Flue gas gradient utilization cold and heat combined supply system

Abstract

The utility model provides a flue gas gradient utilization cold and heat combined supply system, which relates to the technical field of flue gas waste heat utilization and comprises a high-temperature flue gas heat collector, a low-temperature flue gas heat collector, an absorption machine and a steam turbine. The high-temperature flue gas heat collector is communicated with the absorption machine through a first circulating heat exchange pipeline, the low-temperature flue gas heat collector is communicated with the absorption machine through a second circulating heat exchange pipeline, the steam turbine is communicated with the absorption machine, the absorption machine is communicated with user return water through a first water return pipeline, and the absorption machine is communicated with the high-temperature flue gas heat collector through a conveying pipeline. The high-temperature flue gas heat collector is communicated with user water supply through a first water supply pipeline, and the absorption machine is communicated with the user water supply through a second water supply pipeline. The smoke gradient utilization can be realized, cold and heat combined supply is carried out on users, and the equipment utilization rate is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to flue gas waste heat utilization technical field especially is flue gas cascade utilization cold and heat cogeneration system. BACKGROUND

[0002] A large amount of heat is contained in the flue gas of a boiler, and recycling this part of heat can significantly improve the comprehensive utilization efficiency of energy. The flue gas heat can be recycled by using a direct heat exchange method or a heat pump method.

[0003] The direct heat exchange method (for example, Chinese patent CN119065433A disclosed on December 3, 2024) uses a heat exchanger to realize the heat exchange between high-temperature flue gas and a cold source, but its utilization efficiency of high-temperature flue gas is low, and in addition, the recycling of low-temperature flue gas waste heat is not considered.

[0004] The heat pump method (for example, Chinese patent CN111578301A disclosed on December 3, 2024) can effectively recycle low-temperature flue gas waste heat, but it does not mention the utilization of high-temperature flue gas.

[0005] In addition, the existing technologies focus on the heat supply scene where the user has a heat demand, and the system cannot operate normally after the heat supply is over, which means that the utilization rate of the system equipment is low, causing a certain degree of resource waste.

[0006] In order to improve the utilization efficiency of flue gas heat, not only realize external heat supply, but also realize external cold supply, meet the cold and heat demand of the user, and improve the utilization rate of the equipment, a flue gas cascade utilization cold and heat cogeneration system is proposed. CONTENT OF THE UTILITY MODEL

[0007] The utility model aims at providing a flue gas cascade utilization cold and heat cogeneration system, which can improve the utilization efficiency of flue gas heat, not only realize external heat supply, but also realize external cold supply, meet the cold and heat demand of the user, and improve the utilization rate of the equipment;

[0008] The utility model provides a flue gas cascade utilization cold and heat cogeneration system, which comprises a high-temperature flue gas heat extractor, a low-temperature flue gas heat extractor, an absorption machine and a steam turbine; the high-temperature flue gas heat extractor is communicated with the absorption machine through a first circulating heat exchange pipeline, the low-temperature flue gas heat extractor is communicated with the absorption machine through a second circulating heat exchange pipeline, the steam turbine is communicated with the absorption machine, the absorption machine is communicated with user return water through a first return water pipeline, the absorption machine is communicated with the high-temperature flue gas heat extractor through a conveying pipeline, the high-temperature flue gas heat extractor is communicated with user water supply through a first water supply pipeline, and the absorption machine is communicated with user water supply through a second water supply pipeline.

[0009] Further, a heat sink is further included, and the heat sink is communicated with the absorber through a third circulating heat exchange pipeline.

[0010] Further, the second circulating heat exchange pipeline includes a first branch and a second branch, and the first branch is communicated with the second branch through a communication pipeline; the third circulating heat exchange pipeline includes a third branch and a fourth branch, the third branch is communicated with the first branch, and the fourth branch is communicated with the second branch.

[0011] Further, a first valve is arranged on the first branch, and the first valve is located between the communication pipeline and the third branch; a second valve is arranged on the communication pipeline; a third valve and a fourth valve are arranged on the second branch, and the third valve is located between the communication pipeline and the low-temperature flue gas heat extractor, and the fourth valve is located between the communication pipeline and the fourth branch; a fifth valve is arranged on the fourth branch, and the fifth valve is located between the heat sink and the second branch.

