00742 Cofiring coal-water slurry fuel with pulverized coal as a NOx reduction strategy

15

optimal thermal unit commitment. This paper first introduces the general unit commitment scheduling problem and then discusses various considerations, objective functions and different techniques to solve the problem. Finally, recent trends in research on unit commitment are also discussed.

Performance study of a double-absorption water/ calcium chloride heat transformer

99i90734.

Barragan,

R. M. et al.

(9), 791-803.

International Journal of Energy Research, 1998, 22,

There are other possible arrangements in order to increase the temperature lift and efficiency of single-absorption heat transformers. Double-absorption heat transformers have a relatively simple design and smaller size compared to two-stage heat transformers. In this work, the thermodynamic performance of the water/calcium chloride system was modelled for a double-absorption heat transformer. Results indicate that temperature lifts of up to 40°C are possible with coefficients of performance close to 0.3.

Social coet pricing of fossil fuels used In the -736 production of electricity. lmplicatlons to biomass feasibility K. D. and English, B. C. Making Bus. Biomass Energy, Environ., Chemical, Fibers Mater., Proc. Biomass Conf Am., 3rd, 1997, 2, 1455-462.

Dillivan,

Biomass is not as economically efficient as various other fossil fuels given the current fossil fuel cost structure and the lower heat content of biomass even though it is a cleaner burning fuel. For energy producers biomass consumed alone or co-fired with a fossil fuel may represent a cost minimization scenario. Energy market inefficiencies and market barriers prevent biomass from being used by electricity producing power plants; if these inefficiencies are correct and barriers removed, biomass would be used as an energy source to a greater extent. This is the major hypothesis to be tested in this study.

12

(pollution, health protection,

safety)

14 HEAT PUMPS 99lOO736 On the combination steam turbine

of heat pump with solar

Drabkin, L. M. Renewable Energy, 1998, 13, (2), 269-272. Presented in this paper is the thermodynamic analysis of the heat pump with solar steam and gas turbines.

99/00739 Johnson, P.

The Inverted heat pipe

Heat Pipe Technol.: Theory, Appl. Prospects, Proc. Int. Heat Pipe Symp., Sth, 1997, 164-167. Edited by Andrews, J., Akbarzadeh, A. and Sauciuc, I. In England, humorists have often suggested that everything in Australia is an inverted version of what happens in England. To the thermodynamicist this would be seen immediately as an attractive proposition because it hints at the possibility of reversibility and reversible is expected to be best. If there could be a fully effective heat pipe that worked with top, rather than bottom, heating, the possibilities for capitalizing on the thermal superconducting characteristics of heat pipes would be significantly expanded. The ability for a long heat pipe to operate with liquid return against gravity would contradict the popular expectation that ‘heat rises’, as heat that had risen could be easily brought down again. A particular need in an inverted heat pipe is for liquid working fluid to be returned from the condenser upwards against gravity to the evaporator through whatever height the length of the heat pipe represents. As a step towards developing a practical inverted heat pipe, some aspects of the thermodynamic of this process are explored theoretically.

15 ENVIRONMENT

REFRACTORIES/ CERAMICS Properties, production,

Environment

Pollution, health protection, applications

safety

Alternative blo-based fuels for aviation: the clean airports program

99/00740

M. G. Making Bus. Biomass Energy, Environ., Chemical, Fibers Mater., Proc. Biomass Conf. Am., 3rd, 1997, (2), 1171-1181.

Shauck, M. E. and Zanin,

Wall ceramic materlals ashes from Kansk-Achinsk coals

99iW736

based on high-calcium

Shil’tsina, A D. and Selivanov, V. M. Izu. Vyssh. Uchebn. Zaved., Stroit., 1997, (ll), 52-55. (In Russian) Experimentally demonstrated was the possibility of using high-calcium ashes from Kansk-Achinsk coals for manufacturing construction materials, particularly bricks. Good quality facing a?d regular bricks were prepared by using the high-calcia ashes in proportion of 30 and 50% in the charges of conventional raw materials.

