Deep peak regulation system for double-reheat unit

Abstract

The application discloses a kind of for secondary reheat unit depth peak shaving system, including thermal power generating unit, secondary reheat return steam unit and steam supply unit, secondary reheat return steam unit includes first pressure matcher, first desuperheater, from feed pump intermediate tap, first pressure matcher is communicated with boiler, the outlet of first pressure matcher is communicated with first desuperheater, one way of first desuperheater is communicated with from feed pump intermediate tap by second valve group, another way is communicated with the import of secondary reheat ware by first electric isolation valve, the main road of secondary reheat ware is communicated with medium pressure cylinder by medium pressure regulating door, the first branch of secondary reheat ware is communicated with first pressure matcher by third valve group, the second branch of secondary reheat ware is communicated with first desuperheater by fourth valve group, the outlet of first desuperheater is communicated with industrial steam supply system. According to the secondary reheat unit depth peak shaving system for the application can preferably meet user production demand when depth peak shaving.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power generation technology, and in particular to a deep peak-shaving system for secondary reheat units. Background Technology

[0002] With the large-scale grid connection of new energy power generation (wind power, photovoltaic, etc.), the power system has placed higher demands on the peak-shaving capacity of thermal power units. Deep peak shaving (usually referring to the unit load being reduced to below 40% of the rated load, and for some units even to 20%-30%) has become an important operating mode for thermal power units to participate in grid dispatch. However, under deep peak shaving conditions, the industrial steam supply system of a 1000MW thermal power unit faces the dual challenges of "low-load operation stability" and "industrial steam supply continuity." Specifically, drastic changes in the unit's thermal system parameters may lead to fluctuations in steam supply pressure and temperature, and even affect user production. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one object of the present invention is to provide a deep peak-shaving system for double reheat units, which can better meet the user's production needs during deep peak shaving.

[0004] According to an embodiment of the present invention, a deep peak-shaving system for a double reheat unit includes: a thermal power unit, comprising a boiler, an ultra-high pressure cylinder, a high pressure cylinder, an intermediate pressure cylinder, a low pressure cylinder, a primary reheater, and a secondary reheater. Steam generated by the boiler passes sequentially through the ultra-high pressure cylinder, the high pressure cylinder, the intermediate pressure cylinder, and the low pressure cylinder via steam pipelines to convert the thermal energy of the steam into mechanical energy. The converted mechanical energy is used to drive a generator to generate electricity. The primary reheater is connected between the ultra-high pressure cylinder and the high pressure cylinder, and the secondary reheater is connected between the high pressure cylinder and the intermediate pressure cylinder. A first exhaust check valve is installed at the inlet of the primary reheater, and a second exhaust check valve is installed at the inlet of the secondary reheater. An ultra-high pressure regulating valve is installed at the inlet of the ultra-high pressure cylinder, a high pressure regulating valve is installed at the inlet of the high pressure cylinder, and an intermediate pressure regulating valve is installed at the inlet of the intermediate pressure cylinder. A double reheat return steam unit is also included. The return steam unit includes a first pressure matching device, a first desuperheater, an intermediate tap of a self-feeding water pump, a first valve group, a second valve group, and a third valve group. The first pressure matching device is connected to the boiler. The first valve group is located between the first pressure matching device and the boiler. The outlet of the first pressure matching device is connected to the first desuperheater. One path of the first desuperheater is connected to the intermediate tap of the self-feeding water pump via the second valve group, and the other path is connected to the inlet of the secondary reheater via a first electric isolation valve. The main path of the secondary reheater is connected to the intermediate pressure cylinder via the intermediate pressure regulating valve. The first branch of the secondary reheater is connected to the first pressure matching device via the third valve group. The steam supply unit includes a first desuperheater and pressure reducer and a fourth valve group. The second branch of the secondary reheater is connected to the first desuperheater and pressure reducer via the fourth valve group. The outlet of the first desuperheater and pressure reducer is connected to the industrial steam supply system.

[0005] According to the embodiments of the present invention, the deep peak shaving system for reheat units can improve the steam supply guarantee capability and unit operation safety of thermal power units under low load conditions by using reheat return steam units and steam supply units.

[0006] In some embodiments of the present invention, the steam supply unit further includes: a fifth valve group and a second desuperheater and pressure reducer, wherein the inlet of the second desuperheater and pressure reducer is connected to the outlet of the primary reheater through the fifth valve group, and the outlet of the second desuperheater and pressure reducer is connected to the industrial steam supply system.

