JP2000130693A - Cryogenic storage facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a liquid drain drum pump from involving gas. SOLUTION: A pressurized gas supply pipe 31 incorporating a shut-off valve 32 is connected between a liquid drain drum 22 and a miscellaneous boil-off gas(BOG) pipe 21, a shut-off valve 33 is incorporated in a gas vent pipe 30 connected between the liquid drain drum 22 and the BOG pipe 16, and the liquid drain drum 22 is attached thereto with a pressure detector 34 and a liquid lever detector 26, and a control device 40 receives a pressure detecting signal 35 and a liquid level detecting signal 27 from the pressure detector 34 and the liquid level detector 26 so as to deliver control signals 36 to 39 to the shut-off valves 32, 33 and a shut-off valve 24 connected to a liquid drain pipe 23, for pressurizing the inside of the liquid drain drum 22 during a start of a liquid drain drum pump 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature storage facility, and more particularly to a low-temperature storage facility capable of preventing a liquid draining drum pump from being caught by gas.

[0002]

2. Description of the Related Art Cryogenic storage facilities are used to store cryogenic liquids such as liquefied natural gas (LNG).

[0003] As shown in FIG.
It is mainly constituted by a low-temperature storage tank 2 such as an LNG tank which stores the low-temperature liquid 1.
Is a receiving pipe 6 for sending the low temperature liquid 1 from the ship 3 to the low temperature storage tank 2 using the pump 4 mounted on the ship 3.
The receiving pipe 6 is branched into an upper receiving pipe 7 connected to the upper part of the low-temperature storage tank 2 and a lower receiving pipe 8 connected to the lower part of the low-temperature storage tank 2.

In the drawings, reference numeral 9 denotes a valve provided in the middle of the upper receiving pipe 7, and reference numeral 11 denotes a valve provided in the middle of the lower receiving pipe 8.

A low-temperature liquid 1 is provided at the bottom of the low-temperature storage tank 2.
A discharge pipe 18 provided with a discharge pump 12 for discharging the liquid is attached, and a vaporizer 19 for gasifying the low-temperature liquid 1 is provided at a tip of the discharge pipe 18. Is connected to a gas feed pipe 20 for sending generated gas to a demand destination.

In order to keep the receiving pipe 6 in a cooled state at all times, a supply pipe 14 branched from the outlet side of the dispensing pump 12 in the dispensing pipe 18 is connected to the receiving pipe 6 via a level adjusting valve 13. I have.

The evaporative gas 15 is placed above the low temperature storage tank 2.
A BOG pipe 16 (BOG = boil-off gas) for extracting the gas to the outside is attached. The BOG pipe 16 is provided with a compressor 17 for increasing the pressure of the evaporative gas 15 on the way.

[0008] The outlet of the compressor 17 in the BOG pipe 16 is connected to a gas feed pipe 20, and pressurized gas is discharged from the outlet of the compressor 17 in the BOG pipe 16. A miscellaneous BOG tube 21 for use in miscellaneous demands of low-temperature storage equipment is branched.

On the other hand, the receiving pipe 6 is connected to a drain pipe 23 for sending the low-temperature liquid 1 accumulated in the vertical portion 10 of the upper receiving pipe 7 to the drain drum 22. An opening / closing valve 24 is provided on the inlet side of the drawing drum 22, and a limiting orifice 25 is provided in parallel with the opening / closing valve 24.

In the lower part of the draining drum 22, a draining drum pump 28 is driven by a liquid level detection signal 27 from a liquid level detector 26, and the low temperature liquid 1 accumulated in the draining drum 22 is cooled to a low temperature. Return pipe 2 to return to the top of storage tank 2
9 are provided.

Furthermore, on the upper part of the liquid draining drum 22,
A gas vent tube 30 is provided for sending the evaporative gas in the liquid drain drum 22 to the BOG tube 16.

According to this configuration, the low-temperature liquid 1 such as LNG gas stored in the low-temperature storage tank 2 such as an LNG tank.
Is taken out through the discharge pipe 18 and gasified by the vaporizer 19 provided at the tip of the discharge pipe 18,
It is sent to the demand destination via 0.

