36 MVA Totally Enclosed Submerged Arc DC Ferroalloy Furnace for Manganese Silicon Alloy

Abstract

The present invention discloses a 36MVA fully enclosed submerged arc DC submerged arc furnace for ferromanganese-silicon alloy, comprising: a DC furnace body and at least two sets of transformer-rectifier devices electrically connected to the DC furnace body; an electrode holder is arranged on the DC furnace body and is matched with the output end of the transformer-rectifier device, and an electrode is provided on the electrode holder, and the output end of the transformer-rectifier device is connected to the electrode. Wherein, the DC furnace body is sealed by a furnace cover so that the furnace surface does not burn and the temperature in the furnace is at least 4000 °C during operation. A plurality of through holes for the electrode to pass through are arranged on the furnace cover, the electrode is a self-baking electrode, the rated DC current output by the transformer-rectifier device is at least 70000A, and the rated DC voltage output is at least 260V. By combining the self-baking electrode and the furnace cover sealing design, the present invention reduces the oxidation loss of the electrode and reduces the oxygen content on the furnace surface to inhibit the combustion of CO in the furnace.

Description

Technical Field

[0001] The present invention belongs to the field of submerged arc furnaces, and particularly relates to a 36 MVA manganese-silicon alloy fully enclosed submerged arc DC furnace. Background Art

[0002] Submerged arc furnaces are crucial production equipment in the ferroalloy industry and play an irreplaceable role in smelting ferroalloy products such as silicomanganese, ferrosilicon, ferrochrome, and nickel. In the early days, submerged arc furnaces mainly used the power grid industrial frequency three-phase power supply method after transformer step-down for smelting, mostly in the form of small-capacity and open-type. Limited by the technical level at that time, many problems occurred in the actual application of the traditional submerged arc furnace power supply method, including three-phase imbalance, low power factor, and the resulting harmonic pollution, high smelting energy consumption, and high noise. With the application of DC technology, these problems have been effectively solved, not only balancing the three-phase current, improving the power factor, but also significantly improving the operation efficiency and energy use efficiency of the submerged arc furnace, and making great progress in aspects such as energy conservation, emission reduction, and product quality stability.

[0003] However, the carbothermal reduction reaction of manganese-silicon alloy is an extremely complex high-temperature smelting process, which involves multiphase flow transfer among ore materials, slag, manganese-silicon alloy, and furnace gas, as well as multi-physical field coupling among electromagnetic field, temperature field, flow field, and metal oxide components. For large DC furnaces with high power, it is currently impossible to achieve good stability and controllability. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a 36 MVA manganese-silicon alloy fully enclosed submerged arc DC furnace. The technical problems to be solved by the present invention are achieved through the following technical solutions:

[0005] A 36 MVA manganese-silicon alloy fully enclosed submerged arc DC furnace includes:

[0006] A DC furnace body and at least two sets of transformer-rectifier devices electrically connected to the DC furnace body;

[0007] An electrode holder is provided on the DC furnace body to cooperate with the output end of the transformer-rectifier device. An electrode is provided on the electrode holder, and the output end of the transformer-rectifier device is connected to the electrode. Among them, the DC furnace body is sealed by a furnace cover to prevent combustion on the furnace surface, and the temperature inside the furnace is at least 4000 °C during operation. A plurality of through holes for the electrode to pass through are provided on the furnace cover. The electrode is a self-baking electrode. The rated DC current output by the transformer-rectifier device is at least 70000 A, and the rated DC voltage output is at least 260 V.

[0008] In a specific embodiment, the transformer-rectifier device includes: a transformer bank, a first rectifier cabinet, and a second rectifier cabinet;

[0009] The input end of the transformer bank is connected to a power supply, and the output ends are respectively connected to a first rectifier cabinet and a second rectifier cabinet. The first output end of the first rectifier cabinet and the first output end of the second rectifier cabinet are connected to a first electrode, and the second output end of the first rectifier cabinet and the second output end of the second rectifier cabinet are connected to a second electrode, wherein the first electrode and the second electrode have opposite polarities.

