JP2015113701A - Method for mining methane hydrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient method for mining methane hydrate existing on an abyssal floor or a lake bottom, which minimizes energy to be injected.SOLUTION: All or some of shock waves, heat rays, hot water and high-temperature exhaust gas, which are generated by explosive combustion of mixed gas of ultra-high pressure compressed air and ultra-high pressure compressed methane gas on an abyssal floor or a deep lake bottom, are supplied to a methane hydrate layer so that the methane gas can be separated and recovered.

Description

  The present invention relates to a method for mining methane hydrate present in deep sea or deep lake water.

  Various methods of mining methane hydrate existing in the deep sea or deep lake water have been studied and studied, and civil engineering methods, heating methods, decompression methods, and chemical methods have been proposed.

  Accordingly, there has been a demand for a methane hydrate mining method that can be obtained from methane hydrate that has mined more energy than that injected from the outside and that does not release waste gas to the atmosphere as much as possible.

Patent Publication No. 10-317869 Patent Publication 2013-120257 Wikipedia, methane hydrate term

  Traditionally, research and trial drilling has been carried out to use methane hydrate as an energy resource, but methane hydrate exists in the deep sea and generally exists widely and thinly, so energy and cost for mining can be obtained. It has not been put to practical use more than the energy and benefits obtained from methane gas.

  The present invention provides a mining method that solves such conventional problems and that is inexpensive and less susceptible to natural destruction.

  And in order to achieve the above-mentioned purpose, the present method mixes ultra-high pressure compressed air and mined ultra-high pressure compressed methane gas in the water near the deep sea floor or deep lake bottom, and blasts and burns the resulting shock waves, heat rays, Hot water and hot exhaust gas are used.

  Since the methane hydrate mining method of the present invention takes the form as described above, a shock wave whose size can be adjusted in the deep sea or deep lake bottom is generated in the water, and is lost along with hot rays, hot water, and hot exhaust gas. It can irradiate the methane hydrate layer with less and more efficiently generate methane gas by synergistic effect than each.

  Further, by using the power generation internal combustion engine of Patent Document 2 on the deep sea floor, it is possible to generate power with good power generation efficiency and no problem of exhaust gas, and the power can be used in the field, and high temperature exhaust gas is also sand layer type methane hydrate layer. It is possible to supply slowly with the weight of the piston.

  Since the warm gas exhaust gas is supplied to the sand layer methane hydrate layer, unlike the liquid, it is difficult to cool and easily penetrates into the sand layer methane hydrate layer, and the methane gas easily mixes with the gas exhaust gas. It has been recovered.

  Methane hydrate mining explanation block diagram in shallow layer of water bottom   Block diagram explaining sand layer type methane hydrate mining in the deep bottom

  Embodiments of the methane hydrate mining method of the present invention will be described below with reference to the drawings.

  The methane hydrate layer that exists in the Sea of Japan has many methane hydrate layers exposed in bulk from the seabed to a relatively shallow layer.

  As shown in FIG. 1, a pipe 3 having a side hole 2 with a sharp tip is pierced into a methane hydrate lump 1 located shallow from the seabed.

  A pipe-shaped explosion combustion chamber 4 is provided at the upper end of the pipe 3, and a valve 6 is attached to the side hole 5.

  In addition, an air pipe 7, a methane injection pipe 8, and an exhaust pipe 9 are attached to the upper part of the cylindrical explosion combustion chamber 4. The exhaust pipe 9 descends and is connected to the heat exchanger 10 near the side hole 5. Yes.

  And the uppermost part has the funnel 11 covering the whole.

  Opening the valve 6 of the side hole 5 of the explosion combustion chamber 4 to inject seawater into the cylindrical explosion combustion chamber 4, air pipe 7, super-high pressure mixed gas of air and methane gas from the methane injection pipe 8, cylindrical explosion combustion chamber 4 is sent to the top.

