A flue gas waste heat recovery device and method with carbon capture coupled with heat storage and photothermal

Abstract

The present invention belongs to the field of flue gas recovery, and specifically relates to a flue gas waste heat recovery device and method with carbon capture that couples heat storage and photothermal, including a first heat exchanger, an absorption tower, a solar photothermal conversion device, a heat storage tank, a desorption tower, a second heat exchanger, and a third heat exchanger; by using the return water of the heat network as a cold source, the amount and consumption of circulating cooling water are reduced, and a certain water-saving effect is achieved. The use of solar energy to heat the carbon dioxide-rich ionic liquid provides more heat. By fully utilizing energy, hot network water with a maximum temperature of 130°C can be supplied. By using flue gas diversion and a heat storage tank, the temperature of the return water of the heat network and the temperature of the ionic liquid entering the desorption tower can be effectively controlled when the temperature changes drastically.

Description

Technical Field

[0001] The present invention belongs to the field of flue gas recovery, and in particular relates to a flue gas waste heat recovery device and method with carbon capture coupled with heat storage and photothermal. Background Art

[0002] Carbon dioxide is one of the main components of greenhouse gases that cause global warming, contributing 55% to the greenhouse effect. Currently, the total amount of carbon dioxide emitted into the atmosphere each year reaches nearly 30 billion tons, while the amount of carbon dioxide used is only about 100 million tons, far less than one percent of the total emissions.

[0003] Ionic liquids are environmentally friendly green solvents, catalysts and absorbents with the advantages of low volatility, good thermal stability and low vapor pressure. They can also be designed to link specific functional groups to effectively capture carbon dioxide and have the potential for industrialization.

[0004] On the one hand, existing carbon dioxide capture technologies waste energy, resulting in excessively high heating revenues. On the other hand, existing technologies lack the ability to adapt to day and night temperature changes, which seriously affects the stability of the unit's operation and fails to involve the use of renewable energy. Summary of the invention

[0005] The present invention proposes a flue gas waste heat recovery device and method with carbon capture that couples heat storage and photothermal energy to solve the problems in the prior art that the heat recovery rate is very low and the temperature stability of the system cannot be guaranteed when the temperature changes drastically, and the prior art does not involve the use of renewable energy.

[0006] To achieve the above object, the present invention proposes the following scheme:

[0007] A flue gas waste heat recovery device with carbon capture that couples heat storage and photothermal energy, comprising a first heat exchanger, an absorption tower, a solar photothermal conversion device, a desorption tower, a second heat exchanger and a third heat exchanger;

[0008] The first heat exchanger is provided with a first heat exchanger smoke inlet, a first heat exchanger smoke outlet and a first heat exchanger hot network water inlet; the first heat exchanger smoke inlet is connected to the first heat exchanger smoke outlet;

[0009] The absorption tower is provided with an absorption tower flue gas inlet, an absorption tower ionic liquid inlet, an absorption tower second heat exchanger flue gas inlet and an absorption tower ionic liquid outlet;

[0010] The solar thermal conversion device is provided with a photothermal ion liquid inlet and a photothermal ion liquid outlet;

[0011] The desorption tower is provided with a desorption tower ion liquid inlet, a desorption tower ion liquid outlet and a desorption tower carbon dioxide outlet;

[0012] The second heat exchanger is provided with a second heat exchanger carbon dioxide inlet, a second heat exchanger hot network water inlet and a second heat exchanger hot network water outlet; the second heat exchanger hot network water inlet is connected to the second heat exchanger hot network water outlet;

[0013] The third heat exchanger is provided with a third heat exchanger ionic liquid inlet, a third heat exchanger ionic liquid outlet, a third heat exchanger hot network water inlet and a third heat exchanger hot network water outlet; the third heat exchanger ionic liquid inlet is connected to the third heat exchanger ionic liquid outlet, and the third heat exchanger hot network water inlet is connected to the third heat exchanger hot network water outlet;

