Redundant overspeed protection interrupting system for small steam turbine

Abstract

The utility model provides a redundancy overspeed protection interrupting system for a small steam turbine, which comprises a main steam valve of the small steam turbine arranged at a main steam inlet end of the small steam turbine, a hanging gate key arranged on the main steam valve of the small steam turbine and used for controlling the main steam valve to be closed, an electromagnet interrupting device and a butterfly valve interrupting device arranged on a main steam supply pipe of the small steam turbine, the speed measuring device is used for detecting the rotating speed of the small steam turbine; and the control system further comprises a PLC (Programmable Logic Controller) which can receive a signal of the speed measuring device and can control the electromagnet blocking device and the butterfly valve blocking device. According to the utility model, the electromagnet interrupting device and the butterfly valve interrupting device are arranged to form redundant overspeed protection, the two overspeed protection interrupting devices are adopted, can work simultaneously, can quickly respond and control the speed reduction of the small steam turbine, and meanwhile, two insurance of overspeed protection of the small steam turbine is formed, so that the reliability of the overspeed protection system of the small steam turbine is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of steam turbine speed control, in particular to a redundant overspeed protection tripping system for a small steam turbine. Background Art

[0002] The overspeed protection system of industrial small steam turbine consists of two sets of protection devices: electric overspeed protection device and mechanical overspeed protection device. When the steam turbine is overspeeding, the emergency tripping device connecting rod is actuated to make the steam turbine automatically shut down in an emergency. The purpose of stopping can also be achieved by manually or remotely actuating the rotating shaft. The overspeed protection system is an important device to ensure the safe operation of the steam turbine and prevent accidents. The existing unit's safety system consists of the following components: emergency tripping device emergency tripping connecting rod and electromagnet. The emergency tripping device is a fly hammer type, installed on the extended shaft of the steam turbine rotor. At normal speed, the centrifugal force generated by the fly hammer is less than the preload force of the spring. When the speed is 110-112% of the normal rated speed, the centrifugal force will be greater than the preload force of the spring and hit the knockout rod of the emergency tripping device connecting rod, driving the entire connecting rod mechanism to rotate the rotating shaft on the steam valve assembly, and the main steam valve is released and quickly closed. When the speed decreases, the centrifugal force decreases and the flyweight returns to its original position under the action of the spring force.

[0003] Due to the poor reliability and spring adjustment linearity of the mechanical overspeed protection device, the test verifies that its stability is poor and its adjustment ability is poor. At the same time, the sensitivity of the small steam turbine electric overspeed protection device is poor; in addition, when the electric overspeed protection device is activated, it takes about 20 seconds for the steam inlet electric door to close, which cannot meet the requirements of "quick action and tight closure". If the small steam turbine overspeeds, the electric overspeed protection device cannot provide timely and effective overspeed protection for the small steam turbine, and there are still safety hazards. The mechanical overspeed protection device may affect the stability of the electric overspeed protection device. In view of this, a redundant overspeed protection tripping system is provided. Summary of the invention

[0004] The technical solution adopted by the utility model to solve its technical problems is:

[0005] A redundant overspeed protection tripping system for a small steam turbine is provided, comprising a main steam valve of a small steam turbine arranged at a main steam inlet end of the small steam turbine, a latching key for controlling the closing of the main steam valve of the small steam turbine being arranged on the main steam valve of the small steam turbine, and an electromagnet tripping device, wherein the electromagnet tripping device comprises an electromagnet, a push rod being installed at the output end thereof, a driving rod being hinged at the end of the push rod, a rotating shaft being arranged at the end thereof, the rotating shaft being hinged on the housing of the main steam valve of the small steam turbine, and a shift fork being arranged at one end of the rotating shaft, and the shift fork being able to drive the shift fork to be linked with the latching key when the rotating shaft rotates;

[0006] It also includes a butterfly valve shutoff device arranged on the main steam supply pipe of the small steam turbine;

[0007] It also includes a speed measuring device for detecting the speed of the small steam turbine;

[0008] It also includes a PLC controller, which can receive the speed measuring device signal and control the electromagnet shutoff device and the butterfly valve shutoff device.

[0009] Preferably, the butterfly valve shut-off device is a pneumatic butterfly valve shut-off device.

