Refrigeration – Storage of solidified or liquified gas – Underground or underwater storage
Reexamination Certificate
1999-09-20
2001-02-27
Doerrler, William (Department: 3744)
Refrigeration
Storage of solidified or liquified gas
Underground or underwater storage
Reexamination Certificate
active
06192691
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of collecting methane hydrate gas hoarded in the bottom of the sea or in the bottom of the water, and an apparatus therefor.
2. Description of the Prior Art
Various methods have heretofore been studied for collecting methane hydrate gas. There has been known, for example, a method according to which hot seawater is injected into a methane hydrate layer in the bottom of the sea to change the temperature condition for the methane hydrate into a temperature at which the methane hydrate is decomposed into water and a methane hydrate gas, and the decomposed methane hydrate gas only is transported to a liquefying facility on the sea and is liquefied. There has further been known an apparatus for collection wherein a pair of transport pipes are extended from the facility on the sea to the methane hydrate layer, the seawater is injected into the methane hydrate layer through one transport pipe, and the other transport pipe is connected to the liquefying facility to collect the methane hydrate gas. As is well known, the methane hydrate is a product having a composition CH
4
. 6 to 7 H
2
O and having affinity to water, and decomposes under a pressure of 8 kg/cm
2
at 0° C. producing heat of decomposition of 100 kcal/kg. However, it is difficult to correctly probe the pressure in the methane hydrate layer and the degree of stability of the layer from above the water or the sea. The transport pipes that are carelessly driven causes the methane hydrate gas to erupt on a large scale permitting a useful gas resource to be released into the open air accelerating the warming-up of the atmosphere.
Therefore, a technical problem is arousing that must be solved for trapping the methane hydrate gas on the bottom of the sea or on the bottom of the water using a flexible sheet. It is a first object of the present invention to solve the above-mentioned problem.
Another object of the present invention is to collect the methane hydrate gas trapped in the sheet by transporting it to above the water or the sea.
SUMMARY OF THE INVENTION
In order to accomplish the first object, the present invention provides a method of collecting methane hydrate gas by forming a sheet to cover the bottom of the sea or the bottom of the water over a predetermined area, sinking the sheet on the bottom of the sea or on the bottom of the water to spread it, and trapping the methane hydrate gas in the sheet as the interior of the sheet is lifted up by the buoyancy of the gasified methane over the area where the sheet is spread.
The invention further provides a method of collecting methane hydrate gas by stretching skeletal members for a sheet to form a dome for covering the bottom of the sea or the bottom of the water over a predetermined area, sinking said dome so as to be landed on a portion where the methane hydrate is hoarded in the bottom of the sea or in the bottom of the water, and trapping the gasified methane hydrate gas in said dome.
In order to accomplish another object, the present invention provides a method of collecting methane hydrate gas, wherein a gas transport pipe is connected to said sheet, and the methane hydrate gas trapped in said sheet is transported through said transport pipe to above the water or above the sea.
The invention further provides a method of collecting methane hydrate gas of any one of the above-mentioned methods, wherein the seawater, water or hot water of a temperature for gasifying the methane hydrate is continuously supplied to between said sheet and the bottom of the sea or the bottom of the water in order to forcibly gasify the methane hydrate.
In order to accomplish the first object, further, the present invention provides an apparatus for collecting methane hydrate gas comprising a sheet for covering the bottom of the sea or the bottom of the water over a predetermined area, a sheet-sinking means such as weights or anchors for spreading and sinking said sheet on the bottom of the sea or on the bottom of the water, and a guide means for guiding said weights to predetermined positions on the bottom of the sea or on the bottom of the water, wherein the portion where the methane hydrate is hoarded in the bottom of the sea or in the bottom of the water is covered with said sheet to trap the methane hydrate gas in the sheet as the interior of the sheet is lifted up by the buoyancy of the gasified methane hydrate.
The invention further provides an apparatus for collecting methane hydrate gas wherein skeletal members are stretched for a sheet to form a dome for covering the bottom of the sea or the bottom of the water over a predetermined area, sheet-sinking means such as weights or anchors are secured to said dome in order to sink the sheet together with the skeletal members on the bottom of the sea or on the bottom of the water, said dome is provided with a dome guide means for guiding the dome onto the portion where the methane hydrate is hoarded in the bottom of the sea or in the bottom of the water so as to be landed thereon, and said dome is landed on the portion where the methane hydrate is hoarded in the bottom of the sea or in the bottom of the water in order to trap the methane hydrate gas in the dome.
In order to accomplish another object, the present invention provides an apparatus for collecting methane hydrate gas wherein a gas transport pipe is connected to said sheet, said gas transport pipe extending from the bottom of the sea or from the bottom of the water to above the water or above the sea, and the methane hydrate gas trapped in said sheet is transported through said transport pipe.
The invention further provides an apparatus for collecting methane hydrate gas wherein a gas transport pipe is connected to said sheet, said gas transport pipe extending from the bottom of the sea or from the bottom of the water to above the water or above the sea, and the seawater, water or hot water of a temperature for gasifying the methane hydrate is supplied to between said sheet and the bottom of the sea or the bottom of the water through said transport pipe, in order to gasify the methane hydrate gas trapped in the bottom of the sea or in the bottom of the water.
REFERENCES:
patent: 3159006 (1964-12-01), Sliepcevich
patent: 3195310 (1965-07-01), Schoeder
patent: 3662558 (1972-05-01), Jackson
Doerrler William
Drake Malik N.
Fattibene Arthur T.
Fattibene Paul A.
Fattibene & Fattibene
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