Coal power unit

Abstract

The utility model relates to a coal power unit. The coal power unit comprises a boiler, a thermodynamic cycle system, a unit load adjusting device and a feed water heater. The first end of the boiler is connected with the first end of the thermodynamic cycle system, the second end of the thermodynamic cycle system is connected with the first input end of the feed water heater, and the output end of the feed water heater is connected with the second end of the boiler; the input end of the unit load adjusting device is connected with the first end of the boiler and the first end of the thermodynamic cycle system, and the first output end of the unit load adjusting device is connected with the second input end of the feed water heater. By adopting the coal power unit provided by the invention, the coal consumption can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal power units, in particular to a coal power unit. BACKGROUND

[0002] With the continuous increase of new energy installed capacity and the development of new generation coal power, coal power units are more and more widely used, and the flexibility of the units needs to be continuously improved. Generally, a coal power unit can generate steam by burning coal, drive a steam turbine to drive a generator to generate electricity.

[0003] However, when the coal power unit is at low load, there is a problem of increased coal consumption. CONTENT OF THE INVENTION

[0004] Therefore, it is necessary to provide a coal power unit capable of reducing unit coal consumption in view of the above technical problems.

[0005] In a first aspect, the present application provides a coal power unit, comprising: a boiler, a thermal cycle system, a unit load adjusting device and a feedwater heater;

[0006] The first end of the boiler is connected with the first end of the thermal cycle system, the second end of the thermal cycle system is connected with the first input end of the feedwater heater, and the output end of the feedwater heater is connected with the second end of the boiler.

[0007] The input end of the unit load adjusting device is connected with the first end of the boiler and the first end of the thermal cycle system, and the first output end of the unit load adjusting device is connected with the second input end of the feedwater heater.

[0008] In one of the embodiments, the coal power unit further comprises a steam parameter detection device, and the thermal cycle system comprises a cold end device.

[0009] The steam parameter detection device is arranged at the first output end of the unit load adjusting device.

[0010] The first output end of the unit load adjusting device is further connected with the cold end device.

[0011] In one of the embodiments, the coal power unit further comprises a steam quantity detection device, the thermal cycle system comprises a high-pressure cylinder, the first end of the thermal cycle system comprises a first input end of the high-pressure cylinder, and the steam quantity detection device is arranged at the first input end of the high-pressure cylinder.

[0012] The input end of the unit load adjusting device is connected with the first end of the boiler and the first input end of the high-pressure cylinder, and the first output end of the unit load adjusting device is further connected with the second input end of the high-pressure cylinder.

[0013] In one of the embodiments, the unit load adjusting device comprises a back pressure turbine; the second output end of the unit load adjusting device comprises a second output end of the back pressure turbine, and the second output end of the back pressure turbine is connected with the second generator.

[0014] In one of the embodiments, the unit load adjusting device comprises an attemperator.

[0015] In one of the embodiments, the unit load adjusting device comprises a back pressure turbine and an attemperator, and the back pressure turbine and the attemperator are connected in parallel.

[0016] In one of the embodiments, the coal-fired unit further comprises a first switch device; the first output end of the unit load adjusting device is connected with the cold-end device through the first switch device.

[0017] In one of the embodiments, the coal-fired unit further comprises a second switch device; the second switch device is arranged at the second input end of the feedwater heater.

[0018] In one of the embodiments, the coal-fired unit further comprises a third switch device; the first output end of the unit load adjusting device is connected with the second input end of the high-pressure cylinder through the third switch device.

[0019] In one of the embodiments, the coal-fired unit further comprises a fourth switch device and a fifth switch device, and the fourth switch device and the fifth switch device are connected in parallel; the input end of the unit load adjusting device comprises an input end of the back pressure turbine and an input end of the attemperator.

[0020] The input end of the back pressure turbine is connected with the first end of the boiler and the first end of the thermal cycle system through the fourth switch device; and the input end of the attemperator is connected with the first end of the boiler and the first end of the thermal cycle system through the fifth switch device.

