Steam inlet valve control system for steam turbine

Abstract

The steam inlet valve control system for the steam turbine comprises an EH oil pump, the EH oil pump is communicated with a distribution integrated block, the distribution integrated block is communicated with a corresponding steam inlet valve through an EH oil pipe, oil pressure transmitters are installed in front of servo valves of the steam inlet valves, and a main oil pressure transmitter is installed on a mother pipe. An oil inlet port of each EH oil pipe is provided with an electromagnetic valve, and the electromagnetic valves are connected with the DEH system through lines. According to the utility model, an abnormal oil path can be cut off before the steam turbine is not stopped, so that the oil pressure of the EH oil mother pipe is recovered to be normal, the normal operation of unit equipment is ensured, and the stability of a power grid system is maintained.

Description

Technical Field

[0001] The utility model belongs to the technical field of thermal power generation equipment, and in particular relates to a steam inlet valve control system for a steam turbine. Background Art

[0002] A steam turbine, also known as a steam turbine engine, is a rotary steam power device. High-temperature and high-pressure steam passes through a fixed nozzle and becomes an accelerated airflow, which is then sprayed onto the blades, causing the rotor with the blades to rotate and perform work externally. Steam turbines are the main equipment in modern thermal power plants and are also used in the metallurgical industry, chemical industry, and ship power devices.

[0003] The steam turbine contains a DCS control system, a DEH system and an EH oil system. The DCS control system is also called a "distributed control system" or a "distributed computer control system". It adopts the basic design concept of decentralized control, centralized operation and management, and adopts a multi-level, hierarchical, cooperative and autonomous structure. Its main features are its centralized management and decentralized control.

[0004] The DEH system is a part of the DCS system. It is a digital electro-hydraulic control system for steam turbines and an important component of steam turbine generator sets in power plants. It is a regulating controller for steam turbine start-up, stop, normal operation and accident conditions. The electro-hydraulic control system composed of the DEH control system and the EH system controls the speed, load, pressure, etc. of the steam turbine generator set by controlling the opening of the main steam valve and the regulating valve of the steam turbine.

[0005] The EH oil system, also known as the high-pressure fire-resistant oil system, is an important part of the digital electro-hydraulic system of the steam turbine. It is mainly composed of three parts: the oil supply system, the actuator, and the emergency trip system. The function of the EH oil system is to accept the output instructions of the DEH, control the opening of the air intake regulating valve, and change the steam flow entering the steam turbine to do work, so as to meet the changing requirements of the steam turbine speed and load, and at the same time maintain the safety and stability of the unit.

[0006] At present, each valve in the existing steam turbine steam inlet system is driven by EH oil, and a manual stop valve is installed in front of each valve. However, when a leak occurs in a certain oil circuit or the servo valve is stuck, the oil pressure of the EH oil main pipe will be low, causing the steam turbine to stop unexpectedly. Maintenance personnel are required to check and repair each one one by one, which seriously reduces the reliability of the equipment and affects the stability of the power grid system. Utility Model Content

[0007] The utility model aims to provide a steam inlet valve control system for a steam turbine, which can cut off the abnormal oil circuit before the steam turbine is shut down, so that the oil pressure of the EH oil mother pipe returns to normal, ensuring the normal operation of the unit equipment and maintaining the stability of the power grid system.

[0008] The technical scheme adopted by the utility model is a steam inlet valve control system for a steam turbine, comprising an EH oil pump, the EH oil pump is connected to the input end of a distribution integrated block through a main pipe, the output end of the distribution integrated block is connected to the corresponding steam inlet valve through a plurality of EH oil pipes, an oil pressure transmitter is installed in front of the servo valve of the steam inlet valve, a main oil pressure transmitter is installed on the main pipe, and the plurality of oil pressure transmitters and the main oil pressure transmitter are respectively connected to the DEH system of the steam turbine through lines;

[0009] The oil inlet port of each EH oil pipe is equipped with a solenoid valve, which is fixed in the distribution integrated block. The solenoid valve is connected to the DEH system through a line, and the DEH system is also connected to the optical sign through a line.

[0010] The technical solution of the utility model is also characterized in that:

[0011] The measuring range of the oil pressure transmitter is 0MPa~25MPa.

