JP5265620B2 - Method and apparatus for manufacturing gas hydrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a dehydration effect comparable to a power dehydrator without using the power dehydrator. <P>SOLUTION: This method for manufacturing gas hydrate includes: a process in which a gas hydrate which is a hydrate of natural gas and water is formed by introducing the natural gas g and water w in a vertically long formation tower 6; a process in which the gas hydrate and unreacted water are sent out into a plurality of solid/liquid separation towers 53 which are set like a panel independent of the formation tower 6; a process in which unreacted water is removed from the gas hydrate by making the gas hydrate and unreacted water which are introduced in the respective solid/liquid separation towers flow into a filter 7 which is set near the exit of the solid/liquid separation towers; and a process in which the remaining gas hydrate in the filter is sent out to the next process using the upward flow of the unreacted water. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method and apparatus for producing a gas hydrate that is convenient for production, transportation, and storage in place of liquefied natural gas (hereinafter referred to as LNG) obtained by liquefying natural gas mainly composed of methane. .

  Conventionally, as a method for producing a gas hydrate, for example, (a) water is sprayed from a water jet pipe into an atmosphere of boil-off gas (hereinafter referred to as BOG) introduced into a hydrate production tank, and gas hydrate is produced. (B) a bubbling method for generating gas hydrate by blowing natural gas in a bubble form from a natural gas blowing pipe into a container in which water is stored. (Refer to Literature 2.) (c) A combination of bubbling and stirring in which natural gas is ejected in the form of bubbles from a gas discharge port into a pressure-resistant reaction vessel in which water is stored, and water in the pressure-resistant reaction vessel is stirred with a stirrer It has been known.

JP 2001-279277 A (page 3-7, FIG. 1) Japanese Unexamined Patent Publication No. 2000-304196 (page 2-3, FIG. 1)

  However, since the gas hydrate produced by any method is in the form of a slurry containing a large amount of water, it is generally unreacted by a power dehydrator such as a centrifugal dehydrator or a screw press. It is necessary to remove water, ie the mother liquor.

  However, a power-type dehydrator such as a centrifugal dehydrator or a screw press has a limited dehydration capability, and it is difficult to completely dehydrate unreacted water (mother liquor). In addition, power dehydrators such as centrifugal dehydrators and screw presses are uneconomical because of their large driving power and high power consumption.

  When removing unreacted water (mother liquor) using a power dehydrator such as a centrifugal dehydrator or a screw press, the moisture content of the gas hydrate after dehydration is about 30 to 25%. At this level of moisture content, the amount of gas contained in the gas hydrate is low, so the means for transporting the same amount of gas (transport containers and number of transports), the unit price of the storage tank and generated power (consumption per weight of raw natural gas) Power) and the like, and it will not be able to compete with existing energy such as LNG.

  The present invention has been made to solve such problems, and the object of the present invention is to achieve the same level as a power dehydrator without using a power dehydrator such as a centrifugal dehydrator or a screw press. A gas hydrate manufacturing method and apparatus that can significantly reduce the power required for dehydration of gas hydrate slurry and reduce the cost of manufacturing equipment by adopting a dehydration method that can achieve the dehydration effect of There is to do.

A method for producing a gas hydrate according to claim 1 is a method for producing a gas hydrate , in which natural gas and water are reacted to produce a gas hydrate that is a hydrate of natural gas and water. Water is introduced into a vertically long production tower, and a gas hydrate, which is a hydrate of natural gas and water, is produced in the production tower; independent of the production tower, and arranged in a panel shape. A step of sending gas hydrate and unreacted water into a plurality of solid-liquid separation towers installed, and an outlet of the solid-liquid separation tower for introducing the gas hydrate and unreacted water introduced into each solid-liquid separation tower A process of removing the unreacted water from the gas hydrate by flowing it into a filter provided nearby, and sending the gas hydrate remaining in the filter to the next process using the upward flow of unreacted water And the process of performing.

In the method for producing a gas hydrate according to claim 2 , the next step is a step of reacting the adhering water adhering to the wet gas hydrate with natural gas, and removing adhering water from the gas hydrate. And a step of supercooling the gas hydrate from which the adhering water has been removed .

