A perspective on the current US Electrical Power Industry situation is provided. The main topics are : Most of the large increase in US generation capacity over the past 40 years was accomplished in several major building time periods that includes a surge of combustion turbine/combined cycle capacity during the past three years Future annual peak and total energy growth is expected to be less than in the past five years. Natural gas pricing was low for the past 10 years, but may become more expensive in the future. Coal and nuclear fuel prices have declined and are expected to be remain nearly constant in the future. US Environmental Agency mandated emissions reductions have substantially reduced the environmental impact of new and existing units. However, the trend for future additional reductions continues; especially for mercury and small particulate emissions. Currently there are a significant number of transmission lines operating near capacity. Eliminating these capacity restrictions is important to electricity supply reliability and pricing. Current generation reserve margins and diversity of supply should result in reliable service and slow rates of electricity price increases.

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The emission control during coal combustion and waste incineration is imperative for the development of clean coal technology and clean waste incineration technology. In this paper, the latest advances at the Institute for Thermal Power Engineering of Zhejiang University in this field are reported. The reported achievements are concentrated on the following aspects : SO_2 and NOx formation and control during pulverized coal combustion; organic pollutants emission during coal and waste combustion and trace elements emission and control during coal combustion.

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At the beginning of the (21)^<st> century, the author considers it a high time to make a deliberate study to prospect how power plants will change and going to be over the coming time period of 100 years or more. By imaging the future style of power plants, it will become clear what we should do right now. Thermal power plants will still play an important role even in the (21)^<st> century. However, as long as fossil fuels are used, they will be under strong influence of the quantity and availability of fossil fuels. When fossil fuels are all consumed, thermal power plants are no more possible. Therefore, we should develop technologies to give maximum power with minimum fossil fuel consumption, namely, technologies of highest energy conversion efficiencies. And as fossil fuels become less and less as time passes, determination of priority in usage will be necessary, and shift to sustainable energy must also be considered. In addition to these, environmental issues including global climate change is also an important issue for power systems engineers to consider. Proper scientific and engineering understanding is necessary. This paper will summarize these broad and important items for power plant engineers to consider and solve.

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Recent Japanese industries have been drastically changing the industrial structure due to the deregulation of the Electric Utility Law. The first phase has been deregulated in 1995 for wholesale power business, the second phase in 2000 and third phase is on 2004 and 2005 respectively for partial liberalization in retail power markets. And Independent Power Produces (IPP) or Power Producer Suppliers (PPS) have been emerging in the Japanese power industries. In such circumstances, distributed resources (DR) systems such as micro-gas turbine wind-mill and etc, have been discussing to spread then to the customers. Especially combined heat and power (CHP) system are of high interested items for higher efficiency than conventional power units. Further combined heat, information and power system (CHIPS) is highest concern to spread the DR system as represented to the demonstration project in Hachinohe city. This paper is described over view of these items.

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In the new era of mounting awareness of sustainable development, the distributed power generation is become one of energy system alternatives under consideration. This paper deals with a cost model of distributed power generation. An office building distributed energy system located in Beijing is investigated as a sample of the model. In line with the office building's energy demand profile and the characteristics of Beijing local electric network, an economic feasibility study on the distributed power generation at a competitive electric market structure is presented.

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An optimal planning method of system structure is proposed to determine kinds, numbers and capacities of equipment for an energy supply system installed in commercial and public buildings from economic viewpoint. In this method, they are determined together with maximum contract demands of utilities such as electricity and natural gas so as to minimize the annual total cost in consideration of system's annual operational strategies corresponding to seasonal and hourly energy demand requirements. A numerical study is carried out for an office building with total floor area of 15000m^2. Through the study, the following are clarified : (a) the optimal system structure for the office building; (b) the economic effects of the optimal system compared to other typical energy supply systems; (c) the influence on the optimal system structure of the future efficiency improvement and initial capital cost reduction of equipment.