[0014] The flue gas inlet of the first heat exchanger is connected to the flue gas inlet, the flue gas outlet of the first heat exchanger is connected to the flue gas inlet of the absorption tower, the ionic liquid outlet of the absorption tower is connected to the photothermal ionic liquid inlet, the photothermal ionic liquid outlet is connected to the ionic liquid inlet of the desorption tower, the ionic liquid outlet of the desorption tower is connected to the ionic liquid inlet of the third heat exchanger, the carbon dioxide outlet of the desorption tower is connected to the carbon dioxide inlet of the second heat exchanger, the hot network water outlet of the second heat exchanger is connected to the hot network water inlet of the third heat exchanger, the hot network water outlet of the third heat exchanger is connected to the hot network water inlet of the first heat exchanger, and the ionic liquid outlet of the third heat exchanger is connected to the ionic liquid inlet of the absorption tower.

[0015] Preferably, it also includes a heat storage tank, which is provided with a heat storage tank ion liquid inlet, a heat storage tank ion liquid outlet, a heat storage tank smoke inlet, a heat storage tank smoke outlet, a heat storage tank heat network water inlet and a heat storage tank heat network water outlet; the heat storage tank ion liquid inlet is connected to the heat storage tank ion liquid outlet, the heat storage tank heat network water inlet is connected to the heat storage tank smoke inlet, and the heat storage tank smoke outlet is connected to the heat storage tank heat network water outlet;

[0016] The photothermal ionic liquid outlet is connected to the ionic liquid inlet of the heat storage tank, the ionic liquid outlet of the heat storage tank is connected to the ionic liquid inlet of the desorption tower, the heat network water outlet of the third heat exchanger is connected to the heat network water inlet of the heat storage tank, and the flue gas inlet of the heat storage tank is connected to the heat network water inlet of the first heat exchanger;

[0017] The heat network water outlet of the heat storage tank is connected to the flue gas inlet, and the flue gas outlet of the heat storage tank is connected to the ionic liquid outlet of the absorption tower.

[0018] Preferably, the water outlet of the first heat exchanger heat network is connected to the heat network.

[0019] Preferably, the absorption tower is provided with an absorption tower smoke outlet, and the absorption tower smoke outlet is connected to the chimney.

[0020] Preferably, the flue gas outlet of the absorption tower is located at the top of the absorption tower.

[0021] Preferably, the second heat exchanger is provided with a second heat exchanger carbon dioxide outlet, and the second heat exchanger carbon dioxide outlet is connected to the second heat exchanger carbon dioxide inlet.

[0022] Preferably, it is characterized in that the ionic liquid outlet of the absorption tower is located at the bottom of the absorption tower.

[0023] Preferably, it is characterized in that the carbon dioxide outlet of the desorption tower is located at the top of the desorption tower, and the ionic liquid outlet of the desorption tower is located at the bottom of the desorption tower.

[0024] A flue gas waste heat recovery method with carbon capture coupled with heat storage and photothermal energy comprises the following steps:

[0025] The flue gas passes through the flue gas inlet, and a part of the flue gas enters the first heat exchanger. The flue gas in the first heat exchanger exchanges heat with the hot water network, and the flue gas is cooled and enters the absorption tower;

[0026] Another part of the flue gas enters the heat storage tank, which stores the heat from the flue gas, and the cooled flue gas enters the absorption tower;

[0027] The flue gas contacts the ionic liquid in the absorption tower, the ionic liquid absorbs carbon dioxide, and the flue gas depleted in carbon dioxide is discharged through the flue gas outlet of the absorption tower and enters the chimney;

[0028] The carbon dioxide-rich ionic liquid enters the solar thermal conversion device, is heated and enters the heat storage tank, is heated again in the heat storage tank, and enters the desorption tower;

[0029] The carbon dioxide-rich ionic liquid is desorbed in the desorption tower, the desorbed carbon dioxide enters the second heat exchanger, and the desorbed carbon dioxide-poor ionic liquid enters the third heat exchanger;

[0030] The hot network water enters the second heat exchanger and exchanges heat with the carbon dioxide from the desorption tower. After the carbon dioxide is cooled, it is discharged through the carbon dioxide outlet of the second heat exchanger and enters the carbon dioxide storage tank. The heated hot network water enters the third heat exchanger.

