Efforts are being made to achieve environmental sustainability by combining heat and power production and exploiting renewable resources, in order to save primary energy and reduce greenhouse gas emissions. This study concerns a stand-alone 1-megawatt plant composed of a wood pyrolyzer and a combined heat and power plant based on a gas turbine. Care is devoted to saving the solid-state product of the pyrolysis reaction (biochar), both to produce agricultural fertilizer and to sequester carbon dioxide, i.e., the emissions avoided by not burning biochar. The plant is simulated by three in-house codes: gas turbine off-design performance, pyrolysis process and time-by-time integrated plant working. A quasi steady-state, lumped parameter approach is adopted. While components models are taken from the literature, solver algorithms are partly original. In this first step of the research, a stand-alone plant with a zero-volume syngas tank is analyzed. Technical aspects alone, without considering economic or legal implications, are investigated. Our simulation suggests that there is no primary energy saving in comparison with separate heat and power systems, as shaft efficiency is too low, but that a remarkable saving in greenhouse gas emissions can be achieved.

The end-wall boundary-layer theory of Mellor and Wood has been reformulated in streamline coordinates and extended to include predictions for complete velocity profiles in the end-wall regions. Application to a model compressor shows that all parameters vary in the sense expected from known experimental data. These parameters include variable shape factors, skin friction coefficient, and wall skewing angles. The analysis developed has been coupled to a mainstream flow calculations program based on finite elements. Application to axial flow compressors permits the prediction of the complete velocity triangles, including the wall regions and the end-wall losses. Comparisons with experimental results are presented.

The gas turbine or Brayton cycle offers many advantages over a conventional power plant, especially when installed in a cogeneration mode. These advantages include physically compact packages, high reliability, improved system economics and full operating flexibility to meet variable electrical/steam demand. Until recently, the primary disadvantage of the gas turbine cycle has been that internal burning of dirty fuels caused unacceptable erosion and corrosion of turbine blading. In the simple cycle gas turbine modified for indirect heating, the compressor discharge air passes through the tube side of a heat exchanger before passing on to the turbine. Heat is transferred to the air via the combustion products of alternative fuels passing through the shell side of the heat exchanger. This paper discusses the potential of the indirectly heated gas turbine burning wood in a cogeneration configuration with a back-pressure steam turbine.

Indirect firing of combined Brayton and Rankine cycles has been considered as a means of utilizing solid fuels such as wood or coal for power generation. Combined cycles utilizing indirect firing offer potentially higher efficiencies than conventional direct fired Rankine cycles. Many thermodynamic alternatives exist for indirect firing; however, technical, economic, and commercial barriers must be overcome for each of these alternatives. This paper reviews several of the options for indirect fired cycles and considers the factors affecting their application to power generation systems.

Allis-Chalmers, in conjunction with twelve electric utilities, and the State of Illinois is completing the construction of a coal gasification demonstration plant at Illinois Power Company’s Wood River Generating Station. When it begins sustained operation later this year, the plant will gasify 600 tons (544,320 kg)/day of coal, producing clean low-Btu gas to fuel an existing 50 MW boiler at the station. The Electric Power Research Institute has joined the program and will provide a portion of the funds for the demonstration and testing activities. During its first year of operation, the plant will concentrate on the gasification of high sulfur Midwestern and Appalachian coals. This paper seeks to review the design and construction of the plant, known as the KILnGAS Commercial Module, and to discuss the key aspects of the demonstration program. Successful operation of the plant will permit the process developer, Allis-Chalmers Corporation, to furnish future commercial coal gasification plants with performance and equipment warranties.

High Velocity Oxy-Fuel thermal spray systems (HVOF), also known as High Velocity Combustion systems (HVC) are high energy thermal spray combustion processes, producing very hard, high density coatings. These coatings are used in areas where high wear resistance is of particular importance, with metal carbide coatings being typical in gas turbine applications. Gas turbines use hard face coatings in such areas where vibration is the initial source of the problem. The areas tend to be in the hot end of the gas turbines although certain areas of the cold end are also affected. To date the hard face coating that has been predominately applied in gas turbines particularly in the hot end, is the Praxair (Union Carbide) “D” gun coating. As a result to date, the “D” gun system has had a virtual monopoly with regards to the overhaul/repair of gas turbine components where hard face coating was required. However new HVOF systems have come on to the market Examples are: CDS, Plasma Technik; Diamond Jet, Metco; Top Gun, UPT U.K. (Miller); Jet Kote, Deloro Stellite; Gun. Metallisation and JP 5000, Hobart Tafa. As a result gas turbine overhaul bases are now in a position to offer a more competitve coating service, producing comparable, and in some cases superior, coatings to those produced by the “D” gun process. This paper covers, from the Rolls Wood Group point of view, the developments of the HVOF systems, where they appear to be today and how these systems, now allow overhaul bases to offer services not previously available and the ability to develop new coating applications.

