JP6370195B2 - Method and apparatus for supplying LNG to LNG storage tank - Google Patents

Description

  The present invention relates to a method and apparatus for supplying LNG to an LNG storage tank.

  In recent years, natural gas has attracted attention as an energy resource to replace oil and coal. Coupled with the shale gas revolution, liquefied natural gas (hereinafter referred to as LNG) is expected to be promoted more and more. In LNG satellite facilities, LNG is stored in storage tanks and supplied to consumers.

  At that time, LNG in the LNG storage tank is known to cause a rollover event due to its physical properties. LNG is known to be stratified between light and heavy components in LNG storage tanks. The upper LNG becomes heavier due to heat input. Although the temperature of the lower LNG rises due to heat input, the upper stratified LNG is lightened without being able to generate BOG (boil-off gas). When the density difference between the upper and lower LNG exceeds a certain level, convection called rollover occurs. BOG is generated abruptly from LNG that has risen to the top due to rollover. For this reason, it is assumed that the pressure in a storage tank rises rapidly and leads to damage of a storage tank. In order to prevent rollover, a device that generates jet mixing in the LNG storage tank is installed to destroy the boundary layer, or the LNG at the bottom of the storage tank is discharged to the outside at an early stage, causing boil-off gas. A method for eliminating gas has been proposed.

  In Patent Document 1, piping for supplying LNG to the LNG storage tank is provided above and below, pressure measuring means and flow rate adjusting means are provided, and the control amount is adjusted in accordance with the internal pressure to adjust the internal pressure of the LNG storage tank. Therefore, it is described that the boil-off gas generation amount is controlled.

  Patent Document 2 describes that the amount of boil-off gas generated is controlled using a bottom feed pipe depending on the size of the LNG liquid density.

JP 2008-95873 A JP 2001-324096 A

  It is said that there is a risk that an LNG boundary layer will be formed when receiving mixed LNG with different density differences. In the case of LNG satellite facilities, LNG storage tanks are unlikely to accept LNG with a large density difference because LNG tanks in large-scale LNG terminals are filled with LNG tanked tanks to prevent stratification. . However, the temperature rise due to external heat input and the occurrence of rollover due to evaporation in the LNG storage tank are not completely suppressed. For this reason, even in the case of an LNG satellite facility equipped with a tank lorry, rollover countermeasures have an important meaning. In the case of accepting different types of LNG, countermeasures for rollover have an important meaning. Especially when LNG storage tanks increase in the future, this rollover countermeasure becomes important.

  Patent Document 1 describes that the amount of boil-off gas generated is controlled. As the means, pressure measuring means and flow rate adjusting means are provided, and the control amount is adjusted according to the internal pressure. Yes. Patent Document 2 describes that the amount of boil-off gas generated is controlled using a bottom feed pipe depending on the size of the LNG liquid density.

  LNG storage tanks are expected to be installed more and more in the future. Providing additional means such as those described in the patent literature in a large number of LNG storage tanks that are expected to increase reduces the merit of supplying LNG at a low price, and increases the pressure each time LNG is supplied. There is an inconvenience that the change must be measured and the upper and lower acceptances must be frequently switched due to pressure changes. In addition, LNG has a large latent heat of vaporization due to its physical properties, so the pressure change caused by receiving from the upper part and the lower part is small, and the pressure change is hardly adjusted by filling both the upper part and the lower part. Conventionally, LNG acceptance from the lower part has become common. The LNG that is received is transported with a saturated liquid whose pressure is lower than the pressure in the LNG storage tank of the LNG satellite facility, so that when the pressure is adjusted and the lower part is received, the LNG will actively flow and cause mixing. Has not been made.

  In addition, non-conventional gas such as Sierl gas, which is different from conventional gas, has a large proportion of methane, and has a lower density than LNG that is currently widely imported. It is expected that the probability of rollover will increase when it is routinely received in small tanks such as the above, and it is possible to prevent the occurrence of boil-off gas that does not cause unmixing that occurs when different types of LNG mixed with different density Operation will be required.

  In view of the above, the present invention has been devised with a new LNG receiving / filling method under the present situation where the number of LNG satellite installations is rapidly increasing, making the operation easy and reducing the capital investment required to avoid rollover. The purpose is to propose measures that can be reduced, are inexpensive, and can reliably perform rollover avoidance operations and prevent boil-off gas generation.