[0021] The above coal-fired unit, by arranging the unit load adjusting device between the outlet of the boiler main steam and the inlet of the high-pressure cylinder, can extract part of the boiler main steam to enter the unit load adjusting device to do work under the low load working condition of the unit, and further, the unit load adjusting device can discharge steam into the feedwater heater to heat the feedwater based on the feedwater heater, so that the temperature of the feedwater is increased, thereby reducing the coal consumption of the unit, further reducing the carbon consumption and carbon dioxide emission, saving fuel cost, and helping to achieve the double carbon target. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A structural schematic diagram of a coal-fired unit in an embodiment;

[0024] Figure 2 A structural block diagram of a coal-fired unit in an embodiment;

[0025] Figure 3 A structural schematic diagram of a coal-fired unit in another embodiment;

[0026] Figure 4 A structural schematic diagram of a coal-fired unit in another embodiment;

[0027] Figure 5 A structural schematic diagram of a coal-fired unit in another embodiment.

[0028] Explanation of reference signs:

[0029] 10-coal-fired unit; 101-boiler; 102-high pressure cylinder; 103-medium pressure cylinder; 104-low pressure cylinder; 105-condenser; 106-first feed water pump; 107-low pressure heater; 108-deaerator; 109-second feed water pump; 110-high pressure heater; 20-first generator; 201-thermal cycle system; 202-unit load adjusting device; 203-feed water heater; 2021-back pressure turbine; 2022-temperature and pressure reducer; 204-first valve; 205-second valve; 30-second generator; 206-first switching device; 207-third switching device; 208-fourth switching device; 209-sixth switching device; 210-fifth switching device; 211-seventh switching device. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present application, the following will make a more comprehensive description of the present application with reference to the related drawings. The embodiments of the present application are shown in the drawings. However, the present application can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0032] It is to be understood that the terms "first", "second", and etc. can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first resistor can be called a second resistor without departing from the scope of the present application, and similarly, a second resistor can be called a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0033] It is to be understood that "connection" in the following embodiments, if the circuits, modules, units, etc. connected to each other have the transmission of electrical signals or data, should be understood as "electrically connected", "communicatively connected", etc.

[0034] As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It is also to be understood that the term "comprising" or "including" or "having" or the like, as used herein, specifies the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0035] As shown in Figure 1 A structural schematic diagram of a coal-fired power unit is provided, the coal-fired power unit 10 includes a boiler 101, a high-pressure cylinder 102, a medium-pressure cylinder 103, a low-pressure cylinder 104, a condenser 105, a first feed water pump 106, a low-pressure heater 107, a deaerator 108, a second feed water pump 109, and a high-pressure heater 110. The main steam discharged from the boiler 101 enters the high-pressure cylinder 102, the exhaust steam of the high-pressure cylinder 102 enters the boiler 101 for reheating, the reheated steam enters the medium-pressure cylinder 103, the medium-pressure exhaust steam of the medium-pressure cylinder 103 enters the low-pressure cylinder 104, the exhaust steam of the low-pressure cylinder enters the condenser 105, the condensate water enters the low-pressure heater 107 and the deaerator 108 in turn through the first feed water pump 106, the condensate water of the deaerator 108 is pressurized by the second feed water pump 109 and enters the high-pressure heater 110, and finally returns to the boiler 101, thereby realizing the thermal cycle of the boiler. The power generated by the first generator 20 comes from the work of the high-pressure cylinder, the medium-pressure cylinder, and the low-pressure cylinder of the steam turbine. The condenser can also be replaced by an air cooling island.

[0036] However, when the unit is in a low load condition, the main steam pressure slides to a lower pressure, reducing the cycle efficiency of the unit and increasing the coal consumption for power supply. And in the future, with the continuous increase of new energy installed capacity and the development of new generation of coal-fired power, coal-fired power units need to continuously improve flexibility, and the running time under low load condition is increasing. Due to the decrease of total enthalpy drop, the decrease of feedwater temperature, the decrease of turbine efficiency and other reasons, the coal consumption of the unit increases. And under the low load condition, the steam required by the high-pressure cylinder of the steam turbine decreases. In order to match this demand change, the steam entering the high-pressure cylinder can be adjusted by throttling, but throttling will cause the main steam pressure to drop, so the pressure of the boiler main steam entering the high-pressure cylinder of the steam turbine decreases. Therefore, how to solve the problem of high coal consumption of coal-fired power units under low load condition, and the problem of peak regulation and frequency modulation of coal-fired power units, is the focus of attention of current coal-fired power units.

