A waste heat recovery combined heat and power system and method based on medium pressure cylinder split

Abstract

The application provides a waste heat recovery combined heat and power system and method based on medium-pressure cylinder division, which comprises a thermal power heat supply subsystem and a heat network heat supply subsystem, wherein the thermal power heat supply subsystem is connected with the heat network heat supply subsystem; the thermal power heat supply subsystem is used for providing steam and electric energy to users, wherein the thermal power heat supply subsystem comprises a first medium-pressure cylinder, a second medium-pressure cylinder and a condenser; the condenser is connected with the heat network heat supply subsystem; the heat network heat supply subsystem is used for inputting heat network return water into the condenser to absorb steam heat in the condenser, generating heat network supply water and then providing heat energy to users. The technical scheme provided by the application realizes energy cascade utilization, energy saving and emission reduction, and fully utilizes unit exhaust steam waste heat in the heating season, and reduces cold source loss.

Description

Technical Field

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

[0002] Renewable energy sources such as wind and solar power are intermittent and volatile, posing new challenges to the power grid. Combined heat and power (CHP) units, while providing industrial steam, also frequently participate in peak shaving. This forces existing thermal power units to use hot reheat steam to reduce temperature and pressure under low-load conditions to meet the parameter requirements of low-pressure industrial steam supply, which could originally be sourced from intermediate-pressure cylinder exhaust. This results in poor thermal economy and increased coal consumption. A comprehensive approach is needed, considering energy-saving and consumption-reducing retrofits for coal-fired power plants, heating system upgrades, and flexibility improvements, to achieve coordinated "three-pronged" reforms.

[0003] The commonly used low-pressure industrial steam supply technology for existing cogeneration units is intermediate-pressure cylinder exhaust steam heating, with hot reheat steam as a backup steam source. However, for the most commonly used 300MW-class thermal power units in China, intermediate-pressure cylinder exhaust steam, under 75% THA conditions, struggles to provide the required steam supply of 100t / h at industrial parameters of 0.5MPa. While hot reheat steam pressure-reduced heating can meet the steam supply requirements under low-load conditions, its economic efficiency is poor and it fails to meet the requirements of the "three-stage" (renovation, upgrading, and transformation) linkage. Therefore, developing a new, efficient, flexible waste heat recovery cogeneration technology that enables cascaded energy utilization is urgently needed. Summary of the Invention

[0004] This application provides a waste heat recovery cogeneration system and method based on a medium-pressure cylinder, which at least solves the technical problems of poor economic efficiency caused by the inability of existing heating technologies to save energy and reduce emissions and the failure of energy cascade utilization.

[0005] The first aspect of this application proposes a waste heat recovery cogeneration system based on a medium-pressure cylinder with separate cylinders, comprising: a thermal power heating subsystem and a heating network heating subsystem, wherein the thermal power heating subsystem is connected to the heating network heating subsystem;

[0006] The thermal power heating subsystem is used to provide steam and electricity to users, and the thermal power heating subsystem includes a first intermediate pressure cylinder, a second intermediate pressure cylinder, and a condenser; The condenser is connected to the heating network subsystem, which is used to input the return water from the heating network into the condenser to absorb the heat of the steam in the condenser, generate heating network water, and then provide heat energy to users.

[0007] Preferably, the thermal power heating subsystem further includes: a boiler, a high-pressure cylinder, a low-pressure cylinder, and a generator; The boiler, the high-pressure cylinder, the first intermediate-pressure cylinder, the second intermediate-pressure cylinder, the low-pressure cylinder, and the generator are connected in sequence; 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.

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

[0009] Furthermore, the thermal power heating subsystem 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 thermal power heating subsystem 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 thermal power heating subsystem also includes: condensate pumps and 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] The second aspect of this application proposes a waste heat recovery cogeneration method based on intermediate-pressure cylinder division, including: Steam and electricity are generated using a thermal power heating subsystem, and the steam is delivered to users and the condenser in the thermal power heating subsystem, while the electricity is delivered to users. The heat return water in the heating network subsystem is fed into the condenser to absorb the heat of the steam in the condenser, generating heat network supply water, and then providing heat energy to users.

[0014] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements the method described in the second aspect of the embodiment.

