Combined heat and power generation system and scheduling method

Abstract

The invention relates to a combined heat and power generation system which comprises a boiler, a generator set, a fused salt heat storage subsystem and a steam heat storage subsystem. The generator set comprises a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder; the fused salt heat storage subsystem comprises a cold salt tank, a hot salt tank, a heat storage heat exchanger and a heat supply heat exchanger, the heat storage heat exchanger is provided with a first low-temperature medium flow channel and a first high-temperature medium flow channel, and the heat supply heat exchanger is provided with a second low-temperature medium flow channel and a second high-temperature medium flow channel; the first high-temperature medium flow channel is connected with the steam extraction end of the medium-pressure cylinder; one end of the second low-temperature medium runner is connected with the water supply end, and the other end is connected with a heat user; the steam heat storage subsystem comprises a steam heat storage tank, the input end of the steam heat storage tank is connected with the steam extraction end of the medium-pressure cylinder, the output end of the steam heat storage tank is connected with the steam inlet end of the low-pressure cylinder, and the system has the advantages that different dispatching requirements can be met, and the dispatching flexibility is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation systems, and in particular to a cogeneration system and a scheduling method. Background Art

[0002] The cogeneration unit not only supplies electricity to electricity users, but also heats heat to heat users. While the cogeneration unit needs to stably supply heat to heat users, the power grid has put forward requirements for the cogeneration unit to participate in peak load and frequency regulation.

[0003] However, the electrical load operating range of existing cogeneration units is affected by the thermal load, and the units' ability to participate in frequency regulation is limited, resulting in the cogeneration units' operation being unable to meet actual scheduling needs and having low flexibility.

[0004] Therefore, it is urgent for technical personnel in this field to provide a cogeneration system and scheduling method to expand the operating range of the electric and thermal loads of the generator set, improve the ability of the generator set to participate in peak regulation, and at the same time increase the load increase and decrease rate of the unit and increase the flexibility of the system. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects in the prior art, thereby providing a cogeneration system and a scheduling method.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A cogeneration system, comprising a boiler, a generator set, a molten salt heat storage subsystem and a steam heat storage subsystem; the boiler is used to provide hot steam to the generator set; the generator set comprises a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder, the steam extraction end of the medium-pressure cylinder is connected to a heat user through a first pipeline assembly; the molten salt heat storage subsystem comprises a cold salt tank, a hot salt tank, a heat storage heat exchanger and a heat supply heat exchanger, the heat storage heat exchanger has a first low-temperature medium flow channel and a first high-temperature medium flow channel, the heat supply heat exchanger has a second low-temperature medium flow channel The cold salt tank, the first low-temperature medium flow channel, the hot salt tank, the second high-temperature medium flow channel, and the cold salt tank are connected in sequence to form a molten salt loop; the first high-temperature medium flow channel is connected to the steam extraction end of the intermediate-pressure cylinder; one end of the second low-temperature medium flow channel is connected to the water supply end, and the other end is connected to the heat user; the steam heat storage subsystem includes a steam heat storage tank, the input end of the steam heat storage tank is connected to the steam extraction end of the intermediate-pressure cylinder, and the output end is connected to the steam inlet end of the low-pressure cylinder.

[0008] Preferably, it also includes a steam condensation reflux subsystem, and the boiler, the generator set and the steam condensation reflux subsystem are connected in sequence to form a circulation loop; in the flow direction from the exhaust end of the low-pressure cylinder to the boiler, the steam condensation reflux subsystem includes a condenser, a condensate pump, a deaerator and a first feed water pump connected in sequence by pipelines.

[0009] Preferably, the steam extraction end of the intermediate pressure cylinder is connected to the input end of the deaerator.

[0010] Preferably, the output end of the first high-temperature medium flow channel is connected to the input end of the deaerator; and the input end of the second low-temperature medium flow channel is connected to the output end of the deaerator.

[0011] Preferably, the input end of the second low-temperature medium flow channel is connected to the output end of the deaerator through a second pipeline assembly; the second pipeline assembly includes a second control valve and a second water supply pump connected by a pipeline.

[0012] Preferably, the first pipeline assembly includes a first steam delivery pipe and a first control valve installed on the first steam delivery pipe.

