JPH09210297A - Separating and releasing device for boil-off gas caught in receiving lead tube - Google Patents

Abstract

(57) Abstract: A BOG that is caught when a low-temperature liquefied gas is transferred from a low-temperature liquefied gas receiving pipe to a receiving lead pipe and received in a low-temperature liquefied gas tank is released. A lower end outlet of a low temperature liquefied gas receiving pipe is installed in a gas layer I of a low temperature liquefied gas tank. A receiving lead tube 4 having a funnel portion 5 at its upper end is arranged immediately below the low temperature liquefied gas receiving tube 3 such that the lower end is immersed in the liquid layer. A cap-shaped structure 8 is supported and fixed to the inner upper end of the receiving lead pipe 4, and a BOG discharge pipe 10 equipped with a check valve 11 is connected to the cap-shaped structure 8. The spiral guide plate 12 is fixed inside the receiving lead tube 4 along the inner peripheral surface. Low temperature liquefied gas receiving pipe 3
The low-temperature liquefied gas 2 that has flowed down to the receiving lead tube 4 flows as a swirl flow on the spiral guide plate 12, thereby causing the low-temperature liquefied gas 2 to be subjected to centrifugal force and being caught.
G is separated and collected in the center of the receiving lead tube 4,
It is discharged from the OG discharge tube 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic liquefied gas tank, in which a boil-off gas trapped in a receiving lead tube used for letting out a cryogenic liquefied gas received from the upper portion into the tank through a tank roof to a tank bottom is liquefied. The present invention relates to a separating / releasing device that separates gas and discharges it outside a receiving lead tube.

[0002]

2. Description of the Related Art FIGS. 5 and 6 schematically show a low temperature liquefied gas tank for receiving a low temperature liquid such as liquefied natural gas LNG or liquefied petroleum gas LPG and storing it for a required period. In the gas layer I, the lower end outlet of the low temperature liquefied gas receiving pipe 3 for receiving the low temperature liquefied gas 2 into the low temperature liquefied gas tank 1 is introduced through the tank roof 1a, and the low temperature liquefied gas receiving pipe 3 A receiving lead pipe 4 having a funnel portion 5 at the upper end is positioned directly below the upper end of the pipe so that the upper end faces the lower end outlet of the low temperature liquefied gas receiving pipe 3 and the lower end is immersed in the liquid layer II so as to be vertical. The low-temperature liquefied gas 2 that has been installed and sent into the gas layer I of the low-temperature liquefied gas tank 1 through the low-temperature liquefied gas receiving pipe 3 is made to flow down from the outlet at the lower end toward the funnel portion 5 of the receiving lead pipe 4. The receiving lead tube 4 Liquid phase low-temperature liquefied gas tank 1 and
BOG take-out pipe 6 for taking out the boil-off gas (hereinafter referred to as BOG) generated by vaporizing a part of the low temperature liquefied gas 2 in the liquid layer II is provided on the tank roof 1a. The BOG compressor 7 is connected to the top and a BOG compressor 7 is installed in the middle of the BOG extraction pipe 6.

[0003]

However, in the above-mentioned low temperature liquefied gas tank, as shown in the enlarged view of FIG. 6, the low temperature liquefied gas 2 is supplied from the lower end outlet of the low temperature liquefied gas receiving pipe 3 to the funnel portion of the receiving lead pipe 4. 5, when a large amount of turbulence is generated on the outside of the low temperature liquefied gas 2 flowing down and a large amount of gas is enclosed, this causes the low temperature liquefied gas receiving pipe 3 to receive lead pipe. When the low temperature liquefied gas is transferred to 4, a large amount of surrounding BOG will be entrained. Further, in the case of the receiving lead tube 4 which has been conventionally used in the low temperature liquefied gas tank 1, since the cylindrical tube having the funnel portion 5 at the upper end is simply used, the receiving lead tube 4 is introduced into the receiving lead tube 4. The low-temperature liquefied gas 2 is forcedly descended in the receiving lead tube 4 to cause turbulence in the flow. When the flow is disturbed, the low-temperature liquefied gas 2 flows down to the liquid surface 2a in the receiving lead tube 4. When the liquid surface 2a is disturbed, the liquid surface 2a becomes turbulent and wavy, and the BOG may be caught in the liquid of the receiving lead tube 4 from here. When the entrained BOG enters the liquid layer II, it condenses, so that the amount of BOG in the gas layer I decreases and the gas pressure of the gas layer I in the low temperature liquefied gas tank 1 decreases. When the pressure of the BOG in the low temperature liquefied gas tank 1 decreases, the BO connected to the top of the tank roof 1a
BOG compressor 7 provided at an intermediate position of the G extraction pipe 6
However, when the low temperature liquefied gas tank 1 becomes larger, the BOG pressure decreases and the low temperature liquefied gas tank due to the external pressure is not compressed. There is a problem that there is a risk of buckling of item 1.

