Affiliation:
1. School of Mechanical and Vehicle Engineering, Linyi University, Linyi 276000, China
Abstract
Background:
The pellet shaft furnace is widely used to roast pellets, which is essential
for the blast furnace burden structure; however, the study on the roasting process in the pellet shaft
furnace is very critical for obtaining high-quality pellets.
Objective:
A theoretical model of the pellet roasting process in the pellet furnace (8 m2) has been
developed on the basis of reaction engineering. The present study aims at investigating the roasting
process in the pellet shaft furnace by taking into account gas flow and heat transfer so that a reasonable
structural design for the shaft furnace can be obtained.
Methods:
A numerical model for an 8m2 pellet shaft furnace has been developed on the basis of reaction
engineering by taking into account gas flow, heat exchange between pellets and gas, and oxidation
reaction of pellets.
Results:
The results show that four reaction zones (preheating, roasting, soaking, and cooling) exist
obviously in the pellet shaft furnace. About 80% coolant gas flows through the gas coolant passage
in the roasting zone, and the non-uniformity of coolant gas in the cooling zone exists under normal
operative conditions. Furthermore, effects of some operation conditions on the distributions of process
variables in the furnace are also examined. The numerical results are in agreement with industrial
experiment results.
Conclusion:
The results reveals that the non-uniform flow of gas occurs in the cooling zone. The
non-uniform flow of gas greatly affects the cooling effect. The present results can provide a theoretical
basis for the prediction of the furnace process, the optimization of operation and the rational
design of furnace shape. At the same time, the present work is helpful in realizing the automatic
control and computer management of furnace production. In the future, the movement of pellets
should be observed by means of a visualized model experiment to verify that the descending movement
of pellets is approximately a potential flow in the furnace and piston flow except for the cooling
zone. In addition, the experimental study of a single pellet under a widely varying range of conditions
should be carried out to investigate the controlling step of oxidation reaction for pellets in
the furnace.
Funder
National Natural Science Foundation of China
Publisher
Bentham Science Publishers Ltd.
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