[0013] Preferably, the steam thermal storage subsystem further includes a third control valve and a fourth control valve, and the third control valve and the fourth control valve are respectively arranged upstream and downstream of the steam thermal storage tank.

[0014] A scheduling method applicable to the above-mentioned cogeneration system comprises the following steps: when the generator set needs to reduce the load, the steam extraction from the intermediate pressure cylinder is stored in a steam heat storage tank, and / or, the heat of the steam extraction from the intermediate pressure cylinder is stored in a molten salt heat storage subsystem; when the generator set needs to increase the load, the steam stored in the steam heat storage tank is transported to the low pressure cylinder; when the generator set needs to expand the electric load operation range, the molten salt flowing in the high temperature medium flow channel of the heat supply heat exchanger is controlled to exchange heat with the saturated water flowing in the low temperature medium flow channel of the heat supply heat exchanger to form hot steam, and the hot steam replaces part or all of the steam extraction from the intermediate pressure cylinder to supply heat users.

[0015] Preferably, the method further includes the following steps: delivering saturated water output from the output end of the deaerator of the condensation reflux subsystem to the heat supply heat exchanger; and delivering the high-temperature medium flow channel of the heat storage heat exchanger to the deaerator of the condensation water flow subsystem through the heat exchange medium.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] A cogeneration system provided by the present invention can not only quickly adjust the amount of steam in the medium-pressure cylinder through the cooperation between the steam heat storage tank and the molten salt heat storage subsystem, but also adjust the amount of steam supplied to the low-pressure cylinder, thereby increasing the load change rate of the generator set by adjusting the amount of steam entering the generator set to do work, thereby improving the ability of the generator set to participate in frequency regulation. In addition, the setting of the molten salt heat storage subsystem can achieve complete decoupling of heat and electricity, expand the operating range of the electric and thermal load of the generator set, and improve the ability of the generator set to participate in peak regulation. Through the cooperation between the molten salt heat storage subsystem and the steam heat storage subsystem, different scheduling requirements of the generator set can be met, and the flexibility of the operation of the cogeneration system is increased. Correspondingly, the scheduling method based on the cogeneration system can meet different scheduling requirements and increase the flexibility of scheduling. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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.

[0019] Figure 1 This is a connection diagram of one example of this system.

[0020] Description of reference numerals:

[0021] 1. Boiler; 11. Main steam pipe; 12. Reheat steam pipe; 21. High-pressure cylinder; 22. Medium-pressure cylinder; 23. Low-pressure cylinder; 31. Cold salt tank; 311. Fifth control valve; 32. Hot salt tank; 321. Sixth control valve; 33. Heat storage heat exchanger; 330. Seventh control valve; 331. First low-temperature medium flow channel; 332. First high-temperature medium flow channel; 34. Heat supply heat exchanger; 341. Second low-temperature medium flow channel; 342. Second high-temperature medium flow channel; 41. Steam heat storage tank; 42. Third control valve; 43. Fourth control valve; 51. Condenser; 52. Condensate pump; 53. Deaerator; 54. First feed water pump; 61. First steam delivery pipe; 62. First control valve; 71. Second control valve; 72. Second feed water pump. DETAILED DESCRIPTION

[0022] 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.

[0023] 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.

[0024] 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.

[0025] See also Figure 1 An embodiment of the present invention provides a cogeneration system, including a boiler 1, a generator set, a molten salt heat storage subsystem and a steam heat storage subsystem; wherein the boiler 1 is used to provide hot steam to the generator set so that the generator set can generate electricity.

[0026] Specifically, the generator set includes a high-pressure cylinder 21, an intermediate-pressure cylinder 22 and a low-pressure cylinder 23. The extraction end of the intermediate-pressure cylinder 22 is connected to the heat user through the first pipeline assembly; the extraction steam of the intermediate-pressure cylinder 22 is then supplied to the heat user to meet the needs of the heat user. It can be known that the boiler 1 has a main steam pipe 11 and a reheat steam pipe 12. The output end of the main steam pipe 11 is connected to the high-pressure cylinder 21, and the exhaust end of the high-pressure cylinder 21 is connected to the input end of the reheat steam pipe 12. The output end of the reheat steam pipe 12 is connected to the steam output end of the intermediate-pressure cylinder 22, and the exhaust end of the intermediate-pressure cylinder 22 is also connected to the steam input end of the low-pressure cylinder 23.

