Turbine three-cylinder micro-output system of circulating fluidized bed unit and regulation and control method

Abstract

The invention provides a circulating fluidized bed unit turbine three-cylinder micro-output system and a regulation and control method, and relates to the technical field of thermal power generation. The system comprises an overheating device used for supplying main steam to a high-pressure cylinder, and the main steam acts in the high-pressure cylinder and then becomes high-pressure exhaust steam to be exhausted; the adjacent machine steam supplementing device is used for supplying auxiliary steam to the high-pressure cylinder to do work in the high-pressure cylinder to become high-pressure exhaust steam to be exhausted; the reheating device is used for heating the high-pressure exhaust steam exhausted from the high-pressure cylinder, the high-pressure exhaust steam becomes first steam after being heated, the first steam is sent to the intermediate-pressure cylinder to do work to become intermediate-pressure exhaust steam, and the intermediate-pressure exhaust steam is exhausted from a steam exhaust port of the intermediate-pressure cylinder; the medium-pressure exhaust steam enters a low-pressure cylinder of the steam turbine through a medium-pressure exhaust steam pipeline to act and then becomes low-pressure exhaust steam to be exhausted; the high-pressure exhaust bypass is used for feeding high-pressure exhaust steam into the medium-pressure exhaust steam pipeline; and the recovery device is used for recovering the medium-pressure exhaust steam and the low-pressure exhaust steam. The problem that in the prior art, when a circulating fluidized bed unit operates in banking fire, a steam turbine cannot operate safely under the working condition of small volume flow is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation, in particular to a three-cylinder micro-output system of a steam turbine of a circulating fluidized bed unit and a three-cylinder micro-output control method of a steam turbine of a circulating fluidized bed unit. Background Art

[0002] At present, the deep peak regulation technology of thermal power units mainly achieves the dynamic balance of the power grid by deep load variation, thermal-electric decoupling or unit start-stop of 20% to 50% of the rated load of thermal power units. However, the peak regulation cost of thermal power units by start-stop is relatively high, and frequent start-stop will also affect the life of the unit. Thermoelectric decoupling technology is only suitable for extraction steam units during the heating period, and its application is relatively narrow. Deep load variation technology has become the main way for thermal power units to participate in flexible peak regulation. Since the circulating fluidized bed boiler in the thermal power unit has strong fuel adaptability, low pollutant control cost, stable combustion, and a large amount of bed material and refractory and wear-resistant materials, the thermal inertia is very large, so it has an inherent advantage in deep peak regulation. Therefore, deeply exploring the deep peak regulation capability of this type of unit is an important way to improve the overall deep peak regulation capability of thermal power units. The circulating fluidized bed boiler operates at a pressure-fire mode, which can greatly reduce the unit output to less than 5%, but the main and reheat steam temperatures of the boiler drop significantly due to the limitation of the boiler's evaporation capacity during pressure-fire operation, and the safe and stable operation of the steam turbine can be maintained for a short time, currently only about 1-2 hours. At the same time, during the compressed fire operation, the steam flow in the high-pressure cylinder of the turbine changes greatly, and the tail of the high-pressure cylinder may also produce a blasting condition, which is easy to cause overheating in the cylinder and deformation of the cylinder. At the same time, the long blades of the last stage and the second last stage of the low-pressure cylinder enter the small volume flow condition. Under the small volume flow condition, the long blades are separated, resulting in an increase in the temperature of the blast exhaust steam. In order to suppress the temperature increase, water spraying is used to cause water erosion of the blades. When the volume flow is reduced to 10-20%, the blades may induce flutter, endangering the safety of the turbine.

[0003] Therefore, there is an urgent need for a device that can solve at least one of the above problems. Summary of the invention

[0004] The purpose of the embodiment of the present invention is to provide a three-cylinder micro-output system for a circulating fluidized bed unit steam turbine, which is used to solve the problem in the prior art that the steam turbine of the circulating fluidized bed unit cannot operate safely under small volume flow conditions when the steam turbine is in low-volume flow operation during low-pressure operation.

[0005] In order to achieve the above-mentioned object, the present invention provides a three-cylinder micro-output system for a steam turbine of a circulating fluidized bed unit, comprising: The superheater is connected to the high-pressure cylinder of the steam turbine through the main pipeline and is used to supply main steam to the high-pressure cylinder. The main steam becomes high-pressure exhaust steam and is discharged after doing work in the high-pressure cylinder. The adjacent machine steam supplement device is connected to the high-pressure cylinder through a steam supplement pipeline. The adjacent machine steam supplement device is used to supply auxiliary steam to the high-pressure cylinder. The auxiliary steam becomes high-pressure exhaust steam and is discharged after doing work in the high-pressure cylinder. The reheating device is arranged between the exhaust port of the high-pressure cylinder and the steam inlet of the intermediate-pressure cylinder of the steam turbine, and is used to heat the high-pressure exhaust steam discharged from the high-pressure cylinder. After the high-pressure exhaust steam is heated, it becomes the first steam and is sent to the intermediate-pressure cylinder to do work to become the intermediate-pressure exhaust steam, and is discharged from the exhaust port of the intermediate-pressure cylinder; an intermediate-pressure exhaust steam pipeline is arranged between the exhaust port of the intermediate-pressure cylinder and the steam inlet of the low-pressure cylinder of the steam turbine, and the intermediate-pressure exhaust steam enters the low-pressure cylinder of the steam turbine through the intermediate-pressure exhaust steam pipeline, and becomes the low-pressure exhaust steam after doing work and is discharged; The high-pressure exhaust bypass is connected between the exhaust port of the high-pressure cylinder and the medium-pressure exhaust pipe, and is used to send the high-pressure exhaust steam into the medium-pressure exhaust pipe; The recovery device is connected to the exhaust port of the medium-pressure cylinder and the exhaust port of the low-pressure cylinder, and is used to recover the medium-pressure exhaust steam and the low-pressure exhaust steam.

[0006] Specifically, the system further comprises: an auxiliary bypass connected between the main pipeline and the reheat steam inlet of the reheat device, and used for sending the main steam into the reheat device for reheating.

[0007] Specifically, a first regulating valve and a first temperature and pressure reducing valve are sequentially arranged on the auxiliary bypass.

[0008] Specifically, a first check valve, a first electric isolation valve and a main steam regulating valve are sequentially arranged on the main pipeline along the flow direction of the main steam.

[0009] Specifically, a second electric isolation valve and a second check valve are sequentially arranged on the high-pressure exhaust bypass.

[0010] Specifically, the reheat device includes: a low-temperature reheater and a high-temperature reheater; The low-temperature inlet of the low-temperature reheater is connected to the exhaust port of the high-pressure cylinder through a pipeline, and the low-temperature reheater is used to preliminarily heat the high-pressure exhaust steam discharged from the high-pressure cylinder; The high-temperature inlet of the high-temperature reheater is connected to the low-temperature outlet of the low-temperature reheater, and the high-temperature outlet is connected to the steam inlet of the medium-pressure cylinder; the high-temperature reheater is used for secondary heating of the high-pressure exhaust steam discharged from the high-pressure cylinder to become the first steam, and the first steam is sent to the medium-pressure cylinder after being discharged from the high-temperature outlet of the high-temperature reheater.

[0011] Specifically, the system further includes: a steam extraction pipeline connected between a recovery inlet of the recovery device and a high-temperature outlet of the high-temperature reheater, and the first steam is transported to the recovery device through the steam extraction pipeline.

[0012] Specifically, a second electric isolation valve and a second temperature and pressure reduction valve are arranged on the steam extraction pipeline.

