Full-vacuum-degree oxygen blowing decarburization device and pump set automatic frequency conversion control system thereof

Abstract

The invention provides a full-vacuum-degree oxygen-blowing decarburization device and a pump set automatic frequency conversion control system thereof.The full-vacuum-degree oxygen-blowing decarburization device comprises a vacuum oxygen-blowing decarburization furnace, a steel ladle is arranged at the inner end of the vacuum oxygen-blowing decarburization furnace, a vacuum tank cover is arranged at the top end of the vacuum oxygen-blowing decarburization furnace, and a top-blowing oxygen lance is arranged at the top end of the center of the vacuum tank cover; an oxygen outlet pipe is arranged at the output end of the top blowing oxygen lance, the oxygen covering assembly is used for fully covering oxygen in the vacuum oxygen blowing decarburization furnace and comprises a sealing bearing, a rotary drum, a positioning groove, a positioning block and a linkage rod, the sealing bearing and the rotary drum are located at the outer end of the oxygen outlet pipe, and the positioning groove, the positioning block and the linkage rod are located at the inner end of the oxygen outlet pipe. A threaded rod, a threaded groove, a limiting pipe and a limiting rod which are convenient to adjust and rotate are arranged at the inner end of the rotating cylinder, and multiple sets of end pipe openings, multiple sets of oxygen conveying end pipes and a rotating groove which are convenient for oxygen conveying are arranged at the inner end of the rotating cylinder. The problems that different oxygen blowing amounts cannot be adjusted in all stages, and in the oxygen blowing process, molten steel in a steel ladle cannot react with oxygen to be subjected to uniform and rapid decarburization are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of vacuum oxygen blowing decarburization furnaces, and more particularly to an oxygen blowing decarburization device with full vacuum degree and its automatic variable frequency control system for the pump group. Background Art

[0002] VOD (Vacuum Oxygen Decarburization Device) is a crucial part in the production of low-carbon, extra-low-carbon alloy steel and stainless steel. In the technical improvement route of energy conservation, emission reduction, cost reduction and efficiency improvement, more efficient mechanical vacuum systems have been widely adopted in newly built VOD equipment. However, at present, due to the complex process of VOD equipment, such as: the large additional load brought by oxygen blowing, the uncertain range of oxygen blowing vacuum degree, and the frequent adjustment of oxygen blowing flow rate, etc., it is difficult to select a suitable mechanical pump, and the control is difficult to match, and the vacuum degree control is difficult to accurately complete. Therefore, although the mechanical vacuum system has the advantages of energy conservation and high efficiency, it is not widely used in VOD applications, and there are certain thresholds for popularization. Different from the steam jet pump system, the mechanical pump system consists of smaller single pumps. The increase in the required gas volume means an increase in the number of pumps, an increase in the installed and operating power, and a linear increase in the pump group configuration and operating costs. Therefore, it is completely and very necessary to finely adjust the overall pump group configuration according to the different oxygen blowing amounts in each stage.

[0003] In the prior art, during the use of the vacuum oxygen blowing decarburization furnace, it is impossible to adjust different oxygen blowing amounts in each stage, and during the oxygen blowing process, it is impossible to uniformly and quickly decarburize the molten steel in the ladle with oxygen; therefore, we make improvements and propose an oxygen blowing decarburization device with full vacuum degree and its automatic variable frequency control system for the pump group. Summary of the Invention

[0004] The purpose of the present invention is to address the problems that the current design of the vacuum oxygen blowing decarburization furnace cannot adjust different oxygen blowing amounts in each stage, and during the oxygen blowing process, it cannot uniformly and quickly decarburize the molten steel in the ladle with oxygen.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] An oxygen blowing decarburization device with full vacuum degree and its automatic variable frequency control system for the pump group to improve the above problems.

[0007] Specifically, this application is as follows:

[0008] An oxygen blowing decarburization device with full vacuum degree, including a vacuum oxygen blowing decarburization furnace, a ladle is provided at the inner end of the vacuum oxygen blowing decarburization furnace, a vacuum tank cover is provided at the top of the vacuum oxygen blowing decarburization furnace, a top oxygen blowing lance is provided at the central top of the vacuum tank cover, an oxygen outlet pipe is provided at the output end of the top oxygen blowing lance, and further includes:

[0009] Oxygen covering component, used for full coverage of oxygen in a vacuum oxygen blowing decarburization furnace. The oxygen covering component includes a sealing bearing and a rotating cylinder located at the outer end of the oxygen outlet pipe, a positioning groove, a positioning block, and a linkage rod located at the inner end of the oxygen outlet pipe. The inner end of the rotating cylinder is provided with a threaded rod, a threaded groove, a limiting pipe, and a limiting rod for facilitating rotation adjustment. The inner end of the rotating cylinder is provided with multiple groups of end nozzles, multiple groups of oxygen delivery end pipes, and a rotating groove for facilitating oxygen delivery. The lower end of the linkage rod is provided with a plug rod, the surface of the plug rod is provided with an annular toothed cylinder, the outer end of the annular toothed cylinder is provided with linkage teeth, the linkage teeth are wrapped around the outer end of the oxygen delivery end pipe, and both ends of the oxygen delivery end pipe are connected with linkage bearings. A delivery ring is connected between two groups of oxygen delivery end pipes through the linkage bearings.

[0010] As a preferred technical solution of the present application, both ends of the sealing bearing are fixedly connected to the oxygen outlet pipe and the rotating cylinder respectively. The positioning block moves up and down along the positioning groove. The linkage rod is fixedly connected to the central lower end of the positioning block. The positioning block is a combination of an outer ring, an inner cylinder, and a cross bar connecting the two. The positioning groove is embedded in the inner surface of the oxygen outlet pipe, and the positioning groove is slidably connected to the positioning block.

[0011] As a preferred technical solution of the present application, there is a fixed connection between the center of the positioning block and the linkage rod, a fixed connection between the lower end of the linkage rod and the plug rod, a linkage rod is fixed at the lower end of the plug rod, a fixed connection between the lower end of the linkage rod and the threaded rod, and the outer end of the threaded rod is threadedly connected to the threaded groove. The threaded groove is embedded in the inner surface of the lower end of the rotating cylinder.