[0012] Further, a valve is arranged on the second water supply pipeline.

[0013] Further, a desulfurization tower is further included, and the high-temperature flue gas heat extractor is communicated with the desulfurization tower through a first flue gas discharge pipeline, and the desulfurization tower is communicated with the low-temperature flue gas heat extractor through a second flue gas discharge pipeline.

[0014] Further, a first condensate discharge pipe is connected to the absorber.

[0015] Further, a steam exhaust heat exchanger is further included, and the steam exhaust of the steam turbine is communicated to the steam exhaust heat exchanger through a steam exhaust pipeline, the steam exhaust heat exchanger is communicated with a second condensate discharge pipe, the steam exhaust pipeline is communicated with the second condensate discharge pipe, and the first condensate discharge pipe is communicated with the second condensate discharge pipe.

[0016] Further, the steam exhaust heat exchanger is communicated with user backwater through a second backwater pipeline, the first backwater pipeline is communicated with the second backwater pipeline, and valves are arranged on the first backwater pipeline and the second backwater pipeline respectively.

[0017] Further, the first backwater pipeline is communicated with the conveying pipeline.

[0018] The technical scheme of the utility model discloses heat exchanger and low temperature flue gas heat exchanger respectively with the absorption machine, thereby the system can realize flue gas cascade utilization. In the heat supply condition, the steam extraction of the steam turbine is used as the driving heat source of the absorption machine, the user return water enters the absorption machine and is heated, and after heating, enters the high temperature flue gas heat exchanger and exchanges heat with the flue gas as the cold source, and after further heating, provides the user with the water supply. In the refrigeration condition, the absorption machine is used as the refrigeration machine condition operation, the hot water of the high temperature flue gas heat exchanger enters the absorption machine and is used as the driving heat source of the absorption machine, the user return water enters the absorption machine and is cooled, and after cooling, provides the user with the water supply. Therefore, the system can realize the cold and heat combined supply to the user and improve the equipment utilization. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical scheme in the embodiment of the utility model or prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description, obviously, the drawings in the following description are some embodiments of the utility model, and those skilled in the art can also obtain other drawings according to these drawings without creating labor.

[0020] Figure 1 It is the system schematic diagram of embodiment 1 and embodiment 2 of the utility model;

[0021] Figure 2 It is the system schematic diagram of embodiment 3 of the utility model;

[0022] Explanation of reference signs:

[0023] 1-high temperature flue gas heat exchanger;2-desulfurization tower;3-low temperature flue gas heat exchanger;4-radiator;5-absorption machine;6-steam turbine;7-exhaust steam heat exchanger;

[0024] 8-first circulating heat exchange pipeline;

[0025] 9-second circulating heat exchange pipeline;901-first branch;902-second branch;903-communication pipeline;

[0026] 10-first return water pipeline;11-conveying pipeline;12-first water supply pipeline;13-second water supply pipeline;

[0027] 14-third circulating heat exchange pipeline;1401-third branch;1402-fourth branch;

[0028] 15-valve;16-first exhaust flue gas pipeline;17-second exhaust flue gas pipeline;18-first condensate water discharge pipe;19-exhaust steam pipeline;20-second condensate water discharge pipe;21-second return water pipeline;22-user return water;23-user water supply;24-flue gas;25-exhaust port;

[0029] V1 - first valve; V2 - second valve; V3 - third valve; V4 - fourth valve; V5 - fifth valve. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0032] In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited. In addition, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixedly connected, or detachably connected, or integrally connected; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0033] Embodiment 1

