08 Steam raising (boiler operation/design)

An eight-week test programme was carried out on a test burner with 2.5 MW thermal output in the IFRF test furnace in Ijmuiden, The Netherlands. The burner test was accompanied by numerical calculations and cold flow experiments. This led to the application of the burner in a utility boiler with a thermal capacity of 32 MW per burner, recommissioned in summer 1995 after retrofitting the burners. Burner operation performance did not experience problems. Experimental data are reported and the possibilities of adapting the burner to existing units are addressed.

9aio3971 Effect of pressure on char combustion in a pressurized circulating fluidized bed boiler MacNeil, S. and Basu, P. Fuel, 1998, 77, (4) 269-275. Under simulated pressurized circulating fluidized bed conditions, coal char combustion was studied at furnace temperatures between 700 and 850°C. At 1,3,5, and 7 atmospheres and oxygen concentrations of 10 and 21%, the kinetic rates of char combustion were measured. The surface reaction rates increased with pressure up to a pressure of 5 atm, but decreased with higher pressures. Pressure was found to exert a strong influence on the kinetic parameters. The chars burned primarily under kinetically controlled conditions. Traditional char oxidation models cannot adequately predict the variation of reaction rates with pressures. Mass transfer rates were measured for comparison with those obtained from previous studies. These results show a marked difference in comparison with calculated values.

98193972 Experience with combined coal/gas low NO, bur- ners in utility boiler retrofit applications King, .I. L. FACT, 1996, 21, (Proceedings of the International Joint Power Generation Conference, Volume 1: Environmental Control/ Fuels and Combustion Technologies, 1996), 87-94. Mitsui Babcock Energy Services have retrofit over 17,000 MW, of coal fired utility boilers with low NO, Axial Swirl burners, over the past five years. Reductions of 40-70% have been achieved for NO, in a wide variety of boiler configurations, firing a range of coal qualities. Interest in recent years in combined low-NO, gas and coal firing in utility boilers has increased. In addition to summarizing the results from the coal fired retrofits, this paper presents the results of the development of a combined coal/gas low NO, burner.

9aio3973 Extending the life of cyclone-fired boilers using low cost staged combustors Murrell, F. J. and Ashworth, R. A. FACT, 1996, 21, (Proceedings of the International Joint Power Generation Conference, Volume 1: Environ- mental Control/Fuels and Combustion Technologies, 1996), 249-253. Many power plants will be adversely affected by the new NO, regulations handed down hy EPA, in particular cyclone-fired units will be affected. Sponsored by Florida Power Corporation, a new technology is under develoument which incornorates a staeed slaeeine combustor. resultine in low Nb, output as well as a reductio: of bo;h SOz and ash’enteringthe boiler. The net result of the combustor is to provide a low cost NO, control technology which permits the use of low cost, high sulfur and high ash coal. The combustor is designed to reduce NO, to -0.4 Ib/MMBtu, as well as significantly reducing particulates and SO,. This is provided to the power producers as the least cost alternative for NO. and SO, control.

98103974 Fire-tube boiler test burn on coal-water fuel Hale, B. M. and Arnold, D. W. Energy Sources, 1998, 20, (l), 11-24. An existine fire-tube boiler was retrofitted to burn coal-water fuel ICWFl: it was operated for 800 h on CWF. Operating with CWF required a boiler derating of 20% and natural gas as a support fuel. The test burn of CWF is described, including combustion characteristics, boiler efficiency, boiler derating, and emission quality of the flue gas, and a brief summary of the economic analysis of conversion from natural gas to CWF is presented.

9alo3975 Installation of low-NO, burners and gas co-firing technology at New England Power’s Brayton Point Station Afonso, R. er al. FACT, 1996, 21, (Proceedings of the International Joint Power Generation Conference, Volume 1: Environmental Control/Fuels and Combustion Technologies, 1996), 11 l-l 18. As the largest fossil-fuelled generating station in New England, New England Power’s Brayton Point Station in Somerset, Massachusetts generates nearly 1600 MW, in its four steam boilers fuelled by coal, oil and natural gas. New England Power have retrofitted three coal-fired boilers at the Brayton Point Station with low-NO, burners and gas co-firing technology as part of its compliance strategy with Titles I and IV of the 1990 Clean Air Act Amendments. New England Power (NEP), the Gas Research Institute (GRI) and the Electric Power Research Institute fEPRI) contracted the Enerev Svstems Associations (ESA) to nerform a gas cd-firing and low NO, &trner deployment project on the units at Brayton Point. The results of baseline and post low-NO, burner retrofit emissions and unit performance measurements are described, as well as the impact of gas co-firing on these parameters. The project results should be useful to coal-fired utilities evaluating low NO. burner or gas co-firing retrofit technologies for tangential and wall-fired boilers.

