EP1630425A2 - Safety circuit for a fluid actuated user and method for using the same - Google Patents

Abstract

The protection circuit has solenoid valves (1.2, 1.3) interconnected to another solenoid valve (1.1). Control valves e.g. cartridge valves, (2.1, 2.2, 3.1, 3.2) are connected in parallel to each other such that a large flow rate is controlled with their simultaneous opening through the controlled solenoid valves. The valve (2.1) affects an actuation bearing (9), by simultaneous control of the solenoid valves (1.2, 1.3). An independent claim is also included for a procedure for an operation of a protection circuit.

Description

The invention relates to a safety circuit for media-driven consumers, such as steam or gas turbines, with at least one first solenoid valve, which acts on a fluid circuit, in particular hydraulic circuit to which an actuating device is connected, which acts on the operating behavior of the consumer. The invention further relates to a method for operating the safety circuit.

In conventional power plants, consumers such as steam or gas turbines are driven by live steam from the boiler via a guided through a steam line mass flow, the control of the mass steam flow via interposed turbine control valves. The usual nominal speed of a turbine to produce a 50 Hz frequency is 3000 U / min, whereby the speed is to be maintained within a narrow percentage range. The actual turbine control valves are preceded by so-called quick-acting valves as control valves, which can go under certain conditions or criteria in the so-called "rapid closure". A definable criterion is, for example, a clutch fracture on the turbine shaft, which usually has the consequence that the turbine tends toward Overspeed is running, which can lead to their destruction. In this looming case, a safety circuit is previously triggered in a very short time available, which shuts off the mass flow in front of the turbine concerned and thus protects the turbine from overspeed and concomitant damage.

In the known solutions, the so-called quick-closing valves are usually actuated hydraulically, wherein the use of an actuator, usually in the form of equipped with disc springs hydraulic cylinder (working cylinder) at Drucklos circuit thereof, under the action of the spring force the piston rod of the cylinder extends, while the Closes quick-acting valve as a control valve and the mass flow supply to the turbine stops before it can get into the damaging overspeed range.

In the known safety circuits, as they are used today in turbine power plants, the control of the working cylinder for the operation of the respective quick-closing valve of the turbine is realized with simple design solenoid valve concepts, which may be relatively easy to malfunction in the safety circuit, for example, if the actual Switching function of the solenoid valve is disturbed by contamination or the like. Uncertainties in the safety circuit itself, however, naturally lead to uncertain conditions in the obvious monitoring of the operating situation of the turbine, with the result that in case of failure by failure of the safety circuit, it comes in extreme cases to considerable damage to the turbine concerned.

Based on this prior art, the invention is based on the object, the known safety circuits and their operating methods to further improve that to a high degree the functional reliability is made for each consumer, the field of application of the safety circuit should not be limited to the turbine or power plant area. This object is achieved by a safety circuit having the features of patent claim 1 and an operating method having the features of patent claim 10.

Characterized in that according to the characterizing part of claim 1, at least one further solenoid valve is present, which is connected at least one of the other solenoid valves such that only with simultaneous activation of at least two solenoid valves at least one switched into the fluid circuit control valve on the actuator (lifting cylinder with disc spring package ), the possibility of the permanent verifiability of each individual essential component of the safety circuit, in particular in the form of the valves created, regardless of whether the mentioned power plant is in operation or is stationary. Even during operation of the plant, it is possible to always check a part of the valves and to ensure the safety function with the other components, in particular in the form of the further solenoid valves, so that this results in a high availability for the entire system. The solenoid valves used can be optimized to the particular safety application case, so that here very short switch-back times may result, even with the use of customary for these valves spring return for the valve piston.