  Next, the mixed gas is ignited, and seawater accumulated in the lower portion of the cylindrical explosion combustion chamber 4 is injected into the methane hydrate lump 1. By repeating this operation, the injected seawater becomes warm water.

  At this time, the methane hydrate lump 1 is irradiated with shock waves and heat rays. Therefore, the methane hydrate lump 1 is crushed by the shock wave, and the methane hydrate lump 1 becomes methane gas at the time of rough wave of the dense wave and prevents it from becoming methane hydrate again by the heat supplied together.

  The hot exhaust gas is sent to the heat exchanger 10 near the side hole 5 of the cylindrical explosion combustion chamber 4 to warm the nearby seawater, and the warmed seawater is efficiently injected into the methane hydrate lump 1.

  By this series of operations, methane gas generated from the methane hydrate lump 1 rises from the periphery of the pipe 3 and accumulates on the ceiling portion of the funnel 11.

  The accumulated methane gas is led to the sea by the exhaust pipe 12 and collected.

In the cavity where the methane hydrate lump 1 has been excavated, mud on the surrounding seabed is injected, and in the hole from which the pipe 3 has been removed, the cement disclosed in Patent Document 1 is injected and covered.
At this time, if the mud and cement in the seabed are mixed and injected into the cavity, it becomes stronger and has the effect of preventing the collapse of the seabed.

The exhaust gas that has finished its role is discharged from the exhaust pipe 9 into seawater. Therefore, CO ₂ and nitrogen oxides dissolve in seawater and are not discharged into the atmosphere.

  This shock wave is transmitted to a distant place of the methane hydrate lump 1, but its strength can be adjusted, the effective transmission range can be controlled, and there is no possibility of blowout of methane gas.

  To mine methane from methane hydrate mixed with sand called sand layer type deep in the deep ocean floor of the Pacific Ocean disclosed in Non-Patent Document 1

  As shown in FIG. 2, the pile 14 is excavated from the seabed toward the sand layer type methane hydrate layer 13,

  An exhaust gas pipe 16 having a side hole 15 at the tip is inserted into the standing pile 14. A power generation internal combustion engine 17 and a shock wave generator 18 disclosed in Patent Document 2 are connected to the seabed side of the exhaust gas pipe 16.

  The internal combustion engine 17 for electric power generation has a gap between the piston and the cylinder that is slightly wide at the top and bottom so that it operates in the sea, and the seawater is filtered and injected into the gap.

  At the time of explosion combustion of the mixed gas of ultra high pressure compressed air and ultra high pressure methane gas, the piston is lifted, and at this time, power is generated, and then the high temperature exhaust gas is guided to the exhaust gas pipe 16 by the pressure at which the piston falls and the sand layer type It is injected into the methane hydrate layer 13.

  At this time, a sufficient amount of methane gas is mixed with air so that the exhaust gas contains as little oxygen as possible.

  The shock wave generator 18 is also obtained by explosive combustion of a mixed gas of ultra high pressure compressed air and ultra high pressure compressed methane gas, and guides the generated shock wave to the exhaust gas pipe 16.

  The methane gas is separated from the methane hydrate by the warm exhaust gas supplied to the sand layer type methane hydrate layer 13 and the irradiated shock wave, and the methane gas rises from the periphery of the exhaust gas pipe 16, and reaches the ceiling of the funnel 19 at the top. Can be stored.

  The mixed gas of exhaust gas and methane gas stored in the upper part of the funnel 19 is guided to the outside, and mixed at the bottom of the sea with the seawater, so that the methane gas and the carbon dioxide gas become hydrate, respectively, and the methane hydrate has a higher temperature Then, the remaining carbon dioxide hydrate is separated into methane and taken out, and the remaining carbon dioxide hydrate is fed into the exhaust gas pipe 16 and injected into the sand layer methane hydrate layer 13 after completion of mining. The generated methane gas can be sent to the sea again as methane hydrate. The exhaust gas sent to the sand-type methane hydrate layer contains a large amount of carbon dioxide, which remains as carbon dioxide hydrate after being mined as methane gas.