[0007] In some embodiments of the present invention, a second electrically operated isolation valve is provided between the first valve group and the first pressure matcher. The deep peak shaving system for the secondary reheat unit also includes an auxiliary unit, which includes: a third electrically operated isolation valve, a fourth electrically operated isolation valve, a second pressure matcher, a second desuperheater, and a sixth valve group. The second pressure matcher is connected between the first valve group and the second electrically operated isolation valve through a first branch pipe. The third electrically operated isolation valve is provided on the first branch pipe. The outlet of the second pressure matcher is connected to the second desuperheater. One path of the second desuperheater is connected to the inlet of the primary reheater through the fourth electrically operated isolation valve. The outlet of the primary reheater is connected to the second pressure matcher through a second branch pipe. The sixth valve group is provided on the second branch pipe.

[0008] In some embodiments of the present invention, the auxiliary unit further includes: a seventh valve group, wherein another path of the second desuperheater is connected to the intermediate tap of the self-supply water pump via the seventh valve group.

[0009] In some embodiments of the present invention, a second electrically operated isolation valve is provided between the first valve group and the first pressure matcher. The steam supply unit further includes: a fifth electrically operated isolation valve, an eighth valve group, a third pressure matcher, and a third desuperheater. The third pressure matcher is connected between the first valve group and the second electrically operated isolation valve via a third branch pipe. The third branch pipe is equipped with the fifth electrically operated isolation valve. The suction port of the third pressure matcher is connected to the outlet of the secondary reheater via a fourth branch pipe. The fourth branch pipe is equipped with the eighth valve group. The outlet of the third pressure matcher is connected to the third desuperheater. One path of the third desuperheater is connected to the industrial steam supply system.

[0010] In some embodiments of the present invention, the steam supply unit further includes: a ninth valve group, wherein another path of the third desuperheater is connected to the intermediate tap of the self-feeding water pump via the ninth valve group.

[0011] In some embodiments of the present invention, two low-pressure cylinders are provided, and the two low-pressure cylinders are connected in series.

[0012] In some embodiments of the present invention, the first valve group includes a first quick-closing regulating valve, a sixth electrically operated isolation valve, and a first pneumatic check valve connected in series; the second valve group includes a first electrically operated regulating valve and a seventh electrically operated isolation valve connected in series; the third valve group includes a second electrically operated regulating valve and an eighth electrically operated isolation valve connected in series; the fourth valve group includes a second quick-closing regulating valve, a ninth electrically operated isolation valve, and a second pneumatic check valve connected in series; and the fifth valve group includes a third quick-closing regulating valve, a tenth electrically operated isolation valve, and a third pneumatic check valve connected in series.

[0013] In some embodiments of the present invention, the sixth valve group includes a third electrically controlled regulating valve and an eleventh electrically isolated valve connected in series; the seventh valve group includes a fourth electrically controlled regulating valve and a twelfth electrically isolated valve connected in series.

[0014] In some embodiments of the present invention, the eighth valve group includes a fifth electrically controlled regulating valve and a thirteenth electrically isolated valve connected in series; the ninth valve group includes a sixth electrically controlled regulating valve and a fourteenth electrically isolated valve connected in series.

[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is the first embodiment of the deep peak shaving system for a double reheat unit.

[0017] Figure 2 This is the second embodiment of the present invention for a deep peak shaving system for a secondary reheat unit.

