A combined flue gas waste heat recovery system

Abstract

The present invention discloses a combined flue gas waste heat recovery system, comprising a first heat storage chamber, a second heat storage chamber, a reversing valve and a high-efficiency heat exchanger; the two heat storage chambers are provided with a smoke inlet, an air outlet, a smoke outlet and an air inlet; the reversing valve is a four-way valve, provided with a switchable smoke inlet / air outlet and a reversing valve smoke outlet / air inlet, as well as a fixed reversing valve smoke outlet and a reversing valve air inlet; the reversing valve smoke inlet / air outlet and the reversing valve smoke outlet / air inlet are respectively connected to the heat storage chamber smoke outlet / air inlet and the heat storage chamber air inlet / smoke outlet in a switching manner; the high-efficiency heat exchanger comprises a high-efficiency heat exchange element; the reversing valve smoke outlet and the heat exchanger air outlet are connected to the interface of the high-efficiency heat exchanger. The device solves the problems of large resistance and high exhaust temperature of the heat storage chamber, reduces exhaust heat loss and system power consumption, improves the effect of flue gas waste heat recovery, and reduces the natural gas consumption of the product.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchanger equipment, and in particular to a combined flue gas waste heat recovery system. Background Art

[0002] High-temperature air combustion technology is a new type of combustion technology widely used in industrial furnaces, also known as heat storage combustion technology. The efficient heat storage system is an important equipment for the realization of this combustion technology. The efficient heat storage system uses the heat storage body as the medium to transfer the heat of the high-temperature flue gas to the combustion air, thereby heating the air entering the furnace and realizing the heat recovery of the high-temperature flue gas. At present, most of the efficient heat storage systems use the heat storage chamber alone. This heat storage chamber is a high-temperature, high-efficiency, compact heat exchange device that can preheat the combustion air to a very high temperature and has a high heat exchange efficiency. However, the gas resistance of this heat storage chamber is extremely large, and the exhaust temperature is also high, especially for small equipment. The exhaust temperature can only be guaranteed at 200°C under some necessary conditions. As a result, the exhaust heat loss of the entire combustion system is high and the power consumption is high, so the economy of the entire system needs to be improved. Summary of the invention

[0003] The object of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a combined flue gas waste heat recovery system.

[0004] The present invention is realized through the following technical scheme: a combined flue gas waste heat recovery system, connected to an aluminum melting furnace, comprising a first heat storage chamber, a second heat storage chamber, a reversing valve and a high-efficiency heat exchanger; the first heat storage chamber is provided with a heat storage chamber smoke inlet / air outlet, and a heat storage chamber smoke outlet / air inlet; the second heat storage chamber is provided with a heat storage chamber air outlet / smoke inlet, and a heat storage chamber air inlet / smoke outlet; the reversing valve is a four-way valve, provided with a reversing valve smoke inlet / air outlet, a reversing valve smoke outlet / air inlet, a reversing valve smoke outlet, and a reversing valve air inlet; the reversing valve smoke outlet and the reversing valve air inlet are both fixed inlets and outlets, the reversing valve smoke inlet / air outlet and the reversing valve smoke outlet / air inlet are both switchable channels, the reversing valve smoke inlet / air outlet and the reversing valve smoke outlet / air inlet are respectively connected to the heat storage chamber smoke outlet / air inlet and the heat storage chamber air inlet / smoke outlet in a switching manner; the high-efficiency heat exchanger comprises A high-efficiency heat exchange element, a heat exchanger air inlet, a heat exchanger air outlet, a heat exchanger smoke inlet, a heat exchanger smoke outlet, a first tube sheet and a second tube sheet; the high-efficiency heat exchange element is installed in the cavity of the high-efficiency heat exchanger, and its two ends are fixed by the first tube sheet and the second tube sheet respectively; the heat exchanger smoke inlet is located on one side of the first tube sheet, and the heat exchanger air outlet is located on one side of the second tube sheet, and the high-efficiency heat exchanger has a channel inside, which connects the heat exchanger smoke inlet with the heat exchanger air outlet respectively; the regenerator smoke inlet / air outlet is connected to the aluminum melting furnace, the regenerator smoke outlet / air inlet is connected to the reversing valve smoke inlet / air outlet, the reversing valve smoke outlet is connected to the heat exchanger smoke inlet, the heat exchanger air outlet is connected to the reversing valve air inlet, the reversing valve smoke outlet / air inlet is connected to the regenerator air inlet / smoke outlet, and the regenerator air outlet / smoke inlet is connected to the aluminum melting furnace.

