A combined heat and power system based on ejector

Abstract

The present invention relates to the field of thermoelectric technology, and in particular to a heat and power cogeneration system based on an ejector, comprising: a boiler, a high-pressure cylinder of a steam turbine, an intermediate-pressure cylinder of a steam turbine, a low-pressure cylinder of a steam turbine, a condenser, a condensate pump, a deaerator and a feedwater pump connected in sequence; a power fluid inlet of the steam-steam ejector is connected to an exhaust steam outlet of the boiler, and an ejection fluid inlet is connected to an exhaust steam outlet of a low-pressure cylinder of the steam turbine; an ejection fluid inlet of a liquid-steam ejector is connected to an outlet of a steam-steam ejector, and a power fluid inlet is connected to a feedwater pump; a first heater is connected to an outlet of the steam-steam ejector; a second heater is connected to an outlet of a liquid-steam ejector, and a hot network water outlet of the first heater is connected to an hot network water inlet of a second heater; the present application improves the efficiency of heat and power cogeneration and avoids thermal pollution by utilizing the exhaust steam of the boiler to pass into the steam-steam ejector and reusing a low-grade heat source, thereby having significant energy-saving and environmental protection benefits; and the waste heat is utilized in a cascade manner to improve energy utilization efficiency.

Description

Technical Field

[0001] The invention relates to the field of thermoelectric technology, and in particular to an ejector-based cogeneration system. Background Art

[0002] Thermal power plants first convert the chemical energy of fuel into heat energy carried by steam, then convert the heat energy into mechanical energy of the turbine, and finally the generator converts the mechanical energy into electrical energy for users. During the operation of thermal power plants, a large amount of steam with a certain pressure is discharged into the air, including: low-grade steam generated during the operation of the deaerator and the boiler blowdown process. Thermal power plants also have a large amount of exhaust heat from low-pressure cylinders that is directly discharged into the environment through cooling towers, forming thermal pollution. The above-mentioned discharged steam is a low-grade heat source and is difficult to use directly. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defect that low-grade heat sources in thermal power plants are difficult to directly utilize, resulting in thermal pollution. Based on the above situation, it is necessary to develop a cogeneration system that can utilize low-grade heat sources in thermal power plants and avoid thermal pollution.

[0004] In order to achieve the above object, the present invention provides a cogeneration system based on an ejector, comprising:

[0005] A boiler, a steam turbine high-pressure cylinder, a steam turbine intermediate-pressure cylinder, a steam turbine low-pressure cylinder, a condenser, a condensate pump, a deaerator and a feedwater pump connected in sequence; the steam turbine high-pressure cylinder, the steam turbine intermediate-pressure cylinder and the steam turbine low-pressure cylinder are all coaxially connected to a generator;

[0006] The steam ejector, the power fluid inlet is connected to the exhaust steam outlet of the boiler through the second valve, and the ejection fluid inlet of the steam ejector is connected to the exhaust port of the low-pressure cylinder of the steam turbine;

[0007] A liquid-steam ejector, wherein the ejection fluid inlet is connected to the outlet of the steam-steam ejector, and the power fluid inlet of the liquid-steam ejector is connected to the feedwater pump;

[0008] A first heater connected to the outlet of the steam ejector, wherein the outlet fluid of the steam ejector is suitable for serving as a heat source for the first heater;

[0009] A second heater is connected to the outlet of the liquid-vapor ejector, wherein the outlet fluid of the liquid-vapor ejector is suitable for serving as a heat source for the second heater;

[0010] The hot water network outlet of the first heater is connected to the hot water network inlet of the second heater. The hot water network outlet of the first heater is suitable for connecting to domestic hot water users, and the hot water network outlet of the second heater is suitable for connecting to heating users.

[0011] Optionally, the exhaust steam outlet of the deaerator is connected to the power fluid inlet of the steam ejector through a fourth valve.

[0012] Optionally, the steam extraction port of the low-pressure cylinder of the steam turbine is connected to the power fluid inlet of the steam ejector through a third valve.

[0013] Optionally, a first valve is provided between the power fluid inlet of the liquid-steam ejector and the water feed pump; a fifth valve is provided between the heat source end inlet of the first heater and the outlet of the steam-steam ejector; a sixth valve is provided between the ejection fluid inlet of the liquid-steam ejector and the outlet of the steam-steam ejector; an eighth valve is provided between the hot network water outlet of the first heater and the hot network water inlet of the second heater; and a seventh valve is provided between the hot network water outlet of the first heater and the domestic hot water user.

