JP4617548B2 - Hydrate slurry production method, hydrate slurry production apparatus and aqueous solution - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for producing a hydrate slurry by cooling an aqueous solution containing a guest compound. More specifically, the present invention relates to a method and apparatus for reliably and efficiently producing a hydrate slurry by preventing supercooling when the aqueous solution is cooled to produce a hydrate.
[0002]
[Prior art]
Conventionally, aqueous solutions containing guest compounds such as various salts such as tetra n-butylammonium salt, tetraiso-amylammonium salt, tetraiso-butylphosphonium salt, triiso-amylsulfonium salt are cooled. Then, it is known that a hydrate is produced. This hydrate can be produced at a temperature of 0 ° C. or higher, and becomes fine particles and floats in an aqueous solution to form a highly fluid hydrate slurry. It has preferable characteristics as a cold transport medium.
[0003]
By the way, when the aqueous solution as described above is cooled, the hydrate is not generated even when the temperature at which the hydrate is to be generated, and the hydrate is generated after being cooled to a temperature lower than this temperature. It is known that so-called supercooling occurs.
[0004]
Such supercooling not only reduces the efficiency of the refrigeration system that cools the undesirably low temperature when producing hydrates, but also reduces the efficiency of the supercooled aqueous solution. Hydrate is undesirably generated in each part of the device, causing problems such as blocking the piping and valves of the device.
[0005]
For this reason, various techniques for preventing this overcooling have been developed.
[0006]
A representative example of this supercooling prevention technique is to add various supercooling prevention chemicals to this aqueous solution. However, even when such a chemical is added, it is not possible to effectively prevent supercooling, and depending on the type of the chemical added, there is a problem that the corrosiveness of the aqueous solution becomes high.
[0007]
It is also known that such supercooling can be mitigated by applying mechanical stimulation to the aqueous solution, for example, by causing the aqueous solution to collide with the surface of a member or a metal mesh. However, such a method has a low effect of preventing overcooling, and hydrates are generated on the surface of the member or on the wire mesh. For this reason, there is a problem that the wire mesh and the pipe are blocked, and it is difficult to produce fine hydrate particles, which is not suitable for the production of hydrate slurry.
[0008]
[Problems to be solved by the invention]
The present invention has been made based on the above circumstances, effectively preventing supercooling, facilitating the production of fine hydrate particles, and efficiently producing a hydrate slurry having excellent fluidity. A method and an apparatus for producing a hydrate slurry that can be produced are provided.
[0009]
[Means for Solving the Problems]
The method of the present invention described in claim 1 is a guest compound of any of tetra n-butylammonium salt, tetraiso-amylammonium salt, tetraiso-butylphosphonium salt and triiso-amylsulfonium salt. When the aqueous solution containing water is cooled to produce hydrate particles, the core particles that form the hydrate particles are brought into contact with the aqueous solution to prevent overcooling of the aqueous solution, thereby producing hydrate particles. A method for producing a hydrate slurry, characterized in that tap water or industrial water is used as an aqueous solution, and fine particles contained in tap water or industrial water are used as core particles.
[0010]
When such an aqueous solution is cooled through the heat transfer surface and the core particles come into contact with this aqueous solution, supercooling is extremely effectively prevented, and fine hydrate particles in the aqueous solution are generated. It becomes easy and a hydrate slurry with high fluidity is produced.
[0011]
That is, in such an aqueous solution, the minute portions are successively brought into contact with the heat transfer surface, and the minute portions are sequentially cooled to a supercooled state. Of course, after a certain amount of time has passed, the minute portions of the aqueous solution are mixed to reach a uniform temperature. However, if the core particles in the aqueous solution are in contact with, for example, dispersed and suspended, The core particles to be immediately come into contact with a small portion of the aqueous solution in a supercooled state, and the supercooling is eliminated to produce hydrate particles.
[0012]
Therefore, since the supercooling state is eliminated before the entire aqueous solution reaches the supercooled state, the supercooling can be effectively prevented, and hydrate particles are generated, so that the water having high fluidity is used. A Japanese slurry can be produced efficiently.