Atmospheric gasification of wood powder in a cyclone has been studied. A cyclone gasifier has been designed where the wood powder is injected into the cyclone with air or air/steam as transport media. The effects of stochiometry and steam injection on the gasification temperature and gas composition are investigated. The experimental results are compared with theoretical equilibrium calculations. The fuel flow has been 26 kg/h corresponding to a thermal input of 140 kW. Equivalence ratio was varied between 0.15 and 0.4. Wood powder has been injected with steam mass flows of 50–80% of the fuel flow. The gas from the cyclone gasifier was analysed regarding CO, H 2 , CH 4 and CO 2 . The lower heating value of the gas varies between 4 and 6 MJ/Nm 3 with lower values for steam injected gasification. Compared to theoretical calculations the air/steam injected measurements showed better agreement with equilibrium predictions than only air injection.

Considering the expected climate change biomass is one of the promising energy sources for the future; however, burning and only producing low temperature heat means wasting exergy. To utilize this renewable fuel highly efficient cogeneration plants are required. Existing small and medium sized power generation systems using gas turbines have either complicated flow sheets or problems with charging pressurized combustion chambers, which are not yet solved. This project deals with the investigation and the development of an atmospheric biomass combustion chamber combined with an inverted gas turbine cycle followed by a steam cycle. The system consists of a combustor with a wood grate firing working at atmospheric pressure. A gas turbine expands the hot particle loaded exhaust gas with a temperature of about 800 to 1000°C from atmospheric pressure down to a pressure of about 0.35 bar. The exhaust gas of the turbine is used for operating a single-pressure steam generator, the steam is mainly utilized for power generation in a steam turbine, a part stream is used to control the gas turbine inlet temperature depending on the moisture content of the fuel. The gas outlet temperature of the steam generator is about 186°C (Fig. 1, p6) at a pressure of 0.3 bar, one part is used for preheating the air required for combustion, the other part is cooled down by water injection, whereby ashes and particles are separated. The cleaned gas is compressed to atmospheric pressure again (Moser, 1995). Such a system can achieve an efficiency of up to 40 % in the MW electricity range using components, which are available on the market, and at the same time it demonstrates the possibility of highly efficient biomass utilization.

A new concept for direct combustion of wood in a gas turbine is presently developed and tested in Sweden. The process is based on a fuel rich cyclone gasifier/separator and a direct coupled modified standard gas turbine combustor. A main concern is the behaviour of ash forming elements in the turbine. A picture of this can be obtained with chemical equilibrium calculations. The objective of the present work was to determine the equilibrium speciation of the ash forming elements from wood passing through the turbine of a gas turbine engine for varying feed characteristics and operating conditions. In addition, the differences between using only stoichiometric and using non-ideal solution models as thermodynamic input data were illustrated. The equilibrium relationships at the turbine stage were evaluated in a parametric study, utilizing statistical experimental designs to systematically perform the model calculations. A wide range of operating conditions, wood compositions and cyclone elemental retention efficiencies were thereby covered. The results show considerable variation in the alkali speciation as well as in devolitalization and condensation temperatures, depending on the elemental composition. Plots of the effects of the most influential variables are presented and results not directly displayed in this work are illustrated with model equations provided.