[0031] The hot water in the third heat exchanger exchanges heat with the carbon dioxide-poor ionic liquid, the hot water is heated up again and enters the heat storage tank, and the carbon dioxide-poor ionic liquid is cooled down and enters the absorption tower;

[0032] The heat network water in the heat storage tank is heated up and enters the first heat exchanger;

[0033] The water in the heating network exchanges heat with the flue gas in the first heat exchanger, and the water in the heating network is heated up and enters the heating network.

[0034] Preferably, after the hot network water exchanges heat with the flue gas in the first heat exchanger, the temperature of the hot network water is greater than 100 degrees Celsius and less than 130 degrees Celsius.

[0035] The present invention is beneficial in that:

[0036] By utilizing flue gas diversion and heat storage tanks, multi-stage utilization of heat is achieved in multiple heat exchangers, increasing heating revenue.

[0037] The heat storage tank adjusts the diversion ratio of the flue gas. More flue gas flows to the energy storage tank during the day, and less flows to the energy storage tank at night. This is the system temperature regulation under the current temperature difference change.

[0038] The solar thermal conversion device is used to heat the ionic liquid to realize the utilization of renewable energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0040] Figure 1 Schematic diagram of a flue gas waste heat recovery device with carbon capture that couples heat storage and solar thermal.

[0041] Figure 2 This is a schematic diagram of the device without the heat storage tank.

[0042] In the figure, 1 is the first heat exchanger, 2 is the absorption tower, 3 is the solar thermal conversion device, 4 is the heat storage tank, 5 is the desorption tower, 6 is the second heat exchanger, and 7 is the third heat exchanger;

[0043] 10 is a flue gas inlet, 11 is a flue gas inlet of the first heat exchanger, 12 is a flue gas outlet of the first heat exchanger, 13 is a water inlet of the hot network of the first heat exchanger, and 14 is a water outlet of the hot network of the first heat exchanger;

[0044] 21 is the flue gas inlet of the absorption tower, 22 is the flue gas outlet of the absorption tower, 23 is the ionic liquid inlet of the absorption tower, 24 is the ionic liquid outlet of the absorption tower, and 25 is the flue gas inlet of the second heat exchanger of the absorption tower;

[0045] 31 is the photothermal ionic liquid inlet, 32 is the photothermal ionic liquid outlet;

[0046] 41 is the ionic liquid inlet of the heat storage tank, 42 ​​is the ionic liquid outlet of the heat storage tank, 43 is the flue gas inlet of the heat storage tank, 44 is the flue gas outlet of the heat storage tank, 45 is the hot network water inlet of the heat storage tank, and 46 is the hot network water outlet of the heat storage tank;

[0047] 51 is the desorption tower ionic liquid inlet, 52 is the desorption tower ionic liquid outlet, 53 is the desorption tower carbon dioxide outlet;

[0048] 61 is the carbon dioxide inlet of the second heat exchanger, 62 is the carbon dioxide outlet of the second heat exchanger, 63 is the hot network water inlet of the second heat exchanger, and 64 is the hot network water outlet of the second heat exchanger;

[0049] 71 is the ionic liquid inlet of the third heat exchanger, 72 is the ionic liquid outlet of the third heat exchanger, 73 is the hot network water inlet of the third heat exchanger, and 74 is the hot network water outlet of the third heat exchanger. DETAILED DESCRIPTION

[0050] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0051] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0052] Embodiment 1:

[0053] See also Figure 1 and Figure 2 As shown, the present invention discloses a flue gas waste heat recovery device with carbon capture that couples heat storage and photothermal, comprising a first heat exchanger 1, an absorption tower 2, a solar photothermal conversion device 3, a heat storage tank 4, a desorption tower 5, a second heat exchanger 6 and a third heat exchanger 7;

[0054] The first heat exchanger 1 is provided with a first heat exchanger smoke inlet 11, a first heat exchanger smoke outlet 12, a first heat exchanger hot network water inlet 13 and a first heat exchanger hot network water outlet 14; the first heat exchanger smoke inlet 11 is connected to the first heat exchanger smoke outlet 12, the first heat exchanger hot network water outlet 14 is connected to the first heat exchanger hot network water inlet 13, and the first heat exchanger hot network water outlet 14 is connected to the hot network.

