Method and apparatus for producing compressed air

Abstract: A method and apparatus for producing compressed air include sealing air in a container (10) capable of reducing its volume upon application of an external hydraulic pressure, attaching a weight (40) having a larger specific gravity than water to the container (10) and sinking the container (10) deep under water. The air which is compressed in the container as its volume is reduced is collected in a recovery vessel (30) connected to the container (10) via a non-return valve. The weight (40) is subsequently released from the container (10) to allow the container (10) to float to the surface of the water by the action of buoyancy to allow the compressed air to be recovered from the recovery vessel (30). The compressed gas may then be used to provide the motive power to drive a water pump to return water that has been used for hydroelectric power generation from a lower reservoir to an upper reservoir.

Description: The present invention relates to a method for the production of compressed air and to an apparatus for carrying out the method. Energy available at present in the world relies heavily on coals, petroleum, nuclear power, the use of which often results in environmental destruction. On the other hand, hydro-electric power, wind power or wave power whose power has nothing to do with environmental destruction has little or no prospect of great development. JP 60190679 describes a method and apparatus for obtaining compressed gas in which the volume of a fixed chamber filled with air is reduced by the compressing action of a piston. According to a first aspect of this invention a method for producing compressed air, comprises the steps of; sealing air in a container capable of reducing its volume upon the application of an actuating force; and, inserting under pressure compressed air produced when the volume of the container is reduced by said actuating force into a recovery vessel connected to the container via a non-return valve; and is characterised in that it further comprises the steps of attaching a weight having a larger specific gravity than water to the container and sinking the container deep under water to reduce the volume of the container by the application of external hydraulic pressure; separating the weight from the container to cause the container to float to the water surface by the action of buoyancy; and, recovering the recovery vessel (30) containing the compressed air, whereby the compressed air can subsequently be recovered from the recovery vessel (30). According to a second aspect of this invention an apparatus for producing compressed air, comprises: a container having an air chamber in which air is sealed and which is capable of a reduction in volume on application of an actuating force; and, a recovery vessel connected to the container via a non-return valve for receiving compressed air produced when the volume of the chamber is reduced by the actuating force; and is characterised in that a weight (40) is attached to the container for sinking the container and the vessel deep under water to reduce the volume of the container by the application of external hydraulic pressure. The present invention utilises three physical properties, i.e. the fact that a substance at a high position has a higher potential energy than a substance at a low position, that buoyancy acts on a substance in water and that hydraulic pressure increases in proportion to depth of water. To be specific, a container having air sealed therein is sunk deep under water by using a weight having a larger specific gravity than water, thereby compressing the air in the container by means of hydraulic pressure and then the weight is caused to be free from the container to allow the container to float on the water by the action of buoyancy of a buoyant body, and the compressed air is recovered from the container. Thus, the present invention requires the specific gravity hydraulic pressure and buoyancy all obtained from the natural resources. The air expansion energy of the recovered compressed air can be applied to a hydroelectric power generating apparatus. Such an apparatus is described and claimed in our co-pending divisional application, European Application No. 93118570.6 (Publication No.0599196). In this case, the water once subjected to power generation can be repeatedly re-cycled. Therefore, the hydraulic power generation otherwise limited by the amount of rain water can be utilised to the maximum possible extent. In addition, the hydro-electric power generation can be applied to a private power generation in a multi-stored building, for example. The air expansion energy of the compressed air can be used in the form of a power for driving and propelling vehicles or as cooling means utilising the phenomenon that when gas is expanded it absorbs the environmental heat. When the compressed air is mixed with a fuel in an internal combustion engine, the amount of the fuel can be saved. The compressed air is also applicable to a sprayer. Thus, since the air expansion energy of the compressed air can be converted into various kinds of energy, the present invention can reduce the amount of the fossil fuels used at present to a great extent. Particular