CN216955917U - Aluminum electrolysis bath furnace side liquation process simulation device - Google Patents
Aluminum electrolysis bath furnace side liquation process simulation device Download PDFInfo
- Publication number
- CN216955917U CN216955917U CN202123099411.5U CN202123099411U CN216955917U CN 216955917 U CN216955917 U CN 216955917U CN 202123099411 U CN202123099411 U CN 202123099411U CN 216955917 U CN216955917 U CN 216955917U
- Authority
- CN
- China
- Prior art keywords
- simulation device
- cold wall
- cooling
- air
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
Landscapes
- Electrolytic Production Of Metals (AREA)
Abstract
The utility model belongs to the technical field of aluminum electrolysis, and particularly relates to a furnace side liquation process simulation device of an aluminum electrolysis cell and a use method thereof. The device comprises a simulation device body, an air cooling system and a temperature control system; the simulation device body is of an inverted T-shaped structure and comprises a base and a rectangular cold wall perpendicular to the base, wherein a rectangular cooling cavity is formed in the cold wall, and a sealing rod is arranged at the upper part of the cooling cavity; the air cooling system is connected with the cooling cavity; the temperature control system is arranged in the molten electrolyte on the periphery of the cold wall and the simulation device body to measure the temperature of the cold wall and the molten electrolyte, and the simulation device further comprises a high-temperature reactor and a crucible. The utility model constructs a plane cold wall furnace upper growth model simulation device according to the side wall plane type heat dissipation structure of the actual aluminum electrolytic cell, the device can truly simulate the heat dissipation state of the operation process of the electrolytic cell, the precipitation and solidification process of the electrolyte on the simulation device is similar to the actual furnace upper growth process, and the simulation device has better experimental simulation effect.
Description
Technical Field
The utility model belongs to the technical field of aluminum electrolysis, and particularly relates to a furnace side liquation process simulation device for an aluminum electrolysis cell.
Background
The large prebaked electrolytic cell used in the modern aluminum industry is composed of four major parts, namely a cathode structure, an upper structure, a bus structure and electrical insulation. The cathode structure is the most important component of the electrolytic cell, and is a container for holding electrolytic melt (including molten electrolyte and aluminum liquid), including a cell shell and lining masonry contained therein. The bottom of the lining masonry is built by carbon blocks, the side part is built by plates made of carbon blocks or silicon carbide and the like, and the lower part is made of refractory bricks, insulating bricks and other refractory, insulating and anti-seepage materials. After the aluminum electrolytic cell is started, a circle of solid electrolyte blocks condensed by molten electrolyte can be formed on the inner wall of the hearth, and the solid electrolyte blocks are industrially called as a furnace side. The furnace wall mainly comprises cryolite, alumina, calcium fluoride and other solid inorganic salts, and continuously forms a chamber space with different thicknesses, and electrochemical and physicochemical reactions of aluminum electrolysis are carried out in the chamber space to realize the aluminum electrolysis process. The furnace side can protect the side wall of the groove from being corroded by high-temperature corrosive electrolyte; the heat loss of the electrolytic cell is reduced, and the heat preservation of the hearth is promoted; current is prevented from flowing through the side part of the groove, and horizontal current is restrained; meanwhile, the furnace side can adjust the heat balance and the material balance of the aluminum electrolytic cell.
