Efficient coal-fired generator set

Abstract

The utility model relates to an efficient coal-fired generator set. The coal power unit comprises a boiler, a high-pressure cylinder, a back pressure machine and a feed water heating assembly. The steam output end of the boiler is connected with the steam input end of the back pressure machine; the steam output end of the back pressure machine is connected with the steam input end of the high-pressure cylinder; the first steam circulation area of the back pressure machine is smaller than the second steam circulation area of the high-pressure cylinder; the steam output end of the back pressure machine and the steam output end of the high-pressure cylinder are respectively connected with the feed water heating assembly so as to output steam to the feed water heating assembly; the feed water heating assembly is connected with the feed water end of the boiler so as to output feed water heated by steam to the boiler. The coal consumption of the coal power unit can be reduced.

Description

Technical Field

[0001] This application relates to the field of coal-fired power unit technology, and in particular to a high-efficiency coal-fired power unit. Background Technology

[0002] With the continuous increase in the installed capacity of new energy sources and the development of new-generation coal-fired power, the application of coal-fired power units is becoming more and more widespread, and there is a need to continuously improve the flexibility of these units. Typically, coal-fired power units generate steam by burning coal, which drives a steam turbine to power a generator.

[0003] In traditional coal-fired power unit systems, as the load decreases, the main steam pressure of the unit slides down to a lower pressure, which leads to a decrease in the unit's cycle efficiency and an increase in the unit's coal consumption. Utility Model Content

[0004] Therefore, it is necessary to provide a high-efficiency coal-fired power generation unit that can reduce coal consumption in order to address the aforementioned technical problems.

[0005] In a first aspect, this application provides a coal-fired power unit, including: a boiler, a high-pressure cylinder, a back pressure unit, and a feedwater heating assembly;

[0006] The steam output end of the boiler is connected to the steam input end of the back pressure unit;

[0007] The steam output end of the back pressure compressor is connected to the steam input end of the high-pressure cylinder; the first steam flow area of ​​the back pressure compressor is smaller than the second steam flow area of ​​the high-pressure cylinder.

[0008] The steam output end of the back pressure compressor and the steam output end of the high-pressure cylinder are respectively connected to the feedwater heating component to output steam to the feedwater heating component;

[0009] The feedwater heating unit is connected to the feedwater end of the boiler to output feedwater heated by steam to the boiler.

[0010] In one embodiment, the water heating assembly includes a high-pressure heater;

[0011] The high-pressure heater is connected to the high-pressure cylinder to extract high-pressure exhaust steam from the high-pressure cylinder to heat the feedwater flowing to the boiler.

[0012] In one embodiment, the water supply heating assembly further includes a water supply heater;

[0013] The water supply input terminal of the water heater is connected to the water supply output terminal of the high-pressure heater;

[0014] The feedwater heater is connected to the back pressure unit to extract steam from the back pressure unit and reheat the feedwater supplied by the high-pressure heater.

[0015] In one embodiment, the coal-fired power unit further includes:

[0016] The first valve controls the opening and closing of the steam transmission channel between the boiler and the back pressure unit; the first valve is located between the boiler and the back pressure unit.

[0017] In one embodiment, the coal-fired power unit further includes:

[0018] A second valve that controls the opening and closing of the steam transmission channel between the back pressure unit and the feedwater heater; the second valve is located between the back pressure unit and the feedwater heater.

[0019] In one embodiment, the coal-fired power unit further includes:

[0020] A third valve that controls the opening and closing of the steam transmission channel between the back compressor and the high-pressure cylinder; the third valve is located between the back compressor and the high-pressure cylinder.

[0021] In one embodiment, the coal-fired power unit also includes a first generator; a back pressure unit is also connected to the first generator.

[0022] In one embodiment, the steam output end of the boiler is also connected to the steam input end of the high-pressure cylinder; the coal-fired power unit also includes:

[0023] The fourth valve controls the opening and closing of the steam transmission channel between the boiler and the high-pressure cylinder; the third valve is located between the boiler and the high-pressure cylinder.

[0024] In one embodiment, the high-pressure heater includes a first high-pressure heater and a second high-pressure heater;

[0025] The first water supply output terminal of the first high-pressure heater is connected to the water supply input terminal of the water supply heater, and the first water supply input port of the first high-pressure heater is connected to the second water supply output terminal of the second high-pressure heater.

