Title:
Procedure and apparatus for collection of free methane gas from the sea bottom
Kind Code:
A1


Abstract:
The present invention is referring to a procedure and an apparatus for collection of free methane gas from the sea bottom, destined to collect and liquefy the methane gas liberated from metastabile deposits of hydrate methane situated on the seas or oceans bottom. The procedure, in a first version of realization, according to the invention, includes the collection of free methane gas from the sea bottom in a mixture with the sea water and directing this mixture up wards to the surface, where is taking place a gravitational distribution of it on a big surface, for permitting the methane gas to separate from water. The humid captured methane gas is cooled to produce the condensation of the last seawater fraction after, which is done its cooling to the required temperature for passing from the gaseous state into the liquid state.

The apparatus, in its first version of realization, according to the invention, is made from some guiding arms A on which is sitting an intermediary platform B, destined to support some electrical reversible trolleys D and E, used for the displacement on radial and vertically direction of some telescopic conduit 21 and of some collectors K, of some electrical reversible and double trolleys F for driving some separators L and of a flexible conduit 50 on radial direction, as well and of some electrical reversible and double trolleys G used for some lateral anchors 7 maneuver. On the vertical axis of apparatus is found a central anchor 5 stiffed by a hoist 4. The ends of arms A are provided with some propellers 8, 9, 10 and 11 for ensemble's rotation. On platform B and C are positioned a humidity extractor M from which the condense is eliminated, a gas methane liquefactor N and this is connected with a storage tank O. A nitrogen compressor 70 discharged the arrived nitrogen through laminate valve f towards a tank of liquid nitrogen P




Inventors:
Baciu, Petru (Woodside, NY, US)
Application Number:
10/712142
Publication Date:
04/07/2005
Filing Date:
11/14/2003
Assignee:
BACIU PETRU
Primary Class:
Other Classes:
95/241, 166/357
International Classes:
B01D19/00; B01D53/00; B01D53/26; B63B21/50; B63B35/44; E02F7/00; E21B43/01; E21B43/34; E21C45/00; (IPC1-7): E02F7/00
View Patent Images:
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Primary Examiner:
BOMAR, THOMAS S
Attorney, Agent or Firm:
PETRU BACIU (WOODSIDE, NY, US)
Claims:
1. Procedure for the collection of free methane gas from the sea bottom, characterized by means of that, in a first operation takes place the free methane collection from the sea bottom and it is directed up wards, to a running section of methane gas together with sea water and forms a mixture of methane gas and sea water. The displacement of mixture is being done under the form of a current tube until a room in which takes place the separation phase, in which the mixture overflows, at an inferior sea level, where the pressure is smaller then that from the sea bottom and where takes place a distribution/gravitational spreading of it on a big surface, on which the running is done at a lower pressure, to permit the separation of methane gas from water, the humid methane gas being collected at the superior part of the room, and the sea water freely running to an inferior level from where, in the following operation, is sucked and evacuated back in the sea to ensure the required level of difference for mixture's rising, and in the following operation the humid methane gas, captured at the superior part of the room, being sucked to an other room, where it is cooled to produce the condensation of last sea water fraction, operation after which is obtained sea water in liquid state, which is collected and then is evacuated and dry methane gas, in the following operation, proceeds to the cooling of this gas at a required temperature for it to pass in the liquid state.

2. Procedure for the collection of free methane gas from the sea bottom, in an other version of realization, characterized by means of that, in a first operation, the humid methane gas brought to the sea surface, is cooled in a room by bringing it in contact with cool methane gas and by mixing it with that, due to the temperature lowering takes place the condensation of the last fraction of sea water vapors and obtaining of the dry methane gas, the operation followed by its compression in a first step, up to a certain pressure and temperature, after which, in an other operation, is cooled at the seawater temperature, after which takes place a second step of compression followed by a new cooling at the sea water temperature and of the third step of compression, an a last operation the methane gas is discharged followed by this last compression and sent towards a room where, after the lamination followed by an adiabatic expansion passes from the gaseous phase into the liquid phase. In parallel with the above operation takes place an other process in which part from compressed methane gas in first step is taken for producing the suction of liquid methane obtained, according to the last operation, sucktion after which the compressed and warm methane gas from the first step of compression is mixed with the liquid methane and is discharged into a room in which takes place a first cooling of methane gas arrived as a result of its water separation operation.

