OCR Text |
Show guard against heat loss. Thermocouples (chromel-alumel) are placed in the fire tube, in the exhaust stack at the exit of the fire tube, and the area of the stack tube (see Figure 3-2). The cooling water system is a closed circuit, flowing from the fire tube test apparatus through a pump into a radiator and back to the test unit. The burner, North American Mfg. (No. 6525-43-6), is specifically designed for use in small heavy oil systems. Because of the higher viscosity of PETCOM, the burner is slightly derated from 11.6 gal/hr of oil to a maximum of 10 gal/hr. The built-in pilot is of the interrupted type, being used only for light off. Atomizing air (375 SCFH) is supplied from a compressor at 15 psig minimum. The North American nozzle supplied with this burner is shown in Figure 3-3 and, as received, has an annular opening of 445 microns. A modified type of this nozzle was used where the annular opening was increased to 662 microns with the internal oil feed holes also enlarged from 0.055" to 0.078" (1.98mm). Also used was a nozzle designed by Franklin. This nozzle is particularly useful in burning high viscosity fuels and is shown in Figure 3-4. This nozzle configuration uses the swirling nozzle air to shear and atomize the fuel. Steam atomization was also used with both types of nozzles. The North American Burner System is supplied with a refractory flame holder 7" in diameter and 9" long. In cases where high solids concentrations are used, an additional refractory block of the same length and diameter is attached to the one existing on the burner. This gives a refractory liner length of 18" which helps confine the flame and promotes mixing of the air/fuel system. A Moyno type 3M1-CDQ positive displacement pump with a 0-300 RPM SCR drive is used and provides a maximum flow of 7.5 gallons per hour. A water bath containing an aqueous solution of ethylene glycol with two copper coils is utilized in order to heat both the fuel and atomizing air. 19-9 |