JPH06221497A - Gas liquefaction and gasification device and its operation method - Google Patents

Abstract

PURPOSE:To cool gas for reliquefying gas without using a heat transfer pipe by providing a plural number of steps of heat exchangers and cooling vessels and changing flow rate of refrigerant for cooling in each heat exchanger in accordance with temperature level. CONSTITUTION:A gas passage 10 reaches a LNG tank 12 through a first heat exchanger 21, a second heat exchanger 22, and a third heat exchanger 23 in this order. On the other hand, this device is provided with a cooling tank 30, and four cooling vessels including a first cooling vessel 31, a second cooling vessel 32, a third cooling vessel 33, and a fourth cooling vessel 34 which are heat insulated each other are installed in parallel in the cooling tank 30. This device can cool gas, even if refrigerant for cooling 26 at liquid phase is used, by providing the heat exchangers 21 to 23 and cooling vessels 31 to 34 at a plural number of steps and changing flow rate of refrigerant in accordance with temperature level, that is, in accordance with heat exchangers at each step. Consequently, it is possible to exclude a heat transfer pipe which has been a necessity in the conventional device and reduce the cost.

Description

Detailed Description of the Invention

[0001]

The present invention relates to liquefied natural gas (LN
G) The present invention relates to a device for liquefying, storing, and vaporizing other gases and a method for operating the device.

[0002]

2. Description of the Related Art Conventionally, in order to provide a stable supply of city gas or the like, so-called peak shaving, in which, for example, city gas is stored in a gas holder at midnight, and the stored gas is discharged during peak use during the daytime, for example. Is being done. When performing such peak shaving, it is possible to significantly reduce the volume required for storage by liquefying the gas once and storing it in the tank instead of storing it as a gas in the gas holder. . However, if such liquefaction of city gas is simply executed by a cold heat source of only a refrigeration cycle, a great amount of power (actually electric power) will be consumed. For this reason, conventionally, a method of reducing the required power (external cold heat) by using a cold storage container has been provided (see, for example, JP-A-63-9800).

FIG. 9 shows an example of an apparatus for realizing the above method. In the figure, reference numeral 90 denotes a cold storage container containing a cold storage refrigerant, and a meandering heat transfer tube 91 is vertically arranged in the cold storage container 90. When the gas is liquefied, the gas to be liquefied is introduced into the upper end portion (that is, the high temperature side end portion) of the heat transfer tube 91 through the passage 92, is cooled by the cold storage refrigerant 99 in the heat transfer tube 91, and is further passed through the passage 93. Is introduced into the liquefying heat exchanger 94 through which it is completely liquefied by external cold heat and stored in the liquefied gas container 95. On the other hand, when the gas is vaporized, the liquefied gas in the liquefied gas container 95 is decompressed by the valve 98, and then introduced into the lower end portion (that is, the low temperature side end portion) of the heat transfer tube 91 in the cold storage container 90 through the passage 96. After being heated by the cold storage refrigerant 99 in the cold storage container 90, it is further heated by external heating by the vaporization heat exchanger 97, completely vaporized, and discharged to the outside. During this vaporization, cold heat is stored in the cold storage refrigerant 99 by heat exchange with the gas.

FIGS. 10 (a) and 10 (b) respectively show temperature-enthalpy changes during liquefaction and vaporization when cold storage is not performed and when cold storage is performed. As shown in (a) of the same figure, when the cold storage is not used, it is necessary to rely on external cooling and external heating for all liquefaction and vaporization of gas, whereas as shown in (b) of the same figure, In the case of using, the cold storage heat is received from the refrigerant in the region from the temperature A to the temperature B during the liquefaction, and the cold storage heat is applied to the coolant in the region from the temperature C to the temperature D during the vaporization, whereby the external cooling In addition, the required power can be reduced because the area where external heating must be performed is significantly reduced.

[0005]

In the cold storage container as described above, the heat transfer tube is of a type in which the heat transfer tube is immersed in the cold storage medium for heat exchange. Moreover, since the heat transfer between the heat transfer tube and the cold storage refrigerant is due to natural convection heat transfer, the heat transfer coefficient is generally low. Therefore, in order to compensate for this, it is necessary to provide a fin around the heat transfer tube or to increase the number and length of the heat transfer tube, which is a major factor of cost increase.