3. Installation for free methane gas collection from the sea bottom, characterized by means of that, in a first realization operation, is constituted from some guiding arms A in a crosswise position, on which are sitting an intermediary platform B, destined to support some electrical reversible trolleys D and E used for displacement on vertical and radial direction of a flexible or telescopic conduit 21 and of some collectors K of some electrical reversible and double trolleys F with the help of which some separators L and a flexible conduit 50 can be driven on a radial direction, and conduit 50 can be driven on radial direction, and conduit 50 is kept in its horizontal position by some floating caissons 51 as well and of some electrical reversible and double trolleys G used to modify the position of some lateral anchors 7 and an inferior platform C destined for supporting together with platform B of components of a technological line H or Q and a superior platform 6 for alight or take-off of helicopter, some sloping portion of arms A serving for installing mentioned platforms B, C and 6 and the superior ends of them being rigidly assembled and supporting a hoist 4 for stiffing of a central anchor 5.

4. Apparatus for free methane gas collection from the sea bottom, according to the claim 2, characterized by means of that, under of arm A is placed a separator L connected at its inferior part through a conduit 21 to the collector K and on platform B and C are placed accordingly the separators L and connected with them by intermediary of flexible conduit 50 the mentioned technological lines H or Q.

5. Apparatus for collection of free methane gas from the sea bottom, according to the claim 2 characterized by means of that, the guiding arms A are provided with some horizontal portions 1 supported by some floating casings 2, at the exterior ends of each from arms A being located some propellers 8, 9, 10 and 11 so that at theirs putting in operation to produce a couple which to rotate the apparatus, according to the invention, around a vertical axis, materialized by rope of central anchor 5, the stiffness of mentioned arms A being done with the help of some ropes 12 stretched between the exterior ends of horizontal portion 1.

6. Apparatus for collection of free methane gas from the sea bottom, according to the claim 2, characterized by means of that the platform B and C have an octagonal form are provided with some openings a and respectively b.

7. Apparatus for collection of free methane gas from the sea bottom, according to the claim 2, characterized by means of that, each from water separators L is provided with a parallelepiped body 39 closed at its superior part with a cover 40 and sitting on a platform 45 supported by some floating cassias 46, in interior being positioned an horizontal plate 44 which delimits some rooms c and d and on which are installed a sleeve for overflow 43 connected at its inferior end with conduit 21 and some guiding tubes 52 through which vertically is running the ropes 22 and 26 through which are supported conduit 21 and a collector K, and at superior part of body 39 being installed some screens 41 and 42, on the same platform 45 being positioned and some pumps 47, and the connection of separator L is done by some ropes 48. The positioning of collector K close to the sea bottom is done with some legs 49.

8. Apparatus for collection of free methane gas from the sea bottom, according to the claim 2, characterized by means of that, each form the technological lines is provided with an humidity extractor M connected at its base with conduit 50 and from which is eliminated the condense from the methane gas, and at superior part by the conduit 60 the dry methane gas passes towards a methane gas liquidifier N from which is running, in the liquid state, through conduit 66 in a storage tank 0, a nitrogen-compressor 70 discharging the nitrogen gas through the expanded valve f towards a liquid nitrogen tank P from where the nitrogen is running towards some serpentines 62 and 55 of liquefactor N and respectively extractor M turbocompressor 70 being driven by a gas turbine 71 which is driving also an electric generator 4.

9. Apparatus for collection of free methane gas from the sea bottom, according to the claim 2, characterized by means of that, the electrical reversible trolleys D, E, F and G are provided with some ropes 13, 14, 22, 26, 31 and 36 supported and guided with the help of some rolls 15, 16, 17, 18, 19, 20, 23, 24, 25, 27, 28, 29, 30, 32, 33, 34 and 35 and of a block of rolls J.

