JPS6255040B2 - - Google Patents
Info
- Publication number
- JPS6255040B2 JPS6255040B2 JP14969180A JP14969180A JPS6255040B2 JP S6255040 B2 JPS6255040 B2 JP S6255040B2 JP 14969180 A JP14969180 A JP 14969180A JP 14969180 A JP14969180 A JP 14969180A JP S6255040 B2 JPS6255040 B2 JP S6255040B2
- Authority
- JP
- Japan
- Prior art keywords
- natural gas
- liquefied natural
- pressure
- liquefied
- regeneration
- 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.)
- Expired
Links
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 86
- 239000003949 liquefied natural gas Substances 0.000 claims description 69
- 239000003345 natural gas Substances 0.000 claims description 43
- 230000008016 vaporization Effects 0.000 claims description 34
- 238000000034 method Methods 0.000 claims description 29
- 238000009834 vaporization Methods 0.000 claims description 25
- 230000008929 regeneration Effects 0.000 description 40
- 238000011069 regeneration method Methods 0.000 description 40
- 230000000052 comparative effect Effects 0.000 description 7
- 238000010248 power generation Methods 0.000 description 7
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical group CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 6
- 238000011084 recovery Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000009833 condensation Methods 0.000 description 4
- 230000005494 condensation Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 230000008020 evaporation Effects 0.000 description 4
- 238000001704 evaporation Methods 0.000 description 4
- 239000006200 vaporizer Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 239000002737 fuel gas Substances 0.000 description 3
- 239000001294 propane Substances 0.000 description 3
- 239000013535 sea water Substances 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C9/00—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure
- F17C9/02—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure with change of state, e.g. vaporisation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2221/00—Handled fluid, in particular type of fluid
- F17C2221/03—Mixtures
- F17C2221/032—Hydrocarbons
- F17C2221/033—Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
- F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
- F17C2223/0146—Two-phase
- F17C2223/0153—Liquefied gas, e.g. LPG, GPL
- F17C2223/0161—Liquefied gas, e.g. LPG, GPL cryogenic, e.g. LNG, GNL, PLNG
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2225/00—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel
- F17C2225/01—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel characterised by the phase
- F17C2225/0107—Single phase
