Large electric melting furnace for rock wool and rock wool raw material heating method

Abstract

The invention discloses a large electric melting furnace for rock wool and a rock wool raw material heating method. The electric melting furnace comprises a furnace bottom, a furnace shell bottom layer, a furnace shell middle part, a furnace shell upper part and a furnace cover which are sequentially connected from bottom to top; and the upper part of the furnace shell comprises an arc-shaped cooling wall, and air cooling or water cooling, furnace shell middle water cooling and furnace cover air cooling are adopted. The invention further comprises an adjustable electrode circle, a melting dead zone in the furnace is avoided, the electrode resistance is accurately controlled, the melt homogeneity is improved, the power distribution uniformity is improved, and the melt convection strength is improved. The melting quantity of the electric furnace is 10-30 tons per hour, the melt storage quantity is 100-300 tons, the melting temperature is 1600-2000 DEG C, and all waste materials entering the electric furnace can be fully melted and fully homogenized. The electric melting furnace is high in melting capacity, the problem that powder enters the furnace and crusts is avoided, and the variety and range of available industrial waste are effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of rock wool production, and in particular relates to a large electric melting furnace for rock wool and a rock wool raw material heating method. Background Art

[0002] The electric melting furnace is an arc resistance furnace used for continuous production of rock wool; the raw materials for melting in the electric furnace are basalt, dolomite, slag, waste slag from rock wool production, waste fiber, and a mixture of other available industrial waste particles or powders; the raw materials are proportioned through a distributor and added to the electric melting furnace for smelting, and the melting process is carried out in the electric melting furnace; the electric melting furnace uses electricity as a heat source, and the raw materials are heated to about 1600-2000℃ through three electrodes in the electric melting furnace. After high-temperature melting and homogenization, the raw materials form a melt with a temperature of 1450-1600℃; the melt is the main product, and the iron oxide contained in the raw materials undergoes a reduction reaction at high temperature to produce a very small amount of molten iron or other metals that precipitate to the bottom of the furnace as a by-product. The melt flows out from the melt outlet on the lower side of the electric melting furnace, flows to the centrifuge through various levels of water-cooled flow troughs, and enters the next fiber-forming process section.

[0003] The advantages of using electric furnaces in rock wool production are that no coke, no blast and no oxygen are required; no large pieces of raw materials are required, small pieces of raw materials or powders are easier to find and cheaper; electric furnaces are more flexible, easy to operate, stable in operation, and the flow and temperature fluctuations of the melt are small; the amount of flue gas is small, and the waste gas treatment system is relatively simple; electric furnaces can digest solid wastes such as waste slag and waste cotton generated by the rock wool production line; electric furnaces can digest industrial wastes such as fly ash and magnesium slag; the melting efficiency is high, the quality is stable, and it is suitable for making products with high acidity coefficients.

[0004] However, the current melting output of electric furnaces is limited, and when different materials are added, uneven heating is prone to occur in the electric furnace due to uneven materials without a stirring device, and the furnace temperature cannot be controlled; the electrode position in the fixed structure electric furnace is inconvenient to adjust, and a better heating effect cannot be formed in the polar center circle state. Summary of the invention

[0005] In order to solve the deficiencies of the prior art, the present invention proposes a large electric melting furnace for rock wool, which is a large electric melting furnace for rock wool with high output and high melting efficiency, and can digest and process industrial waste residues such as fly ash and magnesium slag. In order to achieve this effect, the technical solution provided by the present invention is as follows:

[0006] As one aspect of the present invention, there is provided a large electric melting furnace for rock wool, which comprises, from bottom to top, a furnace bottom, a furnace shell bottom, a furnace shell middle, a furnace shell upper part and a furnace cover connected in sequence;

[0007] One of the innovations of the present invention is that it provides a suitable cooling scheme. The furnace bottom is cooled by a plurality of independent furnace bottom air ducts to realize flexible control of the local temperature at different positions of the furnace bottom. The middle part of the furnace shell includes a cooling wall, and each layer of the cooling wall is divided into a plurality of independent blocks. Each cooling wall is an independent closed forced water cooling closed cycle structure, including a cooling wall inner plate, a cooling wall outer plate and a cooling wall side plate. The cooling wall inner plate, the cooling wall outer plate and the cooling wall side plate form a cavity, and a labyrinth water channel baffle is arranged inside the cavity to set the water cooling closed cycle into a labyrinth water channel form.

[0008] The upper and lower ends of the bottom layer of the furnace shell are respectively connected to the middle part of the furnace shell and the furnace bottom. The bottom layer of the furnace shell includes an annular steel plate. Furnace bottom refractory materials are arranged inside the annular steel plate and inside the cooling wall in the middle part of the furnace shell. Several thermocouples are installed on the furnace bottom refractory materials to monitor the temperature changes of the furnace bottom refractory materials.

[0009] Preferably, the cooling stave is an arc-shaped cooling stave. Each arc-shaped forced cooling stave is provided with an inspection hole, a cooling water inlet and outlet, a cleaning door flange, an exhaust hole, and a temperature detection hole, and is connected to the upper part of the furnace shell and the bottom part of the furnace shell through upper and lower flanges, respectively, and is connected to other cooling staves through side flanges. Triangular reinforcing ribs are provided at the connection between the inner plate of the cooling stave, the outer plate of the cooling stave, the upper and lower flanges, and the side flanges to enhance the connection strength. The upper part of the furnace shell includes an arc-shaped cooling stave, which is air-cooled or water-cooled.

[0010] In the embodiment of the present invention, the furnace cover comprises a plurality of independent furnace cover plates, adopts an air-cooling structure, and the flow channel is composed of a series of baffles, which form a maze with a constant cross-sectional area so that the wind speed passing through it is as constant as possible. This ensures the cooling of the equipment and its service life.

[0011] Furthermore, the furnace cover plate is divided into an inner ring plate with an electrode hole and an outer ring plate located outside the inner ring plate; a furnace cover discharge hole is set at the connection between adjacent furnace cover plates, a furnace cover exhaust gas outlet is set on one of the furnace cover plates, and a furnace cover liquid level measuring hole is set on the other furnace cover plate.

[0012] Furthermore, each furnace cover plate near the electrode is insulated from the three-phase electrodes by high temperature resistant insulating materials to ensure safety and avoid the formation of circular induced current due to electromagnetic induction. An expansion gap is left between adjacent furnace cover plates to allow differential expansion between the plates.

[0013] In an embodiment of the present invention, a melt outlet is further provided on a melt outlet base, the melt outlet base is a hollow water-cooled part connected to a cooling wall in the middle of the furnace shell, and a water-cooled back plate is provided on the back. In an embodiment of the present invention, the melt outlet is opened and closed by a melt control door.

[0014] In an embodiment of the present invention, a molten metal outlet is further provided on the middle side wall of the furnace shell, and a hole opening and plugging machine is provided on the molten metal outlet, and a melt outlet hole opening machine facing the melt outlet is also provided.

[0015] The middle side wall of the furnace shell is also provided with two emergency evacuation exits, which are respectively arranged on the side and bottom of the furnace shell.

[0016] A material discharge system is arranged above the furnace cover, including a kiln head storage bin, an electric screw conveyor, a weighing device, a flap valve, and a material discharge pipe which are connected in sequence. The material discharge pipe passes through the furnace cover, and a rotating material distribution device is arranged at the bottom.

[0017] It also includes an electrode system arranged on the furnace cover, including an electrode, an electrode lifting device, a pressing device, and a pressure ring of a holder. The bottom end of the electrode extends into the furnace, at a position slightly above the middle of the furnace shell; the electrode lifting device includes a hanging vertical cylinder and a pressing platform, one end of the pressing platform is connected to the hanging vertical cylinder, and the other end is connected to the pressing device. The electrode lifting device is used to change the depth of the electrode inserted into the charge, adjust the operating resistance, and make the power input into the furnace reach the rated requirements.

