JP2000256227A - Method and apparatus for producing hydrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a highly concentrated hydrate at high rate by efficient reaction between a hydrate-forming material and water, and to provide an apparatus for the method. SOLUTION: This method comprises reaction between water and a hydrate- forming material (e.g. methane) in a hydrate production vessel 1 to obtain the aimed hydrate; the gas phase G inside the vessel 1 is sprayed with water in an atomized fashion to enlarge the surface area of the water per unit volume to markedly increase the contact area between the water particles 10 and the gas phase G, thereby increasing the rate of methane hydrate production. Inside the vessel 1, although the hydrate thus produced may adhere, surface skin- fashion, to the surface of especially large-sized water particles, such hydrate surface skin is destructively separated by subjecting the gas phase or aqueous phase inside the vessel 1 to ultrasonic vibration by an ultrasonic vibration generator 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for efficiently producing a high-concentration hydrate by reacting a hydrate-forming substance (for example, methane) with water and an apparatus for producing the same.

[0002]

2. Description of the Related Art It is known that natural gas components such as methane are distributed in large quantities as hydrates underground in cold regions. Since these hydrates exist stably under the condition of low temperature and high pressure, they are expected as the next generation natural gas source. In particular, methane hydrate (hereinafter “methane hydrate”)
Is a type of clathrate in which methane molecules are contained in a basket composed of water molecules arranged three-dimensionally. The intermolecular distance of methane in a hydrated cage is It is shorter than the intermolecular distance in a gas cylinder filled with high pressure and is in a tightly packed state.
Transport is expected, and the reaction between methane and water is a reversible equilibrium reaction, which generates a large heat of hydration.
Applications to heat storage materials, refrigerators and heat pumps are also being studied.

[0003] On the other hand, since various applications are expected as described above, studies for efficiently synthesizing methane hydrate in addition to relying on natural resources have been conducted. But methane hydrate is generally
For example, the pressure that can exist stably at 15 ° C. is 100 kg / c
In order to exist stably as m ² or more, low temperature and high pressure are required, and handling is difficult. Therefore, various stabilizers have been sought so that the methane hydrate formation equilibrium shifts to a higher temperature and lower pressure side even a little. For example, aliphatic amines such as isobutylamine and isopropylamine (see Japanese Patent Publication No. 53-1508), 3-dioxolan, cyclobutanone,
Tetrahydrofuran, cyclopentanone, acetone, etc. (Seiichi Yokoi et al., The Chemical Society of Japan, 1993, (4), P.387-39
4) was found to be effective as a stabilizer.

[0004] In the synthesis of the methane hydrate, for example, an apparatus shown in FIG. 9 has conventionally been generally used. In FIG. 9, the methane hydrate synthesizing apparatus
The pressure vessel 150 is equipped with an aqueous phase injection pipe 151, a methane introduction pipe 152 for introducing methane gas, a discharge port 153, and a stirring blade 154.
5. This synthesizer includes a gas phase temperature T ₁ measuring device, a liquid phase temperature T ₂ measuring device, a container pressure P measuring device, a rotating speed R measuring device of the stirring blade 154, and a temperature T ₃ measuring device in the thermostatic chamber 155. Is set.

In order to synthesize methane hydrate using the above-described apparatus, for example, first, methane gas is introduced into a pressure-resistant vessel 150 from a methane introduction pipe 152 to eliminate air in the vessel, and then an aqueous phase injection pipe 151 is formed. , An aqueous solution containing a stabilizer at a predetermined concentration is injected as an aqueous phase, and is stabilized at a predetermined temperature by a thermostat 155. Under stirring by the stirring blade 154, methane gas is introduced from the methane introduction pipe 152 until a predetermined pressure is reached. If stirring is continued in this state, a hydration reaction occurs, and the pressure P in the vessel decreases, and the heat of hydration increases the liquidus temperature T ₂ . Adjust the container pressure by venting a portion of necessary exhaust port 153 of the methane, if the liquid phase temperature T ₂ in a constant temperature bath 155 and vapor temperature T ₁ is allowed to stand until it matches, temperature T ₂ The methane hydrate having the production equilibrium pressure P at is obtained as a liquid phase.

