Heat recovery system

Abstract

The utility model belongs to the field of energy storage technology discloses a kind of waste heat recovery systems.The system includes waste heat recovery module, at least one heat exchange unit and external heat recovery module, and waste heat recovery module is provided with flue gas passage for flue gas flow;All heat exchange units are arranged in waste heat recovery module, and are heat transfer connection with flue gas passage, and heat exchange unit can be exchanged heat with the flue gas of flue gas passage by the heat storage medium flowing in it;Flue gas outlet end of external heat recovery module is communicated with flue gas inlet end of waste heat recovery module by first pipeline, and external heat recovery module can pre-recovery the heat energy of flue gas into waste heat recovery module, to control the temperature of flue gas into waste heat recovery module;Wherein, the flue gas input by the flue gas inlet end of waste heat recovery system can be transported to the flue gas inlet end of external heat recovery module by No.1 input pipeline.The system can prevent flue gas and molten salt heat exchange from causing molten salt overtemperature, and improve the use safety reliability of system.

Description

Technical Field

[0001] This utility model relates to the field of energy storage technology, and in particular to a waste heat recovery system. Background Technology

[0002] Currently, in the field of industrial silicon flue gas waste heat recovery, conventional waste heat boilers are commonly used for heat recovery. These boilers utilize the waste heat from the flue gas to generate steam, which drives a turbine to generate electricity. Since conventional waste heat recovery systems lack energy storage systems, the waste heat energy from the flue gas is used immediately. With the widening gap between peak and off-peak electricity prices, it is worth considering configuring energy storage systems to store the heat from the flue gas during off-peak hours and release it during peak hours, thereby achieving peak-valley arbitrage.

[0003] Currently, molten salt energy storage systems can be configured to store waste heat from flue gas during off-peak hours and release it during peak hours, achieving peak shaving and valley filling, and peak-valley arbitrage. However, since the temperature of industrial silicon flue gas is generally 500-600℃, it can rise to 800-1000℃ within 10-20 minutes during furnace shut-off. This can cause the molten salt in the boiler to overheat and decompose, posing a safety risk.

[0004] Therefore, it is necessary to design a waste heat recovery system to solve the problems existing in the current technology. Utility Model Content

[0005] The purpose of this invention is to provide a waste heat recovery system to reduce the risk of overheating and decomposition of molten salt in molten salt boilers and improve the safety and stability of its use.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] Waste heat recovery system, including:

[0008] Waste heat recovery module, wherein a flue gas channel for flue gas flow is provided in the waste heat recovery module;

[0009] At least one heat exchange unit, all of which are disposed within the waste heat recovery module and are heat-transfer connected to the flue gas passage, wherein the heat exchange unit is configured to exchange heat with the flue gas entering the flue gas passage through a heat storage medium flowing therein.

[0010] An external heat recovery module, wherein the flue gas outlet of the external heat recovery module is connected to the flue gas inlet of the waste heat recovery module through a first pipeline, and the external heat recovery module is configured to pre-recover the heat energy of the flue gas entering the waste heat recovery module in order to control the temperature of the flue gas entering the waste heat recovery module.

[0011] The flue gas input at the flue gas inlet of the waste heat recovery system can be transported to the flue gas inlet of the external heat recovery module through the No. 1 input pipeline.

[0012] Preferably, the system also includes a flue gas flow path control module, which includes a temperature detection unit, a first baffle group unit, and a second baffle group unit.

[0013] The first baffle group unit is provided on the first input pipeline;

[0014] The flue gas input to the waste heat recovery system can be transported to the flue gas inlet of the waste heat recovery module through the second input pipeline, and the second baffle group unit is provided on the second input pipeline;

[0015] The temperature detection unit can detect the temperature of the flue gas input into the waste heat recovery system, and control the opening or closing of the first baffle group unit and the second baffle group unit according to the preset temperature.

[0016] As a preferred option, a second pipeline is also included;

[0017] The flue gas outlet of the waste heat recovery system is connected to the first pipeline via a second pipeline.

[0018] Preferably, it also includes a third baffle group unit and a fourth baffle group unit;

[0019] The third baffle assembly unit is provided on the first pipeline;

[0020] The flue gas output end of the second input pipeline is connected to the first pipeline, and the connection between the flue gas output end of the second input pipeline and the first pipeline is located between the flue gas outlet end of the external heat recovery module and the third baffle group unit.

[0021] The connection point between the flue gas output end of the second input pipeline and the first pipeline is taken as the first connection point;

[0022] The second pipeline is equipped with the fourth baffle unit, and the connection between the flue gas inlet of the second pipeline and the first pipeline is located between the first connection point and the third baffle unit.

[0023] Preferably, the external heat recovery module includes a first heat recovery unit and a second heat recovery unit;

[0024] The flue gas output end of the first input pipeline is connected to the flue gas inlet end of the first heat recovery unit, and the flue gas outlet end of the first heat recovery unit is connected to the flue gas inlet end of the second heat recovery unit through the third pipeline.

[0025] The flue gas inlet of the first pipeline is connected to the flue gas outlet of the second heat recovery unit.

[0026] Preferably, the first heat recovery unit is a heat storage brick, and the second heat recovery unit is a water-cooled heat exchanger.

