JP2009168221A - Liquefied natural gas satellite facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively use natural gas remaining in a lorry tank as well as contributing to prevention of global warming when reducing the inner pressure of the lorry tank after transferring LNG from a tank lorry to an LNG storage tank. <P>SOLUTION: In the LNG satellite facility, LNG is transferred from the lorry tank 13 provided in the tank lorry 12 to the LNG storage tank 25 and stored in the tank. The LNG is offloaded from the LNG storage tank, gasified by a vaporizer 29, and supplied as a fuel gas through an offloading line 28. The LNG satellite facility has a transfer line 23 which transfers LNG from the lorry tank to the LNG storage tank, pressurization lines 21, 22 for increasing the inner pressure force of the lorry tank when transferring the LNG, and a depressurizing line 31 which connects the lorry tank to the offloading line at the downstream side of the vaporizer while connecting the LNG storage tank to the offloading line at the downstream side of the vaporizer after completing the transfer of the LNG, with the lorry tank and LNG storage tank connected by the transfer line. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an LNG satellite facility that includes an LNG storage tank (storage tank) that receives LNG from a liquefied natural gas (LNG) tank lorry, and supplies LNG as fuel gas from the LNG storage tank to a consumer. The present invention relates to an LNG satellite facility having a mechanism for reducing the tank internal pressure of an LNG tank lorry after completion of transfer from the tank lorry and a lorry tank depressurizing method.

  In general, so-called LNG satellite facilities (satellite bases) are arranged in local cities to supply LNG as fuel gas to consumers, and this LNG satellite facility has an LNG storage tank (LNG storage for storing LNG). A tank) is provided, and the LNG stored in the LNG storage tank is vaporized by a vaporizer and supplied to a consumer as fuel gas. The LNG satellite facility (that is, the LNG storage tank) is periodically replenished with LNG by an LNG tank truck (hereinafter simply referred to as a tank truck).

  In such an LNG satellite facility, LNG is received (transferred) from a lorry tank (tank lorry tank) via an LNG transfer line. A fuel discharge line communicates from the LNG storage tank to a customer facility such as a gas turbine through a heat exchanger (vaporizer).

  Further, the LNG satellite facility branches from the LNG transfer line, communicates with the upstream side of the heat exchanger of the fuel discharge line, and sends LNG to the fuel discharge line in parallel with the supply of LNG to the LNG storage tank. A fuel discharge subline and a gas discharge line for sending the gas discharged from the lorry tank and the LNG storage tank to the vent stack via the heat exchanger are provided (for example, see Patent Document 1).

  By the way, when the LNG transfer from the tank lorry to the LNG satellite facility (that is, the LNG storage tank) is completed, the tank lorry will return from the LNG satellite facility to, for example, the tank lorry base. Prior to this, it is necessary to lower the internal pressure of the lorry tank to a predetermined level (value). That is, it is necessary to perform a depressurization operation (hereinafter referred to as a lorry tank depressurization operation).

Conventionally, when depressurizing a lorry tank, natural gas is discharged from the lorry tank outside the system to reduce the internal pressure of the lorry tank, but the internal pressure of the LNG storage tank may be higher than the internal pressure of the lorry tank. Natural gas remaining in the lorry tank is released from the vent stack to the atmosphere, and the internal pressure of the lorry tank is reduced.
JP 2002-54796 A

  However, when the natural gas remaining in the lorry tank is released into the atmosphere as in the prior art and the internal pressure of the lorry tank is lowered, the natural gas contains methane, which is a so-called greenhouse gas. There is a problem that it is not preferable for global warming.

  Furthermore, although the natural gas remaining in the lorry tank can be used as a fuel gas, it is released into the atmosphere, which is not preferable from the viewpoint of effective use of natural gas.

  Accordingly, the present invention contributes to the prevention of global warming when the LNG is lowered from the tank lorry to the LNG storage tank and then contributes to the prevention of global warming, and can effectively use the natural gas remaining in the lorry tank. The purpose is to provide.