In view of such circumstances, it is an object of the present invention to provide a device and a method of operating the same which can realize gas liquefaction and vaporization with a low cost structure without using a heat transfer tube. .

[0007]

The present invention is provided with a liquefied gas container for storing liquefied gas, and the liquefied gas is introduced into the liquefied gas container in a liquefied state and liquefied from the liquefied gas container. In a gas liquefaction and vaporization apparatus in which gas is taken out in a vaporized state, N heat exchangers from a first heat exchanger to an Nth heat exchanger (N is a constant of 2 or more), and these heat exchangers From the first heat exchanger to the Nth
A gas introduction passage for introducing the gas to be liquefied into the liquefied gas container in series up to the heat exchanger, and a liquefied gas from the liquefied gas container to draw the liquefied gas from the Nth heat exchanger to the first heat exchanger Up to the gas introduction passage, the gas lead-out passage for sending out to the outside through the series in the reverse order, and (N + 1) pieces from the first cold storage container to the (N + 1) th cold storage container that stores the cold storage refrigerant in an adiabatic state Of the cold storage container and the cold storage refrigerant in the (N + 1) th cold storage container during liquefaction are sequentially introduced from the Nth heat exchanger to the first heat exchanger into the first cold storage container and the nth heat exchanger and the ( (n + 1) heat exchanger (n is a natural number not less than 1 and not more than (N-1)) and a part of the refrigerant for cold storage is branched and introduced into the (n + 1) th cold storage container. And the first heat exchange of the cold storage refrigerant in the first cold storage container during vaporization To the Nth heat exchanger and introduced into the (N + 1) th cold storage container, and the cooling storage refrigerant is connected to the (N + 1) th heat exchanger between the nth heat exchanger and the (n + 1) th heat exchanger. ) A vaporizing refrigerant circulating means for merging the cold storage refrigerant in the cold storage container is provided (Claim 1).

Here, in order to supplement the cold heat at the time of liquefaction, cooling for further cooling and liquefying the fluid passing through the gas introduction passage at a position downstream of the Nth heat exchanger in the gas introduction passage. Means are preferably provided (Claim 2).

Further, a refrigerating cycle is provided as the cooling means, and in this refrigerating cycle, in order to store a part or all of the exhaust heat of the compressor in the first cool storage container, the refrigerating cycle for the cool storage refrigerant is provided with a first 1 A heat exchanger is provided at a position downstream of the heat exchanger and at a position downstream of the compressor with respect to the refrigeration cycle circulation passage, and heat is exchanged between the cycle refrigerant and the heat storage refrigerant by this heat exchanger. By configuring the replacement, a more excellent effect as described later can be obtained (claim 3).

Further, the present invention provides a method of operating the above apparatus, in which the refrigerant temperature at the inlet side and outlet side of each heat exchanger at the time of liquefaction is lower than the temperature of the gas to be liquefied flowing at the same point. Set the flow rate of the cold storage refrigerant in each heat exchanger and vaporize it so that the temperature of the cold storage refrigerant at the inlet and outlet sides of each heat exchanger during vaporization is higher than the temperature of the gas to be vaporized flowing at the same point. The flow rate of the cold storage refrigerant in each heat exchanger at this time is set (claim 4).

Further, by replenishing the liquefied gas in a portion closer to the liquefied gas container than the total heat exchanger, the total vaporized amount of the gas is made larger than the total liquefied amount of the gas. The effect is obtained (claim 5).

[0012]

In the apparatus according to claim 1, when the gas is liquefied, the gas to be liquefied is first passed through the gas introduction passage.
Pass the heat exchanger to the Nth heat exchanger in series in order. As a result, the gas is cooled by heat exchange with the cold storage refrigerant flowing through each heat exchanger, specifically, the cold storage refrigerant distributed from the (N + 1) th heat exchanger to each heat exchanger, and further, the cooling means is provided. In some cases (Claim 2) this provides cooling,
It is stored in a liquefied gas container in a liquefied state. here,
The amount of the cold storage refrigerant flowing through each heat exchanger is set such that the temperature at each point of the cold storage refrigerant is lower than the temperature of the liquefied gas flowing through the same point as described in claim 4. Therefore, the heat exchange in each heat exchanger is favorably performed. The flow rate of the cold-storage refrigerant can be adjusted by the amount of the cold-storage refrigerant split into each cold-storage container, and a specific setting procedure will be described in the section of the embodiment below.

