Wide-load operation method of turboset

Abstract

According to the wide-load operation method of the turboset, the wide-load operation working condition of the turboset comprises a peak-shaving operation working condition and a non-peak-shaving operation working condition, the load of the peak-shaving operation working condition of the turboset is x% of the rated load of the turboset, a high-pressure cylinder, an intermediate-pressure cylinder and a second-class low-pressure cylinder jointly output power, and 5 < = xlt; a; the load of the turboset under the non-peak-shaving operation condition is y% of the rated load of the turboset, the high-pressure cylinder, the medium-pressure cylinder and the first-class low-pressure cylinder jointly output power, and y is larger than or equal to a and smaller than or equal to 110; a is a peak regulation working condition point from a high load to a low load of the turboset; the steam flow of the first-class low-pressure cylinder is gradually reduced to be closed or gradually reduced to be maintained at the minimum cooling flow working condition, and the steam flow of the second-class low-pressure cylinder is gradually increased to the rated rotating speed and the rated load working condition; the steam flow of the first-class low-pressure cylinder is gradually increased to the rated load working condition, and the steam flow of the second-class low-pressure cylinder is gradually reduced to be closed.

Description

Technical Field

[0001] The present invention belongs to the technical field of peak shaving of steam turbine units, and particularly relates to a wide-load operation method for steam turbine units. Background Art

[0002] New energy has characteristics such as volatility and intermittency. For example, photovoltaic power depends on the sun and wind power depends on the weather, which has a negative impact on the overall safety and stability of the power grid. To solve this contradiction, the power system requires thermal power units to undertake peak shaving tasks. When new energy power generation is at a low valley, it is required that thermal power units generate electricity at full capacity. When new energy power generation is at a peak, it is required that thermal power units generate as little electricity as possible. The power system usually requires thermal power units to peak shave to operate at 20% load or lower. Units coupled with energy storage often require coal-fired units to peak shave to 10% or below. Thermal power units are usually designed based on the design operating point at 100% load. When operating at 100% load, the internal efficiency of the unit is the highest, the heat consumption rate is the lowest, and the performance is the best. As the load decreases, the operation of the unit deviates from the design operating point, and the efficiency and heat consumption indexes of the unit gradually deteriorate.

[0003] Therefore, when thermal power units perform peak shaving, the performance indexes of the units are often poor;

[0004] In the power system, "peak shaving" refers to adjusting the output of generator sets according to the change of power grid load to maintain the balance between power supply and demand. Specifically, peak shaving is divided into two categories: daily peak shaving and seasonal peak shaving. Daily peak shaving is to cope with the changes of daily load peaks and valleys, and seasonal peak shaving is to cope with seasonal load changes.

[0005] In order to meet the application requirements of new energy, the realization of "deep peak shaving" is imminent; "deep peak shaving" refers to the ability and range of generator sets to operate under low-load conditions. The depth of deep peak shaving generally refers to the lowest load percentage at which the generator set can operate stably and safely. For conventional coal-fired generator sets, deep peak shaving usually means that the unit load is reduced to 20%-50% of the rated load; however, the existing new energy supply trend requires that the steam turbine unit can still operate normally at a rated load as low as 20%-5%;

[0006] However, at the load of deep peak shaving, there are such safety problems and economic operation cost problems:

[0007] Thermal shock of steam turbine: During deep peak shaving, the unit frequently adjusts the load, and the steam turbine is easily subjected to rapid temperature rise and fall shocks, resulting in an increase in mechanical stress, which may cause mechanical failures such as cracks and deformations.

[0008] Decrease in steam quality: When the load decreases, the steam pressure and temperature are unstable, which may cause an increase in the water content in the steam, trigger a water hammer phenomenon, and damage the low-pressure cylinder and its related equipment.

[0009] Decrease in thermal efficiency: Conventional thermal power generation units are usually designed and operated at the full-load design operating point. When operating at low loads, the thermal efficiency decreases significantly, the coal consumption increases, and the economy deteriorates.

[0010] Increase in maintenance costs: Deep peak shaving exacerbates the mechanical wear and chemical corrosion of equipment, resulting in an increase in the maintenance frequency and maintenance costs.

[0011] Spare capacity and start-up costs: To cope with load fluctuations, it is necessary to keep some generating units in a standby state, or frequently start and stop the units, increasing the start-up costs and fuel consumption.

[0012] When operating at 20% load or lower, both the economic and safety problems of coal-fired steam turbine units are prominent. Since the design operating point of the unit is based on full load, the characteristics of the unit operating at low load are as follows:

[0013] 1) Compared with operating at 100% load, when at 20% load or lower, the internal efficiency of the high-pressure cylinder and the intermediate-pressure cylinder slightly decreases, and the internal efficiency of the low-pressure cylinder significantly decreases. As shown in Figure 5 、 8 , that is, when operating at low load, the low-pressure cylinder significantly affects the operating efficiency of the unit;

[0014] 2) When at 20% load or lower, safety problems such as blowing, overheating, water erosion, and flutter occur in the last stage blades of the low-pressure cylinder of the steam turbine. Usually, the lower the load, the more prominent these problems are. Safety problems such as blowing, overheating, water erosion, and flutter affect the safe operation of the unit; in this case, the low-pressure cylinder needs to be equipped with special means, such as staged water injection and additional monitoring systems, etc., to operate safely at a certain low load;

[0015] 3) There is a flutter interval for the last stage blades, and the unit usually cannot operate continuously below 20% load. For example, when in the load interval of 15% - 10%, the dynamic stress of the last stage blades increases sharply. At this time, the unit operates unstably, and the steam inlet quantity or back pressure needs to be adjusted to quickly cross this dangerous interval; this processing method ensures the safe operation of the steam turbine, but conflicts with the flexible regulation of the full load section of the power grid; the power system usually requires thermal power generation units to operate at 20% of the rated load or lower.

[0016] The flow-through and exhaust area of the low-pressure cylinder of the unit is designed based on full load. When at full load, the specific volumes of the inlet and exhaust of each module of the steam turbine are different. As shown in Figure 6As shown, the specific volume of the exhaust steam of the low-pressure cylinder of the steam turbine is more than 2,000 times that of the inlet steam of the high-pressure cylinder. The flow passage and exhaust area of the low-pressure cylinder need to be very large and long to meet the requirements of the full-load low-pressure exhaust steam volume. Therefore, the flow passage area of the low-pressure cylinder needs to be designed very large, and long last-stage blades need to be used in the exhaust area. Since the specific volume of the inlet and exhaust steam of the high and medium pressure cylinders of the steam turbine is small, the flow passage area of the high and medium pressure cylinders does not need to be designed very large, and shorter blades in the high and medium pressure cylinders can meet the requirements of the steam flow in the flow passage.

[0017] However, when the load is 20% or below, the steam parameters, inlet and exhaust steam volume of the unit decrease significantly. In this case, due to the small flow passage area of the high and medium pressure modules, they are not sensitive to this situation, and the steam inside the flow passage still mainly expands and does work along the axial direction. Therefore, the internal efficiency of the high and medium pressure modules decreases less, as Figure 5 , 8 shown. Due to the large flow passage and exhaust area of the low-pressure cylinder, the internal efficiency of the low-pressure cylinder is very sensitive to this situation, as Figure 5 , 8 shown. When low-parameter and small amounts of steam enter the large low-pressure cylinder, the internal steam streamline becomes disordered. Not only are there more separation vortices and recirculation vortices inside, but a large amount of steam at the exhaust end becomes radial flow, and the steam pressure becomes smaller, as Figure 7 shown. When small-volume flow steam enters the large-flow passage low-pressure cylinder, the last few stages of blades at the low-pressure exhaust cylinder start to do reverse work on the steam, which not only reduces the internal efficiency of the low-pressure cylinder, but also causes local overheating and blowing of the blade tip due to the friction between the low-pressure blade and the steam. At the low-pressure exhaust end, the blade blows and heats up, and overheats. The recirculating wet steam acts on the blade, causing blade water erosion. The unstable steam flow also acts on the last-stage blade with alternating stress, causing a sharp increase in the dynamic stress of the blade and blade flutter. When operating at 20% load or below, the low-pressure exhaust cylinder is not only unsafe, but also has poor economy, greatly affecting the deep peak shaving and flexible operation ability of the unit.

[0018] Generally speaking, the above-mentioned existing technologies have the following defects: There is a lack of a safe and economic technical implementation path for realizing the operation of a steam turbine unit at low loads. In order to meet the development needs of new energy, improvement is urgently needed. Summary of the Invention

[0019] To overcome the above problems of the existing technology and achieve the above and other related purposes, the present application provides a wide-load operation method for a steam turbine unit. The wide-load operation conditions of the steam turbine unit include peak shaving operation conditions and non-peak shaving operation conditions, and meet the following requirements:

[0020] The load of the peak shaving operation condition of the steam turbine unit is x% of the rated load of the steam turbine unit, and the high-pressure cylinder, medium-pressure cylinder and the second type of low-pressure cylinder jointly generate power, where 5 ≤ x < a;

[0021] The load of the non-peak shaving operation condition of the steam turbine unit is y% of the rated load of the steam turbine unit. The high-pressure cylinder, the intermediate-pressure cylinder and the first-class low-pressure cylinder jointly generate power, where a ≤ y ≤ 110; a is the peak shaving operation point from the high load to the low load of the steam turbine unit, and 20 ≤ a ≤ 60;

[0022] The steps for the steam turbine unit to switch between the peak shaving operation condition and the non-peak shaving operation condition include:

[0023] Switching from the non-peak shaving operation condition to the peak shaving operation condition: The first-class low-pressure cylinder gradually reduces the steam flow rate until it is closed or gradually reduces to maintain the minimum cooling flow rate condition, and the second-class low-pressure cylinder gradually increases the steam flow rate to the rated speed and rated load condition;

[0024] Switching from the peak shaving operation condition to the non-peak shaving operation condition: The first-class low-pressure cylinder gradually increases the steam flow rate to the rated load condition, and the second-class low-pressure cylinder gradually reduces the steam flow rate until it is closed.

[0025] The first-class low-pressure cylinder is used to meet the non-peak shaving operation condition, and the second-class low-pressure cylinder is used to meet the peak shaving operation condition; the low-pressure flow-through and exhaust areas of the first-class low-pressure cylinder are both larger than those of the second-class low-pressure cylinder;

[0026] The first-class low-pressure cylinder includes at least one low-pressure cylinder, and the second-class low-pressure cylinder includes at least one low-pressure cylinder;

[0027] a is the peak shaving operation point from the high load to the low load of the steam turbine unit, which is determined based on the supplementary situation of new energy. Generally, the operation condition above 30% of the rated load of the steam turbine unit is regarded as the normal operation state; conservatively estimated, the operation condition below 20% of the rated load of the steam turbine unit is the peak shaving operation condition, that is, the condition of multiple energy supplements to reduce the load required by the steam turbine unit.