[0037] Based on this, the application can increase a back pressure turbine and / or a desuperheater, and a feedwater heater, the outlet of the back pressure turbine and / or the desuperheater is connected with the inlet of the feedwater heater, the back pressure turbine and / or the desuperheater is connected with the high-pressure cylinder of the steam turbine in parallel, the feedwater heater is arranged before the boiler feedwater side, and the feedwater is heated based on the feedwater heater. An adjusting valve can also be arranged between the boiler main steam outlet and the high-pressure cylinder of the steam turbine, the high-pressure parameter main steam is extracted to do work in the back pressure turbine, the generated power is used for auxiliary power, the exhaust steam of the back pressure turbine and / or the desuperheater enters the feedwater heater to heat the feedwater, and the feedwater temperature is increased, so that the coal consumption of the unit can be reduced.

[0038] As shown in Figure 2 , a structural diagram of a coal-fired power unit is provided, wherein the coal-fired power unit 10 comprises a boiler 101, a thermal cycle system 201, a unit load adjusting device 202 and a feedwater heater 203.

[0039] The first end of the boiler 101 is connected with the first end of the thermal cycle system 201, the second end of the thermal cycle system 201 is connected with the first input end of the feedwater heater 203, and the output end of the feedwater heater 203 is connected with the second end of the boiler 101; the input end of the unit load adjusting device 202 is connected with the first end of the boiler and the first end of the thermal cycle system 201, and the first output end of the unit load adjusting device 202 is connected with the second input end of the feedwater heater 203.

[0040] Based on Figure 2The structure shown sets a unit load adjusting device between the outlet of the boiler main steam and the inlet of the high-pressure cylinder, so that part of the boiler main steam can be extracted to enter the unit load adjusting device to do work under the low load condition of the unit, and further, the unit load adjusting device can exhaust steam into the feed water heater to heat the feed water based on the feed water heater, the temperature of the feed water is increased, so that the coal consumption of the unit can be reduced, further, the carbon consumption and carbon dioxide emission can be reduced, the fuel cost can be saved, and the realization of the double carbon target is helpful.

[0041] It should be understood that by setting the unit load adjusting device, the amount of steam entering the high-pressure cylinder is reduced, the power generation of the unit is reduced, the initial parameter of the thermal cycle of the coal-fired unit can be increased, that is, the main steam pressure and temperature, so that the unit reaches the original electric load, that is, under the same electric load, Figure 2 The coal-fired unit shown has a higher initial parameter of the thermal cycle than Figure 1 The initial parameter of the thermal cycle of the coal-fired unit shown is higher, so that the coal consumption can be further reduced.

[0042] It should be understood that increasing the initial parameter of the thermal cycle, that is, the main steam parameter, can improve the overall efficiency of the unit, but increasing the initial parameter of the thermal cycle will also cause the power generation to increase and the electric load to increase, so that the unit load cannot meet the power grid scheduling. Therefore, while improving the initial parameter of the cycle, the excess power needs to be utilized so that the power generation of the unit meets the power grid scheduling. Therefore, the unit load adjusting device is used to extract part of the main steam to generate power in the present application, the generated power is not connected to the grid, but only used for auxiliary power, which can reduce the auxiliary power rate. Moreover, the present application can improve the initial parameter of the cycle without affecting the power generation of the unit, and can also increase the feed water temperature, greatly reducing the coal consumption under the low load condition, and having wide load efficiency.

[0043] In one embodiment, the thermal cycle system 201 can include a high-pressure cylinder 102, a medium-pressure cylinder 103, a low-pressure cylinder 104, a condenser 105, a first feed water pump 106, a low-pressure heater 107, a deaerator 108, a second feed water pump 109, and a high-pressure heater 110.

