FR2471590A1 - meter calibration system for hydrocarbon liquids - has piston travelling along tube past two proximity indicators to provide accurate vol. of liq. fed through meter - Google Patents

Abstract

A tube is used to deliver a known vol. of liq. through a meter. The tube contains a piston with an axial hole contg. a spring-loaded valve. The valve is initially held in its open position by a winch cable, so the tube can be filled with liq. The cable is then released, so valve closes. The pressure of the liq. then drives a piston along the tube past two proximity detectors, which each deliver an electric signal, so the vol. of liq. delivered between the two signals is exactly known. The appts. is used e.g where a petrol meter delivers one counting pulse for every 10 ml delivered, the number of pulses obtd. between the two proximity signals can be counted.

Description

Calibration and control device for liquid meters,
in particular of liquid hydrocarbon meters.

 the present invention relates to a device for calibrating and verifying a liquid meter, in particular a liquid hydrocarbon meter, by means of a standard volume.

In the prior art, several methods and devices are already known for calibrating or checking a liquid meter by means of a standard volume:
In a known method, a known capacity (standard volume), called gauge, is filled with a liquid passing through the meter to be checked, then the volume of the gauge is compared to the volume indicated by the indicator driven by the meter. This method is precise, but has the disadvantage of involving, during its implementation, non-use. of the distribution installation on which the meter is mounted. In addition, you must then empty the heel volume to reuse it.

Also known are standard loops which comprise a tube in which the flowing liquid pushes a spherical piston. The standard volume is constituted by this tube placed in derivation of the circuit after the counter to be checked. The piston is initially loaded at a loading station and recovered at the end of the check at an unloading station. Each measurement requires emptying, opening of the standard loop, transfer of the pis ton and purging of the capacity before operation.

 The object of the present invention is to enable the control of the meters by means of a standard volume without having any of the above-mentioned drawbacks.

To this end, the present invention relates to a peddling device in coabination:
- a plain tube with two orifices located at different points along the length of this tube, these orifices one constituting the inlet, the other the outlet of the tube;
- A piston placed in this tube in which it can slide while sliding with sealing against the internal wall of this tube, that between a first extreme position located downstream of the entry orifice and a second extreme position located upstream of the exit port, the piston being traversed from one face to the other by a passage and being. provided with a shutter member for this passage, this member being movable on the piston to which it is linked and comprising, on the one hand, return means which urge it towards the closed position and, on the other hand, a control pusher which is directed towards the outlet orifice and can put it in the open position when it is pushed ;;
- A winch mounted in a space located upstream of the first extreme position, this winch carrying a cable attached to said shutter member;
- Downstream of the second extreme position, a stop which is carried by the tube and which is located on the trajectory of said pusher;
- Detector or indicator members which signal that the piston is present in one or the other of at least two different places along the length of the tube which are located between said extreme positions.

When checking a coaptor the device works as follows
The piaton being in the first extreme position and the liquid flowing through the tube crossing the passage arranged in the piston, the winch is released. Under the effect of the return means, the shutter member closes the passage in the piston, and the latter is then pushed by the liquid and causes the emission of a first then a second signal by the detector members or indicators. Then, the pusher linked to the shutter member meets the stop, which opens the passage in the piston which stops in the second extreme position.

The counting indications or pulses coming from the counter are taken into account between the emission of the first signal and the emission of the second signal and are compared with the volume of the part of the tube included between the places where the piston was when the emission of the first signal, then of the second signal
To return the piston to the first extreme position, in order to carry out another check, it suffices to actuate the winch so as to wind the cable there. The piston is then pulled through the shutter member that the target pull maintains on opening condition.

It is obvious that such a device does not require any interruption of service, if it is installed at a fixed post (either on an oil pipeline or in a distribution station), since the liquid can always flow either through the piston either by pushing it.

 In a preferred embodiment, the detector or indicator members consist of proximity detectors placed on the tube, at said different locations located between the extreme positions of the piston, which gives the device a particularly simple structure.

 In order to reduce the number of components of the device as much as possible, it is also advantageous for the passage passing through the piston to be a hole in which a valve seat cooperating with the valve member is arranged, which is then constituted by a valve with a stem. . This rod then constitutes the control pusher, and it is at the head of this valve that the target is attached.

 the description which follows, with reference to the accompanying drawings by way of nonlimiting examples, will make it possible to understand clearly how the invention can be put into practice.