[0005] Flue gas enters the regenerator from the regenerator flue gas inlet to heat the regenerator inside, then flows out from the regenerator flue gas outlet, enters the high-efficiency heat exchanger to heat the air, and is finally discharged from the heat exchanger flue gas outlet; air enters from the heat exchanger air inlet, is heated by the flue gas, then flows out from the heat exchanger air outlet, enters the regenerator to cool the regenerator inside, and at the same time the air is further heated, and finally enters the aluminum melting furnace to participate in combustion; this system is equipped with two regenerators, which can alternately supply combustion-supporting air to the aluminum melting furnace and discharge high-temperature flue gas, and the reversing valve is used to control the change of flue gas and air flow direction.

[0006] The first heat storage chamber and the second heat storage chamber are both provided with a refractory material layer, and ceramic ball heat storage bodies are installed in the two heat storage chambers. The refractory material layer can ensure that the heat storage chamber is not burned by high-temperature flue gas; the ceramic ball has the properties of high temperature resistance, high heat storage density, excellent thermal conductivity, high thermal shock resistance, corrosion resistance, slag resistance, oxidation resistance, etc., and has the advantages of sufficient structural strength, long service life, and low cost. The ceramic ball can be repeatedly heated and cooled.

[0007] The reversing valve is a reversing valve with a periodic reversing period. The reversing valve periodically acts to switch the airflow direction in the two heat storage chambers, and the two heat storage chambers are heated and cooled in turn.

[0008] The high-efficiency heat exchange element is a three-dimensional deformable tube, and a plurality of the three-dimensional deformable tubes are provided. Adjacent three-dimensional deformable tubes are closely connected to form a self-supporting structure with stable positioning. The three-dimensional deformable tube forms a self-supporting structure, which can save baffles, realize pure counterflow of flue gas and air, improve heat exchange efficiency, reduce resistance, and realize that the exhaust temperature is only 20°C higher than the ambient temperature. Without violating the law of conservation of energy, the flue gas temperature can be reduced to the lowest possible level.

[0009] The internal channel of the high-efficiency heat exchange element is an air channel, and the outside of the air channel and the cavity of the high-efficiency heat exchanger are smoke channels, and the airflow direction of the air channel is set in the opposite direction to the airflow direction of the smoke channel. The reverse setting of the airflow direction can make the heat exchange efficiency higher.

[0010] The three-dimensional deformed tube is a heat exchange tube with a high specific surface area. The three-dimensional deformed tube with a high specific surface area has a good heat exchange effect and is conducive to heat recovery.

[0011] A plurality of the three-dimensional deformed tubes form a heat exchange tube bundle, and the three-dimensional deformed tubes support each other through convex point contact, and form a circulation channel with axial multi-channels and longitudinal full-channels. The three-dimensional deformed tubes support each other through convex point contact, so that the heat exchange tube bundle structure is very compact, occupies a small space, and is easy to install; the circulation channel with axial multi-channels and longitudinal full-channels, the heat exchange medium flows in the three-dimensional deformed tube in the whole space without dead corners, there is no vortex point, and no scaling or dust accumulation will be formed.

[0012] The cross section of the three-dimensional deformation tube is nearly elliptical. The nearly elliptical cross section does not have the wear angle of the circular cross section, the wear amount of the three-dimensional deformation tube is greatly reduced, and dust will not accumulate.

[0013] The three-dimensional deformed tube is a round tube that is processed into a spiral shaped tube after secondary processing. The three-dimensional deformed tube with a spiral shaped tube shape makes the flow field formed by it very stable and uniform, without dead corners, and greatly reduces the probability of dust accumulation.

[0014] The high-efficiency heat exchanger of this system adopts three-dimensional deformed tubes as high-efficiency heat exchange elements, so the high-efficiency heat exchanger is also called "three-dimensional variable space high-efficiency heat exchanger".

[0015] Compared with the prior art, the advantages of the present invention are:

[0016] (1) The aluminum melting furnace adopts this system to overcome the disadvantage of large resistance of the heat storage chamber when using it alone, and also overcomes the disadvantage of not being able to be used in high temperature environment when using it alone.

