JP2010235718A - Gas hydrate production apparatus and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas hydrate production apparatus equipped with a depressurizing device that can treat a large amount, has few incidental facilities and is small-sized, and to provide a control method therefor. <P>SOLUTION: In the gas hydrate production apparatus 1, the depressurizing device 2 has a high-pressure tank 10 to which a mixture of pellets m and a sealing liquid L is supplied, an intermediate tank 11 in which the sealing liquid L is supplied and a pellet recovery part 12. One side of the intermediate tank 11 is connected to the high-pressure tank 10, the other is connected to the pellet recovery part 12 and the depressurizing device has a first circulation line 14a for circulating the sealing liquid L from the intermediate tank 11 to the high-pressure tank 10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a gas hydrate production apparatus for producing a gas hydrate such as natural gas, methane, ethane, and propane, and a control method therefor.

  For example, in the case of natural gas hydrate pellets or the like, the conventional gas hydrate pellet manufacturing process includes a generation process for generating gas hydrate under a high pressure environment of about 5.4 MPa, and a generated powder snow hydrate. It is composed of a molding step that is pressed into a spherical or almond-shaped pellet, a cooling step and a depressurizing step that cool and depressurize the pellet, and a storage step that is stored in a pellet storage tank under atmospheric pressure. Yes.

  FIG. 3 shows an example of the gas hydrate production apparatus 1X. The gas hydrate manufacturing apparatus 1X includes a generator 3 that generates gas hydrate, a molding device 4 that compresses the gas hydrate to process it into pellets m, a cooling device 5 that cools the pellets m, and a pellet m. It is comprised from the depressurization apparatus 2X which presses, and the storage tank 6 which stores the pellet m.

  First, the cooling process of the pellet m will be described. In the cooling device 5, the pellet m is cooled by the sealing liquid L. In order to accelerate this cooling, stirring may be performed with a motor or the like. Here, the sealing liquid L is comprised from the gas different from source gas, for example, liquid propane is used.

  Next, the depressurization process of the pellet m will be described. The cooled pellet m is conveyed together with the sealing liquid L to the decompression device 2X. The depressurizing device 2X is constituted by, for example, a lock hopper or the like, and has a high pressure side valve 13a and a low pressure side valve 13b. When the high-pressure side valve 13a is opened, the cooling device 5 filled with the sealing liquid L and the depressurizing device 2X communicate with each other, and the pellet m settles in the sealing liquid L due to gravity and enters the depressurizing device 2X. Moving. After the pellet m has moved into the depressurization device 2X, the high pressure side valve 13a is closed, the low pressure side valve 13b is opened, the pellet m is depressurized to atmospheric pressure, and the depressurization step is completed. The pellet m is stored in the storage tank 6 (for example, refer patent document 1).

  In the depressurization process described in Patent Document 1, the decompression drum (depressurization device 2X) to which the pellet m has been transferred is filled with the working fluid (sealing liquid L), the working fluid is flushed from the flash valve, and the decompression drum The inside is depressurized to atmospheric pressure. With this configuration, it is not necessary to increase the pressure of the atmospheric purge gas flowing into the storage tank 6 to the gas pressure of the raw material gas of about 5.4 MPa, and the power consumption in the gas hydrate manufacturing apparatus 1X can be suppressed. It is said.

JP 2006-52261 A

However, due to the configuration in which the pellet m is moved from the liquid phase of the cooling device 5 to the liquid phase of the depressurization device 2X, there is a problem that the movement time of the pellet m increases. That is, since the specific gravity difference between the pellet m and the sealing liquid L is very small, the sedimentation speed of the pellet m is extremely slow. Incidentally, the specific gravity of the pellet m is about 0.85~0.95g / cm ^3, sealing liquid L, if for example, liquid propane, 0.55~0.65g / cm ^3, if the oil 0.75 ~ 0.8
5 g / cm ³ . Here, in the case of constructing a plant for producing gas hydrate commercially, it is desired to process the depressurizer in a large amount.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is a gas hydrate manufacturing apparatus that can perform a large amount of processing, has few auxiliary facilities, and is small in size. An object of the present invention is to provide a gas hydrate manufacturing apparatus including a pressure device and a control method thereof.

