JP2008248032A - Method for producing natural gas hydrate and device for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a gas hydrate having a high hydrate content in a short time and a device for the same. <P>SOLUTION: This method for producing the natural gas hydrate comprises a first process of introducing a raw material gas G and raw material water W in a reaction vessel 2 holding a prescribed pressure and temperature and bringing the raw material gas in contact with the raw material water W for forming a first slurry S1 containing powdery natural gas hydrate, and a second process of forming a liquid surface WL presenting the natural gas hydrate on the surface of the first slurry S1, bringing the liquid surface WL in contact with the raw material gas G and forming the second slurry P2 increased with the particle diameter of the natural gas hydrate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and apparatus for producing natural gas hydrate, and more specifically, a method for producing natural gas hydrate by reacting a raw material gas such as methane with raw water to produce a relatively coarse natural gas hydrate. And an apparatus for the same.

  In recent years, a gas mainly composed of methane such as natural gas has attracted attention as a clean energy source. And it is made into the liquefied natural gas (LNG) which liquefied this for the transport and storage of such a natural gas. However, since the transport and storage of gas by LNG requires a cryogenic state, not only the generation device but also the transport device and the storage device are expensive. As a result, it was limited to only large-scale gas fields, and was not economically feasible for relatively small-scale gas fields.

  From such a background, it has been studied to produce natural gas hydrate (NGH: hereinafter simply referred to as gas hydrate) by reacting natural gas and water, and to transport or store the gas by this gas hydrate. And roughly, two methods for producing gas hydrates have been proposed.

  The first is a gas-liquid stirring method, which is a method of stirring while blowing a raw material gas into the raw material water (for example, see Patent Document 1), and the second is a water spray method, in which the raw material is This is a method of spraying raw water into gas (for example, see Patent Document 2).

  By the way, according to these methods, although the expected gas hydrate can be generated, the generated gas hydrate is powdery and has a small particle size (for example, about 30 to 50 mμ). Since it is easy to vaporize, its handling is difficult. In particular, the gas hydrate produced by these methods is so-called “slurry” and is suspended and turbid in unreacted water, and is difficult to trap. This slurry is separated from unreacted water and gas hydrate. It was troublesome to do.

As a method for increasing the particle size of the gas hydrate, the applicant of the present invention uses a gas-liquid stirring method as an example to control the temperature in the reactor (see Patent Document 3), and flows to the downstream side of the reactor. Proposed a method (see Patent Document 4) in which a gas hydrate produced in the reactor is provided and a gas hydrate produced in the reactor is introduced into the fluidized bed reactor and fluidized with a source gas while controlling the temperature of the fluidized bed reactor did.
JP 2000-302701 A JP 2000-264852 A JP 2006-160821 A JP 2006-160820 A

  The invention described in Patent Document 3 is provided with a CCD camera in a reaction tank or in a circulating water line, and an image captured by the CCD camera is input to a particle size measuring instrument to determine the particle size of hydrate particles. The present invention provides a method for controlling the generation conditions in the reaction tank by inputting to the control unit. According to this method, the control conditions in the reaction tank can be controlled in relation to the particle size of the hydrate particles, but it does not provide means for positively growing the particle size of the gas hydrate particles.

  The invention described in Patent Document 4 controls the temperature in the fluidized bed reactor of a gas hydrate production apparatus in which a reaction tank, a separator, and a fluidized bed reactor are provided in series. A method for claiming particle size is provided. However, it does not provide a method for increasing the particle size of the gas hydrate in the reaction tank for producing the first slurry.

  Further, according to the knowledge of the present inventor, according to the gas hydrate production method in which the particle size of the gas hydrate described in Patent Documents 3 and 4 is increased, the operation for increasing the gas hydrate is performed. Since it took a long time, it turned out that it was difficult to use for practical use.

