Flue gas waste heat recovery system

Abstract

The invention relates to a flue gas waste heat recovery system which comprises a waste heat recovery pipeline and a heat exchange pipeline, the waste heat recovery pipeline comprises a flue gas inlet, a flue gas treatment assembly and a flue gas outlet, and the flue gas treatment assembly comprises a liquid storage tank, a solution spraying part, a first circulation loop, a second circulation loop and a solution concentration part. The smoke inlet and the smoke outlet are respectively communicated with the liquid storage tank, the solution spraying part is located in the liquid storage tank, the first circulation loop is used for communicating the liquid storage tank with the solution spraying part, the second circulation loop is used for communicating the liquid storage tank with the solution concentrating part, and the heat exchange pipeline comprises a water inlet, a water outlet and a first heat exchange part. The first heat exchange part further communicates with the first circulation loop and is located between the liquid storage box and the solution spraying part. According to the flue gas waste heat recovery system disclosed by the invention, heat is recovered through the solution, so that the flue gas waste heat recovery system has relatively high heat absorption efficiency, and the flue gas waste heat recovery system disclosed by the invention is relatively simple in structure, relatively small in occupied space and convenient to process and use.

Description

Technical Field

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

[0002] Thermal power plants generate a large amount of high-temperature flue gas through combustion during the production process. Direct emission will not only aggravate the pollution of the atmospheric environment, but also waste a lot of heat energy. In the related technology, waste heat boilers, heat pipe heat exchangers and other methods are used to recover waste heat in flue gas. However, the waste heat boiler system has a complex structure, high initial investment and requires a large installation space. Although the heat pipe heat exchanger has high heat transfer efficiency, it has a limited life when used in high-temperature flue gas and has a high maintenance cost. Therefore, those skilled in the art are in urgent need of a waste heat recovery device with higher waste heat recovery efficiency and lower cost. Summary of the invention

[0003] The purpose of the present invention is to provide a flue gas waste heat recovery system, which has a high waste heat recovery efficiency and can effectively recover the flue gas waste heat.

[0004] In order to achieve the above object, the present disclosure provides a flue gas waste heat recovery system, comprising: A waste heat recovery pipeline, comprising a flue gas inlet, a flue gas treatment component and a flue gas outlet, wherein the flue gas treatment component comprises a liquid storage tank, a solution spraying component, a first circulation loop, a second circulation loop and a solution concentrating component, wherein the flue gas inlet and the flue gas outlet are respectively connected to the liquid storage tank, the solution spraying component is located in the liquid storage tank, the first circulation loop is used to connect the liquid storage tank with the solution spraying component, and the second circulation loop is used to connect the liquid storage tank with the solution concentrating component; The heat exchange pipeline includes a water inlet, a water outlet and a first heat exchange element. The water inlet and the water outlet are respectively connected to the first heat exchange element. The first heat exchange element is also connected to the first circulation loop and is located between the liquid storage tank and the solution spray element.

[0005] Optionally, the heat exchange pipeline also includes a second heat exchange element, two of which are provided and are both connected to the water inlet and the water outlet, and the two second heat exchange elements are also connected to the waste heat recovery pipeline, one of the second heat exchange elements is located between the flue gas inlet and the liquid storage tank, and the other second heat exchange element is located between the liquid storage tank and the flue gas outlet.

[0006] Optionally, a first control valve is provided in both the first circulation loop and the second circulation loop, and the first control valve is used to open or close the first circulation loop and the second circulation loop.

[0007] Optionally, the solution concentration unit further includes a recovery box, and the recovery box is used to recover the distilled water generated during the solution concentration process.

[0008] Optionally, a water supply pipeline is also included, and the water supply pipeline is used to connect the recovery tank with the heat exchange pipeline.

[0009] Optionally, the flue gas treatment component further includes a demister, and the demister is located above the solution spraying member in the vertical direction.

[0010] Optionally, the solution in the liquid storage tank is a lithium chloride or lithium bromide solution.

[0011] Optionally, a plurality of the flue gas treatment components are provided, and the plurality of the flue gas treatment components are arranged side by side in the vertical direction, and the liquid storage tanks in the plurality of the flue gas treatment components are connected to each other, and adjacent liquid storage tanks are separated by gas-liquid separators.

[0012] Optionally, the heat exchange pipeline includes a plurality of first heat exchange elements, the first heat exchange elements are arranged corresponding to the flue gas treatment components, and the plurality of first heat exchange elements are connected in series and are located between the water inlet and the water outlet.