Further, there has been proposed a technique for generating hydrate by spraying water into a gaseous phase of ethane, which is a hydrate-forming substance, and contacting it with a large contact area (INTERNATIONAL CONFERENCE ON NATURAL GAS HYDRAT).
ES (JUNE 2-6, 1996 TOULOUSEFRANCE)).

[0007]

The conventional method for producing methane hydrate shown in FIG. 9 has the following problems. First, the reaction between methane and water is caused by the absorption of methane into the water phase at the gas-liquid interface. On the other hand, as shown in FIG. 10, the methane hydrate MH generated by the reaction has a density of water. Smaller (theoretical density 0.915 g / cm ² ) and floats near the liquid surface of the liquid phase L (aqueous phase) to form a methane hydrate layer, so that methane M at the interface between the gas phase G and the liquid phase L Absorption will be hindered by the product. Further, with the generation of methane hydrate, the viscosity of the liquid phase L increases, and the stirring effect decreases. As a result, it becomes difficult to obtain a high concentration of methane hydrate.

Further, the concentration of methane hydrate in the liquid phase L increases with the introduction of methane gas from the methane introduction pipe, but the ratio of water remaining in the liquid phase L due to the reaction decreases. When the production equilibrium is reached at the pressure, the reaction does not proceed any further, and even in this respect, it is not possible to obtain a high concentration of methane hydrate.

Further, after injecting the aqueous solution into the container, it takes a long time from the time of the injection until the hydration reaction between the aqueous solution and methane gas is completed, that is, in order to stabilize the aqueous solution at a predetermined temperature by a constant temperature bath. And the production efficiency of methane hydrate is poor. In the technology for generating hydrate by spraying water into the gaseous phase of ethane, water particles and ethane can be brought into contact with a large contact area. May be attached to the skin. The water particles contained in the hydrate do not convert to the hydrate as it is, and there is room for improvement in improving the hydrate generation efficiency.

The present invention has been made in view of the above-mentioned problems of the prior art, and is a method for efficiently producing a high-concentration hydrate at a high speed by efficiently reacting a hydrate-forming substance with water. It is an object to provide a method and an apparatus for manufacturing the same.

[0011]

SUMMARY OF THE INVENTION The present invention for achieving the above object provides a hydration reaction by spraying water into a gas phase comprising a hydrate-forming substance in a hydrate-producing vessel. Awake and generate hydrate, by ultrasonically vibrating the gas phase or aqueous phase in the hydrate generation container, to separate the generated hydrate skin attached to the surface of the water particles. This is a method for producing a hydrate.

According to the present invention, the surface area per unit volume of water is increased by spraying water in a gaseous phase (comprising a hydrate-forming substance) in the hydrate generation vessel, and water and The contact area with the gas phase can be greatly increased, and the rate of hydrate generation can be improved. Then, in the hydrate generation container, the generated hydrate may adhere to the surface of particularly large water particles in a skin-like manner.In the present invention, the gas phase or the aqueous phase in the hydrate generation container is removed. The hydrate skin attached to the surface of the water particles can be separated by ultrasonic vibration, so that the water particles can be used as a raw material for hydrate again to achieve high-speed generation.