[0028] The steam path of the steam turbine unit:

[0029] High-pressure cylinder → Intermediate-pressure cylinder → Low-pressure cylinder → Condenser: This is the typical steam flow path, and energy conversion and expansion are carried out in sequence;

[0030] High-pressure cylinder: High-pressure steam first enters the high-pressure cylinder for preliminary expansion, converting the energy of high-temperature and high-pressure steam into mechanical energy;

[0031] Intermediate-pressure cylinder: The steam expands in the high-pressure cylinder and then enters the intermediate-pressure cylinder for further expansion, further converting heat energy into mechanical energy;

[0032] Low-pressure cylinder: The steam expanded in the intermediate-pressure cylinder enters the low-pressure cylinder for final expansion and energy conversion, and then is discharged into the condenser;

[0033] The design and operation load distribution of each cylinder body affect the efficiency of the entire steam turbine unit;

[0034] For the shutdown or load reduction of the first-class low-pressure cylinder and the second-class low-pressure cylinder, the steam admission is gradually reduced, the low-pressure cylinder is closed or maintained at the minimum cooling flow condition; by adjusting the steam admission regulating valve of the low-pressure cylinder or the cylinder-cutting regulating butterfly valve, the steam flow into the low-pressure cylinder is gradually reduced.

[0035] For the startup of the first-class low-pressure cylinder and the second-class low-pressure cylinder, the steam admission is gradually increased to open the low-pressure cylinder and maintain it at the rated load or design load condition; by adjusting the steam admission regulating valve of the low-pressure cylinder or the cylinder-cutting regulating butterfly valve, the steam flow into the low-pressure cylinder is gradually increased.

[0036] For the shutdown of the first-class low-pressure cylinder and the second-class low-pressure cylinder, the steam admission regulating valve is used to cut off the steam entering the low-pressure cylinder to ensure that there is no high-pressure steam inside the cylinder body.

[0037] A technical solution provided by this application also has the following technical features:

[0038] Preferably, in an embodiment of this application, the second-class low-pressure cylinder is arranged in front of the high-pressure cylinder, and a clutch is provided to connect or disengage the shaft systems of the high-pressure cylinder and the intermediate-pressure cylinder.

[0039] After the second-class low-pressure cylinder reaches the rated speed, it is connected to the main shafts of the high-pressure cylinder and the intermediate-pressure cylinder through the clutch. The regulating valve of the first-class low-pressure cylinder is closed, the first-class low-pressure cylinder is cut off, the regulating valve of the second-class low-pressure cylinder is opened, so that the intermediate-pressure exhaust steam enters the second-class low-pressure cylinder and realizes grid connection.

[0040] Preferably, in an embodiment of this application, under non-peak shaving operation conditions, the first-class low-pressure cylinder is connected to the shaft systems of the high-pressure cylinder and the intermediate-pressure cylinder, and the second-class low-pressure cylinder is disengaged from the shaft systems of the high-pressure cylinder and the intermediate-pressure cylinder;

[0041] Under peak shaving operation conditions, the first-class low-pressure cylinder is disengaged from the shaft systems of the high-pressure cylinder and the intermediate-pressure cylinder, and the second-class low-pressure cylinder is connected to the shaft systems of the high-pressure cylinder and the intermediate-pressure cylinder.

[0042] Preferably, in an embodiment of this application, the design load point of the second-class low-pressure cylinder is preferably 10%-50% of the design load point of the first-class low-pressure cylinder;

[0043] The design load point is a key parameter to ensure its safe and efficient operation; the design load of the low-pressure cylinder refers to the best operating load condition determined during the design and manufacturing stages, that is, the low-pressure cylinder can operate stably, safely and efficiently for a long time under this load; under the best operating load condition, the design parameters of the low-pressure cylinder include: the inlet pressure and outlet pressure of the low-pressure cylinder, the steam temperature entering the low-pressure cylinder, the rotational speed of the low-pressure cylinder, the power output value of the low-pressure cylinder for the steam turbine unit, the thermal efficiency of the low-pressure cylinder, the steam flow of the low-pressure cylinder, and the structure and materials of the low-pressure cylinder, such as the blade shape and materials of the moving and static blades design. Under the design load condition, the blade profile and flow passage should be adapted.

[0044] Preferably, in an embodiment of the present application, a regulating valve is provided between the intermediate pressure cylinder and the first type of low-pressure cylinder, and the regulating valve is used to open and close the first type of low-pressure cylinder; a regulating valve is provided between the intermediate pressure cylinder and the second type of low-pressure cylinder, and the regulating valve is used to open and close the second type of low-pressure cylinder.

[0045] Preferably, in an embodiment of the present application, two regulating valves are provided between the intermediate pressure cylinder and the first type of low-pressure cylinder and are connected through steam guide pipes of different specifications; the regulating valve of the steam guide pipe with a larger specification is used to open and close the first type of low-pressure cylinder; the regulating valve of the steam guide pipe with a smaller specification is used to ensure that the first type of low-pressure cylinder has a minimum cooling flow; a regulating valve is provided between the intermediate pressure cylinder and the second type of low-pressure cylinder, and the regulating valve is used to open and close the second type of low-pressure cylinder.

[0046] Preferably, in an embodiment of the present application, when the steam turbine unit is in a non-peak shaving operation condition, the high-pressure cylinder, the intermediate pressure cylinder and the first type of low-pressure cylinder jointly generate power;

[0047] When the steam turbine unit is in a peak shaving operation condition, the first type of low-pressure cylinder is cut off, and the high-pressure cylinder, the intermediate pressure cylinder and the second type of low-pressure cylinder jointly generate power.

[0048] Preferably, in an embodiment of the present application, when the steam turbine unit switches from a non-peak shaving operation condition to a peak shaving operation condition, the regulating valve of the first type of low-pressure cylinder is gradually closed, and the regulating valve of the second type of low-pressure cylinder is gradually opened.

[0049] Preferably, in an embodiment of the present application, after the second type of low-pressure cylinder reaches the rated speed, it is connected to the high- and intermediate-pressure main shafts through a clutch, the regulating valve of the first type of low-pressure cylinder is closed, the first type of low-pressure cylinder is cut off, and the regulating valve of the second type of low-pressure cylinder is opened, so that the intermediate pressure exhaust completely enters the second type of low-pressure cylinder.

[0050] Preferably, in an embodiment of the present application, when the steam turbine unit switches from a peak shaving operation condition to a non-peak shaving operation condition, the regulating valve of the second type of low-pressure cylinder is gradually closed, and the regulating valve of the first type of low-pressure cylinder is gradually opened.

[0051] Preferably, in an embodiment of the present application, during the switching process of the first type of low-pressure cylinder and the second type of low-pressure cylinder, the steam turbine unit does not perform warm-up.

[0052] Preferably, in an embodiment of the present application, when the steam turbine unit is in a non-peak shaving operation condition, the high-pressure cylinder, the intermediate pressure cylinder and the first type of low-pressure cylinder jointly generate power, and the load of the non-peak shaving operation condition of the steam turbine unit is higher than or equal to y% of the rated load of the steam turbine unit;

[0053] When the steam turbine unit is in a peak shaving operation condition, the high-pressure cylinder, the intermediate pressure cylinder and the second type of low-pressure cylinder jointly generate power, and the load of the peak shaving operation condition of the steam turbine unit is preferably 5%-50% of the rated load of the steam turbine unit.

[0054] Preferably, in an embodiment of the present application, as Figure 1 , the high-pressure cylinder rotor and the intermediate-pressure cylinder rotor are connected, arranged on shaft I, and connected to generator I; a first type of low-pressure cylinder rotor is independently arranged, arranged on shaft II, and connected to generator II; the shaft of the second type of low-pressure cylinder rotor is connected and separated from the shaft systems of the high-pressure cylinder rotor and the intermediate-pressure cylinder rotor through a clutch; shaft I and shaft II are arranged non-coaxially; the shaft system of the second type of low-pressure cylinder is independently arranged, and a clutch is provided for connecting and disconnecting with the shaft systems of the high-pressure cylinder rotor, the intermediate-pressure cylinder rotor, and the first type of low-pressure cylinder rotor.

[0055] When the steam turbine unit is in a non-peak shaving operation condition, the clutch is disengaged, the regulating valve of the second type of low-pressure cylinder is closed, and the second type of low-pressure cylinder stops; the regulating valve of the first type of low-pressure cylinder is opened, and the first type of low-pressure cylinder operates in combination with the high-pressure cylinder and the intermediate-pressure cylinder, and generators I and II are used for power generation.

[0056] When the steam turbine is in peak shaving operation, the regulating valve of the first type of low-pressure cylinder is gradually closed, the first type of low-pressure cylinder gradually reduces the load and speed to the turning speed or stops; the regulating valve of the second type of low-pressure cylinder is gradually opened, the second type of low-pressure cylinder starts and rises to the rated speed, the clutch is engaged, and the second type of low-pressure cylinder connects with the high-pressure cylinder to output power, and generator I is used for power generation.

[0057] The unit realizes the start-up, wide-load operation, and shutdown of the unit by disengaging or engaging the clutch and opening or closing the regulating valves of the first type of low-pressure cylinder and the second type of low-pressure cylinder.

[0058] Preferably, in an embodiment of the present application, as Figure 2 , the high-pressure cylinder rotor and the intermediate-pressure cylinder rotor are connected, arranged on shaft I, and connected to generator I; a first type of low-pressure cylinder rotor is independently arranged, arranged on shaft II, and connected to generator II; the second type of low-pressure cylinder rotor is arranged on shaft III and connected to generator III; shaft I, shaft II, and shaft III are arranged non-coaxially.

[0059] When the steam turbine unit is in a non-peak shaving operation condition, the regulating valve of the second type of low-pressure cylinder is closed, and the second type of low-pressure cylinder stops; the regulating valve of the first type of low-pressure cylinder is opened, the first type of low-pressure cylinder increases the speed and load, and the first type of low-pressure cylinder outputs power in combination with the high-pressure cylinder and the intermediate-pressure cylinder, and generators I and II are used for power generation.

[0060] When the steam turbine unit is in a peak shaving operation condition, the regulating valve of the first type of low-pressure cylinder is closed, the first type of low-pressure cylinder reduces the load and speed to the turning speed or stops; the regulating valve of the second type of low-pressure cylinder is opened, the second type of low-pressure cylinder increases the speed to the rated speed and increases the load to the peak shaving load, and generators I and III are used for power generation.

[0061] The unit realizes the start-up, wide-load operation, and shutdown of the unit by opening or closing the regulating valves of the first and second types of low-pressure cylinders.