 FIG. 1 represents an overall view of a device according to the invention n arranged at a fixed station in a hydrocarbon distribution station.

 FIG. 2 represents a view in longitudinal section of a first embodiment of the device according to the invention, oriented in the opposite direction to that in which it is shown in FIG. 1.

 Figure 3 shows an enlarged sue of the piston, shutter member, elastic return means of eelui-ai and seals arranged on either side of the grooves which, when the piston is at one of its extreme positions are in front of bleed holes arranged in the tube.

FIG. 4 schematically represents an embodiment of the device in which the piston is placed outside the liquid flow path when a plant is not being carried out.

Figure-5 illustrates another possible arrangement of the device which is shown mounted on a pipeline.

 FIG. 6 shows a distribution plague equipped with a central unit device according to the invention.

 In FIG. 1, one can see a series of distributors I of liquid hydrocarbon, for example petrol or diesel distributors, of a type known per se. Each dispenser 1 has a counter which it is desired to be able to possibly control by means of a device 2 according to the invention. This is arranged by having distributors there, between the liquid source and the distributors. The source here consists of a pump 3 which is immersed in an underground tank 4 and supplies the distributors via a pipe 5, 6.

 In Figure 2, one can see a possible embodiment of the device 2 according to the present invention.

 This device comprises a tube 8 provided with two orifices 9 and 10 which, in this example are formed by the ends of this tube. The orifice 9 is here the inlet orifice of the tube 8, while the orifice D constitutes the outlet orifice of this tube. Connection pieces 6 'and 7' respectively connect the orifices 9 and 10 to the portions 6 and 7 of the pipe going from the source to the meter-distributors 1. The device is therefore inserted in series in the flow path of the liquid passing through that of the meters that you want to control.

 A piston 11 is placed in the tube 8 in which it can slide while sliding with sealing against the internal wall of this tube, that enters a first extreme position (in which it is represented in solid line in figure 2) located downstream of the inlet 9 and a second extreme position located upstream of the outlet.

 In Figure 2, the piston is shown in broken lines, in llwg in this second extreme position. The piston 11 is crossed from one face to the other by a passage 12 and is provided with a member 13 capable of closing this passage. This shutter member 13 is movable on the piston to which it is linked and comprises, turned towards the outlet orifice, a control pusher 14 (Figures 2 and 3) capable of putting it in the open condition.

Upstream of the first extrAeme position of the piston 11, the device comprises an enclosure 15 in the interior space 16 of which and located a winch 17 carrying a cable 18 attached to said shutter member 13.

 Downstream of the second extreme position of the piston (11 "), the device is provided with a stop 19.

This stop 19 is carried by the tube 82 here by the intermediary of the connecting piece 7 '. The stop 19 is located on the path of the pusher 14 which meets it by its open end 15 when the piston reaches the second extreme position.

 According to the invention, the device further comprises detector or indicator members which signal the possible presence. of the piston in one or the other of at least two different locations of the length of the tube, which locations are located between said extreme positions.

In the example shown in FIG. 2, these detector or indicator members consist of two sensors 20, 21 of a type known per se, mounted on the tube at said different locations which are marked by the lines Eo, Ep marked in dotted lines .

These sensors 20, 21 are, for example, members for detecting the proximity of the piston. When the piston, or a member carried by it, arrives near the sensor 20 the latter emits a signal. From stem, sensor 21 emits a signal when the piston comes close to it. It is imperative that the positions of the piston to which the emission of a signal corresponds (by the detector or indicator bodies) are located between the extreme positions 11 and 11 of the piston.

In general, such a detector, located or not at a place, Eo or Ep where the presence of the piston must cause the emission of a signal, can be constituted by any known known means (mechanical, electrical, electromagnetic, inductive, optical, opto-electronic, etc.) making it possible to detect the presence (or the passage), in a given position, of the piston or of an organ or reference linked to it.