- F17C2225/0123—Single phase gaseous, e.g. CNG, GNC
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
- F17C2227/01—Propulsion of the fluid
- F17C2227/0128—Propulsion of the fluid with pumps or compressors
- F17C2227/0135—Pumps
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
Description
（産業上の利用分野）
本発明は液化天然ガスの気化方法に関し、更に
詳しくは、液化天然ガスを昇圧および気化せし
め、その昇圧圧力と略等しい天然ガスを燃料ガス
として系外へ送出する気化系統に、最適の動力回
収方法を付加した液化天然ガスの気化方法に関す
るものである。
（従来の技術）
液化天然ガスを気化させるに際して産出地で天
然ガスを液化させるに要した動力を回収する、い
わゆるLNG冷熱利用方法としては、液化窒素、
液体酸素等の製造の如く他の気体の液化、冷凍倉
庫、食品の冷凍、冷熱発電など種々提案されてい
る。これらのうち、大量の液化天然ガス
（LNG）を安定的に処理すること、下流側（火力
発電所、都市ガス）の負荷変動に対して充分な対
応が可能であること、冷熱により生産される商品
に新たな流通ルートや需要確保が要求されないこ
と等、冷熱利用のための望ましい条件を考慮する
と液化天然ガスの冷熱発電が実現性の高い有効な
手段の一つといえる。
従来、液化天然ガスの気化プロセスに冷熱発電
を適用した方法として、例えば、特開昭51−
42704号公報に記載のように、液化天然ガスを昇
圧して直列接続された複数の熱交換器で昇温、気
化、降圧させ、所望の温度、圧力の天然ガスを得
るにあたり、各熱交換器から出る天然ガスを次の
熱交換器に入る前に発電用膨張タービンに供給し
てタービンを駆動させるようにした気化方法が提
案されている。
（発明が解決しようとする問題点）
しかしながら、気化系統に直接発電用膨張ター
ビンを配設した場合、タービンの出口側の圧力を
低くしなければ、発電設備の有効出力を大きくで
きず、従つて、液化天然ガスの昇圧圧力と略等し
い圧力の天然ガスを燃料ガスとして系外に送出す
ることを要求される気化系統には適用できないと
いう問題がある。
従つて、本発明はこの冷熱発電を液化天然ガス
の気化プロセス、特に、液化天然ガスを例えば
50ataの高圧に昇圧して気化せしめ、50ataの高圧
天然ガスとして系外へ送出するごとき、気化設備
における入側液化天然ガスと出側天然ガスの圧力
の略等しい気化プロセスへ適用するに際し、動力
回収効率が最もよく、簡便なプロセスを提供せん
とするものである。
（問題点を解決するための手段）
本発明は、前記問題を解決する手段として、液
化天然ガスを昇圧させた後、気化せしめ、昇圧圧
力と略等しい圧力の天然ガスとして系外へ送出す
る気化方法であつて、気化した天然ガスの一部を
膨張タービンに供給し、これを駆動させて動力回
収を行なうと共に自らは断熱膨張させ、次いで液
化天然ガス気化系統の液化天然ガス流路に設けた
再生器により液化天然ガスと熱交換させて再液化
し、昇圧させた後前記再生器の入口側の液化天然
ガス流路に帰還させることを特徴とする液化天然
ガスの気化方法、をその要旨とするものである。
液化天然ガス冷熱の利用をさらに向上させるた
め、液化天然ガス気化系統の液化天然ガス流路に
熱交換器を配設し、この熱交換器を介して液化天
然ガスの冷熱により二次媒体を液化し、これを昇
圧後、気化させて他の膨張タービンを駆動させる
二次媒体サイクル系統を設けるようにしてもよ
い。
（作用）
前記構成の液化天然ガスの気化方法において
は、液化天然ガスは昇圧された後、気化され、昇
圧した圧力と略等しい圧力の天然ガスとして系外
へ送出されるが、本発明は系外へ天然ガスを送出
する天然ガス流路から天然ガスの一部を取り出
し、これを膨張タービンに供給して膨張タービン
を駆動することによつて、膨張タービンの出口側
の圧力を、天然ガス流路から系外に送出される天
然ガスの圧力とは無関係に任意に設定できるよう
にし、有効出力を大きくすることを可能にしてい
る。
また、膨張タービンで断熱膨張した天然ガス
は、気化系統を流れる液化天然ガスと再生器で熱
交換し、液化天然ガスを昇温、気化させる一方、
自らは、再液化したのち、昇圧して再生器の入口
側の液化天然ガス流路に帰還されるが、再液化し
た天然ガスを再生器の入口側の液化天然ガス流路
に帰還させることによつて、気化系統を流れる全
天然ガスに対する再生サイクル系統を流れる天然
ガスの比（再生比）を大きくし、大きな有効出力
を得ることを可能にしている。
以下、本発明方法の実施に使用する液化天然ガ
ス気化装置におけるフローシートを示す図面を参
照して説明する。
（実施例）
第１図の装置は、液化天然ガス貯蔵タンク１か
らポンプ２にて抽出して昇圧し、これをオープン
ラツクベーパライザなどの熱交換器３で海水など
と熱交換させて気化し、この天然ガスを系外へ燃
料ガスとして送出する気化系統に加え、系外への
天然ガス流路４を２分し、天然ガスの一部を膨張
タービン５に供給してこれを駆動して該膨張ター
ビン５に連結された発電機Ｇにより発電して液化
天然ガスの持つエクセルギー（最大有効仕事）を
回収し、天然ガス自らは断熱膨張した後、気化系
統の液化天然ガス流路６ａ，６ｂに設けた再生器
７にて液化天然ガスと熱交換して該液化天然ガス
を昇温、気化させる一方、自らは再液化し、この
再液化させた天然ガスをポンプ８により昇圧して
再生器７の入口側の液化天然ガス流路６ａに帰還
させる再生サイクル系統とから構成されている。
上記装置を用いて、液化天然ガスを気化させる
場合、ポンプ２にて、例えば、50ataまで液化天
然ガスを昇圧させ、これを気化器３にて海水と熱
交換させて昇温、例えば−160℃から＋10℃程度
にまで温度を高め、系外へ送出する天然ガスと再
生サイクル系統に供給される天然ガスとに流路９
ａ，９ｂにより二分され、流路９ａを通る天然ガ
