JP2001324261A - Method and apparatus for refining mixed liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for refining a mixed liquid wherein cold possessed by a low temperature liquefied gas such as LNG or the like can effectively be used for refining the mixed liquid. SOLUTION: After the mixed liquid 11 containing a plurality of kinds of constituents having different solidification temperatures is temporarily stored in a container main body 12 (container), LNG 2 (low temperature liquefied gas) introduced from a liquid phase zone of a low temperature tank 1 is introduced into a bundle of pipes 24 (pipes) disposed within the container main body 12. A constituent having a high solidification temperature is selectively frozen around the bundle of the pipes 24 so as to be extracted from the mixed liquid 11 and the remaining liquid left unfrozen (refined liquid 18) is discharged out of the container main body 12 and recovered. The vaporized gas 2' extracted from the gas phase zone of the low temperature tank 1 and pressurized is introduced into the bundle of the pipes 24 by replacing LNG 2. Thus, the constituent frozen around the peripheries of the pipes 24 are liquefied again and discharged out of the tank main body 12 and recovered separately from the remaining liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for refining a mixed solution for selectively separating a component having a high coagulation temperature from a mixture containing a plurality of types of components having different coagulation temperatures by utilizing cold heat of a low-temperature liquefied gas. It concerns the device.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a general low-temperature liquefied gas storage facility. In FIG. 2, reference numeral 1 denotes a storage device for storing LNG2 (low-temperature liquefied gas) obtained by liquefying natural gas at about -162.degree. The low-temperature tank 3 indicates a thermal power plant (demand destination) that uses the vaporized gas 2 ′ of the LNG 2 as fuel, and the LNG 2 stored in the low-temperature tank 1 is
After being extracted by an LNG pump 4 (low-temperature liquefied gas pump) and raised to a predetermined pressure, it is led to an open rack type vaporizer 5 where heat exchange with seawater 8 guided from a seawater facility 6 through a seawater pump 7 is performed. The vaporized gas 2 ′ is vaporized by the gas generator 2, and the vaporized gas 2 ′ is sent to the thermal power plant 3 for use.

On the other hand, the vaporized gas 2 'generated by natural heat input in the low-temperature tank 1 is always compressed by the compressor 9 from the top of the low-temperature tank 1 in order to keep the pressure in the low-temperature tank 1 below a certain value. After the pressure is increased to the final pressure of the supplied gas (pressure at the outlet of the vaporizer 5) by the compressor 9, the gas is joined to the outlet of the vaporizer 5, and the vaporized gas 2 ′ from the vaporizer 5 is discharged. To the thermal power plant 3 for consumption.

[0004]

However, in such a low-temperature liquefied gas storage facility, the low-temperature tank 1
The low-temperature LNG extracted by the NG pump 4 is led to a vaporizer 5, where the vaporizer 5 exchanges heat with seawater 8 guided from a seawater facility 6 via a seawater pump 7 to form a vaporized gas 2 '. It simply discharges LNG into seawater without any effective use of the cold heat of LNG.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method and an apparatus for purifying a mixed liquid in which the cold of a low-temperature liquefied gas such as LNG can be effectively used for purifying the mixed liquid. It is an object.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a low-temperature liquefied gas stored in a low-temperature tank is used to selectively select a component having a high coagulation temperature from a mixture containing a plurality of types of components having different coagulation temperatures. A method for purifying a mixed liquid, wherein the mixed liquid is temporarily stored in a container, and then a low-temperature liquefied gas introduced from a liquid phase region of a low-temperature tank is introduced into a tube disposed in the container, A component having a high coagulation temperature is selectively frozen around the tube and separated and extracted from the mixed solution, and the remaining liquid that has not been frozen is discharged out of the container and collected, while the gas phase region of the low-temperature tank is collected. The vaporized gas extracted and pressurized is switched to a low-temperature liquefied gas and introduced into the pipe, whereby the components frozen around the pipe are reliquefied and discharged out of the container, and the residual liquid is It is characterized by being collected separately.

