WO2015040476A2

WO2015040476A2 - Mechatronic actuator for the automatic management of subsea valves

Info

Publication number: WO2015040476A2
Application number: PCT/IB2014/001873
Authority: WO
Inventors: Tiziano CAZZOLA
Original assignee: Petrolvalves S.R.L.
Priority date: 2013-09-19
Filing date: 2014-09-18
Publication date: 2015-03-26
Also published as: MX2016003434A; BR112016006051A2; WO2015040476A3; ITBG20130032U1

Abstract

Mechatronic actuator for the operation of subsea valves, comprising a set of electronic components immersed in a bath of dielectric oil, an elastic compensator and a related breather, designed to equalize the external hydraulic pressure, present in the vicinity of the seabed, with the one inside the actuator itself. The equalization of the hydraulic pressure allows the mechatronic actuator to operate on seabeds at depths of up to three thousand metres without damage.

Description

TITLE

MECHATRONIC ACTUATOR FOR THE AUTOMATIC MANAGEMENT OF SUBSEA VALVES. DESCRIPTION

This invention refers to a mechatronic actuator for the control of subsea valves, built with special devices, capable of operating the latter using specific management software.

The valve is a mechanical component that allows intercepting or regulating the flow of a material capable of flowing through a pipe in order to ensure specific pressure or flow rate values.

In the great majority of cases this material is of fluid type, i.e. in a liquid or gaseous state; it is possible, however, to create a flow of solids, e.g. powdery or granular ones, which can be intercepted or regulated by a valve.

As a trivial example, the traditional home tap is a valve, as is also the case to extend the concept - for the air vents found in many windows, usually made up of adjustable strips of glass.

The valves are normally made up of three basic elements, namely:

- a body, which contains the movable member and allows the connection to the pipes within which the fluid flows and the connection to the control units;

- a shutter, which is the movable member, and which allows the interception of the fluid;

- control units, which may be manual, electric or magnetic, by means of which the movable member is manoeuvred. Then there are several criteria for the classification of valves: by design shape (e.g. ball, butterfly, gate valves), by type of operation (e.g. manually operated, driven by actuators with electric, pneumatic and hydraulic control) and by application (e.g. as regulating and shut-off valves).

Particular care and attention is paid to the design of subsea valves for the "oil & gas" industry, in both "on-shore" and "off-shore" oil platforms.

The subsea valve is a complex component of fundamental importance to the oil platform.

Italy is generally recognized as the leading country in the world production of subsea valves for the "oil & gas" industry.

The companies in the sector still hold a high-level "know-how", which guarantees them huge advantages in terms of competition.

At the state of the art, the management of subsea valves for oil platforms is often carried out through the use of hydraulic actuators, in which the movement of the shutter is determined by the hydraulic energy of the fluid flowing through the pipeline. This solution, however, results in limited operativeness , ending in lack of flexibility and manageability of the entire system. Hydraulic actuators, at the state of the well-known technology, also pose overt issues in the event of falls in hydraulic pressure.

Another widely practiced management method involves drives with electrical servo controls (actuators), in which the shutter movement, whether linear or rotational, is caused by a "brushless" type electric motor. This solution is more used than the previous one, as it makes possible a greater selectivity in the regulation of flows within the pipeline, as well as greater efficiency of the entire system. Moreover, the "brushless" motor, unlike the classic brush motor, has a longer working life and a greater precision of intervention, despite involving higher costs. In this case the control of the actuator takes place remotely, through a dedicated electromechanical system, which optimizes the operativeness thereof . Therefore, what is refereed to as a mechatronic actuator is actually a "smart" device, intended for specific applications, which combines the three distinct disciplines, namely: mechanics, electronics and computer science. These technological expedients, although able to meet the majority of the complex demands of clients, present some criticalities.

Some International Research Centres point out that over the next decade oil and its derivatives will be playing a fundamental role as reference fuel just as they have been playing so far. For this reason, oil companies continue to dig new wells, especially out at sea ("off-shore"). Huge deposits have actually been detected in the seabed. As the depth increases, however, the pressure the components of the systems are subjected to - as for instance the above mentioned subsea valves and mechatronic actuators - increases accordingly. For this reason, it becomes necessary to use a very powerful hyperbaric chamber, so as to be allowed to test all products. The hyperbaric chamber is actually able to simulate the conditions that occur at a depth of 4,500 metres, when the pressure reaches 450 bar. During this test, the entire management of the pressurization system is then entrusted to a software capable of analyzing and storing the data coming from the sensors distributed inside the hyperbaric chamber and in the analyzed components (valve, actuator, cables, joints, etc.). Not only does the automatic collection of all test conditions, as well as of the results recorded, allow creating a series of test procedures, to be reused also in the future, but it also allows recording all relevant data to ensure a complete traceability of the products tested.

