JPH09101023A - Furnace body cooling structure for plasma melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive the elongation of life of a furnace body and maintain a melting thermal efficiency optimally at the same time by a method wherein a cooling water belt is divided along the peripheral direction of a furnace and the cooling capacity, generated by the cooling water flowing through the divided chambers, is controlled in accordance with an atmospheric temperature in the circumferential direction of the furnace. SOLUTION: A melting furnace 4 is structured so as to have the lining of refractories 5 and the outer periphery of the same is covered by cooling water jacket 6. The water cooled jacket 6 is divided into eight cooling belts A-H by partitioning plates 11a, 11b,...11h so as to be symmetry about the center of a vertical surface connecting a tapping port 8 and an incineration ash supplying port 7. The flow rates of cooling water Q1-Q8 in respective cooling belts A-H are permitted to be increased or reduced independently in accordance with the temperature condition in the furnace respectively. In this case, the cooling water belt is preferably divided into positions having the central angle of at least ±30 deg. in the circumferential direction about the tapping hole 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace body cooling structure for a plasma melting furnace, and more particularly to a furnace body cooling structure for a plasma melting furnace capable of prolonging the life of the furnace body and at the same time maintaining an optimum melting heat efficiency. It is about.

[0002]

2. Description of the Related Art As a conventional furnace body cooling structure for a plasma melting furnace, a structure shown in FIG. 5 is known. That is, FIG.
FIG. 4 is a schematic explanatory view showing a cylindrical plasma melting furnace 4, and the plasma torch 1 is inserted and arranged from the center of the upper part of the melting furnace 4. The plasma arc 9 serving as a heat source for melting is supplied with a direct current from the power supply device 2 having a built-in AC / DC converter, using the plasma torch 1 as an anode, the molten slag bath 10 and the bottom of the furnace provided at the bottom of the melting furnace. It is configured to flow to the cathode 3.

Then, the incineration ash that is the material to be melted is introduced into the melting furnace 4 through the supply port 7 provided in the upper part of the melting furnace 4. The incinerated ash charged is heated to the melting temperature by the high-temperature plasma arc 9 irradiated from the plasma torch 1 to become molten slag, and the slag bath 10 is formed.
The molten slag overflows from the outlet 8 on the inner side of the furnace and is discharged to the outside of the furnace.

Further, the melting furnace 4 is lined with a refractory material 5, and the outer periphery thereof is structured so that the refractory material 5 can be cooled from the surroundings with cooling water. Further, the cooling structure 6 is
The entire circumference of the melting furnace 4 is covered, and consideration is given to extending the life of the refractory material 5.

[0005]

The temperature inside the furnace is 2000 °.
In principle, it is effective in principle to provide a water-cooled structure in order to protect the refractory material in an environment of C or higher, and to apply self-coating of slag to the inside of the furnace due to its cooling effect. However, since the atmospheric temperature in the furnace is not constant throughout, there is a problem in uniformly applying the same degree of water cooling to the entire circumference of the furnace body. That is, the atmosphere in the vicinity of the incineration ash supply port 7 is the lowest, about 1000 ° C, and the vicinity in the incinerator ash 8 is the highest, over 2000 ° C. Therefore, the in-furnace portion that must be particularly considered for protection of the refractory 5 should be limited to the refractory near the outlet port 8.

Further, if the water is evenly cooled along the entire circumference of the melting furnace 4, heat is taken away by the cooling water and the temperature in the furnace is lowered even in a place where only the refractory structure can withstand the temperature. On the contrary, in the vicinity of the incinerator ash supply port 7 where the temperature is to be positively increased, the amount of heat used for melting the incinerated ash is deprived by the cooling water, and the melting heat efficiency is lowered.

On the other hand, there are special precautions for protecting the vicinity of the outlet 8. That is, if the refractory is protected too much and cooled too much, another problem such as clogging due to solidification of slag at the slag spout 8 may occur. Therefore, under conditions that do not cause such clogging. Refractory protection must be realized.

Therefore, the invention according to claim 1 of the present invention provides a furnace body cooling structure for a plasma melting furnace capable of prolonging the life of the refractory material of the plasma melting furnace and at the same time maintaining the optimum melting heat efficiency. The purpose is to do.
In addition to the object of the invention described in claim 1, the invention described in claim 2 provides a furnace body cooling structure for a plasma melting furnace capable of preventing blockage at a slag opening and performing stable continuous operation. With the goal.

