APPARATUS FOR FLOW EQUIPARTITION

Technical field

This invention addresses the technical field relating to the distribution of gas.

More specifically, the invention relates to an equipartition apparatus for systems or stations for adjusting the pressure on two or more lines.

Background art

The systems or stations for adjusting the pressure on several lines are basically plants which allow networks to be fed for carrying and distributing gas to civil and industrial users.

Purely by way of example, systems for adjusting the pressure are used in distribution networks for reducing the gas pressure from medium pressure to low pressure.

With reference to the standards currently in force in Italy, low feed pressure means a pressure between 0.04 bar and 12 bar, medium feed pressure means a pressure between 12 bar and 24 bar, and above this one speaks of high pressure.

The reference to“two or more lines” in the above-mentioned adjusting systems refers to the fact that they usually consist of several pressure adjusting lines arranged in parallel.

Of these lines, one is generally referred to as“main”, as it is normally operational, and the others are referred to as“secondary”, as they are normally inactive and designed to enter into operation in the case of a fault or malfunction of the main line.

The main and secondary lines are calibrated differently and, if the main line is no longer able to feed gas at the calibration pressure, the secondary lines activate automatically, feeding gas at the relative calibration pressure, which is lower than that of the main line. Gas distribution firms are starting to make low cost and fully automatic apparatuses for equipartition of the flow that allow the two or more existing lines to be always run in parallel with a flow of gas equipartitioned and substantially equal.

In short, this modification would theoretically allow the achievement of many advantages, including a considerable lowering of the noise linked to the subdivision of the flow between several lines or the elimination of the problems of sticking of the seals (O-rings) which sometimes occurs when, following a fault on the main line, an emergency line (secondary) must intervene after long periods of inactivity or, also, the possibility, thanks to the simultaneous operation of several lines in parallel, of designing them to each cover a percentage of the overall flow.

There are prior art devices designed to automatically control the equipartition of the flow between various lines in parallel but these devices, even though they are worthwhile in terms of many aspects, are not free from drawbacks.

One of these drawbacks is connected precisely to the automatic operation of the devices. In fact, in the case of an intervention due to a malfunction in one of the lines in parallel, the automatic switch intervenes in order to separate and render independent the two lines and, when the pressure values stabilise again on the calibration values, it returns, automatically, to its initial operating condition. This operating mode, although apparently valid and effective, is not always useful as it does not in practice allow the operator to understand the causes of the malfunction, and this could result in ignoring any signals of damage or imminent breakages even of significant extent.

Disclosure of the invention

The aim of the invention is therefore to provide a technical solution which overcomes this drawback, by means of an equipartition apparatus which is able to operate effectively and safely in the case of a fault or malfunction on one of the gas feed lines, and which is also inexpensive to make.

A further aim of this invention is to provide an equipartition apparatus which allows simple operation and practical control.

The above-mentioned aims are achieved according to this invention by an apparatus for equipartition of the flow of gas comprising the technical features described in the appended claims.

According to an aspect of the invention, the invention provides a system for equipartition of the flow in gas distribution lines. The system comprises a main control line and a secondary control line.

Each line of said main and secondary control line includes a respective controlled“master” service adjustment device (first and second pressure adjustment device), configured to adjust, under normal conditions of use, the pressure of the corresponding line. Each line of said main and secondary control line includes a respective controlled “monitor” adjustment device (that is to say, safety device), (third and fourth pressure adjustment device), configured to control the pressure of the corresponding distribution line if faults occur at the corresponding“master” service adjustment device.

The main line comprises a first control unit, connected to the“master” service adjustment device of the main line for adjusting it so as to maintain an operating pressure in the first line at a first predetermined value (first predetermined pressure).

The secondary line comprises a second control unit, connected to the “master” service adjustment device of the secondary line for adjusting it so as to maintain an operating pressure in the secondary line equal to the primary line (that is to say, at the predetermined pressure P1 ). To do this, the first and the second control unit are connected pneumatically through a pneumatic conduit for sending a same control pressure to the corresponding "master" adjustment devices. The pneumatic conduit is intercepted by a pneumatic lock switch (a lock valve), which is set to prevent the pneumatic connection for pressure values in the primary line equal to or greater than a second predetermined value (activation pressure of the lock switch).

In the absence of pneumatic connection between the first and the second control unit, the second control unit is configured to maintain the operating pressure value in the secondary line equal to a third predetermined value (second predetermined pressure).