[0018] The innovation of the present invention also lies in that it also includes an adjustable pole center circle, the adjustable pole center circles are distributed in an equilateral triangle, the electrode is arranged on the adjustable pole center circle, and the three parts are respectively arranged on the three inner ring plates at the innermost end of the furnace cover, and the relative distance from the center of the furnace cover is adjusted by a top screw pull rod; in the embodiment of the present invention, a fixed plate facing the center of the furnace cover is arranged on the furnace cover, and waist-shaped electrode holes for the electrodes to pass through are arranged on the three inner ring plates at the innermost end of the furnace cover, and a pair of limit blocks are respectively arranged on both sides of the waist-shaped electrode holes, and the limit blocks serve as tracks to limit the trajectory of electrode movement.

[0019] The adjustable polar circle is provided with a polar circle air cooling cover, under which a polar circle refractory material is provided, and the air cooling cover is provided with a labyrinth air duct and a polar circle air inlet for air cooling. The air inlet volume can be adjusted. The choice of air cooling is to ensure cooling while avoiding the adverse effects of accidental water leakage in the traditional water-cooled furnace cover structure. The air outlet of the air cooling cover is arranged along the periphery of the electrode, and the gas is blown into the furnace body along the gap between the electrode and the electrode hole, forming a ring airflow that seals the flue gas and effectively cools the electrode hole.

[0020] Electrode seals are arranged at the adjustable pole center circle and the electrode contact position.

[0021] According to the different input materials, the pole center circle is adjusted to avoid the melting dead zone in the furnace, accurately control the electrode resistance, improve the melt homogenization, improve the uniformity of power distribution, and improve the intensity of melt convection. The pole center circle is adjusted to change the electrode resistance distribution according to the process requirements of electrode insertion depth, melt liquid level height, component formula, etc., so as to balance power, improve efficiency, and increase output.

[0022] As a second aspect of the present invention, a method for heating rock wool raw materials is provided, using the large electric melting furnace for rock wool provided by the present invention, comprising the following steps:

[0023] Step 1, pre-adding materials and turning on the electric furnace to increase the temperature;

[0024] Step 2, the electric furnace cover is ventilated through the air inlet and outlet; cooling water is introduced into the middle of the furnace shell; the furnace bottom is ventilated; and the thermocouple at the bottom of the furnace shell detects the temperature;

[0025] Step 3, adjusting the electrode insertion depth by the electrode lifting device, and adjusting the relative distance of the electrodes by the top wire pull rod of the adjustable pole center circle, so that the material in the furnace melts and the temperature reaches the predetermined temperature and is stable;

[0026] Step 4, the material is continuously circulated and supplied into the furnace shell by the feeding system. The material can be conventional material for rock wool production, including basalt, diabase, dolomite; the material can also be industrial waste; the material can also be a mixture of conventional material for rock wool production and industrial waste;

[0027] Step 5, the temperature is detected by the thermocouple, and the process parameters are adjusted by air cooling of the furnace cover and furnace bottom and water cooling structure in the middle of the furnace shell;

[0028] Step 6, adjusting the electrode insertion depth, controlling the input power, etc.;

[0029] Step 7, the melt is continuously discharged through the melt outlet;

[0030] Step 4, step 5, step 6 and step 7 are a closed loop.

[0031] During the production of an electric furnace, molten iron is discharged through the iron outlet at regular intervals.

[0032] The existing rock wool electric furnace has the following disadvantages:

[0033] 1. The melt output is no more than 8 tons / hour, and the melt reserve is no more than 80 tons; the existing rock wool electric melting furnace cannot solve the relationship between the furnace diameter, furnace height, electrode diameter, and polar center circle diameter; it cannot form the heating effect under the best state;

[0034] 2. The material distribution is uneven and unstable, and the furnace temperature cannot be well controlled;

[0035] 3. The existing rock wool electric furnaces all adopt the backward external spray cooling method, which has low cooling intensity and generally short service life of refractory materials; the control and automation levels of the existing rock wool electric furnaces are backward; the above reasons restrict the increase of its production.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The total amount of industrial waste used by the electric furnace accounts for 0-100% of all raw materials. The electric furnace has strong melting capacity, a melting capacity of 10-30 tons / hour, a large melt reserve (100-300 tons) and a high melting temperature (1600-2000℃), which can fully melt and homogenize all the waste entering the electric furnace. The strong melting capacity and huge melt reserve are achieved by relying on the furnace diameter of 6-12 meters, the furnace height of 3-6 meters, the electrode diameter of 450-850mm, the polar center circle diameter of 1.8-4.0 meters adjustable, the melting capacity of 10-30 tons / hour, and the power of 10-30MVA. It takes 2-15 hours for the waste to flow out from the melt outlet from the beginning of melting. After a long high-temperature process, various crystals in the waste have fully become a high-temperature liquid mixture of silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, iron oxide and titanium dioxide.

[0038] 2. The electric furnace can effectively utilize industrial waste and construction waste. The industrial waste includes but is not limited to fly ash, magnesium slag, blast furnace slag, blast furnace dry slag, construction waste (building bricks, concrete, rock wool, slag wool, glass wool, aluminum silicate, etc.), etc. After the waste and other raw materials are proportioned, as long as the average content of silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, iron oxide, titanium dioxide, etc. is within the range of rock wool or slag wool, for example, 30-55% silicon dioxide, 10-20% aluminum oxide, 15-30% calcium oxide, 5-20% magnesium oxide, 0-15% iron oxide, and 0-5% titanium dioxide.

[0039] 3. The industrial waste materials used in this electric furnace can be either granules or powders, as long as the particle size after crushing is less than or equal to 4cm. This electric furnace has a strong melting capacity, which can prevent the occurrence of powder crusting in the furnace, and effectively increase the types and range of industrial waste that can be used. The existing rock wool electric melting furnace has uneven power distribution and insufficient convection. The heat cannot be effectively transferred to the furnace, which easily forms dead corners and the heat cannot be fully utilized, resulting in some furnace materials not being able to heat up quickly, forming crusting. In addition, uneven loading can easily cause some furnace materials to exceed the designed height, making them difficult to heat and forming crusts.

[0040] 4. The temperature gradient changes near the electrodes of the large rock wool electric melting furnace, coupled with the physical and chemical changes near the electrodes during the high-temperature melting process, the decomposed gas expands and overflows to drive the convection of the melt, thereby driving the flow and tumbling of the melt. No stirring mechanism is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0042] Figure 1A schematic diagram of the overall structure of a large electric melting furnace for rock wool provided in Example 1 of the present invention;

[0043] Figure 2 Schematic diagram of the arc-shaped forced cooling wall structure in the middle of the furnace shell; wherein (a) is a schematic diagram of a single arc-shaped cooling wall from a side view, and (b) is a schematic diagram of a single arc-shaped cooling wall from a top view;

[0044] Figure 3 This is a schematic diagram of the furnace cover structure;

[0045] Figure 4 Schematic diagram of the melt outlet structure; (a) is a schematic diagram of the overall structure of the melt control door, and (b) is a detailed structure diagram of the water-cooled back plate;

[0046] Figure 5 This is a schematic diagram of the iron discharge port and emergency exit structure;

[0047] Figure 6 Schematic diagram of the material discharging system; wherein (a) is a schematic diagram of the overall structure of the material discharging system, and (b) is a schematic diagram of the structure of the rotating material discharging device;

[0048] Figure 7 It is a schematic diagram of the electrode column, seal, and adjustable polar center circle structure;

[0049] Figure 8 A logic diagram of the connection relationship between the components of a large-scale electric melting furnace for rock wool provided in Example 1 of the present invention;

[0050] Fig. 9 This is the structural diagram of the furnace bottom air duct.

