JPH08200596A - Liquid receiving equipment for low temperature tanks - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] When receiving multiple LNG with different specific gravities in the same tank, stratification can be effectively suppressed and piping cost can be reduced. Provide equipment. [Structure] A liquid level gauge 10 in a low-temperature tank A, a temperature sensor 11 for a liquid stored in the low-temperature tank A, a low-temperature liquefied gas receiving pipe 12, and a low-temperature tank branched from the receiving pipe 12 into upper and lower stages. A plurality of branch pipes 15 each connected to A,
Liquid receiving control valve 16 for controlling opening / closing of the branch pipe 15
And a sampling device 13 for detecting the liquid composition of the low-temperature liquid to be received, and a control device 14 for controlling the opening and closing of the liquid reception control valve according to the liquid level gauge 10, the temperature sensor 11, and the liquid information from the sampling device 13. I have it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low temperature tank for storing a low temperature liquefied gas such as LNG, and more particularly to a liquid receiving facility for a low temperature tank for receiving a low temperature liquid having a different liquid composition.

[0002]

2. Description of the Related Art FIG. 2 shows an LN carried by an LNG carrier or the like.
It is an example of a conventional low temperature tank that temporarily stores a low temperature liquid such as G. As shown in the figure, this low temperature tank is such that an inner tank 3 is erected on a foundation 1 made of concrete pile or the like via a bottom cold insulation layer 2, and an outer tank 4 is formed around the inner tank 3. Further, between the inner tank 3 and the outer tank 4, there is formed a cold insulation layer 5 made of, for example, a parularite grain cold insulation material, which stores a low temperature liquid in the inner tank 2 and is formed around it. The bottom cold insulation layer 2 and the cold insulation layer 5 prevent external heat input. Now, suppose that two types of LNG with different compositions and densities are layered in such a low temperature tank without mixing, and a light liquid is added on top.
When the liquid becomes heavy in the lower part, BOG is generated from the light liquid in the upper layer due to heat input from the outside, and the density of the upper layer increases. When the difference in density with the liquid in the lower layer disappears,
The two layers are mixed in a short time, the thermal energy stored in the lower layer is released, and a so-called rollover phenomenon occurs with a large amount of BOG generation. For this reason, these low-temperature tanks are provided with a device 6 for eliminating the stratification of the lower layer LNG and the upper layer LNG. By this device 6, the lower layer LNG is extracted and returned to the upper layer to prevent the rollover phenomenon. It is designed to prevent the layering that would occur. There is also a tank equipped with a device for mixing and stirring with a mixing nozzle.

[0003] In addition, such a conventional low temperature tank is designed to receive LNG having the same composition, that is, LNG obtained from the same place of origin in one tank in principle. When LNG of (1) is received in the same tank after a certain period of time, the density of LNG differs depending on the place of origin, so that a difference in specific gravity occurs and layering is likely to occur. Therefore, as shown in the figure, in this low temperature tank, a bottom feed 7 for receiving LNG from the bottom of the tank and a top feed 8 for receiving it from the top of the tank are provided and the LNG to be received is provided.
If the specific gravity of LNG is lower than the specific gravity of LNG already accepted, on the contrary, if it is higher than the specific gravity of LNG already accepted, it is accepted from the side of top feed 8 respectively.
It is devised to promote the agitation and prevent layering.

[0004]

As described above, in the conventional low temperature tank, in order to prevent stratification, the bottom feed 7 and the top feed 8 are provided, and the mixing device 6 for stirring LNG is provided. However, there is a drawback in that the LNG is mixed by the mixing device 6, and it is easily affected by the external heat input, and the heat insulation measures for that are also costly. It was

Therefore, the present invention has been devised to solve the above problems, and an object thereof is to effectively suppress stratification when a plurality of LNG having different specific gravities are received in the same tank. Of course, it is to provide a new liquid receiving facility for a low temperature tank that can reduce piping costs.