Next, when the gas is vaporized, that is, the liquefied gas is discharged, the liquefied gas in the liquefied gas container is sequentially passed in series from the Nth heat exchanger to the first heat exchanger through the gas outlet passage. As a result, the gas is a cold storage refrigerant flowing through each heat exchanger, more specifically, a cold storage refrigerant introduced from each heat exchanger from the first heat exchanger to the Nth heat exchanger to the (N + 1) th heat exchanger. It is heated by heat exchange with and is taken out of the device in a vaporized state. Here, regarding the amount of the cold storage refrigerant flowing through each heat exchanger, as described in claim 4, the temperature of each point of this cold storage refrigerant is higher than the temperature of the gas to be vaporized flowing through the same point. By setting, the heat exchange in each heat exchanger will be favorably performed. The flow rate of the cold storage refrigerant can be adjusted by the amount of the cold storage refrigerant merged from each cold storage container, and the details thereof will be described in the section of Examples below.

Further, according to the third aspect of the present invention, in the refrigerating cycle, the temperature of the refrigerant for the cycle at the outlet of the compressor is lowered by the refrigerant for the cold storage. As a result, the temperature of the refrigerant for the cycle at the inlet of the compressor is lowered, which Therefore, the power required for the refrigeration cycle required for liquefaction will be reduced. In addition, the cold storage refrigerant is heated by heat exchange in the refrigerant heat exchanger, and the hot exhaust heat is stored in the cold storage container.Therefore, the hot exhaust heat is used to add the gas in the gas outlet passage during vaporization. By heating, the amount of heat required for heating for vaporization can also be reduced.

According to the operating method of the fifth aspect,
By replenishing the liquefied gas from the outside, operation is performed so that the total vaporized amount of the liquefied gas becomes larger than the total liquefied amount, so the total enthalpy at the time of vaporization also increases as the total vaporized amount increases. As a result, the difference between the gas temperature during liquefaction and the gas temperature during vaporization at the same point widens. As a result, it is possible to widen the temperature range of the cold storage refrigerant in which heat can be exchanged between the cold storage refrigerant and the gas.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 (a) shows the flow when the gas is liquefied in the apparatus of the present invention, and FIG. 1 (b) shows the flow when the gas is vaporized. In addition, in this embodiment, an apparatus for liquefying and vaporizing city gas (natural gas; NG) will be described, but in the present invention, regardless of the gas to be liquefied and vaporized, other various gases having appropriate boiling points Can be applied.

1 (a) and 1 (b), 10 is a gas passage (gas introduction passage and gas discharge passage), and this gas passage 10 includes a first heat exchanger 21, a second heat exchanger 22, and a third heat exchanger.
It passes through the heat exchanger 23 in order and reaches the LNG tank (liquefied gas container) 12. In the gas passage 10, the portion between the third heat exchanger 23 and the LNG tank 12 is the same as the introduction passage 16 as shown in FIG.
A heat exchanger (cooling means) 14 for performing external cooling is provided in the introduction passage 16 and a pressure reducing valve 18 is provided in the introduction passage 20. Are provided respectively.

On the other hand, a cold storage tank 30 is installed in this apparatus, and in the cold storage tank 30, a first cold storage container 31, a second cold storage container 32, a third cold storage container 33, and a fourth cold storage container which are insulated from each other. The four cold storage containers of the container 34 are arranged in parallel.

In each of the cold storage containers 31 to 34, the same type of cold storage refrigerant 26 is housed in a state where the temperatures are different from each other.
The cold storage refrigerant 26 has a minimum temperature (-1 in this embodiment).
The basic condition is that it does not freeze even at about 30 ° C.), but it is more preferable that it is inexpensive, has low toxicity, and has a high boiling point. Although it is difficult to obtain a pure substance that satisfies all of these conditions, for example, by mixing a medium having a eutectic composition such as ethanol or methanol at a ratio near the eutectic composition, the region shown in FIG. 44
Thus, it is possible to obtain a suitable product having a substantially low freezing point. By mixing such multiple substances, the range of selection of the cold storage refrigerant 26 is expanded.