[0062] Preferably, in an embodiment of the present application, as Figure 3, the high-pressure cylinder rotor, the intermediate-pressure cylinder rotor, the first-class low-pressure cylinder rotor and the rotor of Generator I are connected and arranged on Shaft I; the second-class low-pressure cylinder rotor is connected to the rotor of Generator II and arranged on Shaft II; Shaft I and Shaft II are arranged non-coaxially;

[0063] Two steam guide pipes are arranged between the exhaust steam of the intermediate-pressure cylinder and the first-class low-pressure cylinder, and they have different specifications; the steam guide pipe with a larger specification is used for the intermediate-low pressure connecting pipe, and a connecting pipe butterfly valve is set; a regulating valve for the first-class low-pressure cylinder is set on the steam guide pipe with a smaller specification;

[0064] A steam guide pipe is arranged between the exhaust steam of the intermediate-pressure cylinder and the second-class low-pressure cylinder, and a regulating valve for the second-class low-pressure cylinder is set on the steam guide pipe;

[0065] When the steam turbine unit is in a non-peak shaving operation condition, the regulating valve of the second-class low-pressure cylinder is closed and the second-class low-pressure cylinder stops; the connecting pipe butterfly valve of the first-class low-pressure cylinder is fully open, the regulating valve of the first-class low-pressure cylinder is closed, and the first-class low-pressure cylinder jointly outputs power with the high-pressure cylinder and the intermediate-pressure cylinder, and Generator I generates electricity;

[0066] When the steam turbine unit is in a peak shaving operation condition, the connecting pipe butterfly valve of the first-class low-pressure cylinder is gradually closed, the regulating valve of the first-class low-pressure cylinder is gradually opened, the first-class low-pressure cylinder gradually reduces the load and enters the cut-off state with the minimum cooling steam flow, the regulating valve of the second-class low-pressure cylinder is gradually opened, and the second-class low-pressure cylinder rises from zero speed or turning speed to the rated speed and peak shaving load, and Generator I and Generator II generate electricity;

[0067] The unit realizes the start-up, wide-load operation and shutdown of the unit by opening or closing the regulating valves and connecting pipe butterfly valves of the first-class and second-class low-pressure cylinders.

[0068] Preferably, in an embodiment of the present application, as Figure 4 , the high-pressure cylinder rotor, the intermediate-pressure cylinder rotor, the first-class low-pressure cylinder rotor and the rotor of Generator I are connected and arranged on Shaft I; the second-class low-pressure cylinder rotor is connected to the rotor of Generator I and arranged on Shaft I;

[0069] Two steam guide pipes are arranged between the exhaust steam of the intermediate-pressure cylinder and the first-class low-pressure cylinder, and they have different specifications; the steam guide pipe with a larger specification is used for the intermediate-low pressure connecting pipe, and a connecting pipe butterfly valve is set; a regulating valve for the first-class low-pressure cylinder is set on the steam guide pipe with a smaller specification;

[0070] A steam guide pipe is arranged between the exhaust steam of the intermediate-pressure cylinder and the second-class low-pressure cylinder, and a regulating valve for the second-class low-pressure cylinder is set on the steam guide pipe;

[0071] The shafting of the second-class low-pressure cylinder is independently arranged, and a clutch is provided for connecting and disconnecting with the shafting of the high-pressure cylinder rotor, the intermediate-pressure cylinder rotor, and the first-class low-pressure cylinder rotor; when the steam turbine unit is in a non-peak shaving operation condition, the butterfly valve of the connecting pipe of the first-class low-pressure cylinder is fully open, the regulating valve of the first-class low-pressure cylinder is closed, the regulating valve of the second-class low-pressure cylinder is closed, the clutch between the second-class low-pressure cylinder and the high-pressure cylinder is disengaged, the second-class low-pressure cylinder stops, and the high-pressure cylinder and the intermediate-pressure cylinder jointly output power with the first-class low-pressure cylinder, and Generator I generates electricity;

[0072] When the steam turbine unit is in a peak shaving operation condition, the butterfly valve of the connecting pipe of the first-class low-pressure cylinder is gradually closed, the regulating valve of the first-class low-pressure cylinder is gradually opened, the regulating valve of the second-class low-pressure cylinder is gradually opened, the first-class low-pressure cylinder reduces the load and enters the cut-off state with the minimum cooling steam flow rate. The second-class low-pressure cylinder rises from zero speed or turning speed to the rated speed, the clutch of the second-class low-pressure cylinder is engaged, the second-class low-pressure cylinder is connected to the high-pressure cylinder and rises to the peak shaving load, and Generator I generates electricity;

[0073] The unit realizes the start-up, wide-load operation, and shutdown of the unit by disengaging or engaging the clutch and opening or closing the regulating valves and connecting pipe butterfly valves of the first-class low-pressure cylinder and the second-class low-pressure cylinder.

[0074] Preferably, in an embodiment of the present application, the first-class low-pressure cylinder and the second-class low-pressure cylinder start up, operate under wide load, and shut down through valves arranged on the steam inlet pipeline or clutches on the shafting.

[0075] Preferably, in an embodiment of the present application, a first-class low-pressure cylinder regulating valve is arranged on the inlet pipeline of the first-class low-pressure cylinder, and a second-class low-pressure cylinder regulating valve is arranged on the inlet pipeline of the second-class low-pressure cylinder.

[0076] Preferably, in an embodiment of the present application, when the steam turbine unit is in a non-peak shaving operation condition, the clutch is disengaged, the regulating valve of the second-class low-pressure cylinder is closed, and the second-class low-pressure cylinder stops; the regulating valve of the first-class low-pressure cylinder is opened, the first-class low-pressure cylinder operates jointly with the high-pressure cylinder and the intermediate-pressure cylinder, and Generators I and II are used for generating electricity.

[0077] The beneficial effects of the present application are as follows:

[0078] 1. The wide-load operation method of the steam turbine unit of the present application can operate efficiently in a relatively wide load change range, with an adjustment range of 5%-100%, and higher peak shaving flexibility; when the unit performs peak shaving, problems such as low-pressure blade blowing, overheating, flutter, and water erosion are avoided, and the safety is better;

[0079] 2. By switching the use of the first-class low-pressure cylinder and the second-class low-pressure cylinder of the present application, the internal efficiency during deep peak shaving of the unit is significantly improved, and the economy of the unit is better; due to the low brittle transition temperature of the low-pressure rotor material, the low-pressure cylinder can be flexibly switched between the two types of low-pressure cylinders without preheating, and the flexibility is higher;

[0080] The adjustment method of this application has the characteristic of a relatively light low-pressure cylinder rotor, and can be connected to and disconnected from the high-pressure cylinder through a clutch;

[0081] 3. Thermal power units can better meet the requirements of the new power system and are suitable for application scenarios with a wide load range and multiple energy supplements. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 Turbine unit layout for a wide-load operation method of a steam turbine unit of the present invention Figure 1 ;

[0083] Figure 2 Turbine unit layout for a wide-load operation method of a steam turbine unit of the present invention Figure 2 ;

[0084] Figure 3 Turbine unit layout for a wide-load operation method of a steam turbine unit of the present invention Figure 3 ;

[0085] Figure 4 Turbine unit layout for a wide-load operation method of a steam turbine unit of the present invention Figure 4 ;

[0086] Figure 5 Schematic diagram of the internal efficiency change curve of a steam turbine cylinder in the prior art;

[0087] Figure 6 Schematic diagram of the specific volume change of a steam turbine in the prior art;

[0088] Figure 7 Schematic diagram of the steam flow distribution in the exhaust cylinder at low load in the prior art;

[0089] Figure 8 Schematic diagram of the internal efficiency change curve of a steam turbine unit at different loads in the prior art;

[0090] Figure 9 Schematic diagram of the internal efficiency change curve of a steam turbine unit at different loads under a wide-load operation method of a steam turbine unit of the present invention;

[0091] Figure 10 Schematic diagram of the dynamic output of the power generation ratio of a steam turbine unit under a wide-load operation method of a steam turbine unit of the present invention;

[0092] Figure 11 Schematic diagram of the dynamic output of the power generation ratio of a steam turbine unit under a wide-load operation method of a steam turbine unit of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0093] The following further elaborates on the specific implementation manners of the present application in conjunction with the accompanying drawings. These implementation manners are only used to illustrate the present application and do not limit the present invention.

[0094] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0095] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0096] In addition, in the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0097] Such as Figures 1-4 , the #1 low-pressure cylinder is a type of low-pressure cylinder; the #2 low-pressure cylinder is a type of low-pressure cylinder;

[0098] A wide-load operation method for a steam turbine unit. The wide-load operation conditions of the steam turbine unit include a peak shaving operation condition and a non-peak shaving operation condition, and meet the following requirements:

[0099] The load of the peak shaving operation condition of the steam turbine unit is x% of the rated load of the steam turbine unit. The high-pressure cylinder, the intermediate-pressure cylinder, and the type II low-pressure cylinder jointly output power, where 5 ≤ x < a;

[0100] The load of the non-peak shaving operation condition of the steam turbine unit is y% of the rated load of the steam turbine unit. The high-pressure cylinder, the intermediate-pressure cylinder, and the type I low-pressure cylinder jointly output power, where a ≤ y ≤ 110; a is the peak shaving operating point from the high load to the low load of the steam turbine unit, and 20 ≤ a ≤ 60;

[0101] The steps for the steam turbine unit to switch between the peak shaving operation condition and the non-peak shaving operation condition include:

[0102] Non-peak-shaving operation condition is switched to peak-shaving operation condition: the first-class low-pressure cylinder gradually reduces the steam flow rate until it is closed or gradually reduces to maintain the minimum cooling flow rate condition, and the second-class low-pressure cylinder gradually increases the steam flow rate to the rated load condition;

[0103] Peak-shaving operation condition is switched to non-peak-shaving operation condition: the first-class low-pressure cylinder gradually increases the steam flow rate to the rated load condition, and the second-class low-pressure cylinder gradually reduces the steam flow rate until it is closed;

[0104] The steam turbine unit includes a first-class low-pressure cylinder and a second-class low-pressure cylinder. The first-class low-pressure cylinder is used to meet the non-peak-shaving operation condition, and the second-class low-pressure cylinder is used to meet the peak-shaving operation condition; the low-pressure flow path and exhaust area of the first-class low-pressure cylinder are both larger than those of the second-class low-pressure cylinder;

[0105] In the prior art, the high-pressure cylinder, medium-pressure cylinder, low-pressure cylinder, and generator are arranged on one shaft, and the high-pressure cylinder, medium-pressure cylinder, and low-pressure cylinder are all designed based on full load; during deep peak shaving, the steam flow rate into the low-pressure cylinder is greatly reduced, and the steam flow changes significantly, resulting in disorders, vortices, and radial flow characteristics in the steam flow, leading to safety problems such as drum wind, overheating, flutter, and water erosion in the low-pressure cylinder, and resulting in a significant reduction in the efficiency inside the low-pressure cylinder;

[0106] The heat rate is an important indicator to measure the efficiency of power generation equipment and is usually used to describe the fuel utilization efficiency of a power plant or generator set; specifically, the heat rate represents the amount of heat energy consumed to generate unit electric energy;

[0107] For a general steam turbine unit, the greater the difference from the rated load, that is, the operating condition below the rated load, the lower the load corresponds to a higher heat rate, which means high operating cost and low thermal efficiency;

[0108] Moreover, with the increase in new energy supplementation, the operating time of the steam turbine unit is mostly in the low-load state, or generally in the situation below the rated load. Therefore, in order to reduce heat loss, improve thermal efficiency, and reduce power generation cost; it is necessary to adjust the rated load design value, reduce the equipment design redundancy, reduce the heat loss during operation, and improve the thermal efficiency and power generation efficiency;