[0044] The first end of the thermal cycle system 201 includes the first input end and the output end of the high-pressure cylinder 102, and the input end of the medium-pressure cylinder 103, the first end of the boiler 101 includes the first input end, the first output end and the second output end of the boiler 101, and the second end of the boiler 101 includes the second input end of the boiler 101. Wherein:

[0045] The first output end of the boiler 101 is connected with the first input end of the high-pressure cylinder 102, the output end of the high-pressure cylinder 102 is connected with the first input end of the boiler 101, and the second output end of the boiler 101 is connected with the input end of the medium-pressure cylinder 103. Thus, the main steam discharged from the boiler 101 enters the high-pressure cylinder 102, and the exhaust steam of the high-pressure cylinder 102 can enter the boiler 101 for reheating, and the reheated steam can enter the medium-pressure cylinder 103.

[0046] The second input end of the boiler is connected with the output end of the feedwater heater 203, so that the main steam from the boiler 101 returns to the boiler 101 for further heating after completing the thermodynamic cycle in the thermodynamic cycle system, and the circulating heating process of the coal-fired power unit can be realized.

[0047] In an embodiment, the coal-fired power unit 10 can further include a first valve arranged between the first output end of the boiler 101 and the input end of the unit load adjusting device 202, and a second valve arranged between the first output end of the boiler 101 and the first input end of the high-pressure cylinder 102, and the first valve and the second valve are connected in parallel. Thus, by controlling the opening and closing of the first valve and the second valve, the load adjustment of the coal-fired power unit can be realized.

[0048] In some cases, for basic operation conditions, for example, in the low load condition of the unit, that is, in the deep peak shaving condition, it is assumed that the required electric load of the unit is 20%, and the boiler load of the unit can be set to 25% by the unit. Specifically, by controlling the second valve to be opened, 20% of the steam can pass through the throttle to enter the high-pressure cylinder to do work, so as to meet the requirement of the electric load of 20% of the unit; by controlling the first valve to be opened, 5% of the steam can enter the unit load adjusting device to do work before throttling, and the exhaust steam enters the feedwater heater to heat the feedwater, so as to reduce the coal consumption.

[0049] In one case, for the load increasing condition, for example, the power plant receives the instruction of the power grid, and the unit needs to increase the load, and the instruction of the power grid is that the electric load is 30%. It is assumed that the original electric load of the unit is 20%, and the boiler load is 25% when the unit is stably operated at the electric load of 20%, and the electric load is 20%, and 5% of the steam enters the unit load adjusting device to do work. After receiving the instruction of the power grid indicating that the unit needs to increase the load, the boiler can immediately perform the load increasing operation, specifically by controlling the first valve to be closed, the steam extraction pipeline for passing the main steam into the unit load adjusting device is disconnected, so that 25% of the steam of the boiler enters the high-pressure cylinder to do work, so that the unit rapidly increases the load to 25%, and then rapidly increases the load to 30%.

[0050] In one case, for the load reduction condition, for example, the power plant receives a grid instruction, the unit needs to reduce the load, assuming that the original unit electric load is 30%, and the grid instruction electric load is 20%. When the unit is stably running at an electric load of 30%, the boiler load is 30% and the electric load is 30%. After the unit receives the grid instruction indicating load reduction, the boiler can immediately perform load reduction operation, specifically by controlling the first valve to open to connect the main steam to the steam extraction pipeline of the unit load adjusting device, so that part of the main steam at the outlet of the boiler enters the unit load adjusting device to do work, reducing the amount of steam entering the high-pressure cylinder of the steam turbine, reducing the work of the steam turbine, and rapidly reducing the unit load to 25%, and subsequently continuing to rapidly reduce the load to 20%.

[0051] In one embodiment, the unit load adjusting device 202 can include a back pressure turbine or a desuperheater and pressure reducer. The type of back pressure turbine is not limited.

[0052] In one embodiment, the second output end of the unit load adjusting device 202 includes the second output end of the back pressure turbine, and the second output end of the back pressure turbine is connected to the second generator. Thus, the main steam before throttling enters the back pressure turbine to do work, and the generated power is used for auxiliary power, that is, because the main steam before throttling is extracted, the main steam throttling is reduced, thereby improving the utilization rate of steam. In some embodiments, the input end of the back pressure turbine is connected to the first output end of the boiler and the first input end of the high-pressure cylinder, and the first output end of the back pressure turbine is connected to the second input end of the feedwater heater.

