JP5763324B2 - Gas hydrate manufacturing apparatus and gas hydrate manufacturing method - Google Patents

Description

  The present invention relates to a gas hydrate production apparatus and a gas hydrate production method for producing a gas hydrate such as methane and propane.

  In recent years, attention has been paid to a method using gas hydrate, which is a solid hydrate of these raw material gases, as a safe and economical means for transporting and storing natural gas and methane. A gas hydrate manufacturing apparatus for manufacturing the gas hydrate includes a generating device, a molding device, a cooling device, a decompression device, a storage, and the like. Gas hydrate is generally generated at high pressure and low temperature (for example, 6.0 MPaG, 4 ° C.) and stored under atmospheric pressure. Therefore, the depressurization device has a function of depressurizing the gas hydrate from a high pressure (for example, 6.0 MPaG) to atmospheric pressure (0.0 MPaG). As this depressurizing device, a rotary depressurizing device or the like is used (see, for example, Patent Document 1).

  FIG. 6 shows a gas hydrate production apparatus 1X. The gas hydrate manufacturing apparatus 1X includes a cooling device 31X that cools the gas hydrate generated by the generation device 30 in the sealing liquid L, a rotary depressurization device 2X, a transport device 32, and a storage 33. Yes. The decompression device 2X has a valve chamber that is rotatably installed in a spherical casing. The depressurization device 2X moves the gas hydrate with the sealing liquid L from the high pressure side (cooling device 31X) to the valve chamber, rotates the valve chamber, and discharges it to the low pressure side (transport device 32 side). The gas hydrate is depressurized. After the gas hydrate is discharged, the sealing liquid L is supplied into the valve chamber for pressurization. With this configuration, large power is not required for pressurization in the valve chamber.

  However, the above depressurization device has several problems when considering the enlargement of the gas hydrate business. First, since the gas hydrate is configured to move together with the sealing liquid, there is a problem that a large amount of sealing liquid is required. In particular, when considering the production of gas hydrate on, for example, an offshore drilling rig, it may be difficult to transport a large amount of sealing liquid to the offshore drilling rig. Moreover, even if the sealing liquid can be transported, there is a problem that a large cost is required for this purpose. Furthermore, there is a problem that the sealing liquid must be maintained in a limited space. As the sealing liquid L, liquid propane or the like is used.

  Secondly, when the sealing liquid is not used, it is necessary to pressurize the inside of the decompression device with a compressor or the like, and this pressurization process requires a great amount of energy. In particular, enormous amounts of energy are required when producing gas hydrates in large quantities.

  Thirdly, there is a problem that it takes time to increase the pressure in the decompression device. For this reason, when producing gas hydrate in large quantities, it becomes difficult to fully improve this production amount.

JP 2010-116263 A

The present invention has been made in view of the above problems, and an object of the present invention is a manufacturing apparatus and a gas hydrate manufacturing method for manufacturing a gas hydrate, in which a sealing liquid is unnecessary and the inside of the decompression apparatus is An object of the present invention is to provide a gas hydrate production apparatus and a gas hydrate production method capable of reducing energy for pressurization and preventing loss of gas accompanying the gas hydrate.

In order to achieve the above object, a gas hydrate production apparatus according to the present invention includes at least a generator that generates gas hydrate under high pressure , a depressurizer connected to the generator via a cooling device, In the gas hydrate manufacturing apparatus having a storage connected to the depressurization device via a transport device, the depressurization device receives the gas hydrate from the high pressure side, the depressurization tank and a plurality of lines A reservoir tank connected to the compressor, and a compressor. Further, a pressure equalization line communicating the decompression tank and the reservoir tank, and a gas in the decompression tank are supplied to the reservoir tank via the compressor. It has a depressurization line to send, and a pressurization line to send the gas in the reservoir tank to the depressurization tank through the compressor.