[0009]

To achieve the above object, the invention according to claim 1 of the present invention provides a cooling water zone on the outer periphery of a furnace body of a plasma melting furnace having a refractory structure, and the cooling water is provided. A structure for cooling the furnace body of the plasma melting furnace by circulating cooling water in the zone, the cooling water zone is divided along the circumferential direction of the furnace body, and the cooling ability by the cooling water flowing through each division chamber Is provided in accordance with the ambient temperature in the peripheral direction of the furnace.

The refractory material in the melting furnace generally becomes more reactive with the surroundings as the temperature of the atmosphere with which it comes into contact increases. Further, the flow of the molten slag bath abrades the refractory material in the contact area. This also has a large effect on the temperature of the refractory, and when the temperature rises, the amount of wear also increases. Therefore, when considering protection of refractories, it is certain that the first condition is to first lower the temperature of the refractory itself.

Further, by lowering the temperature, the protective effect of self-coating the slag can be obtained. That is, the protective effect of the self-coating of the slag is to lower the temperature of the refractory, solidify the molten slag in contact, and coat the refractory surface with the slag itself to isolate the refractory from the high temperature atmosphere in the furnace. The effect is to suppress the above reaction and wear.

However, these effects are usually expected when the melting furnace is operated at an ambient temperature of 1300 ° C. or higher and the temperature of the molten slag is 1100 ° C. under low temperature conditions. There should be no need for refractory protection in. In the melting furnace, when heating the incineration ash that is the material to be melted, it is preferable to absorb the heat energy from the plasma torch as efficiently as possible, and the water cooling of the refractory as described above is rather negative in terms of melting heat efficiency. . However, inside the melting furnace, 20
A high temperature region of 00 ° C or higher and a low temperature region of about 1000 ° C coexist, and there is a part where it is not always necessary to strongly protect the furnace body with cooling water.

Therefore, the inventors of the present invention detect the high temperature region and the low temperature region in the furnace, protect the furnace body with a water cooling effect in the high temperature region of 2000 ° C. or higher, and cool the low temperature region as much as possible. The means for suppressing and effectively utilizing the thermal energy of the plasma gas in the melting furnace was investigated. Specifically, to realize a means that can perform a series of automatic controls independently and in correlation with each other in the cooling capacity control in the high temperature area near the outlet of the molten slag and the low temperature area near the supply port of the incineration ash. I repeated my studies.

In this case, there are some matters to be considered. In other words, considering only thermal efficiency, it is important in principle to transfer the thermal energy of the plasma gas to the incineration ash in the low temperature region as efficiently as possible. Can be taken. However, since the plasma gas has a high temperature of 2000 ° C. or higher, for example, during steady operation such as stable and continuous supply of incinerated ash, even in the case of an adiabatic structure, during preheating or no-load operation, etc. In some cases, the temperature inside the furnace may reach 2000 ° C or higher. In such a case, refractory must be cooled to protect the furnace body.

Therefore, in consideration of such a point, the cooling water zone provided on the outer periphery of the furnace body is divided into a plurality of pieces in the circumferential direction, and
It is possible to employ means peculiar to the present invention, which monitors the atmosphere temperature in the furnace in the circumferential direction and controls the amount of cooling water so that the cooling capacity of each divided chamber can be strengthened or suppressed in accordance with the indicated temperature. By this means, the life of the refractory material of the melting furnace can be extended, and at the same time, the heat efficiency of melting can be optimally maintained. As a concrete control means of the cooling ability by the cooling water, generally, the cooling water amount is increased when the furnace atmosphere temperature is high, and is decreased when the furnace temperature is low.

In this case, the command to increase / decrease the amount of cooling water is based on the amount of change in the temperature of the atmosphere in the furnace. However, after being cooled in each division chamber, it is discharged from each division chamber. It is also possible to constantly monitor the temperature and flow rate of the cooling water, detect the degree of deviation of the discharged heat amount from a predetermined set value, and control the cooling capacity of each divided chamber on the basis of this change amount.

The phrase "controlling the cooling capacity of the cooling water flowing through each of the divided chambers" does not necessarily mean that all of the divided chambers are always controlled by increasing or decreasing the amount of cooling water, but some of the dividing chambers. Specifically, it is meant to include the case where the air-cooling control is applied to the divided chambers located in the low temperature region near the incinerator ash supply port.

Further, the present inventors have tried to find the optimum positioning as a division chamber required for independent enhanced cooling in order to improve the accuracy of the furnace body cooling control in the vicinity of the outlet, which is particularly likely to cause a problem. First, an experimental operation was performed to confirm the refractory surface temperature and the state of the self-coating of slag when the cooling capacity was changed in the circumferential direction of the furnace body. That is, as shown in FIG. 5A, the circumferential direction is divided into four, A, B, C, and D, and the cooling capacity of each divided chamber is A = B <C = D and the cooling capacity on the C and D sides. Was controlled to be twice the cooling capacity on the A and B sides. FIG. 5 shows the result of examining the relationship between the circumferential position of the division chambers and the corresponding refractory surface temperature for each of the division chambers A, B, C, and D when the steady operation is reached. It is (b). The shaded area in FIG. 5A shows the situation in which the coating layer of slag is formed.