The cold storage containers 31 to 34 may be installed separately from each other, but these cold storage containers 31 to 31 are also provided.
If 34 is formed by partitioning the cold storage tank 30 having a constant capacity as shown in the figure, it is very advantageous in terms of cost and installation space. In this case, each cold storage container 3
Refrigerant 2 for cold storage accommodated therein between 1 to 34
In order to maintain the temperature difference between the six members, it is very preferable to form the cold storage containers 31 to 34 with the heat insulating material 37 lined with the membrane 38 as shown in FIG.

The regenerators 31 to 34 are connected to the heat exchangers 21.
To 23 through a refrigerant passage (which constitutes a liquefying refrigerant circulating means and a vaporizing refrigerant circulating means) 35.
Specifically, the refrigerant passage 35 is provided in each of the heat exchangers 21-23.
Heat exchange passage 350 penetrating in a series state, and four branch passages 351 to 354 branched from the heat exchange passage 350.
And the branch passage 351 includes the first heat exchanger 2
1 is branched from a position outside (on the left side in the drawing) and connected to the first cold storage container 31, and the branch passage 352 is branched from a position between the first heat exchanger 21 and the second heat exchanger 22. Second
The branch passage 353 is connected to the cold storage container 32, the branch passage 353 is branched from a position between the second heat exchanger 22 and the third heat exchanger 23, and is connected to the third cool storage container 33, and the branch passage 354 is the third heat exchange. It branches from a position outside (right side in the figure) of the container 23 and is connected to the fourth cool storage container 34. In addition, a refrigerant pump 36 for drawing out the cold storage refrigerant 26 from the three cold storage containers 31 to 33 or sending the cold storage refrigerant 26 to the cold storage containers 31 to 33 is provided in the three branch passages 351 to 353. It is provided.

Next, the operation of this device will be described.

First, when liquefying (that is, storing) NG, as shown in FIG. 1A, the NG is passed through the gas passage 10 to the first heat exchanger 21 and the second heat exchanger 2.
While passing through the second and third heat exchangers 23 in this order, the cold storage refrigerant 26 in the fourth cold storage container 34 is led out through the branch passage 354, and the cold storage refrigerant 14 is passed through the third heat exchanger 23, the second
The heat exchanger 22 and the first heat exchanger 21 are passed in this order to
While being introduced into the cool storage container 31, the flow is divided into the third cool storage container 33 and the second cool storage container 32 through branch passages 353 and 352 in the middle. This allows
The NGs passing through the gas passage 10 are heat exchangers 21 to 23.
It is cooled by heat exchange with the cold storage refrigerant 26 flowing therethrough, and is further externally cooled by the liquefying heat exchanger 14 in the liquefying gas passage 16 to be completely liquefied and stored in the LNG tank 12 in this state.

During this liquefaction, the cold storage refrigerant 26 and NG
In order to ensure good heat exchange between the
The amount of refrigerant flowing through 23 must be set to an appropriate value, which will be described in detail later.

On the other hand, when vaporizing (ie, paying out) the LNG, as shown in FIG. 1B, the LNG in the LNG tank 12 is decompressed by the pressure reducing valve 18 in the outlet passage 20 ( In this embodiment, 8 kg / cm ² G → 6 kg /
cm ² G), then the third heat exchanger 23, the second heat exchanger 2
2, while passing through the first heat exchanger 21 in this order, the cold storage refrigerant 26 is derived from the first cold storage container 31, and the cold storage refrigerant 26 is passed through the heat exchange passage 350 to the first heat exchanger 21 and the second heat exchanger. While passing through the container 22 and the third heat exchanger 23 in this order to be introduced into the fourth cold storage container 34, the cold storage refrigerant 26 is provided with branch passages 352, 35 in the middle of the heat exchange passage 350.
The refrigerant for cold storage 26 in the second cold storage container 32 and the third cold storage container 33 is appropriately merged through 3. As a result, the LNG passing through the gas passage 10 is cooled by heat exchange with the cold storage refrigerant 26 flowing through the heat exchangers 23 to 21, and is further externally heated by the after heater 38 to be completely vaporized and then taken out of the apparatus. Be done.

Next, the procedure for setting the flow rate of the cold storage refrigerant 26 will be described with reference to FIG.