World is now endangered by the threat of fuel source scarcity and environmental degradation. Researchers all over the world are searching for the alternative energy resources to supplement the present energy needs and to conserve the conventional resources from depletion which are less costly and environmentally friendly. Harnessing the wind power and its utilization is one of the best possible answers. Investigations for recent years have revealed that wind energy has been the great deals to the rural farmers for their water pumping. Wind power can be used effectively in maintaining livestock, water supply, fish & ice farming, water desalination, sawing wood, irrigation, electrification, agricultural operations etc. If all possible considerations are given in exploiting wind energy, in the coming 4 to 5 decades it can meet 30% to 45% of the world’s total energy demand contributing no unwanted emissions into the atmosphere. It can adjust more jobs and occupies fewer lands. It is cheaper than any other sources. Bangladesh possesses flat terrain, hilly & mountainous regions, open river banks & harbors, and a vast lengthy coastal belt by the sea “the Bay of Bengal” where reasonable wind flow round the year available. For most of the said areas, electricity supply from the mother grid is almost inaccessible due to various difficulties and limitations. Moreover, a total of 2105 MW national generation capability absolutely unable to meet the present suppressed peak demand of 2114 MW for the consumers already in the grid. This continuously causing a severe regular load shedding up to 30% of the peak demand. The large sized population of the above areas is being maintained over decades mostly from fuel wood, charcoal plant & agricultural residues, dung and very few from imported petroleum and derivatives as the only energy sources. The energy scarcity let the locality remained economically backward and noncontributing to the GDP. In some of the areas namely Chittagong Harbor, Coastal belts & City periphery, from recent observations the monthly mean wind speeds (m/s) ranging between 4.5 and 8.5 are recorded which show the genius prospect of reaping wind power in Bangladesh. Despite a promising future of this free fuel, benefits for utilizing this energy in Bangladesh are being missed because too little is known about either the resource or the technology. Wind energy can successfully be utilized in utility for supplementing our generation and to meet decentralized needs or wind-solar hybrids for Bangladeshi modern multistory buildings which are now meeting their energy deficit by individual diesel generators at higher money and environmental costs. In the context of Bangladesh, wind power to come to use, this paper is an attempt to describe the methodologies for site selection; wind data collection & regime modeling; power availability, conversion & storage; turbine performance monitoring & augmenting wind speed using cloth scoops including costs and environmental impact Assessment. This paper also discusses Bangladesh energy scenario and strategies for meeting deficit demand and summarizes global wind development and proposes that Bangladesh government and other agencies must take immediate initiatives towards implementing wind projects.

The kraft process dominates pulp and paper production worldwide. Black liquor, a mixture of lignin and inorganic chemicals, is generated in this process as fiber is extracted from wood. At most kraft mills today, black liquor is burned in Tomlinson boilers to produce steam for on-site heat and power and to recover the inorganic chemicals for reuse in the process. Globally, the black liquor generation rate is about 85,000 MW fuel (or 0.5 million tonnes of dry solids per day), with nearly 50% of this in North America. The majority of presently-installed Tomlinson boilers will reach the end of their useful lives during the next 15 to 20 years. As a replacement for Tomlinson-based cogeneration, black liquor-gasifier/gas turbine cogeneration promises higher electrical efficiency, with prospective environmental, safety, and capital cost benefits for kraft mills. Several companies are pursuing commercialization of black liquor gasification for gas turbine applications. This paper presents results of detailed performance modeling of gasifier/gas turbine cogeneration systems using different black liquor gasifiers modeled on proposed commercial designs.

Considering the expected climate change, biomass is one of the promising energy sources for the future. However, burning and only producing low temperature heat means wasting exergy. To utilise this renewable fuel, highly efficient cogeneration plants are requierd. Existing, small and medium sized power generation systems using gas turbines, have, either complicated flow schemes, or problems with fuel charging of pressurised combustion chambers, which are yet to be solved. Here is a solution is presented requiring no preparation of the biomass fuel. In several publications (Jericha 1991, Fesharaki 1995, Fesharaki 1996) the inverted gas turbine cycle has been presented. This project deals with the investigation and the development of an atmospheric biomass combustion chamber, combined with an inverted gas turbine cycle. The system consists of a combustor with wood grate firing, working at atmospheric pressure. The exhaust gas from the combustor, with a temperature of 1050 °C, is cooled by water or steam injection, to a temperature of 730 °C. The exhaust gas is purified in a cyclone and expanded in a gas turbine to a pressure of 0.3 to 0.4 bar. The exhaust gas of the turbine can be used for operating a single-pressure steam generator, and for district heating. The exhaust gas is purified again by condensing the moisture in the exhaust gas, which stems from the biomass and the steam, or water injection after the combustion chamber. The purified gas is recompressed to atmospheric pressure, which is used for combustion-air preheating. With such a system a high electrical efficiency can be achieved, dependent upon the turbo machines, and the use of an additional bottoming steam cycle. Considering the Austrian situation a feasibility study is being carried out. Special attention has been paid to: Turbine design, Exhaust gas purification, and the cycle control. The feasibility study shows, that this concept is practicable, and that several biomass existing heating systems in Austria could be converted for production of electricity.