[0013] As a manufacturing apparatus for carrying out the above-mentioned manufacturing method, a hydrate generating vessel in which the internal temperature and pressure are set under hydrate generating conditions, A hydrate-forming substance supply means for supplying a hydrate-forming substance to form a gas phase, a spray means for spraying water into the gas phase in a spray form, and a gas phase in a hydrate generation container. Alternatively, it is provided with a hydrate skin separator for ultrasonically vibrating the aqueous phase, and hydrate collecting means for collecting hydrate generated and floating near the liquid surface of the aqueous phase. It is. Here, the hydrate skin separation device is an ultrasonic vibration generator provided on an outer wall of the hydrate generation container, or an ultrasonic vibration network provided in a gas phase in the hydrate generation container. be able to.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings. In the embodiment described below, the hydrate-forming substance is methane gas, and an apparatus and a method for consistently producing methane hydrate will be described.However, the hydrate-forming substance is not limited to methane gas, and ethane, propane, butane, There are also krypton, xenon, and carbon dioxide. As shown in FIGS. 6 (a) and 6 (b), the methane hydrate MH is provided in a basket in which water molecules W are arranged in a three-dimensional form (for example, dodecahedral or tetrahedral). Is a kind of clathrate (clathrate) containing, for example, generated based on the following reaction formula. Also, methane hydrate MH
Is decomposed into about 0.9 water and about 170 methane gas under standard conditions per 1 volume of methane hydrate. CH ₄ + 5.7H ₂ O → CH ₄ .5.7H ₂ O + heat of hydration

FIG. 1 is a block diagram of an embodiment of a hydrate producing apparatus according to the present invention. Reference numeral 1 denotes a sealed hydrate generation vessel (reaction vessel), in which a cooling coil 8 as a cooling means (temperature control means) is inserted. Thereby, the below-mentioned aqueous phase L in the hydrate generation vessel 1 can be cooled and maintained at, for example, about 1 ° C. within the hydrate generation temperature range (for example, 1 to 5 ° C.). When methane hydrate MH is generated, heat of hydration is generated. On the other hand, since methane hydrate MH is not generated unless it is in a low-temperature and high-pressure state, cooling means is provided in the hydrate generation vessel 1 as described above. It is preferable to always cool. Although the cooling coil 8 is used as the cooling means, the cooling means is not limited to this. For example, the hydrate generation container 1 may be surrounded by a cooling jacket, and the cooling jacket may be supplied with brine from a brine tank and circulated, or a radiator may be inserted into the hydrate generation container 1, or a combination of these may be used. You may.

Reference numeral 3 denotes a water storage tank. When water is introduced from the water storage tank 3 into the hydrate generation vessel 1 via the pipe 25, the aqueous phase L ( Liquid phase). A water supply pump 24 and a valve 26 are provided in the pipe 25, and are controlled so that the liquid level S of the aqueous phase L maintains a constant level. The water tank 3, the water supply pump 24 and the pipe 25
The water supply means 51 is constituted by the above.

A methane inlet 1a is provided on a lower side wall of the hydrate generating vessel 1. The methane inlet 1a is connected to a pipe 12 from a methane cylinder 2 as a methane supply source.
A methane gas (hydrate-forming substance) is supplied via the. Normal valve 1
1 and a flow control valve 16 (control unit) are provided.
The opening of the flow control valve 16 depends on the hydrate generation vessel 1
By controlling the pressure with a pressure gauge 23 for detecting the pressure of a gaseous phase G (methane gas), which will be described later, methane is replenished in the hydrate generation vessel 1 and the pressure of the gaseous phase G is constantly adjusted to the hydrate generation pressure (this example). At 40 atm). The methane cylinder 2 and the pipe 12 constitute a methane supply means 52 (hydrate-forming substance supply means), and the pressure gauge 23 and the flow control valve 16 constitute a production vessel pressure constant means 13.

At the bottom of the hydrate generating vessel 1, a water outlet 1b for extracting unreacted water is provided, and the unreacted water extracted from the water outlet 1b is
After being supercooled, it is configured to be supplied again into the hydrate generation container 1. More specifically, the water outlet 1b and the spray nozzle 9 provided at the top of the hydrate generation container 1 are connected by a pipe 20, and the pipe 20 has a valve 18, a water circulation pump 19, a heat exchanger ( A cooler 21 and a valve 22 are sequentially arranged. The water extracted by the water circulation pump 19 is supercooled by the heat exchanger 21 and then sprayed into the gas phase G (methane atmosphere) in the hydrate generation vessel 1 by the spray nozzle 9 (see reference numeral 10). Supplied.