In the present invention, an LNG upper receiving valve and an LNG lower receiving valve are provided in a pipeline connected to an LNG storage tank for supplying LNG, and LNG adjusted to a pressure higher than the internal pressure of the LNG storage tank is supplied to the LNG storage tank. In the LNG supply method to the storage tank,
The upper and lower connection ports to the LNG storage tank of the pipeline provided with the LNG upper receiving valve and the LNG lower receiving valve, respectively, are vertically opposed so that LNG is supplied from the connection port to the LNG storage tank,
The LNG upper receiving valve and the LNG lower receiving valve are periodically and regularly switched based on the switching signal, and are expressed in a mountain shape on the control basic line consisting of a predetermined planned receiving flow rate with respect to the LNG receiving elapsed time. An actual acceptance state is formed,
The actual receiving flow from the LNG lower receiving valve is supplied to the LNG storage tank from the lower connection port to form an agitation zone that periodically and regularly agitates the LNG in the LNG storage tank in the vertical direction of the LNG,
The actual incoming flow from the LNG upper receiving valve is supplied to the LNG storage tank from the upper connection port to the lower connection port, and the LNG in the uppermost layer region formed on the upper surface side of the stirring region in the LNG vertical direction is periodically cycled. A method for supplying LNG to an LNG storage tank is provided.

  The present invention provides an LNG supply method to an LNG storage tank, characterized in that, in the above-described LNG supply method to an LNG storage tank, the mountain shape is a symmetrical mountain shape.

  In the LNG supply method to the LNG storage tank described above, the present invention has a shape in which the actual receiving flow rate from the LNG lower receiving valve is expressed in a mountain shape larger than the actual receiving flow rate from the LNG upper receiving valve. A method for supplying LNG to an LNG storage tank is provided.

  The present invention is characterized in that, in the LNG supply method to the LNG storage tank described above, the actual receiving flow rate from the LNG lower receiving valve is set to be more than twice the actual receiving flow rate from the LNG upper receiving valve. Provides a method for supplying LNG to LNG storage tanks.

In the present invention, an LNG upper receiving valve and an LNG lower receiving valve are provided in a pipeline connected to an LNG storage tank for supplying LNG, and LNG adjusted to a pressure higher than the internal pressure of the LNG storage tank is supplied to the LNG storage tank. In LNG supply equipment to storage tanks,
The upper and lower connection ports to the LNG storage tank of the pipeline equipped with the LNG upper receiving valve and LNG lower receiving valve, respectively, are vertically opposed,
The LNG upper receiving valve and the LNG lower receiving valve are periodically and regularly switched based on the switching signal, and are expressed in a mountain shape on the control basic line consisting of a predetermined planned receiving flow rate with respect to the LNG receiving elapsed time. An actual acceptance state is formed,
An actual receiving flow is supplied to the LNG storage tank from the lower connection port, and an agitation zone is formed in which the LNG in the LNG storage tank is periodically and regularly agitated vertically.
The actual incoming flow is supplied to the LNG storage tank from the upper connection port correspondingly to the lower connection port, and the LNG in the uppermost layer area formed on the upper surface side of the stirring fluctuation area in the vertical direction of LNG is periodically and regularly stirred. An LNG supply system for LNG storage tanks is provided.

  The present invention provides an LNG supply apparatus for an LNG storage tank, characterized in that, in the above-described LNG supply apparatus for an LNG storage tank, the mountain shape is a symmetrical mountain shape.

  In the LNG supply apparatus to the LNG storage tank described above, the present invention has a shape in which the actual receiving flow rate from the LNG lower receiving valve is expressed in a mountain shape larger than the actual receiving flow rate from the LNG upper receiving valve. An LNG supply device for an LNG storage tank is provided.

  According to the present invention, in the LNG supply apparatus for the LNG storage tank described above, the actual flow rate receiving means in which the actual received flow rate from the LNG lower receiving valve is set to more than twice the actual received flow rate from the LNG upper receiving valve is provided. Provided is a supply device for an LNG storage tank.

