JP2007254503A - Apparatus for producing gas hydrate pellet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve filling ratio in a storage container for gas hydrate pellets. <P>SOLUTION: The apparatus for producing the gas hydrate pellets is composed of the following: a plurality of pelletizers 5 for compression molding of a gas hydrate produced by subjecting a raw material gas and water to a hydration reaction and producing the gas hydrate pellets having different diameters, respectively and a mixer for dispersing the gas hydrate pellets fed from each of the pelletizers 5 in the axial direction of a rotating shaft 64, stirring and mixing the gas hydrate pellets with a plurality of radially mounted portal blades 65. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gas hydrate pellet manufacturing apparatus for compressing and molding a gas hydrate produced by hydrating a raw material gas and water.

  A gas hydrate is a solid hydrate having a structure in which gas is taken into a cage formed by water molecules, and is stable under atmospheric pressure of -20 ° C to -10 ° C. Research is being carried out to use it as a means of transporting and storing natural gas instead of gas (LNG).

  As a method for producing such a gas hydrate, as described in Patent Document 1, first, a gas hydrate slurry containing a relatively large amount of water is prepared by reacting a raw material gas with water in a first generator. After the water is separated from the gas hydrate slurry by the dehydrator, the raw material gas is supplied again to the dehydrated gas hydrate by the second generator, and the raw material gas and the unreacted water are reacted to form a powder. It is known to form a gas hydrate in the form of a gas.

  Further, in Patent Document 1, the powdered gas hydrate thus produced is cooled to a predetermined low temperature with a cooler, depressurized to atmospheric pressure with a depressurizer, and then gas hydrate is obtained with a pellet manufacturing apparatus. Is molded into gas hydrate pellets of a predetermined size and shape and stored in a storage container.

JP 2005-263675 A

  The technology of Patent Document 1 considers the convenience at the time of gas hydrate transportation by molding powdered gas hydrate into gas hydrate pellets, but when storing gas hydrate pellets in a storage container There is a problem that the filling rate is not considered.

  That is, Patent Document 1 does not describe any specific molding means for powdered gas hydrate and specific storage means for the molded gas hydrate pellets. Therefore, for example, it is conceivable to form powdered gas hydrate into pellets such as spherical or elliptical spheres and store them in storage containers as they are, but this creates gaps between the gas hydrate pellets in the storage containers. The filling rate is not good.

  This invention makes it a subject to improve the filling rate in the storage container of a gas hydrate pellet.

  In order to solve the above problems, the gas hydrate pellet manufacturing apparatus of the present invention generates gas hydrate pellets of different diameters by compression molding gas hydrates produced by hydration reaction of raw material gas and water. A plurality of pelletizers, and a mixing device for mixing the gas hydrate pellets supplied from each pelletizer.

  That is, gas hydrate pellets having different diameters are generated by a plurality of pelletizers, and these gas hydrate pellets are mixed in a mixing device so that small diameter gas hydrate pellets are placed between large diameter gas hydrate pellets. The resulting void is filled. Therefore, the filling rate in the storage container of gas hydrate pellets can be improved.

  In this case, the mixing device includes a horizontal cylindrical container, a rotating shaft inserted in the axial direction of the cylindrical container, a blade member attached to the outer peripheral surface of the rotating shaft, and a gas hydrate pellet provided at one end of the cylindrical container. It is desirable to include a supply port through which gas is supplied and a discharge port provided at the other end of the horizontal container to discharge gas hydrate pellets. Further, the blade member is a portal blade or a rotation shaft in which a pair of leg portions of a plurality of rod-shaped members formed by bending in a gate shape are dispersed in the axial direction of the rotation shaft and attached radially around the shaft. It is desirable to use a spiral screw blade integrally formed in the axial direction.

  According to this, gas hydrate pellets having different diameters supplied from the supply port are conveyed to the discharge port while being agitated and mixed by the portal blades or screw blades. The space between them is filled with gas hydrate pellets having a small diameter. Therefore, the filling rate in the storage container of gas hydrate pellets can be improved.

  The mixing apparatus preferably includes a cooling gas circulation blower that extracts the cooling gas supplied from the bottom of the cylindrical container from the upper part of the cylindrical container and circulates it through the cooler to the bottom of the cylindrical container.