[0010] In a specific embodiment, the transformer bank includes: a voltage regulating transformer, a first rectifier transformer, and a second rectifier transformer; the input end of the voltage regulating transformer is connected to the power supply, the output end of the voltage regulating transformer is connected to the first rectifier transformer and the second rectifier transformer, the first rectifier transformer is connected to the first rectifier cabinet, and the second rectifier transformer is connected to the second rectifier cabinet.

[0011] In a specific embodiment, both the first rectifier cabinet and the second rectifier cabinet include a rectifier circuit, and the number of thyristors on each rectifier arm of the rectifier circuit is determined according to the rated DC current and DC voltage output by the voltage transformation and rectification device.

[0012] In a specific embodiment, the rectifier circuit is a double reverse star rectifier circuit, and the thyristors arranged on the same rectifier arm have a preset forward volt-ampere characteristic curve.

[0013] In a specific embodiment, the voltage regulating transformer includes: an on-load tap-changer, and the on-load tap-changer has a gear controller, and the gear controller is used to control the output voltage of the voltage regulating transformer.

[0014] In a specific embodiment, a control signal generator is further included, the control signal generator is connected to the matrix switch, and the matrix switch is respectively connected to a plurality of gear controllers, a main and standby controller, a remote controller, and a current feedback controller;

[0015] The matrix switch is configured to receive a control signal with a preset coding rule to control the corresponding switch to be turned on or off according to the control signal with the preset coding rule, wherein the control signal with the preset coding rule includes: a signal type field, a linkage field, and a control adjustment field.

[0016] In a specific embodiment, at least a part of the switch nodes of the matrix switch are further connected to a delay circuit, the output ends of the at least a part of the switch nodes are connected to the gear controller, and the control signal with the preset coding rule further includes a delay signal trigger field;

[0017] The control signal generator is further configured to set the signal type field to a field for controlling the gear controller and set the linkage field to a field for controlling the remote controller when it is determined that the thyristor control angle is less than a preset angle.

[0018] In a specific embodiment, the matrix switch is further configured to control the corresponding delay circuit to be enabled when it is determined that the delay signal trigger field in the control signal of the preset coding rule is not empty.

[0019] In a specific embodiment, a DC current sensor is provided at the output end of the variable voltage rectifying device, and current transformers are provided at the input ends of the first rectifying transformer and the second rectifying transformer. The DC current sensor and the current transformers are both connected to the control signal generator;

[0020] The control signal generator is further configured to set the signal type field to a field for controlling the current feedback controller and set the linkage field to a field for controlling the remote controller when it is determined that the feedback signal of the DC current sensor is lost or the feedback signal of the current transformer is lost.

[0021] Advantages of the present invention:

[0022] 1. The 36MVA ferromanganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace of the present invention combines the self-baking electrode and the furnace cover sealing design to reduce the electrode oxidation loss and reduce the oxygen content on the furnace surface to inhibit the combustion of CO in the furnace.

[0023] 2. The 36MVA ferromanganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace of the present invention can accurately control the opening or closing of the corresponding switches by using the control signal generator and the matrix switch in cooperation, and can realize stable control of devices such as the gear controller, the main and standby controllers, the remote controller, and the current feedback controller by receiving the control signal with the preset coding rule, and realize seamless connection control of the corresponding controllers through the linkage field, improving the controllability in case of faults.

[0024] The present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings

[0025] Figure 1 is a block diagram of a 36MVA ferromanganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace provided by an embodiment of the present invention;

[0026] Figure 2 is a circuit schematic diagram of a variable voltage rectifying device of a 36MVA ferromanganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace provided by an embodiment of the present invention;

[0027] Figure 3It is a schematic diagram of the transformer bank of a 36MVA manganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace provided by an embodiment of the present invention;

[0028] Figure 4 It is a schematic diagram of the switch control of a 36MVA manganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace provided by an embodiment of the present invention;

[0029] Figure 5 It is a schematic diagram of the switch control of another 36MVA manganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace provided by an embodiment of the present invention. Detailed implementation manners

[0030] The present invention will be further described in detail below in conjunction with specific embodiments, but the implementation manners of the present invention are not limited thereto. Embodiment

[0031] Please refer to Figure 1 , Figure 1 It is a block diagram of a 36MVA manganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace provided by an embodiment of the present invention, including:

