Tempering furnace with both high-temperature tempering operation and low-temperature tempering operation

Abstract

The utility model relates to a tempering furnace with both high-temperature tempering operation and low-temperature tempering operation, which comprises a furnace body, a closed furnace door, an air inlet, a smoke outlet, a heating element, a high-temperature fan, a compressed air supply mechanism and an oil smoke forced discharge mechanism, the lower part and the upper part of the furnace body are respectively provided with an air inlet, a compressed air inlet, a smoke outlet and an oil smoke forced discharge outlet which are communicated with the hearth, the heating element and the high-temperature fan are arranged at the upper part of the furnace body and are positioned in the hearth, and the compressed air supply mechanism and the oil smoke forced discharge mechanism are respectively arranged at the compressed air inlet and the oil smoke forced discharge outlet; compressed air is input into the hearth, and oil smoke in the hearth is extracted and discharged step by step or at the same time. Therefore, corrosion of a heat preservation layer structure or short circuit of a heating element caused by oil stains accumulated in the hearth can be effectively prevented in high-temperature and low-temperature tempering operation of a workpiece, and the risk of detonation or explosion in the hearth can be effectively prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of workpiece heat treatment, in particular to a tempering furnace capable of both high-temperature and low-temperature tempering operations. Background Art

[0002] In the field of workpiece heat treatment technology, the diversification of production line products has become a development trend. In the production process of the multi-purpose furnace quenching production line, workpieces with different characteristics need to be produced according to product requirements, and the tempering process is an important process link to make the workpieces have different characteristics. At present, more and more users hope to use the same multi-purpose furnace quenching production line to perform both high-temperature tempering and low-temperature tempering operations on the workpieces. However, there is no tempering furnace body capable of high and low temperature tempering operations on the market. Moreover, since the process temperature of low-temperature tempering is much lower than that of high-temperature tempering, the low-temperature tempering operation will cause the impurities such as residual oil stains on the surface of the workpiece to produce a large amount of oil smoke. If the high-temperature tempering furnace is used to reduce the power of the heating element to perform the low-temperature tempering operation of the workpiece, the large amount of oil smoke generated will not be discharged from the furnace body in time, which will cause the oil stains in the tempering furnace to increase sharply, causing the erosion of the insulation layer structure, and will also cause the heating element to short-circuit. Long-term operation may even cause the risk of deflagration or explosion in the tempering furnace. Therefore, in order to meet the production needs of workpieces with different characteristics, users often have to purchase not only high-temperature tempering furnaces but also low-temperature tempering furnaces in the production line, which leads to higher operating costs, increased production line floor space, and reduced equipment utilization.

[0003] Therefore, how to provide a multi-purpose tempering furnace that can perform both high-temperature tempering and low-temperature tempering operations on workpieces has become one of the important technical problems that need to be solved urgently in the field of workpiece heat treatment technology. Utility Model Content

[0004] The technical problem to be solved by this technical solution is how to provide a multi-purpose tempering furnace which can perform both high-temperature tempering operation and low-temperature tempering operation on the workpiece.