[0034] As Figure 1The utility model provides a flue gas cascade utilization cold -heat combined supply system, including high temperature flue gas heat exchanger 1, low temperature flue gas heat exchanger 3, absorption machine 5 and steam turbine 6, high temperature flue gas heat exchanger 1 is connected with absorption machine 5 through first circulating heat exchange pipeline 8, low temperature flue gas heat exchanger 3 is connected with absorption machine 5 through second circulating heat exchange pipeline 9, steam turbine 6 is connected with absorption machine 5, absorption machine 5 is connected with user return water 22 through first backwater pipeline 10, absorption machine 5 is connected with high temperature flue gas heat exchanger 1 through conveying pipeline 11, high temperature flue gas heat exchanger 1 is connected with user water supply 23 through first water supply pipeline 12, absorption machine 5 is connected with user water supply 23 through second water supply pipeline 13, and valve 15 is equipped on second water supply pipeline 13. Still including desulfurizing tower 2, high temperature flue gas heat exchanger 1 is connected with desulfurizing tower 2 through first flue gas discharge pipeline 16, and desulfurizing tower 2 is connected with low temperature flue gas heat exchanger 3 through second flue gas discharge pipeline 17.

[0035] Specifically, as shown in the drawings, Figure 1 After high temperature flue gas 24 is cooled down through high temperature flue gas heat exchanger 1, it enters desulfurizing tower 2 through first flue gas discharge pipeline 16, and then enters low temperature flue gas heat exchanger 3 through second flue gas discharge pipeline 17 after flowing out of desulfurizing tower 2, and is discharged through flue gas discharge port 25 after being further cooled down.

[0036] In the heat supply condition, absorption machine 5 operates in the heat supply condition, and the steam extraction of steam turbine 6 is used as the driving heat source of absorption machine 5, which is cooled and condensed in absorption machine 5 and then flows out through first condensate water discharge pipe 18. User return water 22 enters absorption machine 5 through first backwater pipeline 10 to be heated up, and then enters high temperature flue gas heat exchanger 1 through conveying pipeline 11 after being heated up, which is used as the cold source to exchange heat with flue gas 24, and then is provided to users as water supply through first water supply pipeline 12 after being further heated up.

[0037] In the refrigeration condition, absorption machine 5 operates as a refrigerator. Through first circulating heat exchange pipeline 8, the hot water flowing out of high temperature flue gas heat exchanger 1 enters absorption machine 5 as the driving heat source of absorption machine 5, which is cooled down in absorption machine 5 and then returns to high temperature flue gas heat exchanger 1. User return water 22 enters absorption machine 5 through first backwater pipeline 10 to be cooled down, and then is provided to users as water supply through second water supply pipeline 13 after being cooled down.

[0038] Valve 15 is arranged on the connecting pipeline 903 between steam turbine 6 and absorption machine 5, which is opened in the heat supply condition. Valves 15 are arranged on conveying pipeline 11 and first water supply pipeline 12, which are closed in the refrigeration condition and opened in the heat supply condition. Valve 15 on second water supply pipeline 13 is opened in the refrigeration condition and closed in the heat supply condition.

[0039] Valves 15 are arranged on two branches of first circulating heat exchange pipeline 8, and a booster pump is arranged on one of the two branches.

[0040] Embodiment 2

[0041] As Figure 1 shown, the heat sink 4 is further connected with the absorption machine 5 through a third circulating heat exchange pipeline 14. The second circulating heat exchange pipeline 9 comprises a first branch 901 and a second branch 902, and the first branch 901 is connected with the second branch 902 through a connecting pipeline 903; the third circulating heat exchange pipeline 14 comprises a third branch 1401 and a fourth branch 1402, the third branch 1401 is connected with the first branch 901, and the fourth branch 1402 is connected with the second branch 902. The first branch 901 is provided with a first valve V1, and the first valve V1 is located between the connecting pipeline 903 and the third branch 1401; the connecting pipeline 903 is provided with a second valve V2; the second branch 902 is provided with a third valve V3 and a fourth valve V4, and the third valve V3 is located between the connecting pipeline 903 and the low-temperature flue gas heat exchanger 3, and the fourth valve V4 is located between the connecting pipeline 903 and the fourth branch 1402; the fourth branch 1402 is provided with a fifth valve V5, and the fifth valve V5 is located between the heat sink 4 and the second branch 902.

