A waste heat recovery device that uses an ejector to self-regulate the back pressure of a condenser

Abstract

The present invention relates to the technical field of clean heating, and in particular to a novel waste heat recovery device that uses an ejector to automatically adjust the back pressure of a condenser. It includes a steam turbine, an ejector, a waste steam reheater, a condenser, and a condensate cooler; to solve the technical problems that the outlet water temperature of the condenser cooling water is mainly determined by the exhaust back pressure of the steam turbine and the absolute pressure in the condenser is lower than the exhaust back pressure of the steam turbine, resulting in limited adjustment of the outlet water temperature of the condenser cooling water and being lower than the condensate temperature under the exhaust back pressure of the steam turbine. The adjustment is more free, and the outlet water temperature of the cooling water of the condenser is higher; the waste steam reheater reduces the energy consumption of high-temperature and high-pressure steam by heating waste steam to generate high-temperature and high-pressure steam.

Description

Technical Field

[0001] The present invention relates to the technical field of clean heating, and particularly to a new waste heat recovery device that uses an ejector to automatically adjust the back pressure of a condenser. Background Art

[0002] Cogeneration is a common centralized heating method in the northern regions of China. Common methods include traditional extraction condensing heating, absorption heat pump heating technology, and high back pressure retrofit technology. Among them, high back pressure retrofit is a relatively common retrofit plan, which is widely used due to its characteristics of being clean, environmentally friendly, and having high waste heat recovery efficiency. The Taigu heating project is one of the relatively successful cases of high back pressure retrofit. The entire project mainly adopts two core technologies: low-grade energy hierarchical heating technology and high back pressure retrofit technology. In the application of high back pressure technology, its back pressure is mainly determined by the exhaust device of the steam turbine. In addition, in order to allow the exhaust steam to smoothly enter the condenser, a vacuum extraction pipeline is also provided in the condenser. In the prior art, on the one hand, the outlet water temperature of the cooling water in the condenser is mainly determined by the exhaust back pressure of the steam turbine, so the adjustment of the outlet water temperature of the condenser is limited; on the other hand, due to the existence of the vacuum pump, the absolute pressure in the condenser is usually less than the exhaust back pressure of the steam turbine, directly resulting in a relatively low outlet water temperature of the cooling water in the condenser. Summary of the Invention

[0003] The purpose of the present invention is to provide a waste heat recovery device that uses an ejector to automatically adjust the back pressure of a condenser, so as to solve the technical problems that the outlet water temperature of the cooling water in the condenser is mainly determined by the exhaust back pressure of the steam turbine and the absolute pressure in the condenser is lower than the exhaust back pressure of the steam turbine, resulting in limited adjustment of the outlet water temperature of the cooling water in the condenser and being lower than the condensation water temperature under the exhaust back pressure of the steam turbine.

[0004] To achieve the above purpose, an embodiment of the present invention provides a waste heat recovery device that uses an ejector to automatically adjust the back pressure of a condenser, including a steam turbine, an ejector, an exhaust steam reheater, a condenser, and a condensate cooler; the water inlet end of the steam turbine is connected to the hot side outlet pipeline of the condensate cooler, and the exhaust device of the steam turbine is respectively connected to the secondary fluid inlet end of the ejector and the inlet pipeline of the exhaust steam reheater; the outlet end of the exhaust steam reheater is connected to the primary fluid inlet pipe of the ejector; at the same time, the outlet pipeline of the ejector is connected to the hot side inlet pipeline of the condenser; the circulating water return pipeline is connected to the cold side inlet of the condenser, and the inlet and outlet of the condensate cooler are connected to the circulating water return pipeline; the connection position of the inlet connection pipeline of the condensate cooler on the circulating water return pipeline is farther from the condenser than the connection position of the outlet connection pipeline of the condensate cooler on the circulating water return pipeline to the condenser.

[0005] Furthermore, the condensate cooler is used for waste heat recovery of the condensate water of a condenser with a higher back pressure.

[0006] Further, the ejector is a steam ejector, which draws in the exhausted steam through high-temperature and high-pressure steam, thereby increasing the back pressure in the condenser.