[0027] Further, the molten salt heat storage subsystem includes a cold salt tank 31, a hot salt tank 32, a heat storage heat exchanger 33 and a heat supply heat exchanger 34. The heat storage heat exchanger 33 has a first low-temperature medium flow channel 331 and a first high-temperature medium flow channel 332, and the heat supply heat exchanger 34 has a second low-temperature medium flow channel 341 and a second high-temperature medium flow channel 342; the cold salt tank 31, the first low-temperature medium flow channel 331, the hot salt tank 32, the second high-temperature medium flow channel 342, and the cold salt tank 31 are connected in sequence to form a molten salt loop; the first high-temperature medium flow channel 332 is connected to the steam extraction end of the medium-pressure cylinder 22; one end of the second low-temperature medium flow channel 341 is connected to the water supply end, and the other end is connected to the heat user. The setting of the molten salt heat storage subsystem can store the heat in the steam extraction of the medium pressure cylinder 22 in the molten salt when the unit load is small, and can also release the heat stored in the molten salt when the unit load is large, and use it to heat the water to form hot steam, so that the generated hot steam replaces part or all of the steam extraction of the medium pressure cylinder 22 to supply the heat user, reduce the steam extraction of the medium pressure cylinder 22, and meet the high load demand of the generator set. It can be known that the output end of the cold salt tank 31 is provided with a fifth control valve 311, and the output end of the hot salt tank 32 is provided with a sixth control valve 321, which can control the circulation or interruption of the molten salt circuit. The input end of the first high-temperature medium flow channel 332 can also be provided with a corresponding seventh control valve 330.

[0028] Furthermore, the steam heat storage subsystem includes a steam heat storage tank 41, the input end of the steam heat storage tank 41 is connected to the steam extraction end of the intermediate pressure cylinder 22, and the output end is connected to the steam inlet end of the low pressure cylinder 23. The arrangement of the steam heat storage tank 41 can utilize the steam heat storage tank 41 to store the extraction steam of the intermediate pressure cylinder 22 when the generator set needs to quickly reduce the load, and when the generator set needs to quickly increase the load, the steam stored in the steam heat storage tank 41 is transported to the low pressure cylinder 23.

[0029] Through the above scheme, the steam heat storage tank 41 and the molten salt heat storage subsystem can cooperate with each other to quickly adjust the amount of steam in the medium-pressure cylinder 22, and at the same time, adjust the amount of steam supplied to the low-pressure cylinder 23, and then adjust the amount of steam entering the generator set to do work to increase the load change rate of the generator set, thereby improving the ability of the generator set to participate in frequency regulation. In addition, the setting of the molten salt heat storage subsystem can achieve complete decoupling of heat and electricity, expand the operating range of the electric and thermal load of the generator set, and improve the ability of the generator set to participate in peak regulation. Through the cooperation of the molten salt heat storage subsystem and the steam heat storage subsystem, different scheduling requirements of the generator set can be met, and the flexibility of the operation of the cogeneration system is increased.

[0030] See also Figure 1In this embodiment, the cogeneration system also includes a steam condensation reflux subsystem, and the boiler 1, the generator set and the steam condensation reflux subsystem are connected in sequence to form a circulation loop, so that the exhaust steam after the generator set does work can be condensed into condensate, and then flow back to the boiler 1 to generate steam to supply the generator set.

[0031] Specifically, in the flow direction from the low-pressure cylinder 23 to the boiler 1, the steam condensation reflux subsystem includes a condenser 51, a condensate pump 52, a deaerator 53 and a first feed water pump 54 which are sequentially connected by pipelines.

[0032] Specifically, the steam extraction end of the intermediate pressure cylinder 22 is connected to the input end of the deaerator 53 .

[0033] Furthermore, the output end of the first high-temperature medium flow channel 332 is connected to the input end of the deaerator 53, so that the water liquid condensed after heat exchange in the heat storage heat exchanger 33 can be transported to the deaerator 53 and supplied to the boiler 1 together with the water liquid transported to the deaerator 53 from the low-pressure cylinder 23.

