- Email: [email protected]
02240 Cofiring wood waste and coal in cyclone boilers: Test results and prospectus
08 Steam raising (boiler operation/design) presented in order to evaluate the control flexibility. The results of three control problems are finally shown in order to prove the reliability of the suggested control technique.
of usable energy is generally more expensive. These high costs probably represent the main reason for the limited use of renewable energies in Germany.
Performance analysis of a small wind powered reverse osmosis plant
98102235 Kalinowski, 1997, Appl. Describes painting in
9wo2230
Infield, D. Solar Energy, 1997, 61, (6), 415-421. The performance of a small wind powered reverse osmosis plant has been assessed with a stand-alone systems analysis approach. The study is concerned with the sensitivity of operation to key parameters: wind speed, battery storage capacity and reverse osmosis operating pressure. The results of such a system analysis are shown to occasionally be inconsistent with more simplistic approaches sometimes adopted in this applications area. A provisional calculation of annual expected water delivery has also been undertaken. Detailed modelling results are presented and discussed. The paper concludes that the ideal operational pressure is not always the maximum design pressure, but can depend on the site wind speed. Since water storage is far cheaper than electricity storage, there is motivation to minimize the capacity of the battery store. The most effective battery capacity would seem to be in the range of 4 to 8 h at nominal rated load for the reverse osmosis plant, with the actual value critically dependent on wind speed at the site.
98102236 Use of sewage sludge energy in Swarzewo Ostejski, A. Gaz, Woda Tech. Sanit., 1997, 71, (lo), 370-373. (In Polish) After dewatering to moisture content 60 wt%, wastewater treatment sludge is mixed with fine coal in the ratio 1:l and used as fuel to fire a hot-water boiler (output 100 kW) at a sewage treatment plant in Swarzewo, Poland.
08
99102231 Production costing and economic analysis of power systems containing wind energy conversion systems Tripathy, S. C. et al. Energy Convers. Mgmt, 1998, 39, (7) 649-659. It is possible to generate electricity by both conventional sources (nuclear, coal, diesel, etc.) and non-conventional sources (such as wind, tidal, solar energy, etc.). There currently exists a growing interest in the nonconventional sources of energy, as they are limitless and cheap to operate and wind is one of the best potential candidates for this role. The effect of combining wind energy conversion systems (WECS) with the conventional power system is studied here. Fast transform techniques are used to determine the production costing of the combined system. An economic analysis is performed, based on the production costs, to study the benefits obtained over the lifetime of the WECS. 98102232
Simultaneous frequency and voltage control of wind-diesel power systems using energy storage
Mufti, M.-U.-D. et al. Int. J. Energy Res., 1998, 22, (3), 221-235. A new scheme for smoothing out the voltage and frequency fluctuations simultaneously in a hybrid wind-diesel system using a superconducting magnetic energy storage (SMES) unit is presented. The SMES unit located at induction generators’ terminal bus, uses local measurements for exchanging real and reactive powers simultaneously in four quadrants. Complete model of the hybrid wind-diesel SMES system is developed and is used for eigenvalue analysis and design of controllers. Computer simulation results illustrate the positive impact of the SMES unit on the quality of the supply and furthermore some modifications of the controller design are proposed.
Soclo-economic lessons from Denmark
98102233
assessment
of wind power-
Munksgaard, J. and Larsen, A. Energy Policy, 1998, 26, (2) 85-93. Results from a study on the social assessment of wind power in Denmark are reported. Using the cost effectiveness paradigm production costs for wind power are compared to reference figures for central power production based on coal and natural gas. The external production costs which arise from the emissions of COz, SOz and NO, from combustion of fossil fuel and from noise and visual effects from wind mills are added to the internal costs. The macro-economic effects on employment and the balance of payments from investing in a 1000 MW wind power development which is about double the total capacity of the present Danish level are considered. Taking into account the Danish obligation of reducing COz emissions by 20% in 2005 compared to 1988, the main result of the investigations is that the environmental benefits of wind power are so significant that from a socio-economic point of view wind power and natural gas power are equal. Having a coal-fired power plant as the reference technology, wind power is more advantageous.
