JP2005240739A - Steam valve safety device and method for confirming operation thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safety device for a steam turbine preventing accidents by more promptly and securely closing a steam valve, when abnormal situations occur during operation of the steam turbine. <P>SOLUTION: In this safety device for the steam turbine, a safety system 21 is provided in a pilot pressure oil line 28 branched from an emergency oil line 27 supplying pressure oil to a servomotor 24 for driving the steam valve 20 and reconnected with the emergency oil line 27. The safety system 21 has solenoid valves 29a, 29b and logic valves 33a, 33b to have a multiple structure. The safety device is provided with a trip circuit 32 for closing the steam valve 20 by exciting solenoids 31a<SB>1</SB>, 31a<SB>2</SB>provided on the solenoid valves 29a, 29b, when abnormal situations occur in the steam turbine. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a steam that quickly closes the steam valve to prevent an accident from occurring in the event of an abnormal situation in which overspeed or vibration occurs during operation of the steam turbine and the operation cannot be continued. The present invention relates to a turbine safety device and a method for confirming whether or not the turbine is operating.

  Conventionally, a steam turbine is provided with a safety device in many devices so that when an abnormal situation occurs during operation, a steam valve is one of them.

  FIG. 6 shows a steam valve, such as a main steam stop valve, applied to a steam turbine. The steam valve includes a valve rod 3 connected to a valve body 2 housed in a valve casing 1 and an oil cylinder 5 for moving the valve body 2 forward and backward relative to a valve seat 2a.

  The oil cylinder 5 accommodates the piston 5a connected to the valve rod 3 and the spring 4, and applies the pressing force of the supplied high-pressure oil to the piston 5a, changes the pressing force into a driving force, and restores the restoring force of the spring 4. The valve body 2 is opened from the valve seat 2a.

  Further, the oil cylinder 5 includes a safety system 6, controls supply / discharge of high-pressure oil supplied from the pressure oil-based emergency oil line 7, copes with an abnormal situation during operation, and closes the valve body 2. The supply of steam to the steam turbine is refused.

  The safety system 6 includes a logic valve 9 and an electromagnetic valve 10 which are provided in a closed circuit-like pilot pressure oil line 8 once branched from the emergency oil line 7 and connected to the emergency oil line 7 again.

  The logic valve 9 is provided with a piston 11 and a spring 12.

  The solenoid valve 10 includes a trip circuit 13, a solenoid 14, and a spring 12, and is configured to shut off the pressure oil supplied from the pilot pressure oil line 8 when an abnormal trip command is input to the trip circuit 13. .

  In the steam valve including the safety system 6 having such a configuration, during normal operation, high-pressure oil is supplied from the emergency oil line 7 to the oil cylinder 5 and gives a pressing force of the high-pressure oil to the piston 5a, where the pressing force is driven. Instead of the force, the valve rod 3 is pushed up against the restoring force of the spring 4 and is released from the valve seat 2a to open the valve body 2.

Further, the steam valve excites the solenoid 14 to cause the ports P ₁ and P ₂ of the solenoid valve 10 to conduct, and supplies high pressure oil from the pilot pressure oil line 8 to the logic valve 9, where the restoring force of the spring 12 is supplied. to move the piston 11 against the back pressure oil drain in the vessel from the port P ₃ to the pressure oil tank (not shown), which blocks the high pressure oil from the pilot hydraulic fluid line 8.

  On the other hand, during a normal operation, when a trip command is input to the trip circuit 13 due to the occurrence of an abnormal situation, the steam valve cuts off the excitation current A applied from the trip circuit 13 to the solenoid 14 and deenergizes the solenoid 14.

When the solenoid 14 is de-energized, the solenoid valve 10 switches the ports P ₁ and P _2, makes the ports P ₄ and P ₅ conductive, and cuts off the supply of high-pressure oil from the pilot pressure oil line 8. When the piston 11 and the spring 12 of the logic valve 9 are moved to the solenoid valve 10 side, and during this time, the high pressure oil is returned from the ports P ₄ and P _{5 of the} solenoid valve 10 to the pressure oil tank (not shown) as a drain. high pressure oil in the oil cylinder 5 is returned to the pressure oil tank as a drain from the port P ₃ of the valve 9.