[0055] The absorption tower 2 is provided with an absorption tower flue gas inlet 21, an absorption tower flue gas outlet 22, an absorption tower ionic liquid inlet 23, an absorption tower second heat exchanger flue gas inlet 24 and an absorption tower ionic liquid outlet 25; the absorption tower flue gas outlet 22 is connected to the chimney, the absorption tower ionic liquid outlet 25 is located at the bottom of the absorption tower 2, and the absorption tower flue gas outlet 22 is located at the top of the absorption tower 2. The absorption tower flue gas outlet 22 is connected to the chimney.

[0056] The solar thermal conversion device 3 is provided with a photothermal ionic liquid inlet 31 and a photothermal ionic liquid outlet 32;

[0057] The heat storage tank 4 is provided with a heat storage tank ionic liquid inlet 41, a heat storage tank ionic liquid outlet 42, a heat storage tank flue gas inlet 43, a heat storage tank flue gas outlet 44, a heat storage tank hot network water inlet 45 and a heat storage tank hot network water outlet 46;

[0058] The desorption tower 5 is provided with a desorption tower ionic liquid inlet 51 , a desorption tower ionic liquid outlet 52 and a desorption tower carbon dioxide outlet 53 . The desorption tower carbon dioxide outlet 53 is located at the top of the desorption tower 5 , and the desorption tower ionic liquid outlet 52 is located at the bottom of the desorption tower 5 .

[0059] The second heat exchanger 6 is provided with a second heat exchanger carbon dioxide inlet 61, a second heat exchanger carbon dioxide outlet 62, a second heat exchanger heat network water inlet 63 and a second heat exchanger heat network water outlet 64; the second heat exchanger heat network water inlet 63 is connected to the second heat exchanger heat network water outlet 64, and the second heat exchanger carbon dioxide outlet 62 is connected to the second heat exchanger carbon dioxide inlet 61. The second heat exchanger carbon dioxide outlet 62 is connected to the carbon dioxide storage tank.

[0060] The third heat exchanger 7 is provided with a third heat exchanger ionic liquid inlet 71, a third heat exchanger ionic liquid outlet 72, a third heat exchanger hot network water inlet 73 and a third heat exchanger hot network water outlet 74; the third heat exchanger ionic liquid inlet 71 is connected to the third heat exchanger ionic liquid outlet 72, and the third heat exchanger hot network water inlet 73 is connected to the third heat exchanger hot network water outlet 74;

[0061] The first heat exchanger flue gas inlet 11 and the heat storage tank flue gas inlet 43 are connected to the flue gas inlet 10, the first heat exchanger flue gas outlet 12 is connected to the absorption tower flue gas inlet 21, the heat storage tank heat network water outlet 46 is connected to the first heat exchanger heat network water inlet 13, the absorption tower ionic liquid outlet 25 is connected to the photothermal ionic liquid inlet 31, the photothermal ionic liquid outlet 32 ​​is connected to the heat storage tank ionic liquid inlet 41, the heat storage tank flue gas outlet 44 is connected to the absorption tower second heat exchanger flue gas inlet 24, the heat storage tank ionic liquid outlet 42 is connected to the desorption tower ionic liquid inlet 51, the desorption tower carbon dioxide outlet 53 is connected to the second heat exchanger carbon dioxide inlet 61, the desorption tower ionic liquid outlet 52 is connected to the third heat exchanger ionic liquid inlet 71, the second heat exchanger heat network water outlet 64 is connected to the third heat exchanger heat network water inlet 73, the third heat exchanger heat network water outlet 74 is connected to the heat storage tank heat network water inlet 45, and the third heat exchanger ionic liquid outlet 72 is connected to the absorption tower ionic liquid inlet 23;

