JP2010229255A - Gas hydrate pellet molding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas hydrate pellet molding device that makes it possible to improve efficiency in molding GH pellets at high concentration by performing a gas hydrate dehydration process and a GH pellet molding process with a single device. <P>SOLUTION: The device includes an inner cylinder 3 made of a perforated plate, which is connected to a water squeezing cylinder 4 having an inner diameter greater than that of the inner cylinder 3 and without having conduction pores; and a die plate 5 disposed across the water squeezing cylinder 4 from the inner cylinder 3; and is divided into a compression chamber 6 and a pellet receiving chamber 7 by the die plate 5, wherein the chambers 6, 7 each includes a compression plunger 8 and a die opening and closing plunger 10 slidably placed therein. The die opening and closing plunger 10 is pressed against the die plate 5 to close, and the compression plunger 8 is moved forward to compress GH slurry supplied to the compression chamber 5 and squeeze the water out from the GH slurry. When water is squeezed while the compression plunger 8 is located in the water squeezing cylinder 4, water flows out through a space between the compression plunger 8 and the inner wall of the water squeezing cylinder 4, and is discharged to the back of the compression plunger 8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

In the present invention, for example, natural gas hydrate existing under the seabed or artificially produced gas hydrate (natural gas hydrate, CO ₂ hydrate) is generated in a state suitable for transportation and storage. More specifically, the present invention relates to a gas hydrate pellet forming apparatus that forms pellets while removing moisture from a slurry-like gas hydrate.

  Natural gas hydrate (NGH), the main component of which is methane, exists under the seabed at a depth of 500 m or less in frozen land zones such as Siberia, Canada, and Alaska and in the continental area. This NGH is a stable gas or clathrate hydrate composed of gas molecules such as methane and water molecules under low temperature and high pressure, and is attracting attention as a clean energy that emits less carbon dioxide and air pollutants. Yes.

  Natural gas, after being liquefied, is stored and used as energy, but its production and storage are performed at an extremely low temperature of -162 ° C. On the other hand, natural gas hydrate has the advantage that it exhibits stable properties without being decomposed at −20 ° C. and can be handled as a solid. Because of these properties, it is possible to effectively use gas resources in undeveloped small and medium-sized gas fields, especially for reasons such as profitability existing all over the world, or as a means to make effective use of short-distance and small-lots from large gas fields. As a means of transport, a method of transporting natural gas in a hydrate (NGH transport) is expected.

  In NGH transportation, an NGH suitable for transportation and storage is generated at an NGH shipping base such as a small and medium gas field, and then formed according to circumstances and transported to a desired NGH receiving base by a transport ship or a vehicle. On the other hand, at the NGH receiving terminal, the transported NGH is stored and gasified as necessary to be used as an energy source, or small-scale transportation by vehicles or the like is further performed as it is. FIG. 7 is a schematic block diagram illustrating an example of the configuration of a gas hydrate generation plant used in the NGH shipping base. The mined raw material gas is sufficiently mixed with water and hydrated in a generator 31 which is a high-pressure reaction vessel, and a low concentration gas hydrate (GH) slurry is generated. The generated GH slurry is supplied to the dehydrator 33 by the supply pump 32 to generate a dehydrated high-concentration GH slurry. At this time, the dehydrator 33 is supplied to the lowermost part of the dehydrator 33. The supplied GH slurry is dehydrated while gradually raising the dehydrator 33, and is taken out from the upper end of the dehydrator 33. The extracted gas hydrate is extracted as, for example, GH powder that has been dehydrated and powdered. This GH powder is supplied to the pelletizer 34 and granulated to form GH pellets of an appropriate size for transportation and storage. Next, after being cooled by the cooler 35 to a temperature at which it does not decompose even under normal pressure, it is supplied to the decompressor 36. That is, from the generator 31 to the cooler 35, processing is performed under gas hydrate production conditions (for example, 5MPa, 8 ° C in the case of NGH), and the normal pressure is reduced by the cooler 35 and the decompressor 36. However, it is processed at a temperature at which decomposition is difficult (for example, in the case of NGH, −20 ° C.). Thereafter, the generated GH pellets are fed to a storage tank and stored.

  By the way, this applicant has proposed the manufacturing method and manufacturing apparatus of the gas hydrate pellet which can manufacture the pellet excellent in storability at low cost (refer patent document 1). In this method for producing gas hydrate pellets, the gas hydrate is dehydrated by compression molding means under the production conditions and is molded into pellets. Further, as the compression molding means, a briquetting roll having a plurality of pellet molding dies on the outer peripheral surface and comprising a pair of rolls rotating in directions opposite to each other.