When the high pressure oil in the oil cylinder 5 is returned to the hydraulic oil tank through a port P ₃ of the logic valve 9, the steam valve moves the valve stem 3 downward, thereby closing the valve element 2 in the valve seat 2a soon.

  The trip circuit 13 for controlling the supply and discharge of the high-pressure oil with respect to the opening / closing operation of the steam valve has the logic shown in FIG.

  In the normal state when no abnormal situation has occurred, the trip circuit 13 turns on the contact 18 of the trip relay 16 and supplies the excitation current A from the DC (direct current) / DC (direct current) power source 17 to the solenoid 14 of the solenoid valve 10. Giving.

  However, when the conditions for closing the steam valve, such as overspeed of the steam turbine and occurrence of abnormal vibration, are met, the trip circuit 13 turns off the contact 18 of the trip relay 16, de-energizes the solenoid 14 of the solenoid valve 10, and electromagnetically Move the valve 10 to the trip position.

When the operation of the logic valve 9 and the electromagnetic valve 10 shown in FIG. 6 is made to correspond to the logic of such a trip circuit 13, when the solenoid 14 is de-energized, the electromagnetic valve 10 is turned into a spool (not shown). ₁₎ , and the port P ₄ , P ₅ is made conductive by the restoring force of the spring 15 instead of maintaining the conductive position of the ports P ₁ , P ₂ until now.

When the ports P ₄ and P ₅ are turned on, the solenoid valve 10 cuts off the supply of high-pressure oil from the pilot pressure oil line 8. At this time, since the logic valve 9 also cuts off the high-pressure oil supplied from the pilot pressure oil line 8 via the solenoid valve 10, the piston 11 is moved to the solenoid valve 10 side by the restoring force of the spring 15, and the oil cylinder The high pressure oil 5 is pulled out via the port P ₃ , and the pressing force to the piston 11 by the high pressure oil in the oil cylinder 5 is lost, and the valve rod 3 is lowered to close the valve body 2.

  In this way, the safety system 6 provided in the steam valve is designed to be fail-safe, and even if an unforeseen situation occurs, the safety system 6 is promptly dealt with to ensure safety.

For example, JP-A-7-145705 discloses an invention relating to fail-safe steam valves.
JP 7-145705 A

  A safety system used in a steam turbine operates only when an abnormal situation occurs, and further, a reliable signal transmission force is required for maintaining safety.

  However, the conventional steam valve security device shown in FIGS. 6 and 7 has the following problems.

  (1) In the conventional steam valve safety device, the safety system may be activated (referred to as an erroneous operation) due to some malfunction of the trip circuit and the hydraulic circuit, although no abnormal situation has occurred. (2) Despite the occurrence of an abnormal situation in the steam turbine, the safety system sometimes did not operate (referred to as malfunction / non-operation).

Table 1 summarizes the non-conformance events for each cause of malfunction and malfunction.

  In Table 1, events marked with x are events that are unlikely to occur. There is no need for improvement, but events marked with ○ or △ are likely to occur or have occurred. It is an event that has a low probability but is a possibility and an improvement plan is desired.

  First, from the viewpoint of fail-safe, since the valve body 2 is always in a pressurized state, the logic valve 9 may stick due to impurities inside the logic valve 9 and may malfunction or slow down. . This leads to a malfunction of the logic valve 9 or a delay in operation even when the electromagnetic valve 10 is operated. Similarly, from the viewpoint of fail-safe, the solenoid valve 10 has the same problem as the logic valve 19 because the solenoid 14 is always excited.

  On the other hand, both the logic valve 9 and the solenoid valve 10 are unlikely to malfunction due to oil pressure loss due to some factor, although oil leakage or the like can be assumed. Further, even if a trip is caused due to a malfunction, it is determined that the current state is acceptable because it becomes fail-safe from the viewpoint of protection of the steam turbine.

  Next, the solenoid 14 is always excited from the viewpoint of fail-safe, and is not excited when an abnormal event occurs. And since the solenoid 14 is always in the excited state during the operation of the steam turbine, the exciting current A flows. Therefore, there is a possibility of disconnection of the cable, disconnection of the coil due to heating, or a short circuit. Although it is a trip even if it occurs during driving, it is a fail-safe event that should be improved.

  In addition, even if an abnormal factor that makes it difficult to continue operation in the steam turbine due to seizure of the contact 18 of the trip relay 16 due to a long-time excitation state, the contact 19 of the trip relay 16 may not be opened, which is improved. Was needed.