[0012] As a preferred technical solution of the present application, each group of end nozzles penetrates through the inner surface of the rotating cylinder. There is an inclined pipe between the end nozzle and the delivery ring. The delivery ring is movably connected to the oxygen delivery end pipe through a linkage bearing. The outer side of the rotating end of the oxygen delivery end pipe is fixedly connected to the linkage teeth, the outer end of the linkage teeth is meshed with the annular toothed cylinder, the annular toothed cylinder is fixed to the outer end of the plug rod, and each group of oxygen delivery end pipes is movably connected to the rotating cylinder through the rotating groove.

[0013] As a preferred technical solution of the present application, the upper end of the annular toothed cylinder is provided with an annular plate, the upper end of the annular plate is provided with an inner ring groove, the outer end of the annular plate is provided with a linkage push plate, the outer end of the linkage push plate is provided with a linkage push groove, the linkage push groove is embedded in the inner end of the rotating cylinder, the linkage push plate and the linkage push groove are correspondingly connected, the number of linkage push plates is the same as the number of oxygen delivery end pipes, the linkage push groove is connected through to the end nozzle, the linkage push groove is slidably connected to the linkage push plate, multiple groups of linkage push plates are all fixedly connected to the annular plate, and there is a space for the up and down movement of the annular plate at the top end of the annular toothed cylinder.

[0014] As a preferred technical solution of the present application, a limiting tube is provided at the central inner end of the threaded rod. A limiting rod is provided at the inner end of the limiting tube. A rotating plate is provided at the lower end of the limiting rod. A spring is provided at the upper end of the rotating plate. The limiting tube penetrates through the central inner end of the threaded rod. The limiting tube is slidably connected with the limiting rod. The lower end of the limiting rod is fixedly connected with the rotating plate. The rotating plate rotates along the inner surface of the lower end of the rotating cylinder. The spring is wrapped around the outer end of the limiting rod. The upper and lower ends of the spring are respectively fixed at the lower end of the threaded rod and the upper end of the rotating plate.

[0015] As a preferred technical solution of the present application, an outer ring groove is provided at the outer end of the rotating cylinder. A positioning ring is provided at the inner end of the outer ring groove. A plurality of support rods are provided at the outer end of the positioning ring. The outer ring groove is embedded in the outer end of the rotating cylinder, and the position of the outer ring groove is higher than the position of the rotating groove. The outer ring groove is movably connected with the positioning ring. The outer end of the positioning ring is fixedly connected with the support rods. The plurality of support rods are arranged in an equidistant annular pattern along the positioning ring.

[0016] A pump group automatic frequency conversion control system for a full vacuum oxygen blowing and decarburizing device. The pump assembly 4 includes at least one four-stage mechanical pump, a three-stage mechanical pump group, a plurality of groups of conveying pipelines 5 and valve instruments. The three-stage mechanical pump group includes at least one three-stage mechanical pump, at least one two-stage mechanical pump and at least one one-stage mechanical pump. The four-stage mechanical pump, at least one three-stage mechanical pump, at least one two-stage mechanical pump and at least one one-stage mechanical pump are connected in series between levels through the conveying pipeline 5 in sequence. A group of standby pumps are respectively arranged in parallel for at least one three-stage mechanical pump, at least one two-stage mechanical pump and at least one one-stage mechanical pump through the conveying pipeline 5. The valve instruments at least include a bypass valve, a vacuum main valve and a pre-pump valve at each stage in the three-stage mechanical pump group.

[0017] As a preferred technical solution of the present application, the pumps put into use in the automatic frequency conversion control system among the four-stage mechanical pump, three-stage mechanical pump, two-stage mechanical pump and one-stage mechanical pump are the pumps in use, and the pumps with faults in use among the four-stage mechanical pump, three-stage mechanical pump, two-stage mechanical pump and one-stage mechanical pump are the pumps out of use.

[0018] As a preferred technical solution of the present application, the operation steps are as follows:

[0019] Step 1: The four-stage mechanical pump operates at full frequency. Sequentially open the pre-pump valves at each stage in the three-stage mechanical pump group except for the standby pumps. Open the bypass valve and the vacuum main valve. After all the above valves are opened, start the vacuum pumping timing and record the pressure value at the inlet of the pump assembly 4.

[0020] Step 2: When the vacuum degree drops, when it is above 0.8 kPa, the full vacuum degree on the pump side is used as the standard; when it is below 0.8 kPa, the high vacuum degree on the pump side is used as the standard; when the vacuum degree rises, when it is below 1 kPa, the high vacuum degree on the pump side is used as the standard; when it is above 1 kPa, the full vacuum degree on the pump side is used as the standard.

[0021] Step 3: Adjust the frequency of each stage of the pump in the pump assembly 4 according to the pressure value at the inlet of the pump assembly 4, and compare according to the magnitude of the actual frequency sum and the target frequency sum:

[0022] When the actual frequency sum is less than the target frequency sum, increase the frequency of the pump with the minimum current among all the in-service pumps, and poll once per unit time;

[0023] When the actual frequency sum is greater than the target frequency sum, decrease the frequency of the pump with the maximum current among all the in-service pumps, and poll once per unit time.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] In the solution of the present application:

[0026] 1. The oxygen delivery is comprehensively and stably set: Each component of the oxygen coverage assembly operates in coordination. The rotating drum rotates horizontally and the oxygen delivery end pipe rotates vertically, so that oxygen can be delivered to the inner end of the ladle, ensuring that the oxygen is sprayed comprehensively and stably in the ladle. The stable and comprehensive oxygen delivery method can accelerate the decarburization progress of the molten steel in the ladle. When the oxygen supply amount decreases, the spring in the rotating drum bounces upward, facilitating the upward movement and recovery of the plug rod, realizing a certain degree of automatic adjustment.

