Electric furnace flue gas treatment device

Abstract

The utility model relates to an electric furnace flue gas treatment device which comprises a combustion chamber, the combustion chamber is directly communicated with a preheating mechanism, the combustion chamber is directly communicated with an electric furnace at the same time, a flow adjusting assembly is arranged at the communication position of the combustion chamber and the preheating mechanism, and a flow adjusting assembly is also arranged at the communication position of the combustion chamber and the electric furnace. A heat exchange assembly is further arranged in the combustion chamber. The cooling mechanism is communicated with the combustion chamber, at least two dry type quenching assemblies are arranged in the cooling mechanism, and each dry type quenching assembly is provided with a waste heat recovery structure; the dust removal mechanism is communicated with the dry type quenching assembly; and the steam-water system is connected with the combustion chamber and the cooling mechanism at the same time. The combustion chamber, the cooling mechanism, the dust removal mechanism and the steam-water system are matched with one another so as to stably purify smoke and absorb heat in the smoke.

Description

Technical Field

[0001] The utility model relates to the technical field of industrial furnace fume treatment, in particular to an electric furnace fume treatment device. Background Art

[0002] During the smelting process of electric furnace, a large amount of high-temperature flue gas is generated. When it enters the subsequent flue gas treatment equipment, the temperature is as high as 1200℃. The high-temperature flue gas carries metal particles and oxide particles generated during the metal heating process. The particles are small in size, high in temperature, and contain toxic substances such as dioxins. Dioxins are mainly produced by the elementary reactions in the metal preheating process, the combustion / pyrolysis of high-chlorine molecular compounds at 500-800℃, and the high-temperature flue gas at 300-500℃.

[0003] The method for treating the above-mentioned high-temperature flue gas in the prior art is mainly combustion + water cooling. After burning to eliminate toxic substances in the flue gas, water mist is sprayed to quickly cool the flue gas to <200°C within 2 to 3 seconds to avoid elementary reactions in the flue gas to produce dioxin-like substances. This method consumes a lot of water resources and produces a lot of water vapor. Water vapor increases the burden of subsequent treatment equipment and is also prone to cause the "smoke plume" phenomenon. The heat in the flue gas is not well utilized. In actual production, although the water cooling device is replaced with a rapid cooling waste heat recovery device to cool the high-temperature flue gas while recovering heat, the temperature and flow rate of the flue gas generated by the electric furnace fluctuate greatly, which has a greater impact on the rapid cooling waste heat recovery device, affecting the stability and life of the device. The fluctuations in the flue gas temperature and flow rate will also affect the combustion and rapid cooling effects, resulting in incomplete purification of dioxin-like substances. Utility Model Content

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the utility model is to provide an electric furnace fume treatment device to stably purify the fume and absorb the heat in the fume.

[0005] To achieve the above purpose, the technical solution of the utility model is as follows:

[0006] The electric furnace fume treatment device comprises a preheating mechanism and an electric furnace, wherein the preheating mechanism is connected to the electric furnace, and further comprises:

[0007] A combustion chamber, the combustion chamber is directly connected to the preheating mechanism, the combustion chamber is also directly connected to the electric furnace, a flow regulating component is provided at the connection between the combustion chamber and the preheating mechanism, the flow regulating component is also provided at the connection between the combustion chamber and the electric furnace, and a heat exchange component is also provided in the combustion chamber;

[0008] A cooling mechanism, the cooling mechanism being connected to the combustion chamber, the cooling mechanism being provided with at least two dry quenching components, and the dry quenching components being provided with a waste heat recovery structure;

[0009] A dust removal mechanism, the dust removal mechanism being connected to the dry quenching assembly;

[0010] A steam-water system is connected to the combustion chamber and the cooling mechanism at the same time.

[0011] Furthermore, a plurality of heat storage rods are arranged in the combustion chamber, and the plurality of heat storage rods are evenly and staggeredly arranged in the combustion chamber, and the length direction of the heat storage rods is perpendicular to the flow direction of the flue gas.