  In order to achieve the above object, a gas hydrate manufacturing apparatus according to the present invention includes a generator for generating gas hydrate under conditions for generating gas hydrate, and a hydrate by dehydrating and pressing the gas hydrate. In a gas hydrate manufacturing apparatus having a molding device for molding pellets, a cooling device for cooling the pellets, a decompression device for decompressing the pellets, and a storage tank for storing the pellets, the decompression device comprises: A high-pressure tank supplied with a mixture of the sealing liquid of the pellets and the gas hydrate, an intermediate tank filled with the sealing liquid, and a pellet recovery unit, and one of the intermediate tanks is the high-pressure tank The other is connected to the pellet recovery unit, and further, a first circulation line for circulating the sealing liquid from the intermediate tank to the high-pressure tank is installed to form a circulation path for the sealing liquid. Characterized in that was.

  Here, as the sealing liquid, a liquefied gas having the same quality as the source gas, hexane, kerosene, silicon oil, or the like can be used.

  In the gas hydrate manufacturing apparatus, a second circulation line for circulating the sealing liquid from the pellet recovery unit of the depressurization apparatus to the intermediate tank is installed, and a circulation path for the sealing liquid is formed. To do.

  In the gas hydrate production apparatus, the depressurization device has a transport device in the pellet recovery unit, and the transport device is a solid-liquid separation type that takes out and transports only the pellets from the sealed liquid. It is a transport device.

  In the gas hydrate manufacturing apparatus described above, the depressurization apparatus includes a liquid return line for filling the sealing liquid from the pellet recovery unit having a gas phase to the intermediate tank.

  In the gas hydrate manufacturing apparatus, the depressurization apparatus is configured to remove the high-pressure tank and supply the pellet and the sealing liquid to the cooling apparatus, and the cooling apparatus and the intermediate tank are connected. And

  In order to achieve the above object, a method for controlling a gas hydrate manufacturing apparatus according to the present invention includes a generator for generating gas hydrate under conditions for generating gas hydrate, and dehydrating and pressing the gas hydrate. In a control method of a gas hydrate manufacturing apparatus having a molding apparatus for forming hydrate pellets, a cooling apparatus for cooling the pellets, a decompression apparatus for depressurizing the pellets, and a storage tank for storing the pellets, A cooling step in which the pellet and the sealing liquid are brought into contact with each other and cooled by the cooling device, and a high-pressure side valve installed between the cooling device and the intermediate tank installed in the depressurizing device and filled with the sealing liquid is opened. A pellet movement start step, a circulation pump of a first circulation line connecting the intermediate tank and the cooling device is operated, and the sealing liquid is moved forward from the intermediate tank. Circulating to a cooling device, forcibly moving the pellet to the intermediate tank, the pellet sedimentation promoting step, closing the high-pressure side valve, opening the low-pressure side valve installed between the intermediate tank and the pellet recovery unit, And a depressurizing step for depressurizing the pellet.

  According to the depressurization apparatus and the control method thereof according to the present invention, it is possible to provide a depressurization apparatus that can perform a large amount of processing, has a small number of incidental facilities, and is small, and a control method thereof. That is, the first circulation line that circulates the sealing liquid from the intermediate tank filled with the sealing liquid to the high-pressure tank causes the flow of the sealing liquid from the high-pressure tank to the intermediate tank. Can be positively moved to the intermediate tank by this flow. Therefore, it becomes possible to control the speed at which the pellets move from the high-pressure tank to the intermediate tank, and it is possible to realize mass processing of the depressurization apparatus.

  Further, it is easy to increase the flow rate of the pellets by increasing the flow rate of the sealing liquid circulating in the circulation line, and the processing amount of the depressurization device can be increased. Due to the increase in the throughput per unit time, the depressurization device can be made smaller than the conventional one.

  Furthermore, the configuration in which the second circulation line for circulating the sealing liquid is installed from the pellet recovery unit filled with the sealing liquid to the intermediate tank generates a flow of the sealing liquid from the intermediate tank to the pellet recovery unit. The pellet can be positively moved to the pellet collecting section by this flow.