[0006]

To achieve the above object, the present invention provides a low temperature tank for storing two or more types of low temperature liquids having different specific gravities in a low temperature tank for storing a low temperature liquefied gas such as LNG. In the liquid receiving facility, a liquid level gauge for detecting the liquid level in the low temperature tank, a plurality of temperature sensors for detecting the temperature of the stored liquid in the low temperature tank along its height direction, and A low temperature liquefied gas receiving pipe erected along the height direction of the low temperature tank, and a plurality of branch pipes respectively branched from the low temperature liquefied gas receiving pipe into upper and lower stages and connected to the low temperature tank, respectively. A liquid receiving control valve provided on the branch pipe for controlling the opening and closing of the branch pipe, a sampling device for detecting the liquid composition of the low temperature liquid to be received, and a liquid level gauge, a temperature sensor, and information from the sampling device. It is obtained and a control device for controlling the opening and closing of the serial fluid admission control valve.

[0007]

Since the present invention is configured as described above, the liquid temperature of the low temperature liquid already stored in the tank, the liquid level and the composition of the low temperature liquid to be received later are input to the control device. By calculating the specific gravity and the liquid level in the tank and operating the opening and closing of the liquid reception control valve that receives it in the tank, it becomes possible to receive the low temperature liquid from the optimum position and prevent stratification. You can That is,
If the density of the low-temperature liquid to be added later and the composition such as the liquid temperature are measured with a sampling device and the specific gravity is heavier than the specific gravity of the low-temperature liquid already stored in the tank, the temperature above the low-temperature liquid surface in the tank On the contrary, when the low temperature liquid is poured from a certain branch pipe and the specific gravity of the low temperature liquid to be added later is light, the low temperature liquid is mixed and stirred by flowing the low temperature liquid from the branch pipe connected to the bottom of the tank. However, it will be accepted, and stratification will be suppressed.

[0008]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a liquid receiving facility for a cryogenic tank according to the present invention. As shown in the figure, the liquid receiving equipment of the low temperature tank includes a liquid level gauge 10 for detecting the liquid level in the low temperature tank A, and a temperature sensor 11 for detecting the temperature of the stored liquid in the low temperature tank A. A low-temperature liquefied gas receiving pipe 12 for receiving a low-temperature liquid from an LNG ship or the like into the low-temperature tank A, a sampling device 13 for checking the composition of the low-temperature liquid to be received, and a liquid level gauge 10, a temperature sensor 11, a sampling device 13 It is mainly composed of a control device 14 for controlling the reception of the low temperature liquid by calculating the information input from.

The low-temperature liquefied gas receiving pipe 12 is erected vertically upward from the bottom of the low-temperature tank A, and a plurality of branch pipes 15a and 15b are arranged in a vertical multistage (three stages in this embodiment) along the height direction. , 15c are branched from this and are respectively connected to the tank A side in a multi-step manner so that the low temperature liquid flowing through the low temperature liquefied gas receiving pipe 12 is shunted to flow into the tank A side from an arbitrary height. Has become. Further, each of the branch pipes 15a, 15b, 15c is provided with a liquid reception control valve 16a, 16b, 16c such as an electromagnetic valve for regulating the flow of the low temperature liquid flowing therethrough.
The opening / closing control of the liquid reception control valves 16a, 16b, 16c is individually operated by the control device 14 individually.

Further, the temperature sensor 11 is composed of a plurality of thermometers 11a, which are arranged in a plurality of stages in the vertical direction along the height direction of the tank A,
11b, 11c, 11d, 11e (five in this embodiment)
The temperature of the liquid stored in the tank A is measured along the height direction and the measured value is input to the control device 14 side.

Further, as described above, the sampling device 13 not only receives the LNG components before being received, but also the temperature,
The density can be measured, and the information is input to the control device to calculate the specific gravity. Since the structure of the tank A itself is the same as the conventional one as described above, its detailed description is omitted.

Next, the operation of this embodiment will be described.

First, as shown in FIG. 1, the first low temperature liquid (α-LNG) is supplied from the low temperature liquefied gas receiving pipe 12 into the tank A in an empty state by using all the branch pipes 15a, 15b and 15c. The temperature and liquid level of the first low temperature liquid (α-LNG) are measured at the time when the reception is completed, and the values of the low temperature liquid (α-LNG) measured in advance by the sampling device 13 are measured. It is input to the controller 14 together with the composition (density, temperature, etc.) information.