[0015] The fourth 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 bring at least the following beneficial effects: This application proposes a waste heat recovery cogeneration system and method based on intermediate-pressure cylinder sub-cylinders. The system includes a thermal power heating subsystem and a heating network subsystem, with the thermal power heating subsystem connected to the heating network subsystem. The thermal power heating subsystem provides steam and electricity to users, and includes a first intermediate-pressure cylinder, a second intermediate-pressure cylinder, and a condenser. The condenser is connected to the heating network subsystem, which uses the heating network return water to absorb the heat from the steam in the condenser, generating heating network supply water, and thus providing heat energy to users. The technical solution proposed in this application achieves energy cascade utilization, energy saving and emission reduction, and fully utilizes the waste heat from the unit's exhaust steam during the heating season, reducing cold source losses.

[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 application provides a structure for a waste heat recovery cogeneration system based on a medium-pressure cylinder with separate cylinders, according to one embodiment of the present application. Figure 2 This is a detailed structural diagram of a waste heat recovery cogeneration system based on a medium-pressure cylinder with separate cylinders, according to an embodiment of this application; Figure 3 This is a flowchart of a waste heat recovery cogeneration method based on a medium-pressure cylinder splitting according to an embodiment of this application; Figure Labels Thermal power heating subsystem 1, heating network heating subsystem 2, first intermediate pressure cylinder 1-1, second intermediate pressure cylinder 1-2, condenser 1-3, boiler 1-4, high pressure cylinder 1-5, low pressure cylinder 1-6, generator 1-7, first connecting pipe 1-8, second connecting pipe 1-9, low pressure industrial steam supply main pipe 1-10, sealing butterfly valve 1-11, condensate pump 1-12, unit regeneration subsystem 1-13. 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 waste heat recovery cogeneration system and method based on intermediate-pressure cylinder sub-cylinders. The system includes a thermal power heating subsystem and a heating network subsystem, with the thermal power heating subsystem connected to the heating network subsystem. The thermal power heating subsystem provides steam and electricity to users, and includes a first intermediate-pressure cylinder, a second intermediate-pressure cylinder, and a condenser. The condenser is connected to the heating network subsystem, which uses the heating network return water to absorb the heat from the steam in the condenser, generating heating network supply water, and thus providing heat energy to users. The technical solution proposed in this application achieves energy cascade utilization, energy saving and emission reduction, and fully utilizes the waste heat from the unit's exhaust steam during the heating season, reducing cold source losses.

[0021] The following description, with reference to the accompanying drawings, describes an embodiment of the present application of a waste heat recovery cogeneration system and method based on a medium-pressure cylinder.

[0022] Example 1 Figure 1 This is a structural diagram of a waste heat recovery cogeneration system based on a medium-pressure cylinder sub-cylinder according to an embodiment of this application, as shown below. Figure 1 As shown, it includes: a thermal power heating subsystem 1 and a heating network heating subsystem 2, wherein the thermal power heating subsystem 1 is connected to the heating network heating subsystem 2; The thermal power heating subsystem 1 is used to provide steam and electricity to users. The thermal power heating subsystem 1 includes a first intermediate pressure cylinder 1-1, a second intermediate pressure cylinder 1-2, and a condenser 1-3. The condenser 1-3 is connected to the heating network subsystem 2. The heating network subsystem 2 is used to input the return water from the heating network into the condenser 1-3 to absorb the heat of the steam in the condenser 1-3, generate heating network water, and then provide heat energy to users.

[0023] It should be noted that, Figure 1 This is merely a schematic diagram of a waste heat recovery cogeneration system based on a medium-pressure cylinder, and does not limit the structure of the cogeneration system in this application.

[0024] In the embodiments disclosed herein, such as Figure 2 As shown, the thermal power heating subsystem 1 also includes: a boiler 1-4, a high-pressure cylinder 1-5, a low-pressure cylinder 1-6, and a generator 1-7; The boiler 1-4, the high-pressure cylinder 1-5, the first intermediate-pressure cylinder 1-1, the second intermediate-pressure cylinder 1-2, the low-pressure cylinder 1-6, and the generator 1-7 are connected in sequence; The boiler 1-4 is used to heat condensate to generate steam and deliver the steam to the high-pressure cylinder 1-5; The boiler 1-4 is also used to heat the cold resteam discharged from the high-pressure cylinder 1-5 to generate hot resteam, and to transport the hot resteam to the first intermediate-pressure cylinder 1-1; The first intermediate-pressure cylinder 1-1 and the second intermediate-pressure cylinder 1-2 are both used to provide steam to the user; The generators 1-7 are used to generate electricity based on steam.

[0025] It should be noted that, as Figure 2 As shown, a first connecting pipe 1-8 is provided between the first intermediate pressure cylinder 1-1 and the second intermediate pressure cylinder 1-2; A second connecting pipe 1-9 is provided between the second intermediate pressure cylinder 1-2 and the low pressure cylinder 1-6.

