mat on the bottom of the mill. This has limited the amount of biomass which can be processed in the mills and hence limited the amount of biomass used in the power-stations, and hence limited the carbon savings from co-firing biomass. Some power stations have invested millions of pounds to install separate, different types of mills for cutting biomass so that they can use more - for example, up to 20% by weight is used in Fiddlers Ferry power station. Another strategy is a process known as torrefaction in which the biomass is pre-treated so that it becomes more brittle and easier to crush. This process involves heating biomass to a moderate temperature (~280 C) in the absence of air. It is similar to the process used to roast coffee beans and so is sometimes refered to as roasting biomass. During torrefaction some material is lost from the biomass - particularly moisture and some gases and volatile substances - but the material which is left, the residue, still contains typically 80% of the heating value of the original biomass, and is transformed into a harder, darker fuel, which is much easier to crush. This process is attracting a great deal of interest from all sectors involved in the bioenergy chain: - growers see this is a way of adding value to the biomass they grow and reducing transportation costs (since the fuel is dry and has a greater energy per unit volume); power-generators see this as a simpler fuel to handle in the power stations; and there is also interest in using torrefied biomass as a fuel in other conversion processes, such as biomass gasification to liquid (transport) fuels (BTL). Furthermore, torrefied biomass does not go mouldy upon storage like raw biomass and so it becomes attractive for extending the supply window for using biomass. In order for torrefaction of biomass to happen on a large scale much information is needed in order to design safe, environmentally-friendly torrefiers. This research is aimed at providing much of this information and answering these questions: What are the explosion risks within torrefiers or mills using torrefied biomass? (Fine dust can result in explosions under certain concentrations, and knowledge of these concentrations is needed in order to incorporate adequate safety design features.) What would the effluents from the process (liquid and gas) be composed of? Can the gas and vapours produced provide the heat to drive the torrefaction? How would torrefied biomass burn in the power station? It also aims to develop a tool which engineers can use to help them design the torrefier itself, so that they know what temperature is needed, and how long the biomass needs to reside within the torrefier so that an optimum fuel is produced.

Managing creep is a major issue in the power and other industries, particularly as plant ages, but there is currently no satisfactory method for in-situ monitoring the of progress of creep damage. The proposers have recently conducted a feasibility study that has shown that the progress of creep can be tracked by monitoring the evolution of potential drop anisotropy between directions parallel to and perpendicular to the loading direction. The technique is potentially a very simple method of monitoring creep, but several fundamental issues must be addressed before the method can be applied in industry. To date, only nominally homogeneous, ferritic steels have been tested, and these exhibit significant voiding during creep. Other important materials such as stainless steels can exhibit less voiding so it is necessary to understand better the mechanism of the evolution of the potential drop anisotropy and to investigate its applicability to austenitic steels and nickel base super alloys. In addition, creep often occurs at welds, so it is necessary to determine how the intrinsic conductivity difference between the base metal and the weld affects the apparent anisotropy measured by directional potential drop measurements, and also whether different thermally-induced microstructural evolution in these different microstructures leads to spurious apparent anisotropy changes, and hence limits the detectability of creep damage in welds and their neighbourhood. While monitoring using a permanently attached probe is attractive in some applications, in others such as turbine blades, it is not feasible so it is necessary to investigate whether a deployable probe can be used. This proposal seeks funds to address these scientific and engineering issues, and so to produce a new creep monitoring technique that will particularly benefit the power and related industries.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.