Others, including Development, Economics 98102234
Provlding low-temperature heat with renewable energies. An energy economical comparison
Lux, R. and Kaltschmitt, M. Erdoel, Erdgas, Kohle, 1998, 114, (l), 31-37. (In German) The possible use of renewable energies is discussed with great interest for the provision of heat and electricity in Germany. Although they offer advantages in environmental aspects, their actual use is very small. The aim of this paper is make a comparison between the costs of providing lowtemperature heat from renewable energies such as solar radiation, geothermal energy, and biomass with those from fossil fuels. The results of this comparison show that the use of renewable energies for the provision
202
Fuel and Energy Abstracts
May 1998
System for utilising volatile air pollutants as fuel C. and Romanski, T. Pal. PL 172,365 (Cl. ClOKl/OO), 30 Sep 301,165, 23 Nov 1993, 4 pp. (In Polish) a system for catching volatile pollutants generated during various paint shops and utilizing them as fuel.
STEAM RAISING Boiler Operation/Design
9wo2237 Apparatus for dust-charged wet-type desulfurization of coal-fired boiler flue gases Yokosuka, T. et al. Jpn. Kokai Tokkyo Koho JP 09 57,054 [97 57,054] (Cl. BOlD53/50), 4 Mar 1997, Appl. 951217,096, 25 Aug 1995; 7 pp. (In Japanese) This apparatus provides a means for removing coal dust and mist from gaseous effluents of a coal-fired boiler flue gas desulfurization system using a crimped plate mist eliminator. The mist eliminator may be equipped with grounded electrode plates, corona-discharge electrode wires for trapping mist, and means for washing the deposits of electrically charged dust from the crimped plate in a gas passage partition plate perpendicular to the gas flow. Smoke formation is prevented and dust removal increased with this apparatus. 9WO2238 Ash behavior In a CFB boiler during combustion of coal, peat or wood Skrifvars, B.-J. et nl. Fuel, 1998 (Pub. 1997) 77, (112). 65-70. Selected results are reported from an extensive on-site measurement campaign where the ash behaviour in a 12 MW CFB boiler was studied during firing of coal, peat and wood. Samples were taken from all in-going and out-going solid material streams, as well as from the bed and the return leg. Deposit samples were further collected from the cyclone inlet and from two different locations in the convective path. Furthermore, the boiler operation was monitored, including collection of operational data, flue gas temperature profiles and emissions. The differences in the ash chemistry that were detected between the three different combustion cases are discussed and the paper draws conclusions on the impact of the chemical and the bed agglomeration and fouling tendency for each fuel.
Case study of the conversion of tangential- and wall-fired units to low-NO, combustion: impact on fly ash quality
gal02239
Hower, J. C. et al. Waste Management, 1997, 17, (4), 219-229. Fly ash quality can be influenced by the conversion of boilers to low-NO, combustion. It is affected in terms of the amount and forms of carbon, the overall fly ash fineness and the relative amount of glass versus crystalline inorganic phases. All of these factors can influence the potential for marketing fly ash utilization. In this study, three coal-fired combustors were studied before and after conversion: two tangentially fired and one wallfired. The post-conversion fly ash was higher in carbon than the preconversion ash from the same unit in all cases. The fly ashes in at least two of the units would appear to have post-conversion ashes which still fall within the regional guidelines for the limit of carbon.
99lo2240 Cofiring wood waste and coal In cyclone boilers: test results and prospectus Tilman, D. et al. Proc. Biomass Conf. Am.: Energy, Environ., Agric. Ind., 2nd, 1995, 382-389. The potentials offered by the co-firing wood waste in coal-fired utility boilers include reducing fuel costs, supporting local economic development and addressing environmental concerns ranging from emissions of NO, emissions to greenhouse gas. Consequently, TVA and EPRI developed an extensive programme initially involving case studies and calculations and extending into the conduct of co-firing tests at Boiler #2 of the Allen Fossil Plant. The wood waste co-fired was sawdust obtained locally and the coal employed was an eastern bituminous coal. The influence of co-firing on fuel preparation and handling, fuel management operations, boiler efficiencies and operating temperatures and the formation and control of airborne emissions was investigated. The tests demonstrated the potential for significant technical, economic and environmental benefits associated with wood co-firing, including improving dust control during fuel handling,
08
achieving 100% boiler capacities while co-firing, experiencing minimum impacts on boiler efficiency and achieving reductions in such pollutants as NO,. The wood waste is now being co-fired in similar tests with Utah bituminous coal. This paper reports on the results of the test programme to date and considers their implications.