  Patent Document 2 discloses a method for producing carbon dioxide clathrate, and discloses a configuration in which carbon dioxide clathrate fine particles are compressed and consolidated to form a carbon dioxide clathrate lump in the assembly chamber. Has been.

  However, in the conventional process, each device of the dehydrator 33 and the pellet former 34 is required, and the gas hydrate production plant is increased in size.

  On the other hand, in the gas hydrate pellet manufacturing apparatus described in Patent Document 1, since dehydration and pellet molding are performed by compression molding means, it is not necessary to dispose a dehydrator individually, but mass production is assumed. In such a case, there is a problem that the facility becomes large-scale.

  Furthermore, both Patent Document 1 and Patent Document 2 disclose a reciprocating pellet manufacturing apparatus. In this reciprocating type, dehydration and molding can be performed reliably while compressing, but since this method is so-called batch processing, there are the same problems as described above.

  In view of such a problem, the present applicant is a gas hydrate pellet molding apparatus that compresses and forms pellets while removing moisture from the gas hydrate slurry, and includes an outer cylinder and an inner cylinder, An inner cylinder is formed of a perforated plate, a die plate is disposed at an appropriate position in the longitudinal direction of the inner cylinder, a pressing chamber for supplying a gas hydrate slurry across the die plate, and the gas hydrate slurry And a pellet receiving chamber for storing pellets generated from slab, a squeezing plunger is slidably provided in the squeezing chamber, a die opening / closing means for opening and closing the die plate is provided in the pellet receiving chamber, and conveyed to the pellet receiving chamber Means for opening and closing the outlet side of the die plate by the die opening and closing means, and by sliding the squeezing plunger, Presses Lee said die plate, and proposed gas hydrate pellets forming apparatus in which the above was accommodated in a pellet receiving chamber pellets to provide the transport means (Patent Document 3).

JP2007-270029A Japanese Patent No. 3241108 Japanese Patent Application No. 2008-295060

  In the gas hydrate forming apparatus described in Patent Document 3, it is possible to continuously form gas hydrate pellets, but the inner cylinder is used to discharge water squeezed by pressurization of the squeezing plunger. The structure is arranged up to the die plate. For this reason, if the pressure is increased to increase the gas hydrate concentration, the gas hydrate may be pushed out from the through hole of the inner cylinder, so the squeezing force cannot be increased and the gas hydrate concentration is limited. There is a risk that. In addition, when the squeezing force is increased, it is necessary to increase the wall thickness in order to ensure the strength of the inner cylinder in which the through-holes are formed, resulting in a device having a robust structure.

  On the other hand, in order to obtain a sufficient pressure-resistant structure even when the squeezing force is increased, a structure in which the through hole of the inner cylinder near the die plate is not provided. In this case, since the strength of this portion can be ensured, the thickness can be reduced and the structure can be simplified.

  However, in the case where the through hole is not formed, if the squeezing force is increased to increase the concentration of the gas hydrate, since the through hole is not formed in the inner cylinder, the squeezed water may escape. Can not. That is, since water cannot be discharged, the concentration cannot be increased. Alternatively, the gas hydrate pellets formed through the die plate may be accompanied.

  Accordingly, an object of the present invention is to provide a gas hydrate pellet molding apparatus that can eliminate water squeezing even when squeezed at a high pressure and can increase the concentration of gas hydrate. It is said.

  As a technical means for achieving the above object, a gas hydrate pellet molding apparatus according to the present invention is a gas hydrate pellet molding apparatus that compresses and forms pellets while removing moisture from a gas hydrate slurry. An outer cylinder having a pressure-resistant structure and an inner cylinder made of a perforated plate and a squeezing cylinder having a diameter larger than that of the inner cylinder, and the squeezing cylinder is disposed continuously to the inner cylinder, A die plate is disposed on the opposite side of the inner cylinder, and a compression chamber for supplying gas hydrate slurry between the inner cylinder and the squeezing cylinder with the die plate as a boundary, and the gas hydrate on the opposite side of the compression chamber A pellet receiving chamber for storing pellets generated from the slurry, a squeezing plunger provided slidably in the squeezing chamber, and a die opening / closing means for opening and closing the die plate in the pellet receiving chamber. Then, the conveying means is connected to the pellet receiving chamber, the outlet side of the die plate is opened and closed by the die opening and closing means, and the gas hydrate slurry in the inner cylinder is pressed against the die plate by sliding of the pressing plunger. In addition, the pellets accommodated in the pellet receiving chamber are provided to the conveying means.

