OCR Text |
Show tion between the cone bottom and the furnace there is a tube bank of two staggered rows of water-cooled tubes, with triangular leaders to prevent dust deposition, which acts as a radiation trap and allows radiative flame holding. A series of ports down the front face of the furnace below the tube bank allows intrusive access for gas and solid samples, and for temperature measurements by suction pyrometer or 2-color pyrometer. Wall temperature measurements are obtained by Pt-Pt/lO% Rh TC's in wells flush with the inside of the back wall. In the first configuration used by Csaba [1] in 1956 et seq, there was no water-cooled tube bank and the flame stabilized inside the (refractory) cone itself. This configuration was used to measure flame speeds as a function of dust concentration and, for this, the design followed that described by Taffanel and Durr [12] though with very different results. A second, larger version with circular cross-section was used by Beer [2] but for obtaining reactivity data which is of independent importance but not immediately relevant to the purposes of this paper. The configuration with the tube bank as a radiation trap was used first by Howard [3], and this was the configuration used in our subsequent investi-gations [4,5]. The firing rates used in these experiments were mostly in the range 5 to 10 kg/hr with stoichiometries ranging from slightly lean to substantially fuel-rich, particularly in the case of Csaba's and Gee et ai's experiments. Further details of the experimental methods and particular results are given in the citations. 2.2 Hieb-Intensity Reactor and Furnace. Figures 2 and 3 illustrate the high-intensity jet mix reactor [6,7] and the furnace [8-11] respectively. The basis of both devices is a set of 4 primary jets conveying coal, which are all aimed at a common point in the center of the reactor or on the center line of the furnace. In both cases, this jet system produces such rapid mixing that 6 the particle heating rates are of the order of 10 deg/sec, compared with 4 5 something between 10 and 10 in other combustors. The jet-mix reactor (Fig. 2) is spherical, of about 200 cc., with an exhaust on the underside at which point there is a sampling probe and temperature |