  Furthermore, the pellet recovery unit is filled with the sealing liquid, and the solid-liquid separation type transport device that transports only the pellets from the sealing liquid to the storage tank of the next process is installed, so that it moves from the intermediate tank to the pellet recovery unit. It is possible to prevent the pellets to be broken by an impact such as dropping. That is, since the yield in pellet manufacturing increases, the mass production of pellets becomes possible.

  Moreover, even if it is a case where the pellet recovery unit is configured to include a gas phase by connecting the pellet recovery unit including the gas phase and the intermediate tank with a liquid return line, in the high pressure tank, the intermediate tank, and the pellet recovery unit Increase or decrease in the amount of sealing liquid can be suppressed. In addition, since the pellet recovery unit includes a gas phase, it becomes easy to remove the sealing liquid attached to the pellets. In other words, by reducing the number of ancillary equipment, the number of devices installed to improve the production volume of pellets can be increased, and the removal of the sealing liquid from the pellets can proceed efficiently, so that the pellets can be stored in an early stage. Can be sent by.

  Furthermore, by removing the high-pressure tank and using the cooling device as a high-pressure tank, the number of devices in the high-pressure region can be reduced, and as a result, the number of devices necessary for manufacturing other gas hydrates can be increased. This enables mass production of gas hydrate.

It is a figure which shows the decompression apparatus of embodiment which concerns on this invention. It is a figure which shows the decompression apparatus of different embodiment which concerns on this invention. It is the schematic of the conventional gas hydrate manufacturing apparatus.

  Hereinafter, a depressurization apparatus and a control method thereof in a gas hydrate production apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a depressurization apparatus 2A used in the depressurization process of the gas hydrate production apparatus 1.

  The depressurization apparatus 2A has a high-pressure tank 10, an intermediate tank 11, and a pellet recovery unit 12. One of the intermediate tanks 11 is a high-pressure tank 10 and the other is a pellet recovery unit 12, respectively. The intermediate tank 11 and the high-pressure tank 10 are connected via a valve 13b and a first circulation line 14a having a circulation pump 15a and a circulation valve 16a. Moreover, the pellet collection | recovery part 12 and the intermediate tank 11 are similarly connected by the 2nd circulation line 14b.

  In addition, a solid-liquid separation type transport device 17 that separates and extracts only the pellet m from the sealing liquid L is installed in the pellet recovery unit 12. For example, a bucket conveyor having a slit structure in the bucket can be used as the transport device 17.

  Note that the cooling device 5 shown in FIG. 3 can be used as the high-pressure tank 10. With this configuration, the scale of the gas hydrate production apparatus can be reduced. In particular, it is desirable to reduce the volume of the apparatus in the high pressure region.

  Next, control of the decompression device 2A will be described. First, the pellet m and the sealing liquid L are supplied from the cooling device 5 to the high-pressure tank 10. At this time, the high pressure side valve 13a and the low pressure side valve 13b are closed, and the intermediate tank 11 is filled with the sealing liquid L.

  With the start of the depressurization process of the pellet m, the high-pressure side valve 13a is opened, and the high-pressure tank 10 having a pressure of, for example, 5.4 MPa and the intermediate tank 11 having an atmospheric pressure communicate with each other. At this time, since the high-pressure tank 10 and the intermediate tank 11 are both filled with the sealing liquid L, expansion of gas such as flash does not occur.

  By opening the high-pressure side valve 13a, the pellet m starts to settle into the intermediate tank 11 due to gravity. At this time, the circulation valve 16a of the first circulation line 14a is opened, the circulation pump 15a is started, the sealing liquid is circulated in the direction of the arrow shown in FIG. Move actively to.

  After the pellet m moves to the intermediate tank 11, the high-pressure side valve 13a and the circulation valve 16a are closed, and the circulation pump 15a is stopped. Thereafter, the low pressure side valve 13b is opened, and the second circulation line 14b is operated in the same manner as described above to move the pellet m to the pellet recovery unit 12.