As described above, the manufacturing method of the gas hydrate according to claim 1, introducing the natural gas and water to the vertically long the product column, hydrates of natural gas and water in the product column gas A step of generating hydrate, a step of sending gas hydrate and unreacted water into a plurality of solid-liquid separation towers independent of the generation tower and disposed in a panel shape, and each solid-liquid A step of allowing the gas hydrate and unreacted water introduced into the separation tower to flow into a filter provided near the outlet of the solid-liquid separation tower to remove unreacted water from the gas hydrate; Since the remaining gas hydrate is sent to the next process using the rising flow of unreacted water, there is no need to use a power dehydrator such as a centrifugal dehydrator or a screw press. A gas hydrate with a dehydration rate of about 70% It can be easily manufactured. The power required for the dehydration of the gas hydrate slurry can be greatly reduced as compared with the prior art, and the manufacturing equipment can be reduced in cost , and the following effects can be obtained.

  That is, in the case where the primary production tower and the filter are integrated, if an attempt is made to apply high-pressure (for example, 5 MPa) natural gas, the diameter of the primary production tower is about 9 m and the wall thickness thereof is also about However, if the primary production tower and the separation tower are separated as in the present invention, the diameter of the primary production tower is about 1 m and the wall thickness is about 34 mm. it can.

Further, the apparatus for producing gas hydrate according to claim 3, a) a hollow head portion, smaller in diameter than the head portion, and, from the bottom of the head portion of the elongated obtained by a predetermined length projecting into the head section A primary column is formed by the production cylinder, and a first circulation path for circulating unreacted water in the production cylinder is provided in the primary production column, and b) a separation tower made independent of the primary production tower Are provided in a panel form, and a cylindrical filter is provided in the vicinity of the outlet of each separation tower, and c) a gas hydrate comprising the gas hydrate produced in the primary production tower and unreacted water. with a rate slurry providing a slurry supply pipe for supplying to the separation column, since the unreacted water removed in the separation column provided with a return pipe for returning to said generator tube, the power of a centrifugal dehydrator or a screw press Do not use a dehydrator Even it is possible to easily produce the gas hydrate state dehydration rate was flaky of about 70%. With significantly reduced than in the conventional power required for dehydration of the gas hydrate slurry, the cost reduction of manufacturing facilities not only can FIG Rukoto, the following effects can be obtained.

  That is, in the case where the primary production tower and the filter are integrated, if an attempt is made to apply high-pressure (for example, 5 MPa) natural gas, the diameter of the primary production tower is about 9 m and the wall thickness thereof is also about However, if the primary production tower and the separation tower are separated as in the present invention, the diameter of the primary production tower is about 1 m and the wall thickness is about 34 mm. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(1) First, the gas hydrate production tower and the slurry mother liquor separation means will be described as an integral structure.

  As shown in FIG. 1, the gas hydrate production apparatus 1 of the present invention includes a primary generation tower 2, a secondary generator 3, and a supercooler 4. As shown in FIG. 2, the primary production tower 2 is provided with a cylindrical filter 7 as a slurry mother liquor separation means on the upper part of a gas hydrate production cylinder 6 that produces gas hydrate.

  More specifically, the primary generation tower 2 includes an airtight container-shaped head portion 5, a gas hydrate generation cylinder 6 having a smaller diameter than that of the head, and a cylinder having the same diameter as the gas hydrate generation cylinder 6. A filter 7, a first cooler 17, and a pump 18 are provided.

  The upper end portion of the gas hydrate generating cylinder 6 is inserted into the head portion 5 by a predetermined height upward from the bottom of the head portion 5. Further, a cylindrical filter 7 is provided between the upper end portion of the gas hydrate generating cylinder 6 and the delivery pipe 8 provided on the top plate of the head section 5.

  As the filter, for example, a cylindrical body made of a porous ceramic, a perforated plate made of metal such as stainless steel, a metal mesh, or the like is preferable. In short, unreacted water (also referred to as mother liquor) w and natural gas mainly composed of methane (hereinafter simply referred to as natural gas) g are permeated, but have a fine particle size (for example, 0.4 As long as it does not allow the gas hydrate a to pass through (about 1.0 mm).