[0014] Optionally, the first valve, the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve and the eighth valve are all valves with adjustable openings.

[0015] Optionally, the outlet steam of the high-pressure cylinder of the steam turbine is connected to the steam inlet of the intermediate-pressure cylinder of the steam turbine after being reheated by the boiler.

[0016] Optionally, it also includes:

[0017] A low-pressure heater group is connected between the condensate pump and the deaerator;

[0018] One end of the high-pressure heater group is connected to the feed water pump, and the other end of the high-pressure heater group is connected to the boiler.

[0019] Optionally, the power fluid inlet of the liquid-steam ejector is connected to the middle tap of the feed water pump.

[0020] Optionally, the drain ports of the first heater and the second heater are both connected to the condenser.

[0021] Optionally, the first heater is suitable for heating water in the heat circuit network to supply external domestic hot water heat load; the second heater is suitable for heating water in the heat circuit network that has been preliminarily heated by the first heater to supply external heating heat load.

[0022] The above technical solution of the present invention has the following advantages compared with the prior art:

[0023] 1. The heat and power cogeneration system based on the ejector provided by the present invention comprises: a boiler, a high-pressure cylinder of a steam turbine, an intermediate-pressure cylinder of a steam turbine, a low-pressure cylinder of a steam turbine, a condenser, a condensate pump, a deaerator and a feedwater pump connected in sequence; the high-pressure cylinder of the steam turbine, the intermediate-pressure cylinder of the steam turbine and the low-pressure cylinder of the steam turbine are all coaxially connected to a generator; a steam-steam ejector, wherein the power fluid inlet is connected to the exhaust steam outlet of the boiler through a second valve, and the ejection fluid inlet of the steam-steam ejector is connected to the exhaust port of the low-pressure cylinder of the steam turbine; a liquid-steam ejector, wherein the ejection fluid inlet is connected to the outlet of the steam-steam ejector, and the power fluid inlet of the liquid-steam ejector is connected to the feedwater pump; a first heater is connected to the outlet of the steam-steam ejector, and the outlet fluid of the steam-steam ejector is suitable for being used as a heat source for the first heater; a second heater is connected to the liquid-steam ejector. The outlet is connected, and the outlet fluid of the liquid-steam ejector is suitable for being used as a heat source for the second heater; the hot water network outlet of the first heater is connected to the hot water network inlet of the second heater, the hot water network outlet of the first heater is suitable for connecting to domestic hot water users, and the hot water network outlet of the second heater is suitable for connecting to heating users; the present application adopts the above-mentioned technical scheme, by utilizing the exhaust steam of a certain pressure generated in the boiler blowdown process to pass into the steam ejector and reuse the low-grade heat source, fully utilizing the low-grade residual pressure and waste heat in the operation of the thermal power plant, reducing the high-grade steam consumption in the heating process, improving the thermal efficiency of cogeneration, avoiding thermal pollution, and having significant energy-saving and environmental protection benefits; and utilizing the low-grade residual pressure and waste heat to perform step-by-step heating and utilization of the hot water network, thereby improving energy utilization efficiency.

[0024] 2. The exhaust steam outlet of the deaerator described in the present invention is connected to the power fluid inlet of the steam ejector through a fourth valve; the present application adopts the above technical scheme, when the pressure generated by the exhaust steam during boiler blowdown cannot meet the heating demand or the boiler is not in a blowdown state, the exhaust steam from the deaerator is supplemented into the steam ejector to reuse the low-grade heat source, fully utilize the low-grade residual pressure and waste heat during the operation of the thermal power plant, reduce the consumption of high-grade steam in the heating process, improve the thermal efficiency of cogeneration, avoid thermal pollution, and have significant energy-saving and environmental protection benefits.

[0025] 3. The steam extraction port of the low-pressure cylinder of the steam turbine described in the present invention is connected to the power fluid inlet of the steam ejector through a third valve; the present application adopts the above technical solution, when the exhaust steam pressure generated during the deaerator deoxygenation process cannot meet the heating demand, the steam is supplemented by the steam extraction port of the low-pressure cylinder of the steam turbine into the steam ejector.