The main line comprises a third control unit, connected to the safety adjustment device (that is to say, the “monitor”) of the main line for adjusting it so as to maintain the operating pressure in the primary line equal to a fourth predetermined value (third predetermined pressure).

The secondary line comprises a fourth control unit, connected to the safety adjustment device (that is to say, the“monitor”) of the secondary line for adjusting it so as to maintain the operating pressure in the secondary line equal to a fifth predetermined value (fourth predetermined pressure).

The main line and the secondary line, upstream of the respective adjustment devices ("master" and "monitor"), comprise a respective emergency lock (that is, a second safety device), which is set to close at an emergency value.

The second predetermined value (at which the pneumatic lock switch enters into action) is greater than the first predetermined value (setting value of the first control unit) and, preferably, less than the fourth predetermined value (setting value of the third control unit). In any case, the second predetermined value is less than the emergency value. The third predetermined value (setting value of the second control unit) is less than the first predetermined value (setting value of the first control unit). The fourth predetermined value (setting value of the third control unit) is between the emergency value and the first predetermined value (setting value of the first control unit).

The above-mentioned features, which specify the numerical relations between the various setting values of the adjustment devices of the primary and secondary line allow an intervention procedure to be performed in a precise manner which must be performed if faults or malfunctions occur, which can potentially cause significant pressure deviations from the required network pressure.

In particular, if the“master” service adjustment device of the primary line (or the corresponding first control unit) loses part of its functionality, an increase in pressure can occur relative to the first predetermined value. In this case, when the operating pressure reaches the second predetermined value, the pneumatic lock switch closes the pneumatic connection. The operating pressure in the secondary line will therefore be adjusted by the “master” service adjuster controlled by the second control unit. In the primary line, the operating pressure is maintained at a maximum value equal to the fourth predetermined value by means of the “monitor” adjustment device.

According to an aspect of the invention, the invention provides a lock valve, configured to prevent or allow a flow of a fluid in a gas distribution line.

According to an embodiment, the lock valve is operated pneumatically. This enables it to be implemented in lines which are located in zones where the availability of electricity is limited or not convenient.

According to an embodiment, the lock valve has a connection (for example threaded or by means of flange), configured to be connected to the pneumatic line on which the lock valve is installed.

According to an embodiment, the connection is of the threaded type with a nominal diameter of ¼”. This allows use of pneumatic valves even in very small lines on which solenoid valves are generally used.

Brief description of the drawings

The technical characteristics of the invention, with reference to the above- mentioned aims, are clearly described in the claims below and its advantages are more apparent from the detailed description which follows, with reference to the accompanying drawings which illustrate preferred, non-limiting embodiments, and in which:

Figure 1 is a schematic view of a preferred embodiment of the apparatus for equipartition of the flow according to the invention;

Figure 2 is a schematic cross-section view of a detail of the apparatus of Figure 1 in a first embodiment of it;

Figure 3 is a schematic cross-section view of a variant embodiment of the detail of Figure 2;

- Figures 4A and 4B illustrate, respectively, a first and a second embodiment of a release element of the apparatus of Figure 2.

With reference to the accompanying drawings, the numeral 100 denotes in its entirety an apparatus for equipartition of the flow between several gas feed lines.

Detailed description of preferred embodiments of the invention

With reference to Figure 1 , the numeral 1 denotes a section of a first line for feeding gas hereafter also referred to as the main line.

Numeral 2, on the hand, denotes a section of a second line for feeding gas, parallel to the above-mentioned first line 1 , hereinafter also referred to as the secondary line.

Respective arrows indicate the direction of travel of the gas along the lines

1 , 2.

With reference to the first line 1 , along the section illustrated there are, one after the other, two devices 3, 4, of substantially known type, for adjusting the pressure.

The adjusting device 3 positioned upstream relative to the above- mentioned direction of travel is a reserve device whilst the adjusting device 4 positioned downstream is the one normally operating, which therefore adjusts the pressure of the gas passing through it. The adjusting device 4 positioned downstream will be referred to hereinafter also as the first adjusting device.

Similarly to what was just described, considering the second line 2, along the section illustrated there are, one after the other, two respective devices 5, 6, for adjusting the pressure, also of substantially known type.

