Steam turbine admission system with adjustable steam ejector and method of regulation

Abstract

The application discloses a steam turbine admission system with an adjustable steam ejector and an adjusting method. The system comprises a main steam regulating valve, a supplementary steam inlet stop valve, an adjustable steam ejector, a supplementary steam outlet stop valve, a steam extraction check valve, a high-pressure cylinder and corresponding pipeline systems. The steam flow into the high-pressure cylinder is adjusted by the supplementary steam system and the adjustable steam ejector, so that the main steam pressure of the steam turbine under low load is greatly increased. During the process of increasing the load of the steam turbine from low load to high load, the operation mode of the steam turbine is changed from sliding pressure operation to constant pressure operation, and the extra steam enters the supplementary steam chamber through the supplementary steam pipeline system, mixes with the incoming steam and does work. During the process of reducing the load of the steam turbine, the steam flow is reduced to a critical value, the supplementary steam pipeline stop valve is closed, and the operation mode of the steam turbine is changed from constant pressure operation to sliding pressure operation. The steam into the high-pressure cylinder is kept at high parameters under low load by reasonably arranging the supplementary steam system, the steam flow is controlled by moving the position of the adjustable steam ejector adjusting device, the load change of the steam turbine is adapted, the flow loss is reduced, and the thermal economy is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steam turbine load regulation, and particularly relates to a steam turbine admission system with an adjustable steam ejector and a regulation method. BACKGROUND

[0002] Large-scale grid connection of renewable energy power generation has affected the stability of the power grid, and thermal power units can improve the stability of the power grid through deep peak regulation technology, but the admission pressure of the steam turbine of the unit will be significantly reduced when the unit is operated at ultra-low load. The coal consumption rate of a conventional condensing unit is higher than that at the design condition at low load, which seriously reduces the thermal economy of the unit and cannot effectively exert the design advancement of large units. Developing complete sets of technology related to high-efficiency peak-regulation steam turbines and improving the technical level of the electric power industry have significant economic and social benefits.

[0003] There are two ways to improve the cycle efficiency of a steam turbine system: one is to increase the initial steam parameter and reduce the final parameter; and the other is to adopt a new type of thermal cycle system design. The existing steam turbine admission mode includes nozzle admission, throttling admission and sliding pressure admission. Only at the rated condition, the admission pressure of the high-pressure cylinder reaches the rated value. At the low load condition, the admission pressure is lower than the rated value, and there is throttling loss and partial admission loss, which affects the economy and safety of the unit. Developing a steam turbine admission operation system that can improve the admission pressure at low load can further reduce the energy consumption level of coal-fired units and improve the flexibility and load regulation capacity. SUMMARY

[0004] In order to further improve the thermal economy of coal-fired units at partial load and increase the wide load regulation capacity, the present application provides a steam turbine admission system with an adjustable steam ejector and a regulation method.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] A steam turbine admission system with adjustable steam ejector, comprising a main steam admission pipe 1, a main steam regulating valve 2, a supplementary steam admission pipe 3, a supplementary steam admission inlet stop valve 4, an adjustable steam ejector 5, a supplementary steam outlet stop valve 6, a supplementary steam chamber 7, a steam extraction check valve 8, a steam extraction pipe 9, a high-pressure cylinder exhaust pipe 10 and a high-pressure cylinder 11; the outlet of the main steam admission pipe 1 is connected with the inlet of the main steam regulating valve 2, the outlet of the main steam regulating valve 2 is connected with the steam inlet of the high-pressure cylinder 11; the other outlet of the main steam admission pipe 1 is connected with the inlet of the supplementary steam admission pipe 3, the outlet of the supplementary steam admission pipe 3 is connected with the inlet of the supplementary steam admission inlet stop valve 4, the outlet of the supplementary steam admission inlet stop valve 4 is connected with the inlet of the adjustable steam ejector 5, the outlet of the adjustable steam ejector 5 is connected with the inlet of the supplementary steam outlet stop valve 6, the outlet of the supplementary steam outlet stop valve 6 is connected with the inlet of the supplementary steam chamber 7 of the high-pressure cylinder 11; the steam extraction outlet of the high-pressure cylinder 11 is connected with the inlet of the steam extraction check valve 8; the outlet of the steam extraction check valve 8 is connected with the other inlet of the adjustable steam ejector 5 through the steam extraction pipe 9; the inlet of the high-pressure cylinder exhaust pipe 10 is connected with the steam exhaust outlet of the high-pressure cylinder 11.