[0005] In order to solve the above technical problems, the present technical scheme provides a tempering furnace with both high-temperature and low-temperature tempering operations, which includes: a furnace body, a closed furnace door, an air inlet, a smoke outlet, a plurality of heating elements, a high-temperature fan, a compressed air supply mechanism and an oil fume forced exhaust mechanism; wherein the furnace body has a furnace chamber inside, a workpiece inlet and outlet communicating with the furnace chamber is opened on one side of the furnace body, the workpiece inlet and outlet are equipped with a closed furnace door, the air inlet and the smoke outlet are respectively arranged at the lower part and the upper part of the furnace body and communicate with the furnace chamber, the plurality of heating elements are vertically and evenly arranged in the furnace chamber and The inner side surface of the side wall of the adjacent furnace body, and the upper end of the heating element is fixedly arranged on the upper part of the furnace body, the high-temperature fan is installed on the upper part of the furnace body and the blades of the high-temperature fan are located in the upper part of the furnace chamber, and the lower and upper parts of the furnace body are respectively provided with a compressed air inlet and a forced fume exhaust port communicated with the furnace chamber, and the compressed air supply mechanism and the forced fume exhaust mechanism are respectively installed at the compressed air inlet and the forced fume exhaust port; during operation, the compressed air supply mechanism can input compressed air into the furnace chamber, and the forced fume exhaust mechanism can draw out and discharge the fume in the furnace chamber. Accordingly, when the tempering furnace using the present technical solution is performing high-temperature tempering of the workpiece, the compressed air supply mechanism can be opened to input compressed air into the furnace when the temperature is relatively low in the early stage of heating, so that the pressure in the furnace is increased and the oil smoke generated by the incomplete combustion of oil stains and impurities on the workpiece surface due to low temperature is passively discharged from the smoke exhaust port, and during this period, the forced oil smoke discharge mechanism can also be opened at any time to assist in the discharge of oil smoke and ensure that no oil smoke remains in the furnace, and when the temperature in the furnace reaches a high temperature, the compressed air supply mechanism is closed to allow the oil stains and impurities remaining on the surface of the workpiece to be fully burned at high temperature and directly discharged through the smoke exhaust port; when the tempering furnace is used to perform low-temperature tempering of the workpiece, the compressed air supply mechanism is opened to input compressed air into the furnace, so that the pressure in the furnace is increased and the oil smoke generated by the incomplete combustion of oil stains and impurities on the workpiece surface due to low temperature is passively discharged from the smoke exhaust port, and the forced oil smoke discharge mechanism can be opened at any time to assist in the discharge of oil smoke and ensure that no oil smoke remains in the furnace. The tempering furnace of this technical solution can effectively discharge the oil smoke generated in the early stage of the high-temperature tempering process due to the temperature rising from low to high, as well as the oil smoke generated in the low-temperature tempering process, so as to prevent the accumulation of oil stains in the furnace from causing erosion of the insulation layer structure or short circuit of the heating element, and can effectively prevent the risk of deflagration or explosion in the furnace. In addition, the production line only needs one tempering furnace device to implement high and low temperature tempering operations on the workpiece, thereby effectively reducing the operating cost, saving the floor space of the production line, and improving the utilization rate of the equipment.

[0006] As another implementation of the technical solution, the compressed air supply mechanism may include: a compressed air supply source and a compressed air input pipe, wherein the compressed air supply source is arranged outside the furnace body, one end of the compressed air input pipe is connected to the compressed air inlet, and the other end of the compressed air input pipe is connected to the compressed air supply source, and a control valve is arranged on the compressed air input pipe. Accordingly, compressed air can be provided to the furnace through the compressed air supply source.

[0007] As another implementation of the present technical solution, the compressed air supply source may be a compressed air pump, or a compressed air main pipeline in a production line.

[0008] As another implementation of the technical solution, the oil fume forced exhaust mechanism may include: a centrifugal fan, an air supply pipe, a trumpet-shaped exhaust pipe, a three-way pipe, an oil fume exhaust pipe and an electric butterfly valve, wherein the oil fume forced exhaust port is opened at a position on the upper part of the furnace body away from the closed furnace door, the centrifugal fan is arranged outside the furnace body, one end of the air supply pipe is connected and communicated with the air outlet end of the centrifugal fan, the other end of the air supply pipe and the contracted end of the trumpet-shaped exhaust pipe are respectively connected and communicated with two opposite ports of the three-way pipe, one end of the oil fume exhaust pipe is connected and communicated with the oil fume forced exhaust port, the other end of the oil fume exhaust pipe is connected and communicated with the middle port of the three-way pipe, and the electric butterfly valve is arranged on the oil fume exhaust pipe. Accordingly, air can be quickly input into the three-way pipe through the operation of the centrifugal fan, and when discharged from the expanded end of the trumpet-shaped exhaust pipe, a Bernoulli negative pressure effect is formed inside the three-way pipe to generate negative pressure, thereby forcing the oil fume in the furnace to be sucked into the three-way pipe through the oil fume exhaust pipe and discharged through the expanded end of the trumpet-shaped exhaust pipe. Compared with using fans and other devices to directly extract oil fumes, using the Bernoulli negative pressure principle to extract oil fumes can effectively prevent the pollution and loss of the drive device by oil fumes.

[0009] As another implementation of the technical solution, the other end of the air delivery pipe is in a constricted shape, and the constricted end is inserted into the port of the three-way pipe and is located at the middle port, so that a better Bernoulli negative pressure effect can be formed in the three-way pipe.