The high pressure found at significant sea depths, therefore, requires attention at the design stage, particularly with regard to the materials used and to their operational reliability.

It is precisely because of the high pressure that the electronic components located inside the mechatronic actuators of control-valve are compulsorily almost complete^'-y placed under vacuum, using inert gas, typically nitrogen (normally at about 0.02 bar); this results, therefore, in such a considerable pressure difference between the inside and the outside as to increase the risk of damage. Placing the electronics under vacuum also partially solves the problem of strong vibrations and shocks that are created under certain operational circumstances.

Any electrical connections inside the actuators are a source of problems too, as they should be placed under vacuum or, alternatively, directly withstand the high pressure, through the inclusion of appropriate connector joints. Connector joints are, among other things, for obvious reasons, very expensive.

In order to adopt the expedients mentioned above you inevitably end up having to deal with an increase in the overall dimensions and weight of the equipment. Another issue not to be overlooked is represented by the SIL index (Safety Integrity Level), defined by European standards 61508 and 61511 , of the International Electrotechnical Commission (I EC), as a "relative level of functional risk-reduction". The SIL represents, in this specific case, the calculation of the probabilities that certain products (valve and actuator) can not be damaged within a certain time (probability of failure-per-hour "pfh"). Therefore, the greater the SIL index, from a minimum of SIL 1 to a maximum of SIL 4, the lower the failure rate.

The purpose of the present invention is to define a mechatronic actuator that allows a controlled and automatic management of subsea valves, of different types, through the adoption of specific software, particularly for "on-shore" and "off-shore " marine platforms, typical of the oil industry.

Another purpose is to define an actuator that can operate together with the valves, at marine depths of up to 3,000 metres and at an equalized pressure of 300 bar, without damage.

Another purpose is to define a part of the actuator, comprising the electronics, suitable to be offset with respect to the external pressure up to 300 bar.

Another purpose is to define an actuator as above that, with appropriate hardware and software, makes the system more usable and adaptable to different needs.

Another purpose is to define an actuator as above, which allows operating in the absence of electrical voltage, through the appropriate insertion of a back- up battery and the related battery-charger, essential in cases of failure and black-out.

Another purpose is to define an actuator that allows ensuring the monitoring, diagnostics, and advanced management of the subsea valves.

Another purpose is to define an actuator as above, remotely manageable. Another purpose is to define an actuator as above that may have a reduced overall dimensions and less weight.

Another purpose is to define an actuator as above that allows a significant reduction in instr!lation costs.

Another purpose is to define an actuator that allows reaching a high efficiency in terms of energy consumption, through the optimization of the electrical power absorbed.

Another purpose is to define an actuator that allows achieving a high safety standard, by means of the Overall Risk Mitigation (valve and actuator).

Another purpose is to define an actuator as above that enables fulfilling the regulatory requirements with respect to valves-actuators, as mentioned in the introduction.

Another purpose is to define an actuator that proves feasible at reasonable prices.

These and other purposes will appear as achieved by reading the following detailed description, which illustrates a mechatronic actuator for the automatic management of subsea valves.

The invention is illustrated, by way of example but in no way being limited thereto, in the following description and drawing tables, of which: Fig. 1 shows an axonometric view of a mechatronic actuator for a subsea valve .

Fig . 2 shows an axonometric view with a partial cross-section of the inside of the mechatronic actuator.

Fig. 3 shows a front view of the mechatronic actuator.

Fig. 4 shows a side view of the mechatronic actuator.

Fig. 5 shows a partial cutaway front view of the mechatronic actuator.

Fig. 6 shows a side view of a planetary gear unit.

Fig. 7 shows a cutaway front view of the planetary gear unit.

Fig . 8 shows elastic compensator an axonometric view of an elastic compensator.

Fig . 9 shows elastic compensator a cutaway view of the elastic compensator.

Fig. 1 0 shows an axonometric view of the mechatronic actuator, coupled to a "ball" type subsea valve.

Fig. 1 1 shows an axonometric view of the mechatronic actuator, coupled to a "check" type subsea valve.

Fig. 1 2 shows an axonometric view of the mechatronic actuator, coupled to a "gate" type subsea valve.

Fig. 1 3 shows an axonometric view of the mechatronic actuator, coupled to a "double gate" type subsea valve.

With reference to the figures listed above, a mechatronic actuator 1 consists of a lower section 2, a central section 3 and an upper section 4, all typically made of steel. The lower section 2, the middle section 3 and the upper section 4 of the actuator 1 are firmly fastened together by means of suitable stainless steel bolts and the related sealing gaskets. The lower section 2 includes a circular valve coupling flange 5, with the related male anchoring plates 6 and a female frame housing 7 for coupling with a male input shaft of a generic subsea valve . If necessary, there are several flanges available for various valve couplings. The actuator 1 also includes grips 8 for handling. The upper section 4 is provided with two external couplings to connector 9, for the input of electrical power and control cables.

