JPH0243078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for effectively transporting low-temperature liquefied gas stored in a tank while reducing loss, and a liquid transport device for carrying out the method.

For example, when the low-temperature liquefied gas in the tank T is sent to the user via the long-distance low-temperature liquefied gas sending pipe 4 using the liquid sending system illustrated in FIG. The temperature rises due to the intrusion heat of the tank T, so if you open the main valve 3 and the destination valve 6 of the tank T and suddenly transfer the liquid, the low temperature liquefied gas transfer pipe will be damaged due to evaporation during the liquid transfer. The piping resistance of No. 4 increases, and the flow rate decreases accordingly, so the amount of liquid sent decreases. Therefore, in general, the tank T is
The blow valve 5 provided at the main valve 3 and the terminal end of the low temperature liquefied gas delivery pipe 4 is opened to send the low temperature liquefied gas in the tank T through the low temperature liquefied gas outlet pipe 2 and the main valve 3. After pre-cooling the liquid sending pipe 4 by passing liquid through the pipe 4 and releasing it into the atmosphere from the blow valve 5,
Close valve 5 and open valve 6 to send the liquid. In this way, the low-temperature liquefied gas in the tank T is sequentially led out and fed from the bottom of the tank T. On the other hand, the temperature of the low-temperature liquefied gas in the tank T is higher as it approaches the top, and as it approaches the bottom, the temperature of the low-temperature liquefied gas in the tank T is higher. The temperature has become low (supercooled). That is, the temperature of each layer of gas layer A, upper layer liquid B, and lower layer liquid C is A
The temperature decreases in the order of →B →C, and C is the lowest temperature and is in a supercooled state. Therefore, in the pre-cooling, the tank bottom liquid C in a supercooled state is used, and in the liquid transfer after pre-cooling, low-temperature liquefied gas with a higher liquid temperature is transferred, but if the liquid temperature is high, it will evaporate. Therefore, it is disadvantageous for applications where liquid state is used as a forebank because evaporation loss increases. Therefore, it is required to send low-temperature liquefied gas with a low liquid temperature to the place of use. For this reason, conventionally, a supercooling operation was performed before or after precooling. This is done by opening the blow valve 1 attached to the tank T with the main valve 3 and tank pressurizing valve 8 closed, releasing the gas layer A at the top of the tank T to the atmosphere and reducing the pressure. After evaporating a portion of the gas to lower the temperature, close the valve 1, then open the tank pressurization valve 8, introduce the low temperature liquefied gas in the tank T to the vaporizer 7, evaporate it, and raise the tank internal pressure necessary for liquid delivery. The pressure is increased to a certain level.

In this way, conventionally, in order to send low-temperature liquefied gas with a low liquid temperature, the above-mentioned supercooling operation is performed before and after pre-cooling, but this operation results in a loss of a part of the low-temperature liquefied gas, making it unnecessary. This is not only economical, but also requires complicated work and a certain amount of time for the supercooling operation. Furthermore, if a supercooling operation is performed after precooling, the temperature of the precooled low-temperature liquefied gas feeding pipe will rise again during this period, so precooling will be required again.

The present invention was proposed in view of the above-mentioned disadvantages.
The feature is that when the low-temperature liquefied gas stored in the tank is sent to the user via the low-temperature liquefied gas pipe, the low-temperature liquefied gas pipe is pre-cooled by the gas layer or upper liquid layer at the top of the tank. After the liquid is drawn out, the lower liquid at the bottom of the tank is sent, and the liquid is inserted from the outer tank side into a protective tube that airtightly penetrates the tank's inner and outer tanks at approximately the vertical midpoint of the low-temperature liquefied gas tank. A low-temperature liquefied gas outlet pipe, an L-shaped suction pipe that is inserted from the inner tank side and has a power transmission part that receives power from the drive device, and a suction port that opens inside the tank are connected by a swivel joint or the like in the protective pipe. This liquid feeding device is connected via a movable joint, and the suction port can be positioned at an arbitrary height within the tank by operating the drive device.

According to the present invention, as described above, the liquid pipe is pre-cooled by drawing out the gas layer or the upper liquid in the upper part of the tank. The temperature is rising;
The liquid sending pipe is further cooled by flowing the lower layer liquid after the pre-cooling, but even though the temperature is high, it is still considerably lower than before pre-cooling, so it is necessary to flow the lower layer liquid from the beginning. The amount of lower liquid used for cooling the liquid pipe is significantly reduced compared to the conventional method used.

First, the liquid transfer device of the present invention will be explained by illustrating one embodiment in FIG. At approximately the midpoint in the vertical direction of T,
A protective tube 11 is attached to the tank inner tank 9 and the tank outer tank 10 by penetrating the tank inner tank 9 and the tank outer tank 10 in an airtight manner by welding or the like. The thickness of the protective tube 11 is preferably as thin as its mechanical strength allows, in order to make it difficult for atmospheric heat to enter the tank. A part of the protective tube 11 can also be made to have a flexible structure to withstand expansion and contraction that occurs. A low temperature liquefied gas outlet pipe 20 passes through the outer tank side end of the protective tube 11 and is fixed to the insertion portion 18 by welding or the like. This low-temperature liquefied gas outlet pipe 20 is connected to the swivel joint 1 in the protection pipe 11.
It is connected to the suction pipe 14 via a movable joint such as No. 5, and the pipe 14 is configured to be freely rotatable with respect to the outlet pipe 20.