[0010] As another implementation of the technical solution, the oil fume forced exhaust mechanism may also include: a pressure gauge and / or a thermometer, which is arranged on the oil fume exhaust pipe between the oil fume forced exhaust port and the electric butterfly valve. In this way, the pressure and / or temperature in the furnace can be monitored to control the tempering process.

[0011] As another implementation of the technical solution, the tempering furnace may further include: a central control unit, which is electrically connected to the opening and closing motor of the closed furnace door, the gas supply device of the air inlet, the heating element, the high-temperature fan, the centrifugal fan, the control valve, the electric butterfly valve, the pressure gauge and / or the thermometer. In this way, the degree of automatic operation of the tempering furnace can be effectively improved and the investment in labor costs can be reduced.

[0012] As another implementation of the technical solution, the tempering furnace may further include: an oil receiving pan, which is arranged at the bottom of the furnace, so as to receive liquefied grease that cannot be volatilized during the low-temperature tempering operation, so as to prevent oil stains from contaminating the refractory structure at the bottom of the furnace.

[0013] As another implementation of the technical solution, the tempering furnace may also include: an oil drain pipe, an oil drain port communicating with the furnace may be provided at the lower part of the furnace body, an oil outlet hole may be provided at the bottom of the oil receiving bottom plate, one end of the oil drain pipe is connected to the oil outlet hole, and the other end of the oil drain pipe is connected to the oil drain port. In this way, the oil stains collected by the oil receiving bottom plate can be discharged through the oil drain pipe. In addition, a valve may be provided at the oil drain port to control the timing of discharging the oil stains.

[0014] As another implementation of the technical solution, a high-temperature heat protection coating can be sprayed on the furnace wall insulation layer in the furnace, thereby preventing the oil smoke from penetrating into the insulation layer structure in the furnace during low-temperature tempering and shortening the service life of the furnace lining. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a cross-sectional view of a tempering furnace of the utility model that has both high-temperature and low-temperature tempering operations;

[0016] Figure 2 It is a partial enlarged view of the oil fume forced emission mechanism in the utility model.

[0017] Explanation of symbols in the accompanying drawings: 10 tempering furnace with both high-temperature and low-temperature tempering operations; 1 furnace body; 11 furnace chamber; 12 workpiece inlet and outlet; 13 compressed air inlet; 14 oil fume forced exhaust port; 15 exhaust port; 2 closed furnace door; 3 heating element; 4 high-temperature fan; 51 compressed air input pipe; 52 control valve; 61 air supply pipe; 611 end; 62 trumpet-shaped exhaust pipe; 621 contracted end; 63 three-way pipe; 64 oil fume exhaust pipe; 65 electric butterfly valve; 7 centrifugal fan. DETAILED DESCRIPTION

[0018] The detailed description and technical contents of the present invention are described below with reference to the accompanying drawings. However, the accompanying drawings are only provided for reference and description and are not intended to limit the present invention.

[0019] In the context of this specification, any two or more embodiments of the present invention may be arbitrarily combined, and the technical solution thus formed belongs to part of the original disclosure of this specification and also falls within the protection scope of the present invention.