  Accordingly, an object of the present invention is to provide a method for efficiently growing a fine particle size of a gas hydrate. The present invention relates to a method and apparatus for producing natural gas hydrate, and more specifically, a natural gas hydrate produced by reacting a raw material gas such as methane with raw material water to produce a relatively coarse natural gas hydrate. The present invention relates to a manufacturing method and apparatus therefor.

  Therefore, as a result of intensive studies on the method for producing a gas hydrate in which the particle size of the gas hydrate is effectively increased, the present inventor has made the following invention.

(1) In the gas hydrate production method according to claim 1, the raw material gas and the raw water are introduced into a reactor maintaining a predetermined pressure and temperature, and the raw material gas and the raw water are brought into contact with each other to form a powder. A first step of producing a first slurry containing the gas hydrate, and forming a liquid level such that the gas hydrate exists on the surface of the first slurry, and using the liquid level as a source gas A second step of contacting to increase the particle size of the gas hydrate to produce a second slurry containing natural gas hydrate having an increased particle size, and introducing the second slurry into the separator It is characterized by comprising a third step of separating the gas hydrate and the raw water.

  According to the gas hydrate production method of the present invention, the powdered natural gas hydrate produced in the first step floats on the surface of the raw water and comes into contact with the raw material gas, and its particle size is rapid. To grow. Therefore, a large amount of natural gas hydrate can be produced in a short time.

(2) According to the invention of claim 3, the raw material gas and the raw water are introduced into the first reactor maintaining a predetermined pressure and temperature, and the raw material gas and the raw water are brought into contact with each other to form a powdery gas. A first step of producing a first slurry containing hydrate, and introducing the first slurry into a second reactor maintaining a predetermined pressure and temperature; Forming a liquid surface in which the gas hydrate is present and bringing the liquid surface into contact with a raw material gas to produce a second slurry having an increased gas hydrate particle size; and It is characterized by comprising a third step of introducing the second slurry into the separator to separate the gas hydrate and the raw water.

  According to the gas hydrate production method of the present invention, a powdery gas hydrate is generated in the first reactor, and a second slurry in which the particle size of the gas hydrate is increased is generated in the second reactor. Therefore, for example, it is suitable for adjusting the particle size of the gas hydrate by controlling the reaction temperature of the second reactor.

(3) According to the invention of claim 4, a stirrer is disposed in the lower part of the main body maintaining a predetermined pressure and temperature, and a raw material gas and raw material water are introduced to contain powdered gas hydrate. And a raw material gas layer is formed on the liquid surface of the first slurry to generate a second slurry having an increased gas hydrate particle size in the vicinity of the liquid surface of the first slurry. A gas hydrate production apparatus comprising: a reactor configured as described above, and a scraper blade disposed in the vicinity of the liquid surface; and a separator for separating the second slurry from gas hydrate and raw water.

  According to the gas hydrate production apparatus of the present invention, the second slurry having an increased particle size of the gas hydrate generated in the vicinity of the liquid surface of the first slurry is forcibly separated by the scrape blade on the downstream side. The powdered gas hydrate is not layered and deposited on the liquid surface of the first slurry so that it can be discharged into the vessel. Therefore, the powdered gas hydrate should be placed in the presence of raw material water and raw material gas. Can do. Therefore, the particle size of the gas hydrate can be increased rapidly.

(4) According to the invention of claim 5, a partition plate having an opening capable of flowing in the vertical direction is provided in a main body maintaining a predetermined pressure and temperature, and a stirrer is disposed below the partition plate, and a source gas and a source material Water is introduced, the liquid level of the first slurry containing powdered gas hydrate is positioned on the upper part of the partition plate, and a raw material gas layer is formed on the liquid level to form the first slurry. A reactor configured to generate a second slurry having an increased gas hydrate particle size in the vicinity of the liquid surface; a slurry discharge device connected in the vicinity of the liquid surface of the first slurry; The slurry is characterized by comprising a separator for separating gas hydrate and raw water.