[0026] 4. The present invention provides a first valve between the power fluid inlet of the liquid-steam ejector and the water feed pump; a fifth valve is provided between the heat source end inlet of the first heater and the outlet of the steam-steam ejector; a sixth valve is provided between the ejection fluid inlet of the liquid-steam ejector and the outlet of the steam-steam ejector; an eighth valve is provided between the hot network water outlet of the first heater and the hot network water inlet of the second heater; a seventh valve is provided between the hot network water outlet of the first heater and the domestic hot water heat user; the present application adopts the above technical scheme, and adjusts the water supply of the water feed pump to the liquid-steam ejector by the first valve; adjusts the steam supply of the steam-steam ejector to the first heater by the fifth valve; adjusts the steam supply of the steam-steam ejector to the liquid-steam ejector by the sixth valve; and adjusts the heat supply of the system to domestic hot water heat users and heating heat users by the seventh valve and the eighth valve.

[0027] 5. The first valve, the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve and the eighth valve of the present invention are all valves with adjustable openings; the present application adopts the above technical solution, and conveniently adjusts the flow and pressure parameters of heating or water supply through valves with adjustable openings.

[0028] 6. The outlet steam of the high-pressure cylinder of the steam turbine described in the present invention is connected to the steam inlet of the intermediate-pressure cylinder of the steam turbine after being reheated by the boiler; the present application adopts the above technical scheme, by reheating the steam at the steam outlet of the high-pressure cylinder of the steam turbine through the boiler, and then passing it into the steam inlet of the intermediate-pressure cylinder of the steam turbine, thereby increasing the steam temperature of the intermediate-pressure cylinder of the steam turbine and improving the working capacity of the intermediate-pressure cylinder of the steam turbine.

[0029] 7. The ejector-based cogeneration system provided by the present invention also includes: a low-pressure heater group, which is connected between the condensate pump and the deaerator; a high-pressure heater group, one end of which is connected to the feed water pump, and the other end of the high-pressure heater group is connected to the boiler; the present application adopts the above-mentioned technical scheme to heat the condensate return water through the low-pressure heater group and the high-pressure heater group, and circulate it to the boiler for reuse, thereby saving water resources, improving boiler efficiency and reducing costs.

[0030] 8. The drain ports of the first heater and the second heater of the present invention are both connected to the condenser; the present application adopts the above technical solution to recycle the drain to the condenser for reuse, thus saving water resources.

[0031] 9. The first heater of the present invention is suitable for heating water in the heat circuit network to supply external hot water heat load; the second heater is suitable for heating water in the heat circuit network that has been preliminarily heated by the first heater to supply external heating heat load; the present application adopts the above technical solution to heat the heat network water in stages through the first heater and the second heater to improve energy utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 Schematic diagram of the connection structure of the ejector-based cogeneration system provided in an embodiment of the present invention.

[0034] Description of reference numerals:

[0035] 1. Boiler; 2. High-pressure cylinder of steam turbine; 3. Medium-pressure cylinder of steam turbine; 4. First valve; 5. Second valve; 6. Low-pressure cylinder of steam turbine; 7. Condenser; 8. Condensate pump; 9. Low-pressure heater group; 10. Deaerator; 11. Feedwater pump; 12. High-pressure heater group; 13. Third valve; 14. Steam-steam ejector; 15. Liquid-steam ejector; 16. Fourth valve; 17. First heater; 18. Second heater; 19. Fifth valve; 20. Sixth valve; 21. Seventh valve; 22. Eighth valve. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0038] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] like Figure 1 A specific embodiment of the ejector-based cogeneration system shown includes: a boiler 1, a turbine high-pressure cylinder 2, a turbine intermediate-pressure cylinder 3, a turbine low-pressure cylinder 6, a condenser 7, a condensate pump 8, a low-pressure heater group 9, a deaerator 10, a feed water pump 11 and a high-pressure heater group 12 connected in sequence, a steam-steam ejector 14, a liquid-steam ejector 15 and a second heater 18 connected in sequence, and a first heater 17 connected to the steam-steam ejector 14, etc.

