Water supply pump set and thermal power unit

Abstract

The present disclosure relates to a feed water pump unit and a thermal power generating unit, and relates to the technical field of power systems, and can realize flexible switching of steam driving and electric driving of the feed water pump, thereby improving the driving efficiency of the feed water pump. The feed water pump unit comprises a small steam turbine, a motor generator and a feed water pump, the steam inlet of the small steam turbine is externally connected to the medium pressure cylinder and the low pressure cylinder of the main steam turbine through a steam pipeline, the steam outlet of the small steam turbine is externally connected to a condenser, and the small steam turbine, the motor generator and the feed water pump are coaxially connected. The small steam turbine is used for switching to a target steam extraction mode according to the unit load of the main steam turbine, and in the case that the power in the target steam extraction mode is greater than the power of the feed water pump, steam is supplied to the feed water pump to drive the feed water pump to operate. The motor generator is used for generating power in the case that the power of the small steam turbine in the target steam extraction mode is less than or equal to the power of the feed water pump, and the small steam turbine supplies steam to the feed water pump to drive the feed water pump to operate.

Description

Technical Field

[0001] This disclosure relates to the field of power system technology, specifically to a water supply pump set and a thermal power unit. Background Technology

[0002] In related technologies, feedwater pump sets in thermal power units can be driven by a dual steam-electric drive. However, when feedwater pumps are driven by a dual steam-electric drive, it is impossible to flexibly switch between the generator's power generation and power consumption modes. This results in low efficiency and low reliability of feedwater pump drive under deep peak shaving conditions in thermal power units, affecting the safe operation of the main steam turbine in thermal power units. Utility Model Content

[0003] To address the shortcomings of related technologies, this disclosure provides a water supply pump unit and a thermal power unit.

[0004] To achieve the above objectives, in a first aspect, this disclosure provides a feedwater pump set, comprising: a small steam turbine, an electric generator, and a feedwater pump, wherein the steam inlet of the small steam turbine is externally connected to the intermediate-pressure cylinder and low-pressure cylinder of the main steam turbine through a steam pipe, the steam outlet of the small steam turbine is externally connected to a condenser, and the small steam turbine, the electric generator, and the feedwater pump are coaxially connected. The small steam turbine is used to switch to the target extraction mode according to the unit load of the main steam turbine, and to supply steam to the feedwater pump when the power of the target extraction mode is greater than the power of the feedwater pump, so as to drive the feedwater pump to operate. The electric generator is used to generate electricity when the power of the small steam turbine under the target steam extraction mode is less than the power of the feedwater pump, and the small steam turbine supplies steam to the feedwater pump to drive the feedwater pump.

[0005] Optionally, the small steam turbine, the electric generator, and the feedwater pump are arranged in series, the small steam turbine is coaxially connected to the electric generator via a coupling, and the electric generator is coaxially connected to the feedwater pump via a coupling. The electric generator is equipped with a frequency converter, and the small steam turbine, the electric generator, and the water pump operate at the same speed.

[0006] Optionally, the water pump, the small steam turbine, and the electric generator are arranged in series, the water pump is coaxially connected to the small steam turbine via a coupling, and the small steam turbine is coaxially connected to the electric generator via a coupling. The electric generator is equipped with a frequency converter and the electric generator has a variable speed.

[0007] Optionally, the electric generator, the feedwater pump, and the small steam turbine are arranged in series, the electric generator is coaxially connected to the feedwater pump via a coupling, and the feedwater pump is coaxially connected to the small steam turbine via a coupling. The electric generator is equipped with a frequency converter, and the electric generator, the water pump, and the small steam turbine operate at the same speed.

[0008] Optionally, it also includes a speed-changing gearbox, wherein the small steam turbine, the electric generator, the speed-changing gearbox and the feedwater pump are arranged in series, the small steam turbine is coaxially connected to the electric generator through a coupling, and the electric generator is coaxially connected to the feedwater pump through the speed-changing gearbox; The electric generator is equipped with a frequency converter and operates at a constant speed.