[0020] like Figure 1The figure shows a schematic diagram of a specific embodiment of a tempering furnace with both high-temperature and low-temperature tempering operations of the utility model. The tempering furnace 10 with both high-temperature and low-temperature tempering operations (hereinafter referred to as the tempering furnace 10) includes a furnace body 1, a closed furnace door 2, an air inlet (not shown in the figure), a smoke outlet 15, a plurality of heating elements 3, a high-temperature fan 4, a compressed air supply mechanism and a fume forced exhaust mechanism. Among them, the furnace body 1 has a furnace 11 inside, and a workpiece inlet and outlet 12 communicating with the furnace 11 is opened on one side of the furnace body 1, and a closed furnace door 2 is installed at the workpiece inlet and outlet 12. The air inlet and the smoke outlet 15 are respectively arranged at the lower and upper parts of the furnace body 1 and communicate with the furnace 11. The air inlet is usually connected to a gas supply device to provide a process atmosphere such as air or nitrogen to the furnace 11 according to the tempering process steps. The smoke outlet 15 is usually directly connected to the external environment and a counterweight cover (not shown in the figure) is provided at the port, but it can also be connected to an exhaust gas treatment device, which is not limited by the utility model. The plurality of heating elements 3 are vertically and evenly arranged in the furnace 11 and adjacent to the inner side of the side wall of the furnace body 1, and the upper end of the heating element 3 is fixedly arranged on the upper part of the furnace body 1, and the heating power of the heating element 3 can be controlled according to the requirements of the tempering process. The high-temperature fan 4 is installed on the upper part of the furnace body 1 and the blades of the high-temperature fan 4 are located at the upper part of the furnace 11. The above-mentioned component installation structure of the tempering furnace 10 is a common structure of the existing tempering furnace type. Therefore, in order to save space, the specific structure and function of the existing tempering furnace type components are no longer described. The special feature of the tempering furnace 10 of the utility model is that a compressed air inlet 13 and a fume forced exhaust port 14 communicating with the furnace 11 are respectively opened at the lower part and the upper part of the furnace body 1, and the compressed air supply mechanism and the fume forced exhaust mechanism are respectively installed at the compressed air inlet 13 and the fume forced exhaust port 14. When the tempering furnace is in operation, the compressed air supply mechanism can input compressed air into the furnace 11, and the oil fume forced exhaust mechanism can extract and discharge the oil fume generated in the furnace 11. In more detail, when the tempering furnace 10 of the utility model is used to implement the high-temperature tempering operation of the workpiece, the compressed air supply mechanism can be opened to input compressed air into the furnace 11 when the temperature is low in the early stage of heating, so that the pressure in the furnace 11 is increased and the oil fume generated by the incomplete combustion of oil stains and impurities on the surface of the workpiece due to low temperature is passively discharged from the exhaust port 15, and during this period, the oil fume forced exhaust mechanism can also be opened at any time to assist in the exhaust of oil fume and ensure that there is no oil fume in the furnace 11, and when the temperature in the furnace 11 reaches a high temperature, the compressed air supply mechanism is closed, so that the oil stains and impurities remaining on the surface of the workpiece are fully burned at high temperature and directly discharged through the exhaust port 15. During the low-temperature tempering operation of the workpiece using the tempering furnace, the compressed air supply mechanism is turned on to input compressed air into the furnace 11, so that the pressure in the furnace 11 increases and the oil smoke generated by the incomplete combustion of oil stains and impurities on the surface of the workpiece due to low temperature is passively discharged from the exhaust port 15, and the forced fume discharge mechanism can be turned on at any time to assist in the fume discharge to ensure that no fume remains in the furnace 11.

[0021] Specifically, the compressed air supply mechanism may include a compressed air supply source (not shown) and a compressed air input pipe 51, wherein the compressed air supply source is arranged outside the furnace body 1, one end of the compressed air input pipe 51 is connected to the compressed air inlet 13, and the other end of the compressed air input pipe 51 is connected to the compressed air supply source, and a control valve 52 may be arranged on the compressed air input pipe 51 to control the opening and closing of the compressed air input pipe 51, and the compressed air supply source may provide compressed air to the furnace 11. The compressed air supply source may be a separate compressed air pump or a compressed air main pipeline in the production line.

[0022] The oil fume forced exhaust mechanism may include a centrifugal fan 7, an air supply pipe 61, a trumpet-shaped exhaust pipe 62, a three-way pipe 63, an oil fume exhaust pipe 64 and an electric butterfly valve 65, wherein the oil fume forced exhaust port 14 is opened at a position on the upper part of the furnace body 1 away from the closed furnace door 2, the centrifugal fan 7 is arranged outside the furnace body 1, one end of the air supply pipe 61 is connected to the air outlet end of the centrifugal fan 7, the other end of the air supply pipe 61 and the contracted end 621 of the trumpet-shaped exhaust pipe 62 are respectively connected to the two opposite ports of the three-way pipe 63, and one end of the oil fume exhaust pipe 64 is connected to the oil fume forced exhaust port 14. The discharge port 14 is connected and communicated, and the other end of the oil fume exhaust pipe 64 is connected and communicated with the middle port of the three-way pipe 63. The electric butterfly valve 65 is arranged on the oil fume exhaust pipe 64. The electric butterfly valve 65 is a high temperature resistant electric butterfly valve. The air can be quickly input into the three-way pipe 63 through the operation of the centrifugal fan 7, and when discharged from the flared end of the trumpet-shaped exhaust pipe 62, a Bernoulli negative pressure effect is formed inside the three-way pipe 63 to generate negative pressure, thereby forcing the oil fume in the furnace 11 to be sucked into the three-way pipe 63 through the oil fume exhaust pipe 64 and discharged through the flared end of the trumpet-shaped exhaust pipe 62. Compared with using a fan or other device to directly extract the oil fume, the use of the Bernoulli negative pressure principle to extract the oil fume can effectively prevent the pollution and loss of the drive device by the oil fume. In addition, combined with Figure 2 As shown, in order to form a better Bernoulli negative pressure effect in the three-way pipe 63, the end 611 of the other end of the air supply pipe 61 can be set to be a tapered shape, and the tapered end 611 is inserted into the port of the three-way pipe 63 and is located at the middle port.