[0051] Among them, 1-furnace bottom, 2-furnace shell bottom, 3-furnace shell middle, 4-furnace shell upper, 5-furnace cover, 6-melt outlet, 7-iron discharge outlet, 8-side emergency evacuation outlet, 9-feeding system, 10-electrode system, 11-adjustable pole center circle, 12-electrode seal;

[0052] 101-furnace bottom fan, 102-furnace bottom air duct, 103-furnace bottom foundation, 104-furnace bottom support;

[0053] 201-annular steel plate, 202-bottom flange of furnace shell, 203-reinforcement ribs, 204-bottom plate, 205-thermocouple;

[0054] 301- labyrinth waterway baffle, 302- inspection hole, 303- cooling wall outer plate, 304- cooling wall inner plate, 305- cooling water inlet and outlet, 306- cleaning door flange, 307- exhaust hole, 308- temperature detection hole, 309- arc cooling wall;

[0055] 401-air inlet and outlet on the upper part of the furnace shell, 402-monitoring hole on the upper part of the furnace shell, 403-monitoring equipment on the upper part of the furnace shell, 404-inspection hole on the upper part of the furnace shell, 405-inspection door on the upper part of the furnace shell;

[0056] 501-furnace cover air inlet and outlet, 502-electrode hole, 503-furnace cover feed hole, 504-furnace cover exhaust gas outlet, 505-furnace cover liquid level measuring hole, 506-insulating material, 507-expansion gap;

[0057] 601-melt outlet base, 602-refractory brick, 603-water cooling back plate, 604-melt control door, 605-melt door drive device, 606-melt outlet eye opening machine; 6201-melt circulation channel;

[0058] 701- water-cooled copper plate, 702- orifice brick, 703- eyelet opening and plugging machine, 704- refractory channel, 705- ladle;

[0059] 801-inner water-cooled copper block, 802-outer water-cooled copper block, 803-frame square box, 804-refractory brick;

[0060] 901-kiln head storage bin, 902-electric screw conveyor, 903-weighing device, 904-flap valve, 905-feeding pipe, 906-cooling fan, 907-rotating material distribution device; 9701-cone, 9702-propeller blades, 9703-driving power;

[0061] 1001-electrode, 1002-electrode lifting device, 1003-pressing device, 1004-holding pressure ring; 100201-hanging vertical cylinder; 100301-upper brake, 100302-lifting and lowering cylinder, 100303-lower brake;

[0062] 1101-polar center circle air cooling cover plate, 1102-polar center circle refractory material, 1103-polar center circle air inlet, 1104-fixing plate, 1105-top screw pull rod, 1106-limiting block;

[0063] 1201-clamping bolt, 1202-clamping buckle. DETAILED DESCRIPTION

[0064] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0065] Example 1, a large electric melting furnace for rock wool

[0066] The invention provides a large electric melting furnace for rock wool, with a furnace diameter of 6-12 meters, a furnace height of 3-6 meters, an electrode diameter of 450-850 mm, a polar center circle diameter of 1.8-4.0 meters adjustable, a melting capacity of 10-30 tons / hour, and a power of 10-30 MVA.

[0067] Structure Figure 1 and Figure 8 As shown, it includes a furnace bottom 1, a furnace shell bottom layer 2, a furnace shell middle part 3, a furnace shell upper part 4, a furnace cover 5, a melt outlet 6, an iron discharge outlet 7, a side emergency evacuation outlet 8, a material discharge system 9, an electrode system 10, an adjustable pole center circle 11 and an electrode seal 12.

[0068] The electric melting furnace uses refractory materials as the inner lining structure. The refractory materials are a combination of high temperature resistant and corrosion resistant refractory materials, mainly high aluminum, high magnesium and high chromium refractory materials.

[0069] The furnace bottom 1 is a frame supporting the upper structure, including a furnace bottom foundation 103 at the bottom and a furnace bottom support 104 located on the top of the furnace bottom foundation 103. The furnace bottom foundation 103 is connected to the furnace shell bottom layer 2 through the furnace bottom support 104. A furnace bottom air duct 102 is arranged above the furnace bottom foundation 103 and between the furnace bottom supports 104, and a furnace bottom fan 101 is arranged at the end of the furnace bottom air duct 102.

[0070] In this embodiment, Fig. 9 As shown, the furnace bottom 1 is provided with 6-20 independent furnace bottom air ducts 102 for cooling, and each furnace bottom air duct 102 corresponds to a furnace bottom fan 101, cooling the bottom plate 204 of the bottom layer 2 of the furnace shell. The advantage of centralized cooling compared to the traditional one large fan is that each channel uses an independent cooling fan to cool the furnace bottom, and the air volume of any fan can be flexibly adjusted, and the local temperature of different parts of the furnace bottom can be flexibly controlled. For example, if the area to be cooled in the middle of the electric melting furnace is large and the temperature is high, the cooling air volume is relatively controlled to be larger; if the area to be cooled on both sides is small and the temperature is low, the cooling air volume is relatively controlled to be smaller.

[0071] The bottom layer 2 of the furnace shell includes an annular steel plate 201 on which reinforcing ribs 203 are arranged. The bottom of the bottom layer 2 of the furnace shell is connected to the furnace bottom 1 through a bottom plate 204, and the top is connected to the middle part 3 of the furnace shell through a bottom flange 202 of the furnace shell.

[0072] The annular steel plate 201 is 20-30 mm thick and is divided into 8-20 independent pieces. It is located at the bottom of the furnace for heat preservation. The upper and lower parts are connected by flanges. There are several holes on each upper flange, which are connected to the cooling wall in the middle of the adjacent furnace shell through bolts and other fasteners. Reinforcement ribs are also provided between the flange and the outer plate to strengthen the rigidity of the flange and the steel plate. The bottom plate is made of 20-30 mm thick steel plate. The bottom and top sheets are designed as single pieces, and the bottom plate is made into 3-5 pieces or more for easy transportation and installation.

[0073] The middle part 3 of the furnace shell is composed of an arc-shaped cooling wall 309, such as Figure 1 and Figure 2 As shown, each layer of the arc-shaped cooling stave is divided into 8-20 independent blocks, which is convenient for manufacturing, transportation and installation. Each arc-shaped cooling stave is an independent closed forced water-cooled closed circulation structure, including a cooling stave inner plate 304, a cooling stave outer plate 303 and a cooling stave side plate. The cooling stave inner plate 304, the cooling stave outer plate 303 and the cooling stave side plate form a cavity, and a labyrinth waterway baffle 301 is arranged inside the cavity to set the water-cooled closed circulation into a labyrinth waterway form. Each arc-shaped forced cooling stave is provided with an inspection hole 302, a cooling water inlet and outlet 305, a cleaning door flange 306, an exhaust hole 307, and a temperature detection hole 308, which are respectively connected to the upper part of the furnace shell and the bottom layer of the furnace shell through the upper and lower flanges, and connected to other cooling staves through the side flanges. The cooling stave inner plate 304, the cooling stave outer plate 303 and the upper and lower flanges, and the side flanges are connected with triangular reinforcing ribs to enhance the connection strength. The labyrinth is not limited to the up and down direction, and can also be left and right when necessary. The water channel flow cross-sectional area, water flow rate and water inlet temperature are strictly calculated based on the three-dimensional model Fluent finite element heat transfer simulation. This method can fully reduce the temperature of the inner wall refractory material, making it easier to slag inside the refractory material, forming a condensation furnace lining, and extending the service life of the refractory material.