[0009] Optionally, it also includes a speed-changing gearbox, wherein the electric generator, the speed-changing gearbox, the small steam turbine and the feedwater pump are arranged in series, the electric generator is coaxially connected to the small steam turbine through the speed-changing gearbox, and the small steam turbine is coaxially connected to the feedwater pump through a coupling; Both the electric generator and the gearbox operate at a constant speed.

[0010] Optionally, it also includes a variable speed gearbox, wherein the small steam turbine, the feedwater pump, the variable speed gearbox and the electric generator are arranged in series, the small steam turbine is coaxially connected to the feedwater pump through a coupling, the feedwater pump is coaxially connected to the electric generator through the variable speed gearbox, and the electric generator operates at a constant speed.

[0011] Optionally, it also includes a gearbox and a transmission. The small steam turbine, the gearbox, the electric generator, the transmission, and the feedwater pump are arranged in series. The small steam turbine is coaxially connected to the electric generator through the gearbox, and the electric generator is coaxially connected to the feedwater pump through the transmission. The electric generator operates at a constant speed.

[0012] Optionally, the length of the final blade of the low-pressure cylinder in the small steam turbine ranges from 500mm to 800mm.

[0013] Secondly, this disclosure provides a thermal power unit including the feedwater pump unit described in the first aspect.

[0014] The above technical solution allows for switching the extraction mode of the small steam turbine based on the unit load of the main steam turbine, thereby maximizing the efficiency of the feedwater pump set and improving the operating efficiency of the main unit. Furthermore, by flexibly switching between the small steam turbine and the feedwater pump's power based on their relative power, the feedwater pump can be driven by either the small steam turbine or an electric generator. This enables flexible switching between steam-driven, electric-driven, and mixed steam-electric drive of the feedwater pump, thereby improving its driving efficiency. The switching method is also simple, enhancing the reliability of the dual steam-electric drive system for the feedwater pump and the power generation efficiency of the main unit to which the feedwater pump set belongs.

[0015] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of a water supply pump unit according to an exemplary embodiment of the present disclosure.

[0017] Figure 2 This is another schematic diagram of a water supply pump unit according to an exemplary embodiment of the present disclosure.

[0018] Figure 3 This is another schematic diagram of a water supply pump unit shown according to an exemplary embodiment of the present disclosure.

[0019] Figure 4 This is another schematic diagram of a water supply pump unit according to an exemplary embodiment of the present disclosure.

[0020] Figure 5 This is another schematic diagram of a water supply pump unit shown according to an exemplary embodiment of the present disclosure.

[0021] Figure 6 This is another schematic diagram of a water supply pump assembly shown according to an exemplary embodiment of the present disclosure.

[0022] Figure 7 This is yet another schematic diagram of a water pump assembly shown according to an exemplary embodiment of the present disclosure.

[0023] Figure 8 This is another schematic diagram of a water pump assembly shown according to an exemplary embodiment of the present disclosure.

[0024] Figure 9 This is a control flowchart of a water supply pump unit according to an exemplary embodiment of the present disclosure.

[0025] Explanation of reference numerals in the attached figures 1. Small steam turbine, 2. Electric motor, 3. Water pump, 4. Coupling, 5. Frequency converter, 6. Gearbox, 7. Gearbox, 8. Transmission. Detailed Implementation

[0026] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0027] It should be noted that all actions involving the acquisition of signals, information, or data in this disclosure are carried out in compliance with the relevant data protection laws and policies of the country where the location is situated, and with authorization from the owner of the relevant device.

[0028] It should be understood that with the accelerated construction of new power systems, deep peak-shaving operation of thermal power units has become a routine requirement. Statistics show that peak-shaving in thermal power plants became more frequent in 2024, placing higher demands on key auxiliary equipment. In related technologies, invention patent publication number "CN104373158B" discloses a novel boiler-driven steam turbine unit, including a steam turbine, a feedwater pump, and a hydraulic planetary gear composite transmission device. The steam turbine is equipped with a steam turbine generator main shaft, and the steam turbine drives the feedwater pump through the hydraulic planetary gear composite transmission device. The feedwater pump is connected to the boiler. Under varying operating conditions, feedwater efficiency is improved; specifically, under varying operating conditions, the efficiency of the feedwater pump driven by the hydraulic planetary gear composite transmission device is greater than the efficiency of the feedwater pump driven by a hydraulic coupling, thus improving feedwater efficiency.