[0034] Furthermore, the input end of the second low-temperature medium flow channel 341 is connected to the output end of the deaerator 53, so that the water liquid in the deaerator 53 can be supplied to the second low-temperature medium flow channel 341, and then exchange heat with the high-temperature molten salt in the second high-temperature medium flow channel 342, so as to heat the water liquid flowing through the second low-temperature medium flow channel 341 into hot steam and then supply it to heat users.

[0035] See also Figure 1 The input end of the second low-temperature medium flow channel 341 is connected to the output end of the deaerator 53 through a second pipeline assembly; the second pipeline assembly includes a second control valve 71 and a second water supply pump 72 connected by a pipeline.

[0036] See also Figure 1 The first pipeline assembly includes a first steam delivery pipe 61 and a first control valve 62 installed on the first steam delivery pipe 61 .

[0037] See also Figure 1 The steam heat storage subsystem further includes a third control valve 42 and a fourth control valve 43 , and the third control valve 42 and the fourth control valve 43 are respectively arranged upstream and downstream of the steam heat storage tank 41 .

[0038] Based on the above system, its actual working principle is as follows:

[0039] When the unit receives the frequency modulation instruction, due to the high steam flow rate in the system, changing the amount of steam entering the generator set to do work will quickly affect the electrical load output by the generator of the generator set. Specifically, when it is necessary to quickly reduce the load, a portion of the steam extraction of the intermediate pressure cylinder 22 is stored in the steam heat storage tank 41. At this time, due to the reduction in the amount of steam entering the low pressure cylinder 23 to do work, the output power of the generator set drops rapidly. At the same time, a portion of the steam extraction of the intermediate pressure cylinder 22 can also be transported to the heat storage heat exchanger 33 to exchange heat with the molten salt input into the heat storage heat exchanger 33 in the cold salt tank 31, and the high-temperature molten salt after heat exchange is stored in the hot salt tank 32, and the steam after heat exchange (or steam with condensate is transported to the deaerator 53). When it is necessary to quickly increase the load, the hot steam stored in the steam heat storage tank 41 is quickly released and transported to the low pressure cylinder 23 to do work, thereby rapidly increasing the output power of the unit.

[0040] When the unit receives a peak load instruction, since the unit's electrical load regulation range is affected by the amount of heat supplied to heat users, it is necessary to use the molten salt heat storage subsystem to supply heat to heat users, thereby achieving thermal-electric decoupling and expanding the unit's electrical load regulation range. Specifically, when the unit's electrical load is at an intermediate load, the molten salt heat storage subsystem stores heat, that is, part of the steam extraction from the intermediate pressure cylinder 22 is transported to the heat storage heat exchanger 33, and heat is exchanged with the molten salt input into the heat storage heat exchanger 33 from the cold salt tank 31, and the high-temperature molten salt that has undergone heat exchange is stored in the hot salt tank 32. When the unit receives a peak load instruction and needs to expand the electrical load operation range, the first control valve 62 is completely closed at this time. ， The steam used by heat users is completely provided by the steam generated by the molten salt heat storage subsystem, thus achieving complete decoupling of heat and electricity of the unit

[0041] Through the above-mentioned adjustment process, the heat supply to heat users remains stable, and the electric heat load operating range and load increase and decrease rate of the cogeneration unit are greatly improved, thereby improving the flexibility of the cogeneration unit operation.

[0042] The embodiment of the present invention further provides a scheduling method applicable to the above cogeneration system, comprising the following steps:

[0043] When the generator set needs to reduce its load, the steam heat storage tank 41 is used to store the extracted steam from the intermediate pressure cylinder 22, and the molten salt heat storage subsystem is used to store the heat of the extracted steam from the intermediate pressure cylinder 22.

[0044] When the generator set needs to increase its load, the steam stored in the steam heat storage tank 41 is delivered to the low-pressure cylinder 23 .

[0045] When the generator set needs to expand the electric load operating range, the molten salt flowing in the high-temperature medium flow channel of the heat supply heat exchanger 34 is controlled to exchange heat with the saturated water flowing in the low-temperature medium flow channel of the heat supply heat exchanger 34 to form hot steam, and the hot steam replaces part or all of the steam extracted from the intermediate pressure cylinder 22 to supply heat users.