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Two distributed energy supply systems with different generation efficiency were evaluated based on exergy analysis and optimized on the running cost for a few patterns of energy demand. One of the systems uses a gas turbine with generation efficiency of 30%. Saturated steam is generated in a waste heat boiler, and is used for hot water and heating, and moreover for cooling. On the other hand, another system uses a SOFC and a micro gas turbine combined system as high efficient power generator with the generation efficiency of 50%. A shortage of electric power is made up by buying from an electric power company, and a gas boiler and a refrigerator with an electrically-driven turbo compressor are also used to make up for a shortage of heating and cooling demand, respectively. As a result, the relation between the operating cost and the exergy efficiency had been clearly shown. If a gas boiler is used for heating demand, the exergy efficiency of energy supply system decreases due to low exergy efficiency of gas boiler, in spite of the higher thermal efficiency. In order to increase exergy efficiency of system, heating demand should be covered by a waste heat from generators. Moreover, operating cost reduction could be compatible with the increase of exergy efficiency of system by selling surplus power.

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The high efficient dispersed co-generation system is proposed to make our living environment, comfortable and high quality, using combined heat information and power technologies. The key technology of this system is to connect home and home with one loop of heat transfer line and to level the heat demand, using the thermal storage system, in the neighboring communities than the conventional home co-generation system. The pipe diameter of this heat transfer line is only one or two inches. The number of houses in the neighboring communities is from several dozen to several hundred. At present, the joint study of the academic, business and governmental circles have been developed to verify the control logic for leveling the heat duty of mainly hot feed-water. This paper presents the concept of this neighboring communities co-generation system compared with the ordinary heat and power supply system and also the test result of New Heat Supply Unit is described.

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Recently, the distributed energy system has spread quickly because of earth environment preservation, CO2 and NOx discharge reduction, and effective use of energy. Under such situation, Kawasaki Heavy Industries, LTD. (KHI) has newly developed 20MW class gas turbine Model L20A in 2000. The L20A is based on our own turbine design technology and its extensive long time industry experience. After a year, in October 2001,KHI has constructed a co-generation pilot plant in its Akashi Works applying the first commercial L20A gas turbine engine.

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Conventional gas engine exhaust heat absorption chiller, which is often used for space cooling, can not make temperature below -10℃, because the driving temperature of the jacket water is too low for the purpose. Although it can make temperature below -10℃ if driven by high temperature steam extracted from the exhaust gas boiler, the cooling capacity becomes very small in such a case. A hybrid refrigeration system has been newly developed to overcome this problem. The system is a turbo-charger integrated absorption system in which the compressor of 135,000rpm transfers the refrigerant from evaporator to absorber. The turbine is driven by 3 MPa vapor from exhaust gas boiler, while the jacket water, together with the spent vapor after turbine, regenerates the refrigerant. It has been proven that the capacity of the developed system is about the twice of above mentioned steam-driven conventional chiller.

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Heating value of gaseous fuel produced from waste gasification systems is as low as 1/10 of that of natural gas, and there is almost no established energy conversion methods for such low-calorific gas. In this experiment, two-step pyrolysis/reforming gasification gases made from PO film were tested by a commercial scale dual-fueled diesel engine whose displacement volume is 3331cc. Engine operation is quite steady for increase of low calorific gas supply with remarkable reduction of NO_x emission. Experimental results show dual-fueled engines are quite feasible option for efficient utilization of low calorific gases.

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For the future promotion of the co-generation systems, it is necessary to reduce initial cost and improve power generation efficiency with low NOx emission. The primary target is set to the 200 [kW] output class co-generation system whose prospective markets are office buildings and small-scale industries. To realize a low cost system, a mass-production diesel engine for a truck has been converted to a gas engine. Furthermore, open chamber lean burn combustion is adopted owing to its potential of simultaneously accomplishing low NOx and high thermal efficiency with the least complex structure. To improve thermal efficiency while maintaining low NOx, following techniques were attempted. Optimization of combustion chamber geometry Application of Miller cycle Optimization of the turbocharger These efforts have achieved brake thermal efficiency exceeding 39 [%] with a NOx emission level below 150 [ppm] (in O2=0%). This is the highest performance gained in 200 [kW] output class gas engines.