[0029] The invention patent with publication number "CN102865232A" discloses an energy-saving system for an electric feedwater pump using a hydraulic coupling with a variable frequency drive (VFD) switching mechanism. This system maintains the original connection method of the electric feedwater pump group by configuring a VFD and a power frequency bypass between the power circuit breaker and the electric generator. The VFD and its power frequency bypass are installed between the power circuit breaker and the motor. By switching, the VFD power supply is input to the electric generator. One end of the electric generator coaxially drives the pre-pump, and the other end coaxially drives the input shaft of the hydraulic coupling. The output shaft of the hydraulic coupling drives the feedwater pump. A lubricating oil pump and a working oil pump are designed and installed in the hydraulic coupling's lubrication and working oil systems, allowing the same hydraulic coupling to have two operating modes. The pre-pump, to meet the VFD operation requirements of the feedwater pump group, is modified to allow for both constant-speed and variable-speed operation.

[0030] The inventors discovered that in the relevant technologies, when the feedwater pump in a thermal power unit is driven by a dual steam-electric drive, it is impossible to flexibly switch between the two modes of power generation and power consumption. This results in low efficiency and low reliability of the feedwater pump drive under deep peak shaving conditions in the thermal power unit, affecting the safe operation of the main steam turbine in the thermal power unit.

[0031] In view of this, the present disclosure provides a water supply pump set and a thermal power unit, which can achieve flexible switching between steam-driven, electric-driven and mixed-drive water supply pumps while ensuring the highest efficiency of the water supply pump set.

[0032] Figure 1 This is a schematic diagram of a water supply pump set according to an exemplary embodiment of the present disclosure, such as... Figure 1 As shown, the feedwater pump set includes: a small steam turbine 1, a motor 2, and a feedwater pump 3. The steam inlet of the small steam turbine 1 is connected to the intermediate-pressure cylinder and low-pressure cylinder of the main steam turbine through a steam pipe. The steam outlet of the small steam turbine 1 is connected to a condenser. The small steam turbine 1, the electric generator 2, and the feedwater pump 3 are coaxially connected. The small steam turbine 1 is used to switch to the target extraction mode according to the unit load of the main steam turbine, and to supply steam to the feedwater pump 3 when the power of the target extraction mode is greater than the power of the feedwater pump 3, so as to drive the feedwater pump 3 to operate. The electric generator 2 is used to generate electricity when the power of the small steam turbine 1 under the target steam extraction mode is less than or equal to the power of the feedwater pump 3, and the small steam turbine 1 supplies steam 3 to the feedwater pump to drive the feedwater pump 3 to operate.

[0033] It is worth noting that the steam inlet of the small steam turbine 1 is connected to an external steam extraction system via a steam pipeline. The steam extraction system includes, but is not limited to, the intermediate-pressure cylinder, low-pressure cylinder, and high-pressure cylinder of the main steam turbine, as well as the reheater. This means that the steam extraction methods of the small steam turbine include, but are not limited to, intermediate-pressure cylinder extraction, low-pressure cylinder extraction, and reheater cold-end extraction.

[0034] In this embodiment, in the feedwater pump group, the power of the small turbine is equal to the sum of the power of the motor and the power of the feedwater pump. Therefore, when the power of the small turbine is greater than the power of the feedwater pump, the feedwater pump is driven by the small turbine, and the electric generator can consume electricity as an electric motor. When the power of the small turbine is less than or equal to the power of the feedwater pump, the electric generator can generate electricity as a generator, and the small turbine supplies steam to the feedwater pump. The feedwater pump is driven by both the electric generator and the small turbine, and the small turbine or the motor can be flexibly switched to drive the feedwater pump. The motor can also flexibly switch between generating and consuming electricity, realizing flexible switching between steam-driven, electric-driven, and steam-electric hybrid drive of the feedwater pump, thereby improving the driving efficiency of the feedwater pump and the power generation efficiency of the main unit to which the feedwater pump group belongs.