[0027] Preferably, the waste heat recovery module includes a first heat exchange unit, a second heat exchange unit, and a third heat exchange unit;

[0028] The third heat exchange unit, the second heat exchange unit and the first heat exchange unit are arranged sequentially at a preset distance interval in the flue gas channel along the first flue gas flow direction;

[0029] The heat storage medium output end of the first heat exchange unit is connected to the heat storage medium input end of the second heat exchange unit through a fourth pipeline, and the heat storage medium output end of the second heat exchange unit is connected to the heat storage medium input end of the third heat exchange unit through a fifth pipeline.

[0030] Wherein, the flow direction of the flue gas entering the flue gas channel is the first flue gas flow direction; the heat storage medium input end of the first heat exchange unit is the low-temperature first heat storage medium input end of the waste heat recovery module, and the heat storage medium output end of the third heat exchange unit is the high-temperature first heat storage medium output end of the waste heat recovery module.

[0031] Preferably, it also includes a sixth pipeline, a first valve assembly, and a second valve assembly;

[0032] The heat storage medium input end of the first heat exchange unit is connected to the fifth pipeline through the sixth pipeline, the first valve assembly is disposed on the sixth pipeline, and the second valve assembly is disposed on the sixth pipeline;

[0033] The connection point between the heat storage medium input end of the sixth pipeline and the heat storage medium input end of the first heat exchange unit is taken as the second connection point, and the connection point between the heat storage medium output end of the sixth pipeline and the fifth pipeline is taken as the third connection point.

[0034] The first valve assembly is located near the second connection point, and the second valve assembly is located near the third connection point.

[0035] Preferably, the heat exchange unit further includes a fourth heat exchange unit;

[0036] Along the first flue gas flow direction, the fourth heat exchange unit is disposed at a preset distance behind the first heat exchange unit;

[0037] The heat storage medium input terminal of the fourth heat exchange unit is the second heat storage medium input terminal of the waste heat recovery module, and the heat storage medium output terminal of the fourth heat exchange unit is the second heat storage medium output terminal of the waste heat recovery module.

[0038] The first heat storage medium is molten salt, and the second heat storage medium is cooling water or demineralized water.

[0039] Preferably, a first header is provided at the heat storage medium input end of the first heat exchange unit, and a second header is provided at the heat storage medium output end of the first heat exchange unit.

[0040] A third header is provided at the heat storage medium input end of the second heat exchange unit, and a fourth header is provided at the heat storage medium output end of the second heat exchange unit.

[0041] A fifth header is provided at the heat storage medium input end of the third heat exchange unit, and a sixth header is provided at the heat storage medium output end of the third heat exchange unit.

[0042] A seventh header is provided at the heat storage medium input end of the fourth heat exchange unit, and an eighth header is provided at the heat storage medium output end of the fourth heat exchange unit.

[0043] The flue gas passage is U-shaped, and the first flue gas flow direction is U-shaped.

[0044] The beneficial effects of this utility model are as follows: This utility model provides a waste heat recovery system. In this device, by setting an external heat recovery module before the flue gas channel inlet, the flue gas discharged from the flue gas outlet (i.e., the flue gas inlet of the waste heat recovery system) whose temperature is not within the preset safe range can be intercepted by the external heat recovery module first, and part / all of the heat is recovered in the external heat recovery module. The purpose of the external heat recovery module recovering the heat energy of the flue gas is to reduce the temperature of the flue gas entering the waste heat recovery module in advance, so as to prevent the molten salt from overheating when the flue gas temperature rises further during the furnace turnover and exchanges heat with the molten salt, thereby improving the safety and reliability of the system. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of the flue gas waste heat recovery system provided in this embodiment of the utility model.

[0046] In the picture:

[0047] 1. Waste heat recovery module; 101. Flue gas passage; 2. Heat exchange unit; 201. First heat exchange unit; 202. Second heat exchange unit; 203. Third heat exchange unit; 204. Fourth heat exchange unit; 205. First header; 206. Second header; 207. Third header; 208. Fourth header; 209. Fifth header; 210. Sixth header; 211. Seventh header; 212. Eighth header; 3. External heat recovery module; 301. First heat recovery unit; 3 02. Second heat recovery unit; 3021. Ninth header; 3022. Fifth heat exchange unit; 3023. Tenth header; 4. First pipeline; 5. First input pipeline; 601. First baffle assembly unit; 602. Second baffle assembly unit; 7. Second input pipeline; 8. Second pipeline; 9. Third baffle assembly unit; 10. Fourth baffle assembly unit; 11. Fourth pipeline; 12. Fifth pipeline; 13. Sixth pipeline; 14. First valve assembly; 15. Second valve assembly. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0049] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0050] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0051] In the description of this embodiment, the terms "upper," "lower," "right," and "left," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0052] Currently, existing markets offer solutions for storing waste heat from flue gas during off-peak hours and releasing it during peak hours using molten salt energy storage systems, thus achieving peak shaving and arbitrage. However, since the temperature of industrial silicon flue gas is generally between 500-600℃, it can rise to 800-1000℃ within 10-20 minutes during furnace shutdown. This can lead to overheating and decomposition of the molten salt in the boiler, posing a safety risk.