[0018] Figure label: 1. Boiler; 2. Ultra-high pressure cylinder; 3. High pressure cylinder; 4. Medium pressure cylinder; 5. Low pressure cylinder; 6. Primary reheater; 7. Secondary reheater; 8. Generator; 9. First exhaust check valve; 10. Second exhaust check valve; 11. Ultra-high pressure regulating valve; 12. High pressure regulating valve; 13. Medium pressure regulating valve; 14. First pressure matching device; 15. First desuperheater; 16. Intermediate tap of self-feeding water pump; 17. First electric isolation valve; 18. First desuperheater and pressure reducer; 19. Second desuperheater and pressure reducer; 20. Second electric isolation valve; 21. Third electric isolation valve; 22. Fourth electric isolation valve; 23. Second pressure matching device; 24. Second desuperheater; 25. Fifth electric isolation valve; 26. Third pressure matching device; 27. Third desuperheater; 2 8. Industrial steam supply system; 31. First quick-closing regulating valve; 32. Sixth electric isolation valve; 33. First pneumatic check valve; 41. First electric regulating valve; 42. Seventh electric isolation valve; 51. Second electric regulating valve; 52. Eighth electric isolation valve; 61. Second quick-closing regulating valve; 62. Ninth electric isolation valve; 63. Second pneumatic check valve; 71. Third quick-closing regulating valve; 72. Tenth electric isolation valve; 73. Third pneumatic check valve; 81. Third electric regulating valve; 82. Eleventh electric isolation valve; 91. Fourth electric regulating valve; 92. Twelfth electric isolation valve; 101. Fifth electric regulating valve; 102. Thirteenth electric isolation valve; 111. Sixth electric regulating valve; 112. Fourteenth electric isolation valve. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0020] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] With the large-scale grid connection of new energy power generation (wind power, photovoltaic, etc.), the power system has placed higher demands on the peak-shaving capacity of thermal power units. Deep peak shaving (usually referring to the unit load being reduced to below 40% of the rated load, and for some units even to 20%-30%) has become an important operating mode for thermal power units to participate in grid dispatch. However, under deep peak shaving conditions, the industrial steam supply system of a 1000MW thermal power unit faces the dual challenges of "low-load operation stability" and "industrial steam supply continuity." Specifically, drastic changes in the unit's thermal system parameters may lead to fluctuations in steam supply pressure and temperature, and even affect user production.

[0023] 1000MW thermal power units are typically designed with subcritical or supercritical parameters, and their industrial steam supply mainly relies on extraction steam from the intermediate-pressure cylinder of the turbine (intermediate-pressure steam supply) or extraction steam from the low-pressure cylinder (low-pressure steam supply). Under deep peak-shaving conditions, the unit load rapidly drops from the rated value (1000MW) to below 400MW, and the thermal system exhibits characteristics of "sudden reduction in steam flow and increased parameter fluctuations," directly affecting the operating status of the steam supply system, specifically in the following three aspects: (i) Decreased stability of steam supply parameters. Increased pressure fluctuations: The turbine extraction pressure is positively correlated with the unit load—when the load drops from 1000MW to 300MW, the intermediate-pressure cylinder extraction pressure may drop from 3.5MPa to 1.2MPa (a decrease of over 65%), and the low-pressure cylinder extraction pressure may drop from 0.8MPa to 0.2MPa (a decrease of 75%). If industrial users require stable intermediate-pressure steam (e.g., 2.5MPa), traditional extraction methods are insufficient, requiring desuperheating and pressure reducing devices for parameter compensation. However, under low loads, the adjustment margin of the desuperheating and pressure reducing devices will be significantly reduced, easily leading to pressure overshoot or undershoot.

[0024] Increased risk of steam temperature fluctuations: At low loads, boiler combustion intensity decreases, furnace temperature drops, and the steam temperature at the superheater and reheater outlets may deviate from design values ​​(e.g., the reheat steam temperature of a supercritical boiler drops from 560℃ to below 500℃). If the extraction steam temperature is too low, it may lead to a decrease in steam dryness (or even water carryover), causing corrosion or water hammer in user equipment; if the temperature is too high, the desuperheating water volume needs to be increased, which not only wastes energy but may also cause temperature fluctuations due to the lag in desuperheater adjustment.

[0025] (ii) Limited Steam Supply Flow Regulation Capacity. Industrial steam supply flow needs to match the user's steam load (e.g., chemical industrial parks require 50-200 t / h of medium-pressure steam). However, under deep peak shaving conditions, the unit's extraction steam flow is limited by the turbine's flow capacity: when the load is below 40% of the rated value, the extraction steam flow of the medium-pressure cylinder may drop from 150 t / h to below 50 t / h. If the user's steam consumption is consistently higher than the extraction steam flow, the boiler's "direct steam supply" (extraction of steam directly from the superheater outlet) needs to be activated. However, the direct steam supply pressure is high (e.g., 16 MPa), requiring multiple stages of pressure reduction, resulting in a heat loss of 15%-20%. The extraction steam from the low-pressure cylinder is more susceptible to load influence. When the load is below 30%, the low-pressure cylinder exhaust pressure may approach a vacuum, and the extraction steam flow is almost zero, which cannot meet the user's low-pressure steam demand (e.g., heating, food processing). It is necessary to rely on auxiliary steam systems (e.g., boiler start-up) to supplement the supply, increasing operating costs.