[0013] Optionally, the flue gas treatment components are provided with three groups, the two groups of the flue gas treatment components located at the top share one solution concentration component, and the second circulation loops in the two groups of the flue gas treatment components are arranged in parallel and are connected to the solution concentration component through a second control valve, and the second control valve is used to control the opening and closing of the second circulation loop.

[0014] Compared with the prior art, the advantages of the present invention are: the flue gas waste heat recovery system of the present invention includes a waste heat recovery pipeline and a heat exchange pipeline, and the water vapor and heat in the flue gas are recovered through a liquid storage tank and a solution spray part in the waste heat recovery pipeline, and the heated solution is then passed through a first heat exchanger to heat the water in the heat exchange pipeline to complete the heat recovery of the flue gas. Since heat recovery is carried out through solution, it has a higher heat absorption efficiency, and the flue gas waste heat recovery system of the present invention is also relatively simple in structure, occupies less space, and is easy to process and use.

[0015] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 Schematic diagram of a flue gas waste heat recovery system provided in an exemplary embodiment of the present disclosure.

[0017] Description of Reference Numerals 1-waste heat recovery pipeline; 11-smoke inlet; 12-smoke outlet; 2-heat exchange pipeline; 21-water inlet; 22-water outlet; 23-first heat exchange element; 24-second heat exchange element; 3- flue gas treatment component; 31- liquid storage tank; 32- first circulation loop; 33- second circulation loop; 34- solution spraying part; 35- solution concentration part; 351- recovery tank; 36- first control valve; 37- demister; 38- second control valve; 4-Water supply pipeline; 5-Gas-liquid isolator. DETAILED DESCRIPTION

[0018] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0019] In the present disclosure, unless otherwise stated, directional words such as "upper, lower, high, low, top, bottom" generally refer to the position of the corresponding component or structure in the direction of gravity. Figure 1 The directions of the drawings shown. "Inside and outside" refer to the inside and outside of the corresponding component outline. In addition, it should be noted that the terms used, such as "first, second", etc., are to distinguish one element from another and have no order or importance. In addition, in the description with reference to the drawings, the same mark in different drawings represents the same element. The above definitions are only used to explain and illustrate the present disclosure and should not be understood as limitations on the present disclosure.

[0020] For ease of understanding, please refer to the attached Figure 1 , the specific structure and working principle of the flue gas waste heat recovery system disclosed in the present invention are explained in detail with reference to the embodiments.

[0021] The present disclosure relates to a flue gas waste heat recovery system, which can effectively recover waste heat in flue gas through a solution to achieve a high recovery efficiency. Figure 1 The flue gas waste heat recovery system disclosed in the present invention includes a waste heat recovery pipeline 1 and a heat exchange pipeline 2. The waste heat recovery pipeline 1 includes a flue gas inlet 11, a flue gas outlet 12 and a flue gas treatment component 3. The flue gas inlet 11 is used to introduce the flue gas to be treated, and the flue gas outlet 12 is used to discharge the treated flue gas. The flue gas treatment component 3 includes a liquid storage tank 31, a solution spraying component 34, a first circulation loop 32, a second circulation loop 33 and a solution concentration component 35.

[0022] The liquid storage tank 31 is used to store the solution and is connected to the flue gas inlet 11 and the flue gas outlet 12. Conventional components such as a desulfurization tower may also be arranged between the flue gas inlet 11 and the liquid storage tank 31. The solution spraying part 34 is located in the liquid storage tank 31. A cellulose hard medium pad or a ceramic medium pad material may be used to reduce the corrosion of the solution spraying part 34 by the flue gas. The first circulation loop 32 can connect the liquid storage tank 31 and the solution spraying part 34, so that the solution in the liquid storage tank 31 can flow to the solution spraying part 34 through the first circulation loop 32, and then spray back into the liquid storage tank 31. The second circulation loop 33 is used to connect the liquid storage tank 31 with the solution concentration part 35. The solution concentration part 35 may be a compressor for concentrating the solution, so that the solution in the liquid storage tank 31 can flow to the solution concentration part 35 through the second circulation loop 33 for concentration, and then flow back to the liquid storage tank 31 from the solution concentration part 35 through the second circulation loop 33 to wait for the next cycle.

[0023] The heat exchange pipeline 2 includes a water inlet 21, a water outlet 22 and a first heat exchange element 23. The first heat exchange element 23 can be a plate heat exchanger or other types of heat exchangers. The water inlet 21 and the water outlet 22 are connected to the first heat exchange element 23, and the first heat exchange element 23 is also connected to the first circulation loop 32 to complete the heat exchange between the water in the heat exchange pipeline 2 and the solution in the first circulation loop 32.

