Heat supply system and method based on energy cascade utilization of combined heat and power with medium-pressure cylinder split

Abstract

The application provides a heat supply system and method based on medium-pressure cylinder split for combined heat and power energy cascade utilization, which comprises a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder and a generator; the boiler, the high-pressure cylinder, the medium-pressure cylinder, the low-pressure cylinder and the generator are sequentially connected; wherein the medium-pressure cylinder comprises a first medium-pressure cylinder and a second medium-pressure cylinder; the boiler is used for heating condensate water to generate steam, and the steam is delivered to the high-pressure cylinder; the boiler is also used for heating cold re-steam discharged from the high-pressure cylinder to generate hot re-steam, and the hot re-steam is delivered to the first medium-pressure cylinder; the first medium-pressure cylinder and the second medium-pressure cylinder are both used for providing steam to users; and the generator is used for generating electric energy based on the steam. The technical scheme provided by the application splits the medium-pressure cylinder into two medium-pressure cylinders, so that the steam energy cascade utilization and energy saving and emission reduction can be realized while meeting the demand of low-pressure industrial steam supply.

Description

Technical Field

[0001] This application relates to the field of energy utilization, and in particular to a heating system and method based on the energy cascade utilization of cogeneration energy from a medium-pressure cylinder. Background Technology

[0002] Renewable energy sources such as wind and solar power are characterized by intermittency and volatility, which bring new challenges to the power grid. Cogeneration thermal power units need to frequently participate in peak shaving in order to provide industrial steam. This leads existing thermal power units to meet the parameter requirements of high-pressure industrial steam supply by reducing the temperature and pressure of the main steam under low load conditions, which in turn results in poor thermal economy and increased coal consumption.

[0003] The commonly used low-pressure industrial steam supply technology for existing cogeneration units is to use intermediate-pressure cylinder exhaust steam for heating, with hot reheat steam as a backup steam source. For the most commonly used 300MW-class thermal power units, intermediate-pressure cylinder exhaust steam is insufficient to meet the industrial parameters of 0.5MPa and a steam supply rate of 100t / h under 75% THA conditions. While hot reheat steam pressure reduction heating can meet the steam supply requirements under low-load conditions, its economic efficiency is poor and it is difficult to meet the requirements of the "three-stage" (renovation, upgrading, and transformation) linkage. Therefore, it is urgent to develop a new, efficient, flexible, and energy-cascade utilization-enabled low-pressure steam supply cogeneration technology. Summary of the Invention

[0004] This application provides a heating system and method based on the energy cascade utilization of cogeneration in a medium-pressure cylinder, in order to at least solve the technical problems of existing heating technologies being unable to save energy and reduce emissions and the poor economic efficiency caused by the energy cascade utilization.

[0005] The first aspect of this application proposes a cogeneration energy cascade utilization heating system based on a medium-pressure cylinder, comprising: a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, and a generator;

[0006] The boiler, the high-pressure cylinder, the medium-pressure cylinder, the low-pressure cylinder, and the generator are connected in sequence; The intermediate pressure cylinder includes a first intermediate pressure cylinder and a second intermediate pressure cylinder; The boiler is used to heat condensate to generate steam and deliver the steam to the high-pressure cylinder; The boiler is also used to heat the cold resteam discharged from the high-pressure cylinder to generate hot resteam, and to deliver the hot resteam to the first intermediate-pressure cylinder. Both the first and second intermediate-pressure cylinders are used to provide steam to the user; The generator is used to generate electricity based on steam.

[0007] Preferably, a first connecting pipe is provided between the first intermediate pressure cylinder and the second intermediate pressure cylinder.

[0008] Furthermore, a second connecting pipe is provided between the second intermediate-pressure cylinder and the low-pressure cylinder.

[0009] Furthermore, the combined heat and power energy cascade utilization heating system also includes: a low-pressure industrial steam supply header; The low-pressure industrial steam supply main pipe is connected to the first connecting pipe and the second connecting pipe, respectively.

[0010] Furthermore, the combined heat and power energy cascade utilization heating system also includes: multiple sealed butterfly valves; The low-pressure industrial steam supply main pipe is connected to the first connecting pipe and the second connecting pipe through sealing butterfly valves.