The adjusting device 5 positioned upstream, relative to the above- mentioned direction of travel, is a reserve device whilst the adjusting device 6 positioned downstream is the one normally operating, which therefore adjusts the pressure of the gas passing through it. The adjusting device 6 positioned downstream will be referred to hereinafter also as the second adjusting device.

The above-mentioned pressure adjusting devices 3, 4, 5, 6 contribute to defining, on the lines 1 , 2, a pressure adjusting system.

For each of the pressure adjusting devices 3, 4, 5, 6, the apparatus 100 comprises a respective control unit 7, 8, 9, 10.

The control units 7, 8, 9, 10 are of substantially known type and are actuated pneumatically using the difference in pressure of the gas between upstream and downstream of the pressure adjusting devices 3, 4, 5, 6.

Each control unit 7, 8, 9, 10 is connected to the respective adjusting device 3, 4, 5, 6 by a respective drive conduit 7a, 8a, 9a, 10a.

In the following description, the control units 8, 10 of the first and second pressure adjusting device 4, 6 will also be indicated, respectively, as the first control unit 8 and the second control unit 10.

Each feed line 1 , 2 also comprises a respective actuating conduit 1 1 , 12 for driving the control units 7, 8, 9, 10.

On the first line 1 , downstream of the first adjusting device 4, there is a pressure pick-up point 13.

From this point, 13, advantageously integrating a manifold 14, a plurality of pipes 15 extend, designed to transmit the measured pressure value (normally P1 ) to the various devices forming part of the adjusting system on the line 1.

Similarly to that just described with reference to the first line 1 , also on the second line 2, downstream of the second adjusting device 6 there is a pressure pick-up point 16.

From this point 16, advantageously integrating a manifold 17, a plurality of pipes 18 extend, designed to transmit the measured pressure value to the various devices forming part of the adjusting system on the line 2.

In particular, both the pressure adjusting devices 3, 4, 5, 6 and the relative control units 7, 8, 9, 10 need, in known manner, for the correct operation, to receive a signal representing the pressure value downstream of the first and second adjusting device 4, 6.

A way to transmit this value is that of placing directly in communication each of the above-mentioned adjusting devices and control units with the gas on the respective line, downstream of the adjusting device 4, 6.

As illustrated in Figure 1 , the equipartition apparatus 100 comprises a pneumatic conduit 19 for connecting the first control unit 8 of the first adjusting device 4 with the second adjusting device 6, to determine in the second line 2, downstream of the second adjusting device 6, a pressure P1 equal to that adjusted on the first line 1.

In practice, the pneumatic conduit 19 connects the conduit 8a with the conduit 10a, effectively excluding the control unit 10 from the control of the second adjusting device 6, thanks to the calibration pressure P2 of the unit 10 which is less than the calibration pressure P1 of the unit 8.

In other words, by means of the pneumatic connection conduit 19 the control unit 8 of the first adjusting device 4 also controls the second adjusting device 6, effectively equipartitioning the pressure of the gas passing along the two lines 1 , 2 downstream of the apparatus 100.

As illustrated in Figure 1 , the equipartition apparatus 100 comprises a pneumatic lock switch 20 positioned along the above-mentioned pneumatic connection conduit 19.

The pneumatic lock switch 20 is designed to interrupt the pneumatic connection between the first control unit 8 and the second device 6 for adjusting the pressure of the second line 2.

As illustrated in Figure 1 , the apparatus 100 comprises a pneumatic conduit 21 for feeding the switch 20. The switch 20 is therefore a pneumatically operated lock switch.

The pneumatic feeding conduit 21 is connected to the first gas feed line 1 , downstream of the first adjusting device 4, in a zone subjected normally to the above-mentioned first predetermined pressure P1.

Advantageously, the pneumatic conduit 21 is connected to the manifold 14 defining the above-mentioned pick-up point 13.

The above-mentioned pneumatic feeding conduit 21 defines for the apparatus 100 means of a pneumatic type for controlling the pneumatic lock switch 20.

The pneumatic lock switch 20 is manually reset, meaning that once its function for interrupting the pneumatic connection conduit 19 is activated, it can be returned to the relative open condition (that is, without interruption of the conduit 19) only by means of manual intervention by an operator.

The pneumatic lock switch 20 is shown schematically in Figure 1.

Figure 2, on the other hand, illustrates, denoted by the reference numeral 20’, a first embodiment of the pneumatic lock switch.