10. Apparatus for collection of free methane gas from the sea bottom, characterized by means of that, in an other version of realization, is provided with a technological line Q equipped with an extractor of humidity R connected through conduit 53 to the separator L situated on platform C and connected through a conduit 86 at some turbocompressor S, T and U installed on the same axis of a gas turbine W which is coupled with an air compressor Z and with an electrical generator 84, between turbocompressor S, T and U being inserted some coolers g and h, the turbocompressor U being connected through a conduit 97 with a methane liquid tank V provided with a laminate valve j, between the extractor R and the tank V being placed an ejector m in which the suction is realized through a conduit 107 trough which is brought the methane gas from compressor S.

Description:

The present invention is referring to a procedure and apparatus for collection of free methane gas from the sea bottom destined to catch and liquefy the released methane gas from metastabile of methane hydrate situated on the seas and oceans bottom.

Following the increased interest of world's wide regarding the research efforts on getting the methane gas, a multitude of hydrate formation zones were discovered on the seas and oceans bottom bed, from which was found a multitude of metastabile zone of methane hydrate without lithologocal cover. If only a small fraction of this free methane gas from the seas and oceans bottom would be collected, it could constitute a significant energy resource as a fuel.

It is not known a procedure for collection of methane gas released from zones of metastabile gas hydrate deposits from the sea bottom. It is not known an apparatus destined to free methane gas collection released from deposits of hydrate gas from the sea bottom.

The matter that is resolved by the invention is the realization of a procedure and an apparatus, which will allow the free methane gas collection from the bottom of the sea. The procedure for collection of free methane gas from the bottom of the sea, according to the invention, eliminate the above mentioned disadvantages, because it is constituted from a first operation in which the collection of free methane gas from the bottom of the sea takes place and it is directed upwards, to a running section of methane gas, together with the sea's water and forming a mixture of methane gas-sea water. The shifting of mixture is done under a form of a current tube up to a room in which is taking place the separation phase, in which the mixture overflows at a level inferior to the sea's level, where the pressure is smaller than the one of the sea's bottom, and where is taking place a distribution/gravitational dispersion of it on a big surface on which the running is done at a more reduced pressure, which allows the separation of methane gas from water. The humid methane gas is collected at the room's superior part and the sea water is running freely towards an inferior level, from where, in the following operation, is absorbed and evacuated back in the sea for insuring the required level difference for the mixture's raising. In the following operation, the humid methane gas, captured at the superior room's part, is absorbed towards an other room where is cooled to reduce the condensation of the last fraction of sea's water, operation after which are obtained sea water in liquid state which is collected and then evacuated and dry methane gas. In the following operation is proceeding to the methane cooling at required temperature for its passing from gaseous state into liquid state. The procedure, in an other version of realization, comprises a first operation in which the humid methane gas, brought to the sea's surface is cooled in a room by bringing it in contact with cooled methane gas and by mixing it with this. Due to the diminished temperature it is taking place the condensation of the last fraction of the sea's water vapors and is getting the dry methane gas.

This operation is followed by the compression, in a first stage, up to a certain pressure and temperature, after which, to an other operation is cooled at sea water temperature. Follows a second compression stage, followed by a new cooling at sea temperature and by that the third stage of compression, in a last operation the methane gas discharged after this last compression being sent to a room where, after lamination followed by an adiabatic expansion, is passing from a gaseous phase to a liquid phase.