[0053] Taking the back pressure turbine as an example of the unit load adjusting device, as shown in Figure 3 , a structural schematic diagram of a coal-fired unit is provided. The coal-fired unit 10 can further include a back pressure turbine 2021, a feedwater heater 203, a first valve 204 arranged between the first output end of the boiler 101 and the first input end of the back pressure turbine 2021, and a second valve 205 arranged between the first output end of the boiler 101 and the first input end of the high-pressure cylinder 102; the first valve 204 and the second valve 205 are connected in parallel, the first output end of the back pressure turbine 2021 is connected to the second input end of the feedwater heater 203, and the second output end of the back pressure turbine 2021 is connected to the second generator 30.

[0054] Based on the structure shown in Figure 3 , on the one hand, by controlling the first valve 204 and the second valve 205, variable load adjustment of the coal-fired unit can be achieved; on the other hand, by connecting the second output end of the back pressure turbine 2021 to the second generator 30, after the boiler main steam enters the back pressure turbine to do work, the generated power can also be used for auxiliary power, and the back pressure turbine can exhaust steam into the feedwater heater for heating the feedwater, the temperature of the feedwater is increased, and the coal consumption of the unit can be reduced.

[0055] As shown in FIG. 1, a structural schematic diagram of a coal-fired power unit is provided. The coal-fired power unit 10 can further include a desuperheater 2022, a feedwater heater 203, a first valve 204 arranged at the first output end of the boiler 101 and the input end of the desuperheater 2022, and a second valve 205 arranged between the first output end of the boiler 101 and the first input end of the high-pressure cylinder 102, and the first valve 204 and the second valve 205 are connected in parallel. Thus, the main steam is extracted from the desuperheater to heat the feedwater in the feedwater heater, and the coal consumption of the unit can be reduced by increasing the temperature of the feedwater. Figure 4

[0056] In an embodiment, the coal-fired power unit 10 can further include a steam parameter detection device, and the thermodynamic cycle system 201 includes a cold-end device, which refers to a device for cooling and condensing working medium (such as steam or refrigerant), and its main function is to remove heat from the working medium to condense or cool it, thereby maintaining the efficient operation of the system.

[0057] The cold-end device can include a condenser or an air cooling island. The condenser is used to condense the steam discharged from the steam turbine into water to re-enter the boiler cycle; the air cooling island is used to cool the steam by air.

[0058] The steam parameter detection device is arranged at the first output end of the unit load regulation device 202, and the first output end of the unit load regulation device 202 is further connected with the cold-end device.

[0059] Specifically, the steam parameter detection device is used to detect the steam parameters, such as the steam pressure and / or the steam temperature, after passing through the unit load regulation device 202. In the case that the steam parameters are less than or equal to the preset parameters, it indicates that the exhaust steam from the unit load regulation device cannot heat the feedwater, therefore, the pipeline communication between the unit load regulation device and the cold-end device is controlled to deliver the exhaust steam from the unit load regulation device to the cold-end device, and the pipeline disconnection between the unit load regulation device and the feedwater heater is controlled to prevent the exhaust steam from the unit load regulation device from being delivered to the feedwater heater, and the steam parameter detection device is re-controlled to obtain new steam parameters in real time. In the case that the new steam parameters are greater than the preset parameters, it indicates that the exhaust steam from the unit load regulation device can heat the feedwater, therefore, the pipeline disconnection between the unit load regulation device and the cold-end device is controlled, and the pipeline communication between the unit load regulation device and the feedwater heater is controlled, so that the exhaust steam from the unit load regulation device can be delivered to the feedwater heater, and the feedwater is heated based on the delivered exhaust steam, thereby the heating efficiency can be improved.

[0060] ​It should be understood that, in the process of starting the unit, the steam from the unit load adjusting device is not high in pressure and temperature, and thus steam can not be delivered to the feedwater heater; when the steam pressure and / or temperature reaches the requirement, the feedwater heater can be quickly heated by delivering steam to the feedwater heater, and the feedwater heating efficiency can be improved.

