JPS59113967A - Drying and heating device of pan for metallurgy - Google Patents

Abstract

PURPOSE:To provide a titled device which dries and heats uniformly lining refractories with good efficiency by the constitution wherein a heat transmitting and converting device consisting of an air-permeable, heat-resistant metal is provided in a pan for metallurgy, radiation heat is generated from the surface thereof and the flow of the combustion gas in the pan is made uniform. CONSTITUTION:A pan-shaped heat transmitting and converting device 13 consisting of an air permeable heat resistant metal or ceramic is provided in tight contact with a pan cover 6 in the upper space of a heating burner 7a positioned near the refractories 4 in the bottom of a ladle. An air piping 9a and fuel gas piping 10a for combustion connecting to the burner 7a are provided in said device. The combustion gas generated from the burner 7a forms flow 11 which dries and heats the refractories 4, brick masonry 5 in the corner part and lining refractories 3, whereafter the gas enters the device 13 and heats the device to a high temp. thereby generating radiation heat. The gas preheats further the air for combustion and gaseous fuel thus decreasing its temp. by itself. Such gas is discharged through a waste gas port 8.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a so-called pot drying and heating device used in the metallurgical industry. It provides equipment.

A so-called pot is used in the steel industry to receive hot metal or molten steel, transport it, temporarily hold it, and cast it into a mold.There are hot metal pots, molten steel ladles, tundishes, etc. Various types of pots are used in the industry, and they are also widely used in the non-ferrous metal industry.

These pots are lined with firebricks or monolithic refractories, but in recent years, as the conditions for their use have become more severe, improvements have been made in the quality of firebricks, the development of monolithic refractories, and the spraying of such materials. However, when the lining refractory is damaged beyond its service life due to abrasion caused by the agitation of molten steel and its flow, reaction with slap, repeated heating and cooling, etc., it must be rebuilt. In addition, spraying with monolithic refractories is carried out during intermediate repairs.These installed refractories contain moisture, so if molten steel, etc. is accepted as it is, it will explode due to rapid heating, so this should not be done. To prevent this, the moisture in the refractory must be sufficiently removed before reuse.In addition to removing moisture, the lining refractory must be heated to raise the temperature inside the pot before pouring the molten metal. Acceptance is common practice.

Drying and heating of the pot for this purpose has conventionally been carried out as shown in FIG. In other words, Figure 1 is a longitudinal cross-sectional view of the ladle, where 1 is the outer shell, 2 is the inner wall of refractory bricks built on the inside, also called permanent lining, and 3 is the poured inside. It is a castable refractory and is also called work lining. 4 is a refractory built at the bottom of the pot (also called a lining), and the outside is castable castable refractory.
The inside is lined with firebrick. 5 is a part of the corner brickwork to protect the part of the corner that is particularly severely damaged by the use of pots.

For example, the thickness of the pot is 4.2 m in inner diameter at the top and 3 m in inner diameter at the bottom.
, 7 m in length and 6.8 m in depth, and is covered with a pot lid 6 during dry heating, and an opening for installing a heating burner 7 and one to six combustion exhaust gas ports 8 are provided in the center. It is. 9 is a combustion air pipe, and 10 is a fuel gas pipe.

Dry heating of a pot is performed by sealing the top with a pot lid 6, burning fuel such as C gas in a burner 7, jetting out combustion gas in the right direction, and discharging the combustion gas from a combustion exhaust gas port 8.
The flow of the combustion gas is approximately as shown in Figure 11, and the radiant heat and convective heat transfer of the combustion gas cause the lining refractory 3
．． 4.5 is heated, but in such devices and methods, the thermal efficiency (absorbed heat amount of refractory lining/generated heat amount x 100
) is an extremely low numerical coefficient, and the actual situation is that high-temperature combustion gas of 700 to 1100° C. is discarded from the exhaust gas port 8.