[0046] Furthermore, the following steps are also included:

[0047] The saturated water outputted from the output end of the deaerator 53 of the condensation reflux subsystem is transported to the heat supply heat exchanger 34;

[0048] The high-temperature medium flow channel of the heat storage heat exchanger 33 is transported to the deaerator 53 of the condensed water flow subsystem through the heat exchange medium.

[0049] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A cogeneration system, characterized in that , including boiler, generator set, molten salt heat storage subsystem and steam heat storage subsystem; The boiler is used to provide hot steam to the generator set; The generator set comprises a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder, and the steam extraction end of the medium-pressure cylinder is connected to the heat user through a first pipeline assembly; The molten salt heat storage subsystem comprises a cold salt tank, a hot salt tank, a heat storage heat exchanger and a heat supply heat exchanger, wherein the heat storage heat exchanger has a first low-temperature medium flow channel and a first high-temperature medium flow channel, and the heat supply heat exchanger has a second low-temperature medium flow channel and a second high-temperature medium flow channel; The cold salt tank, the first low-temperature medium flow channel, the hot salt tank, the second high-temperature medium flow channel, and the cold salt tank are connected in sequence to form a molten salt circuit; The first high-temperature medium flow channel is connected to the steam extraction end of the intermediate pressure cylinder; one end of the second low-temperature medium flow channel is connected to the water supply end, and the other end is connected to the heat user; The steam heat storage subsystem comprises a steam heat storage tank, an input end of the steam heat storage tank is connected to the steam extraction end of the intermediate pressure cylinder, and an output end of the steam heat storage tank is connected to the steam inlet end of the low pressure cylinder.

2. A cogeneration system according to claim 1, characterized in that: It also includes a steam condensation reflux subsystem, wherein the boiler, the generator set and the steam condensation reflux subsystem are sequentially connected to form a circulation loop; In the flow direction from the exhaust end of the low-pressure cylinder to the boiler, the steam condensation reflux subsystem includes a condenser, a condensate pump, a deaerator and a first feed water pump which are sequentially connected by pipelines.

3. A cogeneration system according to claim 2, characterized in that: The steam extraction end of the medium pressure cylinder is connected to the input end of the deaerator.

4. A cogeneration system according to claim 2, characterized in that: The output end of the first high-temperature medium flow channel is connected to the input end of the deaerator; The input end of the second low-temperature medium flow channel is connected to the output end of the deaerator.

5. A cogeneration system according to claim 4, characterized in that: The input end of the second low-temperature medium flow channel is connected to the output end of the deaerator through a second pipeline assembly; The second pipeline assembly includes a second control valve and a second water supply pump connected by a pipeline.

6. A cogeneration system according to claim 1, characterized in that: The first pipeline assembly includes a first steam delivery pipe and a first control valve installed on the first steam delivery pipe.

7. A cogeneration system according to claim 1, characterized in that: The steam thermal storage subsystem further includes a third control valve and a fourth control valve, and the third control valve and the fourth control valve are respectively arranged upstream and downstream of the steam thermal storage tank.

8. A scheduling method applicable to the cogeneration system according to any one of claims 1 to 7, characterized in that: The following steps are included: When the generator set needs to reduce load, the steam extraction from the intermediate pressure cylinder is stored in a steam heat storage tank, and / or the molten salt heat storage subsystem is used to store the heat of the steam extraction from the intermediate pressure cylinder; When the generator set needs to increase its load, the steam stored in the steam heat storage tank is transported to the low-pressure cylinder; When the generator set needs to expand the electric load operating range, the molten salt flowing in the high-temperature medium flow channel of the heat supply heat exchanger is controlled to exchange heat with the saturated water flowing in the low-temperature medium flow channel of the heat supply heat exchanger to form hot steam, which replaces part or all of the intermediate pressure cylinder extraction steam to supply heat users.

9. The scheduling method according to claim 1, characterized in that: The following steps are also included: delivering saturated water outputted from the output end of the deaerator of the condensation reflux subsystem to the heat supply heat exchanger; The high-temperature medium flow channel of the heat storage heat exchanger is transported to the deaerator of the condensate flow subsystem through the heat exchange medium.

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