[0026] (III) Increased Coupling Contradictions in the Thermal System. The "power generation-steam supply" system of a 1000MW thermal power unit has a strong coupling relationship. During deep peak shaving, this coupling contradiction will be amplified. In order to maintain stable combustion at low load, the boiler needs to maintain the minimum air volume and fuel volume, resulting in steam production exceeding the unit's power generation demand. If the industrial steam supply is insufficient, the excess steam needs to be vented through the "vent valve", resulting in energy waste (e.g., at 30% load, the vented steam volume can reach 20-30t / h). If the industrial steam supply suddenly increases (e.g., users add new production lines), the unit needs to quickly increase the steam extraction volume. However, the turbine response speed is slow at low load (the load ramp rate drops from 10MW / min to below 5MW / min), which may cause grid load fluctuations and trigger dispatch assessments.

[0027] Meanwhile, with the increase in the number of industrial users and the diversification of production processes in the industrial park, the demand for steam from users is characterized by multiple varieties, small batches, and random fluctuations, which puts forward higher requirements for the stability and flexibility of the steam supply system of the 1000MW thermal power unit industrial steam supply system.

[0028] This invention, through the design of a deep peak-shaving system for reheat units, can effectively improve the steam supply guarantee capability and operational safety of thermal power units under low-load conditions.

[0029] The following is for reference. Figures 1-2 A deep peak shaving system for a double reheat unit is described according to an embodiment of the present invention.

[0030] like Figure 1 and Figure 2 As shown, the deep peak-shaving system for a double reheat unit according to an embodiment of the present invention includes: a thermal power unit, a double reheat return steam unit, and a steam supply unit. The thermal power unit includes a boiler 1, an ultra-high pressure cylinder 2, a high pressure cylinder 3, an intermediate pressure cylinder 4, a low pressure cylinder 5, a primary reheater 6, and a secondary reheater 7. Steam generated by the boiler 1 passes sequentially through the ultra-high pressure cylinder 2, the high pressure cylinder 3, the intermediate pressure cylinder 4, and the low pressure cylinder 5 via steam pipelines to convert the thermal energy of the steam into mechanical energy. The converted mechanical energy is used to drive a generator 8 to generate electricity. The primary reheater 6 is connected between the ultra-high pressure cylinder 2 and the high pressure cylinder 3, and the secondary reheater 7 is connected between the high pressure cylinder 3 and the intermediate pressure cylinder 4. A first exhaust check valve 9 is installed at the inlet of the primary reheater 6, and a second exhaust check valve 10 is installed at the inlet of the secondary reheater 7. An ultra-high pressure regulating valve 11 is installed at the inlet of the ultra-high pressure cylinder 2, a high pressure regulating valve 12 is installed at the inlet of the high pressure cylinder 3, and an intermediate pressure regulating valve 13 is installed at the inlet of the intermediate pressure cylinder 4. The secondary reheat return steam unit includes a first pressure matching device 14, a first desuperheater 15, a self-feeding water pump intermediate tap 16, a first valve group, a second valve group, and a third valve group. The first pressure matching device 14 is connected to the boiler 1. The first valve group is located between the first pressure matching device 14 and the boiler 1. The outlet of the first pressure matching device 14 is connected to the first desuperheater 15. One path of the first desuperheater 15 is connected to the self-feeding water pump intermediate tap 16 via the second valve group, and the other path is connected to the inlet of the secondary reheater 7 via the first electric isolation valve 17. The main path of the secondary reheater 7 is connected to the intermediate pressure cylinder 4 via the intermediate pressure regulating valve 13. The first branch of the secondary reheater 7 is connected to the first pressure matching device 14 via the third valve group. The steam supply unit includes a first desuperheater and pressure reducer 18 and a fourth valve group. The second branch of the secondary reheater 7 is connected to the first desuperheater and pressure reducer 18 via the fourth valve group. The outlet of the first desuperheater and pressure reducer 18 is connected to the industrial steam supply system 28.

[0031] For example, for a 1000MW-class thermal power unit, the pressure parameters of the high-pressure cylinder 3 are relatively high, which can meet the requirements of high-parameter steam supply. Therefore, it is generally not necessary to consider the scheme of direct main steam supply. For medium steam supply parameters, such as around 1.5MPa, the medium-pressure steam inlet parameters of 1.246MPa-2.267MPa are close to those of the thermal power unit under pure condensing conditions at 40%~75% rated load. Therefore, the basic steam supply scheme for industrial extraction of thermal power units can adopt the intermediate-pressure cylinder 4 parameter regulation, and supply steam after de-heating and de-pressure of secondary reheat steam.

