JP2020133871A - Fuel gas supply system and fuel gas supply method - Google Patents

Abstract

To provide a fuel gas supply system capable of supplying fuel gas with a different calorific value to a demand destination stably and inexpensively without deterioration of quality, and a fuel gas supply method.SOLUTION: An LNG supply system 1 is configured to vaporize "low calorific value LNG" discharged from a first LNG tank TL, to generate "power generation gas" to be supplied to a demand destination via a first NG supply line 30A; and vaporize "high calorific value LNG" discharged from a second LNG tank TH, to generate "city gas" to be supplied to the demand destination via a second NG supply line 30B.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fuel gas supply system and a fuel gas supply method, and more particularly to a fuel gas supply system and a fuel gas supply method capable of supplying a fuel gas having a high calorific value and a fuel gas having a low calorific value to a demand destination. It is a thing.

Conventionally, at LNG terminals, liquefied natural gas (hereinafter referred to as "LNG") stored in a tank (LNG tank) is vaporized to give "city gas" (hereinafter, "LNG") to general households and the like. In addition to supplying gas vaporized from "NG" (hereinafter referred to as "NG"), other demand destinations such as "NG" used for gas generators (hereinafter referred to as "gas for power generation") are supplied to power plants and the like. We are operating to supply.

In general, the properties (quality) of "NG" supplied from an LNG terminal are often determined according to the intended use of the demand destination.
Specifically, in the case of "city gas", the calorific value suitable for use at the demand destination (for example, "45 MJ / m ³ ") is strictly defined, while in the case of "power generation gas" Although there is no strict regulation as for "city gas", it is required to adjust to the required calorific value (for example, "40.5 to 42.5 MJ / m ³ ") specified by the contract.

By the way, in recent years, the demand for LNG has been expanding worldwide from the viewpoint of global warming countermeasures, and "unconventional LNG" (for example, shale gas) whose production volume is increasing is drawing attention.
Such "unconventional LNG" is relatively easy to procure and its price is stable at a low level. Therefore, in the future, the ratio of "unconventional LNG" to the total LNG procurement amount at LNG terminals will be Is expected to increase.

However, in general, the calorific value of "unconventional LNG" is relatively low (for example, "40-42.5 MJ / m ³ "), so the ratio of "unconventional LNG" to the total LNG procurement amount. As the amount of heat generated increases, the average calorific value of LNG held by the LNG terminal also decreases accordingly.

In such a case
(A) In the case of "city gas", it goes without saying that it is far from the specified calorific value (for example, "45 MJ / m ³ ").
(B) In the case of "power generation gas", if "LNG" (for example, "41MJ / m ³ ") that matches the required calorific value is received (stored) in the LNG tank, this is used. It may be difficult to maintain (eg, out of the range of "40.5-42.5 MJ / m ³ ").

Therefore, as a method for eliminating such inconvenience, for example, a technique such as Patent Document 1 is known.
The technique of Patent Document 1 is
An "LNG vaporizer" that vaporizes "LNG" to generate "NG",
A "BOG compressor" that compresses the boil-off gas (Boil Off Gas, hereinafter referred to as "BOG") discharged from the tank.
An "LPG vaporizer" that vaporizes liquefied petroleum gas (hereinafter referred to as "LPG") to generate LPG vaporized gas.
A "flow rate control valve" that adjusts the amount (flow rate) of LPG vaporized gas generated by the "LPG vaporizer"
A "mixer" that mixes the "BOG" boosted by the "BOG compressor" and the LPG vaporized gas whose flow rate is adjusted by the "flow rate control valve".
A "gas conduit" that supplies "NG" to the demand destination in a state where the "BOG" mixed by the "mixer" and the "NG" generated by the "LPG vaporizer" are merged.
It is equipped with.

According to such a technique, it is possible to raise "city gas" or the like to a predetermined calorific value by providing a "flow rate control valve", a "mixer" or the like.

Real Fairness 06-022429 Gazette

However, in general, "LPG" used for increasing the heat of "LNG" and "NG" is relatively expensive, and therefore, in the technique of Patent Document 1, the cost (gas production unit price) is increased as the amount used increases. ) Was expensive.

Further, in the technique of Patent Document 1, in order to obtain a predetermined calorific value such as "city gas", it is necessary to control the opening / closing amount of the "flow rate adjusting valve" with relatively high accuracy, and depending on the control content, heat generation There is a problem that the amount varies and it is not always possible to supply a certain quality of "city gas" to the demand destination.

Further, in the technique of Patent Document 1, since "BOG" to which "LPG" is added is configured to be directly introduced into the "gas conduit" through which "NG" flows, it has a relatively large capacity (discharge pressure, etc.). It is necessary to use a high-performance "BOG compressor", which causes a problem that power consumption increases depending on the driving frequency and the like.

An object of the present invention is to solve such a problem, and to stably and stably produce fuel gas having a different calorific value (for example, "city gas" or "power generation gas") without causing deterioration in quality. The purpose is to provide a fuel gas supply system and a fuel gas supply method that can be supplied to a demand destination at low cost.

According to the fuel gas supply system according to the present invention, the above-mentioned problems are a first low-temperature tank for storing a low-temperature liquid, a second low-temperature tank for storing a low-temperature liquid having a higher calorific value than the low-temperature liquid, and the first low-temperature tank. A first payout line connected to a low-temperature tank for supplying a first fuel gas having a first calorific value to a demand destination, and a second calorific value connected to the second low-temperature tank and higher than the first calorific value. By mixing the heating fuel with the second payout line for supplying the second fuel gas to the demand destination and the low temperature liquid flowing through the first payout line or the fuel gas obtained by vaporizing the low temperature liquid. A calorific value adjusting device capable of generating the second fuel gas is provided, and the low temperature liquid adjusted to a calorific value range predetermined as the first calorific value is stored in the first low temperature tank. It will be resolved.

Further, according to the fuel gas supply method according to the present invention, the above-mentioned problems include a first low temperature tank for storing a low temperature liquid, a second low temperature tank for storing a low temperature liquid having a calorific value higher than that of the low temperature liquid, and the above. A first payout line connected to a first low temperature tank for supplying a first fuel gas having a first calorific value to a demand destination, and a second line connected to the second low temperature tank and having a higher calorific value than the first calorific value. A fuel gas supply method in a fuel gas supply system including a second payout line for supplying a second fuel gas having a calorific value to a demand destination, wherein the fuel gas supply method is used as the first calorific value. It is also solved by including a storage step of storing the low temperature liquid adjusted to a predetermined calorific value range in the first low temperature tank.

The term "low temperature liquid" as used herein means a so-called ultra-low temperature or extremely low temperature liquid, and for example, "LNG" or "LPG" is applicable.

