JP3876348B2 - Gas hydrate manufacturing method and manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas hydrate production method and apparatus for producing a gas hydrate by reacting a raw material gas such as natural gas with water.
[0002]
[Prior art]
The gas hydrate is an ice-like substance that contains gas molecules such as natural gas and carbon dioxide in a high concentration inside the cage structure formed by water molecules. Gas hydrate can contain a large amount of gas per unit volume, and it can be stored and transported at a relatively high temperature under atmospheric pressure compared to liquefied natural gas. Therefore, it can be applied to transport and storage of natural gas, etc. Attention has been paid.
For this reason, hitherto, studies have been focused on the use of naturally occurring gas hydrates, but in recent years, attempts have been made to produce them industrially by paying attention to this property.
[0003]
The outline of the conventional gas hydrate production process is as follows. Raw gas such as natural gas and water are kept in the hydrate generation range indicated by the equilibrium curve while keeping the temperature and pressure of gas and water in contact with each other. To generate gas hydrate. The generated so-called sherbet-like gas hydrate is separated and dehydrated from unreacted gas and raw material water, further subjected to freezing and molding, and stored in a storage facility. And it is carried out and transported from the storage facility as necessary.
[0004]
By the way, in the gas hydrate manufacturing process, the most important factors governing the gas hydrate production rate are the diffusion and dissolution rate of the gas into water and the heat removal efficiency that takes away the heat of reaction when the gas and water react. is there.
[0005]
As a technique for efficiently producing gas hydrate by increasing the gas dissolution rate in water and the heat removal efficiency at the time of gas hydrate production, for example, natural gas hydrate disclosed in Japanese Patent Application Laid-Open No. 2001-10985 shown in FIG. There is an invention of a rate manufacturing apparatus and manufacturing method.
The invention of this publication includes a pressure vessel 51, a porous plate 55 that divides the pressure vessel 51 into a gas space 56 and a gas-liquid contact space 52, and coil evaporation arranged in two or more stages in the gas-liquid contact space 52. 53, a refrigerator 58 for supplying a refrigerant to this, a gas hydrate storage tank 62 connected to the outlet of the gas-liquid contact space 52 via a buffer tank 59, and water at the bottom of the gas-liquid contact space The gas hydrate production units A, B, and D having a raw water supply pipe 61 for supplying to the bottom in 52 and a raw gas supply pipe 57 for supplying natural gas to the gas space 56 are made according to the component gas of the natural gas. A plurality of pipes are connected, and a gas extraction pipe 70 is connected to the upper space of each storage tank 62, and this is connected to a regenerative gas mixer 66 in the downstream.
[0006]
[Problems to be solved by the invention]
However, the above prior art has the following problems.
As described above, the generation rate is determined by the diffusion and dissolution rate of gas in water and the heat removal efficiency that takes away the heat of reaction during gas hydrate generation.
In this regard, in the above prior art, in order to promote gas diffusion and dissolution in water, a method of increasing the contact area between water and gas by generating fine gas bubbles by the porous plate 55 is employed. Adopted.
However, in the method of introducing bubbles through such a porous plate 55, the bubble diameter that can be generated is not so small, and the effect of promoting gas dissolution by expanding the gas-liquid interface area cannot be expected.
On the other hand, a space for installing the porous plate 55 having a certain area or more is required, and a gas-liquid contact space 52 for contacting the gas-liquid in the pressure vessel 51 needs to be secured at a certain level or more. Therefore, there is a problem that it is necessary to increase the volume of the pressure vessel 51, and the equipment becomes large.
Further, hydrate adheres and grows on the porous plate 55, and in the worst case, the holes may be blocked.
[0007]
Moreover, although removal of reaction heat at the time of gas hydrate generation is an important factor, since the volume of the pressure vessel 51 as a reaction tank is large, sufficient cooling cannot be performed only by cooling the wall surface of the pressure vessel.
For this reason, in the conventional example described above, means for installing the refrigerant circulation coil 53 inside the pressure vessel 51 for directly cooling water and gas is adopted, but the problem is that the apparatus becomes larger and complicated. There is.