[0074] The outer plate of the arc-shaped cooling wall is made of 5-10 mm thick steel plate. The inner plate is made of 20-30 mm thick steel plate. Taking into account the unfavorable conditions of thermal expansion and contraction in the furnace, the inner plate is made of a whole plate to avoid cracking. Each arc-shaped cooling wall is provided with two cooling water inlets and outlets, which are generally diagonally distributed. The upper part of each cooling wall is provided with an exhaust hole for discharging trapped air, and the exhaust holes are provided in plurality according to the layout of the maze. The lower part of each cooling wall is also provided with a plurality of cleaning doors for cleaning accumulated impurities, rust, etc., and the cleaning door flange cover is sealed. The arc-shaped cooling wall is surrounded by flanges with dozens of holes on the flanges. The cooling wall is connected to the upper, lower, left and right cooling walls adjacent to it by bolts and other fasteners. A triangular reinforcement rib is also provided between the flange and the outer plate to strengthen the rigidity of the flange.

[0075] The arc-shaped cooling wall is a forced closed-circulation water-cooling structure. The water pump provides water flow power. The forced closed-circulation water-cooling structure effectively reduces the temperature of the refractory materials in the furnace. The refractory materials are heat-conductive refractory materials. The forced closed-circulation water-cooling structure is to ensure slagging on the inner wall of the electric furnace to form a condensed furnace lining. The formed slag layer is used to protect the refractory materials in the furnace and reduce the erosion of the refractory materials by the melt in the furnace.

[0076] The furnace bottom refractory material is arranged inside the annular steel plate 201 of the bottom layer 2 of the furnace shell and inside the lower arc-shaped cooling wall 309 of the middle part 3 of the furnace shell. It is a combination of high-temperature resistant and corrosion-resistant refractory materials, mainly high-aluminum, high-magnesium and high-chromium refractory materials. Each piece of furnace bottom refractory material is composed of 4-6 layers of high-aluminum bricks, 2-4 layers of high-magnesium bricks, 1-2 layers of high-chrome bricks, and multiple layers of cast and ramming materials from bottom to top, with a thickness of about 1 meter.

[0077] Several thermocouples 205 are installed on the furnace bottom refractory material to monitor the temperature changes of the furnace bottom refractory material.

[0078] 5-20 temperature measuring points are set on each cooling wall, and the temperature measuring points are evenly distributed at equal heights. Thermocouples and thermal resistors are used for temperature measurement. The temperature measuring points measure the change in the cooling water temperature in the water channel, and can also measure the temperature of the contact surface between the inner plate of the cooling wall and the refractory material, the temperature of the contact surface between the outermost layer of refractory material and the second to last layer of refractory material, and the temperature of the contact surface between other different layers of refractory materials. The measured temperature data is analyzed centrally, and combined with the electric valves and flow meters respectively installed in the water cooling branches, the different flow rates of water entering different cooling walls are adjusted according to the changes in the temperature of the side walls of the furnace body. Accurate temperature control is achieved to prevent excessive water from causing the local furnace body temperature to be too low, resulting in excessive slag on the furnace wall and excessive heat loss; or too little water from causing the local furnace body temperature to be too high, causing erosion of the furnace wall refractory material.

[0079] The upper part 4 of the furnace shell is also composed of arc-shaped cooling walls. Each layer of the arc-shaped cooling walls is divided into independent 8-20 arc-shaped cooling wall modules. The same as the middle part 3 of the furnace shell is that it includes a cooling wall inner plate, a cooling wall outer plate and a cooling wall side plate to form a cavity. The unique feature is that each block is an independent closed air-cooled closed cycle. The air-cooled closed cycle is arranged in a maze form through a baffle. The maze is not limited to the up and down direction, but can also be left and right. The cross-sectional area, flow rate and temperature of the air duct flow are strictly calculated according to the three-dimensional model Fluent finite element heat transfer simulation. This method can not only fully reduce the temperature of the refractory material on the surface of the insulation layer. The upper layer is not limited to air cooling, but can also be water-cooled. Air cooling is for the comprehensive utilization of the heat of the outlet hot air. On the outer plate of the cooling wall, each arc-shaped cooling wall module is respectively provided with an upper furnace shell air inlet and outlet 401, which is divided into an independent air inlet and an air outlet.

[0080] The middle part of the furnace shell is the core part of the electric melting furnace. The middle part of the furnace shell is the high-temperature molten pool area and the part for holding the melt. The refractory material is heat-conductive, and the internal temperature of the refractory material can reach 1500°C. The present invention adopts water cooling for cooling; the reason is that: air cooling here cannot achieve the cooling requirements, and the heat dissipation effect of water cooling is much higher than that of air cooling. Water cooling can effectively reduce the temperature of the furnace body, prevent overheating and damage, extend the service life of the furnace body, and improve the operating efficiency and safety of the electric melting furnace.

[0081] At the same time, in this structure, the upper part of the furnace shell is a heat preservation area, not a molten pool, and the refractory material is a heat preservation type. The internal temperature of the refractory material is not more than 700°C, and both air cooling and water cooling can meet the cooling requirements.

[0082] The upper layer has 3-8 upper furnace shell monitoring holes 402 for monitoring the furnace conditions on the side. The monitoring holes are equipped with upper furnace shell monitoring equipment 403. The monitoring equipment is resistant to high temperatures and has other cooling structures such as water cooling and air cooling. The purpose of monitoring is to monitor the electrodes, magma, raw material distribution, and melting state in the furnace in real time to evaluate the production status. At the same time, 3-5 upper furnace shell inspection holes 404 are opened on the side, and an upper furnace shell inspection door 405 is installed. The inspection door is sealed and has refractory materials inside.

[0083] The furnace shell has expansion gaps between adjacent panels to allow for differential expansion between the panels.

[0084] The furnace cover 5 is composed of 6 to 20 independent furnace cover panels. Figure 1 and Figure 3 As shown in the figure, each furnace cover plate is surrounded by flanges with dozens of holes on the flanges. The furnace cover plate is connected to the adjacent front, rear, left and right furnace cover plates by bolts and other fasteners. The unique feature is that it adopts an air-cooled structure instead of water-cooled. The flow channel is composed of a series of partitions, which form a maze with a constant cross-sectional area so that the wind speed passing through it is as constant as possible (the cross-sectional area is constant under the condition of constant air volume to ensure constant wind speed, wind speed = air volume ÷ cross-sectional area). The layout of the maze flow channel is set and arranged according to the shape of different parts, and there is no fixed form. The significance of requiring a constant wind speed is that the heat received by the furnace cover is mainly the radiation heat of the melt, and the heat per unit area per unit time is basically uniform. The constant wind speed is to ensure that each part of each furnace cover is evenly cooled and takes away the same amount of heat per unit time, so as to avoid local cooling too fast or too slow, causing stress concentration and deformation inside the furnace cover. In addition, the constant wind speed also helps to optimize the cooling process, so that the furnace cover can smoothly reach the required cooling temperature and accurately control the temperature. This ensures the cooling of the equipment and its service life. Each furnace cover plate adopts an independent wind system, and is respectively provided with a furnace cover air inlet and air outlet 501. The air volume is adjustable through the valves of the air inlet and outlet. This structure can avoid the adverse effects of accidental water leakage into the furnace due to the traditional water-cooled furnace cover structure while ensuring cooling. Air cooling can also make comprehensive use of the heat of the outlet hot air. The furnace cover plate is divided into an inner circle plate with an electrode hole 502 and an outer circle plate located outside the inner circle plate; a furnace cover discharge hole 503 is set at the connection between adjacent furnace cover plates, a furnace cover exhaust gas outlet 504 is set on one furnace cover plate, and a furnace cover liquid level measuring hole 505 is set on another furnace cover plate; the exhaust gas outlet 504 is connected to the exhaust gas treatment mechanism, and the exhaust gas treatment mechanism can adopt heat exchange or other methods with waste heat utilization structure. There are related solutions in the prior art, which will not be repeated here.

[0085] The three-phase electrodes are insulated from each other by high-temperature resistant insulating material 506 between each furnace cover plate near the electrode, so as to ensure safety and avoid the formation of circular induced current due to electromagnetic induction.