[0062] Embodiment 2:

[0063] like Figure 1 The flue gas enters the pipeline through the flue gas inlet 10, and a part of the flue gas enters the first heat exchanger 1 through the first heat exchanger flue gas inlet 11. The flue gas in the first heat exchanger 1 exchanges heat with the hot network water. The flue gas is cooled and enters the absorption tower 2 through the first heat exchanger flue gas inlet 12 and the absorption tower flue gas inlet 21;

[0064] Another part of the flue gas enters the heat storage tank 4 through the heat storage tank flue gas inlet 43, and the heat storage tank 4 stores the heat from the flue gas. The cooled flue gas enters the absorption tower 2 through the heat storage tank flue gas outlet 44 and the absorption tower second heat exchanger flue gas inlet 24;

[0065] The flue gas in the absorption tower 2 contacts the ionic liquid, the ionic liquid absorbs carbon dioxide, and the flue gas depleted in carbon dioxide is discharged through the absorption tower flue gas outlet 22 and enters the chimney;

[0066] The carbon dioxide-rich ionic liquid enters the solar thermal conversion device 3 through the absorption tower ionic liquid outlet 25 and the photothermal ionic liquid inlet 31, and after being heated, enters the heat storage tank 4 through the photothermal ionic liquid outlet 32 ​​and the heat storage tank ionic liquid inlet 41. The carbon dioxide-rich ionic liquid in the heat storage tank 4 is heated again, and enters the desorption tower 5 through the heat storage tank ionic liquid outlet 42 and the desorption tower ionic liquid inlet 51;

[0067] The carbon dioxide-rich ionic liquid is desorbed in the desorption tower 5, and the desorbed carbon dioxide enters the second heat exchanger 6 through the desorption tower carbon dioxide outlet 53 and the second heat exchanger carbon dioxide inlet 61, and the desorbed carbon dioxide-poor ionic liquid enters the third heat exchanger 7 through the desorption tower ionic liquid outlet 52 and the third heat exchanger ionic liquid inlet 71;

[0068] The hot network water enters the second heat exchanger 6 through the hot network water inlet 63 of the second heat exchanger, exchanges heat with the carbon dioxide from the desorption tower 5, and the carbon dioxide is discharged through the carbon dioxide outlet 62 of the second heat exchanger after cooling, and enters the carbon dioxide storage tank. The heated hot network water enters the third heat exchanger 7 through the hot network water outlet 64 of the second heat exchanger and the hot network water inlet 73 of the third heat exchanger;

[0069] The hot network water in the third heat exchanger 7 exchanges heat with the carbon dioxide-depleted ionic liquid, the hot network water is heated up again, and enters the heat storage tank 4 through the hot network water outlet 74 of the third heat exchanger and the hot network water inlet 45 of the heat storage tank, the carbon dioxide-depleted ionic liquid is cooled down, and enters the absorption tower 2 through the ionic liquid outlet 72 of the third heat exchanger and the ionic liquid inlet 23 of the absorption tower;

[0070] The heat network water in the heat storage tank 4 is heated up and enters the first heat exchanger 1 through the heat storage tank heat network water outlet 46 and the first heat exchanger heat network water inlet 13;

[0071] The heating network water exchanges heat with the flue gas in the first heat exchanger 1, the heating network water is heated up, and enters the heating network through the heating network water outlet 14 of the first heat exchanger.

[0072] After the hot network water exchanges heat with the flue gas in the first heat exchanger 1, the temperature of the hot network water is greater than 100 degrees Celsius and less than 130 degrees Celsius.