In parallel with the above operation, an other phase occurs, in which a part of compressed methane gas in first stage is taken to produce the absorption of liquid methane obtained according with the last operation. Following to this absorption, the compressed hot methane gas from the first compression stage is mixed with the liquid methane and is discharged into a room in which is taking place a first cooling of methane gas arrived following the operation of its water separation. The apparatus for collection of free methane gas from the sea bottom, according to the invention, is made from some guiding arms, set-up in crosswise position, on which are sitting an intermediary platform, destined to support some electrical reversible trolleys, used for radial and vertical direction displacement of a flexible or telescopic conduit and of some collectors for mixture, some double reversible trolleys with the help of which some water separators and a flexible conduit can be vertically and radial driven, and the flexible conduit is supported on its horizontal portion by some floating caissons, as well and of some double reversible electrical trolleys used to change the position of some lateral anchors.

An inferior platform, together with the intermediary platform, is destined to support the components of some technological lines, and a superior platform serves to alight or take off for the helicopter. Some sloping portion of guiding arms serve to support the three specified platforms and its superior ends are rigidly connected and keep up a hoist to stretch out a central anchor. Under each guiding arm is seating a water separator connected at its inferior part through a telescopic conduit with the collector of mixture, and on intermediary and inferior platform are located corresponding to the water separators and connected to them through the flexible conduits, the mentioned technological lines. The guiding arms are provided with some horizontal portions supported by some floating caissons, at the ends of each arm being located some helix, so that at their putting in operation to do a couple which to rotate the entire ensemble around the vertical axis, materialized by the central anchor's rope. Rigidiness of the showed guiding arms is done with the help of some ropes stretched between the exterior ends of its horizontal portions. The inferior and medium platforms have an octagonal form and are provided with an opening. Each of the water separators are provided with a parallelepiped corps closed at the superior part with a cover and sitting on a submarine platform sustained by some floating caissons. Inside is placed an horizontal plate which defines an inferior and superior room, on plate being mounted an overflow sleeve, connected at its down end to a telescopic conduit and some guiding tubs through which vertical is running the ropes through which is achieving the supporting of telescopic conduit and the mixture collector.

At the superior part of parallelepiped corps are sitting some screens for separation and on the same submarine platform are also sitting some pumps for evacuation. The hanging up of water separator is realized through some ropes, time in which the seating of mixture collector close to the sea bottom is done through some legs. Each of technological lines is provided with an extractor of humidity from methane, connected to the bottom with a conduit through which the condensate is eliminated and upper part, through other conduit, the dry methane gas is passing towards a methane gas liquifier, from which is running in the liquid state through a conduit in a storage tank. A compressor for nitrogen drive the nitrogen in gas state through a valve of lamination towards a tank of liquid nitrogen from where, the becoming liquid nitrogen is running towards some serpentines of methane liquidifier and respective water extractor. The turbo compressor is driven by a turbine with gases, which is driving and an electrical generator also. The reversible electrical trolleys are provided with some ropes supported and guided with the help of some guiding rolls and of one block of rolls. The apparatus, in an other version of realization, is provided with an other technological line equipped with an other extractor of humidity, connected through a conduit to the water separator, which is placed on an inferior platform and connected through other conduit to some turbocompressor in steps. They are situated on the same axis of a turbine with gases, which is coupled with an air compressor, and with an electrical generator, between turbocompressors being inserted some coolers. The turbocompressor is connected through a conduit with a tank of liquid methane provided with a valve for lamination, between the water extractor and the liquid methane tank being placed an ejector in which the aspiration is realized through a conduit through which the methane gas is brought from turbocompressor.

By using the invention, the following advantages are acquired:

    • The use of a big source of combustible which will reduce the effect of the energy needs.
    • The diminution of the atmosphere pollution.

In the following is presented an example of invention's realization in connection with figures from 1 to 10, which represent:

FIG. 1, general lateral view of apparatus for collection of free methane gas from the bottom of the sea, according to the invention;

FIG. 2, the kinematics sketch for driving anchors collectors and of methane gas separators, afferent to each guiding arms, according with the invention;

FIG. 3, the technological line of methane gas liquefaction, in first version of realization, afferent to each guiding arm, according to the invention;

FIG. 4, lateral view of apparatus, according to the invention, making evident the connection between the collector and separator of methane gas and technological line afferent to a guiding arm;

FIG. 5, section with a plane I-I from FIG. 4;

FIG. 6, section with a plane II-II from FIG. 4;

FIG. 7, section with a vertical plane through the collector and through the methane gas separator;

FIG. 8, section with a horizontal plane III-III from FIG. 7;

FIG. 9, section with a vertical plane IV-IV from FIG. 8;

FIG. 10, the technological line of methane gas liquefaction, in other version of realization, afferent to each guiding arm, according to the invention.