[0024] Specifically, when in use, the flue gas to be treated enters the liquid storage tank 31 from the flue gas inlet 11, and the solution spraying part 34 in the liquid storage tank 31 also sprays the solution into the liquid storage tank 31. The sprayed solution will contact the flue gas, absorb the water vapor and heat in the flue gas, and fall into the liquid storage tank 31. The solution in the liquid storage tank 31 that has completed heat absorption will enter the first circulation loop 32, and flow into the first heat exchanger 23 through the first circulation loop 32 to exchange heat with the water therein, heat the water therein and cool it down, and finally flow to the solution spraying part 34 through the first circulation loop 32 and spray again. When the solution in the liquid storage tank 31 absorbs a large amount of water vapor and the concentration decreases, the solution will enter the solution concentration part 35 through the second circulation loop 33 to be concentrated to maintain the concentration and absorb water, and the concentrated solution will flow back to the liquid storage tank 31 through the second circulation loop 33 for subsequent use. The water to be heated enters the heat exchange pipeline 2 through the water inlet 21 and flows into the first heat exchange element 23 to exchange heat with the solution that has completed heat absorption. The heated water finally flows out of the heat exchange pipeline 2 through the water outlet 22 for subsequent use.

[0025] The flue gas waste heat recovery system disclosed in the present invention absorbs water vapor and heat in the flue gas through a solution in a liquid storage tank 31, and then heats the water in the heat exchange pipeline 2 through the first heat exchange element 23 to complete the heat recovery of the flue gas. Since the heat recovery is carried out through a solution, it has a higher heat absorption efficiency. The flue gas waste heat recovery system disclosed in the present invention is also relatively simple in structure, occupies less space, and is easy to process and use.

[0026] In one embodiment of the present disclosure, see Figure 1 The heat exchange pipeline 2 also includes a second heat exchanger 24, which can be a plate heat exchanger or other types of heat exchangers. Two second heat exchangers 24 are provided, both of which are connected to the water inlet 21 and the water outlet 22, and the two second heat exchangers 24 are also connected to the waste heat recovery pipeline 1, one of the second heat exchangers 24 is located between the flue gas inlet 11 and the liquid storage tank 31, and the other second heat exchanger 24 is located between the liquid storage tank 31 and the flue gas outlet 12. By providing the second heat exchanger 24, before the flue gas enters the liquid storage tank 31 for heat exchange, the second heat exchanger 24 can first exchange heat with the water in the heat exchange pipeline 2, and when the flue gas is about to flow out of the waste heat recovery pipeline 1, the second heat exchanger 24 can exchange heat with the water in the heat exchange pipeline 2 again, thereby improving the efficiency of heat recovery in the flue gas and reducing energy waste.

[0027] In one embodiment of the present disclosure, see Figure 1 , the first circulation loop 32 and the second circulation loop 33 are both provided with a first control valve 36, and the first control valve 36 may be a solenoid valve or other valve bodies. By providing the first control valve 36, the first circulation loop 32 and the second circulation loop 33 can be selectively opened and closed. For example, when recovering flue gas heat, the first circulation loop 32 needs to be opened to circulate the solution. When the solution needs to be concentrated, the first circulation loop 32 can be closed and the second circulation loop 33 can be opened to concentrate the solution, so as to avoid both circulation loops working, thereby reducing the efficiency of solution concentration. Of course, in other embodiments, the components for controlling the opening or closing of the first circulation loop 32 and the second circulation loop 33 may also be of other types, which may be determined according to actual conditions, and the present disclosure does not limit this.

[0028] In one embodiment of the present disclosure, see Figure 1The solution concentration unit 35 includes a recovery box 351. The recovery box 351 can recover the distilled water generated by the solution concentration unit 35 during the solution concentration process. After a certain amount of distilled water is collected, the distilled water can be taken out for reuse to recover water resources in the flue gas. In some other embodiments, the recovery box 351 is connected to the heat exchange pipeline 2 through the water supply pipeline 4. By setting the water supply pipeline 4, after a certain amount of distilled water is collected in the recovery box 351, the distilled water in the recovery box 351 can be transported to the heat exchange pipeline 2 for use. After the distilled water is heat-exchanged by the first heat exchange unit 23 and the second heat exchange unit 24, it can be used subsequently, thereby saving water resources to a certain extent.

[0029] In one embodiment of the present disclosure, see Figure 1 The flue gas treatment assembly 3 further includes a demister 37, which may be a ridge demister, a corrugated plate demister, a wire mesh demister, or other types of demisters 37. The demister 37 may be disposed vertically above the solution spraying member 34, so that the flue gas that has completed heat exchange with the solution can pass through the demister 37 to remove the mist droplets in the flue gas, making the flue gas purer when discharged, and the demister 37 is located above the solution spraying member 34, so as to avoid direct contact with the solution and corrosion by the solution.