A well-shaped furnace is very important to obtain high current efficiency and production efficiency. At present, researchers develop a static/dynamic numerical simulation calculation method based on temperature field analysis to calculate and analyze the properties of the furnace wall of the aluminum electrolytic cell, heat transfer and the like, but due to the high-temperature corrosivity of molten electrolyte, the actual shape and change behavior of the furnace wall in the aluminum electrolytic cell are difficult to directly measure. In the prior art, patent CN109283207B discloses a detection device for simulating the growth process of an aluminum electrolytic cell furnace side, which adopts a revolving body (the material is the same as that of the side wall of an industrial electrolytic cell) with a through hole at the center to simulate the side carbon blocks and artificial extension legs of the aluminum electrolytic cell, when in use, the revolving body is put into molten industrial electrolyte, and cooling air is blown into the center hole to cool the inner wall of the hole, so that the electrolyte is solidified at the outer wall, and a simulated furnace side is obtained. The cylindrical revolving body structure adopted by the utility model has a slightly larger difference with the plane side wall shape of an actual electrolytic bath, the heat transfer modes of the cylindrical revolving body structure and the actual electrolytic bath are different, the actual heat dissipation condition of the electrolytic bath cannot be really simulated, the generated furnace wall shape has a larger difference with the actual furnace wall, and the simulation device adopts a mode of blowing air into a central through hole for cooling, so that the heat transfer of the device is slow, and the temperature distribution of the outer wall is uneven due to the small volume of a cooling cavity. Therefore, in order to simulate the liquation behavior of the actual aluminum electrolytic cell furnace upper more truly and grasp the data of the generation, melting process and component distribution, microstructure and the like of the furnace upper, a simulation device and a method capable of reflecting the liquation process of the furnace upper more accurately need to be designed.
Disclosure of Invention
The utility model provides an aluminum electrolysis bath furnace side elutriation process simulation device with a large-volume cooling cavity and a furnace side elutriation plane and capable of accurately controlling temperature and a using method thereof, aiming at solving the problem that a simulation device in the prior art cannot truly simulate the elutriation behavior of an actual aluminum electrolysis bath furnace side.
In order to achieve the purpose, the technical scheme of the utility model is as follows:
a simulation device for the liquation process of an aluminum electrolysis bath furnace side comprises a simulation device body, an air cooling system and a temperature control system;
the simulation device body is of an inverted T-shaped structure and comprises a base and a cuboid cold wall perpendicular to the base, a cuboid cooling cavity is formed in the cold wall, and a sealing rod is arranged at the top of the cooling cavity;
the air cooling system is connected with the cooling cavity and cools the cooling cavity; specifically, circulating cooling gas is introduced into the cooling cavity to control the temperature of the cold wall to be lower than the primary crystal temperature of the electrolyte, so that the electrolyte is solidified and separated out on the outer side of the cold wall to form a furnace wall;
the temperature control system is disposed in the cold wall and the molten electrolyte to measure the temperature of the cold wall and the molten electrolyte.
As a further preferable scheme, the sealing rod is provided with a cooling gas inlet and a gas outlet, the gas cooling system is connected with the cooling gas inlet and the gas outlet, and the gas cooling system conveys cooling gas into the cooling cavity through the cooling gas inlet and then discharges the cooling gas through the gas outlet.
As a further preferable mode, the air cooling system comprises a cold air source container, an air inlet pipe and an air outlet pipe, the cold air source container is connected with the air inlet pipe and the air outlet pipe, the air inlet pipe penetrates through a cooling air inlet on the sealing rod and extends into the bottom of the cooling cavity, and the air outlet pipe is arranged in the air outlet.
As a further preferred scheme, the air inlet pipe is provided with a flowmeter and a cooling gas regulating valve, and the temperature of the cold wall can be accurately regulated and controlled by regulating the flow speed of the cooling gas.
As a further preferable mode, the temperature control system is a thermocouple, the thermocouple includes a first thermocouple and a second thermocouple, the first thermocouple is disposed in the molten electrolyte, and the second thermocouple is pre-embedded in the cold wall.
Further, the thermocouple is arranged at the center of the cold wall.
In a further preferred embodiment, the simulation device body is made of one of graphite, corundum, ceramic, silicon carbide and the like, and has the same material as the material of the side wall of the electrolytic cell; the air inlet pipe and the air outlet pipe are both stainless steel pipes or corundum pipes, and the air inlet pipe is used for introducing argon, nitrogen or compressed air into the cavity of the cold wall through the air inlet so as to reduce the temperature of the cold wall.