[0027] 2. It can work synchronously according to the variable frequency control system when the working frequency of each stage is reached, and be refreshed within the unit time, and can save more energy and reduce energy consumption to a greater extent during the oxygen blowing decarburization process, ensuring the high efficiency and high yield of the molten steel oxygen blowing decarburization. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of an oxygen blowing decarburization device with full vacuum degree and its automatic variable frequency control system for the pump group provided by the present application;

[0029] Figure 2 It is a schematic diagram of the overall structure of the vacuum oxygen blowing decarburization furnace of an oxygen blowing decarburization device with full vacuum degree and its automatic variable frequency control system for the pump group provided by the present application;

[0030] Figure 3 It is an oxygen blowing decarburization device with full vacuum degree and its automatic variable frequency control system for the pump group provided by the present application Figure 2 of the side sectional structure schematic diagram;

[0031] Figure 4 It is an oxygen blowing decarburization device with full vacuum degree and its automatic variable frequency control system for the pump group provided by the present application Figure 3 of the enlarged structure schematic diagram of A;

[0032] Figure 5 It is an oxygen blowing decarburization device with full vacuum degree and its automatic variable frequency control system for the pump group provided by the present applicationFigure 4 Front view;

[0033] Figure 6 A full-vacuum oxygen blowing decarburization device and its pump group automatic frequency conversion control system provided by this application Figure 2 Schematic diagram of the front sectional structure;

[0034] Figure 7 A full-vacuum oxygen blowing decarburization device and its pump group automatic frequency conversion control system provided by this application Figure 6 Enlarged schematic diagram of B in;

[0035] Figure 8 Enlarged schematic diagram of the upper cross-section of the oxygen delivery end pipe of a full-vacuum oxygen blowing decarburization device and its pump group automatic frequency conversion control system provided by this application;

[0036] Figure 9 A full-vacuum oxygen blowing decarburization device and its pump group automatic frequency conversion control system provided by this application Figure 6 Explosion structure diagram of the transfer cylinder and the plug rod;

[0037] Figure 10 A full-vacuum oxygen blowing decarburization device and its pump group automatic frequency conversion control system provided by this application Figure 10 Front view of the explosion part;

[0038] Figure 11 Double-sided sectional structure diagram of the vacuum oxygen blowing decarburization furnace of a full-vacuum oxygen blowing decarburization device and its pump group automatic frequency conversion control system provided by this application;

[0039] Figure 12 A full-vacuum oxygen blowing decarburization device and its pump group automatic frequency conversion control system provided by this application Figure 11 Enlarged schematic diagram of C in;

[0040] Figure 13 Schematic diagram of the pump group automatic frequency conversion control system of a full-vacuum oxygen blowing decarburization device and its pump group automatic frequency conversion control system provided by this application.

[0041] Labels in the figure:

[0042] 1. Vacuum oxygen decarburization furnace; 2. Top oxygen lance; 3. Ladle; 4. Pump assembly; 5. Delivery pipeline; 6. Vacuum tank cover; 7. Support rod; 8. Positioning ring; 9. Outer ring groove; 10. Sealed bearing; 11. Oxygen outlet pipe; 12. Positioning groove; 13. Positioning block; 14. Linking rod; 15. Plug rod; 16. Inner ring groove; 17. Linking push plate; 18. Linking push groove; 19. Oxygen delivery end pipe; 20. Delivery ring; 21. End pipe orifice; 22. Ring plate; 23. Linking bearing; 24. Rotating groove; 25. Ring-shaped toothed cylinder; 26. Linking tooth; 27. Limiting pipe; 28. Limiting rod; 29. Threaded rod; 30. Threaded groove; 31. Rotating cylinder; 32. Rotating plate; 33. Spring. Detailed implementation mode

[0043] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention.

[0044] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents some embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention. It should be noted that, without conflict, the embodiments in the present invention and the features and technical solutions in the embodiments may be combined with each other.

[0045] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0046] As Figures 1 - 12 shown, this implementation mode provides an oxygen blowing decarburization device with full vacuum degree, including a vacuum oxygen decarburization furnace 1. A ladle 3 is arranged at the inner end of the vacuum oxygen decarburization furnace 1. A vacuum tank cover 6 is arranged at the top of the vacuum oxygen decarburization furnace 1. A top oxygen lance 2 is arranged at the central top of the vacuum tank cover 6. An oxygen outlet pipe 11 is arranged at the output end of the top oxygen lance 2. It further includes:

[0047] Oxygen covering assembly, used for full coverage of oxygen in the vacuum oxygen blowing decarburization furnace 1. The oxygen covering assembly includes a sealing bearing 10 and a rotating cylinder 31 located at the outer end of the oxygen outlet pipe 11, a positioning groove 12, a positioning block 13 and a linkage rod 14 located at the inner end of the oxygen outlet pipe 11. The inner end of the rotating cylinder 31 is provided with a threaded rod 29, a threaded groove 30, a limiting pipe 27 and a limiting rod 28 for facilitating adjustment of rotation. The inner end of the rotating cylinder 31 is provided with multiple groups of end nozzles 21, multiple groups of oxygen delivery end pipes 19 and a rotating groove 24 for facilitating oxygen delivery. The lower end of the linkage rod 14 is provided with a plug rod 15. The surface of the plug rod 15 is provided with an annular tooth cylinder 25. The outer end of the annular tooth cylinder 25 is provided with linkage teeth 26. The linkage teeth 26 are wrapped around the outer end of the oxygen delivery end pipe 19. Both ends of the oxygen delivery end pipe 19 are connected with a linkage bearing 23. A delivery ring 20 is connected between the two groups of oxygen delivery end pipes 19 through the linkage bearing 23.

[0048] Both ends of the sealing bearing 10 are fixedly connected to the oxygen outlet pipe 11 and the rotating cylinder 31 respectively. The positioning block 13 moves up and down along the positioning groove 12. The linkage rod 14 is fixed to the central lower end of the positioning block 13. The positioning block 13 is a combination of an outer ring, an inner cylinder and a cross bar connecting the two. The positioning groove 12 is embedded in the inner surface of the oxygen outlet pipe 11. The positioning groove 12 is slidably connected to the positioning block 13.

[0049] There is a fixed connection between the center of the positioning block 13 and the linkage rod 14, a fixed connection between the lower end of the linkage rod 14 and the plug rod 15, a plug rod 15 is fixed to the lower end of the linkage rod 14, a fixed connection between the lower end of the linkage rod 14 and the threaded rod 29, and the outer end of the threaded rod 29 is threadedly connected to the threaded groove 30. The threaded groove 30 is embedded in the inner surface of the lower end of the rotating cylinder 31.