  Based on the operation of the LNG upper receiving valve and LNG lower receiving valve to the LNG storage tank by the valve operation signal, the LNG storage tank is alternately filled with LNG adjusted to a pressure higher than the LNG storage tank pressure. Under the present situation where LNG fluctuations pulsating alternately in the vertical direction are formed and the number of LNG satellite facilities installed is increasing rapidly, the LNG receiving and filling method and equipment have been newly devised as described above, and the operation has been improved. It is simple, can reduce the capital investment required to avoid rollover, is inexpensive, reliably performs rollover avoidance operation, and boil-off does not cause unmixing that occurs when mixing different LNG with greatly different density differences Measures that can prevent the generation of gas are proposed.

The figure which shows the whole system of the Example of this invention. The figure which shows the Example of this invention with a block. The figure explaining the concept of the Example of this invention. The coordinate diagram which shows the control target line of the Example of this invention. The time chart figure of the Example of this invention. The figure which shows the liquid quantity and acceptance flow rate at the time of LNG storage tank LNG acceptance of the Example of this invention. The figure which shows the liquid quantity and acceptance flow rate at the time of LNG storage tank LNG acceptance of the other Example of this invention. The figure which shows the heterogeneous LNG mixing analysis at the time of filling from the lower part. The figure which shows the heterogeneous LNG mixing analysis at the time of filling from the upper part. The figure which shows the heterogeneous LNG mixing analysis at the time of filling periodically from both the lower part and the upper part.

  Hereinafter, the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an overall system of an embodiment of the present invention.

  FIG. 1 shows an LNG supply device 100 for an LNG storage tank. In FIG. 1, LNG from an LNG lorry 2 is supplied to a tank-type LNG storage tank 1. In the figure, as one example, the LNG lorry itself is configured as an LNG supply tank and has a supply pressure adjustment function. The LNG storage tank 1 has a tank configuration, in which LNG 3 is stored, and when there is no operation for avoiding rollover, a two-layer configuration of an upper LNG layer 4 and a lower LNG layer 5 is shown. In many cases, the LNG boundary layer 6 is formed between these two layers. A gas phase portion 7 is formed above the upper LNG layer 4.

  A pipeline 11 is disposed in the LNG storage tank 1. One side of the pipeline 11 is connected to the connection port of the installation type LNG lorry 2. The pipeline 11 is branched into a lower pipeline 12 for receiving a lower part and an upper pipeline 13 for receiving an upper part at a halfway point. The branch point is arbitrary. The lower pipeline 12 is connected to the lower part of the LNG storage tank 1 via a connection port 18 and opens toward the LNG storage tank LNG. In this way, the pipeline connected to the LNG storage tank that supplies LNG is equipped with an LNG upper receiving valve and an LNG lower receiving valve, and supplies LNG adjusted to a pressure higher than the internal pressure of the LNG storage tank to the LNG storage tank An LNG supply device 100 for the storage tank is formed.

  The upper pipeline 13 passes through the tank wall of the LNG storage tank and opens to the gas phase part 7. In addition, an LNG supply pipeline 15 for LNG derivation connected to the consumption facility 14 is connected to the lower part. The connection of the upper pipeline 13 to the LNG storage tank may be provided with a connection port that passes through the tank wall and opens to the gas phase part 7 or may be provided with a connection port 19 on the tank wall as shown in the figure. .

  The gas phase section 7 formed in the upper part of the LNG storage tank is connected to a test solution pipe 16 and a gas extraction pipe 17 which open into the gas phase section.

  In the configuration described above, the LNG supply device 100 is configured as follows.

  A lower receiving control valve 21 that is a receiving and filling control valve is installed in the lower receiving pipeline 12, and an upper receiving control valve 22 is installed in the upper receiving pipeline 13. The reception pressure A is formed by the upper reception control valve 22 and the reception pressure B is formed by the lower reception control valve 21 by the signal formed by the control device 25. Thus, these pressure signals are formed by the control device 25 formed on the personal computer. The control device 25 has arithmetic processing means, storage means, and communication means included in the personal computer, and has a program for management and control. Communication means can be provided in the control device 25. Measurement data is input to the control device 25 and a control signal is output. These signals may be exchanged by either a wireless system or a wired system. The control device 25, that is, a personal computer equipped with the control device 25, may be placed in an LNG lorry and used for the corresponding equipment when receiving the LNG, or controlled according to a control instruction from a control body installed in the central control room. You may do it. In this case, the terminal may be a stationary type or a portable type. In short, it is a terminal to which the LNG supply status from the LNG lorry is communicated. The type of terminal does not matter.