Here, the supercooling means, as shown in FIG.
At least the temperature is lower than an arbitrary point D on the methane hydrate production equilibrium line C (in the direction of arrow X) or the pressure is higher (in the direction of arrow Y). The region above the generation equilibrium line C (hatched for convenience) is a hydrate generation region (under hydrate generation conditions). For reference, the production equilibrium lines of ethane, propane and butane are also shown. As the heat exchanger (cooler) 21,
For example, a multi-tube heat exchanger having excellent heat conduction efficiency, a coil heat exchanger having a simple structure, and a plate heat exchanger having excellent heat conduction efficiency and easy maintenance can be used. In addition, the water circulation pump 19, the pipe 20, the heat exchanger 21
Thus, the water subcooling circulation means 4 (water circulation means) is constituted.

Here, the spray nozzle 9 (spray means) is provided downward at the top of the hydrate generating vessel 1 as shown in FIG. Thus, water particles 10 having an outer diameter of several tens μm on average (in principle, the smaller the particle diameter, the better) are ejected toward the gas phase G. As described above, by spraying water into the gas phase G in a spray form to form a large amount of water particles 10, the surface area per unit volume of water, that is, the gas phase G
Contact area can be extremely increased. In addition,
As described above, when the unreacted water extracted from the bottom of the hydrate generation container 1 is sprayed in the hydrate generation container 1 by the spray nozzle 9, it is important to prevent the foreign matter from clogging the spray nozzle 9. Becomes Therefore, it is preferable to provide a filter 18a for collecting foreign matter such as hydrate in the pipe 20, and to reliably remove the foreign matter from the extracted unreacted water. The spray means of FIG. 4B will be described later.

When methane hydrate is generated by spraying water into the gas phase G in the hydrate generating vessel 1 in the form of spray, as shown in FIG. , Generated methane hydrate MH
May be attached to the skin. Since the water particles 10 included in the methane hydrate MH do not convert to methane hydrate as it is, it is necessary to remove the skin of the methane hydrate MH. Therefore, in the present embodiment, an ultrasonic vibration generator 6 as a hydrate skin separation device is mounted on, for example, the outer wall of the gas phase part of the hydrate generation container 1, and the ultrasonic vibration generator 6 particularly uses the ultrasonic vibration generator 6. Is subjected to ultrasonic vibration. As a result, FIG.
As shown in (b), the methane hydrate MH of the water particles 10 in the gas phase G is destroyed, and the water particles 10 are separated from the methane hydrate MH. And achieve fast generation.

The ultrasonic vibration generator 6 is not limited to being provided in the gaseous phase portion of the hydrate generation container 1, and the ultrasonic vibration generator 60 is connected to the water of the hydrate generation container 1 as shown in FIG. Although it may be mounted on the outer wall of the phase portion, the running cost can be reduced by providing the gas phase portion and vibrating the gas phase G in particular. Further, as shown in FIG. 2B, an ultrasonic vibration network 61 as a hydrate skin separating device is provided in the gas phase portion in the hydrate generation container 1, and the ultrasonic vibration network 61 is ultrasonically vibrated. Thereby, the methane hydrate skin of the water particles passing through the ultrasonic vibration network 61 may be destroyed.

A liquid layer outlet 1c is provided in the hydrate generating vessel 1 near the liquid surface S of the aqueous phase L. The liquid layer outlet 1c and the hydrate recovery tank 50 are connected to a pipe 34.
Connected by The pipe 34 has a liquid layer discharge outlet 1c
From the side, a valve 35, a filter 36, a valve 37, and an extraction pump 38 are sequentially arranged. With such a configuration, the relatively low-density methane hydrate layer MH floating on the liquid level S passes through the pipe 34, and after the foreign matter is removed by the filter 36, is collected in the hydrate collection tank 50. According to such a hydrate recovery means 70, since methane hydrate can be transferred together with water, the recovered product is in a slurry state, and thus handling is easy.