The actuator 1 has a small service hydraulic outlet 10, for filling a volume 38 of approximately twenty litres, of the upper section 4, with dielectric oil 39. The dielectric oil 39 is used for compensating the outer pressure with the inner one. The upper section 4 houses a breather 11 with the purpose of stabilizing the operating pressure of the volume 38 with the external marine pressure.

In order to allow the storage and handling of the actuator 1 the intervention of a one-way safety valve 12, calibrated at about three point five bars, is planned for the purpose of expelling the excess pressure from volume 38, due, for example, to a rise in the ambient temperature.

The actuator 1 is provided, within the area of the central section 3, of a reduction gear unit 13, preferably made up of a cascade of planetary gears, driven through a rotary motion by a motor shaft 14 of an electric motor 15. The motor shaft 14 is coupled to the input pin of the reduction gear unit 13 through insertion within a female housing 17, the latter being suitably equipped with usual systems fitted to allow the transmission of the torque, allowing the removability of the junction and the related axial movement; in order to properly decrease the number of revolutions of an output shaft 16 of the reduction gear unit 13, the axial motion passes through a series of trains of planetary gears 18. The reduction gea r u n it 1 3 , is equipped with male pins 19 for fixing to a ju nction base 20 of the lower section 2 of the actuator 1 , as well as with female threaded holes 21 for fixing to a junction base 22 of the electric motor 15. Also inside the area of the central section 3, a shock absorber with elastic meshes 23 is inserted, interposed between the electric motor 15 and an electronic component 24. The shock absorber with elastic meshes 23, made of stainless steel, has the function to protect the electronic components 24, absorbing any shocks and vibrations that may arise during the operation. The shock absorber with elastic meshes 23 is capable of dampening down and deflecting more than forty percent of the frequencies of stress, coming from any direction, included between five and twenty five Hertz.

For the compensation of the electronics, it is necessary to use electronic components 24 of "solid state" type, i.e. consisting of components free from inner air pockets.

The electronic components 24 consist of a motherboard 25, a power board 26, a control board 27, and a drive board 28, said boards being inserted within the area of the upper section 4 of the actuator 1 .

As mentioned above, as for the breather 11 , there is a very important element, acting in cooperation with the breather itself, consisting of an elastic com pensator 29 (shown in Figs. 2 and 5 and in more detail in Figs. 8 and 9). The elastic compensator 29, together with the breather 11 , has the function of equalizing the external pressure, present in the sea depths, with the internal one of the upper section 4, in which the electronic components 24 are housed. The elastic compensator 29, is basically made of stainless steel material, of suitable thickness, with a volume 30 of about two litres, a circular base 31 ', a circular locking ca p 31 ", a collar joint band 32 , suitable for locking an elastic membrane 33 (preferably made of polytetrafluoroethylene) by means of suitable clamping bolts 34. For fastening the elastic membrane 33 to the circular base 3 V and to the circu lar locking cap 31 ", a nitrile rubber sealing gasket 35, with suitable mechanical resistance to permanent deformation and good water and oil tightness is interposed. The aforementioned breather 11 , also made of stainless steel material, is positioned upon the surface of the circu lar locking cap 31 "; it is manufactured according to technologies well-known in the sector, and consists, for example, of a cylindrical body 36, possibly divided into a lower chamber 37', and an upper chamber 37". The body 36, that is the aforesaid chambers 37' and 37", are connected with the outside of the actuator 1 by means of openings 40; in this way, the pressure in the seabed spreads within the volume 30, inside the membrane 33, thereby causing the expansion of the latter and the simultaneous contraction of the combined volume 38, leading to the equalization between the two (pressure 38 = pressure 30 = sea pressure). The aforementioned openings 40 are located upon a circular copper plate 43 , retained in the operating position by a polytetrafluoroethylene bushing (PTF E) . The plate 43 is made of copper in order to better avoid any phenomena of marine fouling, such as for example, calcareous sediments and mucilage.

Figu res 1 0 , 11 , 1 2 a nd 1 3 show the various types of subsea valves most commonly used in the petrochemical industry, respectively; in particular, amongst the ones represented therein please note the presence of the actuator 1 coupled to a valve of the "ball valve" type 44, to a valve of the "check valve" type 45, to a valve of the "gate valve" type 46, and finally to a valve of the "double gate valve" type 47.

The electronic components 24 as described above allow embedding devices capable of operating remote communications via a common "bus" cable, so as to avoid the onerous task of laying a large number of cables and the related joints in the sea depths, as required instead by certain installation solutions at the State of the Art.