  According to this, since each gas hydrate pellet is agitated by the rotation of the gate blade or the screw blade, the cooling operation by the cooling gas is promoted in addition to the mixing operation. Therefore, the filling rate of the gas hydrate pellets in the storage container can be improved and the gas hydrate pellets can be cooled to a desired temperature. As a result, the mixing device and the cooler can be provided as a single unit without being provided separately.

  ADVANTAGE OF THE INVENTION According to this invention, the filling rate in the storage container of a gas hydrate pellet can be improved.

  Hereinafter, an embodiment of a gas hydrate pellet manufacturing apparatus to which the present invention is applied will be described with reference to FIGS. FIG. 1 is a diagram showing an overall configuration of a gas hydrate pellet manufacturing plant to which a gas hydrate pellet manufacturing apparatus of the present invention is applied. In addition, although this embodiment demonstrates as a plant which manufactures the natural gas hydrate (henceforth NGH) pellet using natural gas as raw material gas, this invention is not restricted to natural gas, Other raw material gas It can also be applied to hydrate pellet manufacturing.

  As shown in FIG. 1, the hydrate pellet manufacturing plant 1 of the present embodiment includes a first generator 2 that generates an NGH slurry, and a dehydrator 3 that separates moisture from the NGH slurry generated by the first generator 2. And a second generator 4 for further increasing the concentration of the NGH slurry dehydrated by the dehydrator 3, and a high pressure for compressing and molding the NGH slurry obtained by the second generator 4 with different diameters to generate NGH pellets. Pelletizers 5a and 5b, NGH pellet mixing and cooling device 6 for cooling NGH pellets having different diameters discharged from high-pressure pelletizers 5a and 5b, respectively, and NGH pellet removal for depressurizing the mixed and cooled NGH pellets to atmospheric pressure. A pressure device 7 and an NGH pellet storage tank 8 are provided. The first generator 2 to the NGH pellet mixing and cooling device 6 are both maintained at a predetermined high pressure (for example, 3 to 10 MPa) and a predetermined low temperature (for example, 0 ° C. to 10 ° C.).

  In the first generator 2, when a high-pressure raw material gas (natural gas) and high-pressure water are introduced, a reaction is performed under the low-temperature and high-pressure conditions in the first generator 2 to generate slurry-like NGH. At this time, in the 1st generator 2, reaction is accelerated | stimulated by stirring with a stirrer, bubbling natural gas in water. Further, since the generation of NGH involves heat generation, the NGH slurry is extracted from the bottom of the first generator 2 by a circulating slurry pump or the like, cooled by a heat exchanger, and then returned to the first generator 2. Further, the unreacted natural gas and the water recovered by the subsequent apparatus are reused in the first generator 2 as a raw material gas and raw water, respectively. The NGH slurry generated in the first generator 2 in this way is continuously extracted by a slurry transfer pump or the like and supplied to the dehydrator 3.

  The dehydrator 3 is a vertical cylindrical container, and the NGH slurry is supplied to the bottom thereof. Since NGH has a specific gravity smaller than that of water, it rises in the dehydrator 3 and is fed from the upper part to the second generator 4 further downstream by a screw feeder or the like. On the other hand, water is discharged out of the dehydrator 3 from a drainage portion formed by a metal mesh or a perforated plate provided in the middle of the dehydrator 3.

  In the second generator 4, the NGH slurry dehydrated by the dehydrator 3 is flowed while blowing natural gas, thereby further promoting the NGH generation reaction and increasing the concentration of the NGH slurry. The natural gas blown here is normally discharged from the second generator 4, cooled by a heat exchanger, and supplied again to the second generator 4 by a circulating gas blower or the like. At that time, the NGH powder flowing out with the natural gas is collected by a cyclone or the like and then returned to the second generator 4.

  The NGH obtained in this way is supplied to the high-pressure pelletizers 5a and 5b on the downstream side by a screw feeder or the like.

  Next, the high pressure pelletizers 5a and 5b will be described with reference to FIG. Both the high-pressure pelletizers 5 a and 5 b are composed of a container 50, two rolls 52 having a plurality of molds 51, a motor 53 that rotates the rolls 52, and the like. Here, the mold 51a of the high-pressure pelletizer 5a and the mold 51b of the high-pressure pelletizer 5b have different diameters. For example, the diameter of the mold 51a is 50 mm to 70 mm, and the diameter of the mold 51b is 5 mm to 20 mm. Is preferred. Although not shown, the outer periphery of the container 50 is surrounded by a jacket, and the inside of the container 50 is kept at a predetermined low temperature by circulating a refrigerant through the jacket.