スはそのまま直接高圧、例えば、約50ataで系外
へ送出され、流路９ｂを通る天然ガスは膨張ター
ビン５にて外部仕事をして減圧、温度低下した
後、再生器７へ流入し、そこでタンク１からの液
化天然ガスと熱交換して再液化し、ポンプ８にて
50ata以上に昇圧されて再生器７の入口側の液化
天然ガス流路６ａに帰還され、再び気化系統を流
動する。この気化系統を流れる全天然ガスに対す
る再生サイクル系統を流れる天然ガスの比、すな
わち、再生比は系外へ送出する天然ガスの量、圧
力等に応じて適宜設定されるが、エクセルギー回
収効率を高めるため、通常0.3〜0.5の範囲に設定
される。
第２図は本発明方法の実施に使用する装置の他
の実施例のフローシートを示し、第１図の装置の
構成に加えて、二次媒体、例えば、プロパンを液
化天然ガスと熱交換させて凝縮させる凝縮器１１
と、凝縮した二次媒体を昇圧させるポンプ１２
と、昇圧した二次媒体を海水等と熱交換させて気
化するオープンラツクベーパライザなどの熱交換
器１３と、気化した二次媒体で駆動され発電機
G2を作動させる膨張タービン１４とからなる二
次媒体ランキンサイクル系統を有している。この
二次媒体ランキンサイクル系統を設けることによ
り液化天然ガスの冷熱をさらに有効に利用するこ
とができる。
上記本発明方法によれば、液化天然ガスを気化
して外部へ天然ガスとして送出するばかりでな
く、液化天然ガスのエクセルギーを回収すること
ができ、しかも、再生サイクル系統の圧力を送出
天然ガス圧力と無関係に最適化することができ
る。
なお、第３図に比較例として示す液化天然ガス
気化装置のように、再生器７で再液化した液化天
然ガスを再生器７の出口側の液化天然ガス流路６
ｂに帰還させることも考えられるが。この場合、
再生比を高くとることができないため、本発明方
法の場合に較べエクセルギー効率が著しく低下す
るので好ましくない。
即ち、再生器で再液化した液化天然ガスを再生
器の入口側に帰還させる場合と、再生器の出口側
に帰還させる場合において、再生器の温度と交換
熱量との関係、すなわち、再生器内での液化天然
ガスの蒸発カーブとの再生天然ガスの凝縮カーブ
を示すと第４図の通りである。
同図から明らかなように、再液化した液化天然
ガスを再生器の出口側に帰還させる場合、再生器
内での液化天然ガスの蒸発カーブは再生比に関係
なく一定で、再生天然ガスの凝縮カーブは破線で
示すように再生比に応じて変化する。しかし、再
生比を大きくしていくと、再生比0.5で蒸発カー
ブと凝縮カーブが接触する、即ち、二流体間の温
度差△ｔが０となるため、それ以上、再生比を大
きくすることはできない。
これに対し、再液化した天然ガスを再生器の入
口側に帰還させた場合、再生天然ガスの凝縮カー
ブが再生比に応じて変化することは前記の場合と
同じであるが、蒸発カーブは一定ではなく、再生
比に応じて傾きが緩やかとなり、再生比が0.5で
も二流体間の温度差△ｔはなお３℃程度とること
ができる。これは、同等の伝熱面積を有する再生
器において、同じ温度差△ｔを取るためには、再
液化した天然ガスを再生器の入口側に帰還させる
場合の方が大きな再生比を取ることができること
を意味し、再生比と再生サイクル系統における出
力とは比例関係にあるので、再液化した天然ガス
を再液器の入口側に帰還させる場合の方がより大
きな出力を得ることができる。
従つて、二次媒体サイクルを除外した再生付気
化系統においては再生比が大きければ大きいほ
ど、すなわち、比較例の方法よりも本発明方法の
方が高出力が得られる。一方、二次媒体ランキン
サイクルを考慮した場合を考えると、この場合も
再生サイクルの出力については上記の説明がその
ままあてはまるので、ここでは二次媒体ランキン
サイクルの出力について考える。
二次媒体ランキンサイクルにおける媒体凝縮器
の液化天然ガスの入口温度は比較例、本発明方法
を問わず再生比のみにより決まる。
再生サイクルにおける出力の説明で述べたよう
に再生サイクルに対しては再生比が大きいほど出
力が大である。ところが再生比が大きくなると二
次媒体凝縮器への液化天然ガス入口温度が高くな
る。すなわち、二次媒体ランキンサイクルにて利
用できるエクセルギーが減少し出力が低下する。
したがつて、再生付LNG気化系統＋二次媒体ラ
ンキンサイクル方式においては、再生サイクルに
よる出力増加は二次媒体ランキンサイクルにおけ
る出力減少につながり、その又逆も成り立つ。し
たがつて、再生サイクルによる出力増加をねらう
か、二次媒体ランキンサイクルにおける出力増加
をねらうかいずれがより有効かを判断する事が必
要である。しかし、二次媒体ランキンサイクルに
おいて回収できる最大のエクセルギーは二次媒体
をプロパンとしたとき、凝縮温度−40℃から仕事
後の温度10℃の範囲に制限されるため、常にプロ
パンサイクルでの出力増加分が再生サイクルでの
出力減少分を上回ることはない。これはプロパン
ランキンサイクルが−40℃以上の温度範囲しかエ
クセルギーを回収できないのに対し、再生サイク
ル側では−124.5℃以上の広い温度範囲でエクセ
ルギーを回収できるからである。すなわち、エク
セルギー回収はより広い温度範囲で利用できるラ
ンキンサイクルにて行うことがより効果的であ
る。
結局、再生付気化系統＋二次媒体ランキンサイ
クル方式においては、再生サイクルすなわち
LNGランキンサイクルで出力を得る方向、つま
り再生比をできるだけ高くできる方法が望まし
く、本発明方法が比較例より高い出力が得られる
方法であることがわかる。
実施例
液化天然ガス貯蔵タンク１からポンプ２により
送出する液化天然ガスの供給量を100tom／hr、
その温度を−160℃、供給圧力50ataとし、装置外
部への天然ガスの送出温度＋10℃、供給圧力
48.0ataの条件下で、第２図の装置を用いて発電
した。その結果を再生サイクル系統の動作条件と
共に第１表に示す。
比較例
第３図の装置を用いた実施例１と同じ機器を用
いて発電した。その結果も第１表に示す。なお、
第３図の装置の再生サイクル系統の動作条件は二
次媒体サイクルにおける出力と再生サイクル系統