[0012] Furthermore, a plurality of air nozzles are arranged in the combustion chamber, and the air nozzles are aimed at the heat storage rod.

[0013] Furthermore, it also includes an ash discharge mechanism, which includes an ash discharge pipe and a compression fan connected to the ash discharge pipe, the ash discharge pipe is connected to the combustion chamber, and the ash discharge pipe is connected to the dust removal mechanism.

[0014] Furthermore, at least two of the dry quenching components are arranged in parallel, and the dry quenching components include a plurality of flue gas inner tubes, and the flue gas inner tubes are sleeved with heat exchange outer tubes.

[0015] Furthermore, the lower wall of the combustion chamber is recessed downward to form a conical first ash hopper, and the heat exchange assembly is arranged in the first ash hopper.

[0016] Furthermore, the dust removal mechanism includes at least two metal membrane filters, and a conical second ash hopper is connected below the dust removal mechanism.

[0017] Furthermore, the flow regulating assembly includes a first regulating valve disposed between the combustion chamber and the preheating mechanism, and a second regulating valve disposed between the combustion chamber and the electric furnace.

[0018] Compared with the prior art, the beneficial technical effects of the utility model are as follows:

[0019] (1) The electric furnace flue gas treatment device described in the utility model is provided with a combustion chamber connected to the preheating mechanism and the electric furnace at the same time, which can mix the flue gas flowing out of the preheating mechanism and the electric furnace in proportion, so that the temperature of the flue gas flowing into the combustion chamber is stable, and the temperature of the flue gas flowing into the cooling mechanism after full combustion is also more balanced; a heat exchange component is also provided in the combustion chamber to absorb the heat of the particulate dust generated and settled during combustion; at least two dry quenching components connected to the combustion chamber are matched, and the flue gas after combustion is divided and enters different dry quenching components, and is absorbed heat and cooled very quickly. The combustion chamber, cooling mechanism, dust removal mechanism and steam-water system cooperate with each other to stably purify the flue gas and absorb the heat in the flue gas.

[0020] (2) Furthermore, a heat storage rod is provided in the combustion chamber. The temperature of the flue gas after combustion fluctuates. When the flue gas after combustion flows through the heat storage rod at a relatively high temperature, the heat storage rod can absorb the stored heat to lower the temperature of the flue gas; when the flue gas after combustion flows through the heat storage rod at a relatively low temperature, the heat storage rod can release the stored heat to increase the temperature of the flue gas and reduce the temperature fluctuation of the flue gas flowing into the cooling mechanism.

[0021] (3) Furthermore, the dry quenching component includes a plurality of inner flue gas tubes, on which outer heat exchange tubes are sleeved, and a plurality of inner flue gas tubes are arranged to increase the heat exchange area. The cooling medium flows between the inner flue gas tubes and the outer heat exchange tubes. The large heat exchange area cooperates with the low-temperature cooling medium to quickly cool down the flue gas, and the heat of the flue gas is transferred to the cooling medium to complete the heat absorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the layout of an electric furnace fume treatment device provided in an embodiment of the utility model is shown.

[0023] Figure 2 The schematic diagram of the structure of the combustion chamber in the electric furnace fume treatment device provided by the embodiment of the utility model is shown.

[0024] Figure 3 The schematic diagram of the structure of the dust removal mechanism in the electric furnace fume treatment device provided by the embodiment of the utility model is shown.

[0025] Figure 4 The utility model shows an assembly diagram of an inner flue gas pipe and an outer heat exchange pipe in an electric furnace flue gas treatment device provided in an embodiment of the utility model.