[0013] Specifically, the system further includes an auxiliary supplementary steam pipeline connected between the supplementary steam outlet of the adjacent machine supplementary steam device and the steam inlet of the intermediate pressure cylinder, and the auxiliary steam of the adjacent machine supplementary steam device is transported to the intermediate pressure cylinder through the auxiliary supplementary steam pipeline.

[0014] Specifically, along the flow direction of the auxiliary steam in the auxiliary supplementary steam pipeline, the auxiliary supplementary steam pipeline is provided with: a second regulating valve, a fourth electric isolation valve and a third check valve in sequence.

[0015] Specifically, a butterfly valve is arranged on the medium-pressure exhaust steam pipeline.

[0016] Another aspect of the present invention provides a method for controlling a three-cylinder micro-output system of a steam turbine of a circulating fluidized bed unit, which is implemented based on the three-cylinder micro-output system of a steam turbine of a circulating fluidized bed unit described in any one of the above items, and the control method comprises: Main steam is supplied to the high-pressure cylinder through the superheating device so that the high-pressure cylinder can do work. After the main steam does work, it becomes high-pressure exhaust steam and is discharged. Auxiliary steam is supplied to the high-pressure cylinder through the adjacent machine supplementary steam device so that the high-pressure cylinder can do work. After the auxiliary steam does work, it becomes high-pressure exhaust steam and is discharged. The high-pressure exhaust steam is heated to become the first steam, and the first steam is sent to the intermediate-pressure cylinder for the intermediate-pressure cylinder to do work. After the first steam does work, it becomes the intermediate-pressure exhaust steam and is discharged; The medium-pressure exhaust steam is sent to the low-pressure cylinder to perform work, and the medium-pressure exhaust steam becomes low-pressure exhaust steam after performing work and is discharged; The high-pressure exhaust steam is transported to the medium-pressure exhaust steam pipeline between the medium-pressure cylinder and the low-pressure cylinder so that the high-pressure exhaust steam and the medium-pressure exhaust steam are mixed and enter the low-pressure cylinder to work and then become low-pressure exhaust steam and be discharged; Recover the discharged medium-pressure exhaust steam and low-pressure exhaust steam.

[0017] The three-cylinder micro-output system and control method of the steam turbine of the circulating fluidized bed unit provided by the present invention supplies main steam to the high-pressure cylinder of the steam turbine through the superheating device, and can supply auxiliary steam to the high-pressure cylinder through the adjacent machine steam supplement device. In this way, during the compressed fire operation of the circulating fluidized bed unit, the auxiliary steam is transported to the high-pressure cylinder through the adjacent machine steam supplement device to supply the high-pressure cylinder with work. After the main steam and the auxiliary steam enter the high-pressure cylinder to do work, they become high-pressure exhaust steam and are discharged from the exhaust port of the high-pressure cylinder. After the high-pressure exhaust steam is heated by the reheating device, it is The temperature rises to become the first steam, and the first steam is sent to the medium-pressure cylinder to do work. After the first steam does work in the medium-pressure cylinder, it becomes medium-pressure exhaust steam and is discharged from the exhaust port of the medium-pressure cylinder. The discharged medium-pressure exhaust steam enters the low-pressure cylinder to do work and becomes low-pressure exhaust steam and is discharged from the exhaust port of the low-pressure cylinder. The low-pressure exhaust steam is sent to the recovery device for recovery. The high-pressure exhaust steam can be sent to the medium-pressure exhaust pipe through the high-exhaust bypass and mixed with the medium-pressure exhaust steam before entering the low-pressure cylinder to do work. In this way, the high-pressure cylinder, medium-pressure cylinder and low-pressure cylinder of the steam turbine achieve micro-output operation. The three-cylinder micro-output system and control method of the steam turbine of the circulating fluidized bed unit provided by the present invention supplements auxiliary steam to the high-pressure cylinder through the adjacent machine steam supplement device, and sends the high-pressure exhaust steam into the medium-pressure exhaust pipe, which solves the problem that the steam turbine of the circulating fluidized bed unit cannot operate safely under small volume flow conditions when the circulating fluidized bed unit is under pressure operation in the prior art, reduces the loss of working fluid, and improves the deep peak-shaving operation capability of the unit.

[0018] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings: Figure 1 The diagram is a layout diagram of a three-cylinder micro-output system of a steam turbine of a circulating fluidized bed unit provided by an embodiment of the present invention.

[0020] Description of Reference Numerals 1- High-pressure cylinder; 2- Medium-pressure cylinder; 3- Low-pressure cylinder; 5- Superheater; 6- High-temperature reheater; 7- Low-temperature reheater; 8- Recovery device; 9- High-pressure cylinder exhaust check valve; 10- Second electric isolation valve; 11- Second temperature reduction and pressure relief valve; 12- Fifth electric isolation valve; 13- Third temperature reduction and pressure relief valve; 14- Butterfly valve; 15- Main steam regulating valve; 16- First electric isolation valve; 17- First check valve; 18- Fourth regulating valve; 19- Seventh electric isolation valve; 20- Sixth check valve; 21- Second electric isolation valve; 22- Second check valve; 2 3-eighth electric isolating valve; 24-seventh check valve; 25-first regulating valve; 26-first temperature-reducing and pressure-reducing valve; 27-second regulating valve; 28-fourth electric isolating valve; 29-third check valve; 30-third regulating valve; 31-sixth electric isolating valve; 32-fifth check valve; 33-fifth electric isolating valve; 34-third temperature-reducing and pressure-reducing valve; 35-medium-pressure exhaust pipe; 36-steam drainage pipe; 37-drain expansion tank; 40-high-pressure exhaust bypass; 50-auxiliary bypass; 60-extraction pipe; 70-recovery pipe; 80-auxiliary steam supply pipe. DETAILED DESCRIPTION

[0021] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0022] Figure 1 Schematic diagram of the layout of the three-cylinder micro-output system of the steam turbine of the circulating fluidized bed unit. Figure 1 As shown, the present invention provides a three-cylinder micro-output system for a steam turbine of a circulating fluidized bed unit, and the three-cylinder micro-output system for a steam turbine of a circulating fluidized bed unit comprises: The superheating device 5 is connected to the high-pressure cylinder 1 of the steam turbine through a main pipeline and is used to supply main steam to the high-pressure cylinder 1. The main steam becomes high-pressure exhaust steam and is discharged after doing work in the high-pressure cylinder 1; The adjacent machine steam supplement device is connected to the high-pressure cylinder 1 through a steam supplement pipeline. The adjacent machine steam supplement device is used to supply auxiliary steam to the high-pressure cylinder 1. The auxiliary steam becomes high-pressure exhaust steam and is discharged after doing work in the high-pressure cylinder 1. The reheating device is arranged between the exhaust port of the high-pressure cylinder 1 and the steam inlet of the intermediate-pressure cylinder 2 of the steam turbine, and is used to heat the high-pressure exhaust steam discharged from the high-pressure cylinder 1. After the high-pressure exhaust steam is heated, it becomes the first steam and is sent to the intermediate-pressure cylinder 2 to do work to become the intermediate-pressure exhaust steam, and is discharged from the exhaust port of the intermediate-pressure cylinder 2; an intermediate-pressure exhaust steam pipeline 35 is arranged between the exhaust port of the intermediate-pressure cylinder 2 and the steam inlet of the low-pressure cylinder 3 of the steam turbine, and the intermediate-pressure exhaust steam enters the low-pressure cylinder 3 of the steam turbine through the intermediate-pressure exhaust steam pipeline 35, and becomes the low-pressure exhaust steam after doing work and is discharged; The high-pressure exhaust bypass 40 is connected between the exhaust port of the high-pressure cylinder 1 and the medium-pressure exhaust pipe 35, and is used to send the high-pressure exhaust steam into the medium-pressure exhaust pipe 35; The recovery device 8 is connected to the exhaust port of the medium-pressure cylinder 2 and the exhaust port of the low-pressure cylinder 3, and is used to recover the medium-pressure exhaust steam and the low-pressure exhaust steam.

