OCR Text |
Show 9 00 - :f 150 - •00 - '50 - i00 - :50 - 00 - Flue gas inlet temp./Air preheat temp. \ 2x 3 2x 6 N.G.=10 m/Hr Flue gas outlet temp./Air inlet temp. J i t -A J A J A A jAt •so - | J \ s ; y : x : y ; / : • i • i • i • i • i • i • i • i • i • i • i • i • . 0 30 60 90 120 150 180 210 240 270 300 330 360 390 Time (sec.) Fig.6 The effect of regenerator bed depth on the heat recovery Under a same cross-section area, the effect of the regenerator bed depth on the temperature efficiency is eluciated in Fig.7. The result shows that the increment of the efficiency decreases as the unit increases, whereas the most heat recovery is found to occur at the first 3 units. Since the rotary combustion system is likely to be operated at 1 min per rotation, in other words, the access of regenerator bed of combustion exhaust and process exhaust will be switched. The result in Fig.8 shows a heat recovery at 30 seconds cycle time, the temperature of flue gas and air preheating temperature exhibit a marginal difference of 35 ~ 55°C across entire furnace testing temperature, this indicates that the temperature efficiency is easier to be over 90% if the bed depth is longer enough, despite of the flue gas outlet temperaure is at least 150 °C higher than the air inlet temperature. On the other hand, an increase of cycle time causes only a slightly decrease of temperature efficiency, as shown in Table 1, whereas AT means the temperature difference of the flue gas and preheated air streams. |