[0017] (2) The aluminum melting furnace can improve the fuel combustion efficiency by using this system. This system can heat the combustion air to a higher temperature to facilitate the combustion of the fuel.

[0018] (3) This system can recover the waste heat of flue gas to the maximum extent. The three-dimensional variable space high-efficiency heat exchanger can reduce the exhaust temperature to only 20°C higher than the ambient temperature, thereby recovering the waste heat of flue gas to the maximum extent.

[0019] (4) This system can improve the thermal efficiency of the aluminum melting furnace. Since the exhaust gas temperature is reduced to a very low level, the corresponding exhaust gas heat loss is very small, and the thermal efficiency is correspondingly improved.

[0020] (5) This system has low resistance and can reduce system power consumption. The biggest disadvantage of using a heat storage chamber alone is its high resistance. However, adding a three-dimensional variable space high-efficiency heat exchanger can reduce a portion of the ceramic ball heat storage body, thereby significantly reducing resistance and reducing the power consumption of the induced draft fan.

[0021] (6) This system arranges the heat storage chamber before the three-dimensional variable space high-efficiency heat exchanger, which can also filter the flue gas and ensure the safety of the operation of the three-dimensional variable space high-efficiency heat exchanger.

[0022] (7) This system overcomes the shortcomings of high resistance and high exhaust temperature of the heat storage chamber system, and overcomes the shortcomings of the three-dimensional variable space high-efficiency heat exchanger that cannot be used at excessively high temperatures. It combines the advantages of the two in one, reduces the exhaust temperature while also reducing the system resistance, greatly saving natural gas and improving the economic benefits of the aluminum melting furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural schematic diagram of the arrangement of ceramic ball heat storage bodies in the heat storage chamber according to an embodiment of the present invention;

[0024] Figure 2 It is a structural schematic diagram of an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of a high-efficiency heat exchanger according to an embodiment of the present invention;

[0026] Figure 4 This is a schematic structural diagram of a three-dimensional deformation tube according to an embodiment of the present invention;

[0027] Figure 5 It is a side view of a three-dimensional deformation tube according to an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of the wear of a common round pipe in conventional use;

[0029] Figure 7 This is a schematic diagram of the anti-wear principle of the three-dimensional deformable tube using a high specific surface area tube in an embodiment of the present invention.

[0030] The meanings of the reference numerals in the figure are as follows: 1. Smoke inlet / air outlet of heat storage chamber; 2. Air outlet / smoke inlet of heat storage chamber; 3. Smoke outlet / air inlet of heat storage chamber; 4. Air inlet / smoke outlet of heat storage chamber; 5. Smoke inlet / air outlet of reversing valve; 6. Smoke outlet / air inlet of reversing valve; 7. Smoke outlet of reversing valve; 8. Air inlet of reversing valve; 9. Smoke inlet of heat exchanger; 10. Air outlet of heat exchanger; 11. Air inlet of heat exchanger; 12. Smoke outlet of heat exchanger; 13. First tube sheet; 14. Second tube sheet; 15. Three-dimensional deformed tube; 20. First heat storage chamber; 30. Second heat storage chamber; 40. Reversing valve; 50. High-efficiency heat exchanger. DETAILED DESCRIPTION

[0031] The content of the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0032] Example