[0035] The above technical solution achieves the highest efficiency of the feedwater pump set by switching the extraction mode of the small steam turbine according to the unit load of the main steam turbine. Furthermore, based on the power ratio between the small steam turbine and the feedwater pump, the feedwater pump can be flexibly switched between being driven by the small steam turbine or an electric generator. This allows for flexible switching between steam-driven, electric-driven, and dual-drive feedwater pumps, thereby improving the driving efficiency of the feedwater pump and the power generation efficiency of the main unit to which the feedwater pump set belongs. The switching method is also simple, enhancing the reliability of the dual-drive feedwater pump system.

[0036] To facilitate a better understanding of the water supply pump set provided in this disclosure by those skilled in the art, the water supply pump set will be described in detail below.

[0037] In one feasible embodiment, the length of the final blade of the low-pressure cylinder in the small steam turbine ranges from 500mm to 800mm.

[0038] It is worth noting that, in order to adapt to deep peak shaving, the blades of the low-pressure cylinder of the small steam turbine are selected with a length range of 500mm to 800mm to ensure that the efficiency of the feedwater pump set is the highest when the unit load is within the preset load range. The preset load range can be preset according to the peak shaving requirements or according to the actual operating parameters of the feedwater pump set. In this disclosure, the preset load range is taken as [45%, 75%]THA.

[0039] In one feasible embodiment, such as Figure 2 As shown, the small steam turbine 1, the electric generator 2, and the feedwater pump 3 are arranged in series. The small steam turbine 1 is coaxially connected to the electric generator 2 through a coupling 4, and the electric generator 2 is coaxially connected to the feedwater pump 3 through a coupling 4. The electric generator 2 is equipped with a frequency converter 5, and the small steam turbine 1, the electric generator 2, and the water pump 3 operate at the same speed.

[0040] In the aforementioned technical solution, when the small steam turbine controls its speed by adjusting the steam intake, energy loss occurs due to valve throttling. However, when the small steam turbine, electric generator, and feedwater pump operate at the same speed, the feedwater pump speed can be controlled by a frequency converter configured with the motor, thus avoiding valve throttling losses and significantly improving the operating efficiency of the feedwater pump unit. Furthermore, when the small steam turbine, electric generator, and feedwater pump operate at the same speed, the valve at the steam inlet of the small steam turbine can be kept at a large opening or even fully open, allowing for more efficient utilization of the steam's work capacity, thereby improving the operating efficiency of the small steam turbine.

[0041] In one feasible embodiment, such as Figure 3As shown, the water pump 3, the small steam turbine 1, and the electric generator 2 are arranged in series. The water pump 3 is coaxially connected to the small steam turbine 1 through a coupling 4, and the small steam turbine 1 is coaxially connected to the electric generator 2 through a coupling 4. The electric generator 2 is equipped with a frequency converter 5, and the electric generator 2 operates at variable speed.

[0042] In the above technical solution, the feedwater pump, small steam turbine, and electric generator are arranged coaxially in sequence, with the motor operating at variable speed. When the small steam turbine has a reliable steam source, the motor can switch to no-load or generator mode, allowing the small steam turbine to drive the feedwater pump independently. In this case, the motor operates as a generator, converting the surplus power of the small steam turbine into electrical energy, which is fed back into the plant power system, achieving pure steam drive. When the small steam turbine lacks a reliable steam source or requires maintenance, the motor can switch to electric mode, driving the feedwater pump independently to ensure stable operation and achieve pure electric drive. Under certain operating conditions, the small steam turbine and motor can jointly drive the feedwater pump. Through the motor's variable speed control function, the pump's speed can be precisely controlled to adapt to different load requirements, achieving combined steam and electric drive.

[0043] In one feasible embodiment, such as Figure 4 As shown, the electric generator 2, the water pump 3, and the small steam turbine 1 are arranged in series. The electric generator 2 is coaxially connected to the water pump 3 through a coupling 4, and the water pump 3 is coaxially connected to the small steam turbine 1 through a coupling 4. The electric generator 2 is equipped with a frequency converter 5, and the electric generator 2, the water pump 3, and the small steam turbine 1 operate at the same speed.