embodiments of the various aspects of this invention will now be described with reference to the accompanying drawings; in which: FIG. 1 is a schematic cross section illustrating one embodiment of the apparatus for producing compressed air according to the present invention, with a clamping device omitted; FIG. 2 is a schematic cross section illustrating the apparatus, with a compressed air recovery vessel omitted; FIG. 3 is a schematic cross section illustrating another embodiment of the apparatus for producing compressed air according to the present invention; FIGS. 1 and 2 are schematic cross-sectional views illustrating one embodiment of the apparatus for producing compressed air according to the present invention. The apparatus 1 includes a container body 10 having an air chamber 12 sealing air therein and is capable of reducing its volume by hydraulic pressure, a compressed air recovery vessel 30 connected to the air chamber 12 via a check valve 32 and adapted to receive the compressed air therein when the volume of the air chamber 12 is reduced by hydraulic pressure, and a weight 40 mounted on the container body 10 and adapted to sink the container body 10 and recovery vessel 30 deep under water. The cylindrical container body 10 has a compression piston 14 disposed therein for dividing the interior of the container body 10 and being slidable upward and downward along the inner wall of the container body 10 into the air chamber 12 and a water chamber 16 formed with a plurality of water inlet ports 18 for introducing water thereinto. When the container body 10 is caused to sink deep under water, the external water enters the water chamber 16 disposed on the upper side of the compression piston 14 through the water inlet ports 18 under pressure. The compression piston 14 moves toward the air chamber 12 urged by hydraulic pressure of the water entering the water chamber 16 to thereby compress the air in the air chamber 12. The air chamber 12 is connected to a compressed air recovery vessel 30 through a connecting tube 34. The connecting tube 34 is provided with a check valve 32. The compressed air recovery vessel 30 has a very small volume compared with that of the air chamber 12 before being reduced in volume so that the compressed air supplied into the recovery vessel 30 can be maintained intact. The check valve 32 acts such that when the pressure in the air chamber 12 is higher than that in the compressed air recovery vessel 30, the air in the air chamber 12 is permitted to flow into the air recovery vessel 30 and that when the pressure relation is reversed, the compressed air in the air recovery vessel 30 does not flow back into the air chamber 12. The recovery vessel 30 can be detached from the container body 10 for replacement. FIG. 3 shows another embodiment of the apparatus for producing compressed air according to the present invention. In this embodiment, the outer wall of the container body 10 can be deformed in such a manner as being expanded and contracted in the vertical direction by the external hydraulic pressure. The inside space of the container body 10 serves as an air chamber 12. When the outer wall is contracted by the external hydraulic pressure, the volume of the air chamber 12 can be reduced. The structure of the container body 10 will be described in more detail. It is constructed in a sealed state such that an upper plate 21 and a lower plate 22 are joined together through a cloth material 24 and that a plurality of annular reinforcement member 26 are sewn to the cloth member 26 so that it is expanded into a cylindrical configuration when air having a higher pressure than the atmospheric pressure is introduced into the air chamber 12. The cloth material 24 is formed of a material which is strong in tensile stress and water- and air-impermeable. The reinforcement members 26 is strong against a compressive force and is hardly deformed. The air chamber 12 is provided with an air inlet valve 28 adapted to take air into the air chamber 12. The upper plate 21 of the container body 10 is connected to a compressed air recovery vessel 30 via a connecting tube 34. The connecting tube 34 is provided with a check valve 32 which has the same function as the check valve 32 of the previous embodiment. Although the container body 10 of this embodiment has a hollow cylindrical configuration, it is preferable to have a hollow spherical configuration so that it can bear the hydraulic pressure of deep sea. In any of the embodiments described above, a weight 40 is detachably attached to the container body 10 in order to sink the container body 10 deep under water. The weight 40 is detached from the container body 10 when the volume of the air chamber 12 is reduced to the maximum possible extent by hydraulic pressure. The container body 10 of the embodiment shown in FIGS. 1 and 2 is provided with a buoyant body 70 so that it can float on the water by means of buoyancy when the sink weight 40 has been detached from the container body 10, whereas the compressed air recovery vessel 30 of the embodiment shown in FIG. 3 concurrently serves as a buoyant body 70, which will be described later. The weight 40 detached from the container body 10 when the volume of the air chamber 12 is reduced to the