The suction pipe 14 is inserted through the protection pipe 11 from the inner tank side, is rotatably sealed in the insertion part 19 with a gasket, etc., and has a suction port 13 at the tip inside the tank. The opening 13 is bent approximately at a right angle to form an L-shape at an appropriate position that does not contact the inner tank 9 of the tank and can suck in the lower liquid from the gas layer of low-temperature liquefied gas in the tank. Also suction pipe 1
4 is provided with a gear 16 as a power transmission section between the inner tank 9 and the swivel joint 15, and the drive device 1
It rotates by 7. That is, the gear 16 fixed to the suction pipe 14 meshes with the pinion 22.
is fixed to a rod 23 of the drive device 17, the rod 23 passes through the protective tube 11 at a penetration part 24, and a handle 25 is attached to the outside.
5, the rod 23 is supported by the through portion 24 and rotates, thereby rotating the small gear 22 and rotating the gear 16. Therefore, the suction pipe 14 is supported by the swivel joint 15 and the insertion part 19 and rotates, and the suction port 13 can be positioned at an arbitrary height, making it possible to suck in the low-temperature liquefied gas from the gas layer to the lower layer liquid. Become.

In this embodiment, the rotation of the suction pipe 14 is controlled by the handle 2.
5, but the handle 2
It is also possible to have a mechanism in which the suction port 13 is lowered in accordance with the drop in the liquid level by linking the pump 5 with a liquid level gauge attached to the tank. Further, the gear 16 as a power transmission unit can also be formed by a belt, a chain, a link mechanism, or the like. Note that 21 is a reinforcing material for reinforcing the suction pipe 14.

A method for feeding low-temperature liquefied gas using the tank device of the present invention configured as described above will be described with reference to FIG. Components that are the same as those in FIG. 1 or FIG. 2 are designated by the same reference numerals and their explanations will be omitted.

First, with the suction port 13 facing the gas layer A at the top of the tank, open the valves 3 and 5 to pre-cool the low-temperature liquefied gas liquid supply pipe 4, and then gradually lower the suction port 13 to lower the low-temperature liquefied gas upper layer liquid B. After the precooling is completed, the suction port 13 is directed toward the bottom of the tank, the valve 6 is opened, and the valve 5 is closed to start liquid feeding. Note that the above method may be used to derive the upper layer liquid B and start precooling. In this case, the effective use of cold is slightly less than when the gas layer A is derived and precooling is started, but the precooling time is shortened. There are advantages that can be achieved.

In this way, when starting liquid feeding after pre-cooling, the suction port 13
Since the lower layer liquid, which is maintained at the lowest temperature (supercooled) of the low-temperature liquefied gas in the tank, is sent to the bottom of the tank, the degree of supercooling of the low-temperature liquefied gas being sent is sufficient. The liquid is maintained in a liquid state and delivered to the receiving destination.

As described above, according to the method of sending low-temperature liquefied gas according to the present invention, it is possible to omit the supercooling operation required in the conventional method of sending liquid that extracts only from the bottom of the tank. Loss can be eliminated, as well as the complicated work and work time associated with conventional supercooling operations. Furthermore, the pre-cooling interruption of the low-temperature liquefied gas delivery pipe that occurs due to supercooling operations is eliminated, and the low-temperature liquefied gas is maintained in a sufficiently liquid state and sent to the destination through a series of smooth and simple operations. Therefore, it has great economical effects and excellent practical advantages. The effect described above is more pronounced as the low-temperature liquefied gas pipe is longer, but even if the pipe is short, the same effect can be obtained if pre-cooling of the pipe is required. There is.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet diagram for explaining a conventional liquid feeding method, and FIG. 2 is a sectional view of a tank showing a state in which a liquid feeding device according to an embodiment of the present invention is attached.
FIG. 3 is a flow sheet diagram for explaining the liquid feeding method of the present invention. 1, 3, 5, 6, 8 are valves, 2, 20 are low temperature liquefied gas outlet pipes, 4 is low temperature liquefied gas feed pipe, 7 is a tank vaporizer, 9 is a tank inner tank, 10 is a tank outer tank,
11 is a protection tube, 12 and 24 are penetration parts, 13 is a suction port, 14 is a suction pipe, 15 is a swivel joint, 16
1 is a gear, 17 is a gear drive device, 18 is an insertion part, 1
9 is an insertion part, 21 is a reinforcing material, 22 is a small gear, 23
is the rod, 25 is the handle, T is the tank, A is the gas layer, B is the upper liquid, and C is the lower liquid.

Claims (1)

[Claims] 1. When sending the low-temperature liquefied gas stored in a tank to a user via a low-temperature liquefied gas pipe, the low-temperature liquefied gas pipe is pre-cooled by a gas layer at the top of the tank or 1. A method for transferring low-temperature liquefied gas stored in a tank, which comprises drawing out the upper layer liquid and then transferring the lower layer liquid at the bottom of the tank. 2. A protective tube that airtightly penetrates the tank's inner and outer tanks at approximately the vertical midpoint of the low-temperature liquefied gas tank.
L having a low temperature liquefied gas outlet pipe inserted from the outer tank side, a power transmission part inserted from the inner tank side and receiving power from the drive device, and a suction port opened inside the tank.
The suction port can be positioned at any height within the tank by connecting the letter-shaped suction pipe through a movable joint such as a swivel joint within the protection pipe and operating the drive device. Features: A liquid delivery device for low-temperature liquefied gas stored in a tank.