  A pressure gauge 23 and a liquid level gauge 24 that measure the LNG state at the lower part and the upper part to detect the LNG pressure are provided. Detection signals from the pressure gauge 24 and the liquid level gauge 23 are input to the control device 25 as a storage tank pressure signal C and a storage tank liquid level signal D.

  Each pipeline and piping is provided with a check valve, a stop valve, a three-way valve, a step-down adjustment valve, a shut-off valve, an automatic control valve, and a three-way valve as shown in the figure.

  FIG. 2 is an acceptance control block diagram for performing acceptance control by the control device 25.

  The control device 25 stores an automatic acceptance control curve 31 that will be described later. The automatic acceptance control curve 31 and the timer signal from the timer means 32 and the automatic acceptance start signal DI1 are input to the switching means SW33, and the automatic acceptance control curve 31 and the timer signal are sent as SV signals to the PID proportional control calculation means PID34. The PID proportional control calculation means 34 is supplied with the tank liquid level signal AI1 recognized as the process bar PV. The PID proportional control calculation means 34 calculates a deviation from the input SV and PV signals, generates a control signal, and outputs it as a control signal MV. The output MV signal is obtained by the multipliers 35 and 36 with a large flow rate signal, for example, 2.0 times the control target flow rate value and a small flow rate signal, for example 0.25 times the control target flow rate value. An operation is created on the signal. Which of the control signals is used for the operation is switched by the switching operation means 37 at a predetermined time based on the signal from the timer means 39, and is used as a large flow signal and a small flow signal for operation. Furthermore, whether the lower receiving control valve 21 or the upper receiving control valve 22 receives is switched by the switching calculation means 38 based on a signal from the timer means 40 in a certain time, and based on conditions preset in the program, A control signal A for the upper receiving control valve 22 and a control signal B for the lower receiving control valve 21 are generated. The timer means 40 can be incorporated in the control device 25 and may be of an external installation type, but it is recommended to use a time measuring means included in the calculation means.

  The control method is not limited to the PID proportional control method. Other control methods may be employed.

  FIG. 3 shows a method of supplying LNG to the LNG storage tank 1 from above and below.

  In FIG. 3, the lower and upper connection ports 18 and 19 of the pipelines 12 and 13 provided with the LNG lower receiving valve 21 and the LNG upper receiving valve 22 to the LNG storage tank 1 are arranged to face each other in the vertical direction. The lower and upper connection ports 18 and 19 are installed in the central portion of the LNG storage tank 1, and an axis of symmetry is formed around these. That is, LNG is alternately supplied from the lower side and the upper side on the axis of symmetry as shown in FIG. As shown in FIG. 3 by this alternate supply from the lower side and the upper side, the lower LNG is stirred while the stirring and mixing regions A to G are formed. Due to the installation of the lower and upper connection ports 18 and 19 arranged opposite to each other, a convection centered on the symmetry axis is formed in the LNG storage tank 1 over a wide area and the stirring is continued.

FIG. 4 shows an automatic acceptance control curve 31. The automatic acceptance control curve 31 can be displayed in a coordinate axis table in which the Y axis is the storage tank liquid level (%) and the X axis is the elapsed time (min). In this coordinate axis table, the control target line, the current storage amount, and the full liquid amount are displayed. An automatic receiving liquid level control curve is calculated from a received amount from the current liquid level data and a prefilled maximum filling amount by a program stored in advance, and a control target line is constructed as an automatic receiving liquid level control curve. . The automatic receiving liquid level control curve is constructed, for example, by setting the following control items in advance.
1) Set the time from the original storage amount to the full liquid amount. For example, 60 minutes.
2) The liquid level rise control curve is linear control.
3) Perform lower receiving lead control.
4) Upper acceptance is forcibly weaved three times within the acceptance time. Also, if the upper pressure rises during reception, the upper reception is forcibly performed.
5) The upper receiving time for regular insertion is 5 minutes / time. It may be 5 minutes or longer.
6) An LNG vibration forming method is adopted in which the received amount is periodically shaken 0.25 times (25%)-2.0 (200%) times the control target flow rate value based on the automatic receiving liquid level control curve.