[0026] In one embodiment, the extraction steam temperature of the first high-pressure heater is greater than the extraction steam temperature of the second high-pressure heater.

[0027] The aforementioned coal-fired power unit includes a boiler, a high-pressure cylinder, a back-pressure turbine, and a feedwater heating assembly. The boiler's steam output is connected to the back-pressure turbine's steam input. Thus, when the unit is operating at low to medium loads, steam supply to the high-pressure cylinder is stopped, and steam is supplied from the boiler to the back-pressure turbine. At this time, all the main steam from the boiler enters the back-pressure turbine, performs work there, and is then discharged into the high-pressure cylinder. Because the first steam flow area of ​​the back-pressure turbine is smaller than the second steam flow area of ​​the high-pressure cylinder, the main steam pressure can be increased. Therefore, the back-pressure turbine can increase the main steam pressure entering it through pressure buildup, thereby improving the initial parameters of the thermodynamic cycle. Finally, the feedwater heating assembly is connected to both the back-pressure turbine's steam output and the high-pressure cylinder's steam output. The feedwater heating assembly utilizes the exhaust steam from both the back-pressure turbine and the high-pressure cylinder to heat the feedwater flowing to the boiler, thereby increasing the feedwater temperature and reducing the unit's coal consumption. Therefore, this application achieves the goal of improving unit efficiency by adding a back pressure turbine and a feedwater heater, and by increasing the main steam pressure and feedwater temperature, thereby reducing unit coal consumption and improving unit economy. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of a coal-fired power unit in one embodiment;

[0030] Figure 2 This is a structural block diagram of a coal-fired power unit in one embodiment;

[0031] Figure 3 This is a schematic diagram of the optimized coal-fired power unit structure in one embodiment.

[0032] Explanation of icon numbers:

[0033] Boiler-101; High-pressure cylinder-102; Intermediate-pressure cylinder-103; Low-pressure cylinder-104; Condenser-105; Low-pressure heater-106; Deaerator-107; First high-pressure heater-110; Second high-pressure heater-109; Third high-pressure heater-108; Back pressure unit-202; Feedwater heating assembly-203; Feedwater heater-204; First valve-205; Second valve-207; Third valve-206; Fourth valve-208; First generator-20; Second generator-30 Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0035] Coal-fired power generation is a complex energy conversion process involving the interconversion of multiple energy forms. The unit mainly consists of a boiler, turbine, generator, and auxiliary systems. In the boiler, coal is fed into the combustion chamber for combustion, releasing a large amount of heat energy. Feedwater in the boiler is heated and evaporated through heating surfaces, forming high-temperature, high-pressure steam. After entering the turbine, the steam expands on the blades, driving them to rotate and thus converting heat energy into mechanical energy. The mechanical energy output from the turbine is converted into electrical energy by the generator and transmitted to the outside world through power lines.

[0036] Steam turbine cylinders can be classified into high-pressure cylinders, intermediate-pressure cylinders, and low-pressure cylinders based on different steam inlet parameters. Figure 1 A schematic diagram of a coal-fired power unit is shown. The coal-fired power unit 10 includes a boiler 101, a high-pressure cylinder 102, an intermediate-pressure cylinder 103, a low-pressure cylinder 104, a condenser 105, a low-pressure heater 106, a deaerator 107, a third high-pressure heater 108, a second high-pressure heater 109, and a first high-pressure heater 110. The third high-pressure heater, the second high-pressure heater, and the first high-pressure heater are connected sequentially via feedwater channels, and the steam extraction temperature of the third high-pressure heater, the second high-pressure heater, and the first high-pressure heater increases sequentially.