[0073] Embodiment 3:

[0074] When the heat storage tank is not needed to adapt to temperature changes, the heat storage tank can be removed. At this time:

[0075] The first heat exchanger flue gas inlet 11 is connected to the flue gas inlet 10, the first heat exchanger flue gas outlet 12 is connected to the absorption tower flue gas inlet 21, the absorption tower ionic liquid outlet 25 is connected to the photothermal ionic liquid inlet 31, the photothermal ionic liquid outlet 32 ​​is connected to the desorption tower ionic liquid inlet 51, the desorption tower ionic liquid outlet 52 is connected to the third heat exchanger ionic liquid inlet 71, the desorption tower carbon dioxide outlet 53 is connected to the second heat exchanger carbon dioxide inlet 61, the second heat exchanger hot network water outlet 64 is connected to the third heat exchanger hot network water inlet 73, the third heat exchanger hot network water outlet 74 is connected to the first heat exchanger hot network water inlet 13, and the third heat exchanger ionic liquid outlet 72 is connected to the absorption tower ionic liquid inlet 23.

[0076] like Figure 2 The flue gas enters the first heat exchanger 1 through the flue gas inlet 11 of the first heat exchanger, exchanges heat with the hot network water in the heat exchanger, the flue gas cools down, and the hot network water heats up. The flue gas enters the absorption tower 2 through the flue gas outlet 12 of the first heat exchanger and the flue gas inlet 21 of the absorption tower. The carbon dioxide in the flue gas is absorbed by the ionic liquid, and the flue gas with carbon dioxide absorbed is discharged through the flue gas outlet 22 of the absorption tower. The carbon dioxide-rich ionic liquid is sent to the solar thermal conversion device 3 through the ionic liquid outlet 25 of the absorption tower and the ionic liquid inlet 31 of the solar thermal conversion device. The carbon dioxide-rich ionic liquid is heated inside the solar thermal conversion device 3, and then enters the desorption tower 5 through the ionic liquid outlet 32 ​​of the solar thermal conversion device and the ionic liquid inlet 51 of the desorption tower. The carbon dioxide-rich ionic liquid is desorbed in the desorption tower 5, and the separated carbon dioxide enters the third heat exchanger 6 through the carbon dioxide outlet 53 of the desorption tower and the carbon dioxide inlet 61 of the second heat exchanger. The separated carbon dioxide-poor ionic liquid enters through the ionic liquid outlet 52 of the desorption tower and the ionic liquid inlet 71 of the third heat exchanger. The second heat exchanger 7, the hot network water enters the third heat exchanger 6 through the hot network water inlet 63 of the second heat exchanger, the hot network water exchanges heat with the carbon dioxide from the desorption tower 5 in the third heat exchanger, the carbon dioxide is cooled, and the hot network water is heated. The cooled carbon dioxide enters the carbon dioxide storage tank through the carbon dioxide outlet 62 of the second heat exchanger, and the heated hot network water enters the second heat exchanger 7 through the hot network water outlet 65 of the second heat exchanger and the hot network water inlet 73 of the third heat exchanger. The heated hot network water and the carbon dioxide-lean ion liquid from the desorption tower 5 are mixed. Heat exchange occurs in the body, the temperature of the hot network water rises, and the temperature of the carbon dioxide-lean ionic liquid drops. After cooling, the carbon dioxide-lean ionic liquid enters the absorption tower 2 through the third heat exchanger ionic liquid outlet 72 and the absorption tower ionic liquid inlet 23. The heated hot network water enters the first heat exchanger 1 through the third heat exchanger hot network water outlet 75 and the first heat exchanger hot network water outlet 13, and is heated in the first heat exchanger 1. At this time, the hot network water temperature is greater than 100 degrees Celsius and less than 130 degrees Celsius. Finally, it returns to the hot network through the first heat exchanger hot network water outlet 15.