  The present invention has been made based on such circumstances, and when an overspeed or abnormal vibration occurs in the steam turbine and it is difficult to continue operation, the steam valve is closed more quickly and reliably. It is an object of the present invention to provide a steam turbine safety device and a method for confirming whether or not the steam turbine is operating.

  In order to achieve the above object, a safety device for a steam turbine according to the present invention branches from an emergency oil line that supplies pressure oil to an oil cylinder that drives a steam valve, as described in claim 1, and again In the steam turbine safety device provided with a safety system in the pilot pressure oil line connected to the emergency oil line, the safety system is multiplexed with an electromagnetic valve and a logic valve, and an abnormal situation has occurred in the steam turbine. In some cases, a trip circuit is provided for energizing a solenoid provided in the electromagnetic valve to close the steam valve.

  In the steam turbine safety device according to the present invention, in order to achieve the above-described object, as described in claim 2, the multiplexed safety systems are configured in a parallel arrangement.

  Further, in order to achieve the above-mentioned object, the steam turbine safety device according to the present invention is multiplexed as described in claim 3, and the parallel-arranged safety systems connect the bypass pilot pressure oil lines to each other. Is provided on the outlet side of the solenoid valve.

  In order to achieve the above object, the steam turbine safety device according to the present invention includes a plurality of solenoids for one solenoid valve, as described in claim 4, and the plurality of solenoids. Exciting current is given through the trip relay of the trip circuit every time, while the DC / DC power source is connected to one of the trip relays and the AC / CD power source is connected to the other one. Is.

  In order to achieve the above object, the safety device for a steam turbine according to the present invention includes a current detector for detecting an exciting current and a detected actual exciting current value as described in claim 5. Compare the current indicator that displays one of the divided currents and the rest with a preset value. If the actual excitation current is lower than the set value, the excitation current is cut off and no excitation is displayed. Means.

  In order to achieve the above object, the safety device for a steam turbine according to the present invention is a test for testing the closing of the steam valve during the operation of the steam turbine as described in claim 6. A circuit is provided.

  Further, in order to achieve the above-described object, the steam turbine safety device according to the present invention includes a solenoid test relay that operates according to a command from a test logic, and a solenoid circuit for the test circuit. A trip relay is provided that excites a solenoid by applying an excitation current from either a DC / DC power supply or an AC / DC power supply in accordance with a test relay command.

  In addition, in order to achieve the above-described object, the method for confirming whether or not the safety device for a steam turbine according to the present invention is operated is a safety method for supplying and discharging pressure oil in an oil cylinder that drives a steam valve. When the system is multiplexed and the solenoid provided in the multiplexed safety system solenoid valve is operated, the actual excitation current value given from either the DC / DC power supply or the AC / DC power supply is displayed on the solenoid. In this method, the given actual exciting current value is compared with a predetermined set value, and when the given actual exciting current value is lower than the set value, it is confirmed that the solenoid is not operating.

  A steam turbine safety device and a method for confirming whether or not the steam turbine is operating according to the present invention includes a safety system comprising a trip valve, a solenoid valve, a logic valve, and the like as a steam valve for protecting the steam turbine when an abnormality occurs in the steam turbine. Are divided into multiple safety systems and multiplexed, and the reliability of fail-safe operation is further improved, so even if an abnormal situation occurs in the steam turbine, the steam valve can be made faster and more reliably. The steam turbine can be protected by closing the valve, and an unforeseen situation of the safety system can be detected earlier, and the steam turbine can be stably operated.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a steam turbine safety device and an operation confirmation method according to the present invention will be described below with reference to the drawings and reference numerals attached to the drawings.

  FIG. 1 and FIG. 2 are control system diagrams showing a first embodiment of a safety device for a steam turbine and a method for confirming whether or not the steam turbine is in accordance with the present invention. FIG. 1 is a pressure oil system diagram of a safety device for a steam turbine taking a steam valve as an example. FIG. 2 is a sequence circuit diagram of the safety device for the steam turbine shown in FIG.

  In the steam turbine safety device according to the present embodiment, for example, when the steam valve 20 such as the main steam stop valve is taken as an example, when an abnormal situation such as overspeed occurs in the steam turbine, the steam valve 20 is made faster and more reliably. A double safety system 21 composed of a first security system 21a and a second security system 21b to be closed is provided in parallel.