[0037] Specifically, the main steam discharged from boiler 101 enters high-pressure cylinder 102. The exhaust steam from high-pressure cylinder 102 enters the reheater of boiler 101 for reheating, forming reheated steam. Simultaneously, the second high-pressure heater 109 and the first high-pressure heater 110 extract exhaust steam from high-pressure cylinder 102 at different temperatures for reheating. The reheated steam discharged from boiler 101 enters intermediate-pressure cylinder 103. The intermediate-pressure exhaust steam from intermediate-pressure cylinder 103 enters low-pressure cylinder 104, while the third high-pressure heater 108 extracts a portion of the exhaust steam from intermediate-pressure cylinder 103 for reheating. The exhaust steam that performs work in low-pressure cylinder 104 enters condenser 105 and condenses into water. The condensate then sequentially enters low-pressure heater 106, deaerator 107, third high-pressure heater 108, second high-pressure heater 109, and first high-pressure heater 110, finally returning to boiler 101, thus realizing the boiler's thermal cycle. The power generated by the first generator 20 comes from the combined work of the high-pressure cylinder 102, the medium-pressure cylinder 103, and the low-pressure cylinder 104. The condenser in this scheme can be replaced by an air-cooled island.

[0038] It is understandable that with the changing energy structure, coal-fired power will shift towards a supporting and regulating power source in the future. The operating time of coal-fired power units under rated and high-load conditions will decrease, and operation under medium and low load conditions will become the main operating mode. This places higher demands on the operation of coal-fired power units under medium and low load conditions. In traditional coal-fired power unit systems, as the load decreases, the main steam pressure of the unit slides to a lower pressure, resulting in a decrease in the unit's cycle efficiency and an increase in coal consumption.

[0039] Based on this, this plan selects to add a back-pressure turbine and a feedwater heater. A back-pressure turbine is a steam turbine with an exhaust pressure higher than atmospheric pressure, significantly higher than that of a condensing steam turbine. The main steam can enter the back-pressure turbine to perform work before entering the high-pressure cylinder. The back-pressure turbine can increase the main steam pressure through pressure buildup, thereby improving the energy conversion efficiency of the entire coal-fired power unit. This effectively reduces the unit's coal consumption and improves its economic efficiency. The feedwater heater is a steam-water heat exchange device that uses extracted steam to heat the boiler feedwater. By further heating the boiler feedwater, it improves the overall thermal cycle efficiency of the coal-fired power unit.

[0040] In some embodiments, Figure 2 A structural block diagram of a coal-fired power unit is shown, wherein the coal-fired power unit 10 includes: a boiler 101, a high-pressure cylinder 102, a back pressure machine 202, and a feedwater heating assembly 203.

[0041] The boiler 101 has a steam output terminal connected to the back pressure unit 202's steam input terminal; the boiler 101 has a steam output terminal connected to the high-pressure cylinder 102's steam input terminal; the back pressure unit 202 has a steam output terminal connected to the high-pressure cylinder 102's steam input terminal; the back pressure unit's first steam flow area is smaller than the high-pressure cylinder's second steam flow area; the feedwater heating component 203 is connected to both the back pressure unit 202's steam output terminal and the high-pressure cylinder 102's steam output terminal, so as to use the steam output from the back pressure unit 202 and the high-pressure cylinder 102 to heat the feedwater flowing to the boiler 101.

[0042] In some embodiments, Figure 3 A schematic diagram of the optimized coal-fired power unit is shown. The feedwater heating assembly 203 includes a feedwater heater 204 and a high-pressure heater. The high-pressure heater includes a third high-pressure heater 108, a second high-pressure heater 109, and a first high-pressure heater 110.

[0043] Specifically, the back-pressure turbine is located before the high-pressure cylinder of the steam turbine and is connected in series with the high-pressure cylinder. Under medium and low load conditions, the main steam from the boiler enters the back-pressure turbine, performs work within it, and then discharges into the high-pressure cylinder to continue generating electricity. The feedwater heater draws steam from the back-pressure turbine to heat the feedwater supplied by the first high-pressure heater, thereby increasing the feedwater temperature.

[0044] It should be noted that the steam flow area refers to the channel area of ​​the steam flow passage inside the back pressure compressor / high-pressure cylinder, which can characterize the flow velocity and flow rate of steam in the back pressure compressor / high-pressure cylinder. By setting the first steam flow area of ​​the back pressure compressor 202 to be smaller than the second steam flow area of ​​the high-pressure cylinder 102, when the back pressure compressor 202 and the high-pressure cylinder 102 are connected in series, the main steam will first enter the back pressure compressor 202, then be discharged from the back pressure compressor 202, and enter the high-pressure cylinder 102. Since the back pressure compressor 202 has a lower steam flow area, the main steam pressure in the main steam transmission pipeline can be increased, that is, the main steam pressure is increased by pressure buildup. After the pressurized main steam flows into the back pressure compressor 202 to do work, the main steam pressure decreases, and then it is input into the high-pressure cylinder 102 to do work.