[0044] In the above technical solution, the motor speed can be quickly adjusted by a frequency converter, thereby rapidly responding to load changes. For example, when the unit load suddenly increases, the frequency converter can quickly increase the motor speed, increasing the feedwater pump flow rate to meet the boiler's feedwater requirements. This improves the regulation performance and stability of the feedwater pump set. On the other hand, in traditional feedwater pump systems, the steam inlet valve of the small steam turbine needs frequent adjustment, resulting in significant throttling losses. However, by using frequency converter speed regulation for the motor, the speed of the electric generator can be precisely controlled by the frequency converter, avoiding valve throttling losses and significantly improving the system's operating efficiency.

[0045] In one feasible embodiment, such as Figure 5 As shown, it also includes a speed change gearbox 6. The small steam turbine 1, the electric generator 2, the speed change gearbox 6 and the water pump 3 are arranged in series. The small steam turbine 1 is coaxially connected to the electric generator 2 through a coupling 4. The electric generator 2 is coaxially connected to the water pump 3 through the speed change gearbox 6. The electric generator 2 is equipped with a frequency converter 5, and the electric generator operates at a constant speed.

[0046] In the above technical solution, the speed of the feedwater pump can be quickly adjusted according to load changes via a variable speed gearbox. For example, when the unit load suddenly increases, the variable speed gearbox can rapidly adjust the feedwater pump speed to increase the flow rate and meet the boiler's feedwater requirements. Furthermore, the variable speed gearbox can precisely control the speed to smoothly and quickly adjust the feedwater pump speed, avoiding fluctuations in feedwater pump speed caused by steam parameter fluctuations or untimely valve adjustments, thus improving the operational stability of the feedwater pump. It also reduces throttling losses and operating load, lowers equipment wear and fatigue, and thereby extends the service life of equipment such as the small steam turbine, motor, and feedwater pump.

[0047] In one feasible embodiment, such as Figure 6 As shown, it also includes a speed change gearbox 6. The electric generator 2, the speed change gearbox 6, the small steam turbine 1 and the water pump 3 are arranged in series. The electric generator 2 is coaxially connected to the small steam turbine 1 through the speed change gearbox 6. The small steam turbine 1 is coaxially connected to the water pump 3 through a coupling 4. Both the electric generator 2 and the gearbox 6 operate at a constant speed.

[0048] In the above technical solution, the electric generator and the gearbox operate at a constant speed. The electric generator's rotational speed remains constant, providing a stable power input to downstream equipment. The constant-speed operation of the gearbox ensures stable output speed, allowing the small steam turbine and feedwater pump to operate in a relatively stable speed environment. This stable speed transmission method reduces equipment vibration and wear problems that may be caused by speed fluctuations.

[0049] In one feasible embodiment, such as Figure 7 As shown, it also includes a speed change gearbox 6. The small steam turbine 1, the feedwater pump 3, the speed change gearbox 6 and the electric generator 2 are arranged in series. The small steam turbine 1 is coaxially connected to the feedwater pump 3 through a coupling 4. The feedwater pump 3 is coaxially connected to the electric generator 2 through the speed change gearbox 6. The electric generator 2 operates at a constant speed.

[0050] In the above technical solution, the small steam turbine, feedwater pump, gearbox, and motor are arranged coaxially in series, resulting in a short power transmission path and reducing energy loss caused by excessively long drive shafts or too many transmission links. Furthermore, the compact coaxial arrangement makes power transmission more direct, reducing energy conversion losses in intermediate links, improving transmission efficiency, and minimizing energy loss. On the other hand, the electric generator operates at a constant speed, and the gearbox allows for precise control of the feedwater pump's speed, ensuring it operates under optimal conditions. This stable speed control method avoids unstable fluid flow within the pump caused by speed fluctuations, thereby reducing pump vibration and wear.

[0051] In one feasible embodiment, such as Figure 8 As shown, it also includes a gearbox 7 and a transmission 8. The small steam turbine 1, the gearbox 7, the electric generator 2, the transmission 8, and the water pump 3 are arranged in series. The small steam turbine 1 is coaxially connected to the electric generator 2 through the gearbox 7. The electric generator 2 is coaxially connected to the water pump 3 through the transmission 8. The electric generator 2 operates at a constant speed.

