WO2004059206A1

WO2004059206A1 - Method of fluid transfer

Info

Publication number: WO2004059206A1
Application number: PCT/GB2003/005685
Authority: WO
Inventors: Sigurd Gaard; Odd Tore Isaksen; Tore Arnesen; Emil Edwin
Original assignee: Statoil Asa; Cockbain, Julian
Priority date: 2002-12-31
Filing date: 2003-12-31
Publication date: 2004-07-15
Also published as: AU2003290357A1; GB0230343D0

Abstract

The invention provides a method of fluid transfer comprising causing a fluid to flow through a conduit, characterized in that carbon fibres are added to said fluid.

Description

Method of fluid transfer

This invention relates to a method of enhancing fluid flow, e.g. in pipelines, more particularly to a method of reducing friction or drag, and so reducing the power required to cause fluid flow, by inclusion within the fluid of carbon fibres.

It has long been known that the interaction of hydrocarbon gas and metal surfaces can give rise to dehydrogenation and the growth of carbon "whiskers" on the metal surface. More recently it has been found that such carbon whiskers, which are hollow carbon fibres having a diameter of about 3 to 100 nm and a length of about 0.1 to 1000 μm, have interesting and potentially useful properties, e.g. the ability to act as reservoirs for hydrogen storage (see for example Chambers et al . in J. Phys. Chem. B 102: 4253-4256 (1998) and Fan et al . in Carbon 37: 1649-1652 (1999)).

Several researchers have thus sought to produce carbon nanofibres (CNF) and to investigate their structure, properties and potential uses and such work is described in a review article by De Jong et al in Catal. Rev. - Sci . Eng. 42: 481-510 (2000).

As described by De Jong et al . (supra) and in a further review article by Rodriguez in J. Mater. Res. 8: 3233-3250 (1993) , transition metals such as iron, cobalt, nickel, chromium, vanadium and molybdenum, and their alloys, catalyse the production of CNF from gases such as methane, carbon monoxide, synthesis gas (i.e. H₂/CO) , ethyne and ethene. In this reaction, such metals may take the form of flat surfaces, of microparticles (having typical sizes of about 100 nm) or of nanoparticles (typically 10-50 nm in size) supported on an inert carrier material, e.g. silica or alumina. The metal of the catalyst must be one which can dissolve carbon or form a carbide . We have now found that carbon fibres and in particular CNF may advantageously be used as an additive to fluids which are to be transported by being flowed, e.g. pumped, through a conduit, typically a pipeline.

Thus viewed from one aspect the invention provides a method of fluid transfer comprising causing a fluid to flow through a conduit, characterized in that carbon fibres, in particular CNF, are added to said fluid.

The fluid transferred by the method of the invention may be a liquid or a gas but especially preferably is a gas, more especially a dense gas, i.e. a gas at a pressure higher than the cricondenbar (the pressure threshold above which gas and liquid do not coexist as separate phases) . The material constituting the fluid may be any substance capable of existing in a fluid state but especially preferably it comprises a hydrocarbon, more especially a

hydrocarbon, particularly methane, ethane, ethene, propane, propylene, butane, butene or pentane.

In an especially preferred embodiment, the fluid comprises methane, e.g. it may be the methane-containing material commonly referred to as natural gas .

The carbon fibre introduced into the fluid according to the invention is preferably carbon nanofibre . This may be produced as described above or as described for example in International Patent Application Publication No. WO 03/097910.

The carbon fibre will typically be introduced into the fluid at a concentration by weight of 0.05 to 1000 ppm, preferably 0.5 to 500 ppm, especially 1 to 100 ppm. The fibres may be injected into the fluid or may be premixed with a fluid, e.g. a fluid of the same chemical composition as that which is to be transferred or of a compatible, miscible composition.