[0010] Preferably, the front end of the driving rod is extended and arranged on the counterweight block.

[0011] Preferably, a thread is provided at the front end of the driving rod, and the counterweight is screwed onto the driving rod.

[0012] The beneficial effect of the utility model is that the novel arrangement of the electromagnetic shut-off device and the butterfly valve shut-off device constitutes redundant overspeed protection, and the two overspeed protection shut-off devices are used, which can work simultaneously, can respond quickly and control the deceleration of the small steam turbine, and at the same time, constitute two insurances for the overspeed protection of the small steam turbine, thereby ensuring the reliability of the overspeed protection system of the small steam turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 It is a structural schematic diagram of a redundant overspeed protection tripping system for a small steam turbine in an embodiment of the utility model;

[0015] Figure 2 It is a schematic diagram of the structure of the electromagnet interrupting device in the embodiment of the utility model;

[0016] In the figure: 1-electromagnet shut-off device, 1.1-electromagnet, 1.2-push rod, 1.3-rotating shaft, 1.4-driving rod, 1.5-counterweight, 2-butterfly valve shut-off device, 3-small steam turbine, 3.1-main steam valve of small steam turbine, 3.11-locking key, 4-main steam supply pipe, 5-speed measuring device, 6-PLC controller. DETAILED DESCRIPTION

[0017] The above scheme is further described below in conjunction with specific examples. It should be understood that these examples are used to illustrate the utility model rather than to limit the scope of the utility model. The implementation conditions used in the examples can be further adjusted according to the conditions of the specific manufacturer, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0018] In a specific embodiment, a small steam turbine redundant overspeed protection tripping system is provided, including a small steam turbine main steam valve 3.1 arranged at the main steam inlet end of the small steam turbine 3, the main steam valve 3.1 can block the main steam supply pipe 4 from supplying steam to the small steam turbine. Since the small steam turbine main steam valve 3.1 requires a large torque to close and is difficult to be directly turned by hand, a latching key 3.11 for controlling the closing of the small steam turbine main steam valve 3.1 is provided on the small steam turbine main steam valve 3.1, the latching key 3.11 is equivalent to a control switch, and the state change of the small steam turbine main steam valve 3.1 can be realized by changing its state.

[0019] In order to realize the fast and reliable overspeed protection of small steam turbines in this application, two overspeed protection tripping devices are used, which can work at the same time, thus forming redundant overspeed protection, forming two insurances for overspeed protection of small steam turbines, and ensuring the reliability of the overspeed protection system of small steam turbines. Specifically, it includes an electromagnet tripping device and a butterfly valve tripping device.

[0020] Among them, the electromagnet blocking device includes an electromagnet 1.1, a push rod 1.2 is installed at its output end, and the push-pull movement of the push rod 1.2 can be realized by turning the electromagnet on and off. In addition, a driving rod 1.4 is hinged at the end of the push rod 1.2, and a rotating shaft 1.3 is arranged at its end. The rotating shaft 1.3 is hinged on the housing of the main steam valve 3.1 of the small steam turbine. Therefore, the push rod 1.2 and the driving rod 1.4 can form a linked connecting rod mechanism, and a shift fork is arranged at one end of the rotating shaft 1.3. When the electromagnet is working, the rotating shaft 1.3 can be driven to rotate through the connecting rod structure to drive the shift fork to link with the gate key 3.11. The action torque and action stroke of the electromagnet are reasonably selected by calculation to improve the action speed and reliability. On this basis, the front end of the driving rod 1.4 is extended and arranged on the counterweight block 1.5. The weight of the electromagnet core is offset by the counterweight block, so that the torque on both sides of the connecting rod is consistent, and the misoperation caused by the inconsistent gravity on both sides of the connecting rod during operation is prevented. The stability is increased and the risk of misoperation and refusal to operate is reduced. To further facilitate the adjustment of the position of the counterweight 1.5, a thread is provided at the front end of the driving rod 1.4, and the counterweight 1.5 is screwed on the driving rod 1.4, and can be adjusted by screwing the thread.

