JPS5919800A - Low-temperature liquid storing tank - Google Patents

Abstract

PURPOSE:To prevent the stratification of liquid stored in a tank, by disposing a heat-insulating sleeve opened at its opposite ends in the liquid stored in the tank. CONSTITUTION:Low-temperature liquid in a lower layer B, heated by the heat applied from the bottom face and the side face of a tank 1, is passed through an annular passage formed between the tank 1 and the heat-insulating sleeve 5 and flows upward while raising its temperature. Then, the heated liquid is distributed through a clearance 2 over the surface of low-temperature liquid in an upper layer A and flows toward the central portion or the peripheral portion of the tank 1 while lowering its temperature through evaporation. During the above while, the heated liquid is mixed with the low-temperature liquid in the upper layer A. Thus, since the low-temperature liquid in the upper layer A and that in the lower layer B are mixed with each other gradually from the surface of the upper layer A, roll over is not caused. In the above arrangement, it is necessary to vary the values of the clearances 2, 3 and the depth 4 according to the heating rate at the bottom and side faces of the tank and the type of the liquid to be stored in the tank 1.

Description

[Detailed Description of the Invention] When storing cryogenic liquid in a tank, no matter how insulated the bottom and sides of the tank, it cannot be completely insulated, and the low temperature equivalent to artificial heating from the bottom and sides of the tank cannot be completely insulated. It is inevitable that liquid will evaporate from the storage liquid surface. When a low-temperature liquid is injected into the tank, it is generally done with some remaining low-temperature liquid, and low-temperature liquids having different physical properties such as temperature and density are supplied.

At this time t? The two liquids do not mix easily, convection occurs in the upper and lower layers, and these layers maintain a relatively stable state.

However, after a considerable amount of time has passed, the lower layer is heated from the side at the bottom of the tank, and the density difference between the upper and lower layers becomes smaller. rapidly increases, place iF] rolled oats z JJ
7. Elephants may occur.

To prevent this kind of rollover phenomenon, low-temperature liquid tanks are supplied from the top when receiving low-temperature liquid with a higher density than the stored liquid, and from the bottom when receiving low-temperature liquid with a lower density. Facilitates mixing with existing stock solutions.

Also, as shown in Figure 1, for some reason the tank (r)
When the interior is divided into upper and lower layers (Al (B), a low temperature liquid of E3+ is spouted from the nozzle (C) installed on the bottom of the tank to form a boundary layer between the upper and lower layers (A) and (B). and promotes mixing of both layers.

However, the former method requires the preparation of such a receiving device, and these methods alone cannot achieve complete mixing, and the latter method detects the stratification situation and, moreover, does not handle low-temperature liquids. In addition, the evaporation volume is not only increased by the energy of the jet stream, but also efficient (-5) The present invention was proposed to prevent the rollover phenomenon described in 11 As shown in Figure 1,
Uni 2 J) 1 (Considering a state in which Al CB+ is stably formed, if the amount of heat transfer from the side surface exceeds a certain level, the material in the lower layer (B) will break through the boundary layer. , reaches the top of the upper layer (Al) along the tank side wall,
It was experimentally confirmed that the lower layer (T3) was mixed in the same upper layer (A) and the lower layer (T3) was sequentially stacked, and that no rollover phenomenon occurred.

The present invention was proposed by focusing on such experimental findings, and is designed to actively pump the low-temperature liquid in the lower layer to the low-temperature liquid in the upper layer to the extent that rollover does not occur. Inside, there is a heat insulating tube with open top and bottom ends to prevent layering of the stored liquid.
-ff characteristic of low temperature/lk storage V.

In the present invention, as described in item 1J, an insulating cylinder with open upper and lower ends is installed in the liquid storage inside the tank, so that it is heated by heat input from the bottom surface of the cooker as well as from the 1111j surface. The low-temperature liquid in the lower layer passes through the passage formed between the heat insulating cylinder and the side wall of the tank described in 11J or inside the heat insulating cylinder, and rises while gradually increasing its temperature. The liquid then spreads from near the surface of the storage liquid to the surface of the upper layer of low-temperature liquid, evaporates and lowers the temperature while flowing to the center or periphery, during which time it also mixes with the upper layer of low-temperature liquid.