In the low-temperature storage tank 2, the stored low-temperature liquid 1 evaporates due to heat input from the outside. Then, the evaporated gas 1 generated by the evaporation
5 is sent from the upper part of the low-temperature storage tank 2 to the compressor 17 via the BOG pipe 16, is pressurized to a required pressure by the compressor 17, and is joined to the gas sending pipe 20.

A miscellaneous BOG tube 21 is branched from a portion of the BOG tube 16 on the outlet side of the compressor 17.
The gas pressurized by the compressor 17 can be used for miscellaneous demand of low-temperature storage equipment.

On the other hand, the receiving pipe 6 cannot pass the low-temperature liquid 1 immediately from the normal temperature state, so that a required amount of the low-temperature liquid 1 is always stored inside the receiving pipe 6 to receive the low-temperature liquid 1. It is necessary to keep the tube 6 cool.

For this purpose, the level of the low-temperature liquid 1 in the receiving pipe 6 is detected by a level detector or the like (not shown), and when the liquid level becomes low, the level adjusting valve 13 is opened and the supply pipe 14 is opened.
, The low-temperature liquid 1 is supplied from the dispensing pipe 18 to the receiving pipe 6. When the low-temperature liquid 1 is supplied to the receiving pipe 6 to a predetermined level, the level adjusting valve 13 is automatically closed.

When the ship 3 loaded with the low-temperature liquid 1 arrives, the pump 4 mounted on the ship 3 is driven, and the low-temperature liquid 1 loaded on the ship 3 is received via the receiving pipe 6.
Is transferred to the low-temperature storage tank 2.

At this time, the density of the cryogenic liquid 1 from the ship 3
The density of the low-temperature liquid 1 stored in the low-temperature storage tank 2 is checked, and when the density of the low-temperature liquid 1 from the ship 3 is higher, the valve 11 of the lower receiving pipe 8 is closed, and the valve of the upper receiving pipe 7 is closed. By opening 9, the low-temperature liquid 1 is introduced from above the low-temperature storage tank 2 through the upper receiving pipe 7. Conversely, if the density of the cryogenic liquid 1 from the ship 3 is smaller, the valves 11 and 9
By opening both, the low-temperature liquid 1 is introduced from the lower side of the low-temperature storage tank 2 through the lower receiving pipe 8. Thereby, it is possible to prevent the low-temperature liquid 1 in the low-temperature storage tank 2 from separating into two phases due to the density difference.

Here, when the low-temperature liquid 1 is introduced from the lower side of the low-temperature storage tank 2, the valve 9 is opened such that the gas contained in the low-temperature liquid 1 is allowed to escape to the upper receiving pipe 7 side. In order to When the valve 9 is opened as described above, the low-temperature liquid 1 enters the vertical portion 10 of the upper receiving pipe 7 to a liquid level equal to the liquid level of the low-temperature storage tank 2.

When the low-temperature liquid 1 is put into the low-temperature storage tank 2, the valve 9 is opened and the valve 11 is closed.

In this state, the low-temperature liquid 1 remains in the vertical portion 10 of the upper receiving pipe 7, but the low-temperature liquid 1 left in the vertical portion 10 having a small diameter dimension is input by external heat input. An unstable state (a state of intermittent boiling) is likely to occur.

Therefore, conventionally, after the low-temperature liquid 1 is put into the low-temperature storage tank 2, the low-temperature liquid 1 remaining in the vertical portion 10 is removed by opening the valve 9 and the on-off valve 24 by using gravity.
The liquid is sent to the liquid discharging drum 22 via the receiving pipe 6 and the liquid discharging pipe 23 so that the liquid in the vertical portion 10 is drained.

In the liquid draining drum 22, the liquid level is detected by the liquid level detector 26.
2 is higher than the upper limit set value, the liquid drain drum pump 28 is driven by the liquid level detection signal 27 from the liquid level detector 26, and the low temperature liquid of the liquid drain drum 22 is returned via the return pipe 29. 1 will be returned to the upper part of the low-temperature storage tank 2. Conversely, when the liquid level of the liquid drain drum 22 becomes lower than the lower limit set value, the liquid drain drum pump 28 is stopped by the liquid level detection signal 27 from the liquid level detector 26. As described above, the liquid level of the liquid draining drum 22 is kept within a certain range.