[0007] In this manner, the component having a high coagulation temperature in the mixed solution is selectively frozen and separated and extracted by utilizing the cold heat of the low-temperature liquefied gas stored in the low-temperature tank. The remaining liquid remaining in the mixture is discharged out of the container and collected, while the component frozen around the tube is reliquefied and collected separately from the residual liquid, so that the component having a high coagulation temperature from the mixed liquid is recovered. And the purification of the mixed solution can be achieved, and the cold heat of the low-temperature liquefied gas, which has been discarded in the past, can be effectively used.

[0008] Further, when this method is concretely carried out, for example, a shell-and-tube type heat exchanger in which a tube bundle is accommodated in a container body, and a branch from the middle of a liquid discharge line of a low-temperature tank. A refrigerant introduction line connected to the inlet side of the tube bundle, a heating medium introduction line branched from the middle of the vaporized gas extraction line of the low-temperature tank and connected to the middle of the refrigerant introduction line, and a heating medium introduction line. A first flow path switching means for selectively switching between a refrigerant introduction line and a refrigerant introduction line, a refrigerant discharge line connected from the outlet side of the tube bundle to the middle of the liquid discharge line of the low-temperature tank, and a branch from the middle of the refrigerant discharge line A heating medium discharge line connected in the middle of the vaporized gas extraction line of the low-temperature tank, and second flow path switching means for selectively switching between the heating medium discharge line and the refrigerant discharge line. It is possible to configure the liquid mixture purification unit comprises.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an embodiment of a mixed liquid purifying apparatus according to the present invention. In FIG.
FIG. 2 shows a shell and tube type heat exchanger in which a tube bundle 24 (tube) is housed inside a (container);
Is formed in a vertical shape with a predetermined pressure resistance, and the tube bundle 24 is constituted by a plurality of heat transfer tubes 24a.

An introduction pipe 13 is connected to the top of the container body 12 so that a mixed liquid 11 containing a plurality of types of components having different coagulation temperatures can be introduced through an introduction opening / closing valve 13a. A discharge pipe 14 is connected to the bottom of the container body 12 so that the mixed liquid 11 after the treatment can be discharged via a discharge opening / closing valve 14a.

Here, the discharge pipe 14 is branched via a discharge flow switching valve 15 provided on the downstream side of the discharge on-off valve 14a.
And a purified liquid tank 19 for recovering the purified liquid 18 via a purified liquid pump 17, and a separated liquid 22 via a separated liquid on-off valve 20 and a separated liquid pump 21 in the other pipeline. The separated liquid tank 23 to be stored is connected.

In addition, the container body 12 has an inlet tube 25 in which the inlets of the heat transfer tubes 24a forming the tube bundle 24 are integrated.
And an outlet tube 26 in which the outlet sides of the heat transfer tubes 24a are integrated into one.
The inlet pipe 25 is provided with a refrigerant introduction line 28 branched from the middle of the liquid discharge line 27 of the low-temperature tank 1 and a refrigerant introduction opening / closing valve 29 and a first flow path switching valve 33. (First flow switching means), and the first flow switching valve 33 of the refrigerant introduction line 28 is provided with heat branched off from the middle of the vaporized gas extraction line 30 of the low temperature tank 1. The medium introduction line 31 is connected via a heating medium introduction opening / closing valve 32.

Also, the low temperature tank 1 is connected to the outlet pipe 26.
The refrigerant discharge line 34 branched from the middle of the liquid discharge line 27 is connected via a refrigerant discharge opening / closing valve 35 and a second flow path switching valve 38 (second flow path switching means). Second flow path switching valve 3 of discharge line 34
A heating medium discharge line 36 branched from the middle of the vaporized gas extraction line 30 of the low-temperature tank 1 is connected to 8 via a heating medium discharge opening / closing valve 37.