98iO3976 Iron-chromium-nickel alloy having high corrosion resistance in aggressive environment for liners of steel pipes for boilers Ishitsuka. T. and Nose. K. PCT Int. Aool. WO 97 39.153 ICI. C21D84101. 23 Ott 1997, JP Appl.‘97/8,106, 20 Jan ‘1597, 29 pp. (in Japanese) ~” The alloy has especially high corrosion resistance in the atmosphere of burned wastes or fossil fuel.

9aio3977 Low NO. burners and heat transfer surface mod- ifications for a successful conversion to Powder River Basin fuel on a wall fired boiler Woldehanna, S. et al. FACT, 1996, 21, (Proceedings of the International Joint Power Generation Conference, Volume 1: Environmental Control/ Fuels and Combustion Technologies, 1996) 241-248. The objectives and evaluations of the project are presented, along with the operating results of the Low NO, Powder River Basin (PRB) fuel conversion at the Northern Indiana Public Service Company’s (NIPSCO), Schahfer unit 15, 500 MW boiler. The overall goals were to burn cost effective PRB coal at NO, emissions SO.45 Ib/MMBtu while maximizing boiler performance. Working closely with NIPSCO, Foster Wheeler Energy Corporation (FWEC) designed and supplied the necessary low NO, burners and pressure parts modification to enable PRB coal firing on this unit. Without overfire air, the NO, emissions were consistently co.35 lb/ MMBtu with <l% repeatable loss of ignition performance. The pressure part modifications met NIPSCO’s boiler performance requirements, with successful unit operation ~90% MCR.

9aiO3978 Low NO, combustion system with DSVS rotating classifier retrofit for a 630 MW. cell burner unit Bryk, S. A. et al. FACT, 1996, 21, (Proceedings of the International Joint Power Generation Conference, Volume 1: Environmental Control/Fuels and Combustion Technologies, 1996), 201-209. A universal pressure (UP) type supercritical boiler, New England Power Company’s (NEP) 630 MW, Brayton Point Unit 3 was originally equipped with pulverized coal (PC) fired cell burners. To comply with Phase I NO, emission requirements under Title I of the 1990 Clean Air Act Amend- ments, the unit was retrofitted with a low NO, staged combustion system in spring 1995. By the end of the first month, the unit was operating under state compliance emission levels. Additional optimization testing was performed in August, 1995. The retrofit scope consisted of replacing the cell burners with low NO, DRB-XCL type PC/oil burners and overfire air ports within the existing open windbox, with no change in firing pattern. To maintain low UBC concentrations, the scope included modifying the MPS- 89 pulverizers by replacing existing stationary classifiers with the B&W DSVS (dynamically-staged variable speed) two-stage rotating classifiers. The project is described, retrofit emissions data are presented and recommendations for retrofitting other similarly designed units are given.

98lQ3979 Low-cost options for abatement of nitrogen oxide emissions from pulverized-fuel boilers Gaj, K. Gospod. Poliwami Energ., 1997, 45, (11) 10-14. (In Polish) Low-NO, pulverized coal burning systems are reviewed, and comparisons are made between NO, reduction efficiency of some primary means and some technical and ecological aspects of low-NO, modernizations of combustion.

98103980 Low-NO,-emission system for boilers in Power Plant Ill Szpak, A. and Przydatek, Z. Energeqka, 1997, 51, (12) 48-52. (In Polish) Based on Babcock-Hitachi burners, this low emission system has been implemented in the power plant Jaworzno III (Poland) by IV0 Interna- tional Ltd (Finland). Cost effectiveness and environmental effects (mainly NO, control) are discussed.

9alO3981 Main repair and modernization measures for OP 650-060 boilers Wojcik, W. Energeryka, 1997, 51, (12), 104-105. (In Polish) When low-NO, burners were installed in a pulverized coal-coal fired utilitv boiler, it became necessary to increase the heating surface area of the secondary steam superheater. The existing superheater was replaced and ash blowers were installed to address this problem.

9aiQ3902 Method and assembly for Increasing the capacity of a boiler plant Hirvenoja, J. PCT Int. Appl. WO 98 10,037 (Cl. ClOJ3/54), 12 Mar 1998, FI Appl. 96/3,459, 4 Sep 1996, 31 pp. The paper presents a method for increasing the energy production and the fuel processing capacity of a boiler plant. Among other things, the invention is suitable for increasing the share of electric power particularly in plants using fluidized-bed boilers and also the capacity of soda recovery boilers. The invention is based on exhausting gas by suction from an air-deficient zone in phased combustion, after which the gas is separate combusted in a gas turbine or a separate boiler. The boiler or burner can then be fed a quantity of additional fuel corresponding approximately to the amount of exhaust gas.

372 Fuel and Energy Abstracts September 1996