DE2629205C3 - Pressure rise rate limiter for pipelines - Google Patents

Description

fc | The invention relates to a pressure increase speed

H digkeits limiter for Druckanstiegsgeschwindigkeits-

limitation in pipelines in the event of pressure surge or water hammer according to the preamble of claim 1.

Pressure surges that z. B. when switching off Pumping stations are one of the main causes of pipe ruptures that cause considerable damage.

To protect long pipelines from destruction, various devices are used to flatten the shock wave front.
ίο The widest application has found safety valves of various types, which correspond to a rise in pressure in the pipeline and cause liquid to drain into a collecting container.

It is also possible to use safety spring valves that are arranged on a branch pipeline and directly respond to the force of the shock wave.

A safety spring valve includes a housing with a drain port and one housed in the housing Piston with a spring. When the piston is moved, the drain opening opens in the housing, and the pipeline comes into connection with the drain line via the drain opening.

In the event of a pressure surge, the valve opens quickly enough to allow the working fluid to drain into one to ensure pressureless container. The response limit of the valves is determined by changing the spring pressure force set.

The investigation of the behavior of the safety spring valves has shown that they do not work sufficiently safely μ. One of the main causes of its unsafe Its function is its inertia and the change in the response pressure due to the lack of constancy of the elastic properties of the spring.

A known limiter which can be used for flattening the shock wave in pipelines has a Valve and a compressed air control unit, the exchangeable throttles and a gradient regulator, which is connected in series to the valve contains. The valve is opened by a signal from Compressed air control unit. The signal is generated in accordance with the rate of pressure increase in the Pipeline formed. The rate of pressure increase is controlled by one of the exchangeable throttles certainly.

The gradient controller speaks in the event of a deviation between the nominal pressure increase speed and the actual pressure increase speed in the pipeline.

When the valve is opened, the working fluid is drained into the collecting container, whereby the Flattening of the shock wave front is achieved.

One disadvantage of this limiter is a minor one

Operational safety of the valve, since it does not close sufficiently tightly, so that liquid losses through the Valve occur, which leads to significant losses of working fluid.

In addition, the circuit of the compressed air control unit is very complicated, what its operation difficult.

Another known limiter has a valve which is built into the pipeline and one with control unit connected to this valve, which is connected in series with an electronic regulator of the rate of pressure increase, contains a hydraulic follow-up system, a compressed air tank and throttles, the Compressed air tank and the throttles serve as a delay element.

The said valve is a perforated cylinder on which a rubber sleeve is placed. Of the

The cavity behind the cylinder is connected to the pipeline, which means that the operating condition is stationary acting on the interior of the rubber sleeve Pressure is compensated by the pressure acting on the outer walls.

At the time of the pressure surge, de / pressure in the cavities of the valve is caused by the delay element balanced after a time interval. During this time interval, the cuff is off the cylinder pressed and the pipeline is connected to the collecting tank.

As a result, liquid flows out of the valve into the sump in the event of a pressure surge, whereby the Flattening of the shock wave takes place

Disadvantages of this limiter are the low operational reliability of the rubber sleeve in the valve, their rapid wear and the need, depending on the wear, the compressed air tank and the throttles set again. In addition, the operation of the control unit is too complicated

It is also a pressure rise rate limiter for limiting the rate of pressure increase in pipelines in the event of pressure surge or water hammer a jet valve arranged directly in the pipeline known which has an inlet, an outlet and contains an additional outlet connected to an unpressurized drainage container via an actuator a pressure increase rate signal transmitter and with a pressure transmitter whose output with the The input of the rate of pressure transducer is connected.

This limiter works like this:

At a low rate of pressure change in the pipeline, which is the stationary Corresponds to the operating state of the pipeline, the flow of the working fluid flows through the jet valve into the Pipeline.

When exceeding a specified speed the pressure increase signal transmitter speaks of the pressure change in the pipeline, which occurs in the event of a pressure surge at. A signal is sent to the control inlet of the jet valve, which signals the deflection of the working fluid flow via the Ejects jet valve in the collecting container. This leads to a decrease in the rate of pressure rise.

If the pressure increase speed specified in the signal generator is reached, a signal is generated which arrives at the control inlet of the jet valve, which redirects the working fluid flow back into the pipeline causes.