[0109] By adjusting the rated load value in the design condition, that is, adjusting the design load of the low-pressure cylinder, high-efficiency thermal efficiency and low-cost power generation can be achieved;

[0110] This application switches the first-class low-pressure cylinder by adding a second-class low-pressure cylinder with different design loads to meet the deep peak shaving requirements. That is, when the load adjustment requirement exceeds the operating conditions that the first-class low-pressure cylinder can meet, that is, when the operation of the first-class low-pressure cylinder will greatly reduce the thermal efficiency of the steam turbine unit, the supplemented second-class low-pressure cylinder is used to replace the first-class low-pressure cylinder under low load conditions and conditions with low thermal efficiency of the first-class low-pressure cylinder for combined power generation, so as to achieve high thermal efficiency and low-cost power generation;

[0111] As Figure 9 shown, after applying the technical solution of the present invention, it can be seen that the efficiency in the low load stage is improved; by comparing with Figure 7 it can be seen that the efficiency of the low load condition of this application is significantly improved;

[0112] As Figure 10 shown, after applying the present invention, it can be seen that under the change of the energy supply of photovoltaic power generation, applying this application can meet the deep peak shaving, cooperate with new energy, and ensure the overall stability of the output power while reducing coal-fired power generation, meet the demand of the power consumption side, and at the same time absorb the huge change in the grid power caused by the change of photovoltaic supply;

[0113] As Figure 11 shown, after applying the present invention, under the complex supply changes of various new energies, the technical requirements for deep peak shaving are more clear, and rapid response and adjustment are required to meet the changing needs of multiple supplies and dynamically and stably meet the terminal output requirements, that is, to ensure the stable operation of the grid supply, and at the same time absorb the fluctuations caused by the huge change in the new energy power output;

[0114] Furthermore, by combining wind energy, tidal energy, geothermal energy, hydroelectric power, nuclear power, etc., under the complex multi-energy supply, the wide-load operation of coal is utilized to meet the peak shaving operation requirements, and the grid stability can also be ensured, providing strong technical support for power safety, reducing coal consumption, and reducing carbon emissions;

[0115] When this application is implemented, the implementation key points are as follows: Two types of low-pressure cylinders are designed, one or more. The design operating point of one type of low-pressure cylinder is based on full load, with a large low-pressure flow path and exhaust area. The design operating point of the second type of low-pressure cylinder is based on low load, which can be set at 10%-50% of the design load point of the first type of low-pressure cylinder, specifically determined according to the peak shaving width. The second type of low-pressure cylinder has a small flow path and exhaust area, and the small-volume flow steam coming from the intermediate-pressure exhaust has a high matching degree with the flow path area and exhaust area of the #2 low-pressure cylinder. At full load or high load, the high-pressure cylinder, intermediate-pressure cylinder, and the first type of low-pressure cylinder jointly output power, ensuring the safety and economy of the unit; when peak shaving to low load is required, the first type of low-pressure cylinder is removed, and the high-pressure cylinder, intermediate-pressure cylinder, and the second type of low-pressure cylinder jointly output power, ensuring the safety and economy of the unit; since the brittle transition temperature of the low-pressure rotor material is low, the switching between the first type of low-pressure cylinder and the second type of low-pressure cylinder can be quickly completed without warm-up.

[0116] Specifically, in an embodiment of the present application, the second type of low-pressure cylinder is arranged in front of the high-pressure cylinder, and a clutch is provided to connect or disconnect the shaft systems of the high-pressure cylinder and the intermediate-pressure cylinder.

[0117] Under non-peak shaving operating conditions, the first type of low-pressure cylinder connects the shaft systems of the high-pressure cylinder and the intermediate-pressure cylinder, and the second type of low-pressure cylinder disconnects from the shaft systems of the high-pressure cylinder and the intermediate-pressure cylinder;

[0118] Under peak shaving operating conditions, the first type of low-pressure cylinder disconnects from the shaft systems of the high-pressure cylinder and the intermediate-pressure cylinder, and the second type of low-pressure cylinder connects the shaft systems of the high-pressure cylinder and the intermediate-pressure cylinder.

[0119] Specifically, in an embodiment of the present application, after the second type of low-pressure cylinder reaches the rated speed, it is connected to the high- and intermediate-pressure main shafts through a clutch, the regulating valve of the first type of low-pressure cylinder is closed, the first type of low-pressure cylinder is removed, and the regulating valve of the second type of low-pressure cylinder is opened, so that the intermediate-pressure exhaust completely enters the second type of low-pressure cylinder;

[0120] When the steam turbine unit switches from the peak shaving operating condition to the non-peak shaving operating condition, the regulating valve of the second type of low-pressure cylinder is gradually closed, and the regulating valve of the first type of low-pressure cylinder is gradually opened.

[0121] Specifically, in an embodiment of the present application, when the steam turbine unit is in the non-peak shaving operating condition, the high-pressure cylinder, intermediate-pressure cylinder, and the first type of low-pressure cylinder jointly output power;

[0122] When the steam turbine unit is in the peak shaving operating condition, the first type of low-pressure cylinder is removed, and the high-pressure cylinder, intermediate-pressure cylinder, and the second type of low-pressure cylinder jointly output power; when the steam turbine unit switches from the non-peak shaving operating condition to the peak shaving operating condition, the regulating valve of the first type of low-pressure cylinder is gradually closed, and the regulating valve of the second type of low-pressure cylinder is gradually opened.

[0123] Specifically, in an embodiment of the present application, as Figure 1, the high-pressure cylinder rotor is connected to the intermediate-pressure cylinder rotor, arranged on Shaft I, and connected to Generator I; one type of low-pressure cylinder rotor is independently arranged on Shaft II and connected to Generator II; the shaft of the second type of low-pressure cylinder rotor is connected and separated from the shaft systems of the high-pressure cylinder rotor and the intermediate-pressure cylinder rotor through a clutch; Shaft I and Shaft II are arranged non-coaxially; the shaft system of the second type of low-pressure cylinder is independently arranged, and a clutch is provided for connecting and disconnecting from the shaft systems of the high-pressure cylinder rotor, the intermediate-pressure cylinder rotor, and the first type of low-pressure cylinder rotor.

[0124] When the steam turbine unit is in a non-peak shaving operation condition, both Generator I and Generator II are used for power generation.

[0125] It has the following characteristics:

[0126] The design operating point of #1 low-pressure cylinder is based on full load design, and the low-pressure flow passage and exhaust area are large; the design operating point of #2 low-pressure cylinder is based on low load design, and the low-pressure flow passage and exhaust area are small.

[0127] At high loads, that is, in the non-peak shaving condition, the regulating valve of #1 low-pressure cylinder is fully open, the regulating valve of #2 low-pressure cylinder is closed, and the high-pressure cylinder, intermediate-pressure cylinder and Low-pressure cylinder 1 jointly output power, and electricity is generated through two generators.

[0128] When peak shaving to low load is required, that is, in the peak shaving condition, the regulating valve of #1 low-pressure cylinder is gradually closed, the regulating valve of #2 low-pressure cylinder is gradually opened. After #2 low-pressure cylinder is rotated to reach the rated speed, it is connected to the high and intermediate pressure main shafts through a clutch. Then close the regulating valve of #1 low-pressure cylinder, cut off #1 low-pressure cylinder, open the regulating valve of #2 low-pressure cylinder, so that the intermediate-pressure exhaust completely enters #2 low-pressure cylinder.

[0129] #2 low-pressure cylinder is arranged in front of the high-pressure cylinder, and its rotor is connected and separated from the shaft systems of the high and intermediate pressure cylinder rotors through a clutch. Since the flow passage area and exhaust area of #2 low-pressure cylinder are small, the small-volume flow steam coming from the intermediate-pressure exhaust has a high matching degree with the flow passage area and exhaust area of #2 low-pressure cylinder, and the economy of the unit is good. Moreover, the small-volume flow steam always flows axially and expands to do work in #2 low-pressure cylinder, which can effectively avoid problems such as drum wind, overheating, water erosion and flutter in the low-pressure cylinder. When the unit starts and high-load economic operation is required, the regulating valve of #1 low-pressure cylinder is fully open, the regulating valve of #2 low-pressure cylinder is closed, and the high-pressure cylinder, intermediate-pressure cylinder and #1 low-pressure cylinder jointly output power, and the unit generates electricity at full load or high load through two generators.

[0130] When the unit needs to perform peak shaving to a low load, the regulating valve of the #1 low-pressure cylinder gradually closes, and the regulating valve of the #2 low-pressure cylinder gradually opens, gradually realizing the switching between the #1 low-pressure cylinder and the #2 low-pressure cylinder. After the #2 low-pressure cylinder is impulsed to reach the rated speed, it is connected to the high- and medium-pressure main shafts through a clutch. Then, continue to close the regulating valve of the #1 low-pressure cylinder. After a certain degree, cut off the generator excitation. The regulating valve of the #2 low-pressure cylinder gradually opens wide, so that the medium-pressure exhaust steam completely enters the #2 low-pressure cylinder, and the #2 low-pressure cylinder is coupled with the high-pressure cylinder and the medium-pressure cylinder to generate electricity at low load. At this time, completely close the regulating valve of the #1 low-pressure cylinder, and the #1 low-pressure cylinder stops. When the unit needs to be adjusted from low load to high load, gradually open the regulating valve of the #1 low-pressure cylinder and gradually close the regulating valve of the #2 low-pressure cylinder. The #1 low-pressure cylinder starts, gradually reaches the rated speed and is connected to the grid for power generation; gradually reduce the steam inlet of the #2 low-pressure cylinder. After reaching a certain steam volume, disengage the clutch to realize the separation of the #2 low-pressure cylinder from the high-pressure cylinder. With the opening of the regulating valve of the #1 low-pressure cylinder, the #1 low-pressure cylinder gradually increases to the rated speed, is connected to the grid and increases to the rated load. Through the adjustment of the regulating valve of the #1 low-pressure cylinder and the #2 regulating valve, finally realize the shutdown of the #2 low-pressure cylinder and the high-load or full-load operation of the #1 low-pressure cylinder, realizing the high-load or full-load output of the steam turbine;

[0131] Using this control method for unit peak shaving has high flexibility, wide peak shaving depth, good safety and economy, and can realize peak shaving in the low load range of about 20%-5%;

[0132] Due to the small flow-through and small exhaust area of the #2 low-pressure cylinder, the steam turbine unit can be deeply adjusted to the load range of about 20%-5%; during low-load peak shaving operation, the small-volume flow steam always axially flows and expands in the #2 low-pressure cylinder to do work, which can effectively avoid problems such as drum wind, overheating, water erosion and flutter in the low-pressure cylinder, and the steam inlet volume of the low-pressure cylinder is relatively matched with the flow-through of the #2 low-pressure cylinder, and the unit has high economy.