Combustion technology for low-volatile coal in wail 98102241 firing boilers
K&a, T. et al. Ishikawujima-Hurima Giho, 1998, 38, (I), 15-20. (In Japanese) Combustion technology in wall firing boilers has been developed for effective combustion of low-volatile coal with poor ignition and combustion characteristics. This technology is comprised of modernized CI-oWR burners (which are very effective to improve ignition characteristics) and micro-pulverized coal combustion technology. Combustion tests in IHl’s 12 MW (thermal) demonstration test furnace using several Chinese semianthracites (whose volatile content was down to 10%) proved stable flame and low NO, emission with the CI-oWR burners, and also low unburnt loss combustion with the combined use of CI-(-uWR burners and micropulverized coal. A stable ignition for any size of CI-nWR burners was verified through numerical analyses. 98102242
Corrosion in ultra supercritical boilers for straw
Steam raising (boiler operation/design)
into the role of combustion parameters and fuel chemistry on fireside corrosion. In addition, the current view of the impact of coal chlorine on the wastage mechanisms concerned in each boiler stage is detailed.
Fireside corrosion testing of candidate superheater 98/02248 tube alloys, coatings, and claddings-phase ii
Blough, J. L. and Stanko, G. J. Oak Ridge Natl. Laboratory, [Rep.] ORNLIFMP, 1996, (ORNLIFMP-96/I, Proceedings of the Tenth Annual Conference on Fossil Energy Materials, 1996) 455-464. A variety of developmental and commercial tubing alloys and claddings were exposed to laboratory fireside corrosion testing in phase I, simulating a superheater or reheater in a coal-fired boiler. In Phase II samples of 347, RA-85H, HR3C, 253MA, FeaAI + 5Cr, 310 modified, SOOHT, NF 709, 690 clad, and 671 clad were exposed for over 10,000 h to the actual operating conditions of a 250-MW coal-fired boiler. The specimens were installed on an air-cooled, retractable corrosion probe, installed in the reheater cavity, and controlled to the operating metal temperatures of an existing and advanced-cycle coal-fired boiler. Specimens of each alloy were exposed for 4000, 12 000, and 16 000 h of operation. The results of the metallurgical examination of the corrosion probe samples after 4000 h of exposure are presented.
First year of operation of Provence SOPROLIF 250 MW CFB boiler
98lo2247
combustion
Henriksen, N. and Larsen, 0. H. Muter. High Temperalure, 1997, 14, (3), 227-236. ELSAM (an electric utility company in western Denmark) is looking into the possibilities of using biomass, mainly straw, for combustion in highefficiency power plants, in an attempt to reduce COz emission. The three ultra supercritical boiler concepts for combustion of straw only or together with coal are (1) pulverized fuel boilers (2) circulating fluidized bed boilers (3) vibrating grate boilers using 100% straw. Full-scale tests with straw fed into existing boilers have comprised the greater part of these experiments. Corrosion tests have been performed in these boilers by using temperatureregulated probes and in-plant tubes in existing superheaters. The corrosion has been determined by detailed measurements of wall thickness reduction and light optical microscopy measurements of the heat-resistant iron alloy degradation due to high-temperature corrosion. Corrosion mechanisms have been evaluated by using SEMiEDX together with thermodynamic considerations based on measurements of the chemical environment of the flue gas.
Levy, D. et al. Collect. Notes Internes Dir. Etud. Rech.: Prod. Energ. (Hydraul., Therm. Nucl.), 1997, (97NB00/05), l-8. The largest CFB boiler currently in operation is the SOPROLIF 250 MW CFB boiler, installed in the Provence Power Plant located near the town of Gardanne in the south of France. The purpose of the Provence project was to replace an old existing pulverized coal boiler in order to continue burning the local high sulfur coal of the nearby Gardanne mine, while ensuring an environmentally friendly operation. Engineering and construction of the CFB boiler and auxiliaries were carried out by Electricite de France (EDF), in collaboration with CdF for coal feeding and ash handling systems, civil works and renovation of turbine hall. Construction of the boiler was completed on schedule, full load was attained in November 1995 and commercial operation started in April 1996. Acceptance tests were successfully completed in April and May 1997. The SOPROLIF CFB boiler performances recorded during the first year of operation are in accordance with the expected figures. Carefully planned training prepared staff for the transfer from pulverized fuel to CFB, and the new process was accepted by the plant operators.