[0007] Further, the exhausted steam reheater heats the exhausted steam discharged from the steam turbine to generate high-temperature and high-pressure steam, which is used as the primary fluid of the ejector for the ejector.

[0008] Further, the water inlet end of the steam turbine is connected to the hot-side outlet pipeline of the condensate cooler through a first butterfly valve, and the exhaust device of the steam turbine is connected to the secondary fluid inlet of the ejector through a first gate valve and a sixth butterfly valve; the water outlet end of the steam turbine is connected to the inlet of the exhausted steam reheater through a first gate valve, a second butterfly valve and a ball valve; the outlet of the exhausted steam reheater is connected to the inlet of the primary fluid of the ejector through a third butterfly valve and a seventh butterfly valve; meanwhile, the outlet pipeline of the ejector is connected to the hot-side inlet pipeline of the condenser; the hot-side outlet of the condenser condensate on the condenser is connected to the hot-side inlet pipeline of the condensate cooler through a second gate valve and an eighth butterfly valve; the outer end of the cold-side inlet pipe of the condenser is connected to the cooling circulating water return pipeline, and the cold-side inlet pipe of the condenser is also connected to the condensate cooler cooling water return pipeline on the condensate cooler through a third gate valve; the cold-side inlet pipe of the condenser is also connected to the condensate cooler cooling water supply pipeline on the condensate cooler through a ninth butterfly valve, and the cold-side outlet pipe of the condenser is connected to the outlet pipeline of the circulating water.

[0009] The beneficial effects of the embodiment of the present invention compared with the prior art are as follows: the back pressure in the condenser is jointly determined by the ejector and the exhaust device of the steam turbine, and the adjustment is more flexible; by arranging both the inlet pipeline and the outlet pipeline of the condensate cooler on the circulating water return pipeline, the back pressure in the condenser is higher than the exhaust back pressure of the steam turbine, and the outlet water temperature of the cooling water in the condenser is higher; the exhausted steam reheater generates high-temperature and high-pressure steam by heating the exhausted steam, thereby reducing the energy consumption of the high-temperature and high-pressure steam; the setting of the condensate condenser can further reduce the temperature of the condensate, recover the waste heat to the greatest extent, eliminate the cold-end loss, and make the energy utilization rate of the entire waste heat recovery device reach 100%. Description of the Drawings

[0010] Figure 1 is a schematic structural diagram of the present invention.

[0011] Description of the reference numerals in the drawings: 1. Steam turbine; 2. Injector; 3. Reheater for exhaust steam; 4. Condenser; 5. Condensate cooler; 6.1. First gate valve; 6.2. Second gate valve; 7. Ball valve; 8. Butterfly valve; 8.1. First butterfly valve; 8.2. Second butterfly valve; 8.3. Third butterfly valve; 8.4. Fourth butterfly valve; 8.5. Fifth butterfly valve; 8.6. Sixth butterfly valve; 8.7. Seventh butterfly valve; 8.8. Eighth butterfly valve; 8.9. Ninth butterfly valve; 9. Multiple high-temperature and high-pressure steam pipes; 10. Connecting bypass; 11. Inlet pipe of the cold side of the condenser; 12. Outlet pipe of the cold side of the condenser; 13. Hot-side outlet of the condensate of the condenser; 14. Return pipe of the cooling water of the condensate cooler; 15. Supply pipe of the cooling water of the condensate cooler. Detailed implementation manners

[0012] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0013] The terms "first" and "second" in the description and claims of the embodiments of the present invention are used to distinguish different objects, rather than to describe a specific order of the objects. For example, the first parameter set and the second parameter set are used to distinguish different parameter sets, rather than to describe a specific order of the parameter sets.

[0014] In the description of the embodiments of the present invention, unless otherwise specified, the meaning of "a plurality of" refers to two or more. For example, a plurality of elements refers to two elements or more than two elements.