[0050] Each group of end nozzles 21 penetrates through the inner surface of the rotating cylinder 31. There is an inclined pipe between the end nozzle 21 and the delivery ring 20. The delivery ring 20 is movably connected to the oxygen delivery end pipe 19 through the linkage bearing 23. The outer side of the rotating end of the oxygen delivery end pipe 19 is fixedly connected to the linkage teeth 26. The outer end of the linkage teeth 26 is meshed with the annular tooth cylinder. The annular tooth cylinder is fixed to the outer end of the plug rod 15. Each group of oxygen delivery end pipes 19 is movably connected to the rotating cylinder 31 through the rotating groove 24.

[0051] The upper end of the annular tooth cylinder 25 is provided with an annular plate 22. The upper end of the annular plate 22 is provided with an inner ring groove 16. The outer end of the annular plate 22 is provided with a linkage push plate 17. The outer end of the linkage push plate 17 is provided with a linkage push groove 18. The linkage push groove 18 is embedded in the inner end of the rotating cylinder 31. The linkage push plate 17 and the linkage push groove 18 are correspondingly connected. The number of the linkage push plates 17 is the same as the number of the oxygen delivery end pipes 19. The linkage push groove 18 is connected through to the end nozzle 21. The linkage push groove 18 is slidably connected to the linkage push plate 17. Multiple groups of linkage push plates 17 are all fixedly connected to the annular plate 22. There is a space for the up and down movement of the annular plate 22 at the top end of the annular tooth cylinder.

[0052] A limiting tube 27 is provided at the central inner end of the threaded rod 29. A limiting rod 28 is provided at the inner end of the limiting tube 27. A rotating plate 32 is provided at the lower end of the limiting rod 28. A spring 33 is provided at the upper end of the rotating plate 32. The limiting tube 27 penetrates through the central inner end of the threaded rod 29. The limiting tube 27 is slidably connected with the limiting rod 28. The lower end of the limiting rod 28 is fixedly connected with the rotating plate 32. The rotating plate 32 rotates along the inner surface of the lower end of the rotating cylinder 31. The spring 33 is wrapped around the outer end of the limiting rod 28. The upper and lower ends of the spring 33 are respectively fixed at the lower end of the threaded rod 29 and the upper end of the rotating plate 32.

[0053] The spring 33 in the vacuum oxygen decarburization furnace 1 is made of high chromium nickel alloy spring 33 steel, which can ensure the stability of elasticity and material in high temperature environment.

[0054] An outer ring groove 9 is provided at the outer end of the rotating cylinder 31. A positioning ring 8 is provided at the inner end of the outer ring groove 9. A plurality of support rods 7 are provided at the outer end of the positioning ring 8. The outer ring groove 9 is embedded in the outer end of the rotating cylinder 31, and the position of the outer ring groove 9 is higher than that of the rotating groove 24. The outer ring groove 9 is movably connected with the positioning ring 8. The outer end of the positioning ring 8 is fixedly connected with the support rods 7. The plurality of support rods 7 are arranged in an equidistant annular pattern along the positioning ring 8.

[0055] Connection and transmission components: The oxygen outlet pipe 11 and the rotating cylinder 31 are connected by a sealed bearing 10; the positioning block 13 slides along the positioning groove 12 and is connected with the linkage rod 14. The linkage rod 14 drives the plug rod 15. The plug rod 15 cooperates with the threaded groove 30 on the rotating cylinder 31 through the threaded rod 29 to realize the rotation of the rotating cylinder 31.

[0056] Oxygen delivery components: The rotating cylinder 31 is provided with a plurality of end nozzles 21, oxygen delivery end pipes 19 and rotating grooves 24. The end nozzles 21 and the delivery ring 20 are connected by an inclined pipe. The oxygen delivery end pipes 19 are movably connected with the delivery ring 20 and the rotating cylinder 31 through linkage bearings 23. The outer end of the oxygen delivery end pipe 19 meshes with the linkage teeth 26 on the annular toothed cylinder.

[0057] Auxiliary control components: A ring plate 22 is provided at the upper end of the annular toothed cylinder. The ring plate 22 is connected with the linkage push plate 17. The linkage push plate 17 is slidably connected with the linkage push groove 18 in the rotating cylinder 31; a limiting tube 27 and a limiting rod 28 are provided at the inner end of the threaded rod 29. A rotating plate 32 and a spring 33 are provided at the lower end of the limiting rod 28.

[0058] Comprehensive and stable oxygen delivery: Through the coordinated operation of each component of the oxygen coverage assembly, including the rotation of the rotating cylinder 31 on the horizontal plane and the rotation of the oxygen delivery end pipe 19 on the vertical plane, oxygen can be delivered to the inner end of the ladle 3, ensuring that the oxygen is sprayed comprehensively and stably in the ladle 3.

[0059] Accelerate the decarburization progress: The stable and comprehensive oxygen delivery method can accelerate the decarburization progress of the molten steel in the ladle 3.

[0060] Automatic adjustment function: When the oxygen supply decreases, the spring 33 in the rotary cylinder 31 bounces upward, facilitating the upward movement and recovery of the plug rod 15, achieving a certain degree of automatic adjustment.