[0032] A DC furnace body 1 and at least two groups of transformer-rectifier devices 2 electrically connected to the DC furnace body 1;

[0033] An electrode holder matching the output end of the transformer-rectifier device 2 is arranged on the DC furnace body 1, an electrode 3 is provided on the electrode holder, and the output end of the transformer-rectifier device 2 is connected to the electrode 3. Among them, the DC furnace body 1 is sealed through a furnace cover so that combustion does not occur on the furnace surface and the temperature in the furnace is at least 4000°C during operation. A plurality of through holes for the electrode to pass through are arranged on the furnace cover. The electrode 3 is a self-baking electrode. The rated DC current output by the transformer-rectifier device is at least 70000A, and the rated DC voltage output is at least 260V.

[0034] It should be noted that the main structure of the 36MVA manganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace in this embodiment is designed and completed according to size requirements. For example, the main structure is mainly divided into: furnace body, furnace cover, feeding system, electrode lifting and pressure release, electrode holder, water cooling system, purification flue, discharge flue, tapping port smoke exhaust, short network, hydraulic system, etc.

[0035] Specifically, the furnace body is a fixed quadrilateral structure. The furnace bottom is forced-ventilated and cooled. The furnace shell is 200 mm higher than the working layer platform for sealing purposes. Two tapping holes are arranged on both sides of the furnace body at 180°. The I-beams at the furnace bottom are arranged side by side with 40C I-beams. Multiple temperature measurements are set at the furnace bottom (at the electrode center and the center of the electric furnace). Accordingly, multiple thermocouples are used (two for each point, with one monitoring position being higher and the other being lower). Three maintenance channels are made at the furnace bottom foundation to facilitate the maintenance and replacement of the thermocouples. The thermocouples for temperature measurement are of type K and can withstand a temperature of 1000 °C. The furnace bottom cooling uses eight mixed-flow fans to ventilate and cool the furnace bottom from the side. The thickness of the side plate of the furnace shell is, for example, 25 mm, the thickness of the furnace bottom plate is 30 mm, and the thickness of the stiffener plate is 16 mm.

[0036] One pneumatic ventilation butterfly valve (which can be remotely operated and is equipped with a manual zipper) is provided behind each of the two tapping fume hoods. After the fume hoods are fabricated, refractory ramming (or refractory fiber blocks are used) is carried out. The hanging of the fume hoods needs to be insulated from the upper platform. The scope of the tapping fume hoods is one ladle and three slag ladles. The tapping fume exhaust pipe extends one meter outside the factory building (a set of dust removal can be shared by multiple furnaces).

[0037] The furnace cover consists of an electrode cover plate, an outer peripheral cover plate, an electrode sealing and guiding device, a maintenance furnace door, an observation door, an explosion-proof device, a pressure measuring device, a temperature measuring device, a suspension rod device, etc. The top cover plate and the side cover plate of the furnace cover form a 90° angle; the electrode seals are all made of 06Cr18Ni11Ti, and the remaining cover plates are made of carbon steel material Q235B. The electrode seal adopts a copper sector seal form, and the material of the copper sector seal ring is H62; mica + ceramic fiber + glass ribbon is used as the insulation between the cover plate and the material pipe, and refractory castable is used for sealing after the refractory bricks are positioned. Four detachable furnace doors are set at the electrode intervals, and four small doors are also provided. Explosion-proof holes, two pressure detection points, 16 material pipe holes, four electrode through holes, and two flue cover plates are set on the furnace cover; a total of one temperature measuring point is set at the center of the furnace cover, and one temperature measuring point is set on each of the two flues. The supply and welding of the cover anchor hooks are provided. The thickness of the bottom plate is 10 mm, and the thickness of the outer water isolation plate and the cover plate is 8 mm.

[0038] The electrode holder consists of copper shoes, copper pressure rings, water-cooled protection screens, conductive copper pipes, copper shoe suspensions, pressure ring suspensions, lower holding cylinders, water-cooled pipelines, insulation, etc.