A remote hardware and software system, to be specially prepared, can allow you to monitor, trace the amounts of fluids in transit through the opening modulation of the valves, conduct diagnoses and statistics, or manage the functions of the actuator 1 , and consequently the related su bsea valves (44, 45, 46 , 47). A remote management software system makes therefore the present invention widely usable and adaptable to the most varied needs. Moreover, the realization of the mechatronic actuator also allows:

- Obtaining an International Declaration of Conformity with regard to the Electro-Magnetic Compatibility (EMC);

- Achieving, by adopting appropriate quality standards in relation to the materials used and the construction procedures, a high level of reliability, documentable, if necessary, through a SIL certification 2, even in high testing mode (HDM);

- Obtaining, consequently, a certification at the highest international levels (e.g. in compliance with the standards set out by "Lloyd's Register" for marine related applications).

Claims

Claim 1 : Actuator (1 ) of rnechatronic type for the management of subsea valves having a bottom section (2), a central section (3) and an upper section (4), characterized in that it comprises within a volume (38) of said upper section (4) a set of electronic components (24) of a type capable of withstanding high pressures, in a bath of dielectric oil (39), an elastic compensator (29) and a related breather (11 ), the elastic compensator (29) and the breather (11 ) being able to equalize the hydraulic pressure present in the vicinity of the seabed with that of the volume (38) of the upper section (4).

Claim 2: Actuator (1 ), as per previous claim, characterized in that it includes a shock absorber with elastic meshes (23), interposed between an electric motor ( 1 5) and the set of electronic components (24) , capable of protecting said electronic components (24) absorbing any shocks and vibrations that may arise during the operation of the actuator (1 ) a damper elastic meshes (23), interposed between an electric motor (15) and the electronic components (24), able to protect said electronic components (24) absorbing shocks and vibrations that may arise during operation of the actuator (1 ).

Claim 3: Actuator ( 1 ), as per previous claims, characterized in that the electronic components (24 ) are of "solid state" type, i.e. free from inner air pockets.

Claim 4: Actuator ( 1 ), as per previous claims, characterized in that the elastic compensator (29) comprises a volume (30 ) of approximately two litres, a circular base (31' ), a circular locking cap (31"), a collar joint band (32) suitable to lock an elastic membrane (33), preferably made of a polytetrafluoroethylene material and shaped as extensible bellows, by means of suitable clamping bolts (34) to the circular base (31') and to the circular locking cap (31"), with interposed nitrile rubber sealing gaskets (35) with suitable mechanical resistance to permanent deformation, designed to provide a good water and oil tightness.

Claim 5: Actuator (1), as per previous claims, the breather (11), also made of stainless steel material, comprises a cylindrical body (36), possibly divided into a lower chamber (37') and an upper chamber (37"), characterized in that said chambers (37', 37") are placed in connection with the outside of the actuator (1) by means of openings (40), so that the pressure in the seabed spreads within the volume (30), inside the membrane (33), causing the expansion of the latter and the simultaneous contraction of the combined volume (38), leading to the equalization between the two, or pressure (38) equal to pressure (30; equal to sea pressure; the aforementioned openings (40) are located upon a circular copper plate (43), retained in the operating position by a polytetrafluoroethylene bushing (42).

Claim 6: Actuator (1), as per previous claims, characterized in that it includes, in the lower section (2), a circular valve coupling flange (5), with the related male anchoring plates (6), and a female frame housing (7), for coupling with a male input shaft of a generic subsea valve.

Claim 7: Actuator (1), as per previous claims, characterized in that it includes, in the central section (3), a reduction gear unit (13) driven through a rotary motion by a shaft (14) of an electric motor (15), referred to as shaft (14) of the electric motor (15) being interposed within a female housing (17), with the purpose of decreasing through trains of planetary gears (18) the number of revolutions of a shaft (16) of the reduction gear unit itself (13).

Claim 8: Actuator (1), as per previous claims, characterized in that it include, in the upper section (4), two external connector joints

(9), useful for the entry of electric cables, a safety valve (12) for the expulsion of the pressure in excess in the volume (38), and a service hydraulic outlet

(10) for filling the volume (38) with dielectric oil (39),

Claim 9: Actuator (1), as per previous claims, characterized in that electronic components (24) include embedded devices capable of operating remote communications via a common "bus" cable, so as to avoid the onerous task of laying a large number of cables and the related joints in the sea depths.

Claim 10: Actuator (1), as per previous claim, characterized in that it adopts a remote hardware and software system capable of monitoring, conducing diagnoses and statistics, or managing the functions of the actuator (1), and consequently the related subsea valves (44, 45, 46, 47) relying on the maximum operational versatility.