Device for preventing accumulation of flammable fluids in manholes containing line valves

Abstract

The device (100) prevents the accumulation of flammable gas, vapor or mists in a manhole (P) housing a ball valve (Vs) of a pipeline (T) carrying a flammable fluid. The ball valve (Vs) is closed and reopened periodically in an automatic manner by motorized means (2) of a known system (1). The device (100) comprises a ventilation box (102) communicating with the outside environment, one ventilation duct (101) housing said ball valve (Vs) and a gas sensor (103) intended to send a signal about the possible presence of a flammable gas so as to inhibit the closing / opening operation of said ball valve (Vs). The device (100) allows the system (1) to be verified to risk class "2" or as a "safe space" according to ATEX regulations, instead of the more restrictive risk class "0".

Description

[Technical field]

[0001] The present invention relates to the technical field of networks for transporting and distributing fluids, in particular flammable fluids, such as gas pipelines, oil pipelines, etc. [Background technology]

[0002] Very often, the pipelines making up these networks extend for many kilometers, branch off in several directions and even cover very large areas.

[0003] Line valves, usually, but not necessarily, of the ball type, are placed along the aforementioned pipelines to section off certain parts of the corresponding network and / or to stop the flow of fluid downstream of certain points, for example for maintenance purposes.

[0004] The size of these line valves is proportional to the diameter of the associated pipeline and can vary from approximately 4 to 16 inches.

[0005] Often the transmission or distribution network is located below ground level and each line valve is accessible through an associated inspection manhole that is closed, for example, by a manhole cover.

[0006] Under normal operating conditions of each fluid distribution network, the line valves are in an open position and this condition can persist for very long periods of time, such as months or even years.

[0007] technical challenges Thus, a valve not moving for a long period of time will almost certainly result in the valve becoming clogged. To prevent this, the companies that manage the distribution network are obliged to carry out periodic exercise cycles, usually at least every one to two months.

[0008] To carry out this cycle and maintain the correct operability of the valves, one or more employees may be dispatched to periodically inspect each valve, operate the valve to partially close it, and then immediately reopen it fully.

[0009] As can be readily appreciated, such procedures present many drawbacks with respect to manpower, timing, cost, schedule requirements, and sometimes logistics, since it is not uncommon for at least some of the line valves in a transmission or distribution network to be located in locations that are difficult to access for a variety of reasons.

[0010] To overcome these shortcomings, the same applicant filed the Italian patent application No. 102020000026648 for an industrial invention, followed by a PCT application based on WO 2022 / 097118, in which a "Method and system for automatic operation and functional verification of line valves installed in fluid distribution networks" is described and claimed.

[0011] The above-described system is intended to automatically operate line valves (e.g., ball valves), thus avoiding the need to physically be present where those valves are located.

[0012] Each ball valve is controlled by a gear motor unit, which is controlled by a sensor element that transmits data to an electronic processing and control unit, which is responsible for activating / deactivating the gear motor unit according to the operating program of the ball valve, which partially closes the ball valve and then reopens it immediately afterwards at a given time interval, which transmits reports on the results of the performed operations to a remote operation center by means of a transceiver device.

[0013] In the drawings and description above, the most common system installation configuration is considered, in which the pipeline is buried and the ball valve is housed in an inspection manhole closed by a manhole cover.

[0014] To make the system energy independent, the solar panels, charger and battery are located above ground near the manhole.

[0015] The system described above is quite satisfactory from a functional point of view, but, like any device that needs to be brought to market, it had to be verified for compliance with the safety regulations applicable to both the components of the system and the installation site.

[0016] Specifically, this last aspect takes into account regulations relating to the flammability and explosion risks of atmospheres in which flammable gases, vapours and mists are present.

[0017] The main regulatory references are Directive 1999 / 92 / EC (ATEX) and CEI EN 60079-10-1:2021-09. According to the parameters contained in the cited standards, the zones can be classified as follows: - Class 0: Highest risk due to the high probability of an explosive atmosphere being present; - Class 1: Medium hazard due to occasional possibility of an explosive atmosphere being present; - Class 2: Low risk due to the low or exceptional probability of an explosive atmosphere existing for a short period of time; -Safe Space: An environment that is free from the accumulation of explosive materials and therefore free from hazards.

[0018] In the tests carried out under the given conditions, the manhole environment is considered as class 0 due to the presence of an electrically operated gear motor unit in a compartment of limited volume such as the manhole mentioned above. Indeed, any leakage of gas or other flammable fluid from ball valves or some joints due to faulty seals, even very small leakage, can easily saturate the manhole environment, so that, as can be easily guessed, a spark generated by the electric motor would cause an explosion in the manhole, potentially with very serious consequences.