[0012] The solenoid valve is a Parker GS022700N cartridge-type normally open solenoid valve.

[0013] A manual shut-off valve is installed on each EH oil pipe, and the manual shut-off valve is located between the oil pressure transmitter and the solenoid valve.

[0014] Several solenoid valves are connected to the DO channel of the DEH system through lines, and the switching of the solenoid valves is controlled by the DEH system.

[0015] The steam inlet valves include main steam valve a, main steam valve b, high tuning valve a, high tuning valve b, high tuning valve c, high tuning valve d, middle main valve a, middle main valve b, middle tuning valve a and middle tuning valve b.

[0016] The beneficial effects of the utility model are:

[0017] (1) The utility model is used for the steam inlet valve control system of the steam turbine. By installing a solenoid valve at the oil circuit port of each steam inlet valve and an oil pressure transmitter in front of the servo valve of each steam inlet valve, the switch of the solenoid valve is controlled by the DEH system. When the oil pressure transmitter detects that the oil pressure in the oil circuit drops, the DEH system controls the solenoid valve of the corresponding oil circuit to close, so that the main pipe oil pressure returns to normal, ensuring that the steam turbine does not stop unexpectedly and ensuring the stable operation of the unit.

[0018] (2) The utility model is used for the steam inlet valve control system of the steam turbine. The DCS light-emitting board is installed to give an alarm. When the solenoid valve of the steam inlet valve is closed, the light-emitting board gives an alarm to remind the staff that there is an abnormality in the valve. After the solenoid valve is closed, the oil supply of the faulty steam inlet valve is promptly cut off, so that the faulty valve is closed under the action of the oil motor spring force and remains in a safe state for processing. This prevents the faulty valve from causing power oscillation of the power grid.

[0019] (3) The utility model is used for the steam inlet valve control system of the steam turbine. By setting three conditions for the emergency valve closing command, such as the oil pressure transmitter signal of the corresponding steam inlet valve drops, the main pipe oil pressure drops, and the DCS system has no tripping command, the DCS system will send a closing command to the solenoid valve of the corresponding oil circuit only when all three conditions are met, thereby avoiding the solenoid valve from being closed by mistake and affecting the stability of the unit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The utility model is a structural block diagram of a steam inlet valve control system for a steam turbine.

[0021] In the figure, 1. EH oil pump, 2. main pipe, 3. main oil pressure transmitter, 4. distribution integrated block, 5. solenoid valve, 6. EH oil pipe, 7. manual stop valve, 8. oil pressure transmitter, 9. main steam valve a, 10. main steam valve b, 11. high-adjustment valve a, 12. high-adjustment valve b, 13. high-adjustment valve c, 14. high-adjustment valve d, 15. middle main door a, 16. middle main door b, 17. middle adjustment valve a, 18. middle adjustment valve b, 19. main AND unit, 20. AND unit. DETAILED DESCRIPTION

[0022] The utility model is described in detail below with reference to the accompanying drawings and specific implementation modes.

[0023] Example 1

[0024] The utility model is used for the steam inlet valve control system of the steam turbine, such as Figure 1 As shown, it includes an EH oil pump 1, which is connected to the input end of the distribution integrated block 4 through a main pipe 2, and the output end of the distribution integrated block 4 is connected to the corresponding steam inlet valve through a plurality of EH oil pipes 6. In this embodiment, the steam inlet valves include main steam valve a9, main steam valve b10, high-adjustment valve a11, high-adjustment valve b12, high-adjustment valve c13, high-adjustment valve d14, middle main door a15, middle main door b16, middle adjustment valve a17 and middle adjustment valve b18, a total of ten steam inlet valves, each valve is separately connected to the distribution integrated block 4 through an EH oil pipe 6, and the EH oil is sent to the corresponding steam inlet valve through the EH oil pipe 6.

[0025] A high-range oil pressure transmitter 8 is installed in front of the servo valve of the steam inlet valve. The range of the oil pressure transmitter 8 is 0MPa~25MPa. In this embodiment, 10 oil pressure transmitters 8 are installed. A main oil pressure transmitter 3 is installed on the mother pipe 2. Several oil pressure transmitters 8 and the main oil pressure transmitter 3 are connected to the DEH system of the steam turbine through lines respectively; a solenoid valve 5 is installed at the oil inlet port of each EH oil pipe 6, and the solenoid valve 5 is connected to the DEH system through lines.