In FIG. 2, N flown in the liquefaction process
The temperature-enthalpy curves of G and LNG flown in the vaporization process are shown by solid line 40L and solid line 40G, respectively. The "enthalpy difference", which is the amount on the vertical axis of this graph, means the total amount of enthalpy at each point based on the enthalpy at the high temperature side exit point of the third heat exchanger 23 (that is, per liquefaction / vaporization cycle). This means the amount of change in the total enthalpy), and therefore the enthalpy differences during liquefaction and vaporization are all the same at the same point.

As shown in the figure, the temperature-enthalpy curve 40L of NG at the time of liquefaction sharply bends at the boiling point of NG (around -130 ° C), and the region where gas and liquid coexist (the region above the boiling point). Then, the curve is convex upward. The temperature-enthalpy curve 40G at the time of vaporization is similar to the temperature-enthalpy curve 40L at the time of liquefaction,
The amount of self-cooling generated by decompression in the pressure reducing valve 18 and the amount of external cold heat in the liquefying heat exchanger 14 deviate to the low temperature side (left side in the figure).

Here, in order to ensure good heat exchange between the NG and LNG and the cold storage refrigerant 26 during liquefaction and vaporization, the inlet and outlet sides of the heat exchangers 21 to 23 during liquefaction are secured. The refrigerant temperature needs to be lower than the temperature of NG flowing at the same point, and the refrigerant temperatures at the inlet side and the outlet side of each heat exchanger 21-23 at the time of vaporization need to be higher than the temperature of LNG flowing at the same point. This is shown in the graph of FIG. 2, where the two temperature-enthalpy curves 40G and 40L are
It is necessary that the temperature-enthalpy curve of the cold storage refrigerant 26 be located between the two.

However, since the cold storage refrigerant 26 always maintains the liquid phase, the relationship between the temperature and the enthalpy difference is shown in FIG.
Is a straight line in the graph, and it is impossible to position such a simple straight line between the two temperature-enthalpy curves 40L and 40G. Therefore, the flow rate of the cold storage refrigerant 26 in each of the heat exchangers 21 to 23 is adjusted to change the slope of the temperature-enthalpy line in each of the heat exchangers 21 to 23, and each line is represented by, for example, the broken lines 41, 42 in FIG. By setting the number to 43, it is possible to realize excellent heat exchange during liquefaction and vaporization. This cold storage refrigerant 26
The flow rate in each of the heat exchangers 21 to 23 is the amount of the cold storage refrigerant 26 diverted to the second cold storage container 32 and the third cold storage container 33 during liquefaction, and the second cold storage container 3 during liquefaction.
This can be easily set by adjusting the amount by which the cold storage refrigerant 26 is led out from the second and third cold storage containers 33 and merged.

That is, in this apparatus, the heat exchanger and the cold storage container are provided in a plurality of stages, and the flow rate of the refrigerant is changed according to the temperature level (in other words, according to the heat exchanger of each stage). It is characterized in that cold storage can be performed even by using a liquid-phase cold storage refrigerant 26 having a similar temperature-enthalpy characteristic, thereby eliminating the heat transfer tube that was indispensable in the conventional device. The cost can be reduced significantly.

Next, a second embodiment will be described with reference to FIGS.

Here, at the time of liquefaction shown in FIG. 5A, the total heat exchanger is taken as an example and the flow rate is 1 ton / hour (hereinafter T
/ H), LNG is added to the LNG tank 12 from the outside of the device by a tank truck 48 or the like at a flow rate of 0.1 T / H, and both are introduced into the LNG tank 12, and at the time of vaporization, as shown in FIG. Moreover, LNG is paid out at a flow rate of 1.1 T / H.

In this way, LNG is replenished from the outside with L
If the total vaporization amount of NG is made larger than the total liquefaction amount of NG, the enthalpy of LNG during vaporization is further increased (1.1 times that in the case of not replenishing in this example). As shown in FIG. 6, the difference between the temperature-enthalpy curve 40L at the time of liquefaction and the temperature-enthalpy curve 40G at the time of vaporization becomes wider than in the case of FIG. Along with this, the settable range of the flow rate of the cold storage refrigerant 26 for heat exchange (the area between the two curves 40L and 40G) also expands, so that, for example, as shown in FIGS. Even if the number of stages of the cold storage container and the heat exchanger is reduced as compared with the device of FIG. 1, as shown in FIG.
The temperature-enthalpy straight line, that is, the broken line consisting of the broken lines 51 and 52 in FIG. 6 can be positioned inside both curves 40L and 40G, which makes it possible to further reduce the cost of the device.

