JP2001279280A - Method for manufacturing town gas - Google Patents

Method for manufacturing town gas

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Publication number
JP2001279280A
JP2001279280A JP2000095658A JP2000095658A JP2001279280A JP 2001279280 A JP2001279280 A JP 2001279280A JP 2000095658 A JP2000095658 A JP 2000095658A JP 2000095658 A JP2000095658 A JP 2000095658A JP 2001279280 A JP2001279280 A JP 2001279280A
Authority
JP
Japan
Prior art keywords
gas
city
liquefied natural
demand
boil
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2000095658A
Other languages
Japanese (ja)
Other versions
JP4064037B2 (en
Inventor
Hiroshi Emi
浩 江見
Yoshihiro Yamazaki
善弘 山崎
Minoru Takubo
稔 田窪
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Osaka Gas Co Ltd
Original Assignee
Osaka Gas Co Ltd
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Filing date
Publication date
Application filed by Osaka Gas Co Ltd filed Critical Osaka Gas Co Ltd
Priority to JP2000095658A priority Critical patent/JP4064037B2/en
Publication of JP2001279280A publication Critical patent/JP2001279280A/en
Application granted granted Critical
Publication of JP4064037B2 publication Critical patent/JP4064037B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0238—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 2 carbon atoms or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
    • F25J3/0209—Natural gas or substitute natural gas
    • F25J3/0214—Liquefied natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/02—Processes or apparatus using separation by rectification in a single pressure main column system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/90—Boil-off gas from storage

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

PROBLEM TO BE SOLVED: To reduce the power consumption for sending out BOG to town under high pressure to an extremely lower level than the conventional case, depending on the requirement of town gas. SOLUTION: It becomes possible that BOG is liquefied and sent out to town under high pressure even in the case where the demand of the town gas in city is small, without using large amount of LNG by using the BOG as the heat source needed for LNG fractionation in a fractionating apparatus 17. In the case where the demand of the town gas in city is large, a large amount of LNG is used in an LNG/BOG heat exchanger 12, and thereby the power consumption is widely reduced.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、液化天然ガス（以
下、「ＬＮＧ」と略称する）を主原料する都市ガス製造
方法に関する。The present invention relates to a method for producing city gas using liquefied natural gas (hereinafter abbreviated as "LNG") as a main raw material.

【０００２】[0002]

【従来の技術】従来から、都市ガスを製造するＬＮＧ基
地において、原料のＬＮＧは−１５５［℃］以下の極低
温の状態でＬＮＧタンクに貯蔵される。ＬＮＧ基地から
市中に供給する都市ガスは、たとえば３．９［ＭＰａ
Ｇ］（４０［ｋｇｆ／ｃｍ2 Ｇ］）に昇圧する必要があ
る。ＬＮＧタンクに貯蔵されるＬＮＧは、都市ガスとし
ての需要に応じて昇圧され、気化され、液化石油ガス
（以下、「ＬＰＧ」と略称する）などを添加して発熱量
を調整し、都市ガスとして市中に送出される。2. Description of the Related Art Conventionally, in an LNG base for producing city gas, raw LNG is stored in an LNG tank at an extremely low temperature of -155 [° C.] or less. City gas supplied from the LNG base into the city is, for example, 3.9 [MPa]
G] (40 [kgf / cm 2 G]). The LNG stored in the LNG tank is pressurized and vaporized according to the demand as a city gas, and the calorific value is adjusted by adding a liquefied petroleum gas (hereinafter, abbreviated as “LPG”) or the like, and is converted into a city gas. Sent out to the city.

【０００３】ＬＮＧタンクでは、貯蔵中のＬＮＧの一部
が外部からの入熱で気化して、ボイルオフガス（以下、
「ＢＯＧ」と略称する）が発生する。ＬＮＧタンクから
自然発生するボイルオフガスも都市ガスの原料として有
効に使用するためには、昇圧して市中に送出する必要が
あるけれども、気体の状態で圧縮するため、液化してか
ら昇圧する場合に比べ、多大な電力が必要とされる。ま
た、ＢＯＧは、ＬＮＧ中でもメタン（ＣＨ4 ）等を主と
する軽質成分であり、発熱量は比較的小さいので、都市
ガスとして使用するためには、熱量調整が必要である。In the LNG tank, a part of LNG during storage is vaporized by heat input from the outside, and boil-off gas (hereinafter, referred to as boil-off gas).
"BOG") occurs. In order to effectively use boil-off gas naturally generated from LNG tanks as a raw material for city gas, it is necessary to pressurize it and send it out to the city. Requires a large amount of power. In addition, BOG is a light component mainly composed of methane (CH 4 ) in LNG, and has a relatively small calorific value. Therefore, calorific value adjustment is required to use BOG as city gas.

【０００４】図２は、ＢＯＧ高圧送出技術の概要を示
す。ＬＮＧタンクから発生したＢＯＧは、圧縮機１によ
って温度７５［℃］、圧力３．９［ＭＰａＧ］まで昇圧
され、その後冷却器２で温度２０［℃］、圧力３．９
［ＭＰａＧ］まで冷却される。この間に消費される電力
量は４，６１７［ｋＷ・ｈ］となり、一旦気体を液化し
てから昇圧するときと比べ約１，０００〜２，０００
［ｋＷ・ｈ］の電力量を余分に必要とする。昇圧された
ＢＯＧは、その後ＬＰＧ等で熱量調整され、市中に都市
ガスとして送出されるか、または工業用等の低カロリー
顧客等に供給される。FIG. 2 shows the outline of the BOG high-pressure delivery technique. BOG generated from the LNG tank is pressurized to a temperature of 75 ° C. and a pressure of 3.9 MPag by the compressor 1 and then cooled at a temperature of 20 ° C. and 3.9 in the cooler 2.
It is cooled to [MPaG]. The amount of electric power consumed during this time is 4,617 [kW · h], which is about 1,000 to 2,000 compared to the case where gas is once liquefied and then pressurized.
An extra amount of power of [kW · h] is required. The pressurized BOG is then calorie-adjusted by LPG or the like, and is sent out into the city as city gas or supplied to industrial or other low-calorie customers.