  (1) The present invention transfers LNG from a tank provided in a tank lorry to an LNG storage tank, stores the LNG, discharges the LNG from the LNG storage tank, vaporizes the LNG with a vaporizer, and supplies fuel gas via a discharge line. LNG satellite equipment to be supplied as a transfer line for transferring the LNG from the lorry tank to the LNG storage tank, a pressure line for increasing the internal pressure of the lorry tank during the transfer of the LNG, After the transfer of LNG is completed, the LNG storage tank is connected to the discharge line on the downstream side of the carburetor in a state where the lorry tank and the LNG storage tank are connected by the transfer line, and the lorry tank is connected to the downstream of the carburetor. And a decompression line connected to the discharge line on the side.

  In the LNG satellite facility described in (1), after the transfer of the LNG to the LNG storage tank, the LNG storage tank is connected to the discharge line on the downstream side of the vaporizer by the depressurization line, and the lorry tank is connected to the downstream side of the vaporizer. Since it is connected to the payout line, the natural gas remaining in the lorry tank is sent directly or indirectly to the payout line. As a result, not only the internal pressure of the lorry tank can be lowered, but also the natural gas in the lorry tank is not released into the atmosphere.

  (2) The present invention is the LNG satellite facility according to (1), wherein the transfer line includes first and second branch lines connected to a lower part and an upper part of the LNG storage tank, respectively. The second branch line is provided with first and second on-off valves, respectively. The first and second on-off valves are opened when the LNG is transferred, and after the transfer of the LNG is completed, the first and second on-off valves are opened. The on-off valve 2 is closed.

  In the LNG satellite facility described in (2), the first and second on-off valves are opened when the LNG is transferred, and the second on-off valve is closed after the LNG transfer is completed. The natural gas is sent to the LNG storage tank, and the natural gas can be sent to the payout line via the LNG storage tank.

  (3) The present invention is the LNG satellite facility according to (2), wherein the first on-off valve is closed when an internal pressure of the lorry tank becomes equal to an internal pressure of the LNG storage tank. Is.

  In the LNG satellite facility described in (3), the first on-off valve is closed when the internal pressure of the lorry tank becomes equal to the internal pressure of the LNG storage tank. Can deliver natural gas directly from the lorry tank to the payout line.

  (4) The present invention provides the LNG satellite facility according to (3), wherein after the first and second on-off valves are closed, the inner pressure of the lorry tank is equal to or higher than the pressure of the fuel gas. Natural gas is supplied from the tank to the discharge line through the depressurization line.

  In the LNG satellite facility described in (4), when the internal pressure of the lorry tank is equal to or higher than the pressure of the fuel gas, natural gas is sent from the lorry tank to the discharge line via the depressurization line. Can be reduced.

  (5) The present invention is the LNG satellite facility according to any one of (1) to (4), wherein the depressurization line is a storage tank line connected to the LNG storage tank, and a lorry line connected to the lorry tank. The storage tank line is provided with a pressure regulating valve.

  In the LNG satellite facility described in (5), the depressurization line has a storage tank line connected to the LNG storage tank and a lorry line connected to the lorry tank, and the storage tank line is provided with a pressure regulating valve. Therefore, when the pressure in the LNG storage tank reaches a predetermined pressure, the natural gas in the LNG storage tank can be automatically sent to the depressurization line.

  (6) The present invention is the LNG satellite facility according to (5), wherein the lorry line is connected to at least the transfer line.

  In the LNG satellite facility described in (6), since the lorry line is connected to at least the transfer line, not only the natural gas in the lorry tank but also the natural gas in the transfer line can be sent to the decompression line.

  (7) The present invention is the LNG satellite facility according to (5), wherein the pressurization line is provided with a pressurizer, the lorry line is connected to the transfer line, and upstream of the pressurizer. It is connected to the said pressurization line by the side.

  In the LNG satellite facility described in (7), a pressurizer is provided in the pressurization line, and the lorry line is connected to the transfer line and connected to the pressurization line on the upstream side of the pressurizer. The natural gas in the transfer line and the pressurized line as well as the natural gas inside can be sent to the depressurization line.

  (8) In the LNG satellite facility according to any one of (1) to (7), the present invention is characterized in that a heater is provided in the depressurization line.

  In the LNG satellite facility described in (8), since the depressurization line is provided with a heater, the natural gas in the lorry tank can be heated to a desired temperature and supplied to the discharge line.