The drain pipe 23 and the drain drum pump 2
8 and the like cannot immediately pass the low-temperature liquid 1 from the normal temperature state.
By providing a restricting orifice 25 in parallel with 4, a small amount of low-temperature liquid 1 is constantly sent to the draining drum 22 and the draining drum pump 28 through the restricting orifice 25, and these are kept at a low temperature.

[0025]

However, the above-mentioned conventional low-temperature storage equipment has the following problems.

That is, as described above, the draining drum 22 is used mainly for draining the liquid from inside the vertical portion 10 of the upper receiving pipe 7.
Is operated intermittently, but the portion of the return pipe 29 between the liquid draining drum 22 and the liquid draining drum pump 28 has a narrow and complicated shape due to the installation space and the like. Therefore, the low-temperature liquid 1 staying inside the return pipe 29 tends to have a high enthalpy due to heat input from outside during standby.

Then, when the draining drum pump 28 is driven for draining, the draining drum 22 of the return pipe 29 is
The low-temperature liquid 1 having a high enthalpy staying in the portion between the draining pump 28 and the draining pump 28
The liquid may be vaporized by the negative pressure associated with the suction of the liquid, and the liquid discharging drum pump 28 may be caught by the gas, and may not be able to suck the low-temperature liquid 1 from the liquid discharging drum 22.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a low-temperature storage facility capable of preventing gas from clogging a liquid drain pump.

[0029]

The present invention is characterized in that a pressurized gas supply pipe for connecting the inside of the liquid removing drum to a pressurized state when the liquid removing drum pump is started is connected to the liquid removing drum. It concerns storage facilities.

Also, the present invention relates to a liquid discharging drum and a BOG
A pressurized gas supply pipe with a first on-off valve is connected between the pipe and the pipe, and a second on-off valve is provided in the middle of a degassing pipe connected between the liquid discharging drum and the BOG pipe, Attach a pressure detector to the draining drum, input the liquid level detection signal from the liquid level detector attached to the draining drum and the pressure detection signal from the pressure detector, and open and close the first and second A control device is provided to send control signals to a valve and a third on-off valve provided in the middle of the liquid drain pipe and to the liquid drain drum pump, respectively, and to pressurize the inside of the liquid drain drum when the liquid drain drum pump is started. A low-temperature storage facility characterized by the above.

According to the above means, the following effects can be obtained.

When the liquid level in the liquid drain drum rises, a liquid level detection signal is generated from a liquid drain drum pump attached to the liquid drain drum.

Then, the control device sends control signals to a second on-off valve provided in the middle of the gas vent pipe and a third on-off valve provided in the middle of the liquid vent pipe. The third on-off valve is closed, and the drainage drum is closed.

Next, the control device sends a control signal to a first on-off valve provided in the middle of the pressurized gas supply pipe to open this first on-off valve.

Then, the high-pressure gas of the BOG pipe flows into the drainage drum, and the inside of the drainage drum is pressurized.

When it is detected by the pressure detection signal from the pressure detector that the inside of the liquid draining drum has been pressurized to a predetermined pressure or higher, the control device sends a control signal to the liquid draining drum pump and drains the liquid. At the same time as starting the drum pump, a control signal is sent to the first on-off valve to close the first on-off valve.

Then, as described above, since the inside of the liquid draining drum is in a pressurized state, the low-temperature liquid having a high enthalpy staying in the portion between the liquid discharging drum and the liquid discharging drum pump is discharged. The liquid is pushed by the low-temperature liquid having a low enthalpy in the draining drum, so that it is possible to prevent the liquid discharging drum pump from sucking the low-temperature liquid at startup.

At this time, since the inside of the liquid draining drum is in a pressurized state, the pressure of the high-enthalpy low-temperature liquid retained in the portion between the liquid draining drum and the liquid discharging drum pump also rises, resulting in a supercooled state. In addition, the low-temperature liquid is less likely to be vaporized even by the negative pressure caused by the suction of the liquid discharging drum pump, so that the effect of suppressing the generation of gas and preventing the liquid discharging drum pump from being caught by the gas can also be obtained. .