  With this configuration, it is possible to provide a gas hydrate production apparatus that does not require sealing liquid and that reduces energy for pressurizing the inside of the depressurization apparatus. That is, since the operation of pressurizing or depressurizing the depressurization tank is performed after the pressure is equalized between the depressurization tank and the reservoir tank, the energy required for the pressurization or depressurization can be suppressed. Moreover, the time for pressurizing or depressurizing the depressurization tank can be shortened. For example, when pressurizing the depressurization tank, pressurization is started from a pressure higher than the atmospheric pressure, so that the pressurization time can be shortened.

  In the gas hydrate manufacturing apparatus, the depressurization apparatus includes a plurality of depressurization tanks and a number of reservoir tanks equal to or less than the number of depressurization tanks. With this configuration, it is possible to easily increase the scale of the gas hydrate production apparatus using a plurality of depressurization apparatuses at low cost. This is because only the compressor requires power in the decompression device, and other than this compressor can be constituted by a pressure vessel and piping.

  In the gas hydrate manufacturing apparatus, a heat exchanger is installed in each of the pressure equalization line and the pressure line, and the heat exchanger is connected by a refrigerant circulation path. With this configuration, the pressure line can be cooled by the cold generated in the pressure equalizing line. That is, it is possible to reduce the amount of cold necessary to keep the depressurization tank at a low temperature, and to improve the production efficiency of the gas hydrate.

In order to achieve the above object, a gas hydrate production method according to the present invention includes at least a generator that generates gas hydrate under high pressure , and degass the gas hydrate generated by the generator from high pressure to atmospheric pressure. a depressurizing device for pressurizing, have a storage to store depressurized gas hydrate at atmospheric pressure in the dehydration pressure device, the previous SL depressurizing device, and de圧槽receiving a gas hydrate from the high pressure side, A reservoir tank connected to the depressurization tank by a plurality of lines; a compressor; a pressure equalization line communicating the depressurization tank and the reservoir tank; and a gas in the depressurization tank, Product made from gas hydrate which has a depressurization line which sends to the reservoir tank via a compressor, and a pressurization line which sends gas in the reservoir tank to the depressurization tank via the compressor A applying the device gas hydrate production method, a loading step of loading the gas hydrate in the de圧槽, opening the pressure equalizing line for connecting the reservoir tank and the de圧槽, the depressurizing a first pressure equalization step of pressurizing the reservoir tank and tank average, the gas in the de-圧槽, and depressurizing sending before Symbol reservoir tank through the depressurization line with the compressor, the de-圧槽A second pressure equalizing unit that discharges the gas hydrate in the chamber and sends it to the next process; and a pressure equalizing line that connects the depressurizing tank and the reservoir tank to equalize the depressurizing tank and the reservoir tank. a step, the gas in the reservoir tank, and having the pressure sending before Symbol de圧槽via pressure lines with the compressor.

  According to the gas hydrate manufacturing apparatus and the gas hydrate manufacturing method according to the present invention, no sealing liquid is required, energy for pressurizing the inside of the depressurization apparatus is reduced, and loss of gas accompanying the gas hydrate is lost. It is possible to provide a gas hydrate manufacturing apparatus and a gas hydrate manufacturing method that can prevent the above. Furthermore, the gas hydrate manufacturing apparatus and gas hydrate manufacturing method which can mass-produce gas hydrate can be provided.

It is the schematic which showed the depressurization apparatus of the gas hydrate manufacturing apparatus of embodiment which concerns on this invention. It is the figure which showed the pressure change in the depressurization tank of the manufacturing apparatus of embodiment which concerns on this invention. It is the figure which showed the pressure change in the depressurization tank of the manufacturing apparatus of embodiment which concerns on this invention. It is the figure which showed the pressure change in the reservoir tank of the manufacturing apparatus of embodiment which concerns on this invention. It is the figure which showed the pressure change in the reservoir tank of the manufacturing apparatus of embodiment which concerns on this invention. It is the schematic which showed the decompression apparatus of the conventional gas hydrate manufacture.