  (9) The present invention is the LNG satellite facility according to (8), wherein the liquefied natural gas is heated to a predetermined temperature by the heater.

  In the LNG satellite facility described in (9), since the natural gas is heated to a predetermined temperature by the heater, the natural gas is effectively heated by heating to the temperature required by the fuel gas supply destination. Can be used.

  (10) According to the present invention, in the LNG satellite facility according to any one of (1) to (9), when the internal pressure of the lorry tank reaches a predetermined pressure, the depressurization step is terminated. It is a feature.

  In the LNG satellite facility described in (10), when the internal pressure of the lorry tank reaches a predetermined pressure, the depressurization process is terminated, so that the internal pressure of the lorry tank can be lowered to a desired internal pressure.

  As described above, according to the present invention, after the transfer of LNG to the LNG storage tank, the LNG storage tank is connected to the discharge line on the downstream side of the vaporizer by the depressurization line, and the lorry tank is connected to the downstream side of the vaporizer. Since it is connected to the payout line, natural gas is not released into the atmosphere and can be used effectively as fuel gas, reducing the internal pressure of the lorry tank and contributing to the prevention of global warming. There is an effect that can be.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an example of an LNG satellite facility according to an embodiment of the present invention. The LNG satellite facility has an LNG receiving system 10, and this LNG receiving system 10 includes tank lorries by flexible hoses 11a to 11c. 12 is connected. The tank lorry 12 is provided with an LNG valve mechanism 12a, and the LNG receiving system 10 is connected to an LNG tank (hereinafter referred to as a lorry tank) 13 of the tank lorry 12 through the LNG valve mechanism 12a.

  The LNG receiving system 10 includes LNG pressurization lines 21 and 22, an LNG transfer line 23, a BOG (boil-off gas) line (not shown), and a vent line (not shown). , Piping. The LNG pressure lines 22 and 21 are connected to the flexible hoses 11a and 11b, respectively, and the LNG transfer line 23 is connected to the flexible hose 11c. The LNG pressurization lines 21 and 22 are connected to an LNG pressurizer (Lowry pressurizer) 24, and the LNG transfer line 23 is connected to an LNG storage tank (double shell storage tank) 25.

  The pressurization line 22 is provided with a pressure regulating valve 26, the LNG transfer line 23 is branched into two, and one branch line 23 a is connected to the lower part of the LNG storage tank 25. The other branch line 23 b reaches the upper part of the LNG storage tank 25. The branch lines 23a and 23b are provided with on-off valves 27a and 27b, respectively.

  A discharge line 28 is connected to the bottom surface of the LNG storage tank 25, and an LNG vaporizer 29 and a pressure regulating valve 30 are arranged on the discharge line 28, and LNG discharged from the LNG storage tank 25 is vaporized by the LNG vaporizer 29. And supplied to consumers as fuel gas.

  On the other hand, a depressurization line 31 is connected to the discharge line 28 between the LNG vaporizer 29 and the pressure regulating valve 30. The depressurization line 31 is provided with a warmer 32. On the downstream side of the warmer 32, the depressurization line 31 is branched into three lines, that is, first to third lines 31a to 31c. ing. Here, the first line 31a is a storage tank line, and the second and third lines 31b and 31c are lorry tank lines.

  The first line 31 a is provided with a pressure regulating valve 33, and the end of the first line 31 a is connected to the upper part of the LNG storage tank 25. The second line 31 b is connected to the LNG transfer line 23, and the third line 31 c is connected to the LNG pressurization line 21 before the lorry pressurizer 24.

  Referring also to FIG. 2, when receiving LNG from the lorry tank 13 to the LNG storage tank 25, as described above, the LNG pressurization lines 22 and 21, and the LNG transfer line 23 are respectively connected by the flexible hoses 11a, 11b, and 11c. Connected to the lorry tank 13 (flexible hose connection: step S1).

  Thereafter, although not shown, nitrogen gas is supplied from the nitrogen supply line to the LNG transfer line 23 and the LNG pressurization lines 21 and 22, and is discharged from the vent line, and the LNG transfer line 23, the LNG pressurization lines 21 and 22 are discharged. Air is replaced with nitrogen gas (nitrogen gas replacement: step S2).