[0086] An expansion gap 507 is left between adjacent roof panels to allow for differential expansion between the panels.

[0087] In this embodiment, the air outlet on the upper part of the furnace shell and the air outlet on the furnace cover are connected to the dryer through pipelines, and the return air heat is used in the dryer to dry the raw materials, so that all the heat is utilized.

[0088] The cooling of the upper part of the furnace shell and the furnace cover of the traditional rock wool electric furnace is basically external water cooling. The external water circulation takes away some heat while cooling the electric furnace. At the same time, the external water circulation needs a cooling tower to cool down. It is actually just energy conversion, resulting in heat waste in the water circulation. The cooling of the upper part of the furnace shell and the furnace cover of the rock wool electric furnace invented in this invention is an air-cooled structure. Natural air is blown into the furnace cover through a fan for cooling, taking away heat and increasing the outlet air temperature. The return air with heat enters the dryer combustion chamber through a pipe, which reduces the use of natural gas by increasing the heat supply.

[0089] The melt outlet 6, including the furnace door, is arranged on the melt outlet base 601, such as Figure 1 and Figure 4 As shown, the melt outlet base 601 is a hollow water-cooled part welded to the cooling wall of the middle part 3 of the furnace shell, which is used to connect the furnace body and the various accessories of the melt outlet. The water-cooled back plate 603 is connected to the melt outlet base by bolts. A base water-cooling pipe 6101 is set on the side to connect the cold water and return water pipelines. The base is used to connect the furnace body and the various accessories of the melt outlet. The hollow base is welded to the cooling wall of the furnace body. The inner hole of the base is elliptical, and a prefabricated oblong refractory brick 602 is installed in the inner hole of the base. There are no less than 2 circular melt flow channels 6201 reserved on the oblong refractory brick, and the reserved diameter of the circular channel is 30-150mm. The circular channels are arranged up and down and are on the same vertical line, with only different heights. The oblong refractory bricks and the hollow water-cooled base are conically nested and fit tightly. During production, a flow channel with a moderate height is selected for use, and the remaining reserved flow channels are blocked with refractory castables. The melt outlet is set to be adjustable in relative height up and down. According to the production process, when the relative height of the melt outlet needs to be adjusted, refractory castables are used to block unused circulation channels, and the water-cooled back plates 603 corresponding to different heights are replaced to open the reserved circulation channels to be used. The melt control door installed on the water-cooled back plate is universal and suitable for small back plates of different heights, so that the relative height of the melt outlet can be adjusted. The adjustment of the relative height of the melt outlet refers to the relative height relative to the iron discharge port and the furnace bottom. A back plate water cooling pipe 6301 is set on the side of the water-cooled back plate 603 to connect the cold water and return water pipelines.

[0090] All channels for melt flow at the furnace outlet are water-cooled and made of special stainless steel. The relevant structures can also be easily disassembled and replaced when worn.

[0091] The melt control door is a servo-driven mechanical device. The servo motor drives the lifting mechanism to drive the slide up and down to control the opening of the discharge center port. The control accuracy is 0.1mm to ensure the best melt flow to the centrifuge. The melt control door is also equipped with a spare manual device 6510, which is activated when the drive motor or melt gate lifting mechanism fails. In order to cope with possible emergencies and ensure the safety of the production process, the melt control door is also equipped with a quick closing device. The quick closing device is pneumatic and is activated in an emergency when the furnace door needs to be closed quickly. It can quickly cut off the flow of the melt, prevent possible accidents, and ensure the safety of the production process.

[0092] Melt control door Figure 4 As shown, it includes a melt door 604 and a melt door driving device 605. The melt door 604 is fixed to a water-cooled back plate 603, and includes a door frame. The door frame is provided with a melt outlet 6402 and a pin hole 6403 connected to a fluid flow channel 6201. A water cooling channel is provided in the door frame, and the cold water and return water pipelines are connected through a melt door water cooling pipe 6401.

[0093] The melt door driving device 605 includes a driving device bracket 6503 fixed on the water-cooled wall 3 in the middle of the furnace body, and a servo motor 6501 and a reducer 6502 arranged on the driving device bracket 6503. The output end of the reducer 6502 is connected to a connecting rod 6504. The connecting rod 6504 is rotatably arranged on the driving device bracket 6503 through a bearing structure, and a gear 6505 is arranged on the connecting rod 6504.

[0094] The melt door drive device 605 also includes a slide plate 6507 passing through the drive device bracket 6503, and a rack 6506 meshing with the gear 6505 is arranged on the slide plate 6507. The slide plate 6507 is connected to a latch 6508 below, and the latch 6508 passes through the pin hole 6403 of the door frame. Driven by the servo motor 6501, the connecting rod 6504 and its gear 6505 rotate, driving the rack 6506 and the slide plate 6507 to rise and fall, so that the latch 6508 moves to control the opening of the melt outlet 6402. A latch water cooling pipe 65801 is arranged on the latch 6508 to connect to the cold water pipe and the return water pipe.

[0095] The melt outlet 6402 on the door frame is provided with an arc-shaped contact surface in the shape of a matching latch 6508 .

[0096] Furthermore, a quick closing device 6511 is provided, comprising a quick closing cylinder 651101 fixedly arranged on the water-cooled wall 3 in the middle part of the furnace body or on the driving device bracket 6503, a crank structure 651102 hinged to the telescopic rod of the quick closing cylinder 651101, and a pressure block 651103 connected to the crank structure, the pressure block is located above the slide plate 6507, and the crank structure 651102 is arranged on the driving device bracket 6503 through a pin shaft.

[0097] The melt door drive device 605 also includes a meshing drive cylinder 6509 arranged on the water-cooled wall 3 in the middle part of the furnace body or on the drive device bracket 6503. The meshing drive cylinder 6509 is a small cylinder, and the telescopic end is hinged to the upper end of the rack 6506. The lower end of the rack 6506 is connected to the slide plate 6507 by a hinged manner. The rack 6506 can swing relative to the slide plate 6507. The function of the meshing drive cylinder 6509 is to determine whether the rack 6506 and the gear 6505 are in a meshing state. During normal operation, the quick-closing cylinder 651101 retracts and the meshing drive cylinder 6509 extends. At this time, the rack 6506 and the gear 6505 are normally meshed. At this time, the furnace door is driven by the servo motor 6501 and can be raised and lowered normally. During abnormal operation, the quick-closing cylinder 651101 extends and the meshing drive cylinder 6509 retracts. At this time, the rack 6506 and the gear 6505 are not meshed. Under the action of the quick-closing cylinder 651101 and various levers, the furnace door can be quickly closed.

[0098] A melt outlet eye-drilling machine 606 is also provided facing the melt outlet. When the melt door is closed due to an emergency, the melt in the channel will solidify quickly because the surrounding of the channel is water-cooled. When production needs to continue, the melt control door is opened, and the eye-drilling machine can drill holes quickly and leave quickly. Instead of the traditional manual impact drill, the eye-drilling of the electric furnace is mechanized and automated. The eye-drilling machine is not only fast and stable, but also reduces the damage to the refractory of the melt outlet channel in the traditional operation mode.

[0099] The side wall of the middle part 3 of the furnace shell is also provided with an iron discharge port 7. Figure 1 and Figure 5 As shown, multi-layer chrome corundum bricks are used inside the iron outlet. Chrome corundum bricks have strong corrosion and scouring resistance. The left and right sides and upper and lower refractory materials near the iron water outlet are built into a stop structure, which effectively prevents the leakage of molten iron. Multiple water-cooled copper plates 701 are set on the four sides of the iron outlet 7 and embedded in the refractory material, which effectively reduces the temperature around the iron water outlet. When there is enough cooling water, the molten iron and melt have little corrosion on the copper plate. Silicon carbide or chrome corundum flow brick 702 structure is used at the center of the iron outlet. Silicon carbide or chrome corundum flow brick has high thermal conductivity, good resistance to molten iron corrosion, and low expansion rate. When used in combination with water-cooled copper plates, the effect is better than the structure of traditional electric furnaces using magnesium bricks alone.