[0027]
The apparatus according to claim 2 includes a guest compound of any one of a tetra-n-butylammonium salt, a tetraiso-amylammonium salt, a tetraiso-butylphosphonium salt, and a triiso-amylsulfonium salt. An apparatus for producing a hydrate slurry by cooling an aqueous solution to produce hydrate particles, an aqueous solution tank for storing the aqueous solution, and a heat generation exchange for cooling the aqueous solution supplied from the aqueous solution tank And supplying the core particles serving as nuclei of the hydrate particles to the aqueous solution supplied to the generation heat exchanger upstream of the supply port for supplying the aqueous solution to the generation heat exchanger. and a core particle supply mechanism, said product heat exchanger has a heat transfer surface by contacting the aqueous solution of the above to the heat transfer surface cooled, on the above small portion of the aqueous solution in the supercooled state Is intended to product a eliminates supercooled state hydrate particles by contacting the core particles, the above aqueous solution is tap water supply or industrial water containing the guest compound, the above core particles Are fine particles contained in tap water or industrial water.
[0028]
In addition, the aqueous solution according to claim 3 is cooled to obtain any one of a tetra-n-butylammonium salt, a tetraiso-amylammonium salt, a tetraiso-butylphosphonium salt, and a triiso-amylsulfonium salt. An aqueous solution for producing hydrate particles as a guest compound, which is tap water or industrial water containing the hydrate guest compound, and the fine particles contained in the tap water or industrial water are the above-mentioned It becomes a nucleus of hydrate particles and becomes a nucleus particle that prevents supercooling of the aqueous solution.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
When producing a hydrate slurry, it is effective to disperse and suspend the core particles, which are the nuclei of the hydrate particles, in an aqueous solution in order to prevent overcooling. It is particularly effective to use fine particles having a particle size of 10 μm or less as the core particles. Since such fine particles easily disperse and float in an aqueous solution, it has a very high effect of becoming a nucleus of hydrate particles and preventing overcooling. When the concentration of the core particles having a particle size of 10 μm or less in the aqueous solution is 0.1 mg / L or more, the core particles are in good contact with the aqueous solution and effective in preventing overcooling. General tap water has a turbidity of 1 degree when kaolin 1 mg / L is defined as 1 degree of turbidity, and about 20 degrees in industrial water, and therefore contains fine particles at a concentration of 0.1 mg / L or more. Therefore, overcooling can be prevented by using tap water or industrial water as the water of the aqueous solution containing the guest compound. When fine particles having a particle size of 10 μm or less are used as the core particles, the upper limit of the concentration in the aqueous solution is about 100 mg / L. If the fine particles are dispersed and suspended in a large amount exceeding the upper limit concentration, the heat transfer performance of the heat exchanger is lowered, which is not preferable.
[0035]
Further, when fine particles having a particle size of 100 μm or less are used as the core particles, stirring the aqueous solution makes it possible to disperse and float the core particles in the aqueous solution and to prevent overcooling. As a means for stirring, a means for generating a jet in an aqueous solution, a means for stirring by rotating a stirring blade, or the like is used. A preferred range of concentration in the aqueous solution is in the range of 1 mg / L to 5 g / L. If the concentration is higher than the upper limit value, it is not preferable because it causes spraying and stagnation in the hydrate slurry generator. If the concentration is lower than the lower limit, the effect of preventing overcooling will be reduced.
[0036]
Further, in the case where fine particles having a particle size of 300 μm or less are used as the core particles, the core particles are attached to a surface in contact with the aqueous solution such as an inner wall of the hydrate slurry generator, a stirring blade, etc. To prevent overcooling. The core particles are adhered to the aqueous solution so as to have a concentration of 1 g / L or more. You may adhere to the whole surface which contacts aqueous solution.