における出力との和が最大となるように設定し
た。
(Industrial Application Field) The present invention relates to a method for vaporizing liquefied natural gas, and more specifically to a vaporization system that boosts the pressure of liquefied natural gas, vaporizes it, and sends natural gas that is approximately equal to the boosted pressure to the outside of the system as fuel gas. The present invention also relates to a method for vaporizing liquefied natural gas that includes an optimal power recovery method. (Prior art) As a so-called LNG cold energy utilization method, which recovers the power required to liquefy natural gas at the production site when vaporizing liquefied natural gas, liquefied nitrogen, liquefied nitrogen,
Various proposals have been made, including the production of liquid oxygen, liquefaction of other gases, cold storage, food freezing, and cold energy power generation. Among these, it is necessary to stably process large amounts of liquefied natural gas (LNG), be able to adequately respond to load fluctuations on the downstream side (thermal power plants, city gas), and produce using cold heat. Considering the desirable conditions for using cold energy, such as not requiring new distribution routes or securing demand for the product, cold energy power generation using liquefied natural gas can be said to be one of the highly feasible and effective means. Conventionally, as a method of applying cold power generation to the vaporization process of liquefied natural gas, for example,
As described in Publication No. 42704, liquefied natural gas is pressurized and then heated, vaporized, and pressure lowered using multiple heat exchangers connected in series to obtain natural gas at a desired temperature and pressure. A vaporization method has been proposed in which the natural gas emitted from the engine is supplied to an expansion turbine for power generation to drive the turbine before entering the next heat exchanger. (Problem to be Solved by the Invention) However, when an expansion turbine for power generation is installed directly in the vaporization system, the effective output of the power generation equipment cannot be increased unless the pressure on the outlet side of the turbine is lowered. However, there is a problem in that it cannot be applied to a vaporization system that requires sending natural gas at a pressure substantially equal to the boosted pressure of liquefied natural gas to the outside of the system as fuel gas. Therefore, the present invention utilizes this cold thermal power generation in the process of vaporizing liquefied natural gas, particularly in the process of vaporizing liquefied natural gas, e.g.