  The NGH slurry supplied from the second generator 4 through the discharger 30 is pushed downward while being compressed by the two rolls 52 rotating in the direction indicated by the arrow 55 in each of the high pressure pelletizers 5a and 5b. The NGH pellets are formed by the two forming dies 51 at the portion where the roll 52 substantially contacts, and are discharged from the lower portion of the container 50.

  The NGH pellets supplied from the high pressure pelletizers 5 a and 5 b are supplied to the NGH pellet mixing and cooling device 6.

  Next, the NGH pellet mixing and cooling device 6 will be described in detail with reference to FIGS. The NGH pellet mixing and cooling device 6 includes a horizontal cylindrical container 60, an NGH pellet supply port 61 is provided at the top of one end of the cylindrical container 60, and an NGH pellet discharge port 62 is provided at the bottom of the other end. A rotating shaft 64 rotated by a motor 63 is inserted into the cylindrical container 60 in the axial direction of the cylindrical container 60 and is rotatably supported. Around the rotation shaft 64, a plurality of portal blades 65 are provided that are radially distributed and dispersed in the axial direction.

  The gate-shaped blade 65 is formed in a gate shape by bending a rod-shaped member, and is attached to the outer peripheral surface of the rotary shaft with the pair of gate-shaped legs facing the axial direction of the rotary shaft 64. As shown in FIG. 2, the gate-shaped blade 65 is configured such that a pair of gate-shaped blades 65 are mounted symmetrically on the rotation shaft 64, and the mounting angle between the gate-shaped blades 65 shifted in the axial direction is 90 °, for example. Alternatively, it can be attached with a shift of 60 ° or the like. Further, in place of the gate-shaped blade 65, as shown in FIG. 3, a so-called T-shaped (hammer-shaped) blade 66 formed by fixing a short rod-shaped or plate-shaped member at the tip of the rod-shaped member can be used. . In particular, by combining the portal blade 65 and the T blade 66, a better stirring effect can be realized.

  Further, in addition to the gate-shaped blade 65 and the T-shaped blade 66, for example, a spiral screw blade formed integrally in the axial direction of the rotating shaft 64 may be used.

  Further, baffle plates 67 having a diameter smaller than the inner diameter of the cylindrical container 60 are fixed between the plurality of portal blades 65 at appropriate positions (two locations in the illustrated example) fixed to the rotary shaft 64. Further, a semicircular dam plate 68 is provided at a position closer to the NGH pellet supply port 61 side than the NGH pellet discharge port 62, rising from the bottom surface of the cylindrical container 60.

  The cylindrical container 60 is supplied with natural gas (NG), which is a raw material gas, via a cooler 69. In the cooler 69, a refrigerant is circulated from a refrigeration apparatus (not shown), whereby the raw material gas supplied to the cylindrical container 60 is cooled to a predetermined temperature (for example, −40 ° C. to −25 ° C.). Yes. In addition, a cooling gas circulation blower 70 for extracting the raw material gas in the container from the upper part of the cylindrical container 60 is provided, and the raw material gas extracted by the cooling gas circulation blower 70 is supplied to the diffuser 72 via the cooler 71. To be supplied. The air diffuser 72 is configured, for example, by forming a plurality of pores in the pipe wall of one or a plurality of pipe lines, and in the gap between the bottom surface in the cylindrical container 60 and the tip of the portal blade 65, the cylindrical container 60 extends in the axial direction.

  Further, the outer periphery of the cylindrical portion of the cylindrical container 60 is surrounded by a jacket 73, and the inside of the cylindrical container 60 is cooled to a predetermined temperature by circulating and supplying a refrigerant from a refrigeration apparatus (not shown) into the jacket 73. It is like that. Note that the inside of the cylindrical container 60 is maintained at a predetermined high pressure (for example, 3 to 10 MPa) as in the upstream process.