13

SPACE HEATING COOLING

AND

Use of inertance In orifice pulse tube refrigerators 99l99737 Gardner, D. and Swift, G. Cvogenics, 1997, 37, 117-121. The oscillating velocity in efficient Stirling-cycle cryocoolers leads the oscillating pressure at the hot end of the regenerator, and lags behind it at the cold end. In single-orifice pulse tube refrigerators, the velocity leads pressure at both ends, resulting in lower efficiency. The phase shift between oscillating pressure and oscillating velocity at the cold end is determined in part by the purely resistive nature of the ‘orifice’ of the orifice pulse tube refrigerator, so that the pressure difference across the orifice is in phase with the velocity through it. We show that the phase shift between velocity and pressure can be shifted to the more efficient Stirling values by adding an ‘inertance’ in series with the orifice. Use of an inertance is significantly beneficial only when the gross cooling power is sufficiently large.

Edited by Overend, R. P. and Chornet, E. The position of national co-ordinator of the Clean Airports Program has been given to the Renewable Aviation Fuels Development Center at Baylor University in Waco, Texas. This program, a spin-off of the Clean Cities Program, was initiated to increase the use of alternative fuels in aviation. The two major fuels used in aviation today are the current piston engine aviation gasoline and the current turbine engine fuel. The environmental impact of each of these fuels is significant. Aviation gasoline, currently used in the general aviation piston engine fleet, contributes 100% of the emissions containing lead in the US today. Turbine engine fuel produces two major environmental impacts: a local one, in the vicinity of the airports, and a global impact on climate change. The Clean Airports Program was established to achieve and maintain clean air at and in the vicinities of airports by using alternative fuel-powered air and ground transportation vehicles.

99/00741 system

Analysis

of hot gas cleanup

for China IGCC

Li, C. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (5), 27-33. An important role is played by coal in China. But the wide utilization of coal for power generation has resulted in great environmental problems. Integrated coal gasification combined cycle (IGCC) systems are considered to be one of the most promising available processes toward reducing contaminants to very low levels. This paper will review mainly achievements and experience on hot gas cleanup employing in the IGCC system abroad. From the view of hot gas cleanup development and research in China, the two stage desulfurization processes and two kinds of desulfurization processes and two kinds of desulfurization sorbents were suggested. From the viewpoints of economics and available technology the selectivities of temperature ranges as well as the types of reactors for the requirement of hot gas cleanup were systematically put forward.

Coflrlng coal-water slurry fuel with pulverized coal as a NO,, reduction strategy

99lOO742 Miller,

23-36.

B. G. et al.

Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (23).

From impounded bituminous coal fines a low solids, low viscosity coalwater slurry fuel (CWSF) was formulated and produced and burned in a utility-scale boiler to investigate NO, emissions reduction during the cofiring of CWSF with pulverized coal. Two Babcock & Wilcox pulverizers feed coal to six burners (two burner levels each containing three low-NO, burners). Approximately 20% of the thermal input was provided by CWSF, the balance by pulverized coal. There was a significant reduction of NO,

Fuel and Energy Abstracts

January 1999 73

15 Environment (pollution, health protection, safety) emissions when cofiring CWSF and pulverized coal as compared to firing 100% pulverized coal. The level of reduction was dependent upon the cofiring configuration, with NO, emissions being reduced by as much as 26.5%. The reduction in NO, emissions was not due to the tempering effect of the water in the CWSF, because a greater reduction in NO, occurred when cofiring CWSF than when injecting the same quantity of water at the same boiler firing rate. This paper discusses the tests in detail and the proposed reburn mechanism for the NO, reduction.

Consumption of fossil fuels. How reliable are 99199743 scenarios of anthropogenic carbon dioxide emissions? Berner, U. et al. DGMK Tagungsber., 1998, 9801, 43-47. (In German) The Bundesanstalt for Geowissenschaften und Rohstoffe (BCR), Germany carried out a reassessment of anthropogenic COz emission by combustion of fossil fuels comprising coal, natural gas, and crude oil. It was based on statistical data from the BCR data bank covering the fuel production and consumption in the period 1840-1996. The results were compared with former assessments carried out by the Intergovernmental Panel of Climate Change (IPCC). The evaluated COz emission by the BCR for the eighties was 1.0 GtC/yr lower than the emission values from the IPCC and corresponds with the ‘Missing Carbon Sink’, IPCC Report 1995. Other deviations from the evaluated COz emission were caused by unexpected changes in the world economy and their impact on the fuel consumption.

