Liquefied gas plant

Abstract

A liquefied gas plant according to one embodiment of the present disclosure is provided with: a storage region in which boil-off gas is present; a boil-off gas output pipe for outputting the boil-off gas in the storage area; an exhaust tower for discharging to the atmosphere the boil-off gas output from the storage area; and an inert gas supply pipe that supplies an inert gas to the exhaust tower such that the oxygen concentration in the exhaust tower is always lower than a limit oxygen concentration or the concentration of the boil-off gas in the exhaust tower is always lower than a lower limit explosion concentration.

Description

Technical Field

[0001] The present disclosure relates to a liquefied gas apparatus for processing liquefied gas. Background Art

[0002] Regarding liquefied gas equipment, Patent Document 1 discloses a vent mast that discharges volatile components (evaporated gas) of liquefied gas stored in a liquefied gas tank from the liquefied gas tank to prevent a pressure increase in the liquefied gas tank.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-194986 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In an exhaust tower such as a vent mast, if boil-off gas in the exhaust tower contacts an ignition source and ignites, a large fire with flashback and explosion may develop. Therefore, an object of the present disclosure is to provide a liquefied gas facility that can prevent the ignition of boil-off gas in the exhaust tower in advance.

[0008] Means for solving problems

[0009] A liquefied gas device in one embodiment of the present invention comprises: a storage area in which boil-off gas exists; a boil-off gas output piping that outputs the boil-off gas in the storage area; an exhaust tower that releases the boil-off gas output from the storage area into the atmosphere; and an inert gas supply piping that supplies an inert gas to the exhaust tower so that the oxygen concentration in the exhaust tower is always lower than the limiting oxygen concentration or the concentration of the boil-off gas in the exhaust tower is always lower than the lower explosion limit concentration.

[0010] Effects of the Invention

[0011] According to the above configuration, it is possible to prevent ignition of the boil-off gas in the exhaust tower in advance. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of the liquefied gas equipment according to the first embodiment.

[0013] Figure 2 This is a schematic diagram of a liquefied gas facility according to a second embodiment.

[0014] Figure 3 This is a flow chart of the inert gas supply control.

[0015] Figure 4 This is a schematic diagram of a liquefied gas facility according to a third embodiment. DETAILED DESCRIPTION

[0016] (First embodiment)

[0017] First, the liquefied gas equipment 100 according to the first embodiment will be described. Figure 1 This is a schematic diagram of a liquefied gas facility 100 according to the first embodiment. The liquefied gas facility 100 according to this embodiment may be mounted on a ship or installed on land.

[0018] like Figure 1 As shown, the liquefied gas facility 100 includes a storage area 10, a boil-off gas output pipe 20, a boil-off gas output valve 30, a gas exhaust tower 40, an inert gas supply pipe 50, and a control device 60. These components will be described below in order.

[0019] The storage area 10 is an area where boil-off gas exists. The storage area 10 is located inside a liquefied gas tank, for example, but may also be located inside a pipe. Examples of liquefied gas stored in the storage area 10 include liquefied hydrogen, liquefied natural gas (LNG), and liquefied petroleum gas (LPG). In the storage area 10, boil-off gas may exist from the beginning, or boil-off gas may be generated due to the gasification of part of the liquefied gas. The boil-off gas in this embodiment is a combustible gas.

[0020] The boil-off gas output pipe 20 is a pipe for outputting the boil-off gas in the storage area 10 from the storage area 10. The boil-off gas output pipe 20 of this embodiment is located between the storage area 10 and the exhaust tower 40. That is, the boil-off gas in the storage area 10 is output to the exhaust tower 40 via the boil-off gas output pipe 20.

[0021] The boil-off gas output valve 30 is a valve located in the boil-off gas output piping 20. The boil-off gas output valve 30 of this embodiment is a safety valve that opens when the internal pressure of the storage area 10 exceeds a predetermined value. However, the boil-off gas output valve 30 may be a valve other than a safety valve, for example, a manual valve that can be opened and closed arbitrarily by an operator. When the boil-off gas output valve 30 is opened, the boil-off gas in the storage area 10 is supplied to the exhaust tower 40.