[0015] The term "and / or" in this article is a correlation relationship describing associated objects, indicating that three relationships may exist. For example, a display panel and / or a backlight may represent: the display panel exists alone, the display panel and the backlight exist simultaneously, and the backlight exists alone. The symbol " / " in this article represents an "or" relationship between associated objects. For example, input / output represents input or output.

[0016] In the embodiments of the present invention, words such as "exemplary" or "for example" are used to represent examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present invention should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Exactly speaking, using words such as "exemplary" or "for example" aims to present relevant concepts in a specific manner.

[0017] Please refer to Figure 1, the present invention provides the following technical solution: A waste heat recovery device that uses an ejector to automatically adjust the back pressure of a condenser, including a steam turbine 1, an ejector 2, a waste steam reheater 3, a condenser 4, and a condensate cooler 5; the water inlet end of the steam turbine 1 is connected to the hot side outlet pipeline of the condensate cooler 5, and the exhaust device of the steam turbine 1 is respectively connected to the secondary fluid inlet end of the ejector 2 and the inlet pipeline of the waste steam reheater 3; the outlet end of the waste steam reheater 3 is connected to the primary fluid inlet pipe of the ejector 2; at the same time, the outlet pipeline of the ejector 2 is connected to the hot side inlet pipeline of the condenser 4; the outlet end of the waste steam reheater 3 is connected to the outlet pipeline of the ejector 2; at the same time, the outlet pipeline of the ejector 2 is connected to the hot side inlet pipeline of the condenser 4; the hot side outlet 13 of the condensate in the condenser 4 is connected to the water inlet pipeline of the steam turbine 1 through the condensate cooler 5; the cold side inlet pipe 11 of the condenser is connected to the water inlet of the cooling circulating water pipeline, and at the same time is connected to the condensate cooler cooling water supply pipe 15 and the condensate cooler 5 through the condensate cooler cooling water return pipe 14; the cold side outlet pipe 12 of the condenser 4 is connected to the outlet of the cooling circulating water pipeline.

[0018] Working principle: The waste steam with waste heat is discharged from the steam turbine 1 and enters the condenser 4 under the entrainment of the ejector 2. During this process, the ejector 2 can freely adjust the back pressure in the condenser 4 by changing the parameters of the ejector 2, flexibly adjust the outlet temperature of the cooling water in the condenser 4 and the outlet temperature of the condensate. Then the condensate enters the condensate cooler 5 through the pipeline, and the temperature of the condensate is further reduced through the condensate cooler 5, aiming to improve the energy utilization efficiency. The circulating water, as the carrier of waste heat recovery, mainly obtains heat through heat exchange with the condenser 4, supplemented by obtaining heat from the condensate cooler 5. Thus, it solves the technical problems that the outlet temperature of the condenser cooling water is mainly determined by the exhaust back pressure of the steam turbine 1 and the absolute pressure in the condenser 4 is lower than the exhaust back pressure of the steam turbine 1, resulting in limited adjustment of the outlet temperature of the condenser cooling water and being lower than the condensate temperature under the exhaust back pressure of the steam turbine. By setting both the inlet pipeline and the outlet pipeline of the condensate cooler 5 on the circulating water return pipeline, the back pressure in the condenser is higher than the exhaust back pressure of the steam turbine, and the outlet temperature of the cooling water in the condenser is higher.

[0019] In order to make the operation of the entire system more reliable, further, a connection bypass 10 and a multi - selection high - temperature and high - pressure steam pipe 9 are also provided on the inlet pipeline of the primary fluid of the ejector 2. By setting a connection bypass 10 parallel to the waste steam reheater 3 on the ejector 2, it is connected to the multi - selection high - temperature and high - pressure steam pipe 9. Thus, in the case of a failure of the waste steam reheater 3, the inlet end valve of the waste steam reheater 3 can be closed in time, and at the same time, the control switches of the connection bypass 10 and the multi - selection high - temperature and high - pressure steam pipe 9 are opened, so as to use the multi - selection high - temperature and high - pressure steam pipe 9 to replace the waste steam reheater 3 to heat the waste steam. Make the operation of the entire equipment more reliable.