When the mixed liquid 11 is purified by the mixed liquid purifying apparatus shown in FIG.
3a is opened to temporarily store the mixed liquid 11 in the container main body 12 via the introduction pipe 13, and when a predetermined amount of the mixed liquid 11 is stored in the container main body 12, the introduction on-off valve 13a is closed. .

Then, the inlet pipe 25 is connected to the liquid discharge line 27 of the low-temperature tank 1 via the refrigerant introduction line 28 by the first flow path switching valve 33, while the second flow path switching valve 38 The outlet pipe 26 is connected to the liquid discharge line 27 of the low-temperature tank 1 via the refrigerant discharge line 34, and thereafter, the on-off valve 29 for refrigerant introduction is opened to cool the LNG 2 (low-temperature liquefied gas) of the low-temperature tank 1 to low temperature. Tank 1
From the liquid discharge line 27 to the tube bundle 24 through the refrigerant introduction line 28, and then open the refrigerant discharge on-off valve 35 to allow the LN to flow through the heat transfer tube 24a of the tube bundle 24.
G2 is returned to the liquid discharge line 27 of the low-temperature tank 1 via the refrigerant discharge line 34.

At this time, since the LNG 2 flowing through the inside of the heat transfer tube 24a of the tube bundle 24 exchanges heat with the mixed liquid 11 stored in the container body 12, the outer periphery of the heat transfer tube 24a of the tube bundle 24 The component having a high coagulation temperature in the mixed liquid 11 is frozen and separated and extracted.

After the frozen component having a high coagulation temperature has sufficiently grown around the tube bundle 24, the discharge flow path switching valve 1
5 is switched to the purified liquid tank 19 side, and the discharge on-off valve 14
a and the purified liquid on-off valve 16 are opened, and then the purified liquid pump 17 is operated to discharge the unfrozen residual liquid (purified liquid 18) from the container body 12 to the purified liquid tank 19 via the discharge pipe 14. And collect.

Next, after closing the discharge opening / closing valve 14a, the inlet pipe 25 is connected to the vaporized gas extraction line 30 of the low temperature tank 1 through the heating medium introduction line 31 by the first flow path switching valve 33. On the other hand, the second flow path switching valve 3
8, the outlet pipe 26 is connected to the vaporized gas extraction line 30 of the low-temperature tank 1 via the heating medium discharge line 36,
Thereafter, the on-off valve 32 for introducing the heat medium is opened to guide the vaporized gas 2 ′ of the low-temperature tank 1 from the vaporized gas extraction line 30 of the low-temperature tank 1 to the tube bundle 24 via the heat medium introduction line 31, By opening the medium discharge on-off valve 37, the vaporized gas 2 'flowing through the inside of the heat transfer tube 24a of the tube bundle 24 is returned to the vaporized gas extraction line 30 of the low temperature tank 1 via the heat medium discharge line 36.

At this time, the vaporized gas 2 'flowing through the inside of the heat transfer tube 24a of the tube bundle 24 exchanges heat with the component frozen on the outer periphery of the heat transfer tube 24a of the tube bundle 24, so that the component is thawed. Then, the liquid is reliquefied as the separated liquid 22 and flows down to the bottom of the container body 12 and is stored.

Then, the discharge passage switching valve 15 provided in the discharge pipe 14 of the container body 12 is switched to the separation liquid tank 23 side, and the discharge opening / closing valve 14a and the separation liquid opening / closing valve 20 are opened. Activate the pump 21 for the separation liquid 2
2 is discharged from the container body 12 to the separated liquid tank 23 through the discharge pipe 14 and collected.

Thus, the operation for one batch of the mixed liquid refining operation is completed, and thereafter, the above-mentioned batch operation is repeated, whereby the refining operation of the mixed liquid 11 can be continuously performed. Only the operation of freezing and separating and extracting the component having a high coagulation temperature is performed by re-adding the mixed solution 11 several times, and after the frozen component having a high coagulation temperature grows largely around the tube bundle 24, the component is removed. Thawing and re-liquefaction may be performed.