98102243
98102248
Luthe, C. et al. Chemowhere, 1998 (Pub. 1997), 36, (2), 231-249. In terms of toxicity equivalence (TEQs), stack dioxin emissions levels at a coastal Canadian pulp mill burning salt-laden wood waste in its power boiler, at typical steam production rates, were found to be 0.089 ng/m7. These levels easily lie below the guideline of 0.5 npim’ recommended by the Canadian Council of Ministers for Environment for municipal solid waste incinerators. Stack emissions accounted for less than 1% of all dioxin TEQs generated by the power boiler. While some dioxins appear to have been generated within the particulate collection devices, the excellent TEQ removal efficiency of these units confirms their essential role in controlling stack dioxin emissions. The TEQ contribution from high-temperature dioxin formation appears to have been minimal, less than 15% of the total. This suggests that dioxin formation in power boilers fuelled with salt-laden wood waste occurs primarily at low temperatures. Therefore, a relatively effective control strategy potential could be provided by temperature quenching.
Katakawa, A. et al. Jpn. Kokai Tokkyo Koho JP 09,323,024 [97,323,024] (Cl. BOlD53150). 16 Dee 1997, Appl. 96/145,954, 7 Jun 1996, 8 pp. (In Japanese) A wet type desulfurization apparatus, a heat-exchanger for heat recovery, installed in the upstream side of the apparatus and a heat-exchanger for reheating and installed in the downstream side of the apparatus comprise the apparatus. It also features a waste gas thermometer, a SOz concentration meter and a dust concentration meter installed in the upstream side of the heat-exchanger. A SOa concentration computing apparatus to compute the SO3 concentration based on the detection values of the SOa concentration meters; a waste gas temperature computing apparatus to select both or either one of detection values of the SOS concentration computing apparatus and the meter based on the mixing ratio of fuel oil and coal and determine the lower limit of the waste gas temperature at the outlet of the heat-exchanger and a controlling apparatus to control the circulation rate of a heat medium of the heat-exchanger and adjust the waste gas temperature higher than the temperature determined by the waste gas temperature computing apparatus, are also employed in the system. The operation controlling method includes optimization of the circulation rate of the heat medium in the heat-exchanger. Corrosion and choking of appliances can be prevented even if a mixed fuel of coal and fuel oil is used.
Dioxins formation in salt-laden power boilers: a mass balance
98102244
The effect of coal chlorine and sulfur contents on high temperature corrosion in an AFBC system
Xie, W. et al. Prepr. Pap. Am. Chemical Sot., Div. Fuel Chem., 1997, 42, (1). 369-373. The role of coal chloride in the corrosion of boiler components was considered in this work. The research AFBC system was configured to simulate the Shawnee plant’s system, especially the secondary superheater region in the plant. This simulation excluded consideration of the erosion problems, When using low chloride content coal, no wastage was observed in the plant in this location. 98102245
Effect of coal chlorine on the fireside corrosion of boiler furnace wail and superheater/reheater tubing
James, P. .I. and Pinder, L. W. Mater. High Temperature, 1997, 14, (3), 187-196. Boiler tube failures have been identified by EPRI studies as the principal cause of loss of power plant availability world-wide. A significant proportion of the failures in the furnace wall and pendant/platen superheater and reheater stages are the result of excessive metal loss by fireside corrosion, Despite fundamental differences in the corrosion mechanisms active on furnace walls and superheater/reheater stages, much of the worsening fireside corrosion problems experienced in both sections in UK plants in the 1960s and 1970s was attributed to fuel chemistry, in particular the coal chlorine content. The more recent history of fireside corrosion in CEGB and PowerGen Stations is taken from a literature survey undertaken as the inaugural exercise in a jointly sponsored EPRI/ PowerGen project
Flue gas desuifurization treatment apparatus for boilers and its operating method
Fouling of heat-transfer surfaces in oil-fired boilers for domestic heating
gal02249
Butcher, T. et al. J. Inst. Energy, December 1997, 70, 151-159. Fired with distillate oil, domestic heating boilers are subject to fouling of the convective section gas-side surfaces, which leads to a reduction in efficiency and to increased maintenance requirements. A rapid test to enable the composition of fouling deposits and the rates of fouling to be studied has been developed and used at two laboratory sites. it involves special fouling surfaces which can be removed for deposit analysis. Fouling rates are shown to be directly related to the sulphur content of the fuel. Also, operation with reduced excess air in these boilers can lessen fouling rates by reducing the conversion of fuel sulphur to sulphuric acid. Results are compared with those from tests on full-size boilers. 98lo2250 Heat recovery from the starting vessel of a oncethrough boiler system Ma, X.-G. and Chen, Z.-H. Appl. Therm. Eng., 1998 (Pub. 1997). 18, (34), 179-186. The week-day load is covered by an increasing number of coal- and oil-fired boilers which are shut down at weekends. An attempt has been made to calculate the amount of heat recovery in a once-through boiler system during its start-up. First, a mathematical model was developed and an
Fuel and Energy Abstracts
May 1998
203
of usable energy is generally more expensive. These high costs probably represent the main reason for the limited use of renewable energies in Germany.
