now Sithe Energies). More recent programs at GPU Genco, NIPSCO, Southern Company, Alliant Energy, and Allegheny Power Company have investigated and/or tested cofiring with more advanced concepts including blending biofuels with other opportunity fuels to design alternative energy sources for cyclone boilers, firing switchgrass and other agricultural products in PC boilers using separate injection, designing burners explicitly to optimize cofiring, and gasifying biomass in order to integrate biofuel cofiring into natural gas-fired electricity generating settings. This paper focuses upon some fundamental fuel consumption and associated combustion chemical considerations to consider recent results from cofiring programs, and to examine some of the opportunities and technical issues associated with eofiring. Williams, A. et al. Progress in Energy and Combustion Science, 2001, 27, (6), 587-610. This paper addresses the current status of the understanding of the combustion of pulverized coal and pulverized biomass from the viewpoint of computer modelling. While a knowledge of the underpinning science is of vital importance it's translation into applicable computer usable equations or computer data base libraries is of vital importance. A review is given of the current status of sub-models for the combustion of pulverized coal. Much of the information available for coal is transferable to biomass combustion although there are still areas where there is lack of information. 02/02136 Combustion of Victorian and South Australian high moisture lignites in a circulating fluidized bed combustion pilot plant Bhattacharva, S. P. et al. Proceedings of the International Conference on Fluidized Bed Combustion, 2001, ( 16), 921-933. Victoria and South Australian lignites are characterized by high moisture content (up to 67%) and in some cases high sodium, chlorine and sulphur contents. When fired in conventional fired furnaces, these coals are known to produce unacceptable ash fouling and corrosion of heat transfer surfaces. Due to an interest in the behaviour of these coals when fired in CFBC boilers the CRC undertook combustion tests to assess the performance of four high moisture lignites in a 0.3 MWth circulating fluidized bed combustion (CFBC) pilot plant. The test program involved evaluation of: bed agglomeration as a function of bed temperature and operating time; additives (limestone and dolomite) and bed material usage; ash deposition and fouling of heat transfer surfaces; gaseous emissions -SO2, NOx, CO, and COz as a function of fuel properties, bed temperature, excess air, ratio of primary to secondary air, and additives. Tests were conducted at g00-850Β°C for periods ranging from 24 h to 130 h. Silica sand was initially used as the bed material. For three of the coals, tests were terminated after 130 h. At that stage, there was no sign of bed agglomeration problems. For another coal, which had highest levels of sodium, chlorine and sulphur for the coals tested, tests had to be stopped after 28 h due to difficulties in recirculating the bed material. An increase in operating hours was obtained when this coal was pre-mixed with fine particles of additive material prior to combustion. In all tests, the bed material was sampled every 24 h. The bed material, deposits formed on air cooled probes, and fly ash collected from the fabric filter were examined using chemical analysis, SEM, and X-ray diffraction. This paper presents the results and discusses the effects of bed temperature and additives on the combustion performance, agglomeration behaviour and control, deposition characteristics of the ash material, and gaseous emissions during combustion of the four lignites.
02/02135 Combustion of pulverized coal and biomass