  Hereinafter, a gas hydrate manufacturing apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a depressurization apparatus 2 constituting a gas hydrate production apparatus 1 (not shown). The decompression device 2 includes a decompression tank 3 (first decompression tank 3a and second decompression tank 3b), a reservoir tank 4 (first reservoir tank 4a and second reservoir tank 4b), and a compressor 5. doing. Here, the depressurizing device 2 has at least one depressurizing tank 3 and a number of reservoir tanks 4 that do not exceed the depressurizing tank 3.

  The depressurization tank 3 and the reservoir tank 4 are connected to a pressure equalization line 7 (first pressure equalization line 7a and second pressure equalization line 7b) and pressure release line 8 (first pressure release line 8a and second pressure release line 8b). And pressurization line 9 (first pressurization line 9a and second pressurization line 9b). The pressure equalization line 7 directly connects the depressurization tank 3 and the reservoir tank 4. The pressure equalizing line 7 has a pressure equalizing valve 17 (a first pressure equalizing valve 17a and a second pressure equalizing valve 17b) in the middle part. The decompression line 8 is connected to the reservoir tank 4 from the decompression tank 3 via the compressor 5. The decompression line 8 has a decompression valve 18 (a first decompression valve 18a and a second decompression valve 18b) in the middle part. The pressurization line 9 is connected from the reservoir tank 4 via the compressor 5 to the depressurization tank 3. The pressurizing line 9 has a pressurizing valve 19 in the middle part. The depressurization tank 3 has a discharge port 6 (first discharge port 6a and second discharge port 6b). Further, the valves 21a and 21b are used to control the pressures of the reservoir tanks 4a and 4b, respectively. Normally closed.

  In FIG. 1, for the sake of simplicity, the pressure equalizing line, the depressurizing line, and the pressurizing line are shown as three independent pipes, but these are partially shared through valves or the like. It can also be formed as a conduit.

Next, the operation of the decompression device 2 will be described. In particular, the operation when the decompression device 2 has two decompression tanks 3a and 3b and two reservoir tanks 4a and 4b will be described. It is desirable that the depressurization device 2 has at least one depressurization tank 3 and has a number of reservoir tanks 4 equal to or less than the number of depressurization tanks 3. The reservoir tank 4 is desirably kept at a low temperature of −10 to −30 ° C.

  First, gas hydrate pellets (hereinafter referred to as pellets) formed by pressing and solidifying gas hydrate are transported from the previous step of the depressurization step (for example, the cooling device 31) to the first depressurization tank 3a (loading step). a). Moreover, the inside of the depressurization tank 3a is a high pressure (for example, 6.0 MPaG) and a low temperature (for example, −10 to −30 ° C.).

  When the transfer of the pellets into the first depressurization tank 3a is completed, the first transfer valve 16a is closed and the pressure equalization valve 17a of the pressure equalization line 7a is opened (first pressure equalization step b). Thereby, the first depressurization tank 3a having a high pressure (for example, 6.0 MPaG) and a low pressure (for example, atmospheric pressure, that is, 0.0 MPaG in gauge pressure) communicate with each other, and the pressure of the first depressurization tank 3a and the reservoir tank 4a is reduced. It will be equal. The pressure at this time varies depending on the volumes of the depressurization tank 3 and the reservoir tank 4, but is, for example, about 0.3 MPaG. Moreover, the opening speed of the pressure equalizing valve 17a may be controlled to mitigate the impact caused by the pressure change applied to the pellet.

  Thereafter, the pressure equalization line 7a is closed, and the pressure release valve 18a of the pressure release line 8a is opened. Further, the compressor 5 is operated. By the operation of the compressor 5, the gas (entrained gas) in the decompression tank 3a is moved to the reservoir tank 4a (decompression step c). Thereby, the depressurization tank 3a is depressurized to atmospheric pressure (gauge pressure is 0.0 MPaG).

