Flexible aluminum electrolysis cell shell and electrolysis cell

Abstract

The invention belongs to the technical field of electrolytic aluminum equipment, and particularly relates to a flexible aluminum electrolytic cell shell and an electrolytic cell. The inner side heat conduction plate is arranged on the inner side of the outer side strong protection plate, is in contact with the cell lining structure of the electrolytic cell, corresponds to the positions of the molten aluminum and the electrolyte, and forms a double-layer cell shell structure with the inner side heat conduction plate; the barrier plate is arranged between the inner side heat conduction plate and the outer side strong protection plate; the side heat exchanger is arranged in a space defined by the inner side heat conduction plate, the outer side strong protection plate and the blocking plate and makes contact with the inner side heat conduction plate. The insulating bricks are filled in the area between the outer side strong protection plate and the electrolytic cell; and the cathode system tank is arranged in the insulating brick below the barrier plate and penetrates through the outer side strong protection plate. The problems that an existing flexible aluminum electrolysis cell is high in side wall temperature and low in heat exchange efficiency are solved, and the potential safety hazard that when a heat exchange medium is liquid, leakage is likely to occur is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum electrolysis equipment, and in particular relates to a flexible aluminum electrolysis cell shell and an electrolysis cell. Background Art

[0002] At present, the coordinated development of sources, grids, loads and storage has become the main technical route for the utilization of renewable energy. However, in actual applications, since renewable energy is greatly affected by changes in natural conditions, the loads of hydropower, wind power and solar power vary greatly in different seasons, day and night, and at different times, and the power supply system has unstable technical problems.

[0003] As a high-power consumption industry, the electrolytic aluminum industry consumes about 5-7% of my country's electricity generation each year. Due to the process characteristics of 24-hour stable operation of electrolytic aluminum production, the electrolytic aluminum industry has extremely high requirements for the stability of the power supply system. The instability of the power supply system does not meet the stable operation of aluminum electrolysis. As an important load of the power grid, if the electrolytic aluminum industry can measure and peak the load for the power grid, it will greatly increase the proportion of wind (solar) power on the grid in my country and solve the key technical problems of renewable energy utilization in my country. In order to solve the problem of energy storage peak regulation, the existing technology proposes to develop a wide range of flexible power input through the energy flow regulation technology at the output end of the electrolytic cell, so that the electrolytic cell can get rid of the high dependence on power stability, thereby making the electrolytic aluminum plant a large-capacity "virtual battery".

[0004] The existing method is to install a heat exchanger structure on the outside of the electrolytic cell based on the existing large pre-baked electrolytic cell, and use the high-temperature heat exchange medium to exchange the heat from the side of the electrolytic cell and make use of it. At the same time, the heat exchange control of the heat exchange system is used to adjust the crust inside the electrolytic cell, control the internal shape of the tank, and maintain the efficient operation of the electrolytic cell.

[0005] Chinese patent CN113913873 discloses an aluminum electrolytic cell that can act as a flexible load and a method for controlling its thermal balance. Although the patent mentions the problem of combining the heat exchange system with the electrolytic cell structure and the problem of optimizing the temperature field of the electrolytic cell, its structure still has the problem of low heat exchange efficiency and high temperature of the electrolytic cell side wall. When the heat exchange medium is gas, the specific heat capacity of the gas is small, which is not suitable for long-distance transportation and has low heat exchange efficiency. When the heat exchange medium is liquid (high-temperature molten salt, etc.), the heat exchange efficiency is high and it is suitable for long-distance transportation. However, the heat exchange medium will inevitably leak at the connection of the pipeline and after long-term use of the pipeline. Once the heat exchange medium enters the cathode system, it will corrode the insulating material of the cathode system and cause a safety accident. Summary of the invention

[0006] Purpose of the invention: The present invention proposes a flexible aluminum electrolysis cell shell and an electrolysis cell, the purpose of which is to solve the problems of high side wall temperature and low heat exchange efficiency of existing flexible aluminum electrolysis cells, as well as the potential safety hazard of leakage when the heat exchange medium is liquid.