[0026] Furthermore, such as Figure 2 As shown, the thermal power heating subsystem 1 also includes: a low-pressure industrial steam supply header 1-10; The low-pressure industrial steam supply main pipe 1-10 is connected to the first connecting pipe 1-8 and the second connecting pipe 1-9 respectively.

[0027] It should be noted that, as Figure 2 As shown, the thermal power heating subsystem 1 also includes: multiple sealing butterfly valves 1-11; The low-pressure industrial steam supply main pipe 1-10 is connected to the first connecting pipe 1-8 and the second connecting pipe 1-9 respectively through sealing butterfly valve 1-11.

[0028] When the unit load corresponding to the boiler 1-4 is less than the preset first load value, the sealing butterfly valve 1-11 connected to the first connecting pipe 1-8 is opened, and the sealing butterfly valve 1-11 connected to the second connecting pipe 1-9 is closed. Low-pressure steam is provided to the user by the extraction of steam in the first intermediate pressure cylinder 1-1 and the second intermediate pressure cylinder 1-2. 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 1-4 is greater than or equal to the preset first load value, the sealing butterfly valve 1-11 connected to the second connecting pipe 1-9 is opened, the sealing butterfly valve 1-11 connected to the first connecting pipe 1-8 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 1-2.

[0029] The intermediate pressure cylinder is divided into two parts. After the hot reheat steam does work in the first intermediate pressure cylinder 1-1, it enters the connecting pipe between the first and second sections of the intermediate pressure cylinder, namely the first connecting pipe 1-8. The connecting pipe 1-8 between the first intermediate pressure cylinder 1-1 and the second intermediate pressure cylinder 1-2 can extract steam for heating. At the same time, combined with the original intermediate pressure cylinder exhaust steam extraction, a steam extraction system with dual extraction nodes is formed.

[0030] It should be noted that during the heating season, the back pressure of the exhaust steam from the low-pressure cylinders 1-6 is increased to 50 kPa, and the return water of the heating network is introduced into the condenser 1-3 to absorb the waste heat of the exhaust steam and form a heating network water supply of about 80°C. At the same time, the exhaust steam is condensed into liquid water in the condenser 1-3.

[0031] For example, the steam discharged from the low-pressure cylinder 1-6 connected to the condenser 1-3 and entering the condenser 1-3 can be 80 degrees Celsius. The temperature of the steam in the condenser 1-3 is used to heat the heat network return water of the heating network subsystem 2. After being heated, the heat network return water becomes the heat network supply water, which provides heat energy to users. The temperature of the heat network return water can be around 50 degrees Celsius.

[0032] Furthermore, by heating the return water of the heat network based on the condenser 1-3, the waste heat of the unit's exhaust steam is utilized, reducing cold source loss and saving energy.

[0033] In the embodiments disclosed herein, such as Figure 2 As shown, the thermal power heating subsystem 1 also includes: condensate pump 1-12 and unit regenerative subsystem 1-13; One end of the condenser 1-3 is connected to the outlet of the low-pressure cylinder 1-6, and the other end is connected to the condensate pump 1-12; The unit's regenerative subsystem 1-13 is connected to the boiler 1-4, the high-pressure cylinder 1-5, the first intermediate-pressure cylinder 1-1, the second intermediate-pressure cylinder 1-2, the low-pressure cylinder 1-6, the condenser 1-3, and the condensate pump 1-12, respectively.

[0034] It should be noted that, as Figure 2 As shown, the unit's regenerative subsystem 1-13 includes: 3 high-pressure heaters, 1 deaerator, 1 feedwater pump, and 4 low-pressure heaters.

[0035] For example, taking a conventional 350MW supercritical unit (main steam pressure 24.2MPa, main steam temperature 566℃, reheat steam temperature 566℃) as a reference, and under the condition that the unit simultaneously meets the requirements of industrial steam supply (pressure 2MPa, temperature 200℃, steam extraction rate 100t / h) and residential heating, the main performance parameters of the system in this invention are calculated and summarized in Table 1. Under the main steam parameters (24.2 MPa, 566℃, 1008.5 t / h), the boiler heat absorption is 744.7 MW, the unit power generation is 291.1 MW, the industrial steam supply heat load is 77 MW, and the residential heating heat load is 373.2 MW; under the main steam parameters (23.3 MPa, 566℃, 732.8 t / h), the boiler heat absorption is 570.9 MW, the unit power generation is 209.5 MW, the industrial steam supply heat load is 77 MW, and the residential heating heat load is 281.9 MW; under the main steam parameters (15.8 MPa, 566℃, 474.9 t / h), the boiler heat absorption is 382.6 MW, the unit power generation is 126.8 MW, the industrial steam supply heat load is 77 MW, and the residential heating heat load is 176.6 MW.