[0011] Furthermore, when the unit load corresponding to the boiler is less than the preset first load value, the sealing butterfly valve connected to the first connecting pipe is opened, and the sealing butterfly valve connected to the second connecting pipe is closed, and low-pressure steam is provided to the user by the extraction steam in the first intermediate pressure cylinder and the second intermediate pressure cylinder. When the unit load corresponding to the boiler is greater than or equal to the preset first load value, the sealing butterfly valve connected to the second connecting pipe is opened, and the sealing butterfly valve connected to the first connecting pipe is closed, and low-pressure steam is provided to the user by using the cold re-extraction steam discharged from the second intermediate pressure cylinder.

[0012] Furthermore, the combined heat and power energy cascade utilization heating system also includes: a condenser, a condensate pump, and a unit regenerative subsystem; One end of the condenser is connected to the outlet of the low-pressure cylinder, and the other end is connected to the condensate pump. The unit's regenerative subsystem is connected to the boiler, the high-pressure cylinder, the first intermediate-pressure cylinder, the second intermediate-pressure cylinder, the low-pressure cylinder, the condenser, and the condensate pump, respectively.

[0013] A second aspect of this application provides a method for cascaded utilization of cogeneration energy for heating based on intermediate-pressure cylinder sub-cylinders, the method comprising: The boiler heats the condensate to generate steam, and the steam is then sent to a high-pressure cylinder, where it performs work to discharge cold reheat steam. The cold resteam discharged from the high-pressure cylinder is heated by a boiler to generate hot resteam, and the hot resteam is then delivered to the intermediate-pressure cylinder. The intermediate-pressure cylinder supplies steam to the user based on the heat resteam; The intermediate pressure cylinder includes: a first intermediate pressure cylinder and a second intermediate pressure cylinder.

[0014] Preferably, the intermediate-pressure cylinder provides steam to the user based on the hot resteam, including: When the unit load corresponding to the boiler is less than the preset first load value, the sealing butterfly valve connected to the first connecting pipe is opened and the sealing butterfly valve connected to the second connecting pipe is closed, and low-pressure steam is provided to the user by the extraction steam in the first intermediate pressure cylinder and the second intermediate pressure cylinder. When the unit load corresponding to the boiler is greater than or equal to the preset first load value, the sealing butterfly valve connected to the second connecting pipe is opened, and the sealing butterfly valve connected to the first connecting pipe is closed. Low-pressure steam is provided to the user using the cold re-extraction steam discharged from the second intermediate pressure cylinder.

[0015] A third aspect of this application provides a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the method described in the second aspect.

[0016] The technical solutions provided by the embodiments of this application have at least the following beneficial effects: This application proposes a combined heat and power (CHP) energy cascade utilization heating system and method based on a medium-pressure cylinder divided into two cylinders. The system includes a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, and a generator. The boiler, high-pressure cylinder, medium-pressure cylinder, low-pressure cylinder, and generator are connected sequentially. The medium-pressure cylinder includes a first medium-pressure cylinder and a second medium-pressure cylinder. The boiler heats condensate to generate steam and delivers the steam to the high-pressure cylinder. The boiler also heats the cold resteam discharged from the high-pressure cylinder to generate hot resteam and delivers the hot resteam to the first medium-pressure cylinder. Both the first and second medium-pressure cylinders supply steam to users. The generator generates electricity based on the steam. The technical solution proposed in this application divides the medium-pressure cylinder into two cylinders, enabling cascade utilization of steam energy and energy conservation and emission reduction while meeting the low-pressure industrial steam supply needs.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a first structural diagram of a cogeneration energy cascade utilization heating system based on a medium-pressure cylinder sub-cylinder, according to an embodiment of this application; Figure 2 This is a second structural diagram of a cogeneration energy cascade utilization heating system based on a medium-pressure cylinder sub-cylinder, according to an embodiment of this application; Figure 3 This is a flowchart illustrating a method for cascaded utilization of cogeneration energy based on a medium-pressure cylinder sub-cylinder, according to an embodiment of this application. Figure Labels Boiler 1, High-pressure cylinder 2, Medium-pressure cylinder 3, Low-pressure cylinder 4, Generator 5, First medium-pressure cylinder 3-1, Second medium-pressure cylinder 3-2, First connecting pipe 6, Second connecting pipe 7, Low-pressure industrial steam supply main pipe 8, Sealed butterfly valve 9, Condenser 10, Condensate pump 11, Unit regenerative subsystem 12, High-pressure heater 12-1, Deaerator 12-2, Feedwater pump 12-3, Low-pressure heater 12-4. Detailed Implementation