[0007] Technical solution: The first method of the present invention proposes a flexible aluminum electrolytic cell shell, including an outer strong protective plate, which is arranged on the outer circumference of the electrolytic cell; an inner heat conductive plate, which is arranged on the inner side of the outer strong protective plate, contacts the cell lining structure of the electrolytic cell, corresponds to the positions of the aluminum liquid and the electrolyte, and forms a double-layer cell shell structure with the inner heat conductive plate; a baffle, which is arranged between the inner heat conductive plate and the outer strong protective plate; a side heat exchanger, which is arranged in a space surrounded by the inner heat conductive plate, the outer strong protective plate and the baffle, and contacts the inner heat conductive plate; insulation bricks, which are filled in the area between the outer strong protective plate and the electrolytic cell; and a cathode system slot, which is opened in the insulation bricks below the baffle and passes through the outer strong protective plate.

[0008] Preferably, the inner heat conducting plate and the blocking plate are an integral structure vertically arranged, and the cross-section of the integral structure is L-shaped.

[0009] Furthermore, the distance between the outer strong protective plate and the inner heat conducting plate is at least 10 cm.

[0010] Furthermore, the inner heat conducting plate is made of stainless steel material resistant to electrolyte corrosion, has a thickness of 5-20 mm, a thermal conductivity of at least 100 (W / mk), and a high temperature resistance of at least 700°C.

[0011] Furthermore, the distance h between the blocking plate and the upper surface of the cathode system is ≥ 0.75d, where d is the deformation of the outer strong guard plate in the width direction, in mm.

[0012] Furthermore, the side heat exchanger is a structure in which multiple liquid heat exchange pipes are arranged in parallel, and are arranged on the inner wall of the inner heat conduction plate. The upper and lower ends of each liquid heat exchange pipe are respectively connected to the first inlet and the second inlet, and an outlet is opened in the middle. The liquid heat exchange pipe between the first inlet and the outlet corresponds to the electrolyte of the electrolytic cell, and the liquid heat exchange pipe between the second inlet and the outlet corresponds to the aluminum liquid of the electrolytic cell.

[0013] Alternatively, the side heat exchanger is a double-tube liquid heat exchange pipe structure arranged in an S shape, and is arranged on the inner wall of the inner heat conduction plate, wherein two adjacent ports of the double-tube liquid heat exchange pipe, one is a liquid inlet, and the other is a liquid outlet, and the flow directions of the heat exchange medium in the two pipes of the double-tube liquid heat exchange pipe are opposite.

[0014] Alternatively, the side heat exchanger is a structure in which multiple gas heat exchange pipes are arranged in parallel, and are arranged on the inner wall of the inner heat conduction plate. One end of the gas heat exchange pipe is connected to the gas inlet, and the other end is connected to the gas outlet. The interior of the gas heat exchange pipe is arranged with multiple staggered metal baffles, and the end connected to the gas outlet is arranged with a structure with a gradually smaller inner diameter.

[0015] Furthermore, when the heat exchange medium is a liquid, the heat exchange medium is a nitrate; the nitrate includes one or more of sodium nitrate, potassium nitrate, calcium nitrate, and ammonium nitrate.

[0016] The present invention also provides a flexible aluminum electrolysis cell, comprising the flexible aluminum electrolysis cell shell, wherein one end of the cathode system is arranged in the cathode system cell and extends out an outer strong guard plate.

[0017] Beneficial effects: The tank shell structure proposed by the present invention is a side heat exchanger placed in the space surrounded by the outer strong guard plate, the inner heat conduction plate and the blocking plate, and the outer strong guard plate and the electrolytic cell are filled with insulation bricks. The heat transferred from the electrolytic cell to the inner heat conduction plate can basically only be exchanged through the side heat exchanger, which reduces the heat loss, promotes the maximum heat exchange and heat preservation of the side heat exchanger, and improves the waste heat temperature and efficiency of the side heat exchanger, so that the electrolytic cell can flexibly absorb wind power. The temperature of the outer strong guard plate is also reduced, and the temperature can be lower than 50°C, which is about 200°C lower than the temperature of the existing electrolytic cell shell, which improves the waste heat recovery rate, and at the same time greatly improves the high-temperature production environment of the electrolysis workshop to ensure the health of personnel.