 The operation of the device with the above-mentioned members is as follows: Liquid passing through the meter to be checked flows from the inlet orifice 9 to the outlet orifice 10 passing through the passage 12 passing through the piston. This passage is initially opened because the shutter member 13 is retained in the open position by the cable 18 secured to the winch 17 which is then in blocking condition. The low pressure drop inherent in the passage 12 creates a slight pressure difference between the two faces of the piston 11 which is biased in the direction of flow but remains stationary because the shutter member 13, which is linked to it, retains it.

Thus, as long as the winch 17 remains blocked, the piston remains stationary and the liquid can flow without encountering any obstacle. If, while the liquid is flowing, the winch 17 is released, the shutter member 13 closes the passage 12. The piston 11 is then driven back by the liquid and moved towards the outlet 10 of the tube while in the condition shown in 11 '. During its movement it passes in front of the first presence detector 20 which then emits a first signal, then in front of the second presence detector 21 which emits a second signal
When the piston 11 reaches its second extreme position, the pusher 14 gives the stop 19 which puts the shutter member 13 in the open condition and immobilizes the piston. As the piston constituted, during its movement, a perfect shutter , it follows that the volume of liquid passed between the emission of the first and of the two signal is perfectly known, since it only depends on the internal section of the tube 8 and on the distance between the places Eo and Ep and can therefore constitute a standard volume. Consequently, checking the counter simply consists in comparing the standard volume with the volume recorded by the counter between the emission of a signal by the sensor 20 and the emission of a signal by the sensor 21.

 If the controlled counter l is of the type with emission of counting pulses (for example one pulse per one centiliter) the control then consists in counting the pulses emitted between the signals of the proximity detectors 20 and 21. This checking counting can be performed by any process, including electronics, within the reach of ordinary skill in the art.

After a control operation, the device can either be immediately returned to the initial condition by means of the winch (C using which the piston is brought back to its first extreme position by means of the target 18 and the shutter member 13 which is linked to the piston), either remain in the condition shown in 11 "and be brought back to the initial condition only just before carrying out a new check.

 In the device described so far, the passage 12 passing through the piston is a hole in which a seat 12 'is arranged for a shutter member constituted by a valve with rod 14. This rod constitutes the control pusher. It is at the head of this valve 13 that the atble is attached.

 As for the return means urging the shutter member towards the closed position, they can be hydrodynamic and / or elastic. If they are hydrodynamic, they are then formed by the head of this valve that the current of liquid tends to apply on its seat.

 However, the production of a large hydrodynastic force implies the establishment of a significant pressure drop on the liquid flow path.

However, such a pressure drop is not desirable in a device such as that shown, especially if it is installed once and for all in a distribution station. In addition, at low flow rates, the bydynamic force is very low and may be insufficient to bring the shutter member into the closed position when the cable 18 is released by unlocking the winch 17.

It is therefore advantageous to use elastic return means such as a spring 22 (FIG. 3). This spring then bears against the piston and surrounds the rod 14 of the valve. It is / a relief 15 with which the rod is provided that it urges the valve towards its closed position.

 For the reasons indicated above, it is advantageous for the pressure drop created by this device shown to be as low as possible. To this end, the head of the valve returned by the spring 22 preferably has a hydrodynamic profile promoting the flow of the liquid when the valve is detached from its seat.

Of course, this is only a preferred embodiment, other embodiments being possible within the scope of the invention. This is how the piston could, for example, constitute the body of a tap (shutter member) which would be controlled by a pusher and which would be returned to the closed position by a spring. Although more complicated and less advantageous, such a shape However, it is within the scope of the invention.

 In order to ensure the accuracy and reliability of the calibration device, it is very important that the tightness of the piston in the tube 8 is perfect. For this, the piston 11 is advantageously provided with one or more seals 23 of a type known per se. In order to enable a possible leakage to be detected and to determine its importance in order to correct the measurement made, it is advantageous for the piston 11 to include at least one pair of seals 23, 23 ′ rubbing estre the wall of the tube 8, and comperte a groove 24 located between the joints of this pair 23, 23 '. In the vicinity of each of the extreme positions of the pisten, the tube then has as many purge orifices 25 as there are grooves 24. Each purge orifice 25 can communicate with the outside via a tap purge 26.