  The numerical value shown here shows one example, and can be arbitrarily changed.

  The liquid level rising control curve by the automatic receiving liquid level control curve may be a liquid level rising straight line. In this way, a control target line is established.

  FIG. 5 shows an example of a time schedule.

LNG is supplied to the LNG storage tank, and a filling control signal for filling the LNG storage tank is obtained.
Acquires a filling control signal for filling LNG into the LNG storage tank. The control device 25 may generate a filling control signal for filling LNG into the LNG storage tank, or may input and acquire a filling control signal generated elsewhere. When LNG is supplied from the LNG lorry 2 to the LNG storage tank, it is expressed as “LNG supply”, when filling the LNG storage tank is expressed as “LNG filling”, and when viewed from the LNG storage tank, LNG filling is expressed as “LNG reception”. use.

  A switching signal is generated based on the signal from the timer means.

  Based on the switching signal, the filling control signal can be switched alternately, and the filling control signal is a set, and each of the LNG upper receiving control valve and the LNG lower receiving control valve is controlled corresponding to the filling control signal set A valve control signal is generated.

  Based on the control of the LNG upper receiving control valve and the LNG lower receiving control valve to the LNG storage tank by the valve control signal, the LNG storage tank is alternately filled with LNG adjusted to a pressure higher than the LNG storage tank pressure. In addition, LNG fluctuations that alternately pulsate vertically are formed.

  This pulsating LNG fluctuation can suppress or alleviate the formation of an LNG boundary layer in the LNG storage tank.

  In the LNG storage tank filling, a control target is determined as described above, and a filling result line is formed along the configured control target line. It is controlled by the control device and the personal computer so that the actual filling line is formed along the control target line. Examples of the control target line and the filling result line are shown in FIG. When filling the LNG storage tank with LNG, by using such a filling method, it is possible to avoid rollover sometimes by the operation itself of filling while performing the targeted filling.

  As described above, the filling control signal is generated into a large and small filling control signal composed of a large flow filling signal and a small flow filling signal, and the two large flow filling signals of the large and small filling control signals are the LNG storage tanks. The LNG fluctuation that alternately pulsates in the vertical direction is formed, and the small flow rate filling signal in the filling control signal is processed to adjust the LNG filling amount in the LNG storage tank within a predetermined time . It may be formed only with a large flow rate.

  FIG. 6 is a diagram showing the amount of liquid and the reception flow rate when receiving the LNG storage tank. The Y-axis is the amount of liquid in the storage tank (ton), and the X-axis is the elapsed time (min) of reception.

  FIG. 6 is a coordinate in which the Y-axis indicates the amount of liquid in the storage tank (ton), the receiving flow rate (kg / h), the receiving filling control valve opening degree (%), and the X-axis indicates the receiving elapsed time (min). The amount of liquid in the storage tank formed by filling the coordinates, the control basic line that is the control target line, the valve opening to the lower side B, the valve opening to the upper side A, the valve opening to the lower side B The liquid amount and the receiving flow rate at the time of receiving formed by the diagram formed from the receiving flow rate B based on and the receiving flow rate A based on the valve opening degree to the upper side A are shown.

  The control device 25 generates a filling control signal as a large and small filling control signal composed of a large flow filling signal and a small flow filling signal, and the two large flow filling signals of the large and small filling control signals are LNG. Arithmetic processing is performed so that LNG fluctuations that alternately pulsate in the vertical direction in the storage tank are formed, and the filling signal with a small flow rate in the filling control signal adjusts the LNG filling amount in the LNG storage tank within a predetermined time. To do.

  The set filling control signals are formed from two shapes having the same size, and the large and small filling control signals are formed from two shapes having the same size, and are the same in opposite directions as the filling method to the LNG storage tank 1. The small and large filling control signals are formed in two shapes having the same size in opposite directions. It is not limited to making it the same magnitude | size.

  Instead of the liquid amount and the reception flow rate shown in FIG. 6, the liquid amount and the reception flow rate shown in FIG. 7 may be adopted.