  Further, a water supply pipe 9 and a gas supply pipe 10 are provided at the lower part of the gas hydrate production cylinder 6. The water supply pipe 9 is attached to the bottom of the gas hydrate generation cylinder 6 from the bottom to the top so that water w is supplied into the gas hydrate generation cylinder 6. On the other hand, the gas supply pipe 10 replenishes the natural gas g to the bubble generator 11 provided slightly above the bottom of the gas hydrate production cylinder 6.

  Any bubble generator may be used as long as the natural gas g is ejected into the water w in the form of fine bubbles, and examples thereof include a tube or a box having a large number of fine holes. Can do.

  A part of the unreacted natural gas g separated by the filter 7 is returned to the gas supply pipe 10 via the second circulation pipe 12, and the remaining natural gas g passes through the branch pipe 13 to the second. It is sent to the cooler 14 (see FIG. 1). The circulation path pipe 12 is provided with a circulation blower 15 and a circulation gas compressor (not shown).

  On the other hand, the unreacted water w separated by the filter 7 is stored in the head portion 5 and then returned to the middle of the water supply pipe 9 via the first circulation path pipe 16. The pipe 16 for the first circulation path is provided with a first cooler 17 and a circulation pump 18 in this order.

  Returning to FIG. 1, the secondary generator 3 and the subcooler 4 are horizontally provided above the primary generation tower 2 (upper side in the drawing). As shown in FIG. 3, the secondary generator 3 and the subcooler 4 have one common horizontal screw feeder 19 and two cooling jackets 20 and 21 on the outside thereof. The secondary gas hydrate generator 3 is constituted by the cooling jacket 20 on the upstream side, and the supercooler 4 is constituted by the cooling jacket 21 on the downstream side.

  The screw feeder 19 is configured to rotate a screw shaft 23 provided in a cylinder 22 by a motor 24. The cylinder 22 of the screw feeder 19 includes a pipe 8a connected to the delivery pipe 8 of the primary gas hydrate generator 2 at the upstream end thereof, and a discharge pipe for discharging the supercooled gas hydrate at the downstream end thereof. 26. Further, the cooled brine b is supplied to the cooling jackets 20 and 21.

  Returning to FIG. 1 again, the gas hydrate generator 1 includes a pellet molding machine 30. The pellets p granulated into a predetermined shape and size by the pellet molding machine 30 are stored in the storage tank 34 via the three conveyors 31, 32, 33. Any pellet molding machine may be used as long as it can mold powdered gas hydrate into a predetermined shape and size (for example, particle size: 5 to 50 mm).

  Although the explanation may be mixed, the pellet molding machine 30 is supplied with the powdered gas hydrate a supercooled by the supercooler 4 via the decompressor 35 and the conveyor 36. The unreacted natural gas a accompanying the gas hydrate a is sent out by the circulation blower 37, and a part thereof is returned to the gas supply pipe 10 already described through the pipe 38, that is, the raw material gas supply pipe, The remaining natural gas is introduced into the second cooler 14 via the pipe 39 and the branch pipe 13.

  The natural gas g cooled to a predetermined temperature by the second cooler 14 is supplied to the downstream side of the screw feeder 19 already described. In addition, as shown by a broken line, the pipe 40 connected to the secondary gas hydrate generator 3 may be communicated with the branch pipe 13 so that the natural gas that is not rehydrated is returned to the second cooler 14. .

  Then, the effect | action of this gas hydrate manufacturing apparatus is demonstrated.

  As shown in FIG. 2, when the circulation pump 18 provided in the primary production tower 2 is operated, the head portion 5, the pipe 16, and the gas hydrate production cylinder 6 constituting the primary production tower 2. The water w is circulated counterclockwise by the first cooler 17 to a predetermined temperature (a temperature slightly lower than the equilibrium temperature for hydrate formation, for example, about 5 ° C. if the equilibrium temperature is 7 ° C.). To be cooled.

  When the water w of the primary generation tower 2 is cooled to a predetermined temperature (for example, 0 to 10 ° C.), natural gas g having a predetermined gas pressure (for example, 2.5 to 7 MPa) is supplied from the valve generator 11. When jetted into the gas hydrate generating cylinder 6, the natural gas g reacts with the water w while rising in the gas hydrate generating cylinder 6 as fine bubbles, and is a hydrate of natural gas and water. A certain fine gas hydrate a is generated.