[0023] The three-cylinder micro-output system of the steam turbine of the circulating fluidized bed unit provided by the present invention has a superheating device 5 that supplies main steam to the high-pressure cylinder 1 for the high-pressure cylinder 1 to do work. After the main steam does work, it becomes high-pressure exhaust steam and is discharged from the exhaust port of the high-pressure cylinder 1. The high-pressure exhaust steam is heated by the reheating device to become the first steam. The first steam enters the medium-pressure cylinder 2 to do work and becomes the medium-pressure exhaust steam. The medium-pressure exhaust steam enters the low-pressure cylinder 3 through the medium-pressure exhaust pipe 35 to do work and becomes the low-pressure exhaust steam. In order to ensure the safe operation of the unit during the fire suppression, a high-pressure exhaust bypass 40 is provided to transfer the high-pressure exhaust steam The high-pressure exhaust steam is sent to the medium-pressure exhaust steam pipeline 35 and mixed with the medium-pressure exhaust steam, and then enters the low-pressure cylinder 3 to perform work to become low-pressure exhaust steam. The high-pressure exhaust steam is not only sent to the medium-pressure cylinder 2 to perform work, but also sent to the low-pressure cylinder 3 through the high-exhaust bypass 40 to perform work, thereby realizing micro-output operation of the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder, improving the safety of the unit operation, solving the problem in the prior art that the steam turbine of the circulating fluidized bed unit cannot operate safely under small volume flow conditions during pressure operation, reducing the working fluid loss, and improving the unit's deep peak-shaving operation capability.

[0024] A recovery pipe 70 is arranged between the exhaust port of the medium-pressure cylinder 2 and the recovery intake port of the recovery device 8. The excess medium-pressure steam is sent to the recovery device 8 for recovery through the recovery pipe 70. The fifth electric isolation valve 12 and the third temperature and pressure reduction valve 13 are arranged in sequence on the recovery pipe 70. The fifth electric isolation valve 12 can control the flow state of the medium-pressure steam flowing through the recovery pipe 70, and the third temperature and pressure reduction valve 13 reduces the pressure of the medium-pressure steam flowing through the recovery pipe 70.

[0025] like Figure 1 As shown, the system further includes: an auxiliary bypass 50, connected between the main pipeline and the reheat steam inlet of the reheat device, for sending the main steam into the reheat device for reheating.

[0026] The first regulating valve 25 and the first temperature-reducing and pressure-reducing valve 26 are sequentially arranged on the auxiliary bypass 50 .

[0027] The first check valve 17 , the first electric isolation valve 16 and the main steam regulating valve 15 are arranged in sequence on the main pipeline along the flow direction of the main steam.

[0028] A second electric isolation valve 21 and a second check valve 22 are sequentially arranged on the high-pressure exhaust bypass 40 .

[0029] The reheat device comprises: a low temperature reheater 7 and a high temperature reheater 6; The low-temperature inlet of the low-temperature reheater 7 is connected to the exhaust port of the high-pressure cylinder 1 through a pipeline, and the low-temperature reheater 7 is used to preliminarily heat the high-pressure exhaust steam discharged from the high-pressure cylinder 1; The high-temperature inlet of the high-temperature reheater 6 is connected to the low-temperature outlet of the low-temperature reheater 7, and the high-temperature outlet is connected to the steam inlet of the intermediate-pressure cylinder 2; the high-temperature reheater 6 is used for secondary heating of the high-pressure exhaust steam discharged from the high-pressure cylinder 1 to become the first steam, and the first steam is discharged from the high-temperature outlet of the high-temperature reheater 6 and then sent to the intermediate-pressure cylinder 2.

[0030] The flow rate of the main steam flowing through the auxiliary bypass 50 is regulated by the first regulating valve 25 arranged on the auxiliary bypass 50, and the pressure of the main steam flowing through the auxiliary bypass 50 is regulated by the first temperature reduction and pressure reducing valve 26. After the main steam flows through the first regulating valve 25 and the first temperature reduction and pressure reducing valve 26, it enters the low-temperature reheater 7 and the high-temperature reheater 6 of the reheating device in sequence through the auxiliary bypass 50. After the main steam is heated by the low-temperature reheater 7 and the high-temperature reheater 6, it enters the intermediate pressure cylinder 2 through the steam inlet of the intermediate pressure cylinder 2 to become intermediate pressure exhaust steam after doing work. In order to control the flow rate of the main steam flowing to the high-pressure cylinder 1, a main steam regulating valve 15 is arranged on the main pipeline to regulate the flow rate of the main steam flowing to the high-pressure cylinder 1. The first check valve 17 can prevent the main steam from flowing back in the main pipeline. The first electric isolation valve 16 can control the flow state of the main steam in the main pipeline.

[0031] The main steam and auxiliary steam that have completed work in the high-pressure cylinder 1 become high-pressure exhaust steam, and the high-pressure exhaust steam can be transported to different steam-using components in three ways. In order to prevent the high-pressure exhaust steam from flowing back into the high-pressure cylinder 1, a high-pressure cylinder exhaust check valve 9 is arranged at the exhaust port of the high-pressure cylinder 1 to prevent the high-pressure exhaust steam from flowing back. The high-pressure exhaust steam can be sent to the reheat device, and after being heated by the low-temperature reheater 7 and the high-temperature reheater 6 of the reheat device, it becomes the first steam and then enters the medium-pressure cylinder 2 to do work. An eighth electric isolation valve 23 and a seventh check valve 24 are arranged in sequence on the pipeline between the exhaust port of the high-pressure cylinder 1 and the low-temperature inlet of the low-temperature reheater 7. The eighth electric isolation valve 23 controls the flow state of the high-pressure exhaust steam in the pipeline between the exhaust port of the high-pressure cylinder 1 and the low-temperature inlet of the low-temperature reheater 7, and the seventh check valve 24 prevents the high-pressure exhaust steam from flowing back into the pipeline between the exhaust port of the high-pressure cylinder 1 and the low-temperature inlet of the low-temperature reheater 7. The high-pressure exhaust steam flows back through the pipeline between the low-temperature inlet of the high-temperature reheater 7, and enters the high-temperature reheater 6 for secondary heating after preliminary heating by the low-temperature reheater 7. The high-pressure exhaust steam becomes the first steam after being added in sequence by the low-temperature reheater 7 and the high-temperature reheater 6. The third regulating valve 30, the sixth electric isolating valve 31 and the fifth check valve 32 are sequentially arranged on the connecting pipeline between the high-temperature outlet of the high-temperature reheater 6 and the steam inlet of the medium-pressure cylinder 2. The third regulating valve 30 regulates the flow rate of the first steam in the connecting pipeline between the high-temperature outlet of the high-temperature reheater 6 and the steam inlet of the medium-pressure cylinder 2. The sixth electric isolating valve 31 controls the flow state of the first steam in the connecting pipeline between the high-temperature outlet of the high-temperature reheater 6 and the steam inlet of the medium-pressure cylinder 2. The fifth check valve 32 prevents the first steam from flowing back through the connecting pipeline between the high-temperature outlet of the high-temperature reheater 6 and the steam inlet of the medium-pressure cylinder 2. High-pressure exhaust steam can also be sent into the medium-pressure exhaust steam pipeline 35 and mixed with the medium-pressure exhaust steam before entering the low-pressure cylinder 3 to perform work. The second electric isolation valve 21 arranged on the high-pressure exhaust bypass 40 can control the flow state of the high-pressure exhaust steam in the high-pressure exhaust bypass 40, and the second check valve 22 arranged on the high-pressure exhaust bypass 40 can prevent the high-pressure exhaust steam from flowing back in the high-pressure exhaust bypass 40; the high-pressure exhaust steam can also enter the hydrophobic expansion tank 37 through the steam evacuation pipeline 36, and the fifth electric isolation valve 33 and the third temperature reduction and pressure reducing valve 34 are arranged on the steam evacuation pipeline 36 in sequence. The fifth electric isolation valve 33 can control the flow state of the high-pressure exhaust steam in the steam evacuation pipeline 36, and the third temperature reduction and pressure reducing valve 34 can prevent the high-pressure exhaust steam from flowing back in the steam evacuation pipeline 36.