[0018] The blocking plate structure in the tank shell structure effectively blocks the possibility of the heat exchange medium contacting the cathode system, avoiding the risk of liquid heat exchange medium corroding the insulating material of the cathode system and causing safety accidents; the inner heat conduction plate is arranged at the position of the electrolytic cell corresponding to the aluminum liquid and the electrolyte, and does not contact the cathode system, and the distance between the outer strong guard plate and the inner heat conduction plate is equivalent to the overall tank shell structure extending outward relative to the electrolytic cell by at least 10 cm, combined with the insulation bricks filled between the outer strong guard plate and the electrolytic cell, this structural design will further alleviate the thermal stress and the stress released by the cathode expansion, and reduce the deformation of the tank shell and the external cradle frame. Furthermore, the thickness of the inner heat conduction plate in the present invention can be as low as 5 mm, which greatly improves the heat transfer efficiency compared to the existing steel plate. The outer strong guard plate bears the stress released by the cathode on the electrolytic cell, ensuring the safe and stable operation of the electrolytic cell.

[0019] When the tank shell structure proposed in the present invention is used in combination with a 3000A aluminum electrolytic cell, the side heat exchange efficiency can reach 83%, which is equivalent to saving about 1,738 kWh of electricity per ton of aluminum; within 85% of the current fluctuation, the electrolytic aluminum production can operate stably, achieving the purpose of the electrolytic cell for peak regulation of the power grid.

[0020] The tank shell structure proposed in the present invention is used in combination with a 10000A aluminum electrolytic cell. The heat exchange efficiency of the side heat exchanger is 68%, which is equivalent to saving 1423 kWh of electricity per ton of aluminum. The current fluctuation varies by 80%, and the electrolytic aluminum production can operate stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a cross-sectional view of the device; Figure 2 This is a schematic diagram of the first structure of the side heat exchanger; Figure 3 It is a schematic diagram of the second structure of the side heat exchanger; Figure 4 It is a schematic diagram of the third structure of the side heat exchanger; Figure 5 This is a schematic diagram of the heat exchange structure on the side of a 3000A flexible aluminum electrolytic cell; Figure 6 This is a schematic diagram of the heat exchange structure of the side of a 10000A flexible aluminum electrolytic cell; Note in the figure: 1. Electrolytic cell, 11. Cell lining structure, 2. Side heat exchanger, 21. Liquid heat exchange pipeline, 211. First inlet, 212. Second inlet, 213. Outlet, 22. Double-tube liquid heat exchange pipeline, 221. Liquid inlet, 222. Liquid outlet, 23. Gas heat exchange pipeline, 231. Gas inlet, 232. Gas outlet, 3. Inner heat conduction plate, 4. Outer strong protective plate, 5. Cathode system tank, 6. Baffle plate, 7. Insulation brick, 8. Cathode system, 9. Electrolyte, 10. Liquid aluminum. DETAILED DESCRIPTION

[0022] To further illustrate the technical means and effects of the present invention, the present invention is further described below in conjunction with the embodiments and drawings. It should be understood that the specific implementation methods described herein are only used to explain the present invention, rather than to limit the present invention.

[0023] like Figure 1 As shown, a flexible aluminum electrolytic cell shell comprises: The outer strong guard plate 4 is arranged on the outer circumference of the electrolytic cell 1; the thermal stress generated after the electrolytic cell 1 is calcined will cause the maximum displacement of the electrolytic cell 1 along its length direction to be 1-3cm, the maximum displacement in the width direction to be between 2-4cm, and the maximum displacement in the height direction to be between 2-4cm; the function of the outer strong guard plate 4 is to bear the stress released by the cathode of the electrolytic cell, and to provide a closed space to reduce heat loss. The material is preferably stainless steel.

[0024] The inner heat conducting plate 3 is arranged on the inner side of the outer strong protective plate 4, contacts the tank lining structure 11 of the electrolytic tank 1, corresponds to the position of the aluminum liquid 10 and the electrolyte 9, and forms a double-layer tank shell structure with the inner heat conducting plate 3; the function of the inner heat conducting plate 3 is to resist the high temperature of the electrolytic tank 1 and the corrosion of the electrolyte, and conduct the heat of the electrolytic tank 1 to the side heat exchanger 2.

[0025] The blocking plate 6 is arranged between the inner heat conducting plate 3 and the outer strong protection plate 4; as a preferred embodiment, the inner heat conducting plate 3 and the blocking plate 6 are an integral structure arranged vertically, and the cross section of the integral structure is L-shaped. Since the stress is mainly concentrated at the connection of each structure, the connection is affected by the stress and cracks occur. After the two are integrated, it is equivalent to one less connection, and there will be no cracks here due to the change of stress, which will cause the risk of heat exchange medium leakage.