When applied to a vaporization process in which the pressure of the inlet liquefied natural gas and the outlet natural gas in the vaporization equipment are approximately equal, such as increasing the pressure to a high pressure of 50 ata, vaporizing it, and sending it out of the system as high-pressure natural gas of 50 ata, power recovery is required. The aim is to provide the most efficient and simple process. (Means for Solving the Problems) As a means for solving the above problems, the present invention provides vaporization that increases the pressure of liquefied natural gas, then vaporizes it and sends it out of the system as natural gas with a pressure substantially equal to the boosted pressure. In this method, part of the vaporized natural gas is supplied to an expansion turbine, which is driven to recover power and expands itself adiabatically, and then installed in the liquefied natural gas flow path of the liquefied natural gas vaporization system. The gist thereof is a method for vaporizing liquefied natural gas, which is characterized in that the liquefied natural gas is re-liquefied by heat exchange with the liquefied natural gas in a regenerator, the pressure is increased, and then the liquefied natural gas is returned to the liquefied natural gas flow path on the inlet side of the regenerator. It is something to do. In order to further improve the use of liquefied natural gas cold energy, a heat exchanger is installed in the liquefied natural gas flow path of the liquefied natural gas vaporization system, and the secondary medium is liquefied by the cold energy of liquefied natural gas through this heat exchanger. However, a secondary medium cycle system may be provided for boosting the pressure and vaporizing it to drive another expansion turbine. (Function) In the method for vaporizing liquefied natural gas having the above configuration, the liquefied natural gas is pressurized, then vaporized, and sent out of the system as natural gas having a pressure substantially equal to the pressure increased. By extracting a portion of the natural gas from the natural gas flow path that sends the natural gas outside and supplying it to the expansion turbine to drive the expansion turbine, the pressure on the outlet side of the expansion turbine can be adjusted to the natural gas flow. This allows the pressure to be set arbitrarily regardless of the pressure of the natural gas sent out of the system from the pipe, making it possible to increase the effective output. In addition, the natural gas adiabatically expanded in the expansion turbine exchanges heat with the liquefied natural gas flowing through the vaporization system in the regenerator, raising the temperature of the liquefied natural gas and vaporizing it.
After being reliquefied, the natural gas is pressurized and returned to the liquefied natural gas flow path on the inlet side of the regenerator. Therefore, the ratio (regeneration ratio) of the natural gas flowing through the regeneration cycle system to the total natural gas flowing through the vaporization system is increased, making it possible to obtain a large effective output. DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the method of the present invention will be explained with reference to the drawings showing a flow sheet of a liquefied natural gas vaporization apparatus used for carrying out the method of the present invention. (Example) The device shown in Fig. 1 extracts liquefied natural gas from a storage tank 1 using a pump 2, increases the pressure, and vaporizes it by exchanging heat with seawater or the like using a heat exchanger 3 such as an open rack vaporizer. In addition to the vaporization system that sends this natural gas out of the system as fuel gas, the natural gas flow path 4 to the outside of the system is divided into two, and a part of the natural gas is supplied to an expansion turbine 5 to drive it. The generator G connected to the expansion turbine 5 generates electricity to recover the exergy (maximum effective work) of the liquefied natural gas, and after the natural gas itself expands adiabatically, the liquefied natural gas flow path 6a of the vaporization system, The regenerator 7 installed in 6b exchanges heat with the liquefied natural gas to raise the temperature and vaporize the liquefied natural gas, while the natural gas itself is reliquefied, and the reliquefied natural gas is pressurized by the pump 8 and regenerated. It is composed of a regeneration cycle system that returns the liquefied natural gas to the liquefied natural gas flow path 6a on the inlet side of the vessel 7. When liquefied natural gas is vaporized using the above device, the pressure of the liquefied natural gas is increased to, for example, 50 ata using the pump 2, and the temperature is increased by exchanging heat with seawater in the vaporizer 3, e.g. -160°C. A flow path 9 is established between the natural gas to be heated to around +10°C and sent out of the system and the natural gas supplied to the regeneration cycle system.