  The liquid amount and the reception flow rate at the time of reception shown in FIG. 7 are set so that the reception flow rate A based on the valve opening degree to the upper side A is smaller than the reception flow rate B based on the valve opening degree to the lower side B. The received flow B based on the valve opening to the lower side B is the same as the received flow B based on the valve opening to the lower side B shown in FIG. By doing so, the number of fillings of the receiving flow rate A from the upper side A and the lower side B receiving flow rate B shown in FIG. The number of times can be increased as a group.

  The amount of LNG in the LNG storage tank is controlled like any of the liquid volumes in the storage tank described above with respect to the control basic line. The received amount is automatically switched from the upper part and the lower part to each large flow-small flow, and is formed by the energy of the LNG in which the LNG in the LNG storage tank is filled with the LNG vibration fluctuation motion. The kinetic energy causing the LNG vibration fluctuation motion is given by the energy of LNG based on the filling operation. For this reason, LNG adjusted appropriately to a pressure higher than the internal pressure of the LNG storage tank is supplied to the LNG storage tank.

  Based on the switching signal, the LNG upper receiving valve and the LNG lower receiving valve are periodically and regularly switched, and the LNG lower receiving valve for the control basic line consisting of a predetermined planned receiving flow rate for the LNG receiving elapsed time. An actual receiving state is formed which is expressed by a mountain shape in which the actual receiving flow rate from the LNG is the same or larger than the actual receiving flow rate from the LNG upper receiving valve.

  The actual receiving flow from the LNG lower receiving valve forms an agitation zone where the LNG in the LNG storage tank is periodically and regularly agitated vertically. That is, the actual receiving flow from the LNG lower receiving valve is supplied from the lower connection port to the LNG storage tank to form an agitation region that periodically and regularly agitates the LNG in the LNG storage tank in the vertical direction of the LNG.

  The actual incoming flow rate from the LNG upper receiving valve is formed on the upper surface side of the stirring area in the LNG vertical direction. The LNG is periodically and regularly agitated in response to the actual reception from the LNG lower receiving valve. That is, the actual receiving flow from the LNG upper receiving valve is supplied to the LNG storage tank from the upper connection port to the lower connection port, and the LNG in the uppermost layer region formed on the upper surface side of the stirring region in the LNG vertical direction is reduced. Stir periodically and regularly.

  An LNG supply method to the LNG storage tank having such characteristics is formed.

  By performing such operation control, a flow is formed in the LNG stored by the lower switching acceptance by the receiving operation to the LNG storage tank, and the LNG vibration fluctuation is formed. The flow is further promoted by giving a large change and pulsation to the incoming flow rate, and the formation of the layered boundary in the LNG storage tank is suppressed, and when the LNG boundary layer is formed, it is destroyed early. To do. Thereby, the occurrence of the rollover phenomenon is suppressed.

  In the LNG receiving method for different types of LNG in the LNG tank, the LNG upper layer area, which is formed on the upper surface side of the LNG up-and-down agitation fluctuation area and is difficult to agitate due to the LNG up-and-down agitation, is prevented. Therefore, the LNG in the stirring area in the vertical direction of LNG is required to be stirred.

  In the present embodiment, the received flow rate A based on the valve opening to the upper side A is employed to prevent the LNG upper layer region from expanding.

8 to 10 are diagrams showing a heterogeneous LNG mixture analysis. FIG. 8 is a diagram showing a heterogeneous LNG mixture analysis when filling from the lower part of 90 _VOL % → 40 _VOL %, and FIG. 9 is a figure showing a heterogeneous LNG mixture analysis when filling from the upper part of 90 _VOL % → 40 _VOL %. FIG. 10 is a diagram showing a heterogeneous LNG mixture analysis in the case of filling from both the lower and upper portions of 90 _VOL % → 40 _VOL %.

◆ Assumption LNG90 = filling rate 90 _VOL % LNG
LNG40 = LNG at a filling rate of 40 _VOL %
The liquid phase part is set as the analysis region. LNG90 is introduced into LNG40 for 5 minutes. A stirring and mixing state is formed by turbulent diffusion ◆ LNG90
Composition (volume fraction): CH4 0.888, C2H6 0.056, C3H8 0.037
C4H10 0.018, N2 0.001
Average molecular weight: 18.63
Density (kg / m ³ ): 459.35
Viscosity coefficient (μPa sec): 98.68
In FIG. 8, by performing the unsteady fluid analysis, the different LNG stirring and mixing states in the LNG storage tank shown below were grasped. In addition, FIG. 8 shows the left half of the LNG storage tank with the LNG storage tank placed horizontally and centering on the target axis as the center line, and in order to see the whole, it is required to expand the screen to the right side. .

