A combined heat and power waste heat utilization energy-saving system

Abstract

The application provides a combined heat and power waste heat utilization energy-saving system, which comprises a steam turbine, a heat exchange device connected with the steam turbine through a first heating pipeline, a first condensing device connected with the heat exchange device through a first condensing pipeline, and the first condensing device connected with the steam turbine through a first backflow pipeline; the heat exchange device; a first heat pump connected with the heat exchange device through a heat recovery pipeline, the first heat pump connected with the steam turbine through the first backflow pipeline, the steam turbine connected with the first heat pump through a first heating pipeline, and the first heating pipeline connected with the first condensing device after passing through the first heat pump; and a compression heat pump unit comprising a compression heat pump, a compression heat pump condensing device, a compression heat pump user and a first heating device. The application utilizes the heat energy of backflow water, improves the absorption of waste heat by backflow water and increases the utilization rate of waste heat.

Description

Technical Field

[0001] This invention relates to an energy-saving system for utilizing waste heat from combined heat and power (CHP) plants, belonging to the field of waste heat technology. Background Technology

[0002] With technological advancements, my country has developed numerous waste heat utilization technologies for thermal power plants. Two relatively mature methods are: The first involves upgrading the unit to increase the waste heat temperature, sacrificing some of the steam's power generation, and raising the waste water temperature to around 60 degrees Celsius for direct use in centralized heating. The second method utilizes low-temperature waste heat, currently primarily through heat pump technology. Driven by a portion of electricity or a high-temperature heat transfer medium, the low-temperature waste heat is extracted to a higher temperature for use as chilled water waste heat in the power plant or for heating return water. The first method is not suitable for larger units and has low operating efficiency outside the winter heating season, making it unsuitable for widespread adoption. The second method currently faces challenges due to the small temperature difference between the return water and the power plant's chilled water waste heat, resulting in low return water heat absorption efficiency and inefficient preheating. Summary of the Invention

[0003] Based on the above background, the purpose of this invention is to provide an energy-saving system for utilizing waste heat from combined heat and power (CHP) to solve the problems described in the background art.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] The steam turbine is connected to a heat exchange device via a first heating pipe.

[0006] The first condensing device is connected to the heat exchange device via a first condensing pipe. The first condensing pipe is equipped with a first condensing pipe valve. The first condensing device is connected to the steam turbine via a first return pipe.

[0007] Heat exchange device;

[0008] The first heat pump is connected to the heat exchange device via a regenerative pipe, the regenerative pipe being equipped with a regenerative pipe valve. The first heat pump is connected to the main steam turbine via a first return pipe, the main steam turbine being connected to the first heat pump via a first heating pipe, the first heating pipe passing through the first heat pump and then connected to the first condensing device, the first heating pipe being equipped with a first heating pipe valve.

[0009] The first energy-consuming terminal is connected to the heat exchange device through the first return water pipe, and the heat exchange device is connected to the first energy-consuming terminal through the outlet water pipe. The first return water pipe passes through the first heat pump.

[0010] A compression heat pump unit includes a compression heat pump, a compression heat pump condenser, a compression heat pump user, and a first heating device. A first return water pipe passes through the compression heat pump. The first heating device is connected to the compression heat pump condenser via a second heating pipe, which also passes through the compression heat pump. The compression heat pump user is connected to the compression condenser via a second condensing pipe, which also passes through the compression heat pump.

[0011] By using a secondary gradient utilization method to reduce the temperature of the heating return water, the temperature difference between the return water and the outlet water of the heat exchange device is increased. This fully utilizes the temperature of the return water, increases the utilization rate of low-quality energy, and increases the utilization of waste heat by increasing the temperature difference between the return water and the outlet water of the heat exchange device. This reduces the energy consumption for reheating the return water, lowers costs, and meets the requirements of environmental protection and energy conservation.

[0012] Preferably, the combined heat and power (CHP) waste heat utilization energy-saving system further includes a second energy-consuming terminal, a flue gas heating device, a second heat pump, and a second condensing device. A second return pipe is also provided between the heat exchange device and the steam turbine, passing through the second heat pump, and is equipped with a second return pipe valve. During normal low-power operation, the heat from the steam turbine is not used to heat the first return water pipe; the waste heat is only converted into output through the first condensing device. By setting up the second energy-consuming terminal, the waste heat utilization efficiency is improved.

[0013] Preferably, the flue gas heating device is connected to the second condensing device through a second heating pipe, the second heating pipe passing through the second heat pump, and the second energy-consuming terminal is connected to the second condensing device through a second return water pipe, the second return water pipe passing through the second heat pump.