[0053] To address the shortcomings of existing technologies, this invention provides a waste heat recovery system to solve the problem of molten salt overheating and decomposition during heat exchange, thereby improving the safety of the device.

[0054] Example 1

[0055] This embodiment provides a waste heat recovery system, including a waste heat recovery module 1, at least one heat exchange unit 2, and an external heat recovery module 3. The waste heat recovery module 1 has a flue gas channel 101 for flue gas flow. All heat exchange units 2 are located within the waste heat recovery module 1 and are heat-transfer connected to the flue gas channel 101. Each heat exchange unit 2 is configured to exchange heat with the flue gas entering the flue gas channel 101 through a heat storage medium flowing within it. The flue gas outlet of the external heat recovery module 3 is connected to the flue gas inlet of the waste heat recovery module 1 via a first pipe 4. The external heat recovery module 3 is configured to pre-recover the heat energy of the flue gas entering the waste heat recovery module 1 to control the temperature of the flue gas entering the waste heat recovery module 1. The flue gas input to the flue gas inlet of the waste heat recovery system can be transported to the flue gas inlet of the external heat recovery module 3 via a first input pipe 5.

[0056] Specifically, refer to Figure 1As shown, this embodiment includes at least one heat exchange unit 2 within the flue gas channel 101 of the waste heat recovery module 1. As the flue gas flows along the flue gas channel 101, the heat storage medium, which has a temperature difference with the flue gas, exchanges heat with the flue gas in the heat exchange unit 2, absorbing the heat energy from the flue gas. This heat energy is then used to heat the low-temperature heat storage medium to form a high-temperature heat storage medium, which is released during peak electricity consumption periods, thus achieving peak-valley arbitrage. Furthermore, by installing an external heat recovery module 3 before the waste heat recovery module 1, the flue gas discharged from the flue gas outlet (i.e., the flue gas inlet of the waste heat recovery system) can be intercepted by the external heat recovery module 3 and pre-recover all / part of the heat energy of the flue gas entering the waste heat recovery module 1, thereby controlling the temperature of the flue gas entering the waste heat recovery module 1 and preventing the heat storage medium of the waste heat recovery module 1 from overheating.

[0057] It should be noted that, in this embodiment of the technical solution, no restrictions are placed on how the external heat recovery module 3 cools the high-temperature flue gas, as long as the temperature of the flue gas entering the waste heat recovery module 1 can be controlled. Furthermore, in this embodiment, the flue gas refers to a high-temperature gas and does not represent any specific flue gas component; the design can be tailored to specific flue gas compositions. Similarly, the connection method between the heat exchange units 2 within the waste heat recovery module 1 is not limited. For example, the heat exchange units 2 can be connected in series within the waste heat recovery module 1, while in other embodiments of this technical solution, they can be connected in parallel within the waste heat recovery module 1, depending on the specific circumstances.

[0058] In this embodiment, a flue gas flow path control module is also included. The flue gas flow path control module includes a temperature detection unit, a first baffle group unit 601, and a second baffle group unit 602. The first baffle group unit 601 is provided on the first input pipe 5. The flue gas input to the waste heat recovery system can be transported to the flue gas inlet end of the waste heat recovery module 1 through the second input pipe 7. The second baffle group unit 602 is provided on the second input pipe 7. The temperature detection unit can detect the temperature of the flue gas input to the waste heat recovery system and control the opening or closing of the first baffle group unit 601 and the second baffle group unit 602 according to the preset temperature.

[0059] For details, please refer to Figure 1As shown, the flue gas discharged from the flue gas outlet (i.e., the flue gas inlet entering the waste heat recovery system) can also be transported to the waste heat recovery module 1 through the second input pipe 7. A first baffle group unit 601 is installed on the first input pipe 5, and a second baffle group unit 602 is installed on the second input pipe 7. The temperature detection unit can detect the temperature of the flue gas. For example, when the temperature of the flue gas is within a preset safety range (i.e., the temperature of the flue gas will not cause the heat storage medium in the waste heat recovery module 1 to overheat), the temperature detection unit will control the second baffle group unit 602 to open. The first baffle unit 601 is closed, allowing the flue gas to enter the waste heat recovery module 1 through the second input pipe 7. When the temperature of the flue gas is outside the preset safe range (i.e., when the temperature of the flue gas causes the heat storage medium in the waste heat recovery module 1 to overheat), the temperature detection unit will control the first baffle unit 601 to open and the second baffle unit 602 to close, allowing the flue gas to enter the external heat recovery module 3 through the first input pipe 5. The external heat recovery module 3 will reduce the temperature of the flue gas to the preset safe range before it enters the waste heat recovery module 1. Of course, in the embodiments of this technical solution, by controlling the first baffle group unit 601, the shut-off, connection and flow regulation of the first input pipeline 5 can be realized, and by controlling the second baffle group unit 602, the shut-off, connection and flow regulation of the second input pipeline 7 can be realized. Of course, the first baffle group unit 601 can be a single baffle or a baffle group formed by multiple baffles, and the second baffle group unit 602 can be a single baffle or a baffle group formed by multiple baffles. This technical solution does not limit the first baffle group unit 601 and the second baffle group unit 602, and can be specifically designed according to the actual situation.