The procedure for collection of free methane gas from the sea bottom, in a first version of realization, according to the invention, starts with a first operation in which is taking place the collection of saturated mixture formed from sea water and methane gas and of free methane gas emanated from metastabile deposits from the sea bottom, from a big surface and of them upwards direction to a narrow running section towards sea's surface.

The water-methane gas mixture, which is rising continuously from the sea bottom based on the vessels communication principle, is over flown, in the next phase in a room, at an inferior level of the sea's level, where the pressure is smaller than that from the sea bottom and where is taking place a gravitational distribution/spreading of it on a big surface on which the running is done on a thin stratum. In these conditions, the separation of methane gas and water is done, the humid methane gas is collected at the superior part of room and the sea water is running freely towards an inferior level from where, in the next operation, is sucked and evacuated back into the sea.

The humid methane gas is then cooled, in an other room, by being in contact with a continuous cooled surface, for the condensation of the last fraction of the sea water vapors to be done, operation after which is obtaining the dry methane gas and sea water in liquid state, water which is collected and then evacuated.

In the next operation the cooling of methane gas is continued, until the required temperature for its passing into the liquid state is achieved, followed by its collection and storage.

The procedure for free methane gas collection from the sea bottom in other version of realization, according to the invention, is showing the modality of liquefaction of methane gas by compression and lamination, followed by an adiabatic expansion. In this way, the humid methane gas brought to the sea surface is cooled in a room by bringing it in contact with a jet of cooled methane gas and by mixing this cooled gas inside of the mentioned room. Because of temperature reduction is taking place the condensation of last fraction of sea water vapors, operation after which is obtained dry methane gas and sea water, water which after collection is evacuated.

The dry methane gas is sucked and compressed in a first step, up to a certain pressure and temperature, after which, in an other operation, is brought under the sea level where in contact with a surface at sea temperature is taking place its cooling.

These two successive operations of compression and cooling of methane gas are repeated also in the second step of compression. The methane gas so compressed at this second step is cooled too at the sea temperature and then is compressed again in that of the third step.

In a last operation, the methane gas discharged after the third compression is sent to a room where, after a lamination followed by an adiabatic expansion, is passing from gaseous phase into liquid phase.

In parallel with the above described operation of procedure, according to the invention, in this second version of realization, is taking place an other phase, in which a part of compressed methane gas from first step is taken to produce the suction of liquid methane gas obtained according to the last operation. The sucked liquid methane is discharged into the mixture with gaseous methane from the first step of compression towards a room in which, as was shown before, is taking place the first cooling of methane gas coming from water separator.

The apparatus for collection of free methane gas from the sea bottom, in a first version of realization, according to the invention is made from some guiding arms A positioned crosswise and provided with a horizontal portion 1 maintained at sea surface level with the help of some floating caissons 2 and which is cotinuing in the central zone with a slopping portion 3. The floating caissons 2 should be able to take over the statics and dynamics loads caused by the waves and winds so that the apparatus, according to the invention, to be maintained at sea surface level.

The slopping 3 portions are rigidified between them at the superior portion and holding a hoist 4 for stretching a central anchor 5, a superior platform 6 destined to alight and take off of helicopters, an intermediary platform B and an inferior platform C which sustain the power actuated elements and other various equipment.

The guiding arms A can be made from steel pipes, assembled in lattices, and the platforms 6, B and C are provided with steel grills and with balustrades for service personnel's protection. The platforms 6, B and C have to be rigidified towards the sloped portions 3 with the help of some beams, pillars, bars and diagonals, but these construction details do not make the object of this invention, being themselves known.