[0041] The steam turbine high pressure cylinder 2, the steam turbine intermediate pressure cylinder 3 and the steam turbine low pressure cylinder 6 are all coaxially connected to a generator; the outlet steam of the steam turbine high pressure cylinder 2 is reheated by the boiler 1 and communicated with the steam inlet of the steam turbine intermediate pressure cylinder 3. The high pressure heater group 12 is connected to the boiler 1; specifically, the high pressure heater group 12 is a plurality of high pressure heaters connected in series; the low pressure heater group 9 is a plurality of low pressure heaters connected in series. The power fluid inlet of the steam ejector 14 is connected to the exhaust steam outlet of the boiler 1 through the second valve 5, and the ejection fluid inlet of the steam ejector 14 is connected to the exhaust port of the low-pressure cylinder 6 of the steam turbine; the ejection fluid inlet of the liquid-steam ejector 15 is connected to the outlet of the steam-steam ejector 14 through the sixth valve 20, and the power fluid inlet of the liquid-steam ejector 15 is connected to the middle tap of the feed water pump 11 through the first valve 4; the first heater 17 is connected to the outlet of the steam-steam ejector 14 through the fifth valve 19, and the outlet fluid of the steam-steam ejector 14 is suitable for being used as the heat source of the first heater 17. The hot network water outlet of the first heater 17 is connected to the hot network water inlet of the second heater 18 through the eighth valve 22, and the hot network water outlet of the first heater 17 is connected to the domestic hot water heat user through the seventh valve 21. The second heater 18 is connected to the outlet of the liquid-steam ejector 15, and the outlet fluid of the liquid-steam ejector 15 is suitable for being used as the heat source of the second heater 18; the hot network water outlet of the second heater 18 is suitable for being connected to the heating heat user. Further, the drain ports of the first heater 17 and the second heater 18 are both connected to the condenser 7. The exhaust steam outlet of the deaerator 10 is connected to the power fluid inlet of the steam ejector 14 through the fourth valve 16. The steam extraction port of the low-pressure cylinder 6 of the steam turbine is connected to the power fluid inlet of the steam ejector 14 through the third valve 13. Specifically, the first valve 4, the second valve 5, the third valve 13, the fourth valve 16, the fifth valve 19, the sixth valve 20, the seventh valve 21 and the eighth valve 22 are all valves with adjustable openings.

[0042] The working process of the exhaust steam of the cogeneration system based on the ejector described in the present application is briefly described as follows: when the boiler 1 is discharging wastewater, the second valve 5 is opened to generate exhaust steam of a certain pressure, which enters the steam ejector 14 and ejects the exhaust steam of the low-pressure cylinder 6 of the steam turbine; high-temperature steam is generated and enters the first heater 17 to release heat for heating; the outlet fluid of the steam ejector 14 is simultaneously passed into the liquid-steam ejector 15, and the high-pressure water from the middle tap of the feedwater pump 11 ejects the outlet steam of the steam ejector 14 in the liquid-steam ejector 15, and generates high-temperature water and enters the second heater 18 to release heat for heating. At the same time, the hot network water preliminarily heated by the first heater 17 is passed into the second heater 18 to release heat for heating. Specifically, the first heater 17 is suitable for heating the water in the hot circuit pipe network to supply the domestic hot water heat load to the outside; the second heater 18 is suitable for heating the water in the hot circuit pipe network preliminarily heated by the first heater 17 to supply the heating heat load to the outside.

[0043] When the exhaust steam pressure generated by the boiler 1 blowing down cannot meet the heating demand or the boiler 1 is not in the blowing down state, the fourth valve 16 is opened, and the exhaust steam of a certain pressure generated by the deaerator 10 during the deoxidation process is supplemented into the steam ejector 14 to eject the exhaust steam of the low-pressure cylinder 6 of the steam turbine, and the outlet fluid is passed into the liquid-steam ejector 15 and the first heater 17, and the high-pressure water from the middle tap of the feed water pump 11 ejects the outlet steam of the steam ejector 14 in the liquid-steam ejector 15, and generates high-temperature water that enters the second heater 18, and the hot network water preliminarily heated by the first heater 17 is passed into the second heater 18 to release heat for heating. When the exhaust steam pressure generated by the deaerator 10 during the deoxidation process cannot meet the heat supply, the third valve 13 is opened, and the extraction steam of the low-pressure cylinder 6 of the steam turbine is supplemented into the steam ejector 14, and the exhaust steam of the low-pressure cylinder 6 of the steam turbine is ejected, and the outlet fluid is passed into the liquid-steam ejector 15 and the first heater 17. The high-pressure water from the middle tap of the feed water pump 11 ejects the outlet steam of the steam ejector 14 in the liquid-steam ejector 15, and generates high-temperature water to enter the second heater 18, and the hot network water preliminarily heated by the first heater 17 is passed into the second heater 18 to release heat for heating. By changing the opening of the first valve 4, the second valve 5, the third valve 13, the fourth valve 16, the fifth valve 19, the sixth valve 20, the seventh valve 21 and the eighth valve 22, the flow and pressure parameters of heating or water supply can be adjusted.