[0042] Specifically, (1) in the heat supply working condition, the low-temperature water generated by the absorption machine 5 flows through the first valve V1 of the first branch 901 into the low-temperature flue gas heat exchanger 3, and after being heated in the low-temperature flue gas heat exchanger 3, it returns to the absorption machine 5 through the third valve V3 and the fourth valve V4 of the second branch 902 as a heat pump cold source, and at this time, the second valve V2 and the fifth valve V5 are closed.

[0043] (2) in the refrigeration working condition, the second valve V2, the third valve V3 and the fifth valve V5 are opened, and the first valve V1 and the fourth valve V4 are closed; the cold water generated by the absorption machine 5 enters the low-temperature flue gas heat exchanger 3 through the first branch 901, the connecting pipeline 903 and the second valve V2, the second branch 902 and the third valve V3, and after cooling the low-temperature flue gas 24, it enters the heat sink 4 through the first branch 901 and the third branch 1401, and after being cooled and released in the heat sink 4, it returns to the absorption machine 5 through the fourth branch 1402 and the fifth valve V5.

[0044] or the first valve V1, the third valve V3, the fourth valve V4 and the fifth valve V5 are opened, and the second valve V2 is closed; at this time, the water flowing out of the heat sink 4 passes through the fourth branch 1402 and the fifth valve V5, the second branch 902, part of which enters the absorption machine 5 to be heated, and the other part enters the low-temperature flue gas heat exchanger 3 through the second branch 902 and the fourth valve V4 and the third valve V3 to be heated, and after being heated in the low-temperature flue gas heat exchanger 3, it is combined with the water flowing out of the absorption machine 5 through the first branch 901 and the first valve V1, and then returns to the heat sink 4.

[0045] Alternatively, the second valve V2, the third valve V3, and the fourth valve V4 may all be closed, while the first valve V1 and the fifth valve V5 may be opened. The cold water generated by the absorber 5 enters the radiator 4 through the first branch 901 and the first valve V1. After cooling and releasing heat in the radiator 4, it returns to the absorber 5 through the fourth branch 1402 and the fifth valve V5.

[0046] Through the above valve 15 combinations, different valve 15 combinations correspond to different low-temperature flue gas heat exchanger 3 outlet flue gas 24 temperature requirements, as well as different radiator 4 heat dissipation capacities.

[0047] In Embodiments 1 and 2 above, the high-temperature flue gas heat exchanger 1 and the low-temperature flue gas heat exchanger 3 achieve cascaded utilization matching the temperature of the flue gas 24. In heating mode, the user's return water 22 is heated sequentially by passing through the absorber 5 and the high-temperature heat exchanger. In cooling mode, the hot water flowing out of the high-temperature flue gas heat exchanger 1 is used as the driving heat source for the absorber 5, thus improving the utilization efficiency of the heat from the flue gas 24. Furthermore, the absorber 5 in the above technical solution can provide both heating and cooling to users. In cooling mode, the radiator 4 and the switching of the first valve V1 to the fifth valve V5 ensure a relatively stable final exhaust temperature, enabling continuous system operation and improving equipment utilization efficiency.

[0048] This invention utilizes the heat from flue gas 24 in a tiered manner and a matching system process to improve the utilization efficiency of flue gas 24. The absorber 5 can provide both external heating and cooling. Under different operating conditions, the heat from the high-temperature flue gas 24 can be used to heat the user return water 22 or as a heat source to drive the absorber 5, thereby improving equipment utilization. Through the combination of valve 15 and radiator 4, the exhaust temperature of the low-temperature flue gas heat exchanger 3 can also be kept at a low level under cooling conditions. The waste heat of the exhaust steam from the turbine 6 is recovered. The user return water 22 can be heated by the absorber 5 and the high-temperature flue gas heat exchanger 1 in series or in parallel, thereby improving the overall energy utilization efficiency.