[0045] For example, assuming 70% load is applied to the back pressure turbine, the original main steam pressure at 70% load is 22 MPa. With the back pressure turbine 202 and high-pressure cylinder 102 connected in series, the main steam pressure can be increased to 28 MPa through pressure build-up in the back pressure turbine 202. Therefore, the main steam pressure entering the back pressure turbine 202 is 28 MPa. After the main steam enters the back pressure turbine 202 and performs work, the exhaust pressure of the back pressure turbine 202 will decrease back to 22 MPa before entering the high-pressure cylinder 102. From the perspective of the high-pressure cylinder 102's operation, the steam pressure entering the high-pressure cylinder 102 is 22 MPa regardless of the presence of the back pressure turbine 202, and the energy conversion efficiency of the high-pressure cylinder 102 will not change. However, without the back pressure turbine 202, the high-pressure energy conversion efficiency is only the energy conversion efficiency of the high-pressure cylinder 102 alone. With the back pressure turbine 202 installed, the energy conversion efficiency of the high-pressure cylinder 102 will not change, and the back pressure turbine 202 will also operate efficiently, improving the overall energy conversion efficiency of the coal-fired power unit. The back pressure unit 202 can effectively increase the main steam pressure, thereby improving the overall energy conversion efficiency of the coal-fired power unit, without the need to redesign the high-pressure cylinder.

[0046] In the above embodiments, the coal-fired power unit includes a boiler, a high-pressure cylinder, a back-pressure turbine, and a feedwater heating assembly. The steam output end of the boiler is connected to the steam input end of the back-pressure turbine. Thus, when the coal-fired power unit is operating at medium to low load, steam supply to the high-pressure cylinder is stopped, and steam supply from the boiler to the back-pressure turbine is controlled. At this time, all the main steam from the boiler enters the back-pressure turbine, performs work in the back-pressure turbine, and is then discharged into the high-pressure cylinder. Since the first steam flow area of ​​the back-pressure turbine is smaller than the second steam flow area of ​​the high-pressure cylinder, the main steam pressure can be increased. Therefore, the back-pressure turbine can increase the main steam pressure entering the back-pressure turbine by pressure buildup, thereby improving the initial parameters of the thermodynamic cycle. Finally, the feedwater heating assembly is connected to the steam output ends of both the back-pressure turbine and the high-pressure cylinder. The feedwater heating assembly can use the exhaust steam from the back-pressure turbine and the high-pressure cylinder to heat the feedwater flowing to the boiler, thereby increasing the feedwater temperature and reducing the unit's coal consumption. Therefore, this application achieves the goal of improving unit efficiency by adding a back pressure turbine and a feedwater heater, and by increasing the main steam pressure and feedwater temperature, thereby reducing unit coal consumption and improving unit economy.

[0047] In some embodiments, the high-pressure heater is connected to the high-pressure cylinder 102 and is used to extract high-pressure exhaust steam from the high-pressure cylinder 102 to heat the feedwater flowing to the boiler; the feedwater input end of the feedwater heater 204 is connected to the feedwater output end of the high-pressure heater; the feedwater heater 204 is connected to the back pressure machine 202 and is used to extract steam from the back pressure machine 202 to reheat the feedwater delivered by the high-pressure heater.

[0048] Specifically, after the low-pressure heater 106 heats the condensate produced by the condenser 106, the heated feedwater is processed by the deaerator 107 and then sent to the third high-pressure heater 108. The third high-pressure heater 108 then reheats the feedwater using steam extracted from the intermediate-pressure cylinder 103, and sends the reheated feedwater to the second high-pressure heater 109 through the feedwater channel. The second high-pressure heater 109 also reheats the feedwater using steam extracted from the high-pressure cylinder 102, and sends the reheated feedwater to the first high-pressure heater 110 through the feedwater channel. After the first high-pressure heater 110 heats the feedwater using extracted steam, the reheated feedwater is sent to the newly added feedwater heater 204 through the feedwater channel. The feedwater heater 204 further heats the feedwater using steam extracted from the back pressure turbine, and then sends the heated feedwater to the boiler 101.