  Subsequently, the nitrogen gas in the LNG transfer line 23 and the LNG pressurization lines 21 and 22 is discharged from the vent line to replace the nitrogen gas with natural gas (natural gas replacement: step S3). The on-off valves 27a and 27b are opened to bring the lorry tank 13 and the LNG storage tank 25 into communication with each other through the LNG transfer line 23. The LNG is vaporized to increase the pressure in the lorry tank 13 (increase in the lorry tank internal pressure: step S4).

  Then, LNG is transferred from the lorry tank 13 to the LNG storage tank 25 by the LNG transfer line 23 in accordance with the pressure difference between the pressure in the lorry tank 13 and the pressure in the LNG storage tank 25 (LNG transfer: step S5).

  In this manner, after the LNG is transferred from the tank lorry 12 to the LNG storage tank 25, the pressure in the lorry tank 13 is depressurized (a depressurization step).

  With reference to FIG. 3, the depressurization step will be described. In the state where the transfer of LNG to the LNG storage tank 25 is completed, the natural gas remains in the lorry tank 13, and the pressure in the lorry tank 13 is high due to this natural gas (lorry tank internal pressure> LNG storage tank). internal pressure).

  Therefore, the on-off valve 27b is closed. At this time, if the pressure regulating valve 33 operates, it may be impossible to transfer natural gas from the lorry tank 13 to the depressurization line. Therefore, it is desirable to forcibly close the pressure regulating valve 33. As a result, the natural gas remaining in the lorry tank 13 is sent to the LNG storage tank 25 through the LNG transfer line 23 (at this time, the natural gas is reliquefied in the LNG storage tank 25).

  Although not shown, the pressure gauge measures the internal pressure of the lorry tank and the internal pressure of the LNG storage tank, and determines whether or not the LNG storage tank internal pressure is equal to the lorry tank internal pressure (step S7). Then, the on-off valve 27a is closed (valve closing operation: step S8). Further, the forced closing of the adjustment valve 33 is stopped.

  When the pressure in the LNG storage tank 25 becomes equal to or higher than a predetermined pressure (step S9), the pressure regulating valve 33 operates as a pressure reducing valve, and the natural gas in the LNG storage tank 25 is heated by the heater 32 via the first line 31a. (Release of natural gas: step S10).

  On the other hand, if the internal pressure of the lorry tank after the pressure is lowered as described above> the fuel gas pressure (step S11), the natural gas is supplied from the lorry tank 13 through the second and third lines 31b and 31c. (Release of natural gas: step S12), the internal pressure of the lorry tank is further reduced. When the pressure in the lorry tank is depressurized to a predetermined pressure (step S13), the depressurization process is terminated (step S14).

  In this way, in the depressurization step, the natural gas remaining in the lorry tank 13 is transferred to the LNG storage tank 25, and further, the natural gas remaining in the lorry tank 13 is transferred to the LNG vaporizer via the depressurization line 31. 29, the natural gas remaining in the lorry tank 13 is not released into the atmosphere when the internal pressure of the tank lorry is lowered, that is, when the pressure is released.

  As a result, greenhouse gases are not released into the atmosphere, which can contribute to the prevention of global warming, and the natural gas remaining in the lorry tank 13 can be used effectively.

  In the depressurization step, it has been described that it is desirable to forcibly close the pressure adjustment valve 33. However, when the pressure in the LNG storage tank 25 rises and an alarm is generated, the pressure adjustment valve 33 The forced closing is stopped and the natural gas in the LNG storage tank 25 is preferentially sent to the heater 32.

  By the way, the aforementioned depressurization step may be performed by the control system shown in FIG. In FIG. 4, the control device 40 includes a valve control unit 41, a pressure detection unit 42, and a pressure comparison unit 43, and a console device 50 having an input unit and an output unit is connected to the control device 40. ing.