[0052] In the above technical solution, the small steam turbine, gearbox, electric generator, transmission, and feedwater pump are arranged in series and coaxially, reducing the lateral space occupied by the equipment, resulting in a more compact overall layout. The power transmission path is short and direct, reducing energy loss during transmission. The electric generator operates at a constant speed, and the speed of the feedwater pump is adjusted by the transmission, enabling the entire system to operate stably under the set operating conditions. This stable operating mode reduces the number of equipment start-ups and shutdowns and the impact of frequent speed adjustments, extending the service life of the equipment.

[0053] It is worth noting that, under high, medium, or low load conditions, to ensure the highest overall energy efficiency of the feedwater pumping unit, the extraction mode of the small turbine can be switched to achieve the highest efficiency for different unit loads. Specifically, when the unit load is less than 45% THA, the feedwater pumping unit is in a deep peak-shaving state. At this time, the extraction mode of the small turbine is switched to reheater cold end extraction, drawing different amounts of steam from the reheater cold section to small turbine 1 to regulate the reheat steam temperature, reduce the amount of steam going to the reheater, and improve the efficiency of the medium and low pressure cylinders. When the unit load is between [45% and 75% THA], the extraction mode of the small turbine is switched to four extractions, with the upper limit being that the steam temperature difference before and after the switch does not exceed 50℃, controlling the small turbine... The opening degrees of each valve in the unit are adjusted to complete the switching. When the unit load is greater than 75% THA, the extraction method of the small turbine is switched to extraction through the medium and low pressure connecting pipe. Furthermore, under low load conditions, the extraction method of the small turbine is switched to extraction from the cold end of the reheater, which maintains the highest regenerative efficiency. Increasing the reheat steam temperature reduces water erosion problems in the last stage blades of the low-pressure cylinder, improving unit safety. Simultaneously, extracting steam from before the reheater increases the steam velocity in the reheater, which in turn improves the heat exchange efficiency of the reheater.

[0054] like Figure 9 As shown, the control process of the water supply pump set includes the following steps: I. Obtain the unit load.

[0055] II. Compare the unit load with the preset load range [45%, 75%] THA. When the unit load is less than 45% THA, the small turbine switches to reheater cold end extraction; when the unit load is in the range [45%, 75%] THA, the small turbine switches to fourth extraction; when the unit load is greater than 75% THA, the small turbine switches to medium and low pressure cylinder extraction.

[0056] III. Control the valve opening in the small steam turbine.

[0057] IV. Determine if the temperature difference before and after switching the extraction mode of the small steam turbine is less than 50℃. If yes, proceed to V; otherwise, return to proceed to III.

[0058] V. Determine whether the power of the small steam turbine is greater than the power of the feedwater pump. If yes, the small steam turbine drives the feedwater pump; if not, the generator continues to generate electricity, and the small steam turbine supplies steam to drive the feedwater pump.

[0059] In the above technical solution, the gas source of the small steam turbine is switched according to the unit load to ensure the highest unit efficiency. The regulating valve of the small steam turbine is fully opened to maximize the extraction of steam from the main unit, and the feedwater pump speed is regulated by the load of the electric generator. Moreover, the feedwater pump set is driven by both steam and electricity, which can improve the overall thermal efficiency of the main unit and reduce the plant power consumption of the feedwater pump.

[0060] Based on the same inventive concept, this disclosure also provides a thermal power unit, including the above-mentioned feedwater pump unit.

[0061] The above technical solution achieves the highest efficiency of the feedwater pump set by switching the extraction mode of the small steam turbine according to the unit load of the main steam turbine; and by flexibly switching between the small steam turbine or electric motor to drive the feedwater pump based on the power relationship between the small steam turbine and the feedwater pump, thereby improving the driving efficiency of the feedwater pump. The switching method is simple and improves the reliability of the dual steam-electric drive of the feedwater pump.