The pneumatic lock switch 20’, of a substantially known type for other uses, comprises a valve element 22 which is normally open and configured to occlude the pneumatic connection conduit 19.

As illustrated in Figure 2, the above-mentioned valve element 22 has a longitudinal extension in a predetermined axis A1 and is slidable, inside a body 23, complete with a cap 23a, of the pneumatic lock switch 20’, relative to the axis A1. The valve element 22 is operatively connected to a release element 24 which, under the action of certain pressure values of the gas present in the pneumatic feeding conduit 21 , according to known methods in the locking devices of this type and therefore not described further, is set up to free the valve element 22, which, precisely, closes the pneumatic connection conduit 19.

According to an embodiment, the release unit 24 is a lever, rotatable about a hinge 24’. In particular, the release unit 24 is connected with a control element 24A, which moves along a direction perpendicular to the direction of sliding of the valve element 22.

The movement of the control unit 24A is determined by a variation of the pressure of the pneumatic supply conduit 21. The control unit 24A is in contact with the lever 24 in a contact surface S. The control unit 24A moves maintaining the contact with the lever 24 in the contact surface S.

In particular, after the activation of the lock switch 20, during the manual reset, the lever 24 is configured to rotate about the hinge 24’ and to slide relative to the control unit 24A. For this reason, the friction of the control unit 24A on the contact surface S influences the ease of reset, which, in turn, influences an operational range of the lock switch 20.

According to an embodiment, the contact surface comprises a sliding surface S1 , which is inclined relative to the direction of maximum extension of the lever 24 by a sliding angle A.

The sliding angle is between zero and ninety degrees. According to an embodiment, the sliding angle A is between 10 degrees and 30 degrees. According to an embodiment, the sliding angle is between 40 degrees and 60 degrees.

According to an embodiment, the sliding angle A is 54 degrees. As the inclination of the inclined surface S1 increases, the reset force reduces. According to an embodiment, the pneumatic lock switch 21 comprises an additional socket 19’. The additional grip 19’ is in fluid communication with the conduit 19. According to an embodiment, the apparatus comprises a pressure sensor, which can be inserted in the additional socket 19’ to detect the pressure in the pneumatic conduit 19.

According to an embodiment, the connection of the pneumatic lock switch 20 is of the threaded type and has a nominal diameter of ¼”. These dimensions are generally too small for pneumatic valves and solenoid valves are therefore used. However, with this modification in size to the pneumatic valves they can be applied even in remote areas where electrical power is unavailable or not convenient.

More in detail, again with reference to Figure 2, the valve element 22 comprises a cap 22a which, at the time of activating the pneumatic lock switch 20’, closes the pneumatic conduit 19 moving in the direction of the arrow F.

The valve element 22 also comprises a shaft 22b.

Advantageously, the pneumatic lock switch 20 has a cover 25 screwed to the above-mentioned cap 23a protecting the longitudinal end of the shaft 22b of the valve element 22.

The cover 25 has a cavity 25a threaded internally which, once the cover 25 is disengaged from the cap 23a, is configured to screwably engage with the above-mentioned longitudinal end of the shaft 22b of the valve element 22, which is in turn threaded.

By means of the cover 25 screwed on the end of the valve shaft 22b, an operator, pulling in the direction indicated by the arrow F’, can reset the switch, returning it to the condition of non-interruption of the connection conduit 19.

When the cover 25 is engaged by screwing with the valve element 22, the means M for manually resetting the pneumatic lock switch 20’ are defined. Figure 3 illustrates, denoted by the reference numeral 20”, a second embodiment of the pneumatic lock switch.

The pneumatic lock switch 20”, during normal operation, is open and its intervention is only planned in certain circumstances, such as, for example, the above-mentioned emergency situations.

More in detail, the pneumatic lock switch 20” comprises a shutter O, shown only partly in Figure 3, since it is shown in the retracted configuration, the shutter O being designed to move between two limit positions for, respectively, opening and closing the flow of gas.

The pneumatic lock switch 20”, of substantially known type, has a mechanism 26 for driving the shutter, the mechanism 24 comprising a plurality of linkages. The linkages, schematically illustrated in Figure 3, contribute to defining, together with a spring 27, a position of stable equilibrium at which the shutter O is maintained in the open configuration.

The drive mechanism 24 is also connected to a pneumatic baffle 28 facing into a chamber 29 wherein there is normally a predetermined pressure value.