[0033] See also Figures 1 to 5, is a combined flue gas waste heat recovery system, connected to the aluminum melting furnace, including a first regenerator 20, a second regenerator 30, a reversing valve 40 and a high-efficiency heat exchanger 50; the first regenerator 20 is provided with a regenerator flue gas inlet / air outlet 1 and a regenerator flue gas outlet / air inlet 3; the second regenerator 30 is provided with a regenerator air outlet / flue gas inlet 2 and a regenerator air inlet / flue gas outlet 4; the reversing valve 40 is a four-way valve, provided with a reversing valve flue gas inlet / air outlet 5 and a reversing valve flue gas outlet The reversing valve smoke outlet 7 and the reversing valve air inlet 8 are both fixed inlets and outlets, the reversing valve smoke inlet / air outlet 5 and the reversing valve smoke outlet / air inlet 6 are both switchable channels, the reversing valve smoke inlet / air outlet 5 and the reversing valve smoke outlet / air inlet 6 are respectively connected to the heat storage chamber smoke outlet / air inlet 3 and the heat storage chamber air inlet / smoke outlet 4 in a switching manner; the high-efficiency heat exchanger 50 includes High-efficiency heat exchange element, heat exchanger air inlet 11, heat exchanger air outlet 10, heat exchanger smoke inlet 9, heat exchanger smoke outlet 12, first tube sheet 13 and second tube sheet 14; the high-efficiency heat exchange element is installed in the cavity of the high-efficiency heat exchanger 50, and its two ends are fixed by the first tube sheet 13 and the second tube sheet 14 respectively; the heat exchanger smoke inlet 9 is located on one side of the first tube sheet 13, and the heat exchanger air outlet 10 is located on one side of the second tube sheet 14. The high-efficiency heat exchanger 50 has a channel inside, which transfers the heat exchange The heat storage chamber smoke inlet 9 is connected with the heat exchanger air outlet 10 respectively; the heat storage chamber smoke inlet / air outlet 1 is connected with the aluminum melting furnace, the heat storage chamber smoke outlet / air inlet 3 is connected with the reversing valve smoke inlet / air outlet 5, the reversing valve smoke outlet 7 is connected with the heat exchanger smoke inlet 9, the heat exchanger air outlet 10 is connected with the reversing valve air inlet 8, the reversing valve smoke outlet / air inlet 6 is connected with the heat storage chamber air inlet / smoke outlet 4, and the heat storage chamber air outlet / smoke inlet 2 is connected with the aluminum melting furnace.

[0034] Flue gas enters the regenerator from the regenerator flue gas inlet to heat the regenerator therein, then flows out from the regenerator flue gas outlet, enters the high-efficiency heat exchanger 50 to heat the air, and is finally discharged from the heat exchanger flue gas outlet 12; air enters from the heat exchanger air inlet 11, is heated by the flue gas, then flows out from the heat exchanger air outlet 10, enters the regenerator to cool the regenerator therein, and the air is further heated at the same time, and finally enters the aluminum melting furnace to participate in combustion; the system is provided with two regenerators, which can alternately supply combustion-supporting air to the aluminum melting furnace and discharge high-temperature flue gas, and the reversing valve 40 controls the change of the flow direction of the flue gas and air.

[0035] The first regenerator 20 and the second regenerator 30 are both provided with a refractory material layer, and ceramic ball regenerators are installed in both regenerators. The refractory material layer can ensure that the regenerator is not burned by high-temperature flue gas; the ceramic ball has the properties of high temperature resistance, high heat storage density, excellent thermal conductivity, high thermal shock resistance, corrosion resistance, slag resistance, oxidation resistance, etc., and has sufficient structural strength, long service life, and low cost. The ceramic ball can be repeatedly heated and cooled. Figure 1 The ceramic ball heat storage body installed in the heat storage chamber of the present application is a plurality of ceramic balls stacked in sequence, and the upper ceramic ball is placed between two lower ceramic balls to form a compact stacking structure.

[0036] The reversing valve 40 is a reversing valve 40 with a periodic reversing period. The reversing valve 40 acts periodically to switch the airflow direction in the two heat storage chambers, and the two heat storage chambers are heated and cooled in turn.

[0037] The high-efficiency heat exchange element is a three-dimensional deformable tube 15, and a plurality of three-dimensional deformable tubes 15 are provided. Adjacent three-dimensional deformable tubes 15 are close together to form a self-supporting structure with stable positioning. The three-dimensional deformable tube 15 forms a self-supporting structure, which can save baffles, realize pure counterflow of flue gas and air, improve heat exchange efficiency, reduce resistance, and reduce the exhaust temperature to only 20°C higher than the ambient temperature. Under the premise of not violating the law of conservation of energy, the flue gas temperature can be reduced to the lowest possible level. The three-dimensional deformable tube 15 can realize small end difference heat transfer, and the small end difference is the temperature difference between two fluids at one end of the heat exchanger. For example, in this embodiment, the air inlet temperature of a section of the heat exchanger is 40°C at the ambient temperature, and the exhaust temperature is 60°C. This concept can measure the maximum heat exchange capacity of the heat exchanger. The heat exchanger can achieve an exhaust temperature that is only 20°C higher than the ambient temperature.