Effect of co-combustion of biomass on emissions in pulverized fuel furnaces

99100744

Spliethoff, H. and Hem, K. R. G. Fuel Process. Technology, 1998, 54, (l3), 189-205. Biomass shows a reasonable cost level in comparison to other renewable energies as well as having a considerable potential as an additional fuel source. The fuel types are both residual material from forestry and agriculture, such as wood or straw, and especially cultivated reproducible feedstocks. As single fuel, it is also considered to be sensible to utilize biomass in co-combustion in existing firing systems, such as pc-fired power stations. The European Union, in order to promote the biogenetic fuels, within the framework of the APAS Clean Coal Technology Program, has initiated a research project concerning the co-combustion of biomass in existing firing systems. The focus of the investigations in experimental and industrial-scale plants was to establish the impact of co-combusting biomass and sewage sludge in coal-fired systems with regard to combustion behaviour and pollutant formation. The task of the Institut fur Verfabrenstechnik und Dampfkesselwesen (IVD), University of Stuttgart, within the EU clean coal technology program, was to investigate the effects of cocombustion of solid biomass (Miscanthus, straw) and municipal sewage sludge together with the primary fuel hard coal. The experimental plant used was a semi-industrial pulverized fuel test rig (0.5 MW). In this publication, a synopsis is given of the outcome of the project, with special regard to the effect of co-combustion on emissions. The investigations reveal that biomass addition has a positive effect on emissions. Since biomass in most cases contains considerably less sulfur than coal, an increasing biomass share in the thermal output makes the SO* emissions decrease proportionally. As for sewage sludge, the emissions of SO2 correlate with the sulfur content of the fuel and hence rise with an increasing share of this biomass. Low NO, emissions can be achieved both by air staging and by reburning due to the high volatile content of the biomass.

Environmental emission mitigation efficient electrical appliances In Sri Lanka

99100745

Environmental impact of the energy recovery of scrap tires in a cement kiln

99100746

Carrasco, F. et al. Environ. Technology, 1998, 19, (5). 461-474. At a cement plant which produces one million tons of cement per year the study of the impact of the use of scrap tires as a fuel substitute with respect to gaseous emissions was conducted. This study was conducted through the modelling of the atmospheric dispersion of contaminants emitted with the use of the ISC-ST2 software put forth by the United States’ Environmental Protection Agency. The entry data required by this Gaussian model were the meteorological data, the characteristics of the source and the pollutants, the data relating to the buildings downwash effects and the location of the receptors. The simulation of the atmospheric dispersion of pollutants allows for the evaluation of daily and annual maximum concentrations as well as the localization of the latter, which is done just as easily at a cement kiln operating with coal only or with a combination of coal and scrap tires. The analysis of the results obtained shows whether the incorporation of tires

Fuel and Energy Abstracts January 1999

EU clean coal technology-co-combustion and biomass

99100747

of coal

Hem, K. R. G. and Bemtgen, .I. M. Fuel Process. Technology, 1998,54, (l3), 159-169. The application of regenerative energy sources should be advanced in order to reduce COz emissions in addition to a more economical use of fossil fuels. One of the alternatives considered to decrease the net emissions of CO2 are the cultivation and combustion of solid biomass, or the thermal utilization of sewage sludge. In order to achieve a noticeable COz reduction, as well as fossil fuel substitution, it is desirable to use fairly large quantities of biomass for energy production. However, an exclusive biomass utilization would consequently lead to the construction of many decentralized plants, which is time-consuming and would require high financial investments as well as large storage capacities due to the seasonal fuel availability. Co-combustion, in contrast, is considered to be a cheap option for utilizing the existing biomass resources. For these reasons, an EU-project, ‘Combined Combustion of Biomass/Sewage Sludge and Coals of High and Low Rank in Different Systems of Semi-industrial and Industrial Scale’ was launched in 1993. Partners from eight European countries investigated the effects of burning sewage sludge, agricultural residuals, such as straw and manure, as well as especially cultivated energy plants in combination with coals of vanous ranks and origin. Both the pulverized fuel and the fluidized bed mode were tested, ranging from laboratory rigs to large scale utility boilers. This paper provides an overview of the activities of the various partners involved and will, in particular, show the synergetic co-operation towards a common aim. Summarized are the results of the 2-year project.