Further, the above-mentioned "first fuel gas" (of "first calorific value") and "second fuel gas" (of "second calorific value" higher than "first calorific value") are, for example, "low temperature". If the "liquid" is "LNG", the "power generation gas" (for example, calorific value: "40.5 to 42.5 MJ / m ³ ") becomes the "first fuel gas", and the "city gas" (city gas) For example, the calorific value: "45 MJ / m ³ ") corresponds to the "second fuel gas", respectively.

In the above configuration
(A) By vaporizing the low-temperature liquid discharged from the first low-temperature tank, it is supplied to the demand destination via the first discharge line (first calorific value (hereinafter referred to as "low calorific value")). ) While the first fuel gas is generated
(B) By vaporizing the low-temperature liquid discharged from the second low-temperature tank, it is supplied to the demand destination via the second discharge line (second calorific value (hereinafter referred to as "high calorific value"). ) Second fuel gas is generated,
It is configured as follows.

That is, in the above configuration,
(A) A system in which the first payout line supplies a "low calorific value" first fuel gas (for example, "power generation gas").
(B) A system in which the second payout line supplies a "high calorific value" second fuel gas (for example, "city gas").
Since these systems are simply and clearly separated, it is possible to supply a predetermined calorific value of fuel gas to each demand destination without performing complicated control or the like.

In addition, in the above configuration,
(A) "Low calorific value" low temperature liquid is put into the first low temperature tank, and
(B) "High calorific value" low temperature liquid is put into the second low temperature tank.
Each is configured to be stored.

Therefore, in the above configuration, for example, even if "LNG" species (for example, shale gas) are diversified, they are flexibly accepted (corresponding to) without mixing (without homogenizing) "LNG" having different calorific values. ), Therefore, it is possible to easily manage and accept the calorific value of "LNG".

Further, in the above configuration, a facility (for example, an LNG terminal) in which two gas supply lines (“gas for power generation” supply line and “city gas” supply line) and two or more low-temperature tanks are already provided is provided. ), It can be used almost as it is without requiring large-scale construction work.

Further, in the above configuration, depending on the low temperature liquid stored in the first low temperature tank and the second low temperature tank,
(A) While it is possible to supply the first fuel gas having a "low calorific value" to the demand destination only by vaporizing the low temperature liquid discharged from the first low temperature tank.
(B) By simply vaporizing the low-temperature liquid discharged from the second low-temperature tank, it is possible to supply the second fuel gas having a "high calorific value" to the demand destination.
It is configured as follows.
In such a case, since it is not necessary to perform heat adjustment treatment, it is possible to directly and stably supply high quality fuel gas (first fuel gas and second fuel gas) to the demand destination.

In particular, in the above configuration, if there is no problem with the quality of the low-temperature liquid stored in the first low-temperature tank, the required properties of the first fuel gas (“power generation gas”) used at the demand destination (for example, a power plant). It is possible to secure a sufficient amount.

Here, taking a gas turbine for power generation as an example, this type of gas turbine is configured to be able to perform stable operation as long as the calorific value and combustion speed of "NG" are constant. Is common.
That is, in the above configuration, the operation of the gas turbine is hindered only by storing "LNG" in the first low temperature tank, which has a constant calorific value and combustion rate and satisfies the requirements of the demand destination (power plant, etc.). It is possible to provide "gas for power generation" that does not cause any problems to power plants and the like.

On the other hand, in the above configuration, it is assumed that the low-temperature liquid stored in the second low-temperature tank does not satisfy the calorific value required as the second fuel gas (for example, "45 MJ / m ³ " in the case of city gas). To.
However, since the second low-temperature tank stores a low-temperature liquid having a relatively high calorific value (for example, a low-temperature liquid of "44.5 MJ / m ³ "), the burden required for heat increase is reduced (for example). , The amount of "LPG" added can be reduced).

In the invention relating to the fuel gas supply system, the fuel gas supply system uses the evaporative gas generated in at least one of the first low temperature tank and the second low temperature tank in the low temperature tank. An evaporative gas discharge line for discharging to the outside, a reliquefaction device that cools and reliquefies the evaporative gas discharged through the evaporative gas discharge line, and a reliquefaction gas reliquefied by the reliquefaction device. A reliquefied gas supply line that supplies the gas to the first payout line, a control valve provided in the reliquefaction gas supply line that changes the amount of the reliquefied gas supplied to the first payout line, and the first The control device includes a measuring device that measures a quality value indicating the quality of the fuel gas and a control device that controls the opening / closing amount of the control valve based on the quality value measured by the measuring device. It has a determination unit for determining whether or not the quality value measured by the measuring device satisfies a predetermined quality standard value, and the determination unit determines that the quality value does not satisfy the quality standard value. Then, it is preferable to control the opening / closing amount of the control valve so as to reduce the amount of the reliquefied gas supplied to the first payout line.
In this case, the fuel gas supply system is provided in the second reliquefied gas supply line for supplying the reliquefied gas reliquefied by the reliquefaction device to the second payout line and the second reliquefied gas supply line. The control device further includes a second control valve that changes the amount of the reliquefied gas supplied to the second payout line, and the quality value of the control device does not satisfy the quality reference value by the determination unit. When it is determined, the opening / closing amount of the second control valve is controlled so as to supply the reliquefied gas corresponding to the amount reduced by controlling the control valve to the second payout line. Suitable.

As described above, according to the present invention having such a configuration, a fuel gas having a relatively simple configuration, which can be easily applied to existing equipment and has a different calorific value, can be used. It can be provided stably and inexpensively without causing deterioration in quality.

It is a system diagram for demonstrating the LNG supply system which concerns on this Embodiment. It is a flow chart for demonstrating the content of the LNG supply method which concerns on this Embodiment. It is explanatory drawing for demonstrating the flow of the reliquefaction BOG when the shutdown process is performed. It is explanatory drawing for demonstrating the flow of the reliquefaction BOG at the time of performing an interlock process. It is explanatory drawing for demonstrating the flow of the city gas at the time of performing the process of increasing the amount of city gas supply.

Hereinafter, embodiments of the invention will be described with reference to the drawings. FIG. 1 is a system diagram for explaining the LNG supply system according to the present embodiment, FIG. 2 is a flow diagram for explaining the contents of the LNG supply method according to the present embodiment, and FIG. 3 is a flow diagram when the shutdown process is performed. An explanatory diagram for explaining the flow of the reliquefied BOG, FIG. 4 is an explanatory diagram for explaining the flow of the reliquefied BOG when the interlock process is performed, and FIG. 5 is an explanatory diagram for explaining the flow of the city gas supply amount when the city gas supply amount is increased. It is explanatory drawing for demonstrating the flow of the city gas of.
Is.

(Configuration of LNG supply system 1)
FIG. 1 is a piping system diagram showing an outline of the LNG supply system 1 and the facility to which the LNG supply method according to the present embodiment is applied (hereinafter, referred to as “LNG terminal”). The LNG supply system 1 corresponds to the "fuel gas supply system" described in the claims.