From the results of these experiments, when the cooling capacity is enhanced, the slag is coated from a position advanced by about 30 ° in the D direction around the outlet as shown in FIG. 5 (a). I know that This is because if the cooling capacity is too high in the part D, another problem such as blockage of the outlet can occur, so the cooling capacity is at least ± 30 ° in the circumferential direction from the outlet to the circumferential direction. This is because you cannot raise it. On the other hand, the cooling capacity from D to C tends to be too high. Therefore, the central angle ±
If the cooling water zone is divided at the 30 ° position, the vicinity of the outlet can be appropriately controlled without blocking the outlet, while the cooling capacity from D to C can also be controlled independently. It is possible not to reduce the thermal efficiency. Based on the above experimental results, as the invention according to claim 2, it is possible to adopt a peculiar configuration in which the cooling water zone is divided at positions with a central angle of ± 30 ° in the circumferential direction around at least the outlet. It is a thing.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are schematic explanatory views showing a furnace body cooling structure of a plasma melting furnace according to the present invention.
The same components as those of the conventional example shown in FIG. 6 are designated by the same reference numerals to avoid redundant description.

In FIG. 1A, the melting furnace 4 is a refractory 5
Is lined, and the outer periphery thereof is covered with a water cooling jacket 6 for cooling the refractory 4.
The refractory material cooled by the water cooling jacket 6 may extend to the side surface and the upper portion of the melting furnace 4, but since the location where the refractory material is most damaged is the upper space containing the molten slag 10, the lower side surface must be the same. It does not require cooling.

The water cooling jacket 6 is shown in FIG.
As shown in (a) a schematic cross-sectional view taken along the line X-X), eight coolings are made symmetrical about a vertical plane connecting the slag port 8 and the incineration ash supply port 7 with partition plates 11a, 11b, ..., 11h. It is divided into bands A to H. Cooling water Q1 in each cooling zone A to H
The flow rates of Q8 to Q8 are configured so that the flow rates can be individually increased or decreased depending on the temperature conditions in the furnace. The ambient temperature in the furnace is measured by using the measured temperature of the refractory inside the furnace.

FIG. 2 shows the temperature distribution in the refractory material in the cooling zones A, B, C and D. In this case, the refractory thickness and the cooling water flow rate are set under the same conditions. A is a cooling zone in contact with the refractory near the outlet port 8,
B and C are cooling zones in contact with the refractory located in the middle of the incineration ash supply port 7 and the slag discharge port 8, and D is a cooling zone in contact with the refractory near the incineration ash supply port 7. That is, A is a cooling zone in charge of controlling the region where the atmospheric temperature in the furnace is the highest, and the temperature of the refractory material is also the highest.

Further, in the area D near the supply port 7, since the thermal energy of the plasma gas is consumed for heating the incineration ash, the ambient temperature becomes lower than that near the outlet 8 and the temperature of the refractory is also the lowest. This is the cooling zone in charge of control. In addition, B,
C is a cooling zone in charge of controlling an intermediate temperature region near the slag port 8 and the incineration ash supply port 7.

As a result of a series of plasma melting furnace operations performed so far, the present inventors have found that there is a constant value between the refractory temperature and the state of formation of a self-coat of slag on the refractory surface, which appears as an effect of cooling. I confirmed that there is a relationship. That is,
FIG. 2 is a diagram showing a region where the self-coating is not formed on the upper side and a region where the self-coating is formed on the lower side with respect to the refractory temperature θ1.

Now, assuming that the refractory thickness a on the horizontal axis is the refractory position near the inner surface of the furnace, the refractory surface temperature exceeds the self-coating boundary temperature θ1 in FIGS. In this state, the self-coating is not formed, so the refractory will be damaged if it is left as it is. Therefore, in order to deal with this, it is necessary to further strengthen the cooling performance of A and B and lower the temperature of the refractory material. Further, in C and D, the refractory surface temperature is lower than θ1, and the self-coating is formed.

In such an operating condition, it is rather inefficient to uniformly cool the melting furnace, and the cooling zone A is intensively strongly cooled and B is normally cooled.
Further, regarding C and D, it can be seen that the cooling performance may be small. However, the ambient temperature in the furnace, that is, the temperature of the refractory, continuously changes without endurance according to the operating conditions of the melting furnace, and it is necessary to appropriately control the cooling performance.