[0039] The electrode holder adopts the corrugated pipe pressure ring type. The pressure ring type electrode holder realizes the pressing of the copper bushing against the electrode by filling pressure oil into the corrugated expansion pipe, and can realize the one-to-one radial pressing of the copper bushing, so that the pressure between the copper bushing and the electrode is uniform. The outer cooling jacket of the corrugated pipe is cooled by casting T2. There are 8 copper bushings and 8 corrugated pipes on each phase of the electrode. The copper bushing and the conductive copper pipe are made of T2. The rated current density of the conductive copper pipe is ≤3.0 A / mm², and the copper pipe of Φ75×15 mm is selected. The pressure ring is made of forged T2 copper-silver alloy material. The water-cooled protection screen is composed of a 06Cr18NI11Ti water-cooled structure and is made in 8 pieces. Between the water-cooled protection screen and the electrode, dense aluminosilicate ceramic fiber felt is filled. The main function of the electrode cooling water system is to send the external cooling water from the cooling water distributor to the parts that need to be cooled at the lower part of the electrode. The internal connecting rubber hose of the holder is a threaded rubber hose, and the connection with the water distributor is made by using a heat-insulating rubber hose. Each phase of the copper pressure ring is made in 8 pieces, and each phase of the upper protection screen is made in 8 pieces. The circulating water pipe of the holder is made of Q235. The holding cylinder at the position of the conductive copper pipe is made of 06Cr19Ni10 material (500 mm higher than the position of the conductive copper pipe). The thickness of the lower holding cylinder is 14 mm. The water-cooled cable has a specification of 2800 mm² and a length of about 2.5 meters. The current density at the maximum current is about 2.68 A / mm².

[0040] The 36 MVA ferrosilicon manganese all-closed submerged arc DC submerged arc furnace of this embodiment combines the self-baking electrode and the furnace cover sealing design to reduce the oxidation loss of the electrode and reduce the oxygen content on the furnace surface to inhibit the combustion of CO in the furnace.

[0041] In a specific embodiment, please refer to Figure 2 , Figure 2 FIG. is a schematic circuit diagram of a variable voltage rectifier device of a 36 MVA ferrosilicon manganese all-closed submerged arc DC submerged arc furnace provided by an embodiment of the present invention. The input end of the transformer bank 21 is connected to the power supply 20, and the output ends are respectively connected to the first rectifier cabinet 22 and the second rectifier cabinet 23. The first output end of the first rectifier cabinet 22 and the first output end of the second rectifier cabinet 23 are connected to the first electrode 31, and the second output end of the first rectifier cabinet 22 and the second output end of the second rectifier cabinet 23 are connected to the second electrode 32. Among them, the polarities of the first electrode 31 and the second electrode 32 are opposite.

[0042] In a specific embodiment, please refer to Figure 3 , Figure 3It is a schematic diagram of the transformer bank of a 36MVA manganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace provided by an embodiment of the present invention. The variable voltage rectifying device 2 includes: a transformer bank 21, a first rectifying cabinet 22, and a second rectifying cabinet 23. The transformer bank 21 includes: a voltage regulating transformer 211, a first rectifying transformer 212, and a second rectifying transformer 213. The input end of the voltage regulating transformer 211 is connected to the power supply 20, the output end of the voltage regulating transformer 211 is connected to the first rectifying transformer 212 and the second rectifying transformer 213, the first rectifying transformer 212 is connected to the first rectifying cabinet 22, and the second rectifying transformer 213 is connected to the second rectifying cabinet 23.

[0043] In a specific embodiment, both the first rectifying cabinet 22 and the second rectifying cabinet 23 include a rectifying circuit, and the number of thyristors on each rectifying arm of the rectifying circuit is determined according to the rated DC current and DC voltage output by the variable voltage rectifying device.

[0044] In a specific embodiment, the rectifying circuit is a double reverse star rectifying circuit, and the thyristors arranged on the same rectifying arm have a preset forward volt-ampere characteristic curve.