  According to the guy hydrate production apparatus of the present invention, a first slurry containing gas hydrate is generated at the lower part of one reactor, and the gas hydrate in the first slurry passes through the opening of the partition plate. The particle size of the gas hydrate rapidly increases because it floats to the upper liquid level and reacts in the presence of the raw material gas and raw material water.

(5) The invention according to claim 6 contains a powdered gas hydrate by introducing a raw material gas and raw water into a main body maintaining a predetermined pressure and temperature, and bringing the raw material gas and raw material water into contact with each other. A first reactor for producing a first slurry, and the first slurry produced in the first reactor is maintained at a predetermined pressure and temperature, and the gas hydrate is formed on the surface of the first slurry. A second reactor that forms a liquid surface such that a rate is present and that contacts the raw material gas to produce a second slurry containing a gas hydrate of increased particle size; and The second slurry is constituted by a separator for separating natural gas and raw water.

  According to the gas hydrate production apparatus of the present invention, a powdery gas hydrate is produced in the first reactor, and then the second slurry in which the particle size of the gas hydrate is increased in the second reactor. For example, it is suitable when the particle size of natural gas hydrate is adjusted by controlling the reaction temperature.

  As is apparent from the above description, according to the method and apparatus for producing gas hydrate according to the present invention, powdered gas hydrate produced by a gas-liquid stirring method or a water spray method is converted into raw water and raw material gas. Therefore, the particle size can be increased rapidly. Therefore, the effect that it can be set as the manufacturing method and apparatus of the gas hydrate which can be provided for practical use is produced.

  Hereinafter, with reference to FIGS. 1-6, the manufacturing method of the gas hydrate by this invention, the principle of the apparatus, and its embodiment are demonstrated.

(Basic principle of the present invention)
FIG. 1 shows an apparatus for producing a liquid surface reaction type gas hydrate according to the present invention. This gas hydrate production apparatus 1 comprises a reactor 2 and a separator 3 such as a gravity dehydration tower. . A gas jet pipe 4 and a stirring blade 5 are provided in the lower part inside the reactor 2, and a scraping blade 6 is disposed in the vicinity of the liquid surface of the first slurry S1 generated in the raw water.

  The stirring blade 5 is attached to the tip of the inner shaft 8 rotated by the first driving machine 7, and the scraping blade 6 is attached to the tip of the outer shaft 10 rotated by the second driving machine 9, respectively. A discharge path 11 for a second slurry S2 described later is provided outside the reactor 2. In the reactor 2, the reaction proceeds even at a predetermined pressure and temperature, for example, a pressure and temperature selected within a range of 30 to 100 atm and a temperature of 1 to 10 ° C., that is, at the liquid level. Such conditions are maintained.

  The raw material gas G such as methane and the raw water W are supplied from the water supply line 13 to the reactor 2 configured as described above from the gas supply line 12. The raw material gas G is supplied from the gas layer 14 at the top of the reactor 2 through the gas line 15 to the gas jet pipe 4 disposed at the bottom of the reactor 2, and is supplied from the gas jet pipe 4 into the water layer 16. Is done. Then, the raw material gas G and the raw material water W react while being stirred by the stirring blade 5 to generate the first slurry S1 containing the powdered gas hydrate P1.

  As shown in FIG. 2, this powdery gas hydrate P1 rises in the water layer 16 and reaches the liquid level WL, where it contacts and hydrates in the presence of the raw material gas G and raw material water W. Thus, the particle size gradually increases. Then, a second slurry S2 containing the gas hydrate P2 having an increased particle size is produced. Thereafter, the second slurry S2 is discharged to the discharge path 11 by the scraping blade 4 rotating in the vicinity of the liquid level WL, and is passed through the slurry discharge line 17 connected to the discharge path 11 to the separator 3. The gas hydrate P2 and the separated water W1 are separated by gravity dehydration here, and the gas hydrate P2 passes through the hydrate take-out line 18 and, for example, a pellet manufacturing apparatus (see FIG. The separated water W1 is fed into the reactor 2 via the return line 19.

