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Show 1800 1700 OXYCUIN DATA - 1/10/. 1800L-__ ~ __ ~~~ __ ~~~~~=-~=-~~~~~ 7:00 LlIO 8:00 10:00 11:00 12:00 TIME TEMP. e-e-e110 • 1\ ,, 111 ___ 112 STeEL PAOOUC'TlOH - 144.1 TONSIHA Fig. 7 - Temperature distribution for oxygen system A'R DATA-ent/N TIME TEMP. e-e-e 110 • , " 111 .... 112 STeEL PAOOUC'TlON - 130.0 TONS/HA Fig. 8 - Temperature distribution for air system 2400 2200 OXYO ... DATA - 1/20/88 TIME TEMP. _ STACK _ n STeEL PAOOUC'TlON - ' ..... 1TONS/HI! Fig. 9 - Stack temperature for oxygen system 264 Figures 9 and 10, for oxygen and air respectively, show temperature readings from two thermocouples, one located in the stack and one located in the roof near the beginning of the Preheat zone in the middle of the furnace. Note the large difference in these two thermocouples in the oxygen case. The smaller flue gas volume results in a much larger temperature drop in the unfired area between these two thermocouples. The stack thermocouple varies around 1300 to 1400 OF for the o~gen case as compared to around 1700 to 1800 F for the air case. This seems to support the previous conclusion of a difference in flue gas temperature of around 300 OF. 2800 2400 E., 2000 II: i 1800 II! ~ 1800 1400 1200 A'R DATA - 1/10,.. S:OO 0:00 10:00 11:00 12:00 13:00 14:00 15:00 11:00 17:00 TIME TEMP. _ STACK _ n STeEL PAOOUC'TlON - 130.0 TOHS/HI! Fig. 10 - Stack temperature for air system COMPUTER MODELING Throughout the course of this project, a better understanding of continuous furnaces was gained through the use of a computer program which modeled the operation of a continuous furnace for both steady state and transient conditions. For instance , the effect of a change in the length of the unfired section could be analyzed using the computer model. The modeling studies showed a significant increase in fuel savings when the unfired area was lengthened. In fact, this proved to be true when the fuel savings improved dramatically after the two burners in the Preheat zone were shut off. Table 3 shows the results from the computer model for this example. Case 1 is the air base case. Conversion of the Preheat and No. 1 Heat zones to oxygen is given in Cases 2 and 3. In Case 2 the unfired area has been shortened to simulate the placement of the two oxygen burners nearer to the flue. Lengthening of the unfired area is given in Case 3 to simulate the effect of shutting off these two burners. |