  When gas hydrate (GH) slurry is supplied to the compression chamber in a state where the compression plunger is farthest away from the die plate, that is, in a position where it is retracted to the end, it is accompanied by the GH slurry. Moisture passes through the through hole of the inner cylinder and is discharged into the outer cylinder, and the concentration of the GH slurry is increased. The GH slurry is supplied to the squeezing chamber by a raw material gas and water supplied to a generator and produced by reaction under high pressure, or a natural gas hydrate collected from the seabed. When the GH slurry is supplied to the pressing chamber, the die plate is closed by the operation of the die opening / closing means. For this reason, GH slurry does not flow into the pellet receiving chamber. When the desired amount of GH slurry has been supplied, the supply of GH slurry is stopped and the pressing plunger is advanced by sliding it toward the die plate. Thereby, the supplied GH slurry is squeezed and water is squeezed out and discharged from the through hole of the inner cylinder. This drainage is performed until just before the pressing plunger reaches the water bottle.

  When the squeezing plunger further advances and reaches the water squeezing cylinder, the GH slurry is further pressurized, and the water contained in the GH slurry is squeezed out to further increase the concentration. At this time, since the squeezing cylinder is expanded in diameter compared to the inner cylinder, that is, a gap is formed between the inner wall of the squeezing cylinder and the squeezing plunger, The water thus made passes through this gap and flows out to the back side of the pressing plunger.

  When the GH slurry is increased to a desired concentration, the die opening / closing means is operated to open the die plate, and the compression chamber and the pellet receiving chamber are communicated with each other. When the pressing plunger is further advanced in this state, the substantially solid GH slurry is pushed out from the die plate to the pellet receiving chamber. Therefore, the rod-like GH slurry is extruded into the pellet receiving chamber through the die plate, cut into a suitable length by its own weight, and formed into pellets. The pellets are fed to the next process by the conveying means.

  Further, the gas hydrate pellet forming apparatus according to the invention of claim 2 is characterized in that the inner cylinder side end of the squeezing cylinder is gradually expanded toward the die plate to form a truncated cone shape. It is said.

  When the pressing plunger moves backward after pushing out the GH pellet from the die plate, it reaches the inner cylinder while being guided by the frustoconical portion.

  According to the gas hydrate pellet forming apparatus according to the present invention, since the GH slurry can be pressurized with the squeeze plunger just before the die plate, the concentration of the gas hydrate can be further increased. Generation efficiency can be improved. In addition, since the most pressurized portion is used as a squeezing cylinder and no through-hole is formed, the thickness of the squeezing cylinder can be made smaller than that of the inner cylinder, thereby reducing the size of the gas hydrate pellet molding apparatus. Can be achieved.

  Moreover, according to the gas hydrate pellet shaping | molding apparatus which concerns on invention of Claim 2, a retraction operation | movement of a pressing plunger can be performed smoothly, and the smooth operation of a gas hydrate pellet shaping | molding apparatus can be performed.

It is a figure explaining the schematic structure of the gas hydrate pellet shaping | molding apparatus which concerns on this invention, and has shown the state in which GH slurry is supplied. The state where the GH slurry is squeezed in the inner cylinder portion by the gas hydrate pellet forming apparatus shown in FIG. 1 is shown. The state where the GH slurry is squeezed in the portion of the squeezing cylinder by the gas hydrate pellet forming apparatus shown in FIG. 1 is shown. The state which shape | molds a pellet with the gas hydrate pellet shaping | molding apparatus shown in FIG. 1 is shown. It is a figure which shows other embodiment of the gas hydrate pellet shaping | molding apparatus which concerns on this invention, and is a figure equivalent to FIG. It is a figure which shows the preferable structure of the die plate used for the gas hydrate pellet shaping | molding apparatus concerning this invention. It is a schematic block diagram explaining an example of the structure of the conventional gas hydrate production | generation plant utilized for the shipping base of a natural gas hydrate.

  The gas hydrate pellet forming apparatus according to the present invention will be specifically described below based on the preferred embodiments shown in the drawings.

  FIG. 1 is a cross-sectional view illustrating a schematic structure of a pellet forming apparatus 1 according to the present invention. The pellet forming apparatus 1 includes an outer cylinder 2 made of a pressure vessel and an inner cylinder 3 accommodated in the outer cylinder 2. The inner cylinder 3 is formed of a perforated plate such as punching metal. A through-hole formed in the perforated plate serves as a communication portion that communicates the inside of the inner cylinder 3 and the inside of the outer cylinder 2. A drainage chamber 3a is provided between the outer cylinder 2 and the inner cylinder 3 by being partitioned by an appropriate number of partition walls 3b. In FIG. 1, the partition walls 3b are provided along the longitudinal direction of the cylinder so that the intervals are narrowed toward the die plate. Moreover, although the density of the hole of a perforated plate may be equal intervals in the longitudinal direction of a cylinder, it is preferable to make the die plate side mentioned later into a higher density.