However, a disadvantage of this limiter for protecting the pipeline against a pressure surge is Considerable energy losses in the jet valve, since it is necessary in this the potential energy of the Convert working fluid into kinetic energy and vice versa.

In addition, when there are vibrations in the pipeline, a large amount of working fluid is drained off the pipeline, which disrupts the operating condition in the pipeline. This will make the functional Possibilities of ano dniuig limited.

The invention is based on the object of a pressure increase speed limiter for limiting the pressure increase speed to create the functional possibilities in pipelines in the event of a pressure surge, which enables hydraulic energy losses to be reduced of the limiter and to ensure a safe flattening of the pressure wave front.

This task is performed by a pressure rise rate limiter for limiting the rate of pressure rise in pipelines in the event of a surge or water hammer, with a directly in the Pipeline arranged jet valve, which has an inlet, an outlet and an additional, with a unpressurized drain container containing an actuator connected outlet, with a pressure rise rate signal transmitter and with a pressure transmitter, the output of which is connected to the input of the pressure increase rate signal transmitter is connected, solved according to the invention by a gas-tight compressed air equalizer, the is connected to the additional outlet of the jet valve and to reduce the rate of pressure rise in the pipeline as a result of working fluid lift in the compressed air equalizer in the event of a pressure surge and Contraction of the air cushion is provided above the level of the working fluid in this, the Compressed air equalizer connected to the pressure increase rate signal transmitter via the pressure transmitter whose output is connected to a diaphragm drive of the actuator

It is useful that the jet valve consists of a nozzle, a diffuser coaxial with it and a There is an intermediate nozzle chamber which is directly connected to the additional outlet of the jet valve.

The invention is advantageously developed by a logic unit and a level transmitter for the Working fluid level in the compressed air equalizer, of which two outputs are connected to the compressed air equalizer and a third output is connected to an input of the logic unit via a position controller, one of which is second input with the output of the pressure increase rate signal transmitter and a third input Connected via a further position controller to a further pressure transducer arranged on the pipeline the compressed air equalizer is connected to an air supply line via a further actuator, of which a membrane drive is connected to the output of the logic unit.

It is also advisable that in the case of a pressure increase rate limiter, wherein the rate of pressure rise transducer is sounded in series an element for initial adjustment of the signal generator, a control signal generator and a comparator contains, the pressure increase rate signal transmitter has a delay element, the one for Comparator tank connected in parallel and one connected to the outlet of the tank connected to the atmosphere Comparator connected change choke possesses.

The use of the gas-tight compressed air equalizer with the logic unit and connections of the The jet valve with the compressed air equalizer and the drain line enable, in steady-state operating conditions a conversion of the entire potential energy of the working fluid flow into kinetic ones To avoid energy, namely thanks to the existing pressure in the intermediate nozzle chamber.

Only part of the potential energy of the working fluid flow is in the flow valve the kinetic energy converted by the difference in the speed of the working fluid flow in the pipeline and that of the working fluid sirome is determined in the intermediate nozzle chamber of the jet valve. This causes energy losses considerably reduced. The connections of the signal transmitter with the actuator and the compressed air equalizer enable an effective reduction in pressure surges

the rate of pressure increase in the pipeline and an operational adjustment of all blocks of the limiter according to the invention. This allows expand the functionality of the limiter and make it universal.

In the following the invention is exemplified explained in more detail with reference to the drawing. It shows

F i g. 1 is a basic circuit diagram of the pressure rise rate limiter to limit the rate of pressure increase in pipelines in the event of pressure surge or water hammer;

F i g. 2 a jet valve;

F i g. 3 is a pneumatic circuit diagram of the rate of pressure rise signal generator.

The pressure rise rate limiter has a jet valve 1 (Fig. 1), which is directly in a Pipeline 2 of the suction line of a pumping station 3 is arranged. The jet valve 1 has an inlet, an outlet and an additional outlet, which is connected to an unpressurized drain container 4 via an actuator 5 communicates.

The limiter has a gas-tight compressed air equalizer 6, which is connected to the additional outlet of the Jet valve 1 is connected. The limiter also has a rate of pressure rise signal transmitter 7 and a pressure transmitter 8, the output of which is connected to the input of the signal transmitter 7.