With the safety circuit according to the invention, according to the feature configuration of claim 10, an operation is possible in which the individual solenoid valves can be checked for their functional reliability, for example, from a control room, in predeterminable time cycles, and always exclude at least two solenoid valves from a pending review, in order to ensure over this the redundant safety function for each consumer. In this way it is possible with the safety circuit to control a predeterminable oil volume flow in a very short time (60-80 ms) almost without pressure to the tank side of the fluid circuit in order to relieve the actuator of its control pressure, so that, for example, under the action of an energy storage as a diaphragm spring, the actuating device, preferably in the form of the spring-loaded lifting cylinder can cause the control of the quick-closing valve, in order to separate the consumer, preferably in the form of the steam or gas turbine from their media stream (steam). To realize the pertinent safety concept is preferably provided that the respective solenoid valves of the safety circuit in the manner of a series circuit are connected in such a fluid-conducting manner that always an output of a valve fluid leading connected to an input of another valve, wherein at least one input control line of the respective control valve is connected to the input side of at least one assignable solenoid valve.

Preferably, it is further provided that at least a part of the control valves are connected in parallel to each other so that when they are simultaneously opened by means of the controlled solenoid valves, a large volume flow is manageable. Preferably, so-called cartridge valves are used as control valves, which ensure a high reliability due to their structural design. These cartridge valves are also referred to in technical language with logic valves. Their structure and function is exemplary in volume 4 of the hydraulic trainer of Mannesmann Rexroth (edition 1989, print number RD 00280 / 01.89-1th edition).

Further advantageous embodiments of the safety circuit according to the invention are the subject of the other claims.

Fig. 1

ein erstes Ausführungsbeispiel mit drei Magnet- und einem Cartridge-Ventil,

Fig. 2 bis 8

ein zweites Ausführungsbeispiel der erfindungsgemäßen Sicherheitsschaltung in verschiedenen Schalt- und Betriebszuständen mit drei Magnet- und insgesamt vier Cartridge-Ventilen.

In the following, the safety circuit according to the invention is explained in more detail with reference to two embodiments according to the drawing. This show in principle and not to scale representation in the manner of schematics

Fig. 1

a first embodiment with three magnetic and one cartridge valve,

Fig. 2 to 8

A second embodiment of the safety circuit according to the invention in various switching and operating states with three magnetic and a total of four cartridge valves.

The basic structure of the safety circuit will first be explained in more detail in the first embodiment of FIG. The safety circuit according to the invention has three solenoid valves 1.1, 1.2 and 1.3. Furthermore, a single cartridge valve 2.1 is provided for the safety circuit according to FIG. At a tapping point DS, the system pressure can be recorded via an electrical pressure transducer 3. The cartridge valve 2.1 is spring-loaded and has a proximity or limit switch 5, in order to detect the switching position of the cartridge valve 2.1. Furthermore, the safety circuit is provided with a throttle 6 and a diaphragm 7. The pertinent aperture 7 leads to a filter unit 8, which in turn on the input side to a part of a fluid circuit 10 is connected. Further, an actuator 9 opens between the junction P and the throttle 7 in the fluid circuit 10th

All three solenoid valves 1.1, 1.2, 1.3 are shown in their closed position, ie in their de-energized position, in which the respective inputs and outputs of the solenoid valves as shown crosswise connected to each other fluidly. Furthermore, a respective output A1 of a solenoid valve 1.1, 1.2, 1.3 is connected to a respective input E1 of the series-connected solenoid valve. Furthermore, the respectively further input E2 is connected in a fluid-conducting manner to a supply line 12 of the fluid circuit 10. The other outputs A2 of the respective solenoid valve 1.1, 1.2, 1.3 are on the one hand fluidly connected to each other and the other fluid connected to the tank T of the fluid circuit 10 connected. An input side of the cartridge valve 2.1 opens in the direction of the connection point P in the fluid circuit 10 and the output side, as shown in FIG. 1, the cartridge valve 2.1 is also connected to the tank T.

In their energized further switching position, the respective solenoid valve 1.1, 1.2, 1.3 would connect the inputs E1 and E2 according to the circuit diagram representation and shut off the outputs A1, A2. The solenoid valves 1.1, 1.2, 1.3 are spring-loaded held in its closed position and the respective position of the solenoid valve is verifiable via encoder 14.