In the same time, the platforms B and C which have an octagonal shape and each are provided with an opening a and respectively b, will be placed at a sufficient height so that the sea's waves action to not impeded the worker's activity and the function of the equipment situated the platforms.

Because this entire apparatus, according to the invention, not to be displaced by the sea's currents of waves and winds, it is provided, besides the central anchor 5 with some lateral anchor 7, one for each arm A, connected by ropes.

The apparatus, according to the invention, can be rotated on an horizontal plane, around of central anchor 5, with the help of some propellers 8 and 9, driven by some not shown electromotrs, propellers placed diametrical opposite to the exterior ends of two arms A with the purpose of producing a couple of rotations of the entire ensemble.

The braking of this rotation movement can be done with the help of some other propellers 10 and 11 placed at the exterior ends of the other two arms A, diametrically opposed, allowing in this way to choose the desired position of the ensemble. It is obviously understood that, during the rotation operation of apparatus, according to the invention, the lateral anchors 7 should be raised.

To obtain a good stiffness of the guiding arms A, the exterior ends are connected between them with some ropes 12.

On the intermediary platform B are placed some groups of electrical reversible trolleys D, E, F and G, placed over each of guiding arms A and destined for driving the suspended components of respective arm A. On platform B is also placed a part of the necessary equipment of a technological line H.

The first two trolleys D and E are provided with a rope 13 and respectively 14, which are running on some guiding rolls 15 and 16 and respectively 17 and 18 as well and on a roll 19 and respectively 20, placed on a rolls block J, the ropes 13 and 14 upholding and permitting the vertical position modification of a collector K of mixture and of a conduit 21.

The third electrical reversible and double trolley F id driving a rope 22 which is passing over some guiding rolls 23, 24 and connected with frame 25 placed on block J, from where an other rope 26 is rolling on a guiding roll 27, then on a guiding roll 28 placed on block J and on some guiding rolls 29 and 30, rope 26 which allows the radial displacement along the arms A, of block of rolls J of a water separator L.

The trolleys G also double, is driving a rope 31 which is rolling on some rolls 32 and 33, on a roll 34 placed on block J and then on a guiding roll 35 being connected at the inferior end of lateral anchor 7 and permitting its vertical movement.

An other rope 36 of the same trolley G is rolling on some guiding rolls 37 and 38 with the scope of radial displacement and anchoring to the bottom of the sea the lateral anchor 7.

The water separators L are placed under each of guiding arms A, being partially submersed in the seawater.

Each of the water separators L are provided with a parallelipipedic body 39 closed tight and provided at its superior part with a cover 40, like a pyramid. The body 39 includes a superior room c in which are provided some horizontal strainers 41 and 42 of different sizes which are placed at certain distance one to the other, with the purpose of contributing to the partial separation of the methane gas of water vapors.

In the center of the body 39 is placed an overflow sleeve 43 united with a horizontal plate 44 so that the superior end of sleeve 43 to be situated under the seawater surface level and in the same time, over the plate 44. The bottom of the body 39 is placed on a platform 45; platform, which is sitting on some floating caissons 46 and together with plate 44, forms an inferior room d.

The sea water-methane gas mixture, which is running from sleeve 43 and is spreading on plate 44 surface, liberates the gas and the water is running through the two ends of plate 44 entering in the inferior room d. Some pumps 47 placed close to the body 39 on the same platform 45 suck the water from room d and discharge it in the sea.

The superior corners of paralelipipedic body 39 are connected with the help of rope 48 by the rolls block J, connection that allows the water separator L to move on a radial direction.

The overflow sleeve 43 is connected at its inferior ends with conduit 21, which can be flexible or telescopic and of which the inferior end was connected to the collector K. This one has the form of a pyramid and is provided at its base perimeter with some sitting legs 49 of a certain weight. After the collector K positioning over a metastabile zone e of hydrate methane, by penetration its legs 49 in the stratum of the sea bottom, its anchorage in a chosen position should be achieved.