  The steam valve 20 includes a valve rod 26 having one end connected to a valve body 22 housed in the valve casing 20a and the other end connected to the piston 25 of the oil cylinder 24 via a spring 23, and the piston of the oil cylinder 24. An emergency oil line 27 for supplying high pressure oil to 25 is provided.

  The emergency oil line 27 includes a first pilot pressure oil line 28a and a second pilot pressure oil line 28b that divide the pilot pressure oil line 28 once from the middle and divide it back into two.

  The first safety system 21a includes a first electromagnetic valve 29a and a first logic valve 33a in order along the flow of high-pressure oil in the first pilot pressure oil line 28a. As with the first safety system 21a, the second solenoid valve 29b and the second logic valve 33b are provided, and the first pilot pressure oil line 28a branches from the outlet side of the first solenoid valve 29a, and the second pilot pressure oil line 28b It has a so-called double safety system configuration including a bypass pilot pressure oil line 30 connected to the outlet side of the second electromagnetic valve 29b.

Each of the first solenoid valve 29a and the second solenoid valve 29b includes a first solenoid valve first solenoid 31a ₁ , a first solenoid valve second solenoid 31a ₂ , and a second solenoid valve first solenoid 31b. ₁ and second solenoid valve second solenoid 31b ₂ are provided, and each solenoid 31a ₁ , 31a ₂ , 31b ₁ , 31b ₂ is connected to trip circuit 32.

  The first logic valve 33a accommodates the first logic valve piston 34a and the first logic spring 35a, while the second logic valve 33b is also connected to the second logic valve piston 34b and the second logic valve 33b in the same manner as described above. The logic valve spring 35b is accommodated so that when an abnormal situation occurs in the steam turbine, the high pressure oil in the oil cylinder 24 that drives the steam valve 20 is pulled out.

On the other hand, in the doubled safety system 21, the first solenoid valve first solenoid 31a ₁ provided in the first solenoid valve 29a, the first solenoid valve second solenoid 31a ₂ and the second solenoid valve 29b provided in the second solenoid valve 29b. The trip circuit 32 that gives the control signals a, b, c, d to the first solenoid valve solenoid 31b ₁ and the second solenoid valve second solenoid 31b ₂ has the configuration shown in FIG.

An abnormality occurrence signal that causes the steam valve 20 to become a closing command condition (trip condition) due to overspeed, abnormal vibration, or the like of the steam turbine is transmitted to the trip relays 36a ₁ , 36a ₂ , 36b ₁ via the OR circuit and NOT circuit of the trip circuit 32. , 36b ₂ . The first solenoid 31a ₁ for the first solenoid valve and the first solenoid 31b ₁ for the second solenoid valve are connected to the DC (direct current) / DC (direct current) power source via the contact points 37a ₁ and 37b ₁ of the trip relays 36a ₁ and 36b _1. 38, and the second solenoid 31a ₂ for the first solenoid valve and the second solenoid 31b ₂ for the second solenoid valve are connected to AC (alternating current) / DC (via the contact points 37a ₂ and 37b ₂ of the trip relays 36a ₂ and 36b _2. Each is connected to a DC power source 39.

FIGS. 1 and 2 both show that the steam turbine is in operation, and the first solenoid valves 31a ₁ and 31a ₂ provided in the first solenoid valve 29a and the second solenoid valves provided in the second solenoid valve 29b. Each of the solenoids 31b ₁ and 31b ₂ for use is excited and indicates the fully open state of the steam valve 20.

  Next, in the steam turbine safety device having the above-described configuration, an operation when an abnormality occurs during normal (normal) operation or when an abnormal situation occurs in one of the doubled safety systems will be described.

When the steam valve 20 has no closing command conditions (trip conditions) such as overspeed and abnormal vibration, the contacts 37a ₁ , 37a ₂ ,... Of the four trip relays 36a ₁ , 36a ₂ ,. Excitation currents from the AC / DC power supply 39 and the DC / DC power supply 38 are applied to the solenoids 31a ₁ and 31a ₂ for the first solenoid valve and the solenoids 31b ₁ and 31b ₂ for the second solenoid valve, and the solenoids 31a ₁ , 31a ₂ , 31b ₁ , 31b ₂ are all excited.