[0026] Markings in the accompanying drawings:

[0027] 1. Preheating mechanism; 11. First flue gas duct; 12. First regulating valve; 2. Electric furnace; 21. Second flue gas duct; 22. Second regulating valve; 3. Combustion chamber; 31. Burner; 32. Heat storage rod; 33. Air nozzle; 34. First ash hopper; 35. Heat exchange component; 36. Membrane water-cooled wall; 4. Cooling mechanism; 41. Dry quenching component; 42. Flue gas inner pipe; 43. Depression; 44. Heat exchange outer pipe; 5. Steam-water system; 6. Dust removal mechanism; 61. Metal membrane filter; 62. Second ash hopper; 7. Ash discharge mechanism; 71. Compressor fan; 72. Air outlet; 73. Ash discharge duct; 8. Variable frequency fan; 9. Chimney. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the utility model clearer, the device proposed in the utility model is further described in detail below in combination with the accompanying drawings and specific implementation methods. According to the following description, the advantages and features of the utility model will be clearer. It should be noted that the accompanying drawings adopt a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the implementation method of the utility model. In order to make the purpose, features and advantages of the utility model more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structure, proportion, size, etc. illustrated by the accompanying drawings of this specification are only used to match the content disclosed in the specification, so that people familiar with this technology can understand and read, and are not used to limit the limiting conditions for the implementation of the utility model, so it has no technical substantive significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effect that the utility model can produce and the purpose that can be achieved, should still fall within the scope of the technical content disclosed by the utility model.

[0029] In the description of the present invention, the orientations or positional relationships indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "axial", "radial", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0030] Figure 1 The schematic diagram of the layout of the electric furnace fume treatment device provided by the embodiment of the utility model is shown. Figure 2 The schematic diagram of the structure of the combustion chamber 3 in the electric furnace fume treatment device provided by the utility model is shown in FIG. Figure 1 and Figure 2The electric furnace flue gas treatment device includes a preheating mechanism 1 and an electric furnace 2, wherein the preheating mechanism 1 is connected to the electric furnace 2, and further includes a combustion chamber 3, wherein the combustion chamber 3 is directly connected to the preheating mechanism 1, and the combustion chamber 3 is also directly connected to the electric furnace 2, and a flow regulating component is provided at the connection between the combustion chamber 3 and the preheating mechanism 1, and a flow regulating component is also provided at the connection between the combustion chamber 3 and the electric furnace 2, and a heat exchange component 35 is also provided in the combustion chamber 3. A cooling mechanism 4, wherein the cooling mechanism 4 is connected to the combustion chamber 3, and at least two dry quenching components 41 are provided in the cooling mechanism 4, and the dry quenching components 41 are provided with a waste heat recovery structure; a dust removal mechanism 6, wherein the dust removal mechanism 6 is connected to all the dry quenching components 41. A steam-water system 5, wherein the steam-water system 5 is connected to the combustion chamber 3 and the cooling mechanism 4 at the same time. Specifically, the combustion chamber 3 is connected to the preheating mechanism 1 through the first flue gas duct 11, and the combustion chamber 3 is connected to the electric furnace 2 through the second flue gas duct 21. A burner 31 is provided in the combustion chamber 3 to burn the flue gas. The burner 31 can be an oxygen auxiliary burner 31 to improve the combustion efficiency. The dust removal mechanism 6 is connected to a chimney 9, and a variable frequency fan 8 is provided between the two. The variable frequency fan 8 has better energy consumption, noise and vibration performance. The flue gas after dust removal is driven by the variable frequency fan 8 and discharged along the chimney 9. At least two dry quenching components 41 are connected in parallel to the smoke outlet of the combustion chamber 3, and the flue gas after combustion is diverted into different dry quenching components 41. Multiple dry quenching components 41 cooperate with each other to ensure the cooling speed. The flue gas temperature in the preheating mechanism 1 is lower than the temperature of the flue gas in the electric furnace 2. Through the flow regulating component, the flue gas retained in the preheating mechanism 1 and the electric furnace 2 is mixed in the combustion chamber 3 in proportion, so that the temperature and flow of the mixed flue gas in the combustion chamber 3 can be adjusted to be stable, and the thermal shock impact of the mixed flue gas on the cooling mechanism 4 is reduced. At the same time, the stable temperature and flow are also convenient for flue gas combustion and purification.