Furthermore, when the amount of LNG supplied from the outside is sufficient, the cold added by this supply causes
As shown in (a), the liquefaction heat exchanger 14 in the first embodiment can be omitted.

The method for obtaining such an effect is not limited to the method of replenishing LNG on the upstream side of the LNG tank 12, and for example, LNG may be replenished directly to the LNG tank 12 after completion of liquefaction, or liquefaction may be performed. The same effect can be obtained by a method of storing excess LNG in the LNG tank 12 in advance before starting. In addition, the LNG from the LNG tank 12 during vaporization is not replenished during liquefaction.
At the time of NG payout, LNG may be added to the LNG from the outside and introduced into the heat exchangers 21 and 22.

Next, a third embodiment will be described with reference to FIGS. 7 and 8.

In the figure, 50 is a refrigeration cycle,
The refrigerating cycle 50 cools NG in the liquefying process by circulating a cycle refrigerant and passing it through the liquefying heat exchanger 14. This refrigeration cycle 50
Includes a cycle heat exchanger 51, an expansion turbine 52, a compressor 57, an aftercooler 58, and a refrigerant heat exchanger 59 in this order, and the liquefaction heat exchanger 14 is arranged downstream of the expansion turbine 52. Further, the refrigerant heat exchanger 59 has the first heat exchanger 2 in the heat exchange passage 350 of the refrigerant passage 35.
1 and the branch passage 351 are arranged, and in this refrigerant heat exchanger 59, heat exchange between the cold storage refrigerant 26 flowing in the refrigerant passage 35 and the cycle refrigerant circulating in the refrigeration cycle 50 is performed. It is supposed to be.

According to such an apparatus, since the cycle refrigerant is cooled by the heat exchange in the refrigerant heat exchanger 59, the refrigerating cycle power required for the liquefaction as shown in FIG. 7 is correspondingly cooled. On the other hand, while the cold storage refrigerant 26 heated by the heat exchange is introduced into the first cold storage container 31, the gas temperature at the device outlet at the time of vaporization as shown in FIG. It is possible to omit external heating means such as an after heater.

That is, in this apparatus, the cold storage refrigerant 26
A refrigerant heat exchanger 59 for exchanging heat between the refrigerating cycle 50 and the cycle refrigerant circulating in the refrigerating cycle 50 is provided, whereby the cold heat required for liquefaction is pumped from the cold storage tank 30 and the hot exhaust heat generated in the refrigerating cycle 50 is vaporized. Since it functions as a so-called heat pump that serves as a heat source at the time, the refrigerant for the cycle is cooled by the aftercooler 58 alone like the conventional refrigeration cycle, and the gas is specially heated externally at the time of vaporization. Compared to the heating device,
It is possible to simultaneously reduce the required power both during liquefaction and during vaporization.

The present invention is not limited to the above embodiments, and the following modes can be adopted as examples.

(1) In each of the above embodiments, the gas passage 10 is also used as the gas introduction passage and the gas discharge passage in the present invention, but the present invention is not limited to this, and both passages are constructed separately. You may do it. In each of the above embodiments, the refrigerant passage 35 and the refrigerant pumps 36 are also used as the liquefying refrigerant circulating means and the vaporizing refrigerant circulating means in the present invention, but in the present invention, the liquefying refrigerant circulating means and the vaporizing refrigerant circulating means are shown. The refrigerant circulating means may be separately configured. For example, the liquefying refrigerant passage and the vaporizing refrigerant passage may be provided side by side, and both may be passed through a common heat exchanger.

(2) In the present invention, the number of heat exchangers and regenerators may be appropriately set according to various conditions, the total number of heat exchangers is N (≧ 2), and the number of regenerators is (N + 1).
In such a case, during liquefaction, the cold storage refrigerant in the (N + 1) th cold storage container is sequentially introduced from the Nth heat exchanger to the first heat exchanger into the first cold storage container and the nth heat of the cold storage refrigerant is transferred. Exchanger and (n + 1) th heat exchanger (n is 1 or more (N-
1) Part of the cold storage refrigerant passing between each of the following natural numbers) is split and introduced into the (n + 1) th cold storage container, and at the time of vaporization, the cold storage refrigerant in the first cold storage container is fed from the first heat exchanger. The N-th heat exchanger is sequentially passed through and introduced into the (N + 1) th cold storage container, and the cold storage refrigerant is stored in the n-th cold storage container between the (n + 1) th heat exchanger and the (n + 1) th heat exchanger. The effect of the present invention can be obtained by merging the use refrigerant.