As shown in FIG. 1, the LNG supply system 1 includes an LNG tank T for storing "LNG", an LNG receiving line 10, an LNG payout line 20, a cooling LNG line 25, an NG supply line 30, and a BOG. It includes a discharge line 40, a reliquefaction device R, a reliquefaction BOG supply line 50, a heat control facility 60, and a control device 70. The above-mentioned "LNG", the BOG discharge line 40, the reliquefaction device R, and the control device 70 are the "low temperature liquid", the "low temperature tank", and the "evaporated gas" described in the scope of the patent claim, respectively. It corresponds to "discharge line", "reliquefaction device", "calorific value adjusting device", and "control device".

(LNG tank T)
The LNG tank T is a first LNG tank TL that stores "LNG" (hereinafter referred to as "low calorific value LNG") having a first calorific value ("42.5 MJ / m ³ " in this embodiment) and a first LNG tank TL. The second LNG tank TH that stores the second calorific value (in the present embodiment, "LNG" (hereinafter referred to as "high calorific value LNG") of "44.5 MJ / m ³ ") having a calorific value higher than the calorific value of one. The first LNG tank TL and the second LNG tank TH correspond to the "first low temperature tank" and the "second low temperature tank" described in the claims, respectively. ..

Both the first LNG tank TL and the second LNG tank TH are provided between the inner tank for storing "LNG", the outer tank provided around the inner tank, and the inner tank and the outer tank, and are provided as a cold insulating material. An underground double-shell tank with a cold insulation layer filled with (eg, pearlite).

Various pipes such as the LNG receiving line 10 and the LNG payout line 20 are connected to the first LNG tank TL and the second LNG tank TH, and the first LNG payout pump P1A and the second LNG payout pump P1B are contained therein, respectively. Is provided.

(LNG receiving line 10)
The LNG receiving line 10 is a pipeline for receiving "LNG" unloaded from the LNG tanker S via the unloading arm 2 into the LNG tank T, and is a first LNG receiving line 10A connected to the first LNG tank TL. And a second LNG receiving line 10B connected to the second LNG tank TL.

In the present embodiment, the "low calorific value LNG" unloaded from the LNG tanker S is introduced (as is) into the first LNG tank TL via the first LNG receiving line 10A, while the "high calorific value LNG" is introduced. It is configured to be introduced (as is) into the second LNG tank TH via the 2LNG receiving line 10B.

(LNG payout line 20)
The LNG payout line 20 includes a first LNG payout line 20A connected to the first LNG payout pump P1A, a second LNG payout line 20B connected to the second LNG payout pump P1B, and a first LNG branching from the first LNG payout line 20A. It has a payout branch line 20C. The first LNG payout line 20A and the second LNG payout line 20B correspond to the "first payout line" and the "second payout line" described in the claims, respectively.

The first LNG payout line 20A is a pipeline for paying out the “low calorific value LNG” pumped from the first LNG payout pump P1A to the first NG supply line 30A via the first vaporizer V1 described later. In the present embodiment, the reliquefaction BOG supply line 50 (the first reliquefaction BOG supply line 50A described later) is branched and connected in the pipeline of the first LNG discharge line 20A.

On the other hand, the second LNG payout line 20B is a pipeline for paying out the "high calorific value LNG" discharged from the second LNG payout pump P1B to the second NG supply line 30B via the second vaporizer V2 described later. .. In the present embodiment, the cooling LNG outgoing line 25A, the second reliquefied BOG supply line 50B, the cooling LNG return line 25B, and the LPG payout line 62, which will be described later, are provided in the pipeline of the second LNG payout line 20B, respectively. They are connected in order toward the downstream side.

The first LNG payout branch line 20C is a pipeline for paying out the "low calorific value LNG" to the second NG supply line 30B via the third vaporizer V3 and the second NG branch supply line 30C, which will be described later. In the present embodiment, the flow rate adjusting valve 21 (for example, an electric valve) capable of varying the amount of "low calorific value LNG" introduced into the third vaporizer V3 in the pipeline of the first LNG payout branch line 20C. ) Is provided, and the LPG payout branch line 64, which will be described later, is connected.

In this embodiment, two bypass lines 22A and 22B are provided as pipelines that bypass the first LNG payout line 20A and the second LNG payout line 20B. On-off valves 23A and 23B are provided in the pipelines of the bypass lines 22A and 22B, respectively. In the present embodiment, the on-off valves 23A and 23B are used in any case except for special cases such as performing construction. Is always closed.

(LNG line 25 for cooling)
The cooling LNG line 25 is a pipeline for cooling and reliquefying the “BOG” introduced in the reliquefaction device R, and has a cooling LNG going line 25A and a cooling LNG return line 25B. are doing. The above "BOG" corresponds to the "evaporative gas" described in the claims.

The cooling LNG outgoing line 25A is a pipeline for supplying "LNG" to the reliquefaction device R, and the discharge amount (introduction amount) of "LNG" to the reliquefaction device R is provided in the pipeline. A variable cooling LNG pump P2 is provided.
On the other hand, the cooling LNG return line 25B is a pipeline for returning the “LNG” discharged from the reliquefaction device R to the second LNG payout line 20B again.

(NG supply line 30)
The NG supply line 30 is branched from the first NG supply line 30A connected to the first vaporizer V1, the second NG supply line 30B connected to the second vaporizer V2, and the second NG supply line 30B, and is branched from the third vaporization. It has a second NG branch supply line 30C connected to the vessel V3.
The second NG branch supply line 30C is provided with a flow rate adjusting valve 31 (for example, an electric valve) capable of varying the amount of "city gas" introduced into the second NG supply line 30B in the pipeline. There is. The first NG supply line 30A and the second NG supply line 30B correspond to the "first payout line" and the "second payout line" described in the claims, respectively.

(1st vaporizer V1 to 3rd vaporizer V3)
Here, the first vaporizer V1 to the third vaporizer V3 will be described. Since the first vaporizers V1 to the third vaporizers V3 have almost the same configurations, the first vaporizers V1 will be described below, and the second vaporizers will be described unless necessary. The description of V2 and the third vaporizer V3 will be omitted.

Similar to the known vaporizer, the first vaporizer V1 is for vaporizing "LNG" supplied via the first LNG payout line 20A with seawater or the like to generate "NG"("citygas"). It is a device.
In the present embodiment, the first vaporizer V1 is a "power generation gas" (for example, calorific value: "40.5 to 42.5 MJ / m ³ "), and the second vaporizer V2 and the third vaporizer V3. Is provided as a device for generating "city gas" (calorific value: "45 MJ / m ³ "), respectively. The above-mentioned "power generation gas" and "city gas" are the "first fuel gas" of the "first calorific value" and the "second calorific value" of the "second calorific value" described in the claims, respectively. 2 Fuel gas ”.

That is, in the present embodiment, the first NG supply line 30A connected to the first carburetor V1 is connected to the second carburetor V2 and the third carburetor V3 as a line for supplying "gas for power generation". The second NG supply line 30B to be supplied is systematized as a line for supplying "city gas".