The water separators L are connected to some aerial flexible conduits 50 of which horizontal portions found under the arms A are sitting on some floating caissons 51.

The ropes, 13 and 14, which are upholding the collector K, and conduit 21, are crossing the body 39 of separator L through some guiding tubes 52.

At its superior part, aerial, each flexible conduit 50 is connected through a fixed conduit 53 and a valve 54 with some humidity extractor M like a heat exchanger, located on an intermediary platform B. The extractor M is provided with a cooling serpentine 55, connected through valves 56 and 57 with technological line H, with a valve 58 at its superior part and with a discharge valve 59 at its lower part. From the valve 58 through conduit 60 and a valve 61 the extractor M is connected with a liquefactor of methane gas N equipped with an other cooling serpentine 62, provided at its ends with some valves 63 and 64 for entering and respectively exit.

The humidity extractor M and the gas liquefactor N are located on the intermediary platform B.

At the lower part of the liquefactor N are sitting a discharge valve 65 which, through a conduit 66 and a valve 67 makes the connection to a storage tank O provided with a discharge valve 68, and sitting on an inferior platform C.

The serpentine 55 of the extractor M is connected through a return conduit 69 to a compressor for nitrogen 70 driven by a gas turbine 71. The closing of this line through which the nitrogen is running is done through a discharge conduit 72 which makes the connection to a tank of liquid nitrogen P provided at its superior part with a valve 73 and a lamination valve f for adiabatic nitrogen expansion, and at the lower part with an other valve 74 from which through conduit 75 and entrance valve 63 is done the connection with gas liquefactor N.

The exit valve 64 of the cooling serpentine 62 of liquefactor N can be connected, either with the entrance valve 56 of serpentine 55 of extractor M through a conduit 76, or with a return conduit 69 through a conduit 77 and a valve 78.

An other connection, done with the scope of apparatus air purging, according to the invention, is that through which the conduit 60 between the valves 58 and 61 of extractor M and respectively liquefactor N was connected with the discharge conduit 72 which connects the compressor 70 with entrance valve 73 and the lamination valve f of liquid nitrogen tank P, connection made through a conduit 79 and a purge valve 80.

An other conduit 81 and a valve 82 make the connection from the superior part of liquid nitrogen tank P and the return conduit 69, on which is provided a connection 83 for filling with nitrogen gas.

The required electric energy for supplying the electromotors and other electrical subensembles of apparatus, according to the invention, is furnished by some electrical generators 84 placed on each of the guiding arms A and driven by gas turbine 71.

The apparatus for collection of free methane gas from the sea bottom, in an other realization version, according to the invention, has as scope the liquefaction of methane gas by compression, goal achieved with the help of a technological line Q. The coming methane gas from water separator L through conduit 53 enters through valve 54 in a humidity extractor R placed on platform C.

The dry methane gas is sucked through a valve 85, a conduit 86 and then through a valve 87 of a turbocompressor S, placed on the guiding arm A, from where, after a first compression, is sent through a valve 88 and conduit 89 to run through a cooler g placed in the sea water at a level close to its surface. From the cooler g, the methane gas is sucked through conduit 90 and through a valve 91 by turbocompressor T situated on the same axis with turbocompressor S. In the compressor T takes place the second step of methane gas compression and from where is discharged through a valve 92 and a conduit 93 towards an other cooler h, situated in the same conditions like the cooler g under the sea's surface level.

After the second cooling operation the methane gas is sucked through a conduit 94 and through valve 95 by the compressor U which does the third step of compression before the liquefaction. From here, the methane gas passes through valve 96 a conduit 97 a valve 98, after which is laminate through a valve j and then is adiabatic expanded passing in the liquid state in a tank V, where is being accumulated. From the tank V the liquid methane can be delivered to the custumers through conduit 99 and valve 100.

The turbocompressor S, T and U are driven by a gas turbine W coupled with an air compressor Z and with an electrical generator 84, all these equipment being placed on the guiding arm A at the intersection between the horizontal portion 1 and the sloping portion 3.