To improve this, it is possible to introduce high-temperature exhaust gas into a recuperator to preheat the fuel gas and combustion air, but if you try to recover enough sensible heat from high-temperature exhaust gas, the scale of the recuperator will become extremely large. Therefore, it is a problem with the equipment.

On the other hand, since the flow of combustion gas is as shown in Fig. 1, the bottom refractory 4, corner brickwork 5, and their surroundings are not sufficiently heated and moisture removal is delayed, so dry heating of the entire pot is not necessary. The reality is that it takes 50 to 60 hours to complete, and therefore the total amount of heat required to dry one pot is extremely large (uneconomical).

In order to improve this type of uneven heating, attempts have been made to make the burner 7 movable up and down as shown in Figure 2, and to bring it down to the bottom for combustion, but this method requires proper flow of combustion gas. On the contrary, the drying of the refractories on the upper part of the inner wall tends to be delayed, and it is difficult to control the drying and heating of the whole part evenly.
However, since the fuel pipe 10 is directly exposed to high temperatures, it has many disadvantages as a practical technology, such as the need for a special material.

As explained above, the drying and heating of conventional pots has a hole in terms of thermal efficiency.
At present, there are still many problems in terms of efficiency, equipment, and technology.

This invention was made to solve the above problems, and its feature is that most of the space above the heating burner located near the bottom of the pot is made of breathable heat-resistant metal or ceramic. It is surrounded by a tin cane container (hereinafter referred to as the "heat transfer exchange device") manufactured in As it rises, it passes through the heat transfer conversion device and is heated, and it is further circulated upward through the space inside the heat transfer conversion device and discharged to the outside from the exhaust gas port, where it is heated and reaches a high temperature. This is a drying and heating device that further dries and heats the lining refractory using radiant heat.

This invention will be explained based on drawings showing embodiments.
FIG. 3 is a longitudinal side view of the ladle shown in FIG.
A burner support rod 12 made of heat-resistant steel coated with a castable refractory is fixed to the pot lid 6 at a central position separated by w. The interior space above the burner is mostly delimited by a heat transfer device 13. That is, as shown in the figure, the heat transfer converter 13 has almost the same shape as a smaller pot, and the distance from the side wall refractory 6 of the pot is about 100 m, and the upper part is crimped to the pot lid 6 and can be opened. It is fixed so that it does not have 11 parts.

The heat transfer/conversion device 13 is made of heat-resistant steel, nickel steel, or ceramic in the form of wires, coils, nets, fibers, porous plates, etc., which are laminated as appropriate to a thickness of 10 to 20 m and have high air permeability. It is a solid, has a high thermal emissivity, a small heat capacity, and a large surface area (it is an air-permeable heat-resistant plate with a moderate flow resistance, and the wire diameter is 0.8 m in the example shown in Fig. 3).
1 piece of high Ni disease Cr stainless steel wire mesh with a mesh spacing of 2.4-
0 sheets were used with a thickness of approximately 10 m.

In the space inside the heat transfer conversion device 13, a coiled combustion air pipe 9a and a fuel gas pipe 10a are arranged, the lower ends of which are connected to the heating burner 7a, and the upper ends of which pass through the pot lid 6. and are connected to the air blower and fuel supply mains, respectively.

In this dry heating device, the swirling flow of combustion gas generated when the burner 7a is fired first flows around the space above the bottom of the pot and sufficiently heats the bottom refractory, and then the hollow formed by the side wall and the heat transfer device. The side wall refractories are heated by convection electric heat and radiant heat of the combustion gas as it ascends through the circular mound-shaped space.

Next, the combustion gas passes through a highly permeable heat transfer conversion device, and further passes through an air pipe 9a and a fuel gas pipe 1 in the internal space.
0a is heated and discharged to the outside from the exhaust gas port 8a in the center of the pot lid. The heat transfer conversion device is made of the materials mentioned above and has a large surface area, and since it is a thin metal wire, it has an extremely high convection heat transfer coefficient, so its surface is heated to a high temperature by the passage of combustion gas. That is, as the combustion gas flows in the thickness direction, heat is taken away one after another, so the outer periphery of the heat transfer conversion device (the surface facing the side wall of the pot) becomes high temperature close to the combustion gas temperature, but the temperature rapidly increases in the thickness direction. descend.