[0060] In this embodiment, a second pipeline 8 is also included; the flue gas outlet of the waste heat recovery system is connected to the first pipeline 4 via the second pipeline 8. Specifically, refer to... Figure 1 As shown, the flue gas passing through the external heat recovery module 3 and / or the second baffle unit 602 can also be discharged directly to the outside of the entire waste heat recovery system through the second pipeline 8 without entering the waste heat recovery module 1. By adopting this scheme, it is possible to effectively prevent the flue gas whose temperature is still not within the preset safe range after being reduced by the external heat recovery module 3 from entering the waste heat recovery module 1, thereby causing the heat storage medium in the waste heat recovery module 1 to overheat. In addition, it can also discharge the flue gas that the waste heat recovery module 1 cannot contain, thereby ensuring the safety of the entire waste heat recovery system.

[0061] Furthermore, it also includes a third baffle group unit 9 and a fourth baffle group unit 10; the third baffle group unit 9 is provided on the first pipeline 4; the flue gas output end of the second input pipeline 7 is connected to the first pipeline 4, and the connection point between the flue gas output end of the second input pipeline 7 and the first pipeline 4 is located between the flue gas outlet end of the external heat recovery module 3 and the third baffle group unit 9; the connection point between the flue gas output end of the second input pipeline 7 and the first pipeline 4 is taken as the first connection point; the fourth baffle group unit 10 is provided on the second pipeline 8, and the connection point between the flue gas input end of the second pipeline 8 and the first pipeline 4 is located between the first connection point and the third baffle group unit 9.

[0062] For example, when the device needs maintenance or the waste heat recovery module 1 malfunctions, the fourth baffle unit 10 opens and the third baffle unit 9 closes, so that the flue gas passage 101 is disconnected, allowing the flue gas to be discharged from the second input pipe 7 through the second pipe 8, bypassing the waste heat recovery module 1 and being discharged to the outside, so that the staff can carry out maintenance and ensure personal safety.

[0063] In this embodiment, the external heat recovery module 3 includes a first heat recovery unit 301 and a second heat recovery unit 302; the flue gas output end of the first input pipeline 5 is connected to the flue gas inlet end of the first heat recovery unit 301, and the flue gas outlet end of the first heat recovery unit 301 is connected to the flue gas inlet end of the second heat recovery unit 302 through a third pipeline; the flue gas input end of the first pipeline 4 is connected to the flue gas outlet end of the second heat recovery unit 302.

[0064] For details, please refer to Figure 1 As shown, the external heat recovery module 3 includes a first heat recovery unit 301 and a second heat recovery unit 302. The flue gas outlet of the first heat recovery unit 301 is connected to the flue gas inlet of the second heat recovery unit 302. The first heat recovery unit 301 is used to absorb and store the heat energy in the flue gas whose temperature is outside the preset safety range, while the second heat recovery unit 302 can cool the flue gas to a preset temperature (i.e., flue gas whose temperature is within the preset safety range). By configuring the first heat recovery unit 301 and the second heat recovery unit 302, not only can the temperature of the flue gas at the inlet of the flue gas channel 101 (i.e., the flue gas inlet of the waste heat recovery module 1) be effectively controlled, but also some of the heat in the flue gas whose temperature is outside the preset safety range can be recovered. Subsequently, the heat stored in the first heat recovery unit 301 can be used for external equipment, thereby avoiding heat waste and further enhancing the heat recovery capability of the device.

[0065] The first heat recovery unit 301 can use heat storage bricks, such as magnesia high-temperature heat storage bricks, which have a heat storage capacity per unit volume that far exceeds that of traditional refractory bricks, thereby significantly improving the heat storage capacity of the first heat recovery unit 301. In addition, magnesia high-temperature heat storage bricks have high compressive strength under high pressure, can withstand long-term operating loads, and have strong corrosion resistance to acidic flue gas (such as flue gas containing SO2), thus having a longer service life, effectively reducing replacement costs and improving economic efficiency.

[0066] The second heat recovery unit 302 includes a ninth header 3021, a fifth heat exchange unit 3022, and a tenth header 3023 connected in sequence. The flue gas inlet of the fifth heat exchange unit 3022 is connected to the flue gas outlet of the first heat recovery unit 301, and the flue gas outlet of the fifth heat exchange unit 3022 is connected to the inlet of the flue gas passage 101 (i.e., the flue gas inlet of the waste heat recovery module 1). The fifth heat exchange unit 3022 can be a water-cooled heat exchanger. That is, when it is necessary to store the heat obtained after heat exchange with the flue gas, the heat exchange medium can be demineralized water. If it is not necessary to store this part of the heat, the heat exchange medium is cooling water. The temperature of the flue gas discharged from the second heat recovery unit 302 can be controlled by controlling the flow rate of the demineralized water or cooling water in the second heat recovery unit 302.

[0067] In practical use, for example, cooling water or demineralized water enters the water-cooled pipe of the fifth heat exchange unit 3022 through the ninth header 3021. In the fifth heat exchange unit 3022, heat exchange occurs with the flue gas, cooling the flue gas. The cooled flue gas is then transported to the flue gas channel 101 through the flue gas outlet end of the fifth heat exchange unit 3022. After the heat exchange is completed, the cooling water or demineralized water is output from the tenth header 3023 along the water-cooled pipe for use.