[0049] In the above embodiments, by adding a feedwater heater between the high-pressure heater and the boiler, the feedwater is further heated and the feedwater temperature is increased, thereby improving the overall cycle thermal efficiency of the unit.

[0050] In some embodiments, the coal-fired power unit 10 may further include a first valve 205 disposed between the boiler 101 and the back pressure unit 202 for controlling the opening and closing of the steam transmission channel between the boiler 101 and the back pressure unit 202; a second valve 207 disposed between the back pressure unit 202 and the feedwater heater 204 for controlling the opening and closing of the steam transmission channel between the back pressure unit 202 and the feedwater heater 204; a third valve 206 disposed between the back pressure unit 202 and the high-pressure cylinder 102 for controlling the opening and closing of the steam transmission channel between the back pressure unit and the high-pressure cylinder; the steam output end of the boiler 101 is also connected to the steam input end of the high-pressure cylinder 102; and a fourth valve 208 disposed between the boiler 101 and the high-pressure cylinder 102 for controlling the opening and closing of the steam transmission channel between the boiler 101 and the high-pressure cylinder 102.

[0051] Specifically, when the coal-fired power unit is operating at low to medium load, the back pressure turbine 202 is put into operation. At this time, the first valve 205, the second valve 207, and the third valve 206 are all open, allowing main steam to enter the back pressure turbine 202. Part of the exhaust steam from the back pressure turbine 202 enters the feedwater heater 204 to further heat the feedwater. Simultaneously, after performing work in the back pressure turbine 202, the main steam flows into the high-pressure cylinder 102 to continue performing work. Meanwhile, the fourth valve 208 is closed, preventing main steam from entering the high-pressure cylinder 102.

[0052] In some embodiments, when the coal-fired power unit is under high load, the unit operates relatively stably, and the initial parameters of the thermodynamic cycle, i.e., the main steam parameters, are also high. Therefore, the coal consumption increases only slightly compared to the rated operating condition, and the back pressure turbine and additional heaters do not need to be put into operation. In this case, the first valve 205, the second valve 207, and the third valve 206 are all closed, and the main steam does not enter the back pressure turbine 202. At the same time, the fourth valve 208 is in the open state, and the main steam enters the high-pressure cylinder 102.

[0053] In some embodiments, the back pressure turbine may not be used when the coal-fired power unit is under high load. Two scenarios are possible in this case: First, if the back pressure turbine is not used for an extended period, it can be considered completely shut down. In this case, the first valve 205, the second valve 207, and the third valve 206 are all closed, and main steam does not enter the back pressure turbine 202. Second, if the back pressure turbine is not used for a short period or temporarily, it can be considered in standby mode. In this case, a small amount of steam can be controlled to enter the back pressure turbine to maintain its operating temperature, facilitating its immediate operation. Therefore, in this scenario, the first valve 205, the second valve 207, and the fourth valve 208 are fully open, allowing main steam to enter the high-pressure cylinder 102 and the back pressure turbine 202 respectively to perform work. The exhaust steam from the back pressure turbine 202 enters the feedwater heater 204 to heat the feedwater. Simultaneously, the third valve 206 is closed to prevent the exhaust steam from the back pressure turbine 202 from entering the high-pressure cylinder 102.

[0054] In this context, the back pressure turbine being in standby mode refers to the back pressure turbine being able to quickly start up without participating in power generation, typically within a few minutes, by maintaining its operating temperature and minimum steam supply. This is a transitional state between "operation" and "shutdown".

[0055] In some embodiments, a minimum steam inlet flow rate can be input to the back-pressure turbine when it is in standby mode. The minimum steam inlet flow rate refers to the lowest steam flow rate that the back-pressure turbine must maintain in standby mode. The minimum steam inlet flow rate can maintain the operating temperature of the back-pressure turbine and ensure its rapid commissioning capability.

[0056] In the above embodiments, by installing valves between the boiler and the back pressure machine, between the boiler and the high-pressure cylinder, between the back pressure machine and the high-pressure cylinder, and between the back pressure machine and the feedwater heater, the opening or closing of each steam transmission pipeline can be precisely controlled, thereby improving the accuracy of steam transmission control.