The actuator 9 consists of a hydraulic cylinder, the piston rod unit 16 is permanently spring loaded, preferably by exerting a compressive force on a plate spring 18. As shown in FIG. 1, the piston rod unit 16 against the pressure force of the plate spring 18 via the system pressure of the fluid circuit 10 seen in the direction of FIG. 1 in the raised position held and at a pressure drop at the pressure input point P1 for the actuator 9, the piston rod unit 16 moves down and actuates a control valve 20 which controls the media flow to the respective consumer (not shown), for example, the steam mass flow for driving a steam or Gas turbine (not shown) prevents.

The actual purpose of the safety circuit is to control a certain oil volume flow in a predetermined time (60 to 80 ms) as depressurized as possible to the tank T. The pressure difference .DELTA.p available for this purpose results inter alia from the characteristic of the spring assembly integrated in the actuating device 9 in the form of the disk springs 18. The disk springs 18 act in the closing direction, ie. H. the piston rod unit 16 extends, wherein the design system pressure in the safety circuit shown should be at least 7 to 8 bar, with fully tensioned plate spring 18. Depending on the component selection for the safety circuit quite system pressures up to 300 bar and more can be realized.

The individual components are designed and matched to one another such that the resulting end Δ p does not exceed 1.5 to 2 bar when the spring 18 is relaxed. This pressure is triggered even when triggered, ie currentless solenoid valves 1.1, 1.2 and 1.3, the criterion for a non-pressurized circulation, ie the specific oil through the aperture 7 volume is passed through the cartridge valve 2.1 to the tank T that the spring 18 in the hydraulic cylinder Actuator 9 is not tensioned. This happens only when at least two of the solenoid valves are connected to the positions 1.1, 1.2 or 1.3 energized.

According to the illustration according to FIG. 1, the aforementioned solenoid valves 1.1, 1.2 and 1.3 are shown de-energized and are monitored for their piston switching position. In order to be able to ensure a permanent testability of the components, the solenoid valves 1.1, 1.2 and 1.3 are provided with the encoders 14, in particular in the form of inductive proximity switches. The pertinent proximity switches can be used either as normally closed or as normally open.

In the starting situation, first all the solenoid valves 1.1, 1.2 and 1.3 are energized, d. H. All control channels related to the outputs A2 are blocked to the tank T.

During normal operation of the safety circuit is then always alternately a solenoid valve 1.1 or 1.2 or 1.3 under review. The pressure-conducting control bores of both the cartridge valve 2.1 and the solenoid valves 1.1, 1.2 and 1.3 are not depressurized on the input side. This means that the closing surface of the cartridge valve 2.1 is kept under system pressure and therefore remains closed. When triggered - de-energized - two or three solenoid valves of positions 1.1, 1.2 and 1.3, the system is completely depressurized. It is irrelevant which solenoid valves are de-energized, if only two of them are de-energized. The electroless circuit of two solenoid valves has the consequence that the cartridge valve 2.1 is relieved on the closing surface and opens in no time. The common oil flow, which results both from the closing operation of the hydraulic cylinder 9 and from the fluid flow coming from the orifice 7, is then against said differential pressure of about <1.5 to 2 bar from the input side port of the cartridge valve 2.1 in the direction of the output side port against the atmospheric pressure in the tank T passed.

The limit switch 5, which may also be in the form of a pressure transducer (not shown), then signals the current valve position (open) of the cartridge valve 2.1 to a central office (control room or the like) on, which allows the inference that successfully a Sturgeon situation at the consumer (turbine) could be eliminated via the control valve 20 by closing the same. The pressure transducer 3 monitors the pressure in the system in addition to the position monitoring of the valve initiators in the form of the encoder 14. The safety circuit shown is basically designed as a closed circuit current; but there are also applications conceivable, especially in other technical areas, where a triggering of the safety function by energizing the solenoid valves 1.1, 1.2 and 1.3 takes place. Monitoring the system pressure as indicated also allows for permanent electronic monitoring as an additional safety criterion. In addition, the use of cartridge valves within the safety circuit has achieved increased functional reliability.
The possible modes of operation of the safety circuit will be described below with reference to a second embodiment of FIGS. 2 to 8 in more detail. If components of the first embodiment are used in the second embodiment, the same reference numerals are used insofar as the previous versions apply to the new second embodiment. For ease of illustration was shown in Figs. 2 to 8 of the working cylinder 9 only with its connection point.