[0014] Preferably, the second heat pump is further equipped with a second heating device, which is connected to the second condensing device via a third heating pipe that passes through the second heat pump. Due to the uncertainty of the turbine return water direction and the fluctuation of flue gas waste heat with flue gas volume, adding a second heating device supplements the heat source of the second heat pump, helping to stabilize the heat supply to users and enhance stability.

[0015] Preferably, the heat source for the flue gas heating device is boiler exhaust or deaerator steam. Besides the heated return water, another portion of the waste heat is contained in the flue gas. By adding a second heat pump, the waste heat from the flue gas is absorbed to heat the second condenser pipe after heat exchange, enabling the recovery and reuse of low-quality energy and increasing the utilization rate of waste heat.

[0016] Preferably, the first heating pipe, the second heating pipe, the first warming pipe, the second warming pipe, the third warming pipe, the first condensing pipe, the second condensing pipe, the first return pipe, the second return pipe, the reheat pipe, the first return water pipe, and the second return water pipe are provided with an outer insulation sleeve.

[0017] Preferably, the first heating device is a solar heating device.

[0018] Preferably, the inlet water temperature of the heat exchange device is 100-120°C, and the outlet water temperature of the heat exchange device is 50-70°C.

[0019] Preferably, the inlet water temperature of the first return water pipe to the compression heat pump is 50-70°C, and the outlet water temperature of the first return water pipe after passing through the compression heat pump is 20-40°C.

[0020] Preferably, the inlet water temperature of the first return water pipe to the first heat pump is 20-40°C, and the outlet water temperature of the first return water pipe after passing through the first heat pump is 70-90°C.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The present invention discloses a cogeneration waste heat utilization energy-saving system that utilizes gradient utilization of return water heat energy, reduces the temperature of the heating return water, increases the temperature difference between the return water and the outlet water of the heat exchange device, makes full use of the temperature of the return water, increases the utilization rate of low-quality energy, and improves the absorption of waste heat by the return water by increasing the temperature difference between the return water and the outlet water of the heat exchange device, thereby increasing the waste heat utilization rate. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of the first embodiment of the cogeneration waste heat utilization energy-saving system of the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of a second embodiment of an energy-saving system for utilizing waste heat from a combined heat and power plant according to the present invention;

[0026] Figure 3 yes Figure 1 A magnified schematic diagram of part A in the middle.

[0027] In the diagram: 1. Steam turbine; 2. First condensing unit; 3. First heating pipe; 4. Heat exchanger; 5. First return water pipe; 6. Outlet water pipe; 7. First energy consumption terminal; 8. Compression heat pump; 9. Second condensing pipe; 10. Compression heat pump user; 11. Compression heat pump condensing unit; 12. Second heating pipe; 13. First heating unit; 14. First heat pump; 15. First heating pipe; 16. First return pipe; 17. First heating pipe valve; 18. Third heating pipe; 19. Second energy consumption terminal; 20. Second return water pipe; 21. Second condensing unit; 22. Second heating pipe; 23. Flue gas heating unit; 24. Second heat pump; 25. Second return pipe valve; 26. Second return pipe; 27. Second heating unit; 28. First condensing pipe; 29. ​​First condensing pipe valve; 30. Regenerative pipe; 31. Regenerative pipe valve. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention.

[0029] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art. Unless otherwise specified, the components or equipment in the following embodiments are general standard parts or components known to those skilled in the art, and their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0030] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In this detailed description, numerous specific details are set forth to facilitate explanation and provide a thorough understanding of the embodiments of the present invention. However, one or more embodiments may be practiced by those skilled in the art without these specific details.

[0031] First Embodiment

[0032] like Figure 1 and Figure 3 The energy-saving system for waste heat utilization in cogeneration, as shown, includes a steam turbine 1, a first condensing unit 2, a heat exchange unit 4, a first heat pump 14, a first energy-consuming terminal 7, and a compression heat pump unit 8.

[0033] The steam turbine 1 is connected to the heat exchange device 4 via the first heating pipe 3. The heat exchange device 4 is connected to the first condensing device 2 via the first condensing pipe 28, which is equipped with a first condensing pipe valve 29. The first condensing device 2 is connected to the steam turbine 1 via the first return pipe 16.

[0034] The first heat pump 14 is connected to the heat exchange device 4 through the regenerative pipe 30. The regenerative pipe 30 is equipped with a regenerative pipe valve 31. The first heat pump 14 is connected to the main steam turbine 1 through the first return pipe 16. The main steam turbine 1 is connected to the first heat pump 14 through the first heating pipe 15. The first heating pipe 15 passes through the first heat pump 14 and is connected to the first condensing device 2. The first heating pipe 15 is equipped with a first heating pipe valve 17.

[0035] The first energy-consuming terminal 7 is connected to the heat exchange device 4 through the first return water pipe 5, and the heat exchange device 4 is connected to the first energy-consuming terminal 7 through the outlet water pipe 6. The first return water pipe 5 passes through the first heat pump 14.