In this way, if the low-temperature liquid having a high enthalpy staying in the portion between the liquid draining drum and the liquid draining drum pump passes through the liquid draining drum pump, there is no longer a risk of gas being caught. After a lapse of a predetermined time during which the liquid from the liquid discharging drum to the liquid discharging drum pump is exchanged, a second opening / closing valve provided in the middle of the gas discharging pipe and a third opening / closing provided in the middle of the liquid discharging pipe A control signal is sent to the valve to open the second and third on-off valves and return to the original state. The liquid drain drum pump is stopped by a control signal from a control device that detects that the low-temperature liquid has dropped to a predetermined level at which the pump should be stopped based on the liquid level detection signal from the liquid level detector.

As described above, according to the present invention, it is possible to start the liquid discharging drum pump without causing gas to be caught.

[0041]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an example of an embodiment of the present invention, and the basic configuration of the low-temperature storage equipment is the same as that of FIG. 2, so that FIG. The same parts as those described above are denoted by the same reference numerals and description thereof will be omitted.

In the present invention, a pressurized gas supply pipe 31 is connected between the upper part of the liquid draining drum 22 and the BOG pipe 21,
An on-off valve 32 (first on-off valve) is provided in the middle of the pressurized gas supply pipe 31.

The upper part of the draining drum 22 and the BOG tube 16
On-off valve 33 in the middle of the vent pipe 30 connected between
(Second on-off valve) is provided.

Further, a pressure detector 34 is mounted above the liquid draining drum 22.

Then, if necessary, the liquid level detection signal 27 from the liquid level detector 26 and the pressure detection signal 35 from the pressure detector 34 are inputted, and the open / close valve 32, the open / close valve 33 and the open / close valve 24 ( A control device 40 for sending control signals 36 to 39 to the third opening / closing valve) and the liquid discharging drum pump 28 is provided.

Here, a specific control sequence by the controller 40 is as described below. First, in the initial state when the liquid discharging drum pump 28 is stopped, the on-off valve 32 is closed and the on-off valve 33 is turned on. The open / close valve 24 is open when the liquid is drained and closed when the liquid is not drained.

When the control device 40 detects that the low-temperature liquid 1 has reached a predetermined level at which the pump is to be started by the liquid level detection signal 27 from the liquid level detector 26, the control device 40 outputs The control signal 37 closes the on-off valve 33, the control signal 38 closes the on-off valve 24, and the control signal 36 opens the on-off valve 32.

As a result, when the pressure in the liquid draining drum 22 rises and the control device 40 detects that the pressure has reached a predetermined pressure by the pressure detection signal 35 of the pressure detector 34, the control from the control device 40 The liquid drain drum pump 28 is started by the signal 39, and the on-off valve 32 is closed by the control signal 36.

Next, a predetermined time during which the liquid from the liquid draining drum 22 to the liquid draining drum pump 28 is exchanged is measured by a timer, and after a lapse of the predetermined time, the open / close valve 33 is opened by the control signal 37 from the control device 40, The control signal 38 opens the on-off valve 24 only at the time of removal.

When the controller 40 detects that the low-temperature liquid 1 has dropped to a predetermined level at which the pump should be stopped, based on the liquid level detection signal 27 from the liquid level detector 26,
The liquid drain drum pump 28 is stopped by the control signal 39 from the control device 40, and thereby, the liquid is returned to the initial state described above.

Next, the operation of this embodiment will be described below.

The basic operation of the low-temperature storage facility is the same as that in FIG.

When the liquid level in the liquid draining drum 22 rises, for example, when liquid is drained from the vertical portion 10 of the upper receiving pipe 7, a liquid level detection signal 27 is output from a liquid level detector 26 attached to the liquid draining drum 22. Is generated.

Then, the control device 40 firstly opens and closes the on-off valve 33 provided in the middle of the gas vent pipe 30 and the liquid vent pipe 23.
The control signals 37 and 38 are sent to the on-off valve 24 provided in the middle of the process, the on-off valve 33 and the on-off valve 24 are closed, and the liquid draining drum 22 is closed.

Next, the control device 40 controls the pressurized gas supply pipe 3
The control signal 36 is sent to the on-off valve 32 provided in the middle of the step 1 to open the on-off valve 32.