[0026] Specifically, the oil pressure transmitter 8 monitors the oil pressure value of the EH oil pipe 6 and transmits it to the AND unit 20 in the DEH system. When the oil pressure value of a certain EH oil pipe 6 in the data received by the AND unit 20 drops to the warning value, the AND unit 20 captures data from the main AND unit 19 in the DEH system. The main AND unit 19 obtains the oil pressure value of the main pipe 2 through the main oil pressure transmitter 3, and obtains whether the DCS system has an emergency valve closing instruction such as a tripping instruction. If the oil pressure value of the main pipe 2 drops to the warning value, and the DCS system has no emergency valve closing instruction such as a tripping instruction, the main AND unit 19 transmits a signal to the AND unit 20, and the AND unit 20 adjusts the solenoid valve 5 after receiving the signal transmitted by the main AND unit 19.

[0027] Furthermore, the solenoid valve 5 is a Parker GS022700N plug-in normally open solenoid valve, which ensures the normal oil supply flow of each valve and can cut off the oil supply in time.

[0028] Furthermore, a manual stop valve 7 is installed on each EH oil pipe, and the manual stop valve 7 is located between the oil pressure transmitter 8 and the solenoid valve 5 .

[0029] That is, the utility model detects the oil pressure of each EH oil pipe 6 through the oil pressure transmitter 8. When it is detected that the oil pressure of the EH oil pipe 6 drops, the oil pressure of the mother pipe 2 is detected. If the oil pressure of the mother pipe 2 also drops, and the oil pressures of the EH oil pipe 6 and the mother pipe 2 both drop to the warning value, the solenoid valve 5 at the front end of the EH oil pipe 6 with the dropped oil pressure can be controlled by the DEH system to close, so that the oil pressure of the mother pipe 2 returns to normal, thereby avoiding the unit from tripping.

[0030] Example 2

[0031] On the basis of Example 1, the utility model is further provided with a light sign for the steam inlet valve control system of the steam turbine, which is connected to the DEH system of the steam turbine through a line. When the DEH system controls a certain solenoid valve 5 to be closed, the light sign performs an alarm operation to remind the staff that there is an abnormality in the valve. When the solenoid valve 5 is closed to cut off the oil supply to the faulty valve, the faulty valve is closed under the action of the oil motor spring force, and remains in a safe state pending processing, thereby avoiding the power oscillation of the power grid caused by the faulty valve.

[0032] Example 3

[0033] On the basis of Example 2, the utility model is used for a plurality of solenoid valves 5 in the steam inlet valve control system of a steam turbine, which are connected to the DO channel of the steam turbine DEH system through a line, and the DEH system controls the switch of the solenoid valve 5. When the unit is operating normally, the solenoid valve 5 is in an open state.

[0034] Furthermore, the ten oil pressure transmitters 8 of this embodiment are all connected to the AI ​​(analog input) channel of the steam turbine DEH system.

[0035] The utility model installs a solenoid valve at the oil circuit port of each steam inlet valve and an oil pressure transmitter in front of the servo valve of each steam inlet valve, and controls the switch of the solenoid valve through the DEH system. When the oil pressure transmitter detects that the oil pressure in the oil circuit drops, the DEH system controls the solenoid valve of the corresponding oil circuit to close, so that the main pipe oil pressure returns to normal, ensuring that the steam turbine does not stop unexpectedly and ensuring the stable operation of the unit.

[0036] When the utility model is used, the following steps are specifically included:

[0037] Step 1, start the EH oil pump 1, the solenoid valve 5 is in the open state, and the solenoid valve 5 is kept in the open state under normal circumstances;

[0038] Step 2, the main oil pressure transmitter 3 and the oil pressure transmitter 8 respectively collect the oil pressure values ​​of the main pipe 2 and the corresponding EH oil pipe 6;

[0039] Step 3, the collected oil pressure value is transmitted to the DEH system, and the DEH system analyzes the oil pressure value of the main pipe 2, the oil pressure value of the EH oil pipe 6 and the instruction sent by the DCS system;

[0040] Further, the analysis is specifically to determine whether the oil pressure of the EH oil pipe 6 is greater than 5MPa; if the oil pressure of a certain EH oil pipe 6 reaches 5MPa or is less than 5MPa, the next step of determination is performed.