  A water squeezing cylinder 4 having an inner diameter that is wider than the inner diameter of the inner cylinder 3 is connected to the end of the inner cylinder 3. In addition, in this embodiment, although it is set as the structure where the outer cylinder 2 serves as this squeezing cylinder 4, you may provide this squeezing cylinder 4 as a separate body inside the outer cylinder 2.

  On the opposite side of the inner cylinder 3 across the water squeezing cylinder 4, a die plate 5 in which a large number of molding holes for molding GH pellets is formed is fitted. A chamber formed by the inner cylinder 2 and the squeezing cylinder 4 is a squeezing chamber 6, and a chamber on the opposite side of the squeezing chamber 6 across the die plate 5 is a pellet receiving chamber 7. A compression plunger 8 is arranged in the inner cylinder 3 of the compression chamber 6, and the compression plunger 8 is moved in the axial direction of the inner cylinder 3 by reciprocation of the drive rod 9 a by the operation of the compression cylinder 9 composed of a hydraulic cylinder or the like. It is possible to slide. The pellet receiving chamber is provided with a die opening / closing plunger 10 as a die opening / closing means, and the die opening / closing plunger 10 is operated by reciprocating a drive rod 11a by an operation of an opening / closing cylinder 11 such as a hydraulic cylinder. 3 is slidable in the axial direction. The squeezing plunger 8 approaches the inlet side surface of the die plate 5 by its sliding, and advances and retreats away from the die plate 5. The die opening / closing plunger 10 advances and retreats between a position pressed against the outlet side surface of the die plate 5 and a position separated from the die plate 5.

  Below the pellet receiving chamber 7, a screw conveyor 12 is disposed as a conveying means. The conveying means is not limited to this, and a pipe that is simply inclined downward may be provided, and the pellets may be sent to the downstream equipment by sliding down along the inner wall.

  The operation of the pellet forming apparatus 1 in the gas hydrate production plant according to the present invention configured as described above will be described below.

  FIG. 1 shows a filtration process in which the pellet forming apparatus 1 filters water accompanying the GH slurry (for example, 5% slurry, GH concentration in the slurry is 5 wt%) while supplying the GH slurry to the compression chamber 6. Shows the state. The squeezing plunger 8 is in a slurry receiving position which is retracted and is most separated from the die plate 5, and the die opening / closing plunger 10 is pressed against the outlet side surface of the die plate 5 to close the die plate 5. In this state, if the GH slurry is continuously supplied while being pressed into the pressing chamber 6, the water contained in the GH slurry passes through the through hole of the inner cylinder 3 without being subjected to the reaction when the GH slurry is generated. Then, it is filtered and dehydrated by flowing into the drainage chamber 3a. The discharged water is discharged from the drain chamber 3a. The discharged water can be recovered and used again to generate GH slurry.

  When water is separated to some extent (for example, 30% slurry, GH concentration in the slurry is 30 wt%) and the compression chamber 6 is filled with GH slurry, the GH slurry supply system and the water discharge system are closed and compressed. The chamber 6 is sealed and moved to a pressing process. In a pressing process, as shown in FIG. 2, in the state where the pressing chamber 6 was sealed, the pressing plunger 8 was advanced to squeeze water while pressurizing the GH slurry. Here, the GH slurry is pressurized by the advance of the squeezing plunger 8, and the water remaining in the GH slurry is squeezed out. The compressed water passes through the through hole of the inner cylinder 3 and flows out into the drainage chamber 3a.

  After the squeezing plunger 8 has advanced to the position shown in FIG. 2, the squeezing plunger 8 will advance in the squeezing cylinder 4 and further pressurize the GH slurry (FIG. 3). For example, if it is squeezed to about 70% (GH concentration is 70 wt%) when sliding to the end of the inner cylinder 3, it is further squeezed by sliding inside the squeezing cylinder 4 It is assumed that the water is squeezed to about 90% (GH concentration is 90 wt%). Since the inner diameter of the squeezing cylinder 4 is wider than the inner diameter of the inner cylinder 3, a gap is formed between the inner wall surface of the squeezing cylinder 4 and the outer peripheral surface of the squeezing plunger 8. For this reason, the water squeezed when the squeezing plunger 8 moves forward in the squeezing cylinder 4 flows out to the back side of the squeezing plunger 8 through this gap. And if it squeezed to about 90% (GH density | concentration is 90 wt%) by squeezing in this squeezing cylinder 4, it will transfer to the pellet formation process shown in FIG.

