JPH0135897B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a preheating zone without a burner in a heating furnace for heating billet material or the like.

In a conventional metal heating furnace, for example, as shown in FIGS. 1 and 2, a slab b in a heating furnace a is
are a preheating zone d, a heating zone e, and a heating zone e divided by a partition wall j.
While moving through the soaking zone f as indicated by arrow i,
Heated to 900-1200℃. The heating zone e and the soaking zone f have a ceiling burner g and a side burner h, but there is no burner in the preheating zone d, and the high temperature exhaust gas of 800 to 1000 degrees Celsius flowing from the heating zone e burns the top of the slab support c. Preheat slab b. In other words, the conventional preheating zone d is as shown in Fig. 1, and since the gas flow k flows only through easy-to-flow areas, large temperature stratification due to gas accumulation and draft occurs in the height direction of the preheating zone d. The effective gas radiation diameter was small, and the ceiling and hearth temperatures were lower than the gas temperature, so the effective rate of heat transfer was low. In addition, because the cross section within the preheating zone d was uniform and wide, the gas flow velocity was low at about 0.5 meters per second, and the amount of convective heat transfer was small. On the other hand, in order to improve the heat transfer efficiency of the preheating zone d, there is a jet preheating zone in which the exhaust gas is jetted onto the slab by a fan, but in this case, the power of the fan increases and the equipment cost increases, especially in hot charge slabs. The heat resistance of the fan is low at around 500℃,
This caused problems such as unusability. Furthermore, when the height H of the preheating zone d was lowered to increase convective heat transfer, the gas layer thickness decreased and the amount of radiation heat transfer decreased.

The present invention provides a preheating zone that does not rely on a fan, does not require gas to accumulate, is mixed well, reaches a high temperature, and can increase the amount of radiant heat transfer by alternately providing baffle plates. This is the purpose.

For this reason, the configuration of the present invention is such that in the preheating zone of the heating furnace where no burner is provided, the buttful plate with a distance between it and the ceiling to allow the gas flow to pass through, and the buttfull plate that is in close contact with the ceiling are connected to the heated material. are arranged alternately in the traveling direction of the gas flow, and the interval between the two baffle plates is within a range of 1 to 3 times the length in the height direction of the buffle plate that provides the distance through which the gas flow passes. It is characterized by

An embodiment of the present invention will be described below with reference to FIGS. 3 to 6.

3 and 4 show an embodiment of the present invention, in which 1 is a preheating zone, 2 is an arrow indicating the gas flow from the heating zone 13, 3 is a slab of the material to be heated, 4 is a slab support pipe, and 5 and 6 are buttful plates installed on the ceiling and hearth, respectively.

That is, in the preheating zone 1, a buttful plate 5 having a gas flow path m between the ceiling and the hearth, and a buttful plate 6 in close contact with the ceiling and the hearth, ) are provided alternately over the entire width of the oven.

The double plates 5 and 6 are made of heat-resistant metal, fire-resistant material,
Ceramic fiber is a good material to block gas radiation from the upstream side. Also, as shown in FIG. 4, the ceiling side bracket 5 is a heat-resistant metal hanging rod 7, and the hearth side bracket 5 is a pillar 8 made of fireproof material.
It is supported by

In this way, a distance m is provided between the baffle plate 5 and the ceiling or the hearth to allow the gas flow to flow, and the gas near the ceiling or hearth is flowed out, and the baffle plate 6 is in close contact with the ceiling or the hearth. The gas flow is made to flow along the slab 3 at a high velocity. The flow of these gases is indicated by arrow 2. In addition, because the low temperature gas near the hearth, especially the low temperature gas near the ceiling, is moved quickly, the gas in the preheating zone 1 is always at a high temperature, increasing heat transfer, and the gull flow under the buttful plate 6 is Convective heat transfer increases due to high velocity flow.