Performance analysis of a small wind powered reverse osmosis plant
98102235 Kalinowski, 1997, Appl. Describes painting in
9wo2230
Infield, D. Solar Energy, 1997, 61, (6), 415-421. The performance of a small wind powered reverse osmosis plant has been assessed with a stand-alone systems analysis approach. The study is concerned with the sensitivity of operation to key parameters: wind speed, battery storage capacity and reverse osmosis operating pressure. The results of such a system analysis are shown to occasionally be inconsistent with more simplistic approaches sometimes adopted in this applications area. A provisional calculation of annual expected water delivery has also been undertaken. Detailed modelling results are presented and discussed. The paper concludes that the ideal operational pressure is not always the maximum design pressure, but can depend on the site wind speed. Since water storage is far cheaper than electricity storage, there is motivation to minimize the capacity of the battery store. The most effective battery capacity would seem to be in the range of 4 to 8 h at nominal rated load for the reverse osmosis plant, with the actual value critically dependent on wind speed at the site.
98102236 Use of sewage sludge energy in Swarzewo Ostejski, A. Gaz, Woda Tech. Sanit., 1997, 71, (lo), 370-373. (In Polish) After dewatering to moisture content 60 wt%, wastewater treatment sludge is mixed with fine coal in the ratio 1:l and used as fuel to fire a hot-water boiler (output 100 kW) at a sewage treatment plant in Swarzewo, Poland.
08
99102231 Production costing and economic analysis of power systems containing wind energy conversion systems Tripathy, S. C. et al. Energy Convers. Mgmt, 1998, 39, (7) 649-659. It is possible to generate electricity by both conventional sources (nuclear, coal, diesel, etc.) and non-conventional sources (such as wind, tidal, solar energy, etc.). There currently exists a growing interest in the nonconventional sources of energy, as they are limitless and cheap to operate and wind is one of the best potential candidates for this role. The effect of combining wind energy conversion systems (WECS) with the conventional power system is studied here. Fast transform techniques are used to determine the production costing of the combined system. An economic analysis is performed, based on the production costs, to study the benefits obtained over the lifetime of the WECS. 98102232
Simultaneous frequency and voltage control of wind-diesel power systems using energy storage
Mufti, M.-U.-D. et al. Int. J. Energy Res., 1998, 22, (3), 221-235. A new scheme for smoothing out the voltage and frequency fluctuations simultaneously in a hybrid wind-diesel system using a superconducting magnetic energy storage (SMES) unit is presented. The SMES unit located at induction generators’ terminal bus, uses local measurements for exchanging real and reactive powers simultaneously in four quadrants. Complete model of the hybrid wind-diesel SMES system is developed and is used for eigenvalue analysis and design of controllers. Computer simulation results illustrate the positive impact of the SMES unit on the quality of the supply and furthermore some modifications of the controller design are proposed.
Soclo-economic lessons from Denmark
98102233
assessment
of wind power-
Munksgaard, J. and Larsen, A. Energy Policy, 1998, 26, (2) 85-93. Results from a study on the social assessment of wind power in Denmark are reported. Using the cost effectiveness paradigm production costs for wind power are compared to reference figures for central power production based on coal and natural gas. The external production costs which arise from the emissions of COz, SOz and NO, from combustion of fossil fuel and from noise and visual effects from wind mills are added to the internal costs. The macro-economic effects on employment and the balance of payments from investing in a 1000 MW wind power development which is about double the total capacity of the present Danish level are considered. Taking into account the Danish obligation of reducing COz emissions by 20% in 2005 compared to 1988, the main result of the investigations is that the environmental benefits of wind power are so significant that from a socio-economic point of view wind power and natural gas power are equal. Having a coal-fired power plant as the reference technology, wind power is more advantageous.
Others, including Development, Economics 98102234
Provlding low-temperature heat with renewable energies. An energy economical comparison
Lux, R. and Kaltschmitt, M. Erdoel, Erdgas, Kohle, 1998, 114, (l), 31-37. (In German) The possible use of renewable energies is discussed with great interest for the provision of heat and electricity in Germany. Although they offer advantages in environmental aspects, their actual use is very small. The aim of this paper is make a comparison between the costs of providing lowtemperature heat from renewable energies such as solar radiation, geothermal energy, and biomass with those from fossil fuels. The results of this comparison show that the use of renewable energies for the provision
202
Fuel and Energy Abstracts
May 1998
System for utilising volatile air pollutants as fuel C. and Romanski, T. Pal. PL 172,365 (Cl. ClOKl/OO), 30 Sep 301,165, 23 Nov 1993, 4 pp. (In Polish) a system for catching volatile pollutants generated during various paint shops and utilizing them as fuel.