[0026] The side heat exchanger 2 is arranged in a space surrounded by the inner heat conducting plate 3, the outer strong protection plate 4 and the blocking plate 6, and contacts the inner heat conducting plate 3; The insulation brick 7 is filled in the area between the outer strong guard plate 4 and the electrolytic cell 1; because the insulation brick 7 itself is fireproof and heat-insulating, it is enclosed in the space surrounded by the inner heat conducting plate 3, the outer strong guard plate 4 and the blocking plate 6. The heat generated during the aluminum electrolysis process cannot be dissipated through the insulation brick 7. Most of the heat can only be exchanged through the side heat exchanger 2 to reduce or compensate for the heat. The heat loss is small, which greatly improves the waste heat recovery efficiency. The cooperation of the insulation brick 7 and the side heat exchanger 2 greatly improves the waste heat recovery efficiency. When used in conjunction with the side heat exchanger 2, the temperature of the outer strong guard plate 4 in contact with the external environment of the electrolysis workshop is lower than 50°C, which greatly improves the high-temperature production environment of the electrolysis workshop and ensures the health of personnel.

[0027] The cathode system slot 5 is opened in the insulation brick 7 below the blocking plate 6 and penetrates the outer strong guard plate 4. It is used to place the cathode system 8, and the cathode system 8 extends out of the outer strong guard plate 4.

[0028] The stress during the operation of the aluminum electrolytic cell is very complex. In the electrolysis process, in addition to the precipitation of aluminum, there is also the precipitation of sodium. After the sodium precipitates, it will diffuse to the cathode carbon block, causing the volume expansion of the cathode carbon block to produce sodium expansion stress. The cell shell needs to withstand the thermal expansion of the cathode carbon block and the sodium expansion stress. Sometimes the cell shell will be damaged due to excessive stress. Therefore, the inner steel plate of the existing cell shell structure that contacts the cell lining structure usually uses a thicker steel plate (the existing structure only has the inner steel plate, 16-20mm) to resist the thermal stress after the electrolytic cell is roasted and the expansion stress of the cathode system, but the thickness will affect the thermal conductivity of the inner heat conductive plate 3, resulting in low temperature and low efficiency of the waste heat recycled by the side heat exchanger 2. The present invention sets the inner heat conducting plate 3 at the position of the electrolytic cell 1 corresponding to the aluminum liquid 10 and the electrolyte 9, without contacting the cathode system, and fills the insulation brick 7 between the outer strong guard plate 4 and the electrolytic cell 1, thereby relieving thermal stress and expansion stress, and wraps the side heat exchanger 2 in the space surrounded by the inner heat conducting plate 3, the outer strong guard plate 4 and the blocking plate 6, and filled with the insulation brick 7, so that heat can only be exchanged through the side heat exchanger 2, thereby improving the waste heat temperature and efficiency of the side heat exchanger 2. In addition, the blocking plate 6 can effectively isolate the side heat exchanger 2 from the cathode system 8, avoiding the serious problem of accidental leakage of the heat exchange medium in the side heat exchanger 2, contact with the cathode system, corrosion of the insulation material of the cathode system, and the occurrence of safety accidents.

[0029] The outer strong guard plate 4 is also arranged at the bottom of the insulation brick 7 and the electrolytic cell 1, and above the side heat exchanger 2. The overall tank shell structure is in a concave shape, which wraps the heat inside the tank shell structure to improve the recovery and utilization of waste heat. Preferably, the outer strong guard plate 4 arranged above the side heat exchanger 2 and the outer strong guard plates 4 or the inner heat conducting plate 3 on both sides are an opening and closing structure, and the opening and closing structure can be an existing structure such as a cover structure and a folding structure, which is convenient for the internal side heat exchanger 2 to be repaired, inspected and replaced after long-term use.

[0030] Furthermore, the distance between the outer strong guard plate 4 and the inner heat conducting plate 3 is at least 10 cm, preferably 10 to 20 cm, which is equivalent to the overall tank shell structure extending outward by 10 to 20 cm relative to the electrolytic cell 1. Combined with the insulation bricks 7 filled between the outer strong guard plate 4 and the electrolytic cell 1, this structural design will further alleviate the stress released by the cathode expansion and reduce the deformation of the tank shell and the external cradle frame.