By using the pneumatic feed conduit 21 , leading into the chamber 29, it is possible to place the chamber 29 at a pressure which is greater than the above-mentioned predetermined pressure, thereby destabilising the drive mechanism 26 which, abandoning its position of equilibrium in an open configuration, causes the immediate closing of the shutter and, consequently, the locking of the pneumatic connection conduit 19.

In use, with reference to the diagram shown in Figure 1 , during normal operation, the first control unit 8 of the first device 4 for adjusting the pressure of the main line 1 also controls the second device 6 for adjusting the pressure of the secondary line 2. In this way, both the lines 1 , 2 feed gas downstream at the same calibration pressure P1 as the first control unit 8, splitting the requested flow between them.

According to an embodiment, the calibration pressure P1 of the first control unit 8 is 20 mbar.

This, as mentioned, occurs under normal operation of the equipartition apparatus 100, where, precisely, the flow of gas is equally distributed between the main line 1 and the secondary line 2.

The pneumatic lock switch 20 is therefore normally inactive, that is to say, open, allowing the pneumatic connection between the first control unit 8 and the second device 6 for adjusting the pressure of the secondary line 2, through the connection conduit 19.

In this normal operating condition, the second control unit 10 associated with the second device 6 for adjusting the pressure of the second line 2 is inactive.

If there is a fault or a malfunction on the main line, such as to determine downstream of the adjusting device a variation of the pressure to a value which is significantly different (normally, greater) than the calibration value of the first control unit 8, the altered pressure is established immediately also within the pneumatic lock switch 20.

The pneumatic switch 20 is calibrated to activate both at a pressure greater than that of normal operation of the main line 1 and at a pressure significantly less than that value, thus interrupting the pneumatic connection conduit 19 between the first control unit 8 and the second device 6 for adjusting the pressure of the secondary line 2.

In this way, the main 1 and secondary 2 lines are completely independent. According to embodiment, the switch 20 is configured to be activate at a pressure greater than 26 mbar and/or at a pressure less than 12 mbar. According to embodiment, the switch 20 is configured to activate at a pressure greater than 21 mbar and/or at a pressure less than 18 mbar.

In this way, pressure deviations close to the calibration value of the first control unit 8 immediately cause an activation of the lock switch 20 and a quick implementation of safety of the apparatus.

Following this interruption, the second control unit 10 becomes active on the second pressure adjusting device 6, imposing on the adjusting device 6 a relative calibration pressure.

According to an embodiment, the calibration pressure of the second control unit 10 is 17 mbar.

According to an embodiment, the (third) control unit 7, configured to control the third adjustment unit 3, is set to a calibration pressure having a value of 25 mbar.

According to an embodiment, the (fourth) control unit 9, configured to control the fourth adjustment unit 5, is set to a calibration pressure having a value of 22 mbar.

According to an embodiment, the apparatus comprises, for each line 1 , 2, a respective locking element B1 , B2. Each locking device B1 , B2 is configured to close the respective line 1 , 2 for pressures greater than an emergency value. According to an embodiment, the emergency value is 40 mbar.

According to embodiment, the switch 20 is configured to activate at a pressure of between 20 mbar and 40 mbar or at a pressure of between 20 mbar and 25 mbar.

The apparatus for equipartition according to the invention achieves the preset aims and brings important advantages.

A first of these advantages is linked to the fact that following an alteration of the pressure values on the line, the switch excludes the equipartition between the two or more lines present, which it makes impossible to re establish the equipartition without the intervention of an operator.

The physical presence of an operator is in fact a safety index in the sense that the normal operating conditions will be re-established (by resetting the pneumatic lock switch) only after verifying and resolving the causes of the malfunction which led to the intervention of the switch itself.

This degree of security is not, for example, possible with an electro pneumatic switch where the resetting of the switch is theoretically possible remotely, even without having verified the causes of the malfunction.

Similarly, the same limit is present in automatic pneumatic switches in which the re-establishing of the initial operating conditions can also occur randomly, to reach a predetermined pressure value, regardless of the causes of the malfunction and, above all, regardless of any termination of the same.

Moreover, unlike normal lock switches which are positioned directly on the relative protection line, in the case of the equipartition apparatus according to this invention, the pneumatic lock switch is positioned between two or more lines protecting the system, having the purpose of guaranteeing, in an emergency condition, the complete independence of the lines until there is a manual reset by an operator.