◆ 60 to 300 sec elapsed In the vicinity of the liquid level, as the time passes from the start of filling, the LNG 90 volume concentration increases as shown by the concentrations A to F along the liquid level from the vicinity of the target axis.

  The concentration H indicates LNG40.

    As time elapses from the start of filling, the LNG 90 volume concentration is increased so as to follow the target axis from the liquid level to the liquid level, and from the vicinity of the symmetry axis to the liquid level. The uppermost layer is only LNG 90 volume concentration.

◆ After 300 sec
LNG The upper layer region of LNG that is difficult to stir is formed and expanded by stirring in the vertical direction.

In FIG. 9, by performing the unsteady fluid analysis, the different types of LNG stirring and mixing states in the LNG storage tank shown below were grasped.
◆ 60 to 300 sec elapsed In the vicinity of the liquid level, as the time passes from the start of filling, the LNG 90 volume concentration becomes higher as indicated by the concentrations M to Q along the liquid level. And a liquid level stirring mixing state expands.
In FIG. 10, by performing the unsteady fluid analysis, the different LNG stirring and mixing states in the LNG storage tank shown below were grasped. The state shown in FIG. 10 corresponds to the state shown in FIG. In the vicinity of the liquid surface, as time passes from the start of filling, the LNG 90 volume concentration increases as shown by the concentrations A to G along the liquid surface from the vicinity of the symmetry axis. It is formed. As time passes from the start of filling, the stirring / mixing state in which the volume concentration of LNG 90 is increased so that the liquid level is along the axis of symmetry and then along the liquid level from the vicinity of the axis of symmetry is the LNG storage tank. It will reach the bottom.

  LNG upper layer region that is difficult to stir by the initial LNG upward stirring at the start of filling was formed, but from the start of filling as shown in 240 seconds by filling the receiving flow rate A based on the valve opening to the upper side A As time passes, the volume concentration of LNG90 increases so as to follow the axis of symmetry up to the liquid level, and then from the vicinity of the axis of symmetry to the liquid level. It became a mixed state.

  Adoption of the receiving flow rate A based on the valve opening to the upper side A is to prevent the expansion of the LNG upper layer area, which is difficult to stir by stirring in the vertical direction of LNG, and is sufficiently aimed by the filling method shown in FIG. Therefore, the filling method shown in FIG. 7 is recommended for suppressing the occurrence of the rollover phenomenon rather than the filling method shown in FIG.

  Thus, the layering that forms the boundary can be suppressed, the occurrence of the rollover phenomenon can be prevented, and the generation of boil-off gas can be suppressed.

  Conventionally, in order to suppress the formation of the LNG boundary layer in the tank, a method of providing a kinetic energy by installing a jet pump in the tank has been proposed. In this case, the operation is used to give the LNG vertical kinetic energy, so it is possible to give the LNG vertical kinetic energy without installing a special device such as a jet pump in the LNG storage tank. The layering that will form the LNG boundary is suppressed, the occurrence of the rollover phenomenon is suppressed, and the LNG upper layer region, which is difficult to stir by the stirring of the LNG in the vertical direction, is prevented when filling different types of LNG. Is achieved.

  According to this embodiment, the LNG storage tank is alternately filled with LNG adjusted to a pressure higher than the internal pressure of the LNG storage tank based on the operation of the LNG upper receiving valve and the lower LNG receiving valve in the LNG storage tank by the valve operation signal. Under the current situation where LNG fluctuations that alternately pulsate in the vertical direction are formed in the LNG in the LNG storage tank, and the number of installations of LNG satellite facilities is increasing rapidly, the LNG receiving and filling method and equipment are new as described above. It is devised, easy to operate, can reduce the capital investment required to avoid rollover, is inexpensive, and reliably performs the rollover avoidance operation, and also occurs when mixing different types of LNG with greatly different densities A countermeasure is proposed that can prevent the generation of boil-off gas in which no unmixing occurs.