  The electric power required at the site is the electric power generated by the power generation internal combustion engine 17. The methane gas that is collected on site is used. By doing so, the loss of electricity transmission and the energy loss of sending methane gas compressed to ultra high pressure are eliminated.

  By providing the shock wave generator 18 separately, the shock wave intensity can be finely adjusted.

  Since the exhaust gas is mainly a gas made of nitrogen and carbon dioxide, it has a lower thermal conductivity than liquid, so it is difficult to cool and mix quickly with methane, so that methane gas becomes methane hydrate again. It is preventing.

  The exhaust gas penetrates well into the sand layer type methane hydrate layer 13. Since the positive pressure is applied, the exhaust pipe 16 is not clogged with sand.

  When the methane hydrate excavation is finished, the seabed mud and cement disclosed in Patent Document 1 are mixed into the exhaust gas 16 and pushed in with the high-temperature and high-pressure exhaust gas generated from the power generation internal combustion engine 17.

  In order to prevent large-scale collapse of the seabed, the geological pattern of the seabed and the methane hydrate layer will be investigated in advance to determine the order of methane hydrate excavation positions.

There is an embodiment in which the exhaust gas pipe 16 is extended along the sand layer type methane hydrate layer 13.

  In order to send air to the sea bottom or the lake bottom, a large amount of energy is consumed for compression. Therefore, air is put into a container containing a gas that opens downward, and is submerged to the sea bottom or lake bottom under its own weight. Then, the methane gas collected after using the air inside is packed and floated on the sea or lake. By repeating this work, the energy used for transporting air and methane gas can be reduced.

  The gas is compressed at the bottom of the sea or lake and is compressed and the buoyancy is greatly reduced, so the rope or chain is connected to a container containing the open gas, and a weight is placed under the rope or chain, so Since no external force is required, the energy required for transporting air and methane gas can be saved.

  The present invention can be used for methane hydrate excavation on the seabed and lake bottom.

DESCRIPTION OF SYMBOLS 1 Methane hydrate lump 2,5,15 Side hole 3 Pipe 4 Cylindrical explosion combustion chamber 6 Valve 7 Air pipe 8 Methane injection pipe 9,12 Exhaust pipe 10 Heat exchanger 11, 19 Funnel 13 Sand layer type methane hydrate layer 14 Standing pile 16 Exhaust gas pipe 17 Internal combustion engine for power generation 18 Shock wave generator

Claims (6)

  A methane hydrate mining method that separates and collects methane gas by irradiating the methane hydrate-containing layer with all or part of shock waves, heat rays, hot water, and exhaust gas obtained by exploding fuel in water.   The methane hydrate mining method according to claim 1, wherein compressed air and compressed methane gas are sent into a cylindrical shape and explosive combustion is performed to generate shock waves, heat rays, hot water, or high-temperature and high-pressure exhaust gas.   The methane hydrate mining method according to claim 1, wherein exhaust gas obtained from an internal combustion engine operating in water is supplied to the methane hydrate-containing layer.   The methane hydrate mining according to claim 1, wherein the carbon dioxide gas supplied to the methane hydrate-containing layer and the generated methane gas are changed into a carbon dioxide hydrate and a methane hydrate, respectively, and the methane gas is separated according to a difference in decomposition temperature thereof. Method.   The methane according to claim 1, wherein air is put into a container containing a gas that is open at the bottom and submerged at or near the bottom of the sea or at the bottom of the lake, and after the air has been used, the methane gas is filled and floated on the sea or on the lake. Hydrate mining method.   6. The method of mining methane hydrate according to claim 5, wherein a rope or chain is connected to a container for containing a gas that is open downward, and a weight is attached below the rope or chain.

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