Then, the high-pressure gas in the BOG pipe 21 flows into the liquid draining drum 22, and the inside of the liquid discharging drum 22 is pressurized.

When it is detected by the pressure detection signal 35 from the pressure detector 34 that the inside of the liquid draining drum 22 is pressurized to a predetermined pressure or more, the control device 40
A control signal 39 is sent to the liquid drain drum pump 28 to start the liquid drain drum pump 28, and a control signal 36 is sent to the open / close valve 32 to close the open / close valve 32.

Then, as described above, the draining drum 2
2 is in a pressurized state, the low-temperature liquid 1 having a high enthalpy remaining in a portion between the liquid draining drum 22 and the liquid draining drum pump 28 becomes a low temperature liquid having a low enthalpy in the liquid draining drum 22. The liquid 1 is pushed by the liquid 1, so that it is possible to prevent the liquid discharging drum pump 28 from being unable to suck the low-temperature liquid 1 at startup.

At this time, since the inside of the liquid draining drum 22 is in a pressurized state, the pressure of the high enthalpy low-temperature liquid 1 staying in the portion between the liquid draining drum 22 and the liquid draining drum pump 28 also rises, and the liquid is supercooled. State, the low-temperature liquid 1 is also supplied by the negative pressure caused by the suction of the liquid discharging drum pump 28.
Is less likely to evaporate, thereby suppressing the generation of gas and preventing the liquid draining drum pump 28 from being caught by gas.

In this way, if the low-temperature liquid 1 having a high enthalpy staying in the portion between the liquid draining drum 22 and the liquid draining drum pump 28 passes through the liquid draining drum pump 28, there is no longer a risk of gas being caught. When a timer (not shown) provided inside the control device 40 has counted a predetermined time, the control device 40
The control signals 37 and 38 are sent to the on-off valve 33 provided in the middle of the valve 0 and the on-off valve 24 provided in the middle of the liquid drain pipe 23, and the on-off valve 33 and the on-off valve 24 are opened. To the initial state. The liquid discharging drum pump 28 is stopped by a control signal 39 from a control device 40 which detects that the low-temperature liquid 1 has dropped to a predetermined level at which the pump should be stopped by the liquid level detection signal 27 from the liquid level detector 26. I do.

As described above, according to the present invention, it is possible to start the liquid discharging drum pump 28 without causing gas to be caught.

It should be noted that the present invention is not limited to the above-described embodiment, but can be carried out by manual operation instead of providing a control device. In addition, various modifications can be made without departing from the gist of the present invention. Can of course be added.

[0064]

As described above, according to the low-temperature storage facility of the present invention, an excellent effect of preventing the liquid draining drum pump from being caught by gas can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial enlarged system diagram of an example of an embodiment of the present invention.

FIG. 2 is a schematic overall system diagram of a conventional example.

[Explanation of symbols]

 Reference Signs List 16 BOG pipe 21 Miscellaneous BOG pipe 22 Liquid drain drum 23 Liquid drain pipe 24, 32, 33 Open / close valve 26 Liquid level detector 27 Liquid level detection signal 28 Liquid drain drum pump 30 Gas vent pipe 31 Pressurized gas supply pipe 34 Pressure detection Instrument 35 Pressure detection signal 36-39 Control signal 40 Controller

Claims (2)

[Claims] 1. A low-temperature storage facility, characterized in that a pressurized gas supply pipe for pressurizing the inside of the draining drum when the draining drum pump is started is connected to the draining drum. 2. Between a draining drum and a chore BOG tube,
A pressurized gas supply pipe equipped with a first on-off valve is connected, a second on-off valve is provided in the middle of a degassing pipe connected between the liquid discharging drum and the BOG pipe, and pressure detection is performed on the liquid discharging drum. A liquid level detection signal from the liquid level detector attached to the liquid drain drum and a pressure detection signal from the pressure detector are input, and the first and second on-off valves and the liquid drain pipe are mounted. A control device that sends control signals to a third opening / closing valve and a liquid discharging drum pump provided on the way, and pressurizes the inside of the liquid discharging drum when the liquid discharging drum pump is started. Storage equipment.