[0045] The voltage regulating transformer has a three-phase three-column iron core structure, and the rectifying transformer has two three-phase five-column iron core structures with full inclined joints; the iron core assembly is a multi-stage stepped joint, non-punched, and a TENAX polyester tape is used for lashing and a pull plate structure. The iron core clamp has sufficient strength and good clamp insulation. The iron core and the fuel tank adopt an upper and lower double positioning structure, and the iron core is reliably grounded through the clamp to the fuel tank. The iron core material is selected as high-quality cold-rolled grain-oriented silicon steel sheet 30Q120, with a low magnetic density design, so that the product has excellent no-load performance. Low loss performance. The coil is wound tightly, and insulation is added at the wire transposition. Several line segments at the end of the coil are transversely tied to improve the strength of the coil. The pads on the transformer coil are made of high-density cardboard, and the coil adopts a kerosene vapor drying process. When the body is assembled, a hydraulic jack is used to compress the coil so that the coil compression force reaches the designed specified value. The coil adopts a structure of internal and external support bars and is firmly tied with a heat-shrinkable tape. The support bars and pads are arranged vertically and evenly, and auxiliary support bars are added to ensure the stability of the coil and improve the short-circuit resistance ability. The wire insulation is enhanced insulation, and the insulation assembly between windings adopts a thin paper tube + small oil gap + formed hard corner ring structure to improve the insulation strength and mechanical strength.

[0046] The lead connection of the voltage regulating transformer adopts a cold pressing method; its advantages are: 1) There are no welding points inside the transformer, ensuring the cleanliness of the transformer body. 2) The processability is good, and the mechanical force caused by coil vibration can be reduced. 3) The current distribution from the transformer coil to the copper bar is more uniform, reducing the circulating current loss between copper bars.

[0047] The AC busbar outgoing copper bars are led out from the middle lower part on one side in the long axis direction of the transformer, with 12 bars for each core body. The DC busbar outgoing copper bars are led out from the middle cover of the transformer in the long axis direction, adopting a "single-row linear or double-row arranged structure". At the outgoing part of the large-current outgoing terminal, a large-area anti-magnetic stainless steel plate is used for magnetic isolation to reduce eddy current loss.

[0048] For each phase on the output side of the regulating transformer, a set of current transformers for measurement and protection is provided. The secondary current of the current transformer is 5A, and the accuracy of the transformer is 0.5 level. The secondary side terminals of the current transformer are led out to the current transformer terminal box for external wiring.

[0049] The transformer oil tank adopts a bell-type design with a core-free structure. Anti-loosening measures are taken at both the top and bottom of the core body to ensure that the transformer has no displacement and does not require core lifting after arriving at the site. A manhole is provided near the on-load tap-changer on the oil tank for easy installation and maintenance. There are at least two manholes for each transformer, and it is possible to enter the interior of the transformer without lifting the cover. One oil sampling valve is provided at the lower part of the oil tank. A ladder is set on the transformer oil tank, and the position of the ladder is convenient for taking gas samples and observing the gas relay. A manhole is provided at the on-load tap-changer for on-site maintenance. The main material of the oil tank is Q235.

[0050] There are enough number and strength of support points, lifting points and traction points on the transformer oil tank. A sufficiently large drain valve is provided at the lower part of the transformer oil tank. 90° track rollers are set on the transformer. A traction device is provided at the lower part of the oil tank. The transformer conservator adopts a capsule structure, completely isolating the transformer oil from the air. The conservator is equipped with a pointer-type oil level gauge with a live contact output; an oil filling valve, a gas release valve, a breather, a butterfly valve, etc. are also provided. The breather is installed at a position where it is easy to operate and replace the silica gel. There is a special butterfly valve between the conservator and the oil tank for easy disassembly and assembly. Its volume ensures that the oil does not overflow under the full load state at the highest ambient temperature of 40°C, and there is enough oil in the conservator when it is not put into operation at -15°C.

[0051] The transformer is equipped with a stainless steel control terminal box to collect the above protection signals. A cable connection is used between the control signal and the terminal box. There is a gap between the signal terminals and between the positive and negative terminals, and there is more than 15% spare capacity for the control terminals. The incoming line bushing of the transformer adopts an anti-pollution type bushing, fully considering the environmental pollution of slightly conductive dust in the air.

[0052] In a specific embodiment, the regulating transformer 211 includes: an on-load tap-changer, and the on-load tap-changer has a gear controller 4, and the gear controller is used to control the output voltage of the regulating transformer.

