Filter device, and method of assembly

1. A filter device comprising:

a common inlet manifold;

a common outlet manifold; and

at least two membrane filter units which are configured to be elongated, each of the at least two membrane filter units comprising:

an inlet opening for a fluid flow to be processed,

a first outlet opening for at least a retentate portion of the fluid flow, and

a second outlet opening for at least a remaining portion of the fluid flow,

wherein,

each inlet opening of each of the at least two membrane filter units is fluidly connected to the common inlet manifold, and

each first outlet opening of each of the at least two membrane filter units is fluidly connected to the common outlet manifold,

wherein,

at least one of the at least two membrane filter units is arranged at a first position along a longitudinal axis, at least another one of the at least two membrane filter units is arranged at a second position along the longitudinal axis, the two membrane filter units being staggered with respect to each other and not being axially aligned with respect to each other, and

the at least one of the at least two membrane filter units is fluidly connected to the common inlet manifold and to the common outlet manifold via a first set of conduits, and the at least another one of the at least two membrane filter unit is fluidly connected to the common inlet manifold and to the common outlet manifold via a second set of conduits.

2. The filter device as recited in claim 1 , wherein,

the first set of conduits comprises a first conduit and a second conduit, the first conduit being longer than the second conduit,

the second set of conduits comprises a first conduit and a second conduit, the first conduit being shorter than the second conduit, and

a total length of a flowpath of the first conduit and the second conduit of the first set of conduits, and a total length of a flowpath of the first conduit and the second conduit of the second set of conduits, is the same.

3. The filter device as recited in claim 1 , further comprising:

a structural connection device,

wherein,

the common inlet manifold and the common outlet manifold are structurally interconnected via the structural connection device so as to form a unitary membrane filter cartridge.

4. The filter device as recited in claim 3 , wherein the structural connection device comprises an interlocking member which is configured to provide a structural integrity and to lock together the at least two membrane filter units, the common inlet manifold, and the common outlet manifold.

5. The filter device as recited in claim 4 , wherein the interlocking member is connected to the common inlet manifold and to the common outlet manifold.

6. The filter device as recited in claim 3 , further comprising:

a plurality of the unitary membrane filter cartridges;

an augmented inlet manifold; and

an augmented outlet manifold,

wherein,

the common inlet manifold of each of the plurality of the unitary membrane filter cartridges is connected to the augmented inlet manifold, and the common outlet manifold of each of the plurality of the unitary membrane filter cartridges is connected to the augmented outlet manifold, so as to form an augmented unitary membrane filter cartridge.

7. The filter device as recited in claim 6 , further comprising:

a first pressure vessel part,

wherein,

the augmented unitary membrane filter cartridge comprises a connection which is configures so that augmented unitary membrane filter cartridge is connectable to and supportable by the first pressure vessel part as one single unit.

8. The filter device as recited in claim 6 , wherein the unitary membrane filter cartridge and the augmented unitary membrane filter cartridge each form unitary, elongated, bodies around a common longitudinal axis.

9. The filter device as recited in claim 6 , wherein the unitary membrane filter cartridge and the augmented unitary membrane filter cartridge each are configured to be inserted into a pressure-retaining device having a circular cross-section.

10. The filter device as recited in claim 9 , wherein the pressure-retaining device is a pressure vessel or a pipe.

11. The filter device as recited in claim 3 , further comprising:

a plurality of the unitary membrane filter cartridges;

wherein,

the plurality of the unitary membrane filter cartridges are fluidly and structurally interconnected in an end-to-end relationship so as to form a cartridge string.

12. A membrane filter unit comprising,

the filter device as recited in claim 1 ; and

a pressure vessel comprising an inlet port, an outlet port, and an opening through which a filtered fluid is passable,

wherein,

the filter device is arranged in the pressure vessel, and

the filter device is fluidly connected to the inlet port and to the outlet port of the pressure vessel.

13. A method of using the filter device as recited in claim 6 at a subsea location, the method comprising:

arranging at least one unitary membrane filter cartridge or at least one augmented unitary membrane filter cartridge as recited in claim 6 in a pipe or in a pressure vessel at the subsea location;

flowing a hydrocarbon fluid into an inlet opening of the filter device; and

flowing the retentate out of an outlet opening of the filter device.

14. The method of using as recited in claim 13 , further comprising:

arranging the filter device on the seabed location in a substantially vertical upright orientation or in a substantially horizontal orientation.

15. A method of installing a plurality of membrane filter units into a pressure vessel, the method comprising:

forming at least one unitary membrane filter cartridge or at least one augmented unitary membrane filter cartridge as recited in claim 6 ; and

inserting the at least one unitary membrane filter cartridge or the at least one augmented unitary membrane filter cartridge into the pressure vessel as one integral unit.

16. The method as recited in claim 15 , wherein, prior to the inserting, the method further comprises:

connecting the at least one unitary membrane filter cartridge to a first pressure vessel part,

wherein,

the at least one unitary membrane filter cartridge and the first pressure vessel part are configured to be handleable as a unit.