【０００５】また都市ガスは規定の発熱量である標準状
態で１ｍ3 の単位体積当り４６，０００［ｋＪ］（１
１，０００［ｋｃａｌ／Ｎｍ3 ］）に調整して市中に送
出されることが義務づけられている。この発熱量は天然
ガスの発熱量より大きいので、通常は天然ガスと、天然
ガスより高価なＬＰＧ等とを混合して発熱量を調整し、
市中に送出される。そこで、これまでにこのＬＰＧ量を
できるだけ削減する技術として分留技術が開発されてき
た。[0005] In addition, city gas has a standard calorific value of 46,000 [kJ] (1 m3) per unit volume of 1 m 3 under a standard condition.
1,000 [kcal / Nm 3 ]) and must be transmitted to the city. Since the calorific value is larger than the calorific value of natural gas, the calorific value is usually adjusted by mixing natural gas and LPG which is more expensive than natural gas.
Sent out to the city. Therefore, a fractionation technique has been developed as a technique for reducing the amount of LPG as much as possible.

【０００６】分留技術では、気液平衡関係を利用して、
ＬＮＧを標準状態で１ｍ3 の単位体積当り４０，６００
［ｋＪ］（９，７００［ｋｃａｌ／Ｎｍ3 ］）の低カロ
リーガスと４６，０００［ｋＪ］の高カロリーガスとに
分離する。ＬＮＧ中から重質成分を分留して増熱用に用
いるか、規定の発熱量を得て、ＬＰＧの使用量を削減す
れば、ＬＮＧとＬＰＧとの価格差によって、原料費のコ
ストダウンを図ることができる。このためには、分留の
際に発生する低カロリーガスを、工業用等、低カロリー
顧客等に、熱量調整なしで供給することができる必要が
ある。これが可能であれば、通常ならＬＮＧより高価な
ＬＰＧを使用して増熱しなければならないところを、Ｌ
ＮＧのみで所定の熱量に調整することができる。また、
分留することによって、ＬＮＧ使用量が増え、都市ガス
の需要が少ないときのＬＮＧ在庫調整に寄与し、原料購
入の弾力化も図ることができる。[0006] In the fractionation technology, utilizing the vapor-liquid equilibrium relationship,
LNG is 40,600 per unit volume of 1 m 3 under standard condition.
[KJ] (9,700 [kcal / Nm 3 ]) is separated into low calorie gas and 46,000 [kJ] high calorie gas. If the heavy components are fractionated from LNG and used for increasing the heat, or if the specified calorific value is obtained and the amount of LPG used is reduced, the cost difference between LNG and LPG will reduce the cost of raw materials. Can be planned. For this purpose, it is necessary that the low-calorie gas generated during fractionation can be supplied to industrial and other low-calorie customers without adjusting the calorific value. If this is possible, it is necessary to increase the temperature by using LPG, which is usually more expensive than LNG.
The heat quantity can be adjusted to a predetermined value only by NG. Also,
By fractionating, the amount of LNG used increases, which contributes to LNG inventory adjustment when the demand for city gas is small, and makes it possible to increase the flexibility of purchasing raw materials.

【０００７】図３は、ＬＮＧ分留技術の概要を示す。た
とえば流量７０［ｔ／ｈ］、温度−１５７［℃］、圧力
３９．２［ｋＰａＧ］（０．４［ｋｇｆ／ｃｍ2 Ｇ］）
のＬＮＧは、まずポンプ４で ３．９［ＭＰａＧ］まで
昇圧される。熱交換器５には、ポンプ６で熱交換用の海
水が供給される。昇圧されたＬＮＧの一部である流量３
０［ｔ／ｈ］の部分が熱交換器５で海水と熱交換するこ
とによって、温度１７［℃］、圧力３．９［ＭＰａＧ］
の天然ガスとなり、その後、残りのＬＮＧと混合するこ
とによって、流量７０［ｔ／ｈ］、温度−８０［℃］、
圧力３．９［ＭＰａＧ］の気液混合状態をつくる。次に
この気液混合状態が分留器７に供給されると、気液平衡
関係から、塔頂７ａからは総発熱量が標準状態の単位体
積１ｍ3当り約４０，６００［ｋＪ］の気体が流量２２
［ｔ／ｈ］で、塔底７ｂからは総発熱量が約４６，００
０［ｋＪ］の液体が流量４８［ｔ／ｈ］で生成される。
これまでに消費される電力量は３５４［ｋＷ・ｈ］とな
る。その後、気体は工業用等低カロリー顧客等に引き取
られ、また液体は海水を熱源として気化され、都市ガス
として市中へ送出される。FIG. 3 shows an outline of the LNG fractionation technique. For example, a flow rate of 70 [t / h], a temperature of -157 [° C.], a pressure of 39.2 [kPaG] (0.4 [kgf / cm 2 G])
Of LNG is first raised to 3.9 [MPaG] by the pump 4. The heat exchanger 5 is supplied with seawater for heat exchange by a pump 6. Flow rate 3 which is a part of the boosted LNG
The portion of 0 [t / h] exchanges heat with seawater in the heat exchanger 5 so that the temperature is 17 [° C.] and the pressure is 3.9 [MPaG].
Of natural gas, and then mixed with the remaining LNG to obtain a flow rate of 70 [t / h], a temperature of -80 [° C],
A gas-liquid mixed state with a pressure of 3.9 [MPaG] is created. Next, when this gas-liquid mixed state is supplied to the fractionator 7, a gas having a total calorific value of about 40,600 [kJ] per unit volume of 1 m 3 in the standard state is obtained from the top 7a from the gas-liquid equilibrium relation. Is the flow rate 22
[T / h], the total calorific value from the bottom 7b was about 46,000.
A liquid of 0 [kJ] is generated at a flow rate of 48 [t / h].
The amount of power consumed so far is 354 [kW · h]. Thereafter, the gas is taken by low-calorie customers such as industrial customers, and the liquid is vaporized using seawater as a heat source and sent out to the city as city gas.

【０００８】これまで、ＢＯＧ高圧送出技術とＬＮＧ分
留技術とは、それぞれ独立した技術として取扱われてき
た。本件出願人は、都市ガス製造に関するＢＯＧ高圧送
出技術やＬＮＧ分留技術について、たとえば、特開昭６
０−２６２８９０号公報や、特開平８−２６９４６８号
公報、特開平１０−１９５４６４号公報などで開示して
いる。Heretofore, the BOG high-pressure delivery technology and the LNG fractionation technology have been treated as independent technologies. The present applicant has disclosed, for example, Japanese Unexamined Patent Publication No.
This is disclosed in Japanese Patent Application Laid-Open No. 0-262890, Japanese Patent Application Laid-Open No. 8-269468, and Japanese Patent Application Laid-Open No. 10-195644.