[0031] The inner heat conducting plate 3 is made of stainless steel material resistant to electrolyte corrosion, with a thickness of 5-20 mm, a thermal conductivity of at least 100 (W / m·K), and a high temperature resistance of at least 700°C. The existing electrolytic cell shell structure usually uses a thicker steel plate to resist the thermal stress after the electrolytic cell is roasted and the expansion stress of the cathode system, but it leads to low thermal conductivity of the inner heat conducting plate 3, low temperature of the waste heat recycled by the side heat exchanger 2, and low efficiency. The present invention sets the inner heat conducting plate 3 at the position of the electrolytic cell 1 corresponding to the aluminum liquid 10 and the electrolyte 9, without contacting the cathode system, and fills the insulation brick 7 between the outer strong guard plate 4 and the electrolytic cell 1, thereby relieving thermal stress and expansion stress, thereby limiting the material of the inner heat conducting plate 3, and improving the waste heat temperature and efficiency recycled by the side heat exchanger 2. The thermal conductivity is at least 100 (W / mk), which is convenient for two-way heat exchange, and meets the requirements of the side heat exchanger for recovering the waste heat in the electrolytic cell and the side heat exchanger for compensating the heat on the side of the electrolytic cell for heat preservation. The corrosion resistance avoids corrosion of the heat exchange medium and electrolyte, thereby ensuring the safety of use. The material of the blocking plate 6 is consistent with that of the inner heat conducting plate 3.

[0032] Since the cathode system 8 expands and deforms toward both ends, in order to simultaneously meet the heat exchange efficiency of the side heat exchanger 2 and ensure that the baffle plate 6 is affected as little as possible by the expansion force of the cathode system 8, it is necessary to limit the distance between the baffle plate 6 and the upper surface of the cathode system 8. The present application limits the distance between the baffle plate 6 and the upper surface of the cathode system 8 to h≥0.75d, where d is the deformation of the outer strong guard plate 4 in the width direction, in mm. The deformation d of the outer strong guard plate 4 in the width direction can be obtained by measurement. The expansion stress of the cathode system mainly affects the deformation of the cathode carbon block. The maximum deformation occurs at the center of the upper surface of the cathode carbon block and gradually decreases toward the two ends of the cathode carbon block. Since the deformation of the cathode carbon block is not easy to measure, the deformation of the outer strong guard plate 4 located on the outside in the width direction is convenient to measure. Through the force analysis of the thermal stress and expansion stress in various directions on the outer strong guard plate 4, it is simulated and calculated that when the distance h between the baffle plate 6 and the upper surface of the cathode system 8 is ≥ 0.75d, a large expansion stress can be avoided, thereby avoiding the influence of the expansion stress of the cathode system on the baffle plate 6. It is not easy to produce gaps at the connection between the baffle plate 6 and the outer strong guard plate 4 and / or the inner heat conduction plate 3, thereby eliminating the problem of heat exchange medium leakage and contact with the cathode system.

[0033] This embodiment provides three side heat exchanger 2 structures, and the existing heat exchanger structure is also applicable to the flexible electrolytic cell shell structure of the present application.

[0034] like Figure 2As shown, the first side heat exchanger 2 is a structure in which a plurality of liquid heat exchange pipes 21 are arranged in parallel, and are arranged on the inner wall of the inner heat conducting plate 3. The upper and lower ends of each liquid heat exchange pipe 21 are respectively connected to the first inlet 211 and the second inlet 212, and an outlet 213 is opened in the middle. The liquid heat exchange pipe 21 between the first inlet 211 and the outlet 213 corresponds to the electrolyte 9 part of the electrolytic cell 1, and the liquid heat exchange pipe 21 between the second inlet 212 and the outlet 213 corresponds to the aluminum liquid 10 part of the electrolytic cell 1. Due to the difference in temperature between the electrolyte 9 and the aluminum liquid 10 during the electrolysis process, the first side heat exchanger 2 structure can reduce the heat and compensate the heat according to the temperatures of the electrolyte 9 and the aluminum liquid 10.