[0008]
As another problem, when gas hydrate is generated in a pressure vessel, the generated gas hydrate floats on the water surface in the pressure vessel, and means for taking it out (for example, gas hydrate and water) And the like, and a device for controlling the water surface to that position, etc., are also required, and there is also a problem of complication of the device.
Thus, in the prior art, there is a problem that the facilities are complicated and large.
[0009]
The present invention has been made to solve such a problem, and is capable of efficiently diffusing / dissolving gas in water and removing generated reaction heat, and manufacturing a gas hydrate that can make the apparatus simple and compact. The object is to obtain a method and apparatus.
[0010]
(1) The gas hydrate production method according to the present invention is a method for producing gas hydrate by reacting raw material water and raw material gas, and mixing raw material water and raw material gas by a line mixer in the middle of the line. Mixing / dissolving step for dissolving gas in raw water, step of generating gas hydrate by cooling the mixed / dissolved flow through the reaction pipe, and the generated gas hydrate is unreacted gas, raw material And a process of flowing through a pipeline with water and sending it to a separator.
[0011]
(2) In the method of producing gas hydrate by reacting raw material water and raw material gas,
Raw material water and raw material gas are mixed by a line mixer in the middle of the line to dissolve the raw material gas in the raw material water, and the mixed and dissolved material is cooled while flowing into the reaction pipe to cool the gas hydrate. And a separation and dehydration step in which the generated slurry gas hydrate is separated and dehydrated into a high-concentration slurry or solid by a separator, and the reaction is performed while moving the reaction between the raw water and the raw material gas. In addition, since all of the hydrate, unreacted gas and raw water are once sent to the separator, a mechanism for taking out only the generated gas hydrate is unnecessary.
[0015]
(3) In the method for producing gas hydrate by reacting raw material water and raw material gas,
The raw gas is dissolved in the raw water using a line mixer, and the gas hydrate is generated by cooling the peripheral surface of the pipe using a pipe-like reaction pipe. The rate flows along the unreacted gas and the raw water along the pipeline and is sent to the separator.
[0018]
(4) Further, in any of the above (1) to (3), among the gas hydrate, unreacted gas, and raw water separated by the separator, the raw water and the unreacted gas are again in the line. It is supplied to a mixer.
[0019]
(5) Further, in the separator as described in (4) above , in the separator, the water level in the separator is at a certain level at a level at which the raw water has a sealing effect so that the gas does not flow into the raw water return line. It is controlled as described above.
[0020]
(6) In the above (4) or (5), the source gas boosted by the gas booster is supplied directly to the separator.
[0024]
(7) In any of the above (1) to (6), the mixing by the line mixer is performed by mixing the raw material gas into the fine bubbles by stirring the raw water and entraining the raw material gas therein. Is dissolved in raw material water.
[0025]
(8) Moreover, the gas hydrate manufacturing apparatus according to the present invention includes a line mixer that mixes raw water and raw material gas and dissolves the raw material gas in the raw water, and cools a gas hydrate mixed by the line mixer. Characterized by comprising a reaction pipe for generating a rate and a separator for separating gas hydrate, unreacted gas, and raw water generated in the reaction pipe, and each component device is connected by a pipe. To do.
[0026]
(9) Further , in the above (8), the line mixer generates fine bubbles.
[0027]
(10) In the above (8) or (9) , the separator is any one of a decanter, a cyclone, a centrifuge, a belt press, a screw concentrator / dehydrator, and a rotary dryer. Is.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 5 is an explanatory view of the outline of the gas hydrate production process according to the embodiment of the present invention, and shows a case where natural gas is used as a raw material gas. First, the outline of the gas hydrate manufacturing process will be described with reference to FIG.
Natural gas is cooled to 1 to 10 ° C. and heavy components are separated as condensate (S1). On the other hand, the water is also cooled to 1 to 10 ° C. (S2), and the cooling water and natural gas react at 1 to 10 ° C. and 50 atm to generate gas hydrate (S3). The generated slurry-like gas hydrate is separated and dehydrated to form a highly concentrated slurry or solid (S4), and the water and unreacted gas separated here are returned to the reaction step (S3) again.
[0029]
The separated and dehydrated gas hydrate is frozen at a temperature of about −15 ° C. (S5). This freezing treatment is intended to stabilize the gas hydrate by freezing the water adhering to the surface of the gas hydrate that has been separated and dehydrated in S4 to form an ice shell.