【０００９】[0009]

【発明が解決しようとする課題】前述のＢＯＧ高圧送出
技術とＬＮＧ分留技術とを併用して、都市ガスを製造す
る際に消費される電力量を合計すると、前述の条件で総
消費電力量は４，９７１［ｋＷ・ｈ］（＝４，６１７＋
３５４）となる。前述のように、ＢＯＧを高圧送出する
場合は、気体状態で圧縮するため、非常に大きな電力を
投入して市中に送出しなければならないという問題が生
じてくる。そこで、これまではこの問題を解決する技術
として、ＢＯＧを一旦、約７８５［ｋＰａＧ］（８［ｋ
ｇｆ／ｃｍ 2 Ｇ］）程度の低圧まで昇圧した後、ＬＮＧ
の冷熱と熱交換することによって液化させ、その後昇圧
することによって消費電力量を大幅に削減する液化技術
が開発されてきた。この技術は消費電力量を削減すると
いう意味では確実に効果を得ることができるけれども、
ＢＯＧを液化するのにＢＯＧ量の約６倍という多量のＬ
ＮＧから冷熱を得る必要があるために、ＬＮＧを大量に
市中へ送出できるという条件が成り立つときのみ可能と
なる技術である。The aforementioned BOG high-pressure delivery
Technology to produce city gas in combination with LNG fractionation technology
When the total amount of power consumed during
The power consumption is 4,971 [kW · h] (= 4,617 +
354). As described above, high-pressure delivery of BOG
When compressing in the gaseous state, very large power is
The problem of having to put it in and send it to the market
Will come. So far, the technology to solve this problem
BOG is temporarily set to about 785 [kPaG] (8 [kPaG]
gf / cm Two G]), and then pressurize LNG
Liquefaction by exchanging heat with the cold of
Technology that greatly reduces power consumption
Has been developed. This technology can reduce power consumption
In that sense, you can certainly get the effect,
To liquefy BOG, a large amount of L of about 6 times the amount of BOG
Large amounts of LNG due to the need to get cold from NG
It is possible only when the condition that it can be sent to the city is satisfied
Technology.

【００１０】都市ガスは、夏場や夜間等には需要が減
り、また冬場や夕方等には需要が増える。つまり、需要
が少ない時期に、消費電力量を抑えるために、ＬＮＧタ
ンクから発生したＢＯＧを従来のＢＯＧ液化技術で液化
させると、その際に多量のＬＮＧを使用することとな
り、そのＬＮＧは市中に送出できないという問題が生じ
てくることになる。また、海水等を温熱源などに用いる
と、海水の使用量が多くなってしまう。[0010] Demand for city gas decreases in summer and at night, and increases in winter and in the evening. In other words, when the BOG generated from the LNG tank is liquefied by the conventional BOG liquefaction technology in order to suppress the power consumption at a time when the demand is small, a large amount of LNG is used at that time, and the LNG is marketed. This causes a problem that the data cannot be transmitted to the server. In addition, when seawater or the like is used as a heat source, the amount of seawater used increases.

【００１１】本発明の目的は、こういった都市ガスの需
要量の変化に対応して、ＬＮＧ分留設備を稼働し、かつ
できるだけＢＯＧを高圧で送出する際に消費される電力
量を抑えることができる都市ガス製造方法を提供するこ
とである。An object of the present invention is to operate the LNG fractionation facility in response to such a change in the demand for city gas, and to reduce the amount of power consumed when BOG is sent at a high pressure as much as possible. It is to provide a method for producing city gas.

【００１２】[0012]

【課題を解決するための手段】本発明は、主原料となる
液化天然ガスをＬＮＧタンクに貯蔵しておき、市中での
都市ガスの需要量に応じて予め定める送出圧力に昇圧
し、都市ガスとして市中に送出する際に、熱量調整のた
めの液化天然ガス分留と、ＬＮＧタンクから発生するボ
イルオフガスの再液化とを行う都市ガス製造方法におい
て、液化天然ガス分留に必要な温熱源を、ボイルオフガ
ス再液化用の原料ボイルオフガスから確保し、ボイルオ
フガスを液化するために必要な冷熱源を、液化天然ガス
分留用の原料液化天然ガスから確保することを特徴とす
る都市ガス製造方法である。According to the present invention, liquefied natural gas as a main raw material is stored in an LNG tank, and the pressure is increased to a predetermined delivery pressure according to the demand of city gas in the city. In the city gas production method for performing liquefied natural gas fractionation for calorific value adjustment and re-liquefaction of boil-off gas generated from an LNG tank when the gas is delivered to the city as a gas, the heat required for liquefied natural gas fractionation City gas production characterized by securing a source from a raw material boil-off gas for re-liquefaction of boil-off gas and securing a cold heat source required for liquefying the boil-off gas from a raw material liquefied natural gas for liquefied natural gas fractionation Is the way.

【００１３】本発明に従えば、液化天然ガス分留とボイ
ルオフガス再液化とを併用し、液化天然ガス分留に必要
な温熱源としてボイルオフガスを利用し、ボイルオフガ
スを液化するための冷熱源として液化天然ガスを利用す
ることができる。天然ガスを分留するので、分留器の塔
底からの分留成分を都市ガスの原料として利用して、熱
量調整のために使用し、液化天然ガスに比較して高価な
液化石油ガスなどの使用量を減少させることができる。
ボイルオフガスを再液化する際には、冷却によって消費
電力量を削減することができる。According to the present invention, a liquefied natural gas fractionation and a re-liquefaction of a boil-off gas are used in combination, a boil-off gas is used as a heat source necessary for the liquefied natural gas fractionation, and a cold heat source for liquefying the boil-off gas. Liquefied natural gas can be used as Since natural gas is fractionated, the fractionated fraction from the bottom of the fractionator is used as a raw material for city gas, used for calorific value adjustment, and is more expensive than liquefied natural gas. Can be reduced.
When the boil-off gas is reliquefied, power consumption can be reduced by cooling.

【００１４】また本発明は、前記液化天然ガス分留に必
要な温熱源を、前記ボイルオフガス再液化用の原料ボイ
ルオフガスと熱交換器で熱の授受を行い、間接的に得る
ことを特徴とする。Further, the present invention is characterized in that a heat source required for fractionation of the liquefied natural gas is obtained indirectly by exchanging heat with a raw material boil-off gas for re-liquefaction of the boil-off gas using a heat exchanger. I do.