DESCRIPTION OF SYMBOLS 1 ... LNG storage tank, 2 ... LNG lorry, 3 ... Stored LNG, 4 ... Upper LNG, 5 ... Lower LNG, 6 ... LNG boundary layer, 7 ... Gas phase part, 11 ... Pipeline, 12 ... Lower pipeline, DESCRIPTION OF SYMBOLS 13 ... Upper pipeline, 15 ... LNG supply pipeline, 21 ... Lower receiving control valve, 22 ... Upper receiving control valve, 23 ... Pressure gauge, 24 ... Liquid level gauge, 25 ... Control apparatus, 100 ... LNG to LNG storage tank Feeding device.

Claims (8)

An LNG upper receiving valve and an LNG lower receiving valve are provided in the pipeline connected to the LNG storage tank that supplies LNG, and LNG adjusted to a pressure higher than the internal pressure of the LNG storage tank is supplied to the LNG storage tank. In the supply method,
The upper and lower connection ports to the LNG storage tank of the pipeline provided with the LNG upper receiving valve and the LNG lower receiving valve, respectively, are vertically opposed so that LNG is supplied from the connection port to the LNG storage tank,
The LNG upper receiving valve and the LNG lower receiving valve are periodically and regularly switched based on the switching signal, and are expressed in a mountain shape on the control basic line consisting of a predetermined planned receiving flow rate with respect to the LNG receiving elapsed time. An actual acceptance state is formed,
The actual receiving flow from the LNG lower receiving valve is supplied to the LNG storage tank from the lower connection port to form an agitation zone that periodically and regularly agitates the LNG in the LNG storage tank in the vertical direction of the LNG,
The actual incoming flow from the LNG upper receiving valve is supplied to the LNG storage tank from the upper connection port to the lower connection port, and the LNG in the uppermost layer region formed on the upper surface side of the stirring region in the LNG vertical direction is periodically cycled. The LNG supply method to the LNG storage tank is characterized by regular stirring.   2. The LNG supply method to an LNG storage tank according to claim 1, wherein the mountain shape is a symmetrical mountain shape.   The method for supplying LNG to an LNG storage tank according to claim 1, wherein the actual receiving flow rate from the LNG lower receiving valve is larger than the actual receiving flow rate from the LNG upper receiving valve. An LNG supply method to an LNG storage tank characterized by   The LNG supply method to the LNG storage tank according to claim 1, wherein the actual receiving flow rate from the LNG lower receiving valve is set to be twice or more as compared with the actual receiving flow rate from the LNG upper receiving valve. LNG supply method to the LNG storage tank. An LNG upper receiving valve and an LNG lower receiving valve are provided in the pipeline connected to the LNG storage tank that supplies LNG, and LNG adjusted to a pressure higher than the internal pressure of the LNG storage tank is supplied to the LNG storage tank. In the supply device,
The upper and lower connection ports to the LNG storage tank of the pipeline equipped with the LNG upper receiving valve and LNG lower receiving valve, respectively, are vertically opposed,
The LNG upper receiving valve and the LNG lower receiving valve are periodically and regularly switched based on the switching signal, and are expressed in a mountain shape on the control basic line consisting of a predetermined planned receiving flow rate with respect to the LNG receiving elapsed time. An actual acceptance state is formed,
An actual receiving flow is supplied to the LNG storage tank from the lower connection port, and an agitation zone is formed in which the LNG in the LNG storage tank is periodically and regularly agitated vertically.
The actual incoming flow is supplied to the LNG storage tank from the upper connection port correspondingly to the lower connection port, and the LNG in the uppermost layer area formed on the upper surface side of the stirring fluctuation area in the vertical direction of LNG is periodically and regularly stirred. LNG supply equipment for LNG storage tanks.   6. The apparatus for supplying LNG to an LNG storage tank according to claim 5, wherein the shape of the mountain is a symmetrical mountain shape.   The apparatus for supplying LNG to the LNG storage tank according to claim 5, wherein the actual receiving flow rate from the LNG lower receiving valve is larger than the actual receiving flow rate from the LNG upper receiving valve. An LNG supply device to an LNG storage tank, characterized by being.   In the LNG supply device to the LNG storage tank according to claim 5, the actual flow receiving means in which the actual received flow rate from the LNG lower receiving valve is set to be more than twice the actual received flow rate from the LNG upper receiving valve. A supply device for an LNG storage tank, characterized by comprising.

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