Therefore, most of the radiant energy from the heat transfer device contributes to heat transfer to the side wall of the pot, and the contribution of heat transfer inward is extremely small. In addition, the effect of the reduction in the amount of radiant heat transfer caused by the reduction in the thickness of the combustion gas layer in the pot due to the installation of a heat transfer conversion device,
The increase in the amount of convective heat transfer due to changes in the flow of combustion gas and the amount of radiant heat transfer from the surface of the heat transfer converter due to its installation is overwhelmingly large, and the heating efficiency is greatly improved.

In addition, the flow of combustion gas in the pot when using the device of this invention is such that the space in which the high-temperature gas is held is narrow and the gas flow path is restricted, so there is no short-circuit flow of combustion gas to the exhaust gas port. Also, the delay in temperature rise around the part of the brickwork at the bottom corner of the pot is greatly improved.

FIG. 4 shows point a (part of the inner corner of the pot) in the conventional device shown in FIG. 1 and the embodiment of the present invention shown in FIG. 3, respectively.
, is a graph showing the results of actual measurement using a thermocouple thermometer of the temperature increase over the course of drying and heating time at point b (inside the side wall) and point 0 (inside part of the corner). That is, when comparing the two, the difference in the drying and heating effect between the conventional device and the example is clear from the table above.

In addition, the measurement results of heat calculation in the conventional device and the example are shown in the first section.
Shown in the table.

Table 1 Note: The measurement force method for thermal calculation is based on JIS z9202.

That is, the dry heating of the device of this invention, compared to the conventional device, contributes to the radiation heat transfer of the heat transfer conversion device, improves gas convection, reduces the amount of fuel input per hour due to preheating of fuel and air, and reduces the amount of fuel input per hour due to the preheating of fuel and air. The preheating of the exhaust gas brings about remarkable effects such as a reduction in sensible heat loss, resulting in a significant improvement in thermal efficiency.
The fuel required for drying was reduced by about 1/2, and the time required for drying was shortened by 14 hours.

In the embodiment shown in FIG. 6, the bottom part of the heat transfer converter 16 is made of a non-ventilated ordinary refractory plate, and is made of the same material as the other side cylindrical part, so that the ventilation resistance is lowered from the side part. It goes without saying that even if a thicker breathable material is used, the same effects as in the embodiment shown in FIG. 3 can be obtained by appropriately adjusting the amount of burner combustion and the gap between the burner and the bottom.

This inventive device can be attached to and detached from the inside of the pot using the lifting device 14.
It will be done. That is, the pots that have been reassembled with large linings or have undergone intermediate repairs are moved to a predetermined work area by the moving trolley 15.
Separately, the main body of this first invention device, in which a heating burner, combustion air piping, and fuel gas piping are set in a heat transfer conversion device, is inserted into the center of the pot using the lifting device 14. At this time, the other end of the supply pipe to the burner outside the pot is connected to the air blower and the fuel main pipe, respectively, by flexible pipes so as not to interfere with the lifting and lowering of the apparatus. Next, the pot lid 6 is set and fixed to the upper part of the heat transfer device to seal the opening. The determination of the drying Φ heating time from the start of combustion until it stops varies depending on the condition of the installed refractory and the relative positional relationship between the pot and the heat transfer conversion device (the size of the pot is not necessarily constant). The required time can be set in advance based on the temperature curve inside the pot and the measurement data of the residual moisture in the refractory material.