[0022] The exhaust tower 40 is a device for releasing the boil-off gas in the storage area 10 to the atmosphere. When the liquefied gas equipment 100 is mounted on a ship, the ship's air mast corresponds to the exhaust tower 40. The exhaust tower 40 extends in the vertical direction, and the exhaust port 41 is located at the upper part. The boil-off gas is released to the atmosphere from the exhaust port 41.

[0023] The inert gas supply piping 50 is a piping for supplying an inert gas to the exhaust tower 40. The inert gas supply piping 50 of the present embodiment supplies an inert gas to the exhaust tower 40 via the evaporated gas output piping 20. Examples of the inert gas include nitrogen and argon. The upstream end of the inert gas supply piping 50 is connected to an inert gas generating device 101 that generates an inert gas. However, the upstream end of the inert gas supply piping 50 may be connected to a gas cylinder or tank truck that stores an inert gas instead of the inert gas generating device 101. In addition, the downstream end of the inert gas supply piping 50 is connected to a portion of the evaporated gas output piping 20 that is downstream of the evaporated gas output valve 30.

[0024] In addition, the regulator 51 and the flow meter 52 are located in the inert gas supply piping 50 of this embodiment. The regulator 51 is a device for adjusting the supply amount of the inert gas supplied to the exhaust tower 40. The regulator 51 of this embodiment is controlled by the control device 60, but it can also be controlled manually. The regulator 51 can also include, for example, an electric, hydraulic or pneumatic valve and a throttle hole. The flow meter 52 can measure the supply amount of the inert gas supplied to the exhaust tower 40. In addition, in Figure 1 In the figure, the flow meter 52 is located downstream of the regulator 51 , but the flow meter 52 may be located upstream of the regulator 51 , or may be located between components of the regulator 51 .

[0025] The control device 60 is a device for controlling the liquefied gas equipment 100. The control device 60 of this embodiment has a processor, a volatile memory, a non-volatile memory, an I / O interface, etc. Various programs and various data are stored in the non-volatile memory of the control device 60, and the processor uses the volatile memory to perform calculations based on the various programs.

[0026] The functions of the elements disclosed in this specification can be performed using circuits or processing circuits including general-purpose processors, special-purpose processors, integrated circuits, ASICs (Application Specific Integrated Circuits), existing circuits and / or combinations thereof that are constructed or programmed to perform the disclosed functions. The processor contains transistors and other circuits and is therefore considered a processing circuit or circuit. In the present disclosure, a circuit, unit or component is hardware that performs the listed functions, or hardware that is programmed to perform the listed functions. The hardware may be the hardware disclosed in this specification, or it may be other known hardware that is programmed or constructed to perform the listed functions. In the case where the hardware is a processor that is considered to be a type of circuit, the circuit, component or unit is a combination of hardware and software, and the software is used for the structure of the hardware and / or processor.

[0027] The control device 60 is electrically connected to the flow meter 52, and can obtain the supply amount of the inert gas based on the measurement signal received from the flow meter 52. In addition, the control device 60 is electrically connected to the regulator 51, and can adjust the supply amount of the inert gas supplied from the inert gas supply pipe 50 to the exhaust tower 40 by sending a control signal to the regulator 51.

[0028] The control device 60 of this embodiment supplies the inert gas from the inert gas supply pipe 50 to the exhaust tower 40 so that the oxygen concentration in the exhaust tower 40 is always lower than the limiting oxygen concentration, or the concentration of the evaporated gas in the exhaust tower 40 is always lower than the lower explosion limit concentration. In addition, the above-mentioned "limiting oxygen concentration" refers to the oxygen concentration at which the combustible gas does not explode when the oxygen concentration is reduced. In addition, the "lower explosion limit concentration" refers to the concentration of the combustible gas at the lower limit that causes an explosion.

[0029] Thus, in this embodiment, instead of supplying inert gas to the exhaust tower 40 to extinguish the ignition of the boil-off gas, the inert gas is supplied into the exhaust tower 40 in advance. Therefore, according to this embodiment, the ignition of the boil-off gas in the exhaust tower 40 can be prevented in advance.