[0023] In the utility model, the forced fume exhaust mechanism may also include a pressure gauge and / or a thermometer (not shown in the figure). The pressure gauge and / or the thermometer are arranged on the fume exhaust pipe between the forced fume exhaust port and the electric butterfly valve to monitor the pressure and / or temperature in the furnace to facilitate the control of the tempering process.

[0024] As another embodiment of the present invention, the tempering furnace may also include a central control unit (not shown in the figure), which may be a control panel with command buttons, or an automatic control unit composed of a programmable logic control circuit (PLC), or composed of a centralized control circuit, a centralized control system or a host computer, or a control system connected to the entire production line, etc. The present invention does not limit the mode of the central control unit. The central control unit is electrically connected to the opening and closing motor of the closed furnace door, the gas supply device of the air inlet, the heating element, the high-temperature fan, the centrifugal fan, the control valve, the electric butterfly valve, the pressure gauge and / or the thermometer, etc., to control the operation of the above-mentioned valve body and / or device according to the monitors such as the pressure gauge and / or the thermometer or the control instructions, so as to realize automatic operation and save the investment of labor costs. At present, most of the existing workpiece heat treatment production lines have achieved automated control. In view of the fact that the central control unit currently used controls the operating status of each mechanism or component according to input or written instructions, which is a very widely used and common control method in the field of automated control, that is, the existing control technology, therefore, the operation process of the central control unit used in the utility model to control the above-mentioned components will not be described in detail.

[0025] As another embodiment of the present invention, the tempering furnace may also include an oil receiving pan (not shown in the figure), which is arranged at the bottom of the furnace, and can receive liquefied oils and fats that cannot be volatilized during the low-temperature tempering operation to prevent the oil stains from contaminating the refractory structure at the bottom of the furnace. In addition, an oil drain pipe (not shown in the figure) may be added between the oil receiving pan and the furnace body, specifically, an oil drain port (not shown in the figure) connected to the furnace is provided at the lower part of the furnace body, an oil outlet hole (not shown in the figure) is provided at the bottom of the oil receiving pan, one end of the oil drain pipe is connected to the oil outlet hole, and the other end of the oil drain pipe is connected to the oil outlet, so that the oil stains collected by the oil receiving pan can be discharged through the oil drain pipe. In addition, a valve (not shown in the figure) may be provided at the oil outlet to control the discharge timing of the oil stains.

[0026] The tempering furnace of the utility model can also spray high-temperature heat protection coating on the furnace wall insulation layer in the furnace chamber to prevent oil smoke from penetrating into the insulation layer structure in the furnace chamber during low-temperature tempering and shortening the service life of the furnace lining.

[0027] In summary, the tempering furnace of the utility model can effectively discharge the oil smoke generated in the early stage of the high-temperature tempering process due to the temperature rising from low to high, as well as the oil smoke generated in the low-temperature tempering process, thereby effectively preventing the accumulation of oil stains in the furnace from causing erosion of the insulation layer structure or short circuit of the heating element, and effectively preventing the risk of deflagration or explosion in the furnace. Moreover, the production line only needs one tempering furnace device to implement high and low temperature tempering operations on the workpiece, thereby effectively reducing operating costs, saving the floor space of the production line, and improving the utilization rate of the equipment.

[0028] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Other equivalent changes made using the patent concept of the present invention should all fall within the patent protection scope of the present invention.