After the freezing process, a depressurizing process is performed to depressurize from 50 atm to atmospheric (S6). Thereafter, the frozen gas hydrate is formed into pellets (S7), stored in a storage facility such as a silo (S8), and loaded on a loading facility such as a belt conveyor as required (S9). It is used for long-distance transportation by a transportation device such as a transportation ship (S10).
The above is the outline of the gas hydrate manufacturing process, but this embodiment is devised in the process (S3) of generating slurry gas hydrate from water and natural gas in the above process. Hereinafter, this point will be described in detail.
[0030]
FIG. 1 is a system diagram showing main components of an embodiment of the present invention. First, the component apparatus of this Embodiment is demonstrated based on FIG.
The gas hydrate production apparatus of the present embodiment includes gas boosters 1 and 2 that increase the pressure of a raw material gas such as natural gas, raw material water pumps 3 and 19 that supply raw water, and a mixture of raw water and raw material gas. The line mixer 5 for dissolving the raw material gas in the raw material water, the reaction line 7 for generating the gas hydrate by cooling the material mixed in the line mixer 5, the gas hydrate generated in the reaction line 7, unreacted A separator 9 for separating gas and raw water is provided.
Each component device is connected by a pipe indicated by a solid line with an arrow in the figure, and a pressure detector 10 is installed at a key point, and each valve 12 installed in the pipe line by a signal of the pressure detector 10. Is controlled, and the pressure and flow rate of the piping line are adjusted.
[0031]
The configuration of main components among the above-described components will be described in more detail.
As shown in FIG. 2 (cited from page 7 of “OHR Line Mixer” catalog of Nishika Sangyo Co., Ltd.), the line mixer 5 of the present embodiment has a two-stage shape with a large diameter on the inlet side and a small diameter on the outlet side. A plurality of mushrooms comprising a cylindrical body 11 and having a wing body 13 called a guide vane in a large diameter portion 11a of the cylindrical body 11, and extending from the inner peripheral surface of the cylinder to the center in a small diameter portion 11b. A colliding body 15 is provided.
In such a line mixer 5, the raw water supplied to the line mixer 5 by the raw water pump 3 is swirled by the wing body 13 and pushed outward by a violent centrifugal force, which is a mushroom-like collision body 15. The raw material gas is engulfed therein and crushed into ultrafine bubbles, and the raw material water and the raw material gas are mixed. As a result, the contact area between the source gas and the source water is increased, and the source gas is efficiently dissolved in the source water.
[0032]
The reaction pipe 7 is composed of one or a plurality of bent pipes, and the peripheral surface of the pipe is cooled by a chiller 17. As described above, since the reaction pipe 7 is used, cooling from the surroundings can be performed efficiently, so that it is not necessary to directly cool the gas / raw material water by a cooling coil or the like as in the conventional example. The configuration can be made simple and compact.
[0033]
Such a reaction pipe line 7 can be used because the raw material gas and the raw water are mixed and dissolved by the line mixer 5 in advance, and the reaction pipe line 7 can be conceived with an apparatus configuration centering on cooling. Because. That is, in the conventional example, mixing / dissolution and reaction cooling of the raw material gas and raw material water are performed in a tank-shaped pressure vessel, so that a space with a certain spread is required for mixing / dissolution, and cooling is performed in the reaction vessel. In the present embodiment, the mixing / dissolution of the raw material gas and the raw material water and the reaction cooling are separated from each other. As described above, cooling with a simple configuration is possible.
[0034]
The separator 9 separates gas hydrate, unreacted gas, and raw water. Examples of the separator 9 include a decanter, a cyclone, a centrifuge 9, a belt press, a screw concentrator / dehydrator, A rotary dryer or the like can be considered.
[0035]
Next, a manufacturing process for manufacturing a gas hydrate by the apparatus of the present embodiment configured as described above will be described.
The pressure of the source gas is increased to a predetermined pressure by the gas booster 1. The raw water is also boosted to a predetermined pressure by the raw water pump 3. These pressurized source gas and source water are respectively supplied to the line mixer 5. The raw material gas and the raw water supplied to the line mixer 5 are mixed with a violent momentum by the mechanism described above. At this time, the raw material gas becomes fine bubbles and is mixed into the raw material water, and the dissolution of the raw material gas is promoted.
