JPS5928317Y2 - heat storage brick - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heat storage brick for a hot blast furnace that supplies hot air to a blast furnace.

In recent years, high-temperature blasting has been required for the purpose of reducing the coke ratio in blast furnaces, and high-temperature blasting has been carried out as a countermeasure from an operational standpoint or by expanding the hot blast furnace capacity.

However, from an operational point of view, high-temperature air blowing is difficult to control, and expanding the capacity of hot blast stoves has the problem of dramatically increasing construction costs.

The present invention was developed to solve the above-mentioned problems, and by improving the shape of the through holes provided in the heat storage bricks, it is possible to cope with the increase in air temperature with the current capacity of the hot air stove, and to reduce the amount of thermal energy. It is an object of the present invention to provide a heat storage brick that can be used effectively and can blow high-temperature air.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Figure 1 shows a blast furnace 1 and a hot blast furnace 2 for supplying hot air to the blast furnace 1. Normally, about three hot blast furnaces are provided per blast furnace group, and hot air is supplied to the blast furnace one by one. 1.

The hot air stove 2 is divided into two parts: a combustion chamber 3 and a heat storage chamber 4. The gas heated in the combustion chamber 3 heats a heat storage brick 5 built into the heat storage chamber 4, and then the gas is cut off. By passing cold air through the heat-stored brickwork in the opposite direction to the gas, the cold air is preheated by heat conduction between the heat-storing bricks 5 and the cold air, and is supplied to the blast furnace 1 as hot air. .

As shown in FIG. 2, the heat storage bricks 5 of the present invention to be incorporated into the heat storage chamber 4 are formed, for example, in a hexagonal shape with through-holes 6 at the top and bottom, and a large number of bricks are assembled in a planar manner and densely arranged in the top and bottom.

Further, as shown in FIG. 3, the through hole 6 has a spiral uneven surface 7 formed on its inner circumference.

That is, the reason why the through hole 6 having the spiral uneven surface 7 as described above is provided in the heat storage brick 5 is that the heat transfer amount QGC (Kcal/hr) between the gas and the brick is QGC = hA (
Tc TB) However, h: heat transfer coefficient (Kcal/m2hr'C) A:
Heat transfer area (m2) T6: Gas temperature ('C) T8: Brick temperature ('C) Therefore, in order to increase the amount of heat transfer between the gas and heat storage bricks 5 in the hot air stove 2 of the same capacity, , it is necessary to increase the heat transfer coefficient and heat transfer area.

As a means for this, for example, by increasing the diameter of the through hole 6 to increase the heat transfer area, the heat storage brick 5
This results in a decrease in strength and poor durability.

Further, even if the heat transfer coefficient is increased by decreasing the pore diameter and increasing the gas flow rate, the reduction in the heat transfer area is dominant and the amount of heat transfer does not increase.

However, as shown in FIG. 3, by forming the inner periphery of the through hole 6 into an uneven surface 7 consisting of a spiral groove and a spiral collar, the above-mentioned problems can be eliminated and the amount of heat transfer can be increased.

In other words, if we consider the diameter d of the penetrating circular hole of the conventional heat storage brick and the section of the pitch P of the spiral hole with the same average diameter, the transmission area of the conventional circular hole and the spiral hole will be respectively, and the heat storage brick Not only can the heat transfer area be increased without reducing the strength of the heat storage brick 5, and an increase in the amount of heat transfer can be expected, but also the helical uneven surface 7 formed on the inner periphery of the through hole 6 of the heat storage brick 5 allows the gas to The film becomes thinner and the heat transfer coefficient can be increased.

In other words, the gas flow itself sent to the hot air stove 2 is a turbulent flow, but since this gas has viscosity, if the through hole is only a circular hole as in the past, there will be a laminar flow around the inner circumference of the circular hole. (layer) is formed, and as this thickens, the heat transfer coefficient decreases.

Therefore, the heat storage brick 5 of the present invention reduces the pitch P of the spiral uneven surface 7 formed on the inner periphery of the through hole 6, and the uneven surface 7 makes the gas flow flowing on the inner periphery of the through hole 6 turbulent. Therefore, the film is extremely thin and the heat transfer coefficient is increased.

As mentioned above, when heat exchange is performed between gas and heat storage brick at the same temperature and flow rate, the heat transfer coefficient is controlled by the thickness of the gas film, and therefore the spiral shape formed on the inner circumference of the through hole 6 It is clear that the heat transfer coefficient depends on each dimension.

In this way, a spiral uneven surface 7 is formed on the inner circumference of the through hole 6.
As a result of various experiments, the inventor of the present invention has confirmed that the heat transfer coefficient can be increased most in the vicinity of the ratios shown in FIG. 3 shown below.

P/d Ho1 h/d-=:0.08 As an example of the spiral uneven surface 7 having the above-mentioned dimension ratio, the spiral uneven surface 7 with d=40 mm Pl-42215 mm h=X=3 mm P=40 mm is used. FIG. 4 shows a comparison diagram of the gas temperature and heat transfer coefficient between the through-hole 6 and the conventional circular hole.

In FIG. 4, the solid line shows the heat storage brick 5 of the present invention, and the broken line shows the conventional heat storage brick.

As is clear from FIG. 4, the heat storage brick 5 of the present invention has a heat transfer coefficient approximately twice as large as that of the conventional heat storage brick.

If the heat transfer coefficient increases in this way, the heat exchange efficiency between the gas and the heat storage brick will increase, and the amount of heat stored in the high temperature section during combustion will increase, so the blowing temperature will rise significantly.

That is, if the heat storage brick 5 of the present invention is used under operating conditions in which a conventional heat storage brick can maintain a blowing temperature of 1200°C, as the heat transfer coefficient increases, the blowing temperature also increases as shown in FIG. When the thermal coefficient doubles, the air temperature also increases from 1200°C to 1238°C. Therefore, by simply using the heat storage brick 5 of the present invention in a hot air stove 2 with the same capacity as a conventional one, the air temperature can be increased by 38°C compared to the conventional one. can also be raised.

As mentioned above, the heat storage brick of the present invention has a spiral concavo-convex portion that satisfies the conditions of P/d-=1 h/d-character 0.08 on the inner periphery of the circular through-hole, which prevents contact with gas. Not only does the area increase, but the unevenness causes turbulence in the gas flow inside the circular through hole, which thins the boundary film and increases the heat transfer coefficient. This is a device that has an excellent effect of being able to raise the air temperature higher than before.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the relationship between a hot blast furnace and a blast furnace using the heat storage brick according to the present invention, Fig. 2 is a plan view showing an embodiment of the heat storage brick according to the present invention, and Fig. 3 is an outline of the same brick. FIG. 4 is a diagram showing the relationship between the gas temperature and heat transfer coefficient of the brick of the present invention and the conventional brick, and FIG. 5 is a diagram showing the relationship between the heat transfer coefficient ratio and the blowing temperature. 5 is a heat storage brick, 6 is a through hole, and 7 is an uneven surface.

Claims (1)

[Claims for Utility Model Registration] A heat storage brick characterized by having a spiral uneven surface that satisfies the following conditions on the inner periphery of a circular through hole. P/d-=:1 h/d-=:0.08 However, P: Pitch of spiral uneven surface d: Average diameter of through hole h: Depth of recess