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The objective of this research is to reveal the forced convection heat transfer both in the sub-and super-critical regions near the critical point. In these regions, physical properties strongly depend on both the pressure and temperature, so that characteristics of fluid flow and heat transfer is more complicated than those for lower pressure. The study in the supercritical region relates to the new technology, which applies the supercritical pressure water to the boiling-water nuclear reactor. The other study in the subcritical region, where boiling takes place, aims to obtain the acquisition of design data of the evaporator in the refrigeration using carbon dioxide as a natural refrigerant. The heating experiment was performed for forced convection in the horizontal smooth tube with 2mm inner diameter. And heat transfer coefficient and pressure drop were measured and discussed in connection of variation of the property.

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In this study the absorption refrigeration cycle without an electric solution pump is proposed. To accomplish this cycle, porous material is introduced in a generator, which is able to keep the pressure difference between high-pressure refrigerant vapor and low-pressure solution. Then to verify the effect of capillary pumping which makes the high and low pressure without a compressor or an electric solution pump in the absorption refrigeration cycle, the evaluation apparatus was manufactured and some experiments were performed to measure the pressure and temperature difference. As a result, it was derived that the pressure difference of 3.3&acd;7.4 [kPa] and the temperature difference of 4.5&acd;14 [K] were achieved.

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This paper discussed several kinds of power cycle configuration using ammonia-water mixtures to achieve heat, power and cooling cogeneration. The benefits of these configurations are simple and inexpensive compared with Kalina cycles, and can be used as the bottoming cycle under wide range of heat source such as waste heat from diesel engine, fuel cells, and small gas turbine with temperature ranging from 150&acd;450℃. Theoretical thermodynamic simulation is made for different configurations. The relationship of the process parameters such as pressure, temperature of heat source, component of mixtures and the cycle efficiency are analyzed through numerical simulation. In this study we used a software package that we developed for high temperature ammonia-water thermodynamic properties. On the basis of the above study, we can develop parameters optimization for the design of systems using mixtures under various heat source.

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Internally Circulating Fluidized-bed Gasifire (ICFG) is composed of two chambers with different specific functions in a single furnace, one is the gasification chamber and the other is the combustion chamber. In each of these chambers, there are bed materials (quartz sand, etc.) as the fluidizing medium and they are circulating between these two chambers. Gasification residue including char is transferred from gasification chamber to combustion chamber by this bed circulation. In the combustion chamber, combustion of char supplies heat to bed materials. This heated bed materials is returned to gasification chamber and supply heat needed for pyrolysis reaction. ICFG can produce high-calorific gas from low-calorific solid fuels, such as biomass and wastes that are fed into gasification chamber, because pyrolysis gas under no-oxygen and no-nitrogen and char combustion gas are separately discharged from those chambers without mixing. Thus ICFG can realize some unique gasification process.

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In order to elaborate and predict the NO_x emission characteristics, N&roarr;NO_x of six representative single-component waste variation with bed temperature and excess air was studied in the ^(&awconint;)150mm fluidized bed. The results show paper and wood have the maximum, but rubber and plastics have the minimum N&roarr;NO_x. Fluidized bed temperature has more influence on the coal and rubber than other waste because its fuel-nitrogen chemical construction is stable, N&roarr;NO_x of every waste increases with the excess air coefficient increasing. We construct a 12×7×1 back-propagation neural network according to a lot of experiment analysis. Stop criteria MSEREG=49 could reach after 186 iterations. SCG algorithm was designed because of its good performance. The simulation results indicate approximation error between actual values and simulation value of outputs is relatively low for most patterns. This indicates BP neural network has been trained well and it has good generality capability and memory capability while in usual working parameters.

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A new distributed gasification system for solid fuels is proposed, which is named as MEET (the Multi-staged Enthalpy Extraction Technology) system. In order to realize this system, a demonstration plant of commercial scale, the MEET-II, was constructed. The capacity of the MEET-II is 200kg/h. MEET-II facility consists of a pebble bed slagging-gasifier, a gas clean-up system, a high temperature air generator and a gas engine. The pebble bed slagging-gasifier contains a fixed ceramic ball bed under an entrained flow bed. High temperature air of about 1,000℃ is used as a gasification medium in order to obtain higher calorific value syngas. Gasification and power generation tests at the MEET-II facility were conducted using powdered wood biomass as fuels. These tests demonstrated technical feasibility of the MEET-II facility.