[0036]
A raw material gas dissolved in raw water (containing fine bubbles) is sent to the reaction pipe 7 and cooled by a chiller 17 to generate gas hydrate. And the gas hydrate produced | generated here flows through a pipe line with unreacted gas and raw material water, and is sent to the separator 9. FIG.
As described above, in the present embodiment, the reaction between the raw water and the raw material gas is performed while being moved through the pipe line. Therefore, in this gas hydrate generation step, everything (generated gas hydrate, unreacted) Gas and raw water) are once sent to the separator 9, and a mechanism for taking out only the generated gas hydrate as in the conventional example is unnecessary, and the configuration of the apparatus can be simplified.
[0037]
The mixture of gas hydrate, unreacted gas, and raw water sent to the separator 9 is separated by the separator 9 into gas hydrate, unreacted gas, and raw water. The separated raw material water is supplied again to the line mixer 5 by the pump 19, and the unreacted raw material gas is pressurized to a predetermined pressure by the gas booster 2 and supplied to the line mixer 5.
On the other hand, the generated gas hydrate is taken out from the separator 9 and sent to a post-processing step (steps after S5 in FIG. 5).
In the separator 9, the water level in the separator 9 is detected by the level meter 21, and the water level in the separator 9 is controlled to be a certain level or higher. This is because the raw water has a sealing effect so that the gas does not flow into the raw water return line. The raw water unnecessary for the sealing water is boosted to a predetermined pressure by the raw water pump 19 and supplied to the line mixer 5.
[0038]
In addition, the source gas boosted by the gas booster 1 is directly supplied to the separator 9 in order to keep the pressure in the separator 9 at a certain level or higher.
[0039]
As described above, according to the present embodiment, since the raw material gas is dissolved in the raw material water continuously by the line mixer 5 made of a cylindrical body, it can be performed in a space-saving and efficient manner. it can.
Further, as a result of dissolving the raw material gas in the raw material water by the line mixer 5 separate from the reaction tank, a pipe-like reaction line 7 can be used instead of the conventional reaction tank, A simple and compact cooling means for cooling the peripheral surface is possible.
Moreover, since both the melting of the raw material gas by the line mixer 5 and the generation of the gas hydrate in the reaction pipe line 7 are continuously performed, the production efficiency of the gas hydrate can be dramatically increased.
[0040]
In the above embodiment, no means for adjusting the pressure is provided between the line mixer 5 and the reaction pipe 7.
However, as shown in FIG. 3, a pressure adjusting means 27 including a pressure detector and an adjusting valve 25 may be provided between the line mixer 5 and the reaction pipe line 7.
By providing the pressure adjusting means 27, the pressure on the line mixer 5 side can be increased, and dissolution of the raw material gas into the raw water by the line mixer 5 can be further promoted.
[0041]
Further, in order to further promote the dissolution of the raw material gas into the raw material water, as shown in FIG. 4, a staying portion 29 as a flow rate adjusting means for reducing the flow rate of the fluid flowing through the line downstream of the line mixer 5 is provided. It may be provided. By providing the staying part 29, it is possible to earn time for the raw material gas that has become fine bubbles in the line mixer 5 to be dissolved in the raw material water, thereby promoting dissolution.
In addition, as a specific example of the retention part 29, the tank which has a fixed volume can be considered.
[0042]
In the above description, the temperature and pressure in each step are not particularly specified, but an example is shown in FIG. However, optimum values for the temperature and pressure in each process are selected according to various conditions.
In the above embodiment, natural gas mainly composed of methane gas has been described as a raw material gas. Other examples include ethane, propane, butane, krypton, xenon, carbon dioxide, and the like.
[0043]
Further, as another example of the line mixer, a so-called Venturi tube type in which the raw material gas is sucked and mixed by thinning the middle of the cylindrical body to generate a negative pressure may be used. Alternatively, a device that performs gas-liquid mixing using a swirling flow in a conical or truncated conical container, such as a swirling fine bubble generating device disclosed in Japanese Patent Application Laid-Open No. 2000-447 may be used. In short, the line mixer in the present specification widely includes those on the line that can continuously mix gas and liquid.