Therefore, according to the present invention, the BOG which is transferred from the low temperature liquefied gas receiving pipe to the receiving reed pipe and is caught when the low temperature liquefied gas is received in the low temperature liquefied gas tank can be separated and removed from the low temperature liquefied gas. Another object of the present invention is to provide a device for separating and releasing boil-off gas caught in a receiving lead tube.

[0005]

In order to solve the above-mentioned problems, the present invention provides a low-temperature liquefied gas tank with a low-temperature liquefied-gas receiving pipe, which penetrates through a tank roof of a low-temperature liquefied-gas tank and is guided to a gas layer in the tank. , With the funnel part facing the top inlet and the bottom end submerged in the liquid layer in the tank, the low-temperature liquefied gas flowing down from the low-temperature liquefied gas receiving pipe is passed through the inside to form the liquid layer in the tank. At the inner upper end of the receiving lead tube that is adapted to be received at the bottom of the receiving lead tube, the cap-shaped structure is arranged concentrically with the receiving lead tube with its apex facing upward, and the receiving lead is received in the cap-shaped structure. A BOG discharge pipe opened to the outside of the pipe is connected, and a spiral guide plate is provided inside the receiving lead pipe within a required range from a lower adjacent position of the Jinsha structure to the inside of the receiving lead pipe. Fixed along the circumference, low The low-temperature liquefied gas flowing from the liquefied gas receiving pipe into the receiving reed pipe becomes a swirl flow on the spiral guide plate and separates the boil-off gas that is trapped while flowing and is released to the outside from the BOG releasing pipe. It will be configured as follows.

When the low-temperature liquefied gas flowing from the low-temperature liquefied gas receiving pipe into the receiving reed pipe is swirled and flows down on the spiral guide plate, a centrifugal force is exerted on the low-temperature liquefied gas swirled. As compared with BOG, low-temperature liquefied gas, which is a heavy material, is blown to the outside, so that it is separated from BOG, which is a light material, and the separated BOG rises in the central part of the receiving lead tube, It will be taken out.

In the above, a liquid stopper is formed at the inner end of the spiral guide plate, or the spiral guide plate is inclined so that the inner end is higher than the outer end, and the inner circumference of the receiving lead tube is increased. When fixed along the surface so that the low temperature liquefied gas flows down along the inner peripheral surface of the receiving lead tube, it seems that a large amount of low temperature liquefied gas has flowed down from the low temperature liquefied gas receiving tube to the receiving lead tube. Even in such a case, it is possible to prevent the low temperature liquefied gas from overflowing from the inner end portion of the spiral guide plate, and the BOG entrained is effectively separated.

Further, when the spiral guide plate is made wide so that the plate width exceeds the center of the receiving lead tube, the low temperature liquefied gas is less likely to overflow from the inner end portion of the spiral guide plate and is entrained. The separated BOG is effectively performed.

[0009]

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

FIG. 1 shows an embodiment of a device for separating and releasing boil-off gas wound in a receiving lead tube according to the present invention. The low temperature liquefied gas tank 1 shown in FIGS. 5 and 6 is shown.
The low temperature liquefied gas 2 sent to the inside through the low temperature liquefied gas receiving pipe 3 is made to flow down from the lower end outlet of the low temperature liquefied gas receiving pipe 3 toward the funnel portion 5 of the receiving lead pipe 4 arranged immediately below. And the funnel portion 5 at the inner upper end of the receiving lead tube 4 in the configuration in which the receiving lead tube 4 is received into the bottom of the liquid layer II of the low temperature liquefied gas tank 1.
In the vicinity of the lower boundary line of the above, the capsular structure 8 is arranged concentrically with the receiving lead tube 4 with the apex facing upward, and is fixedly supported by the support frame 9, and inside the capsular structure 8. The receiving lead tube 4 through the receiving lead tube 4.
Is connected to the outside of the BOG release pipe 10 and a check valve 11 is provided at an intermediate position of the BOG release pipe 10 to prevent the BOG of the air layer I from flowing in,
Further, the spiral guide plate 12 is fixed along the inner peripheral surface of the receiving lead tube 4 in a required range downward from the lower adjacent position of the above-mentioned cap-shaped structure 8 inside the receiving lead tube 4. To do.