[0032] When the unit is in pressure operation, the adjacent steam supply device is switched to deliver auxiliary steam to the high-pressure cylinder 1. When the unit is in pressure operation, the main steam is controlled to enter the reheat device through the auxiliary bypass 50 by adjusting the main steam regulating valve 15, the first electric isolation valve 16, the first regulating valve 25 and the first temperature reduction and pressure reducing valve 26. When the unit is in pressure operation, the steam entering the high-pressure cylinder is mainly provided by the adjacent steam supply device. The steam source of the adjacent steam supply device can come from the adjacent main steam, the adjacent reheat steam or the electric boiler steam. The temperature of the auxiliary steam provided by the adjacent steam supply device is high, which can reduce the cold steam of the unit boiler entering the steam turbine system during pressure operation. When the unit is in the compressed fire operation mode, the high-pressure cylinder 1 can adopt the unit startup operation mode, and the high-pressure exhaust steam of the high-pressure cylinder 1 is directly discharged into the drain expansion tank 37. At this time, the unit has the conditions for micro-output operation. In order to prevent leakage from the pipeline from the high-pressure cylinder exhaust steam to the drain expansion tank when the compressed fire operation is frequent and to improve the reliability of the system, it is necessary to install the fifth electric isolation valve 33 and the third temperature and pressure reduction valve 34 on the steam drainage pipeline 36 between the high-pressure cylinder 1 and the drain expansion tank 37.

[0033] When the unit is running under pressure, the adjacent unit's supplementary steam device delivers auxiliary steam to the high-pressure cylinder 1 through the supplementary steam pipeline. Figure 1 As shown, one end of the supplementary steam pipeline is connected to the supplementary steam device of the adjacent machine, and the other end is connected to the main pipeline. The auxiliary steam enters the high-pressure cylinder 1 through the supplementary steam pipeline and the main pipeline. The fourth regulating valve 18, the seventh electric isolation valve 19 and the sixth check valve 20 are arranged on the supplementary steam pipeline. The fourth regulating valve 18 regulates the flow of the auxiliary steam flowing through the supplementary steam pipeline, the seventh electric isolation valve 19 controls the flow state of the auxiliary steam in the supplementary steam pipeline, and the sixth check valve 20 prevents the auxiliary steam from flowing back in the supplementary steam pipeline.

[0034] The unit can also send the first steam discharged from the reheat device to the recovery device 8 for recovery according to the operating status. The system also includes: a steam extraction pipeline 60, connected between the recovery inlet of the recovery device 8 and the high-temperature outlet of the high-temperature reheater 6, and the first steam is transported to the recovery device 8 through the steam extraction pipeline 60.

[0035] A second electric isolation valve 10 and a second temperature and pressure reduction valve 11 are provided on the steam extraction pipeline 60 .

[0036] The second electric isolation valve 10 controls the flow state of the first steam flowing through the steam extraction pipeline 60, and the second temperature and pressure reduction valve 11 adjusts the pressure of the first steam flowing through the steam extraction pipeline 60. When the second electric isolation valve 10 is opened, the first steam can enter the recovery device 8 through the steam extraction pipeline 60, and when the second electric isolation valve 10 is closed, the first steam cannot enter the recovery device 8.

[0037] In order to improve the operating flexibility of the unit, the system also includes: an auxiliary steam supply pipeline 80, which is connected between the steam supply outlet of the adjacent machine steam supply device and the steam inlet of the intermediate pressure cylinder 2. The auxiliary steam of the adjacent machine steam supply device is transported to the intermediate pressure cylinder 2 through the auxiliary steam supply pipeline 80.

[0038] Along the flow direction of the auxiliary steam in the auxiliary supplementary steam pipeline 80 , the auxiliary supplementary steam pipeline 80 is provided with: a second regulating valve 27 , a fourth electric isolation valve 28 and a third check valve 29 in sequence.

[0039] A butterfly valve 14 is provided on the medium-pressure exhaust steam pipeline 35 .

[0040] Auxiliary steam can also be delivered to the intermediate pressure cylinder 2 through the auxiliary steam supply pipeline 80 to make the intermediate pressure cylinder 2 do work, and the flow rate of the auxiliary steam flowing through the auxiliary steam supply pipeline 80 is adjusted by the second regulating valve 27 arranged on the auxiliary steam supply pipeline 80, the fourth electric isolation valve 28 controls the flow state of the auxiliary steam in the auxiliary steam supply pipeline 80, and the third check valve 29 prevents the auxiliary steam from flowing back in the auxiliary steam supply pipeline.

[0041] Another aspect of the present invention provides a method for controlling a three-cylinder micro-output system of a steam turbine of a circulating fluidized bed unit, which is implemented based on the three-cylinder micro-output system of a steam turbine of a circulating fluidized bed unit described in any one of the above items, and the control method comprises: Main steam is supplied to the high-pressure cylinder through the superheating device so that the high-pressure cylinder can do work. After the main steam does work, it becomes high-pressure exhaust steam and is discharged. Auxiliary steam is supplied to the high-pressure cylinder through the adjacent machine supplementary steam device so that the high-pressure cylinder can do work. After the auxiliary steam does work, it becomes high-pressure exhaust steam and is discharged. The high-pressure exhaust steam is heated to become the first steam, and the first steam is sent to the intermediate-pressure cylinder for the intermediate-pressure cylinder to do work. After the first steam does work, it becomes the intermediate-pressure exhaust steam and is discharged; The medium-pressure exhaust steam is sent to the low-pressure cylinder to perform work, and the medium-pressure exhaust steam becomes low-pressure exhaust steam after performing work and is discharged; The high-pressure exhaust steam is transported to the medium-pressure exhaust steam pipeline between the medium-pressure cylinder and the low-pressure cylinder so that the high-pressure exhaust steam and the medium-pressure exhaust steam are mixed and enter the low-pressure cylinder to work and then become low-pressure exhaust steam and be discharged; Recover the discharged medium-pressure exhaust steam and low-pressure exhaust steam.

[0042] In one embodiment, taking a 300MW subcritical air-cooled unit as an example, two units are operated, one unit is under pressure, and the other unit is operated at 30% of the rated load. The other unit serves as an adjacent unit, and the reheat steam of the adjacent unit is used as auxiliary steam. The reheat steam pressure and temperature of the adjacent unit are 1.5MPa and 521℃ respectively.