[0036] The compression heat pump unit 8 includes a compression heat pump 8, a compression heat pump condenser 11, a compression heat pump user 10, and a first heating device 13. A first return water pipe 5 passes through the compression heat pump 8. The first heating device 13 is connected to the compression heat pump condenser 11 via a second heating pipe 12; the first heating device 13 is a solar heating device. The second heating pipe 12 passes through the compression heat pump 8. The compression heat pump user 10 is connected to the compression condenser via a second condensing pipe 9, which also passes through the compression heat pump 8.

[0037] Second Embodiment

[0038] like Figure 2 The cogeneration waste heat utilization energy-saving system shown has the same technical solution as the first embodiment, except that: the cogeneration waste heat utilization energy-saving system also includes a second energy-consuming terminal 19, a flue gas heating device 23, a second heat pump 24, and a second condensing device 21. A second return pipe 26 is also provided between the heat exchange device 4 and the steam turbine 1. The second return pipe 26 passes through the second heat pump 24 and is equipped with a second return pipe valve 25.

[0039] The flue gas heating device 23 is connected to the second condensing device 21 via a second heating pipe 22. The heat source for the flue gas heating device 23 is boiler exhaust gas, deaerator exhaust steam, etc. The second heating pipe 22 passes through the second heat pump 24. The second energy-consuming terminal 19 is connected to the second condensing device 21 via a second return water pipe 20, which also passes through the second heat pump 24. The second heat pump 24 is also equipped with a second heating device 27, which is connected to the second condensing device 21 via a third heating pipe 18, which also passes through the second heat pump 24.

[0040] To reduce heat loss during pipeline transfer, the first heating pipeline 3, the second heating pipeline 22, the first heating pipeline 15, the second heating pipeline 12, the third heating pipeline 18, the first condensing pipeline 28, the second condensing pipeline 9, the first return pipeline 16, the second return pipeline 26, the reheat pipeline 30, the first return water pipeline 5, and the second return water pipeline 20 are equipped with external insulation sleeves.

[0041] The inlet water temperature from the first heating pipe 3 to the heat exchange device 4 is 100–120°C, and the outlet water temperature from the heat exchange device 4 to the regenerative pipe 30 is 50–70°C. The inlet water temperature from the first return water pipe 5 to the compression heat pump 8 is 50–70°C, and the outlet water temperature from the first return water pipe 5 after passing through the compression heat pump 8 is 20–40°C. The inlet water temperature from the first return water pipe to the first heat pump 14 is 20–40°C, and the outlet water temperature from the first return water pipe 5 after passing through the first heat pump 14 is 70–90°C.

[0042] During normal operation, the first condensing pipe valve 29 is open, while the regenerative pipe valve 31 remains closed. Steam is extracted from the turbine 1, and the high-temperature gas travels along the first heating pipe 3 to the heat exchange device 4, heating the loop pipe between the heat exchange device 4 and the first energy-consuming terminal 7. The cooled gas-liquid mixture then reaches the first condensing device 2, and after further cooling, returns to the turbine 1. The outlet pipe 6 carries the heated liquid to the first energy-consuming terminal 7. After passing through the first energy-consuming terminal 7, the heat-loss liquid travels through the first return pipe 16 to the heat exchange device 4. The first return pipe 16 then passes through the compression heat pump 8, where it exchanges heat with the compression heat pump 8 and the compression heat pump condensing device 11. The first heating device 13 then replenishes some heat to the pipes, meeting the energy requirements of the compression heat pump user 10.

[0043] When the heat from the first energy-consuming terminal 7 increases, the regenerative pipeline valve 31 is opened, and a portion of the first condensing pipeline valve 29 is closed. The degree to which the regenerative pipeline valve 31 is opened and the first condensing pipeline 29 is closed varies depending on the degree of heat from the first energy-consuming terminal 7. After the regenerative pipeline 30 is opened, the first return water pipeline 5 of the turbine 1 transfers a portion of the heat to the first return water pipeline 5 through heat exchange via the first heat pump 14. After the heat exchange, the turbine 1 heats the first heat pump 14 through the first heating pipeline 15, thereby increasing the return water temperature and reducing the temperature difference between the return water temperature and the outlet water pipeline 6, thus reducing the power consumption of the turbine 1 and reducing the steam extraction rate of the turbine 1. At the same time, the compression heat pump 8 performs a pre-heat exchange on the first return water pipeline 5, reducing the temperature of the first return water pipeline 5, thereby increasing the temperature difference between the first return water pipeline 5 and the regenerative pipeline 30, increasing the absorption of waste heat, and achieving the design objective of increasing waste heat utilization.