[0035] like Figure 3 As shown, the second side heat exchanger 2 is a structure in which the double-tube liquid heat exchange pipe 22 is closely arranged in an S shape, and is arranged on the inner wall of the inner heat conducting plate 3, wherein two adjacent ports of the double-tube liquid heat exchange pipe 22 are one liquid inlet 221 and the other liquid outlet 222, and the heat exchange medium in the two pipes of the double-tube liquid heat exchange pipe 22 flows in opposite directions. When cooling and heat exchanging, the temperature of the heat exchange medium entering the liquid inlet 221 is low, and the temperature of the heat exchange medium flowing out of the liquid outlet 222 after heat exchange is high relative to the temperature of the liquid inlet 221, which can level the temperature difference between the two ends of the side heat exchanger 2 contacting the electrolytic cell 1, and achieve uniform cooling of each position of the electrolytic cell 1, avoiding the problem of temperature gradient difference due to the lower temperature on one side of the electrolytic cell 1 contacting the low-temperature heat exchange medium and the higher temperature on the other side. When temperature compensation is performed, the temperature of the heat exchange medium entering the liquid inlet 221 is high, and the temperature of the heat exchange medium flowing out of the liquid outlet 222 after heat exchange is lower than the temperature of the liquid inlet 221, which can level out the temperature difference between the two ends of the side heat exchanger 2 contacting the electrolytic cell 1, thereby achieving uniform heat preservation at all positions of the electrolytic cell 1.

[0036] like Figure 4As shown, the third side heat exchanger 2 is a plurality of gas heat exchange pipes 23 arranged in parallel on the inner wall of the inner heat conducting plate 3, and the pipe cross section is preferably a square structure to increase the contact area with the inner heat conducting plate 3. One end of the gas heat exchange pipe 23 is connected to the gas inlet 231, and the other end is connected to the gas outlet 232. The inside of the gas heat exchange pipe 23 is provided with a plurality of staggered metal baffles to increase the heat exchange area and the residence time of the heat exchange medium, and one end connected to the gas outlet 232 is provided with a structure with a gradually decreasing inner diameter, which is conducive to the heat exchange medium to fully contact the electrolytic cell 1. The metal baffle is one or more of a metal fin perpendicular to the inner wall of the gas heat exchange pipe 23, a metal sheet arranged obliquely, and a metal sheet with a wavy vertical direction, and the metal sheet can be provided with a structure with holes. However, when the heat exchange medium is gas, although there is no problem of heat exchange medium leakage, the third side heat exchanger 2 is combined with the flexible aluminum electrolytic cell shell proposed in this application, which can improve the heat exchange efficiency, and can reduce the temperature of the outer strong guard plate 4, and greatly improve the high temperature production environment of the electrolysis workshop.

[0037] The first and second side heat exchangers 2 are both suitable for the case where the heat exchange medium is a liquid. When the heat exchange medium is a liquid, the heat exchange medium is a nitrate, including one or more of sodium nitrate, potassium nitrate, calcium nitrate, ammonium nitrate, etc. When multiple components are used, the specific ratio of each component is not limited.

[0038] The third type of side heat exchanger 2 is suitable for the case where the heat exchange medium is gas. When the heat exchange medium is gas, the heat exchange medium is air or the like.

[0039] One or more temperature measuring units are also provided in the side heat exchanger 2. The temperature signal of the thermocouple in the temperature measuring unit is collected by the data acquisition module and the data transmission module of the temperature measuring unit, and then transmitted to the electrolytic cell controller by wireless or wired means, and then transmitted to the information control center. The flow rate, flow velocity, etc. of the heat exchange medium are adjusted according to the measured temperature.

[0040] When the current of aluminum electrolysis fluctuates, the heat exchange system can be used to adjust the side heat exchange to control the electrolysis temperature to fluctuate within the permitted range. Cooling and heat exchange: When wind power is at its peak, the aluminum electrolytic cell is used to enhance current production to adjust the peak. At this time, the enhanced current in the cell destroys the thermal balance, causing the shape of the furnace wall on the side of the cell to change. The temperature in the electrolytic cell 1 is balanced by adjusting the flow rate and flow velocity of the low-temperature heat exchange medium in the side heat exchanger 2, while realizing the side waste heat recovery.

[0041] Heating and insulation: When wind power is at a trough or there is no wind power transmission, a side molten salt heat exchanger is used to supplement heat on the side of the tank. Since the insulation bricks 7 fill the space between the inner heat conduction plate 3 and the electrolytic cell 1, heat is mainly exchanged through the side heat exchanger 2. By adjusting the flow rate and flow velocity of the high-temperature heat exchange medium in the side heat exchanger 2, the electrolytic cell 1 can maintain the electrolysis temperature as much as possible.