[0007] The design flow of the high-pressure cylinder stage group between the main steam regulating valve 2 and the supplementary steam outlet stop valve 6 is less than the design flow of the high-pressure cylinder stage group between the supplementary steam outlet stop valve 6 and the high-pressure cylinder exhaust pipe 10, and the design flow of the high-pressure cylinder stage group between the supplementary steam outlet stop valve 6 and the high-pressure cylinder exhaust pipe 10 is equal to the design flow of the rated working condition of the steam turbine system.

[0008] The nozzle throat of the adjustable steam ejector 5 has an adjusting device, and the nozzle throat area is adjusted by changing the position of the adjusting device.

[0009] The adjusting method of the steam turbine admission system with adjustable steam ejector, comprising a low-load operation mode of the steam turbine, a high-load operation mode of the steam turbine, a load increase adjusting method of the steam turbine and a load decrease adjusting method of the steam turbine:

[0010] In the low-load operation mode of the steam turbine, the steam turbine is in the sliding pressure operation stage, the supplementary steam admission inlet stop valve 4 and the supplementary steam outlet stop valve 6 are in the closed state, the main steam enters the high-pressure cylinder 11 through the main steam admission pipe 1 and the main steam regulating valve 2 to do work, and the exhaust steam is discharged through the high-pressure cylinder exhaust pipe 10.

[0011] In the high-load operation mode of the steam turbine, the steam turbine is in the constant pressure operation stage, the supplementary steam admission inlet stop valve 4 and the supplementary steam outlet stop valve 6 are in the open state, the main steam is divided into two streams, one stream enters the high-pressure cylinder 11 through the main steam admission pipe 1 and the main steam regulating valve 2 to do work; the other stream enters the supplementary steam chamber 7 after being reduced in parameters through the supplementary steam admission pipe 3, the supplementary steam admission inlet stop valve 4, the adjustable steam ejector 5 and the supplementary steam outlet stop valve 6, mixes with the flow steam and then enters the high-pressure cylinder 11 to do work, and the exhaust steam is discharged through the high-pressure cylinder exhaust pipe 10.

[0012] The turbine load rising regulation method, in the process of turbine load turning from low load to high load, the main steam flow is less than the critical value, the turbine is in sliding pressure operation stage, the main steam enters the high pressure cylinder 11 to do work through the main steam inlet pipeline 1 and the main steam regulating valve 2; the main steam flow gradually increases to the critical value, the main steam pressure reaches the rated value, the supplementary steam inlet stop valve 4 and the supplementary steam outlet stop valve 6 are opened; the main steam flow continues to increase, the turbine is in constant pressure operation stage, the steam exceeding the critical value is branched off through the supplementary steam inlet pipeline 3 and the adjustable steam ejector 5, fully mixes with the low parameter steam from the steam extraction pipeline 9 and then enters the high pressure cylinder 11 to do work, and the steam extraction amount and the supplementary steam amount entering the adjustable steam ejector 5 are closely related to the turbine operation load.

[0013] The turbine load rising regulation method, in the process of turbine load turning from low load to high load, the main steam flow is less than the critical value, the turbine is in sliding pressure operation stage, the main steam enters the high pressure cylinder 11 to do work through the main steam inlet pipeline 1 and the main steam regulating valve 2; the main steam flow gradually increases to the critical value, the main steam pressure reaches the rated value, the supplementary steam inlet stop valve 4 and the supplementary steam outlet stop valve 6 are opened; the main steam flow continues to increase, the turbine is in constant pressure operation stage, the steam exceeding the critical value is branched off through the supplementary steam inlet pipeline 3 and the adjustable steam ejector 5, fully mixes with the low parameter steam from the steam extraction pipeline 9 and then enters the high pressure cylinder 11 to do work, and the steam extraction amount and the supplementary steam amount entering the adjustable steam ejector 5 are closely related to the turbine operation load.

