BY ZHU JINMING

The Stars Regenerative Furnace Engineering Co.,Ltd, Nanjing Jiangsu 210016

Abstract: This paper mainly introduces the temperature difference on the length of billet of regenerative burner in the process of reheating furnace application. As to the temperature difference problem, we have made some reasonable adjustments and optimization of design, and resultantly we figure it out and bring excellent economic benefits.

Keywords: regenerative burner, reheating furnace, temperature difference, heating load

Preface

With the economy developing and market more competitive, businessmen have paid more and more attention to the cost and products’ quality. Nowadays, iron and steel plant is a kind of industry of high energy consumption, thus energy saving is especially important. In this case, regenerative burner starts to be applied into reheating furnace. Regenerative burner can not only use blast-furnace gas with high calorific value by preheating but also recover partial waste heat of flue gas in the process of preheating; in other words, double effects of energy saving and environment protection have been achieved. Thus, the prospect of regenerative burner is very promising. However, anything comes from scratch, and continuously improve, with no exception of regenerative burner. We go on gaining experience and knowledge from practice, and modulate structure and applying ways for an ideal effects.

Background

The first period constructing production of a scaled non stainless product line in FUZHOU yields a walking-beam furnace of 250t/h, at same time reserve a position for same scaled heating furnace. During the first period construction, there has been somehow uneven temperature on the length of billet. With the requirement of increasing yields, the second period project is prepared to start. Aiming at the first period’s problems, we make some adjustments to the second.

Optimization

1.      The first and the second’s reheating furnace both use double-regenerative combustion, taking blast-furnace gas as flue with a five-section reheating mechanism in which combustion can be controlled.

2.      Compared to the structure and combination of the first period, we make corresponding adjustments in the second.

(1)   Reheating furnace in the first period

Design data sheet:

(2)   Reheating furnace in the second period

Design data sheet:

Comparison

Through optimization, there are some changes on the matching amounts of coal gas regenerative chamber and air regenerative chamber, which it is 1air chamber verse 1 coal gas chamber in the first while it is 1:2. Thermal load on single regenerative chamber decreases and so do the pipe diameter of which connects to the chamber, thus increase the flexibility of regulating valve, which is helpful to control the ratio of temperature and air combustion. Meanwhile, regenerative chamber in the second has avoided the problem that one burner is unable to match air or coal gas in every section edge.

 Conclusion

After completion of the second, we can change 30-50 temperature difference of three thermocouples on the top of same furnace section, into around 15, which better meets the rolling mill process requirements and sharply increase yields. Because of the flexible modulating valves, it is easier to control the air flow, then, oxygen enrichment coefficient decreases, furthermore, oxide amount reduces. It can be concluded that the design optimization of the second has solved the prior temperature difference, as well as getting a better economic effects.