Introduction of the carbon fibre may occur at a single site or at multiple sites along the conduit, which will typically be a pipeline. The carbon fibre may be removed from the fluid by any conventional procedure suitable for removing dust or particulates from a fluid, e.g. by centrifuging or filtering the fluid or by passing the fluid through a cyclone separator. Recovered carbon fibres may if desired be recycled for reuse in a method according to the invention. Alternatively they may be used in any of the other available uses for carbon fibre, e.g. as additives to polymer compositions. The carbon fibre used in the method of the invention moreover is preferably produced at a hydrocarbon source, e.g. an oil or gas well or at a site served by an oil or gas pipeline from such a well.

Thus in a particularly preferred embodiment of the invention a portion of hydrocarbon from a hydrocarbon source is diverted for the production of CNF while some or all of the CNF produced is added to some or all of the remaining hydrocarbon to facilitate the pumping of that hydrocarbon down a pipeline to a separate location.

Viewed from a further aspect the invention provides an apparatus for transferring fluid, said apparatus comprising a fluid transfer pipe, a pump to transfer fluid along said pipe, a carbon fibre inlet for introducing carbon fibres into said pipe and a particle separator for removing carbon fibre from fluid that has been transferred along said pipe.

The use of carbon fibre in this way not only reduces energy loss through friction or drag in the pumping of a hydrocarbon fluid but also serves to adsorb undesired components of the fluid, in particular hydrogen sulphide .

The invention will now be described further with reference to the following non-limiting Examples and the accompanying drawing in which:

Figure 1 is a schematic diagram of an apparatus according to the invention.

Referring to Figure 1 there is shown an apparatus 1 comprising a pipeline 2 for conveying fluid provided at an upstream zone thereof with an inlet 3 for introduction of carbon fibres and a pump 4, and at a downstream zone thereof a separator 5 for the removal of carbon fibres through outlet 6.

Example 1

CNF Production

Carbon containing gas (90%.mol methane and 10% mol hydrogen) at a pressure of 5 bar was introduced at a flow rate of 400 m /minute and a temperature of 550°C into a horizontal tubular reactor having a conical section increasing in cross-section in the flow direction. Before the reaction began, 0.3g of a aluminium-leached nickel : aluminium intermetal catalyst (Amperkat^® SK Ni 100 from H.C. Starck GmbH & Co KG, Goslar, Germany) was placed at the narrowest point of the reactor. The gas flow was maintained for 30 hours by which time CNF generation had ceased.

Example 2

CNF Production

Carbon containing gas (90% mol methane and 10% mol hydrogen) at a pressure of 5 bar was introduced at a flow rate of 400 mL/minute and a temperature of 550°C into a horizontal tubular reactor having a conical section increasing in cross-section in the flow direction. Before the reaction . began, 0.3g of a aluminium-leached 68% Nickel/32% Iron: aluminium intermetal catalyst (Amperkat^® SK Ni Fe 68 from H.C. Starck GmbH & Co KG, Goslar, Germany) was placed at the narrowest point of the reactor. The gas flow was maintained for 30 hours by which time CNF generation had ceased.

Claims

Claims:

1. A method of fluid transfer comprising causing a fluid to flow through a conduit, characterized in that carbon fibres are added to said fluid.

2. A method as claimed in claim 1 wherein said carbon fibres are carbon nanofibres (CNF) .

3. A method as claimed in either one of claims 1 and 2 wherein said conduit is a pipeline.

4. A method as claimed in any one of the preceding claims wherein said fluid is a dense gas.

5. A method as claimed in any one of the preceding claims wherein said fluid is a hydrocarbon.

6. A method as claimed in any one of the preceding claims wherein said fluid is natural gas.

7. A method as claimed in any one of the preceding claims wherein said carbon fibre is introduced into the fluid at a concentration by weight of 0.5 to 500 ppm.

8. A method as claimed in any one of the preceding claims wherein said carbon fibre is produced at a hydrocarbon source .

9. An apparatus for transferring fluid, said apparatus comprising a fluid transfer pipe, a pump to transfer fluid along said pipe, a carbon fibre inlet for introducing carbon fibres into said pipe and a particle separator for removing carbon fibre from fluid that has been transferred along said pipe.