[0061] To ensure the stable and comprehensive injection of oxygen in the ladle 3 and accelerate the decarburization progress of the molten steel in the ladle 3, first connect the conveying pipeline 5 with the top oxygen lance 2 to ensure the stable conveyance of oxygen. Before conveyance, an appropriate amount of molten steel to be decarburized is added to the ladle 3 in the vacuum oxygen decarburization furnace 1, the vacuum tank cover 6 is closed, and oxygen is injected into the oxygen outlet pipe 11 from the top oxygen lance 2. The movement of oxygen in the oxygen outlet pipe 11 pushes the positioning block 13 to move downward along the positioning groove 12, and the positioning rod pushes the plug rod 15 connected to the linkage rod 14 to move downward. The threaded rod 29 at the lower end of the plug rod 15 drives the operation of the thread groove 30. Due to the contact movement between the threaded rod 29 and the thread groove 30, and under the action of the force that the threaded rod 29 is only limited (by the limiting pipe 27 and the limiting rod 28) to move up and down, it is ensured that the thread groove 30 contacts the thread on the threaded rod 29, thereby driving the rotary cylinder 31 to rotate at the outer end of the oxygen outlet pipe 11 along the sealed bearing 10. During this process, while the plug rod 15 moves downward, it also drives the linkage push plate 17 connected to the ring plate 22 to move downward along the linkage groove 18, exposing the end pipe orifice 21. When the end pipe orifice 21 is opened, the oxygen conveyed by the pump assembly 4 can enter the conveying ring 20 through multiple end pipe orifices 21 and be conveyed to the vacuum oxygen decarburization furnace 1 through the oxygen conveying end pipe 19 connected by the linkage bearing 23. At the same time, the annular gear cylinder 25 is connected to the linkage teeth 26 at the outer end of the oxygen conveying end pipe 19 while moving downward. The meshing of the linkage teeth 26 can drive the oxygen conveying end pipe 19 to rotate up and down in the vertical plane along the inner end of the rotating groove 24 through the linkage bearing 23, and the external rotary cylinder 31 also rotates synchronously in the horizontal plane. During the rotation process, it is convenient to convey oxygen to the inner end of the ladle 3 and ensure comprehensiveness and stability, facilitating the rapid decarburization of the molten steel. Moreover, during the process of decreasing oxygen supply, the spring 33 located in the rotary cylinder 31 bounces upward, facilitating the upward movement and recovery of the plug rod 15.

[0062] Process flow of the vacuum oxygen decarburization furnace 1:

[0063] (1) The bridge crane hoists the ladle 3 that has been processed by the electric furnace into the vacuum oxygen decarburization furnace 1. The vehicle of the vacuum tank cover 6 drives to the vacuum treatment station, and at the same time, temperature measurement and sampling are carried out. Then the vacuum tank cover 6 descends to the vacuum oxygen decarburization furnace 1 and the vacuum tank cover 6 is closed, and the vacuum pump is started to evacuate.

[0064] (2) When the vacuum degree reaches 20 kPa, oxygen blowing for decarburization starts and is carried out in 5 stages. When the carbon content in the molten steel meets the requirements, oxygen blowing stops, and high-vacuum carbon deoxidation treatment, alloy addition, reducing agent addition, and high-vacuum reduction treatment are carried out.

[0065] (3) After the treatment is completed, close the main vacuum valve, break the vacuum state, lift the ladle cover, move the vehicle of the vacuum tank cover 6 to the standby position, measure the temperature and take samples, make fine adjustments to the alloy (wire feeding), stop blowing argon, and use the overhead crane to lift the ladle 3 to the casting station.

[0066] The five stages of oxygen blowing are as follows:

[0067] (1) Pre-blowing: 20 kPa

[0068] (2) Main blowing: 16 kPa

[0069] (3) Dynamic oxygen blowing 1: 13.3 kPa

[0070] (4) Dynamic oxygen blowing 2: 10.6 kPa

[0071] (5) Dynamic oxygen blowing 3: 8 - 6.7 kPa

[0072] Oxygen blowing flow rate: 400 - 1800 Nm 3 / h, with an average of 700 Nm 3 / h.

[0073] A pump unit automatic frequency conversion control system for an oxygen blowing and decarburization device with full vacuum degree. The pump assembly 4 includes at least one four-stage mechanical pump, a three-stage mechanical pump group, multiple groups of conveying pipelines 5, and valve instruments. The four-stage mechanical pump is a screw pump. The three-stage mechanical pump group includes at least one three-stage mechanical pump, at least one two-stage mechanical pump, and at least one one-stage mechanical pump. The four-stage mechanical pump, at least one three-stage mechanical pump, at least one two-stage mechanical pump, and at least one one-stage mechanical pump are connected in series between levels through the conveying pipeline 5 in sequence. At least one three-stage mechanical pump, at least one two-stage mechanical pump, and at least one one-stage mechanical pump are respectively provided with a group of standby pumps in parallel through the conveying pipeline 5. The valve instruments at least include a bypass valve, a main vacuum valve, and a pre-pump valve at each level in the three-stage mechanical pump group.

[0074] The four-stage mechanical pump, three-stage mechanical pump, two-stage mechanical pump, and one-stage mechanical pump that are put into use in the automatic frequency conversion control system are the pumps in operation. The four-stage mechanical pump, three-stage mechanical pump, two-stage mechanical pump, and one-stage mechanical pump that are put into use and malfunction are the pumps out of service.

[0075] For the four-stage mechanical pump, three-stage mechanical pump, two-stage mechanical pump, and one-stage mechanical pump, at each level, the pump components are connected in parallel so that when one pump component malfunctions (the pump out of service), the standby pump at that level can be pushed into emergency response at that level, so that the malfunctioning pump component (the pump out of service) can be repaired in time without affecting the overall frequency conversion control process.

[0076] The operation steps are as follows:

[0077] Step 1: The four-stage mechanical pump runs at full frequency. Sequentially open the pre-valves of each stage in the three-stage mechanical pump group except the standby pump, open the bypass valve and the main vacuum valve. After all the above valves are opened, start the vacuum pumping timing and record the pressure value at the inlet of the pump assembly 4;

[0078] Step 2: When the vacuum degree drops, use the full vacuum degree on the pump side as the standard above 0.8 kPa, and use the high vacuum degree on the pump side as the standard below 0.8 kPa; when the vacuum degree rises, use the high vacuum degree on the pump side as the standard below 1 kPa, and use the full vacuum degree on the pump side as the standard above 1 kPa;

[0079] Step 3: According to the pressure value at the inlet of the pump assembly 4, adjust the frequency of each stage of the pump in the pump assembly 4, and compare according to the size of the calculated actual frequency sum and the target frequency sum (the calculation of the actual frequency sum and the target frequency sum uses the frequency calculation method of the existing technology. In this case, as long as the comprehensive calculation of the collected actual frequency data can be realized):

[0080] When the actual frequency sum is less than the target frequency sum, increase the frequency of the pump with the smallest current among all the in-use pumps, and poll once per unit time;

[0081] When the actual frequency sum is greater than the target frequency sum, decrease the frequency of the pump with the largest current among all the in-use pumps, and poll once per unit time.