[0036] Table 1. Main parameters of the system of the present invention for meeting the requirements of low-pressure industrial steam supply and residential heating.

[0037] In summary, the waste heat recovery cogeneration system based on the intermediate pressure cylinder has the following advantages: (1) Under low load conditions, compared with the de-cooling and depressurization heating of reheated steam, this scheme can realize energy cascade utilization, energy saving and emission reduction; (2) Compared with the limited extraction steam volume of the traditional regenerative system, the present invention extracts steam by drilling holes in the connecting pipe between the first and second sections of the intermediate pressure cylinder, which significantly increases the extraction steam volume and can meet the demand of 100t / h for low-pressure industrial steam extraction; (3) The system of the present invention consists of two-stage extraction steam sources: intermediate pressure cylinder exhaust and intermediate pressure cylinder first section exhaust, which can flexibly switch the heating steam source according to the unit's electrical load; (4) The thermal system proposed in this invention makes full use of the unit's waste steam heat during the heating season and reduces the loss of cold source.

[0038] Example 2 Figure 3 This is a structural diagram of a waste heat recovery cogeneration method based on a medium-pressure cylinder with separate cylinders, according to an embodiment of this application. Figure 3 As shown, the system includes: Step 1: Use the thermal power heating subsystem to generate steam and electricity, and deliver the steam to users and the condenser in the thermal power heating subsystem, and deliver the electricity to users; Step 2: The heat network return water in the heating network subsystem is input into the condenser to absorb the heat of the steam in the condenser, generate heat network supply water, and then provide heat energy to users.

[0039] In summary, the waste heat recovery cogeneration method based on intermediate-pressure cylinder division proposed in this embodiment divides the traditional intermediate-pressure cylinder into two intermediate-pressure cylinders, which can realize the cascade utilization of steam energy while meeting the steam supply needs of low-pressure industries, thereby achieving energy conservation and emission reduction; at the same time, it makes full use of the waste heat of the turbine exhaust steam and avoids the loss of cold source.

[0040] Example 3 To implement the above embodiments, this disclosure also proposes an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements the method described in Embodiment 2.

[0041] Example 4 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.

[0042] 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.

[0043] 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.

[0044] 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 waste heat recovery combined heat and power system based on medium pressure cylinder split, characterized by, include: A thermal power heating subsystem and a heating network heating subsystem, wherein the thermal power heating subsystem is connected to the heating network heating subsystem; The thermal power heating subsystem is used to provide steam and electricity to users, and the thermal power heating subsystem includes a first intermediate pressure cylinder, a second intermediate pressure cylinder, and a condenser; The condenser is connected to the heating network subsystem. The heating network subsystem is used to input the return water from the heating network into the condenser to absorb the heat of the steam in the condenser, generate heating network supply water, and then provide heat energy to users. The thermal power heating subsystem also includes: a boiler, a high-pressure cylinder, a low-pressure cylinder, and a generator; The boiler, the high-pressure cylinder, the first intermediate-pressure cylinder, the second intermediate-pressure cylinder, the low-pressure cylinder, and the generator are connected in sequence; 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 electrical energy based on steam; A second connecting pipe is provided between the second intermediate-pressure cylinder and the low-pressure cylinder; The thermal power heating subsystem also includes: a low-pressure industrial steam supply main pipe; The low-pressure industrial steam supply main pipe is connected to the first connecting pipe and the second connecting pipe, respectively.

2. The waste heat recovery cogeneration system of claim 1, wherein, The thermal power heating subsystem 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 sealed butterfly valves.

3. The waste heat recovery cogeneration system of claim 2, wherein, 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 waste heat recovery cogeneration system of claim 2, wherein, The thermal power heating subsystem also includes: condensate pumps and 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 waste heat recovery cogeneration method based on a medium-pressure cylinder sub-cylinder in the waste heat recovery cogeneration system according to any one of claims 1-4, characterized in that, The method includes: Steam and electricity are generated using a thermal power heating subsystem, and the steam is delivered to users and the condenser in the thermal power heating subsystem, while the electricity is delivered to users. The heat network return water in the heating network subsystem is fed into the condenser to absorb the heat of the steam in the condenser, generating heat network supply water, and then providing heat energy to users.

6. An electronic device, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method as described in claim 5.

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 claim 5.

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