OCR Text |
Show The heating value of PETCOM, on the other hand, shows about 6 percent increase in volumetric heating value (expressed in MMBTU per barrel for the 45% PETCOM) over that of the No. 6 fuel oil due to higher density coke. The density of the coke as measured by helium displacement is 87.5 lbs/ft3 while that of the No. 6 fuel oil is 60.6 lbs/ft3. The effects of coke weight fraction in PETCOM on viscosity can be seen in Table 2-1. PETCOM with 45 weight percent solids at 140°F has viscosity of 7500 cp, 22.5 weight percent has viscosity of 380 cp and No. 6 fuel oil has viscosity of only 180 cp (Figure 2-2). Efficient PETCOM atomization in a combustion burner is inversely proportional to its viscosity. The higher the concentration of coke in PETCOM, the higher its viscosity at a given temperature and, therefore, the more energy is required for proper atomization. Lower viscosity can be achieved by heating PETCOM to temperatures at which the viscosity becomes comparable to that of No. 6 fuel oil. This is clearly shown in Figure 2-2 for 22.5 percent and 45 percent PETCOM. For example, 45 weight percent PETCOM can be heated to 400°F for a viscosity of approximately 100 centipoise. This viscosity compares to a 160°F preheat temperature for an equivalent viscosity No. 6 fuel oil and about 190°F for a 22.5 weight percent PETCOM. 3. COMBUSTION TEST FACILITY DESCRIPTION Test Facility The Franklin Research Center test apparatus, shown in Figure 3-1 was initially fabricated for burning coal-oil-water emulsions, and has been modified for use with petroleum coke-oil mixtures. Its fire tube is a 9' x 20" schedule 10 steel pipe enclosed in a 9' x 3'6" water bath. The water cooling system consists of five 2" overflow pipes connected from the test apparatus to water pumps, enroute to a heat exchanger. The 2" water return pipes are connected to the bottom of the apparatus. The fire tube is equipped with eight 2" sight holes, four on each side. A sight glass is also installed on the end plate opposite the burner. The entire apparatus along with the five overflow pipes, is insulated to 19-6 |