[0037]
Further, by using fine particles whose specific gravity is larger than the specific gravity of the aqueous solution as the fine particles, it is possible to prevent overcooling by dispersing and floating in the aqueous solution. Since the core particles settle in the aqueous solution, they are in good contact with the aqueous solution and are likely to become nuclei of the hydrate particles. By setting the design and operation method of the apparatus so that the time for the fine particles to settle in the aqueous solution in the hydrate generating apparatus and the time for generating the hydrate slurry are determined appropriately, the hydrate slurry can be stabilized. Can be manufactured.
[0038]
A method for producing hydrate particles by bringing various kinds of core particles as described above into contact with an aqueous solution and preventing supercooling is effective when used alone, but two or three are used in combination. Even a high effect can be obtained.
[0039]
Hereinafter, an embodiment of a method of the present invention and an apparatus for carrying out the method will be described with reference to the drawings. In this embodiment, an aqueous solution containing tetra n-butylammonium bromide (TBAB) as a guest compound is cooled to produce a hydrate slurry. In this embodiment, for ease of explanation and understanding, a plurality of aspects of the method according to the present invention are used in combination, and a plurality of aspects of the method of the present invention are implemented. However, in an actual apparatus and method, it is not always necessary to use all of them together.
[0040]
The code | symbol 1 in FIG. 1 shows the production | generation heat exchanger which cools said aqueous solution and produces | generates a hydrate slurry. In the case of this embodiment, as shown in FIG. 2, the generated heat exchanger 1 has a cylindrical shape, and its inner peripheral surface is formed as a heat transfer surface 1a, and a cooling medium flows around the heat transfer surface 1a. Surrounded by a cooling jacket 8. The cooling jacket 8 is configured so that a cooling medium is circulated from the refrigeration apparatus 2 by the pump 3 to cool the aqueous solution inside through the heat transfer surface 1a to generate a hydrate. .
[0041]
A rotation shaft 5 is disposed at the inner center of the generated heat exchanger 1, and the rotation shaft 5 is rotationally driven by the drive mechanism 4 at a predetermined speed. Further, a peeling blade member 9 having a spiral shape is attached to the rotating shaft 5, and the peeling blade member 9 rotates together with the rotating shaft 5 while being in sliding contact with the heat transfer surface 1 a. The hydrate adhering to the hot surface 1a is peeled off to prevent a decrease in the heat exchange efficiency of the heat transfer surface 1a, and the peeled hydrate is dispersed in an aqueous solution to produce a more uniform hydrate slurry. To do.
[0042]
Moreover, said peeling blade member 9 stirs the aqueous solution in this production | generation heat exchanger 1, and makes it a fluid state with the above effects. The means for bringing the aqueous solution into a fluid state is not limited to this, and a small portion of the aqueous solution flowing while contacting the heat transfer surface 1a in a laminar flow state and contacting the heat transfer surface 1a is inserted. Any means may be used as long as it is a means for maintaining the aqueous solution in a fluid state so as to prevent occurrence of a state that does not change.
[0043]
And as shown in FIG. 3, the surface 10 which adhered the nuclear particle is provided in the surface of said peeling blade member 9. As shown in FIG. The core particle adhering surface 10 is formed by mixing fine particles, for example, granulated slag particles finely crushed by injecting water into the slag of a blast furnace with a suitable binder. The core particle attachment surface 10 is not limited to the surface provided on the surface of the peeling blade member as described above, and may be anywhere as long as the surface of the member is in contact with the aqueous solution in a fluid state.
[0044]
Next, a mechanism for supplying and circulating an aqueous solution to the generated heat exchanger 1 will be described. Reference numeral 11 in the figure denotes an aqueous solution tank for storing the aqueous solution. The aqueous solution in the aqueous solution tank 11 is supplied to the supply port 6 of the generated heat exchanger 1 via the supply pipe 15 and the mixer 16 by the pump 13. To be supplied.
[0045]
And the hydrate slurry produced | generated by cooling in this production | generation heat exchanger 1 is discharged | emitted from the discharge port 7, is sent to the hydrate slurry tank 22 via the divider | distributor 21, and is stored. The hydrate slurry tank 22 and the aqueous solution tank 11 are provided with a stirring device 12.