【００１５】本発明に従えば、再液化用の原料ボイルオ
フガスと液化天然ガス分留に使用する液化天然ガスと
は、熱交換器で間接的に熱の授受を行うので、ボイルオ
フガスの圧力を液化天然ガスと同程度まで気体の状態で
昇圧しておく必要はなく、電力消費を削減することがで
きる。According to the present invention, since the raw boil-off gas for reliquefaction and the liquefied natural gas used for liquefied natural gas fractionation exchange heat indirectly in a heat exchanger, the pressure of the boil-off gas is reduced. It is not necessary to increase the pressure in a gaseous state to the same level as liquefied natural gas, and power consumption can be reduced.

【００１６】また本発明の前記ボイルオフガス再液化で
は、都市ガスの需要量に応じて切換えることができるラ
インを設けて、都市ガスの需要量が多いときには吐出圧
力の低い圧縮機を備えるラインを用い、需要量が少ない
ときは吐出圧力が高い圧縮機を備えるラインを用いるこ
とを特徴とする。In the reliquefaction of the boil-off gas of the present invention, a line which can be switched in accordance with the demand of the city gas is provided, and a line having a compressor having a low discharge pressure is used when the demand of the city gas is large. When the demand is small, a line provided with a compressor having a high discharge pressure is used.

【００１７】本発明に従えば、前述の目的を達成するた
めに、ボイルオフガスを再液化するラインは都市ガスの
需要量に応じて切換えることができ、各ラインには吐出
圧力の異なる圧縮機を設置する。都市ガスの需要が多い
ときには吐出圧力の低い圧縮機で圧縮して、ボイルオフ
ガスに液化天然ガスから多量の冷熱を移行させ、再液化
の際の消費電力を大幅に削減することができる。都市ガ
スの需要が少ないときには吐出圧力の高い圧縮機で圧縮
して、気体状態での圧縮に伴う電力消費を削減すること
ができる。According to the present invention, in order to achieve the above object, the line for reliquefying the boil-off gas can be switched according to the demand of city gas, and each line is provided with a compressor having a different discharge pressure. Install. When the demand for city gas is high, the gas is compressed by a compressor having a low discharge pressure, a large amount of cold heat is transferred from the liquefied natural gas to the boil-off gas, and power consumption during reliquefaction can be significantly reduced. When the demand for city gas is small, the gas is compressed by a compressor having a high discharge pressure, so that the power consumption accompanying the compression in the gas state can be reduced.

【００１８】また前記吐出圧力が、前記高い圧縮機が
２．４［ＭＰａＧ］であり、前記低い圧縮機が７８０
［ｋＰａＧ］であれば、ボイルオフガスを圧縮して分留
に使用する液化天然ガスと熱交換する圧力を、都市ガス
需要量に合わせて切換えることができる。すなわち、都
市ガスの需要量が多いときは、７８０［ｋＰａＧ］程度
の低圧用圧縮機ラインにボイルオフガスを流し、３．９
［ＭＰａＧ］程度となる液化天然ガスよりも低い圧力で
液化を行う。このようにボイルオフガスを、液化天然ガ
スよりも大幅に低い圧力で液化することができるのは、
このとき、ボイルオフガス再液化用に液化天然ガスをボ
イルオフガスの約６倍の流量で使用し、液化天然ガスの
顕熱を利用することによるためである。The discharge pressure of the high compressor is 2.4 [MPaG], and the discharge pressure of the low compressor is 780 [MPaG].
With [kPaG], the pressure at which the boil-off gas is compressed and heat exchanged with the liquefied natural gas used for fractionation can be switched in accordance with the city gas demand. That is, when the demand amount of the city gas is large, the boil-off gas is caused to flow through the low-pressure compressor line of about 780 [kPaG], and 3.9 kPaG is supplied.
Liquefaction is performed at a pressure lower than that of liquefied natural gas of about [MPaG]. The reason that the boil-off gas can be liquefied at a significantly lower pressure than liquefied natural gas is as follows.
At this time, liquefied natural gas is used for re-liquefaction of the boil-off gas at a flow rate approximately six times that of the boil-off gas, and the sensible heat of the liquefied natural gas is used.

【００１９】また前記圧縮機後流のボイルオフガスを、
都市ガスの需要量に関係なく、前記液化天然ガス分留用
液化天然ガスと熱交換器で熱交換して完全に液化し、そ
の後ポンプによって３．９［ＭＰａＧ］の高圧まで昇圧
し、さらにその後、海水からの熱源によって気化すれ
ば、圧縮機の後流にはボイルオフガス再液化用の熱交換
器を設置し、さらにその後流には液化されたボイルオフ
ガスを昇圧するためのポンプが設置され、その後、海水
を熱源として液化されているボイルオフガスを気化す
る。ボイルオフガスは液化してから高圧まで昇圧するの
で、気体の状態での昇圧を低い範囲に留め、消費電力の
削減を図ることができる。The boil-off gas downstream of the compressor is
Irrespective of the demand of city gas, the liquefied natural gas for liquefied natural gas fractionation is completely liquefied by heat exchange with a heat exchanger, and then the pressure is increased to a high pressure of 3.9 [MPaG] by a pump. If vaporized by a heat source from seawater, a heat exchanger for boil-off gas reliquefaction will be installed downstream of the compressor, and a pump for boosting the liquefied boil-off gas will be installed downstream. The liquefied boil-off gas is vaporized using seawater as a heat source. Since the boil-off gas is liquefied and then pressurized to a high pressure, the pressure increase in a gaseous state can be kept in a low range, and power consumption can be reduced.

【００２０】また本発明は、前記液化天然ガス分留に使
用する液化天然ガスを、都市ガスの需要量に応じて流量
の設定を変えるようにして、ポンプへ送出することを特
徴とする。Further, the present invention is characterized in that the liquefied natural gas used for the fractionation of the liquefied natural gas is sent to a pump such that the setting of the flow rate is changed according to the demand of the city gas.

【００２１】本発明に従えば、都市ガスの需要量に応じ
て液化天然ガス分留に使用する液化天然ガスの流量設定
を変えるので、都市ガスの需要量に合わせて液化天然ガ
スを使用することができる。According to the present invention, the setting of the flow rate of liquefied natural gas used for liquefied natural gas fractionation is changed according to the demanded amount of city gas, so that liquefied natural gas is used in accordance with the demanded amount of city gas. Can be.

【００２２】また本発明は、前記ポンプ後流の液化天然
ガスを、都市ガスの需要量に応じて切換えることができ
るラインに導き、都市ガスの需要量が多い時には、液化
天然ガス熱交換器を熱交換するラインに流れ、需要量が
少ない時には、熱交換器をバイパスすることを特徴とす
る。Further, the present invention is also directed to a method in which liquefied natural gas downstream of the pump is led to a line which can be switched according to the demand of city gas. It is characterized in that it flows into a heat exchange line and bypasses the heat exchanger when the demand is small.

