JP3811578B2 - Alcohol-based cryogenic storage material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an alcohol-based cryogenic regenerator material for application to LNG and the like, and more particularly to an alcohol-based cryogenic regenerator material having good fluidity at -135 ° C.
[0002]
[Prior art]
Conventionally, a mixture of ethanol and methanol is known as a cryogenic regenerator material. This cold storage material has a freezing point of −143 ° C. and a low temperature, and is suitable for extremely low temperature cold storage.
[0003]
When this cryogenic regenerator material is applied to, for example, LNG, during the day when the amount of LNG consumption is large, the LNG and the cryogenic regenerator material are heat-exchanged to form a BOG and cool, and stored at night. It can be used for cooling and re-liquefying BOG generated from the LNG tank with a cold storage material for low temperature.
[0004]
[Problems to be solved by the invention]
However, it is a regenerator material suitable for LNG, and in order to store cold using a solid-liquid coexisting phase, the freezing point is high at -143 ° C, it becomes a solid phase when heat exchange with LNG (-169 ° C), and around the heat transfer tube There is a problem that solidified solids grow. In this case, the specific heat of the solid phase is used for cold storage. However, since the specific heat of the liquid phase is larger than that of the solid phase, a sufficient amount of cold storage heat cannot be obtained.
[0005]
Accordingly, an object of the present invention is to solve the above problems and provide an alcohol-based cryogenic regenerator material having a solidification temperature of about −150 ° C. and an extremely low temperature, and having a good fluidity at −135 ° C.
[0006]
[Means for Solving the Problems]
To achieve the above object, the invention of claim 1, the mixed eutectic material about 58 wt% of ethanol and about 42% by weight of methanol, is obtained by addition of water.
[0008]
A second aspect of the present invention, the eutectic material is about 90 wt% or less in water, alcohol cryogenic cold accumulating material according to claim 1, wherein forming a flowable good solid-liquid coexisting phase at about -135 ° C. It is.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0010]
First, 58% by weight of ethanol and 42% by weight of methanol are mixed to form a eutectic material, and water is added to this eutectic material to obtain an alcohol-based cryogenic regenerator material.
[0011]
FIG. 1 shows a phase diagram of three components (ethanol-methanol-water) at a concentration C (wt%) of an eutectic substance and a temperature tw.
[0012]
In this phase diagram, the mixing ratio of the eutectic substance and water was changed from 0 to 100 wt%, and when the temperature tw was lowered to -160 ° C, the temperature at which the phase change occurred was measured. L is a liquidus, S is a solidus, a region where the temperature is higher than the liquidus L is a liquid phase, and a region where the temperature is lower than the solidus S is a solid. A region between the line S and the liquidus line L is a solid-liquid coexisting phase (L + S).
[0013]
In this state diagram, the solid phase line S is constant at −148 ° C. at a eutectic material mixing ratio of 0 to 100 wt%, and the liquidus line L is from 0 ° C. at a eutectic material mixing ratio of 0 wt%, At 90 wt%, it decreases as the mixing ratio increases successively at -148 ° C. And if it becomes 90 wt% or more of eutectic substance (10 wt% or less of water), it will change into a solid phase (Solid) directly when the temperature is lowered from the liquid phase (Liquid) without forming a solid-liquid coexisting phase (L + S). .
[0014]
Therefore, as a regenerator material for reliquefaction of LNG, a material having a ratio of eutectic substance of 90 wt% or less that forms a solid-liquid coexisting phase (L + S) having good fluidity at −135 ° C. is used.
[0015]
The alcohol-based cryogenic regenerator material of the present invention is filled in a regenerator (not shown), a heat transfer tube is provided in the other regenerator, and a cryogenic refrigerant is passed through the heat exchanger tube, thereby The alcohol-based cryogenic regenerator material in the tank is regenerated.
[0016]
At this time, the alcohol-based cryogenic regenerator material forms a solid-liquid coexisting phase (L + S) with good fluidity at −135 ° C., so that the heat transfer coefficient of the heat transfer tube solidifies the solid phase on the surface of the heat transfer tube. Since it becomes larger than a general cold storage material, heat exchange can be performed well, and the heat exchange area can be reduced, and the heat exchanger (heat transfer tube) can be downsized.
[0017]
In addition, since the cold storage stores the amount of cold storage not only in the sensible heat of the liquid phase of the solid-liquid coexisting phase (L + S) but also in the solidification heat of the solid phase, the amount of cold storage heat can be increased.
[0018]
This alcohol-based cryogenic regenerator material of the present invention has a solidification temperature of about −148 ° C. and forms a solid-liquid coexisting phase (L + S) with good fluidity at −135 ° C. It can be a good cold storage material.
[0019]
That is, the temperature of LNG is −169 ° C., and this LNG is passed through a cold storage tank during the day when consumption is high, and the alcohol-based cryogenic cold storage material is stored at −135 ° C. When the amount is small, BOG gas generated from the LNG low-temperature tank is returned to the tank through a heat transfer tube in the cold storage tank in a compressed state, so that reliquefaction can be made using the amount of cold storage heat.
[0021]
【The invention's effect】
In short, according to the present invention, the freezing point is about −150 ° C., and it can be a cold storage material that is good for cold storage at extremely low temperatures compared to the cold storage materials used so far, and at −135 ° C. Since a solid-liquid coexisting phase with good fluidity is formed, the heat exchange rate in the heat storage heat exchanger can be increased.
[Brief description of the drawings]
FIG. 1 is a diagram showing a state diagram of an alcohol-based cryogenic regenerator material according to the present invention.
[Explanation of symbols]
L Liquidus line S Solidus line L + S Solid-liquid coexisting phase

Claims (2)

To about 58 wt% of ethanol and about 42% by weight of the mixed eutectic material methanol, alcohol cryogenic cold accumulating material, characterized in that the addition of water. The alcohol-based cryogenic regenerator material according to claim 1, wherein the eutectic substance is about 90% by weight or less based on water and forms a solid-liquid coexisting phase having good fluidity at about -135 ° C.

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