  What is important here is that the second slurry S2 is discharged to the discharge path 11 by the scraping blade 4 so that the powdery gas hydrate P1 always exists on the liquid level WL. That is, when the first slurry S1 is generated, the powdered gas hydrate P1 rises to the vicinity of the liquid level WL as shown in FIG. 3, and attempts to form the hydrate layer 20 there.

  However, when the hydrate layer 20 is formed, the powdered gas hydrate P1 is prevented from coming into contact with either the raw material gas G or the raw material water W. As a result, the particles of the gas hydrate P1 are prevented. This is because the diameter cannot be increased rapidly.

Example 1
FIG. 4 shows an apparatus 1A for carrying out the method for manufacturing the second gas hydrate P2 according to Embodiment 1 of the present invention, and is a schematic view of an embodiment different from the embodiment described in FIG. is there. In FIG. 4, the same reference numerals as those in FIG. 1 denote the same names.

  In FIG. 4, reference numeral 21 denotes a partition plate (a perforated plate having a mesh opening of 20 mm or a metal mesh) having an opening (not shown) that can flow in the vertical direction in the main body of the reactor 2. Is provided with a scraping blade 6 and a stirring blade 5 disposed below. The raw material gas G is supplied to the upper part of the main body and the raw material water W is supplied to the lower part, and the liquid level WL of the first slurry S1 containing the powdery gas hydrate P1 is located on the upper part of the partition plate 21. In addition, the raw material gas layer 14 is formed on the liquid level WL, and the scraping blade 6 is disposed in the vicinity of the liquid level WL.

  Accordingly, the powdered gas hydrate P1 present in the first slurry S1 generated below the partition plate 21 reaches the liquid level WL through the opening of the partition plate 21, where the raw material gas G and In the presence of the raw water W, the particle size is increased by a hydration reaction.

  According to the first embodiment, even when the stirring blade 5 is in operation, the liquid level WL is not perturbed by the action of the partition plate 21 made of a perforated plate, and is stable because it is stable. The particle size of the hydrate P1 can be increased more quickly, and it can be scraped by the scraping blade 6 and discharged sequentially to the discharge path 11.

(Example 2)
FIG. 5 shows an apparatus 1B for carrying out the manufacturing method of the second gas hydrate P2 according to the second embodiment of the present invention, which is different from the embodiment described in FIGS. It is the schematic of embodiment from which a part differs.

  That is, in FIG.1 and FIG.4, although the case where the 1st slurry S1 was produced | generated by the gas-liquid stirring system which inject | pours the gas G in the water W supplied to the main body and floats up in foam form was shown, FIG. 5 shows a case where the first slurry S1 is generated by spraying water W into the gas G by a spray method. In FIG. 5, the same reference numerals as those in FIGS. 1 and 4 denote the same names.

  In FIG. 5, reference numeral 22 denotes a water collecting plate having an opening (aperture 5 mm) and disposed on the liquid level WL of the first slurry S1, and 23 denotes a spray nozzle.

  In the gas hydrate production apparatus 1B configured as described above, a raw material gas layer 14 in which the raw material gas G is stored is formed in the upper portion of the reactor 2, and a spray tube 23 is formed in the raw material gas layer 14. From the raw material water W is sprayed. And while this raw material water W descend | falls in a mist state, it reacts with the raw material gas G and the fine powdery gas hydrate P1 is produced | generated.

  The mist droplets containing the fine powdery gas hydrate P1 are collected by the water collecting plate 22, and flow down from the small opening to form the first slurry S1. Thereafter, the powdery gas hydrate P1 present in the first slurry S1 rises to the liquid level WL, and comes into contact with the raw material gas G and the raw water W present at the lower part of the water collecting plate 22. A second slurry S2 containing gas hydrate P2 having an increased particle size is generated by hydration reaction and increasing the particle size. And this 2nd slurry S2 is discharged | emitted by the scraping blade 6 to the discharge path 11, and is supplied to the separator 3 via the slurry discharge line 17, and the unreacted raw material water W and the particle size increased. Separated into natural gas hydrate P2. Then, the gas hydrate P2 dehydrated in the separator 3 is transferred to the next step via the hydrate take-out line 18.

