JP4062431B2 - Gas clathrate manufacturing method and manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas clathrate production method and apparatus for producing a gas clathrate by reacting a raw material gas such as natural gas and a raw material liquid (fresh water, seawater, antifreeze).
[0002]
[Prior art]
The gas clathrate (simply referred to as “clathrate”. In addition, when the host substance is water, it is referred to as “gas hydrate”, but in the present specification, “gas clathrate” includes gas hydrate). It is an ice-like solid substance that contains gas molecules such as natural gas and carbon dioxide at a high concentration inside the cage structure formed by the molecules of the host substance. Gas clathrate, mainly gas hydrate, can contain a large amount of gas per unit volume, and can be stored and transported at a relatively high temperature under atmospheric pressure compared to liquefied natural gas. Application to storage is attracting attention.
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]
In the conventional gas clathrate production method, a clathrate-forming substance is supplied as bubbles to the water phase in a clathrate production container composed of a large-diameter tank, and water is sprayed into the gas phase in the clathrate production container. There is one that causes a hydration reaction by spraying (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-264851
[Problems to be solved by the invention]
However, the above prior art has the following problems.
Since the capacity of the tank that is the clathrate generation container is large, it is not possible to sufficiently cool only the wall of the pressure vessel. In the above-mentioned Patent Document 1, the water is cooled directly inside the clathrate generation container. Although a means of installing a coil is adopted, there is a problem that the apparatus becomes large and complicated.
[0006]
As another problem, when a gas clathrate is generated in a tank-shaped container, the generated gas clathrate floats on the water surface in the pressure-resistant container, and means for taking it out (for example, a gas clathrate) And a mixture discharge port of water and a device for controlling the water surface to the position, etc.), and there is a problem of complication of the device.
Thus, in the prior art, there is a problem that the facilities are complicated and large.
[0007]
And as what solves the said subject, there exists invention concerning Japanese Patent Application No. 2001-162950 by the present applicant. The invention mixes raw material water and raw material gas in the middle of the line, dissolves the raw material gas in raw material water, and cools the mixed and dissolved material while flowing it into the reaction pipe to generate gas hydrate. It is a thing.
[0008]
The present invention further develops the above-mentioned prior invention, solves the problems of the prior art disclosed in Patent Document 1, and further simplifies the pressure control of the reaction pipe and the separator installed at the outlet thereof. The object is to obtain a gas clathrate manufacturing method and apparatus that can be realized by an apparatus and that is simple and compact as a whole.
[0009]
[Means for Solving the Problems]
The method for producing a gas clathrate according to the present invention comprises a mixing / dissolving step in which a raw material liquid and a raw material gas are mixed in the middle of the line to dissolve the raw material gas in the raw material liquid, and a mixed / dissolved reaction tube A gas clathrate generating step of cooling while flowing to generate a gas clathrate, a separation step of separating the generated gas clathrate by a separator connected to the reaction pipe, and a pressure of the separator Based on the pressure detection step to be detected and the pressure detected in the pressure detection step, either or both of the supply gas flow rate in the mixing / dissolution step and the raw material liquid flow rate in the gas clathrate generation step are adjusted. And a pressure adjusting step for adjusting the pressure of the separator.
[0010]
Further, the gas clathrate production apparatus according to the present invention comprises a gas flow rate adjusting means for adjusting a supplied raw material gas flow rate, a raw material liquid flow rate adjusting means for adjusting a flow rate of the supplied raw material liquid, a raw material liquid and a raw material gas. A line mixer that mixes in the middle of the line and dissolves the raw material gas in the raw material liquid, a reaction line that cools while flowing the raw material liquid in which the raw material gas is mixed and dissolved, and a gas that is generated by being connected to the reaction line A separator for separating the clathrate; a pressure detecting means for detecting the pressure of the separator; a gas flow rate of the gas flow rate adjusting means based on a pressure detected by the pressure detecting means; And a control means for adjusting either one or both of the raw material liquid flow rates.
[0011]
Further, the line mixer is characterized by generating fine bubbles of the raw material gas.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 3 is an explanatory view of the outline of a gas hydrate production process according to an embodiment of the present invention, and shows a case where natural gas is used as a source 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.
[0013]
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. In the present embodiment, the process of generating a slurry gas hydrate from water and natural gas (S3) and the separation and dehydration process (S4) in the above process. By devising, efficient hydrate manufacturing and equipment simplification have been realized. Hereinafter, this point will be described in detail.