[0014] Compared with the prior art, the present application has the following advantages:

[0015] 1. The present application can adjust the steam flow entering the high pressure cylinder by reasonably arranging the supplementary steam system, improve the main steam pressure of the turbine system under low load, and improve the cycle efficiency.

[0016] 2. The present application integrates the adjustable steam ejector, changes the nozzle throat area by moving the position of the adjusting device, adjusts the steam flow passing through, reduces the flow loss in the flow process, and improves the energy utilization rate.

[0017] 3. The present application controls the steam flow entering the supplementary steam system by adjusting the stop valve, has the frequency regulation function without adjusting the main regulating valve, quickly puts in the adjustable steam ejector, improves the power regulation response speed and response amount of the steam turbine. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a steam turbine inlet system schematic diagram with an adjustable steam ejector. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1 As shown, the present invention discloses a steam turbine inlet system with an adjustable steam ejector, comprising a main steam inlet pipe 1, a main steam regulating valve 2, a make-up steam inlet pipe 3, a make-up steam inlet shut-off valve 4, an adjustable steam ejector 5, a make-up steam outlet shut-off valve 6, a make-up steam chamber 7, an extraction steam check valve 8, an extraction steam pipe 9, a high-pressure cylinder exhaust pipe 10, and a high-pressure cylinder 11; one outlet of the main steam inlet pipe 1 is connected to the inlet of the main steam regulating valve 2, and the outlet of the main steam regulating valve 2 is connected to the inlet of the high-pressure cylinder 11; the other outlet of the main steam inlet pipe 1 is connected to the inlet of the make-up steam inlet pipe 3. The outlet of the supplementary steam inlet pipe 3 is connected to the inlet of the supplementary steam inlet shut-off valve 4. The outlet of the supplementary steam inlet shut-off valve 4 is connected to the inlet of the adjustable steam ejector 5. The outlet of the adjustable steam ejector 5 is connected to the inlet of the supplementary steam outlet shut-off valve 6. The outlet of the supplementary steam outlet shut-off valve 6 is connected to the inlet of the supplementary steam chamber 7 of the high-pressure cylinder 11. The extraction steam outlet of the high-pressure cylinder 11 is connected to the inlet of the extraction steam check valve 8. The outlet of the extraction steam check valve 8 is connected to another inlet of the adjustable steam ejector 5 through the extraction steam pipe 9. The inlet of the high-pressure cylinder exhaust pipe 10 is connected to the exhaust steam outlet of the high-pressure cylinder 11.

[0021] The design flow rate of the high-pressure cylinder stage group between the main steam regulating valve 2 and the supplementary steam outlet shut-off valve 6 is less than the design flow rate of the high-pressure cylinder stage group between the supplementary steam outlet shut-off valve 6 and the high-pressure cylinder exhaust pipe 10, and the design flow rate of the high-pressure cylinder stage group between the supplementary steam outlet shut-off valve 6 and the high-pressure cylinder exhaust pipe 10 is equal to the design flow rate of the turbine system under rated operating conditions. By reducing the characteristic flow area of ​​the high-pressure cylinder, the inlet steam pressure under partial load is increased; and a supplementary steam system is configured to ensure that the output under rated operating conditions meets the requirements.

[0022] The adjustable steam ejector 5 has an adjustment device at the nozzle throat. In this embodiment, an adjustment cone is used. By changing the position of the adjustment cone, the nozzle throat area is adjusted to adapt to different turbine operating conditions. Compared with a supplementary steam regulating valve, it reduces throttling losses during the flow process and improves energy utilization. Compared with a fixed-structure ejector, the adjustable ejector has higher working efficiency and a wider range of flow regulation under different operating conditions.

[0023] The method for regulating a steam turbine inlet system with an adjustable steam ejector includes a steam turbine low-load operation mode, a steam turbine high-load operation mode, a steam turbine load increase regulation method, and a steam turbine load decrease regulation method.

[0024] The low turbine load operation mode, the turbine is in the sliding pressure operation stage, the supplementary steam inlet stop valve 4 and the supplementary steam outlet stop valve 6 are in the closed state, the main steam enters the high-pressure cylinder 11 to do work through the main steam inlet pipeline 1 and the main steam regulating valve 2, and the exhaust steam is discharged through the high-pressure cylinder exhaust pipeline 10.