[0030] Furthermore, in order to maintain the oxygen concentration in the exhaust tower 40 always lower than the limiting oxygen concentration or the boil-off gas concentration in the exhaust tower 40 always lower than the lower explosion limit concentration, the control device 60 of the present embodiment always supplies an inert gas to the exhaust tower 40. That is, the oxygen concentration and the boil-off gas concentration in the exhaust tower 40 are not acquired successively, but the inert gas is always supplied to the exhaust tower 40. In addition, the above-mentioned "always" refers to a state from which the boil-off gas output pipe 20 can supply the boil-off gas to the exhaust tower 40 to a state from which the boil-off gas cannot be supplied.

[0031] Therefore, according to the liquefied gas equipment 100 of this embodiment, the oxygen concentration in the exhaust tower 40 can be maintained at a state lower than the limiting oxygen concentration, or the concentration of the boil-off gas in the exhaust tower 40 can be maintained at a state lower than the lower explosion limit concentration without using complicated control.

[0032] The controller 60 may control the regulator 51 so that the amount of inert gas supplied to the exhaust tower 40 becomes a constant value or a desired target value. According to this configuration, an appropriate amount of inert gas can be quickly supplied to the exhaust tower 40, and the consumption of inert gas can be suppressed.

[0033] In addition, the control device 60 can also obtain the supply amount (actual supply amount) of the inert gas supplied to the exhaust tower 40 based on the measurement signal received from the flow meter 52, and control (i.e., feedback control) the regulator 51 based on the obtained actual supply amount. According to this structure, an appropriate amount of inert gas can be efficiently supplied to the exhaust tower 40.

[0034] In addition, in the present embodiment, the inert gas supply pipe 50 supplies the inert gas to the exhaust tower 40 via the boil-off gas output pipe 20. Therefore, ignition of the boil-off gas in the boil-off gas output pipe 20 can also be prevented in advance.

[0035] In addition, the above-mentioned control may be performed manually by an operator instead of being performed by the control device 60 .

[0036] (Second embodiment)

[0037] Next, a liquefied gas facility 200 according to a second embodiment will be described. Figure 2 FIG. 2 is a schematic diagram of a liquefied gas facility 200 according to the second embodiment. Figure 2 As shown, in the liquefied gas facility 200 of this embodiment, an oxygen concentration meter 42 capable of measuring the oxygen concentration in the exhaust tower 40 is located in the exhaust tower 40. The control device 60 is electrically connected to the oxygen concentration meter 42 and can obtain the oxygen concentration in the exhaust tower 40 based on the measurement signal received from the oxygen concentration meter 42.

[0038] In addition, the control device 60 of the present embodiment stores an inert gas supply control program in a nonvolatile memory, and performs calculation processing using the volatile memory based on the inert gas supply control program. The inert gas supply control program will be described below.

[0039] Figure 3 4 is a flowchart of the inert gas supply control program. The inert gas supply control program is a program for supplying an inert gas to the exhaust tower 40 and is executed by the control device 60.

[0040] like Figure 3 As shown, when the inert gas supply control program starts, the control device 60 obtains the oxygen concentration in the exhaust tower 40 (step S1). As described above, the control device 60 can obtain the oxygen concentration in the exhaust tower 40 based on the measurement signal received from the oxygen concentration meter 42.

[0041] Next, the control device 60 determines whether the oxygen concentration obtained in step S1 exceeds the reference value (step S2). The "reference value" in step S1 is set to a value slightly smaller than the above-mentioned "limiting oxygen concentration". Therefore, when the oxygen concentration exceeds the reference value, although the boil-off gas in the exhaust tower 40 will not ignite, it may be close to the limiting oxygen concentration. On the other hand, when the oxygen concentration does not exceed the reference value, the oxygen concentration is far from the limiting oxygen concentration, and the boil-off gas in the exhaust tower 40 will not ignite.