[0068] Preferably, the first heat recovery unit 301 is a heat storage brick, and the second heat recovery unit 302 is a water-cooled heat exchanger.

[0069] Preferably, in this embodiment, the waste heat recovery module 1 is a molten salt waste heat boiler.

[0070] Example 2

[0071] This embodiment provides a waste heat recovery system. Based on Embodiment 1, the waste heat recovery module 1 includes a first heat exchange unit 201, a second heat exchange unit 202, and a third heat exchange unit 203. The third heat exchange unit 203, the second heat exchange unit 202, and the first heat exchange unit 201 are sequentially arranged at preset distances along the first flue gas flow direction in the flue gas channel 101. Preferably, in this embodiment, the flue gas channel 101 is U-shaped so that the first flue gas flow direction is U-shaped. The heat storage medium output end of the first heat exchange unit 201 is connected to the third heat exchange unit 203. The four-pipe 11 is connected to the heat storage medium input end of the second heat exchange unit 202, and the heat storage medium output end of the second heat exchange unit 202 is connected to the heat storage medium input end of the third heat exchange unit 203 through the fifth pipe 12; wherein, the flow direction of the flue gas entering the flue gas channel 101 is the first flue gas flow direction; the heat storage medium input end of the first heat exchange unit 201 is the low-temperature first heat storage medium input end of the waste heat recovery module 1, and the heat storage medium output end of the third heat exchange unit 203 is the high-temperature first heat storage medium output end of the waste heat recovery module 1.

[0072] For details, please refer to Figure 1 As shown, the first heat storage medium is molten salt; of course, in other embodiments, the heat storage medium can also be liquid metal or other media that can match the specific application environment of the waste heat recovery system. The third heat exchange unit 203, the second heat exchange unit 202, and the first heat exchange unit 201 are sequentially arranged at preset distances along the first flue gas flow direction in the flue gas channel 101. In the waste heat recovery module 1, the third heat exchange unit 203 is closer to the flue gas inlet end of the waste heat recovery module 1 (i.e., the inlet end of the flue gas channel 101) than the second heat exchange unit 202 and the first heat exchange unit 201, while the first heat exchange unit 201 is closer to the waste heat recovery module 1 than the second heat exchange unit 202 and the third heat exchange unit 203. At the flue gas outlet end of block 1 (i.e., the outlet end of flue gas channel 101), the low-temperature molten salt enters the waste heat recovery module 1 through the heat storage medium input end of the first heat exchange unit 201, and passes through the first heat exchange unit 201, the second heat exchange unit 202 and the third heat exchange unit 203 in sequence. In each heat exchange unit 2, it exchanges heat with the flue gas in the flue gas channel 101, and then uses the heat energy of the flue gas to heat the low-temperature molten salt into high-temperature molten salt, which is then output through the heat storage medium output end of the third heat exchange unit 203 for later use.

[0073] Of course, in the embodiments of this technical solution, the specific locations of the third heat exchange unit 203, the second heat exchange unit 202, and the first heat exchange unit 201 in the waste heat recovery module 1 are not subject to excessive restrictions, and can be designed according to actual conditions. For example, the third heat exchange unit 203, the second heat exchange unit 202, and the first heat exchange unit 201 can be respectively a molten salt high-temperature heat exchanger, a molten salt medium-temperature heat exchanger, and a molten salt low-temperature heat exchanger, so as to sequentially form a high-temperature heat exchange zone, a medium-temperature heat exchange zone, and a low-temperature heat exchange zone along the flow direction of flue gas in the waste heat recovery module 1, so that the heat exchange unit 2 and the flue gas can be more fully exchanged.

[0074] It is understood that this utility model does not limit the type of molten salt heat exchange unit 2 in the heat exchange unit 2. For example, in other parallel embodiments, several heat exchange units 2 may also include a secondary high temperature molten salt heat exchange unit 2, a secondary medium temperature molten salt heat exchange unit 2, or a secondary low temperature molten salt heat exchange unit 2, so as to form a secondary high temperature heat exchange zone, a secondary medium temperature heat exchange zone, or a secondary low temperature heat exchange zone in the waste heat recovery module 1, respectively. Among them, the heat exchange temperature range of the secondary high temperature heat exchange zone is between the heat exchange temperature range of the high temperature heat exchange zone and the medium temperature heat exchange zone; the heat exchange temperature range of the secondary medium temperature heat exchange zone is between the heat exchange temperature range of the medium temperature heat exchange zone and the low temperature heat exchange zone; the heat exchange temperature range of the secondary low temperature heat exchange zone is smaller than the heat exchange temperature range of the low temperature heat exchange zone, thereby forming a temperature range with a richer heat exchange temperature hierarchy in the waste heat recovery module 1, further enhancing the heat exchange capacity between the device and the flue gas.

[0075] By using the aforementioned stepped heat exchange units 2, on the one hand, the molten salt can exchange heat more fully with the flue gas; on the other hand, each heat exchange unit 2 can use different materials according to its temperature zone, thereby reducing costs.