[0025] The high turbine load operation mode, the turbine is in the constant pressure operation stage, the supplementary steam inlet stop valve 4 and the supplementary steam outlet stop valve 6 are in the open state, the main steam is divided into two streams, one stream enters the high-pressure cylinder 11 to do work through the main steam inlet pipeline 1 and the main steam regulating valve 2, and the other stream enters the high-pressure cylinder 11 to do work after being mixed with the flow steam in the supplementary steam chamber 7 after reducing parameters through the supplementary steam inlet pipeline 3, the supplementary steam inlet stop valve 4, the adjustable steam ejector 5 and the supplementary steam outlet stop valve 6, and the exhaust steam is discharged through the high-pressure cylinder exhaust pipeline 10.

[0026] The turbine load increasing adjustment method, in the process of the turbine load changing from low load to high load, the main steam flow is less than the critical value, the turbine is in the sliding pressure operation stage, the main steam enters the high-pressure cylinder 11 to do work through the main steam inlet pipeline 1 and the main steam regulating valve 2, the main steam flow gradually increases to the critical value, the main steam pressure reaches the rated value, the supplementary steam inlet stop valve 4 and the supplementary steam outlet stop valve 6 are opened, the main steam flow continues to increase, the turbine is in the constant pressure operation stage, the steam exceeding the critical value is divided into two streams, one stream enters the high-pressure cylinder 11 to do work after being mixed with the low-parameter steam from the steam extraction pipeline 9 through the supplementary steam inlet pipeline 3 and the adjustable steam ejector 5, and the extraction amount and the supplementary steam amount of the adjustable steam ejector 5 are closely related to the turbine operation load.

[0027] The turbine load decreasing adjustment method, in the process of the turbine load changing from high load to low load, the main steam flow gradually decreases with the decrease of the turbine load, before the main steam flow decreases to the critical value, the turbine is in the constant pressure operation stage, the main steam is divided into two streams, one stream enters the high-pressure cylinder 11 to do work through the main steam inlet pipeline 1 and the main steam regulating valve 2, and the other stream enters the high-pressure cylinder 11 to do work after being mixed with the low-parameter steam from the steam extraction pipeline 9 through the supplementary steam inlet pipeline 3 and the adjustable steam ejector 5, the main steam flow decreases to the critical value, the main steam pressure is the rated pressure, the adjustable steam ejector 5 stops operating, the supplementary steam inlet stop valve 4 and the supplementary steam outlet stop valve 6 are closed to prevent the steam from entering the adjustable steam ejector 5 and causing damage, the turbine load continues to decrease, the turbine is in the sliding pressure operation stage, and the main steam enters the high-pressure cylinder 11 to do work through the main steam inlet pipeline 1 and the main steam regulating valve 2.

Claims

1. A method for regulating a steam turbine inlet system with an adjustable steam ejector, the steam turbine inlet system comprising a main steam inlet pipe (1), a main steam regulating valve (2), a supplementary steam inlet pipe (3), a supplementary steam inlet shut-off valve (4), an adjustable steam ejector (5), a supplementary steam outlet shut-off valve (6), a supplementary steam chamber (7), an extraction steam check valve (8), an extraction steam pipe (9), a high-pressure cylinder exhaust pipe (10), and a high-pressure cylinder (11); one outlet of the main steam inlet pipe (1) is connected to the inlet of the main steam regulating valve (2), and the outlet of the main steam regulating valve (2) is connected to the inlet of the high-pressure cylinder (11); the other outlet of the main steam inlet pipe (1) is connected to the supplementary steam inlet pipe (3). The outlet of the supplementary steam inlet pipe (3) is connected to the inlet of the supplementary steam inlet stop valve (4), the outlet of the supplementary steam inlet stop valve (4) is connected to the inlet of the adjustable steam ejector (5), the outlet of the adjustable steam ejector (5) is connected to the inlet of the supplementary steam outlet stop valve (6), and the outlet of the supplementary steam outlet stop valve (6) is connected to the inlet of the supplementary steam chamber (7) of the high-pressure cylinder (11); the extraction steam outlet of the high-pressure cylinder (11) is connected to the inlet of the extraction steam check valve (8); the outlet of the extraction steam check valve (8) is connected to the other inlet of the adjustable steam ejector (5) through the extraction steam pipe (9); the inlet of the high-pressure cylinder exhaust pipe (10) is connected to the exhaust steam outlet of the high-pressure cylinder (11). Its features are, The adjustment method includes a turbine low-load operation mode, a turbine high-load operation mode, a turbine load increase adjustment method, and a turbine load decrease adjustment method: In the low-load operation mode of the steam turbine, the steam turbine is in the sliding pressure operation stage. The supplementary steam inlet shut-off valve (4) and the supplementary steam outlet shut-off valve (6) are closed. The main steam enters the high-pressure cylinder (11) through the main steam inlet pipe (1) and the main steam regulating valve (2) to do work. The exhaust steam is discharged through the high-pressure cylinder exhaust pipe (10). In the high-load operation mode of the steam turbine, the steam turbine is in the constant pressure operation stage. The supplementary steam inlet shut-off valve (4) and the supplementary steam outlet shut-off valve (6) are in the open state. The main steam is divided into two streams. One stream enters the high-pressure cylinder (11) from the main steam inlet pipe (1) and the main steam regulating valve (2) to do work. The other stream enters the supplementary steam chamber (7) after the parameters are reduced through the supplementary steam inlet pipe (3), the supplementary steam inlet shut-off valve (4), the adjustable steam ejector (5) and the supplementary steam outlet shut-off valve (6). After mixing with the incoming steam, it enters the high-pressure cylinder (11) to do work. The exhaust steam is discharged through the high-pressure cylinder exhaust pipe (10). The turbine load increase regulation method states that during the process of the turbine load changing from low load to high load, the main steam flow gradually increases to the critical value, the make-up steam inlet shut-off valve (4) and the make-up steam outlet shut-off valve (6) are opened, and the excess steam is diverted through the make-up steam inlet pipe (3) and the adjustable steam ejector (5) to enter the high-pressure cylinder (11) to do work, and the turbine operation mode changes from sliding pressure operation to constant pressure operation; The turbine load reduction regulation method states that during the process of the turbine load changing from high load to low load, the main steam flow gradually decreases to the critical value, the supplementary steam inlet shut-off valve (4) and the supplementary steam outlet shut-off valve (6) are closed, the adjustable steam ejector (5) stops operating, and the turbine operation mode changes from constant pressure operation to sliding pressure operation.

2. The method for adjusting a steam turbine inlet system with an adjustable steam ejector according to claim 1, characterized in that: In the high-load operation mode of the steam turbine, the steam turbine load increase regulation method and the steam turbine load decrease regulation method, part of the extracted steam in the high-pressure cylinder enters the adjustable steam ejector (5) through the extraction steam check valve (8) and the extraction steam pipeline (9), and mixes with the high-parameter steam from the make-up steam inlet pipeline (3). The steam pressure at the outlet of the adjustable steam ejector (5) is higher than the pressure of the make-up steam chamber (7). The amount of extracted steam and the amount of make-up steam entering the adjustable steam ejector (5) are closely related to the operating load of the steam turbine and increase or decrease synchronously.

3. The method for adjusting a steam turbine inlet system with an adjustable steam ejector according to claim 1, characterized in that: The design flow rate of the high-pressure cylinder group between the main steam regulating valve (2) and the supplementary steam outlet shut-off valve (6) is less than the design flow rate of the high-pressure cylinder group between the supplementary steam outlet shut-off valve (6) and the high-pressure cylinder exhaust pipe (10), and the design flow rate of the high-pressure cylinder group between the supplementary steam outlet shut-off valve (6) and the high-pressure cylinder exhaust pipe (10) is equal to the design flow rate of the turbine system under rated operating conditions.

4. The method for adjusting a steam turbine inlet system with an adjustable steam ejector according to claim 1, characterized in that: The adjustable steam injector (5) has an adjustment device at the nozzle throat, and the nozzle throat area can be adjusted by changing the position of the adjustment device.

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