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Refuse-incineration power generation is one of the requirements for realizing a resource-recycling-type society in response to society's need for consideration of the global environment, as well as for preventing global warming. Co-generation is undertaken as one of the important technological pillars supporting reduction of CO_2,and the combined cycle waste to energy is one such measure. The power generating system installed at the Clean Energy Center, which has been completed recently, has had some important improvements introduced in its system compared with the practical applications of the combined cycle waste to energy. One of these features is the efficient use of a pair of gas-turbine power generators, which has been realized through efforts to enhance profitability. We report in this paper what points among the others features of the Clean Energy Center, differ from those of other existing power plants of the combined cycle waste to energy.

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A waste gasification system, which is equipped with pyrolysis rotary kiln and gas cracker, is reported. After building a pilot plant first, it advanced to construction of a demonstration plant to a commercial plant, then it became possible to realize processing stabilized as a result. Moreover, much plant data was acquired. In an incinerator, after burning waste, heat recovery is performed, combustion gas is purified after that. On the other hand, in a gasification system, energy use is carried out, after purifying hte gasified gas. Since gasification is performed in a hot reduction atmosphere, a possibility that generating of high temperature corrosion and generation of dioxins are controlled is strong. Furthermore, although the amount of calories per unit capacity of the generated clean fuel gas is low, since combining with an efficient power generation system etc. is possible, the improvement in efficiency of generating electricity from waste materials is expected by using this system.

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Waste incineration is more difficult than the fossil fuel's burning because of its composition and burning behavior. Waste has some special features such as low and fluctuated heating value, high water content. In the normal operation, we should burn some auxiliary fuels. So how to make waste incineration optimization and constantly and recycle the resources economically in waste incineration system is our aim. Ningbo Fenglin Green Energy Co. Ltd has incineration lines of four zones and double track large area grates (350tons/day). They have found the relationships about steam load, waste weight, outlet furnace temperature, oxygen content, waste heating value by regulating the air flow, the thickness of waste layer, auxiliary fuel value. They also found out the action of primary air pressure and its distribution in the incineration optimization with the same primary air temperature. The paper introduces how to simple incineration process, data tables and report primary air regulation, air distribution application.

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Ambient temperature strongly influences the gas turbine performance with power output dropping by approximately 0.54% to 0.9% for every 1^0C of temperature rise. There is also a significant increase in the gas turbine heat rate value as the ambient temperature rises, resulting in an increased operating cost. As the increase in power demand often coincides with high ambient temperatures, means for power augmentation during the hot part of the day become important for independent power producers, cogenerators and electric utilities. Evaporative and overspray fogging seem to be the simplest, demonstrated and cost effective approach for recovering the lost gas turbine performance. A comprehensive review on the current understanding, analytical, experimental and field experience, of the high-pressure inlet fogging technology for gas turbine applications is presented. Outstanding issues not fully understood or explored are also discussed.

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The time-dependent unsteady flow at midspan of an axial-flow turbine rotor was investigated experimentally using a laser Doppler velocimetry (LDV) system, focusing on the influence of free-stream turbulence intensity at very low Reynolds number (Re_<out, RT>=3.6×(10)^4). The free-stream turbulence intensity at nozzle inlet was elevated from 0.5% to 9.4% by setting a turbulence-generating sheet. The time-averaged and time-dependent flows were analyzed and the effects of nozzle wake on the flow field inside the rotor were determined qualitatively and quantitatively. The flow separation occurred at the rotor suction surface even under the high turbulence intensity condition because of the low Reynolds number flow. However, the decrease in flow fluctuation was observed at the higher turbulence intensity. The turbulence in the wake region was anisotropy and it exhibited strong Reynolds stress at both the low and high free-stream turbulence intensities.

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The conjugate calculation technique is used for the three-dimensional heat transfer, internal flow, and external flow calculation of a film-cooled test blade of a modern gas turbine. The comparison with thermal index paint experiments shows that with respect to the thermal load a qualitatively good agreement of the conjugate results and the measurements can be found. The 3-D analysis permits to take into account the influence of off-design flow conditions, which lead to a shifting of the stagnation line, on the film cooling at the leading edge. The numerical simulation of the complex internal passage flow is also part of the investigation. It can be shown that a homogeneous distribution of the cooling air on the cooling holes is reached. Nevertheless, the interaction of the cooling jets with secondary flow phenomena of the passage flow can lead to cooling fluid displacement and, thus, to a local degradation of the cooling performance.