[0100] The iron outlet is provided with a hole-opening and plugging machine 703, which can take care of multiple iron outlets at the same time. This mechanism has multiple uses, that is, it can quickly drill holes and plug mud and seal holes at any time. Figure 5 As shown, the eye opening and plugging machine 703 of this structure includes an eye opening machine 7031, an eye plugging machine 7032 and an eye opening and plugging machine arc roller 7033. The eye opening and plugging machine arc roller 7033 is welded under the beam of the melting building in front of the iron discharge port, and the eye opening and plugging machine is installed and suspended under the arc roller. The melting building is a building, a workshop for installing / using electric melting furnaces, and a floor of a concrete or steel structure frame. The main machine of the eye opening and plugging machine is provided with a walking part, and the four walking wheels of the walking part are installed on the eye opening and plugging machine arc roller 7033, and the walking wheels are driven to travel on the arc track by a reduction motor, gears, etc. The eye opening and plugging machine is a mature professional equipment in the field of smelting, which will not be repeated here.

[0101] It replaces the traditional oxygen eye blowing operation mode, making the opening and blocking of electric furnace eyes mechanized and automated, reducing excessive mechanical scouring of furnace mouth refractory materials under the traditional operation mode and avoiding damage to the furnace eye channel and refractory materials inside the furnace eye during oxygen eye blowing.

[0102] The liquid iron discharged from the iron outlet flows out through the refractory channel 704, and the refractory channel sends the molten iron to the ladle 705 on the ground layer for collection. At least three ladles are required, which are arranged in series from high to low.

[0103] The side wall of the middle part 3 of the furnace shell is also provided with two emergency evacuation exits, which are respectively provided on the side and bottom of the furnace shell.

[0104] The side emergency evacuation outlet 8 is located at a certain height and angle, and the height is usually set on the horizontal plane of the lowest height of the magma in the furnace, and the angle is generally opposite to the slurry outlet. The side emergency evacuation outlet is inlaid with water-cooled copper blocks around the side wall opening, including inner water-cooled copper blocks 801 and outer water-cooled copper blocks 802. The water-cooled blocks are distributed in an annular manner, and prefabricated refractory bricks or castings are placed in the water-cooled blocks, and evacuation ports are reserved on the refractory bricks or castings. A detachable skeleton square box 803 is set on the outside and fixed to the flange of the side emergency evacuation outlet. The skeleton square box is also inlaid with water-cooled blocks, which are distributed in an annular manner. Prefabricated refractory bricks 804 are placed in the water-cooled blocks, and evacuation ports are reserved on the refractory bricks. All evacuation ports are blocked with refractory mud, etc. In case of emergency, the evacuation port is opened with a plugging machine or other means, and all magma is taken out of the furnace for emergency or overhaul maintenance.

[0105] The bottom emergency evacuation exit is set just below the center of the furnace. There is a reserved evacuation opening on the refractory bricks of the lower part of the refractory material, and the refractory bricks of the upper part of the refractory material are completely covered without an evacuation opening. It is only opened when the furnace is shut down for overhaul to remove all the magma and molten iron from the furnace.

[0106] A feeding system 9 is arranged above the furnace cover 5: Figure 1 and Figure 6 As shown, it includes a kiln head storage bin 901, an electric screw conveyor 902, a weighing device 903, a flap valve 904, and a feed pipe 905 which are connected in sequence. The feed pipe 905 passes through the furnace cover 5, and a rotating material distribution device 907 is arranged at the bottom.

[0107] The material unloading system uses 8-16 kiln head storage bins 901, each of which is set to a storage capacity of 15-30 tons, which can ensure the usage of no less than 12 hours. Each kiln head bin holds different raw materials according to process requirements, such as basalt, dolomite, slag, waste cotton and waste residue, industrial waste and construction waste. The bottom of the kiln head storage bin is wear-resistant, and each bin corresponds to 1-2 unloading systems, so there are a total of 10-30 unloading systems. Electric screw conveyors are used for quantitative unloading, and the speed and time of the screw conveyors are set to control the unloading amount.

[0108] The bottom of the kiln head storage bin 901 is connected to an electric screw conveyor 902, a weighing device 903 is provided at the rear end of the electric screw conveyor, and a flap valve 904 is installed below the weighing device to accurately control the amount of material discharge according to the needs in the furnace.

[0109] The feeding pipe 905 is made of non-magnetic stainless steel. Each feeding pipe is equipped with a cooling fan to supply air. The fan air volume is frequency-controlled. The cooling air cools the feeding pipe extending into the furnace and adjusts the flue gas temperature in the furnace. A large electric furnace is equipped with 10-30 feeding pipes, which are arranged around each electrode, between two electrodes, and in the center of the furnace body. The arrangement fully considers the balance between feeding and melting.

[0110] A rotating material distribution device 907 is provided at the tail of the material discharging pipe. The main body of the material distribution device is a cone 9701, and propeller-shaped blades 9702 are welded on the surface of the cone. The cone and the spiral blades are both made of high temperature and wear-resistant materials. The cone plays a guiding role. The propeller-shaped blades can rotate freely under the push and impact of the raw materials when discharging. The rotating material distribution device can also be driven by an external driving power 9703 to rotate the rotating material distribution device. It plays a role in evenly distributing materials and avoiding material deviation, so that the melting in the electric melting furnace is more uniform and sufficient, and the material layer is more evenly covered.

[0111] There are two types of operation for electric melting furnaces: black top operation and red top operation. The so-called red top operation means that the material layer is too thin and uneven during production, the hot melt and most of the electrodes are exposed, extremely high radiant heat is generated in the furnace, the temperature of the free space in the furnace exceeds 1000℃, the free space in the furnace and the inner surface of the furnace cover are in a red hot state, at this time, the heat loss of the furnace cover is large and the exhaust gas treatment system is complex. The so-called black top operation means that the material layer is thick and evenly distributed during production, the hot melt and electrodes are covered by the material layer, the free space temperature in the furnace does not exceed 500℃, and the upper surface of the melt layer, the free space in the furnace and the inner surface of the furnace cover are not red hot. At this time, the heat loss of the furnace cover is small and the exhaust gas treatment system is relatively simple.

[0112] In the present invention, the material layer is evenly covered for the black top operation in the furnace. In the black top operation, the material layer on the top of the melt can buffer the influence of power change on the melt temperature. The temperature of the free space and the furnace cover of the black top operation does not exceed 500°C, the heat loss is minimized, and the waste gas and dust treatment of the process is simpler, safer and more reliable.

[0113] The feed pipe is provided with a cooling fan 906 to supply air. The feed pipe fan reduces the temperature in the furnace, lowers the ambient temperature for the generation of nitrogen oxides, reduces the emission of nitrogen oxides, and no longer requires subsequent combustion of natural gas to heat up for SCR denitration reaction. The exhaust temperature inside the traditional rock wool electric furnace is high, at 600-800°C, and the concentration of nitrogen oxides is 300mg / m 3 The temperature of the flue gas in the furnace needs to be lowered to 200℃ for dust collection and then raised to 300℃ for SCR denitration reaction. This time, the flue gas temperature in the furnace was lowered by ventilating the feed pipe position and the temperature was controlled below 450℃. The total amount of nitrogen oxides produced was reduced by 50% year-on-year. After the flue gas is dusted, it does not need to undergo denitration reaction and can directly meet the emission standards, reducing the use of natural gas.