Next, the operation of the above hydrate manufacturing apparatus, that is, the manufacturing method will be described. The air in the hydrate generation vessel 1 is replaced with methane gas in advance, and then the aqueous phase L is introduced from the water storage tank 3 into the hydrate generation vessel 1 so that the liquid level S is higher than the liquid layer outlet 1c. .
This aqueous phase L may contain a stabilizer if necessary. Next, the water phase L in the hydrate generation vessel 1 is cooled to a predetermined temperature of, for example, about 1 ° C. by the cooling coil 8, and thereafter the temperature is controlled so as to maintain this temperature.

When the temperature of the aqueous phase L is stabilized at a predetermined temperature, methane in the methane cylinder 2 is continuously introduced as bubbles K from the methane inlet 1a. As a result, at least part of methane is absorbed into the aqueous phase L from the gas-liquid interface of the bubbles K, and reacts with water to be converted into methane hydrate (hydration reaction). Methane hydrate MH produced by the reaction
Has a density lower than the density of water, so that it floats in the aqueous phase L and forms a layer on the liquid surface S. The methane hydrate layer MH is withdrawn from the liquid layer withdrawal port 1c by the withdrawal pump 38 and collected in the methane hydrate recovery tank 50. Methane hydrate is recovered with water,
It is in the form of slurry. As the methane hydrate layer MH is extracted from the liquid layer extraction outlet 1c, the liquid level S of the aqueous phase L decreases, so that the level of the liquid level S is kept constant.
Fresh water is supplied from the water storage tank 3 into the hydrate generation container 1 via the water supply pump 24.

When methane hydrate MH is generated in the hydrate generation vessel 1, gas methane becomes solid methane hydrate MH, and the internal pressure decreases.
On the other hand, in order to generate methane hydrate at high speed, the conditions in the hydrate generation vessel 1 must be set to a lower temperature and higher pressure state. Therefore, in order to eliminate the pressure drop in the hydrate generation vessel 1 due to the generation of methane hydrate, the pressure in the hydrate generation vessel 1 is measured by a pressure gauge 23.
And the flow control valve 1
6 is continuously controlled. Thereby, a required amount of the raw material methane is replenished in the hydrate generation vessel 1 and the inside of the hydrate generation vessel 1 is maintained at a constant high pressure state, thereby achieving high-speed generation.

On the other hand, unreacted methane gas that has not been absorbed by the aqueous phase L is released from the liquid level S and accumulates as a gas phase G in the hydrate generation vessel 1. Hydrate generation container 1
The unreacted water is extracted from the bottom of the container, and is supercooled by the heat exchanger 21. Then, the unreacted water is atomized in the hydrate generating container 1 by the spray nozzle 9. As described above, a large amount of supercooled water particles 10 is released into the methane gas filled in the hydrate generation vessel 1, and the contact area per unit volume of the water particles 10 with methane is greatly increased, and the water particles 10 are immediately hydrated. As it reacts, methane hydrate is produced at a high rate. The generated hydrate falls to the liquid surface S and is collected in the same manner as described above. When methane hydrate MH is generated in the hydrate generation vessel 1, a large heat of hydration is generated. On the other hand, methane hydrate MH
In order to produce the hydrate at high speed, the conditions in the hydrate production vessel 1 must be set to a lower temperature and higher pressure. Therefore,
Discharging the supercooled water particles 10 into the hydrate generation vessel 1 also effectively removes the heat of hydration.

