JPH0627920Y2 - LNG tank stratification monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an LNG tank, and is a stratified layer for monitoring a stratification phenomenon occurring when LNG having a different density is newly received while the LNG remains in the tank. The present invention relates to a computerized monitoring device.

[Prior Art] Normally, in an LNG tank, when LNG having a different density is newly accepted while LNG remains, as shown in FIG. 3, the LNG in the tank may be layered. The LNG layer has a uniform density due to convection (2) in the layer. This layered LNG becomes layer-to-layer mixed over time, and when the top layer LNG mixes with the layer below it, the Boil o
A phenomenon called rollover occurs in which ff Gas (BOG) rapidly increases. Since this rollover is a problem in safety and operation of the tank, LNG in the tank
It is necessary to determine whether or not is stratified and take appropriate measures. The LNG temperature of each layered layer is higher in the lower layer, the temperature of the uppermost layer is the lowest and the temperature of the lowermost layer is the highest. Therefore, the temperature difference in the vertical direction is detected by utilizing the difference in the temperature of each layer, and the LNG in the tank is detected.
Can be determined.

FIG. 4 is an explanatory view showing a conventional LNG temperature measuring device in a tank. In the figure, (3) is a plurality of temperature sensors fixedly mounted in the vertical direction at fixed intervals, and (4) is L
It is the temperature sensor closest to the liquid surface among the plurality of temperature sensors in the NG.

The conventional stratification monitoring device is configured as described above, and detects the temperature distribution in the vertical direction of the LNG in the tank from the detection values of the plurality of temperature sensors (3), and stratifies the LNG in the tank from the temperature difference. Is determined.

[Problems to be Solved by the Invention] In the conventional stratified monitoring device as described above, since a plurality of temperature sensors (3) in the vertical direction are fixed and fixed at fixed intervals, the surface of the liquid When only LNG between the temperature sensor (4) closest to the liquid level and the temperature sensor (4) is layered, as shown in FIG. 5, the temperature difference (5) between the uppermost layer and the lower layer is (5). There is a problem that it is not detected and the stratification cannot be determined.

The present invention has been made in order to solve the above-mentioned problems of the conventional stratification monitoring device, and provides a stratification monitoring device capable of determining the stratification by detecting the temperature difference in the upper layer of the liquid. It is what

[Means for Solving Problems] A stratified monitoring device for an LNG tank according to the present invention comprises a plurality of axial floats which float in a liquid with a central axis in the vertical direction, arranged in a line in the vertical direction and at equal intervals. The temperature sensor is mounted and a shock absorber is provided to prevent the temperature sensor from colliding with the inner wall surface of the tank and being damaged.

[Operation] In the present invention, the temperature or temperature difference sensor for monitoring stratification is attached to the float at a constant interval in the vertical direction, so that the measurement position of each sensor follows the fluctuation of the liquid surface and is always the liquid surface. To a predetermined depth from the LNG near the liquid surface
Even when the layers are layered, the temperature difference can be detected, and it can be reliably determined whether or not the layers are layered.

[Embodiment] FIG. 1 is an explanatory view showing an embodiment of the present invention, in which (6) is a cylindrical float having a plurality of temperature sensors attached, and (7) is a predetermined interval in the vertical direction on the float (6). (8) is a shock absorber.

The uppermost one of the temperature sensors is mounted so as to have a predetermined depth from the liquid surface. The shock absorber (8) has a ring (8a) whose radius is slightly longer than the length of the temperature sensor (7) and is attached to the upper and lower parts of the axial float (6).

In the stratification monitoring device for the LNG tank configured as described above, the temperature sensor (7) attached to the float (6) at a predetermined interval causes the float (6) to respond accordingly even if the liquid level changes. Since it moves up and down, the position from the liquid surface of LNG is always kept at a predetermined depth, and the temperature of LNG near the liquid surface and the layer below it can be measured reliably. As a result each temperature sensor
By recording the value detected by (7) with a multipoint temperature recorder, it is possible to accurately determine whether or not the LNG in the tank is stratified.

This temperature sensor (7) does not necessarily have to be a sensor that can accurately detect the absolute value of the temperature, but may be a temperature sensor that can detect the difference between the liquid temperature near the liquid surface and the temperature below it. ． Also, if the LNG density changes, it floats.
The distance between the temperature sensor (7) attached to (6) and the liquid level changes, but there are multiple temperature sensors (7) attached, so be sure to measure the temperature difference accordingly. You can

Also, the radius of the ring (8a) of the shock absorber (8) depends on the temperature sensor (7).
When the float (6) collides with the side wall of the tank, the float (6) comes into contact with the side wall of the tank before the temperature sensor group (7) to prevent the temperature sensor from being damaged.

The structure of the shock absorber is not limited to that of the present embodiment, and may be of another type.

[Effects of the Invention] As described above, the present invention has a structure in which a plurality of temperature sensors for monitoring stratification are attached to a float that floats in the liquid. It is possible to always accurately measure the temperature difference between and to determine whether or not the LNG in the tank is stratified, and it is possible to prevent the rollover phenomenon that occurs due to stratification.

[Brief description of drawings]

FIG. 1 is a perspective view of a stratification monitoring device showing an embodiment of the present invention, FIG. 2 is an operation explanatory diagram of the stratification monitoring device, and FIG. 3 is an explanatory diagram showing stratification of LNG in a tank, FIG. 4 is a schematic diagram showing a conventional stratification monitoring device, and FIG. 5 is an explanatory diagram for explaining problems in the conventional device. In the figure, (1) is layered LNG, (2) is convection in the layer, (3) and (7) are temperature sensors, (4) is the temperature sensor closest to the liquid surface, and (5) is temperature. LNG layer where no difference is detected, (6) is an axial float, (8) is a shock absorber, and (8a) is a ring.

Claims (1)

[Scope of utility model registration request] 1. An axial float that floats in a liquid with a central axis in the vertical direction, a plurality of temperature sensors mounted on the axial float in a line in the vertical direction at equal intervals, and the axial float. And a shock absorber provided to protect the temperature sensor, and a stratified monitoring device for the LNG tank.