[0114] It also includes an electrode system 10 arranged on the furnace cover 5, such as Figure 1 and Figure 7 As shown, it includes an electrode 1001, an electrode lifting device 1002, a pressing device 1003, a gripper pressure ring 1004, etc. The bottom end of the electrode 1001 extends into the furnace, and the general position extends to the upper middle part of the furnace shell. During production, the electrode is continuously consumed due to arc erosion, chemical reaction, mechanical loss, etc.

[0115] The electrode lifting device 1002 includes a hanging vertical cylinder 100201 and a pressing platform 100202. The electrode lifting device is used to change the depth of the electrode inserted into the furnace charge, adjust the operating resistance, and make the input furnace power reach the rated requirements. One end of the hanging vertical cylinder 100201 is suspended and fixed on the hanging bracket on the steel beam of the melting building, and the other end is connected to the pressing platform through fasteners. One end of the pressing platform 100202 is connected to the hanging vertical cylinder 100201, and the other end is connected to the pressing device 1003, and the function is to support and connect the pressing device 1003 and the electrode 1001.

[0116] Each phase electrode is equipped with a set of pressure release device 1003 and a gripper pressure ring 1004. The pressure release device 1003 includes an upper brake 100301, a lower brake 100303 and a lifting and lowering pressure release cylinder 100302. A lifting and lowering pressure release cylinder is set between the upper brake and the lower brake. A hanging vertical cylinder 100201 is used to lift and lower the electrode. The combined operation of the upper brake and the lower brake realizes the pressure release of the electrode. The opening, lifting and pressure release of the brake are all completed by the hydraulic system. In normal working state, the pressure of the butterfly spring group in the brake acts on the brake shoe to clamp the electrode body. The electrode pressure release process is: the upper brake is released → the lifting and lowering pressure release cylinder 100302 extends → the upper brake is tightened → the lower brake is released → the lifting and lowering pressure release cylinder 100302 retracts → the lower brake is tightened. Electrode pressure release is a mature professional equipment in the smelting field, so it is not limited here.

[0117] It also includes an adjustable pole center circle 11: in order to meet the process production requirements of a large electric furnace, the pole center circle of the electric furnace is set as an adjustable mechanism, and the pole center circle diameter can be adjusted within the range of 1.8-4 meters. The electrode column hanging bracket of the hanging electrode system and the electrode seal on the electric furnace cover can be adjusted within the range of 1.8-4 meters.

[0118] Adjustable pole center circle means that the relative distance between two electrodes can be changed, in order to avoid the melting dead zone in the furnace, accurately control the electrode resistance, improve the melt homogenization, improve the uniformity of power distribution, and improve the intensity of melt convection. The pole center circle is adjusted to change the electrode resistance distribution according to the process requirements such as electrode insertion depth, melt liquid level height, component formula, etc., so as to balance power, improve efficiency, and increase output.

[0119] The electrode is arranged on an adjustable pole center circle. The three adjustable pole center circles 11 are distributed in an equilateral triangle and are respectively arranged on the three furnace cover plates (inner circle plates) at the innermost end of the furnace cover 5. The principle of top screw pull rod adjustment is adopted. A fixed plate 1104 is arranged at the corresponding position of the furnace cover 5 close to the electrode. The fixed plate 1104 faces the center of the furnace cover. Waist-shaped electrode holes for the electrodes to pass through are arranged on the three furnace cover plates at the innermost end of the furnace cover 5 (not shown in the figure, blocked by the pole center circle refractory material 1102). A pair of limit blocks 1106 are respectively arranged on both sides of the waist-shaped electrode holes. The limit blocks 1106 serve as tracks to limit the trajectory of electrode movement.

[0120] The adjustable polar center circle 11 is located on the three furnace cover plates at the innermost end of the furnace cover, and is provided with a polar center circle air cooling cover plate 1101. A polar center circle refractory material 1102 is provided under the polar center circle air cooling cover plate 1101 for protection. The air cooling cover plate is provided with a labyrinth air duct and a polar center circle air inlet 1103 for air cooling, including a left air inlet and a right air inlet. The air inlet volume can be adjusted. The choice of air cooling is to ensure cooling while avoiding the adverse effects of accidental water leakage in the traditional water-cooled furnace cover structure. The air outlet of the air cooling cover plate is arranged along the periphery of the electrode, and the gas blows into the furnace body along the gap between the electrode and the electrode hole, forming a ring airflow that seals the flue gas. On the one hand, it effectively cools the electrode hole of the furnace cover, and on the other hand, it cools the connection position of the electrode and the adjustable polar center circle, while guiding the airflow in the electric melting furnace downward to avoid the overflow of flue gas in the electric melting furnace.

[0121] The limit blocks 1106 of the furnace cover 5 are located on both sides of the adjustable polar center circle 11. The top screw rod 1105 connects the furnace cover plate and the adjustable polar center circle 11. The top screw rod 1105 is a threaded structure and is fixed on the fixed plate 1104 by a nut. When the polar center circle diameter needs to be adjusted, the nut on the top screw rod 1105 is turned, and the elliptical air-cooled cover plate 1101 and the electrode seal 12 are pulled / pushed to slide along the limit blocks 1106 to adjust the electrode position.

[0122] During adjustment, 11 positions of the adjustable polar center circle and 100201 positions of the large vertical cylinder can be adjusted simultaneously.

[0123] There is no controller involved here, and manual adjustment is used because the electromagnetic induction of the electric furnace is strong here, and it is not suitable for an electric structure.

[0124] An electrode seal 12 is arranged at the contact position between the adjustable pole center circle 11 and the electrode 1001. The electrode seal 12 adopts at least two levels of soft seals. Each level of soft seals is composed of multiple layers of high temperature resistant insulating materials. The high temperature resistant insulating materials are nested with each other. Each level adopts a clamping bolt 1201 and a clamping buckle to adjust the clamping. It has the advantages of strong self-adaptation ability and high reliability, so that the electrode sealing device can adapt to the vibration, deflection and slippage of the electrode during operation.

[0125] Example 2, a method for heating rock wool raw materials

[0126] The large electric melting furnace for rock wool provided in Example 1 is used, comprising the following steps:

[0127] Step 1, pre-adding materials and turning on the electric furnace to increase the temperature;

[0128] Step 2, the electric furnace cover is ventilated through the air inlet and outlet; cooling water is introduced into the middle of the furnace shell; the furnace bottom is ventilated; and the thermocouple at the bottom of the furnace shell detects the temperature;

[0129] Step 3, adjusting the electrode insertion depth by the electrode lifting device, and adjusting the relative distance of the electrodes by the top wire pull rod of the adjustable pole center circle, so that the material in the furnace melts and the temperature reaches the predetermined temperature and is stable;

[0130] When the furnace is opened or the material properties are changed on a large scale, in order to make the materials in the furnace melt evenly and stably, the power can be cut off for a short time to adjust the relative distance of the electrodes so that the large electric furnace can play the maximum efficiency; after heating or during normal production, since the large electric melting furnace has a large melt reserve in the furnace, even if the power is cut off for several hours, it can buffer for a period of time without affecting continuous production.

[0131] Step 4, the material is continuously circulated and supplied into the furnace shell by the material feeding system;

[0132] The materials can be conventional materials for rock wool production, including basalt, diabase, dolomite, etc.;

[0133] The material can also be industrial waste, including but not limited to fly ash, magnesium slag, blast furnace slag, blast furnace slag, construction waste (building bricks, concrete, rock wool, slag wool, glass wool, aluminum silicate, etc.), etc. After the waste and other raw materials are proportioned, as long as the average silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, iron oxide, titanium dioxide, etc. contained are within the range of rock wool or slag wool, for example, silicon dioxide 30-55%, aluminum oxide 10-20%, calcium oxide 15-30%, magnesium oxide 5-20%, iron oxide 0-15%, titanium dioxide 0-5%. The electric melting furnace provided by the present invention can effectively utilize industrial waste and construction waste.