[0019] Obviously, such a classification is highly detrimental to the market of such systems, but in reality the ball valve, and all the components enabling its connection to the pipes, are constructed to guarantee the highest safety level of tightness, making the hypothesized explosion events extremely rare and unlikely. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] Italian Patent Application Publication No. 102020000026648 [Patent Document 2] International Patent Publication No. 2022 / 097118 [Non-patent literature]

[0021] [Non-Patent Document 1] Directive 1999 / 92 / EC (ATEX) [Non-Patent Document 2] CEI EN 60079-10-1:2021-09 Summary of the Invention [Problem to be solved by the invention]

[0022] The technical problem addressed within the scope of the present invention is to overcome the key problems that lead to the classification of a system installed in a manhole into the worst risk classification by proposing to combine the system with a device for preventing the accumulation of flammable fluids in the atmosphere inside the manhole, resulting in a high level of safety and a better classification of the residual risk.

[0023] Another object of the present invention is to provide a technically simple and functionally effective device that does not require frequent maintenance and can operate properly.

[0024] A further object of the invention is to propose a device which is able to interact with the operation of the system so as to avoid, if necessary, any risk of explosion and thus be able to comply with regulations with even more favorable risk classes.

[0025] A further object of the present invention is to provide a low cost device that does not significantly impact the total cost of the system and its installation in the field. [Means for solving the problem]

[0026] These and other objects are fully realised by a device for preventing accumulation of a flammable fluid in manholes housing line valves installed in a pipeline of a network for transporting said flammable fluid, each of said line valves, for example ball valves, being maintained in an open configuration under normal operating conditions of the respective network, associated with a system comprising a gear motor unit for electrically opening / closing said ball valves, an electronic processing and control unit intended to determine the activation / deactivation of said gear motor unit according to a predefined mode, and an RF operated transceiver device interfaced with said electronic processing and control unit and intended to interact with a remote operation centre and to transmit to the remote operation centre a report on the result of each single opening / closing operation of each ball valve.

[0027] The above-mentioned device is a ventilation box located on the ground and communicating with the outside environment; at least one ventilation duct extending from the inside of a corresponding manhole in which said ball valve is housed in said ventilation box; at least one gas sensor, installed at a predetermined position between the manhole and the vent box and interfaced with the electronic processing and control unit, intended to send a signal to the unit about the possible presence of a flammable gas or vapor in the monitored air volume, so that the closing / opening operation of the ball valve is inhibited by the gear motor unit; Includes.

[0028] The features of the present invention will become apparent from the following description of preferred embodiments of a device for preventing the accumulation of a flammable fluid in a manhole housing a line valve installed in a pipeline of a network for transporting said flammable fluid, in accordance with the content of the claims and with the aid of the accompanying drawings. [Brief description of the drawings]

[0029] [Figure 1] 1 shows a general schematic diagram of the claimed device combined with a known system for motorized actuation of a line ball valve housed in a manhole. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In the above figures, the device proposed by the invention is generally designated by the reference number 100 .

[0031] The task of the device 100 is to prevent the accumulation of flammable fluids, i.e. gas, steam and mist, in the receiving manhole P of a line valve, e.g. a ball valve Vs, installed in a pipeline T of a network for transporting said flammable fluids, i.e. methane gas, oil or petroleum products.

[0032] The receiving manhole P is normally closed by a removable manhole cover K.

[0033] As already mentioned in the introduction, the ball valves Vs are maintained in an open configuration under normal operating conditions of the respective network and, in order to avoid their blocking caused by a too long inactivation of the closing means, the latter are automatically and periodically actuated by means of a system 1 implementing the method described in the above mentioned prior art document filed by the same applicant.

[0034] The system 1 according to the teachings described in the aforementioned document comprises, inter alia: a gear motor unit 2 intended to open and close said ball valve Vs, acting on a rotation control Cr external to the body of said valve Vs; a first sensor element 21 connected to the gear motor unit 2 and intended to detect the angular amplitude and direction of the rotation imposed on the rotation control Cr of the ball valve Vs; an electronic processing and control unit 3 intended to determine the activation / deactivation of said gear motor unit 2 according to a predefined mode and to receive feedback of the signal provided by said sensor element 21; an RF-operated transceiver device 4, interfaced with said electronic processing control unit 3 and intended to interact with a remote operation centre 5 and to send it reports on the results of each single opening and closing operation of each ball valve Vs; Includes.