[0014]
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. In the following description, the clath rate targeted by the present invention will be described as an example.
The gas clathrate production apparatus of the present embodiment includes a gas booster 1 that boosts the pressure of a raw material gas such as natural gas, raw water (in this specification, “raw water” means only raw water) And raw water pumps 3 and 19 for supplying the raw material gas, and mixing the raw water and the raw material gas to dissolve the raw material gas in the raw water. The line mixer 5 to be mixed, the reaction pipe line 7 that generates a gas clathrate by flowing while mixing the mixed gas in the line mixer 5, the gas clathrate generated in the reaction pipe line 7, the unreacted gas, and the raw water. And a separator 9 for separation.
[0015]
Each component device is connected by a pipe indicated by a solid line with an arrow in the figure. A gas flow rate control valve 12 a for adjusting the gas flow rate is provided in a piping line for supplying the raw material gas to the line mixer 5. In addition, a flow rate control valve 12b for adjusting the flow rate of the raw material water is provided in the piping line that leads from the raw material pumps 3 and 19 to the line mixer 5. Further, the separator 9 is provided with a pressure detector 10 for detecting the pressure in the separator 9, and the gas flow rate control valve 12 a and the flow rate control valve 12 b are controlled by the control means 14 based on the signal of the pressure detector 10. Is done.
[0016]
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.
[0017]
The reaction pipe 7 is a bent pipe, and the peripheral surface of this pipe is cooled by a chiller 17. As described above, since the reaction pipe 7 is used, cooling from the surroundings can be efficiently performed, so that the gas / raw material water is directly cooled by a cooling coil or the like as conventionally performed. This eliminates the need for a simple and compact device configuration.
[0018]
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 shown in Patent Document 1, since the mixing / dissolution and reaction cooling of the raw material gas and raw material water are performed in a tank-shaped clathrate production container, there is a space with a certain spread for mixing / dissolution. In this embodiment, since mixing and dissolution of raw material gas and raw material water and reaction cooling were separated, cooling was not possible in the reaction step. Thus, cooling with a simple configuration as in the above example is possible.
[0019]
The separator 9 separates gas clathrate, unreacted gas, and raw water. Examples of the separator 9 include a decanter, a cyclone, a centrifuge, a belt press, a screw concentrator / dehydrator, and a rotation. A dryer or the like can be considered.
[0020]
Next, the gas clathrate manufacturing method by the apparatus of this Embodiment comprised as mentioned above is demonstrated.
The pressure of the source gas is increased to a predetermined pressure by the gas booster 1 and supplied to the line mixer 5 via the gas flow control valve 12a. The raw water is also boosted to a predetermined pressure by the raw water pump 3 and supplied to the line mixer 5 via the flow rate control valve 12b. At the start of operation, the gas flow rate control valve 12a and the flow rate control valve 12b are each set to the maximum value. The raw material gas and raw material 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.
[0021]
The raw material water dissolved in the raw water (containing undissolved fine bubbles) is sent to the reaction pipe 7, cooled by the chiller 17, and sent to the separator 9. At the start of operation, since the pressure in the reaction line 7 is not the clathrate generation pressure, no clathrate is generated, and the undissolved raw material gas is supplied to the separator 9. The pressure of 9 rises. As described above, when a certain period of time elapses from the start of operation, the pressure in the separator 9 increases, and when the pressure in the reaction line 7 communicating with the separator 9 increases to the clathrate generation pressure, Generation of a gas clathrate is started in the pipeline 7. The gas clathrate generated here flows along the unreacted gas and the raw water along the pipeline and is sent to the separator 9.
[0022]
When unreacted gas is sent to the separator 9, the pressure in the separator 9 rises, but when this exceeds a preset value, the control means 14 causes the gas flow rate control valve 12 a and the raw water flow rate control valve 12 b to Either or both are controlled, thereby adjusting the pressure in the separator 9 and the pressure in the reaction line 7.
[0023]
As described above, the pressure of the separator 9 is adjusted by adjusting the control valves 12a and 12b. Here, the mechanism by which the pressure of the separator 9 changes when the control valves are adjusted will be described.
As a premise thereof, the mechanism of clathrate generation in the reaction line 7 will be described.
The raw material gas and raw material water are mixed by the line mixer 5, the raw material gas becomes fine bubbles, dissolves in the raw material water, and the whole raw material water reaches an equilibrium concentration.