In Figure 5, the horizontal axis shows the gas temperature in the direction of the arrow, and the vertical axis shows the height H of the preheating zone shown in Figures 1 and 3.The dotted line 9 indicates the temperature of the conventional type without a full plate. The solid line 10 shows the temperature distribution of the present invention. In the present invention, this is the full plate 5.
and 6 are provided alternately, which means that the gases are sufficiently mixed, the diameter of the gas mass increases, and radiation heat transfer increases.

In addition, since the lower gas flow tends to rise to the upper part due to the draft, the main feature of the present invention is to provide a buttful plate at the upper part, that is, along the ceiling. It is desirable to install it at the bottom, that is, near the hearth, but the number of plates in the bottom buttfull should be less than the number of plates in the upper buttfull, so that the pressure loss at the bottom is less than the pressure loss at the top, and the gas flow rate between the upper and lower parts is equally divided. Try to make it.

Figure 6 is a curve diagram showing how high the slab that entered the preheating zone entrance at 30℃ rises at the preheating zone exit.
The horizontal axis represents the ratio l/n of the heightwise length n of the baffle plate 5 to the distance l between the buffle plates 5 and 6, and the vertical axis represents the slab temperature at the outlet of the preheating zone. Also dotted line 1
1 shows a conventional preheating zone without baffle plates, and curve 12 shows a preheating zone with buffle plates 5 and 6 as in the present invention. As is clear from the figure, the ratio l/n of 1 to 3 is efficient. That is, when the ratio l/n exceeds 3, it becomes close to the dotted line 11 with no buffling, and when it is less than 1, the gas layer thickness becomes small and the effect decreases.

The height H of the preheating zone is approximately 1.5 to 2.5 meters, and the higher the height, the better the efficiency, but if it exceeds 2.5 meters, the rate of increase in efficiency will decrease. Further, the distance m between the baffle plate 5 and the ceiling through which the gas flow passes depends on the balance with the pressure loss of the preheating zone, but for general use, it is approximately 1/3 of the length n of the buffle plate 5 in the height direction.

As described above, according to the present invention, one baffle plate is provided with a distance between it and the ceiling to allow the gas flow to flow, allowing gas near the ceiling to flow out, and the other buffle plate is in close contact with the ceiling to cover the gas flow. Because it flows at a high speed along the heating material, the low-temperature gas near the ceiling is moved quickly, and the gas in the preheating zone is always at a high temperature, increasing heat transfer and causing the gas to flow under the buttful plate that is in close contact with the ceiling. Since the gas flow in the gas flows at high speed, convective heat transfer increases. Moreover, since the one baffle plate and the other buffle plate are arranged alternately in the direction of movement of the material to be heated, the gases are sufficiently mixed, the diameter of the gas mass increases, and radiation heat transfer increases. Moreover, the radiant heat transfer increases as the cold gas near the ceiling is flushed out and the hot gas flows in. In particular, the distance between the two buttful plates,
Since the distance through which the gas flow is made is 1 to 3 times the length in the height direction of the baffle plate, efficiency is high as described in FIG. 6 above.

[Brief explanation of drawings]

Fig. 1 is a sectional side view of a conventional heating furnace, Fig. 2 is a sectional front view of Fig. 1, Fig. 3 is a sectional side view showing an embodiment of the present invention, and Fig. 4 is a sectional side view of Fig. 3. Cutting line A
5 is an explanatory diagram of the gas temperature distribution in the preheating zone, and FIG. 6 is an explanatory diagram of the baffle plate spacing. 1... Preheating zone, 2... Arrow showing the flow of gas from the heating zone, 3... Slab as heated material,
4... Slab support pipe, 5, 6... Bound full board, 7... Bound full board hanging rod, 8... Bound full board support, 13... Heating zone.

Claims (1)

[Claims] 1 In the preheating zone where no heating furnace burner is installed,
Baffle plates with a distance between them and the ceiling for allowing gas flow to pass therethrough and buffle plates that are in close contact with the ceiling are arranged alternately in the direction of movement of the material to be heated, and the interval between the two buffle plates is equal to A preheating zone of a heating furnace characterized by having a length in the range of 1 to 3 times the length in the height direction of a buttful plate provided with a distance through which a gas flow is passed.