Next, the combustion air piping and fuel gas piping in this device are installed in the space inside the heat transfer conversion device as described above, but the combustion gas that has passed through the heat transfer conversion device is
Since it has enough sensible heat to heat the air and gas in the pipes to an appropriate temperature at 0°C, the pipes are shaped to easily absorb heat, such as a coil shape or a large number of heat-absorbing studs as shown in Figure 3. The fuel consumption of the device can be reduced by effectively exchanging heat with the attached shape. By doing this, the temperature of the exhaust gas from the exhaust gas port 8a can be lowered to 200 to 300°C, and the overall equipment is more compact and has better heat exchange efficiency than installing separate heat exchange equipment outside the pot. This is effective in reducing fuel consumption.Since over-preheating of fuel gas causes cracking, the combustion gas that has passed through the heat transfer converter first heats the air piping and then heats the fuel gas piping. As shown in FIG. 3, it is desirable to arrange the former on the outside and the latter on the inside to prevent cracking.

As another example of piping that effectively preheats combustion air and fuel gas and prevents fuel cracking,
The figure shows a longitudinal cross-sectional view of the device mounted on a ladle, and FIG. 6 is a plan view of the device, in which 7b is a heating burner, 13 is a heat transfer converter, and 9b is located on the outside (combustion gas side) and has a large surface area. A combustion air pipe 10b is provided with a heat absorbing stud 16 for effective heat exchange, and 10b is a fuel gas pipe disposed in contact with the inside of 9b. By piping in this way, cracking of the fuel gas can be completely prevented.

Since this invention has the configuration as explained above, ■
The flow of combustion gases regulated by heating burners and heat transfer devices near the bottom provides the most effective convective heat transfer to the bottom, corners, and side walls of the pot.

(2) By making the combustion gas pass through a heat transfer and conversion device disposed opposite to the pot lining refractory to raise the temperature to a high temperature, the lining refractory is heated more effectively by the radiant heat.

■ The residual sensible heat of the combustion gas is fully utilized for preheating the air and fuel gas by the heat exchange device installed in the heat transfer conversion device, which significantly lowers the exhaust gas temperature and improves the combustion efficiency of the heating burner. Improve.

(2) As a result of the above, the thermal efficiency has been improved from the conventional several inches to more than 20%, the time required for drying has been shortened from 55 hours to 41 hours, and the entire refractory lining can be dried evenly.

■ The fuel gas can be preheated to prevent cranking.

Has the effect of equal length (

[Brief explanation of the drawing]

Figures 1 and 2 are longitudinal cross-sectional views showing the situation in the ladle of a conventional drying and heating device, Figure 6 is a vertical cross-sectional view showing an embodiment of the present invention, and Figure 4 is drying heating time and position of the ladle. 5 and 6 are longitudinal cross-sectional views showing another embodiment of the present invention, and a cross-sectional view taken along the line A-A in FIG. 5. . In each figure, 2...Permanently lined refractory, 6... Lining refractory, 4...
... Bottom refractory, 6... Pot lid, 7.7a, 7b...
・Heating burner, 8.8a = -exhaust gas port, 9.9a
r 9 b...Combustion air piping, 10.10a, 1
0b...Fuel gas piping, 11...Flow of combustion gas,
13... Heat transfer cost Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. In the center of the upper space of the heating burner located near the bottom of the metallurgical pot, and surrounding most of the space (made of air-permeable heat-resistant metal or air-permeable ceramic). A drying and heating device for a metallurgical pot, characterized in that a heat transfer and conversion device that can be raised and lowered is provided in contact with a pot lid, and a lining refractory is dried and heated by the radiant heat of the heated heat transfer and conversion device.2. At the center of the upper space of the heating burner located near the bottom of the metallurgical pot, and so as to surround most of the space, there is provided a heat transfer and conversion device made of breathable heat-resistant metal or breathable ceramic that can be moved up and down. The refractory lining is dry-heated by the radiant heat of the heated heat transfer converter, which is provided in contact with the pot lid, and the piping for combustion air and fuel gas to be supplied to the heating burner is arranged to cover the entire surface area. A drying and heating device for a metallurgical pot, characterized in that it is provided in the heat transfer conversion device. Claim 2
A drying and heating device for a metallurgical pot as described in 1.