As described above, in the present embodiment, as described above, in addition to the first vaporizer V1 and the second vaporizer V2, "low calorific value LNG" (for example, calorific value: "42.5 MJ / m ³ "). A third vaporizer V3 is provided which vaporizes the gas to generate "city gas" (calorific value: "45 MJ / m ³ ").
In the present embodiment, since such a third vaporizer V3 is provided, when the supply amount of "city gas" to the demand destination tends to be insufficient (flowing through the first LNG payout line 20A), " It is possible to increase the supply amount of "city gas" by using "low calorific value LNG".

Details will be described later, but in this embodiment, when increasing the supply of "city gas",
"LPG" is added by increasing the opening and closing amounts of the flow rate adjusting valve 21 provided on the first LNG payout branch line 20C and the flow rate adjusting valve 65 provided on the LPG payout branch line 64, which will be described later. In addition to introducing "low calorific value LNG" (heated "LNG" (calorific value: "42.5 MJ / m ³ ")) into the third vaporizer V3,
-Increase the opening / closing amount of the flow rate adjusting valve 31 provided in the second NG branch supply line 30C, and use the "NG" (calorific value: "42.5 MJ / m ³ ") generated by the third vaporizer V3. Introduced to 2NG supply line 30B,
It is configured as follows.

(BOG discharge line 40)
The BOG discharge line 40 is a pipeline for discharging the naturally vaporized "BOG" to the outside of the LNG tank T in each of the first LNG tank TL and the second LNG tank TH, and the BOG discharge line 40 is contained in the pipe. A compressor 41 is provided.
In the present embodiment, the "BOG" boosted by the BOG compressor 41 is configured to be introduced into the reliquefaction device R via the BOG discharge line 40.

(Reliquefaction device R)
Here, the reliquefaction device R will be described. The reliquefaction device R according to the present embodiment utilizes the cold heat of the “LNG” introduced via the cooling LNG going line 25A, similarly to the known reliquefaction device. Then, it is a device for reliquefying the "BOG" introduced through the BOG discharge line 40.

(Reliquefaction BOG supply line 50)
The reliquefaction BOG supply line 50 is for pumping the "BOG" (for example, calorific value: "39.6 MJ / m ³ ", hereinafter referred to as "reliquefaction BOG") reliquefied by the reliquefaction device R. It has a condensate pump P3, a first reliquefaction BOG supply line 50A, and a second reliquefaction BOG supply line 50B. The above "reliquefied BOG", the first reliquefied BOG supply line 50A, and the second reliquefied BOG supply line 50B are the "reliquefied gas" and "reliquefied gas" described in the claims, respectively. It corresponds to "gas supply line" and "second reliquefied gas supply line".

The first reliquefaction BOG supply line 50A is connected to the first LNG discharge line 20A, and an emergency shutoff valve 51 (for example, a solenoid valve) capable of blocking the flow of the "reliquefaction BOG" in the pipeline is used. And a flow rate adjusting valve 52 (for example, an electric valve) capable of adjusting the flow rate are provided in order toward the second LNG payout line 20B. The emergency shutoff valve 51 and the flow rate control valve 52 correspond to the "control valve" described in the claims.

The second reliquefaction BOG supply line 50B is connected to the second LNG payout line 20B, and the flow rate adjustment capable of varying the amount of "reliquefaction BOG" introduced into the second LNG payout line 20B in the pipeline. A valve 53 (for example, an electric valve) is provided. The flow rate adjusting valve 53 corresponds to the "second control valve" described in the claims.

(Heat control equipment 60)
The heat control equipment 60 connects the LPG tank 61 for storing the "LPG", the LPG payout line 62 for supplying the "LPG" discharged from the LPG tank 61 to the second LNG payout line 20B, and the first LNG payout line 20A. A flow rate adjusting valve 63 (for example, an electric valve) that adjusts the amount of "LPG" introduced, an LPG payout branch line 64 that branches off from the LPG payout line 62 and is connected to the first LNG payout branch line 20C, and a first LNG. It is equipped with a flow rate adjusting valve 65 (for example, an electric valve) that adjusts the amount of "LPG" introduced into the payout line 20A. The above "LPG" corresponds to the "heat heating fuel" described in the claims.

In the present embodiment, since such a heat control facility 60 is provided, for example,
(A) Even if the calorific value of "LNG" flowing through the second LNG payout line 20B is less than the specified calorific value of "city gas" (calorific value: "45 MJ / m ³ "), "high calorific value LNG" By mixing "LPG" with "", this can be heated and also
(B) When the supply amount of "city gas" to the demand destination tends to be insufficient, "city gas" is mixed with "low calorific value LNG" flowing through the first LNG payout branch line 20C. Can increase the supply of
It is configured as follows.

In the present embodiment, the so-called "liquid-liquid heat adjustment method" is adopted as the method for heating the "LNG", but instead of (or in addition to this), for example,
-"Gas-gas heat adjustment method" (the vaporized "LPG" discharged from the LPG tank 61 and the "BOG" flowing through the BOG discharge line 40 are combined with a gas-gas heat adjustment device such as a mixer. A method of mixing and supplying this to the second NG supply line 30B, a heat control method as in Patent Document 1) may be adopted.
"Liquid-gas heat adjustment method"("LPG" discharged from the LPG tank 61 and "BOG" flowing through the BOG discharge line 40 are mixed by a so-called liquid-gas heat adjustment device, and this is mixed. It is also possible to adopt a method of supplying to the 2NG supply line 30B).

(Control device 70)
The control device 70 has a central control unit (CPU: Central Processing Unit) 71 and a storage unit 72, and can be provided in, for example, a control center that monitors the operation of the gas production facility of the “LNG terminal”. It is a thing. The central control unit 71 corresponds to the "determination unit" described in the claims.

The central control unit 71 is, for example,
(A) The calorific value of "city gas" flowing through the second NG supply line 30B is monitored (for example, a calorimeter (not shown)) to control the opening / closing amount of the flow rate adjusting valve 63, and at the same time.
(B) In addition to monitoring the supply amount of "city gas" flowing through the second NG supply line 30B (for example, a flow meter (not shown)) to control the opening / closing amount of the flow rate adjusting valves 21, 31, 65,
(C)
-Flow rate of "low calorific value LNG" flowing through the first LNG payout line 20A,
-The calorific value and gas components of the "power generation gas" flowing through the first NG supply line 30A,
-Flow rate of "reliquefaction BOG" flowing through the first reliquefaction BOG supply line 50A,
-For cooling based on the measured values of the gas component of "BOG" flowing through the BOG discharge line 40 and the "first quality standard value" and "second quality standard value" stored in the storage unit 72 described later. It controls the drive of the LNG pump P2 and the condensate pump P3, and also controls the opening / closing amount of the flow rate adjusting valves 52 and 53 and the emergency shutoff valve 51. The above-mentioned measured values and a measuring device (for example, a flow meter, a calorimeter, and a gas chromatograph) for measuring the measured values are the "quality value" and the "measuring device" described in the claims, respectively. Corresponds to.

