A cogeneration system and dispatching method

Abstract

The application relates to a combined heat and power system, which comprises a boiler, a generator unit, a molten salt heat storage subsystem and a steam heat storage subsystem; the generator unit comprises a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder; 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 is provided with a first low-temperature medium flow channel and a first high-temperature medium flow channel, 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 a steam extraction end of the medium-pressure cylinder; one end of the second low-temperature medium flow channel is connected with a water supply end, and the other end is connected with a heat user; the steam heat storage subsystem comprises a steam heat storage tank, an input end of the steam heat storage tank is connected with the steam extraction end of the medium-pressure cylinder, an output end is connected with a steam inlet end of the low-pressure cylinder, and the steam heat storage tank has the advantages of being able to meet different scheduling requirements and increasing the flexibility of scheduling.

Description

TECHNICAL FIELD

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

[0002] The cogeneration unit supplies power to the electric user and heat to the heat user. The cogeneration unit needs to stably supply heat to the heat user, and the power grid requires the cogeneration unit to participate in peak regulation and frequency modulation.

[0003] However, the existing cogeneration unit has its electric load operation interval affected by the heat load, and the unit has limited frequency modulation capacity, resulting in that the operation of the cogeneration unit cannot meet the actual scheduling demand and has low flexibility.

[0004] Therefore, it is urgent for those skilled in the art to provide a cogeneration system and a scheduling method to expand the electric and heat load operation interval of the generator unit, improve the capacity of the generator unit to participate in peak regulation, and at the same time improve the load raising and lowering rate of the unit and increase the flexibility of the system. SUMMARY

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

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0007] A cogeneration system, comprising a boiler, a generator unit, a molten salt heat storage subsystem and a steam heat storage subsystem; the boiler is used to provide hot steam to the generator unit; the generator unit comprises a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder, and the extraction end of the medium-pressure cylinder is connected with a heat user through a first pipe 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, 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 sequentially connected to form a molten salt loop; the first high-temperature medium flow channel is connected with the extraction end of the medium-pressure cylinder; one end of the second low-temperature medium flow channel is connected with a water supply end, and the other end is connected with the heat user; the steam heat storage subsystem comprises a steam heat storage tank, and the input end of the steam heat storage tank is connected with the extraction end of the medium-pressure cylinder, and the output end is connected with the steam inlet end of the low-pressure cylinder.

[0008] Preferably, the system further comprises a steam condensing and returning subsystem, the boiler, the generator set and the steam condensing and returning subsystem are connected in sequence to form a circulating loop; from the exhaust end of the low-pressure cylinder to the boiler, the steam condensing and returning subsystem comprises a condenser, a condensate pump, a deaerator and a first feed water pump connected in sequence by pipelines.

[0009] Preferably, the 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; 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 comprises a second control valve and a second feed water pump connected by pipelines.

[0012] Preferably, the first pipeline assembly comprises a first steam conveying pipeline and a first control valve installed on the first steam conveying pipeline.

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

[0014] A dispatching method suitable for the above-mentioned combined heat and power system, comprising the following steps: when the generator set needs to reduce load, the extraction steam of the intermediate-pressure cylinder is stored by the steam heat storage tank and / or the heat of the extraction steam of the intermediate-pressure cylinder is stored by the molten salt heat storage subsystem; when the generator set needs to increase load, the steam stored in the steam heat storage tank is conveyed 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 and the saturated water flowing in the low-temperature medium flow channel of the heat supply heat exchanger are controlled to exchange heat to form hot steam, and the hot steam replaces part or all of the intermediate-pressure cylinder extraction steam to supply the heat user.

[0015] Preferably, the method further comprises the following steps: conveying the saturated water output from the output end of the deaerator of the condensing and returning subsystem to the heat supply heat exchanger; conveying the medium exchanged in the high-temperature medium flow channel of the heat storage heat exchanger to the deaerator of the condensing water flow subsystem.

