Hydraulic and earth engineering – Marine structure or fabrication thereof – Storage container
Reexamination Certificate
2000-08-23
2002-02-19
Bagnell, David (Department: 3673)
Hydraulic and earth engineering
Marine structure or fabrication thereof
Storage container
C405S195100
Reexamination Certificate
active
06347910
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method of manufacturing a large tank for use as an oil tank or a CO
2
storage tank, for use in building a submerged tunnel, a submarine living quarter or a submarine station, or for use as a battery tank.
The invention also relates to a combined system for deep-sea power storage and carbon dioxide dissolution.
Further, the invention relates to a deep-sea power storage system for generating electric power by using sea water.
Still further, the present invention relates to a submarine power storage system which is installed in the deep sea and which stores electric power by utilizing the pressure of sea water.
Moreover, this invention relates to a submarine storage system designed to store, for example, LNG.
Furthermore, the present invention relates to a method of building a submerged tunnel for drive ways and railroads, which runs on the seabed.
BACKGROUND ART
Conventionally, a submarine tank is built on land, in a horizontal position in a dock large enough to hold the entire tank.
A system may be constructed by using as large a tank as possible, for example, a cylindrical tank having a diameter of 100 m and a length of 400 m. Building of such a large tank on land is subjected to various restrictions. Hence, tanks that can be built on land are limited in size.
More specifically, if a large tank is manufactured on the land, its size is limited by the size and proof strength of the dock, and also by the draft of the dock and the depth of the neighboring water passages.
An object of the invention is to provide a method which can manufacture a tank that is too large to be built on land.
Such a large tank finds use in, for example, thermal power plant. A thermal power plant is located near the seacoast in most cases. The carbon dioxide gas (carbon oxide gas) generated in the thermal power plant will result in environmental disruption such as air pollution. Attempts have been made to dissolve the gas in sea water and thereby discard the gas, by using various methods.
More precisely, (1) a method of dissolving the carbon dioxide gas generated in the thermal power plant, directly in sea water; (2) a method of solidifying the carbon dioxide gas into dry ice and sinking the dry ice onto the sea bottom: and (3) a method of liquefying the carbon dioxide gas aboard a ship and dissolving the gas in the sea water, over a sea zone 1000 m wide.
With the method (1) it is difficult to dissolve the carbon dioxide gas sufficiently. Furthermore, there exists the danger that the carbon dioxide gas blows up over the sea surface.
The methods (2) and (3) may render the sea water strongly acid. This is because the liquefied or solidified carbon dioxide is dissolved in the sea water, inevitably increasing the carbon dioxide concentration in the sea water, making the sea water strongly acid.
Consequently, the methods (2) and (3) affect the deep-sea life. The methods (2) and (3) may also induce environmental changes because it lowers the temperature of sea water. Further, a great amount of energy is required to perform the methods (2) and (3), in which carbon dioxide is solidified into dry ice and liquefied, respectively.
The present invention has been made in view of the above. An object of the invention is to provide a combined system for deep-sea power storage and carbon dioxide dissolution, which can store power, causing no cavitation of a high-head pump turbine, and which can dissolve and discard carbon dioxide at low cost, not affecting marine ecology or causing environmental changes.
The conventional power system is disadvantageous in the following respect. Hitherto known is a pumped storage power system in which water is pumped up at night by using surplus electric power, and electricity is generated in the day when the power consumption is at its peak. However, geographical conditions for a pumped storage power system are restrictive, and the building cost of the system is increasing much. In view of this, it has become difficult to construct new pumped storage power plants.
Recently a deep-sea power storage system has been proposed as a low-cost power plant. This system has less restriction on its geographical conditions, and can be constructed at low cost. The system comprises a main body and a battery tank. The main body, which has a pump turbine, is installed in the deep sea, together with the battery tank. At night, the surplus power generated on land is used to turn the pump turbine, thereby discharging sea water from the battery tank, and power is stored by virtue of the energy obtained from the water head between the sea level and the sea water level in the battery tank.
In the day when the power consumption is at its peak, sea water is poured into the battery tank, thereby turning the pump turbine and generating electric power, and the power thus generated is supplied to the land.
Jpn. Pat. Appln. KOKAI Publication No. 04-01940 based on a patent application, for example, in which the present applicants are named as inventors, discloses a deep-sea power storage system. In this system, sea water is introduced into the pressure-resistive vessel laid in the deep sea (usually, on the seabed), rotating the water turbine. The water turbine drives the generator, which generates electric power. The power generated is supplied to the land. In the system, the surplus power available on the land is used to drive the water turbine, pumping the sea water from the pressure-resistant vessel, thereby to store the electric power.
Studies must be conducted for the foundation of such a deep-sea power storage system, which is strong enough to withstand earthquakes. This is because earthquakes may happen at the seabed on which the system is installed.
Measures should be established that must be taken to repair the various components of the system, such as the pump turbine, if troubles should develop in these components in the deep sea. Furthermore, measures should be established that must be taken in case cavitation takes place. Cavitation is likely to happen when a vacuum similar to water vapor develops in the space above the sea water level in the battery tank as the pump turbine discharges the sea water from the tank.
The present invention has been made in view of the above. An object of the invention is to provide a deep-sea power storage system which is greatly resistant to vibration, which can easily be repaired, and which can operate reliably.
A conventional submarine power storage system is installed, with the battery tank and electrical/mechanical component cases (containing power-generating equipment, power-storing equipment and the like) provided and secured within the pressure-resistant vessel.
Therefore, an additional pressure-resistant vessel must be used in order to increase the output of the system a little, if necessary to meet an increased demand for electric power. In fact, it would be extremely difficult to satisfy such a demand as described above.
In the case of a pumped storage power plant constructed in a mountainous region, which utilizes the head of a water storage dam, the amount of power it can store is determined by the capacity of the dam. With this plant it is difficult to store more electric power.
In view of this, the present invention has been made. An object of the invention is to provide a submarine power storage system that can have its storage capacity increased even after the commercial operation.
There is the trend of stockpiling LNG, just like petroleum. The annual domestic consumption of LNG is about 55,000,000 m
3
at present. If LNG were to be stored for 120 days of consumption, like petroleum, it should be stored in an amount of 18,000,000 m
3
.
In order to store this amount of LNG, 90 LNG tanks are necessary, each capable of storing 200,000 m
3
at most. At present there is no land large enough to build so many tanks. From an economical point of view, too, it is difficult to build these tanks.
It would be dangerous, as is pointed out, that LNG tankers frequently navigate along a gulf coast where thermal power plan
Bagnell David
Lee Jong-Suk
Mitsubishi Heavy Industries Ltd.
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