[0019] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0020] This application proposes a combined heat and power (CHP) energy cascade utilization heating system and method based on a medium-pressure cylinder divided into two cylinders. The system includes a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, and a generator. The boiler, high-pressure cylinder, medium-pressure cylinder, low-pressure cylinder, and generator are connected sequentially. The medium-pressure cylinder includes a first medium-pressure cylinder and a second medium-pressure cylinder. The boiler heats condensate to generate steam and delivers the steam to the high-pressure cylinder. The boiler also heats the cold resteam discharged from the high-pressure cylinder to generate hot resteam and delivers the hot resteam to the first medium-pressure cylinder. Both the first and second medium-pressure cylinders supply steam to users. The generator generates electricity based on the steam. The technical solution proposed in this application divides the medium-pressure cylinder into two cylinders, enabling cascade utilization of steam energy and energy conservation and emission reduction while meeting the low-pressure industrial steam supply needs.

[0021] The following description, with reference to the accompanying drawings, describes a heating system and method based on the energy cascade utilization of a medium-pressure cylinder combined heat and power (CHP) system according to embodiments of this application.

[0022] Example 1 Figure 1 This is a structural diagram of a cogeneration energy cascade utilization heating system based on a medium-pressure cylinder sub-cylinder, according to an embodiment of this application. Figure 1 As shown, the system includes: a boiler 1, a high-pressure cylinder 2, a medium-pressure cylinder 3, a low-pressure cylinder 4, and a generator 5; The boiler 1, the high-pressure cylinder 2, the medium-pressure cylinder 3, the low-pressure cylinder 4, and the generator 5 are connected in sequence; The intermediate pressure cylinder 3 includes a first intermediate pressure cylinder 3-1 and a second intermediate pressure cylinder 3-2; The boiler 1 is used to heat condensate to generate steam and deliver the steam to the high-pressure cylinder 2; The boiler 1 is also used to heat the cold resteam discharged from the high-pressure cylinder 2 to generate hot resteam, and to transport the hot resteam to the first intermediate-pressure cylinder 3-1; The first intermediate-pressure cylinder 3-1 and the second intermediate-pressure cylinder 3-2 are both used to provide steam to the user; The generator 5 is used to generate electrical energy based on steam.

[0023] It should be noted that, Figure 1 The system shown is only a schematic diagram of a combined heat and power (CHP) energy cascade utilization heating system and does not limit the structure of the CHP energy cascade utilization heating system of the present invention.

[0024] In the embodiments disclosed herein, such as Figure 2 As shown, a first connecting pipe 6 is provided between the first intermediate pressure cylinder 3-1 and the second intermediate pressure cylinder 3-2; A second connecting pipe 7 is provided between the second intermediate pressure cylinder 3-2 and the low pressure cylinder 4.

[0025] The intermediate pressure cylinder is divided into two parts. After the hot reheat steam does work in the first intermediate pressure cylinder 3-1, it enters the connecting pipe between the first and second sections of the intermediate pressure cylinder, namely the first connecting pipe 6. The connecting pipe between the first and second sections of the intermediate pressure cylinder can extract steam for heating. At the same time, it is combined with the original intermediate pressure cylinder exhaust steam extraction to form a steam extraction system with dual extraction nodes.

[0026] It should be noted that, as Figure 2 As shown, the combined heat and power energy cascade utilization heating system also includes: a low-pressure industrial steam supply header 8; The low-pressure industrial steam supply main pipe 8 is connected to the first connecting pipe 6 and the second connecting pipe 7 respectively.

[0027] Furthermore, such as Figure 2 As shown, the combined heat and power energy cascade utilization heating system also includes: multiple sealed butterfly valves 9; The low-pressure industrial steam supply main pipe 8 is connected to the first connecting pipe 6 and the second connecting pipe 7 respectively through a sealing butterfly valve 9.

[0028] In this embodiment of the present disclosure, when the unit load corresponding to the boiler 1 is less than the preset first load value, the sealing butterfly valve 9 connected to the first connecting pipe 6 is opened and the sealing butterfly valve 9 connected to the second connecting pipe 7 is closed. The steam extracted from the first intermediate pressure cylinder 3-1 and the second intermediate pressure cylinder 3-2 is used to provide low-pressure steam to the user. The low-pressure steam can be low-pressure industrial steam with a pressure level of 0.5MPa. When the unit load corresponding to the boiler 1 is greater than or equal to the preset first load value, the sealing butterfly valve 9 connected to the second connecting pipe 7 is opened, and the sealing butterfly valve 9 connected to the first connecting pipe 6 is closed, and low-pressure steam is provided to the user by using the cold re-extraction steam discharged from the second intermediate pressure cylinder 3-2.