When the reception of the low temperature liquefied gas 2 into the low temperature liquefied gas tank 1 is started, the low temperature liquefied gas 2 flowing down from the lower end outlet of the low temperature liquefied gas receiving pipe 3 toward the funnel portion 5 of the receiving lead pipe 4. Is lowered while entraining the surrounding BOG, but the low-temperature liquefied gas 2 reaching the top of the capsular structure 8 in the receiving lead tube 4 is
The upper side surface of the receiving lead tube 4 directs the inner lead surface of the receiving lead tube 4 to swirl on the spiral guide plate 12 to flow down. Due to the centrifugal force generated by the swirling flow of the low-temperature liquefied gas 2, the low-temperature liquefied gas 2, which is much heavier than BOG, is blown to the outside on the spiral guide plate 12, so that the low-temperature liquefied gas 2 is discharged. B caught in
Separated from the OG, the BOG is collected in the center of the receiving lead tube 4.

The BOG separated from the low-temperature liquefied gas 2 and collected in the central portion of the receiving lead tube 4 rises in the receiving lead tube 4 and is moved to the B side by the lower surface of the Jinsha structure 8.
OG is stored. The volume of BOG accumulated by the Jinkasa structure 8 is increased to gradually increase the BOG pressure in the receiving lead tube 4, becoming higher than the pressure of the gas layer I, and the reverse of being provided in the middle of the BOG discharge tube 10. When the operating pressure of the stop valve 11 is increased, the BOG is discharged through the BOG discharge pipe 10.
Can be released to the outside of the receiving lead tube 4 and returned to the inside of the gas layer I of the low temperature liquefied gas tank 1. Further, since the BOG is released, the inside of the receiving lead tube 4 becomes a negative pressure than the outside. Even in this case, the check valve 11 does not cause the BOG to flow back into the receiving lead tube 4 from the outside.

Further, in the above, since the low-temperature liquefied gas 2 flows along the spiral guide plate 12, as compared with the conventional case where the low-temperature liquefied gas 2 freely falls in the receiving lead tube 4, Since the falling speed of the low temperature liquefied gas 2 is remarkably slowed and the flow is made gentle, there is almost no turbulence in the liquid surface when the flow collides with the liquid surface in the receiving lead tube 4. It is also possible to prevent the liquid level in the receiving lead tube 4 from wavy and entrain the separated BOG.

Next, FIG. 2 shows another embodiment of the present invention, in which the cap-shaped structure 8 shown in FIGS. 1A and 1B and the spiral guide plate 12 are used in combination. In the configuration in which the low-temperature liquefied gas 2 is used as a swirling flow to separate the BOG, the inner end of the spiral guide plate 12 is bent vertically by a required height. The liquid stopper 13 is formed to cool the low temperature liquefied gas 2
Is designed to flow down along the inner peripheral surface of the receiving lead tube 4.

In the case of the embodiment shown in FIG. 2, the low-temperature liquefied gas tank 1 starts to receive the low-temperature liquefied gas 2 and a large amount of low-temperature gas flows from the low-temperature liquefied gas receiving pipe 3 to the funnel portion 5 of the receiving lead pipe 4. Even when the liquefied gas 2 flows down, the low-temperature liquefied gas 2 can be prevented from overflowing from the inner end portion of the spiral guide plate 12, and the entrained BOG can be effectively separated. Moreover, the separated BOG is not caught in the liquid surface in the receiving lead tube 4.

Next, FIG. 3 shows still another embodiment of the present invention. Instead of the method shown in FIG. 2, the liquid stopper 13 is formed at the inner end of the spiral guide plate 12. ,
The spiral guide plate 12 is inclined along the inner peripheral surface of the receiving lead tube 4 so as to be inclined so that the inner end portion is positioned higher than the outer (receiving lead tube 4 side) end portion. In this case, in addition to the same operational effects as those of the embodiment shown in FIG. 2, there is an advantage that the liquid stopper 13 can be eliminated.

Next, FIG. 4 shows another embodiment of the present invention. In the configuration similar to that shown in FIGS. 1A and 1B, the lateral width of the cross section is the center of the receiving lead tube 4. A wide spiral guide plate 12 'having a size exceeding 10 mm is used.

In the case of the embodiment shown in FIG. 4, the low-temperature liquefied gas 2 is swirled along the wide spiral guide plate 12 '.
Since the BOG separated by the centrifugal force is lifted by sewing the gap between the spiral guide plates 12 ', it can be used in the same manner as that shown in FIG. Therefore, the low temperature liquefied gas 2 does not overflow from the inner end of the spiral guide plate 12 ',
The same effects as in the above embodiments can be obtained.

The present invention is not limited to the above-described embodiment, and for example, the cap-shaped structure 8 may have a cross-sectional shape other than that shown in the drawings and within the scope not departing from the gist of the present invention. It goes without saying that various changes can be made in.