The gas-tight compressed air equalizer 6 is connected to the pressure increase speed signal transmitter via the pressure transmitter 8 7, the output of which is connected to the diaphragm drive 9 of the actuator 5.

The limiter also has a logic unit 10, consisting of an OR gate 11 and a Inhibition element 12 and a level sensor 13 for the liquid level in the gas-tight compressed air equalizer 6 on. Two outputs of the level transmitter 13 are connected to the gas-tight compressed air equalizer 6, a third output is connected to an input of the logic unit 10 via a position controller 14, the second input of which is connected to the output of the pressure increase speed signal generator 7 and its third input via a Position controller 15 are connected to a further pressure transducer 16 arranged in pipeline 2.

The gas-tight compressed air equalizer 6 is connected to an air supply line 17 via a further actuator 18 Connection, the membrane drive 19 of which is connected to an output of the logic unit 10

The jet valve 1 (FIG. 2) consists of a nozzle 20 and a diffuser 21, which are arranged coaxially to one another, and an intermediate nozzle chamber 22, which is directly connected to the gas-tight thin air equalizer 6.

The pressure increase rate signal generator 7 contains the following elements connected in series: on Element 23 (FIG. 3) for initial adjustment of the signal generator, a control signal generator 24 and a comparator.

The element 23 is coordinated in such a way that when the operating state of the pipeline has become stationary 2 a control signal to the output of the control signal generator 24 is passed.

The signal generator 7 also has a delay element 26 for delaying the triggering of the output signal on.

The element 23 for initial adjustment of the signal generator 7 represents a signal repeater with a shift (cf. T. K. Berends, T. K. Efremowa, A. A. Tagajewskaja, "Components and circuits of the automatic compressed air system", Verlag Maschinostrojenije, Moscow, 1968).

The control signal generator 24 contains an alternating throttle 27, a container 28, a comparison element 29, a container 30 with all of these elements in a row are switched. The control signal generator 24 also has a repeater 31 with displacement, which is switched on in parallel to element 29.

The comparator 25 includes a comparison element 32 and a power repeater amplifier 33 shown in FIG

ίο are connected in series.

A delay element 26 connects a container 34 connected in parallel to the comparator 25 and one the output of the comparator 25 connected to the atmosphere 35 a. The supply of the signal generator 7 is shown in FIG. 3 not shown.

The operation of the pressure increase rate limiter to limit the pressure increase rate in pipelines with pressure surge is the following:

In the steady operating state of the pipeline 2 (FIG. 1), the jet valve 1 and the compressed air equalizer 6 are in dynamic equilibrium.
The working fluid in the pipeline 2 flows from the nozzle 20 (FIG. 2) into the intermediate nozzle chamber 22 in the diffuser 21.

With smaller pressure fluctuations in the pipeline 2, working fluid flows through the intermediate nozzle chamber 22 in the compressed air equalizer 6 (Fig. 1) as a result of a difference between the air cushion pressure in Compressed air equalizer 6 and the pressure in the pipe 2, thereby flattening the pressure fluctuations the working fluid in the pipeline takes place, which leads to a steady operating state of the pipeline 2.

When the pumping station 3 is switched off, a wave of the pressure increase spreads upstream in the pipeline 2 the working fluid. This occurs when the shaft passes through the flow valve 1 Outflow of working fluid via the intermediate nozzle chamber 22 (Fig. 2) of the jet valve 1 (Fig. 1) in the compressed air equalizer 6. As a result, there is a reduction in the rate of pressure rise of the Working fluid instead. Since the volume of the compressed air equalizer 6 is limited, it takes place in the pipeline 2 in the event of major disturbances in the pressure of the working fluid, the fluid is drained into the pressureless container 4 via the actuator 5.

The suppression of dangerous disturbances of the

so the pressure of the working fluid in the pipeline takes place by means of the signal generator 7 via a with the Compressed air equalizer 6 related pressure transducer 8.

The magnitude of the shock wave at which the rate of pressure increase transducer 7 responds is determined by the operating state of the pipeline 2. If the amplitude of the pressure increase exceeds the Working fluid gives the value given to the signal transmitter 7 in a given time interval The signal generator 7 emits a signal which reaches the logic unit 10 and at the same time to the actuator 5. The actuator 5 opens and drains liquid into container 4. The operation of the logic unit 10 is as follows to be discribed.