[0020] Exemplary: The multi - select high - temperature and high - pressure steam pipe 9 is connected to the power plant's coal gas, thus realizing the effective utilization of resources.

[0021] Exemplary, the condensate cooler 5 is more suitable for the waste heat recovery of the condensate of a higher - back - pressure condenser.

[0022] Exemplary, the ejector 2 is a steam ejector, which induces the exhausted steam through high - temperature and high - pressure steam, thereby increasing the back - pressure in the condenser 4.

[0023] Exemplary, the exhausted - steam reheater 3 heats the exhausted steam discharged from the steam turbine 1 to generate high - temperature and high - pressure steam, which is used as the primary fluid of the ejector 2 for the ejector 2.

[0024] In an embodiment of the present invention, the water inlet end of the steam turbine 1 is connected to the hot - side outlet pipeline of the condensate cooler 5 through the first butterfly valve 8.1, and the exhaust device of the steam turbine 1 is connected to the inlet of the ejector 2 through the first gate valve 6.1 and the sixth butterfly valve 8.6; the exhaust device of the steam turbine 1 is connected to the inlet end of the exhausted - steam reheater 3 through the first gate valve 6.1, the second butterfly valve 8.2 and the ball valve 7; the outlet of the exhausted - steam reheater 3 is connected to the primary - fluid inlet pipeline of the ejector 2 through the third butterfly valve 8.3 and the seventh butterfly valve 8.7; meanwhile, the outlet pipeline of the ejector 2 is connected to the hot - side inlet pipeline of the condenser 4; the hot - side outlet 13 of the condenser condensate on the condenser 4 is connected to the condensate cooler 5 through the second gate valve 6.2 and the eighth butterfly valve 8.8; the outer end of the cold - side inlet pipe 11 of the condenser 4 is connected to the cooling - circulating - water return pipeline, and the cold - side inlet pipe 11 of the condenser 4 is also connected to the condensate - cooler cooling - water return pipe 14 on the condensate cooler 5 through the third gate valve 6.3; the cold - side inlet pipe 11 of the condenser 4 is also connected to the condensate - cooler cooling - water supply pipe 15 on the condensate cooler 5 through the ninth butterfly valve 8.9. Thus, after the circulating water passes through the return pipeline, part of it directly enters the condenser 4, and the other part enters the condensate cooler 5 through the condensate - cooler cooling - water supply pipe 15 on the condensate cooler 5, then returns through the condensate - cooler cooling - water return pipe 14 and then enters the condenser 4 again. Therefore, compared with directly connecting the condensate - cooler cooling - water return pipe 14 on the condensate cooler 5 to the circulating - water outlet pipeline, the outlet temperature of the circulating water can be significantly increased.

[0025] A connection bypass 10 is also connected to the pipeline between the third butterfly valve 8.3 and the extraction steam reheater 3. The connection bypass 10 is connected to the multi-select high-temperature and high-pressure steam pipe 9 through the fourth butterfly valve 8.4 and the fifth butterfly valve 8.5. The primary fluid inlet pipeline of the ejector 2 is connected to the multi-select high-temperature and high-pressure steam pipe 9 through the seventh butterfly valve 8.7 and the fifth butterfly valve 8.5. When a failure occurs in the extraction steam reheater 3, the second butterfly valve 8.2, the ball valve 7, the fourth butterfly valve 8.4 and the third butterfly valve 8.3 can be closed, and at the same time, the fifth butterfly valve 8.5 can be opened to open the multi-select high-temperature and high-pressure steam pipe 9, so that the high-temperature steam introduced into the multi-select high-temperature and high-pressure steam pipe 9 can be introduced into the ejector 2 as the primary fluid. Thus, the operation of the equipment is made more reliable.

[0026] In an embodiment of the present invention: The waste heat recovery device using the ejector 2 to automatically adjust the condenser back pressure provided by the present invention mainly realizes its function through the ejector 2. The inlet of its primary fluid is connected to the extraction steam reheater 3 or other multi-select high-temperature and high-pressure steam pipes 9 (such as: the extraction outlet of other steam turbines), and the secondary fluid inlet is connected to the exhaust port of the steam turbine 1.

