在擴(kuò)散燃燒時(shí)，火焰的形狀是長(zhǎng)矩形，火焰內(nèi)部是燃料氣，外部是助燃空氣，燃料氣與空氣的混合是依靠擴(kuò)散方式進(jìn)行。當(dāng)開始預(yù)混空氣后，火焰的形狀開始發(fā)生變化.

In diffusion combustion, the shape of the flame is long rectangle, the fuel inside the flame is external, the external combustion air is, the mixing of fuel gas and air depends on the diffusion mode. When the air is premixed, the shape of the flame begins to change.

燃料氣與空氣的混合物在燃燒焰面法線方向的速度分量大于該混合物的火焰?zhèn)鞑ニ俣龋瑒t火焰被推出火孔，開始離焰，直到火焰被吹跑造成火焰熄火——脫火。燃燒器發(fā)生脫火是不允許的。

The velocity component of the mixture of fuel gas and air in the normal direction of combustion flame is larger than that of the mixture, and the flame is pushed out of the fire hole and starts to leave the flame until the flame is blown away, causing the flame to go out. It is not allowed to remove fire from the burner.

加熱爐能快速加熱，氧化和脫碳少，適用于加熱圓形料坯和鋼管。與行星軋機(jī)相配合，可用來(lái)加熱連鑄板坯；也可對(duì)某些鋼材進(jìn)行局部加熱。缺點(diǎn)是單位爐長(zhǎng)的生產(chǎn)能力低，爐子熱效率較低。

The heating furnace can be heated quickly, with less oxidation and decarburization, and is suitable for heating round billets and steel pipes. It can be used for heating continuous casting slab and heating some steel products. The drawback is that the production capacity of unit furnace length is low and furnace thermal efficiency is low.

對(duì)流傳熱：對(duì)流傳熱是爐氣與鋼材表面接觸時(shí)的熱交換過(guò)程，包括爐氣各部分發(fā)生位移所產(chǎn)生的對(duì)流作用及爐氣分子之間的導(dǎo)熱作用。

Convective heat transfer: convection heat transfer is the heat exchange process of the contact between the furnace gas and the steel surface, including the convection of the displacement of each part of the furnace gas and the heat conduction between the molecules of the furnace gas.