When the hydrate generation vessel 1 is large, the water at the bottom may be in a supercooled state. Therefore, the water is not taken out and cooled, and the hydrate generation vessel 1 is not cooled. May be sprayed on top of

In the above-described embodiment, the bubble K of methane rises in the aqueous phase L, so that the bubble interface can always be brought into contact with new water molecules without being covered with a high-viscosity reaction product. Is promoted. By continuing this operation in a stable state, high-concentration methane hydrate can be efficiently and continuously recovered in the methane hydrate recovery tank 50.

Water particles 1 ejected from spray nozzle 9
If the particle diameter of the water particle 1 is large, the methane hydrate generated on the surface of the water particle impedes the supply of methane.
0 cannot be methane hydrate entirely. Therefore, in the present embodiment, the methane hydrate MH of the water particles 10 can be destroyed by the ultrasonic vibration generator 6 or the ultrasonic vibration network 60, and the water particles 10 and the methane hydrate MH can be separated. The water particles 10 can be used again as a raw material for methane hydrate, and high-speed production is achieved.

In addition, by spraying gas together with water from the spray nozzle 9 to make the average particle diameter of the water particles 10 around 10 μm, it is possible to reduce the adhesion of methane hydrate as described above. Examples of the gas include an inert gas that does not react with water or a hydrate-forming substance. The number of spray nozzles 9 is not limited to one, but may be plural. Another method for reducing the average particle size of water particles to about 10 μm is shown in FIG.
As shown in (b), an ultrasonic vibration plate 90 provided at the upper part in the hydrate generation container 1 is provided, and the ultrasonic vibration plate 9 is provided.
Water film 91 may be formed by supplying supercooled water from piping 20 to pipe 0, and water particles 10 may be released from water film 91 by ultrasonic vibration. In this case, the particle size of the water particles 10 becomes more uniform, and no adverse effect is caused by the ejection of the gas.

In general, the reaction between methane and water proceeds at a pressure of 40 atm or more, for example, when the reaction temperature is 1 ° C. Therefore, a high-pressure container having a pressure resistance of at least 40 atm is required as the hydrate generation container 1. When it is desired to carry out the reaction at a higher temperature and lower pressure, it is preferable to add a stabilizer to the aqueous phase L. Examples of stabilizers that can shift the hydration reaction of methane to higher temperature and lower pressure include aliphatic amines such as isobutylamine and isopropylamine; alicyclic ethers such as 1,3-dioxolan, tetrahydrofuran, and furan. Alicyclic ketones such as cyclobutanone and cyclopentanone; and aliphatic ketones such as acetone. Since all of these stabilizers have a hydrocarbon group and a polar group in the molecule,
Each polar group attracts water molecules, and the hydrocarbon group attracts methane molecules, reducing the intermolecular distance,
It is thought to promote the hydration reaction. For example, the reaction at 10 ° C. and 20 kg / cm ² G becomes possible by addition of aliphatic amines, and 10 ° C. by addition of tetrahydrofuran.
Reaction at 10 kg / cm ² G or less is also possible. These stabilizers are preferably added in the range of 0.1 to 10 mol per 1000 g of pure water.

The reaction temperature depends on the above-mentioned relation of the production equilibrium.
It is better to be as low as possible. For example, it is preferable to control the temperature of the aqueous phase in the hydrate generating vessel 1 to be in the range of 1 to 5 ° C. As a result, the solubility of methane in water can be increased, and the production equilibrium pressure can be reduced. The reaction between water and methane is an exothermic reaction, and when the reaction is started in the hydrate production vessel 1, the temperature inside the system rises due to the heat of hydration, so that the temperature inside the system is always maintained within a predetermined range. It is preferable to perform temperature control as described above.

Next, another embodiment will be described. As shown in FIG. 7, the same components as those in FIG. 1 are denoted by the same reference numerals, and the differences will be mainly described.