【００２３】本発明に従えば、都市ガスの需要量が多い
ときはボイルオフガスの液化量に比べ、分留用の液化天
然ガス量が多いため、分留するために必要な温度まで加
温されていない。そこでこの場合は、その後流に設置さ
れている切換用バルブを通して、分留に必要な温度まで
海水などから熱源を得て加温される。都市ガスの需要が
少ないときには、分留用の液化天然ガスは分留に必要な
温度まで昇温されているので、熱交換器をバイパスし、
熱交換器での海水等の使用量を削減することができる。According to the present invention, when the demand of city gas is large, the amount of liquefied natural gas for fractionation is large compared to the liquefied amount of boil-off gas, so that it is heated to a temperature required for fractionation. Absent. Therefore, in this case, a heat source is obtained from seawater or the like and heated to a temperature required for fractionation through a switching valve installed in the downstream stream. When the demand for city gas is low, the liquefied natural gas for fractionation is heated to the temperature required for fractionation, so bypassing the heat exchanger,
The amount of seawater used in the heat exchanger can be reduced.

【００２４】[0024]

【発明の実施の形態】図１は、本発明の実施の一形態と
しての都市ガス製造方法に従う都市ガス製造設備の概略
的な構成を示す。本実施形態では、ＬＮＧ分留とＢＯＧ
再液化とを併用する。この併用方法を用いると都市ガス
の需要量の変化に対応して従来よりも大幅に、ＢＯＧ高
圧送出のために必要となる電力量を削減することができ
る。以下、都市ガスの需要量が多いときと少ないときと
に分けて、本実施形態の概要を説明する。FIG. 1 shows a schematic configuration of a city gas production facility according to a city gas production method as one embodiment of the present invention. In the present embodiment, LNG fractionation and BOG
Use with reliquefaction. By using this combined method, it is possible to drastically reduce the amount of power required for high-pressure BOG transmission in response to changes in the demand for city gas. Hereinafter, the outline of the present embodiment will be described separately when the demand amount of the city gas is large and when it is small.

【００２５】本実施形態の都市ガス製造設備で、都市ガ
スの需要量が多いときは、ＢＯＧを再液化する際に必要
な冷熱源としてＬＮＧを多量に使用しても市中で消費さ
れるため、後述する都市ガスの需要量が少ないときに比
べて多くのＬＮＧを冷熱源として使用することができ
る。このＬＮＧを多量に使用することのメリットは、以
下に説明するように、ＢＯＧの圧縮圧力を低く抑えるこ
とができるという点である。In the city gas production facility of this embodiment, when the demand of city gas is large, even if a large amount of LNG is used as a cold heat source required for reliquefying BOG, it is consumed in the city. Thus, more LNG can be used as a cold heat source than when the demand for city gas described below is small. The advantage of using a large amount of LNG is that the compression pressure of the BOG can be kept low, as described below.

【００２６】都市ガスの原料となるＬＮＧは、ＬＮＧタ
ンク１０に貯蔵され、ＬＮＧ分留に必要な温度−１５６
［℃］、圧力３９．２［ｋＰａＧ］、流量２０３［ｔ／
ｈ］である状態Ｎ１で製造設備側に供給され、ＬＮＧポ
ンプ１１によって３．９［ＭＰａＧ］まで昇圧される。
昇圧されたＮ２の状態のＬＮＧは、ＬＮＧ／ＢＯＧ熱交
換器１２で温熱源からの熱を受取り、−１２１［℃］ま
で昇温されてＮ３の状態になる。ＬＮＧの流路に関し、
ＬＮＧ／ＢＯＧ熱交換器１２の後流側には、２系統のラ
インがバルブ２３，２４の開閉で切換可能に設けられて
いる。バルブ１３を開けてバルブ１４を閉じると、状態
Ｎ３のＬＮＧは、熱交換器１５に導かれる。熱交換器１
５には、ポンプ１６によって、熱交換の際に温熱源とな
る海水が送込まれる。熱交換器１５で、ＬＮＧは分留す
るのに必要な温度まで海水と熱交換することによって昇
温される。分流器１７では、気液平衡関係に基づき、塔
頂１７ａから標準状態の単位体積１ｍ3 当りで総発熱量
が約４０，６００［ｋＪ］となる状態Ｎ４の気体が流量
２２［ｔ／ｈ］で、塔底１７ｂからは総発熱量が約４
６，０００［ｋＪ ］となる状態Ｎ５の液体が流量４８
［ｔ／ｈ］となるように生成される。LNG, which is a raw material for city gas, is stored in an LNG tank 10 and has a temperature of -156 required for LNG fractionation.
[° C], pressure 39.2 [kPaG], flow rate 203 [t /
h], is supplied to the manufacturing facility side, and the pressure is increased to 3.9 [MPaG] by the LNG pump 11.
The pressurized LNG in the N2 state receives the heat from the heat source in the LNG / BOG heat exchanger 12, is heated to −121 [° C.], and becomes the N3 state. Regarding the flow path of LNG,
On the downstream side of the LNG / BOG heat exchanger 12, two lines are provided so as to be switchable by opening and closing the valves 23 and 24. When the valve 13 is opened and the valve 14 is closed, the LNG in the state N3 is led to the heat exchanger 15. Heat exchanger 1
5 is supplied with seawater as a heat source at the time of heat exchange by a pump 16. In the heat exchanger 15, LNG is heated by exchanging heat with seawater to a temperature required for fractionation. In the flow divider 17, based on the gas-liquid equilibrium relationship, the gas in the state N4 at which the total calorific value is about 40,600 [kJ] per unit volume of 1 m 3 in the standard state from the tower top 17 a is 22 [t / h]. The total calorific value from the tower bottom 17b is about 4
The flow rate of the liquid in the state N5 of 6,000 kJ is 48.
[T / h].