[0035] The system 1 is independent of an external energy supply thanks to an associated power supply module 6 which comprises at least one photovoltaic panel 60 , a charger 61 and at least one storage battery 62 .

[0036] The module 6 together with the electronic processing control unit 3 and the transceiver device 4 is preferably supported by a pillar 7 located on the ground near the manhole P.

[0037] In the accompanying drawings, the pillars 7 are shown as being cut in height, however this is not in proportion to the other elements shown, for reasons which will be described below.

[0038] According to the invention, at least one ventilation duct 101 is provided in the device 100, which starts from the wall of the manhole P in which the ball valve Vs is housed, extends underground approximately horizontally over a first length 101A, then curves and continues substantially vertically over a second length 101B until it flows into a ventilation box 102 located above ground and in communication with the outside environment.

[0039] At least one ventilation duct 101 is open at both ends, has a proximal end 101C communicating with the inside of the manhole P, and a distal end 101D located at a position outside the manhole P, elevated relative to the manhole, communicating with the atmosphere, for defining a path for discharging to the atmosphere any gas that may leak from the pipe T or valve VS towards the above-mentioned manhole P.

[0040] It should also be noted that if the distal end 10D of the ventilation duct 101 can be placed in a safe location that is high enough and protected from atmospheric agents, the ventilation box 102 may, in some cases, be omitted without defeating the spirit of the present invention.

[0041] According to calculations performed to quantify sufficient airflow velocity, the ventilation duct 101 preferably has an inside diameter of at least 63 millimeters and is made from a corrugated tube of a plastic material of the type used to pass cables in electrical installations.

[0042] Furthermore, to comply with the instructions given by regulations, the ventilation box 102 is placed at least 3 meters above the ground.

[0043] Since the preferred embodiment of the device 100 is based on the assumption that the above-mentioned pillars 7 are provided as shown, it is logical to assume that the ventilation box 102 is also supported by the same pillars 7. As a result, the height of the pillars 7 is sufficient to place said ventilation box 102 at the above-mentioned height from the ground.

[0044] In this case, the second length 101B of the ventilation duct 101 is advantageously inserted inside the pillar 7 at least between the base of the pillar 7 and the ventilation box 102.

[0045] The shape of the ventilation box 102 is designed to prevent rain from entering through the opening 105, by means of which the ventilation box communicates with the outside, and a grille 104 is provided in said opening 105 to prevent the ingress of animals, leaves and / or debris.

[0046] The architectural option under consideration is shown in the accompanying drawings and includes a self-acting fan 106 positioned at the top of the ventilation box 102 and capable of increasing the air extraction flow rate from the manhole P through the ventilation duct 101.

[0047] Alternatively, and for the same purpose, a motor fan (not shown) may be provided and positioned within the interior of the ventilation box 102 and operated in response to input from the electronic processing control unit 3 described above.

[0048] The device 100 comprises at least one gas sensor 103, which is inserted at a predetermined position between the manhole P and the above-mentioned ventilation box 102, interfaces with the electronic processing control unit 3 and is powered via the above-mentioned power supply module 6 of the system 1.

[0049] Preferably, as shown, the gas sensor 103 is located inside the ventilation duct 101, in the ventilation box 102, adjacent its outlet.

[0050] However, it can be envisaged that the gas sensor 103 is placed inside the manhole P mentioned above.

[0051] Intuitively, the gas sensor 103 is intended to signal the possible presence of flammable gas or vapor in the monitored air volume to the electronic processing control unit 3, which inhibits the gear motor unit 2 from opening / closing the ball valve Vs mentioned above, so as to prevent the generation of sparks that could cause an explosion.

[0052] Upon receipt by the electronic processing and control unit 3 of information regarding the abnormal presence of flammable gas or vapor in the manhole P, as well as the associated failure in operation of the ball valve Vs, it is then transmitted by the transceiver device 4 to the remote operation center 5, so that a response plan is prepared on site.

[0053] The device 100 described above makes it possible to validate the system 1 according to the current ATEX regulations briefly mentioned in the introduction, not with risk class "0", but with the even more convenient risk class "2". Furthermore, depending on the materials and devices known to the skilled person that can be used in the construction of the electrical and electronic components present in the manhole (P), in the ventilation box 102 or in the ventilation duct 101, the manhole-ventilation duct-ventilation box environment and the space immediately outside the manhole can also be considered as a "safe space" in that it does not affect the risk of explosive accumulation in any way.