The simulation device further comprises a high-temperature reactor and a crucible, wherein the crucible is arranged in the high-temperature reactor, a molten electrolyte is arranged in the crucible, and the simulation device body is located in the molten electrolyte.
The use method of the aluminum electrolysis bath furnace side liquation process simulation device comprises the following steps:
(1) immersing the simulation device in molten electrolyte, and introducing cooling gas into the cooling cavity through a gas cooling system;
(2) adjusting the temperature of the cold wall by changing the flow rate of the cooling gas to make the difference value between the temperature of the cold wall and the temperature of the electrolyte to be measured consistent with the superheat degree or the target superheat degree of the actual electrolytic cell;
(3) and after the temperature is kept stable, keeping the flow rate of the cooling gas unchanged, and taking out the simulation device after keeping for a certain time to obtain the complete solidified furnace side.
Through the technical scheme, the utility model has the beneficial effects that:
1. the utility model constructs a plane cold wall furnace upper growth model simulation device according to the side wall plane type heat dissipation structure of the actual aluminum electrolytic cell, the device can truly simulate the heat dissipation state of the operation process of the electrolytic cell, the precipitation and solidification process of the electrolyte on the simulation device is similar to the actual furnace upper growth process, and the simulation device has better experimental simulation effect.
2. The simulation device provided by the utility model is provided with the large-volume cooling cavity, and the cooling gas is introduced into the cooling cavity, so that the temperature of the cold wall can be effectively adjusted, the simulation device has the characteristics of convenience in adjustment, rapidness in response and uniform temperature, and furnace wall samples under different superheat degrees can be quickly obtained.
3. The utility model can simulate the growth form of the furnace side of the electrolytic cell under different heat balance states, can provide guidance for the design optimization and daily production management of the lining structure of the modern large-scale electrolytic cell, and is beneficial to realizing the high-efficiency and stable operation of the aluminum electrolytic cell.
Drawings
FIG. 1 is a first schematic structural diagram of a simulation apparatus body of the aluminum electrolysis bath furnace side liquation process simulation apparatus of the present invention.
FIG. 2 is a schematic structural diagram II of a simulation apparatus body of the aluminum electrolytic bath furnace side liquation process simulation apparatus of the present invention.
FIG. 3 is a schematic structural diagram of a sealing rod of the furnace sidewall liquation process simulation device for an aluminum electrolysis cell of the present invention.
FIG. 4 is a schematic view showing the operation state of the apparatus for simulating the furnace sidewall liquation process of an aluminum electrolysis cell according to the present invention.
FIG. 5 is an XRD pattern of cold wall side dense layer material.
FIG. 6 is an XRD pattern of a molten salt-side porous layer material.
In the attached drawings, 1 is a base; 2 is a cold wall; 3 is a sealing rod; 4 is a cooling cavity; 5 is a thermocouple; 6 is an air inlet pipe; 7 is an air outlet pipe; 8 is a cold air source container; 9 is a molten electrolyte, 10 is a high temperature reactor, and 11 is a crucible.
Detailed Description
The utility model is further described with reference to the following figures and detailed description:
example 1
As shown in fig. 1 to 4, the apparatus for simulating the melting process of the furnace side of an aluminum electrolytic cell of the present embodiment includes a simulation apparatus body, an air cooling system and a temperature control system; the simulation device body is the type of falling T structure, and the simulation device body includes base 1 and perpendicular to base 1's cuboid cold wall 2, set up hollow intermediate layer in the cold wall 2, specifically be cuboid form cooling cavity 4, cooling cavity 4 top is provided with sealing rod 3, cooling gas import and gas outlet have been seted up on sealing rod 3.