STEAM RAISING Boiler Operation/Design
9wo2237 Apparatus for dust-charged wet-type desulfurization of coal-fired boiler flue gases Yokosuka, T. et al. Jpn. Kokai Tokkyo Koho JP 09 57,054 [97 57,054] (Cl. BOlD53/50), 4 Mar 1997, Appl. 951217,096, 25 Aug 1995; 7 pp. (In Japanese) This apparatus provides a means for removing coal dust and mist from gaseous effluents of a coal-fired boiler flue gas desulfurization system using a crimped plate mist eliminator. The mist eliminator may be equipped with grounded electrode plates, corona-discharge electrode wires for trapping mist, and means for washing the deposits of electrically charged dust from the crimped plate in a gas passage partition plate perpendicular to the gas flow. Smoke formation is prevented and dust removal increased with this apparatus. 9WO2238 Ash behavior In a CFB boiler during combustion of coal, peat or wood Skrifvars, B.-J. et nl. Fuel, 1998 (Pub. 1997) 77, (112). 65-70. Selected results are reported from an extensive on-site measurement campaign where the ash behaviour in a 12 MW CFB boiler was studied during firing of coal, peat and wood. Samples were taken from all in-going and out-going solid material streams, as well as from the bed and the return leg. Deposit samples were further collected from the cyclone inlet and from two different locations in the convective path. Furthermore, the boiler operation was monitored, including collection of operational data, flue gas temperature profiles and emissions. The differences in the ash chemistry that were detected between the three different combustion cases are discussed and the paper draws conclusions on the impact of the chemical and the bed agglomeration and fouling tendency for each fuel.
Case study of the conversion of tangential- and wall-fired units to low-NO, combustion: impact on fly ash quality
gal02239
Hower, J. C. et al. Waste Management, 1997, 17, (4), 219-229. Fly ash quality can be influenced by the conversion of boilers to low-NO, combustion. It is affected in terms of the amount and forms of carbon, the overall fly ash fineness and the relative amount of glass versus crystalline inorganic phases. All of these factors can influence the potential for marketing fly ash utilization. In this study, three coal-fired combustors were studied before and after conversion: two tangentially fired and one wallfired. The post-conversion fly ash was higher in carbon than the preconversion ash from the same unit in all cases. The fly ashes in at least two of the units would appear to have post-conversion ashes which still fall within the regional guidelines for the limit of carbon.
99lo2240 Cofiring wood waste and coal In cyclone boilers: test results and prospectus Tilman, D. et al. Proc. Biomass Conf. Am.: Energy, Environ., Agric. Ind., 2nd, 1995, 382-389. The potentials offered by the co-firing wood waste in coal-fired utility boilers include reducing fuel costs, supporting local economic development and addressing environmental concerns ranging from emissions of NO, emissions to greenhouse gas. Consequently, TVA and EPRI developed an extensive programme initially involving case studies and calculations and extending into the conduct of co-firing tests at Boiler #2 of the Allen Fossil Plant. The wood waste co-fired was sawdust obtained locally and the coal employed was an eastern bituminous coal. The influence of co-firing on fuel preparation and handling, fuel management operations, boiler efficiencies and operating temperatures and the formation and control of airborne emissions was investigated. The tests demonstrated the potential for significant technical, economic and environmental benefits associated with wood co-firing, including improving dust control during fuel handling,
08
achieving 100% boiler capacities while co-firing, experiencing minimum impacts on boiler efficiency and achieving reductions in such pollutants as NO,. The wood waste is now being co-fired in similar tests with Utah bituminous coal. This paper reports on the results of the test programme to date and considers their implications.