【００２７】次に、温度−１５５［℃］、圧力０［ｋＰ
ａＧ］、流量３４［ｔ／ｈ］の状態Ｎ１０のＢＯＧは、
バルブ２１，２２の開閉によって切換可能で、吐出圧力
が異なる２系統のラインに導入される。すなわち、バル
ブ２１の後流には低圧用の圧縮機２３が設けられ、バル
ブ２２の後流には高圧用の圧縮機２４が設けられる。バ
ルブ２１を開けてバルブ２２を閉じることによって、Ｂ
ＯＧは圧縮機２３に導かれ、７８４［ｋＰａＧ］（８
［ｋｇｆ／ｃｍ2 Ｇ］）まで昇圧される。昇圧されたＮ
１１の状態のＢＯＧは、ＬＮＧ／ＢＯＧ熱交換器１２で
Ｎ２の状態のＬＮＧを冷熱源として冷熱を受取り、液化
されてＮ１２の状態となる。Ｎ１２の状態の液体は、ポ
ンプ２５によって、３．９［ＭＰａＧ］まで昇圧され、
その後熱交換器２６で、ポンプ１６から熱交換器１５に
供給される途中の海水と熱交換することによって、Ｎ１
３の状態の気体になる。これまでに消費された電力量は
約３０１９［ｋＷ・ｈ］となる。その後Ｎ１３の状態の
気体は、ＬＰＧ等で熱量調整された後、都市ガスとして
市中へ送出される。Next, a temperature of -155 [° C] and a pressure of 0 [kP]
aG], the BOG in state N10 at a flow rate of 34 [t / h]
It can be switched by opening and closing valves 21 and 22 and is introduced into two lines with different discharge pressures. That is, a low-pressure compressor 23 is provided downstream of the valve 21, and a high-pressure compressor 24 is provided downstream of the valve 22. By opening valve 21 and closing valve 22, B
The OG is guided to the compressor 23, and 784 [kPaG] (8
[Kgf / cm 2 G]). Boosted N
The BOG in the state of 11 receives cold heat in the LNG / BOG heat exchanger 12 using the LNG in the state of N2 as a cold heat source, and is liquefied to the state of N12. The liquid in the state of N12 is pressurized to 3.9 [MPaG] by the pump 25,
Thereafter, the heat exchanger 26 exchanges heat with seawater being supplied from the pump 16 to the heat exchanger 15, thereby causing N1
It becomes gas in the state of 3. The amount of power consumed so far is about 3019 [kW · h]. Thereafter, the gas in the state of N13 is calorie-adjusted by LPG or the like, and then sent out to the city as city gas.

【００２８】本実施形態の都市ガス製造設備で、都市ガ
スの需要量が少ないときは、ＢＯＧを再液化する際に冷
熱源としてのＬＮＧを多量に必要としても、ＬＮＧが都
市ガスの原料としては市中で消費されないため、前述の
ような都市ガスの需要量の多いときのように、多くのＬ
ＮＧを冷熱源として使用することができない。このよう
にＬＮＧを多量に使用することができないことによっ
て、ＢＯＧの圧縮圧力を低く抑えることができないとい
う欠点がある。しかし、従来技術であるＢＯＧを直接圧
縮する場合に比べると、都市ガスとしての市中への送出
圧力よりも低い圧力でＢＯＧを送出することができ、以
下に説明するように、大幅に電力を削減することができ
る。In the city gas production facility of the present embodiment, when the demand of city gas is small, a large amount of LNG as a cold heat source is required when BOG is reliquefied, but LNG is not used as a source of city gas. Since it is not consumed in the city, as in the case of a large demand for city gas as described above, many L
NG cannot be used as a cold source. Since LNG cannot be used in a large amount as described above, there is a disadvantage that the compression pressure of BOG cannot be kept low. However, BOG can be sent at a pressure lower than the delivery pressure of city gas to the city as compared with the case of directly compressing BOG, which is a conventional technique, and as described below, power is greatly reduced. Can be reduced.

【００２９】ＬＮＧ分留に必要な温度−１５６［℃］、
圧力３９．２［ｋＰａＧ］、流量７０［ｔ／ｈ］の状態
Ｎ１で原料ＬＮＧは、ＬＮＧポンプ１１によって３．９
［ＭＰａＧ］まで昇圧される。注目すべきは、ＬＮＧの
流量の設定が変えられ、都市ガスの需要量が多いときよ
りも流量が減少してることである。昇圧されたＬＮＧ
は、Ｎ２の状態となり、ＬＮＧ／ＢＯＧ熱交換器１２で
温熱源となるＢＯＧから温熱を受取り、分留に必要な温
度−８０［℃］まで昇温されてＮ２４の状態となり、バ
ルブ１３を閉めてバルブ１４を開けることによって、熱
交換器１５をバイパスし、分留器１７に導かれる。ＬＮ
Ｇ／ＢＯＧ熱交換器１２で分留に必要な温度−８０
［℃］まで昇温されているからである。分流器１７で
は、気液平衡関係に基づき、標準状態で単位体積１ｍ3
当り、塔頂１７ａからは総発熱量が約４０，６００［ｋ
Ｊ］の状態Ｎ４の気体が流量２２［ｔ／ｈ］で、塔底１
７ｂからは約４６，０００［ｋＪ］の状態Ｎ５の液体が
流量４８［ｔ／ｈ］で、それぞれ生成される。Temperature required for LNG fractionation -156 [° C.]
In a state N1 at a pressure of 39.2 [kPaG] and a flow rate of 70 [t / h], the raw material LNG is 3.9 by the LNG pump 11.
The pressure is increased to [MPaG]. It should be noted that the setting of the flow rate of LNG is changed, and the flow rate is lower than when the demand amount of the city gas is large. Boosted LNG
Enters the state of N2, receives heat from the BOG serving as a heat source in the LNG / BOG heat exchanger 12, raises the temperature to −80 [° C.] necessary for fractionation, enters the state of N24, and closes the valve 13. By opening the valve 14, the heat exchanger 15 is bypassed and guided to the fractionator 17. LN
The temperature required for fractionation by the G / BOG heat exchanger 12 is -80.
This is because the temperature has been raised to [° C.]. In the flow divider 17, based on the gas-liquid equilibrium relationship, the unit volume is 1 m 3 in the standard state.
From the top 17a, the total calorific value is about 40,600 [k
J] in the state N4 at a flow rate of 22 [t / h],
7b, a liquid in a state N5 of about 46,000 [kJ] is generated at a flow rate of 48 [t / h].