  The discharge port 6a of the depressurization tank 3a depressurized to atmospheric pressure is opened, and the pellet is moved to the transport device 32 side of the next process (discharge step d). After the discharge of the pellet is completed, the discharge port 6a is closed, and the pressure equalizing line 7a is opened again (second pressure equalizing step e). Thereby, the depressurization tank 3a is pressurized from atmospheric pressure to a constant pressure. Thereafter, the pressure equalizing line 7a is closed, and the pressure valve 19a of the pressure line 9a is opened. Further, the compressor 5 is operated. With this control, the depressurization tank 3a is raised to the same pressure as the previous step (cooling step) (pressurizing step f). By repeating the above steps, the pellet is depressurized to atmospheric pressure and stored. Each valve is preferably connected to a control device (not shown) and controlled to be opened and closed by this control device.

  With the above configuration, the following operational effects can be obtained. First, it is possible to provide a depressurizing device that does not require sealing liquid and suppresses energy for pressurizing the inside of the depressurizing device. This is because the operation of pressurizing or depressurizing the depressurization tank is performed after the pressure is equalized between the depressurization tank and the reservoir tank, so that the energy required for this pressurization or depressurization can be suppressed. . In particular, when a large capacity depressurization tank is used, a high energy suppression effect can be obtained.

  Secondly, the time for pressurizing or depressurizing the depressurization tank can be shortened. For example, when pressurizing the depressurization tank, pressurization is started from a pressure higher than the atmospheric pressure, so that the pressurization time can be shortened. Therefore, this depressurization apparatus can cope with mass production of gas hydrate.

  Thirdly, it is possible to easily and inexpensively increase the scale of the gas hydrate production apparatus using a plurality of depressurization apparatuses. This is because the configuration using the reservoir tank eliminates gas loss, and the number of compression stages required for the compressor (compressor) can be reduced by utilizing the gas pressure. Thereby, power consumption can be reduced.

In addition, you may comprise so that the pressurization line 9 may be cooled using the cold heat which generate | occur | produces in the pressure equalization line 7. FIG. Specifically, heat exchangers are installed in the pressure equalization line 7 and the pressurization line 9, respectively, and the heat exchangers are connected by a refrigerant circulation path. In the pressure equalizing line 7, the temperature rapidly decreases to about −60 ° C. during the first pressure equalizing step b. This cold heat can be used to cool the heat generated in the pressurization line 9 during the pressurization step f.

  Moreover, you may comprise so that the open | release valve | bulb 20a of the 1st open | release line 10a which connects the decompression tank 3a and the conveying apparatus 32 may be open | released before opening the discharge port 6a at discharge step d. The opening / closing control of the opening valve 20a can reduce the possibility that the pellet is exposed to the impact of the pressure change accompanying the opening of the discharge port.

  2 and 3 show an example of how the pressure (gauge pressure) in the depressurization tank 3 changes. The vertical axis represents gauge pressure (MPaG) and the horizontal axis represents elapsed time (minutes). Note that the pressure change range, time, and the like vary depending on the scale of the decompression device 2 and the like. In FIG. 2, the state of the pressure in the carrying-in step a of the depressurization tank 3 is shown. Since the depressurization tank 3 communicates with the high-pressure portion of the previous process, it is constant at a high pressure (for example, 6.0 MPaG). During this time, the inside of the depressurization tank 3 is in a state where the pellets are moving from the cooling device 31 and are being accumulated. Moreover, the depressurization tank 3 discharges | emits the gas (entrained gas) of the same volume as the received pellet outside, and is maintaining the pressure constant.

  In FIG. 3, the pressure change from the 1st pressure equalization step b of the depressurization tank 3 to the pressurization step f is shown. In the first pressure equalization step b, the depressurization tank 3 and the reservoir tank 4 are communicated, and the pressure in the depressurization tank 3 decreases from 6.0 MPaG to 0.3 MPaG. The pressure at the time of pressure equalization varies depending on the capacity of the decompression tank 3 and the reservoir tank 4.

  In the depressurization step c, the gas (entrained gas, source gas) in the depressurization tank 3 is moved to the reservoir tank 4 by the compressor 5. Therefore, the pressure in the depressurization tank 3 is reduced to atmospheric pressure (0.0 MPaG in gauge pressure). In the discharge step d, the discharge port 6 of the depressurization tank 3 is opened, and the pellets are discharged out of the depressurization tank 3. In the second pressure equalization step e, the depressurization tank 3 and the reservoir tank are communicated, and the pressure in the depressurization tank 3 increases from 0.0 MPaG to 0.3 MPaG. As described above, the pressure during this pressure equalization varies depending on the capacity of the depressurization tank 3 and the like.

