MULTISPHERICAL SUBSEA ENCLOSURES

Abstract

A watertight enclosure for the underwater confinement of a device includes a set of ellipsoidal modules juxtaposed in a watertight manner and internally delimiting at least one volume receiving the device. It has been found that producing a watertight enclosure by means of juxtaposed ellipsoidal modules enables a total weight saving of the order of one third compared to a cylindrical envelope.

Description

BACKGROUND OF THE INVENTION

Embodiments of the present invention is generally concerned with watertight enclosures for the underwater confinement of various types of device.

Some types of industry, for example in the field of gas or petroleum exploitation, necessitate the immersion at very great depths of electrical or electromechanical devices.

Such industries for example necessitate the immersion at great depths of electrosubmersible pumps (ESP) together with their electrical power supply system.

In this type of application the depths reached can reach or even exceed 3,000 metres.

The immersed devices are generally placed in a watertight envelope in order to protect their internal components from seawater.

To protect the devices against pressure, two principal designs exist for the production of a confinement enclosure.

In accordance with a first type of design, the enclosure is filled with a liquid that is not electrically conductive, generally dielectric oil, in pressure balance with the sea. The equipment placed in the enclosure is then subjected to the immersion pressure and must furthermore be compatible with the oil. As the pressure is balanced, the walls of the enclosure are not subjected to stress linked to the pressure and therefore do not need to be made with a thickness increasing with the immersion depth.

In accordance with the second type of design, the enclosure is filled with a gas (air, nitrogen, . . . ) at low pressure, generally close to atmospheric pressure. The walls of the enclosure are sized to resist the immersion pressure. The equipment is then installed under conditions similar to those of industrial use.

Embodiments of the present invention relates to the second type of enclosure, known as an “atmospheric pressure” enclosure.

Clearly, the thickness of the enclosure must increase as the immersion depth increases, as a function of the pressure it has to withstand.

The watertight enclosures for the underwater confinement of a device are generally based on a cylindrical envelope comprising two end domes.

For example, for an immersion depth of approximately 3,000 metres the thickness of the cylindrical envelope can reach 80 mm with the result that, for an envelope having a length of 7 m and an inside diameter of 2 m, the total mass of the envelope including the equipment that it contains can reach or even exceed 40 tons, which necessitates powerful lifting means.

There also exist spherical envelopes which, because of their shape, make it possible to reduce considerably the thickness of the material entering into the constitution of the envelope.

Although the production of a spherical envelope makes it possible to save weight, it has been found that this type of design has major disadvantages in terms of integration in that, compared to a cylinder, a sphere increases the footprint and therefore leads to a larger and heavier supporting structure.

BRIEF DESCRIPTION OF THE INVENTION

Given the foregoing, there is proposed a watertight enclosure that is relatively easy to manufacture but of lower weight compared to cylindrical envelopes.

In accordance with a first aspect of the invention, there is proposed a watertight enclosure for the underwater confinement of a device, including a set of ellipsoidal modules juxtaposed in a watertight manner and internally delimiting at least one volume receiving the device.

It has been found that producing a watertight enclosure by means of juxtaposed ellipsoidal modules enables a total weight saving of the order of one third compared to a cylindrical envelope.

In one embodiment, the watertight enclosure includes a removable end module of hemispherical dome shape connected to said set of modules by a watertight flange.

In accordance with an aspect, the ellipsoidal modules are connected in pairs by cylindrical connectors.

These cylindrical connectors may have a thickness greater than that of the ellipsoidal modules.

In one embodiment, the cylindrical connectors are equipped with stiffener elements.

For example, these stiffeners are formed by a localized enlargement of the cylindrical connectors.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the invention will become apparent on reading the following description, given by way of nonlimiting example only and with reference to the appended figures, in which:

FIG. 1 is a profile view of a watertight enclosure; and

FIG. 2 is a partial sectional view of the enclosure from FIG. 1.

DETAILED DESCRIPTION

Refer first to FIG. 1, which shows the general architecture of a watertight enclosure, designated by the general reference number 1, for the underwater confinement of a device.

In this figure, the watertight enclosure is represented in a position assumed vertical.

In the application that is envisaged, this enclosure is intended to protect one or more immersed electrical or electromechanical devices, such as a variable speed drive, a low-voltage or high-voltage distribution unit, a power supply system with back-up, . . . Of course, it is not outside the scope of the invention for it to be intended to receive other types of device.

As seen in FIG. 1, the enclosure 1 includes a set of ellipsoidal modules 2, 3 and 4, here 3 in number, disposed in line with one another and connected in pairs by cylindrical portions 5, 6 and 7.

At each end the envelope includes a dome 8 of truncated sphere shape connected in watertight manner to one of the ellipsoidal modules and, at the opposite end, a hemispherical dome 9 connected to the other end ellipsoidal module 2.

The ellipsoidal modules and the end domes together delimit an internal volume filled with nitrogen at atmospheric pressure and intended to receive the device to be immersed. Of course, the number of modules is not limiting on the invention and may be chosen as a function of the overall size of the device.

In reality, each of the ellipsoidal modules has a flattened sphere shape and is more particularly formed by the spherical zone of a flattened sphere contained between two parallel planes such as P1 and P2.

Because of the production of the various modules with a partially spherical shape, the modules and the end domes 8 and 9 have a smaller thickness compared to the thickness of a cylindrical envelope necessary to withstand the immersion pressure. For example, for an immersion pressure that can reach 3,000 metres, the thickness of the spherical wall is therefore of the order of 50 mm.

Where the cylindrical connectors 5 and 6 are concerned, these have an increased thickness determined to provide the stiffness of the whole, for example of the order of 150 mm.

It will be noted that the diameter of the hemispherical dome 9 is less than the inside diameter of the cylindrical connectors 5, 6 and 7 and chosen so as to be greater than the greatest transverse dimension of the device so that after introduction of a device via the opening of the end ellipsoidal module 2 no problem can occur with insertion of the device into the rest of the enclosure.

The hemispherical dome 9 therefore in reality constitutes a removable element and is fixed to the hemispherical module 2 by means of a flange 10.

Finally it is seen in FIG. 1 that the cylindrical connectors 5, 6 and 7 may be provided with a stiffener, such as 11, produced in the form of a localised thickening of material. Such a stiffener 11 remains optional, however, and has been shown for only one of the cylindrical connectors.

Clearly, the watertight enclosure that has just been described, which uses a set of juxtaposed ellipsoidal modules, enables the thickness of the enclosure to be considerably reduced at the location of the ellipsoidal modules. The weight saving can therefore be as much as one third compared to cylindrical enclosures.

This written description uses examples to disclose the invention, including the preferred embodiments, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. A watertight enclosure for the underwater confinement of a device, comprising: a set of ellipsoidal modules juxtaposed in a watertight manner and internally delimiting at least one volume receiving the device.

2. The watertight enclosure according to claim 1, including a removable end module of hemispherical dome shape connected to said set of modules by a watertight flange.

3. The watertight enclosure according to claim 1, wherein the ellipsoidal modules are connected in pairs by cylindrical connectors.

4. The watertight enclosure according to claim 3, wherein the cylindrical connectors have a thickness greater than that of the ellipsoidal modules.

5. The watertight enclosure according to claim 3, wherein the cylindrical connectors are equipped with stiffener elements.

6. The watertight enclosure according to claim 5, wherein the stiffeners are formed by a localized enlargement of the cylindrical connectors.