Claims

1. A tempering furnace capable of both high temperature and low temperature tempering operations, comprising: A furnace body, a closed furnace door, an air inlet, a smoke outlet, a plurality of heating elements and a high-temperature fan, wherein the furnace body has a furnace chamber inside, a workpiece inlet and outlet communicating with the furnace chamber are opened on one side of the furnace body and the closed furnace door is installed at the workpiece inlet and outlet, the air inlet and the smoke outlet are respectively arranged at the lower part and the upper part of the furnace body and communicate with the furnace chamber, the plurality of heating elements are vertically and evenly arranged in the furnace chamber and adjacent to the inner side surface of the side wall of the furnace body, and the upper end of the heating element is fixedly arranged on the upper part of the furnace body, the high-temperature fan is installed at the The blades of the high-temperature fan are located at the upper part of the furnace body and the upper part of the furnace; it is characterized in that it also includes: a compressed air supply mechanism and an oil fume forced exhaust mechanism, the lower part and the upper part of the furnace body are respectively provided with a compressed air inlet and an oil fume forced exhaust port communicated with the furnace, the compressed air supply mechanism and the oil fume forced exhaust mechanism are respectively installed at the compressed air inlet and the oil fume forced exhaust port, the compressed air supply mechanism can input compressed air into the furnace, and the oil fume forced exhaust mechanism can extract and discharge the oil fume in the furnace.

2. The tempering furnace according to claim 1, characterized in that: The compressed air supply mechanism includes: a compressed air supply source and a compressed air input pipe, the compressed air supply source is arranged outside the furnace body, one end of the compressed air input pipe is connected to the compressed air inlet, the other end of the compressed air input pipe is connected to the compressed air supply source, and a control valve is arranged on the compressed air input pipe.

3. The tempering furnace according to claim 2, characterized in that: The compressed air supply source is a compressed air pump or a compressed air main pipeline in a production line.

4. The tempering furnace according to claim 1, characterized in that: The oil fume forced exhaust mechanism comprises: a centrifugal fan, an air supply pipe, a trumpet-shaped exhaust pipe, a three-way pipe, an oil fume exhaust pipe and an electric butterfly valve. The oil fume forced exhaust port is opened at a position on the upper part of the furnace body away from the closed furnace door. The centrifugal fan is arranged on the outside of the furnace body. One end of the air supply pipe is connected to the air outlet end of the centrifugal fan, and the other end of the air supply pipe and the contracted end of the trumpet-shaped exhaust pipe are respectively connected to the two opposite ports of the three-way pipe. One end of the oil fume exhaust pipe is connected to the oil fume forced exhaust port, and the other end of the oil fume exhaust pipe is connected to the middle port of the three-way pipe. The electric butterfly valve is arranged on the oil fume exhaust pipe.

5. The tempering furnace according to claim 4, characterized in that: The other end of the air supply pipe is in a constricted shape, and the constricted end is inserted into the port of the three-way pipe and is located at the position of the middle port.

6. The tempering furnace according to claim 5, characterized in that: The oil fume forced exhaust mechanism further comprises: a pressure gauge and / or a thermometer, and the pressure gauge and / or the thermometer are arranged on the oil fume exhaust pipe between the oil fume forced exhaust port and the electric butterfly valve.

7. The tempering furnace according to claim 6, characterized in that: Also includes: The central control unit is electrically connected to the opening and closing motor of the closed furnace door, the air supply device of the air inlet, the heating element, the high-temperature fan, the centrifugal fan, the control valve of the compressed air supply mechanism, the electric butterfly valve, the pressure gauge and / or the thermometer.

8. The tempering furnace according to claim 1, characterized in that: Also includes: An oil receiving pan is arranged at the bottom of the furnace.

9. The tempering furnace according to claim 8, characterized in that: Also includes: An oil drain pipe, an oil drain port communicating with the furnace is opened at the lower part of the furnace body, an oil outlet hole is opened at the bottom of the oil receiving chassis, one end of the oil drain pipe is connected to the oil outlet hole, and the other end of the oil drain pipe is connected to the oil drain port.

10. The tempering furnace according to claim 1, characterized in that: A high-temperature heat protection coating is sprayed on the insulation layer of the furnace wall in the furnace.

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