  In the pressurization step f, the gas in the reservoir tank 4 is moved to the depressurization tank 3 by the compressor 5. And the pressure in the decompression tank 3 is raised to a high pressure (for example, 6.0 MPaG).

  4 and 5 show an example of how the pressure (gauge pressure) in the reservoir tank 4 changes. The vertical axis represents a gauge pressure (MPaG) in a range different from the above, and the horizontal axis represents elapsed time (minutes). Note that the pressure change range, time, and the like vary depending on the scale of the decompression device 2 and the like. FIG. 4 shows the pressure state in the loading step a of the reservoir tank 4. The initial state of the reservoir tank 4 is atmospheric pressure (0.0 MPaG), and the pressure increases to, for example, 0.36 MPaG with time. This is because the gas (entrained gas) in the depressurization tank 3 discharged along with the pellet loading in the depressurization tank 3 is sent to the reservoir tank 4. That is, a gas having the same volume as that of the pellets carried into the decompression tank 3 is sent to the reservoir tank 4. It is desirable to move the gas at this time via the pressure equalizing line 7 and the pressure equalizing valve 17. Further, it is desirable that the pressure equalizing valve 17 has a check valve. At this time, the reservoir tank 4 is in a standby state.

  FIG. 5 shows the pressure change of the reservoir tank 4 from the first pressure equalizing step b to the pressurizing step f. In the first pressure equalization step b, the reservoir tank 4 and the depressurization tank 3 are communicated, and the pressure in the reservoir tank 4 increases from 0.36 MPaG to 0.45 MPaG. The pressure at the time of pressure equalization varies depending on the capacity of the decompression tank 3 and the reservoir tank 4.

In the decompression step c, the gas (entrained gas) in the decompression tank 3 is moved to the reservoir tank 4 by the compressor 5. Therefore, the pressure in the reservoir tank 4 rises to 0.5 MPaG. In the discharging step d, the reservoir tank 4 is in a standby state. In the second pressure equalization step e, the reservoir tank 4 and the depressurization tank 3 are communicated, and the pressure in the reservoir tank 4 decreases from 0.5 MPaG to 0.3 MPaG.

  In the pressurization step f, the gas in the reservoir tank 4 is moved to the depressurization tank 3 by the compressor 5. Then, the pressure in the reservoir tank 4 is reduced to a low pressure (for example, 0.0 MPaG). Note that the pressure in the initial state in the reservoir tank in the loading step a is not limited to atmospheric pressure, and can be set arbitrarily.

  The pellet can be depressurized by controlling the loading step a to the pressurizing step f in the depressurizing apparatus 2 described above. Next, control (parallel processing) in which this control is performed redundantly in the plurality of depressurization tanks 3 will be described. For example, a first system composed of a first depressurization tank 3a and a reservoir tank 4a, a second system composed of a second depressurization tank 3b and a reservoir tank 4b, and a depressurization apparatus composed of a single compressor 5 ( 2 will be described.

  Reservoir tanks 4a and 4b are connected to the depressurization tanks 3a and 3b, respectively. The compressor 5 is shared by the first system and the second system. The time during which the compressor 5 operates is only the decompression step c and the pressurization step f. Therefore, the first system and the second system are controlled so that the operation times do not overlap. With this configuration, about three systems of depressurization tanks 3 and the like can be connected to one compressor 5. Since this decompression device can install a plurality of decompression tanks 3 with respect to one compressor 5, it is possible to realize a large scale at a low cost.