【００３０】次に、温度−１５５［℃］、圧力０［ｋＰ
ａＧ］、流量３４［ｔ／ｈ］の状態Ｎ１０のＢＯＧは、
バルブ２１は閉じてバルブ２２を開けることによって、
圧縮機２４に導かれ、２．４５［ＭＰａＧ］（２５［ｋ
ｇｆ／ｃｍ2 Ｇ］）まで昇圧される。昇圧されたＢＯＧ
は、Ｎ２１の状態となり、ＬＮＧ／ＢＯＧ熱交換器１２
で冷熱源となるＬＮＧから冷熱を受取り、液化され、状
態Ｎ２２となる。状態Ｎ２２の液体は、ポンプ２５によ
って、３．９［ＭＰａＧ］まで昇圧され、その後熱交換
器２６によって海水と熱交換して、Ｎ１３の状態の気体
となる。これまでに消費された電力量は約４０６２［ｋ
Ｗ・ｈ］となる。その後Ｎ１３の状態の気体は、ＬＰＧ
等で熱量調整された後、都市ガスとして市中へ送出され
る。 本実施形態の都市ガス製造設備と、従来の都市ガ
ス製造設備とを比較すると、次の表１が得られる。Next, a temperature of -155 [° C] and a pressure of 0 [kP]
aG], the BOG in state N10 at a flow rate of 34 [t / h]
By closing the valve 21 and opening the valve 22,
It is guided to the compressor 24 and 2.45 [MPaG] (25 [k
gf / cm 2 G]). Boosted BOG
Is in the state of N21 and the LNG / BOG heat exchanger 12
Receives the cold heat from the LNG serving as a cold heat source, is liquefied, and becomes state N22. The liquid in the state N22 is pressurized to 3.9 [MPaG] by the pump 25, and then heat-exchanges with seawater by the heat exchanger 26 to become a gas in the state N13. The amount of power consumed so far is about 4062 [k
W · h]. After that, the gas in N13 state is LPG
After the calorific value is adjusted by the above method, it is sent out to the city as city gas. The following Table 1 is obtained by comparing the city gas production facility of the present embodiment with the conventional city gas production facility.

【００３１】[0031]

【表１】 [Table 1]

【００３２】本実施形態では、都市ガスの需要量が多い
ときはラインを切換え、ＬＮＧの流量を増量することに
よって、従来の直接ＢＯＧを圧縮する方法に比べて大幅
に電力量を削減することができる。また、都市ガスの需
要量が少ないときはラインを切換え、ＬＮＧの流量を減
量することによって、従来の直接ＢＯＧを圧縮する方法
に比べて大幅に電力量を削減することができる。さら
に、都市ガスの需要量が多いときはラインを切換え、Ｌ
ＮＧの流量を増量することによって、従来の直接ＢＯＧ
を圧縮する方法に比べて大幅に海水使用量を削減するこ
とができる。さらにまた、都市ガスの需要量が少ないと
きはラインを切換え、ＬＮＧの流量を減量することによ
って、従来の直接ＢＯＧを圧縮する方法に比べて大幅に
海水使用量を削減することができる。In this embodiment, when the demand of city gas is large, the line is switched and the flow rate of LNG is increased, so that the amount of power can be greatly reduced as compared with the conventional method of directly compressing BOG. it can. Further, when the demand of city gas is small, by switching the line and reducing the flow rate of LNG, the amount of power can be greatly reduced as compared with the conventional method of directly compressing BOG. Further, when the demand of city gas is large, the line is switched and L
By increasing the flow rate of NG, the conventional direct BOG
Seawater consumption can be significantly reduced as compared with the method of compressing seawater. Furthermore, when the demand of city gas is small, by switching the line and reducing the flow rate of LNG, the amount of seawater used can be greatly reduced as compared with the conventional method of directly compressing BOG.

【００３３】[0033]

【発明の効果】以上のように本発明によれば、液化天然
ガス分留とボイルオフガス再液化とを併用し、液化天然
ガス分留に必要な温熱源としてボイルオフガスを利用
し、ボイルオフガスを液化するための冷熱源として液化
天然ガスを利用して、熱量調整のために使用する液化石
油ガスなどの使用量を減少させ、消費電力量を削減する
こともできる。As described above, according to the present invention, the liquefied natural gas fractionation and the re-liquefaction of the boil-off gas are used in combination, and the boil-off gas is used as a heat source necessary for the fractionation of the liquefied natural gas. By using liquefied natural gas as a cold heat source for liquefaction, the amount of liquefied petroleum gas used for calorific value adjustment can be reduced, and power consumption can also be reduced.

【００３４】また本発明によれば、液化天然ガス分留に
必要な温熱源を、前記ボイルオフガス再液化用の原料ボ
イルオフガスから間接的に得るので、ボイルオフガスの
圧力を液化天然ガスと同程度まで気体の状態で昇圧して
おく必要はなく、電力消費を削減することができる。Further, according to the present invention, the heat source required for the fractionation of liquefied natural gas is obtained indirectly from the raw material boil-off gas for re-liquefying the boil-off gas. It is not necessary to increase the pressure in a gaseous state, and power consumption can be reduced.

【００３５】また本発明によれば、都市ガスの需要量に
応じてボイルオフガスを圧縮して分留に使用する液化天
然ガスと熱交換する圧力を切換え、需要が多いときには
吐出圧力の低い圧縮機で圧縮して、ボイルオフガスに液
化天然ガスから多量の冷熱を移行させ、再液化の際の消
費電力を大幅に削減することができる。都市ガスの需要
が少ないときには吐出圧力の高い圧縮機で圧縮して、気
体状態での圧縮に伴う電力消費を削減することができ
る。According to the present invention, the pressure at which the boil-off gas is compressed and heat exchanged with the liquefied natural gas used for fractionation is switched in accordance with the demand of the city gas, and the compressor having a low discharge pressure when the demand is large. To transfer a large amount of cold heat from the liquefied natural gas to the boil-off gas, thereby greatly reducing power consumption during reliquefaction. When the demand for city gas is small, the gas is compressed by a compressor having a high discharge pressure, so that the power consumption accompanying the compression in the gas state can be reduced.

【００３６】また、分留に使用する液化天然ガスと熱交
換するボイルオフガスの圧力を、都市ガスの需要量が多
いときは、７８０［ｋＰａＧ］程度の低圧用圧縮機ライ
ンに流すようにすれば、電力消費を削減することができ
る。Further, the pressure of the boil-off gas for heat exchange with the liquefied natural gas used for fractionation may be supplied to a low-pressure compressor line of about 780 [kPaG] when the demand of city gas is large. , Power consumption can be reduced.

【００３７】また、圧縮機の後流にはボイルオフガス再
液化用の熱交換器を設置し、さらにその後流には液化さ
れたボイルオフガスを昇圧するためのポンプを設置する
ようにすれば、ボイルオフガスは液化してから高圧まで
昇圧することができ、気体の状態での昇圧を低い範囲に
留め、消費電力の削減を図ることができる。A heat exchanger for boil-off gas reliquefaction is installed downstream of the compressor, and a pump for increasing the pressure of the liquefied boil-off gas is installed downstream of the compressor. After the gas is liquefied, the pressure can be increased to a high pressure, and the pressure increase in the gas state can be kept in a low range, and power consumption can be reduced.