(3) In the apparatus shown in FIG. 7, the refrigeration cycle 5
No particular specific configuration is applicable to the liquefaction heat exchanger 14, and conventionally known ones can be widely applied as long as the gas can be sufficiently cooled in the liquefying heat exchanger 14.

[0046]

As described above, the present invention is provided with a plurality of stages of heat exchangers and regenerators, and changes the flow rate of the regenerator refrigerant in each heat exchanger in accordance with the temperature level to cool the liquid phase. Since it is possible to perform cold storage using a refrigerant, it is possible to perform reliquefaction and vaporization of gas using cold storage as in the conventional device while eliminating the heat transfer tube that was conventionally required. This has the effect of significantly reducing the cost of the device.

According to the third aspect of the present invention, the power required for liquefaction is reduced by cooling the cycle refrigerant for cooling the liquefaction target gas by heat exchange with the cold storage refrigerant. At the same time, by returning the cold storage refrigerant warmed by this heat exchange to the cold storage container, the gas temperature at the outlet of the device during vaporization can be kept sufficiently high, and both reduce the power required for both liquefaction and vaporization. There is an effect that can be.

According to the operating method of the fifth aspect,
Since the operation is performed so that the total vaporization amount of the liquefied gas becomes larger than the total liquefaction amount by the supplement of the liquefied gas from the outside, the total enthalpy at the time of vaporization increases with the increase of this total vaporization amount, It is possible to widen the difference between the gas temperature during liquefaction and the gas temperature during vaporization at the same point. That is, it is possible to widen the temperature range of the cold storage refrigerant that enables heat exchange between the cold storage refrigerant and the gas, and thereby,
This has the effect of reducing the required number of heat exchangers and cold storage containers.

[Brief description of drawings]

FIG. 1 (a) is a flow sheet showing a gas flow at the time of reliquefaction and natural gas reliquefaction in a first embodiment of the present invention, and FIG. 1 (b) is a gas flow at the time of gasification in the same device. Is a flow sheet showing.

FIG. 2 is a temperature-enthalpy curve of NG during liquefaction and a temperature-enthalpy curve of NG during vaporization in the above apparatus.
3 is a graph showing a temperature-enthalpy curve of a cold storage refrigerant during liquefaction and vaporization.

FIG. 3 is a solid-liquid phase diagram showing substances that can be used as a refrigerant in the above apparatus.

FIG. 4 is a cross-sectional view showing a structural example of a cold storage container in the above apparatus.

FIG. 5 (a) is a flow sheet showing a gas flow at the time of reliquefaction and natural gas reliquefaction in the second embodiment of the present invention, and FIG. 5 (b) is a gas flow at the time of gasification in the same device. Is a flow sheet showing.

FIG. 6 is a temperature-enthalpy curve of NG during liquefaction in the above apparatus, a temperature-enthalpy curve of NG during vaporization,
3 is a graph showing a temperature-enthalpy curve of a cold storage refrigerant during liquefaction and vaporization.

FIG. 7 is a flow sheet showing a gas flow during reliquefaction in a natural gas reliquefaction and vaporization apparatus according to a third embodiment of the present invention.

FIG. 8 is a flow sheet showing a gas flow at the time of vaporization in the above apparatus.

FIG. 9 is a flow sheet showing an example of a conventional gas reliquefaction and vaporization apparatus.

FIG. 10 (a) is a graph showing a change in temperature-enthalpy when cold storage is not used in the gas reliquefaction and vaporization steps, and FIG. 10 (b) is a conventional apparatus in which cold storage is used in the gas reliquefaction and vaporization steps. It is a graph which shows the change of temperature-enthalpy in the case.