  Further, as another embodiment, a depressurization apparatus constituted by a first depressurization tank 3a and a second depressurization tank 3b, one compressor 5 and one reservoir tank 4 will be described. In this depressurization apparatus, the second depressurization tank 3b controls the conveyance step a while the first depressurization tank 3a performs the control from the first pressure equalization step b to the pressurization step f. When the pressurization step f of the first depressurization tank 3a is completed and the control of the transport step a is started again, the second depressurization tank 3b is controlled from the first pressure equalization step b to the pressurization step f. I do. That is, the reservoir tank 4 repeats the control from the first pressure equalizing step b to the pressurizing step f. At this time, in the first pressure equalizing step b, the pressure in the reservoir tank 4 can be configured to increase from 0.0 MPaG to 0.45 MPaG. With the above configuration, the gas hydrate manufacturing apparatus can be downsized, and the cost of the gas hydrate manufacturing apparatus can be reduced.

  As described above, the pressure change in the depressurization tank 3 and the reservoir tank 4 has been described with specific pressure values. However, the present invention is not limited to this pressure value and is arbitrarily set. be able to.

DESCRIPTION OF SYMBOLS 1 Gas hydrate manufacturing apparatus 2 Depressurization apparatus 3 Decompression tank (3a 1st depressurization tank, 3b 2nd depressurization tank)
4 reservoir tanks (4a first reservoir tank, 4b second reservoir tank)
5 Compressor 6 outlet (6a first outlet, 6b second outlet)
7 Pressure equalization line (7a 1st pressure equalization line, 7b 2nd pressure equalization line)
8 Decompression line (8a 1st depressurization line, 8b 2nd depressurization line)
9 Pressurization line (9a 1st pressurization line, 9b 2nd pressurization line)
30 generator 31 cooling device 32 transport device 33 storage L sealing liquid

Claims (4)

A gas hydrate having a generator for generating at least a gas hydrate under high pressure, a depressurizer connected to the generator via a cooling device, and a storage connected to the depressurizer via a transport device In manufacturing equipment,
The depressurization apparatus has a depressurization tank that receives gas hydrate from the high pressure side, a reservoir tank connected to the depressurization tank by a plurality of lines, and a compressor,
Furthermore, a pressure equalization line communicating the depressurization tank and the reservoir tank;
A depressurization line for sending the gas in the depressurization tank to the reservoir tank via the compressor;
A gas hydrate manufacturing apparatus comprising a pressurization line for sending the gas in the reservoir tank to the depressurization tank through the compressor.   2. The gas hydrate manufacturing apparatus according to claim 1, wherein the depressurization apparatus includes a plurality of depressurization tanks and a number of reservoir tanks equal to or less than the number of depressurization tanks.   The gas hydrate production apparatus according to claim 1 or 2, wherein a heat exchanger is installed in each of the pressure equalization line and the pressure line, and the heat exchanger is connected by a refrigerant circulation path. A generator that generates at least a gas hydrate under high pressure, a depressurizer that depressurizes the gas hydrate generated by the generator from high pressure to atmospheric pressure, and a gas hydrate that is depressurized by the depressurizer. have a storage to store at atmospheric pressure, before Symbol depressurizing device comprises a de-圧槽receiving a gas hydrate from the high pressure side, and the reservoir tank connected with the de-圧槽a plurality of lines, the compressor And a pressure equalizing line communicating the depressurization tank and the reservoir tank, a depressurization line for sending the gas in the depressurization tank to the reservoir tank via the compressor, A gas hydrate production method applying a gas hydrate production apparatus having a pressurization line for sending gas to the depressurization tank through the compressor,
A loading step of loading the gas hydrate in the de圧槽,
Opening a pressure equalization line connecting the depressurization tank and the reservoir tank, and a first pressure equalization step for equalizing the depressurization tank and the reservoir tank;
The gas in the de-圧槽, and depressurizing sending before Symbol reservoir tank through the depressurization line with the compressor,
Discharging the gas hydrate in the depressurization tank and sending it to the next process;
Opening a pressure equalization line connecting the depressurization tank and the reservoir tank, and a second pressure equalization step for equalizing the depressurization tank and the reservoir tank;
Wherein the gas in the reservoir tank, the gas hydrate production method characterized by having a pressure sending before Symbol de圧槽via the pressure line having the compressor.

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