  At this time, as shown in FIG. 1, the first solenoid valve 29a and the second solenoid valve 29b conduct the port at the position shown in the figure against the restoring force of the springs 46a and 46b, and the first solenoid valve 29a and the second solenoid valve 29b High pressure oil is supplied to each of the first logic valve 33a and the second logic valve 33b of each of the first pilot pressure oil line 28a and the second pilot pressure oil line 28b, and the first and second in each logic valve 33a, 33b. The first and second logic valve pistons 34a and 34b are pressed against the restoring force of the logic valve springs 35a and 35b to close the port.

  At the same time, the high-pressure oil supplied from the emergency oil line 27 to the oil cylinder 24 presses the piston 25, pushes down the valve rod 26 against the restoring force of the spring 23, and opens the valve element 22.

When an abnormality occurs in the steam turbine during operation of the steam valve 20, the OR circuit of the trip circuit 32 shown in FIG. 2 is excited, and the contact points 37a ₁ , 36a ₁ , 36a ₂ ,... Of the trip relays 36a ₁ , 36a ₂ ,. 37a ₂ ,... Are turned off. When the contacts 37a ₁ , 37a ₂ ,... Are turned off, the exciting current to the _first solenoid valve solenoids 31a ₁ , 31a ₂ and the second solenoid valve solenoids 31b ₁ , 31b ₂ is cut off, and the first solenoid valve use The solenoids 31a ₁ and 31a ₂ and the second solenoid valve solenoids 31b ₁ and 31b ₂ are not excited.

When the solenoids 31a ₁ and 31a ₂ for the first solenoid valves and the solenoids 31b ₁ and 31b ₂ for the second solenoid valves are de-energized, the first solenoid valve 29a and the second solenoid valve 29b are restored to the springs 46a and 46b. The position of the port is moved by force, high pressure oil is drained and discharged to an oil tank (not shown), and the first logic valve 33a and the second pilot pressure oil line 28b are respectively discharged from the first pilot pressure oil line 28a and the second pilot pressure oil line 28b. The high pressure oil that has been supplied to the second logic valve 33b is cut off.

  At this time, the first logic valve 33a and the second logic valve 33b are connected to the first logic valve piston 34a and the second logic valve by the respective restoring forces of the first logic valve spring 35a and the second logic valve spring 35b. Each of the pistons 34b is moved, the high-pressure oil in the oil cylinder 24 is drawn out as a drain from the port, the valve rod 26 is lowered, and the steam valve 20 is closed.

  On the other hand, during the operation of the steam turbine, it is considered that an abnormal situation has occurred in the safety system 21 for some reason.

However, in the present embodiment, the safety system 21 is divided into a first security system 21a and a second security system 21b, so-called duplication is achieved, and the first and second electromagnetic valves 29a and 29b of the respective security systems 21a and 21b. The first solenoid valve solenoids 31a ₁ , 31a ₂ and the second solenoid valve solenoids 31b ₁ , 31b _{2 provided in} the respective solenoid valves are designed so that one individual solenoid can drive one solenoid valve separately. Therefore, even if one of the individual solenoids breaks down and loses the excitation force, no erroneous trip occurs.

  This is the same even if one of the DC / DC power supply 38 and the AC / DC power supply 39 is cut off.

Accordingly, any one of the first solenoid valve first solenoid 31a ₁ , the first solenoid valve second solenoid 31a ₂ , the second solenoid valve first solenoid 31b ₁ , and the second solenoid valve second solenoid 31b ₂ is selected. Even if the excitation current is interrupted due to disconnection or the like during operation of one solenoid, the solenoid valve can be driven only by the remaining one series of solenoids, and erroneous trips can be prevented. When the solenoids are doubled and the excitation current flowing through the two solenoids is interrupted together with both systems, the solenoid valve is de-energized, thereby preventing erroneous tripping.

As described above, in the present embodiment, the security system 21 is divided into the first security system 21a and the second security system 21b, and the first security system 21a and the second security system 21b that are arranged in parallel are first. The solenoid valve 29a, the first logic valve 33a, the second solenoid valve 29b, and the second logic valve 33b are provided to be doubled, and further the first solenoid valve first solenoid 3131a ₁ for driving the first solenoid valve 29a, the second Since the first solenoid valve second solenoid 31a ₂ and the second solenoid valve first solenoid 31b ₁ for driving the second solenoid valve 29b and the second solenoid valve second solenoid 31b ₂ are provided to be duplexed, Even if one of the individual solenoid valves and individual solenoids is unforeseen, when the trip command is issued, the steam valve is securely closed and the steam supply to the steam turbine is cut off to ensure the reliability of operation. The improved, lower increase reliability, it is possible to improve the rate of operation of the steam turbine.