[0061] In one of the embodiments, the coal-fired unit 10 further comprises a first switching device; the first output end of the unit load adjusting device 202 is connected with the cold end device through the first switching device. Thus, by controlling the opening and closing of the first switching device, the conduction or disconnection of the pipeline between the unit load adjusting device 202 and the cold end device can be accurately controlled, and the control accuracy is improved.

[0062] In one of the embodiments, the coal-fired unit 10 further comprises a second switching device; the second switching device is arranged at the second input end of the feedwater heater 203. Thus, by controlling the opening and closing of the second switching device, the conduction or disconnection of the pipeline between the unit load adjusting device 202 and the feedwater heater 203 can be accurately controlled, and the control accuracy is improved.

[0063] In one of the embodiments, the coal-fired unit 10 can further comprise a steam amount detecting device; the thermal cycle system 201 comprises a high-pressure cylinder 102, the first end of the thermal cycle system 201 comprises a first input end of the high-pressure cylinder, and the steam amount detecting device is arranged at the first input end of the high-pressure cylinder; the input end of the unit load adjusting device 202 is connected with the first end of the boiler and the first input end of the high-pressure cylinder; and the first output end of the unit load adjusting device is further connected with the second input end of the high-pressure cylinder.

[0064] Specifically, the steam amount detecting device is used to detect the main steam amount entering the high-pressure cylinder; when the main steam amount is less than a preset steam amount, the pipeline between the unit load adjusting device 202 and the high-pressure cylinder is conducted, so that when the main steam amount entering the high-pressure cylinder is less than the preset steam amount, the high-pressure cylinder can be supplemented by the steam from the unit load adjusting device 202, so as to improve the thermal cycle efficiency of the coal-fired unit. In other cases, when the main steam amount entering the high-pressure cylinder is less than the preset steam amount, the main steam amount entering the back-pressure turbine and / or the desuperheater can be adjusted, so as to increase the main steam amount entering the high-pressure cylinder.

[0065] In one of the embodiments, the coal-fired unit 10 further comprises a third switching device; the first output end of the unit load adjusting device 202 is connected with the second input end of the high-pressure cylinder 102 through the third switching device. Thus, by controlling the opening and closing of the third switching device, the conduction or disconnection of the pipeline between the unit load adjusting device 202 and the high-pressure cylinder 10 can be accurately controlled, and the control accuracy is improved.

[0066] In one embodiment, the unit load regulating device 202 can include a back pressure turbine and an attemperator connected in parallel. Thus, in the case of simultaneous activation of the back pressure turbine and the attemperator, on the one hand, more main steam can be consumed, and the main steam parameters (i.e. the initial parameters of the thermodynamic cycle) can be further improved; on the other hand, the load regulating efficiency can be improved when regulating the unit load.

[0067] In some cases, in the case of simultaneous activation of the back pressure turbine and the attemperator, the main steam is preferentially fed into the back pressure turbine for work. In other cases, in the case of simultaneous activation of the back pressure turbine and the attemperator, the amount of steam fed into the back pressure turbine is greater than the amount of steam fed into the attemperator.

[0068] In one embodiment, the coal-fired unit 10 further includes a fourth switch device and a fifth switch device connected in parallel, and the input end of the unit load regulating device 202 includes the input end of the back pressure turbine and the input end of the attemperator. The input end of the back pressure turbine is connected to the first end of the boiler 101 and the first end of the thermodynamic cycle system 201 through the fourth switch device; the input end of the attemperator is connected to the first end of the boiler 101 and the first end of the thermodynamic cycle system 201 through the fifth switch device. Thus, the fourth switch device can accurately control the on-off of the pipeline through which the boiler main steam enters the back pressure turbine, and the fifth switch device can accurately control the on-off of the pipeline through which the boiler main steam enters the attemperator, thereby improving the control accuracy.