  The pellet m moved to the pellet collecting unit 12 is taken out from the sealing liquid by the transport device 17 and transported to the storage tank 6 which is the next process.

  By controlling the flow rate of the circulation line 14 described above, the moving speed of the pellet m can be controlled, so that an improvement in the pellet processing speed of the depressurizer 2A can be realized. That is, a large amount of pellet m can be processed in the decompression device 2A.

  Moreover, in the depressurization apparatus 2A, since the pellet m moves from the liquid phase to the liquid phase, the occurrence of flushing can be suppressed when the high pressure side valve 13a and the low pressure side valve 13b are opened. That is, a liquefying device for liquefying the sealing liquid L vaporized by the flash becomes unnecessary, and the incidental equipment can be reduced in scale. Furthermore, in the high-pressure tank 10, the intermediate tank 11, and the pellet recovery unit 12, since the amount of the circulating sealing liquid L does not increase or decrease, it is necessary to install incidental equipment for moving the sealing liquid L other than the circulation line 14. Absent.

  In addition, the pellet recovery unit 12 is filled with the sealing liquid L and the pellet m in the pellet recovery unit 12 is transported to the gas phase g by a bucket conveyor or the like, so that the pellet m gently lands on the bucket conveyor. It is possible to suppress the problem that the pellet m is broken by the impact of dropping, and the yield of pellet manufacturing can be improved. That is, mass production of the pellet m is possible. In addition, if the conveying apparatus 17 is a structure which isolate | separates and takes out only solid from a liquid phase, other conveying apparatuses, such as a screw conveyor, can also be used, for example.

The sealing liquid L is controlled to a temperature at which it does not vaporize in the decompression device 2A. For example, the high-pressure tank 10 is 5.0 to 5.8 MPa, −25 to −15 ° C., the pellet recovery unit 12 is atmospheric pressure, −25 to −15 ° C., and the intermediate tank 11 has these two conditions. The pressure and temperature are controlled within a range in which the change repeats between.

  Further, a filter that allows the sealing liquid L to pass but not the pellet m to pass through is installed at the inlet of the circulation line 14, and the circulation valve 16 is a commonly used valve such as a ball valve or a butterfly valve. It can be appropriately selected and used. Further, the depressurizing device 2 is not limited to the pellet m, and can be used with powdered snow-like hydrate powder before molding.

  FIG. 2 shows a depressurization apparatus 2B in a gas hydrate production apparatus according to another embodiment of the present invention. The depressurizer 2B uses the pellet recovery unit 12 as the gas phase g, connects the pellet recovery unit 12 and the intermediate tank 11 from the second circulation line, and returns to the liquid return line 18 having the liquid return pump 20 and the liquid return valve 21. Has been changed. In addition, a gas vent 19 is installed in the intermediate tank 11, and a belt conveyor is installed in the pellet recovery unit 12 as a transport device 17.

  Next, the control of the depressurizing device 2B will be described, but until the pellet m and the sealing liquid L of the high-pressure tank 10 are moved to the intermediate tank 11 filled with the sealing liquid L, the above-described operation shown in FIG. This is the same as the decompression device 2A. The pellets m and the sealing liquid L that have moved to the intermediate tank 11 fall on a transport device 17 such as a belt conveyor, for example, by opening the low-pressure side valve 13b. The pellet m is carried on the carrying device 17 and carried to the storage tank 6 in the next process.

  Then, the low pressure side valve 13 b is closed, and the sealing liquid L of the pellet recovery unit 12 is sent to the intermediate tank 11 by the operation of the liquid return line 18. At this time, the gas G in the intermediate tank 11 is discharged from the degassing line 19. After the filling of the sealing liquid L into the intermediate tank 11 is completed, the liquid return valve 21 and the valve (not shown) of the gas vent line 19 are closed, and the process proceeds to the next depressurizing process of the pellet m.

  As described above, the intermediate tank 11 and the pellet recovery part 12 are connected by the liquid return line 18 while the pellet recovery part 12 is in the gas phase g, so that the sealing in the high pressure tank 10, the intermediate tank 11, and the pellet recovery part 12 is performed. Since the amount of the liquid L does not increase or decrease, it is not necessary to install other incidental equipment. Moreover, since the pellet collection part 12 is made into the gaseous phase g, it becomes easy to remove the sealing liquid L adhering to the pellet m.