The main difference with respect to the first solution described above is that in the second embodiment, instead of just one cartridge valve 2.1, a further corresponding second cartridge valve 2.2 is used. Furthermore, the two cartridge valves 2.1 and 2.2 connected on its output side fluid leading together and connected to the tank T. On the input side, the two cartridge valves 2.1 and 2.2 are each fluid-carryingly connected to the outlet of two further cartridge valves 3.1 and 3.2, which have two control inputs X and Y as so-called active cartridge valves. Furthermore, the two input sides of each cartridge valve 3.1 and 3.2 are connected to the supply line 12 of the fluid circuit 10. In a connecting line 22 between the two input lines of the cartridge valves 2.1 and 2.2, another throttle or aperture 4 is connected.

The control port X of the cartridge valve 3.1 opens together with the control port Y of the cartridge valve 3.2 in the connecting line between the output A1 and input E1 of solenoid valve 1.3 or 1.2. Furthermore, the control port X of the cartridge valve 3.2 opens together with the control port Y of the cartridge valve 3.1 in the connecting line between the output A1 and input E1 of solenoid valve 1.2 or solenoid valve 1.1.

• 1. Prüfung 1 x Ruhestrom betreffend Position 1.1 führt zum Öffnen von Ventilpositionen 2.2 und Position 3.1 gemäß Darstellung nach der Fig. 2
• 2. Prüfung 1 x Ruhestrom betreffend Position 1.2 ergibt Öffnen der Ventilpositionen 2.1 und Position 3.2 gemäß Fig. 3
• 3. Prüfung 1 x Ruhestrom betreffend Position 1.3 ergibt Schließen aller Logikventile 2.1, 2.2, 3.1, 3.2 (nicht dargestellt)
• 4. Prüfung 2x Ruhestrom betreffend Position 1.1 und Position 1.2 ergibt Öffnen aller Logikventile gemäß Darstellung nach der Fig. 4
• 5. Prüfung 2x Ruhestrom betreffend Position 1.1 und Position 1.3 ergibt Öffnen aller Logikventile 2.1, 2.2, 3.1, 3.3 gemäß Darstellung nach der Fig. 5
• 6. Prüfung 2x Ruhestrom betreffend Position 1.2 und Position 1.3 ergibt Öffnen aller Logikventile 2.1, 2.2, 3.1, 3.2 gemäß Darstellung nach der Fig. 6
• 7. Prüfung 3x Ruhestrom betreffend Position 1.1, Position 1.2 und Position 1.3 ergibt Öffnen aller Logikventile gemäß Darstellung nach der Fig. 7
• 8. Prüfung 3x Arbeitsstrom betreffend Position 1.1, Position 1.2 und Position 1.3 ergibt Schließen aller Logikventile gemäß Darstellung nach der Fig. 8

Due to the parallel connection of all logic valves 2.1, 2.2, 3.1 and 3.2 with the possibility of their simultaneous opening a large volume flow can be passed without pressure to the tank T in no time. This is an advantage over a solution according to FIG. 1 with only one inserted cartridge valve 2.1. The position of the cartridge valves 2.1 and 2.2 is in turn realized via limit switches 5.1 and 5.2 and a control port of the cartridge valve 2.1 is connected to the control port X of the cartridge valve 3.1 and to the control port Y of the cartridge valve 3.2. Furthermore, according to a control terminal of the cartridge valve 2.2 to the respective control line X and Y of the cartridge valves 3.2 and 3.1 connected. The functionality of all used Valves are monitored and reported by contact with the respective associated electrical transmitters, inter alia. The permanent checks of the individual function modules and assemblies result in the following relationships in the valve assignments and functions:

• 1. Test 1 x quiescent current position 1.1 leads to the opening of valve positions 2.2 and 3.1 position as shown in FIG. 2
• 2. Test 1 x quiescent current with respect to position 1.2 results in opening the valve positions 2.1 and 3.2 according to FIG. 3
• 3. Test 1 x quiescent current regarding position 1.3 results in closing of all logic valves 2.1, 2.2, 3.1, 3.2 (not shown)
• 4. Check 2x quiescent current position 1.1 and 1.2 results in opening all logic valves as shown in FIG. 4th
• 5. Check 2x quiescent current position 1.1 and 1.3 results in opening all logic valves 2.1, 2.2, 3.1, 3.3 as shown in FIG. 5
• 6. Check twice quiescent current position 1.2 and 1.3 results in opening all logic valves 2.1, 2.2, 3.1, 3.2 as shown in FIG. 6th
• 7. Test 3x quiescent current concerning position 1.1, position 1.2 and position 1.3 results in opening of all logic valves as shown in FIG. 7
• 8. Check 3x working current regarding position 1.1, position 1.2 and position 1.3 results in closing of all logic valves as shown in FIG. 8

With the security solution according to the invention, there is a permanent possibility of verifiability of each operable individual component in the manner of a 2/3-safety control, whereby at the same time the non-tested system components can realize the safety function.

In a preferred embodiment, the pressure transducer 3 according to the illustration of Figure 2 opposite to the pertinent representation on both sides of the aperture 4 is connected below the cartridge valves 2.1 and 2.2 in the fluid circuit 10.

Claims (10)

Safety circuit for media-operated consumers, such as steam or gas turbines, with at least one first solenoid valve (1.1) acting on a fluid circuit (10), in particular hydraulic circuit to which an actuator (9) is connected, which acts on the performance of the consumer , characterized in that at least one further solenoid valve (1.2, 1.3) is present, which is at least connected to one of the other solenoid valves (1.1) such that at least one of the at least two solenoid valves (1.1, 1.2, 1.3) at least one of the Fluid circuit (10) switched control valve (2.1) acts on the actuating device (9). Safety circuit according to claim 1, characterized in that the respective solenoid valves (1.1, 1.2, 1.3) in the manner of a series circuit are fluidly connected to each other such that always an output (A) of the one valve fluid leading to an input (E) of another valve is connected and that at least one input control line of the respective control valve (2.1) is connected to the input side (E) of at least one assignable solenoid valve. Safety circuit according to claim 1 or 2, characterized in that at least a part of the control valves (2.1, 2.2, 3.1, 3.2) are connected in parallel to each other such that their simultaneous opening by means of the controlled solenoid valves (1.1, 1.2, 1.3), a large volume flow is controllable. Safety circuit according to one of claims 1 to 3, characterized in that the magnetic and the control valves each have a fluid connection point leading to the tank (T) of the fluid circuit (10). Safety circuit according to one of claims 1 to 4, characterized in that in a supply line (12) from the actuating device (9) and / or from the fluid circuit (10) coming to the respective solenoid valve (1.1, 1.2, 1.3) at least one throttle and / or aperture (4, 6, 7) is connected. Safety circuit according to one of claims 1 to 5, characterized in that the reliability of all solenoid valves (1.1, 1.2, 1.3) by electrical encoder (14) is verifiable. Safety circuit according to claim 6, characterized in that all the solenoid valves (1.1, 1.2, 1.3) constructed the same and switch on voltage drop at the respective assignable encoder (14) to trigger the safety function. Safety circuit according to one of claims 1 to 7, characterized in that the respective solenoid valve (1.1, 1.2, 1.3) is a 4/2-way valve and that the respective control valve is a cartridge valve (2.1, 2.2) - also in active construction ( 3.1, 3.2) - is. Safety circuit according to one of claims 1 to 8, characterized in that the actuating device (9) consists of a spring-loaded working cylinder, which actuates a control valve (20) which controls the media flow to the respective consumer. Method for operating a safety circuit according to one of claims 1 to 9, characterized in that in predetermined cycles, the individual solenoid valves (1.1, 1.2, 1.3) are checked for their reliability and that at least two solenoid valves, except for a pending review, the Ensure safety function for the respective consumer.

Images