[0031] The specific structure of the combustion chamber 3 is described below:

[0032] Please refer to Figure 2 , a plurality of heat storage rods 32 are arranged in the combustion chamber 3, and the plurality of heat storage rods 32 are evenly staggered in the combustion chamber 3, and the length direction of the heat storage rods 32 is perpendicular to the flow direction of the flue gas. Specifically, the heat storage rods 32 can be high-temperature composite phase-change heat storage rods 32, and the plurality of heat storage rods 32 can be staggered in a plum blossom shape, so that the flue gas can fully contact the heat storage rods 32, so that the heat storage rods 32 and the flue gas can exchange heat to balance the temperature of the flue gas, reduce the impact of flue gas temperature fluctuations on the cooling mechanism 4, and thus improve the rapid cooling and purification effects. The heat storage rods 32 are preferably arranged above the first ash hopper 34, and the flow path of the flue gas is disrupted when the flue gas flows through the heat storage rods 32, thereby extending the time that the flue gas stays above the first ash hopper 34, allowing more particles to settle in the first ash hopper 34, and improving the combustion purification effect.

[0033] Please refer to Figure 2A plurality of air nozzles 33 are also provided in the combustion chamber 3, and the air nozzles 33 are aimed at the heat storage rod 32. Specifically, the air nozzles 33 are connected to an air source (not shown in the figure). The air source outputs an air flow, which blows over the surface of the heat storage rod 32 along the air nozzles 33 to clean and remove the dust particles on the surface of the heat storage rod 32. The heat storage rod 32 can be cleaned without opening the heat storage chamber, and the cleaning is simple and quick.

[0034] The specific structure of the ash discharge mechanism 7 is described below:

[0035] Figure 3 The schematic diagram of the structure of the dust removal mechanism 6 in the electric furnace fume treatment device provided by the embodiment of the utility model is shown. Figure 2 and Figure 3 , and also includes an ash discharge mechanism 7, which includes an ash discharge pipe 73 and a compression fan 71 connected to the ash discharge pipe 73, the ash discharge pipe 73 is connected to the combustion chamber 3, and the ash discharge pipe 73 is connected to the dust removal mechanism 6. Specifically, the compression fan 71 is also provided with an air outlet 72, and multiple air outlets 72 point to the first ash hopper 34 and the second ash hopper 62. The air outlet 72 blows air to clean the first ash hopper 34 and the second ash hopper 62, and blows the dust particles in the first ash hopper 34 and the second ash hopper 62 into the ash discharge pipe 73. The heat exchange component 35 provided in the first ash hopper 34 can also clean the dust particles on the surface through the air outlet 72. The operator can remotely control the start and stop of the air outlet 72, which is convenient for cleaning and maintaining the first ash hopper 34, the second ash hopper 62 and the heat exchange component 35, preventing the first ash hopper 34 and the second ash hopper 62 from being blocked, and improving the heat exchange efficiency of the heat exchange component 35. The heat exchange component 35 can be of fin type. Particles and dust are easily accumulated on the surface of the fin type heat exchange component 35, but its heat exchange area is larger and the heat absorption effect is better. Through the air outlet 72, the particles and dust on the surface of the heat exchange component 35 can be cleaned with simple operations to ensure its heat exchange effect.

[0036] Please refer to Figure 2 The lower wall of the combustion chamber 3 is recessed 43 downward to form at least one conical first ash hopper 34, and the heat exchange component 35 is arranged in the first ash hopper 34. Specifically, the particles in the flue gas in the combustion chamber 3 settle in the first ash hopper 34 under the action of gravity, slide along the side wall of the first ash hopper 34 to the ash discharge pipe 73 to be cleaned, and contact the heat exchange component 35 in the first ash hopper 34. The heat of the particles is transferred to the heat exchange component 35, and the heat of the particles can be absorbed and utilized while cooling the particles. The side wall of the first ash hopper 34 can be a membrane water-cooled wall 36, which further increases the heat exchange area of ​​the particles and absorbs the heat of the particles.