When using the limiter, a loss of air from the compressed air equalizer 6 can be observed. A regular air supply to the compressed air equalizer 6 takes place automatically. The mirror of the work flow

fluidity in the compressed air equalizer 6 is monitored by the level sensor 13, which is controlled by the position controller 14 is associated with the dead zone to be coordinated. A significant reduction in the volume of air in the compressed air equalizer 6 is controlled by the level transmitter

13 detected If the signal coming from the level sensor 13 to the position controller 14 exceeds the dem Position controller 14 predetermined pressure value, the position controller 14 sends a signal to the logic unit 19. From the logic unit 10 receives a corresponding signal to the actuator 18, which opens and via which the Compressed air equalizer 6 is filled with air until the level of the working fluid in the compressed air equalizer 6 drops to the pressure value specified by the position regulator 14.

When the pressure value specified for the position controller 14 is reached, its output signal is equal to zero, and the actuator 18 closes. The air pressure for the air supply of the compressed air equalizer 6 should be the Exceed the maximum working pressure in pipe 2.

To avoid the transfer of working fluid into the air feed line of the compressed air equalizer 6 and to prevent incorrect response of the feed system in the event of a change in the liquid level in the compressed air equalizer 6 in the event of a pressure surge Limiter a device for locking the opening of the further actuator 18 is provided. the Locking is effected by the logic unit 10, which by means of the OR element 11 and the inhibition element 12 the passage of the signal from the position controller

14 blocks in the event of a pressure increase in the transitional or steady-state operating state of the pipeline 2. For this purpose, on the control input of the inhibition element 12 via the OR element 11 of the Outputs of the signal generator 7 of the speed and of the position controller 15, which is connected to the one in the pipeline 2 arranged pressure transducer 16 is connected, signals are given.

The pressure transducer 16 detects the pressure in the pipe 2 and sends a corresponding signal to the position controller 15, in which the pressure of the working fluid in the pipe 2 with one of the Position controller 15 predetermined or setpoint pressure value is compared.

The pressure given to the position controller 15 exceeds the operating pressure in the pipeline 2 when it is stationary become operating condition.

When the pressure value of the working fluid specified for the position controller 15 is exceeded, a signal is generated transferred to the OR gate 11 of the logic unit 10.

Furthermore, the signal reaches the actuator 18 via the inhibition element 12 of the logic unit 10 Actuator 18 closes under the influence of this signal and prevents the access of air to the Compressed air equalizer 6.

The mode of operation of the signal generator 7 is explained in more detail below

The signal from the pressure transmitter 8 comes to the input of the signal transmitter 7. The output signal of the Signal generator 7 is the OR gate 11 of the logic unit 10 and the diaphragm drive 9 of the Actuator 5 supplied

When the operating state of the pipeline 2 has become stationary, the pulsation of the working fluid pressure is present in the pipe 2, the air pressure in the compressed air equalizer 6 and, accordingly, the pulsation the input signal value of the signal generator 7 within the limits of the permissible pressure levels and the values of the Changes in the printing speed of the working fluid. The air pressure at the outlet corresponds to the Control signal generator 24 (F i g. 3) the input pressure of the signal generator 7, the latter by one exceeds the predetermined value which is set by the repeater 31.

The adjustment of the element 31 ensures the filtering out of high-frequency changes in the working fluid pressure in the pipe 2 and in the air cushion of the compressed air equalizer 6, which after their characteristic values for pipe 2 are not dangerous.

Furthermore, in the element 32 of the comparator 25, the input signal of the signal generator 7 with the Output signal of the control signal generator 24 compared.

The element 32 responds, and at its output and correspondingly at the output of the signal generator 7 an output signal is formed equal to zero. The output signal of the signal generator 7 influences the with This connected components of the limiter not, the actuators 5 (Fig. 1) and 18 so remain closed. As a result, there is no discharge of the working fluid into the pressureless container 4 and no air supply of the compressed air equalizer 6.

In the event of a very brief change in the working fluid pressure In the pipeline 2, part of the working fluid flows through the flow valve 1 into the Compressed air equalizer 6, so that there is a steep increase in pressure in the air cushion of the compressed air equalizer 6.