[0054] This statement is already considered to be fully supported, however the certifying engineer is expected to subsequently prepare a full technical report that will duly take into account all regulatory aspects in force in order to better investigate and support such preliminary evaluation.

[0055] Of course, the purely bureaucratic aspect of this matter, i.e. the certification of a particular risk class, does not in any way ignore the importance of the practical requirement, i.e. the improvement in safety provided when installing a system thanks to the devices described above.

[0056] It should be said that although with the slight presence of ventilation ducts and ventilation boxes it would probably be possible to obtain a more favourable risk class "1" instead of the worst class (class "0"), the gas sensors and their interaction with the operation of the system, aimed at suppressing the operation of the ball valve, would advantageously avoid any risk of explosion and, as a result, be classified as risk class "2" or even as a safe space and thus be exempt from ATEX predictions and requirements.

[0057] As can be easily seen, the proposed device is technically simple, functionally effective and highly appropriate for the given installation conditions, since it can function properly without the need for frequent maintenance.

[0058] The constructive simplicity of the described device makes it possible to keep the costs of its production low so as not to significantly affect the total cost of the system and its installation on site.

[0059] However, it is understood that what has been described above is illustrative and not limiting, and therefore any detailed variations which may necessarily occur for technical and / or functional reasons are considered to be within the same scope of protection hereafter defined by the following claims.

Claims

1. A device for preventing the accumulation of a flammable fluid in a manhole including a line valve installed in a pipeline (T) of a network for transporting said flammable fluid, each of said line valves, for example ball valves (Vs), being associated with a system (1) comprising a gear motor unit (2) for electrically opening and closing a motor for opening and closing said valves (Vs), an electronic processing and control unit (3) suitable for determining the activation or deactivation of said gear motor unit (2) according to a predefined mode, and a transceiver device (4) intended to interface with said electronic processing and control unit (3) and to communicate with a remote operation center (5), said device (100) being: at least one ventilation duct (101), open at both ends, having a proximal end (101C) communicating with the inside of the manhole (P) in which said valve (Vs) is housed, and a distal end (101D) located in a position outside said manhole (P), elevated relative to said manhole and communicating with the atmosphere, for defining a path for exhausting to the atmosphere said gas that may leak from said pipe (T) or valve (VS) into said manhole (P); at least one gas sensor (103) inserted in said ventilation duct (101) at a predefined position between said proximal end (101C) and said distal end (101D) and interfaced with said electronic processing and control unit (3) and designed to indicate to said electronic processing and control unit a possible presence of a combustible gas or vapour in the monitored air volume, said at least one gas sensor (103) including suppression means for suppressing the operation of said valve (Vs), said suppression means being operated by said electronic processing and control unit (3) in response to a signal of the presence of said gas, intended to suppress the operation of said valve (Vs) by means of said gear motor unit (2) when gas is present; A device comprising:

2. 2. The device according to claim 1, characterized in that it is provided with a ventilation box (102) communicating with the atmosphere and located in line with the distal end (101D) of the ventilation duct (101).

3. 2. The device according to claim 1, characterized in that the at least one gas sensor (103) is installed inside the ventilation duct (101) at a predetermined position between the proximal end (101C) and the distal end (101D).

4. 2. The device according to claim 1, characterized in that said at least one gas sensor (103) is installed inside said manhole (P).

5. 3. The device according to claim 2, characterized in that said at least one gas sensor (103) is installed inside said ventilation box (102).

6. The device according to claims 1 and 2, characterized in that the electronic processing control unit (3) and the transceiver device (4) are associated with a system (1) supported by a pillar (7), the ventilation box (102) is further associated with and supported by the pillar (7), and the ventilation duct (101) is inserted into the pillar (7) at least over a length (101B) included between the base and the ventilation box (102).

7. 3. The device according to claim 2, characterized in that the ventilation box (102) has a shape that prevents rain from entering through an opening (105) by means of which the ventilation box (102) communicates with the outside, and a grille (104) is provided in the area of ​​the opening (105) to prevent animals, leaves and / or debris from entering the ventilation box (102).

8. A device according to any one of claims 1 to 7, characterised in that it is provided with a self-moving fan (106) located at the top of the ventilation box (102) and capable of increasing the air extraction flow rate from the manhole (P) through the ventilation duct (101).

9. A device according to any one of claims 1 to 8, characterised in that there is provided an electric fan arranged inside the ventilation box (102) operable according to an input of the electronic processing control unit (3) and capable of increasing the air flow rate extracted from the manhole (P) through the ventilation duct (101).

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