[0043] During the winter, the unit starts to operate at a reduced fire load of 90MW, stops the main fuel of the unit, and stops the conveying and induced draft fans. After the unit is operated at a reduced fire, as the combustion intensity decreases rapidly, the evaporation of the boiler decreases rapidly, the unit's operating load decreases accordingly, and the main and reheat steam pressures and temperatures of the unit also gradually decrease. The initial main steam pressure is 10MPa, and the main steam temperature and reheat steam temperature are both 540℃. The unit can be operated by adding a high-efficiency vacuum device to assist the unit operation. The unit's operating back pressure can be reduced to 1.5kPa~2.5kPa, meeting the operating requirements of the low-pressure cylinder 3 steam inlet flow rate of 30t / h~40t / h. When the unit is operated under pressure, the butterfly valve 14 is switched to the small valve adjustment mode. The butterfly valve 14 is a new type of double-valve plate low-pressure cylinder steam inlet butterfly valve, which can control the steam intake into the low-pressure cylinder 3 according to the unit back pressure. If the minimum cooling flow corresponding to the operating back pressure is not met, the steam intake from the adjacent machine supplementary steam device to the medium-pressure cylinder 2 should be increased so that the relative volume flow of the exhaust steam of the low-pressure cylinder 3 operates in a safe area. At this time, the fifth electric isolation valve 12 and the third temperature reduction and pressure relief valve 13 are not required. When the unit is operated under pressure in non-winter, the butterfly valve 14 is switched to the small valve adjustment mode to the minimum steam intake flow, and the unit back pressure is appropriately increased to the safety value corresponding to the steam intake flow of the low-pressure cylinder 3 to ensure that the last-stage blades of the low-pressure cylinder 3 quickly pass through the flutter zone. The excess medium-pressure exhaust steam passes through the recovery pipe 70 and flows through the fifth electric isolation valve 12 and the third temperature reduction and pressure relief valve 13 to the recovery device 8, which is the condenser hot well. During operation, the maximum steam inlet into the low-pressure cylinder 3 is controlled according to the back pressure of the unit, so that the relative volume flow of the exhaust steam of the low-pressure cylinder 3 runs in a safe area, and is discharged to the recovery device 8 through the recovery pipeline 70 and the fifth electric isolation valve 12 and the third temperature and pressure reducing valve 13. During the compression process, the unit load is reduced to 4MW~6MW, and the main steam flow is 25~30t / h. During this process, the temperature difference between the main steam and the reheated steam is controlled not to exceed 50℃. In order to ensure the safe operation of the steam turbine, the superheat of the main steam is required to be not less than 150℃, and the superheat of the reheated steam is required to be not less than 150℃.

[0044] As the compression operation time increases, the temperature and pressure of the main and reheat steam gradually decrease. When the superheat of the main steam of the compression unit decreases to nearly 150°C, the main steam regulating valve 15 can be gradually closed, and the adjacent machine steam supplement device can be put into operation to deliver auxiliary steam to the high-pressure cylinder 1. The seventh electric isolation valve 19 and the sixth check valve 20 are opened, and the valve core opening of the fourth regulating valve 18 is gradually increased, so that the steam supply of the high-pressure cylinder 1 of the compression unit is gradually switched from supplying main steam to supplying auxiliary steam. The steam intake of the high-pressure cylinder 1 can maintain the basic cooling flow of the high-pressure cylinder 1, which can meet the long-term safe and stable operation of the high-pressure cylinder 1. At the same time, the first regulating valve 25 and the first desuperheating and pressure reducing valve 26 are opened, and the main steam of the superheating device 5 passes through the auxiliary bypass and flows through the first regulating valve 25 and the first desuperheating and pressure reducing valve 26 on the auxiliary bypass 50, and then enters the cold reheating pipe, which is the pipe arranged between the exhaust port of the high-pressure cylinder 1 and the low-temperature inlet of the low-temperature reheater 7, and then enters the low-temperature reheater 7; at the same time, the fifth electric isolation valve 33 and the third desuperheating and pressure reducing valve 34 are opened, and the high-pressure exhaust steam of the high-pressure cylinder 1 of the steam turbine passes through the steam drainage pipe 36 and flows through the fifth electric isolation valve 33 and the third desuperheating and pressure reducing valve 34, and then enters the drain expansion tank 37. After the main steam provided by the superheating device 5 of the ignition unit is gradually desuperheated and pressure-reduced by the first desuperheating and pressure reducing valve 26 on the auxiliary bypass 50 to match the auxiliary steam pressure and temperature provided by the adjacent machine steam supply device, the main steam enters the reheating device through the auxiliary bypass 50 to absorb heat and become the first steam, and the first steam enters the intermediate pressure cylinder 2 of the steam turbine to do work. After the first steam performs work in the intermediate pressure cylinder 2, it flows through the intermediate pressure exhaust pipe and the butterfly valve 14 on the intermediate pressure exhaust pipe and enters the low pressure cylinder 3 to perform work. The minimum steam intake into the low pressure cylinder 3 can be controlled according to the back pressure of the unit. If the minimum cooling flow corresponding to the operating back pressure is not met, the steam intake flow of the auxiliary steam to the intermediate pressure cylinder 2 should be increased so that the relative volume flow of the exhaust steam of the low pressure cylinder 3 runs in a safe area. During non-winter pressure fire operation, the maximum steam intake into the low pressure cylinder 3 is controlled according to the back pressure of the unit, so that the relative volume flow of the exhaust steam of the low pressure cylinder 3 runs in a safe area. The excess exhaust steam of the intermediate pressure cylinder 2 is discharged to the recovery device 8 through the recovery pipe 70, and the unit power generation load is 4 MW ~ 6MW.

[0045] As the compression operation time increases, when the superheat of the unit's reheat steam decreases to nearly 150°C, the valve core opening of the third regulating valve 30 can be gradually reduced, and the auxiliary steam from the adjacent machine's steam supply device can be gradually input to the intermediate pressure cylinder 2. The valve core opening of the second regulating valve 27 on the auxiliary steam supply pipeline 80 from the adjacent machine's steam supply device to the intermediate pressure cylinder 2 is gradually increased, and the fourth electric isolation valve 28 and the third check valve 29 are opened. In this way, the steam supply to the intermediate pressure cylinder 2 of the compression unit is gradually switched to the auxiliary steam supplied by the adjacent machine's steam supply device. At the same time, the extraction pipeline 60 is gradually opened according to the superheat of the steam inlet of the intermediate pressure cylinder 2, and the first steam at the high-temperature outlet of the high-temperature reheater 7 gradually enters the recovery device 8 through the extraction pipeline 60. The second electric isolation valve 10 controls the flow state of the first steam flowing through the extraction pipeline 60, and the second temperature reduction and pressure reducing valve 11 adjusts the pressure of the first steam flowing through the extraction pipeline 60. The steam inlet of the intermediate pressure cylinder 2 only needs to maintain the basic cooling flow of the intermediate pressure cylinder 2. The steam inlet of the intermediate pressure cylinder 2 is maintained between 25t / h and 30t / h, which can meet the long-term safe and stable operation of the intermediate pressure cylinder 2. After the intermediate pressure cylinder 2 completes the steam switching, the steam inlet of the intermediate pressure cylinder 2 of the compression unit is all provided by the adjacent unit supplementary steam device, and the first steam all enters the recovery device 8 through the steam extraction pipeline 60, and the unit power generation load is 6MW~7MW.

[0046] The third stage is the super-long-term fire suppression stage of the unit, which can realize the non-stop operation of the unit when the boiler is shut down. At this time, the steam inlet of high-pressure cylinder 1 and the steam inlet of medium-pressure cylinder 2 are provided by the adjacent machine supplementary steam device. The steam inlet of high-pressure cylinder 1 can maintain the basic cooling flow of high-pressure cylinder 1 at 25t / h~30t / h, which can meet the long-term safe and stable operation of high-pressure cylinder 1. The basic cooling flow of medium-pressure cylinder 2 is between 25t / h~30t / h. The steam inlet of low-pressure cylinder 3 also meets the safe operation requirements, ensuring that the three cylinders of the steam turbine are in a micro-output operation state. The steam turbine can maintain long-term safe and stable operation, and the power generation load is 6MW~7MW.