[0032] Specifically, at 50% or above the rated load, the pressure of the secondary reheater 7 is 1.537MPa~3.023MPa, and steam pressure reduction is adopted for the secondary reheat hot section.

[0033] Specifically, for 35%~50% of the rated load, the steam is supplied after the steam from the intermediate pressure cylinder 4 is de-heated and depressurized by the secondary reheater 7.

[0034] When the load of the thermal power unit drops to 30-35% of the load, a branch pipe is connected from the pipeline after the secondary reheater 7. A fourth valve group is installed on the pipeline to isolate and regulate the steam flow and prevent steam backflow. The steam is supplied to the industrial steam supply system 28 after being de-cooled and de-pressurized by the first desuperheater and pressure reducer 18.

[0035] In addition, if the flow rate of the secondary reheater 7 decreases significantly, a branch pipe can be connected from the main steam pipeline from boiler 1 to ultra-high pressure cylinder 2 through the secondary reheat return steam unit. A first valve group is installed on the pipeline to isolate and regulate the steam flow rate and prevent steam backflow. The main steam passes through the first pressure matching device 14 and injects the secondary reheat steam from the pipeline after the secondary reheater 7. A third valve group is installed on the secondary reheat steam branch pipe to isolate and prevent steam backflow. After the two steam streams are mixed by the first pressure matching device 14, they are cooled by the first desuperheater 15 and then connected to the secondary reheat cold section pipeline before the secondary reheater 7 through the first electric isolation valve 17 to supplement the secondary reheater 7 with steam and ensure the safe operation of the secondary reheater 7.

[0036] According to the embodiments of the present invention, the deep peak shaving system for reheat units can improve the steam supply guarantee capability and unit operation safety of thermal power units under low load conditions by using reheat return steam units and steam supply units.

[0037] In some embodiments of the present invention, such as Figure 1 As shown, the steam supply unit also includes: a fifth valve group and a second desuperheater 19. The inlet of the second desuperheater 19 is connected to the outlet of the primary reheater 6 through the fifth valve group, and the outlet of the second desuperheater 19 is connected to the industrial steam supply system 28.

[0038] For example, when the load of the thermal power unit drops to 30-35% of the load, a branch pipe is connected from the pipeline after the secondary reheater 7. A fourth valve group is installed on the pipeline to isolate and regulate the steam flow and prevent steam backflow. The steam is supplied to the industrial steam supply system 28 after being de-cooled and de-pressurized by the first de-cooling and pressure reducing device 18.

[0039] Furthermore, a branch pipe can be connected from the pipeline after the primary reheater 6, and a fifth valve group can be installed on the pipeline to isolate and regulate the steam flow and prevent steam backflow. The steam is desuperheated and depressurized by the second desuperheater and pressure reducer 19, and then combined with the steam output from the secondary reheater 7 to supply steam to the industrial steam supply system 28.

[0040] Meanwhile, to prevent the ultra-high pressure cylinder 2 from overloading and the steam flow rate from being too fast, the high pressure regulating valve 12 needs to be adjusted appropriately.

[0041] Furthermore, when the flow rate of the secondary reheater 7 is significantly reduced after the integrated reheater is evacuated, a branch pipe can be connected from the main steam pipeline from boiler 1 to ultra-high pressure cylinder 2 via the secondary reheat return steam unit. A first valve group is installed on the pipeline to isolate and regulate the steam flow rate and prevent steam backflow. The main steam passes through the first pressure matching device 14 and injects the secondary reheat steam from the pipeline after the secondary reheater 7. A third valve group is installed on the secondary reheat steam branch pipe to isolate and prevent steam backflow. After the two steam streams are mixed by the first pressure matching device 14, they are cooled by the first desuperheater 15 and then connected to the secondary reheat cold section pipeline before the secondary reheater 7 via the first electric isolation valve 17 to supplement the secondary reheater 7 with steam, ensuring the safe operation of the secondary reheater 7.

[0042] For example, to meet the steam supply requirement of 200t / h, the return steam volume of the secondary reheat return steam unit should reach about 150t / h to 180t / h. 50 to 60t / h of ultra-high pressure main steam (or low pressure steam) can be used, and 100 to 120t / h of secondary reheat hot section steam can be injected. After desuperheating, it returns to the secondary reheater 7. In this way, the main steam flow rate can be close to the evaporation flow rate of 24% load at 15% load. After supplying industrial steam, the steam inlet pressure of high pressure cylinder 3 is basically matched with the steam supply pressure, which can meet the steam supply requirement of 200t / h.