Combustion technology for low-volatile coal in wail 98102241 firing boilers
K&a, T. et al. Ishikawujima-Hurima Giho, 1998, 38, (I), 15-20. (In Japanese) Combustion technology in wall firing boilers has been developed for effective combustion of low-volatile coal with poor ignition and combustion characteristics. This technology is comprised of modernized CI-oWR burners (which are very effective to improve ignition characteristics) and micro-pulverized coal combustion technology. Combustion tests in IHl’s 12 MW (thermal) demonstration test furnace using several Chinese semianthracites (whose volatile content was down to 10%) proved stable flame and low NO, emission with the CI-oWR burners, and also low unburnt loss combustion with the combined use of CI-(-uWR burners and micropulverized coal. A stable ignition for any size of CI-nWR burners was verified through numerical analyses. 98102242
Corrosion in ultra supercritical boilers for straw
Steam raising (boiler operation/design)
into the role of combustion parameters and fuel chemistry on fireside corrosion. In addition, the current view of the impact of coal chlorine on the wastage mechanisms concerned in each boiler stage is detailed.
Fireside corrosion testing of candidate superheater 98/02248 tube alloys, coatings, and claddings-phase ii
Blough, J. L. and Stanko, G. J. Oak Ridge Natl. Laboratory, [Rep.] ORNLIFMP, 1996, (ORNLIFMP-96/I, Proceedings of the Tenth Annual Conference on Fossil Energy Materials, 1996) 455-464. A variety of developmental and commercial tubing alloys and claddings were exposed to laboratory fireside corrosion testing in phase I, simulating a superheater or reheater in a coal-fired boiler. In Phase II samples of 347, RA-85H, HR3C, 253MA, FeaAI + 5Cr, 310 modified, SOOHT, NF 709, 690 clad, and 671 clad were exposed for over 10,000 h to the actual operating conditions of a 250-MW coal-fired boiler. The specimens were installed on an air-cooled, retractable corrosion probe, installed in the reheater cavity, and controlled to the operating metal temperatures of an existing and advanced-cycle coal-fired boiler. Specimens of each alloy were exposed for 4000, 12 000, and 16 000 h of operation. The results of the metallurgical examination of the corrosion probe samples after 4000 h of exposure are presented.
First year of operation of Provence SOPROLIF 250 MW CFB boiler
98lo2247
combustion
Henriksen, N. and Larsen, 0. H. Muter. High Temperalure, 1997, 14, (3), 227-236. ELSAM (an electric utility company in western Denmark) is looking into the possibilities of using biomass, mainly straw, for combustion in highefficiency power plants, in an attempt to reduce COz emission. The three ultra supercritical boiler concepts for combustion of straw only or together with coal are (1) pulverized fuel boilers (2) circulating fluidized bed boilers (3) vibrating grate boilers using 100% straw. Full-scale tests with straw fed into existing boilers have comprised the greater part of these experiments. Corrosion tests have been performed in these boilers by using temperatureregulated probes and in-plant tubes in existing superheaters. The corrosion has been determined by detailed measurements of wall thickness reduction and light optical microscopy measurements of the heat-resistant iron alloy degradation due to high-temperature corrosion. Corrosion mechanisms have been evaluated by using SEMiEDX together with thermodynamic considerations based on measurements of the chemical environment of the flue gas.
Levy, D. et al. Collect. Notes Internes Dir. Etud. Rech.: Prod. Energ. (Hydraul., Therm. Nucl.), 1997, (97NB00/05), l-8. The largest CFB boiler currently in operation is the SOPROLIF 250 MW CFB boiler, installed in the Provence Power Plant located near the town of Gardanne in the south of France. The purpose of the Provence project was to replace an old existing pulverized coal boiler in order to continue burning the local high sulfur coal of the nearby Gardanne mine, while ensuring an environmentally friendly operation. Engineering and construction of the CFB boiler and auxiliaries were carried out by Electricite de France (EDF), in collaboration with CdF for coal feeding and ash handling systems, civil works and renovation of turbine hall. Construction of the boiler was completed on schedule, full load was attained in November 1995 and commercial operation started in April 1996. Acceptance tests were successfully completed in April and May 1997. The SOPROLIF CFB boiler performances recorded during the first year of operation are in accordance with the expected figures. Carefully planned training prepared staff for the transfer from pulverized fuel to CFB, and the new process was accepted by the plant operators.
98102243
98102248
Luthe, C. et al. Chemowhere, 1998 (Pub. 1997), 36, (2), 231-249. In terms of toxicity equivalence (TEQs), stack dioxin emissions levels at a coastal Canadian pulp mill burning salt-laden wood waste in its power boiler, at typical steam production rates, were found to be 0.089 ng/m7. These levels easily lie below the guideline of 0.5 npim’ recommended by the Canadian Council of Ministers for Environment for municipal solid waste incinerators. Stack emissions accounted for less than 1% of all dioxin TEQs generated by the power boiler. While some dioxins appear to have been generated within the particulate collection devices, the excellent TEQ removal efficiency of these units confirms their essential role in controlling stack dioxin emissions. The TEQ contribution from high-temperature dioxin formation appears to have been minimal, less than 15% of the total. This suggests that dioxin formation in power boilers fuelled with salt-laden wood waste occurs primarily at low temperatures. Therefore, a relatively effective control strategy potential could be provided by temperature quenching.