[0046]
The hydrate slurry in the hydrate slurry tank 22 is taken out from the bottom of the tank and sent to the hydrate concentration controller 23. An aqueous solution is sent from the aqueous solution tank 11 through the pipe 29 to the hydrate concentration controller 23 through the pipe 29, and is mixed with the hydrate slurry as appropriate to obtain a solid phase fraction of the hydrate slurry. The equal concentration is adjusted and supplied to a load side device 26 such as an air conditioner via a feed pipe 25 by a pump 24. Then, the aqueous solution after being used in the load side device 26 is returned to the aqueous solution tank 11 via the return pipe 27.
[0047]
Next, a nuclear particle supply mechanism that is provided in the above-described pipeline and prevents overcooling will be described. First, a predetermined amount of core particles is mixed in the aqueous solution flowing through this system. Various kinds of nuclear particles can be used. The above-mentioned granulated slag particles are preferable, and these granulated slag particles are inexpensive, have stable characteristics, and are highly effective in preventing overcooling. The granulated slag particles have a specific gravity greater than that of the aqueous solution and have sedimentation properties.
[0048]
First, a part of the hydrate slurry discharged from the discharge port 7 of the product heat exchanger 1 is mixed with the mixer 16 by the pump 32 through the pipe 31 from the distributor 21. It is comprised so that it may be supplied to the supply port 6 of said production | generation heat exchanger 1 with aqueous solution.
[0049]
A part of the hydrate slurry taken out from the bottom of the hydrate slurry tank 22 is sent to the hydrate particle tank 34 for preventing overcooling via the pipe 33 and stored therein. The hydrate particle tank 34 is, for example, a heat insulation tank, and has the ability to store the hydrate slurry that has been sent for a predetermined period without melting the hydrate particles.
[0050]
Then, the hydrate slurry in the hydrate particle tank 34 is sent to the mixer 16 via the pipe 36 by the pump 35 and sent to the supply port 6 of the production heat exchanger 1 together with the aqueous solution. It is configured as follows.
[0051]
In addition, this apparatus is provided with a hydrate particle generation mechanism 14. This hydrate particle production mechanism can be operated independently of the hydrate production apparatus including the production heat exchanger described above, and produces a hydrate slurry containing a small amount of hydrate particles. I have the ability.
[0052]
The hydrate slurry produced by the hydrate particle production mechanism 14 is sent to the mixer 16 and is sent to the supply port 6 of the production heat exchanger 1 together with the aqueous solution. Yes.
[0053]
Next, the operation of the apparatus as described above and the method for preventing overcooling of the present invention will be described. First, when this apparatus is operated, the aqueous solution comes into contact with the heat transfer surface 1a in a fluidized state in the generated heat exchanger 1 and is cooled as described above. In this case, even if the minute portion of the aqueous solution comes into contact with the heat transfer surface 1a and becomes supercooled, the minute portion immediately flows and contacts the core particle adhesion surface 10 of the peeling blade member 9 described above. . Then, the contact with the core particles on the core particle attachment surface 10, that is, the granulated slag particles, eliminates the supercooling of the minute portions and generates hydrate particles. Thereby, the whole aqueous solution in this production | generation heat exchanger 1 does not become supercooling, but supercooling is prevented effectively.
[0054]
Further, as described above, core particles such as granulated slag particles are mixed in this aqueous solution, and a part thereof flows into the generated heat exchanger 1 together with this aqueous solution. Therefore, when the core particles come into contact with the supercooled minute portion of the aqueous solution, the supercooling is eliminated as described above, and hydrate particles are generated.
[0055]
When the hydrate particles are generated using the core particles as a core, the core particles are excluded from the generated particles. Therefore, the core particles in this aqueous solution are sent to the hydrate slurry tank 22 together with the produced hydrate slurry, separated in this tank, and settled at the bottom thereof. Therefore, when the operation of the apparatus is continued, the core particles gradually precipitate and accumulate on the bottom of the hydrate slurry tank 22, and the amount of the core particles floating in the aqueous solution decreases.
