EFFECT OF HEATING RATE ON THE THERMODYNAMIC PROPERTIES OF PULVERIZED COAL

Abstract

This semi-annual technical progress report describes work performed under DOE Grant No. DE-FG22-96PC96224 during the period March 24, 1998 to September 23, 1998 which covers the fourth six months of the project. Existing laser heating set-up at the Single Particle Laboratory, Federal Energy Technology Center, Morgantown, WV would work only in the range of 10 to 10 4 5 K/s. During this reporting period, appropriate changes were made to the laser heating system to heat particles in the range of 10 to 10 K/s. Also, calibration for all the components of the 4 7 electrodynamic balance measurement system including single-color pyrometer and heating laser was successfully completed. Following the calibration, a large number of single coal particles were caught in the electrodynamic balance and their volume, external surface area, mass, and density were measured. The same single particles were then heated bidirectionally with a pulsed (10 ms pulse width) Nd:YAG laser beams of equal intensity. The temporal power variation in the laser pulse was monitored for use in the heat transfer analysis by an ultra-fast fiber optic uv light transmitter included in the beam path and coupled to a silicon photodiode. Measurements of changes in particle size that accompanied rapid heating was made by means of the high-speed diode array imaging system discussed in our previous reports. Dynamics of volatile evolution and particle swelling were recorded using well established time-resolved high-speed cinematography. Measurements of the radiant emissive power from the heated and cooled (when the laser is turned off) particles was made using the single-color pyrometer. The above experiments are being repeated for a significant number of coal particles for a number of heating rates in between 10 - 10 K/s at FETC, Morgantown. 4 7 Shipment of the donated heated grid system components from our industrial partner, United Technologies Research Center (UTRC), CT to CAU was complete during this reporting period. Testing of the heated grid system components at CAU is also in progress.