[0027] The extraction steam reheater 3, its inlet is connected to the exhaust device of the steam turbine 1 through a pipeline, and a first butterfly valve 8.2 and an electric ball valve 7 are provided on the pipeline. Its outlet is connected to the inlet of the primary fluid on the ejector 2 through a pipeline through the third butterfly valve 8.3 and the seventh butterfly valve 8.7.

[0028] One end of the connection bypass 10 is connected to the connection pipeline between the third butterfly valve 8.3 and the extraction steam reheater 3, and the other end is connected to the multi-select high-temperature and high-pressure steam pipe 9 through the fourth butterfly valve 8.4 and the fifth butterfly valve 8.5.

[0029] The condenser 4 is divided into a hot side and a cold side. The hot side includes a hot side inlet and a condenser condensate hot side outlet 13. The cold side includes a condenser cold side inlet pipe 11 and a condenser cold side outlet pipe 12. The outside of the condenser cold side inlet pipe 11 is connected to the cooling circulating water return pipeline. The condenser cold side outlet pipe 12 is connected to the cooling circulating water outlet pipeline. The condenser cold side inlet pipe 11 is simultaneously connected to the condensate cooler cooling water return pipe 14 and the condensate cooler cooling water supply pipe 15, and the condensate cooler cooling water supply pipe 15 is arranged on the outside. The condenser 4 is the main device for waste heat recovery.

[0030] The condensate cooler 5 is also divided into a hot side and a cold side. The inlet of its hot side is connected to the outlet of the hot side of the condenser 4 through a pipeline. The outlet of the hot side is connected to the water inlet of the steam turbine 1 through a pipeline. The cold side water inlet is connected to the return pipe of the circulating water through the condensate cooler cooling water supply pipe 15. The cold side water outlet is connected to the return pipe of the circulating water through the condensate cooler cooling water return pipe 14. Electric butterfly valves are installed on all pipelines. It is another device for waste heat recovery, mainly used for waste heat recovery of condensate water in condensers with relatively high back pressure. Its main purpose is to eliminate condensation losses and can further improve the energy utilization rate.

[0031] The ejector 2 mentioned above is a steam ejector, which increases the back pressure in the condenser 4 by ejecting exhaust steam with high-temperature and high-pressure steam. On the one hand, it can increase the drainage temperature of the condensate water. On the other hand, it can achieve the purpose of flexibly adjusting the back pressure of the condenser 4 and reduce the thermoelectric coupling effect of the steam turbine 1. The exhaust steam reheater 3 generates high-temperature and high-pressure steam by heating the exhaust steam discharged from the steam turbine 1 for use as the primary fluid of the ejector 2, which is also the most economical scheme for obtaining the primary fluid in the present invention. Other alternative schemes for using high-temperature and high-pressure steam as the primary fluid of the ejector 2 are to prevent the exhaust steam reheater 3 from failing and causing the heating system to malfunction. The connection bypass 10 is a pipeline for the interconnection of different types of primary fluids of the ejector 2 and can be used as an emergency solution when different equipment is under maintenance or fails.

[0032] The back pressure in the condenser 4 is jointly determined by the ejector 2 and the exhaust device of the steam turbine 1, and the adjustment is more flexible. The back pressure in the condenser 4 is higher than the exhaust back pressure of the steam turbine 1, so that the outlet water temperature of the cooling water in the condenser 4 is higher. By selecting the vacuum pump, a part of the electric energy can be reduced and saved. The exhaust steam reheater 3 generates high-temperature and high-pressure steam by heating the exhaust steam, thus reducing the energy consumption of high-temperature and high-pressure steam. In addition, for the safe and stable operation of the system, the present invention provides alternative pipelines for supplying other high-temperature and high-pressure steam. The setting of the condensate cooler 5 can further reduce the temperature of the condensate water, recover waste heat to the greatest extent, eliminate cold-end losses, and make the energy utilization rate of the entire waste heat recovery device reach 100%.