In the present embodiment, the trip relays 36a ₁ , 36a ₂ ,... That shut off the first solenoid valves 31a ₁ , 31a ₂ and the second solenoid valves 31b ₁ , 31b ₂ are hard relays. Solid state relays or soft logic may be used. Furthermore, in the present embodiment, the security system 21 is duplexed, but multiplexing such as triple or quadruple can be easily realized.

  In the present embodiment, the security system 21 is divided into a first security system 21a and a second security system 21b, and the first solenoid valve 29a and the first logic circuit 33a of the first safety system 21a arranged in parallel are separated. Since the second electromagnetic valve 29b and the second logic circuit 33b of the second security system 21b are individually configured independently, for example, in the worst case, the first electromagnetic valve 29a and the first logic valve of the first security system 21a All failures of 33a are conceivable.

  However, this embodiment branches from the inlet side of the first logic valve 33a on the outlet side of the first electromagnetic valve 29a of the first safety system 21a, and on the outlet side of the second electromagnetic valve 29b of the second safety system 21b. Since the bypass pilot pressure oil line 30 connected to the inlet side of the second logic circuit 33b is provided, the steam valve 20 can be operated safely even if such a case occurs.

  3 to 5 are control logic diagrams showing a second embodiment of the safety device for a steam turbine and the operation confirmation method thereof according to the present invention.

  3 to 5, FIG. 3 is a sequence circuit diagram showing an exciting power monitoring circuit and a test circuit in the trip circuit 32 in the steam turbine safety device according to the present invention, and FIG. 4 is a diagram illustrating the present invention. FIG. 5 is an interlock block diagram showing a test operation in the trip circuit 32 of the steam turbine safety device according to the present invention, and FIG. 5 is a CRT display screen for performing the test operation of the steam turbine safety device according to the present invention. FIG.

  In the steam turbine safety device and the operation confirmation method according to the present invention, the safety system is at least duplexed more than the duplex, but FIGS. 3 to 5 show the first safety system among the multiplexed security systems. Only the description of the system is omitted, and descriptions of other security systems having the same configuration are omitted.

  In this case, the same components as those of the first embodiment are denoted by the same reference numerals.

The steam turbine safety device according to the present embodiment is one in which a first electromagnetic valve 29a is extracted from a plurality of electromagnetic valves as a representative example so that the malfunction prevention of the first electromagnetic valve 29a can be monitored. Along with the flow of the excitation current A given to the first solenoid 31a ₁ for valve and the second solenoid 31a ₂ for first solenoid valve, current detectors 47a ₁ , 47a ₂ , amplifiers 48a ₁ , 48a ₂ , comparators 49a ₁ , 49a ₂ , setting devices 50a ₁ and 50a ₂ , current indicators 51a ₁ and 51a ₂ are provided to monitor the constantly flowing excitation current value, and when an unexpected event such as disconnection or an abnormal event occurs, the excitation current A is It is configured to be able to monitor the interruption.

The detection signals from the current detectors 47a ₁ and 47a ₂ are divided into two detection signals via the amplifiers 48a ₁ and 48a ₂ , and one of them is output to the current indicators 51a ₁ and 51a ₂ . The other is input to the comparators 49a ₁ and 49a ₂ where it is compared with the setting from the setting devices 50a ₁ and 50a ₂ for detecting disconnection. The first solenoid 31a ₁ for the first solenoid valve 31a ₁ and the first solenoid 31a ₂ for the second solenoid valve 31 are configured to ensure non-excitation and excitation depending on the magnitudes of the outputs of the comparators 49a ₁ and 49a ₂ .

Further, the safety device for the steam turbine according to the present embodiment includes the first solenoid valve first solenoid 31a ₁ , the first solenoid valve second solenoid 31a ₂ and the trip relay that are always excited from the viewpoint of fail-safe. The test logic 52 and the solenoid test relays 53a ₁ and 53a ₂ for testing whether or not the 36a ₁ , 36a ₂ etc. should perform the trip operation surely when the original trip operation should be performed are duplicated to a system in which the excitation current A flows. Each is provided independently.