[0069] In some cases, the first end of the boiler 101 includes a first output end of the boiler 101, the input end of the unit load regulating device 202 includes a first input end of the high-pressure cylinder, the input end of the back pressure turbine is connected to the first output end of the boiler 101 and the first input end of the high-pressure cylinder through the fourth switch device, and the input end of the attemperator is connected to the first output end of the boiler 101 and the first input end of the high-pressure cylinder through the fifth switch device.

[0070] In some cases, the first output end of the back pressure turbine is connected to a second input end of a feedwater heater, and the second output end of the back pressure turbine is connected to a second generator. Thus, the main steam enters the back pressure turbine for work, and the generated power can be used for auxiliary power. The back pressure turbine can exhaust steam into the feedwater heater to heat the feedwater. By increasing the feedwater temperature, the coal consumption of the unit can be reduced.

[0071] In one embodiment, the coal-fired power unit 10 may further include a sixth switching device and a seventh switching device, which are connected in parallel. The first output terminal of the unit load regulating device 202 includes the first output terminal of the back pressure compressor and the output terminal of the desuperheater / pressure reducer. The first output terminal of the back pressure compressor is connected to the second input terminal of the feedwater heater via the sixth switching device; the output terminal of the desuperheater / pressure reducer is connected to the second input terminal of the feedwater heater via the seventh switching device. Therefore, when the fourth and fifth switching devices malfunction, the sixth switching device can precisely control the on / off state of the pipeline from the boiler main steam to the back pressure compressor, and the seventh switching device can precisely control the on / off state of the pipeline from the boiler main steam to the desuperheater / pressure reducer, further improving control accuracy.

[0072] Taking the unit load regulating devices, including the back compressor and desuperheater / pressure reducer, and the cold-end devices, including the condenser, as an example, in Figure 1 Based on what is shown, as Figure 5 The diagram illustrates the structure of a coal-fired power unit. The coal-fired power unit 10 may further include a back pressure compressor 2021, a desuperheater and pressure reducer 2022 connected in parallel with the back pressure compressor 2021, a feedwater heater 203, a second valve 205 located between the first output end of the boiler 101 and the first input end of the high-pressure cylinder 102, a first switching device 206 located between the first output end of the back pressure compressor 2021, the output end of the desuperheater and pressure reducer 2022, and the condenser 105, a second switching device (not shown) located at the second input end of the feedwater heater 203, and a valve located between the first output end of the back pressure compressor 2021 and the desuperheater and pressure reducer 2022. A third switching device 207 is configured between the output terminal of boiler 101 and the second input terminal of back pressure unit 2021; a fourth switching device 208 is configured between the first output terminal of boiler 101 and the input terminal of back pressure unit 2021; a sixth switching device 209 is configured between the first output terminal of back pressure unit 2021 and the second input terminal of feedwater heater 203; a fifth switching device 210 is configured between the first output terminal of boiler 101 and the input terminal of desuperheater / pressure reducer 2022; and a seventh switching device 211 is configured between the output terminal of desuperheater / pressure reducer 2022 and the second input terminal of feedwater heater 203. The fourth switching device 208 and the fifth switching device 210 are connected in parallel, and the sixth switching device 209 and the seventh switching device 211 are connected in parallel.

[0073] based on Figure 5 The structure shown allows for the activation of desuperheaters and / or back pressure generators as needed to regulate the load of the coal-fired power unit. Furthermore, the exhaust steam from the desuperheaters and / or back pressure generators can be delivered to the feedwater heater, which heats the feedwater, thereby reducing coal consumption by increasing the feedwater temperature.

[0074] From the above, the coal power unit provided by the application can improve the initial parameters of the thermal cycle at low and medium loads, for example, the main steam pressure of a unit designed at 20% load is 8.2 MPa, and the main steam pressure of the unit at 20% load can be increased to 8.6 MPa by the application, thereby improving the thermal cycle efficiency of the unit at low and medium loads.

[0075] Further, the application can ensure deep load adjustment of the unit by setting the back pressure turbine and / or the desuperheater, and part of the main steam can enter the back pressure turbine and / or the desuperheater, thereby improving the steam utilization rate.

[0076] Further, the application can reduce the throttling loss of part of the main steam by extracting part of the main steam to the back pressure turbine and / or the desuperheater, thereby reducing the coal consumption of the unit.