[0033] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A waste heat recovery device that uses an ejector to self-regulate the back pressure of a condenser, characterized in that: It includes a steam turbine (1), an ejector (2), a waste steam reheater (3), a condenser (4) and a condensate cooler (5); the water inlet end of the steam turbine (1) is connected to the hot side outlet pipeline of the condensate cooler (5), and the exhaust device of the steam turbine (1) is respectively connected to the secondary fluid inlet end of the ejector (2) and the inlet pipeline of the waste steam reheater (3); the outlet end of the waste steam reheater (3) is connected to the primary fluid inlet pipe of the ejector (2); at the same time, the outlet pipeline of the ejector (2) is connected to the hot side inlet pipeline of the condenser (4); the circulating water return pipeline is connected to the cold side inlet of the condenser (4), and the cold side inlet and outlet of the condensate cooler (5) are connected to the circulating water return pipeline; the connection position of the cold side inlet connection pipeline of the condensate cooler (5) on the circulating water return pipeline is farther from the condenser (4) than the connection position of the condensate cooler outlet connection pipeline on the circulating water return pipeline to the condenser (4); the outer end of the condenser cold side inlet pipe (11) on the condenser (4) is connected to the cooling circulating water return pipeline, the condenser cold side outlet pipe (12) is connected to the outlet pipeline of the circulating water, and the condenser condensate hot side outlet (13) on the condenser (4) is connected to the hot side inlet pipeline of the condensate cooler (5) through a second gate valve (8.2) and an eighth butterfly valve (8.8); a connection bypass (10) is also connected to the pipeline between the third butterfly valve (8.3) and the waste steam reheater (3), and the connection bypass (10) is connected to a multi-select high-temperature and high-pressure steam pipe (9) through a fourth butterfly valve (8.4) and a fifth butterfly valve (8.5); the primary fluid inlet pipeline of the ejector (2) is connected to the multi-select high-temperature and high-pressure steam pipe (9) through a seventh butterfly valve (8.7) and a fifth butterfly valve (8.5).

2. The waste heat recovery device for self-regulating the back pressure of a condenser using an ejector according to claim 1, characterized in that: The condensate cooler (5) is used for the waste heat recovery of the condensate of the condenser with a relatively high back pressure.

3. The waste heat recovery device for self-regulating the back pressure of a condenser using an ejector according to claim 2, characterized in that: The ejector (2) is a steam ejector, which ejects waste steam through high-temperature and high-pressure steam, thereby increasing the back pressure in the condenser (4).

4. The waste heat recovery device for self-adjusting the back pressure of a condenser using an ejector according to claim 3, wherein: The waste steam reheater (3) heats the waste steam discharged from the steam turbine (1) to generate high-temperature and high-pressure steam, which is used as the primary fluid of the ejector (2) for the ejector (2).

5. The waste heat recovery device for self-regulating the back pressure of a condenser using an ejector according to claim 1, characterized in that: The water inlet end of the steam turbine (1) is connected to the hot side outlet pipeline of the condensate cooler (5) through a first butterfly valve (8.1). The exhaust device of the steam turbine (1) is connected to the secondary fluid inlet of the ejector (2) through a first gate valve (8.1) and a sixth butterfly valve (8.6). The water outlet end of the steam turbine (1) is connected to the inlet of the waste steam reheater (3) through a first gate valve (8.1), a second butterfly valve (8.2) and a ball valve (7). The outlet of the waste steam reheater (3) is connected to the inlet of the primary fluid of the ejector (2) through a third butterfly valve (8.3) and a seventh butterfly valve (8.7). At the same time, the outlet pipeline of the ejector (2) is connected to the hot side inlet pipeline of the condenser (4). The condensate cooler cooling water return pipe (14) on the condensate cooler (5) is also connected to the cold side inlet pipe (11) of the condenser through a third gate valve. The condensate cooler cooling water supply pipe on the condensate cooler (5) is also communicated with the cold side inlet pipe (11) of the condenser through a ninth butterfly valve (8.9).

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