As each bleed orifice 25 is located at the place where the corresponding groove 24 is placed when the piston 11 is in the corresponding extreme position, it follows that checking the tightness of the piston and determining the volume correction to make to a measurement can be done as follows:
Before checking a counter, while the piston 11 is in the first extreme position (in which it is shown in solid lines in FIGS. 2 and 3) and the shutter member 13 is in the open condition , all the purge valves 26 are opened and any liquid present in the annular cavities formed by the grooves 24 is discharged.

When these cavities contain only air. the valves 26 are closed again, then, the pump 3 (figure 1) delivering, the winch is released 17. When the piston 11 reaches its second extreme position (at 11 "in figure 2), the purge valves 26 are opened ', 26 "located in the vicinity of this extreme position and any liquid contained in the cavities 24 is collected. As long as the volumes of liquid collected in 26' and 26" are less than the volumes of the cavities 24, it is guaranteed to be able to correct the measurement made.

In Figures 1 and 2, the tube 8 of the device is shown with a diameter greater than that of the pipe connecting the meter or meters to the source of liquid. Of course, this is by no means imperative.

The diameter of the tube 8 can have any value compatible with the precision and the space required.

FIG. 4 illustrates an embodiment in which the diameter of the tube 8 is identical to that of the pipe 6, 7, on which the device is inserted.

In this embodiment, the tube has - in addition to the inlet 9 and the outlet 10 - a third hole which is a second inlet 9 '. This is located downstream of the first extreme position of the piston (in which it is represented in FIG. 4), at a point not included between the proximity detectors 20, 21. A valve (or tap) 27 to three channels 27a, 27b, 27e, one channel 27a of which can be selectively put into communication with one or
others the other of the two / channels 27b, 27e, is connected to these two inlet orifices, 9, 9 ′ by the latter (27b, 27c).

This embodiment is particularly suitable for devices installed in a fixed position in distribution installations such as that shown in FIG. 1.

When the meter (s) have been checked and are in normal operation, the valve 27 and the piston 11 are in the position shown in FIG. 4. The device then does not constitute any pressure drop. When it is desired to control a counter, the valve 27 is placed in a position in which the channel 27a is in communication with the channel 27b, then the operation is carried out as described above.

 In this embodiment, the stop 19 is constituted by a bar, perpendicular to the plane of FIG. 5, occupying a diametrical position in an intermediate flange 19 ′ interposed between the outlet orifice 10 of the tube and the pipe 7. In addition, the shutter member 13 is constituted by a conventional mushroom-shaped valve, so that the return means are here both hydrodynamic and elastic. Of course, one could use equivalent means without departing from the scope of the invention.

Thus, for example, the three-way valve 27 could be replaced by two simple valves mounted on the upper branches of the Y-connector or
T. In all the embodiments, the winch 17, the main function of which is to bring the piston back to the first extreme position while maintaining the shutter member in the open condition, can be of any type known per se.

 The sealed casing 15 which contains it may comprise a sealed bearing of a known type by which its control shaft 17 'exits. The rotation of the winch for the return of the piston can then be obtained by a crank or an electric motor. To immobilize the piston in the first extreme position and possibly maintain the shutter member in the open condition when the device is not in use (this maintenance in the open position is only necessary in the embodiments without external valve 27), the winch must be able to be locked and unlocked, which can be obtained, for example, by sliding the shaft 17 'in a sealed bearing. We could also consider mounting in the casing 15 an electric motor plus threshold assembly with retractable stop finger by electromagnet.

In this case, there is no provision for an output bearing, watertight electrical outputs are sufficient. These solutions are in no way limiting.

 As for the piston positions for which there is emission of a signal, their number is not necessarily limited to two, a larger number possibly allowing binding to perform in a single operation of the contrals with different flow rates.

 The word "cable" used to designate the flexible member 18 connecting the piston to the winch-through the shutter member must obviously be taken in the widest sense: it may just as well be a wire, with one or more strands, than a braided or woven ribbon, or a flexible band of a material compatible with the liquid passing through the tube 8.

 The device according to the invention can title designed either as a mobile device that can be brought to the various places where there are counters to counter, or as a fixed device installed once and for all. In this case, it can be either buried, as shown in Figure 1, fool on the outside as shown in Figure 5 which corresponds to a mounting on a pipeline, for the control of turbine meters.