Reference numeral 5 denotes a tank for producing methane saturated water,
Methane gas is supplied from the methane cylinder 2 into the methane saturated water producing tank 5 through the pipe 12, and
Water is supplied from the water storage tank 3 by the water supply pump 24.
As a result, a saturated raw water 28 saturated with methane is produced in the methane saturated water producing tank 5, and the saturated raw water 28
Is supplied to the hydrate generation vessel 1 through the pipe 33. Here, in order to produce saturated water, the contact area between water and methane may be increased, so that methane gas is preferably supplied to the liquid phase of the methane saturated water production tank 5. Methane hydrate has a structure in which methane molecules are contained in a cage made of water molecules as described above. If the water molecules are close to the cage structure in advance, methane hydrate is generated at a higher speed. This is called a memory effect. To achieve the memory effect, it is effective to previously saturate the raw water with methane as in the present embodiment. However, in the present invention, although saturation is the most desirable embodiment, if methane is dissolved, the rate of methane hydrate generation is improved as compared with mere water, and the present invention covers this range. .

The tank 5 for producing methane-saturated water has, for example, a jacket 27 as cooling means, and produces methane-saturated water by brine circulated through a brine tank (not shown) and a brine pump (not shown). Tank 5
The saturated raw water 28 can be cooled to about 40 atm and kept at about 1 ° C. Jacket 2 as temperature control means
7, but is not limited to this. For example, the methane-saturated water producing tank may be constituted by a double pipe or a multi-pipe, and the brine may be circulated in one of the gaps, or a cooling coil or a radiator may be inserted into the methane-saturated water producing tank, They may be used in combination. Saturated raw water 28 in methane saturated water making tank 5
Is circulated to the upper part of the methane-saturated water producing tank 5 by the pump 32 and the pipe 31, and is sprayed by the nozzle 30 (see reference numeral 29) so that the saturated raw water 28 is stirred to be more saturated. be able to.

An integrating flow meter 15 is provided immediately before the flow control valve 16 of the methane supply means 52, and by measuring the total volume of methane supplied from the methane supply means 52 into the hydrate production vessel 1. Calculate and manage the total amount of methane hydrate produced accurately and easily. In addition, since the methane hydrate generated may contain particles with a hydrate film attached to water droplets, the net amount of methane hydrate can be accurately calculated simply by accumulating the generated methane hydrate. It is impossible to measure in

The structure of the hydrate recovery means 7 in this embodiment up to the recovery pump 38 is the same as that shown in FIG. 1, but a centrifugal separator 39 and an adiabatic expansion are provided downstream of the recovery pump 38. A decompression container 40 for reducing the pressure, a conveyor 41 and the like are sequentially arranged. The generated methane hydrate MH layer is first introduced into a centrifugal separator 39 by a recovery pump 38. Here, most of the water is removed from the methane hydrate MH, and the methane hydrate MH in a slurry state is obtained. This centrifuge 3
The pressure in 9 is about 40 atm, which is almost equal to that in hydrate production vessel 1. The slurry-like methane hydrate is conveyed into the depressurized container 40, where it is adiabatically expanded several times.
By reducing the pressure to tm, while maintaining the pressure and temperature of the hydrate under the conditions of hydrate formation, as shown in FIG. 8, ice crust C is formed on the surface of methane hydrate MH, and methane hydrate MH is formed. Stabilize. The methane hydrate is conveyed by a conveyor 41 and, if necessary, undergoes a drying and cooling step.

In each of the above embodiments, unreacted water was extracted from the bottom of the hydrate generation vessel 1, supercooled and sprayed onto the gas phase G in the hydrate generation vessel 1. Spray without supercooling, and water (or supercooled water) from another system
May be sprayed on the gas phase in the hydrate generation container 1.

[0040]

Since the present invention is configured as described above, it has the following effects. According to the first aspect of the present invention, the surface area per unit volume of water is increased by spraying water into the gas phase in the hydrate generation container in the form of spray, and the contact area between water and the gas phase is greatly increased. To increase the hydrate generation rate. And, in the hydrate generation container, particularly on the surface of the large water particles, the generated hydrate may adhere to the skin, but in the present invention,
By oscillating the gas phase or the water phase in the hydrate generation vessel with ultrasonic waves, the hydrate skin attached to the surfaces of the water particles in the gas phase and the water phase can be separated. As a raw material for the rate, achieve high-speed production.