  The produced fine gas hydrate a flows upward along the vertically long gas hydrate producing cylinder 6 together with the unreacted water w. A so-called gas hydrate slurry s in which fine gas hydrate a and unreacted water w are combined (the concentration of the gas hydrate slurry s is about 25% at the outlet of the gas hydrate production tube 6). ) Reaches a cylindrical filter 7 provided in the vicinity of the outlet of the gas hydrate generating cylinder 6 to form a hydrate bed, and unreacted water w is filtered along with the natural gas g by a capillary phenomenon. The fine gas hydrate a is left in the cylindrical filter 7 through the vessel 7.

  These gas hydrates a are also accumulated below the lower side of the cylindrical filter 7 to form the bed layer e, but when the unreacted water w passes through the gas hydrate bed layer e. Since the bed layer e is pushed upward, the gas hydrate a dehydrated (dewatering rate is 70% or more) into the papasa is introduced from the filter 7 through the delivery pipe 8 to the upstream side of the screw feeder 19.

  The gas hydrate a of the papasa which has been transferred to the secondary generator 3 by the screw feeder 19 reacts with the adhering water w adhering to the gas hydrate a in the atmosphere of the natural gas g and the natural gas g. Gas hydrate a is produced. As a result, the adhering water w adhering to the surface of the fine gas hydrate a is removed, and a dry powdery gas hydrate (dehydration rate: about 95%) is obtained.

The gas hydrate that has become dry while passing through the secondary generator 3 is supercooled to a predetermined temperature, for example, about −20 ° C. while passing through the subcooler 4, and the gas hydrate self The preservation effect is improved. The supercooled gas hydrate a is granulated into pellets p (for example, 5 to 50 mm) by the pellet molding machine 30 and then stored in the storage tank 34 via the conveyors 31, 32 and 33. . The water w is replenished from the water supply pipe 9 and the natural gas g is replenished from the gas supply pipe 10 according to the amount of gas hydrate a produced.
(2) Next, a second embodiment of the present invention will be described with reference to the drawings (see FIG. 4 ).

  In the above description, the gas hydrate generator and the slurry mother liquor separation mechanism are integrated. However, the gas hydrate generator and the slurry mother liquor separation mechanism can be separated if desired.

  In the case where the gas hydrate generator and the slurry mother liquor separation mechanism have an integral structure, if an attempt is made to apply high-pressure (for example, 5 MPa) natural gas, the diameter of the gas hydrate generator 6 is about 9 m, and its thickness Therefore, the cost required for transportation and the equipment cost are significantly increased.

In order to avoid such high costs, it is important to separate the gas hydrate generator and the slurry mother liquor separation mechanism. As shown in FIG. 4 , in this embodiment, the primary generator 2 and the separation tower 50 are separated.

  The primary production tower 2 includes a hermetically sealed head portion 5a, a gas hydrate production cylinder 6 having a smaller diameter and a longer diameter, a stirring device 45, a first cooler 17, and a circulation pump 18. ing.

  The stirring device 45 is configured to rotate a stirring shaft 46 inserted into the gas hydrate generating cylinder 6 by a motor 47 installed in a sealed container 5a. The stirring shaft 48 includes a plurality of stirring blades 48. (Two stages in the figure) are provided.

  The upper end portion of the gas hydrate generating cylinder 6 is inserted into the head portion 5a by a predetermined height upward from the bottom thereof. On the other hand, the first cooler 17 and the circulation pump 18 are disposed in a first circulation path pipe 16 provided on the side surface of the gas hydrate generation cylinder 6. Further, the gas hydrate generation cylinder 6 is provided with a water supply pipe 9 and a gas supply pipe 10. The water supply pipe 9 is connected to the above-described circulation path pipe 16 to replenish water w. On the other hand, the gas supply pipe 10 is provided at the bottom of the gas hydrate production cylinder 6 so as to supply high-pressure (for example, 5 MPa) natural gas g.

  On the other hand, the separation tower 50 includes a horizontally long separated water collecting pipe 52 below the horizontally long screw conveyor 51. Then, a plurality (five in the figure) of solid-liquid separation towers 53 penetrating the separation water collecting pipe 52 are attached to the lower part of the screw conveyor 51 to form a panel structure. In addition, each solid-liquid separation tower 53 is provided with a cylindrical filter 7 at a location intersecting with the separated water collecting pipe 52.