This can also be understood from the results of a series of melting furnace operations. That is, FIG. 4 is a diagram showing the results of examining the relationship between the change over time of the refractory temperature in the vicinity of the refractory furnace inner surface in the cooling zone D and the operating conditions of the melting furnace at that time, and the solid line in the figure is Shows the refractory temperature when the cooling performance is constant over the entire circumference of the melting furnace.

When the incinerator ash is charged into the melting furnace with a load of 100%, the refractory temperature goes to θ1 or less, so cooling performance is not so required, but the incinerator ash is not supplied during preheating operation of the melting furnace. During the standby operation, the refractory temperature continues to rise beyond θ1, so that it reaches a region where the refractory may be affected. It is also understood that the refractory temperature needs to be carefully monitored even when the load of supplying the incinerator ash to the melting furnace is changed (50% load in the figure).

[0030]

[Embodiment 1] An embodiment in which the amount of cooling water is controlled according to the temperature of the atmosphere in the furnace will be described with reference to FIGS. 12 of FIG.
, 12h indicate temperature measuring points. That is, instead of measuring the atmosphere temperature in the furnace, the temperature in the vicinity of the inner surface of the refractory furnace was measured, and the flow rates of the cooling waters Q1 to Q8 were controlled according to the results. The curve shown by the broken line in FIG. 4 is obtained by plotting the change over time of the refractory temperature when the cooling control of the cooling zone D is performed using this method.

From this result, even if the operating conditions of the melting furnace are changed, the refractory temperature is well controlled so as not to exceed the boundary temperature θ1 of the self-coating, and sufficient consideration is given to extending the life of the refractory. It is easy to see that the driving is being performed.

[0032]

[Second Embodiment] This is equivalent to a modification of the first embodiment, and in the regions A, B, G, and H in which the atmospheric temperature in the furnace is high, the refractory is always protected by cooling water, and the temperature is relatively low. C,
For D, E, and F, air cooling (air cooling method) control was performed. Also in this case, it was confirmed that effective control can be performed almost in the same manner as in the first embodiment. This modified example focuses on the advantage that the air-cooling method can do so, while the so-called On-Off control cannot be performed by the water-cooling method.

[0033]

As described above, the invention according to claim 1 of the present invention makes it possible to prolong the life of the refractory material of the plasma melting furnace and at the same time maintain the optimum melting heat efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram showing an overall configuration of an embodiment according to the present invention.

FIG. 2 is a diagram showing a temperature distribution in a refractory material in cooling zones A, B, C and D.

FIG. 3 is an explanatory diagram showing a positional relationship between a divided cooling zone formed on the outer periphery of the furnace body and a temperature measurement point of the refractory surface temperature inside the furnace.

FIG. 4 is a diagram showing a change with time in refractory temperature when cooling control is performed near the incinerator ash supply port of the melting furnace according to the present invention.

FIG. 5 is a diagram showing an experimental result when the cooling capacity is changed in the circumferential direction, (a) is a schematic cross-sectional view of a melting furnace for explaining the in-reactor situation at that time, and (b) )
FIG. 4 is a diagram showing a relationship between a cooling zone position at that time and a refractory surface temperature corresponding to the position.

FIG. 6 is a schematic explanatory view showing a furnace body cooling structure of a conventional plasma melting furnace.

[Explanation of symbols]

 1 Plasma Torch 2 Power Supply Device 3 Bottom Cathode 4 Melting Furnace 5 Refractory Material 6 Water Cooling Jacket 7 Incinerator Ash Supply Port 8 Outlet Port 9 Plasma Arc 10 Slag Bath 11 Partition Plate 12 Temperature Measuring Point A to H Cooling Zone Q1 to Q8 Cooling water

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location F27B 3/24 F27B 3/24 (72) Inventor Yoshiaki Shimizu 1-3 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo No. 18 Kobe Steel, Ltd. Kobe Head Office

Claims (2)

[Claims] 1. A structure for cooling a furnace body of a plasma melting furnace by providing a cooling water zone on the outer periphery of a furnace body of a plasma melting furnace of refractory structure and circulating cooling water in the cooling water zone,
The cooling water zone is divided along the peripheral direction of the furnace body, and a means for controlling the cooling capacity of the cooling water flowing through each divided chamber according to the ambient temperature in the peripheral direction in the furnace is provided. Cooling structure for plasma melting furnace. 2. The furnace body cooling structure for a plasma melting furnace according to claim 1, wherein the cooling water zone is divided at positions having a central angle of ± 30 ° in the circumferential direction around at least the outlet.