In this way, the low-temperature liquids in the upper and lower layers in the tank are slowly mixed from the surface of the upper layer, so that no rollover phenomenon occurs. Furthermore, even if the stored liquid is separated and stratified for some reason, it is safe because it automatically mixes as a natural phenomenon.

As described above, according to the present invention, the low-temperature liquid in the lower layer in the tank is allowed to rise to the vicinity of the surface of the upper-layer low-temperature liquid without being significantly influenced by the boundary layer between the upper and lower layers, and the low-temperature liquid in the upper and lower layers is slowly drawn from the same surface. By mixing, the rollover phenomenon is prevented, and at the same time, the temperature rise of the low-temperature liquid in the tank is kept small by directly supplying the low-temperature liquid heated by heat input from the bottom and sides of the tank to the liquid storage surface. It is something that lasts.

The present invention is applicable to all storage tanks, such as low-temperature liquefied gas storage tanks, in which materials with slightly different physical properties are stored in the same tank, and it is preferable that these materials do not mix and form layers. be.

The illustrated embodiment in which the present invention is applied to a low-temperature liquefied gas storage tank will be described and explained below.

(1) is a cylindrical tank, with an appropriate gap (2) inside from the side wall of the tank (1), an appropriate gap (3) from the bottom of the tank, and a low-temperature upper layer (A). A heat insulating cylinder (5) is disposed concentrically with the tank (1) at an appropriate depth 4) from the liquid surface.

The bottom surface of the tank (1) and the lower layer (Bl) heated by the heat input from the bottom surface (111 or 16) pass through the annular passage between the tank (1) and the heat insulating cylinder (5) to raise the temperature. The upper layer (A) spreads from the gap (2) near the surface of the low-temperature liquid, evaporates and flows toward the center or periphery while lowering the temperature. ) is also mixed with the low temperature liquid.

At this time, it is necessary to select the length of each of the gaps (2) (31 depth 4) so as not to destroy the stratification conditions of the upper and lower layers (Alt (B). If it is too small, the lengths of the upper and lower layers (A) (B )
The rollover phenomenon occurs as the densities approach each other. Note that the values of each gap and depth need to be changed depending on the heat input from the bottom and side surfaces of the tank and the storage material.

In this way, in the illustrated low-temperature liquid tank, the upper and lower) fN (A
Since the low temperature liquid of )(B) is slowly mixed from the surface of the upper layer FA, ), no rollover phenomenon occurs. Furthermore, even if the low-temperature liquid is separated and stratified for some reason, it is safe because it automatically mixes as a natural phenomenon.

FIG. 6 shows another embodiment of the present invention, in which the lower edge and the tank (
1) One or more heat insulating cylinders (8) were installed in the tank (1) with a distance (6) from the bottom and an upper layer (depth 7 from the low temperature Al liquid). It is a tank (
1) The low-temperature liquid of the lower layer (1B) heated at the bottom is guided to the surface of the upper layer (Al low-temperature liquid) through the heat insulating cylinder (8), and both the upper and lower layers (A) ([3) are mixed and evaporated. This is to prevent the rollover phenomenon from occurring.

Although the present invention has been described above with reference to embodiments, the present invention is of course not limited to such embodiments, and may be modified in various ways without departing from the spirit of non-invention. is also σ).

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view showing an example of a conventional low-temperature liquid storage tank;
6 and 6 are longitudinal cross-sectional views showing respective embodiments of the low-temperature liquid tank according to the present invention. (1)...Tank, (5)(8)...Insulated tube Sub-agent Patent attorney Shige Okamoto 2 people outside the text 17 Cya 2z

Claims (1)

[Claims] 1. A low-temperature liquid storage tank characterized in that a heat insulating cylinder with open upper and lower ends is provided in the liquid stored inside the tank to prevent stratification of the stored liquid.