[0076] In this embodiment, a sixth pipeline 13, a first valve assembly 14, and a second valve assembly 15 are also included. The heat storage medium input end of the first heat exchange unit 201 is connected to the fifth pipeline 12 through the sixth pipeline 13. The first valve assembly 14 and the second valve assembly 15 are disposed on the sixth pipeline 13. The connection point between the heat storage medium input end of the sixth pipeline 13 and the heat storage medium input end of the first heat exchange unit 201 is the second connection point, and the connection point between the heat storage medium output end of the sixth pipeline 13 and the fifth pipeline 12 is the third connection point. The first valve assembly 14 is disposed near the second connection point, and the second valve assembly 15 is disposed near the third connection point.

[0077] For details, please refer to Figure 1As shown, the sixth pipe 13 is connected in parallel to the heat storage medium input end of the first heat exchange unit 201 and the heat storage medium input end of the third heat exchange unit 203. If the flue gas temperature discharged from the external heat recovery module 3 is still outside the preset safety range or the molten salt temperature at the heat storage medium input end of the third heat exchange unit 203 is too high, a portion of the low-temperature molten salt originally supplied to the first heat exchange unit 201 can be diverted to the sixth pipe 13 by opening the sixth pipe. On the one hand, this can increase the molten salt flow rate in the third heat exchange unit 203 to prevent the molten salt from overheating, that is, to ensure the fluidity of the molten salt in the third heat exchange unit 203, and to ensure that the molten salt after heat exchange with the flue gas in the third heat exchange unit 203 can be pushed out in time, thereby further preventing the accumulation of molten salt and the resulting temperature rise and overheating. On the other hand, mixing the low-temperature molten salt can also reduce the temperature of the molten salt input to the third heat exchange unit 203, thereby effectively preventing the molten salt from overheating.

[0078] Furthermore, the sixth pipeline 13 is provided with a first valve assembly 14 and a second valve assembly 15. The first valve assembly 14 is located near the heat storage medium input end of the first heat exchange unit 201, and the second valve assembly 15 is located near the heat storage medium input end of the third heat exchange unit 203. The first valve assembly 14 can adjust the molten salt flow rate at the input end of the heat storage medium in the sixth pipeline 13, thereby indirectly adjusting the molten salt flow rate into the first heat exchange unit 201. This ensures good heat exchange between the first heat exchange unit 201 and the flue gas, while also ensuring that the molten salt flowing out of the first heat exchange unit 201 is within a controllable flow rate range. The second valve assembly 15 can adjust the molten salt flow rate at the output end of the heat storage medium in the sixth pipeline 13, thereby indirectly adjusting the molten salt flow rate into the third heat exchange unit 203. This allows the third heat exchange unit 203 to precisely control the molten salt flow rate according to the specific temperature of the flue gas under the coordinated control of the first valve assembly 14 and the second valve assembly 15, ensuring sufficient heat exchange with the flue gas and preventing the molten salt from overheating.

[0079] Preferably, the first valve assembly 14 and the second valve assembly 15 each adopt a solenoid valve or a combination of multiple solenoid valves to realize the function of the corresponding valve assembly. Here, no excessive restrictions are placed on the first valve assembly 14 and the second valve assembly 15. They can be designed according to the actual situation. The valve opening degree can be automatically adjusted according to the actual temperature of the molten salt in the first heat exchange unit 201 and the third heat exchange unit 203, reducing human intervention and making the molten salt flow rate control more intelligent and automated.

[0080] In this embodiment, the heat exchange unit 2 further includes a fourth heat exchange unit 204; along the first flue gas flow direction, the fourth heat exchange unit 204 is disposed at a preset distance behind the first heat exchange unit 201; the heat storage medium input end of the fourth heat exchange unit 204 is the second heat storage medium input end of the waste heat recovery module 1, and the heat storage medium output end of the fourth heat exchange unit 204 is the second heat storage medium output end of the waste heat recovery module 1.

[0081] For details, please refer to Figure 1 As shown, the second heat storage medium is cooling water or demineralized water, and the fourth heat exchange unit 204 is located inside the waste heat recovery module 1 and is in thermal contact with the flue gas passage 101. In specific use, the cooling water or demineralized water enters the fourth heat exchange unit 204 through the heat storage medium input end of the fourth heat exchange unit 204, and exchanges heat with the flue gas in the flue gas passage 101 in the fourth heat exchange unit 204, heating the demineralized water or cooling water. After the heating is completed, the demineralized water or cooling water is discharged from the heat storage medium output end of the fourth heat exchange unit 204 for use, and the flue gas after the heat exchange is completed is discharged from the outlet end of the flue gas passage 101.

[0082] Of course, in other parallel embodiments, the heat exchange efficiency between the demineralized water or cooling water and the flue gas can also be adjusted by regulating the flow rate of the demineralized water or cooling water, so as to further ensure that the temperature of the flue gas can meet the emission standards.

[0083] Furthermore, a first header 205 is provided at the heat storage medium input end of the first heat exchange unit 201, and a second header 206 is provided at the heat storage medium output end of the first heat exchange unit 201; a third header 207 is provided at the heat storage medium input end of the second heat exchange unit 202, and a fourth header 208 is provided at the heat storage medium output end of the second heat exchange unit 202; a fifth header 209 is provided at the heat storage medium input end of the third heat exchange unit 203, and a sixth header 210 is provided at the heat storage medium output end of the third heat exchange unit 203; a seventh header 211 is provided at the heat storage medium input end of the fourth heat exchange unit 204, and an eighth header 212 is provided at the heat storage medium output end of the fourth heat exchange unit 204.