Therefore, according to the above embodiment, components having a high coagulation temperature in the mixed solution 11 are selectively frozen by utilizing the cold heat of the LNG 2 stored in the low-temperature tank 1 to separate and extract the components. The residual liquid (purified liquid 18) remaining in the container is discharged to the outside of the container main body 12 and collected, while the components frozen around the tube bundle 24 are reliquefied and collected separately from the residual liquid, whereby the mixed liquid 11 is recovered. It is possible to purify the mixed liquid 11 by separating components having a high coagulation temperature from the inside, and it is possible to effectively use the cold heat of the low-temperature liquefied gas that has been discarded in the past.

The method and apparatus for purifying a mixed solution of the present invention are not limited to only the above-described embodiment,
Low-temperature liquefied gas other than G may be used,
It goes without saying that various changes can be made without departing from the spirit of the present invention.

[0025]

As described above, according to the method and apparatus for purifying a liquid mixture of the present invention, components having a high solidification temperature in the liquid mixture are removed by utilizing the cold heat of the low-temperature liquefied gas stored in the low-temperature tank. By selectively freezing and separating and extracting, and recovering the residual liquid that has not been frozen, the frozen component is reliquefied and recovered separately from the residual liquid, so that the coagulation temperature from the mixed liquid can be reduced. It is possible to achieve an excellent effect that it is possible to purify the mixed solution by separating high components and to effectively use the cold heat of the low-temperature liquefied gas that has been previously discarded unnecessarily.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an example of an embodiment of a mixed liquid purifying apparatus of the present invention.

FIG. 2 is a conceptual diagram of an example of a conventional general low-temperature liquefied gas storage facility.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Low temperature tank 2 LNG (low temperature liquefied gas) 10 Heat exchanger 11 Mixed liquid 12 Container main body (container) 24 Bundle (tube) 27 Liquid discharge line 28 Refrigerant introduction line 30 Vaporized gas extraction line 31 Heat medium introduction line 33 First Flow path switching valve (first flow path switching means) 34 Refrigerant discharge line 36 Heat medium discharge line 38 Second flow path switching valve (second flow path switching means)

Claims (2)

[Claims] A mixed liquid refining method for selectively separating a component having a high coagulation temperature from a mixture containing a plurality of types of components having different coagulation temperatures by utilizing the cold heat of a low-temperature liquefied gas stored in a low-temperature tank. Then, after the mixed solution is temporarily stored in the container, a low-temperature liquefied gas derived from the liquid phase region of the low-temperature tank is introduced into a tube arranged in the container, and a solidification temperature around the tube is reduced. High components were selectively frozen and separated and extracted from the mixed solution, and the remaining liquid that had not been frozen was discharged out of the container and recovered, while it was extracted from the gas phase region of the low-temperature tank and pressurized. The vaporized gas is introduced into the pipe by switching to a low-temperature liquefied gas, whereby the components frozen around the pipe are reliquefied and discharged out of the container, and collected separately from the residual liquid. Mixture purification method. 2. A mixed liquid refining apparatus for selectively separating a component having a high coagulation temperature from a mixture containing a plurality of types of components having different coagulation temperatures by utilizing the cold heat of a low-temperature liquefied gas stored in a low-temperature tank. A shell-and-tube heat exchanger containing a tube bundle inside the container body, and a refrigerant introduction line branched off from the middle of the liquid discharge line of the low-temperature tank and connected to the inlet side of the tube bundle, A heating medium introduction line branched from the middle of the vaporized gas extraction line of the low-temperature tank and connected to the middle of the cooling medium introduction line, and a first flow path switching for selectively switching the heating medium introduction line and the cooling medium introduction line. Means, a refrigerant discharge line connected to the middle of the liquid discharge line of the low-temperature tank from the outlet side of the tube bundle, and a vaporized gas discharge line of the low-temperature tank branched from the middle of the refrigerant discharge line. A mixed liquid purifying apparatus, comprising: a heating medium discharge line connected in the middle.