(Example 3)
FIG. 6 is a schematic view of an apparatus for carrying out the third gas hydrate production method according to the present invention according to the present invention. In FIG. 6, 40 is a first reactor, 41 is a second reactor, and 43 is a dehydrator.

  The first reactor 40 drives a stirring blade 46 fixed to the lower end of the shaft 45 by a drive 44, and supplies water W to the lower half of the reactor 40 through a water supply pipe 47. A gas G as a raw material is supplied through a gas supply pipe 48 to form a gas layer 57 above the water layer 49.

  Then, the water W and the gas G are brought into contact with each other on the water surface WL to cause a hydration reaction, thereby generating a first slurry S1 in which the gas hydrate P1 is dispersed in the water W. A drum-shaped discharge passage 51 is formed around the position of the water surface WL formed in the reactor 40, and through the slit or small hole opened in the main body of the reactor 40 toward the discharge passage 51. The slurry S1 is discharged to the discharge passage 51 while being separated and supplied from the bottom of the second reactor 41 via the slurry supply line 53 and the pump 54.

  Further, one end is connected to the top of the first reactor 40, and the gas G in the gas layer 57 is passed through the compressor 55 through the gas circulation line 56 to the fine bubbles in the water W from the gas ejection nozzle 58. The first slurry S1 containing the gas hydrate P1 is generated by hydrating the water W and the gas G to form a first slurry S1. And slurry S1 produced | generated in this reactor 40 is supplied from the bottom part of the 2nd reactor 41 through the slurry supply line 53 and the pump 54, and a 2nd reaction is performed here.

  In the second reactor 41, the first slurry S1 floating near the water surface is stirred while the scraping blade 63 is rotated by the driving device 62, and the gas circulation line of the first reactor 40 is stirred at this portion. A second slurry S2 containing a gas hydrate P2 is produced by a hydration reaction with the gas G supplied from 56.

  The second slurry S2 is discharged to a discharge path 64 provided around the main body near the liquid surface, supplied from the bottom of the dehydrator 43 via the slurry line 65 and the pump 66, and dehydrated by gravity dehydration. The gas hydrate P2 is transferred to the next process from the hydrate take-out line 67. Further, the water W dehydrated by the dehydrator 43 is supplied to the first reactor 40 as the raw water W via the reflux line 68 and the pump 69.

  The conditions of “pressure and temperature” of the first reactor 40 and the second reactor 41 are as follows. When it repeats, in the series of gas hydrate manufacturing apparatuses configured as described above, the raw material gas G is supplied from the gas layer 57 of the first reactor 40 to the gas ejection pipe 58 via the gas circulation line 56, The gas jet pipe 58 is supplied into the water layer 49. Then, the raw material gas G and the raw material water W are stirred by the stirring blade 5 to generate the first slurry S1 containing the powdered gas hydrate P1.

  Then, the first slurry S1 produced here is supplied to the second reactor 41 through the slurry extraction line 53, and the powdered gas hydrate rising above the liquid level in the second reactor 41 is supplied. The rate P1 is present in the upper part and includes gas hydrate P2 having a particle size increased (increased from 30 to 50 μm to 80 to 300 μm) by contacting the raw material gas G and the raw water W and performing a hydration reaction. 2 slurry S2 is produced.

  In the above description, the first reactor 41 is a gas-liquid stirring method. However, the first reactor 40 may be a spray method in which water is sprayed into a gas as necessary.

  By configuring the reactor 40 as shown in FIG. 6, the operation is simplified, and the quality of the first slurry S1 and the second slurry S2 can be accurately controlled.