[0038] The internal channel of the high-efficiency heat exchange element is an air channel, and the outside of the air channel and the cavity of the high-efficiency heat exchanger 50 are smoke channels, and the airflow direction of the air channel is set in the opposite direction to the airflow direction of the smoke channel. The reverse setting of the airflow direction can make the heat exchange efficiency higher.

[0039] The three-dimensional deformed tube 15 is a heat exchange tube with a high specific surface area. The three-dimensional deformed tube 15 with a high specific surface area has a good heat exchange effect and is helpful for heat recovery.

[0040] A plurality of three-dimensional deformed tubes 15 form a heat exchange tube bundle, and the plurality of three-dimensional deformed tubes 15 support each other through convex point contact, and form a circulation channel with axial multi-channels and longitudinal full-channels. The three-dimensional deformed tubes 15 support each other through convex point contact, so that the heat exchange tube bundle structure is very compact, occupies a small space, and is easy to install; the circulation channel with axial multi-channels and longitudinal full-channels, the heat exchange medium flows in the three-dimensional deformed tube 15 in the whole space without dead corners, there is no eddy point, and no scaling or dust accumulation will be formed.

[0041] The cross section of the three-dimensional deformation tube 15 is nearly elliptical. The nearly elliptical cross section does not have the wear angle of the circular cross section, the wear amount of the three-dimensional deformation tube 15 is greatly reduced, and dust will not accumulate.

[0042] The three-dimensional deformed tube 15 is a round tube that is processed into a spiral special-shaped tube after secondary processing. The three-dimensional deformed tube 15 of the spiral special-shaped tube shape makes the flow field formed by it very stable and uniform, without dead corners, and the probability of dust accumulation is greatly reduced.

[0043] The high-efficiency heat exchanger 50 of this system adopts the three-dimensional deformable tube 15 as a high-efficiency heat exchange element, so the high-efficiency heat exchanger 50 is also called a "three-dimensional variable space high-efficiency heat exchanger".

[0044] In this embodiment, the regenerator smoke inlet / air outlet 1 is the smoke inlet of the first regenerator 20 before the reversing valve 40 is actuated, and the high-temperature smoke in the aluminum melting furnace enters the first regenerator 20 from the regenerator smoke inlet / air outlet 1; after the reversing valve 40 is actuated, it is the air outlet of the first regenerator 20, and the combustion-supporting air enters the aluminum melting furnace from the regenerator smoke inlet / air outlet 1. The regenerator air outlet / smoke inlet 2 corresponds to the regenerator smoke inlet / air outlet 1. Before the reversing valve 40 is actuated, it is the air outlet of the second regenerator 30, and the combustion-supporting air enters the aluminum melting furnace from the regenerator air outlet / smoke inlet 2; after the reversing valve 40 is actuated, it is the smoke inlet, and the high-temperature smoke in the aluminum melting furnace enters the second regenerator 30 from the regenerator air outlet / smoke inlet 2. The regenerator smoke outlet / air inlet 3 can be switched according to the action of the reversing valve 40, and the principle is the same as that of the regenerator smoke inlet / air outlet 1 and the regenerator air outlet / smoke inlet 2. The regenerator air inlet / smoke outlet 4 can be switched according to the action of the reversing valve 40, and the principle is the same as that of the regenerator smoke inlet / air outlet 1 and the regenerator air outlet / smoke inlet 2. The reversing valve smoke inlet / air outlet 5 and the reversing valve smoke inlet / air inlet 6 correspond to the regenerator smoke inlet / air outlet 1 before the reversing valve 40 is actuated. The reversing valve smoke inlet / air outlet 5 is the smoke inlet. After the high-temperature smoke in the aluminum melting furnace passes through the first regenerator 20, it enters the reversing valve 40 through the reversing valve smoke inlet / air outlet 5, while the combustion-supporting air flows out from the high-efficiency heat exchanger 50, passes through the reversing valve 40, and then flows out from the reversing valve smoke outlet / air inlet 6, and then enters the second regenerator 30.