[0041] Determine whether the oil pressure of the main pipe 2 is greater than 10MPa;

[0042] Determine whether the DCS system sends a trip or valve closing command.

[0043] Step 4: the DEH system controls the solenoid valve 5 of the corresponding EH oil pipe 6 according to the analysis result.

[0044] Furthermore, step 4 is specifically as follows:

[0045] If the oil pressure of any EH oil pipe 6 is less than or equal to 5MPa and the oil pressure of the main pipe 2 is less than or equal to 10MPa, and the DCS system does not send a tripping or valve closing command, the DEH system controls the solenoid valve 5 of the EH oil pipe 6 to close; only when all three conditions are met, the DEH system will control the solenoid valve 5 of the EH oil pipe with abnormal oil pressure, and when the solenoid valve 5 is closed, the light sign will perform an alarm operation.

[0046] If the oil pressure of all EH oil pipes 6 is greater than 5MPa or the oil pressure of the main pipe 2 is greater than 10MPa or the DCS system sends a tripping or valve closing instruction, the solenoid valve 5 remains open, that is, if any one of the three conditions is not met, the DEH system will not perform any operation.

[0047] The utility model sets three conditions for emergency valve closing instructions, such as the signal drop of the oil pressure transmitter 8 corresponding to the steam inlet valve, the oil pressure drop of the main pipe 2, and the absence of a tripping instruction in the DCS system. Only when all three conditions are met, the DEH system will send a closing instruction to the solenoid valve 5 of the corresponding oil circuit, thereby avoiding the mistaken closing of the solenoid valve and affecting the stability of the unit operation.

[0048] The utility model analyzes the change trend of the oil pressure before the servo valve, and can provide a direct basis for the condition maintenance of the servo valve, instead of the current mode of combining fault maintenance and regular maintenance, thereby further improving the stability of the steam turbine.

Claims

1. A steam inlet valve control system for a steam turbine, comprising an EH oil pump (1), wherein the EH oil pump (1) is connected to an input end of a distribution manifold (4) through a main pipe (2), and an output end of the distribution manifold (4) is connected to a corresponding steam inlet valve through a plurality of EH oil pipes (6), characterized in that: An oil pressure transmitter (8) is installed in front of the servo valve of the steam inlet valve, a main oil pressure transmitter (3) is installed on the main pipe (2), and a plurality of the oil pressure transmitters (8) and the main oil pressure transmitter (3) are respectively connected to the DEH system of the steam turbine through lines; The oil inlet port of each EH oil pipe (6) is equipped with a solenoid valve (5), which is fixed in the distribution integrated block (4). The solenoid valve (5) is connected to the DEH system via a line, and the DEH system is also connected to an optical sign via a line.

2. The steam inlet valve control system for a steam turbine according to claim 1, characterized in that: The measuring range of the oil pressure transmitter (8) is 0 MPa to 25 MPa.

3. The steam inlet valve control system for a steam turbine according to claim 1, characterized in that: The solenoid valve (5) is a Parker GS022700N plug-in normally open solenoid valve.

4. The steam inlet valve control system for a steam turbine according to claim 1, characterized in that: A manual stop valve (7) is installed on each of the EH oil pipes, and the manual stop valve (7) is located between the oil pressure transmitter (8) and the solenoid valve (5).

5. The steam inlet valve control system for a steam turbine according to claim 4, characterized in that: The plurality of solenoid valves (5) are connected to the DO channel of the DEH system via a line, and the switch of the solenoid valves (5) is controlled by the DEH system.

6. The steam inlet valve control system for a steam turbine according to claim 1, characterized in that: The steam inlet valves include a main steam valve a (9), a main steam valve b (10), a high-adjustment valve a (11), a high-adjustment valve b (12), a high-adjustment valve c (13), a high-adjustment valve d (14), a middle main valve a (15), a middle main valve b (16), a middle-adjustment valve a (17) and a middle-adjustment valve b (18).

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