Further experience improvement in fossil fuel combustion

99100746

for

environmental

Lazzeri, L. and De Santis, R. Proc. Am. Power Conf., 1998, 60, (l), 187195. Reviewed are the most recent Ansaldo Energia achievements in emission control via combustion modifications, with emphasis on NO., CO, and particulate emission reduction from oil-, gas-, and coal-fired boilers.

99ig9749 Gaseous pollutant emission gasification In a steam-fluldized bed. 1. Exper%% on pollutants formation and sulfur capture

s~.$

Zhao, F. et al. Huanjing Kerue Xuebao, 1998, 18, (3), 225-229. (In Chinese) On a steam fluidized bed gasifier with a diameter of 160mm the yields of the principal pollutants including hydrogen sulfide, ammonia and hydrogen cyanide were measured. The effects of operating conditions, such as grade of coal and bed temperature on the yields were determined. The sulfur capture via the HzS-CaO reaction in a reductive atmosphere with high concentration of steam in the fluidized bed was investigated. Comparisons of the yields of HzS between presence and absence of limestone was conducted to obtain the efficiency of sulfur capture. The effects of bed temperature and Ca/S ratio on the extent of sulfur capture were also determined.

potential of

Shrestha, R. M. et al. International Journal of Energy Research, 1998, 22, (lo), 923-933. Assessed in this study is the techno-economic potential of selected efficient demand-side appliances to mitigate emission of air pollutants from the power Sector of Sri Lanka. The study shows that from the technical and economic perspectives a total of about 38,646 GWh and about 25.6%, 34.2% and 34.6% of the total CO*, SO2 and NO, emission, respectively, could be avoided during 1997-2015 with the use of the efficient appliances. The generation savings from utility and user perspectives and emission mitigation potential are, however, significantly smaller as all the selected appliances are not found cost effective from these perspectives. This is mainly because electricity prices in the commercial and industrial sectors exceed the corresponding long-run marginal cost of electricity supply.

74

leads to an increase or a decrease in the concentration of pollutants: particulate matter, non-condensable gases, metals, hydrogen chloride, and semi-volatile compounds. Finally, it is possible to determine if the energy recovery of scrap tires used by a cement kiln meets environmental standards.

Greenhouse gas reduction through the use of high performance power systems (HIPPS)

99/00750

Robson, F. L. et al. (Am. Sot. Mechanical Eng.), 1997, 5, (l), 345-350. Identified were advanced high-performance power systems (HIPPS) which offer the potential of reducing greenhouse gas emissions, mainly COz, by as much as 50% compared to current coal-fired stations. The HIPPS were based on either frame-type or aerodynamic gas turbines which receive up to two-thirds of their thermal input from heat exchangers located in a coalfired high-temperature advanced furnace (HITAF). The remainder of the gas turbine energy was supplied by burning natural gas to increase the temperature from the HITAF to levels needed by modern gas turbines. Advanced HIPPS with a variety of engine configurations and power cycles were analysed for use in greenfield and repowering applications. These included conventional and intercooled gas turbines used in combined cycle and humid air turbine versions of HIPPS. Depending on cycle parameters, system power generation was 200-400 MW (or more), with efficiencies of 42-55%, based on fuel higher heating value. Emissions of COz and NO, were significantly reduced because of the increased efficiencies and advanced combustion technology used.

99l90751 ldentlfication and control of NO. emissions using neural networks f;e.2;;, J. and Feldman, E. E. J. Air Waste Manage. Assoc., 1998,48, (5), The application of two classes of artificial neural networks were investigated for the identification and control of discrete-time non-linear dynamical systems. A fully connected recurrent network is used for process identification, and a multilayer feed forward network is used for process control. The two neural networks are arranged in series for closed-loop control of oxides of nitrogen emissions of a simplified representation of a dynamical system. Plant data from one of Commonwealth Edison’s coal-