[0030] In one embodiment of the present disclosure, the solution in the liquid storage tank 31 for absorbing water vapor and heat in the flue gas is a lithium chloride or lithium bromide solution. The above two solutions are good dehumidifiers, which can better absorb water vapor in the flue gas when in contact with the flue gas, thereby better absorbing the heat in the flue gas, thereby improving the recovery efficiency of the entire flue gas waste heat recovery system. Of course, in other embodiments, the solution in the liquid storage tank 31 can also be other types, which can be determined according to actual conditions, such as the components in the flue gas, the size of the flue gas heat, etc., and the present disclosure does not limit this.

[0031] In one embodiment of the present disclosure, see Figure 1 There are multiple flue gas treatment components 3, and the multiple flue gas treatment components 3 are arranged side by side in the vertical direction. The liquid storage tanks 31 in the multiple flue gas treatment components 3 are connected to each other, and the adjacent liquid storage tanks 31 are separated by a gas-liquid separator 5. The gas-liquid separator 5 can be a plate tower tray. The tower tray (such as a bubble tower tray, a sieve plate tower tray or a floating valve tower tray) is designed to be used to set multiple separation stages in the tower. After the flue gas contacts the liquid through the holes or valves on the tower tray, the liquid flows on the surface of the tower tray, and the gas and liquid achieve a gas-liquid separation effect through continuous multi-stage separation. It can also be a cyclone separator. The cyclone separator uses the rotational motion of the flue gas to separate the flue gas and liquid through centrifugal force. The liquid is thrown to the tower wall and flows down during the rotation, while the flue gas passes through the center.

[0032] By setting up multiple groups of flue gas treatment components 3, multi-stage recovery of flue gas heat can be achieved. After the flue gas passes through each group of flue gas treatment components 3, the heat and water vapor therein will be partially recovered, thereby improving the recovery efficiency of the flue gas waste heat recovery system disclosed in the present invention.

[0033] Specifically, when flue gas treatment is performed, the flue gas to be treated enters the liquid storage tank 31 of the first flue gas treatment component 3 from the flue gas inlet 11, and the solution spraying part 34 in the liquid storage tank 31 sprays the solution to the flue gas so that the solution absorbs the heat and water vapor in the flue gas, and then enters the first circulation loop 32 to exchange heat with the water in the heat exchange pipeline 2. After that, the flue gas will flow out of the first flue gas treatment component 3 and enter the liquid storage tank 31 in the second flue gas treatment component 3 for a second circulation. The above cycle is repeated until the flue gas flows out of the last flue gas treatment component 3 and flows out through the smoke outlet 12, thereby completing the multi-stage recovery of flue gas waste heat and water vapor.

[0034] In one embodiment of the present disclosure, see Figure 1 The heat exchange pipeline 2 includes a plurality of first heat exchange elements 23, the number of which is consistent with the number of flue gas treatment components 3, and is correspondingly arranged in the first circulation loop 32 of each flue gas treatment component 3, and the plurality of first heat exchange elements 23 are connected in series with each other and are located between the water inlet 21 and the water outlet 22, so that the water in the heat exchange pipeline 2 can pass through the plurality of first heat exchange elements 23 in sequence and perform heat exchange with the solution in the first circulation loop 32 of the flue gas treatment component 3 corresponding to each first heat exchange element 23, thereby improving the heating efficiency of the water in the heat exchange pipeline 2.

[0035] In one embodiment of the present disclosure, see Figure 1 , three groups of flue gas treatment components 3 are provided, and the two groups of flue gas treatment components 3 located at the top share a solution concentration component 35, and the second circulation loops 33 in the two groups of flue gas treatment components 3 are arranged in parallel, and the second circulation loops 33 are controlled to be opened and closed by the second control valve 38, and the second circulation loops 33 are controlled to be connected with different flue gas treatment components 3. In this embodiment, the second control valve 38 is a three-way valve to control the opening and closing of the two second circulation loops 33 arranged in parallel, and the second circulation loops 33 are connected with different flue gas treatment components 3.

[0036] Since the water content and calorie content of the flue gas are the largest when the flue gas is passing through the bottom flue gas treatment component 3, the bottom flue gas treatment component 3 uses a solution concentration component 35 alone to ensure the concentration effect of the solution, and the water content and calorie content of the flue gas are reduced when the flue gas passes through the two top flue gas treatment components 3, so that the two top flue gas treatment components 3 share a solution concentration component 35 to meet the solution concentration requirements of the two top flue gas treatment components 3, thereby saving costs and structure, and facilitating use. Of course, in other embodiments, more flue gas treatment components 3 may share a solution concentration component 35, or each flue gas treatment component 3 may use a solution concentration component 35 alone, which can be determined according to actual conditions, and the present disclosure does not limit this.