[0029] It should be noted that when the unit is under high load, that is, when the unit load corresponding to the boiler 1 is greater than or equal to the preset first load value, heat is supplied by exhausting steam through the second intermediate pressure cylinder 3-2; When the unit load decreases, i.e., when the unit load corresponding to boiler 1 is less than the preset first load value, the exhaust steam from the second intermediate pressure cylinder 3-2 cannot guarantee the industrial steam supply parameters. Heat is supplied by using the connecting pipes of the first and second sections of the intermediate pressure cylinder, i.e., the first connecting pipe 6, instead of the currently commonly used hot reheat steam desuperheating and depressurization heating. When the unit load corresponding to boiler 1 is less than the preset first load value, the exhaust steam from the first intermediate pressure cylinder 3-1 can increase the unit's work capacity compared to hot reheat steam desuperheating and depressurization heating, and can realize the cascade utilization of steam energy.

[0030] In the embodiments disclosed herein, such as Figure 2 As shown, the combined heat and power energy cascade utilization heating system also includes: condenser 10, condensate pump 11, and unit regenerative subsystem 12; One end of the condenser 10 is connected to the outlet of the low-pressure cylinder 4, and the other end is connected to the condensate pump 11. The unit's regenerative subsystem 12 is connected to the boiler 1, the high-pressure cylinder 2, the first intermediate-pressure cylinder 3-1, the second intermediate-pressure cylinder 3-2, the low-pressure cylinder 4, the condenser 10, and the condensate pump 11, respectively.

[0031] It should be noted that, as Figure 2 As shown, the unit's regenerative subsystem 12 includes: 3 high-pressure heaters 12-1, 1 deaerator 12-2, 1 feedwater pump 12-3, and 4 low-pressure heaters 12-4.

[0032] In the embodiments disclosed herein, the results of pure condensing operation for a conventional 350MW supercritical unit (main steam pressure 24.2MPa, main steam temperature 566℃, hot reheat steam temperature 566℃, back pressure set at 4.9kPa) are shown in Table 1.

[0033] In the combined heat and power (CHP) process, the low-pressure industrial steam supply parameters are 2 MPa pressure, 200℃ temperature, and 100 t / h extraction rate.

[0034] Calculation results show that, under the flow rate corresponding to 100% THA pure condensation, the exhaust pressure of the second intermediate pressure cylinder 3-2 is 0.585 MPa, which can be used for heating through the exhaust steam from the second connecting pipe 7 connected to the second intermediate pressure cylinder 3-2 (the pressure is adjusted by the regulating valve of the connecting pipe between the intermediate and low pressure cylinders). However, under the flow rates corresponding to 75% THA and 50% THA, the exhaust steam pressures of the second intermediate pressure cylinder 3-2 are 0.444 MPa and 0.305 MPa, respectively, which are below 0.5 MPa. Adjusting these pressures through the regulating valve of the second connecting pipe 7 is relatively difficult and insufficient to meet the heating demand. The exhaust pressures of the first intermediate pressure cylinder 3-1 (intermediate pressure cylinder section 1) and the second intermediate pressure cylinder 3-2 (intermediate pressure cylinder section 2) are 1.65 MPa and 1.11 MPa, respectively, which are higher than the industrial steam supply pressure, and heating can be provided through the exhaust steam from the first intermediate pressure cylinder 3-1.

[0035] Table 1 Main parameters of the unit under pure condensing conditions

[0036] Based on the proposed cogeneration energy cascade utilization heating system with intermediate-pressure cylinder sub-cylinders, heating operation conditions were calculated and analyzed. Under 100% THA conditions, heating was provided by exhaust steam from the intermediate-pressure cylinder; under 75% THA and 50% THA conditions, heating was provided by exhaust steam from the first intermediate-pressure cylinder 3-1. The calculation results are summarized in Table 2. As shown in Table 2, under the main steam parameters corresponding to 100% THA operating conditions, when the steam supply through the intermediate pressure cylinder is 100 t / h (0.5 MPa, 200℃), the unit's coal consumption for power generation is 270.6 g / kWh; under the main steam parameters corresponding to 75% THA operating conditions, when the steam supply through the first intermediate pressure cylinder 3-1 is 100 t / h (0.5 MPa, 200℃), the unit's coal consumption for power generation is 276.0 g / kWh; and under the main steam parameters corresponding to 50% THA operating conditions, when the steam supply through the first intermediate pressure cylinder 3-1 is 100 t / h (0.5 MPa, 200℃), the unit's coal consumption for power generation is 278.7 g / kWh.