[0037] Please refer to Figure 3The dust removal mechanism 6 includes at least two metal membrane filters 61, and a conical second ash hopper 62 is also connected below the dust removal mechanism 6. Specifically, the metal membrane component of the metal membrane filter 61 can be oxides such as TiO2, V2O5, and WO3. While physically filtering the flue gas, the dioxins in the flue gas can be decomposed into substances such as OH2 and HCL to completely remove the dioxins in the flue gas. At least two metal membrane filters 61 are arranged in parallel, and the cooled flue gas passes through all the metal membrane filters 61 in turn to ensure that toxic substances such as dioxins in the flue gas are filtered. The particles generated by filtration and decomposition fall into the second ash hopper 62 under the action of gravity, enter the ash discharge pipe 73 along the second ash hopper 62 and are discharged, avoiding the accumulation of particulate dust in the dust removal mechanism 6.

[0038] The specific structures of the dry quenching assembly 41 and the flow regulating assembly are described below:

[0039] Figure 4 The assembly diagram of the inner flue gas pipe 42 and the outer heat exchange pipe 44 in the electric furnace flue gas treatment device provided by the embodiment of the utility model is shown. Please refer to Figure 1 and Figure 4 At least two dry quenching components 41 are arranged in parallel, and the dry quenching components 41 include multiple flue gas inner tubes 42, and the flue gas inner tubes 42 are sleeved with heat exchange outer tubes 44. Specifically, the dry quenching component 41 does not directly contact the flue gas through water, which saves water resources, avoids mixing water vapor into the flue gas to increase the equipment load, and also avoids the "smoke plume" phenomenon. There are multiple interference quenching components, and each dry quenching component 41 includes multiple flue gas inner tubes 42 to maximize the diversion of flue gas, increase the heat exchange area, increase the cooling rate of the flue gas, and minimize the dioxins produced by the elementary reaction of the flue gas at 250-450°C. The cooling medium flows between the flue gas inner tube 42 and the heat exchange outer tube 44 to absorb the heat of the flue gas in the flue gas inner tube 42. A plurality of depressions 43 are also provided on the tube body of the flue gas inner tube 42. The depressions 43 increase the heat exchange area of ​​the flue gas inner tube 42 and at the same time disrupt the flow paths of the flue gas and the cooling medium to form turbulence, thereby further improving the heat exchange effect.

[0040] Please refer to Figure 1 The flow regulating assembly includes a first regulating valve 12 disposed between the combustion chamber 3 and the preheating mechanism 1, and a second regulating valve 22 disposed between the combustion chamber 3 and the electric furnace 2. Specifically, the first regulating valve 12 is disposed on the first flue gas duct 11, and the flow of the first flue gas duct 11 can be controlled by adjusting the opening of the first regulating valve 12. The second regulating valve 22 is disposed on the second flue gas duct 21, and the flow of the second flue gas duct 21 can be controlled by adjusting the opening of the second regulating valve 22. By adjusting the first regulating valve 12 and the second regulating valve 22, the temperature and flow of the mixed gas flowing into the combustion chamber 3 can be controlled.

[0041] An electric furnace fume treatment method using the electric furnace fume treatment device described in the utility model comprises the following steps:

[0042] S10, mixing the flue gas from the preheating and smelting process in proportion; adjusting the first regulating valve 12 and the second regulating valve 22 so that the temperature and flow rate of the flue gas flowing into the combustion chamber 3 after mixing tend to be stable.

[0043] S20, burn the mixed flue gas for 2 to 3 seconds, and ensure that the temperature of the mixed flue gas is always ≥ 800°C before, during and after combustion; the flue gas flowing into the combustion chamber 3 is burned by the burner 31, and the flue gas after combustion flows through the heat storage rod 32, which absorbs the heat of the relatively high temperature flue gas and releases it when the temperature of the flue gas is relatively low, ensuring that the temperature of the flue gas is always ≥ 800°C.

[0044] S30, the flue gas after combustion is cooled extremely fast at a speed greater than 300°C / s to a temperature of ≤250°C, and the heat dissipated is collected and utilized while cooling; the flue gas after combustion in the combustion chamber 3 flows into the cooling mechanism 4, and the flue gas is diverted and enters different dry quenching components 41, and then diverted again into different flue gas inner tubes 42 to be cooled by the cooling medium.