[0043] In some embodiments of the present invention, such as Figure 2As shown, a second electrically operated isolation valve 20 is provided between the first valve group and the first pressure matcher 14. The deep peak shaving system for the secondary reheat unit also includes an auxiliary unit, which includes: a third electrically operated isolation valve 21, a fourth electrically operated isolation valve 22, a second pressure matcher 23, a second desuperheater 24, and a sixth valve group. The second pressure matcher 23 is connected between the first valve group and the second electrically operated isolation valve 20 through a first branch pipe. The third electrically operated isolation valve 21 is provided on the first branch pipe. The outlet of the second pressure matcher 23 is connected to the second desuperheater 24. One path of the second desuperheater 24 is connected to the inlet of the primary reheater 6 through the fourth electrically operated isolation valve 22. The outlet of the primary reheater 6 is connected to the second pressure matcher 23 through the second branch pipe. The sixth valve group is provided on the second branch pipe.

[0044] In some embodiments of the present invention, such as Figure 2 As shown, the auxiliary unit also includes: a seventh valve group, and another path of the second desuperheater 24 is connected to the intermediate tap 16 of the self-feeding water pump via the seventh valve group.

[0045] In some embodiments of the present invention, such as Figure 2 As shown, a second electrically operated isolation valve 20 is installed between the first valve group and the first pressure matcher 14. The steam supply unit also includes: a fifth electrically operated isolation valve 25, an eighth valve group, a third pressure matcher 26, and a third desuperheater 27. The third pressure matcher 26 is connected between the first valve group and the second electrically operated isolation valve 20 through a third branch pipe. The fifth electrically operated isolation valve 25 is installed on the third branch pipe. The air intake of the third pressure matcher 26 is connected to the outlet of the secondary reheater 7 through a fourth branch pipe. The eighth valve group is installed on the fourth branch pipe. The outlet of the third pressure matcher 26 is connected to the third desuperheater 27. One path of the third desuperheater 27 is connected to the industrial steam supply system 28.

[0046] In some embodiments of the present invention, such as Figure 2 As shown, the steam turbine unit also includes: a ninth valve group, and another path of the third desuperheater 27 is connected to the intermediate tap 16 of the self-feeding water pump via the ninth valve group.

[0047] In some embodiments of the present invention, such as Figure 2 As shown, there are two low-pressure cylinders 5, which are connected in series.

[0048] In some embodiments of the present invention, the first valve group includes a first quick-closing regulating valve 31, a sixth electrically operated isolation valve 32, and a first pneumatic check valve 33 connected in series; the second valve group includes a first electrically operated regulating valve 41 and a seventh electrically operated isolation valve 42 connected in series; the third valve group includes a second electrically operated regulating valve 51 and an eighth electrically operated isolation valve 52 connected in series; the fourth valve group includes a second quick-closing regulating valve 61, a ninth electrically operated isolation valve 62, and a second pneumatic check valve 63 connected in series; and the fifth valve group includes a third quick-closing regulating valve 71, a tenth electrically operated isolation valve 72, and a third pneumatic check valve 73 connected in series.

[0049] In some embodiments of the present invention, the sixth valve group includes a third electrically controlled regulating valve 81 and an eleventh electrically isolated valve 82 connected in series; the seventh valve group includes a fourth electrically controlled regulating valve 91 and a twelfth electrically isolated valve 92 connected in series.

[0050] In some embodiments of the present invention, the eighth valve group includes a fifth electrically controlled regulating valve 101 and a thirteenth electrically isolated valve 102 connected in series; the ninth valve group includes a sixth electrically controlled regulating valve 111 and a fourteenth electrically isolated valve 112 connected in series.

[0051] In a specific example of the present invention, such as Figure 2 As shown, when the thermal power unit is actually operating at 50% load, the steam pressure of the secondary reheater 7 no longer meets the steam supply parameter requirements, and the intermediate pressure regulating valve 13 needs to be adjusted. When the steam supply of the thermal power unit is small below 35% load, the adjustment alone is not enough to meet the steam supply parameter requirements. When the steam supply flow rate is below 150 t / h, a combination of medium-pressure regulating valve 13 and steam injection can be considered for medium and low loads. Specifically, a branch pipe is connected from the main steam pipeline from boiler 1 to ultra-high pressure cylinder 2. A first valve group is installed on the pipeline to isolate and regulate the steam flow rate and prevent steam backflow. Another branch pipe is connected from the first valve group to the third pressure matching device 26, with isolation through the fifth electric isolation valve 25. The main steam is injected through the third pressure matching device 26 into the secondary reheat steam supplied to the industrial steam supply system 28 from the pipeline after the secondary reheater 7. The secondary reheat steam branch pipe is equipped with a fifth electric regulating valve 101 and a thirteenth electric isolation valve 102 to isolate and prevent steam backflow. The two steam streams are mixed and pressurized by the third pressure matching device 26, then cooled by the third desuperheater 27 before being connected to the industrial steam supply system 28. In this way, the industrial steam supply pressure can be increased to 1.5 MPa to 1.7 MPa.