[0037] Table 2 Main parameters for meeting low-pressure industrial steam supply requirements

[0038] Table 3 summarizes the main performance indicators of the unit under the medium-pressure cylinder section 1 exhaust steam heating scheme and the conventional hot reheat steam desuperheating and pressure reduction heating scheme in this embodiment. As can be seen from the table, under the main steam parameters corresponding to the 75% THA pure condensing condition, the coal consumption for power generation under the medium-pressure cylinder section 1 exhaust steam heating scheme of this invention is 276.0 g / kWh, while the coal consumption for power generation under the conventional hot reheat steam heating scheme is 279.7 g / kWh. The coal consumption for power generation under the medium-pressure cylinder section 1 exhaust steam heating scheme proposed in this invention is reduced by 3.7 g / kWh. Under the main steam parameters corresponding to the 50% THA pure condensing condition, the coal consumption for power generation under the medium-pressure cylinder section 1 exhaust steam heating scheme of this invention is 278.7 g / kWh, while the coal consumption for power generation under the conventional main steam heating scheme is 288.2 g / kWh. The coal consumption for power generation under the high-pressure cylinder section 1 exhaust steam heating scheme proposed in this invention is reduced by 9.5 g / kWh. Through calculation and comparison, it can be seen that the high-efficiency cogeneration energy cascade utilization heating scheme with medium-pressure cylinder section proposed in this invention has significant coal-saving benefits.

[0039] Table 3 compares the intermediate pressure cylinder stage 1 exhaust steam heating scheme with the conventional main steam heating scheme.

[0040] In summary, the cogeneration energy cascade utilization heating system based on intermediate-pressure cylinder sub-cylinder proposed in this embodiment (1) under low-load conditions, compared with heat reheat steam de-cooling and de-pressure heating, can realize energy cascade utilization, energy saving and emission reduction. For a conventional 350MW ultra-supercritical unit, under the main steam parameters corresponding to the pure condensing 50% THA condition, the coal consumption of the intermediate-pressure cylinder 1 section exhaust steam heating scheme is reduced by 9.5 g / kWh; (2) compared with the limitation of the limited steam extraction volume of the traditional regenerative system 3 extraction, the present invention drills holes in the first connecting pipe between intermediate-pressure cylinder 1 and 2 to extract steam, and the steam extraction volume is significantly increased, which can meet the demand of 100t / h for low-pressure industrial steam extraction volume; (3) the system of the present invention consists of two-stage steam extraction sources, which can flexibly switch the heating steam source according to the unit's electrical load.

[0041] Example 2 Figure 3 The flowchart below shows a method for cascaded utilization of cogeneration energy based on intermediate-pressure cylinder sub-cylinders, according to an embodiment of this application. Figure 3 As shown, the method includes: Step 1: Use a boiler to heat condensate to generate steam, and then send the steam to a high-pressure cylinder. The high-pressure cylinder performs work to discharge cold reheated steam. Step 2: Use a boiler to heat the cold resteam discharged from the high-pressure cylinder to generate hot resteam, and then send the hot resteam to the intermediate-pressure cylinder; Step 3: The intermediate-pressure cylinder supplies steam to the user based on the reheated steam; The intermediate pressure cylinder includes: a first intermediate pressure cylinder and a second intermediate pressure cylinder.

[0042] In this embodiment of the disclosure, the intermediate-pressure cylinder provides steam to the user based on the hot reheat steam, including: When the unit load corresponding to the boiler is less than the preset first load value, the sealing butterfly valve connected to the first connecting pipe is opened and the sealing butterfly valve connected to the second connecting pipe is closed, and low-pressure steam is provided to the user by the extraction steam in the first intermediate pressure cylinder and the second intermediate pressure cylinder. When the unit load corresponding to the boiler is greater than or equal to the preset first load value, the sealing butterfly valve connected to the second connecting pipe is opened, and the sealing butterfly valve connected to the first connecting pipe is closed. Low-pressure steam is provided to the user using the cold re-extraction steam discharged from the second intermediate pressure cylinder.

[0043] In summary, the cogeneration energy cascade utilization heating method based on intermediate-pressure cylinder splitting proposed in this embodiment divides the intermediate-pressure cylinder into two intermediate-pressure cylinders, which can achieve cascade utilization of steam energy and energy saving and emission reduction while meeting the steam supply needs of low-pressure industries.