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The ultra micro turbine concept based on MEMS technology was proposed by MIT in 1997,and since then several projects have been initiated and sponsored by DARPA to facilitate development at various universities and research institutions in the US. The present authors, who belong to Gas Turbine Society of Japan, regard such ultra micro gas turbine engine systems as being crucial for mobile and environmentally friendly energy utilization technology in the future for general use anywhere in the world. This paper presents an overview of the background behind the development of ultra micro gas turbines, key technologies and applications, as well as describing our palm top-gas turbine (40mm turbine wheel diameter, 2-3kW, 14.3kg dry weight including generator, 235,000rpm, 180mm outer diameter and 335mm length) and our finger-top gas turbine test model (8mm wheel diameter, tens of W, 1,170,000rpm, 23mm outer diameter and 32mm length). These developments represent the outcome of a NEDO-backed three-year international joint research project involving cooperation among Japanese universities, institutions and private firms, together with ONERA, CIAM and VKI, from FY2001 to FY2003.

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Flow and heat/mass transfer characteristics for the array impinging jets with effusion holes are investigated and also the effects of the effusion hole depth on heat/mass transfer characteristics using protruding effusion holes are investigated. For these purposes, a naphthalene sublimation method is employed to determine local heat/mass transfer coefficients on the target surface using a heat and mass transfer analogy. A numerical analysis using a commercial program (FLUENT) is also performed to analyze the flow characteristics. For small gap distances, heat/mass transfer coefficients without effusion holes are very non-uniform due to the strong effects of crossflow and re-entrainments of spent air. However, more uniform and higher heat/mass transfer coefficients than those without effusion holes are obtained by installing the effusion holes. With protruding effusion holes, the overall heat/mass transfer characteristics are similar to those with the simple effusion holes. But the Sh values are slightly higher than those of simple effusion holes and the average Sh increases as increasing the length of the protruding effusion holes.

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In the contact section of industrial gas turbine parts, wear can be observed after normal operations. Especially, in the contact area of combustors and their fittings, such as a transition piece and a seal plate, the sever wear may occur owing to combustion vibration under high temperature. If such severe wear damage occurs, some inspections or repair can be needed. Though combustors and their fittings are subjected to high temperature condition without any lubricant, any relevant prevention has not developed yet. In this paper, wear resistance of ceramic hard coating materials, i.e. TiN, TiAlN, CrN, TiC, SiC, Al_2O_3 against various materials were tested under the condition similar to that in a gas turbine. It was concluded that the combination of Al_2O_3 coating and stellite #6B had excellent high temperature wear resistance.

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With the set-in of the 21st century, energy and environmental problems such as energy security and global warming are sparking much greater controversy as burning issues that sways the fate of human beings. One of technologies presently available to deal with these issues is combined cycle power generation facility that can enhance the efficiency of power generation. At Tohoku Electric Power Company, we successfully developed and introduced Japan's first large-capacity combined cycle power plant (Higashi Niigata Thermal Power Plant Unit 3) in 1985. Going through experience in the operation and maintenance of this plant, we set about R&D on a high-efficiency gas turbine in 1987. The Unit 4-1 train of our Higashi Niigata Thermal Power Station was constructed by applying the results of this high-efficiency gas turbine R&D program, and by applying expertise we gained from the planning, construction, operation and maintenance of the Unit 3 train.

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Mitsubishi Heavy Industries, Ltd. (MHI) has established, through wide-scale development programs, the technologies for design and materials of steam turbines with steam temperature 593℃, and has applied the steam conditions of 24.2MPa/538℃/593℃ to the large-capacity 700MW turbine, Hekinan No.3 Unit for Chubu Electric Power Co., Inc. According to further development of high-temperature design, MHI has successfully developed the 1000MW turbine, Matsuura No.2 Unit for Electric Power Development Co., Ltd. (EPDC) with a steam condition of 600℃ class main steam and reheating steam temperature for the first time in the world. Then 1000MW class high temperature units successfully entered commercial operation at Chugoku Electric Misumi No.1 (24.6MPa/600℃/600℃) and EPDC Tachibana-wan No.2 (25.1MPa/600℃/610℃). The Tachibana-wan No.2 Unit is a 1050MW cross-compound plant with the highest condition of 600℃/610℃, and started commercial operation in December 2000. This paper describes the features of design and operating experience of this unit after about two year's commercial operation.