[0042] When it is determined in step S2 that the oxygen concentration exceeds the reference value ("Yes" in step S2), the control device 60 starts supplying the inert gas to the exhaust tower 40 when the oxygen concentration is likely to approach the limiting oxygen concentration (step S3). The control device 60 can start supplying the inert gas to the exhaust tower 40 by sending a control signal to the regulator 51. When the inert gas is started to be supplied to the exhaust tower 40, the oxygen concentration in the exhaust tower 40 does not reach the limiting oxygen concentration and becomes lower than the reference value. Therefore, the evaporated gas in the exhaust tower 40 does not catch fire. In addition, the control device 60 can also send a signal to an alarm device (not shown) at the same time as starting to supply the inert gas to the exhaust tower 40, so that the sound and image that the operator can recognize are output from the alarm device.

[0043] On the other hand, in step S2, when it is determined that the oxygen concentration does not exceed the reference value ("No" in step S2), that is, when the oxygen concentration is far different from the limiting oxygen concentration and the evaporated gas in the exhaust tower 40 will not ignite, the control device 60 returns to step S1 and repeats the above steps.

[0044] As described above, the liquefied gas equipment 200 of this embodiment is different from the liquefied gas equipment 100 of the first embodiment in that the oxygen concentration in the exhaust tower 40 is acquired and the supply of the inert gas to the exhaust tower 40 is started based on the acquired oxygen concentration. Other points have basically the same structure as the liquefied gas equipment 100 of the first embodiment.

[0045] In the second embodiment, an evaporation gas concentration meter for measuring the concentration of evaporation gas may be installed in the exhaust tower 40 instead of the oxygen concentration meter 42. On this basis, the control device 60 may obtain the evaporation gas concentration in the exhaust tower 40, and start supplying the inert gas to the exhaust tower 40 when the evaporation gas concentration exceeds a reference value (a value slightly smaller than the aforementioned lower explosion limit concentration).

[0046] (Third embodiment)

[0047] Next, a liquefied gas facility 300 according to a third embodiment will be described. Figure 4 1 is a schematic diagram of a liquefied gas facility 300 of the third embodiment. The liquefied gas facility 300 of the third embodiment is different from the liquefied gas facility 100 of the first embodiment in that the inert gas supply pipe 50 is not connected to the boil-off gas output pipe 20 but is directly connected to the exhaust tower 40. Other than this, the liquefied gas facility 300 of the third embodiment has the same structure as the liquefied gas facility 100 of the first embodiment.

[0048] Also in the liquefied gas facility 300 of the present embodiment, similarly to the liquefied gas facility 100 of the first embodiment, it is possible to prevent ignition of the boil-off gas in the exhaust tower 40 in advance.

[0049] In addition, if Figure 4 As shown, the inert gas supply piping 50 of the present embodiment is connected to the lower portion 43 ( Figure 4 According to this structure, the inert gas supplied to the lower portion 43 of the exhaust tower 40 flows toward the exhaust port 41, and the gas in the exhaust tower 40 is discharged from the exhaust port 41 in a manner of pushing upward from the bottom. Therefore, the gas such as oxygen in the exhaust tower 40 can be efficiently discharged.

[0050] (Summarize)

[0051] The first item disclosed in the present specification is a liquefied gas device, which comprises: a storage area where boil-off gas exists; a boil-off gas output piping, which outputs the boil-off gas from the storage area; an exhaust tower, which releases the boil-off gas output from the storage area into the atmosphere; and an inert gas supply piping, which supplies an inert gas to the exhaust tower so that the oxygen concentration in the exhaust tower is always lower than the limiting oxygen concentration or the concentration of the boil-off gas in the exhaust tower is always lower than the lower explosion limit concentration.

[0052] According to this configuration, ignition of the boil-off gas in the exhaust tower can be prevented in advance.

[0053] A second aspect disclosed in the present specification is the liquefied gas facility according to the first aspect, wherein the inert gas supply pipe constantly supplies the inert gas to the exhaust tower.

[0054] According to this configuration, it is possible to simplify the control of supplying the inert gas to the exhaust tower.

[0055] Item 3 disclosed in this specification is the liquefied gas facility according to Item 1 or 2, wherein the inert gas supply pipe starts supplying the inert gas to the exhaust tower when the oxygen concentration in the exhaust tower exceeds a predetermined reference value.