[0045] S40, filtering the cooled flue gas; the cooled flue gas is filtered through at least two metal membrane filters 61 in sequence, and dioxins in the flue gas are also decomposed by oxides such as TiO2, V2O5, WO3, etc. in the metal membrane.

[0046] S50, discharging the filtered flue gas, which is discharged along the chimney 9 under the drive of the variable frequency fan 8.

[0047] The following steps are also included:

[0048] S21, collecting the heat of the particles settled during the combustion of the flue gas. When the flue gas flows in the combustion chamber 3, the particles in the flue gas and the particles generated by the combustion settle in the first ash hopper 34 at the bottom of the combustion chamber 3, and the heat of the settled particles is taken away and utilized by the membrane water-cooled side wall of the first ash hopper 34 and the finned heat exchange component 35 provided in the first ash hopper 34.

[0049] It can be seen that the above-mentioned electric furnace flue gas treatment device eliminates harmful substances in the flue gas through combustion and filtration, and controls the combustion temperature of the flue gas to be ≥800°C, and at the same time quickly cools the flue gas after combustion at a speed greater than 300°C / s to a temperature of ≤250°C, thereby avoiding the combustion / pyrolysis of high-chlorine molecular compounds in the flue gas at 500-800°C, and the elementary reaction of the flue gas at 300-500°C to re-produce dioxin-like substances, so as to completely purify the flue gas of the electric furnace 2. In addition, a heat exchange component 35 is provided to repeatedly absorb and utilize the heat of the flue gas of the electric furnace 2.

[0050] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. An electric furnace flue gas treatment device, comprising a preheating mechanism and an electric furnace, wherein the preheating mechanism is connected to the electric furnace, and is characterized in that: Also includes, A combustion chamber, the combustion chamber is directly connected to the preheating mechanism, and the combustion chamber is also directly connected to the electric furnace. A flow regulating component is provided at the connection between the combustion chamber and the preheating mechanism, and the flow regulating component is also provided at the connection between the combustion chamber and the electric furnace. A heat exchange component is also provided in the combustion chamber; A cooling mechanism, the cooling mechanism being connected to the combustion chamber, the cooling mechanism being provided with at least two dry quenching assemblies, the dry quenching assemblies being provided with a waste heat recovery structure; a dust removal mechanism, the dust removal mechanism being connected to the dry quenching assembly; A steam-water system is connected to the combustion chamber and the cooling mechanism at the same time.

2. The electric furnace flue gas treatment device according to claim 1, characterized in that: A plurality of heat storage rods are arranged in the combustion chamber, and the plurality of heat storage rods are evenly staggered in the combustion chamber, and the length direction of the heat storage rods is perpendicular to the flow direction of the flue gas.

3. The electric furnace flue gas treatment device according to claim 2, characterized in that: A plurality of air nozzles are further provided in the combustion chamber, and the air nozzles are aimed at the heat storage rod.

4. The electric furnace flue gas treatment device according to claim 1, characterized in that: It also includes an ash discharge mechanism, which includes an ash discharge pipe and a compression fan connected to the ash discharge pipe. The ash discharge pipe is connected to the combustion chamber and the ash discharge pipe is connected to the dust removal mechanism.

5. The electric furnace flue gas treatment device according to claim 1, characterized in that: At least two of the dry quenching components are arranged in parallel. The dry quenching components include a plurality of flue gas inner tubes, and the flue gas inner tubes are sleeved with heat exchange outer tubes.

6. The electric furnace flue gas treatment device according to claim 1, characterized in that: The lower wall of the combustion chamber is recessed downward to form a conical first ash hopper, and the heat exchange assembly is arranged in the first ash hopper.

7. The electric furnace flue gas treatment device according to claim 1, characterized in that: The dust removal mechanism includes at least two metal membrane filters, and a conical second ash hopper is connected below the dust removal mechanism.

8. The electric furnace flue gas treatment device according to claim 1, characterized in that: The flow regulating assembly includes a first regulating valve arranged between the combustion chamber and the preheating mechanism, and a second regulating valve arranged between the combustion chamber and the electric furnace.

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