[0047] The fourth stage is the unit fire-loading load stage. The unit fire-loading load-carrying capacity is greatly limited during the start-up process of the unmodified unit due to the low temperature of the main and re-steam, the mismatch between the temperature of the new steam from the boiler and the steam parameters required by the turbine, etc. This scheme improves the matching degree of the machine and boiler parameters during the start-up and fire-loading stage of the unit in pressure-fire operation through the adjacent machine steam supplement device. During the fire-loading start-up process of the pressure-fire unit, as the boiler of the pressure-fire unit is ignited and coal is added, the amount of boiler steam begins to increase significantly, but the steam temperature and pressure generated in the initial stage of boiler fire-loading are low, which cannot meet the safe operation requirements of the unit. At this time, the amount of auxiliary steam passing through the adjacent steam supplement device is increased to the high-pressure cylinder 1 and the medium-pressure cylinder 2, and the unit load is increased by 10-15%. When the parameters of main steam and reheat steam of the compression fire unit are compatible with the operating parameters of the steam turbine, the delivery volume of auxiliary steam of the adjacent steam supply device is gradually reduced, the first temperature reduction and pressure reducing valve 26 and the second temperature reduction and pressure reducing valve 11 are gradually adjusted down, and the third temperature reduction and pressure reducing valve 34 on the steam drainage pipeline 36 between the exhaust steam of the high-pressure cylinder 1 of the steam turbine and the drain expansion tank 37 is gradually closed, and the exhaust steam of the high-pressure cylinder 1 of the steam turbine enters the reheat device through the high-pressure cylinder exhaust check valve 9; at the same time, the main steam regulating valve 15, the first electric isolation valve 16, the third regulating valve 30 and the sixth electric isolation valve 31 are gradually opened until the adjacent steam supply device stops supplying auxiliary steam, the adjacent steam supply device exits the compression fire mode, the unit is switched to the pressure control mode, and the compression fire unit is restored to the normal load state. Due to the coordinated operation of the adjacent steam supply device and the boiler load increase of the compression fire unit, the boiler load increase parameters of the compression fire unit can be quickly matched with the steam turbine, and the recovery time of the low-pressure fire unit with load can be greatly reduced. After the fire suppression is completed and the fire suppression unit returns to the normal load state, during winter operation, the opening of the butterfly valve 14 is gradually adjusted according to the back pressure of the unit, and the third temperature reduction and pressure relief valve 13 on the recovery pipe 70 between the medium pressure cylinder 2 and the recovery device 8 is gradually closed until the normal operation state is restored. During non-winter operation, the butterfly valve 14 is quickly switched to the large valve operation mode to ensure that the last stage blades of the low pressure cylinder 3 quickly pass through the flutter zone, and the third temperature reduction and pressure relief valve 13 of the medium pressure cylinder 2 is gradually closed to restore the normal operation state of the unit.

[0048] In another embodiment, taking a 300MW subcritical air-cooled unit as an example, two units are operated, one unit is operated at reduced fire, and the other unit is operated at deep adjustment at 30% of the rated load. The other unit serves as an adjacent unit, and the reheat steam of the adjacent unit is used as auxiliary steam. The reheat steam pressure and temperature of the adjacent unit are 1.5MPa and 521°C, respectively.

[0049] During the winter, the unit starts to operate at a reduced fire load of 90MW, stops the main fuel of the unit, and stops the conveying and induced draft fans. After the unit is operated at a reduced fire, as the combustion intensity decreases rapidly, the evaporation of the boiler decreases rapidly, the unit's operating load decreases accordingly, and the main and reheat steam pressures and temperatures also gradually decrease. The initial main steam pressure is 10MPa, and the main steam temperature and reheat steam temperature are both 540℃. By adding a high-efficiency auxiliary vacuum device, the operating back pressure can be reduced to 1.5kPa~2.5kPa, meeting the requirements of the low-pressure cylinder 3 steam inlet flow of 30t / h~40t / h. When the unit is operated under pressure, the butterfly valve 14 is switched to the small valve adjustment mode, and the steam intake into the low-pressure cylinder 3 can be controlled according to the back pressure of the unit. If the minimum cooling flow corresponding to the operating back pressure is not met, the adjacent machine steam supplement device should be added to supplement the auxiliary steam to the medium-pressure cylinder 2 steam intake flow, so that the relative volume flow of the exhaust steam of the low-pressure cylinder 3 operates in a safe area. There is no need to open the fifth electric isolation valve 12 and the third temperature and pressure reducing valve 13 on the recovery pipe 70 between the medium-pressure cylinder 2 and the recovery device 8. When the unit is operated under pressure in non-winter, the butterfly valve 14 is switched to the small valve adjustment mode to the minimum steam intake flow, and the back pressure of the unit is appropriately increased to the safety value corresponding to the steam intake flow of the low-pressure cylinder 3, so as to ensure that the last-stage blades of the low-pressure cylinder 3 pass through the flutter zone quickly, and the excess medium-pressure exhaust steam of the medium-pressure cylinder 2 is discharged to the recovery device 8 through the recovery pipe 70. During operation, the maximum steam inlet into the low-pressure cylinder 3 is controlled according to the back pressure of the unit, so that the exhaust steam of the low-pressure cylinder 3 runs in the safe area relative to the volume flow, and the excess medium-pressure exhaust steam of the medium-pressure cylinder 2 is discharged to the recovery device 8 through the recovery pipeline 70. During the compression process, the unit load is reduced to 4 MW ~ 6MW, and the main steam flow is 25~30t / h. In this process, the temperature difference between the main steam and the reheated steam is controlled not to exceed 50℃. In order to ensure the safe operation of the steam turbine, the superheat of the main steam is required to be not less than 150℃, and the superheat of the reheated steam is required to be not less than 150℃.

[0050] As the compression operation time increases, the temperature and pressure of the main and reheat steam gradually decrease. When the superheat of the main steam of the compression unit is reduced to nearly 150℃, the main steam regulating valve 15 can be gradually closed, and the auxiliary steam of the adjacent machine steam supply device can be added to the high-pressure cylinder 1. The seventh electric isolation valve 19 and the sixth check valve 20 are opened, and the fourth regulating valve 18 on the steam supply pipeline between the adjacent machine steam supply device and the high-pressure cylinder 1 is gradually opened. The steam supply to the high-pressure cylinder 1 of the compression unit is gradually switched to that provided by the adjacent machine steam supply device. The steam intake of the high-pressure cylinder 1 can maintain the basic cooling flow of the high-pressure cylinder 1 to meet the long-term safe and stable operation of the high-pressure cylinder 1. At the same time, the first regulating valve 25 and the first temperature-reducing and pressure-reducing valve 26 are opened, and the main steam of the superheating device 5 enters the reheating device through the auxiliary bypass 50; at the same time, the second electric isolation valve 21 and the second check valve 22 are opened, and the fifth electric isolation valve 33 and the third temperature-reducing and pressure-reducing valve 34 are closed, and the high-pressure exhaust steam of the high-pressure cylinder 1 of the steam turbine enters the medium-pressure exhaust pipe 35 through the high-pressure exhaust bypass 40 and the second electric isolation valve 21 and the second check valve 22. The main steam of the superheating device 5 of the compression unit is gradually reduced in temperature and pressure by the first temperature-reducing and pressure-reducing valve 26 on the auxiliary bypass 50 to match the pressure and temperature of the auxiliary steam provided by the adjacent machine supplementary steam device, and then enters the reheating device to absorb heat and become the first steam, and the first steam enters the medium-pressure cylinder 2 of the steam turbine to do work. After the first steam works in the intermediate pressure cylinder 2, it becomes the intermediate pressure exhaust steam and flows through the butterfly valve 14 to enter the low pressure cylinder 3. The minimum steam intake into the low pressure cylinder 3 can be controlled according to the back pressure of the unit. If the minimum cooling flow corresponding to the operating back pressure is not met, the auxiliary steam provided by the adjacent machine supplementary steam device should be increased to send the steam intake flow of the intermediate pressure cylinder 2, so that the relative volume flow of the exhaust steam of the low pressure cylinder 3 runs in a safe area. During non-winter pressure fire operation, the maximum steam intake into the low pressure cylinder 3 is controlled according to the back pressure of the unit, so that the relative volume flow of the exhaust steam of the low pressure cylinder 3 runs in a safe area. The excess intermediate pressure exhaust steam of the intermediate pressure cylinder 2 is discharged to the recovery device 8 through the recovery pipe 70, and the unit power generation load is 7 MW ~ 8MW.

