Research Of The Heat Transfer Progress Of The High Temperature Calcined Petroleum Coke Waste Heat Utilization Exchanger

The calcined petroleum coke is petroleum coke after high temperature calcinated. It is essential material of aluminum electrolysis anode, graphite electrode used in steel producing and carburant. The calcined petroleum coke temperature is above 1273 K when it is discharged from the tank calcined furnace, and possess lots of heat. So it is of great significance to achieve efficient recycling of energy conservation of calcined petroleum coke waste heat for both energy saving and emissions reduction and improving the quality of calcined petroleum coke. In current industrial production, waste heat of the high temperature calcined petroleum coke can be recycled through high temperature calcined petroleum coke heat exchanger. The high temperature calcined petroleum coke heat exchanger consists of two parts: internal and external heat exchanger. The external heat exchanger consists of vertical tubes and diaphragm wall, and the internal heat exchanger consists of vertical tubes, and axial fins were welded in the tubes.In this paper the mathematic models of heat exchanger without fins, and the rectangular, trapezoidal, triangular fin-tube heat exchangers were set up, and numerical simulation and experimental methods were used to study the effects of physical parameters(such as the porosity, equivalent heat conductivity coefficient and equivalent specific heat of calcined petroleum coke) variation and fins structure parameters variation on heat transfer characteristics. Then the results of heat exchanger without fins and rectangular fin-tube heat exchanger, and the results of rectangular, trapezoidal, triangular fin-tube heat exchangers with equal heat exchange area were compared. The conclusions are showed as follows.(1)When the calcined petroleum coke’s porosity increased from 0.581 to 0.794, the calcined petroleum coke average temperature at outlet decreased from 541 K to 489 K, and the heat recovery efficiency increased from 72.7% to 77.9%. When the equivalent heat conductivity coefficient increased from 0.9 to 1.1, the calcined petroleum coke average temperature decreased from 537 K to 502 K, and the heat recovery efficiency increase d from 72.6% to 77.9%. When the equivalent specific heat increased from 0.9 to 1.1, the calcined petroleum coke average temperature increased from 501 K to 535 K, and the heat recovery efficiency decreased from 77% to 73%.(2)When the fin height was changed, the effects on heat transfer characteristics of the heat exchanger were obviously. When the rectangular fin height increased from 34 mm to 46 mm, the calcined petroleum coke average temperature at outlet decreas ed from 415.2K to 377.2K, and the heat recovery efficiency increased from 87% to 91%. When the trapezoidal fin height increased from 34 mm to 46 mm, the calcined petroleum coke average temperature at outlet decreased from 415 K to 377 K, and the heat recovery efficiency increased from 87.2% to 91.5%. When the triangular fin height increased from 34 mm to 46 mm, the calcined petroleum coke average temperature at outlet decreased from 334 K to 315 K, and the heat recovery efficiency increased from 92.5% to 94.4%.(3)When the fins shape were different, and heat exchange area was 0.53m2, results showed that the calcined petroleum coke average temperature of the triangular fin-tube heat exchanger at outlet was 323 K, respectively 70 K and 67 K lower than rectangular and trapezoidal fin-tube heat exchangers. And the heat recovery efficiency was 93.8%, respectively 4.1% and 3.7% higher than rectangular and trapezoidal fin-tube heat exchangers. Therefore when the heat exchange area is equal, the comprehensive heat transfer perf ormance of the triangular fin-tube heat exchanger is the best within the range of the parameters studied in this paper.