The natural gas passing through the flow path 9a is directly sent out of the system at a high pressure, for example, about 50 ata, and the natural gas passing through the flow path 9b is subjected to external work in the expansion turbine 5 to reduce the pressure. After the temperature drops, it flows into the regenerator 7, where it exchanges heat with the liquefied natural gas from the tank 1 to re-liquefy it, and is pumped to the pump 8.
The liquefied natural gas is pressurized to 50 ata or more and returned to the liquefied natural gas flow path 6a on the inlet side of the regenerator 7, and flows through the vaporization system again. The ratio of the natural gas flowing through the regeneration cycle system to the total natural gas flowing through the vaporization system, that is, the regeneration ratio, is set as appropriate depending on the amount and pressure of natural gas sent outside the system, but the exergy recovery efficiency It is usually set in the range of 0.3 to 0.5 to increase the FIG. 2 shows a flow sheet of another embodiment of the apparatus used to carry out the process of the invention, which in addition to the configuration of the apparatus of FIG. condenser 11
and a pump 12 that boosts the pressure of the condensed secondary medium.
, a heat exchanger 13 such as an open rack vaporizer that vaporizes the pressurized secondary medium by exchanging heat with seawater, etc., and a generator driven by the vaporized secondary medium.
It has a secondary medium Rankine cycle system consisting of an expansion turbine 14 that operates G2 . By providing this secondary medium Rankine cycle system, the cold energy of liquefied natural gas can be used more effectively. According to the method of the present invention, it is possible not only to vaporize liquefied natural gas and send it outside as natural gas, but also to recover the exergy of the liquefied natural gas. Can be optimized independently of pressure. Note that, as in the liquefied natural gas vaporization apparatus shown as a comparative example in FIG.
It is also possible to return to b. in this case,
Since a high regeneration ratio cannot be achieved, the exergy efficiency is significantly lower than in the method of the present invention, which is not preferable. In other words, the relationship between the temperature of the regenerator and the amount of heat exchanged is Figure 4 shows the evaporation curve of liquefied natural gas and the condensation curve of recycled natural gas. As is clear from the figure, when the re-liquefied liquefied natural gas is returned to the outlet side of the regenerator, the evaporation curve of the liquefied natural gas in the regenerator is constant regardless of the regeneration ratio, and the condensation of the regenerated natural gas The curve changes depending on the reproduction ratio as shown by the broken line. However, as the regeneration ratio is increased, the evaporation curve and condensation curve touch each other at the regeneration ratio of 0.5, that is, the temperature difference △t between the two fluids becomes 0, so it is impossible to increase the regeneration ratio any further. Can not. On the other hand, when reliquefied natural gas is returned to the inlet side of the regenerator, the condensation curve of the regenerated natural gas changes depending on the regeneration ratio, as in the previous case, but the evaporation curve remains constant. Rather, the slope becomes gentle depending on the regeneration ratio, and even if the regeneration ratio is 0.5, the temperature difference Δt between the two fluids can still be about 3°C. This means that in order to obtain the same temperature difference Δt in regenerators with the same heat transfer area, a larger regeneration ratio must be achieved when reliquefied natural gas is returned to the inlet side of the regenerator. Since there is a proportional relationship between the regeneration ratio and the output in the regeneration cycle system, a larger output can be obtained when reliquefied natural gas is returned to the inlet side of the reliquefier. Therefore, in the regeneration vaporization system excluding the secondary medium cycle, the larger the regeneration ratio, that is, the higher the output can be obtained with the method of the present invention than with the method of the comparative example. On the other hand, considering the case where the secondary medium Rankine cycle is considered, the above explanation also applies to the output of the reproduction cycle in this case as well, so here, the output of the secondary medium Rankine cycle will be considered. The inlet temperature of the liquefied natural gas in the medium condenser in the secondary medium Rankine cycle is determined only by the regeneration ratio, regardless of the comparative example or the method of the present invention. As described in the explanation of the output in the regeneration cycle, the larger the regeneration ratio, the greater the output in the regeneration cycle. However, as the regeneration ratio increases, the temperature of the liquefied natural gas inlet to the secondary medium condenser increases. That is, the exergy available in the secondary medium Rankine cycle decreases, resulting in a decrease in output.