The cooling and condensation of water vapors from the humidity extractor R is done by sucking through a valve 101 and conduit 102 with the help of an ejector m the liquid methane from the tank V and then introducing it through a conduit 102 in the humidity extractor R in a gaseous state and at a suitable temperature for cooling and condensing the water vapors arrived with the gaseous methane through conduit 53 and valve 54. The condensate evacuation is done through a conduit 104 and valve 105.

The transformation of methane from liquid state in a gaseous state takes place in the ejector m with the help of hot methane gas arrived through valve 106, a conduit 107 and through an other valve 108 from the turbocompressor S.

The use of technological line Q for the methane liquefaction requires an additional attention and safety protection in order to eliminate the possible methane explosion.

Like in the case of other apparatus components, according to the invention, on each from guiding arms A and on platforms B and C is installed a technological line Q.

The apparatus, according to the invention, can be brought at the prospective place, where the methane collection will take place, by towing or propelling, or unensembled and then ensembled above the metastabile hydrate gas deposit of which extraction follows.

After its positioning at the desired coordinate by putting it in operation two by two and as much as it is necessary the propellers 8, 9, 10 and 11, it is proceeding to the ensemble alighting, letting first the central anchor 5 with the help of hoist 4 and then on row as two from lateral anchors 7 placed diametrically opposite, with the help of ropes 31 and 36 and the electrical reversible and double trolleys F and G.

The apparatus, according to the invention, once it is positioned, the trolleys D and E are put in operation, choosing first the position on a radial direction of water separators L the mixing collectors K and respectively a flexible conduit 50, maneuver followed by launching the collectors K and conduit 21 until near of the sea bottom, following a good set of legs 49 for giving stability to the collectors K.

The pumps 47 are put in operation to suck the water from the inferior room d of water separator M, water which is accumulated here after the mixture of sea water-methane gas overflows from sleeve 43 and for its continues evacuation into the sea. In this way it is ensured and controlled a water level, inferior of the upper end of mentioned sleeve 43.

This fact allows, in the first place, the ascendant flow of sea water-methane gas mixture, which is coming from metastabile zone e through collector K and conduit 21. This level difference facilitates also the water distribution on the entire surface of the horizontal plate 44 for taking place the gravitational separation, due to the difference of the density of methane gas and seawater.

The humid methane gas collected at the superior part of room c is sucked by conduit 53, enter into the humidity extractor M, where, due to the serpentine 55 cooled with nitrogen, is taking place the water vapors condensation on this surface and then the water collection and its evacuation through a connection 86 and a valve 59. The dry methane gas goes out from the extractor M through valve 58 and conduit 60, penetrates through valve 61 and enters into the methane liquefactor N, in which is produced its cryogenic liquefaction, due to the contact with the cooling serpentine 62 through which is running nitrogen.

The liquid methane accumulated at the inferior part of liquefactor N is running through valve 65 and 67, conduit 66 entering into the storage tank 0, from where its evacuation is done through connection 87 and valve 68.

The required nitrogen to the liquefactor N and the extractor M is introduced in apparatus, according to the invention, in gaseous state through connection 83, the return conduit 69 towards the compressor 70, from where is discharged through conduit 72, valve 73 and lamination valve f, where takes place the adiabatic expansion and then in the liquid nitrogen tank P. From here, the liquid nitrogen is running through the exit valve 74,

Bibliographic References
Patents:
4,007,787February 1977Cottle & Al.USA
4,376,462March 1983Elliott & Al.USA
4,424,858January 1984Elliott & Al.USA
6,180,843January 2001Heineman & Al.USA
6,192,691Februay 2001Nohmura & Al.USA-Japan
6,209,965April 2001Borns & Al.USA
6,214,175April 2001Heineman & Al.USA
6,299,256October 2001Wyatt & Al.USA
Technical literature
“Hydrate of Hydrocarbons” by Yury Makogon, Editor Penn-Well
Books, Tulsa-Oklahoma, USA 1977.