[0044] When the second heat pump 24 is added, and the power is normal and there is no need to use return water heating, the heat in the flue gas and the heat in the second return pipe 26 are used to heat the second energy-consuming terminal 19. This can effectively utilize the turbine heat when there is no return water heating, and use the waste heat energy in the flue gas, increasing the types of waste heat utilization and improving the waste heat utilization rate.

[0045] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An energy-saving system for utilizing waste heat from combined heat and power (CHP) plants, characterized in that: This combined heat and power waste heat utilization energy-saving system includes: A steam turbine (1) is connected to a heat exchange device (4) via a first heating pipe (3). The first condensing device (2) is connected to the heat exchange device (4) via the first condensing pipe (28). The first condensing pipe (28) is equipped with a first condensing pipe valve (29). The first condensing device (2) is connected to the steam turbine (1) via the first return pipe (16). Heat exchange device (4); The first heat pump (14) is connected to the heat exchange device (4) through a heat recovery pipe (30). The heat recovery pipe (30) is equipped with a heat recovery pipe valve (31). The first heat pump (14) is connected to the main steam turbine (1) through a first return pipe (16). The main steam turbine (1) is connected to the first heat pump (14) through a first heating pipe (15). The first heating pipe (15) passes through the first heat pump (14) and is connected to the first condensing device (2). The first heating pipe (15) is equipped with a first heating pipe valve (17). The first energy-consuming terminal (7) is connected to the heat exchange device (4) through the first return water pipe (5), and the heat exchange device (4) is connected to the first energy-consuming terminal (7) through the outlet water pipe (6). The first return water pipe (5) passes through the first heat pump (14). A compression heat pump (8) unit, comprising a compression heat pump (8), a compression heat pump condenser (11), a compression heat pump user (10), and a first heating device (13). The first return water pipe (5) passes through the compression heat pump (8). The first heating device (13) is connected to the compression heat pump condenser (11) through a second heating pipe (12). The second heating pipe (12) passes through the compression heat pump (8). The compression heat pump user (10) is connected to the compression condenser through a second condensing pipe (9). The second condensing pipe (9) passes through the compression heat pump (8).

2. The cogeneration waste heat utilization energy-saving system according to claim 1, characterized in that: The combined heat and power waste heat utilization energy-saving system also includes a second energy-consuming terminal (19), a flue gas heating device (23), a second heat pump (24), and a second condensing device (21). A second return pipe (26) is also provided between the heat exchange device (4) and the steam turbine (1). The second return pipe (26) passes through the second heat pump (24), and the second return pipe (26) is equipped with a second return pipe valve (25).

3. The cogeneration waste heat utilization energy-saving system according to claim 2, characterized in that: The flue gas heating device (23) is connected to the second condensing device (21) through the second heating pipe (22), the second heating pipe (22) passes through the second heat pump (24), and the second energy-consuming terminal (19) is connected to the second condensing device (21) through the second return water pipe (20), the second return water pipe (20) passes through the second heat pump (24).

4. The cogeneration waste heat utilization energy-saving system according to claim 3, characterized in that: Preferably, the second heat pump (24) is further provided with a second heating device (27), which is connected to the second condensing device (21) through a third heating pipe (18), which passes through the second heat pump (24).

5. The cogeneration waste heat utilization energy-saving system according to claim 4, characterized in that: The heat source of the flue gas heating device (23) is boiler exhaust, deaerator exhaust steam, etc.

6. The cogeneration waste heat utilization energy-saving system according to claim 1, characterized in that: The first heating pipe (3), the second heating pipe (22), the first heating pipe (15), the second heating pipe (12), the third heating pipe (18), the first condensing pipe (28), the second condensing pipe (9), the first return pipe (16), the second return pipe (26), the reheat pipe (30), the first return water pipe (5), and the second return water pipe (20) are provided with an outer insulation sleeve.

7. The cogeneration waste heat utilization energy-saving system according to claim 1, characterized in that: The first heating device (13) is a solar heating device.

8. The cogeneration waste heat utilization energy-saving system according to claim 1, characterized in that: The inlet water temperature from the first heating pipe (3) to the heat exchange device (4) is 100-120°C, and the outlet water temperature from the heat exchange device (4) to the regenerating pipe (30) is 50-70°C.

9. The cogeneration waste heat utilization energy-saving system according to claim 1, characterized in that: The inlet water temperature of the first return water pipe (5) to the compression heat pump (8) is 50-70℃, and the outlet water temperature of the first return water pipe (5) after passing through the compression heat pump (8) is 20-40℃.

10. The cogeneration waste heat utilization energy-saving system according to claim 1, characterized in that: The inlet water temperature of the first return water pipe to the first heat pump (14) is 20-40℃, and the outlet water temperature of the first return water pipe (5) after passing through the first heat pump (14) is 70-90℃.

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