The air cooling system is connected with the cooling cavity 4 and cools the cooling cavity 4; specifically, circulating cooling gas is introduced into the cooling cavity 4 to control the temperature of the cold wall 2 to be lower than the primary crystal temperature of the electrolyte, so that the electrolyte is solidified and separated out on the outer side of the cold wall to form a furnace wall. The air cooling system comprises a cold air source container 8, an air inlet pipe 6 and an air outlet pipe 7, wherein the cold air source container 8 is connected with the air inlet pipe 6 and the air outlet pipe 7, the air inlet pipe 6 penetrates through a cooling air inlet in the sealing rod 3 and extends into the bottom of the cooling cavity 4, a flow meter and a cooling air regulating valve are arranged on the air inlet pipe 6, and the temperature of the cold wall 2 can be accurately regulated and controlled by regulating the flow rate of the cooling air. The outlet pipe 7 is arranged in the gas outlet. The gas cooling system conveys cooling gas into the cooling cavity 4 through the cooling gas inlet and discharges the cooling gas through the gas outlet, and the temperature of the cold wall 2 is reduced by guiding out heat.
The material of the simulation device body is the same as the material of the side wall of the electrolytic bath, and is one of graphite, corundum, ceramic, silicon carbide and other materials; the air inlet pipe 6 and the air outlet pipe 7 are both stainless steel pipes or corundum pipes, and the air inlet pipe 6 introduces argon, nitrogen or compressed air into the cooling cavity 4 through the air inlet so as to reduce the temperature of the cold wall 2. In this example, nitrogen was used as the cooling gas.
The temperature control system is provided in the cold wall 2 and the molten electrolyte 9 to measure the temperature of the cold wall 2 and the molten electrolyte 9. Specifically, the temperature control system is a thermocouple 5, the thermocouple comprises a first thermocouple and a second thermocouple, the first thermocouple is arranged in the molten electrolyte 9, and the second thermocouple is embedded in the center of the cold wall 2.
The simulation device further comprises a high-temperature reactor 10 and an iron crucible 11, wherein the iron crucible 11 is arranged in the high-temperature reactor 10, a molten electrolyte 9 is arranged in the iron crucible 11, and the simulation device body is located in the molten electrolyte 9.
The simulation experiment of the melting-out process of the furnace side of the aluminum electrolytic cell is carried out in a high-temperature reactor 10, industrial aluminum electrolyte powder or cryolite-based mixed salt prepared according to a certain proportion is placed in an iron crucible 11, then the iron crucible 11 is placed in a stainless steel reactor 10, the temperature is kept for 2 hours after being heated to 300 ℃ in the argon protective atmosphere to dry moisture, then the temperature is slowly increased to a set temperature, after molten salt is melted to form molten electrolyte, cooling gas nitrogen is introduced into a cooling cavity 4 at a fixed flow rate through a gas cooling system, the nitrogen is introduced into the bottom of the cooling cavity 4 through a gas inlet pipe 6 to cool a cold wall 2, and then the heat is discharged from a gas outlet pipe 7 to lead out heat so as to reduce the temperature of the cold wall 2; the flow rate of the cooling gas is observed through a flow meter on the gas inlet pipe 6, the flow rate of the gas is adjusted through a cooling gas adjusting valve, the temperature of the cold wall 2 is further adjusted, the cold wall reaches a set overheating value (compared with the temperature of the electrolyte), the flow rate of the gas is kept stable for 1 hour after the temperature of the side wall is stabilized at a preset value, and then the simulation device is taken out, so that a complete solidified furnace side sample is obtained.
Example 2
High-purity nitrogen gas is introduced into the cooling cavity in the embodiment 1 at a flow rate of 30L/min for cooling, so that a solidified furnace side sample is obtained under the condition that the temperature of the cold wall is lower than the temperature of the molten electrolyte by 10 ℃ (namely, the superheat degree), the obtained furnace side is continuous and regular in shape, and the cooling gas is introduced into the cooling cavity, so that the overall temperature of the cold wall can be uniformly reduced, and the growth process of the electrolytic cell furnace side is well simulated.