[0020]

As described above, according to the separating / releasing device for boil-off gas wound in the receiving lead pipe of the present invention, the low-temperature liquefied gas flowing down from the low-temperature liquefied gas receiving pipe is passed through the inside of the liquid in the low-temperature liquefied gas tank. Install a cap-shaped structure at the inner upper end of the receiving lead tube that is designed to be received at the bottom of the layer, and fix the spiral guide plate along the inner peripheral surface of the receiving lead tube to flow into the receiving lead tube. Since the low temperature liquefied gas thus generated is made to flow down on the spiral guide plate as a swirling flow, it is transferred from the low temperature liquefied gas receiving pipe to the receiving lead pipe and entrained when the low temperature liquefied gas is received in the low temperature liquefied gas tank. B in the closed air layer
When the OG can be separated and removed from the low-temperature liquefied gas by the centrifugal force applied to the low-temperature liquefied gas in the swirling flow, and the swirling flow causes the low-temperature liquefied gas to flow freely. There is almost no turbulence in the liquid surface when it collides with the liquid surface in the receiving lead tube at a lower speed than that, and the liquid surface in the receiving lead tube swells and entrains the separated BOG. Since the BOG of the gas layer is caught when the low temperature liquefied gas is received and enters the liquid layer and condenses,
It is possible to prevent a decrease in the amount of OG and a decrease in the BOG pressure in the air layer, which can prevent suction failure of the BOG compressor, backflow from the BOG compressor, and the like. It is possible to eliminate the risk of buckling of the low temperature liquefied gas tank due to external pressure.

Further, a liquid stopper is formed at the inner end of the spiral guide plate, or the spiral guide plate is inclined so that the inner end is higher than the outer end, and the inner peripheral surface of the receiving lead tube is inclined. If the low temperature liquefied gas is made to flow down along the inner peripheral surface of the receiving lead tube by fixing it along the inner periphery of the spiral guide plate or by using a wider spiral guide plate, The liquefied gas can be prevented from overflowing, and gas and liquid can be effectively separated, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of a separation and release device for boil-off gas wrapped in a receiving lead tube according to the present invention,
(A) is a sectional side view, and (B) is a view taken in the direction of the arrow AA of (A).

FIG. 2 is a cut end view showing another embodiment of the present invention.

FIG. 3 is a cut end view showing still another embodiment of the present invention.

FIG. 4 is a cut end view showing another embodiment of the present invention.

FIG. 5 is an overall view showing an example of a low temperature liquefied gas tank.

6 is a view showing a relationship between a low temperature liquefied gas receiving pipe and a receiving lead pipe, and is an enlarged view of a B portion in FIG.

[Explanation of symbols]

 1 Low-temperature liquefied gas tank 2 Low-temperature liquefied gas 3 Low-temperature liquefied gas receiving pipe 4 Receiving lead pipe 5 Funnel part 8 Jinkasa structure 10 BOG discharge pipe 12, 12 'Spiral guide plate 13 Liquid stop part

Claims (4)

[Claims] 1. A low-temperature liquefied gas tank is provided with a funnel portion at its lower end facing the lower-end outlet of a low-temperature liquefied-gas receiving pipe penetrating through the tank roof of the low-temperature liquefied gas tank to a gas layer in the tank. It is installed so as to be submerged in the liquid layer inside, and the low temperature liquefied gas flowing down from the low temperature liquefied gas receiving pipe is received through the inside to the bottom of the liquid layer of the tank. , The Jinkasa structure is arranged concentrically with the receiving lead tube with the apex facing upward, the BOG discharge tube opened outside the receiving lead tube is connected to the Jinkasa structure, and the receiving The spiral guide plate is fixed along the inner peripheral surface of the receiving lead tube in the required range from the lower side adjacent position of the above-mentioned Jinkasa structure inside the lead tube, and is received from the low temperature liquefied gas receiving tube. Low temperature liquid flowing into the lead tube The boil-off gas, which is caught in the spiral-shaped guide plate as a swirling flow and flows down, is separated and discharged from the BOG discharge pipe to the outside. Boil-off gas separation and release device. 2. A device for separating and releasing boil-off gas caught in a receiving lead tube according to claim 1, wherein a liquid stopper is formed at an inner end of the spiral guide plate. 3. The receiving lead tube according to claim 1, wherein the spiral guide plate is fixed along the inner peripheral surface of the receiving lead tube by inclining it so that the inner end portion is higher than the outer end portion. Boil-off gas separation and emission device. 4. The separation / release device for boil-off gas caught in a receiving lead tube according to claim 1, wherein the spiral guide plate has a large width such that the plate width exceeds the center of the receiving lead tube.