It is the schematic of the apparatus for enforcing the manufacturing method of the 1st gas hydrate by this invention. It is operation | movement explanatory drawing of the slurry liquid surface in the case of implementing the manufacturing method of the 1st gas hydrate by this invention. It is another action explanatory view of the slurry liquid level at the time of carrying out the manufacturing method of the 1st gas hydrate by the present invention. It is the schematic of the apparatus for enforcing the manufacturing method of the 1st gas hydrate by this invention. It is the schematic of the 3rd apparatus for enforcing the manufacturing method of the 2nd gas hydrate by this invention. It is the schematic of the apparatus for enforcing the manufacturing method of the 3rd gas hydrate by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas hydrate manufacturing apparatus 2 Reactor 3 Separator 4 Gas ejection pipe 5, 30 Stirring blade 6 Scraping blade 11 Discharge path 12 Gas supply line 13 Water supply line 14, 35 Gas layer 15, 34 Gas line 16 Water layer 17 Slurry discharge line 18 Hydrate take-out line 19 Water return line 20 Hydrate layer 21 Partition plate 22 Water collecting plates 23 and 24 Spray nozzle 25 Supply pump 26 Slurry supply line 40 First reactor 41 Second reactor 43 Dehydrator

Claims (5)

  A raw material gas and raw material water are introduced into a reactor that maintains a predetermined pressure and temperature, and the raw material gas and raw material water are brought into contact with each other to produce a first slurry containing powdered natural gas hydrate. The first step and forming a liquid level such that the natural gas hydrate exists on the surface of the first slurry, and increasing the particle size of the natural gas hydrate by bringing the liquid level into contact with the raw material gas A method for producing natural gas hydrate, comprising a second step of producing a second slurry that has been produced.   A first slurry containing powdered natural gas hydrate by introducing raw material gas and raw water into a first reactor maintaining a predetermined pressure and temperature and bringing the raw material gas and raw water into contact with each other. And the first slurry is introduced into a second reactor maintained at a predetermined pressure and temperature so that the natural gas hydrate is present on the surface of the first slurry. A second step of forming a second slurry in which the liquid surface is brought into contact with the raw material gas to increase the particle size of the natural gas hydrate, and a separator for separating the second slurry And a third step of separating the natural gas hydrate and the raw water into the natural gas hydrate manufacturing method.   A raw material gas and raw water are introduced into a main body maintaining a predetermined pressure and temperature to produce a first slurry containing powdered natural gas hydrate, and on the liquid surface of the first slurry. A raw material gas layer is formed to form a second slurry in which the particle size of the natural gas hydrate is increased in the vicinity of the liquid surface of the first slurry, and a scraping blade is disposed in the vicinity of the liquid surface. An apparatus for producing natural gas hydrate, comprising: a reactor; and a separator for separating natural gas hydrate and raw water from the second slurry.   A partition plate having an opening that can flow in the vertical direction is provided in a main body that maintains a predetermined pressure and temperature, a stirrer is disposed at the lower portion of the partition plate, and source gas and source water are introduced, and the partition plate The liquid level of the first slurry containing powdered natural gas hydrate is positioned on the upper part, and a raw material gas layer is formed on the liquid level, and the natural gas hydrate is formed in the vicinity of the liquid level of the first slurry. A reactor configured to generate a second slurry having an increased particle size, a slurry discharge device connected in the vicinity of the liquid surface of the first slurry, and a natural gas hydrate and a raw material for the second slurry A natural gas hydrate manufacturing apparatus comprising a separator for separating water.   A raw material gas and raw water are introduced into a main body that maintains a predetermined pressure and temperature, and the raw material gas and raw water are brought into contact with each other to generate a first slurry containing powdered natural gas hydrate. 1 and the liquid level such that the natural gas hydrate is present on the surface of the first slurry while maintaining the first slurry produced in the first reactor at a predetermined pressure and temperature. And forming a second slurry containing natural gas hydrate having an increased particle size by bringing the liquid surface into contact with the raw material gas, and the second slurry as natural gas A natural gas hydrate production apparatus comprising a separator for separating into raw water.

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