[0037] When the flue gas waste heat recovery system disclosed in the present invention is in use, the treated flue gas enters the liquid storage tank 31 of the first flue gas treatment component 3 from the flue gas inlet 11, and the solution spraying part 34 in the liquid storage tank 31 sprays the solution to the flue gas so that the solution absorbs the heat and water vapor in the flue gas, and then enters the first circulation loop 32 to exchange heat with the water in the heat exchange pipeline 2, and flows back to the solution spraying part 34 through the first circulation loop 32 to be sprayed into the liquid storage tank 31 for circulation again. After the concentration of the solution in the liquid storage tank 31 is reduced, the solution will pass through the second circulation loop 33 to enter the solution concentration part 35 for concentration to maintain the concentration and absorb water, and the concentrated solution will flow back to the liquid storage tank 31 through the second circulation loop 33 for subsequent use. After the flue gas flows out of the first flue gas treatment component 3, it will enter the liquid storage tank 31 in the second flue gas treatment component 3 for a second circulation, and repeat the above cycle until the flue gas flows out of the last flue gas treatment component 3 through the flue gas outlet 12, thereby completing the multi-stage recovery and utilization of flue gas waste heat and water vapor.

[0038] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0039] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0040] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A flue gas waste heat recovery system, characterized in that: include: A waste heat recovery pipeline, comprising a flue gas inlet, a flue gas treatment component and a flue gas outlet, wherein the flue gas treatment component comprises a liquid storage tank, a solution spraying component, a first circulation loop, a second circulation loop and a solution concentrating component, wherein the flue gas inlet and the flue gas outlet are respectively connected to the liquid storage tank, the solution spraying component is located in the liquid storage tank, the first circulation loop is used to connect the liquid storage tank with the solution spraying component, and the second circulation loop is used to connect the liquid storage tank with the solution concentrating component; The heat exchange pipeline includes a water inlet, a water outlet and a first heat exchange element. The water inlet and the water outlet are respectively connected to the first heat exchange element. The first heat exchange element is also connected to the first circulation loop and is located between the liquid storage tank and the solution spray element.

2. The flue gas waste heat recovery system according to claim 1, characterized in that: The heat exchange pipeline also includes a second heat exchange element, two of which are connected to the water inlet and the water outlet, and the two second heat exchange elements are also connected to the waste heat recovery pipeline, one of the second heat exchange elements is located between the flue gas inlet and the liquid storage tank, and the other second heat exchange element is located between the liquid storage tank and the flue gas outlet.

3. The flue gas waste heat recovery system according to claim 1, characterized in that: The first circulation loop and the second circulation loop are both provided with a first control valve, and the first control valve is used to open or close the first circulation loop and the second circulation loop.

4. The flue gas waste heat recovery system according to claim 1, characterized in that: The solution concentration unit further includes a recovery box, which is used to recover distilled water generated during the solution concentration process.

5. The flue gas waste heat recovery system according to claim 4, characterized in that: It also includes a water supply pipeline, which is used to connect the recovery tank with the heat exchange pipeline.

6. The flue gas waste heat recovery system according to claim 1, characterized in that: The flue gas treatment component also includes a demister, which is located above the solution spraying member in the vertical direction.

7. The flue gas waste heat recovery system according to claim 1, characterized in that: The solution in the liquid storage tank is lithium chloride or lithium bromide solution.

8. The flue gas waste heat recovery system according to any one of claims 1 to 7, characterized in that: There are multiple flue gas treatment components, and the multiple flue gas treatment components are arranged side by side in the vertical direction. The liquid storage tanks in the multiple flue gas treatment components are connected to each other, and adjacent liquid storage tanks are separated by gas-liquid separators.

9. The flue gas waste heat recovery system according to claim 8, characterized in that: The heat exchange pipeline includes a plurality of first heat exchange components, which are arranged corresponding to the flue gas treatment components, and the plurality of first heat exchange components are connected in series and are located between the water inlet and the water outlet.

10. The flue gas waste heat recovery system according to claim 8, characterized in that: The flue gas treatment components are arranged in three groups, the two groups of flue gas treatment components located at the top share one solution concentration component, and the second circulation loops in the two groups of flue gas treatment components are arranged in parallel and connected to the solution concentration component through the control of a second control valve, and the second control valve is used to control the opening and closing of the second circulation loop.

Images