METHOD AND AN APPARATUS FOR OBTAINING ENERGY BY EXPANDING A GAS AT A WELLHEAD
First Claim
1. An apparatus (100,300) for reducing the pressure of a natural gas (2) available at an extraction pressure (P1) at a wellhead of a natural gas field, said apparatus (100) comprising:
- an energy recovery expansion device (8,20) for expanding said natural gas until a use pressure (P2) is reached, said energy recovery expansion device (20) having a rotor rotatably arranged about an own axis and a stator, and a gas passageway defined between said rotor and said stator;
an electric power generator (29) that is mechanically connected to said rotor of said energy recovery expansion device (20), so that said electric power generator (29) generates an electric power (W) when a stream of said natural gas is conveyed in said passageway of said energy recovery expansion device (20) thus causing a rotation of said is rotor and causing the gas to expand;
an electric power extraction means for extracting said electric power (W) generated by said electric power generator (29),characterised in that said apparatus comprises a treatment means, upstream of said energy recovery expansion device (8,20), said treatment means comprising;
a solid and/or liquid separation means (11) for separating a solid and/or a liquid fraction that is present in said natural gas (2), anda gas-conditioning means (7) that is adapted to prevent a formation of a solid during said expansion in said rotor,such that said natural gas (2) is turned into a treated gas (3).
1 Assignment
0 Petitions
Accused Products
Abstract
A method and an apparatus (100) for reducing the pressure of a natural gas (2) at a wellhead of a natural gas field. The method provides prearranging an energy recovery expansion device (20), which comprises a stator and a rotor mechanically connected with a power generator (29), and a gas passageway between the rotor and the stator, and conveying the natural gas into the passageway of the energy recovery expansion device (24) to cause a rotation of the rotor and the expansion of the gas, the pressure being reduced from the extraction pressure (P1) to the use pressure (P2), which makes it possible to obtain an electric power (W) during the expansion, adapted to satisfy the energy requirements of the gas extraction unit, in particular of an offshore platform, without installing local electric generators. In order to allow a reliable operation of a recovery expansion device, such as a turbine, a means is provided for finely separating solid and liquid matter present in the gas, as well as a means (7) for conditioning the gas entering the expansion device, which may comprise a feeding means (12) of an additive into the gas (3), said additive adapted to decrease the formation temperature of the solid, and, in an advantageous way in case of higher amount of water, a means for heating the gas such that the temperature is maintained above the formation temperature of the solid.
12 Citations
20 Claims
-
1. An apparatus (100,300) for reducing the pressure of a natural gas (2) available at an extraction pressure (P1) at a wellhead of a natural gas field, said apparatus (100) comprising:
-
an energy recovery expansion device (8,20) for expanding said natural gas until a use pressure (P2) is reached, said energy recovery expansion device (20) having a rotor rotatably arranged about an own axis and a stator, and a gas passageway defined between said rotor and said stator; an electric power generator (29) that is mechanically connected to said rotor of said energy recovery expansion device (20), so that said electric power generator (29) generates an electric power (W) when a stream of said natural gas is conveyed in said passageway of said energy recovery expansion device (20) thus causing a rotation of said is rotor and causing the gas to expand; an electric power extraction means for extracting said electric power (W) generated by said electric power generator (29), characterised in that said apparatus comprises a treatment means, upstream of said energy recovery expansion device (8,20), said treatment means comprising; a solid and/or liquid separation means (11) for separating a solid and/or a liquid fraction that is present in said natural gas (2), and a gas-conditioning means (7) that is adapted to prevent a formation of a solid during said expansion in said rotor, such that said natural gas (2) is turned into a treated gas (3). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. A method for reducing the pressure of a natural gas (2) available at an extraction pressure (P1) at a wellhead of a natural gas field, comprising the steps of:
-
prearranging an energy recovery expansion device (20) suitable for expanding said natural gas until a use pressure (P2) is reached, said energy recovery expansion device (20) having a rotor rotatably arranged about an own axis and a stator, and a gas passageway defined between said rotor and said stator; connecting an electric power generator (29) to said rotor of said energy recovery expansion device (20), so that a rotation of said rotor causes an electric power generation (W) by said generator (29); conveying a stream of said natural gas in said passageway of said energy recovery expansion device (20) in such a way to cause a rotation of said rotor and to cause said expansion, the pressure of said gas decreasing from said extraction pressure (P1) to said use pressure (P2); extracting said electric power (W) that is generated by said generator (29) as a consequence of said rotation of said rotor, characterised in that treatment steps are provided, for said natural gas (2) before said step of conveying, which comprise steps of; separating solids and/or liquids, in particular water, which are present in said natural gas (2), and conditioning said natural gas (2) in order to prevent a formation of a solid during said expansion in said energy recovery expansion device (20), turning said natural gas (2) into a treated gas (3). - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
-
Specification