The storage unit 72 of the control device 70 is composed of a semiconductor memory such as a ROM (Read Only Memory), and includes a storage area for storing a basic operation program that controls the basic operation of the LNG supply system 1.
-Information indicating the quality standard value of "city gas" (in this embodiment, calorific value: "45 MJ / m ³ "),
・ Information indicating the amount of "city gas" supplied in advance on the "LNG terminal" side,
-Information indicating the contract value of "gas for power generation" (value agreed with the demand destination to supply "gas for power generation", hereinafter referred to as "first quality standard value") (heat generation in this embodiment). Amount: "40.5 MJ / m ³ "), and
-Voluntary control value of "gas for power generation" (value predetermined on the "LNG terminal" side so that the quality of "gas for power generation" is higher than the above contract value, hereinafter referred to as "second quality standard value" ) (For example, calorific value: "41.5 MJ / m ³ "),
Has a storage area or the like for storing. The above "first quality standard value" and "second quality standard value" correspond to the "quality standard value" described in the claims.

As will be described in detail later, when the central control unit 71 determines that the quality of the "power generation gas" satisfies either the "first quality standard value" or the "second quality standard value",
-The amount of "reliquefied BOG" introduced into the 1st LNG payout line 20A is "15t / h",
-The amount of "reliquefied BOG" introduced into the second LNG payout line 20B is "1 t / h",
The flow rate adjusting valves 52, 53, etc. are controlled so as to be (total amount of reliquefied BOG introduced: "16 t / h").

In addition, the central control unit 71
(A) If it is determined that the quality of the "power generation gas" satisfies the "first quality standard value" but does not meet the "second quality standard value", the flow rate adjusting valves 52, 53, etc. are controlled. ,
-The amount of "reliquefaction BOG" introduced into the 1st LNG payout line 20A has been reduced from "15t / h" to "2t / h" (introduction amount: "13t / h" reduction).
-Increase the amount of "reliquefied BOG" introduced into the second LNG payout line 20B from "1t / h" to "14t / h" (introduction amount: increase by "13t / h").
While performing control (“interlock step S700” described later) (see FIG. 4),
(B) When it is determined that the quality of the "power generation gas" does not meet the "first quality standard value", the emergency shutoff valve 51, the flow rate adjusting valve 53, etc. are controlled.
・ The amount of "reliquefaction BOG" introduced into the 1st LNG payout line 20A is changed from "15t / h" to "0t / h" (shut down) (introduction amount: "15t / h" reduced).
-Increase the amount of "reliquefied BOG" introduced into the second LNG payout line 20B from "1t / h" to "16t / h" (introduction amount: increase by "15t / h").
Control (“shutdown step S600” described later),
(Total amount of reliquefied BOG introduced: "16 t / h").

By the way, the calorific value of the "reliquefied BOG" is the calorific value of the "LNG" stored in the LNG tank (the calorific value of the "LNG" stored in the first LNG tank TL: "42.5 MJ / m ³ ", the first It is generally lower than the calorific value of "LNG" stored in the 2LNG tank TL: "44.5 MJ / m ³ ") (for example, "39.6 MJ / m ³ ").

Then, when the above-mentioned "shutdown" control is performed, the introduction of the "reliquefaction BOG" to the first LNG payout line 20A is cut off, so that the calorific value of the "power generation gas" rises sharply. There is a concern that it will end up.
That is, in general, as the amount of "reliquefied BOG" introduced into the first LNG payout line 20A increases, the amount of heat generation of the "power generation gas" tends to decrease more, and in such a case, the amount of heat change increases. As a result, the quality of the "power generation gas" is likely to deteriorate.

In this regard, the amount of "reliquefied BOG" introduced into the first LNG payout line 20A is
・ Operating status of reliquefaction device R and
-Transfer speed of "reliquefaction BOG" to the second LNG payout line 20B at the time of "shutdown process",
It can be said that it is desirable to limit in advance (for example, "1/11" or less of the supply amount of "power generation gas") in consideration of the above.

Next, the LNG supply method (corresponding to the “fuel gas supply method” described in the claims) according to the present embodiment will be described with reference to FIGS. 1 to 5.
In the following, for convenience of explanation,
-The amount of "LNG" paid out to the first LNG payout line 20A is "160 t / h", and
-The amount of "LNG" paid out to the second LNG payout line 20B is "160 t / h",
To be
-The total delivery amount of the "reliquefaction BOG" sent from the reliquefaction device R under the control of the cooling LNG pump P2 and the condensate pump P3 by the central control unit 71 is "16 t / h".
-The calorific value of "city gas" is set to "45 MJ / m ³ " by the control of the flow rate adjusting valve 63 by the central control unit 71 (excluding the control of the flow rate adjusting valves 21, 31, 65 by the central control unit 71). ),
Will be explained on the premise of.

As shown in FIG. 2, the LNG supply method according to the present embodiment is mainly performed by the central control unit 71 of the control device 70 (excluding the storage step S200 described later), and the first determination step S100 and the storage step S200. The second determination process S300, the third determination process S400, the reliquefaction BOG normal operation process S500, the shutdown process S600, the interlock process S700, the fourth determination process S800, and the city gas supply amount increase process S900. And have.

(First determination step S100)
As shown in FIGS. 1 and 2, the central processing unit 71 is used in the first determination step S100.
(A) In the first LNG tank TL, a predetermined storage amount (hereinafter referred to as "specified storage amount") of "low calorific value LNG" (in this embodiment, calorific value: "42.5 MJ / m ³ ") While determining whether or not "LNG") is stored,
(B) Whether or not "high calorific value LNG" of "specified storage amount" (in this embodiment, "LNG" of calorific value: "44.5 MJ / m ³ ") is stored in the second LNG tank TH. To judge,
Perform processing.

For example, such a determination is made by the storage amount transmitted from the storage amount measuring device (for example, a liquid amount meter) installed in the first LNG tank TL (second LNG tank TL) and the storage stored in advance in the storage unit 72. This can be achieved by comparing with the quantity (“regulated storage”).
In the present embodiment, it is determined in the central processing unit 71 that the "low calorific value LNG"("high calorific value LNG") of the "specified storage amount" is not stored in the first LNG tank TL (second LNG tank TH). Then, while the process proceeds to step S200, when it is determined that the "low calorific value LNG"("high calorific value LNG") of the "specified storage amount" is stored, the process proceeds to step S300. ing. When the central processing unit 71 determines that "LNG" of the "specified storage amount" is not stored in at least one of the first LNG tank TL and the second LNG tank TH, the central processing unit 71 informs the observer and the like to that effect. It is desirable to perform processing for notifying (for example, notification processing such as issuing a warning sound).