[0049] Example 3

[0050] like Figure 2 As shown, the absorber 5 is connected to a first condensate drain pipe 18. It also includes a waste steam heat exchanger 7. The waste steam from the turbine 6 is connected to the waste steam heat exchanger 7 via a waste steam pipeline 19. The waste steam heat exchanger 7 is connected to a second condensate drain pipe 20. The waste steam pipeline 19 and the second condensate drain pipe 20 are connected, and the first condensate drain pipe 18 is connected to the second condensate drain pipe 20. The waste steam heat exchanger 7 is connected to the user return water 22 via a second return water pipeline 21. The first return water pipeline 10 and the second return water pipeline 21 are connected, and valves 15 are respectively installed on the first return water pipeline 10 and the second return water pipeline 21. The first return water pipeline 10 is connected to the delivery pipeline 11.

[0051] Specifically, as shown in Figure 2 As shown in the figure, the exhaust heat exchanger 7 has two groups of non-intercommunicating pipelines and exchanges heat in the exhaust heat exchanger 7, one group of pipelines connects the turbine 6 exhaust pipeline 19 and the second condensate discharge pipe 20, and the turbine 6 exhaust exchanges heat in the exhaust heat exchanger 7 and is discharged as condensate; the other group of pipelines connects the user return water 22 and the second return water pipeline 21, and the user return water 22 exchanges heat with the exhaust steam and enters the absorber 5 after being heated.

[0052] In the heating condition, the user return water 22 enters the exhaust heat exchanger 7 through the second return water pipeline 21, exchanges heat with the turbine 6 exhaust and is heated, and then is divided into two paths and enters the absorber 5 and the high-temperature flue gas heat extractor 1 in parallel, is heated, and then is combined through the first water supply pipeline 12 and the second water supply pipeline 13 to be provided to the user as water supply. In the foregoing embodiment 1 and embodiment 2, the delivery pipeline 11 is communicated with the second water supply pipeline 13 but is not communicated with the user return water 22; and in the embodiment 3, the delivery pipeline 11 is communicated with the second return water pipeline 21 but is not communicated with the second water supply pipeline 13.

[0053] The embodiment recovers the turbine 6 exhaust heat and improves the overall energy utilization efficiency of the system by performing step-by-step heating on the user return water 22 in the heating condition.

[0054] The working mode and principle of the utility model:

[0055] In the heating condition, the absorber 5 operates in the heating condition, the turbine 6 extraction steam is used as the driving heat source of the absorber 5, is cooled and condensed in the absorber 5, and then flows out through the first condensate discharge pipe 18. The user return water 22 enters the absorber 5 through the first return water pipeline 10 and is heated, and then enters the high-temperature flue gas heat extractor 1 through the delivery pipeline 11, exchanges heat with the flue gas 24 as a cold source, is further heated, and then is provided to the user as water supply through the first water supply pipeline 12. The low-temperature water generated by the absorber 5 flows through the first valve V1 of the first branch 901 into the low-temperature flue gas heat extractor 3, is heated in the low-temperature flue gas heat extractor 3, and then returns to the absorber 5 as a heat pump cold source through the third valve V3 and the fourth valve V4 of the second branch 902, and the second valve V2 and the fifth valve V5 are closed at this time.

[0056] In the refrigeration mode, the absorption machine 5 operates as a refrigerator. The hot water from the high-temperature flue gas heat exchanger 1 enters the absorption machine 5 through the first circulating heat exchange pipeline 8, as the driving heat source of the absorption machine 5, and returns to the high-temperature flue gas heat exchanger 1 after being cooled in the absorption machine 5. The user return water 22 enters the absorption machine 5 through the first return water pipeline 10 and is cooled, and is provided to the user as the supply water through the second supply water pipeline 13 after being cooled. The second valve V2, the third valve V3, and the fifth valve V5 are opened, and the first valve V1 and the fourth valve V4 are closed; the cold water generated by the absorption machine 5 enters the low-temperature flue gas heat exchanger 3 through the first branch 901, the communication pipeline 903, the second valve V2, the second branch 902, and the third valve V3, is cooled by the low-temperature flue gas 24, and enters the radiator 4 through the first branch 901 and the third branch 1401, and returns to the absorption machine 5 through the fourth branch 1402 and the fifth valve V5 after being cooled and heat released in the radiator 4. Or the first valve V1, the third valve V3, the fourth valve V4, and the fifth valve V5 are opened, and the second valve V2 is closed; at this time, the water flowing out of the radiator 4 passes through the fourth branch 1402 and the fifth valve V5, the second branch 902, part of which enters the absorption machine 5 to be heated, and the other part enters the low-temperature flue gas heat exchanger 3 through the second branch 902 and the fourth valve V4 and the third valve V3 to be heated, and then returns to the radiator 4 after being heated in the low-temperature flue gas heat exchanger 3 and being combined with the water flowing out of the absorption machine 5 through the first branch 901 and the first valve V1. Or the second valve V2, the third valve V3, and the fourth valve V4 are closed, and the first valve V1 and the fifth valve V5 are opened; the cold water generated by the absorption machine 5 enters the radiator 4 through the first branch 901 and the first valve V1, is cooled and heat released in the radiator 4, and returns to the absorption machine 5 through the fourth branch 1402 and the fifth valve V5.