[0133] Specifically, in an embodiment of the present application, as Figure 2 , the high-pressure cylinder rotor and the medium-pressure cylinder rotor are connected, arranged on shaft Ⅰ, and connected to generator Ⅰ; the first-class low-pressure cylinder rotor is independently arranged, arranged on shaft Ⅱ, and connected to generator Ⅱ; the second-class low-pressure cylinder rotor is arranged on shaft Ⅲ, and connected to generator Ⅲ; shaft Ⅰ, shaft Ⅱ, and shaft Ⅲ are not coaxially arranged;

[0134] When the steam turbine unit is in a non-peak shaving operation condition, both generator Ⅰ and generator Ⅱ are used for power generation; when the steam turbine unit is in a peak shaving operation condition, generator Ⅲ is used for power generation;

[0135] It has the following characteristics:

[0136] The design working condition point of the #1 low-pressure cylinder is designed based on full load, and the low-pressure flow-through and exhaust area are large; the design working condition point of the #2 low-pressure cylinder is designed based on low load, and the low-pressure flow-through and exhaust area are small;

[0137] During high-load operation, i.e., non-peak shaving conditions, the regulating valves of the #1 low-pressure cylinder are fully open, and the regulating valves of the #2 low-pressure cylinder are fully closed. The high-pressure cylinder and the intermediate-pressure cylinder jointly output power with the #1 low-pressure cylinder, and electricity is generated through two generators.

[0138] When peak shaving to low load is required, i.e., peak shaving conditions, the regulating valves of the #1 low-pressure cylinder are gradually closed, and the regulating valves of the #2 low-pressure cylinder are gradually opened. Gradually, the #1 low-pressure cylinder is cut off, and the high-pressure cylinder and the intermediate-pressure cylinder jointly output power with the #2 low-pressure cylinder for power generation.

[0139] During the startup and operation process, when at full load or high load, the regulating valves of the #1 low-pressure cylinder are fully open, and the regulating valves of the #2 low-pressure cylinder are fully closed. The high-pressure cylinder and the intermediate-pressure cylinder jointly output power with the #1 low-pressure cylinder, and electricity is generated through two generators. When peak shaving to low load is required, the regulating valves of the #1 low-pressure cylinder are gradually closed, and the regulating valves of the #2 low-pressure cylinder are gradually opened. Gradually, the #1 low-pressure cylinder is cut off for power generation, and the operation of the #1 low-pressure cylinder is stopped, realizing the joint output power of the high-pressure cylinder and the intermediate-pressure cylinder with the #2 low-pressure cylinder. When the power grid requires the unit to increase from low load to high load, the regulating valves of the #2 low-pressure cylinder are gradually closed, and the regulating valves of the #1 low-pressure cylinder are opened. The #2 low-pressure cylinder gradually cancels excitation for power generation and reduces its speed, while the #1 low-pressure cylinder gradually increases its speed and is connected to the grid to carry load. After reaching a certain level, the regulating valves of the #2 low-pressure cylinder are fully closed, and the #2 low-pressure cylinder is stopped. All the regulating valves of the #1 low-pressure cylinder are opened, realizing the joint output power of the high-pressure cylinder and the intermediate-pressure cylinder with the #1 low-pressure cylinder.

[0140] Using this control method for unit peak shaving has high flexibility, a wide peak shaving depth, good safety and economy, and can achieve peak shaving in the low-load range of about 20% - 5%.

[0141] The steam turbine unit of this design scheme can be deeply adjusted to the load range of about 20% - 5%. During low-load peak shaving operation, the small-volume flow steam always axially flows and expands in the #2 low-pressure cylinder to do work, which can effectively avoid problems such as drum wind, overheating, water erosion, and flutter in the low-pressure cylinder. Moreover, the steam inlet volume of the low-pressure cylinder is relatively well-matched with the flow passage of the #2 low-pressure cylinder, and the unit has high economy.

[0142] Specifically, in an embodiment of the present application, as Figure 3 , the rotor of the high-pressure cylinder, the rotor of the intermediate-pressure cylinder, the rotor of the first-class low-pressure cylinder, and the rotor of Generator I are connected and arranged on Shaft I; the rotor of the second-class low-pressure cylinder is connected to the rotor of Generator II and arranged on Shaft II; Shaft I and Shaft II are arranged non-coaxially.

[0143] Two steam guide pipes are arranged between the exhaust of the intermediate-pressure cylinder and the first-class low-pressure cylinder, and their specifications are different; the steam guide pipe with a larger specification is used for the medium-low pressure connecting pipe, and a connecting pipe butterfly valve is set; a regulating valve for the first-class low-pressure cylinder is set on the steam guide pipe with a smaller specification.

[0144] A steam guide pipe is arranged between the exhaust of the intermediate-pressure cylinder and the second-class low-pressure cylinder, and a regulating valve for the second-class low-pressure cylinder is set on the steam guide pipe.

[0145] When the steam turbine unit operates under non-peak shaving conditions, the regulating valves of the first-stage low-pressure cylinders are closed, the regulating valves of the second-stage low-pressure cylinders are closed, the butterfly valves of the connecting pipes are fully open, and the high-pressure cylinder and the intermediate-pressure cylinder jointly output power with the first-stage low-pressure cylinders, and Generator I generates electricity.

[0146] When the steam turbine unit operates under peak shaving conditions, the butterfly valves of the connecting pipes are gradually closed, the regulating valves of the first-stage low-pressure cylinders are gradually opened, the regulating valves of the second-stage low-pressure cylinders are gradually opened, the first-stage low-pressure cylinders enter the state of cutting off the minimum cooling steam flow, and the second-stage low-pressure cylinders operate normally.

[0147] It has the following characteristics:

[0148] The design operating point of #1 low-pressure cylinder is based on full load design, and the low-pressure flow passage and exhaust area are large; the design operating point of #2 low-pressure cylinder is based on low load design, and the low-pressure flow passage and exhaust area are small.

[0149] During high-load operation, that is, under non-peak shaving conditions, the regulating valves of #1 low-pressure cylinder are closed, the regulating valves of #2 low-pressure cylinder are closed, the butterfly valves of the intermediate-low pressure connecting pipes are fully open, the high-pressure cylinder and the intermediate-pressure cylinder jointly output power with #1 low-pressure cylinder, and electricity is generated through one generator.

[0150] When peak shaving to low load is required, that is, under peak shaving conditions, the butterfly valves of the connecting pipes are gradually closed, the regulating valves of #1 low-pressure cylinder are gradually opened, the regulating valves of #2 low-pressure cylinder are gradually opened, and finally, #1 low-pressure cylinder enters the state of cutting off the minimum cooling steam flow, and #2 low-pressure cylinder operates normally with grid connection and load bearing.

[0151] When the power grid requires the unit to increase from low load to high load, gradually reduce the regulating valve of #2 low-pressure cylinder, open the regulating valve of #1 low-pressure cylinder. After a certain degree, open the butterfly valve of the connecting pipe, fully close the regulating valves of #1 low-pressure cylinder and #2 low-pressure cylinder, and realize the output power switching between #1 low-pressure cylinder and #2 low-pressure cylinder. After the switching is completed, #2 low-pressure cylinder stops, and #1 low-pressure cylinder generates electricity with full load and high load output.

[0152] Using this control method for unit peak shaving has high flexibility, wide peak shaving depth, good safety and economy, and can realize peak shaving in the low load range of about 20% - 5%.

[0153] The steam turbine unit of this design scheme can be deeply adjusted to the load range of about 20% - 5%; when operating at low load for peak shaving, there is a minimum cooling flow in #1 low-pressure cylinder to ensure safe operation; the small-volume flow steam always flows axially and expands to do work in #2 low-pressure cylinder, which can effectively avoid problems such as air blowing, overheating, water erosion and flutter in the low-pressure cylinder, and the steam inlet volume of the low-pressure cylinder is relatively matched with the flow passage of #2 low-pressure cylinder, and the unit has high economy.

[0154] Specifically, in an embodiment of the present application, as Figure 4, the high-pressure cylinder rotor, the intermediate-pressure cylinder rotor, the first-class low-pressure cylinder rotor, and the rotor of Generator I are connected and arranged on Shaft I; the second-class low-pressure cylinder rotor is connected to the rotor of Generator I and arranged on Shaft I.

[0155] Two steam guide pipes are arranged between the exhaust steam of the intermediate-pressure cylinder and the first-class low-pressure cylinder, and they have different specifications; the steam guide pipe with a larger specification is used for the intermediate-low pressure connecting pipe, and a connecting pipe butterfly valve is set; a regulating valve for the first-class low-pressure cylinder is set on the steam guide pipe with a smaller specification.

[0156] A steam guide pipe is arranged between the exhaust steam of the intermediate-pressure cylinder and the second-class low-pressure cylinder, and a regulating valve for the second-class low-pressure cylinder is set on the steam guide pipe.

[0157] When the steam turbine unit is in the non-peak shaving operation condition, the regulating valve of the first-class low-pressure cylinder is closed, the regulating valve of the second-class low-pressure cylinder is closed, the connecting pipe butterfly valve is fully open, and the high-pressure cylinder and the intermediate-pressure cylinder jointly output power with the first-class low-pressure cylinder, and Generator I generates electricity.

[0158] When the steam turbine unit is in the peak shaving operation condition, the connecting pipe butterfly valve is gradually closed, the regulating valve of the first-class low-pressure cylinder is gradually opened, the regulating valve of the second-class low-pressure cylinder is gradually opened, the first-class low-pressure cylinder enters the cut-off state of the minimum cooling steam flow, and the second-class low-pressure cylinder operates normally.

[0159] The shafting of the second-class low-pressure cylinder is independently arranged, and a clutch is set to connect and disconnect with the shafting of the high-pressure cylinder rotor, the intermediate-pressure cylinder rotor, and the first-class low-pressure cylinder rotor; when the steam turbine unit is in the peak shaving operation condition, after the second-class low-pressure cylinder reaches the rated speed, it is connected to the shafting of the high-pressure cylinder, the intermediate-pressure cylinder, and the first-class low-pressure cylinder through the clutch.

[0160] It has the following characteristics:

[0161] The design operating point of the #1 low-pressure cylinder is based on full load design, and the low-pressure flow path and exhaust area are large; the design operating point of the #2 low-pressure cylinder is based on low load design, and the low-pressure flow path and exhaust area are small.

[0162] The high-pressure cylinder rotor, the intermediate-pressure cylinder rotor, the #1 low-pressure cylinder rotor, and the generator rotor are connected and arranged on one shaft. Two steam guide pipes are arranged between the exhaust steam of the intermediate-pressure cylinder and the #1 low-pressure cylinder, one is a medium-low pressure connecting pipe with a larger specification, and the other is a steam guide pipe with a smaller specification. A connecting pipe butterfly valve is installed on the medium-low pressure connecting pipe, and a regulating valve for the #1 low-pressure cylinder is installed on the steam guide pipe with a smaller specification.

[0163] The #2 low-pressure cylinder is connected to the generator rotor and arranged on one shaft, and a steam guide pipe is arranged between the exhaust steam of the intermediate-pressure cylinder and the #2 low-pressure cylinder, and a regulating valve for the #2 low-pressure cylinder is installed on the steam guide pipe. The shafting of the #2 low-pressure cylinder is independently arranged, but it can realize the functions of connecting and disconnecting with the shafting of the high, intermediate, and #1 low-pressure cylinders through the clutch.