[0044] Example 3 To implement the above embodiments, this disclosure also proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in Embodiment 2.

[0045] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0046] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0047] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A cogeneration energy cascade utilization heating system based on a medium-pressure cylinder with separate cylinders, characterized in that, include: Boilers, high-pressure cylinders, medium-pressure cylinders, low-pressure cylinders, and generators; The boiler, the high-pressure cylinder, the medium-pressure cylinder, the low-pressure cylinder, and the generator are connected in sequence; The intermediate pressure cylinder includes a first intermediate pressure cylinder and a second intermediate pressure cylinder; The boiler is used to heat condensate to generate steam and deliver the steam to the high-pressure cylinder; The boiler is also used to heat the cold resteam discharged from the high-pressure cylinder to generate hot resteam, and to deliver the hot resteam to the first intermediate-pressure cylinder. Both the first intermediate-pressure cylinder and the second intermediate-pressure cylinder are used to provide steam to users. A first connecting pipe is provided between the first intermediate-pressure cylinder and the second intermediate-pressure cylinder, and a second connecting pipe is provided between the second intermediate-pressure cylinder and the low-pressure cylinder. The low-pressure industrial steam supply header is connected to the first connecting pipe and the second connecting pipe respectively. The generator is used to generate electricity based on steam.

2. The cogeneration energy cascade utilization heating system as described in claim 1, characterized in that, The combined heat and power energy cascade utilization heating system also includes: multiple sealed butterfly valves; The low-pressure industrial steam supply main pipe is connected to the first connecting pipe and the second connecting pipe through sealing butterfly valves.

3. The cogeneration energy cascade utilization heating system as described in claim 2, characterized in that, When the unit load corresponding to the boiler is less than the preset first load value, the sealing butterfly valve connected to the first connecting pipe is opened, the sealing butterfly valve connected to the second connecting pipe is closed, and the low-pressure steam is provided to the user by the extraction steam in the first medium-pressure cylinder and the second medium-pressure cylinder. When the unit load corresponding to the boiler is greater than or equal to the preset first load value, the sealing butterfly valve connected to the second connecting pipe is opened, and the sealing butterfly valve connected to the first connecting pipe is closed, and low-pressure steam is provided to the user by using the cold re-extraction steam discharged from the second intermediate pressure cylinder.

4. The cogeneration energy cascade utilization heating system as described in claim 2, characterized in that, The combined heat and power energy cascade utilization heating system also includes: a condenser, a condensate pump, and a unit regenerative subsystem; One end of the condenser is connected to the outlet of the low-pressure cylinder, and the other end is connected to the condensate pump. The unit's regenerative subsystem is connected to the boiler, the high-pressure cylinder, the first intermediate-pressure cylinder, the second intermediate-pressure cylinder, the low-pressure cylinder, the condenser, and the condensate pump, respectively.

5. A method for cogeneration energy cascade utilization heating based on a medium-pressure cylinder sub-cylinder in a cogeneration energy cascade utilization heating system according to any one of claims 1-4, characterized in that, The method includes: The boiler heats the condensate to generate steam, and the steam is then sent to a high-pressure cylinder, where it performs work to discharge cold reheat steam. The cold resteam discharged from the high-pressure cylinder is heated by a boiler to generate hot resteam, and the hot resteam is then delivered to the intermediate-pressure cylinder. The intermediate-pressure cylinder supplies steam to the user based on the heat resteam; The intermediate pressure cylinder includes: a first intermediate pressure cylinder and a second intermediate pressure cylinder.

6. The cogeneration energy cascade utilization heating method as described in claim 5, characterized in that, The intermediate-pressure cylinder supplies steam to the user based on the hot reheat steam, including: When the unit load corresponding to the boiler is less than the preset first load value, the sealing butterfly valve connected to the first connecting pipe is opened and the sealing butterfly valve connected to the second connecting pipe is closed, and low-pressure steam is provided to the user by the extraction steam in the first intermediate pressure cylinder and the second intermediate pressure cylinder. When the unit load corresponding to the boiler is greater than or equal to the preset first load value, the sealing butterfly valve connected to the second connecting pipe is opened, and the sealing butterfly valve connected to the first connecting pipe is closed. Low-pressure steam is provided to the user using the cold re-extraction steam discharged from the second intermediate pressure cylinder.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 5-6.

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