[0084] The working principle of the heat exchange unit 2 provided by this utility model is as follows: Low-temperature molten salt first enters the first heat exchange unit 201 through the first header 205. In the first heat exchange unit 201, it exchanges heat with the flue gas in the flue gas channel 101, thereby heating the low-temperature molten salt flowing in the first heat exchange unit 201. After heating, the molten salt is output through the second header 206, and enters the second heat exchange unit 202 through the third header 207 along the pipeline. In the second heat exchange unit 202, it exchanges heat with the flue gas in the flue gas channel 101, thereby heating the molten salt flowing in the second heat exchange unit 202. After heating, the molten salt is output through the fourth header 208, and enters the third heat exchange unit 203 through the fifth header 209 along the pipeline. In the third heat exchange unit 203, it exchanges heat with the flue gas in the flue gas channel 101, thereby heating the molten salt flowing in the third heat exchange unit 203. After heating, the high-temperature molten salt is output through the sixth header 210.

[0085] When the first valve assembly 14 and the second valve assembly 15 are opened, part of the molten salt flowing to the first header 205 is diverted to the sixth pipeline 13, and after mixing with the molten salt flowing out of the fourth header 208, it flows to the fifth header 209, and then flows into the third heat exchange unit 203.

[0086] In this utility model, the device mainly includes the following two operating conditions:

[0087] Normal operating conditions: Under normal operating conditions, the molten salt in the first heat exchange unit 201 will not overheat. At this time, the second baffle assembly unit 602 is open, the first baffle assembly unit 601 is closed, and the flue gas enters the flue gas passage 101 from the second inlet pipe 7. Furthermore, both the first valve assembly 14 and the second valve assembly 15 are in the closed state.

[0088] Over-temperature condition: Under over-temperature conditions, after the over-temperature flue gas (i.e., flue gas with a temperature outside the preset safety range) exchanges heat with the molten salt in the first heat exchange unit 201, the molten salt is prone to over-temperature, which can easily lead to safety accidents. At this time, the second baffle group unit 602 closes and the first baffle group unit 601 opens, allowing the flue gas to enter the first input pipeline 5. It first passes through the first heat recovery unit 301 for heat exchange, storing most of the heat in the first heat recovery unit 301, and then flows through the second heat recovery unit 302. The outlet flue gas temperature is controlled by controlling the flow rate of cooling water or demineralized water to ensure that the flue gas temperature entering the flue gas channel 101 is within the preset safety range. Under this condition, the first valve assembly 14 and the second valve assembly 15 can automatically control their opening and closing by monitoring whether the actual temperature of the flue gas at the inlet end of the flue gas channel 101 is below the target temperature, so as to prevent the high-temperature molten salt in the third heat exchange unit 203 from over-temperature by diverting some low-temperature molten salt.

[0089] It should also be noted that when the overheating condition ends and the normal operating condition is resumed, the opening of the second baffle group unit 602 and the first baffle group unit 601 can be controlled to allow some flue gas to flow through the first heat recovery unit 301, while the other part of the flue gas enters the second input pipeline 7. This can not only recover this part of the high-temperature heat, but also cool the second heat recovery unit 302 to a certain extent, so that the second heat recovery unit 302 can be prepared for the next stage of furnace overheating.

[0090] Preferably, in this embodiment, the second baffle group unit 602, the first baffle group unit 601, the third baffle group unit 9, and the fourth baffle group unit 10 all adopt flue baffles. As can be seen from the prior art, flue baffles mainly achieve physical isolation through rubber / silicone sealing rings, which can effectively prevent flue gas backflow. In addition, flue baffles are mostly made of glass magnesium fireproof board or metal material, which greatly improves the temperature resistance of flue baffles, thereby extending their service life and thus having good sealing performance and durability.

[0091] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0092] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A waste heat recovery system, characterized in that, include: Waste heat recovery module (1), wherein a flue gas channel (101) for flue gas flow is provided in the waste heat recovery module (1); At least one heat exchange unit (2), all of the heat exchange units (2) are disposed in the waste heat recovery module (1) and are heat-transfer connected to the flue gas passage (101). The heat exchange unit (2) is configured to exchange heat with the flue gas entering the flue gas passage (101) through the heat storage medium flowing therein. An external heat recovery module (3) is provided, wherein the flue gas outlet of the external heat recovery module (3) is connected to the flue gas inlet of the waste heat recovery module (1) via a first pipeline (4). The external heat recovery module (3) is configured to pre-recover the heat energy of the flue gas entering the waste heat recovery module (1) in order to control the temperature of the flue gas entering the waste heat recovery module (1). The flue gas input at the flue gas inlet of the waste heat recovery system can be transported to the flue gas inlet of the external heat recovery module (3) through the No. 1 input pipeline (5).