(Storage process S200)
In the storage step S200,
(A) When the "low calorific value LNG" of the "specified storage amount" is not stored in the first LNG tank TL, the "low calorific value LNG" unloaded from the LNG tanker S (calorific value: "42.5 MJ / m"). ³ ”“ LNG ”) is received into the 1st LNG tank TL as it is via the 1st LNG receiving line 10A, and at the same time.
(B) When the "high calorific value LNG" of the "specified storage amount" is not stored in the second LNG tank TH, the "high calorific value LNG" unloaded from the LNG tanker S (calorific value: "44.5 MJ / m"). The work of receiving "LNG" of " ³ ") into the second LNG tank TH as it is via the second LNG receiving line 10B is performed.
In the present embodiment, after performing such a receiving operation, the process proceeds to step S100 again. The work of receiving the "low calorific value LNG" in the first LNG tank TL corresponds to the "storage process" described in the claims.

(Second determination step S300)
The central processing unit 71 in the second determination step S300
-Performs a process of determining whether or not the calorific value of the "power generation gas" flowing through the first NG supply line 30A satisfies the "first quality standard value" (contract value) stored in the storage unit 72.
Specifically, the central control unit 71 performs a process of determining whether or not the calorific value of the "power generation gas" is less than "40.5 MJ / m ³ ".

If the central control unit 71 determines that the "first quality standard value" is satisfied, the process is transferred to step S400, and if it is determined that the "first quality standard value" is not satisfied, the process is transferred to step S600. In the present embodiment, the predetermined calorific value of the "power generation gas" is set to the "first quality standard value", but in addition to (or instead of this), for example, the predetermined "power generation gas" is specified. It is also possible to set the nitrogen concentration (“4.0 mol%”) as the “first quality standard value”.

(Third determination step S400)
The central control unit 71 determines whether or not the calorific value of the "power generation gas" flowing through the first NG supply line 30A satisfies the "second quality reference value" (self-management value) stored in the storage unit 72. Perform the processing to be performed.
Specifically, the central control unit 71 performs a process of determining whether or not the calorific value of the "power generation gas" is, for example, less than "41.5 MJ / m ³ ".

When the central control unit 71 determines that the "second quality standard value" is satisfied, the process is transferred to step S500, and when it is determined that the "second quality standard value" is not satisfied, the central control unit 71 performs the process in the interlock step S700. Move. In the present embodiment, the predetermined calorific value of the "power generation gas" is set to the "second quality standard value", but in addition to (or instead of this), for example, the predetermined "power generation gas" is specified. It is also possible to set the nitrogen concentration (“0.3 mol%”) as the “first quality standard value”.

(Reliquefaction BOG normal operation process S500)
In the reliquefaction BOG normal operation step S500, the central control unit 71 controls the amount of the reliquefaction BOG introduced into the first LNG payout line 20A and the second LNG payout line 20B so as to be in the normal operation state.
Specifically, the central control unit 71
(A) The opening / closing amount of the flow rate adjusting valve 52 is controlled so that the flow rate of the "reliquefied BOG" flowing through the first reliquefaction BOG supply line 50A is "15 t / h", and the opening / closing amount is controlled.
(B) The opening / closing amount of the flow rate adjusting valve 53 is controlled so that the flow rate of the "reliquefied BOG" flowing through the second reliquefaction BOG supply line 50B is "1 t / h".
Perform processing.
The central control unit 71 performs the reliquefaction BOG normal operation step S500, and then shifts the process to step S100 again.

(Shutdown step S600)
As shown in FIGS. 1 to 3, when the central control unit 71 determines that the “first quality reference value” (contract value) is not satisfied (second determination step S300), in the shutdown process S600,
(A) On the first reliquefaction BOG supply line 50A side, the emergency shutoff valve 51 is moved to the closed position (for example, the amount of "reliquefaction BOG" introduced into the first LNG payout line 20A: "15 t / h" → "0t / h" (15t / h decrease))
(B) On the second reliquefaction BOG supply line 50B side, the flow rate adjusting valve 53 is opened and moved by a predetermined amount (for example, the amount of "reliquefaction BOG" introduced into the second LNG payout line 20B: "1 t / h" → " 16t / h "(15t / h increase)),
Take control.

As a result, the introduction of "reliquefied BOG" (low calorific value (for example, "39.6 MJ / m ³ ") liquefied fuel) to the first LNG payout line 20A is blocked, so that the heat generated by the "power generation gas" is cut off. It is possible to increase the amount.
After performing the shutdown process S600, the central control unit 71 shifts the process to step S800.

If, as a result of performing the shutdown step S600, the calorific value of the "power generation gas" or the like satisfies the "first quality standard value",
(A) While opening and moving the emergency shutoff valve 51,
(B) The flow rate adjusting valve 53 is closed and moved by a predetermined amount.
Although necessary, such restoration work may be performed manually, or may be performed automatically (for example, controlled by the central control unit 71).

(Interlock process S700)
As shown in FIGS. 1, 2 and 4, when the central control unit 71 determines that the “second quality reference value” (self-control value) is not satisfied (third determination step S400), the interlock step S700 In
(A) On the first reliquefaction BOG supply line 50A side, the opening / closing amount of the flow rate adjusting valve 52 is narrowed down, and the amount of "reliquefaction BOG" introduced into the first LNG payout line 20A is changed from "15t / h" to "2t /". While reducing to "h" (13t / h reduction),
(B) On the second reliquefaction BOG supply line 50B side, the flow rate adjusting valve 53 is opened and moved by a predetermined amount, and the amount of "reliquefaction BOG" introduced into the second LNG payout line 20B is changed from "1 t / h" to "14 t". Increase to "/ h" (13t / h increase),
Take control.

As a result, the introduction of the "reliquefaction BOG" to the first LNG payout line 20A is reduced, so that the calorific value of the "power generation gas" can be (gradually) increased as in the shutdown step S600 described above. Become.
After performing the interlock step S700, the central control unit 71 shifts the process to step S800.

If, as a result of performing the interlock step S700, the calorific value, etc. of the "power generation gas" meets the "second quality standard value",
(A) While moving the flow rate adjusting valve 52 by a predetermined amount,
(B) The flow rate adjusting valve 53 is closed and moved by a predetermined amount.
Although necessary, such restoration work may be performed manually, or may be performed automatically (for example, controlled by the central control unit 71).

(4th determination step S800)
As shown in FIGS. 1 and 2, whether or not the central control unit 71 needs to increase the supply amount of "city gas" supplied via the second NG supply line 30B in the fourth determination step S800. Performs the process of determining.
For example, such a determination includes the flow rate transmitted from the flow rate measuring device (for example, a flow meter) installed in the second NG supply line 30B and the supply amount stored in the storage unit 72 (“specified supply amount”). Can be achieved by comparing.
When the central control unit 71 determines that it is necessary to increase the supply amount of "city gas", it shifts the process to step S900, and when it determines that it is not necessary to increase the supply amount of "city gas", the step again. The process is transferred to S100.