This pressure change in the air cushion is detected by the pressure transducer, from whose output a corresponding one Signal is transmitted to the input of the signal generator 7. Exceeds the named pressure change the value given by element 23 (FIG. 3), the comparison element 29 of the speaks Control signal generator 24 and the air pressure remains at the output of the control signal generator 24 during of a time interval which is predetermined by the alternating throttle 27 and the container 28. The output signal of the element 32 of the comparator 25 and, accordingly, the output signal remain of the signal generator 7 is zero.

If the pressure change in pipe 2 and the air cushion pressure are significant and persistent, the element 32 of the comparator 25 responds, and at the output of the element 32 and correspondingly on The output of the signal generator 7 produces an output signal equal to "one".

A significant change in pressure is understood to mean a change in pressure which exceeds the pressure level specified by element 31
The output signal equal to one of the signal generator 7 acts on the diaphragm drive 9 (FIG. 1) of the actuator 5, whereby the latter is opened. As a result, working fluid is drained from the pipeline 2 via the actuator 5 into the unpressurized container 4, and the pressure in the pipeline 2 is reduced to the pressure value in the steady operating state of the pipeline 2

In addition, the output signal of the signal generator 7 acts equal to one via the OR element 11 of the logic unit 10 on the diaphragm drive 19 of the actuator 18, so that the latter is closed. As a result, there is no air supply to the compressed air equalizer 6.
The delay element 26 is for changing the

Transition speed of the output signal of the signal generator 7 provided from one to zero. This is necessary in order to delay the closing of the actuator 5, since a sudden closing of the actuator 5 leads to an additional pressure surge.
The use of the limiter enables the

10

Reliability of the protection of pipelines against pipe rupture in the event of pressure surges or water hammers with minimal pressure losses in the pipeline during the steady-state operating condition of the pipeline to increase.

For this purpose 3 sheets of drawings

Claims (4)

Patent claims: 1. Pressure increase speed limiter for limiting the pressure increase speed in pipelines in the event of a pressure surge or water hammer, with a jet valve arranged directly in the pipeline, which contains an inlet, an outlet and an additional outlet connected to a pressureless drainage container via an actuator, with a pressure increase speed signal transmitter and with a pressure transmitter, the output of which is connected to the input of the pressure increase rate signal transmitter, characterized by a gas-tight compressed air equalizer (6) which is connected to the additional outlet of the jet valve (1) and for reducing the pressure increase rate in the pipeline (2) as a result Working fluid lift in the compressed air equalizer (6) in the event of a pressure surge and contraction of the air cushion above the level of the working fluid in this is provided, the compressed air equalizer (6) via the pressure transmitter (8) with the pressure increase speed signal Via (7) is connected, the output of which is connected to a diaphragm drive (9) of the actuator (5) (Fig. 1). 2. Pressure rise rate limiter according to claim 1, characterized in that the Jet valve (1) consisting of a nozzle (20), a diffuser (21) coaxial with it and an intermediate nozzle chamber (22), which is directly connected to the additional outlet of the jet valve (1) is (Fig. 2). 3. Pressure rise speed limiter according to claim 1 or 2, characterized by a Logic unit (10) and a level sensor (t3) for the working fluid level in the compressed air equalizer (6), of which two outputs with the compressed air equalizer (6) and a third output via one Position controller (14) are connected to an input of the logic unit (10), of which a second input the output of the pressure increase speed signal generator (7) and a third input via a further position controller (15) with a further pressure transmitter (16) arranged on the pipe (2) is connected, the compressed air equalizer (6) to an air supply line (17) via another Actuator (18) is connected, of which a membrane drive (19) with the output of the logic unit (10) is connected (Fig. 1). 4. The rate of pressure rise limiter according to any one of claims 1-3, wherein the rate of pressure rise signal generator connected in series an element for initial adjustment of the signal generator, a control signal generator and contains a comparator, characterized in that the pressure increase rate signal generator (7) has a delay element (26) which is connected in parallel to a comparator (25) Container (34) and one connected to the output of the comparator (25) connected to the atmosphere Exchangeable throttle (35) has (Fig. 3).