[0164] During high-load operation, i.e., under non-peak shaving operation conditions, the regulating valves of the #1 low-pressure cylinder are closed, the regulating valves of the #2 low-pressure cylinder are closed, the butterfly valve in the medium-low pressure connecting pipe is fully open, and the high-pressure cylinder and the medium-pressure cylinder jointly output power with the #1 low-pressure cylinder to generate electricity through a generator.

[0165] When peak shaving to low load is required, i.e., under peak shaving operation conditions, the connecting pipe butterfly valve is gradually closed, the regulating valve of the #1 low-pressure cylinder is gradually opened, and the regulating valve of the #2 low-pressure cylinder is gradually opened. After the #2 low-pressure cylinder reaches the rated speed, it is connected to the main shafts of the high-pressure, medium-pressure, and #1 low-pressure cylinders through a clutch. By adjusting the opening degrees of the #1 and #2 regulating valves, finally, the #1 low-pressure cylinder enters the state of minimum cooling steam flow cut-off, and the #2 low-pressure cylinder operates normally.

[0166] By adjusting the opening degrees of the #1 and #2 regulating valves, finally, the #1 low-pressure cylinder enters the operation state of minimum cooling steam flow cut-off, and the #2 low-pressure cylinder outputs power normally. When the unit needs to increase from low load to high load, the regulating valves of the #1 low-pressure cylinder and the #2 low-pressure cylinder are gradually adjusted smaller, and the connecting pipe butterfly valve is gradually opened. After the regulating valve of the #2 low-pressure cylinder is closed to a certain opening degree, the #2 low-pressure cylinder is disengaged from the high-pressure cylinder through a clutch. After the regulating valve of the #1 low-pressure cylinder is adjusted to a certain opening degree, the connecting pipe butterfly valve is quickly opened, the regulating valve of the #1 low-pressure cylinder is quickly closed, and the #1 low-pressure cylinder changes from the cut-off state to the power output state. The regulating valve of the #2 low-pressure cylinder continues to be closed smaller until it is closed, and the speed of the low-pressure cylinder gradually decreases until it stops. Through this start-up regulation, at high load or full load, the #2 low-pressure cylinder stops running, and the high-pressure cylinder and the medium-pressure cylinder jointly output power with the #1 low-pressure cylinder.

[0167] Using this control method for unit peak shaving has high flexibility, a wide peak shaving depth, good safety and economy, and can achieve peak shaving in the low-load range of about 20% - 5%.

[0168] The steam turbine unit of this design scheme can be deeply adjusted to the load range of about 20% - 5%; during low-load peak shaving operation, a minimum cooling flow is ensured in the #1 low-pressure cylinder, and it can operate safely. The small-volume flow steam always flows axially and expands to do work in the #2 low-pressure cylinder, which can effectively avoid problems such as drum wind, overheating, water erosion, and flutter in the low-pressure cylinder, and the steam inlet volume of the low-pressure cylinder is relatively well-matched with the flow passage of the #2 low-pressure cylinder, and the unit has high economy.

[0169] Specifically, in an embodiment of the present application, the design load point of the second-class low-pressure cylinder is 10% - 50% of the design load point of the first-class low-pressure cylinder, and the low-pressure flow passage and exhaust area of the second-class low-pressure cylinder are small.

[0170] Specifically, in an embodiment of the present application, during the switching process between the first-class low-pressure cylinder and the second-class low-pressure cylinder, the steam turbine unit does not perform warm-up.

[0171] Specifically, in an embodiment of the present application, when the steam turbine unit is operating under a non-peak shaving condition, the high-pressure cylinder, the intermediate-pressure cylinder, and the first type of low-pressure cylinder jointly generate power, and the load of the non-peak shaving operation condition of the steam turbine unit is greater than 50% of the rated load of the steam turbine unit;

[0172] When the steam turbine unit is operating under a peak shaving condition, the high-pressure cylinder, the intermediate-pressure cylinder, and the second type of low-pressure cylinder jointly generate power, and the load of the peak shaving operation condition of the steam turbine unit is 5%-50% of the rated load of the steam turbine unit.

[0173] Specifically, in an embodiment of the present application, as shown in Figure 1 , in Scheme 1, the unit adopts a two-shaft design. The second type of low-pressure cylinder (#2 low-pressure cylinder), the high-pressure cylinder, the intermediate-pressure cylinder, and the first generator are coaxial. The first type of low-pressure cylinder (#1 low-pressure cylinder) and the second generator are coaxial. The #2 low-pressure cylinder is arranged at the head position of the high-pressure cylinder and is connected and disengaged from the high-pressure cylinder through a clutch. The intermediate-pressure exhaust steam is respectively connected to the #1 low-pressure cylinder and the #2 low-pressure cylinder through the #1 low-pressure cylinder regulating valve and the #2 low-pressure cylinder regulating valve. During non-peak shaving operation, the high-pressure cylinder, the intermediate-pressure cylinder, and the #1 low-pressure cylinder are connected in series for operation; during peak shaving operation, the high-pressure cylinder, the intermediate-pressure cylinder, and the #2 low-pressure cylinder are connected in series for operation.

[0174] Specifically, in an embodiment of the present application, as shown in Figure 2 , in Scheme 2: The unit adopts a three-shaft design. The high-pressure cylinder, the intermediate-pressure cylinder, and the first generator are coaxial. The first type of low-pressure cylinder (#1 low-pressure cylinder) is coaxial with the second generator, and the second type of low-pressure cylinder (#2 low-pressure cylinder) is coaxial with the third generator. The intermediate-pressure exhaust steam is respectively connected to the first type of low-pressure cylinder and the second type of low-pressure cylinder through the #1 low-pressure cylinder regulating valve and the #2 low-pressure cylinder regulating valve. During non-peak shaving operation, the high-pressure cylinder, the intermediate-pressure cylinder, and the #1 low-pressure cylinder are connected in series for operation; during peak shaving operation, the high-pressure cylinder, the intermediate-pressure cylinder, and the #2 low-pressure cylinder are connected in series for operation.

[0175] Specifically, in an embodiment of the present application, as shown in Figure 3 , in Scheme 3: The unit adopts a two-shaft design. The high-pressure cylinder, the intermediate-pressure cylinder, the first type of low-pressure cylinder (#1 low-pressure cylinder), and the first generator are coaxial. The second type of low-pressure cylinder (#2 low-pressure cylinder) is coaxial with the second generator. The intermediate-pressure exhaust steam is connected in parallel with the first type of low-pressure cylinder through a connecting pipe butterfly valve and the #1 low-pressure cylinder regulating valve. The intermediate-pressure exhaust steam is connected to the second type of low-pressure cylinder through the #2 low-pressure cylinder regulating valve. During non-peak shaving operation, the high-pressure cylinder, the intermediate-pressure cylinder, and the #1 low-pressure cylinder are connected in series for operation; during peak shaving operation, the high-pressure cylinder, the intermediate-pressure cylinder, and the #2 low-pressure cylinder are connected in series for operation.

[0176] Specifically, in an embodiment of the present application, as shown in Figure 4, Solution 4: The unit adopts a single-shaft design. The second-class low-pressure cylinder (#2 low-pressure cylinder), high-pressure cylinder, intermediate-pressure cylinder, and first-class low-pressure cylinder are coaxial, and the second-class low-pressure cylinder (#1 low-pressure cylinder) and the generator are coaxial. The second-class low-pressure cylinder is arranged at the front end of the high-pressure cylinder and is connected and disengaged from the high-pressure cylinder through a clutch. The intermediate-pressure cylinder and the first-class low-pressure cylinder are connected in parallel through a connecting pipe butterfly valve and the #1 low-pressure cylinder regulating valve. The intermediate-pressure cylinder and the second-class low-pressure cylinder are connected in series through the #2 low-pressure cylinder regulating valve. During non-peak shaving operation, the high-pressure cylinder, intermediate-pressure cylinder, and #1 low-pressure cylinder are connected in series for operation; during peak shaving operation, the high-pressure cylinder, intermediate-pressure cylinder, and #2 low-pressure cylinder are connected in series for operation.

[0177] Specifically, in an embodiment of the present application, during the startup and wide-load operation of the unit, it is necessary to operate according to the formulated operation method:

[0178] Such as Figure 1Solution 1: S1: Disconnect the clutch between the second-class low-pressure cylinder and the high-pressure cylinder; S2: Close the regulating valve of the #2 low-pressure cylinder and open the regulating valve of the #1 low-pressure cylinder; S3: The high-pressure cylinder, intermediate-pressure cylinder, and #1 low-pressure cylinder are connected in series for barring gear operation, raising to the rated speed, and raising to the rated load; S4: When the unit needs deep peak shaving, by reducing the steam outlet parameter of the boiler and the steam flow rate into the steam turbine, reduce the loads of the high-pressure cylinder, intermediate-pressure cylinder, and first-class low-pressure cylinder to 30%-50% of the rated load; S5: Perform barring gear operation on the second-class low-pressure cylinder; S6: Gradually open the regulating valve of the #2 low-pressure cylinder to enable the #2 low-pressure cylinder to quickly raise to the rated speed; S7: Connect the second-class low-pressure cylinder and the high-pressure cylinder shafting through the clutch; S8: Gradually open the regulating valve of the #2 low-pressure cylinder and gradually close the regulating valve of the #1 low-pressure cylinder, finally achieving that the first-class low-pressure cylinder does not admit steam and the intermediate-pressure exhaust completely enters the second-class low-pressure cylinder; S9: Reduce the loads of the high-pressure cylinder, intermediate-pressure cylinder, and second-class low-pressure cylinder to the 5%-20% rated load position to enable the unit to operate safely, economically, and for peak shaving; S10: When the unit needs to switch from deep peak shaving to non-peak shaving operation, raise the loads of the high-pressure cylinder, intermediate-pressure cylinder, and second-class low-pressure cylinder to the 30%-50% load point; S11: Perform barring gear operation on the first-class low-pressure cylinder, then gradually open the regulating valve of the #1 low-pressure cylinder and gradually close the regulating valve of the #2 low-pressure cylinder to achieve raising the first-class low-pressure cylinder to the rated speed and raising the load, and the second-class low-pressure cylinder cuts off the load and reaches the rated speed; S12: Disconnect the second-class low-pressure cylinder from the high-pressure cylinder through the clutch, further close the regulating valve of the #2 low-pressure cylinder, and stop the operation of the second-class low-pressure cylinder; S13: Raise the steam parameter of the boiler and the steam flow rate into the steam turbine, and raise the loads of the high-pressure cylinder, intermediate-pressure cylinder, and first-class low-pressure cylinder to high load or full load; S11: When the unit shuts down from the non-peak shaving condition, reduce the steam parameter of the boiler and the steam inlet volume of the steam turbine, so that the high-pressure cylinder, intermediate-pressure cylinder, and first-class low-pressure cylinder gradually reduce the load to 0 and reduce the speed to the barring gear speed or 0 speed; S12: When the unit shuts down from the peak shaving condition, reduce the steam parameter of the boiler and the steam inlet volume of the steam turbine, so that the high-pressure cylinder, intermediate-pressure cylinder, and second-class low-pressure cylinder gradually reduce the load to 0 and reduce the speed to the barring gear speed, and then operate the clutch to disconnect the second-class low-pressure cylinder from the high-pressure cylinder.