  When the depressurization process start command is given from the console device 50, the valve control unit 41 closes the on-off valve 27b, and further closes the pressure adjustment valve 33. The pressure detection unit 42 detects pressure values (lowry tank internal pressure and LNG storage tank internal pressure) measured by pressure gauges 51 and 52 provided in the lorry tank 13 and the LNG storage tank 25, respectively, and pressures the lorry tank internal pressure and the LNG storage tank internal pressure. This is given to the comparison unit 43.

  The pressure comparison unit 43 gives a first valve closing signal to the valve control unit 41 when the LNG storage tank internal pressure equals the lorry tank internal pressure. As a result, the valve control unit 41 closes the on-off valve 27a and stops closing the pressure regulating valve 33.

  By the way, after the above depressurization step is completed, nitrogen gas is supplied from the nitrogen gas supply line to the LNG transfer line 23, the LNG pressurization lines 21 and 22, and is discharged from the vent line. The natural gas in the LNG pressurization lines 21 and 22 is replaced with nitrogen gas.

It is a systematic diagram which shows an example of a structure of the LNG satellite installation by embodiment of this invention. It is a flowchart for demonstrating the transfer of LNG in the LNG satellite installation shown in FIG. It is a flowchart for demonstrating a depressurization process in the LNG satellite installation shown in FIG. It is a block diagram which shows an example of the control system used at the depressurization process shown in FIG.

Explanation of symbols

10 LNG receiving system 12 tank lorry 13 lorry tank 21, 22 LNG pressurization line 23 LNG transfer line 24 LNG pressurizer (Lowry pressurizer)
25 LNG storage tank 26, 30, 33 Pressure regulating valve 27a, 27b On-off valve 28 Discharge line 29 LNG vaporizer 31 Pressure release line

Claims (10)

Transfer and store liquefied natural gas from the tank provided in the tank lorry to the liquefied natural gas storage tank, discharge the liquefied natural gas from the liquefied natural gas storage tank, vaporize the liquefied natural gas with a vaporizer, and A liquefied natural gas satellite facility supplied as fuel gas via
A transfer line for transferring the liquefied natural gas from the lorry tank to the liquefied natural gas storage tank;
A pressurization line for increasing the internal pressure of the lorry tank when transferring the liquefied natural gas;
After the transfer of the liquefied natural gas, the liquefied natural gas storage tank is connected to the discharge line on the downstream side of the vaporizer while the lorry tank and the liquefied natural gas storage tank are connected by the transfer line. A liquefied natural gas satellite facility comprising a depressurization line connecting a tank to the discharge line downstream of the vaporizer. The transfer line has first and second branch lines connected to a lower part and an upper part of the liquefied natural gas storage tank, respectively.
The first and second branch lines are provided with first and second on-off valves, respectively.
2. The first and second on-off valves are opened during the transfer of the liquefied natural gas, and the second on-off valve is closed after the transfer of the liquefied natural gas is completed. Liquefied natural gas satellite equipment.   The liquefied natural gas satellite facility according to claim 2, wherein the first on-off valve is closed when an internal pressure of the lorry tank becomes equal to an internal pressure of the liquefied natural gas storage tank.   After closing the first on-off valve, when the internal pressure of the lorry tank is equal to or higher than the pressure of the fuel gas, natural gas is supplied from the lorry tank to the discharge line via the depressurization line. The liquefied natural gas satellite facility according to claim 3. The depressurization line has a storage line connected to the liquefied natural gas storage tank, and a lorry line connected to the lorry tank,
The liquefied natural gas satellite facility according to any one of claims 1 to 4, wherein the storage line is provided with a pressure regulating valve.   6. The liquefied natural gas satellite facility according to claim 5, wherein the lorry line is connected to at least the transfer line.   The pressurization line is provided with a pressurizer, and the lorry line is connected to the transfer line and is connected to the pressurization line on the upstream side of the pressurizer. 5. The liquefied natural gas satellite facility according to 5.   The liquefied natural gas satellite facility according to any one of claims 1 to 7, wherein the depressurization line is provided with a heater.   The liquefied natural gas satellite facility according to claim 8, wherein the liquefied natural gas is heated to a predetermined temperature by the heater.   The liquefied natural gas satellite equipment according to any one of claims 1 to 9, wherein when the internal pressure of the lorry tank reaches a predetermined pressure, the depressurization step is terminated.

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