[0062] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0063] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0064] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A water supply pump set, characterized in that, include: The small steam turbine (1), the electric generator (2), and the feedwater pump (3) are connected together. The steam inlet of the small steam turbine (1) is connected to the intermediate-pressure cylinder and low-pressure cylinder of the main steam turbine through a steam pipe. The steam outlet of the small steam turbine (1) is connected to the condenser. The small steam turbine (1), the electric generator (2), and the feedwater pump (3) are coaxially connected. The small steam turbine (1) is used to switch to the target extraction mode according to the unit load of the main steam turbine, and to supply steam to the feedwater pump (3) when the power of the target extraction mode is greater than the power of the feedwater pump (3) to drive the feedwater pump (3) to run. The electric generator (2) is used to generate electricity when the power of the small steam turbine (1) under the target extraction mode is less than or equal to the power of the feedwater pump (3), and the small steam turbine supplies gas to the feedwater pump to drive the feedwater pump (3) to operate.

2. The water supply pump set according to claim 1, characterized in that, The small steam turbine (1), the electric generator (2) and the water pump (3) are arranged in series. The small steam turbine (1) is coaxially connected to the electric generator (2) through a coupling (4). The electric generator (2) is then coaxially connected to the water pump through a coupling (4). The electric generator (2) is equipped with a frequency converter (5), and the small steam turbine (1), the electric generator (2) and the water pump (3) operate at the same speed.

3. The water supply pump set according to claim 1, characterized in that, The water pump (3), the small steam turbine (1) and the electric generator (2) are arranged in series. The water pump (3) is coaxially connected to the small steam turbine (1) through a coupling (4). The small steam turbine (1) is then coaxially connected to the electric generator (2) through a coupling (4). The electric generator (2) is equipped with a frequency converter (5) and the electric generator (2) operates at variable speed.

4. The water supply pump set according to claim 1, characterized in that, The electric generator (2), the water pump (3) and the small steam turbine (1) are arranged in series. The electric generator (2) is coaxially connected to the water pump (3) through a coupling (4). The water pump (3) is then coaxially connected to the small steam turbine (1) through a coupling (4). The electric generator (2) is equipped with a frequency converter (5), and the electric generator (2), the water pump (3) and the small steam turbine (1) operate at the same speed.

5. The water supply pump set according to claim 1, characterized in that, It also includes a speed change gearbox (6), the small steam turbine (1), the electric generator (2), the speed change gearbox (6) and the water pump (3) are arranged in series, the small steam turbine (1) is coaxially connected to the electric generator (2) through a coupling (4), and the electric generator (2) is coaxially connected to the water pump (3) through the speed change gearbox (6); The electric generator (2) is equipped with a frequency converter (5) and the electric generator (2) operates at a constant speed.

6. The water supply pump set according to claim 1, characterized in that, It also includes a gearbox (6), the electric generator (2), the gearbox (6), the small steam turbine (1) and the water pump (3) are arranged in series, the electric generator (2) is coaxially connected to the small steam turbine (1) through the gearbox (6), and the small steam turbine (1) is coaxially connected to the water pump (3) through a coupling (4); Both the electric generator (2) and the gearbox (6) operate at a constant speed.

7. The water supply pump set according to claim 1, characterized in that, It also includes a variable speed gearbox (6), the small steam turbine (1), the water pump (3), the variable speed gearbox (6) and the electric generator (2) are arranged in series. The small steam turbine (1) is coaxially connected to the water pump (3) through a coupling (4), and the water pump (3) is coaxially connected to the electric generator (2) through the variable speed gearbox (6). The electric generator (2) runs at a constant speed.

8. The water supply pump set according to claim 1, characterized in that, It also includes a gearbox (7) and a transmission (8). The small steam turbine (1), the gearbox (7), the electric generator (2), the transmission (8) and the water pump (3) are arranged in series. The small steam turbine (1) is coaxially connected to the electric generator (2) through the gearbox (7). The electric generator (2) is coaxially connected to the water pump (3) through the transmission (8). The electric generator (2) runs at a constant speed.

9. The water supply pump set according to any one of claims 1-8, characterized in that, The length of the final blades of the low-pressure cylinder in the small steam turbine ranges from 500mm to 800mm.

10. A thermal power unit, characterized in that, Includes the water supply pump assembly as described in any one of claims 1-9.

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