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

[0017] The heat and power cogeneration system can quickly adjust the steam quantity in the medium-pressure cylinder by cooperation of the steam storage tank and the molten salt storage subsystem, simultaneously adjust the steam quantity supplied to the low-pressure cylinder, and further adjust the steam quantity entering the generator set to improve the variable load rate of the generator set, thereby improving the frequency modulation capability of the generator set. In addition, the molten salt storage subsystem can realize complete decoupling of heat and power, expand the electrical and thermal load operation range of the generator set, and improve the peak regulation capability of the generator set. The molten salt storage subsystem and the steam storage subsystem can cooperate with each other to meet different scheduling requirements of the generator set, thereby increasing the flexibility of the heat and power cogeneration system. Correspondingly, the scheduling method based on the heat and power cogeneration system can meet different scheduling requirements and increase the flexibility of scheduling. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings also belong to the protection scope of the present application.

[0019] Figure 1 It is a connection schematic diagram of one example of the system.

[0020] MARKED FOR EXPLANATION:

[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 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 conveying pipe; 62, first control valve; 71, second control valve; 72, second feed water pump. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be described below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] See Figure 1 This invention provides a combined heat and power system, including a boiler 1, a generator set, a molten salt thermal storage subsystem, and a steam thermal storage subsystem; wherein, the boiler 1 is used to provide hot steam to the generator set so that the generator set can perform work and 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 a first pipeline assembly; thus, the extracted steam from the intermediate-pressure cylinder 22 is supplied to the heat user to meet their needs. It is 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, 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] Furthermore, the molten salt thermal storage subsystem includes a cold salt tank 31, a hot salt tank 32, a thermal storage heat exchanger 33, and a heating heat exchanger 34. The thermal storage heat exchanger 33 has a first low-temperature medium flow channel 331 and a first high-temperature medium flow channel 332, and the heating 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 circuit. The first high-temperature medium flow channel 332 is connected to the steam extraction end of the intermediate 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 molten salt thermal storage subsystem allows for the storage of heat from the extraction steam of the intermediate-pressure cylinder 22 in molten salt when the unit load is low. It also allows for the release of this stored heat when the unit load is high, using it to heat the water and generate steam. This steam can then replace some or all of the extraction steam from the intermediate-pressure cylinder 22 to supply heat users, reducing the extraction steam load of the intermediate-pressure cylinder 22 and meeting the high-load demands of the generator set. It is known that a fifth control valve 311 is installed at the output end of the cold salt tank 31, and a sixth control valve 321 is installed at the output end of the hot salt tank 32, thereby controlling the flow or interruption of the molten salt circuit. A corresponding seventh control valve 330 can also be installed at the input end of the first high-temperature medium flow channel 332.

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

[0029] The above scheme enables rapid regulation of the steam quantity in the intermediate-pressure cylinder 22 and the steam supply to the low-pressure cylinder 23 through the coordinated operation of the steam storage tank 41 and the molten salt thermal storage subsystem. This, in turn, regulates the amount of steam entering the generator set to perform work, thereby increasing the generator set's load change rate and enhancing its ability to participate in frequency regulation. Furthermore, the molten salt thermal storage subsystem achieves complete decoupling of heat and electricity, expanding the generator set's operating range for both electrical and thermal loads and improving its peak-shaving capability. The coordinated operation of the molten salt and steam thermal storage subsystems can meet different scheduling needs of the generator set, increasing the operational flexibility of the combined heat and power system.

[0030] See Figure 1In this embodiment, the cogeneration system also includes a steam condensation reflux subsystem. 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 has done work can be condensed into condensate and returned to the boiler 1 to generate steam to supply the generator set.

[0031] Specifically, in the direction of flow 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 feedwater pump 54 connected in sequence by pipelines.

[0032] Furthermore, the 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 condensed water 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 transported from the low-pressure cylinder 23 to the deaerator 53.

[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 supply it to the heat user.

[0035] See 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 pipelines.

[0036] See 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 Figure 1 The steam thermal storage subsystem also includes a third control valve 42 and a fourth control valve 43, which are respectively located upstream and downstream of the steam thermal storage tank 41.

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

[0039] When the generator receives a frequency regulation command, the high steam velocity in the system means that changing the amount of steam entering the generator to perform work will rapidly affect the generator's output electrical load. Specifically, when a rapid load reduction is needed, a portion of the extracted steam from the intermediate-pressure cylinder 22 is stored in the steam storage tank 41. At this time, the amount of steam entering the low-pressure cylinder 23 to perform work decreases, causing the generator's output power to drop rapidly. Simultaneously, a portion of the extracted steam from the intermediate-pressure cylinder 22 can be sent to the heat exchanger 33 to exchange heat with the molten salt input into the heat exchanger 33 from the cold salt tank 31. 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 sent to the deaerator 53. When a rapid load increase is needed, the hot steam stored in the steam storage tank 41 is rapidly released and sent to the low-pressure cylinder 23 to perform work, thereby rapidly increasing the generator's output power.