maximum possible extent, i.e. when the surface of the compression piston 14 comes into contact with the bottom of the air chamber 12 in the embodiment of FIGS. 1 and 2 or when the upper and lower plates 21 and 22 comes into contact with each other in the embodiment of FIG. 3. In the embodiment shown in FIGS. 1 and 2, the weight 40 is accommodated within a weight mounting device 42 which comprises a casing 44 having a bottom portion 46 capable of being opened by the weight of the weight 40. The bottom portion 46 is closed by a wire 48 clamped by a clamping device 50 without being accidentally opened. The clamping device 50 comprises a spanner-like holding metal piece 52 which has clamp portions and proximal portions pivoted on a pin 54. When the proximal portions are away from each other, the clamp portions are also away from each other. One of the proximal portions is fixed to a lower part of the container body 10, whereas the other of the proximal portions is left free. Between the proximal portions a spring body 56 is interposed for biasing the free proximal portion in a direction away from the fixed proximal portion. A lock lever 58 is provided to lock the free proximal portion so as not to be away from the fixed proximal end by the biasing force of the spring body 56. An unlocking pin having the upper end thereof projecting into the air chamber 12 and the lower end thereof engaged with the lock lever 58. Therefore, when the upper end of the unlocking pin 60 is depressed by the compression piston 14, the lock lever 58 is disengaged from the free proximal end and, as a result, the free proximal end is biased by the biasing force of the spring body 56 in the direction of being away from the fixed proximal end to open the clamp portions. Consequently, the wire 48 is released from the clamp portions and the bottom portion 46 of the casing 42 is opened by the weight of the weight 40, whereafter the weight 40 is discharged out of the casing 42. Gravel on the seashore can be used as the weight 40. The same clamping device 50 as in the embodiment of FIGS. 1 and 2 is used in the embodiment of FIG. 3, provided that the weight 40 is formed of a bag filled with gravel and suspended from the clamping device 50. In the apparatus shown in FIGS. 1 and 2, both the container body 10 and the casing 4 are provided with buoyant chambers acting as the buoyant body 70. Since a compressed stress applied to the buoyant chambers becomes larger in proportion as the apparatus sinks deeper under water, the structural members constituting the buoyant chambers are required to be rigid. In order to make the difference between the internal pressure and the external pressure small as much as possible at the bottom of water at which the apparatus reaches, it is desirable to fill the buoyant chambers with compressed air in advance. In the apparatus of FIG. 3, the compressed air recovery vessel 30 is concurrently as the buoyant body 70 which has a hollow spherical configuration and is connected to an upper portion of the container body 10 via rods 72. Due to the dual function of the recovery vessel 30, the pressure of the air contained therein is increased by repeating the recovery operation in view of the volume of the recovery vessel 30 and, therefore, the apparatus of FIG. 3 can bear higher hydraulic pressure in deeper water and can be suitably used for obtaining a compressed air of high pressure. The operation of the apparatus of FIGS. 1 and 2 will now be described. The compression piston is pulled to the highest position and then the air recovery vessel is attached to the container body 10. After the bottom portion of the casing 44 is closed, the weight 40 is introduced into the casing 44. The casing 44 is then attached to the lower part of the container body 10. Thereafter the apparatus is hung above the surface of the sea by means of a hanging chain (not shown) and then separated from the hanging chain. As a result, the whole apparatus is sunk deep under sea by the gravity. At that time, water flows into the water chamber 16 through the water inlet ports 18 owing to hydraulic pressure to push the compression piston 14 down, thereby compressing the air in the air chamber 12. The hydraulic pressure increases more and more as the apparatus sinks deeper and the lower end of the compression piston 14 is finally brought to the bottom portion of the air chamber 12. Thus, all air in the air chamber 12 is inserted into the recovery vessel 30 under pressure. Since the recovery vessel 30 is provided with the check valve 32, decrease of air pressure in the air chamber 12 does not cause the compressed air in the recovery vessel 30 to flow back to the air chamber 12. When the lower end of the compression piston 14 reaches the bottom portion of the air chamber 12, the clamped state of the clamping device 50 is released and the bottom portion 46 of the casing 44 is opened to drop the weight 40. As a result, the buoyancy acts on the whole apparatus owing to the function of the buoyant chambers 70 and the whole apparatus floats on the surface of the sea automatically, thus producing compressed air. Operation of the apparatus shown in Fig. 3 will now be described. The air inlet valve 28 of the container body 10 is opened and the weight 40 is