  However, depending on the processing amount of the pellet m, the depressurization device 2B may be destroyed when the pellet m falls on the transport device 17, and the yield in pellet manufacturing may be deteriorated. In this case, as in the depressurization apparatus 2A shown in FIG. 1, the pellet recovery unit 12 can be used as a liquid phase to suppress the destruction of the pellet m.

  Note that the gas G discharged from the gas vent 19 may be returned to the pellet recovery unit 12, and this structure eliminates the need for incidental equipment such as a gas G booster. Moreover, it is good also as a structure which sprays this gas G to the pellet m which moves on the conveying apparatus 17, and removes the sealing liquid adhering to the pellet m.

DESCRIPTION OF SYMBOLS 1 Gas hydrate manufacturing apparatus 2 Depressurization apparatus 3 Generator 4 Molding apparatus 5 Cooling apparatus 6 Storage tank 10 High pressure tank 11 Intermediate tank 12 Pellet collection part 13a High pressure side valve 13b Low pressure side valve 14a First circulation line 14b Second circulation line 15 Circulating pump 17 Conveying device 18 Liquid return line m Gas hydrate pellet (pellet)
L Seal liquid G Gas g Gas phase

Claims (6)

A generator for generating gas hydrate under the conditions for generating gas hydrate, a molding apparatus for forming hydrate pellets by dehydrating and pressing the gas hydrate, a cooling apparatus for cooling the pellets, and the pellets In a gas hydrate production apparatus having a depressurization apparatus for depressurizing and a storage tank for storing the pellets,
The depressurization apparatus includes a high-pressure tank to which a mixture of the pellet and the gas hydrate sealing liquid is supplied, an intermediate tank filled with the sealing liquid, and a pellet recovery unit, and the intermediate tank One is connected to the high-pressure tank, the other is connected to the pellet recovery unit, and further, a first circulation line for circulating the sealing liquid from the intermediate tank to the high-pressure tank is installed to form a circulation path for the sealing liquid A gas hydrate manufacturing apparatus characterized by the above.   A gas hydrate manufacturing apparatus, wherein a second circulation line for circulating the sealing liquid from the pellet recovery part of the depressurization apparatus to the intermediate tank is installed to form a circulation path for the sealing liquid.   The depressurization device has a transport device in the pellet recovery unit, and the transport device is a solid-liquid separation type transport device that takes out and transports only the pellets from the sealed liquid. The gas hydrate manufacturing apparatus according to claim 2.   2. The gas hydrate production apparatus according to claim 1, wherein the depressurization device has a liquid return line for filling the sealing liquid into the intermediate tank from the pellet recovery unit having a gas phase. .   The said depressurization apparatus remove | eliminated the said high pressure tank, it was set as the structure which supplies the said pellet and the said sealing liquid to the said cooling device, The said cooling device and the said intermediate tank were connected, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. The gas hydrate manufacturing apparatus as described in any one. A generator for generating gas hydrate under the conditions for generating gas hydrate, a molding apparatus for forming hydrate pellets by dehydrating and pressing the gas hydrate, a cooling apparatus for cooling the pellets, and the pellets In a control method of a gas hydrate production apparatus having a depressurization apparatus for depressurizing and a storage tank for storing the pellets,
A cooling step of bringing the pellet and sealing liquid into contact with each other and cooling with the cooling device;
Pellet movement start step for opening the high-pressure side valve installed between the cooling device and the intermediate tank installed in the depressurization device and filled with sealing liquid;
Activating a circulation pump of a first circulation line connecting the intermediate tank and the cooling device, circulating the sealing liquid from the intermediate tank to the cooling device, and forcibly moving the pellets to the intermediate tank When,
A depressurization step of closing the high pressure side valve, opening a low pressure side valve installed between the intermediate tank and the pellet recovery unit, and depressurizing the pellet;
A control method for a gas hydrate manufacturing apparatus, comprising:

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