[Explanation of symbols]

10 gas passage (gas introduction passage and gas discharge passage) 12 LNG tank (liquefied gas container) 14 liquefaction heat exchanger (cooling means) 16 introduction passage (gas introduction passage) 20 discharge passage (gas discharge passage) 21 1 heat exchanger 22 2nd heat exchanger 23 3rd heat exchanger 26 refrigerant for cold storage 30 cold storage tank 31 first cold storage container 32 second cold storage container 33 third cold storage container 34 fourth cold storage container 35 refrigerant passage (liquefaction refrigerant Circulating means and vaporizing refrigerant circulating means) 36 Refrigerant pump (constituting liquefying refrigerant circulating means and vaporizing refrigerant circulating means) 50 Refrigeration cycle 59 Refrigerant heat exchanger

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshinori Kusumi, 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka Gas Co., Ltd. (72) Mitsuaki Hata 4-1-2, Hirano-cho, Chuo-ku, Osaka No. within Osaka Gas Co., Ltd.

Claims (5)

[Claims] 1. A liquefied gas container for storing liquefied gas is provided, the gas is introduced into the liquefied gas container in a liquefied state, and the liquefied gas discharged from the liquefied gas container is taken out in a vaporized state. In a gas liquefaction and vaporization apparatus to be used, N heat exchangers from a first heat exchanger to an Nth heat exchanger (N is a constant of 2 or more) and a first heat exchanger for these heat exchangers. To the Nth heat exchanger, a gas introduction passage for introducing the liquefied target gas in series to the liquefied gas container, and a liquefied gas from the liquefied gas container to draw the liquefied gas from the Nth heat exchanger to the first From the first cold storage container that stores the cold storage refrigerant in a heat-insulated state to the (N + 1) th cold storage container ( N + 1)
The individual cold storage containers and the cold storage refrigerant in the (N + 1) th cold storage container during liquefaction are sequentially introduced from the Nth heat exchanger to the first heat exchanger into the first cold storage container, and at the same time as the nth heat exchanger. Liquefaction refrigerant circulation in which a part of the cold storage refrigerant passing between the (n + 1) heat exchanger (n is a natural number of 1 or more and (N-1) or less) is branched and introduced into the (n + 1) th cold storage container. And the refrigerant for cold storage in the first cold storage container at the time of vaporization is sequentially introduced from the first heat exchanger to the Nth heat exchanger into the (N + 1) th cold storage container, and the nth heat exchanger is used as the cold storage refrigerant. Between the (n + 1) th heat exchanger and the (n + 1) th heat exchanger.
+1) A gas liquefaction and vaporization apparatus comprising: a vaporizing refrigerant circulating means for joining the cold storage refrigerant in the cold storage container. 2. The gas liquefaction and vaporization apparatus according to claim 1, wherein a fluid passing through the gas introduction passage is further cooled and liquefied at a position downstream of the Nth heat exchanger in the gas introduction passage. A gas liquefaction and vaporization device, which is provided with a cooling means for 3. The gas liquefaction and vaporization apparatus according to claim 2, wherein a refrigeration cycle is provided as the cooling means, and in this refrigeration cycle, part or all of exhaust heat of a compressor is stored in the first cold storage container. Further, a heat exchanger is provided at a position downstream of the first heat exchanger with respect to the cold storage refrigerant circulation passage and at a position downstream of the compressor with respect to the refrigeration cycle circulation passage. A gas liquefaction and vaporization device, characterized in that heat is exchanged between a cycle refrigerant and a heat storage refrigerant. 4. The gas liquefaction and vaporization apparatus according to claim 1, wherein the refrigerant temperature on the inlet side and the outlet side of each heat exchanger during liquefaction is higher than the temperature of the liquefaction target gas flowing at the same point. The flow rate of the cold storage refrigerant in each heat exchanger during liquefaction is set so that it also becomes low, and the temperature of the cold storage refrigerant on the inlet side and the outlet side of each heat exchanger during vaporization A method for operating a gas liquefaction and vaporization device, characterized in that the flow rate of the refrigerant for cold storage in each heat exchanger at the time of vaporization is set so as to be higher than the temperature. 5. The method for operating a gas liquefaction and vaporization apparatus according to claim 4, wherein the liquefied gas is replenished to a portion on the liquefied gas container side of the total heat exchanger so that the total gasification amount of the gas is reduced. A method for operating a gas liquefaction and vaporization device, which is characterized in that the amount is larger than the liquefaction amount.