  In this pellet forming step, the die opening / closing plunger 10 is retracted and separated from the die plate 5, the GH slurry supply system is opened, and the GH slurry is supplied. When the squeezing plunger 8 further advances in this state, the squeezed GH slurry is pressed by the die plate 5 and is pushed out from the outlet side of the die plate 5 to a pellet receiving chamber 7. When it is extruded and has an appropriate length, it is cut by its own weight to form a pellet P, which falls onto the screw conveyor 12. The dropped pellet P is conveyed to the next process by the screw conveyor 12. Further, in this step, it is preferable that the rod-like GH pellet pushed out into the pellet receiving chamber 7 is appropriately cut to a length by mechanical means such as a chopper (not shown).

  Moreover, when the pressing plunger 8 moves forward to the foremost part, a gap is formed between the inlet side surface of the die plate 5 and the pressing plunger 8. For this reason, the molding hole of the die plate 5 becomes clogged with the GH slurry, and the molding hole of the die plate 5 is maintained in a state of being blocked by the GH slurry. Thereby, the pressing chamber 5 and the pellet receiving chamber 7 do not communicate, and the pressure in the pressing chamber 5 is maintained. At this time, the compression plunger 8 may be a position slightly separated from the die plate 5.

  When the molding process is completed, the compression plunger 8 is retracted. Prior to the retraction, the die opening / closing plunger 4 is advanced and pressed against the die plate 5 to close the die plate 5. If the pressing plunger 8 is retracted to the slurry receiving position, the above-described processing steps are repeated by returning to the above-described filtration step of opening the supply system and supplying the GH slurry.

  5 shows another embodiment of the water squeezing cylinder 4, and the same parts as those in the embodiment shown in FIGS. As shown in the figure, the water squeezing cylinder 15 is gradually expanded toward the die plate 5 to form a truncated cone-shaped plunger guide portion 15a.

  For this reason, when the squeezing plunger 8 that has advanced to the portion of the squeezing cylinder 15 moves backward, it is guided by the plunger guide portion 15a and is smoothly positioned inside the inner cylinder 3.

  FIG. 6 shows a preferable shape of the molding hole 5a formed in the die plate 5. That is, it is preferable to form the forming hole 5a in a drawing shape so as to gradually reduce the diameter toward the outlet side of the die plate 5. Thereby, when it passes through the shaping hole 5a and is formed into a pellet, it is further squeezed to further increase the concentration of the gas hydrate. Further, in order to increase the concentration of gas hydrate, the molding hole 5a formed in the die plate 5 preferably has an opening ratio of 20 to 30%.

  According to the gas hydrate pellet forming apparatus according to the present invention, a gas hydrate pellet having a high concentration can be formed. Therefore, a gas hydrate with high energy efficiency can be generated in a simple process, and the gas hydrate can be produced. Contributes to effective use of

DESCRIPTION OF SYMBOLS 1 Pellet molding apparatus 2 Outer cylinder 3 Inner cylinder 4 Squeezing cylinder 5 Die plate
5a Molding hole 6 Squeeze chamber 7 Pellet receiving chamber 8 Squeeze plunger 9 Squeeze cylinder
9a Piston rod
10 Die opening / closing plunger
15 water bottle
15a Plunger guide (conical frustum)

Claims (2)

A gas hydrate pellet forming apparatus that compresses and forms pellets while removing moisture from a gas hydrate slurry,
An outer cylinder having a pressure-resistant structure, an inner cylinder made of a perforated plate, and a water squeezing cylinder having a diameter larger than that of the inner cylinder,
The water squeezing cylinder is arranged continuously to the inner cylinder, and a die plate is arranged on the opposite side of the inner cylinder across the water squeezing cylinder,
A pressing chamber that supplies gas hydrate slurry between the inner cylinder and the squeezing cylinder with the die plate as a boundary, and a pellet receiving chamber that stores pellets generated from the gas hydrate slurry on the opposite side of the pressing chamber; Provided,
A slidable squeezing plunger is provided in the squeezing chamber, a die opening / closing means for opening and closing the die plate is provided in the pellet receiving chamber, a conveying means is connected to the pellet receiving chamber, and an outlet of the die plate is connected by the die opening / closing means. The gas hydrate slurry in the inner cylinder is pressed against the die plate by sliding the squeezing plunger, and the pellets accommodated in the pellet receiving chamber are supplied to the conveying means. Gas hydrate pellet forming equipment.   2. The gas hydrate pellet forming apparatus according to claim 1, wherein the inner cylinder side end of the water squeezing cylinder is gradually enlarged toward the die plate to form a truncated cone shape.

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