  As the filter body, for example, a cylindrical body made of a porous ceramic, a perforated plate made of a metal such as stainless steel, a metal mesh, or the like is preferable. In short, unreacted water (also referred to as mother liquor) and natural gas mainly composed of methane (hereinafter simply referred to as natural gas) are permeated, but have a fine particle size (for example, 0.4 to 1). Any material that does not allow gas hydrate of about 0.0 mm) to pass therethrough may be used.

  Thus, in the gas hydrate generator 6, the fine gas produced by the reaction of the high-pressure (for example, 5 MPa) natural gas g and the water w cooled to a predetermined temperature (for example, 3 to 5 ° C.). The gas hydrate a overflows from the upper end portion of the gas hydrate generator 6 together with unreacted water (mother liquor) w into the head portion 5a and accumulates therein. A slurry composed of gas hydrate a and unreacted water (mother liquor) w in the head portion 5a, that is, gas hydrate slurry s (the concentration of the gas hydrate slurry s is about 25%). It is pumped out by the slurry pump 54 and supplied to the bottom of each solid-liquid separation tower 53 through the pipe 55.

  The gas hydrate slurry s supplied to the bottom of the solid-liquid separation tower 53 flows upward along the solid-liquid separation tower 53. And when it reaches the cylindrical filter 7 provided in the upper part of the solid-liquid separation tower 53, the unreacted water w permeate | transmits the cylindrical filter 7, and the fine gas hydrate a is a cylindrical filter. 7 is left behind. These gas hydrates a are also accumulated below the lower side of the filter 7 to form a bed layer e, but when the unreacted water w passes through the gas hydrate bed layer e, the bed layer e. The gas hydrate a dehydrated by the filter 7 and turned into a papasa is sent out to the secondary generator 3 by the horizontally long screw conveyor 51 provided at the top of the solid-liquid separation tower 53. The

  On the other hand, unreacted water w separated by the filter 7 is returned from the separated water collecting pipe 52 to the gas hydrate production tower 6 by the pump 56. The unreacted natural gas g sent from the primary generator 2 and the screw conveyor 51 is supplied to the second cooler 14.

(Example)
When the concentration of the slurry of the gas hydrate generated by the primary gas hydrate generator is 60%, 40%, and 30%, respectively, the refrigeration loads of the primary and secondary gas hydrate generators and the subcooler Were as indicated in Table 1.

  From this "Table 1", it can be seen that when the concentration of the gas hydrate slurry changes, the refrigeration load of each device changes, but there is no big difference as a total.

  As a result, although the refrigeration load is changed by removing the generated heat, the first and second sums of the generated heat are not changed, so the refrigeration load is not changed. In this embodiment, first, a hydrate slurry that is easy to handle is generated, dehydrated, and the second generator that further hydrates the highly concentrated slurry (about 95%) can be made a highly reliable facility. It was.

It is a schematic block diagram of the gas hydrate manufacturing apparatus which concerns on this invention. It is a schematic block diagram of a primary generator. It is a schematic block diagram of a secondary generator and a subcooler. It is a schematic block diagram of other embodiment of the gas hydrate manufacturing apparatus which concerns on this invention.

a Gas hydrate g Natural gas w Water 6 Production tower 7 Filter 53 Solid-liquid separation tower

Claims (2)

  In a gas hydrate production method for producing a gas hydrate which is a hydrate of natural gas and water by reacting natural gas and water, the natural gas and water are introduced into a vertically long production tower, A step of producing a gas hydrate which is a hydrate of natural gas and water in the production tower, and a gas in a plurality of solid-liquid separation towers independent of the production tower and arranged in a panel shape A step of feeding hydrate and unreacted water, and the gas hydrate and unreacted water introduced into each solid-liquid separation tower are caused to flow into a filter provided near the outlet of the solid-liquid separation tower to A method for producing a gas hydrate comprising a step of removing unreacted water from a rate, and a step of sending the gas hydrate remaining in the filter to the next step using an upward flow of unreacted water.   In the next step, the water adhering to the wet gas hydrate is re-reacted with natural gas to remove the adhering water from the gas hydrate, and the gas hydrate from which the adhering water has been removed is supercooled. The method for producing a gas hydrate according to claim 1, comprising the steps of:

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