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Over the next 20 years the installed generating capacity in the Asia-Pacific region will almost double. Market changes and environmental pressures will necessitate the need for highly-efficient and reliable generating technologies. Besides the construction of new power plants, modernization opportunities of existing steam turbines will be a necessary consideration for plant owners. Siemens Power Generation has considerable experience in the field of steam plant modernization for both fossil and nuclear power plants on our own and other manufacturers fleets. Through the integration of Siemens KWU, Parsons and Westinghouse technologies, and major technology developments, a wide range of modernization solutions can be offered to the power generation industry. This paper provides an overview of the latest proven technologies for steam turbine upgrades. The latest blading technology for high and low pressure turbines is presented. Attention is also given to rotor and casing construction for HP and LP turbines. These modernization technologies are applied to both impulse- and reaction-type steam turbines and examples of successful modernizations to turbines from different manufacturers are shown.

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This article sets forth the effect on boiler efficiency when add limestone for desulfuration in CFB boilers, it indicates influencing factors, and it quantitatively analyses incidence of each factor.

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Mitsubishi Heavy Industries. Ltd. has been developing the biomass fired bubbling fluidized bed boiler in recent years. The problem with regard to the gas emissions is that the simultaneous control of CO, NOx and dioxins is difficult, which is to say that on one hand CO and dioxins reduces in oxidized region with high temperature in freeboard, on the other hand NOx lowers in reducing region in bed. In order to reduce CO, NOx and dioxins simultaneously the air for the fuel combustion is separately fed into the furnace with four-staged air. The fluidized bed is maintained reducing zone in order to reduce NOx emission. The gas temperature rises with the secondary air injection for less CO and dioxins emissions. As a result of the boiler performance test, the emission levels of CO, NOx and dioxins are below the targeted values respectively in a satisfactory way.

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According to the characteristic of SO_2 emission from the coal-fueled boilers' flue gas, the rule of designing desulfurization device is institued on the basis of chemical reaction mechanism, thus a new multi-stage liquid curtain spay-abstersion tower is designed for studying on the rules among ratio of gas and SO_2 concentration by simulating a certain sulphur content flue gas.

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The Hitachi group has dedicated a great effort to research and development in order to meet present global environment regulations. For pulverized coal combustion, we have developed an extremely low-NOx burner (HT-NR) from our original theory of "In-Flame NOx Reduction". The second-generation burner (HT-NR2) that enhanced the effect of NOx decomposition has been applied to both Japan's domestic and overseas boilers, and has received high evaluation from all users. The latest generation burner (HT-NR3) was created and developed due to the need for high efficiency, low-NOx and easy maintenance. The HT-NR3 burners have already been put into operation in several units, worldwide. The paper will present the theory of HT-NR series and the updated results from both new installation and retrofit case.

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The purpose of this paper is to present the flow field in the 300MW tangential firing utility boiler that used the Low NOx Concentric Firing System…LNCFS. Using the method of cold isothermal simulation ensures the geometric and boundary condition similarity. At the same time the condition of self-modeling is met. The experimental results show that the mixture of primary air and secondary air becomes slower, the average turbulence magnitude of the main combustion zone becomes less and relative diameter of the tangential firing enlarges when the secondary air deflection angle increase ; when the velocity pressure ratio of the secondary air to the primary air (P_2/P_1) enlarges, the mixture of the secondary air and the primary air becomes stronger, the average turbulence magnitude of the main combustion zone increases, the relative diameter of the tangential firing becomes larger, because the OFA laid out near the wall has a powerful penetration, the relative diameter of the tangential firing on the section of the OFA to the primary air (P_<OFA>/P_1) increases, the relative diameter of the tangential firing on the section of the OFA grows little, the average turbulence magnitude becomes larger, the penetration of the OFA becomes more powerful.