[0045] In this embodiment, the reversing valve 40 can be set to a fixed action time. In one reversing cycle, the reversing valve 40 is actuated once, and the working medium flow direction of the first heat storage chamber 20 and the second heat storage chamber 30 is changed once. Figure 2As shown by the two flow directions of the solid arrow and the dotted arrow, specifically, before the reversing valve 40 is actuated, the flue gas flows between the two regenerators and the reversing valve 40 in the direction of the solid arrow, enters from the aluminum melting furnace through the regenerator flue gas inlet / air outlet 1 of the first regenerator 20, heats the ceramic ball regenerator in the first regenerator 20, and after the flue gas temperature is reduced, flows out from the regenerator flue gas outlet / air inlet 3 of the first regenerator 20, enters from the regenerator flue gas inlet / air outlet 5, flows out through the reversing valve flue gas outlet 7, and then enters from the heat exchanger flue gas inlet 9 of the high-efficiency heat exchanger 50 to preheat the combustion air. After the temperature is further reduced, it is discharged from the heat exchanger smoke outlet 12 of the high-efficiency heat exchanger 50. At the same time, the combustion air entering from the heat exchanger air inlet 11 and being heated flows out from the heat exchanger air outlet 10, enters from the reversing valve air inlet 8, flows out through the reversing valve smoke outlet / air inlet 6, and then enters the heat storage chamber air inlet / smoke outlet 4 of the second heat storage chamber 30, is further heated to a higher temperature in the second heat storage chamber 30, and flows out from the heat storage chamber air outlet / smoke inlet 2 of the second heat storage chamber 30 into the aluminum melting furnace. At this time, the ceramic ball heat storage body in the second heat storage chamber 30 is cooled by air. After reaching a reversing cycle, the flue gas flows between the two regenerators and the reversing valve 40 in the direction of the dotted arrow, and the flue gas flows in from the regenerator air outlet / flue gas inlet 2 of the second regenerator 30, and the ceramic ball regenerator in the second regenerator 30 is heated, and the flue gas flows out from the regenerator air inlet / flue gas outlet 4, and then flows in through the reversing valve flue gas outlet / air inlet 6, flows out through the reversing valve flue gas outlet 7, and then enters the high-efficiency heat exchanger 50, and then flows in the same direction as before the reversing cycle. Correspondingly, the combustion-supporting air comes out of the high-efficiency heat exchanger 50, enters through the reversing valve air inlet 8, flows out through the reversing valve flue gas inlet / air outlet 5, enters the first regenerator 20, cools the ceramic ball regenerator in the first regenerator 20, and the air is further heated, and then enters the aluminum melting furnace. In this way, a cycle is completed, and then it repeats itself.

[0046] In order to reduce system resistance, the height of the ceramic ball heat storage body in the first heat storage chamber 20 and the second heat storage chamber 30 needs to be determined after calculation. In principle, while ensuring that the thermal parameters of the heat storage chamber remain unchanged, the height of the ceramic ball heat storage body should be reduced as much as possible to reduce system power consumption.

[0047] In order to achieve a better heat exchange effect, the high-efficiency heat exchanger 50 adopts a heat exchange method of countercurrent heat exchange, and the heat exchange space is between the first tube sheet 13 and the second tube sheet 14. Specifically, the flue gas enters the shell side from the heat exchanger flue gas inlet 9 of the high-efficiency heat exchanger 50, and flows out from the heat exchanger flue gas outlet 12 of the high-efficiency heat exchanger 50. Except for a small part of lateral flushing at the inlet and outlet, the absolute majority of the heat exchanger flows longitudinally along the tube length direction. The air enters the three-dimensional deformation tube 15 from the heat exchanger air inlet 11 of the high-efficiency heat exchanger 50, and then flows out from the heat exchanger air outlet 10, in the opposite direction of the flue gas flow, so as to achieve a better heat exchange effect.

[0048] Figure 6 This is a schematic diagram of the wear of a common round tube in regular use. A black spot is formed at the 60° angle of the round tube in the figure, indicating that the round tube has a 60° wear angle at this point. There is a vortex structure on the right side of the figure, indicating that there is a vortex here; Figure 7 This is a schematic diagram of the anti-wear principle of a high specific surface tube in an embodiment of the present invention. As shown in the figure, no black spots are formed on the high specific surface tube at 60°, indicating that there is no 60° wear angle. There is no vortex structure at 180° on the right side of the figure, indicating that no eddy current is generated there. A detailed description of the anti-wear characteristics of the high specific surface tube is that the largest wear point of a general round tube appears at the 60° angle, which is the first to be worn through, and there is a vortex at the 180° angle (that is, the back of the round tube along the flow direction), and the speed decreases, and dust is most likely to accumulate at this place. According to the wear law of the round tube heat exchange tube in the flue gas flow field, the largest wear position appears at the 60° angle of the circular cross section, while the cross section of the high specific surface tube is nearly elliptical, there is no 60° wear angle, and there are no vortex points on the back, so there will be no dust accumulation.