[0082] One embodiment of the automatic variable frequency control system for the pump group:

[0083] (1) The mechanical pump runs at full frequency. Sequentially open all the pre-valves of the four-stage pumps, the pre-valves of the three-stage pumps, the pre-valves of the two-stage pumps, the pre-valves of the one-stage pumps, the bypass valve and the main vacuum valve except the standby pump. After all the above valves are fully opened, start the vacuum pumping timing;

[0084] (2) Denote the inlet pressure of the pump group as P0 (unit: kPa):

[0085] When the vacuum degree drops, if P0 > 0.8 kPa, use the full vacuum degree on the pump side as the standard; if P0 < 0.8 kPa, use the high vacuum degree on the pump side as the standard;

[0086] When the vacuum degree rises, if P0 < 1 kPa, use the high vacuum degree on the pump side as the standard; if P0 > 1 kPa, use the full vacuum degree on the pump side as the standard.

[0087] Adjust the pump group frequency according to the following requirements:

[0088] (1) Four-stage mechanical pump: Run at normal full frequency;

[0089] (2) Three-stage mechanical pump:

[0090] ① When clicking to start the vacuum, starting from 3-1, the three-stage mechanical pumps are sequentially started up to 25Hz (automatically skipping the deactivated pumps and standby pumps). When starting up to above 5Hz, the pumps start to count the actual frequency sum and start frequency modulation;

[0091] ② When the actual frequency sum < the target frequency sum, the pump with the minimum current among all the in-use pumps is frequency increased, and polling is performed every 5s;

[0092] ③ When the actual frequency sum is greater than the target frequency sum, the pump with the maximum current among all the in-use pumps is frequency decreased, and polling is performed every 5s.

[0093] (3) Secondary mechanical pumps:

[0094] ① When P0 is less than 65kPa, starting from pump 2-1, the secondary mechanical pumps are sequentially started up to 8Hz (automatically skipping the deactivated pumps and standby pumps). When starting up to above 5Hz, the pumps start to count the actual frequency sum and start frequency modulation;

[0095] ② When the actual frequency sum is less than the target frequency sum, the pump with the minimum current among all the in-use pumps is frequency increased, and polling is performed every 5s;

[0096] ③ When the actual frequency sum is greater than the target frequency sum, the pump with the maximum current among all the in-use pumps is frequency decreased, and polling is performed every 5s.

[0097] (4) Primary mechanical pumps:

[0098] ① When P0 is less than 65kPa, starting from pump 1-1, the primary mechanical pumps are sequentially started up to 2Hz (automatically skipping the deactivated pumps and standby pumps). When starting up to above 5Hz, the pumps start to count the actual frequency sum and start frequency modulation;

[0099] ② When the actual frequency sum is less than the target frequency sum, the pump with the minimum current among all the in-use pumps is frequency increased, and polling is performed every 5s;

[0100] ③ When the actual frequency sum is greater than the target frequency sum, the pump with the maximum current among all the in-use pumps is frequency decreased, and polling is performed every 5s.

[0101] During the operation stage of the pump group automatic variable frequency control system, the present application of the pump assembly 4 adopts an automatic control logic (prior art) when in use:

[0102] Place the ladle 3 inside the vacuum oxygen decarburization furnace 1, install the vacuum tank cover 6 at the top, position the top oxygen lance 2 at the center of the top of the vacuum tank cover 6, connect its output end to the oxygen outlet pipe 11, complete the installation of each component of the oxygen covering assembly, fix both ends of the sealed bearing 10 to the oxygen outlet pipe 11 and the rotary drum 31 respectively, connect the positioning block 13 to the inner surface of the oxygen outlet pipe 11 in a sliding manner along the positioning groove 12, fix the linkage rod 14 to the lower center of the positioning block 13, fix the plug rod 15 to the lower end of the linkage rod 14, fix the threaded rod 29 to the linkage rod 14 at the lower end of the plug rod 15 and thread it into the threaded groove 30 on the inner surface of the lower end of the rotary drum 31, connect each oxygen delivery end pipe 19 to the delivery ring 20 through the linkage bearing 23, and engage the linkage teeth 26 with the annular toothed cylinder, etc., to ensure the normal operation of the oxygen covering assembly. At the same time, the pump assembly 4 is connected to the vacuum oxygen decarburization furnace 1 through multiple groups of delivery pipelines 5, and the top group of delivery pipelines 5 is connected to the top oxygen lance 2. The automatic frequency conversion control system in the pump assembly 4 is ready to adjust the variation of the pump assembly 4 according to the vacuum degree and other data inside the vacuum oxygen decarburization furnace 1;

[0103] Lift the ladle 3 after being processed by the electric furnace into the vacuum oxygen decarburization furnace 1 with a bridge crane, drive the vehicle of the vacuum tank cover 6 to the vacuum treatment station, and conduct temperature measurement and sampling simultaneously.

[0104] Check the pump assembly 4 to ensure that the four-stage mechanical pump, the three-stage mechanical pump group (including at least one three-stage mechanical pump, at least one two-stage mechanical pump, and at least one one-stage mechanical pump), multiple groups of delivery pipelines 5, and valve instruments (including at least a bypass valve, a vacuum main valve, and a pre-pump valve for each stage in the three-stage mechanical pump group) are all in normal condition, and the standby pump can be put into use at any time.

[0105] Start the pump assembly 4 to evacuate: The four-stage mechanical pump operates at full frequency, sequentially open the pre-pump valves for each stage in the three-stage mechanical pump group except the standby pump, open the bypass valve and the vacuum main valve. After all the above valves are opened, start the evacuation timing and record the pressure value at the inlet of the pump assembly 4.

[0106] Monitor the vacuum degree and adjust the pump frequency: When the vacuum degree drops, use the full-range vacuum degree on the pump side when it is above 0.8 kPa, and use the high-vacuum degree on the pump side when it is below 0.8 kPa; when the vacuum degree rises, use the high-vacuum degree on the pump side when it is below 1 kPa, and use the full-range vacuum degree on the pump side when it is above 1 kPa.

[0107] Adjust the frequency of each stage of the pump in the pump assembly 4 according to the pressure value at the inlet of the pump assembly 4:

[0108] When the sum of the actual frequencies is less than the target frequency sum, increase the frequency of the pump with the smallest current among all the in-use pumps, and poll once per unit time;

[0109] When the sum of the actual frequencies is greater than the sum of the target frequencies, the pump with the largest current among all the in-service pumps is frequency-reduced, and polling is performed once per unit time.