In addition, since the safety device of the steam turbine according to the present embodiment tests _two of the first solenoid valve first solenoid 31a ₁ and the first solenoid valve second solenoid 31a ₂ at the same time, it actually trips. Interlock is built in so that only one side series can be tested.

Then, if during the operation of the steam turbine, the disconnection circuit through which the excitation current A trip circuit 32 has occurred, if trip relay _36a 1, 36a contact _37a 1 of _2, 37a ₂ has caused a baking or test when performing, first a description will be given of the operation based on the configuration described above, during the operation of the steam turbine, the contact _37a 1, 37a ₂ trip relays _36a 1, 36a ₂ is turned oN, the first solenoid 31a for the first solenoid valve _1. Among the first solenoid valve second solenoids 31 a ₂ , the first solenoid valve first solenoid 31 a ₁ is supplied with the excitation current A from the DC / DC power supply 38, and the first solenoid valve second solenoid 31 a _2. An excitation current A is applied to 31a _{2 from} an AC / DC power source 39.

When the excitation current A is applied to the first solenoid valves 31a ₁ and 31a ₂ for the first solenoid valve, the detection signals from the current detectors 47a ₁ and 47a ₂ are split into two signals via the 48a ₁ and 48a ₂ amplifiers. Is done. One of them is displayed on the current indicators 51a ₁ and 51a ₂ .

The other is given to the comparators 49a ₁ and 49a ₂ , where the minimum current set value from the setters 51a ₁ and 51a ₂ is compared with the actual excitation current value, and when the set current falls below the set value, the excitation current As a shut-off, “first solenoid valve solenoid unexcited” is displayed on the CRT display 54 shown in FIG. 5 and an alarm is issued.

  In this embodiment, by providing such a circuit, when a disconnection occurs in the circuit of the solenoid valve that is always applying the excitation current A, it is easy to determine which circuit of which circuit has an accident. Can know.

  Next, the operation of the test circuit will be described.

In order to forcibly cut off the excitation current A applied to the first solenoid valve first solenoid 31a ₁ and the first solenoid valve second solenoid 31a ₂ shown in FIG. 3, the trip relays 36a ₁ , 36a _{2 are used.} When a command is given to the solenoid test relays 53a ₁ and 53a ₂ provided on the inlet side, the solenoid test relays 53a ₁ and 53a ₂ turn off the contacts, output a test signal, cut off the excitation current A, Each of the first solenoid valve first solenoid 31a ₁ and the first solenoid valve second solenoid 31a ₂ starts a test.

In this way, at the start of each test of the first solenoid valve first solenoid 31a ₁ and the first solenoid valve second solenoid 31a ₂ , the present embodiment, as shown in FIG. If two solenoids of the solenoid 31a ₁ and the second solenoid 31a ₂ for the first solenoid valve are tested at the same time, the steam turbine in operation is unnecessarily tripped. An interlock is built in which the first solenoid 31a ₁ for valve is left excited and the second solenoid 31a ₂ for first solenoid valve 31a ₂ is de-energized.

  In addition, during the test, the present embodiment switches the display of solenoid non-excitation, but incorporates an interlock that does not cause the excitation current alarm to be output to the solenoid under test.

As described above, in the present embodiment, the first solenoid valve first solenoid 31a ₁ and the first solenoid valve second solenoid 31a ₂ are provided in one solenoid valve, multiplexed, and multiplexed. Since each of the solenoids 31a ₁ and 31a ₂ is provided with an exciting current monitoring circuit and a test circuit, even if the steam turbine is in operation, the solenoid provided in each solenoid valve is operated normally without causing an unnecessary trip of the steam turbine. Abnormalities can be easily confirmed, and unforeseen situations such as burning of relay contacts can be easily detected during the test.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a first embodiment of a steam turbine safety device according to the present invention and a method for confirming whether or not the steam turbine is operating, and is a pressure oil system diagram of a steam turbine safety device illustrating a steam valve as an example. FIG. 2 is a sequence circuit diagram of the steam turbine safety device shown in FIG. 1. 2 shows a second embodiment of a steam turbine safety device and a method for confirming whether or not the steam turbine is operating according to the present invention, and is a sequence circuit showing an exciting current monitoring circuit and a test circuit in a trip circuit of an electromagnetic valve provided in an example steam valve Figure. The interlock block diagram which shows test operation in the trip circuit shown in FIG. The figure which shows the CRT display screen for performing the test operation shown in FIG. The pressure oil system figure of the safety device of the steam turbine which shows the safety device of the conventional steam turbine and exemplifies a steam valve. FIG. 7 is a sequence circuit diagram of the steam turbine safety device shown in FIG. 6.