[0021] Among them, the butterfly valve shut-off device is arranged on the main steam supply pipe 4 of the small steam turbine 3. Similar to the prior art, the butterfly valve shut-off device includes a butterfly valve body and a controller, and the valve can be quickly controlled to be on and off by the controller. In order to further facilitate the control of the valve in the butterfly valve shut-off device, an electrically controlled butterfly valve or a pneumatically controlled butterfly valve can be adopted, but a pneumatically controlled butterfly valve is preferred. Specifically, a set of pneumatic butterfly valves with rapid action and tight closure is added on the steam inlet side. The pneumatic butterfly valve can immediately shut off the steam inlet of the heating small steam turbine upon receiving the shut-off signal. In addition, the pneumatic butterfly valve adopts the normally open control form of air loss, which can avoid the valve suddenly closing due to loose air source of the butterfly valve, causing the heating to stop.

[0022] In addition, it also includes a speed measuring device 5 for detecting the rotation speed of the small steam turbine 3, and a PLC controller capable of receiving signals from the speed measuring device 5 and controlling the electromagnet shutoff device and the butterfly valve shutoff device.

[0023] In specific operation, when the speed measuring device 5 detects that the small steam turbine 3 is overspeeding, a signal will be sent to the PLC controller (the control signal source is the small steam turbine speed feedback signal. When the speed of the small steam turbine exceeds 1650r / min, the overspeed protection action is triggered, and the electromagnetic shut-off device and the pneumatic butterfly valve shut-off device are controlled to act simultaneously). By processing the PLC controller, the electromagnetic shut-off device and the butterfly valve shut-off device send signals simultaneously, and the electromagnetic shut-off device disengages the latching key in the main steam valve of the small machine, and the main steam valve of the small machine is quickly closed under the action of the spring force; when the butterfly valve shut-off device receives the signal, the controller controls the valve body to work and immediately shuts off the steam inlet channel of the heating small steam turbine. Therefore, by working simultaneously with two sets of shut-off devices, the speed control of the small steam turbine can be realized efficiently and quickly, and the two sets of redundant overspeed protection improve the reliability and stability of the speed control. Relying on the speed signal, it can act quickly and strictly cut off the driving steam source.

[0024] In addition, since small steam turbines are usually connected to the heating system, after the application of the redundant overspeed protection tripping system for small steam turbines, there was no accidental shutdown of the small steam turbines for heating during the year. This not only improves the inherent safety of the heating equipment, saves a lot of maintenance costs and construction time, but also greatly improves the stability of winter heating.

[0025] Based on the above ideal embodiments of the utility model, the relevant staff can make various changes and modifications without departing from the technical concept of the invention through the above description. The technical scope of the invention is not limited to the content of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A redundant overspeed protection tripping system for a small steam turbine, comprising a small steam turbine main steam valve (3.1) arranged at the main steam inlet end of the small steam turbine (3), a latching key (3.11) for controlling the closing of the small steam turbine main steam valve (3.1) being arranged on the small steam turbine main steam valve (3.1), characterized in that: It also includes an electromagnet shutoff device, the electromagnet shutoff device including an electromagnet (1.1), a push rod (1.2) installed at its output end, a driving rod (1.4) hinged at the end of the push rod (1.2), a rotating shaft (1.3) provided at the end thereof, the rotating shaft (1.3) hinged on the housing of the main steam valve (3.1) of the small steam turbine, and a shift fork provided at one end of the rotating shaft (1.3), the rotating shaft (1.3) being able to drive the shift fork to move in conjunction with the brake key (3.11) when rotating; It also includes a butterfly valve shutoff device arranged on the main steam supply pipe (4) of the small steam turbine (3); It also includes a speed measuring device (5) for detecting the rotation speed of the small steam turbine (3); It also includes a PLC controller (6) capable of receiving a signal from the speed measuring device (5) and controlling the electromagnetic shutoff device and the butterfly valve shutoff device.

2. A small steam turbine redundant overspeed protection tripping system as claimed in claim 1, characterized in that: The butterfly valve shut-off device is a pneumatic butterfly valve shut-off device.

3. A small steam turbine redundant overspeed protection tripping system as claimed in claim 1, characterized in that: The front end of the driving rod (1.4) is extended and arranged on the counterweight block (1.5).

4. A small steam turbine redundant overspeed protection tripping system as claimed in claim 3, characterized in that: The front end of the driving rod (1.4) is provided with a thread, and the counterweight block (1.5) is screwed onto the driving rod (1.4).

Images