[0052] When the steam supply demand reaches 200t / h, a branch pipe is connected from the main steam pipeline from boiler 1 to ultra-high pressure cylinder 2. A first valve group is installed on the pipeline to isolate and regulate the steam flow and prevent steam backflow. A branch pipe is then connected from the first valve group to the second pressure matching device 23. The middle is isolated by the third electric isolation valve 21. The main steam is injected from the hot section of the primary reheater 6 after the primary reheater 6 through the second pressure matching device 23. The primary reheat steam branch pipe is equipped with a third electric regulating valve 81 and an eleventh electric isolation valve 82 to isolate and prevent steam backflow. The two steam streams are mixed and pressurized by the second pressure matching device 23 and then cooled by the second desuperheater 24. Then, they are connected to the cold section of the primary reheater 6 before the primary cold reheater 6 through the fourth electric isolation valve 22 to prevent the primary reheater 6 from overheating. Meanwhile, a branch pipe must be connected from the first valve group to the first pressure matching device 14, and the middle is isolated by the third electric isolation valve 21. The main steam is drawn from the secondary reheat hot section steam after the secondary reheater 7 through the first pressure matching device 14. The secondary reheat steam branch pipe is equipped with the second electric regulating valve 51 and the eighth electric isolation valve 52 to isolate and prevent steam backflow. The two steam streams are mixed and pressurized by the first pressure matching device 14 and then cooled by the first desuperheater 15. Then, they are connected to the secondary reheat cold section steam pipeline before the secondary reheater 7 through the first electric isolation valve 17 to prevent the secondary reheater 7 from overheating.

[0053] Other configurations and operations of the deep peak shaving system for a reheat unit according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0054] In the description of this specification, references to terms such as "some embodiments," "optionally," "furthermore," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0055] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A deep peak-shaving system for a double reheat unit, characterized in that, include: A thermal power unit, comprising a boiler (1), an ultra-high pressure cylinder (2), a high pressure cylinder (3), an intermediate pressure cylinder (4), a low pressure cylinder (5), a primary reheater (6), and a secondary reheater (7). Steam generated by the boiler (1) passes sequentially through the ultra-high pressure cylinder (2), the high pressure cylinder (3), the intermediate pressure cylinder (4), and the low pressure cylinder (5) via steam pipes to convert the thermal energy of the steam into mechanical energy. The converted mechanical energy is used to drive a generator (8) to generate electricity. The primary reheater (6) is connected to the ultra-high pressure cylinder (2). Between the high-pressure cylinder (3) and the secondary reheater (7), the secondary reheater (7) is connected between the high-pressure cylinder (3) and the intermediate-pressure cylinder (4). The inlet of the primary reheater (6) is provided with a first exhaust check valve (9), the inlet of the secondary reheater (7) is provided with a second exhaust check valve (10), the inlet of the ultra-high pressure cylinder (2) is provided with an ultra-high pressure regulating valve (11), the inlet of the high-pressure cylinder (3) is provided with a high-pressure regulating valve (12), and the inlet of the intermediate-pressure cylinder (4) is provided with a medium-pressure regulating valve (13). The secondary reheat steam generator unit includes a first pressure matching device (14), a first desuperheater (15), a self-feeding water pump intermediate tap (16), a first valve group, a second valve group, and a third valve group. The first pressure matching device (14) is connected to the boiler (1). The first valve group is located between the first pressure matching device (14) and the boiler (1). The outlet of the first pressure matching device (14) is connected to the first desuperheater (15). One path of the first desuperheater (15) is connected to the self-feeding water pump intermediate tap (16) through the second valve group, and the other path is connected to the inlet of the secondary reheater (7) through the first electric isolation valve (17). The main path of the secondary reheater (7) is connected to the intermediate pressure cylinder (4) through the intermediate pressure regulating valve (13). The first branch path of the secondary reheater (7) is connected to the first pressure matching device (14) through the third valve group. The steam supply unit includes a first desuperheater (18) and a fourth valve group. The second branch of the secondary reheater (7) is connected to the first desuperheater (18) through the fourth valve group. The outlet of the first desuperheater (18) is connected to the industrial steam supply system (28).