[0051] As the compression operation time increases, when the superheat of the unit's reheat steam decreases to nearly 150°C, the third regulating valve 30 can be gradually closed, the adjacent machine steam supply device is put into use to deliver auxiliary steam to the intermediate pressure cylinder 2, the fourth electric isolation valve 28 and the third check valve 29 are opened, and the valve core opening of the second regulating valve 27 on the auxiliary steam supply pipeline 80 is gradually increased. The steam supply of the intermediate pressure cylinder 2 of the compression unit is gradually switched to the adjacent machine steam supply device. At the same time, the extraction pipeline 60 is gradually opened according to the superheat of the steam inlet of the intermediate pressure cylinder 2. The first steam discharged from the reheat device gradually flows through the extraction pipeline 60 and flows through the second electric isolation valve 10 and the second temperature and pressure reduction valve 11 into the recovery device 8. The steam intake of the intermediate pressure cylinder 2 can be maintained between 25t / h and 30t / h, which can meet the long-term safe and stable operation of the intermediate pressure cylinder 2. After the switch is completed, the steam inlet to the intermediate pressure cylinder 2 of the compression unit is all provided by the adjacent unit supplementary steam device, and the first steam is all sent to the recovery device 8 through the steam extraction pipeline 60. The unit power generation load is 6 MW ~ 7MW.

[0052] The third stage is the super-long-term fire suppression stage of the unit, which can realize the non-stop operation of the unit when the boiler is shut down. At this time, the steam inlet of high-pressure cylinder 1 and medium-pressure cylinder 2 are provided by the adjacent machine supplementary steam device. The steam inlet of high-pressure cylinder 1 can be maintained between 25t / h and 30t / h, which can meet the long-term safe and stable operation of high-pressure cylinder 1. The basic cooling flow of medium-pressure cylinder 2 is between 25t / h and 30t / h. The steam inlet of low-pressure cylinder 3 also meets the safe operation requirements, ensuring that the three cylinders of the steam turbine are in a micro-output operation state. The steam turbine can maintain long-term safe and stable operation, and the power generation load is 10 MW ~12MW.

[0053] The fourth stage is the unit fire-loading load stage. The unit fire-loading load-carrying capacity is greatly limited during the start-up process of the unmodified unit due to the low temperature of the main and re-steam, the mismatch between the temperature of the new steam from the boiler and the steam parameters required by the turbine, etc. This modification plan improves the matching degree of the machine and boiler parameters during the start-up and fire-loading stage of the unit under pressure operation through the adjacent machine steam supplement device. During the fire-loading start-up process of the unit under pressure operation, as the boiler is ignited and coal is added, the amount of boiler steam begins to increase significantly, but the steam temperature and pressure generated in the initial stage of boiler fire-loading are relatively low, which cannot meet the safe operation requirements of the unit. At this time, the auxiliary steam provided by the adjacent machine steam supplement device can be added to the high-pressure cylinder 1 and the medium-pressure cylinder 2, and the unit load increases by 10-15%. When the main steam and reheat steam parameters of the compression unit are compatible with the turbine operating parameters, the steam volume of the auxiliary steam of the adjacent steam supply device is gradually reduced, and the first temperature reduction and pressure reducing valve 26 and the second temperature reduction and pressure reducing valve 11 are gradually reduced; at the same time, the second electric isolation valve 21 and the second check valve 22 are closed, and the eighth electric isolation valve 23 and the seventh check valve 24 are opened, and the high-pressure exhaust steam of the high-pressure cylinder 1 of the turbine enters the reheat device through the high-pressure cylinder exhaust check valve 9, the eighth electric isolation valve 23 and the seventh check valve 24; the main steam regulating valve 15, the first electric isolation valve 16, the third regulating valve 30 and the sixth electric isolation valve 31 are gradually opened until the adjacent steam supply device stops supplying auxiliary steam, the adjacent steam supply device exits the compression mode, the unit switches to the pressure control mode, and the compression unit returns to the normal load state. Due to the coordinated operation of the adjacent steam supply device and the boiler load increase of the compression unit, the boiler load increase parameters of the compression unit can be quickly matched with the turbine, greatly reducing the recovery time of the low-pressure unit. When the fire suppression is completed and the fire suppression unit returns to the normal load state, during winter operation, the opening of the butterfly valve 14 is gradually adjusted according to the back pressure of the unit, and the third temperature reduction and pressure relief valve 13 on the recovery pipe 70 is gradually closed until the unit returns to normal operation. During non-winter operation, the butterfly valve 14 is quickly switched to the large valve operation mode to ensure that the last-stage blades of the low-pressure cylinder 3 quickly pass through the flutter zone, and the third temperature reduction and pressure relief valve 13 on the recovery pipe 70 is gradually closed until the unit returns to normal operation.

[0054] The three-cylinder micro-output system and control method of the steam turbine of the circulating fluidized bed unit provided by the present invention supplies main steam to the high-pressure cylinder of the steam turbine through the superheating device, and can supply auxiliary steam to the high-pressure cylinder through the adjacent machine steam supplement device. In this way, during the compressed fire operation of the circulating fluidized bed unit, the auxiliary steam is transported to the high-pressure cylinder through the adjacent machine steam supplement device to supply the high-pressure cylinder with work. After the main steam and the auxiliary steam enter the high-pressure cylinder to do work, they become high-pressure exhaust steam and are discharged from the exhaust port of the high-pressure cylinder. After the high-pressure exhaust steam is heated by the reheating device, it is The temperature rises to become the first steam, and the first steam is sent to the medium-pressure cylinder to do work. After the first steam does work in the medium-pressure cylinder, it becomes medium-pressure exhaust steam and is discharged from the exhaust port of the medium-pressure cylinder. The discharged medium-pressure exhaust steam enters the low-pressure cylinder to do work and becomes low-pressure exhaust steam and is discharged from the exhaust port of the low-pressure cylinder. The low-pressure exhaust steam is sent to the recovery device for recovery. The high-pressure exhaust steam can be sent to the medium-pressure exhaust pipeline through the high-exhaust bypass and mixed with the medium-pressure exhaust steam before entering the low-pressure cylinder to do work. In this way, the high-pressure cylinder, medium-pressure cylinder and low-pressure cylinder of the steam turbine achieve micro-output operation. The three-cylinder micro-output system and control method of the steam turbine of the circulating fluidized bed unit provided by the present invention supplements auxiliary steam to the high-pressure cylinder through the adjacent machine steam supplement device, and sends the high-pressure exhaust steam into the medium-pressure exhaust pipeline, which solves the problem that the steam turbine of the circulating fluidized bed unit cannot operate safely under small volume flow conditions when the pressure-fire operation is in the prior art, reduces the loss of working fluid, and improves the deep peak-shaving operation capability of the unit.