[0056]
And in order to cope with such a case, a part of discharged | hydrated hydrate slurry is supplied in the production | generation heat exchanger 1 via the mixer 16 via the said piping 31 and the pump 32. . The hydrate particles in the hydrate slurry eliminate supercooling and generate hydrate particles, similarly to the core particles. Since the hydrate particles are the same type of hydrate as the hydrate to be produced, they are the most effective nucleation nuclei and extremely effective in preventing overcooling.
[0057]
Moreover, when this apparatus restarts after stopping operation, the hydrate slurry discharged | emitted from the above production | generation heat exchangers 1 cannot be obtained. In such a case, the hydrate slurry stored in the hydrate particle storage tank 34 is supplied to the supply port 6 of the product heat exchanger 1 through the pipe 36.
[0058]
Even when all of the hydrate particles in the hydrate particle storage tank 34 have melted, the effect of preventing overcooling is obtained by supplying the aqueous solution in the tank to the generated heat exchanger 1. It is done. That is, as described above, since the core particles are deposited on the bottom of the hydrate slurry tank 22, the core particles are collected in the hydrate particle storage tank 34. Therefore, supercooling can be prevented by supplying the core particles together with the aqueous solution to the generated heat exchanger 1. Therefore, the hydrate particle storage tank 34 and the pipe line associated therewith also serve as a recovery / resupply mechanism for nuclear particles.
[0059]
In addition, when the hydrate slurry cannot be supplied from the hydrate particle storage tank 34 when the apparatus is started, the hydrate particle generation mechanism 14 is operated independently first. By supplying the produced hydrate slurry to the production heat exchanger 1 described above, overcooling can be prevented.
[0060]
As described above, if the operation of this apparatus is continued, the core particles may be deposited on the bottom of the hydrate slurry tank 22 and the core particles floating in the aqueous solution may be almost eliminated. When the apparatus is restarted in such a state, extremely large supercooling may occur. However, as described above, the hydrate particles are previously generated from the hydrate particle generation mechanism. By supplying to 1, overcooling can be effectively prevented.
[0061]
In order to avoid an undesirably large number of embodiments to be described, as described above, this embodiment includes a plurality of aspects of each mechanism and method of the apparatus of the present invention. However, it is not necessary to combine all of the above-described mechanisms and methods, and any one or a plurality of devices may be employed in an actual apparatus.
[0062]
Next, the results of experiments conducted to confirm the effects of the above-described methods and mechanisms will be described with reference to FIGS. In this experiment, when the TBAB aqueous solution was cooled and stirred, each of the above means, that is, when granulated slag particles having a particle size of 100 μm or less as the core particles were mixed in the aqueous solution to a concentration of 1 mg / L or more, The effect of, for example, immersing a member coated with granulated slag particles having a particle size of 300 μm or less as core particles in the case where hydrate particles are mixed is confirmed.
[0063]
As a reference example, in order to measure the state of supercooling when the aqueous solution was cooled without stirring, the aqueous solution of TBAB concentration of 25 wt% was cooled without stirring and measured using a differential calorimeter. . As a result, the aqueous solution was cooled to −16 ° C. and then the supercooling was released.
[0064]
FIG. 4 shows the case where the core particles are not mixed in the aqueous solution. As is clear from this figure, supercooling occurred to about −2 ° C. when the aqueous solution concentration was 40% or 19.8%.
[0065]
FIG. 5 shows a case where granulated slag particles having a particle diameter of 100 μm or less are mixed as core particles in an aqueous solution. As is apparent from this figure, it is shown that supercooling has a high effect of preventing overcooling up to about 5 ° C. when the aqueous solution concentration is 40% and up to 6 ° C. when the concentration is 19.8%.
[0066]
FIG. 6 shows a case where a glass rod having a granulated slag particle having a particle size of 300 μm or less as a core particle is immersed in an aqueous solution. When the concentration is 19.8%, it is supercooled to about 1 ° C. However, when the concentration is 40%, the supercooling is about 6 ° C., and depending on the concentration, the effect of preventing the overcooling is high.