【００３８】また本発明によれば、前記液化天然ガス分
留に使用する液化天然ガスの流量設定を変え、都市ガス
の需要量に合わせて液化天然ガスを使用することができ
る。Further, according to the present invention, the setting of the flow rate of the liquefied natural gas used for the fractionation of the liquefied natural gas can be changed so that the liquefied natural gas can be used according to the demand of the city gas.

【００３９】また本発明によれば、都市ガスの需要量が
多いときはボイルオフガスの液化量に比べ、分留用の液
化天然ガス量が多いため、分留に必要な温度まで海水な
どから熱源を得て加温することができる。都市ガスの需
要が少ないときには、分留用の液化天然ガスは分留に必
要な温度まで昇温されているので、熱交換器をバイパス
し、熱交換器での海水等の使用量を削減することができ
る。According to the present invention, when the demand of city gas is large, the amount of liquefied natural gas for fractionation is large compared to the liquefied amount of boil-off gas. Can be heated. When the demand for city gas is low, liquefied natural gas for fractionation is heated to the temperature required for fractionation, so bypass the heat exchanger and reduce the amount of seawater used in the heat exchanger. Can be.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明の実施の一形態の概略的な構成を示す配
管系統図である。FIG. 1 is a piping diagram showing a schematic configuration of an embodiment of the present invention.

【図２】従来からのＢＯＧ直接圧縮技術の概略的な構成
を示す配管系統図である。FIG. 2 is a piping diagram showing a schematic configuration of a conventional BOG direct compression technique.

【図３】従来からのＬＮＧ分留技術の概略的な構成を示
す配管系統図である。FIG. 3 is a piping diagram showing a schematic configuration of a conventional LNG fractionation technique.

【符号の説明】[Explanation of symbols]

１０ ＬＮＧタンク １１ ＬＮＧポンプ １２ ＬＮＧ／ＢＯＧ熱交換器 １３，１４，２１，２２ バルブ １５，２６ 熱交換器 １６，２５ ポンプ １７ 分留器 ２３，２４ 圧縮機 Reference Signs List 10 LNG tank 11 LNG pump 12 LNG / BOG heat exchanger 13, 14, 21, 22 Valve 15, 26 Heat exchanger 16, 25 Pump 17 Fractionator 23, 24 Compressor

───────────────────────────────────────────────────── フロントページの続き (72)発明者 田窪 稔 大阪府大阪市中央区平野町四丁目１番２号 大阪瓦斯株式会社内 Ｆターム(参考） 3E073 DD04  ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Minoru Takubo 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka Gas Co., Ltd. 3E073 DD04

Claims (5)

【特許請求の範囲】[Claims] 【請求項１】 主原料となる液化天然ガスをＬＮＧタン
クに貯蔵しておき、市中での都市ガスの需要量に応じて
予め定める送出圧力に昇圧し、都市ガスとして市中に送
出する際に、熱量調整のための液化天然ガス分留と、Ｌ
ＮＧタンクから発生するボイルオフガスの再液化とを行
う都市ガス製造方法において、 液化天然ガス分留に必要な温熱源を、ボイルオフガス再
液化用の原料ボイルオフガスから確保し、 ボイルオフガスを液化するために必要な冷熱源を、液化
天然ガス分留用の原料液化天然ガスから確保することを
特徴とする都市ガス製造方法。1. A liquefied natural gas, which is a main raw material, is stored in an LNG tank, and the pressure is increased to a predetermined delivery pressure in accordance with a demand amount of a city gas in the city, and is sent to the city as a city gas. Liquefied natural gas fractionation for calorific value adjustment, L
In a city gas production method for reliquefying boil-off gas generated from an NG tank, a heating source necessary for fractionation of liquefied natural gas is secured from a raw material boil-off gas for re-liquefaction of boil-off gas to liquefy the boil-off gas. A source of liquefied natural gas for the fractionation of liquefied natural gas from a source of liquefied natural gas. 【請求項２】 前記液化天然ガス分留に必要な温熱源
を、前記ボイルオフガス再液化用の原料ボイルオフガス
と熱交換器で熱の授受を行い、間接的に得ることを特徴
とする請求項１記載の都市ガス製造方法。2. A heat source required for the fractionation of liquefied natural gas is obtained indirectly by exchanging heat with a boil-off gas for boil-off gas re-liquefaction by a heat exchanger. 2. The method for producing city gas according to 1. 【請求項３】 前記ボイルオフガス再液化では、都市ガ
スの需要量に応じて切換えることができるラインを設け
て、都市ガスの需要量が少ないときには吐出圧力の高い
圧縮機を備えるラインを用い、需要量が多いときは吐出
圧力が低い圧縮機を備えるラインを用いることを特徴と
する請求項１または２記載の都市ガス製造方法。In the re-liquefaction of the boil-off gas, a line that can be switched according to the demand of the city gas is provided, and when the demand of the city gas is small, a line provided with a compressor having a high discharge pressure is used. 3. The method according to claim 1, wherein a line having a compressor having a low discharge pressure is used when the amount is large. 【請求項４】 前記液化天然ガス分留に使用する液化天
然ガスを、都市ガスの需要量に応じて流量の設定を変え
るようにして、ポンプへ送出することを特徴とする請求
項１〜３のいずれかに記載の都市ガス製造方法。4. The liquefied natural gas used for fractionating the liquefied natural gas is sent to a pump so that the flow rate is changed according to the demand of the city gas. The method for producing city gas according to any one of the above. 【請求項５】 前記ポンプ後流の液化天然ガスを、都市
ガスの需要量に応じて切換えることができるラインに導
き、都市ガスの需要量が多い時には、液化天然ガス熱交
換器を熱交換するラインに流れ、需要量が少ない時に
は、熱交換器をバイパスすることを特徴とする請求項１
記載の都市ガス製造方法。5. The liquefied natural gas downstream of the pump is led to a line that can be switched according to the demand for city gas, and when the demand for city gas is high, the liquefied natural gas heat exchanger is heat-exchanged. 2. The heat exchanger according to claim 1, wherein the heat exchanger is bypassed when flowing into the line and the amount of demand is small.
The city gas production method described.
JP2000095658A 2000-03-30 2000-03-30 City gas production method Expired - Fee Related JP4064037B2 (en)

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