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HBC imported the design and manufacturing technology of 600MW subcritical boiler with controlled circulation from Combustion Engineering Inc. of U.S.A. (now ALSTOM) in the early 1980s and designed and manufactured China's first 600MW subcritical boiler with controlled circulation in Pinwei Power Plant. With all technical indexes and performance reaching the design data, the boiler was awarded the National Golden Prize for Excellent Product in 1991. During operation, a considerable deviation was experienced between the both sides of gas and steam temperature of SH and RH. The tests revealed the cause for such deviation. The relevant optimized measures were proposed which eliminated the temperature deviation and local overheating, leading to the design of the HBC product of the second generation-#3 and #4 boiler in Panshan Power Plant. With the optimization, the boiler shows better performance.

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The hydrodynamic performance of once through boiler with spiral circuitry furnace (Benson type) spiraled around by inclined tubes, typically making a single pass around the full furnace from the hopper to the upper region where a transition is made to vertical tubes, has less been investigated. But in the academic and analytical points of view the appearance of unevenness in those parallel tubes may actually exist because of either the different tube length or the inherent gas temperature & projecting heat profiles. A special hydrodynamic calculation of the being constructed 900MW supercritical boiler in Shanghai Waigaoqiao PP has been done. The calculation is focused on determining of "Phase Change Point" under different boiler loads, which reveals the exact position of potential heat transfer deterioration in furnace. Meanwhile the instability, multivalency and pulsation of the two phases flow under partial loads have been analyzed, too. The results such as the maximum thermal deviation, the position of phase change point for heat most absorbed tubes as well as the maximum tube metal temperature in water wall tubes under different loads are shown in this paper.

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Under forced convection and atmospheric pressure conditions, heat transfer characteristics were studied using the annulus channel of a heater rod with highly-wettable surface, Improvement of phase change heat transfer under boiling and condensation process requires that either liquid heated or vapor cooled can contact a heat transfer surface more effectively, while either a vapor layer or liquid film is formed repeatedly on the surface during boiling and condensation processes. As oxide semiconductor materials are known to the highly wettable, we made a TiO_2 coated surface. The Leidenfrost temperature for the TiO_2 coated surface was higher than for the uncoated surface. Under mss flux conditions of 600-1700kg/m^2s, the heater rod surface temperature for variable power input was measured. The results for the TiO_2 coated surface showed higher heat flux where the forced convection vaporization started and larger critical heat flux than for the uncoated surface.

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In a semi technical test rig experiments were accomplished to test the dyamic behaviour of an once through heat recovery steam generator. The digital control system allowed to run experiment with predefined transients using different control schemes. The results may be summed up as follows : Load changes of the gas turbine achieved by varying the flue gas flow while maintaining the flue gas temperature are transmitted with only short delay to the water steam cycle as the heat transfer condition varies simultaneously throughout the heat recovery steam generator. Movements of the evaporation end point happen only slowly. Load changes of the gas turbine where the exhaust flue gas temperature of the gas turbine varies cause large storage or release of stored heat in the tube sheets and steam generator structure. This phenomena delays substantially the load following ability of the steam generator. A relatively long time is needed until new optimal energetic conditions are reached. Flue gas temperature changes of the gas turbine cause an important displacement of the zones of super heating, evaporation and to a lesser extent preheating in the steam generator. Conventional feed water control schemes are not perfectly apt to restrict those displacements, thus large amounts of heat are unnecessarily stored in or released from the system. This deficiency may be mended by using a feed water control concept which takes into consideration the actual need or overcapacity of heat in the tubing and structure of the steam generator. This approach permits a rapid and straight forward load change of the steam generator, with stationary conditions being quickly reached after a transient.

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This paper shows a new combustion system called KACC (Kawasaki Advanced Clean Combustion) on utilize heavy oils such as asphalt or Orimulsion directly for boiler fuel suppressing the Nox emission. The concept of this system is to realize the furnace of high temperature and strong reduction condition. Through the test carried out using 18MWth test rig, it was proved that this technology is available to keep NOx emission below 100ppm. Further more the urea solution injection method was tried for Orimulsion firing, and NOx emission was reduced by 20-30%. Three industrial boilers were constructed based on this concept. The have been operating successfully, and each NOx emission was lower than expected.