[0049] The above detailed description is a specific description of a feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the patent scope of this case.

Claims

1. A combined flue gas waste heat recovery system connected to an aluminum melting furnace, characterized in that: The invention comprises a first heat storage chamber, a second heat storage chamber, a reversing valve and a high-efficiency heat exchanger; the first heat storage chamber is provided with a heat storage chamber smoke inlet / air outlet and a heat storage chamber smoke outlet / air inlet; the second heat storage chamber is provided with a heat storage chamber air outlet / smoke inlet and a heat storage chamber air inlet / smoke outlet; the reversing valve is a four-way valve, provided with a reversing valve smoke inlet / air outlet, a reversing valve smoke outlet / air inlet, a reversing valve smoke outlet and a reversing valve air inlet; the reversing valve smoke outlet and the reversing valve air inlet are both fixed inlets and outlets, the reversing valve smoke inlet / air outlet and the reversing valve smoke outlet / air inlet are both switchable channels, the reversing valve smoke inlet / air outlet and the reversing valve smoke outlet / air inlet are respectively connected to the heat storage chamber smoke outlet / air inlet and the heat storage chamber air inlet / smoke outlet in a switching manner; the high-efficiency heat exchanger comprises a high-efficiency heat exchange element, a heat exchanger air inlet, a heat exchanger air inlet, a heat exchanger air inlet, and a heat exchanger air inlet. The high-efficiency heat exchange element is installed in the cavity of the high-efficiency heat exchanger, and its two ends are fixed by the first tube sheet and the second tube sheet respectively; the heat exchanger smoke inlet is located on one side of the first tube sheet, and the heat exchanger air outlet is located on one side of the second tube sheet. The high-efficiency heat exchanger has a channel inside, which connects the heat exchanger smoke inlet with the heat exchanger air outlet respectively; the heat storage chamber smoke inlet / air outlet is connected to the aluminum melting furnace, the heat storage chamber smoke outlet / air inlet is connected to the reversing valve smoke inlet / air outlet, the reversing valve smoke outlet is connected to the heat exchanger smoke inlet, the heat exchanger air outlet is connected to the reversing valve air inlet, the reversing valve smoke outlet / air inlet is connected to the heat storage chamber air inlet / smoke outlet, and the heat storage chamber air outlet / smoke inlet is connected to the aluminum melting furnace; The high-efficiency heat exchange element is a three-dimensional deformable tube, and a plurality of the three-dimensional deformable tubes are provided, and adjacent three-dimensional deformable tubes are closely connected to form a stable and positioned self-supporting structure; The internal channel of the high-efficiency heat exchange element is an air channel, and the outside thereof and the cavity of the high-efficiency heat exchanger are flue gas channels, and the airflow direction of the air channel is set in the opposite direction to the airflow direction of the flue gas channel.

2. The combined flue gas waste heat recovery system according to claim 1 is characterized in that: The first heat storage chamber and the second heat storage chamber are both provided with a refractory material layer, and ceramic ball heat storage bodies are installed in both heat storage chambers.

3. The combined flue gas waste heat recovery system according to claim 1 is characterized in that: The reversing valve is a reversing valve with a periodic reversing period.

4. The combined flue gas waste heat recovery system according to claim 1 is characterized in that: The three-dimensional deformed tube is a heat exchange tube with a high specific surface area.

5. The combined flue gas waste heat recovery system according to claim 4 is characterized in that: A plurality of the three-dimensional deformed tubes form a heat exchange tube bundle, and the three-dimensional deformed tubes support each other through convex point contact, and form a flow channel with axial multi-channels and longitudinal full-channels.

6. The combined flue gas waste heat recovery system according to claim 4 is characterized in that: The cross section of the three-dimensional deformation tube is nearly elliptical.

7. The combined flue gas waste heat recovery system according to claim 6 is characterized in that: The three-dimensional deformed tube is a round tube that is processed into a spiral special-shaped tube through secondary processing.

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