Example 3
Cooling gas was introduced into the cooling cavity of example 1 to reduce the temperature of the cold wall to about 20 ℃ (superheat degree) below the temperature of the molten electrolyte, and the cold wall was stabilized for 2 hours and then precipitated as a solidified hearth wall. The microstructure of the cold wall is analyzed, and the part close to the cold wall is found to be in a columnar crystalline state and has a compact structure; XRD results are shown in FIG. 5, which shows that cryolite (Na) is the main component3AlF6) While containing a small amount of cryolite (Na)5Al3F14). The external layer structure of the furnace side close to the side of the molten electrolyte is loose and has higher porosity, and the XRD pattern in figure 6 shows that the main phase of the external layer is the sub-cryolite. The structure and the components of the furnace wall are similar to those of the real furnace wall of a 500 kA aluminum electrolytic cell reported in the literature (Zhang Qisong. the heat and mass transfer process in electrolyte phase change influences the real furnace wall [ J]) The simulation device of the utility model can well simulate the real furnace side of the aluminum electrolytic cell.
The melting point of the cryolite is lower than that of cryolite (1009 ℃), and is 737 ℃. Therefore, the melting point of the outer furnace upper with the main phase of the cryolite is low, and when the superheat degree is slightly increased, the outer furnace upper is dissolved; as the degree of superheat decreases, cryolite correspondingly precipitates from the melt, forming the observed porous outer layer. That is, once the thermal balance of the electrolyzer system is broken, the porous crystalline layer of the furnace side responds rapidly with a corresponding melting/leaching change. This law is consistent with that observed in actual production practice. The simulation device can better simulate the liquation process of the electrolytic bath furnace side and is suitable for researching the influence rule of the electrolysis process parameters such as superheat degree, molecular ratio and the like on the furnace side.
The above-described embodiments are merely preferred embodiments of the present invention, and not intended to limit the scope of the utility model, so that equivalent changes or modifications in the structure, features and principles described in the present invention should be included in the claims of the present invention.
Claims (6)
1. A simulation device for the liquation process of an aluminum electrolysis bath furnace side comprises a simulation device body, an air cooling system and a temperature control system; it is characterized in that the preparation method is characterized in that,
the simulation device body is of an inverted T-shaped structure and comprises a base (1) and a cuboid cold wall (2), wherein the cuboid cold wall (2) is perpendicular to the base (1), a cuboid cooling cavity (4) is formed in the cold wall (2), and a sealing rod (3) is arranged at the upper part of the cooling cavity (4);
the air cooling system is connected with the cooling cavity (4) and cools the cooling cavity (4); the air cooling system comprises a cold air source container (8), an air inlet pipe (6) and an air outlet pipe (7), wherein the cold air source container (8) is connected with the air inlet pipe (6) and the air outlet pipe (7); the air inlet pipe (6) extends into the bottom of the cooling cavity (4);
the temperature control system is arranged in the cold wall (2) and the molten electrolyte (9) at the periphery of the simulation device body to measure the temperature of the cold wall (2) and the molten electrolyte (9); the temperature control system is a thermocouple (5), the thermocouple comprises a first thermocouple and a second thermocouple, the first thermocouple is arranged in the molten electrolyte (9) on the periphery of the simulation device body, and the second thermocouple is embedded in the cold wall;
the simulation device further comprises a high-temperature reactor (10) and a crucible (11), wherein the crucible (11) is arranged in the high-temperature reactor (10), a molten electrolyte (9) is arranged in the crucible (11), and the simulation device body is located in the molten electrolyte (9).
2. The aluminum electrolysis bath furnace side liquation process simulation device according to claim 1, wherein the sealing rod (3) is provided with a cooling gas inlet and a gas outlet, and the gas cooling system is connected with the cooling gas inlet and the gas outlet.
3. The aluminum electrolysis bath furnace side liquation process simulation device according to claim 2, wherein the air inlet pipe (6) penetrates through a cooling gas inlet on the sealing rod (3) and extends into the bottom of the cooling cavity (4), and the air outlet pipe (7) is arranged in a gas outlet.
4. The aluminum electrolysis bath furnace side liquation process simulation device according to claim 1, wherein a flow meter and a cooling gas regulating valve are arranged on the air inlet pipe (6).