Katakawa, A. et al. Jpn. Kokai Tokkyo Koho JP 09,323,024 [97,323,024] (Cl. BOlD53150). 16 Dee 1997, Appl. 96/145,954, 7 Jun 1996, 8 pp. (In Japanese) A wet type desulfurization apparatus, a heat-exchanger for heat recovery, installed in the upstream side of the apparatus and a heat-exchanger for reheating and installed in the downstream side of the apparatus comprise the apparatus. It also features a waste gas thermometer, a SOz concentration meter and a dust concentration meter installed in the upstream side of the heat-exchanger. A SOa concentration computing apparatus to compute the SO3 concentration based on the detection values of the SOa concentration meters; a waste gas temperature computing apparatus to select both or either one of detection values of the SOS concentration computing apparatus and the meter based on the mixing ratio of fuel oil and coal and determine the lower limit of the waste gas temperature at the outlet of the heat-exchanger and a controlling apparatus to control the circulation rate of a heat medium of the heat-exchanger and adjust the waste gas temperature higher than the temperature determined by the waste gas temperature computing apparatus, are also employed in the system. The operation controlling method includes optimization of the circulation rate of the heat medium in the heat-exchanger. Corrosion and choking of appliances can be prevented even if a mixed fuel of coal and fuel oil is used.
Dioxins formation in salt-laden power boilers: a mass balance
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The effect of coal chlorine and sulfur contents on high temperature corrosion in an AFBC system
Xie, W. et al. Prepr. Pap. Am. Chemical Sot., Div. Fuel Chem., 1997, 42, (1). 369-373. The role of coal chloride in the corrosion of boiler components was considered in this work. The research AFBC system was configured to simulate the Shawnee plant’s system, especially the secondary superheater region in the plant. This simulation excluded consideration of the erosion problems, When using low chloride content coal, no wastage was observed in the plant in this location. 98102245
Effect of coal chlorine on the fireside corrosion of boiler furnace wail and superheater/reheater tubing
James, P. .I. and Pinder, L. W. Mater. High Temperature, 1997, 14, (3), 187-196. Boiler tube failures have been identified by EPRI studies as the principal cause of loss of power plant availability world-wide. A significant proportion of the failures in the furnace wall and pendant/platen superheater and reheater stages are the result of excessive metal loss by fireside corrosion, Despite fundamental differences in the corrosion mechanisms active on furnace walls and superheater/reheater stages, much of the worsening fireside corrosion problems experienced in both sections in UK plants in the 1960s and 1970s was attributed to fuel chemistry, in particular the coal chlorine content. The more recent history of fireside corrosion in CEGB and PowerGen Stations is taken from a literature survey undertaken as the inaugural exercise in a jointly sponsored EPRI/ PowerGen project
Flue gas desuifurization treatment apparatus for boilers and its operating method
Fouling of heat-transfer surfaces in oil-fired boilers for domestic heating
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Butcher, T. et al. J. Inst. Energy, December 1997, 70, 151-159. Fired with distillate oil, domestic heating boilers are subject to fouling of the convective section gas-side surfaces, which leads to a reduction in efficiency and to increased maintenance requirements. A rapid test to enable the composition of fouling deposits and the rates of fouling to be studied has been developed and used at two laboratory sites. it involves special fouling surfaces which can be removed for deposit analysis. Fouling rates are shown to be directly related to the sulphur content of the fuel. Also, operation with reduced excess air in these boilers can lessen fouling rates by reducing the conversion of fuel sulphur to sulphuric acid. Results are compared with those from tests on full-size boilers. 98lo2250 Heat recovery from the starting vessel of a oncethrough boiler system Ma, X.-G. and Chen, Z.-H. Appl. Therm. Eng., 1998 (Pub. 1997). 18, (34), 179-186. The week-day load is covered by an increasing number of coal- and oil-fired boilers which are shut down at weekends. An attempt has been made to calculate the amount of heat recovery in a once-through boiler system during its start-up. First, a mathematical model was developed and an
Fuel and Energy Abstracts
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