[0077] In this device, the return water from the heat network is used as a cold source, which reduces the amount and consumption of circulating cooling water and achieves a certain water-saving effect. Solar energy is used to heat the carbon dioxide-rich ionic liquid to provide more heat. By fully utilizing energy, the heat network water can be supplied at a maximum temperature of 130°C. By using flue gas diversion and heat storage tanks, the temperature of the return water from the heat network and the temperature of the ionic liquid entering the desorption tower can be effectively controlled when the temperature changes drastically.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A flue gas waste heat recovery method with carbon capture that couples heat storage and photothermal energy, characterized in that: The invention is realized based on a flue gas waste heat recovery device with carbon capture that couples heat storage and photothermal energy, wherein the flue gas waste heat recovery device comprises a first heat exchanger (1), an absorption tower (2), a solar photothermal conversion device (3), a desorption tower (5), a second heat exchanger (6) and a third heat exchanger (7); The first heat exchanger (1) is provided with a first heat exchanger smoke inlet (11), a first heat exchanger smoke outlet (12) and a first heat exchanger hot network water inlet (13); the first heat exchanger smoke inlet (11) is connected to the first heat exchanger smoke outlet (12); The absorption tower (2) is provided with an absorption tower flue gas inlet (21), an absorption tower ionic liquid inlet (23), an absorption tower second heat exchanger flue gas inlet (24) and an absorption tower ionic liquid outlet (25); The solar thermal conversion device (3) is provided with a photothermal ionic liquid inlet (31) and a photothermal ionic liquid outlet (32); The desorption tower (5) is provided with a desorption tower ion liquid inlet (51), a desorption tower ion liquid outlet (52) and a desorption tower carbon dioxide outlet (53); The second heat exchanger (6) is provided with a second heat exchanger carbon dioxide inlet (61), a second heat exchanger hot network water inlet (63) and a second heat exchanger hot network water outlet (64); the second heat exchanger hot network water inlet (63) is connected to the second heat exchanger hot network water outlet (64); The third heat exchanger (7) is provided with a third heat exchanger ionic liquid inlet (71), a third heat exchanger ionic liquid outlet (72), a third heat exchanger hot network water inlet (73) and a third heat exchanger hot network water outlet (74); the third heat exchanger ionic liquid inlet (71) is connected to the third heat exchanger ionic liquid outlet (72), and the third heat exchanger hot network water inlet (73) is connected to the third heat exchanger hot network water outlet (74); The first heat exchanger flue gas inlet (11) is connected to the flue gas inlet (10), the first heat exchanger flue gas outlet (12) is connected to the absorption tower flue gas inlet (21), the absorption tower ionic liquid outlet (25) is connected to the photothermal ionic liquid inlet (31), the photothermal ionic liquid outlet (32) is connected to the desorption tower ionic liquid inlet (51), the desorption tower ionic liquid outlet (52) is connected to the third heat exchanger ionic liquid inlet (71), the desorption tower carbon dioxide outlet (53) is connected to the second heat exchanger carbon dioxide inlet (61), the second heat exchanger heat network water outlet (64) is connected to the third heat exchanger heat network water inlet (73), the third heat exchanger heat network water outlet (74) is connected to the first heat exchanger heat network water inlet (13), and the third heat exchanger ionic liquid outlet (72) is connected to the absorption tower ionic liquid inlet (23); The flue gas waste heat recovery device further comprises a heat storage tank (4), the heat storage tank (4) being provided with a heat storage tank ionic liquid inlet (41), a heat storage tank ionic liquid outlet (42), a heat storage tank flue gas inlet (43), a heat storage tank flue gas outlet (44), a heat storage tank hot network water inlet (45) and a heat storage tank hot network water outlet (46); the heat storage tank ionic liquid inlet (41) is connected to the heat storage tank ionic liquid outlet (42), the heat storage tank hot network water inlet (45) is connected to the heat storage tank flue gas inlet (43), and the heat storage tank flue gas outlet (44) is connected to the heat storage tank hot network water outlet (46); The photothermal ion liquid outlet (32) is connected to the heat storage tank ion liquid inlet (41), the heat storage tank ion liquid outlet (42) is connected to the desorption tower ion liquid inlet (51), the third heat exchanger heat network water outlet (74) is connected to the heat storage tank heat network water inlet (45), and the heat storage tank flue gas inlet (43) is connected to the first heat exchanger heat network water inlet (13); The heat storage tank heat network water outlet (46) is connected to the flue gas inlet (10), and the heat storage tank flue gas outlet (44) is connected to the absorption tower ionic liquid outlet (25); The flue gas waste heat recovery method comprises the following steps: The flue gas passes through the flue gas inlet (10), and a portion of the flue gas enters the first heat exchanger (1). The flue gas in the first heat exchanger (1) exchanges heat with water in the heating network, and the flue gas is cooled and enters the absorption tower (2); Another part of the flue gas enters the heat storage tank (4), which stores the heat from the flue gas. The flue gas after cooling enters the absorption tower (2); The flue gas contacts the ionic liquid in the absorption tower (2), the ionic liquid absorbs carbon dioxide, and the flue gas depleted in carbon dioxide is discharged through the flue gas outlet (22) of the absorption tower and enters the chimney; The carbon dioxide-rich ionic liquid enters the solar thermal conversion device (3), is heated, enters the heat storage tank (4), is heated again in the heat storage tank (4), and enters the desorption tower (5); The carbon dioxide-rich ionic liquid is desorbed in the desorption tower (5), the desorbed carbon dioxide enters the second heat exchanger (6), and the desorbed carbon dioxide-poor ionic liquid enters the third heat exchanger (7); The hot network water enters the second heat exchanger (6) to exchange heat with the carbon dioxide from the desorption tower (5). The carbon dioxide is cooled and discharged through the carbon dioxide outlet (62) of the second heat exchanger and enters the carbon dioxide storage tank. The heated hot network water enters the third heat exchanger (7). The hot network water in the third heat exchanger (7) exchanges heat with the carbon dioxide-poor ionic liquid, the hot network water is heated up again and enters the heat storage tank (4), and the carbon dioxide-poor ionic liquid is cooled down and enters the absorption tower (2); The heat network water in the heat storage tank (4) is heated and enters the first heat exchanger (1); The water in the heating network exchanges heat with the flue gas in the first heat exchanger (1), the water in the heating network is heated up, and enters the heating network; After the hot network water exchanges heat with the flue gas in the first heat exchanger (1), the temperature of the hot network water is greater than 100 degrees Celsius and less than 130 degrees Celsius.