[0110] Oxygen blowing decarburization operation: When the vacuum degree reaches 20 kPa, oxygen blowing decarburization starts and is carried out in 5 stages. The oxygen blowing flow rate is 400 - 1800 Nm 3 / h, with an average of 700 Nm 3 / h. The specific oxygen blowing stages and vacuum degree requirements are as follows:

[0111] Pre-blowing: 20 kPa; Main blowing: 16 kPa; Dynamic oxygen blowing 1: 13.3 kPa; Dynamic oxygen blowing 2: 10.6 kPa; Dynamic oxygen blowing 3: 8 - 6.7 kPa.

[0112] Oxygen is injected into the oxygen outlet pipe 11 from the top oxygen blowing lance 2. The movement of oxygen in the oxygen outlet pipe 11 pushes the positioning block 13 to move downward along the positioning groove 12. The positioning rod pushes the plug rod 15 connected to the linkage rod 14 to move downward, and the threaded rod 29 at the lower end of the plug rod 15 pushes the operation of the threaded groove 30, causing the rotating cylinder 31 to rotate at the outer end of the oxygen outlet pipe 11 along the sealed bearing 10.

[0113] The downward movement of the plug rod 15 pushes the linkage push plate 17 connected to the ring plate 22 to move downward along the linkage push groove 18, exposing the end nozzle 21. The oxygen conveyed by the pump assembly 4 enters the conveying ring 20 through multiple end nozzles 21 and is conveyed to the vacuum oxygen blowing decarburization furnace 1 through the oxygen conveying end pipe 19 connected by the linkage bearing 23.

[0114] The annular tooth cylinder 25 is connected to the linkage teeth 26 at the outer end of the oxygen conveying end pipe 19 while moving downward, pushing the oxygen conveying end pipe 19 to rotate up and down in the vertical plane along the inner end of the rotating groove 24 through the linkage bearing 23. The rotating cylinder 31 rotates synchronously in the horizontal plane, conveying oxygen to the inner end of the ladle 3 to ensure overall stability and accelerate the decarburization progress of the molten steel.

[0115] Subsequent treatment: When the carbon content in the molten steel reaches the requirement, stop oxygen blowing, enter the high-vacuum carbon deoxidation treatment, add alloy and reducing agent, and carry out the high-vacuum reduction treatment.

[0116] After the treatment is completed, close the main vacuum valve, break the vacuum state, lift the ladle cover, move the vehicle of the vacuum tank cover 6 to the standby position, measure the temperature and take samples, perform fine alloy adjustment (wire feeding), stop argon blowing, and use the overhead crane to lift the ladle 3 to the casting station.

[0117] During the whole operation process, the pump group automatic frequency conversion control system closely cooperates with the oxygen blowing decarburization device, maintains an appropriate vacuum degree by precisely controlling the operating frequency of the pump, ensures the smooth progress of the oxygen blowing decarburization process, and improves the decarburization efficiency and quality of the molten steel.

[0118] The above embodiments are only used to illustrate the present invention rather than limit the technical solutions described in the present invention. Although this specification has described the present invention in detail with reference to the above respective embodiments, the present invention is not limited to the above specific implementation manners. Therefore, any modification or equivalent replacement of the present invention; and all technical solutions and their improvements that do not depart from the spirit and scope of the invention are covered by the scope of the claims of the present invention.

Claims

1. An oxygen-blowing decarburization device with full vacuum degree, comprising a vacuum oxygen-blowing decarburization furnace (1), characterized in that, A ladle (3) is provided at the inner end of the vacuum oxygen decarburization furnace (1). A vacuum tank cover (6) is provided at the top of the vacuum oxygen decarburization furnace (1). A top oxygen lance (2) is provided at the central top of the vacuum tank cover (6). An oxygen outlet pipe (11) is provided at the output end of the top oxygen lance (2). Further included is: An oxygen coverage assembly for fully covering oxygen in the vacuum oxygen decarburization furnace (1). The oxygen coverage assembly includes a sealing bearing (10) and a rotating cylinder (31) located at the outer end of the oxygen outlet pipe (11), a positioning groove (12), a positioning block (13), and a linkage rod (14) located at the inner end of the oxygen outlet pipe (11). A threaded rod (29), a threaded groove (30), a limiting pipe (27), and a limiting rod (28) for facilitating rotation adjustment are provided at the inner end of the rotating cylinder (31). A plurality of end nozzles (21), a plurality of oxygen delivery end pipes (19), and a rotating groove (24) for facilitating oxygen delivery are provided at the inner end of the rotating cylinder (31). A plug rod (15) is provided at the lower end of the linkage rod (14). A ring-shaped tooth cylinder (25) is provided on the surface of the plug rod (15). Linkage teeth (26) are provided at the outer end of the ring-shaped tooth cylinder (25). The linkage teeth (26) wrap around the outer end of the oxygen delivery end pipe (19). Linkage bearings (23) are connected to both ends of the oxygen delivery end pipe (19). A delivery ring (20) is connected between the two oxygen delivery end pipes (19) through the linkage bearings (23).

2. The oxygen blowing decarburization device with full vacuum degree according to claim 1, characterized in that, Both ends of the sealing bearing (10) are fixedly connected to the oxygen outlet pipe (11) and the rotating cylinder (31) respectively. The positioning block (13) moves up and down along the positioning groove (12). The linkage rod (14) is fixedly connected to the central lower end of the positioning block (13). The positioning block (13) is a combination of an outer ring, an inner cylinder, and a cross bar connecting the two. The positioning groove (12) is embedded in the inner surface of the oxygen outlet pipe (11). The positioning groove (12) is slidably connected to the positioning block (13).

3. The oxygen blowing decarburization device with full vacuum degree according to claim 2, characterized in that, A fixed connection is provided between the center of the positioning block (13) and the linkage rod (14). A fixed connection is provided between the lower end of the linkage rod (14) and the plug rod (15). A linkage rod (14) is fixedly connected to the lower end of the plug rod (15). A fixed connection is provided between the lower end of the linkage rod (14) and the threaded rod (29). The outer end of the threaded rod (29) is threadedly connected to the threaded groove (30). The threaded groove (30) is embedded in the inner surface of the lower end of the rotating cylinder (31).