 It is only to show that it is by no means essential that the space containing the winch 17 is outside the path of passage of the liquid that the embodiment shown in FIG. 5 has been chosen. such as that shown in Figures 2 or 4 could just as well be considered here. It can also be noted, in FIG. 5, that the stop 19 can be constituted by a rod arranged axially and carried by an intermediate flange 19 '.

 Figure 6 shows another possibility of using the stationary device. It is a loading platform 30 on which three loading stations are grouped together, each comprising a riser 31 leading to an articulated and orientable tubular system 32- for loading portable tanks.

Each column 31 is associated with a trap 33 and a counter 34, the indications of which are transmitted to another indicator 35 placed on the bridge.

 The gateway 30 carries a device according to the invention, of which the standard tube 8 and the case 15 containing the winch have simply been shown. Each supply column of a loading arm comprises, downstream of its counter 34, a valve 37 enabling it to be connected either with its loading arm 32 or with a pipe 36 going to the inlet of the device. The output of the device is permanently connected to a loading arm 32 ′ by which the liquid is discharged when one of the meters 33 is centralized. It is therefore seen, in this example, that the device can be mounted downstream of the counter checked.

Of course, the invention could equally well be applied to the control of the meters of the "source" filling stations, that is to say, of the stations for filling tanks from the bottom thereof.

 This extremely simple system can be installed on vehicles and thus constitute a mobile central unit.

Claims (9)

- Detector or indicator members which signal that the piston is present in one or the other of at least two different places along the length of the tube which are located between said extreme positions.  - Downstream of the second extreme position, a stop which is carried by the tube and which is located on the trajectory of said pusher;  - A winch mounted in a space located upstream of the first position, this winch carrying a target attached to said shutter member;  - a piston placed in this tube in which it can slide while sliding with sealing against the internal wall of this tube, that between a first position ex fallopian tube located downstream of the entry orifice and a second extreme position located upstream of the outlet orifice, this piston being traversed from one face to the other by a passage and being provided with a shutter member for this passage, this member being movable on the piston to which it is linked and comprising, on the one hand , return means which urge it towards the closed position and, on the other hand, a control pusher which is directed towards the outlet orifice and can put it in the open position when it is pushed;  - A tube provided with two orifices located at different points of the length of the tube, these orifices constituting one the inlet, the other the outlet of the tube; l.- Device for calibrating and verifying a liquid meter, in particular a liquid hydrocarbon meter, by means of a standard volume, this device so characterized by the fact that it comprises in combination: 2.- Device according to claim 1, charac terris in that the detector or indicator members are constituted by proximity detectors placed on the tube at said different locations located between said extreme positions.  - it is at the head of this valve that the char is attached.  - The control pusher is constituted by the stem of this valve;  - the shutter member is a stem valve;  - The passage through the piston is a hole in which is fitted a valve seat; 3. - Device according to any one of the preceding claims, characterized in that  4.- Device according to any one of the preceding claims, characterized in that the return means urging the shutter member towards the closed position are hydrodynamic.  5.- Device according to any one of the preceding claims, characterized in that the return means urging the shutter member towards the closed position comprises a spring.  6.- Device according to claims 9 and 5, characterized in that the spring is a compression spring bearing against the piston and surrounding the valve stem which - by a relief which this stem is provided - is biased towards the closed position.  7.- Device according to any one of the preceding claims, characterized in that  - The piston has at least one pair of seals rubbing the chest of the tube paoi and has a groove located between the seals of this pair;  - The tube comprises, in the vicinity of each of said extreme positions of the piston, a purge orifice communicating with the outside by means of a purge valve, each purge orifice being located at the place where said groove is placed when the piston is in the corresponding extreme position.  8.- Device according to any one of the preceding dilation income, characterized in that the tube comprises a third orifice constituting a second inlet orifice situated downstream of the first position, end of the piston, at a point not included between the places for which the presence of the piston is detected or indicated, and by the fact that a three-way valve, one way of which can be selectively put in communication with one seen the other of the two other ways is connected to these two orifices by these two other routes. 9. A liquid distribution and / or loading station, comprising at least one liquid meter and a device according to any one of the preceding claims Mounted on the liquid flow path, in series with said meter.