Explanation of symbols

1 Valve casing 2 Valve body 2a Valve seat 3 Valve body 4 Spring 5 Oil cylinder 5a Piston 6 Safety system 7 Emergency oil line 8 Pilot pressure oil line 9 Logic valve 10 Solenoid valve 11 Piston 12 Spring 13 Trip circuit 14 Solenoid 15 Spring 16 Trip Relay 17 DC (direct current) / DC (direct current) power source 18 Contact 20 Steam valve 21 Safety system 21a First safety system 21b Second safety system 22 Valve body 23 Spring 24 Oil cylinder 25 Piston 26 Valve rod 27 Emergency oil line 28 Pilot pressure the oil line 28a first pilot pressure oil line 28b second pilot pressure oil line 29a first solenoid valve 29b first solenoid 31a ₂ first electromagnetic valve for the second solenoid valve 30 bypass pilot pressure oil line 31a ₁ first solenoid valve 2 solenoid 31b ₁ 2nd solenoid valve 1st solenoid 31b ₂ 2nd Second solenoid valve for solenoid valve 32 trip circuit 33a first logic circuit 33b second logic circuit 34a first logic valve piston 34b second logic valve piston 35a first logic valve spring 35b second logic valve spring 36a ₁ , 36a ₂ , 36b ₁ , 36b ₂ Trip relay 37a ₁ , 37a ₂ , 37b ₁ , 37b ₂ contact 38 DC (direct current) / DC (direct current) power source 39 AC (alternating current) / DC (direct current) power source 46a, 46b Spring 47a, 47b current detector 48a, 48b amplifiers 49a, 49b comparator 50a, 50b setter 51a, 51b current indicator 52 test logic _53a 1, 53a ₂ solenoid test relay

Claims (8)

In a steam turbine safety device that has a safety system in a pilot pressure oil line that branches off from an emergency oil line that supplies pressure oil to an oil cylinder that drives a steam valve and is connected to the emergency oil line again, the safety system includes: A solenoid circuit and a logic valve are provided and multiplexed, and a trip circuit is provided that closes the steam valve by exciting a solenoid provided in the solenoid valve when an abnormality occurs in the steam turbine. Steam turbine security device. 2. The steam turbine safety device according to claim 1, wherein the multiplexed safety systems are arranged in parallel. The steam turbine safety device according to claim 2, wherein the multiplexed and parallel safety system has a bypass pilot pressure oil line connected to each other on the outlet side of the solenoid valve. The solenoid valve has a plurality of solenoids for one solenoid, and an excitation current is given to each of the plurality of solenoids via a trip relay of a trip circuit. On the other hand, one of the trip relays has a DC / DC power source. The steam turbine safety device according to claim 1, wherein an AC / CD power source is connected to another unit. The solenoid compares the current detector that detects the excitation current, the current indicator that displays one of the detected actual excitation current values, and the remaining value with a predetermined set value. 5. The steam turbine safety device according to claim 1, further comprising means for interrupting the excitation current and displaying non-excitation when the excitation current is lower. 5. The steam turbine safety device according to claim 4, wherein the trip circuit includes a test circuit for testing the closing of the steam valve during operation of the steam turbine. The test circuit is a solenoid test relay that operates according to a command from the test logic, and a trip that energizes the solenoid by applying an excitation current from either the DC / DC power supply or the AC / DC power supply according to the command of the solenoid test relay. The steam turbine security device according to claim 6, further comprising a relay. When a safety system for supplying and discharging pressure oil in an oil cylinder that drives a steam valve is multiplexed and a solenoid provided in the multiplexed safety system solenoid valve is operated, the solenoid is supplied with a DC / DC power supply and an AC / DC power supply. When the actual excitation current value given from either of them is displayed and the given actual excitation current value is compared with a predetermined set value, and the given actual excitation current value is lower than the set value A method for confirming whether or not the steam turbine safety device is operating is characterized by confirming that the solenoid is not operating.

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