[0040] When the unit receives a peak-shaving command, the unit's electrical load regulation range is affected by the heat supply to heat users. Therefore, the molten salt thermal storage subsystem is needed to supply heat to these users, thereby achieving thermoelectric 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 thermal storage subsystem stores heat. Part of the extracted steam from the intermediate-pressure cylinder 22 is sent to the thermal storage heat exchanger 33 to exchange heat with the molten salt input to the heat exchanger 33 from the cold salt tank 31. The high-temperature molten salt after heat exchange is then stored in the hot salt tank 32. When the unit receives a peak-shaving command and needs to expand its electrical load operating range, the first control valve 62 is completely closed. The steam for heat users is entirely supplied by the steam generated by the molten salt thermal storage subsystem, thus achieving complete thermoelectric decoupling of the unit.

[0041] Through the above adjustments, the heating supply to heat users remained stable, and the operating range of the electrical and thermal loads of the cogeneration units and the rate of load increase and decrease were greatly improved, thereby enhancing the operational flexibility of the cogeneration units.

[0042] This invention also provides a scheduling method applicable to the above-mentioned cogeneration system, comprising the following steps:

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

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

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

[0046] Furthermore, it also includes the following steps:

[0047] The saturated water output from the deaerator 53 of the condensation reflux subsystem is delivered to the heating heat exchanger 34.

[0048] The high-temperature medium in the heat storage heat exchanger 33 is transported through the heat exchange medium to the deaerator 53 of the condensate flow system.

[0049] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A combined heat and power system, characterized in that... This includes boilers, generator sets, molten salt thermal storage subsystems, and steam thermal storage subsystems; The boiler is used to provide hot steam to the generator set; The generator set includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder. The extraction end of the intermediate-pressure cylinder is connected to the heat user through a first pipeline assembly. The molten salt thermal storage subsystem includes a cold salt tank, a hot salt tank, a thermal storage heat exchanger, and a heating heat exchanger. The thermal storage heat exchanger has a first low-temperature medium flow channel and a first high-temperature medium flow channel, and the heating 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 thermal storage subsystem includes a steam thermal storage tank. The input end of the steam thermal storage tank is directly connected to the steam extraction end of the intermediate-pressure cylinder via a pipeline, and the output end is directly connected to the steam inlet end of the low-pressure cylinder via a pipeline.

2. The 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 connected in sequence to form a circulation loop; The steam condensation reflux subsystem, flowing from the exhaust end of the low-pressure cylinder to the boiler, includes a condenser, a condensate pump, a deaerator, and a first feedwater pump connected in sequence by pipelines.

3. A cogeneration system according to claim 2, characterized in that, The extraction end of the intermediate 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 cryogenic 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 cryogenic medium flow channel is connected to the output end of the deaerator through a second pipeline assembly; The second piping assembly includes a second control valve and a second water supply pump connected by piping.

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 combined heat and power system according to claim 1, characterized in that, The steam thermal storage subsystem also includes a third control valve and a fourth control valve, which are respectively located 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, Includes the following steps, When the generator set needs to reduce load, the steam extracted from the intermediate pressure cylinder is stored in a steam storage tank, and / or the heat of the steam extracted from the intermediate pressure cylinder is stored in a molten salt storage subsystem. When the generator set needs to increase the load, the steam stored in the steam storage tank is delivered to the low-pressure cylinder; When the generator set needs to expand the operating range of the electrical load, the molten salt flowing in the high-temperature medium channel of the heat exchanger is controlled to exchange heat with the saturated water flowing in the low-temperature medium channel of the heat exchanger to form hot steam. The hot steam replaces part or all of the steam extracted from the intermediate pressure cylinder to supply heat users.

9. The scheduling method according to claim 8, characterized in that, It also includes the following steps: The saturated water output from the deaerator of the condensate reflux subsystem is delivered to the heating heat exchanger. The high-temperature medium from the heat storage heat exchanger is transported through the heat exchange medium to the deaerator of the condensate flow system.

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