[0067]
FIG. 7 shows a case where hydrate particles are mixed in an aqueous solution. In this case, for reference, the results of both cases of using distilled water and clean water for the preparation of the aqueous solution are shown. As is apparent from this figure, in each case, when the concentration is 19.8%, the supercooling occurs only at about 7 ° C., and when the concentration is 40%, only 10 ° C., and an extremely high effect is obtained. ing.
[0068]
In addition, this invention is not limited to said embodiment. For example, in the above-described embodiment, the case where the cooling drum-shaped generation heat exchanger provided with the peeling blade member is used has been described. However, the present invention is not limited thereto, and a shell-and-tube type generation heat exchanger is used. It can also be applied when used.
[0069]
Further, the core particles used in the present invention are not limited to those having a large specific gravity. For example, core particles having a specific gravity substantially equal to the specific gravity of the aqueous solution may be used. Since such core particles circulate together with the aqueous solution and do not settle, various problems caused by the precipitation of the core particles can be prevented.
[0070]
【The invention's effect】
As described above, according to the method and apparatus of the present invention, it is possible to extremely effectively prevent supercooling when the aqueous solution is cooled to produce a hydrate slurry. The effect is great because it can be carried out easily and easily.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an apparatus according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a part of the generated heat exchanger according to one embodiment.
3 is a cross-sectional view of a peeling blade member taken along line 3-3 in FIG.
FIG. 4 is a diagram showing the results of an experiment conducted to confirm the effect of the present invention.
FIG. 5 is a diagram showing the results of an experiment conducted to confirm the effect of the present invention.
FIG. 6 is a diagram showing the results of an experiment conducted to confirm the effect of the present invention.
FIG. 7 is a diagram showing the results of an experiment conducted to confirm the effect of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Generation | occurrence | production heat exchanger 1a Heat transfer surface 9 Separation blade member 10 Core particle adhesion surface 14 Hydrate particle generation mechanism 22 Hydrate slurry tank 34 Hydrate particle tank

Claims (3)

  Hydrated particles are cooled by cooling an aqueous solution containing a guest compound of any of tetra n-butylammonium salt, tetraiso-amylammonium salt, tetraiso-butylphosphonium salt and triiso-amylsulfonium salt. A method for producing a hydrate slurry by producing a hydrate particle by preventing the supercooling of an aqueous solution by bringing the core particle that becomes the nucleus of the hydrate particle into contact with the aqueous solution when producing the hydrate slurry. A method for producing a hydrate slurry, characterized in that tap water or industrial water is used as particles, and fine particles contained in tap water or industrial water are used as core particles. Hydrated particles are cooled by cooling an aqueous solution containing a guest compound of any of tetra n-butylammonium salt, tetraiso-amylammonium salt, tetraiso-butylphosphonium salt and triiso-amylsulfonium salt. An apparatus for producing a hydrate slurry by generating an aqueous solution tank for storing the aqueous solution, a generation heat exchanger for cooling the aqueous solution supplied from the aqueous solution tank, and the aqueous solution for generating the aqueous solution. A nuclear particle supply mechanism that supplies a core particle serving as a nucleus of the hydrate particle to the aqueous solution supplied to the generation heat exchanger at an upstream side from a supply port that supplies the exchanger. the heat exchanger has a heat transfer surface by contacting the aqueous solution of the above to the heat transfer surface cooled to contacting the nuclear particles to the above minute portion of the aqueous solution in the supercooled state The supercooled state is eliminated to produce hydrate particles, and the aqueous solution is tap water or industrial water containing the guest compound, and the core particles are converted to tap water or industrial water. An apparatus for producing a hydrate slurry, characterized in that the fine particles are contained.   Cooled to produce hydrate particles having any one of tetra n-butylammonium salt, tetraiso-amylammonium salt, tetraiso-butylphosphonium salt and triiso-amylsulfonium salt as a guest compound. An aqueous solution comprising tap water or industrial water containing a guest compound of the hydrate, and the fine particles contained in the tap water or industrial water serve as the nucleus of the hydrate particle, and the aqueous solution is supercooled. An aqueous solution characterized in that it becomes a core particle for preventing the above.

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