  The NGH pellets having different diameters supplied from the high pressure pelletizers 5a and 5b to the NGH pellet mixing and cooling device 6 are gradually conveyed to the NGH pellet discharge port 62 side while being stirred and mixed by the portal blade 65 in the cylindrical container 60. Is done. Each NGH pellet is cooled to a desired temperature by exchanging heat with natural gas diffused from the air diffuser 72 and cooled by the cooler 71 in the process of being conveyed while being stirred. Here, the weir plate 68 secures the amount of NGH pellets held in the cylindrical container 60 to a constant value, so that the contact efficiency between the NGH pellets and the cooling gas in the cylindrical container 60 and the NGH pellets having different diameters differ from each other. Promotes stirring and mixing. Therefore, the height of the barrier plate 68 is set in accordance with the cooling condition of the NGH pellets and the mixing condition of the NGH pellets having different diameters.

  The NGH pellets thus stirred and mixed and cooled to a desired temperature are discharged from the NGH pellet discharge port 62 and supplied to the NGH pellet decompressor 7. Then, it is depressurized to the atmospheric pressure by the NGH pellet depressurizer 7, becomes an NGH pellet as a product, and is stored in the NGH pellet storage tank 8. Although not shown, the outer circumferences of the NGH pellet depressurizer 7 and the NGH pellet storage tank 8 are surrounded by a jacket or a trace, and the refrigerant is circulated through the jacket to circulate the refrigerant in the NGH pellet depressurizer 7 and the storage tank 8. The inside is kept at a predetermined low temperature.

  As described above, NGH pellets having different diameters are agitated, so that NGH pellets having different diameters are mixed with each other without biasing NGH pellets having the same diameter. As a result, the gap between the large-diameter NGH pellets and the gap formed between the large-diameter NGH pellet and the wall of the NGH pellet storage tank 8 are filled with the small-diameter NGH pellet. The filling rate of the NGH pellets when stored in 8 can be improved.

  In the present embodiment, the case where two high-pressure pelletizers 5 for generating NGH pellets having different diameters are provided has been described as an example. However, the present invention is not limited thereto, and the filling rate of the NGH pellets in the NGH pellet storage tank 8 and It is also possible to increase the number as appropriate in consideration of convenience during transportation.

It is a figure which shows the whole structure of the gas hydrate pellet manufacturing plant formed by applying the gas hydrate pellet manufacturing apparatus of this invention. It is a figure explaining the gas hydrate pellet manufacturing apparatus of this invention in detail. It is a figure explaining one specific embodiment of the gate type feather of this embodiment. It is a figure explaining other embodiment replaced with the portal blade | wing of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydrate pellet manufacturing plant 5 High pressure pelletizer 6 NGH pellet mixing cooling device 60 Cylindrical container 61 NGH pellet supply port 62 NGH pellet discharge port 64 Rotating shaft 65 Gate type blade 70 Cooling gas circulation blower 71 Cooler

Claims (4)

A plurality of pelletizers that generate gas hydrate pellets of different diameters by compression molding gas hydrates generated by hydration reaction of raw material gas and water, and the gas hydrate pellets supplied from each of the pelletizers A gas hydrate pellet manufacturing apparatus comprising: a mixing apparatus for mixing the components. The mixing device includes a horizontal cylindrical container, a rotating shaft inserted in the axial direction of the cylindrical container, a blade member attached to an outer peripheral surface of the rotating shaft, and the gas hydride provided at one end of the cylindrical container. The gas hydrate pellet according to claim 1, further comprising: a supply port for supplying a rate pellet; and a discharge port provided at the other end of the horizontal container to discharge the gas hydrate pellet. Manufacturing equipment. The blade member is a gate-shaped blade in which a pair of leg portions of a plurality of rod-shaped members formed in a gate shape are dispersed in the axial direction of the rotation shaft and attached radially around the shaft, or the rotation 3. The gas hydrate pellet manufacturing apparatus according to claim 2, wherein the apparatus is a spiral screw blade integrally formed toward the axial direction of the shaft. The said mixing apparatus is equipped with the cooling gas circulation blower which extracts the cooling gas supplied from the bottom part of the said cylindrical container from the upper part of the said cylindrical container, and circulates to the bottom part of the said cylindrical container through a cooler. Or the gas hydrate pellet manufacturing apparatus of 3.

Images