[0179] Specifically, in an embodiment of the present application, during the startup and wide-load operation of the unit, it is necessary to operate according to the formulated operation method:

[0180] As attached Figure 2, Plan 2: S1: Close the regulating valve of the #2 low-pressure cylinder and open the regulating valve of the #1 low-pressure cylinder to turn the turbine's high-pressure cylinder, intermediate-pressure cylinder, and the first type of low-pressure cylinder; S2: Start the turbine to make the turbine's high-pressure cylinder, intermediate-pressure cylinder, and the first type of low-pressure cylinder reach the rated speed and the rated load; S3: When the unit needs deep peak shaving, by reducing the boiler steam parameters and the steam flow rate into the turbine, make the combined output load of the turbine's high-pressure cylinder, intermediate-pressure cylinder, and the first type of low-pressure cylinder decrease to 30%-50% of the load; S4: Gradually open the regulating valve of the #2 low-pressure cylinder to full open, gradually close the regulating valve of the #1 low-pressure cylinder to fully closed, the output load of the first type of low-pressure cylinder gradually decreases to 0, gradually reduce the speed from the rated speed to the turning speed or 0 speed, the second type of low-pressure cylinder gradually increases the speed from the turning speed to the rated speed, and then gradually increases the load; S5: Continue to reduce the boiler steam parameters and the steam intake of the turbine, and further reduce the load of the high-pressure cylinder, intermediate-pressure cylinder, and the second type of low-pressure cylinder to the deep peak shaving load position of 5%-20% to make the unit operate safely, economically, and for peak shaving; S6: When the unit needs non-peak shaving operation, increase the boiler steam parameters and the steam intake of the turbine, and increase the load of the high-pressure cylinder, intermediate-pressure cylinder, and the second type of low-pressure cylinder to 30%-50% of the load for operation; S7: Turn the #1 low-pressure cylinder, then gradually close the regulating valve of the #2 low-pressure cylinder to fully closed, gradually open the regulating valve of the #1 low-pressure cylinder to full open, make the output load of the second type of low-pressure cylinder decrease to 0, reduce the speed to the turning speed or 0 speed, make the first type of low-pressure cylinder increase the speed from the turning speed to the rated speed, and then increase the load; S8: Continue to increase the boiler steam parameters and the steam intake of the turbine, and increase the load of the high-pressure cylinder, intermediate-pressure cylinder, and the first type of low-pressure cylinder to the high load or full load to achieve non-peak shaving operation. S9: When the unit shuts down from the non-peak shaving condition, reduce the boiler steam parameters and the steam intake of the turbine to make the high-pressure cylinder, intermediate-pressure cylinder, and the first type of low-pressure cylinder gradually reduce the load to 0 and reduce the speed to the turning speed or 0 speed; S10: When the unit shuts down from the peak shaving condition, reduce the boiler steam parameters and the steam intake of the turbine to make the high-pressure cylinder, intermediate-pressure cylinder, and the second type of low-pressure cylinder gradually reduce the load to 0 and reduce the speed to the turning speed or 0 speed.

[0181] Specifically, in an embodiment of the present application, during the startup and wide-load operation of the unit, it is necessary to operate according to the formulated operation method:

[0182] As attached Figure 3, Scheme 3: S1: Close the regulating valve of the #2 low-pressure cylinder, close the regulating valve of the #1 low-pressure cylinder, fully open the butterfly valve of the connecting pipe, start the high-pressure cylinder, intermediate-pressure cylinder and the first type of low-pressure cylinder, realize barring gear operation, increase to the rated speed, and increase to the rated load for operation; S2: When deep peak shaving operation is required, reduce the boiler steam parameters and the steam inlet volume of the steam turbine, and reduce the combined output of the high-pressure cylinder, intermediate-pressure cylinder and low-pressure cylinder to 30%-50% load; S3: Perform barring gear operation on the second type of low-pressure cylinder, then gradually open the regulating valve of the #2 low-pressure cylinder and gradually close the butterfly valve of the connecting pipe to realize the load reduction of the #1 low-pressure cylinder and the speed increase and load increase of the #2 low-pressure cylinder; S4: Further close the butterfly valve of the connecting pipe until it is fully closed, and gradually open the regulating valve of the #1 low-pressure cylinder to the specified opening to realize the zero output operation of the minimum cooling flow of the first type of low-pressure cylinder; S5: Further reduce the main steam of the boiler and the steam inlet volume of the steam turbine, and reduce the output of the high-pressure cylinder, intermediate-pressure cylinder and the second type of low-pressure cylinder to the deep peak shaving load position of 5%-20% to make the unit operate safely, economically and with peak shaving; S6: When the unit needs non-peak shaving operation, increase the boiler steam parameters and the steam inlet volume of the steam turbine to realize the output of the high-pressure cylinder, intermediate-pressure cylinder and the second type of low-pressure cylinder to the 30%-50% load position; S7: Gradually close the regulating valve of the #2 low-pressure cylinder and the regulating valve of the #1 low-pressure cylinder until they are fully closed, and gradually open the butterfly valve of the connecting pipe until it is fully open to realize the load reduction of the second type of low-pressure cylinder to 0, reduce the speed from the rated speed to the barring gear speed or 0 speed, and realize the operation of the first type of low-pressure cylinder from the zero output of the minimum cooling flow to the load-bearing operation; S8: Increase the boiler steam parameters and the steam inlet volume of the steam turbine, and further increase the output load of the high-pressure cylinder, intermediate-pressure cylinder and the first type of low-pressure cylinder until full load operation after high load to realize the non-peak shaving operation of the unit. S9: When the unit stops from the non-peak shaving condition, reduce the boiler steam parameters and the steam inlet volume of the steam turbine, so that the high-pressure cylinder, intermediate-pressure cylinder and the first type of low-pressure cylinder gradually reduce the load to 0 and reduce the speed to the barring gear speed or 0 speed; S10: When the unit stops from the peak shaving condition, reduce the boiler steam parameters and the steam inlet volume of the steam turbine, so that the high-pressure cylinder, intermediate-pressure cylinder and the second type of low-pressure cylinder gradually reduce the load to 0 and reduce the speed to the barring gear speed or 0 speed.

[0183] Specifically, in an embodiment of the present application, during the start-up and wide load operation of the unit, it is necessary to operate according to the formulated operation method:

[0184] Such as attached Figure 4, Solution 4: S1: Remove the unit clutch to separate the #2 low-pressure cylinder from the high-pressure cylinder; S2: Close the regulating valve of the #2 low-pressure cylinder, close the regulating valve of the #1 low-pressure cylinder, and fully open the butterfly valve of the connecting pipe; S3: Turn the high-pressure cylinder, intermediate-pressure cylinder, and the first type of low-pressure cylinder for barring, and then increase to the rated speed and run at the rated load; S4: When the unit needs to operate in deep peak shaving, reduce the boiler steam parameters and the steam inlet volume of the steam turbine, and reduce the combined output of the high-pressure cylinder, intermediate-pressure cylinder, and the first type of low-pressure cylinder to operate at 30%-50% of the load; S5: Turn the second type of low-pressure cylinder for barring, and then gradually open the regulating valve of the #2 low-pressure cylinder to make the second type of low-pressure cylinder increase to the rated speed; S6: Connect the second type of low-pressure cylinder and the high-pressure cylinder through the clutch; S7: Open the regulating valve of the #2 low-pressure cylinder to full open, gradually close the butterfly valve of the connecting pipe to full close, and open the regulating valve of the #1 low-pressure cylinder to a certain opening to achieve the second type of low-pressure cylinder running with load and the first type of low-pressure cylinder running with zero output at the minimum cooling flow rate; S8: Further reduce the main steam of the boiler and the steam inlet volume of the steam turbine, and reduce the output of the high-pressure cylinder, intermediate-pressure cylinder, and the second type of low-pressure cylinder to the deep peak shaving load position of 5%-20% to make the unit operate safely, economically, and with peak shaving; S9: When the unit needs to operate without peak shaving, increase the boiler steam parameters and the steam inlet volume of the steam turbine to achieve the output of the high-pressure cylinder, intermediate-pressure cylinder, and the second type of low-pressure cylinder to the load position of 30%-50%; S10: Gradually close the regulating valve of the #2 low-pressure cylinder and the regulating valve of the #1 low-pressure cylinder to full close, and gradually open the butterfly valve of the connecting pipe to full open to achieve the second type of low-pressure cylinder to reduce the load to 0 and operate at the rated speed, and achieve the first type of low-pressure cylinder to change from zero output at the minimum cooling flow rate to running with load; S11: Operate the clutch to disconnect the second type of low-pressure cylinder from the high-pressure cylinder, and close the regulating valve of the #2 low-pressure cylinder to full close to make the second type of low-pressure cylinder reduce from the rated speed to the barring speed or 0 speed; S12: Increase the boiler steam parameters and the steam inlet volume of the steam turbine, and further increase the output load of the high-pressure cylinder, intermediate-pressure cylinder, and the first type of low-pressure cylinder until running at full load after high load to achieve the unit operating without peak shaving. S11: When the unit stops from the non-peak shaving condition, reduce the boiler steam parameters and the steam inlet volume of the steam turbine to gradually reduce the load of the high-pressure cylinder, intermediate-pressure cylinder, and the first type of low-pressure cylinder to 0 and reduce the speed to the barring speed or 0 speed; S12: When the unit stops from the peak shaving condition, reduce the boiler steam parameters and the steam inlet volume of the steam turbine to gradually reduce the load of the high-pressure cylinder, intermediate-pressure cylinder, and the second type of low-pressure cylinder to 0, reduce the speeds of the high-pressure cylinder, intermediate-pressure cylinder, and the first and second types of low-pressure cylinders to the barring speed, and then operate the clutch to disconnect the second type of low-pressure cylinder from the high-pressure cylinder.

[0185] Generally speaking: The present invention aims to solve the problem of deep peak shaving of steam turbine units. Two or more low-pressure cylinders are designed. The large low-pressure cylinder is designed based on the full-load design operating point of the unit, and the small low-pressure cylinder is designed based on the deep peak shaving requirements. The design load point of the small low-pressure cylinder is usually 10%-50% of the design operating point of the large high-pressure cylinder. At high load, the large low-pressure cylinder is coupled with the high-pressure and intermediate-pressure cylinders for power generation. At low load, the large low-pressure cylinder is removed, and the small low-pressure cylinder is used to be coupled with the high-pressure and intermediate-pressure cylinders for power generation.

[0186] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and replacements can be made, and these improvements and replacements should also be regarded as the protection scope of the present invention.