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Combustion of heavy oil C and LCO as well as kerosene and heavy oil A was investigated with high temperature air combustion technology. As decreasing air ratio, the combustion took place in the whole of furnace and the luminous flame observed in the combustion at high air ratio was diminished. The emission of NOx was drastically decreased at low air ratio because uniform temperature distribution was observed even in these oil combustion. Even in the combustion of LCO, with temperature air condition. Introduction of high temperature steam causes the reduction of NOx probably because of decreasing the flame temperature.

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In this test, a comparative analysis between Pulverized coal ash (PCA) and several general sorbent was made. It indicated that we could replace the general sorbent with PCA to economize fund, decrease the pollution of the environment and open the new way of PCA comprehensive utilization. The optimal technology condition of regeneration by the orthogonal test of contact method was studied and the character of the fire-resisting oil behind & after regeneration was analyzed.

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In this study, droplet atomization and vaporization characteristics with multi-component fuel were investigated by experimental and numerical simulation methods. Spray characteristics of multi-component fuel including spray cone angle, spray angle and spray tip penetration were analyzed from shadowgraph imaging. Numerical simulation to investigate spatial distribution of fuel-vapor concentration of each component within multi-component fuel was implemented in KIVA code. Vaporization process was calculated by a simplified two-phase region which was approximated by modified saturated liquid-vapor line. Experimental results show that spray cone angle and spray angle become larger increasing in mass fraction of low boiling point component. And spray tip penetration becomes shorter with increasing in mass fraction of low boiling point component in vaporizing spray during that is same on every with increasing in mass fraction of low boiling point component in vaporizing spray during that is same on every mixed fuel in non-vaporizing spray. From numerical simulation results, temporal and spatial distribution of each fuel vapor concentration was found to be stratification.

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The authors have conducted experimental studies to clarify the combustion characteristics of unsteady turbulent diffusion flames in relation to the soot formation and oxidation process in a DI diesel engine. In the present study, the effect of fuel vapor concentration on the process of early combustion and soot formation has been investigated using several optical measurements. Laser-induced incandescence (LII) has been used to obtain the 2-D distribution of soot particles in a sooting field. Furthermore, planar laser-induced exciplex fluorescence (LIEF) has been applied to simultaneous visualization of the liquid and vapor phases of the fuel jet in a DI diesel engine. The experimental results present the effect of fuel vapor distribution on the initial soot formation process subsequent to autoignition in addition to its spatial dependence.

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The extinction of an envelope flame at the forward stagnation-point of a liquid fuel droplet due to forced convection is numerically investigated using a quasi-steady model. The droplet is oxidizing within an air stream at atmospheric pressure and under zero-gravity conditions. Combustion is modeled using finite-rate chemical kinetics and a one-step overall reaction. Results for extinction velocity as a function of droplet diameter are presented for a n-heptane droplet in an environment at 300K. Experimental results available in the literature for various fuels, and different droplet diameters, compare well with the numerical predictions for n-heptane. A linear dependence of the extinction velocity as a function of droplet diameter constitutes the present state of knowledge. This study predicts a nonlinear dependence for small diameters (d<2mm), and a linear dependence only for large diameters(d>2mm).

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Melting characteristics of coal ash depend on coal brand. Its accurate evaluation is necessary for long-term stable operation of gasifier of IGCC. But conventional measurement of melting point is done in the mixture gas of CO and CO_2,which is not similar to actual syn gas. Moreover, the effect of gas composition on ash melting behavior has not been clarified yet. Then, it is not clear if conventional method can evaluate melting behavior in actual gasifier. In this paper, new index, named RCP, was defined to evaluate progress of ash melting behavior. Effect of reducing gas composition on ash melting behavior was also clarified. The ash of 4 brands of coal, gasified in CO_2,are examined their melting characteristics in mixed gas, whose composition was calculated by equilibrium calculation in view of syn gas. Results of melting experiments suggested that melting behavior could predict from coal ash composition.

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