[0053] In a specific embodiment, please refer to Figure 4 , Figure 4It is a schematic diagram of the switch control of a 36MVA manganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace provided by an embodiment of the present invention. It further includes a control signal generator 5, and the control signal generator 5 is connected to the matrix switch 6. The matrix switch 6 is respectively connected to a plurality of gear controllers 4, a main and standby controller 7, a remote controller 8, and a current feedback controller 9;

[0054] The matrix switch 6 is configured to receive a control signal with a preset coding rule, so as to control the corresponding switch to be turned on or off according to the control signal with the preset coding rule. Among them, the control signal with the preset coding rule includes: a signal type field, a linkage field, and a control adjustment field.

[0055] It should be noted that for the large-scale manganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace of this embodiment, the workshop floor area is at least 20,000 square meters, and the distance between different devices is relatively large, and they are even located on different floors. In most control scenarios, generally, different devices need to be controlled in a coordinated manner, rather than simply controlling a single node or a single device. In non-emergency situations, the general requirement for the control time accuracy is relatively low. Within the equipment delay and safety control time, the remote control method is generally adopted. However, in scenarios such as when the equipment fails or equipment switching, shutdown, etc. are required, due to the problems of high delay and long trigger logic in the remote control method, precise control cannot be performed. Therefore, in this embodiment, the control is performed through a matrix switch, and by setting the corresponding control fields, the controllable range of the switch matrix is improved.

[0056] Specifically, the signal type field represents the specific device connected to the switch matrix. It should be noted that since the switch matrix may be connected to multiple devices of the same type, therefore, this signal type field is also required to distinguish devices of the same type. The linkage field represents that after the current control device is completed, the next or the next few control devices associated with the control device are automatically controlled, so as to achieve seamless control. The control adjustment field represents the specific control method, such as which switch circuit in the switch matrix is disconnected or closed, so as to control the corresponding plurality of gear controllers, main and standby controllers, remote controllers, and current feedback controllers to act. It should be noted that the control devices connected to the switch matrix can be adjusted according to the actual situation, and are not limited to the above types.

[0057] In a preferred scenario, when performing the action corresponding to the linkage field, the control signal generator is further configured to generate a control signal with a preset coding rule for linkage execution according to the action corresponding to the linkage field. When the action corresponding to the linkage field is executed normally, the control signal with the preset coding rule for linkage execution is only stored and does not trigger an action. When the action corresponding to the linkage field is executed abnormally, the control signal with the preset coding rule for linkage execution is called to be executed again. That is to say, the control signal with the preset coding rule for linkage execution is not substantially generated by an external input signal, but an internally preset execution logic. Therefore, during the execution of the linkage field, if an external control signal is received, the external control signal is preferentially executed. Correspondingly, the control signal with the preset coding rule may further include a field for distinguishing the external control signal and the internally generated signal, so that when the external control signal conflicts with the internally generated signal, the external control signal is preferentially executed.

[0058] It should be noted that since the linkage field may be associated with the next or the next few control devices, after each linkage execution is completed, the linkage field is correspondingly adjusted to make the front and back logic of the linkage control consistent.

[0059] In a specific embodiment, please refer to Figure 5 , Figure 5 which is a schematic diagram of the switch control of another 36MVA manganese-silicon alloy fully enclosed submerged arc DC submerged arc furnace provided by the embodiment of the present invention. At least a part of the switch nodes of the matrix switch 6 are further connected to the delay circuit 10, and the output end of the at least a part of the switch nodes is connected to the gear controller 4. The control signal with the preset coding rule further includes a delay signal trigger field;

[0060] The control signal generator is further configured to set the signal type field to a field for controlling the gear controller and set the linkage field to a field for controlling the remote controller when it is determined that the thyristor control angle is less than the preset angle.

[0061] In a specific embodiment, the matrix switch is further configured to control the corresponding delay circuit to be enabled when it is determined that the delay signal trigger field in the control signal with the preset coding rule is not empty.

[0062] In some scenarios that require delayed triggering, although the delayed instruction can be triggered through software control, for example, triggering a signal after a 50-second delay, in cases where high controllability is required, if there are conflicts in instruction execution, it may lead to control failure. Moreover, since the matrix switch in this embodiment interconnects multiple controlled devices, the more complex the execution logic, the worse the controllability. Therefore, an additional delay circuit is used for time delay control to avoid the influence of software logic confusion. The delay circuit of this application can be separately provided with an enable switch, which is turned on when enabling is required. After a certain delay circuit is turned on, the next time the path where the delay switch is located receives a control signal, the delay circuit triggers a delay signal by itself. During the delay stage, even if other types of control signals are received on this path, the control will not be triggered until the delay time ends and the control signal before the delay time is responded to.

[0063] In an example, when it is determined that the thyristor control angle is less than a preset angle (for example, the control angle is less than 0°), it indicates that there may be a voltage fault in the system. At this time, the signal type field is set to the field for controlling the gear controller. Since the control angle is less than 0°, time delay control is required during voltage regulation. Then, the delay circuit of the path where the gear controller is located is turned on by triggering the field with a delay signal. For example, after a 60-second delay, after the control action is completed, if on-site fault troubleshooting or alarm troubleshooting is required by relevant technical personnel, the remote controller is turned off through the linkage field and no longer receives remote control instructions to avoid control conflicts. The remote control instruction refers to the instruction received through the control signal generator, which can be, for example, a control instruction sent through the backend control network or an instruction generated by the control signal generator.

[0064] In a specific embodiment, a DC current sensor is provided at the output end of the variable voltage rectifier device, and current transformers are provided at the input ends of the first rectifier transformer and the second rectifier transformer. The DC current sensor and the current transformers are both connected to the control signal generator;

[0065] The control signal generator is further configured to, when it is determined that the feedback signal of the DC current sensor is lost or the feedback signal of the current transformer is lost, set the signal type field to the field for controlling the current feedback controller, and set the linkage field to the field for controlling the remote controller. In this embodiment, the feedback signals of the DC current sensor and the current transformers are used as the basis for judging the magnitude of the output current fluctuation by taking each other as the primary and backup. If one of the feedback signals is lost, switching and adjustment need to be performed through the field for controlling the current feedback controller. Similarly, if on-site fault troubleshooting or alarm troubleshooting is required by relevant technical personnel, the remote controller is turned off through the linkage field and no longer receives remote control instructions to avoid control conflicts.

[0066] The 36MVA ferrosilicon manganese fully enclosed submerged arc DC submerged arc furnace of this embodiment can accurately control the opening or closing of corresponding switches by receiving control signals with a preset coding rule through the combined use of a control signal generator and a matrix switch, realizing stable control of devices such as a gear controller, a main and standby controller, a remote controller, and a current feedback controller, and achieving seamless connection control of corresponding controllers through linkage fields, improving the controllability in case of faults.

[0067] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0068] In the present invention, unless otherwise clearly specified and defined, terms such as "install", "connect", "connection", "fix", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0069] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0070] Although the present application has been described in connection with various embodiments, those skilled in the art will recognize other variations of the disclosed embodiments while practicing the claimed application by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may implement several functions recited in the claims. Certain measures are recited in mutually different dependent claims, but this does not indicate that these measures cannot be combined to produce favorable results.

[0071] The above is a further detailed description of the present invention in connection with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited only to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as falling within the protection scope of the present invention.

Claims

1. A 36MVA fully enclosed submerged arc DC ferroalloy furnace for ferromanganese-silicon alloy, characterized in that, Including: A once-through boiler body and at least two sets of variable voltage rectifier devices electrically connected to the once-through boiler body; An electrode holder that mates with the output end of the variable voltage rectifier device is provided on the once-through boiler body. An electrode is provided on the electrode holder, and the output end of the variable voltage rectifier device is connected to the electrode. Among them, the once-through boiler body is sealed by a furnace cover to prevent combustion on the furnace surface, and the temperature inside the furnace is at least 4000 °C during operation. A number of through holes for the electrode to pass through are provided on the furnace cover. The electrode is a self-baking electrode. The rated direct current output by the variable voltage rectifier device is at least 70000 A, and the rated direct voltage output is at least 260 V. The variable voltage rectifier device includes: a transformer bank, a first rectifier cabinet, and a second rectifier cabinet. The transformer bank includes: a voltage regulating transformer, a first rectifier transformer, and a second rectifier transformer. The voltage regulating transformer includes: a on-load tap-changer, and the on-load tap-changer has a gear controller for controlling the output voltage of the voltage regulating transformer; It further includes a control signal generator, the control signal generator is connected to a matrix switch, and the matrix switch is respectively connected to a number of gear controllers, main and standby controllers, remote controllers, and current feedback controllers; The matrix switch is used to receive a control signal with a preset coding rule to control the corresponding switch to be turned on or off according to the control signal with the preset coding rule. Among them, the control signal with the preset coding rule includes: a signal type field, a linkage field, and a control adjustment field. The signal type field represents the specific device connected to the switch matrix. The linkage field represents that after the current control device is completed, the next or the next few control devices associated with the control device are automatically controlled. The control adjustment field represents the specific control method; When the action corresponding to the linkage field is executed, the control signal generator is further used to generate a control signal with a preset coding rule for linkage execution according to the action corresponding to the linkage field. When the action corresponding to the linkage field is executed normally, the control signal with the preset coding rule for linkage execution is only stored and does not trigger an action. When the action corresponding to the linkage field is executed abnormally, the control signal with the preset coding rule for linkage execution is called to be executed again. Correspondingly, the control signal with the preset coding rule further includes a field for distinguishing external control signals and internally generated signals, so that when there is a conflict between external control signals and internally generated signals, the external control signals are preferentially executed.

2. The 36MVA fully enclosed submerged arc DC ferrosilicon-manganese furnace according to claim 1, wherein The input end of the transformer bank is connected to a power supply, and the output ends are respectively connected to the first rectifier cabinet and the second rectifier cabinet. The first output end of the first rectifier cabinet and the first output end of the second rectifier cabinet are connected to the first electrode, and the second output end of the first rectifier cabinet and the second output end of the second rectifier cabinet are connected to the second electrode. Among them, the first electrode and the second electrode have opposite polarities.

3. The 36MVA fully enclosed submerged arc DC submerged arc furnace for ferromanganese-silicon alloy according to claim 2, characterized in that, The input end of the voltage regulating transformer is connected to the power supply, and the output end of the voltage regulating transformer is connected to the first rectifier transformer and the second rectifier transformer. The first rectifier transformer is connected to the first rectifier cabinet, and the second rectifier transformer is connected to the second rectifier cabinet.

4. The 36MVA fully enclosed submerged arc DC submerged arc furnace for ferromanganese-silicon alloy according to claim 3, characterized in that, Both the first rectifier cabinet and the second rectifier cabinet include a rectification circuit, and the number of thyristors on each rectifier arm of the rectification circuit is determined according to the rated DC current and DC voltage output by the variable voltage rectification device.

5. The 36MVA fully enclosed submerged arc DC ferroalloy furnace for ferromanganese-silicon alloy according to claim 4, characterized in that, The rectification circuit is a double reverse star rectification circuit, and the thyristors arranged on the same rectifier arm have a preset forward volt-ampere characteristic curve.

6. The 36MVA fully enclosed submerged arc DC submerged arc furnace for ferromanganese-silicon alloy according to claim 1, characterized in that, At least a part of the switching nodes of the matrix switch are further connected to a delay circuit, and the output ends of the at least a part of the switching nodes are connected to a gear controller. The control signal with the preset coding rule further includes a delay signal trigger field; The control signal generator is further configured to set the signal type field to a field for controlling the gear controller and set the linkage field to a field for controlling the remote controller when it is determined that the thyristor control angle is less than a preset angle.

7. The 36 MVA fully enclosed submerged arc DC ferroalloy furnace for ferromanganese-silicon alloy according to claim 6, characterized in that, The matrix switch is further configured to control the corresponding delay circuit to be enabled when it is determined that the delay signal trigger field in the control signal of the preset coding rule is not empty.

8. The 36MVA fully enclosed submerged arc DC ferroalloy furnace for ferromanganese-silicon alloy according to claim 1, characterized in that, A DC current sensor is provided at the output end of the variable voltage rectification device, and current transformers are provided at the input ends of the first rectifier transformer and the second rectifier transformer. The DC current sensor and the current transformers are both connected to the control signal generator; The control signal generator is further configured to set the signal type field to a field for controlling the current feedback controller and set the linkage field to a field for controlling the remote controller when it is determined that the feedback signal of the DC current sensor is lost or the feedback signal of the current transformer is lost.

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