2. The waste heat recovery system according to claim 1, characterized in that, It also includes a flue gas flow path control module, which includes a temperature detection unit, a first baffle group unit (601), and a second baffle group unit (602). The first baffle assembly unit (601) is provided on the first input pipeline (5). The flue gas input into the waste heat recovery system can be transported to the flue gas inlet end of the waste heat recovery module (1) through the second input pipeline (7), and the second baffle group unit (602) is provided on the second input pipeline (7). The temperature detection unit can detect the temperature of the flue gas input into the waste heat recovery system, and control the opening or closing of the first baffle group unit (601) and the second baffle group unit (602) according to the preset temperature.

3. The waste heat recovery system according to claim 2, characterized in that, It also includes a second pipeline (8); The flue gas outlet of the waste heat recovery system is connected to the first pipeline (4) via the second pipeline (8).

4. The waste heat recovery system according to claim 3, characterized in that, It also includes a third baffle assembly unit (9) and a fourth baffle assembly unit (10); The third baffle unit (9) is provided on the first pipeline (4); The flue gas output end of the second input pipe (7) is connected to the first pipe (4), and the connection between the flue gas output end of the second input pipe (7) and the first pipe (4) is located between the flue gas outlet end of the external heat recovery module (3) and the third baffle group unit (9). The connection point between the flue gas output end of the second input pipe (7) and the first pipe (4) is taken as the first connection point; The second pipeline (8) is provided with the fourth baffle group unit (10), and the connection between the flue gas inlet end of the second pipeline (8) and the first pipeline (4) is located between the first connection point and the third baffle group unit (9).

5. The waste heat recovery system according to claim 1, characterized in that, The external heat recovery module (3) includes a first heat recovery unit (301) and a second heat recovery unit (302); The flue gas output end of the first input pipeline (5) is connected to the flue gas inlet end of the first heat recovery unit (301), and the flue gas outlet end of the first heat recovery unit (301) is connected to the flue gas inlet end of the second heat recovery unit (302) through the third pipeline. The flue gas inlet of the first pipeline (4) is connected to the flue gas outlet of the second heat recovery unit (302).

6. The waste heat recovery system according to claim 5, characterized in that, The first heat recovery unit (301) is a heat storage brick, and the second heat recovery unit (302) is a water-cooled heat exchanger.

7. The waste heat recovery system according to any one of claims 1-6, characterized in that, The heat exchange unit (2) includes a first heat exchange unit (201), a second heat exchange unit (202) and a third heat exchange unit (203). The third heat exchange unit (203), the second heat exchange unit (202) and the first heat exchange unit (201) are arranged sequentially at a preset distance in the flue gas channel (101) along the first flue gas flow direction; The heat storage medium output end of the first heat exchange unit (201) is connected to the heat storage medium input end of the second heat exchange unit (202) through the fourth pipeline (11), and the heat storage medium output end of the second heat exchange unit (202) is connected to the heat storage medium input end of the third heat exchange unit (203) through the fifth pipeline (12). Wherein, the flow direction of the flue gas entering the flue gas channel (101) is the first flue gas flow direction; the heat storage medium input end of the first heat exchange unit (201) is the low temperature first heat storage medium input end of the waste heat recovery module (1), and the heat storage medium output end of the third heat exchange unit (203) is the high temperature first heat storage medium output end of the waste heat recovery module (1).

8. The waste heat recovery system according to claim 7, characterized in that, It also includes a sixth pipeline (13), a first valve assembly (14), and a second valve assembly (15); The heat storage medium input end of the first heat exchange unit (201) is connected to the fifth pipeline (12) through the sixth pipeline (13), the first valve assembly (14) is disposed on the sixth pipeline (13), and the second valve assembly (15) is disposed on the sixth pipeline (13); The connection point between the heat storage medium input end of the sixth pipeline (13) and the heat storage medium input end of the first heat exchange unit (201) is the second connection point, and the connection point between the heat storage medium output end of the sixth pipeline (13) and the fifth pipeline (12) is the third connection point. The first valve assembly (14) is located near the second connection point, and the second valve assembly (15) is located near the third connection point.

9. The waste heat recovery system according to claim 7, characterized in that, The heat exchange unit (2) also includes a fourth heat exchange unit (204); Along the first flue gas flow direction, the fourth heat exchange unit (204) is disposed at a preset distance behind the first heat exchange unit (201); The heat storage medium input end of the fourth heat exchange unit (204) is the second heat storage medium input end of the waste heat recovery module (1), and the heat storage medium output end of the fourth heat exchange unit (204) is the second heat storage medium output end of the waste heat recovery module (1). The first heat storage medium is molten salt, and the second heat storage medium is cooling water or demineralized water.

10. The waste heat recovery system according to claim 9, characterized in that, A first header (205) is provided at the heat storage medium input end of the first heat exchange unit (201), and a second header (206) is provided at the heat storage medium output end of the first heat exchange unit (201). A third header (207) is provided at the heat storage medium input end of the second heat exchange unit (202), and a fourth header (208) is provided at the heat storage medium output end of the second heat exchange unit (202). The third heat exchange unit (203) is provided with a fifth header (209) at the heat storage medium input end and a sixth header (210) at the heat storage medium output end. The fourth heat exchange unit (204) is provided with a seventh header (211) at the heat storage medium input end and an eighth header (212) at the heat storage medium output end. The flue gas passage (101) is U-shaped, and the first flue gas flow direction is U-shaped.

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