In the above embodiment, one or a plurality of bent pipes are shown as an example of the reaction pipe 7. However, a plurality of branched straight pipes may be used.
[0044]
【The invention's effect】
As described above, in the present invention, the raw material water and the raw material gas are mixed in the middle of the line to dissolve the raw material gas in the raw material water, and the mixed and dissolved gas is cooled while flowing through the reaction pipe and gas. Since the hydrate is generated, gas diffusion / dissolution in the raw water and removal of generated reaction heat can be efficiently performed, and the apparatus can be made simple and compact.
[Brief description of the drawings]
FIG. 1 is a process diagram of one embodiment of the present invention.
FIG. 2 is an explanatory diagram of a line mixer 5 according to an embodiment of the present invention.
FIG. 3 is an explanatory diagram of another aspect of one embodiment of the present invention.
FIG. 4 is an explanatory diagram of another aspect of one embodiment of the present invention.
FIG. 5 is an explanatory diagram of a gas hydrate production process of the present invention.
FIG. 6 is an explanatory diagram of a conventional technique.
[Explanation of symbols]
1, 2 Gas booster 3, 19 Raw material water pump 5 Line mixer 7 Reaction line 9 Separator 27 Pressure adjustment means 29 Retention part (flow rate adjustment means)

Claims (10)

In a method for producing gas hydrate by reacting raw material water and raw material gas,
A mixing / dissolution process in which raw material water and raw material gas are mixed by a line mixer in the middle of the line to dissolve the raw material gas in the raw material water,
A process of cooling the mixed / dissolved material while flowing it through the reaction pipe to generate a gas hydrate;
A process for producing a gas hydrate, comprising: a step in which the produced gas hydrate flows through a pipeline together with unreacted gas and raw water and is sent to a separator. In a method for producing gas hydrate by reacting raw material water and raw material gas,
A mixing / dissolution process in which raw material water and raw material gas are mixed by a line mixer in the middle of the line to dissolve the raw material gas in the raw material water,
A process of cooling the mixed / dissolved material while flowing it through the reaction pipe to generate a gas hydrate;
A separation dehydration step of separating and dewatering the generated slurry-like gas hydrate into a high-concentration slurry or solid by a separator;
A mechanism that takes out only the generated gas hydrate by moving the reaction between the raw material water and the raw material gas and sending all the generated hydrate, unreacted gas and raw material water to the separator once. The gas hydrate manufacturing method characterized by making this unnecessary. In a method for producing gas hydrate by reacting raw material water and raw material gas,
The raw gas is dissolved in the raw water using a line mixer, and the gas hydrate is generated by cooling the peripheral surface of the pipe using a pipe-like reaction pipe. A method for producing a gas hydrate, characterized in that the rate flows along the unreacted gas and the raw material water through the pipeline and is sent to the separator. Gas hydrate is separated by a separator, of the unreacted gas and raw water, according to any one of claims 1 to 3 raw water and unreacted gas is characterized in that it is supplied again to the line mixer Gas hydrate production method. In the separator, so as not to flow into the line gas return raw water, according to claim 4 in water to have a sealing water effects raw water, the water level in the separator, characterized in that it is controlled above a certain level A method for producing a gas hydrate as described in 1. above. 6. The gas hydrate manufacturing method according to claim 4 or 5 , wherein the source gas boosted by the gas booster is directly supplied to the separator. Mixing by line mixer is any one of claims 1 to 6 the raw water stirred to feed gas crushing a raw material gas by involving raw material gas therein fine cells, characterized in that dissolved in raw water The method for producing gas hydrate according to item. A line mixer that mixes raw material water and raw material gas to dissolve the raw material gas in the raw material water, a reaction line that cools the material mixed by the line mixer to generate gas hydrate, and a reaction line that is generated A gas hydrate manufacturing apparatus comprising: a separator that separates gas hydrate, unreacted gas, and raw water; and each component device is connected by piping. 9. The gas hydrate production apparatus according to claim 8, wherein the line mixer generates fine bubbles. The gas hydrate production apparatus according to claim 8 or 9 , wherein the separator is any one of a decanter, a cyclone, a centrifuge, a belt press, a screw concentrator / dehydrator, and a rotary dryer.

Images