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Show general, the primary or transport air was 70°C ; t he secondary air was 300°C. Primary air velocities were in the range 15 - 20 mls and secondary air velocities were from 20 to 60 m/s. For more details about the specific burner and furnace designs and operating conditions, consult the referenced articles [1-5, 20-22]. An isothermal plug flow reactor (IPFR) was used to generate fundamental information about the coals which can be used to understand the burner data. The IPFR used is displayed in Figure 4 [13, 15]. In this reactor, it was possible to simulate the temperature, heating rate, and gas composition to which pulverized coal particles are exposed in actual flames. Thus, realistic estimates of the amount of volatile material and volatile N2 could be gained. The main reactor is a ceramic tube 120 mm in diameter and 2 to 5 m long. The tube is heated externally with graphite heating rods. Hot gases are supplied by the combustion of natural gas in a precombustor. Feeding and collection of the particles is accomplished with water cooled probes. The collection probe also has nitrogen injection at the tip to ensure rapid quenching of the reactants. The data used in this study was generated at 1400 0 C and a residence time of 150-300 ms. The gas in which the particles pyrolyzed was composed of 5% H20, 10% C02 and 85% N2. The weight loss and N2 release information was generated by analysis of the char samples collected. In the studies cited, a wide variety of coals have been used both in the IPFR and in 2.5 MW burners. The results from seven coals will be discussed in this paper, since these are the coals which have been studied by both techniques. The proximate and ultimate analyses of these coals are presented in Table 1. 4.1 Coal Characterisation The results of the coal characterisation work are listed in Table 2 [13]. As was displayed in Table 1, a wide range of coal quality was studied; the proximate volatile matter (VMprox) ranged from 23 to 55%. The second column in Table lists the weight loss of the coals in the IPFR (VMIPFR). This data represents completely pyrolysed coal samples which were exposed to conditions similar to pulverized coal flames. As can be seen, the VMIPFR values are always significantly higher than the VMprox values. The relationship between VMIPFR and VMprox is not simple; the ratio VMIPFR/VMprox ranges from 1.5 to 1.9 with no clear trends. 6 |