[0057] In some embodiments, the coal-fired power unit 10 may further include a second generator 30, and a back compressor 202 is connected to the second generator 30. In this way, the back compressor 202 can generate electricity by using the main steam and supply it to the plant for power consumption.

[0058] Based on the above, this solution adds a back-pressure turbine, allowing main steam to perform work in the back-pressure turbine even under low to medium load conditions. The steam output of the back-pressure turbine is connected to the steam input of the high-pressure cylinder; therefore, the steam performs work in the back-pressure turbine before flowing into the high-pressure cylinder, achieving cascaded energy utilization. This solution also adds a feedwater heater, whose heating steam comes from the exhaust steam of the back-pressure turbine, further increasing the feedwater temperature and thus reducing the unit's coal consumption.

[0059] Moreover, in this scheme, the steam flow area of ​​the back pressure compressor is smaller than that of the high-pressure cylinder, which can increase the main steam pressure. That is, the back pressure compressor increases the main steam pressure by pressurizing, which can improve the initial parameters of the thermodynamic cycle and reduce the unit's coal consumption.

[0060] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A coal-fired power unit, characterized in that, The coal-fired power unit includes: a boiler, a high-pressure cylinder, a back pressure machine, and a feedwater heating assembly; The steam output end of the boiler is connected to the steam input end of the back pressure machine; The steam output end of the back pressure machine is connected to the steam input end of the high-pressure cylinder; the first steam flow area of ​​the back pressure machine is smaller than the second steam flow area of ​​the high-pressure cylinder. The steam output end of the back pressure machine and the steam output end of the high-pressure cylinder are respectively connected to the water supply heating assembly to output steam to the water supply heating assembly; The water supply heating component is connected to the water supply end of the boiler to output water heated by the steam to the boiler.

2. The coal-fired power plant of claim 1, wherein, The water supply heating assembly includes a high-pressure heater; The high-pressure heater is connected to the high-pressure cylinder to extract high-pressure exhaust steam from the high-pressure cylinder to heat the feedwater flowing to the boiler.

3. The coal-fired power plant of claim 2, wherein, The water supply heating assembly also includes a water supply heater; The water supply input terminal of the water supply heater is connected to the water supply output terminal of the high-pressure heater; The feedwater heater is connected to the back pressure unit to extract steam from the back pressure unit and reheat the feedwater supplied by the high-pressure heater.

4. The coal-fired power plant of claim 1, wherein, The coal-fired power unit also includes: A first valve that controls the opening and closing of the steam transmission channel between the boiler and the back pressure unit; the first valve is located between the boiler and the back pressure unit.

5. The coal-fired power plant of claim 3, wherein, The coal-fired power unit also includes: A second valve controls the opening and closing of the steam supply channel between the back pressure unit and the feedwater heater; the second valve is located between the back pressure unit and the feedwater heater.

6. The coal-fired power plant of claim 1, wherein, The coal-fired power unit also includes: A third valve controls the opening and closing of the steam transmission channel between the back compressor and the high-pressure cylinder; the third valve is located between the back compressor and the high-pressure cylinder.

7. The coal-fired power plant of claim 1, wherein, The coal-fired power unit also includes a first generator; the back pressure unit is also connected to the first generator.

8. The coal-fired power plant of claim 1, wherein, The steam output end of the boiler is also connected to the steam input end of the high-pressure cylinder; the coal-fired power unit also includes: A fourth valve controls the opening and closing of the steam transmission channel between the boiler and the high-pressure cylinder; the fourth valve is located between the boiler and the high-pressure cylinder.

9. The coal-fired power unit according to claim 2 or 3, characterized in that, The high-pressure heater includes a first high-pressure heater and a second high-pressure heater. The first water supply output terminal of the first high-pressure heater is connected to the water supply input terminal of the water supply heater, and the first water supply input port of the first high-pressure heater is connected to the second water supply output terminal of the second high-pressure heater.

10. The coal-fired power plant of claim 9, wherein, The extraction steam temperature of the first high-pressure heater is greater than that of the second high-pressure heater.

Images