attached to the lower plate 22 through the clamping 50. When the apparatus with the upper plate 21 directed upward is hung by a crane (not shown), air automatically flows into the air chamber 12 of the container body 10 through the air inlet valve 28 owing to the function of the weight 40 to expand the container body 10 into a cylindrical configuration. Then, the valve 28 is closed. The weight 40 is attached to the clamping device 50 of the weight mounting device 42. The whole apparatus is slowly lowered onto the surface of water and separated from the crane. The whole apparatus slowly sinks under water. When the hydraulic pressure increases as the apparatus sinks deep under water, air in the air chamber 12 is compressed and the air chamber 12 is reduced in volume. However, the air chamber 12 is reduced in size not in the horizontal direction because of the presence of the annular reinforcement members 26 but in the vertical direction and consequently exhibits a vertically compressed appearance as a whole. As a result, air in the air chamber 12 is compressed to an extent that the internal pressure is substantially equal to the external hydraulic pressure, and part of the compressed air is stored in the air recovery vessel 30. As the apparatus sinks deeper, the volume of the air chamber 12 is further reduced by the hydraulic pressure and most of the air in the air chamber 12 is inserted under pressure into the air recovery vessel 30. At the same time, a projection 62 attached to the upper plate 21 pushes down the unlocking pin 60 mounted on the lower plate 22 to release the locked state of the lock lever 58, and the clamping portion of the holding metal piece 52 is opened by means of biasing force of the spring body 56 to release the weight 40. When the weight 40 has been detached from the apparatus, the whole apparatus begins to float upwardly owing to the function of the recovery vessel 30. At this time, since the recovery vessel 30 keeps a high pressure owing to the provision of the check valve 32, it is lifted by the crane when it finally floats on the surface of the water. When the air inlet valve 28 is opened, air flows into the air chamber 12 to restore the apparatus to its original shape. By repeating the above processes without removing the air recovery vessel 30 from the container body 10, the amount of compressed air corresponding to the volume of the recovery vessel 30 can be recovered.

Claims: A method for producing compressed air, comprising the steps of: sealing air in a container (10) capable of reducing its volume upon the application of an actuating force; and, inserting under pressure compressed air produced when the volume of the container (10) is reduced by said actuating force into a recovery vessel (30) connected to the container (10) via a non-return valve (32); characterised in that the method further comprises the steps of; attaching a weight (40) having a larger specific gravity than water to the container (10) and sinking the container (10) deep under water to reduce the volume of the container (10) by the application of external hydraulic pressure; separating the weight (40) from the container (10) to cause the container (10) to float to the water surface by the action of buoyancy; and, recovering the recovery vessel (30) containing the compressed air, whereby the compressed air can subsequently be recovered from the recovery vessel (30). An apparatus for producing compressed air, comprising: a container (10) having an air chamber in which air is sealed and which is capable of a reduction in volume on application of an actuating force; and, a recovery vessel (30) connected to the container (10) via a non-return valve (32) for receiving compressed air produced when the volume of the chamber is reduced by the actuating force; characterised in that a weight (40) is attached to the container (10) for sinking the container (10) and the vessel (30) deep under water to reduce the volume of the container (10) by the application of external hydraulic pressure. An apparatus according to claim 2, wherein said weight (40) is released from the container (10) when the volume of the air chamber is reduced to its maximum extent by the hydraulic pressure and further comprising a buoyant body (70) for encouraging the container (10) to float on the surface of water by means of buoyancy when the weight (40) is released. An apparatus according to claim 2 or 3, wherein the container is formed as a piston (14) and cylinder assembly with a compression piston (14) slidable along the cylinder for dividing the interior of the cylinder into an air chamber (12) and a water chamber (16), the water chamber (16) having water inlet ports (18) for allowing water to flow thereinto, the air chamber (12) having its volume reduced when the compression piston moves towards the air chamber (12) as a result of the hydraulic pressure of the water in the water chamber (16). An apparatus according to claim 2 or 3, wherein said container (10) includes a flexible wall (24) and is capable of being uni-directionally expanded and contracted.

Inventors: NAGATA TSUGIO, NAGATA, TSUGIO
Applicants: NAGATA TSUGIO, NAGATA, TSUGIO
Application year: 1991
Main classification: F04B17
IPC codes: F03B17, F04B9, F04F1, F04B17, F04B45