The generated hydrate descends,
It floats above the liquid phase and accumulates near the liquid surface to form a hydrate layer. The hydrate layer is extracted and collected. In this system, the bubbles of methane rise in the aqueous phase, so that the bubble interface can be constantly brought into contact with new water molecules without being covered with a high-viscosity reaction product, and the reaction is promoted. By continuing this operation in a stable state, high-concentration hydrate can be efficiently and continuously recovered.

According to the manufacturing apparatus of the second aspect, the manufacturing method of the first aspect can be easily and reliably implemented. Here, the hydrate skin separation device may be an ultrasonic vibration generator provided on the outer wall of the hydrate generation container or an ultrasonic vibration network provided in the gas phase in the hydrate generation container. it can. The running cost can be reduced by providing the hydrate skin separation device in the gas phase and in particular by vibrating the gas phase.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a hydrate production apparatus according to a first embodiment of the present invention.

Fig. 2 Hydrate skin separation device (particle decomposition device)
It is a figure which shows other forms.

FIG. 3 is a schematic diagram showing a state when hydrate epidermis is separated from water particles.

4A is an enlarged view of the spray means shown in FIG. 1, and FIG. 4B is a view showing another embodiment of the spray means.

FIG. 5 is a hydrate generation equilibrium diagram.

FIG. 6 is a diagram showing a molecular structure of a hydrate.

FIG. 7 is a configuration diagram of another embodiment of the hydrate manufacturing apparatus of the present invention.

FIG. 8 is a view showing a state in which ice skin is formed on the recovered hydrate.

FIG. 9 is a configuration diagram of a conventional hydrate manufacturing apparatus.

FIG. 10 is a diagram for explaining a problem of the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Hydrate generation container (reaction container) 2 Methane cylinder 3 Water storage tank 4 Water supercooling circulation means (Water circulation means) 5 Saturated water preparation tank 6,60 Hydrate skin separation device (Particle decomposition device) 7,70 Hydrate recovery means 9 Spray nozzle (spray means) 13 Constant pressure inside the production vessel 16 Flow control valve 19 Circulation pump 21 Heat exchanger 23 Pressure gauge 24 Water supply pump 51 Water supply means 52 Methane supply means (hydrate forming substance supply means) G Gas phase (Methane gas) L Water phase K Bubble S Liquid level

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takahiro Kimura 1-1-1 Wadazakicho, Hyogo-ku, Kobe-shi, Hyogo F-term in Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (reference) 4H006 AA02 AC90 BC10 BC11 BC14 BE60

Claims (4)

[Claims] 1. A hydrate is generated by spraying water in a gaseous phase comprising a hydrate-forming substance in a hydrate-producing container in a mist-producing state. A method for producing a hydrate, comprising separating a generated hydrate skin adhered to the surface of water particles by ultrasonically vibrating a gas phase or a water phase in the water. 2. A hydrate generation container in which the temperature and pressure inside are set under hydrate generation conditions, and a hydrate for supplying a hydrate-forming substance into the hydrate generation container to form a gas phase. A rate-forming substance supply means, a spray means for spraying water into the gaseous phase in a spray state, a hydrate skin separation device for ultrasonically vibrating the gaseous or aqueous phase in the hydrate generation vessel, A hydrate recovering means for recovering the hydrate floating near the liquid level of the aqueous phase. 3. The hydrate producing apparatus according to claim 2, wherein the hydrate skin separating apparatus is an ultrasonic vibration generator provided on an outer wall of the hydrate generating container. 4. The hydrate production apparatus according to claim 2, wherein the hydrate skin separation apparatus is an ultrasonic vibration network provided in a gas phase in the hydrate generation container.