5. The aluminum electrolysis bath furnace side liquation process simulation device according to claim 1, wherein the air inlet pipe (6) and the air outlet pipe (7) are both stainless steel pipes or corundum pipes.
6. The apparatus as claimed in claim 1, wherein the second thermocouple is pre-embedded in the center of the cold wall.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123099411.5U CN216955917U (en) | 2021-12-10 | 2021-12-10 | Aluminum electrolysis bath furnace side liquation process simulation device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123099411.5U CN216955917U (en) | 2021-12-10 | 2021-12-10 | Aluminum electrolysis bath furnace side liquation process simulation device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216955917U true CN216955917U (en) | 2022-07-12 |
Family
ID=82306303
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202123099411.5U Active CN216955917U (en) | 2021-12-10 | 2021-12-10 | Aluminum electrolysis bath furnace side liquation process simulation device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN216955917U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023103324A1 (en) * | 2021-12-10 | 2023-06-15 | 郑州大学 | Side-ledge melting process simulation device for aluminum electrolysis cell, and method of using same |
-
2021
- 2021-12-10 CN CN202123099411.5U patent/CN216955917U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023103324A1 (en) * | 2021-12-10 | 2023-06-15 | 郑州大学 | Side-ledge melting process simulation device for aluminum electrolysis cell, and method of using same |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| WO2023103324A1 (en) | Side-ledge melting process simulation device for aluminum electrolysis cell, and method of using same | |
| CN216955917U (en) | Aluminum electrolysis bath furnace side liquation process simulation device | |
| CN109338414B (en) | Method for optimizing addition amount of aluminum fluoride in aluminum electrolysis process by acid method and electronic equipment | |
| CN103993335B (en) | The device and method of aluminium alloy is directly prepared in a kind of fused salt electrolysis-casting | |
| CN107423460B (en) | Numerical simulation method for improving crystallization quality of fused magnesium fused weight | |
| CN107748089B (en) | Sampling device, sampling method and application for determining solubility of metal in molten salt | |
| CN112210795B (en) | Aluminum electrolysis energy balance adjusting method and system based on superheat degree and aluminum electrolysis cell | |
| Yasinskiy et al. | Behaviour of aluminium oxide in KF-AlF3-Al2O3 melts and suspensions | |
| CN105588781B (en) | A kind of device and method for measuring field trash rate of dissolution in metallurgy clinker | |
| CN104562193A (en) | Casting method for polycrystalline silicon ingot | |
| CN109503197A (en) | A kind of preparation method of calcium hexaluminate porous ceramics | |
| CN105779780B (en) | A kind of electroslag remelting free-floride slag and its method for electroslag remelting | |
| CN109283207B (en) | Detection device and method for simulating growth process of furnace side of aluminum electrolytic cell | |
| Tkacheva et al. | Solid phase formation during aluminium electrolysis | |
| CN106477618B (en) | A kind of fused salt solid solution and preparation method thereof and preparation facilities | |
| US7112269B2 (en) | Measuring duct offgas temperatures to improve electrolytic cell energy efficiency | |
| Pearce et al. | Optimization of SPRT measurements of freezing in a zinc fixed-point cell | |
| CN109267108A (en) | A kind of preparation method of aluminum chromium | |
| Wang et al. | Effect of AlN on properties of non-reactive CaO-Al2O3-based mold flux for high-Al steel | |
| Liu et al. | The structure of the smelting cell ledge under variable sidewall heat flow conditions | |
| Li et al. | Development and application of a structured/unstructured combined mesh scheme for global modeling of a directional solidification process of silicon | |
| Ksiazek et al. | Measurement of metal temperature during tapping of an industrial FeSi furnace | |
| Verstreken | Employing a new bath-and liquidus temperature sensor for molten salts | |
| Wang et al. | Numerical simulation of grain growth of directionally solidified DZ4125 alloy under varied blade orientations | |
| Shang et al. | Directional solidification behavior of turbine blades in DZ125 alloy: design of blade numbers on assembly |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |