Steam admission control system for steam turbine of gas-steam combined cycle single-shaft unit

Abstract

The utility model provides a steam admission control system for a steam turbine of a gas-steam combined cycle single-shaft unit, and relates to the technical field of steam turbine units. The system comprises a gas turbine and a steam turbine which are coaxially arranged, the steam turbine comprises a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder, the gas turbine is communicated with a waste heat boiler through an expansion and diffusion section, and a steam outlet of the waste heat boiler is communicated with a steam inlet pipeline of the high-pressure cylinder through a high-temperature and high-pressure steam pipeline; a high-pressure main steam valve and a high-pressure main steam adjusting valve are installed on the steam inlet pipeline, a first temperature monitoring instrument and a first pressure monitoring instrument are connected to the high-temperature and high-pressure steam pipeline, the first temperature monitoring instrument and the first pressure monitoring instrument are both electrically connected with a controller, and the controller can control the opening degree of the high-pressure main steam adjusting valve. The system can control the high-temperature and high-pressure steam inlet flow according to the measured pressure and temperature, control over the amount of steam entering a high-pressure cylinder of a steam turbine is achieved, the negative stress time is shortened, and the thermal state steam inlet rate and the starting efficiency are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of steam turbine units, in particular to a steam inlet control system of a steam turbine of a gas-steam combined cycle single-shaft unit. Background Art

[0002] Steam turbine is one of the key power equipment in power station construction. It is an energy conversion device that converts thermal energy into mechanical energy and then into electrical energy. The high-temperature, high-pressure steam generated by the boiler passes through the steam turbine, converting the thermal energy and pressure potential energy into the mechanical energy of the steam turbine, driving the output shaft of the steam turbine rotor to do work. The mechanical energy is transmitted to the generator through the output shaft of the steam turbine rotor, thereby converting the mechanical energy into electrical energy.

[0003] The gas-steam combined cycle system refers to a system that uses a gas turbine as a pre-turbine and uses a waste heat boiler to recover the exhaust heat of the gas turbine. The produced steam is injected into the steam turbine, and the steam expands in the steam turbine to do work and output electrical energy. The gas-steam combined cycle combines a gas turbine with a higher average heat absorption temperature with a steam turbine with a lower average heat release temperature, so that the high-temperature exhaust gas of the gas turbine enters the waste heat boiler to generate steam, and the steam continues to do work and generate electricity in the steam turbine, which significantly improves the thermal energy utilization rate of the entire combined cycle system compared to the simple cycle. The net efficiency of the combined cycle system can reach 48% to 62%.

[0004] At present, the steam generated by the waste heat boiler enters the steam turbine at a uniform speed controlled according to the steam inlet flow rate. At the initial stage of steam inlet, the negative stress inside the high-pressure steam turbine lasts for a long time, which is not conducive to thermal stress control, resulting in a long hot start-up time, affecting the power generation efficiency of the unit.

[0005] In view of the above reasons, the utility model proposes a steam inlet control system for a single-shaft unit steam turbine in a gas-steam combined cycle to solve the above problems. Utility Model Content

[0006] The purpose of the utility model is to provide a steam inlet control system for a single-shaft unit steam turbine in a gas-steam combined cycle, which can control the steam inlet flow rate of high-temperature and high-pressure steam according to the measured pressure and temperature, thereby realizing the control of the amount of steam entering the high-pressure cylinder, reducing the negative stress time, and improving the hot steam inlet efficiency and startup efficiency.

[0007] The utility model provides a steam inlet control system for a steam turbine of a gas-steam combined cycle single-shaft unit, comprising: a coaxially arranged gas turbine and a steam turbine, the steam turbine comprising a coaxially connected high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder, the gas turbine is connected to a waste heat boiler through an expansion and diffusion section, the steam outlet of the waste heat boiler is connected to a steam inlet pipeline of the high-pressure cylinder through a high-temperature and high-pressure steam pipeline, a high-pressure main steam valve and a high-pressure main steam regulating valve are installed on the steam inlet pipeline, the high-temperature and high-pressure steam pipeline is also connected to a first temperature monitoring instrument and a first pressure monitoring instrument, the first temperature monitoring instrument and the first pressure monitoring instrument are both electrically connected to a controller, and the controller can control the opening size of the high-pressure main steam regulating valve.

[0008] Preferably, the first pressure monitoring instrument is a pressure sensor or a digital pressure gauge, and the first temperature monitoring instrument is a temperature sensor.

[0009] Preferably, the high-temperature and high-pressure steam pipeline is connected to a bypass pipeline, and the bypass pipeline is connected to a condenser.

[0010] Preferably, a high-pressure bypass regulating valve is provided on the bypass pipeline.

[0011] Preferably, the exhaust port of the high-pressure cylinder is connected to the reheat main steam valve and the reheat regulating valve of the medium-pressure cylinder through a reheat pipe and a reheater.

[0012] Preferably, the reheat pipe is connected to a second temperature monitoring instrument and a second pressure monitoring instrument.

[0013] Preferably, the exhaust port of the intermediate pressure cylinder is connected to the low pressure cylinder through a connecting pipe, and a condenser is connected to the bottom of the low pressure cylinder.

[0014] Preferably, the condensate outlet of the condenser is connected to the interior of the waste heat boiler through a shaft seal heater.

[0015] Preferably, the controller includes a main chip, a data acquisition module, a communication module and an execution module, the first temperature monitoring instrument and the first pressure monitoring instrument are wirelessly connected to the communication module, the communication module is electrically connected to the data acquisition module, and the data acquisition module and the execution module are both electrically connected to the main chip.

[0016] Preferably, the first temperature monitoring instrument and the first pressure monitoring instrument are both provided with a 5G module or a Bluetooth module, and are wirelessly connected to the communication module via the 5G module or the Bluetooth module.

[0017] Compared with the prior art, the utility model has the following beneficial effects:

[0018] Since the high-pressure main steam regulating valve adjusts its opening according to a fixed value of the stress change rate, it is impossible to adjust the opening in real time according to the pressure and temperature of the high-temperature and high-pressure steam when the steam is introduced, so as to achieve the effect of adjusting the amount of steam entering the high-pressure cylinder of the steam turbine. Therefore, the utility model arranges temperature and pressure monitoring instruments on the high-temperature and high-pressure steam pipeline, which can measure the temperature and pressure in the pipeline. The opening of the high-pressure main steam regulating valve is controlled by the controller to achieve real-time and rapid flow adjustment, thereby effectively reducing the problem of small flow rate, small regulating valve opening and long negative stress duration in the initial stage of steam introduction, shortening the steam introduction time, and improving the hot steam introduction rate and startup efficiency of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0021] Figure 2 It is a schematic diagram of the composition of the controller in the utility model;

[0022] Description of reference numerals:

[0023] 1: gas turbine; 2: steam turbine; 21: high-pressure cylinder; 211: high-pressure main steam valve; 212: high-pressure main steam regulating valve; 22: medium-pressure cylinder; 221: reheat main steam valve; 222: reheat regulating valve; 23: low-pressure cylinder; 24: condenser; 3: expansion and diffusion section; 4: waste heat boiler; 5: first temperature monitoring instrument; 6: first pressure monitoring instrument; 7: controller; 71: main chip; 72: data acquisition module; 73: communication module; 74: execution module; 8: high-temperature and high-pressure steam pipeline; 9: bypass pipeline; 10: high-pressure bypass regulating valve; 11: reheat pipeline; 12: second temperature monitoring instrument; 13: second pressure monitoring instrument; 14: shaft seal heater; 15: reheater. DETAILED DESCRIPTION

[0024] The technical solution of the utility model will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0026] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0027] like Figure 1 , 2As shown, the utility model provides a steam inlet control system for a single-shaft steam turbine of a gas-steam combined cycle unit, comprising: a coaxially arranged gas turbine 1 and a steam turbine 2, wherein the steam turbine 2 comprises a coaxially connected high-pressure cylinder 21, an intermediate-pressure cylinder 22 and a low-pressure cylinder 23, the gas turbine 1 is connected to a waste heat boiler 4 through an expansion and diffusion section 3, the gas turbine 1 uses natural gas as fuel, the natural gas enters the combustion chamber of the gas turbine 1, and is mixed and burned with the high-pressure air compressed by the compressor, generating a high-temperature and high-pressure airflow to drive the gas turbine 1 to rotate and do work, and the high-temperature and high-pressure airflow enters the waste heat boiler 4 to heat water into high-temperature and high-pressure steam, the steam outlet of the waste heat boiler 4 is connected to the steam inlet pipeline of the high-pressure cylinder 21 through a high-temperature and high-pressure steam pipeline 8, and a high-pressure main steam valve 21 is installed on the steam inlet pipeline. 1 and a high-pressure main steam regulating valve 212, the high-temperature and high-pressure steam pipeline 8 is also connected with a first temperature monitoring instrument 5 and a first pressure monitoring instrument 6, which are respectively used to measure the inlet steam temperature and pressure, and the first temperature monitoring instrument 5 and the first pressure monitoring instrument 6 are both electrically connected to a controller 7, and the controller 7 can control the opening of the high-pressure main steam regulating valve 212; when the temperature and pressure of the high-temperature and high-pressure steam exceed the preset value, it can normally enter the high-pressure cylinder 21 to do work, and the opening of the high-pressure main steam regulating valve 212 is increased by adjusting the controller 7, which can increase the steam inlet flow rate, reduce the negative stress time in the high-pressure cylinder 21, and improve the hot steam inlet rate and startup efficiency; when the temperature and pressure of the high-temperature and high-pressure steam are insufficient, the temperature and pressure are brought to the standard by increasing the heating time of the waste heat boiler 4.

[0028] Specifically, the first pressure monitoring instrument 6 is a pressure sensor or a digital pressure gauge, and the first temperature monitoring instrument 5 is a temperature sensor.

[0029] In this embodiment, the bottom of the low-pressure cylinder 23 is connected to the condenser 24. After the high-temperature and high-pressure steam works in the high-pressure cylinder 21, it enters the medium-pressure cylinder 22 and the low-pressure cylinder 23 in turn to work. After the work is completed, the condensed water enters the condenser 24. The condensed water outlet of the condenser 24 is connected to the inside of the waste heat boiler 4 through the shaft seal heater 14. The condensed water enters the waste heat boiler 4 for further heating and evaporation after being heated by the shaft seal heater 14, which can make full use of the waste heat. The high-temperature and high-pressure steam pipeline 8 is connected to the bypass pipeline 9, and the bypass pipeline 9 is connected to the condenser 24. The bypass pipeline 9 is provided with a high-pressure bypass regulating valve 10 for controlling the bypass flow. The bypass pipeline 9 can control the flow direction of the high-temperature and high-pressure steam pipeline 8. When the high-temperature and high-pressure steam does not reach the specified temperature, the high-pressure main steam valve 211 is closed, and the high-temperature and high-pressure steam pipeline 8 is heated. The working medium of the heated pipe flows to the condenser 24 to heat the condensed water, which is convenient for it to be subsequently passed into the waste heat boiler 4 for heating and evaporation.

[0030] In this embodiment, the exhaust port of the high-pressure cylinder 21 is connected to the reheat main steam valve 221 and the reheat regulating valve 222 of the medium-pressure cylinder 22 through the reheat pipe 11 and the reheater 15. When the high-temperature and high-pressure steam has a low temperature after doing work in the high-pressure cylinder 21, it can be reheated by the reheater 15 to meet the work requirements of the medium-pressure cylinder 22. The reheat pipe 11 is connected with a second temperature monitoring instrument 12 and a second pressure monitoring instrument 13, which can measure the temperature and pressure of the steam in the reheat pipe 11. The exhaust port of the medium-pressure cylinder 22 is connected to the low-pressure cylinder 23 through a connecting pipe.

[0031] like Figure 2 As shown, the controller 7 includes a main chip 71, a data acquisition module 72, a communication module 73 and an execution module 74. The first temperature monitoring instrument 5 and the first pressure monitoring instrument 6 are wirelessly connected to the communication module 73, and the communication module 73 is electrically connected to the data acquisition module 72. The first temperature monitoring instrument 5 and the first pressure monitoring instrument 6 are both provided with a 5G module or a Bluetooth module, and are wirelessly connected to the communication module 73 through the 5G module or the Bluetooth module. The second temperature monitoring instrument 12 and the second pressure monitoring instrument 13 are also wirelessly connected to the communication module 73, so that the data acquisition module can obtain the temperature and pressure data measured by each instrument. The data acquisition module 72 and the execution module 74 are both electrically connected to the main chip 71. The temperature and pressure data can be analyzed through the main chip 71. According to the data size, the main chip 71 controls the opening size of the high-pressure main steam regulating valve 212 and the reheat regulating valve 222 through the execution module 74, and controls the operation of the reheater 15.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. A steam inlet control system for a single-shaft unit steam turbine in a gas-steam combined cycle, characterized in that: include: A gas turbine and a steam turbine are arranged coaxially, wherein the steam turbine comprises a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder which are coaxially connected, the gas turbine is connected to a waste heat boiler through an expansion diffuser section, the steam outlet of the waste heat boiler is connected to a steam inlet pipe of the high-pressure cylinder through a high-temperature and high-pressure steam pipeline, a high-pressure main steam valve and a high-pressure main steam regulating valve are installed on the steam inlet pipe, the high-temperature and high-pressure steam pipeline is also connected to a first temperature monitoring instrument and a first pressure monitoring instrument, the first temperature monitoring instrument and the first pressure monitoring instrument are both electrically connected to a controller, and the controller can control the opening size of the high-pressure main steam regulating valve.

2. The steam inlet control system for a single-shaft steam turbine in a gas-steam combined cycle according to claim 1, characterized in that: The first pressure monitoring instrument is a pressure sensor or a digital pressure gauge, and the first temperature monitoring instrument is a temperature sensor.

3. The steam inlet control system for a single-shaft steam turbine in a gas-steam combined cycle according to claim 1, characterized in that: The high-temperature and high-pressure steam pipeline is connected with a bypass pipeline, and the bypass pipeline is connected to the condenser.

4. The steam inlet control system for a single-shaft steam turbine in a gas-steam combined cycle unit according to claim 3, characterized in that: The bypass pipeline is provided with a high-pressure bypass regulating valve.

5. The steam inlet control system for a single-shaft steam turbine in a gas-steam combined cycle unit according to claim 1, characterized in that: The exhaust port of the high-pressure cylinder is connected to the reheat main steam valve and the reheat regulating valve of the medium-pressure cylinder through a reheat pipe and a reheater.

6. The steam inlet control system for a single-shaft steam turbine in a gas-steam combined cycle unit according to claim 5, characterized in that: The reheat pipe is connected to a second temperature monitoring instrument and a second pressure monitoring instrument.

7. The steam inlet control system for a single-shaft steam turbine in a gas-steam combined cycle unit according to claim 1, characterized in that: The exhaust port of the medium-pressure cylinder is connected to the low-pressure cylinder through a connecting pipe, and a condenser is connected to the bottom of the low-pressure cylinder.

8. The steam inlet control system for a single-shaft steam turbine in a gas-steam combined cycle unit according to claim 7, characterized in that: The condensate outlet of the condenser is connected to the interior of the waste heat boiler through a shaft seal heater.

9. The steam inlet control system for a single-shaft steam turbine in a gas-steam combined cycle unit according to claim 1, characterized in that: The controller includes a main chip, a data acquisition module, a communication module and an execution module. The first temperature monitoring instrument and the first pressure monitoring instrument are wirelessly connected to the communication module, the communication module is electrically connected to the data acquisition module, and the data acquisition module and the execution module are both electrically connected to the main chip.

10. The steam inlet control system for a single-shaft steam turbine in a gas-steam combined cycle unit according to claim 9, characterized in that: The first temperature monitoring instrument and the first pressure monitoring instrument are both provided with a 5G module or a Bluetooth module, and are wirelessly connected to the communication module through the 5G module or the Bluetooth module.

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