2. The deep peak-shaving system for a double reheat unit according to claim 1, characterized in that, The steam supply unit also includes: a fifth valve group and a second desuperheater (19), the inlet of the second desuperheater (19) is connected to the outlet of the primary reheater (6) through the fifth valve group, and the outlet of the second desuperheater (19) is connected to the industrial steam supply system (28).

3. The deep peak-shaving system for a double reheat unit according to claim 1, characterized in that, A second electric isolation valve (20) is provided between the first valve group and the first pressure matcher (14). The deep peak shaving system for the secondary reheat unit also includes an auxiliary unit, which includes: a third electric isolation valve (21), a fourth electric isolation valve (22), a second pressure matcher (23), a second desuperheater (24), and a sixth valve group. The second pressure matcher (23) is connected between the first valve group and the second electric isolation valve (20) through the first branch pipe. The third electric isolation valve (21) is provided on the first branch pipe. The outlet of the second pressure matcher (23) is connected to the second desuperheater (24). One of the second desuperheaters (24) is connected to the inlet of the primary reheater (6) through the fourth electric isolation valve (22). The outlet of the primary reheater (6) is connected to the second pressure matcher (23) through the second branch pipe. The sixth valve group is provided on the second branch pipe.

4. The deep peak-shaving system for a double reheat unit according to claim 3, characterized in that, The auxiliary unit also includes a seventh valve group, through which another path of the second desuperheater (24) is connected to the intermediate tap (16) of the self-supply water pump.

5. The deep peak-shaving system for a double reheat unit according to claim 1, characterized in that, A second electric isolation valve (20) is provided between the first valve group and the first pressure matcher (14). The steam supply unit also includes: a fifth electric isolation valve (25), an eighth valve group, a third pressure matcher (26), and a third desuperheater (27). The third pressure matcher (26) is connected between the first valve group and the second electric isolation valve (20) via a third branch pipe, and the third branch pipe is equipped with the fifth electric isolation valve (25). The intake port of the third pressure matching device (26) is connected to the outlet of the secondary reheater (7) through the fourth branch pipe, and the fourth branch pipe is equipped with the eighth valve group. The outlet of the third pressure matching device (26) is connected to the third desuperheater (27), and one of the third desuperheaters (27) is connected to the industrial steam supply system (28).

6. The deep peak-shaving system for a double reheat unit according to claim 5, characterized in that, The steam supply unit also includes a ninth valve group, and another path of the third desuperheater (27) is connected to the intermediate tap (16) of the self-feeding water pump via the ninth valve group.

7. The deep peak-shaving system for a double reheat unit according to claim 1, characterized in that, There are two low-pressure cylinders (5), and the two low-pressure cylinders (5) are connected in series.

8. The deep peak-shaving system for a double reheat unit according to claim 2, characterized in that, The first valve group includes a first quick-closing regulating valve (31), a sixth electrically operated isolation valve (32), and a first pneumatic check valve (33) connected in series. The second valve group includes a first electrically controlled regulating valve (41) and a seventh electrically controlled isolation valve (42) connected in series. The third valve group includes a second electrically controlled regulating valve (51) and an eighth electrically isolated valve (52) connected in series. The fourth valve group includes a second fast-closing regulating valve (61), a ninth electric isolation valve (62), and a second pneumatic check valve (63) connected in series. The fifth valve group includes a third quick-closing regulating valve (71), a tenth electric isolation valve (72), and a third pneumatic check valve (73) connected in series.

9. The deep peak-shaving system for a double reheat unit according to claim 4, characterized in that, The sixth valve group includes a third electrically controlled regulating valve (81) and an eleventh electrically isolated valve (82) connected in series. The seventh valve group includes a fourth electrically controlled regulating valve (91) and a twelfth electrically isolated valve (92) connected in series.

10. The deep peak-shaving system for a double reheat unit according to claim 6, characterized in that, The eighth valve group includes a fifth electric regulating valve (101) and a thirteenth electric isolation valve (102) connected in series. The ninth valve group includes a sixth electrically controlled regulating valve (111) and a fourteenth electrically isolated valve (112) connected in series.

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