Next, in the tank A in which the low temperature liquid (α-LNG) is received, the low temperature liquid (β-LN) having a different composition is
In the case of accepting G), first, the sampling device 1
The composition is measured at 3, and the information is input to the controller 14. In the control device 14, when the specific gravity of β-LNG measured by the sampling device 13 is heavier than the specific gravity of α-LNG already received in the tank A, the liquid level of α-LNG is high. Open only the liquid reception control valve of the diversion pipe connected to a higher position (for example, when the liquid level of α-LNG is in the middle of the branch pipes 15a and 15b, the liquid reception control valve 16b of the diversion pipe 15b). Therefore, α-L
This β-LNG is accepted from above the NG. Then, the β-LNG having a large specific gravity is received in the tank A while being stirred well as it sinks into the α-LNG, so that the α-LNG and the β-LNG are uniformly mixed, and the α-LNG in the tank A is mixed. The layering of β-LNG with β-LNG is prevented in advance. On the contrary, when the specific gravity of β-LNG is lighter than that of α-LNG, it is already accepted by opening and accepting only the liquid acceptance control valve 16a of the flow dividing pipe 15a connected to the lowest position. Β-LN by ascending and moving in the existing α-LNG
G will be accepted with good agitation.

Thereafter, in γ-LNG in which α-LNG and β-LNG are mixed, δ-LNG having a different composition, α-LNG accepted first, and β accepted second.
In order to accept either LNG having the same composition as -LNG, similarly to the above, the controller 14 calculates the specific gravity and liquid level of γ-LNG, and the specific gravity of δ-LNG or the like to be accepted, and accepts it later. The specific gravity of δ-LNG is
If it is lighter than γ-LNG already accepted in the tank, only the liquid acceptance control valve of the diversion pipe connected to the lowest position is opened to merge from the bottom of the tank. Conversely, if its specific gravity is heavy, By opening only the liquid reception control valve of the flow dividing pipe connected to a position higher than the liquid level and joining them from the upper part of the liquid storage, both are well stirred and received.

As described above, according to the present invention, when the low-temperature liquids having different specific gravities are received in one tank, the specific gravities of the already received stored liquid and the low-temperature liquid to be received are calculated, and the specific gravities thereof are calculated. Since the receiving height of the low-temperature liquid that is later received in the tank is arbitrarily controlled by the difference between the two, both low-temperature liquids are received while being stirred well during reception, and rollover in the tank is prevented. This will prevent the stratification of the stored liquid.

[0018]

In summary, according to the present invention, since low temperature liquids having different compositions can be mixed and accepted well, stratification of the stored liquid which causes rollover can be prevented. Further, as a result, the number of pipes constituting the conventional top feeder, bottom feeder, mixing device, etc. can be significantly reduced, and excellent effects such as tank manufacturing and operating cost reduction can be achieved. .

[Brief description of drawings]

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

FIG. 2 is a schematic diagram showing a configuration of a conventional cryogenic tank.

[Explanation of symbols]

 10 Liquid Level Meter 11 Temperature Sensor 12 Low Temperature Liquefied Gas Receiving Pipe 13 Sampling Device 14 Controller 15 Branch Pipe 16 Liquid Receiving Control Valve A Low Temperature Tank

Claims (1)

[Claims] 1. A liquid receiving facility for a low temperature tank for receiving two or more types of low temperature liquids having different specific gravities in a low temperature tank for storing a low temperature liquefied gas such as LNG. The liquid level in the low temperature tank is detected. Liquid level gauge, a temperature sensor for detecting the temperature of the stored liquid in this low temperature tank along its height direction, and a low temperature liquefied gas receiving stand installed along the height direction of this low temperature tank. Pipes, a plurality of branch pipes branched from the low-temperature liquefied gas receiving pipe into upper and lower stages and connected to the low-temperature tank, and a liquid receiving device provided in each of the branch pipes for controlling opening and closing of the branch pipes. A control valve, a sampling device that detects the liquid composition of the low-temperature liquid that is received, and a control device that controls the opening and closing of the liquid reception control valve according to liquid level gauges, temperature sensors, and liquid information from the sampling device. thing Liquid receiving equipment for low temperature tanks.