Sawmills in the Canadian province of British Columbia (BC) will soon be confronted with a collective wood waste disposal problem (bark, sawdust and shavings) of about 3 Million bone dry tonne/y at an average wet basis moisture content of about 45%. About 40 existing sawmill beehive burners presently incinerate this waste. Emissions from these beehive burners exceed current provincial particulate limits. Markets for the waste — board plants, sawdust digesters, charcoal plants, etc. — are limited. The economics of 25 to 50 MW wood-fired, steam power plants is poor. 6¢/kW.h is needed to finance a plant; the major utility offers 2¢/kW.h. This paper describes a 3 MW to 5 MW, Nuovo Pignone PGT-5 co-generation plant fuelled by the 2000°F (1093°C) exhaust from a Heuristic EnvirOcycler, a two-stage, wood waste incinerator. The exhaust meets BC’s particulate limit of 0.052 grains/dscf (120 mg/Nm 3 ). 37 to 65 Million Btu/h (39 to 68 GJ/h) of waste heat can be recovered from the system exhausts. In this application the PGT-5’s external combustion chamber is replaced by a “recuperator”, i.e., a high temperature, gas-to-air, heat exchanger. Two variations of the basic system are examined. One features a larger than necessary EnvirOcycler to generate additional steam in the waste heat boiler. The other variation discusses heating 1,550°F (843°C) air from the recuperator up to 1,796°F (980°C) with natural gas. The extra power generated can cost as little as 1.9¢/kW.h.

Biomass is a fuel of increasing interest in power generation since it is clean and renewable. Besides conventional power generating systems biomass fuel will be utilized in Integrated Gasification Combined Cycle (IGCC) power plants in the near future. Carbona Inc. (the successor to Enviropower Inc.) is commercializing a biomass fueled IGCC system. This system is based on a simplified IGCC process which applies the gasification technology originally developed by the Institute of Gas Technology (IGT) and further developed by Enviropower before licensing the technology to Carbona and an advanced hot gas clean-up system. An extensive pilot test program has been carried out by Enviropower/Carbona covering all aspects of a biomass based gasification process. More than 5000 tons of different biomass feedstocks have been gasified at the pilot plant in Tampere, Finland. The pilot plant converts 15 MW (51 MMBtu/h) thermal input of fuel to product gas. Several biomass qualities/mixtures have been used during the test runs including hard wood, soft wood with and without branches, needles and bark. Short rotation biomass like willow and alfalfa have also been tested. This paper concentrates on the results and differences in gasification of different biomass materials with special emphasis on the suitability of product gas for gas turbines, the fate of ammonia, vapor phase alkali metals and air toxics. The development of demonstration projects is also discussed in this paper.

One of the main limiting factors when a green field pulp mill intends to increase its production is the capacity of the Tomlinson boiler by which the cooking chemicals are recovered. Since a boiler of this kind has a service life of some thirty years and represents a substantial investment, it is not an easy decision to replace it for a minor production increase. This study takes a novel approach to the problem. The excess black liquor is assumed to be recovered in a black liquor gasifier, an emerging technology for alternative black liquor recovery. Black liquor gasification in itself has been studied considerably during the last decade. In this study it is combined with the gasification of biomass, i.e. bark and wood, which is already available at a pulp mill. The resulting hybrid energy system, with a gas turbine and a gas expander, offers interesting possibilities: good off-design performance and high efficiency with respect to the fuel quality.

A new generation of small scale (less than 20 MWe) biomass fueled, power plants are being developed based on a gas turbine (Brayton cycle) prime mover. These power plants are expected to increase the efficiency and lower the cost of generating power from fuels such as wood. The new power plants are also expected to economically utilize annual plant growth materials (such as rice hulls, cotton gin trash, nut shells, and various straws, grasses, and animal manures) that are not normally considered as fuel for power plants. This paper summarizes the new power generation concept with emphasis on the engineering challenges presented by the gas turbine component.

Biomass integrated gasification-gas turbine (BIG-GT) technology offers the opportunity for efficient and environmentally sound power generation from biomass fuels. Since biomass is ‘carbon-neutral’ it can be used in power generation equipment without contributing to the ‘greenhouse effect’ if it is grown sustainably. The Brazilian BIG-GT initiative is one of a number of initiatives world-wide aimed at demonstrating, and thereby establishing, biomass as an energy resource for power production. The goal of the Brazilian BIG-GT project is to confirm the commercial viability of producing electricity from wood through the use of biomass-fuelled integrated gasification combined-cycle (BIG-GT) technology. To fulfil this goal a 32 MWe eucalyptus-fuelled demonstration power plant will be built in Brazil on the basis of a design made by TPS Termiska Processer AB (TPS). The first two phases of the project, which included experimental and engineering studies and the basic engineering of the plant, were completed in 1997. The next phase of the project, the construction and commissioning of the plant, is the recipient of a U.S. $35 million grant from the Global Environmental Facility (GEF) of the United Nations Development Programme (UNDP), in addition to financing from the World Bank (WB). The plant will be built in Bahia, north-eastern Brazil. The customer of the plant is a consortium, SER - Sistemas de Energia Renovável, comprising of CHESF (Companhia Hidro Elétrica do São Francisco), a federally-owned electricity generation and distribution company, Eletrobras (Centrais Elétricas Brasileiras), a holding company comprising of the main Brazilian companies from the electric generation and distribution sector, and Shell Brasil. Start-up of the plant is scheduled for the year 2000. The plant will be based on a TPS designed atmospheric-pressure gasification/gas cleaning process. The product gas will be fired in a modified GE LM 2500 gas turbine. The gasification and gas cleaning process is based on the use of a circulating fluidised bed gasifier, secondary stage catalytic tar cracker and conventional cold filter and wet scrubbing technology. The feedstock to the plant will be mainly eucalyptus wood from a dedicated plantation which is harvested on a three-year cycle. This paper describes the background of the project leading up to the technology selection, the technology that will be employed in the plant and the outline of the economics of this ‘first-of-a-kind’ plant. The progress made in establishing the organisation and the formal framework (e.g. securing the electricity and fuel contracts) are also reported. Future projections of likely technological improvements and cost reductions, and their effect on the overall economics of an ‘Nth’ plant, are presented.