[0077] Further, the application can generate power by the back pressure turbine using the main steam and supply the power to the auxiliary power of the plant.

[0078] Further, the application can quickly increase the load of the unit by closing the switch device before the back pressure turbine and / or the desuperheater, and quickly decrease the load of the unit by opening the switch device before the back pressure turbine and / or the desuperheater, thereby improving the load change rate of the unit.

[0079] It should be understood that the application uses part of the main steam by the back pressure turbine and / or the desuperheater, reduces the throttling loss of the unit, recycles and utilizes the energy of the lost main steam, uses the energy of the main steam, improves the energy utilization rate, and extracts the main steam by the back pressure turbine to assist the flexible adjustment of the unit when the unit is used for peak shaving and frequency modulation.

[0080] The technical features of the above-described embodiments can be combined in any manner, and to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present application.

[0081] The above-described embodiments only express several implementation manners of the utility model, the description is more specific and detailed, but can not therefore be understood as the limitation of the utility model patent range. It should be pointed out that for ordinary skilled person in the art, without departing from the utility model concept, several modifications and improvements can be made, which belong to the protection range of the utility model. Therefore, the protection range of the utility model patent should be subject to the appended claims.

Claims

1. A coal-fired power plant, characterized by, The coal power unit comprises a boiler, a thermal cycle system, a unit load regulating device and a feedwater heater; a first end of the boiler is connected with a first end of the thermal cycle system, a second end of the thermal cycle system is connected with a first input end of the feedwater heater, and an output end of the feedwater heater is connected with a second end of the boiler; an input end of the unit load regulating device is connected with the first end of the boiler and the first end of the thermal cycle system, and a first output end of the unit load regulating device is connected with a second input end of the feedwater heater.

2. The coal-fired power plant of claim 1, wherein, The coal power unit further comprises a steam parameter detecting device, and the thermal cycle system comprises a cold end device; the steam parameter detecting device is arranged at the first output end of the unit load regulating device; the first output end of the unit load regulating device is further connected with the cold end device.

3. The coal-fired power plant of claim 1, wherein, The coal power unit further comprises a steam quantity detecting device, the thermal cycle system comprises a high-pressure cylinder, the first end of the thermal cycle system comprises a first input end of the high-pressure cylinder, and the steam quantity detecting device is arranged at the first input end of the high-pressure cylinder; an input end of the unit load regulating device is connected with the first end of the boiler and the first input end of the high-pressure cylinder, and a first output end of the unit load regulating device is further connected with a second input end of the high-pressure cylinder.

4. The coal-fired power plant of claim 1, wherein, The unit load regulating device comprises a back pressure turbine, and a second output end of the unit load regulating device comprises a second output end of the back pressure turbine, which is connected with a second generator.

5. The coal-fired power plant of claim 1, wherein, The unit load regulating device comprises a desuperheater and pressure reducer.

6. The coal-fired power plant of claim 1, wherein, The unit load regulating device comprises a back pressure turbine and a desuperheater, and the back pressure turbine and the desuperheater are connected in parallel.

7. The coal-fired power plant of claim 2, wherein, The coal power unit further comprises a first switch device, and the first output end of the unit load regulating device is connected with the cold end device through the first switch device.

8. The coal-fired power plant of claim 7, wherein, The coal power unit further comprises a second switch device, and the second switch device is arranged at the second input end of the feedwater heater.

9. The coal-fired power plant of claim 3, wherein, The coal power unit further comprises a third switch device, and the first output end of the unit load regulating device is connected with the second input end of the high-pressure cylinder through the third switch device.

10. The coal-fired power plant of claim 6, wherein, The coal power unit further comprises a fourth switch device and a fifth switch device, the fourth switch device and the fifth switch device are connected in parallel, and an input end of the unit load regulating device comprises an input end of the back pressure turbine and an input end of the desuperheater; the input end of the back pressure turbine is connected with the first end of the boiler and the first end of the thermal cycle system through the fourth switch device, and the input end of the desuperheater is connected with the first end of the boiler and the first end of the thermal cycle system through the fifth switch device.

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