[0134] In other embodiments, the material may also be a mixture of conventional rock wool production materials and industrial waste in a certain proportion.

[0135] Step 5, the temperature is detected by the thermocouple, and the process parameters are adjusted by air cooling of the furnace cover and furnace bottom and water cooling structure in the middle of the furnace shell;

[0136] Step 6, adjusting the electrode insertion depth and controlling the input power through the output voltage of the transformer connected to the electrode;

[0137] Step 7, the melt is continuously discharged through the melt outlet;

[0138] Step 4, step 5, step 6 and step 7 are a closed loop.

[0139] During the production of an electric furnace, molten iron is discharged through the iron outlet at regular intervals.

[0140] The total amount of industrial waste used in this electric furnace accounts for 0-100% of all raw materials. The melting capacity of this electric furnace is 10-30 tons / hour. The strong melting capacity, large melt reserve (100-300 tons) and extremely high melting temperature (1600-2000℃) can fully melt and homogenize all the waste entering the electric furnace. The strong melting capacity and large melt reserve are achieved by relying on the electric furnace with a furnace diameter of 6-12 meters, a furnace height of 3-6 meters, an electrode diameter of 450-850mm, an adjustable polar circle diameter of 1.8-4.0 meters, a melting capacity of 10-30 tons / hour and a power of 10-30MVA. It takes 2-15 hours for the waste to melt and flow out of the melt outlet. After a long high-temperature process, various crystals in the waste have fully become a high-temperature liquid mixture of silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, iron oxide and titanium dioxide.

[0141] The industrial waste materials used by this electric furnace can be either granules or powders, as long as the particle size after crushing is less than or equal to 4cm. The electric furnace has a strong melting capacity, which avoids the problem of powders entering the furnace and forming crusts, effectively increasing the types and range of industrial waste materials that can be used.

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A large electric melting furnace for rock wool, characterized in that: From bottom to top, it includes the furnace bottom, furnace shell bottom, furnace shell middle, furnace shell upper part and furnace cover connected in sequence; The furnace bottom is cooled by a plurality of independent furnace bottom air ducts; the middle part of the furnace shell includes a cooling wall, and each layer of the cooling wall is divided into a plurality of independent blocks; each cooling wall is an independent closed forced water cooling closed cycle structure, including a cooling wall inner plate, a cooling wall outer plate and a cooling wall side plate, and the cooling wall inner plate, the cooling wall outer plate and the cooling wall side plate form a cavity, and a labyrinth waterway baffle is arranged inside the cavity to set the water cooling closed cycle into a labyrinth waterway form; The upper and lower ends of the bottom layer of the furnace shell are respectively connected to the middle part of the furnace shell and the furnace bottom. The bottom layer of the furnace shell includes an annular steel plate. Furnace bottom refractory materials are arranged inside the annular steel plate and inside the cooling wall in the middle part of the furnace shell. Several thermocouples are installed on the furnace bottom refractory materials to monitor the temperature changes of the furnace bottom refractory materials.

2. The large electric melting furnace for rock wool according to claim 1, characterized in that: The furnace cover comprises a plurality of independent furnace cover plates, adopts an air cooling structure, and the flow channel is composed of a series of partitions.

3. The large electric melting furnace for rock wool according to claim 2, characterized in that: The furnace cover plate comprises an inner ring plate with an electrode hole and an outer ring plate located outside the inner ring plate; a furnace cover feed hole is arranged at the connection of adjacent furnace cover plates, a furnace cover exhaust gas outlet is arranged on one of the furnace cover plates, and a furnace cover liquid level measuring hole is arranged on the other furnace cover plate; The three-phase electrodes are insulated from each other by high-temperature resistant insulating materials between the inner circle plates; expansion gaps are left between adjacent furnace cover plates to allow differential expansion between the plates.

4. The large electric melting furnace for rock wool according to claim 1, characterized in that: It also includes a melt outlet arranged on a melt outlet base, the melt outlet base is a hollow water-cooled part connected to a cooling wall in the middle of a furnace shell, a water-cooled back plate is arranged on the back, and the melt outlet is opened and closed by a melt control door; The middle side wall of the furnace shell is also provided with an iron discharge port, the iron discharge port is provided with an eye opening and blocking machine, and a melt outlet eye opening machine facing the melt outlet is also provided.

5. The large electric melting furnace for rock wool according to claim 1, characterized in that: A material discharge system is arranged above the furnace cover, including a kiln head storage bin, an electric screw conveyor, a weighing device, a flap valve, and a material discharge pipe which are connected in sequence. The material discharge pipe passes through the furnace cover, and a rotating material distribution device is arranged at the bottom.

6. The large electric melting furnace for rock wool according to claim 1, characterized in that: It also includes an electrode system arranged on the furnace cover, the electrode system includes an electrode, an electrode lifting device, a pressing device, and a gripper pressure ring; the bottom end of the electrode extends into the furnace, at a position slightly above the middle of the furnace shell; the electrode lifting device includes a hanging vertical cylinder and a pressing platform, one end of the pressing platform is connected to the hanging vertical cylinder, and the other end is connected to the pressing device, the electrode lifting device is used to change the depth of the electrode inserted into the charge, adjust the operating resistance, and make the power input into the furnace reach the rated requirement.

7. The large electric melting furnace for rock wool according to claim 6, characterized in that: It also includes an adjustable pole center circle, the electrode is arranged on the adjustable pole center circle, the three adjustable pole center circles are distributed in a regular triangle, and are respectively arranged on the three inner circle plates at the innermost end of the furnace cover, and the relative distance from the center of the furnace cover is adjusted by a top screw pull rod.

8. The large electric melting furnace for rock wool according to claim 7, characterized in that: A fixed plate facing the center of the furnace cover is arranged on the furnace cover, and waist-shaped electrode holes for the electrodes to pass through are arranged on the three inner circle plates of the furnace cover. A pair of limit blocks are also arranged on both sides of the waist-shaped electrode holes. The limit blocks serve as tracks to limit the trajectory of electrode movement.

9. The large electric melting furnace for rock wool according to claim 7, characterized in that: The adjustable pole center circle is provided with a pole center circle air cooling cover plate, a pole center circle refractory material protection is provided under the pole center circle air cooling cover plate, the air cooling cover plate is provided with a labyrinth air duct, and a pole center circle air inlet for air cooling; the air outlet of the air cooling cover plate is arranged along the periphery of the electrode, and the gas is blown into the furnace body along the gap between the electrode and the electrode hole, forming an annular airflow that seals the flue gas, effectively cooling the electrode hole.

10. A method for heating rock wool raw materials, characterized in that: The large-scale electric melting furnace for rock wool according to any one of claims 1 to 9 comprises the following steps: Step 1, pre-adding materials and turning on the electric furnace to increase the temperature; Step 2, the electric furnace cover is ventilated through the air inlet and outlet; cooling water is introduced into the middle of the furnace shell; the furnace bottom is ventilated; and the thermocouple at the bottom of the furnace shell detects the temperature; Step 3, adjusting the electrode insertion depth by the electrode lifting device, and adjusting the relative distance of the electrodes by the top wire pull rod of the adjustable pole center circle, so that the material in the furnace melts and the temperature reaches the predetermined temperature and is stable; Step 4, the material is continuously circulated and supplied into the furnace shell by the feeding system, and the material is one or a mixture of conventional materials for rock wool production and industrial waste; Step 5, the temperature is detected by the thermocouple, and the process parameters are adjusted by air cooling of the furnace cover and furnace bottom and water cooling structure in the middle of the furnace shell; Step 6, adjusting the electrode insertion depth and controlling the input power; Step 7, the melt is continuously discharged through the melt outlet; Step 4, step 5, step 6 and step 7 are a closed loop.

Images