[0042] The present invention also proposes an electrolytic cell combined with a flexible aluminum electrolytic cell shell, in which one end of the cathode system 8 of the electrolytic cell 1 is arranged in the cathode system slot 5 of the shell, and an outer strong guard plate 4 is extended. Since the shell is extended outward as a whole, the busbar of the cathode system is also extended outward. The flow of the melt in the aluminum electrolytic cell is mainly driven by the strong electromagnetic field generated by the cathode busbar. The outward extension of the busbar position of the cathode system will cause the magnetic field in the melt area to be weakened, and then the flow rate in the melt area will be reduced, so that the fluctuation amplitude of the aluminum liquid / electrolyte interface is reduced, which is beneficial to improve the current utilization efficiency and reduce the risk of short circuit between the anode and cathode of the aluminum electrolytic cell. When the distance between the outer strong guard plate 4 and the inner heat conducting plate 3 is 10 cm, that is, the overall shell structure is extended outward by 10 cm relative to the electrolytic cell 1, it is expected to reduce the melt flow rate in the electrolytic cell 1 by 0.06 m / s, reduce the interface deformation by 0.4 cm, and improve the current utilization efficiency by 2-5%.

[0043] The heat exchanger on the side of the electrolytic cell 1 is used to carry out two-way heat exchange, which can control the heat balance on the side of the cell, and then adjust the shape change of the furnace wall caused by the current fluctuation to achieve flexible production. The waste heat of the aluminum electrolytic cell is theoretically 50% of the power consumption rate of aluminum electrolysis. If 10% of it is recovered through the side heat exchange, the equivalent power is 750kWh / ton of aluminum. At the same time, it can also be used for peak load regulation of the power grid. Calculated based on the current fluctuation of 50%, the peak load regulation power of an enterprise with an annual output of 1 million tons of aluminum is equivalent to the construction of a 750,000-kilowatt generator set, which has huge economic and social benefits.

[0044] The flexible aluminum electrolytic cell shell structure proposed by the present invention is suitable for electrolytic cells of various models.

[0045] Example 1 like Figure 5 As shown, a 3000A aluminum electrolytic cell test cell is built, nitrate heat exchange medium is used, the inner heat conduction plate 3 is made of 5mm thick stainless steel plate, the insulation material is ordinary insulation brick, the temperature of the side heat exchanger 2 is 700℃, the heat exchange medium outlet temperature is 350℃, the outer wall temperature of the tank shell is 40℃, the heat exchange efficiency of the side heat exchanger 2 is 83%, which is equivalent to saving about 1738 kWh of electricity per ton of aluminum; the current fluctuation varies by 85%, and the electrolytic aluminum production is stable.

[0046] When air is used for heat exchange, the outlet temperature of the heat exchange medium can reach 900°C. Under the condition of constant current, the heat exchange amount increases and the outlet temperature decreases.

[0047] Example 2 like Figure 6 As shown, a 10000A aluminum electrolysis test cell is built, nitrate heat exchange medium is used, the inner heat conduction plate 3 is made of 10mm thick stainless steel plate, the temperature of the side heat exchanger 2 is 750℃, the heat exchange medium outlet temperature is 400℃, the tank shell outer wall temperature is 45℃, and the heat exchange efficiency of the side heat exchanger 2 is 68%, which is equivalent to saving about 1423 kWh of electricity per ton of aluminum; the current fluctuation varies by 80%, and the electrolytic aluminum production is stable.

[0048] Example 3 like Figure 1 As shown, taking a 600kA large-scale industrial aluminum electrolytic cell as an example, a nitrate heat exchange medium is used, and the inner heat conduction plate 3 uses a 12mm thick stainless steel plate. When the electrolytic cell line current fluctuates downward by 40%, the current cannot guarantee the normal operation of the electrolytic cell. Increase the inlet temperature of the heat exchange medium and reduce the inlet flow of the heat exchange medium so that the high-temperature electrolyte can better transfer heat to the side of the electrolytic cell 1. At the same time, heat insulation cotton is arranged outside the outer strong guard plate 4 to reduce heat transfer to the air. In this embodiment, the side heat exchanger 2 is used for heat preservation, so that the electrolytic cell 1 can continue to maintain the melt temperature in the cell under low current electrolysis conditions.