4. The full-vacuum oxygen blowing decarburization device according to claim 3, characterized in that, Each group of end nozzles (21) penetrates through the inner surface of the rotating cylinder (31). An inclined pipe is provided between the end nozzle (21) and the delivery ring (20). The delivery ring (20) is movably connected to the oxygen delivery end pipe (19) through the linkage bearing (23). A fixed connection is provided between the outer side of the rotating end of the oxygen delivery end pipe (19) and the linkage teeth (26). The outer end of the linkage teeth (26) is meshed with the ring-shaped tooth cylinder. The ring-shaped tooth cylinder is fixed to the outer end of the plug rod (15). Each group of oxygen delivery end pipes (19) is movably connected to the rotating cylinder (31) through the rotating groove (24).

5. The oxygen blowing decarburization device with full vacuum degree according to claim 4, characterized in that The upper end of the annular gear cylinder (25) is provided with an annular plate (22). The upper end of the annular plate (22) is provided with an inner annular groove (16). The outer end of the annular plate (22) is provided with a linkage push plate (17). The outer end of the linkage push plate (17) is provided with a linkage push groove (18). The linkage push groove (18) is embedded in the inner end of the rotating cylinder (31). The linkage push plate (17) and the linkage push groove (18) are correspondingly connected. The number of the linkage push plates (17) is the same as the number of the oxygen delivery end pipes (19). The linkage push groove (18) is connected through to the end pipe orifice (21). The linkage push groove (18) is slidably connected with the linkage push plate (17). Multiple groups of the linkage push plates (17) are fixedly connected with the annular plate (22). The top end of the annular gear cylinder is provided with a space for the up and down movement of the annular plate (22).

6. The full-vacuum oxygen blowing decarburization device according to claim 5, characterized in that, The inner end of the central part of the threaded rod (29) is provided with a limit pipe (27). The inner end of the limit pipe (27) is provided with a limit rod (28). The lower end of the limit rod (28) is provided with a rotating plate (32). The upper end of the rotating plate (32) is provided with a spring (33). The limit pipe (27) penetrates through the inner end of the central part of the threaded rod (29). The limit pipe (27) is slidably connected with the limit rod (28). The lower end of the limit rod (28) is fixedly connected with the rotating plate (32). The rotating plate (32) rotates along the inner surface of the lower end of the rotating cylinder (31). The spring (33) is wrapped around the outer end of the limit rod (28). The upper and lower ends of the spring (33) are respectively fixed at the lower end of the threaded rod (29) and the upper end of the rotating plate (32).

7. The full-vacuum oxygen blowing decarburization device according to claim 6, characterized in that, The outer end of the rotating cylinder (31) is provided with an outer annular groove (9). The inner end of the outer annular groove (9) is provided with a positioning ring (8). The outer end of the positioning ring (8) is provided with multiple groups of support rods (7). The outer annular groove (9) is embedded in the outer end of the rotating cylinder (31), and the position of the outer annular groove (9) is higher than the position of the rotating groove (24). The outer annular groove (9) is movably connected with the positioning ring (8). The outer end of the positioning ring (8) is fixedly connected with the support rods (7). Multiple groups of the support rods (7) are arranged in an equidistant annular pattern along the positioning ring (8).

8. An automatic variable frequency control system for the pump group of an oxygen blowing decarburization device with full vacuum degree, comprising a pump assembly (4), a pump group start-stop control circuit and a central processor, characterized in that, The pump assembly (4) includes at least one four-stage mechanical pump, a three-stage mechanical pump group, multiple groups of conveying pipelines (5) and valve instruments. The four-stage mechanical pump is a screw pump. The three-stage mechanical pump group includes at least one three-stage mechanical pump, at least one two-stage mechanical pump and at least one one-stage mechanical pump. The four-stage mechanical pump, at least one three-stage mechanical pump, at least one two-stage mechanical pump and at least one one-stage mechanical pump are connected in series between levels in sequence through the conveying pipelines (5). One set of standby pumps is respectively arranged in parallel for at least one three-stage mechanical pump, at least one two-stage mechanical pump and at least one one-stage mechanical pump through the conveying pipelines (5). The valve instruments at least include a bypass valve, a vacuum main valve and a pump pre-valve at each stage in the three-stage mechanical pump group.

9. The automatic variable frequency control system of the pump unit of an oxygen blowing decarburization device with full vacuum degree according to claim 8, characterized in that, Among the four-stage mechanical pump, three-stage mechanical pump, two-stage mechanical pump and one-stage mechanical pump, the pumps put into the automatic variable frequency control system for use are the pumps in operation, and the pumps with faults in operation among the four-stage mechanical pump, three-stage mechanical pump, two-stage mechanical pump and one-stage mechanical pump are the pumps out of service.

10. The automatic variable frequency control system of the pump unit of an oxygen blowing decarburization device with full vacuum degree according to claim 9, characterized in that, The operation steps are as follows: Step 1: The four-stage mechanical pump runs at full frequency. Sequentially open the pre-pump valves of each stage in the three-stage mechanical pump group except the standby pump. Open the bypass valve and the main vacuum valve. After all the above valves are opened, start the vacuum pumping timing and record the pressure value at the inlet of the pump assembly (4); Step 2: When the vacuum degree drops, use the full vacuum degree on the pump side as the standard above 0.8 kPa, and use the high vacuum degree on the pump side as the standard below 0.8 kPa; when the vacuum degree rises, use the high vacuum degree on the pump side as the standard below 1 kPa, and use the full vacuum degree on the pump side as the standard above 1 kPa; Step 3: According to the pressure value at the inlet of the pump assembly (4), adjust the frequency of each stage of the pump in the pump assembly (4), and compare according to the magnitude of the actual frequency sum and the target frequency sum: When the actual frequency sum is less than the target frequency sum, increase the frequency of the pump with the smallest current among all the pumps in operation, and poll once per unit time; When the actual frequency sum is greater than the target frequency sum, decrease the frequency of the pump with the largest current among all the pumps in operation, and poll once per unit time.

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