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Show INTRODUCTION The impetus for research on the combustion characteristics of coal/ water slurries is varied. In part it is due to the goal of substituting coal for the premium fuels, natural gas and oil, in industrial boilers and furnaces operating at atmospheric pressure. In addition a significant savings in premium fuels can be achieved by substitution of coal for the premium fuels in open cycle gas turbines and industrial diesel engines. While sufficient rheological information exists on coal/water mixtures to suggest that they should be compatible with state-of-the-art liquid fuel transport and combustion injection systems, very little baseline data are available for the prediction and optimization of combustion behavior, although some initial work on the chemistry of wet coals has been recently reported (Solomon et al. 1983). The question is how to design and optimize the combustion process to permit direct use of coal/water mixtures, given the often conflicting requirements of improved efficiencies, control of emissions, and control of corrosion, fouling, slagging, and erosion. One of the most important ingredients in optimization of the combustion process is the design of the input fuel characteristics. For example, what are the benefits (if any) of producing a smaller size distribution of pulverized coal in the slurry? Atomization characteristics of liquid fuels are known to be yery important in determining subsequent combustion behavior (Chigier, 1983). What additional effects are introduced by sol id/liquid two phase mixtures? How does mineral matter content (which can be reduced by beneficiation) affect combustion performance? More specifically, how do these physical properties affect spray atomization, ignition, char burnout, and mineral matter formation? A data base on the combustion of these fuels in controlled laboratory scale systems is required to provide users with the tools to predict the sensitivity of outputs to changes in controllable inputs. In this paper we discuss the development of a laminar flow reactor system to investigate the combustion of coal/water slurries at atmospheric pressure. Our work has focused on the application of an in situ particle counter-sizer-velocimeter (PCSV) (Holve, 1983) and high speed camera to measure the atomization characteristics of several different coal/water slurry mixtures. Following atomization, the size distribution evolution of the atomized slurry is measured in the reactor through ignition, devolatilization, and the initial stages of char burnout. LAMINAR FLOW REACTOR SYSTEM A continuous small flow-rate coal slurry atomizer and laminar flow reactor system has been designed, fabricated, and tested. The reactor can be operated over a range of uniform temperature, oxidizing, and reducing conditions for the early stages of combustion. This system injects a uniform velocity and concentration mixture of atomized slurry into a 2mm by 40mm long slot of a laminar flow reactor, which uses a methane-air mixture to produce uniform flow of the high temperature gases (Figure 1). On either side of the slot are two flat flame burners, 20mm by 40mm long which provide a uniform methane-air mixture matching the slot conditions of temperature, oxygen concentration, and velocity. The fuel feed system consists of an air blast atomizer and associated plumbing. Slurry feed to 5 |