Claims

1. A flexible aluminum electrolysis cell shell, characterized in that: include, An outer strong guard plate (4) is arranged on the outer circumference of the electrolytic cell (1); The inner heat conducting plate (3) is arranged inside the outer strong protective plate (4), contacts the tank lining structure (11) of the electrolytic tank (1), corresponds to the position of the aluminum liquid (10) and the electrolyte (9), and forms a double-layer tank shell structure with the inner heat conducting plate (3); A blocking plate (6) is arranged between the inner heat conducting plate (3) and the outer strong protective plate (4); The side heat exchanger (2) is arranged in a space surrounded by the inner heat conduction plate (3), the outer strong protection plate (4) and the blocking plate (6), and contacts the inner heat conduction plate (3); Insulation bricks (7) are filled in the area between the outer strong protective plate (4) and the electrolytic cell (1); The cathode system slot (5) is opened in the insulation brick (7) below the blocking plate (6) and penetrates the outer strong protective plate (4).

2. The flexible aluminum electrolysis cell shell according to claim 1, characterized in that: The inner heat conducting plate (3) and the blocking plate (6) are an integral structure arranged vertically, and the cross section of the integral structure is L-shaped.

3. The flexible aluminum electrolysis cell shell according to claim 1, characterized in that: The outer strong guard plate (4) and The distance between the inner heat conducting plates (3) is at least 10 cm.

4. The flexible aluminum electrolysis cell shell according to claim 1, characterized in that: The inner heat conducting plate (3) is made of stainless steel material resistant to electrolyte corrosion, has a thickness of 5-20 mm, a thermal conductivity of at least 100 W / mk, and a high temperature resistance of at least 700°C.

5. The flexible aluminum electrolysis cell shell according to claim 1, characterized in that: The distance h between the blocking plate (6) and the upper surface of the cathode system (8) is ≥ 0.75d, where d is the deformation of the outer strong guard plate (4) in the width direction, in units of mm.

6. The flexible aluminum electrolysis cell shell according to claim 1, characterized in that: The side heat exchanger (2) is a structure in which a plurality of liquid heat exchange pipes (21) are arranged in parallel and are arranged on the inner wall of the inner heat conduction plate (3). The upper and lower ends of each liquid heat exchange pipe (21) are respectively connected to a first inlet (211) and a second inlet (212), and an outlet (213) is provided in the middle. The liquid heat exchange pipe (21) between the first inlet (211) and the outlet (213) corresponds to the electrolyte (9) of the electrolytic cell (1), and the liquid heat exchange pipe (21) between the second inlet (212) and the outlet (213) corresponds to the aluminum liquid (10) of the electrolytic cell (1).

7. The flexible aluminum electrolysis cell shell according to claim 1, characterized in that: The side heat exchanger (2) is a structure in which a double-tube liquid heat exchange pipe (22) is arranged in an S shape and is arranged on the inner wall of the inner heat conduction plate (3), wherein two adjacent ports of the double-tube liquid heat exchange pipe (22) are a liquid inlet (221) and a liquid outlet (222), and the heat exchange medium in the two pipes of the double-tube liquid heat exchange pipe (22) flows in opposite directions.

8. The flexible aluminum electrolysis cell shell according to claim 1, characterized in that: The side heat exchanger (2) is a structure in which a plurality of gas heat exchange pipes (23) are arranged in parallel and are arranged on the inner wall of the inner heat conduction plate (3); one end of the gas heat exchange pipe (23) is connected to the gas inlet (231), and the other end is connected to the gas outlet (232); a plurality of staggered metal baffles are arranged inside the gas heat exchange pipe (23), and the end connected to the gas outlet (232) is arranged to have a structure with a gradually decreasing inner diameter.

9. The flexible aluminum electrolysis cell shell according to claim 1, characterized in that: When the heat exchange medium is liquid, the heat exchange medium is nitrate; the nitrate includes one or more of sodium nitrate, potassium nitrate, calcium nitrate and ammonium nitrate.

10. A flexible aluminum electrolysis cell, comprising the flexible aluminum electrolysis cell shell according to any one of claims 1 to 9, wherein one end of the cathode system (8) is arranged in the cathode system cell (5) and extends outwardly from a strong outer protective plate (4).

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