2. A flue gas waste heat recovery method with carbon capture coupled with heat storage and photothermal as claimed in claim 1, characterized in that: The first heat exchanger (1) is provided with a first heat exchanger hot network water outlet (14), and the first heat exchanger hot network water outlet (14) is connected to the first heat exchanger hot network water inlet (13).

3. A flue gas waste heat recovery method with carbon capture coupled with heat storage and photothermal as claimed in claim 2, characterized in that: The first heat exchanger heat network water outlet (14) is connected to the heat network.

4. The flue gas waste heat recovery method with carbon capture coupled with heat storage and photothermal as claimed in claim 1, characterized in that: The absorption tower (2) is provided with an absorption tower smoke outlet (22), and the absorption tower smoke outlet (22) is connected to a chimney.

5. A flue gas waste heat recovery method with carbon capture coupled with heat storage and photothermal as claimed in claim 4, characterized in that: The absorption tower flue gas outlet (22) is located at the top of the absorption tower (2).

6. The flue gas waste heat recovery method with carbon capture coupled with heat storage and photothermal as claimed in claim 1, characterized in that: The second heat exchanger (6) is provided with a second heat exchanger carbon dioxide outlet (62), and the second heat exchanger carbon dioxide outlet (62) is connected to the second heat exchanger carbon dioxide inlet (61).

7. The flue gas waste heat recovery method with carbon capture coupled with heat storage and photothermal as claimed in claim 1, characterized in that: The absorption tower ionic liquid outlet (25) on the absorption tower (2) is located at the bottom of the absorption tower (2).

8. The flue gas waste heat recovery method with carbon capture coupled with heat storage and photothermal as claimed in claim 1, characterized in that: The desorption tower carbon dioxide outlet (53) on the desorption tower (5) is located at the top of the desorption tower (5), and the desorption tower ionic liquid outlet (52) is located at the bottom of the desorption tower (5).

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