[0056] According to this configuration, the oxygen concentration in the exhaust tower can be suppressed, and ignition of the boil-off gas in the exhaust tower can be prevented in advance.

[0057] Item 4 disclosed in the present specification is the liquefied gas facility according to any one of items 1 to 3, wherein the inert gas supply pipe is connected to the boil-off gas output pipe.

[0058] According to this configuration, it is also possible to prevent the ignition of the boil-off gas in the boil-off gas output pipe in advance.

[0059] Item 5 disclosed in the present specification is the liquefied gas facility according to any one of Items 1 to 3, wherein the inert gas supply pipe is directly connected to the exhaust tower.

[0060] Even with this structure, it is possible to prevent ignition of the boil-off gas in the exhaust tower in advance.

[0061] Item 6 disclosed in this specification is the liquefied gas facility according to Item 5, wherein the inert gas supply pipe is connected to a lower third of the exhaust tower.

[0062] According to this configuration, the inert gas flows from the lower portion in the exhaust tower toward the exhaust port, and the air in the exhaust tower can be efficiently exhausted.

[0063] Item 7 disclosed in the present specification is the liquefied gas facility according to any one of Items 1 to 6, wherein the liquefied gas facility includes a regulator capable of adjusting the supply amount of the inert gas supplied to the exhaust tower.

[0064] According to this configuration, an appropriate amount of inert gas can be quickly supplied into the exhaust tower, and the consumption of the inert gas can be suppressed.

[0065] Item 8 disclosed in the present specification is the liquefied gas facility according to any one of Items 1 to 7, wherein the liquefied gas facility includes a flow meter capable of measuring the supply amount of the inert gas supplied to the exhaust tower.

[0066] According to this configuration, an appropriate amount of inert gas can be supplied to the exhaust tower.

[0067] Item 9 disclosed in the present specification is the liquefied gas facility according to Item 1, wherein the liquefied gas facility includes an oxygen concentration meter capable of measuring the oxygen concentration in the exhaust tower.

[0068] According to this configuration, an appropriate amount of inert gas can be supplied into the exhaust tower at an appropriate timing.

[0069] Description of symbols

[0070] 10: storage area; 20: evaporated gas output piping; 30: evaporated gas output valve; 40: exhaust tower; 42: oxygen concentration meter; 50: inert gas supply piping; 51: regulator; 52: flow meter; 100: liquefied gas equipment; 200: liquefied gas equipment; 300: liquefied gas equipment.

Claims

1. A liquefied gas device, comprising: Storage areas where boil-off gases are present; an evaporation gas output pipe for outputting the evaporation gas from the storage area; an exhaust tower for discharging boil-off gas output from the storage area to the atmosphere; and An inert gas supply pipe supplies an inert gas to the exhaust tower so that the oxygen concentration in the exhaust tower is always lower than the limiting oxygen concentration or the concentration of the boil-off gas in the exhaust tower is always lower than the lower explosion limit concentration.

2. The liquefied gas equipment according to claim 1, wherein: The inert gas supply pipe constantly supplies the inert gas to the exhaust tower.

3. The liquefied gas equipment according to claim 1, wherein: The inert gas supply pipe starts supplying the inert gas to the exhaust tower when the oxygen concentration in the exhaust tower exceeds a predetermined reference value.

4. The liquefied gas equipment according to claim 1, wherein: The inert gas supply pipe is connected to the boil-off gas output pipe.

5. The liquefied gas equipment according to claim 1, wherein: The inert gas supply pipe is directly connected to the exhaust tower.

6. The liquefied gas equipment according to claim 5, wherein: The inert gas supply pipe is connected to the lower third of the exhaust tower.

7. The liquefied gas equipment according to claim 1, wherein: The liquefied gas facility includes a regulator capable of adjusting the supply amount of the inert gas supplied to the exhaust tower.

8. The liquefied gas equipment according to claim 1, wherein: The liquefied gas facility includes a flow meter capable of measuring the supply amount of the inert gas supplied to the exhaust tower.

9. The liquefied gas equipment according to claim 1, wherein: The liquefied gas facility includes an oxygen concentration meter capable of measuring the oxygen concentration in the exhaust tower.

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