(City gas supply increase process S900)
As shown in FIGS. 1, 2 and 5, the central control unit 71 is in the city gas supply amount increasing step S900.
(A) The third vaporizer V3 is a "low calorific value LNG" (calorific value: "42.5 MJ / m ³ ") mixed with "LPG" by increasing the opening and closing amounts of the flow rate adjusting valves 21 and 65. Introduced to
-Increase the opening / closing amount of the flow rate adjusting valve 31 and introduce "NG" (calorific value: "42.5 MJ / m ³ ") flowing out from the third vaporizer V3 into the second NG supply line 30B.
Control As a result, in addition to "NG" via the second carburetor V2, "NG" via the third carburetor V3 flows through the second NG supply line 30B, so that "city gas" It is possible to increase the supply amount of.
After performing the city gas supply amount increasing step S900, the central control unit 71 shifts the process to step S100 again.

As described above, in this embodiment, in principle,
(A) By vaporizing the "low calorific value LNG" (calorific value: "42.5 MJ / m ³ ") discharged from the first LNG tank TL, "power generation" supplied via the first NG supply line 30A. While "gas" (calorific value: "40.5-42.5 MJ / m ³ ") is generated,
(B) A "city" supplied via the second NG supply line 30B by vaporizing the "high calorific value LNG" (calorific value: "44.5 MJ / m ³ ") discharged from the second LNG tank TH. "Gas" is generated,
It is configured as follows.

That is, in this embodiment,
(A) A system in which the first LNG payout line 20A and the first NG supply line 30A supply "gas for power generation".
(B) A system for the second LNG payout line 20B and the second NG supply line 30B to supply "city gas".
Since these systems are simply and clearly separated, it is possible to supply a predetermined calorific value of fuel gas to each demand destination without performing complicated control or the like.

Moreover, in this embodiment,
(A) "Low calorific value LNG" is added to the first LNG tank TL.
(B) "High calorific value LNG" is added to the second LNG tank TH.
Each is configured to be stored.
Therefore, in the present embodiment, for example, even if "LNG" species (for example, shale gas) are diversified, they are flexibly accepted (corresponding) without mixing (without homogenizing) "LNG" having different calorific values. Therefore, it is possible to easily manage and accept the calorific value of "LNG".

Further, in the present embodiment, two LNG supply lines and two or more LNG tanks are already provided in a facility (for example, an “LNG terminal” as in the present embodiment), which is a large scale. It can be used almost as it is without any complicated construction work.

Further, in the present embodiment, depending on the calorific value of "LNG" stored in the first LNG tank TL and the second LNG tank TH,
(A) By simply vaporizing the "low calorific value LNG" discharged from the first LNG tank TL, it is possible to supply the "power generation gas" to the demand destination as it is.
(B) By simply vaporizing the "high calorific value LNG" discharged from the second LNG tank TH, "city gas" can be supplied to the demand destination as it is.
It is configured as follows.
In such a case, since it is not necessary to perform heat adjustment treatment, it is possible to directly and stably supply high-quality "power generation gas" and "city gas" to the demand destination.

In particular, in the present embodiment, if there is no problem in the quality of the "low calorific value LNG" stored in the first LNG tank TL, the required properties of the "power generation gas" used at the demand destination (for example, a power plant) are satisfied. It is possible to secure a sufficient amount.

Further, in the present embodiment, since "high calorific value LNG" (calorific value: "44, 5 MJ / m ³ ") is stored in the second LNG tank TH, heat is increased even when this is used as it is. It is possible to reduce the burden required for (“city gas” (calorific value: “45 MJ / m ³ ”)) (reduce the amount of “LPG” added).

Further, in the present embodiment, the quality of the "power generation gas" flowing through the first NG supply line 30A is
(A) "First quality standard value" (contract value, for example, calorific value: "40.5 MJ / m ³ ") and "second quality standard value" (self-managed value, for example, calorific value: "41.5 MJ") If any of the reference values of "/ m ³ ") is satisfied, "15 t / h" of "reliquefied gas" is introduced into the first LNG payout line 20A, while "1 t / h" is introduced into the second LNG payout line 20B. Introduced "reliquefied gas"
(B) If the "first quality standard value" is satisfied but the "second quality standard value" is not satisfied, the amount of "reliquefied BOG" introduced into the first LNG payout line 20A is changed from "15 t / h" to "15 t / h". While reducing to "2t / h" (decreasing "13t / h"), the amount of "reliquefied BOG" introduced into the second LNG payout line 20B is increased from "1t / h" to "14t / h" ( "13t / h" increase),
(C) When the "first quality standard value" is not satisfied, the amount of "reliquefied BOG" introduced into the first LNG payout line 20A is changed from "15t / h" to "0t / h"("15t / h"). h ”decrease), increase the amount of“ reliquefaction BOG ”introduced into the 2nd LNG payout line 20B from“ 1t / h ”to“ 16t / h ”(“ 15t / h ”increase),
It is configured as follows.

That is, in the present embodiment, on the first LNG payout line 20A side,
(A) In principle, the "LNG" (for example, calorific value: "44.8MJ / m ³ ") paid out from the 1st LNG tank TL is relatively large ("15t / h") and the "reliquefied BOG" ( For example, a mixture of calorific value: "39.6 MJ / m ³ ")) can be distributed.
(B) When the quality of the "power generation gas" does not meet the "first quality standard value"("second quality standard value"), only the "low calorific value LNG" paid out from the first LNG tank TL ("" A relatively small amount (“2t / h”) of “reliquefied BOG” mixed with “low calorific value LNG”) can be distributed.
It is configured as follows.

Therefore, in the present embodiment, not only can the "power generation gas" be stably supplied to the demand destination, but also a constant quality ("first quality standard value" and "second quality") can be relatively easily supplied. Since the quality can meet the "standard value"), the cost required for gas production can be surely reduced.

On the other hand, in the present embodiment, when the amount of "reliquefied gas" introduced into the first LNG payout line 20A is reduced, the reduced amount of "reliquefied gas" is introduced into the second LNG payout line 20B. It is configured.

That is, in the present embodiment, even when the amount of "reliquefied gas" introduced into the first LNG payout line 20A is reduced, the process of generating "reliquefied gas" by the reliquefaction device R is continued without interruption. It is possible to stably generate a "reliquefied gas" of a certain quality at all times because it can be carried out in a targeted manner.

In general, in a facility that supplies "city gas"("LNGterminal" as in this embodiment), the specified calorific value of "city gas" (calorific value "45 MJ / m ³ ") is set. Since it is necessary to comply with this, in most cases, equipment such as heat conditioning equipment 60 and an LNG tank for storing "LNG" having a relatively high calorific value are provided.