[0044] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A cogeneration system based on an ejector, characterized in that: include: A boiler (1), a steam turbine high-pressure cylinder (2), a steam turbine intermediate-pressure cylinder (3), a steam turbine low-pressure cylinder (6), a condenser (7), a condensate pump (8), a deaerator (10) and a feedwater pump (11) connected in sequence; the steam turbine high-pressure cylinder (2), the steam turbine intermediate-pressure cylinder (3) and the steam turbine low-pressure cylinder (6) are all coaxially connected to a generator; A steam ejector (14), wherein the power fluid inlet is connected to the exhaust steam outlet of the boiler (1) through a second valve (5), and the ejection fluid inlet of the steam ejector (14) is connected to the exhaust steam outlet of the low-pressure cylinder (6) of the steam turbine; A liquid-steam ejector (15), wherein an ejection fluid inlet is connected to an outlet of the steam-steam ejector (14), and a power fluid inlet of the liquid-steam ejector (15) is connected to a feed water pump (11); a first heater (17) connected to the outlet of the steam ejector (14), wherein the outlet fluid of the steam ejector (14) is suitable for serving as a heat source for the first heater (17); a second heater (18) connected to the outlet of the liquid vapor ejector (15), wherein the outlet fluid of the liquid vapor ejector (15) is suitable for serving as a heat source for the second heater (18); The hot water network outlet of the first heater (17) is connected to the hot water network inlet of the second heater (18), the hot water network outlet of the first heater (17) is suitable for connecting to domestic hot water users, and the hot water network outlet of the second heater (18) is suitable for connecting to heating users; The exhaust steam outlet of the deaerator (10) is connected to the power fluid inlet of the steam ejector (14) via a fourth valve (16); The steam extraction port of the low-pressure cylinder (6) of the steam turbine is connected to the power fluid inlet of the steam ejector (14) through a third valve (13); A first valve (4) is provided between the power fluid inlet of the liquid-steam ejector (15) and the water supply pump (11); a fifth valve (19) is provided between the heat source end inlet of the first heater (17) and the outlet of the steam ejector (14); a sixth valve (20) is provided between the ejection fluid inlet of the liquid-steam ejector (15) and the outlet of the steam ejector (14); an eighth valve (22) is provided between the hot water network outlet of the first heater (17) and the hot water network inlet of the second heater (18); and a seventh valve (21) is provided between the hot water network outlet of the first heater (17) and a domestic hot water user.

2. The ejector-based cogeneration system according to claim 1, characterized in that: The first valve (4), the second valve (5), the third valve (13), the fourth valve (16), the fifth valve (19), the sixth valve (20), the seventh valve (21) and the eighth valve (22) are all valves with adjustable openings.

3. The ejector-based cogeneration system according to claim 1 or 2, characterized in that: The outlet steam of the steam turbine high-pressure cylinder (2) is reheated by the boiler (1) and then communicated with the steam inlet of the steam turbine intermediate-pressure cylinder (3).

4. The ejector-based cogeneration system according to claim 1 or 2, characterized in that: Also includes: A low-pressure heater group (9) is connected between the condensate pump (8) and the deaerator (10); One end of the high-pressure heater group (12) is connected to the feed water pump (11), and the other end of the high-pressure heater group (12) is connected to the boiler (1).

5. The ejector-based cogeneration system according to claim 1 or 2, characterized in that: The power fluid inlet of the liquid-steam ejector (15) is connected to the middle tap of the water feed pump (11).

6. The ejector-based cogeneration system according to claim 1 or 2, characterized in that: The drain ports of the first heater (17) and the second heater (18) are both connected to the condenser (7).

7. The ejector-based cogeneration system according to claim 1 or 2, characterized in that: The first heater (17) is suitable for heating water in the heat circuit pipe network to supply external domestic hot water heat load; the second heater (18) is suitable for heating water in the heat circuit pipe network that has been preliminarily heated by the first heater (17) to supply external heating heat load.

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