Claims

1. A wide load operation method for a steam turbine unit, characterized in that: The wide load operating conditions of the steam turbine unit include peak load operation conditions and non-peak load operation conditions, and meet the following requirements: The load of the steam turbine unit under peak load regulation operation is x% of the rated load of the steam turbine unit, the combined output of the high pressure cylinder, the medium pressure cylinder and the second type of low pressure cylinder, 5≦x <a; The load of the non-peak load operation condition of the steam turbine unit is y% of the rated load of the steam turbine unit, the combined output of the high-pressure cylinder, the medium-pressure cylinder and a type of low-pressure cylinder, a≦y≦110; a is the peak load point from high load to low load of the steam turbine unit, 20≦a≦60; The steps of switching the steam turbine unit between the peak load operation condition and the non-peak load operation condition include: The non-peak-shaving operating condition is switched to the peak-shaving operating condition: the first-class low-pressure cylinder gradually reduces the steam flow to shut down or gradually reduces it to maintain the minimum cooling flow condition, and the second-class low-pressure cylinder gradually increases the steam flow to the rated speed and rated load condition; The peak-shaving operation condition is switched to the non-peak-shaving operation condition: the first-class low-pressure cylinder gradually increases the steam flow to the rated speed and rated load condition, and the second-class low-pressure cylinder gradually reduces the steam flow to shutdown.

2. A wide load operation method for a steam turbine unit according to claim 1, characterized in that: In non-peak-shaving operation conditions, the first-class low-pressure cylinder is connected to the shaft system of the high-pressure cylinder and the intermediate-pressure cylinder, and the second-class low-pressure cylinder is separated from the shaft system of the high-pressure cylinder and the intermediate-pressure cylinder; In the peak load operation condition, the first type of low-pressure cylinder is separated from the shaft system of the high-pressure cylinder and the intermediate-pressure cylinder, and the second type of low-pressure cylinder is connected to the shaft system of the high-pressure cylinder and the intermediate-pressure cylinder; The first type low-pressure cylinder and the second type low-pressure cylinder are started, operated under wide load and shut down through valves arranged on the steam inlet pipe or clutches on the shaft system.

3. A wide load operation method for a steam turbine unit according to claim 1, characterized in that: A type I low-pressure cylinder regulating valve is arranged on the inlet pipeline of the type I low-pressure cylinder, and a type II low-pressure cylinder regulating valve is arranged on the inlet pipeline of the type II low-pressure cylinder.

4. A wide load operation method for a steam turbine unit as claimed in claim 1, characterized in that: When the steam turbine unit switches from a non-peak-shaving operating condition to a peak-shaving operating condition, the regulating valve of the first type of low-pressure cylinder is gradually closed, and the regulating valve of the second type of low-pressure cylinder is gradually opened; when the steam turbine unit switches from a peak-shaving operating condition to a non-peak-shaving operating condition, the regulating valve of the second type of low-pressure cylinder is gradually closed, and the regulating valve of the first type of low-pressure cylinder is gradually opened.

5. A wide load operation method for a steam turbine unit as claimed in claim 2, characterized in that: The second type of low-pressure cylinder is arranged in front of the high-pressure cylinder and is equipped with a clutch for connecting or disconnecting the shaft system of the high-pressure cylinder and the medium-pressure cylinder.

6. A wide load operation method for a steam turbine unit as claimed in claim 4, characterized in that: After the second-class low-pressure cylinder reaches the rated speed, it is connected to the main shaft of the high-pressure cylinder and the medium-pressure cylinder through the clutch, the first-class low-pressure cylinder regulating valve is closed, the first-class low-pressure cylinder is cut off, and the second-class low-pressure cylinder regulating valve is opened, so that the medium-pressure exhaust steam enters the second-class low-pressure cylinder and completes the grid connection.

7. A wide load operation method for a steam turbine unit as claimed in claim 1, characterized in that: The high-pressure cylinder rotor and the medium-pressure cylinder rotor are connected, arranged on shaft I, and connected to generator I; the first-class low-pressure cylinder rotor is independently arranged, arranged on shaft II, and connected to generator II; the second-class low-pressure cylinder rotor shaft is connected and separated from the high-pressure cylinder rotor shaft system and the medium-pressure cylinder rotor shaft system through a clutch; shaft I and shaft II are not arranged on the same axis; the second-class low-pressure cylinder shaft system is independently arranged, and a clutch is provided for connecting and disconnecting with the high-pressure cylinder rotor, the medium-pressure cylinder rotor, and the shaft system of the first-class low-pressure cylinder rotor; When the steam turbine unit is in non-peak-shaving operation, the clutch is disengaged, the regulating valve of the second-class low-pressure cylinder is closed, and the second-class low-pressure cylinder is shut down; the regulating valve of the first-class low-pressure cylinder is opened, and the first-class low-pressure cylinder is operated in conjunction with the high-pressure cylinder and the medium-pressure cylinder, and the generators I and II are used for power generation; When the turbine is in peak load regulation operation, the regulating valve of the first type low-pressure cylinder is gradually closed, and the first type low-pressure cylinder gradually reduces the load and speed to the cranking speed or stops; the regulating valve of the second type low-pressure cylinder is gradually opened, the second type low-pressure cylinder is started and increases to the rated speed, the clutch is engaged, the second type low-pressure cylinder is connected to the high-pressure cylinder for output, and the generator I is used for power generation; The unit completes the startup, wide-load operation and shutdown of the unit by disengaging or engaging the clutch and opening or closing the first-class low-pressure cylinder regulating valve and the second-class low-pressure cylinder regulating valve.

8. A wide load operation method for a steam turbine unit as claimed in claim 1, characterized in that: The high-pressure cylinder rotor and the medium-pressure cylinder rotor are connected, arranged on shaft I, and connected to generator I; the first-class low-pressure cylinder rotor is independently arranged, arranged on shaft II, and connected to generator II; the second-class low-pressure cylinder rotor is arranged on shaft III, and connected to generator III; shaft I, shaft II, and shaft III are not arranged on the same axis; When the steam turbine unit is in non-peak-shaving operation, the regulating valve of the second-class low-pressure cylinder is closed and the second-class low-pressure cylinder is shut down; the regulating valve of the first-class low-pressure cylinder is opened, the speed and load of the first-class low-pressure cylinder are increased, the first-class low-pressure cylinder is combined with the high-pressure cylinder and the medium-pressure cylinder to output power, and the generators I and II are used to generate electricity; When the steam turbine unit is in peak load regulation operation, close the first-class low-pressure cylinder regulating valve, reduce the load and speed of the first-class low-pressure cylinder to the cranking speed or shut down; open the second-class low-pressure cylinder regulating valve, increase the speed of the second-class low-pressure cylinder to the rated speed, increase the load to the peak load, and generators I and III are used for power generation; The unit completes startup, wide-load operation and shutdown by opening or closing the first and second type low-pressure cylinder regulating valves.

9. A wide load operation method for a steam turbine unit as claimed in claim 1, characterized in that: The high-pressure cylinder rotor, the medium-pressure cylinder rotor, the first-class low-pressure cylinder rotor and the rotor of the generator I are connected and arranged on shaft I; the second-class low-pressure cylinder rotor is connected to the rotor of the generator II and arranged on shaft II; shaft I and shaft II are not arranged on the same axis; Two steam pipes with different specifications are arranged between the exhaust of the medium-pressure cylinder and the first-class low-pressure cylinder; the larger steam pipe is used as the medium-low pressure connecting pipe, and a connecting pipe butterfly valve is set; the smaller steam pipe is equipped with a regulating valve for the first-class low-pressure cylinder; A steam pipe is arranged between the exhaust steam of the intermediate pressure cylinder and the second type of low pressure cylinder, and a regulating valve of the second type of low pressure cylinder is arranged on the steam pipe; when the steam turbine unit is in non-peak-shaving operation condition, the regulating valve of the second type of low pressure cylinder is closed and the second type of low pressure cylinder is shut down; the butterfly valve of the connecting pipe of the first type of low pressure cylinder is fully opened, the regulating valve of the first type of low pressure cylinder is closed, the first type of low pressure cylinder and the high pressure cylinder and the intermediate pressure cylinder jointly output, and the generator I generates electricity; When the steam turbine unit is in peak load regulation operation, the butterfly valve of the connecting pipe of the first type low pressure cylinder is gradually closed, the regulating valve of the first type low pressure cylinder is gradually opened, the first type low pressure cylinder gradually reduces the load and enters the cut-off state of the minimum cooling steam flow, the regulating valve of the second type low pressure cylinder is gradually opened, the second type low pressure cylinder increases the rated speed and peak load from zero speed or cranking speed, and generators I and II generate electricity; The unit completes startup, wide-load operation and shutdown by opening or closing the first and second type low-pressure cylinder regulating valves and connecting pipe butterfly valves.

10. A wide load operation method for a steam turbine unit according to claim 1, characterized in that: The high-pressure cylinder rotor, the medium-pressure cylinder rotor, the first-class low-pressure cylinder rotor and the rotor of the generator I are connected and arranged on the shaft I; the second-class low-pressure cylinder rotor is connected to the rotor of the generator I and arranged on the shaft I; Two steam pipes with different specifications are arranged between the exhaust of the medium-pressure cylinder and the first-class low-pressure cylinder; the larger steam pipe is used as the medium-low pressure connecting pipe, and a connecting pipe butterfly valve is set; the smaller steam pipe is equipped with a regulating valve for the first-class low-pressure cylinder; A steam pipe is arranged between the exhaust steam of the intermediate pressure cylinder and the second type of low pressure cylinder, and a regulating valve of the second type of low pressure cylinder is arranged on the steam pipe; The shaft system of the second-class low-pressure cylinder is arranged independently, and a clutch is provided for connecting and disconnecting with the shaft systems of the high-pressure cylinder rotor, the medium-pressure cylinder rotor, and the first-class low-pressure cylinder rotor; when the steam turbine unit is in non-peak-shaving operation condition, the butterfly valve of the first-class low-pressure cylinder connecting pipe is fully opened, the regulating valve of the first-class low-pressure cylinder is closed, the regulating valve of the second-class low-pressure cylinder is closed, the clutch between the second-class low-pressure cylinder and the high-pressure cylinder is disengaged, the second-class low-pressure cylinder is shut down, the high-pressure cylinder and the medium-pressure cylinder are combined with the first-class low-pressure cylinder to output, and the generator I generates electricity; When the steam turbine unit is in peak load operation, the butterfly valve of the first type low pressure cylinder connecting pipe is gradually closed, the regulating valve of the first type low pressure cylinder is gradually opened, the regulating valve of the second type low pressure cylinder is gradually opened, the first type low pressure cylinder reduces the load and enters the cut-off state of the minimum cooling steam flow, the second type low pressure cylinder increases from zero speed or cranking speed to the rated speed, the second type low pressure cylinder clutch is engaged, the second type low pressure cylinder is connected with the high pressure cylinder and increases to the peak load generator I to generate electricity; The unit starts, runs at a wide load and shuts down by disengaging or engaging the clutch and opening or closing the first and second type low-pressure cylinder regulating valves and the connecting pipe butterfly valve.

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