Therefore, even in the case where the calorific value of the "city gas" is reduced by supplying the "reliquefied gas" to the second LNG payout line 20B as in the present embodiment, the existing equipment is used. Therefore, it is possible to increase the heat of "high calorific value LNG".
In this respect, in this embodiment, it can be said that not only "power generation gas" but also "city gas" can be stably supplied to the demand destination while ensuring the quality.

In this embodiment, the reliquefaction device R is used to perform the reliquefaction treatment of "BOG".
(A) It is not necessary to increase the discharge pressure of the BOG compressor 41 more than necessary, and
(B) Since "methane" in "BOG" and "nitrogen" which is a high boiling point component can be separated well, the nitrogen component such as "power generation gas" supplied to the demand destination is reduced. Can be
(C) Since the "BOG" is indirectly cooled by using the cold heat of the "LNG", the calorific value of the "LNG" is hardly lost.
There are merits such as.

As described above, according to the present embodiment, "city gas" and "power generation gas" having different calorific values can be stably and inexpensively supplied to the demand destination without causing deterioration in quality. , Can be easily applied to various facilities such as "LNG terminal".

In the present embodiment, the case where "LNG" as a low-temperature liquid is supplied to a demand destination has been described as an example, but the present invention is not limited to this, and the case where another low-temperature liquid (for example, LPG) is supplied is used. It can also be applied to.

Further, in the present embodiment, a predetermined "calorific value" is set as the "first quality standard value" and the "second quality standard value", but in addition to (or instead of this), other The reference value, for example, "nitrogen concentration" (for example, "nitrogen concentration: 4.0 mol%" as the "first quality reference value", and "nitrogen concentration: 0.3 mol%" as the "second quality reference value" ") And" calorie change rate "(for example," calorie change rate: 5.0% / min "as" first quality reference value ", and" calorie change rate: "as" second quality reference value ". 3.0% / min ") may be set.

Further, in the present embodiment, the "reliquefaction BOG" is configured to be introduced into the first LNG payout line 20A and the second LNG payout line 20B, but it may be configured not to be introduced into either one of the payout lines 20. Well, it can also be configured not to be introduced on any payout line.

Further, in the present embodiment, the first LNG payout branch line 20C, the third vaporizer V3, and the second NG branch supply line 30C are provided as lines for introducing the "low calorific value LNG" into the second NG supply line 30B. , These can be omitted.

Further, in the present embodiment, the heat control equipment 60 is provided only in the system on the “city gas” side, but if necessary, the same heat control equipment is also provided in the system on the “power generation gas” side. Needless to say, it is good.

Although the embodiment to which the invention made by the present inventor is applied has been described above, the present invention is not limited by the discourse and drawings which form a part of the disclosure of the present invention according to this embodiment. That is, it should be added that all other embodiments, examples, operational techniques, etc. made by those skilled in the art based on this embodiment are of course included in the scope of the present invention.

1 LNG supply system 2 Unloading arm 10 LNG receiving line 10A 1st LNG receiving line 10B 2nd LNG receiving line 20 LNG payout line 20A 1st LNG payout line 20B 2nd LNG payout line 20C 1st LNG payout branch line 21 Flow control valve 22A, 22B Bypass Lines 23A, 23B On-off valve 25 Cooling LNG line 25A Cooling LNG outgoing line 25B Cooling LNG return line 30 NG supply line 30A 1st NG supply line 30B 2nd NG supply line 30C 2nd NG branch supply line 31 Flow control valve 40 BOG discharge Line 41 BOG compressor 50 Reliquefied BOG supply line 50A 1st reliquefied BOG supply line 50B 2nd reliquefied BOG supply line 51 Emergency shutoff valve 52, 53 Flow control valve 60 Heat control equipment 61 LPG tank 62 LPG payout line 63, 65 Flow control valve 64 LPG payout branch line 70 Control device 71 Central control unit 72 Storage unit TLNG tank TL 1st LNG tank TH 2nd LNG tank R Reliquefaction device SLNG tanker P1A, P1B LNG payout pump P2 Cooling LNG pump P3 St. Pump V1 1st Vaporizer V2 2nd Vaporizer V3 3rd Vaporizer

Claims (4)

The first low temperature tank for storing cold liquid and
A second low-temperature tank that stores a low-temperature liquid that generates more heat than the low-temperature liquid,
A first payout line connected to the first low temperature tank and for supplying a first fuel gas having a first calorific value to a demand destination,
A second payout line connected to the second low temperature tank and for supplying a second fuel gas having a second calorific value higher than the first calorific value to the demand destination.
A calorific value adjusting device capable of generating the second fuel gas by mixing the heating fuel with the low temperature liquid or the fuel gas obtained by vaporizing the low temperature liquid flowing through the first payout line is provided.
In the first low temperature tank,
A low-temperature liquid adjusted to a predetermined calorific value range as the first calorific value is stored.
A fuel gas supply system characterized by that. The fuel gas supply system
An evaporative gas discharge line for discharging the evaporative gas generated in at least one of the first low temperature tank and the second low temperature tank to the outside of the low temperature tank.
A reliquefaction device that cools and reliquefies the evaporative gas discharged through the evaporative gas discharge line, and
A reliquefied gas supply line that supplies the reliquefied gas reliquefied by the reliquefaction device to the first discharge line, and
A control valve provided in the reliquefied gas supply line and variable in the supply amount of the reliquefied gas to the first discharge line.
A measuring device for measuring a quality value indicating the quality of the first fuel gas, and
A control device for controlling the opening / closing amount of the control valve based on the quality value measured by the measuring device is provided.
The control device is
It has a determination unit for determining whether or not the quality value measured by the measuring device satisfies a predetermined quality standard value.
When the determination unit determines that the quality value does not satisfy the quality reference value, the opening / closing amount of the control valve is controlled so as to reduce the amount of the reliquefied gas supplied to the first payout line.
The fuel gas supply system according to claim 1. The fuel gas supply system
A second reliquefied gas supply line that supplies the reliquefied gas reliquefied by the reliquefaction device to the second discharge line, and
A second control valve provided in the second reliquefied gas supply line and which changes the supply amount of the reliquefied gas to the second discharge line is further provided.
The control device is
When the determination unit determines that the quality value does not satisfy the quality reference value, the reliquefied gas corresponding to the amount reduced by controlling the control valve is supplied to the second discharge line. To control the opening / closing amount of the second control valve,
2. The fuel gas supply system according to claim 2. The first low temperature tank for storing cold liquid and
A second low-temperature tank that stores a low-temperature liquid that generates more heat than the low-temperature liquid,
A first payout line connected to the first low temperature tank and for supplying a first fuel gas having a first calorific value to a demand destination,
A second payout line connected to the second low temperature tank and for supplying a second fuel gas having a second calorific value higher than the first calorific value to the demand destination.
It is a fuel gas supply method in a fuel gas supply system equipped with
The fuel gas supply method is
A storage step of storing a low-temperature liquid adjusted to a predetermined calorific value range as the first calorific value in the first low-temperature tank is included.
A fuel gas supply method characterized by that.