The Brazilian Wood Biomass Demonstration Project (WBP) Phase II was contracted with the United Nations Development Programme - PNUD, Setor Comerical Norte, Quadra 2 - BLOCO A, EDF.Corporation-7° Andar, Brasilia - DF Brasil 70712-900 and General Electric Marine & Industrial Engines to develop the gas turbine equipment necessary to utilize fuel produced by the gasification of wood products. The program included performance studies, control specification requirements, bleed and fuel valve specifications, a modified dual gas fuel nozzle for fuel delivery to the combustor and results of two (2) combustor component tests utilizing biomass simulated fuel. This paper will deal primarily with the fuel nozzle design elements, the setup and evaluation of the component combustor tests and resulting emissions produced by the simulated Biomass fuel. Details of the combustor test arrangement, facilities and special test equipment needed to complete the evaluation will be presented. In addition, background on the two types of combustor testing will be discussed.

The co-processing of coal-biomass mixtures under inert and reducing atmospheres has been studied in a bench scale fixed-bed (‘hot-rod’) reactor. The aim was to look for evidence of synergistic effects during the co-gasification of coal and biomass. Total volatile release, tar and char yields from mixtures of Daw Mill coal and Silver Birch wood (alone and in mixtures of 25, 50 and 75 % by weight), have been determined as a function of temperature (850 and 1000 °C) and pressures (up to 25 bar) under He-pyrolysis and CO 2 -gasification conditions. The total volatile yields of mixtures have been found to match those calculated theoretically from pure coal and biomass values under all conditions attempted, thus suggesting a lack of synergy in the amount of char produced. However, char reactivity measurements in an atmospheric thermogravimetric analyser (isothermal combustion in air at 500 °C) indicate that chars of coal-biomass mixtures have higher combustion reactivities than would be expected from the reactivities of the raw fuels alone. Similarly, the tar yields from mixtures are also somewhat higher than those predicted from the individual contributions of coal and biomass.

There is an increasing interest in catalytic combustors fuelled by low-heating value (LHV) gases, with a LHV of 5–7 MJ/Nm 3 . This is because catalytic combustion could be advantageous compared to flame combustion with respect to stable combustion of LHV-gases and low conversions of fuel-N (mainly NH 3 ) to NO x . In the present project, funded by the EU Joule Programme, catalytic combustion of gasified wood for gas turbine applications is studied. A synthetic gas mixture of H 2 , CO, CO 2 , H 2 O, CH 4 , N 2 and NH 3 , that resembles the output from a fluidized bed gasifier using biomass as raw material, is used. The gas mixture is mixed with air at atmospheric pressure and combusted over washcoated cordierite monoliths in a bench-scale laboratory quartz-reactor. The objectives of the work described here are twofold. To begin with, improvement of the thermal stability of hexaaluminate washcoats by substitutions of rare earth or transition metal compounds is being studied. Secondly, catalytic combustion of gasified biomass over these washcoats has been studied in a bench-scale unit. In this on-going project, obtained result show that it is possible to improve the surface area of hexaaluminate compounds up to 17 m 2 /g after careful synthesis and calcination up to 1400 °C for four hours. The selectivity of NH 3 -conversion to N 2 is at present at 60 percent, but varies strongly with temperature. Fuel components such as H 2 , CO, C 2 H 4 and NH 3 ignite at temperatures close to compressor outlet temperatures. This means that a pilot-flame may not be needed for ignition of the fuel. A comparison between a Pd-impregnated lanthanum hexaaluminate and a Mn-substituted lanthanum hexaaluminate showed that the ignition temperature and the NO x -formation varied strongly over the two different catalysts.