[0057] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A flue gas cascade utilization combined cooling and heating system, characterized in that, This includes high-temperature flue gas heat exchangers, low-temperature flue gas heat exchangers, absorbers, and steam turbines; The high-temperature flue gas heat exchanger and the absorber are connected through a first circulating heat exchange pipeline, the low-temperature flue gas heat exchanger and the absorber are connected through a second circulating heat exchange pipeline, the steam turbine is connected to the absorber, the absorber is connected to the user's return water through a first return water pipeline, the absorber is connected to the high-temperature flue gas heat exchanger through a delivery pipeline, the high-temperature flue gas heat exchanger is connected to the user's water supply through a first water supply pipeline, and the absorber is connected to the user's water supply through a second water supply pipeline.

2. The flue gas cascade utilization combined cooling and heating system according to claim 1, characterized in that, It also includes a radiator, which is connected to the absorber via a third circulating heat exchange pipeline.

3. The flue gas cascade utilization combined cooling and heating system according to claim 2, characterized in that, The second circulating heat exchange pipeline includes a first branch and a second branch, and the first branch and the second branch are connected by a connecting pipeline; The third circulating heat exchange pipeline includes a third branch and a fourth branch. The third branch is connected to the first branch, and the fourth branch is connected to the second branch.

4. The flue gas cascade utilization combined cooling and heating system according to claim 3, characterized in that, A first valve is provided on the first branch, and the first valve is located between the connecting pipeline and the third branch; A second valve is provided on the connecting pipeline; The second branch is provided with a third valve and a fourth valve, wherein the third valve is located between the connecting pipe and the low-temperature flue gas heat exchanger, and the fourth valve is located between the connecting pipe and the fourth branch; A fifth valve is provided on the fourth branch, and the fifth valve is located between the radiator and the second branch.

5. The flue gas cascade utilization combined cooling and heating system according to claim 1, characterized in that, A valve is installed on the second water supply pipeline.

6. The flue gas cascade utilization combined cooling and heating system according to claim 1, characterized in that, It also includes a desulfurization tower, wherein the high-temperature flue gas heat exchanger is connected to the desulfurization tower through a first exhaust pipe, and the desulfurization tower is connected to the low-temperature flue gas heat exchanger through a second exhaust pipe.

7. The flue gas cascade utilization combined cooling and heating system according to claim 1, characterized in that, The absorber is connected to a first condensate drain pipe.

8. The flue gas cascade utilization combined cooling and heating system according to claim 7, characterized in that, It also includes a waste steam heat exchanger, wherein the waste steam from the turbine is connected to the waste steam heat exchanger through a waste steam pipeline, and the waste steam heat exchanger is connected to a second condensate drain pipe, wherein the waste steam pipeline is connected to the second condensate drain pipe, and the first condensate drain pipe is connected to the second condensate drain pipe.

9. The flue gas cascade utilization combined cooling and heating system according to claim 8, characterized in that, The exhaust steam heat exchanger is connected to the user's return water through a second return water pipeline. The first return water pipeline is connected to the second return water pipeline, and valves are respectively installed on the first return water pipeline and the second return water pipeline.

10. The flue gas cascade utilization combined cooling and heating system according to claim 9, characterized in that, The first return water pipeline is connected to the delivery pipeline.

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