[0024]
When the raw water reaches the equilibrium concentration, the pressure P in the reaction pipe 7 is higher than the lowest clathrate generation pressure P ₀ , and the temperature T of each part of the reaction pipe 7 is lower than the highest clathrate generation temperature T _0. Then, generation of the gas clathrate is started. Although the generation of the gas clathrate involves heat generation, the temperature of the reaction line 7 is maintained at a temperature lower than the maximum clathrate generation temperature T ₀ by removing the heat corresponding to the heat generation amount by cooling the chiller 17. Be drunk. In addition, since raw material water will solidify and the flow in the reaction pipe line 7 will be inhibited if it cools too much, the cooling capacity in the chiller 17 is set so that raw material water may not become below a freezing point.
[0025]
When the gas clathrate is generated, the dissolved gas concentration decreases, and the raw material gas further dissolves until the equilibrium concentration is reached. When the gas clathrate exceeds the equilibrium concentration, further gas clathrate is generated. The gas clathrate thus produced flows in the reaction pipe 7 and is sent to the separator 9 together with the raw water and unreacted gas (there is no unreacted gas when the total amount is clathrated). .
[0026]
In the gas clathrate generation mechanism as described above, when the gas flow rate control valve 12a is adjusted to reduce the gas flow rate, the ratio of clathrate formation in the reaction pipe 7 with respect to the supply gas amount can be increased. The amount of unreacted gas sent to 9 decreases. When the amount of the supply gas is set to a certain amount or less, the entire amount of the raw material gas is clathrated in the reaction pipe line 7 and the unreacted gas is not supplied to the separator 9. Thus, the amount of unreacted gas supplied to the separator 9 can be adjusted by adjusting the gas flow rate control valve 12a to reduce the gas flow rate.
On the other hand, since the separator 9 is also in an environment where clathrate is generated, the unreacted gas in the separator 9 is dissolved and clathrated, and the pressure in the separator 9 tends to decrease.
Therefore, when the amount of unreacted gas supplied to the separator 9 decreases or disappears, the amount of unreacted gas decreases due to clathrate formation in the separator 9, and as a result, the pressure of the separator 9 is reduced. Can be reduced.
[0027]
On the contrary, if the gas flow rate control valve 12a is adjusted to increase the gas flow rate, the ratio of the clathrate gas in the reaction pipe line 7 with respect to the supply gas amount can be reduced, and if the supply gas amount exceeds a certain amount. The unreacted gas is supplied to the separator 9 without making the total amount of the raw material gas clathrate in the reaction pipe line 7. Thus, by adjusting the gas flow rate control valve 12a to increase the gas flow rate, the amount of unreacted gas supplied to the separator 9 can be increased, and as a result, the pressure of the separator 9 can be increased. .
[0028]
Further, when the flow rate control valve 12b is adjusted to increase the flow rate of the fluid flowing through the reaction pipe line 7, the residence time in the reaction pipe line 7 of the raw material water is shortened. As a result, the amount of unreacted gas sent to the separator 9 increases. As a result, the pressure of the separator 9 can be increased.
[0029]
Conversely, when the flow rate control valve 12b is adjusted to reduce the flow rate of the fluid flowing through the reaction pipe 7, the residence time in the reaction pipe 7 of the raw water becomes longer, so that the dissolution of the raw material gas, the clathrate The amount of gasification increases, and the amount of unreacted gas sent to the separator 9 decreases. As a result, the pressure increase of the separator 9 can be stopped or the pressure can be reduced.
[0030]
As is clear from the above explanation, in order to increase the pressure of the separator 9, the gas flow rate control valve 12a is adjusted to increase the gas flow rate, or the flow rate control valve 12b is adjusted to change the reaction line 7 What is necessary is just to make the flow velocity of the flowing fluid faster.
Conversely, in order to decrease the pressure of the separator 9, the gas flow rate control valve 12a is adjusted to reduce the gas flow rate, or the flow rate control valve 12b is adjusted to reduce the flow rate of the fluid flowing through the reaction line 7. do it.
[0031]
As described above, by adjusting the control valves 12a and 12b, the pressure of the separator 9 is adjusted, and the generated gas clathrate is maintained in the separator 9 at a stable pressure. As a result, the reaction tube The pressure in the passage 7 is also maintained at a pressure optimum for clathrate formation.
In the separator 9, the gas clathrate, the unreacted gas, and the raw water are separated, and the separated raw water is supplied again to the line mixer 5 by the pump 19.
On the other hand, the generated gas clathrate is taken out from the separator 9 and sent to a post-processing step (steps after S5 in FIG. 3).