[0055] The optional implementation modes of the embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical scheme of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0056] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0057] In addition, various implementation modes of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed by the embodiments of the present invention.

Claims

1. A three-cylinder micro-output system for a circulating fluidized bed unit steam turbine, characterized in that: The three-cylinder micro-output system of the steam turbine of the circulating fluidized bed unit comprises: The superheating device (5) is connected to the high-pressure cylinder (1) of the steam turbine through a main pipeline and is used to supply main steam to the high-pressure cylinder (1). The main steam becomes high-pressure exhaust steam and is discharged after doing work in the high-pressure cylinder (1); An adjacent machine steam supplement device is connected to the high-pressure cylinder (1) via a steam supplement pipeline, and the adjacent machine steam supplement device is used to supply auxiliary steam to the high-pressure cylinder (1). The auxiliary steam becomes high-pressure exhaust steam and is discharged after doing work in the high-pressure cylinder (1); The reheating device is arranged between the exhaust port of the high-pressure cylinder (1) and the steam inlet of the intermediate-pressure cylinder (2) of the steam turbine, and is used to heat the high-pressure exhaust steam discharged from the high-pressure cylinder (1). After the high-pressure exhaust steam is heated, it becomes the first steam and is sent to the intermediate-pressure cylinder (2) to perform work and become the intermediate-pressure exhaust steam, and is discharged from the exhaust port of the intermediate-pressure cylinder (2); an intermediate-pressure exhaust steam pipeline (35) is arranged between the exhaust port of the intermediate-pressure cylinder (2) and the steam inlet of the low-pressure cylinder (3) of the steam turbine, and the intermediate-pressure exhaust steam enters the low-pressure cylinder (3) of the steam turbine through the intermediate-pressure exhaust steam pipeline (35) and becomes the low-pressure exhaust steam after performing work and is discharged; A high-pressure exhaust bypass (40) is connected between the exhaust port of the high-pressure cylinder (1) and the medium-pressure exhaust pipe (35) and is used to send the high-pressure exhaust steam into the medium-pressure exhaust pipe (35); The recovery device (8) is connected to the exhaust port of the medium-pressure cylinder (2) and the exhaust port of the low-pressure cylinder (3) and is used to recover the medium-pressure exhaust steam and the low-pressure exhaust steam.

2. The circulating fluidized bed unit steam turbine three-cylinder micro-output system according to claim 1, characterized in that: The system further comprises an auxiliary bypass (50) connected between the main pipeline and the reheat steam inlet of the reheat device, and used for sending the main steam into the reheat device for reheating.

3. The circulating fluidized bed unit steam turbine three-cylinder micro-output system according to claim 2, characterized in that: A first regulating valve (25) and a first temperature and pressure reducing valve (26) are sequentially arranged on the auxiliary bypass (50).

4. The circulating fluidized bed unit steam turbine three-cylinder micro-output system according to claim 1, characterized in that: A first check valve (17), a first electric isolation valve (16) and a main steam regulating valve (15) are arranged in sequence on the main pipeline along the flow direction of the main steam.

5. The circulating fluidized bed unit steam turbine three-cylinder micro-output system according to claim 1, characterized in that: A second electric isolation valve (21) and a second check valve (22) are sequentially arranged on the high-pressure exhaust bypass (40).

6. The circulating fluidized bed unit steam turbine three-cylinder micro-output system according to claim 1, characterized in that: The reheating device comprises: a low-temperature reheater (7) and a high-temperature reheater (6); The low-temperature inlet of the low-temperature reheater (7) is connected to the exhaust port of the high-pressure cylinder (1) through a pipeline, and the low-temperature reheater (7) is used to preliminarily heat the high-pressure exhaust steam discharged from the high-pressure cylinder (1); The high-temperature inlet of the high-temperature reheater (6) is connected to the low-temperature outlet of the low-temperature reheater (7), and the high-temperature outlet is connected to the steam inlet of the intermediate-pressure cylinder (2); the high-temperature reheater (6) is used for secondary heating of the high-pressure exhaust steam discharged from the high-pressure cylinder (1) to form the first steam, and the first steam is discharged from the high-temperature outlet of the high-temperature reheater (6) and then sent to the intermediate-pressure cylinder (2).

7. The three-cylinder micro-output system of the steam turbine of the circulating fluidized bed unit according to claim 4 is characterized in that: The system further comprises: a steam extraction pipeline (60) connected between a recovery inlet of the recovery device (8) and a high-temperature outlet of the high-temperature reheater (6), and the first steam is transported to the recovery device (8) through the steam extraction pipeline (60).

8. The three-cylinder micro-output system of the steam turbine of the circulating fluidized bed unit according to claim 7 is characterized in that: A second electric isolation valve (10) and a second temperature and pressure reduction valve (11) are provided on the steam extraction pipeline (60).

9. The circulating fluidized bed unit steam turbine three-cylinder micro-output system according to claim 1, characterized in that: The system further comprises: an auxiliary supplementary steam pipeline (80) connected between the supplementary steam outlet of the adjacent machine supplementary steam device and the steam inlet of the intermediate pressure cylinder (2), and the auxiliary steam of the adjacent machine supplementary steam device is transported to the intermediate pressure cylinder (2) through the auxiliary supplementary steam pipeline (80).

10. The circulating fluidized bed unit steam turbine three-cylinder micro-output system according to claim 7, characterized in that: Along the flow direction of the auxiliary steam in the auxiliary steam supply pipeline (80), the auxiliary steam supply pipeline (80) is provided with: a second regulating valve (27), a fourth electric isolation valve (28) and a third check valve (29) in sequence.

11. The circulating fluidized bed unit steam turbine three-cylinder micro-output system according to claim 9, characterized in that: A butterfly valve (14) is provided on the medium-pressure exhaust steam pipeline (35).

12. A method for controlling a three-cylinder micro-output system of a steam turbine of a circulating fluidized bed unit, which is implemented based on the three-cylinder micro-output system of a steam turbine of a circulating fluidized bed unit according to any one of claims 1 to 11, characterized in that: The control method comprises: Main steam is supplied to the high-pressure cylinder through the superheating device so that the high-pressure cylinder can do work. After the main steam does work, it becomes high-pressure exhaust steam and is discharged. Auxiliary steam is supplied to the high-pressure cylinder through the adjacent machine supplementary steam device so that the high-pressure cylinder can do work. After the auxiliary steam does work, it becomes high-pressure exhaust steam and is discharged. The high-pressure exhaust steam is heated to become the first steam, and the first steam is sent to the intermediate-pressure cylinder for the intermediate-pressure cylinder to do work. After the first steam does work, it becomes the intermediate-pressure exhaust steam and is discharged; The medium-pressure exhaust steam is sent to the low-pressure cylinder to perform work, and the medium-pressure exhaust steam becomes low-pressure exhaust steam after performing work and is discharged; The high-pressure exhaust steam is transported to the medium-pressure exhaust steam pipeline between the medium-pressure cylinder and the low-pressure cylinder so that the high-pressure exhaust steam and the medium-pressure exhaust steam are mixed and enter the low-pressure cylinder to work and then become low-pressure exhaust steam and be discharged; Recover the discharged medium-pressure exhaust steam and low-pressure exhaust steam.

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