[0032]
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 become 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.
[0033]
As described above, according to the present embodiment, the gas flow rate control valve 12a and the flow velocity control valve 12b are provided, and the control values 12a and 12b are detected by the pressure detector 10 provided in the separator 9. Since the control is performed based on the control, the pressure control in the separator 9 can be realized by a simple device, and the device can be simplified.
Further, in the present embodiment, since the reaction between the raw water and the raw material gas is performed while being moved through the pipe line, in this gas clathrate generation step, everything (generated gas clathrate, unreacted gas is generated). , The raw material water) is once sent to the separator 9, and there is no need for a mechanism for taking out only the gas clathrate, and the configuration of the apparatus can be simplified.
[0034]
Furthermore, since the raw material gas is continuously dissolved in the raw material water by the line mixer 5 formed of a cylindrical body, it can be efficiently performed in a space-saving manner.
Further, as a result of dissolving the raw material gas in the raw material water by the line mixer 5 different from the clathrate production vessel, it is possible to use the pipe-like reaction line 7 instead of the large-diameter clathrate production vessel. This enables a simple and compact cooling means for cooling the peripheral surface of the pipe line.
In addition, since both the melting of the raw material gas by the line mixer 5 and the generation of the gas clathrate in the reaction pipe 7 are performed continuously, the production efficiency of the gas clathrate can be dramatically increased.
[0035]
In the description of the above embodiment, 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.
[0036]
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.
[0037]
Moreover, in said embodiment, although the kind of raw material water was not specified, for example, fresh water, seawater, and antifreeze can be considered.
[0038]
【The invention's effect】
As described above, in the present invention, the mixing / dissolving step of mixing the raw material liquid and the raw material gas in the middle of the line and dissolving the raw material gas in the raw material liquid, and flowing the mixed / dissolved material into the reaction pipe A gas clathrate generating step of generating a gas clathrate by cooling while cooling, a separation step of separating the generated gas clathrate, the raw material liquid and the raw material gas by a separator connected to the reaction pipe, and the separation One or both of a pressure detection step for detecting the pressure of the vessel, and a supply gas flow rate in the mixing / dissolution step and a raw material liquid flow rate in the gas clathrate generation step based on the pressure detected in the pressure detection step Pressure adjusting step of adjusting the pressure of the separator by adjusting the pressure of the separator, so that the pressure control of the separator installed in the reaction pipe and its outlet can be performed in a simple manner. Together, efficient production of clathrate can be realized.
[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 a gas hydrate manufacturing process according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Gas pressure | voltage booster 3, 19 Raw material water pump 5 Line mixer 7 Reaction pipe line 9 Separator 10 Pressure detector 12a Gas flow rate control valve 12b Flow rate control valve 14 Control means

Claims (3)

In a method for producing a gas clathrate by reacting a raw material liquid and a raw material gas,
Mixing / dissolving process in which raw material liquid and raw material gas are mixed in the middle of the line to dissolve the raw material gas in the raw material liquid, and gas that is mixed and dissolved while flowing through the reaction pipe to generate a gas clathrate A clathrate generation step, a separation step of separating the generated gas clathrate by a separator connected to the reaction pipe, a pressure detection step of detecting the pressure of the separator, and detection by the pressure detection step A pressure adjustment step of adjusting the pressure of the separator by adjusting one or both of the supply gas flow rate in the mixing / dissolution step and the raw material liquid flow rate in the gas clathrate generation step, A gas clathrate manufacturing method comprising: In an apparatus for producing a gas clathrate by reacting a raw material liquid and a raw material gas,
A gas flow rate adjusting means for adjusting the supplied raw material gas flow rate, a raw material liquid flow rate adjusting means for adjusting the flow rate of the supplied raw material liquid, and the raw material liquid and the raw material gas are mixed in the middle of the line to dissolve the raw material gas in the raw material liquid. A line mixer, a reaction pipe that cools the raw material liquid in which the raw material gas is mixed and dissolved, a separator that is connected to the reaction pipe and separates the generated gas clathrate, and A pressure detecting means for detecting pressure, and a control for adjusting one or both of the gas flow rate of the gas flow rate adjusting means and the raw material liquid flow rate of the raw material liquid flow rate adjusting means based on the pressure detected by the pressure detecting means; Means for producing a gas clathrate. 3. The gas clathrate manufacturing apparatus according to claim 2, wherein the line mixer generates fine bubbles of a raw material gas.

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