Therefore, in the LNG vaporization system with regeneration + secondary medium Rankine cycle system, an increase in output due to the regeneration cycle leads to a decrease in output in the secondary medium Rankine cycle, and vice versa. Therefore, it is necessary to judge which is more effective: aiming to increase the output through the regeneration cycle or increasing the output during the secondary medium Rankine cycle. However, the maximum exergy that can be recovered in the secondary medium Rankine cycle is limited to the range from the condensing temperature of -40°C to the post-work temperature of 10°C when the secondary medium is propane, so the output in the propane cycle is always The increase will not exceed the power decrease during the regeneration cycle. This is because the propane Rankine cycle can only recover exergy over a temperature range of -40°C or higher, whereas the regeneration cycle can recover exergy over a wide temperature range of -124.5°C or higher. That is, it is more effective to perform exergy recovery using the Rankine cycle, which can be used over a wider temperature range. In the end, in the vaporization system with regeneration + secondary medium Rankine cycle system, the regeneration cycle, i.e.
It is desirable to obtain output using the LNG Rankine cycle, that is, to increase the regeneration ratio as much as possible, and it can be seen that the method of the present invention is a method that can obtain higher output than the comparative example. Example: The supply amount of liquefied natural gas sent from the liquefied natural gas storage tank 1 by the pump 2 is 100 tom/hr,
The temperature is -160℃ and the supply pressure is 50ata, and the natural gas delivery temperature to the outside of the equipment is +10℃ and the supply pressure.
Power was generated using the equipment shown in Figure 2 under conditions of 48.0ata. The results are shown in Table 1 along with the operating conditions of the regeneration cycle system. Comparative Example Power was generated using the same equipment as in Example 1 using the apparatus shown in FIG. The results are also shown in Table 1. In addition,
The operating conditions of the regeneration cycle system of the apparatus shown in FIG. 3 were set so that the sum of the output in the secondary medium cycle and the output in the regeneration cycle system was maximized.
【表】【table】
【表】
第１表からわかるように、本発明方法によれ
ば、比較例よりも再生比を大きくでき、高いエク
セルギー回収効率を得ることができる。
（発明の効果）
以上の説明から明らかなように、本発明方法に
よれば、再生サイクルを気化系統に付加すること
により液化天然ガスを気化し、天然ガスとして送
出する以外にそのエクセルギーを効率よく回収す
ることができる。また、再生サイクルを再生器の
入口側（低温側）に戻すことにより、同じ再生シ
ステムでも再生器の出口側（高温側）に戻す場合
よりも約15％の電力出力増加を得ることができる
など優れた効果が得られる。[Table] As can be seen from Table 1, according to the method of the present invention, the regeneration ratio can be made larger than in the comparative example, and high exergy recovery efficiency can be obtained. (Effects of the Invention) As is clear from the above explanation, according to the method of the present invention, liquefied natural gas is vaporized by adding a regeneration cycle to the vaporization system, and its exergy can be efficiently utilized in addition to being sent out as natural gas. Can be easily recovered. In addition, by returning the regeneration cycle to the inlet side (low temperature side) of the regenerator, it is possible to obtain an approximately 15% increase in power output than when returning the regeneration cycle to the outlet side (high temperature side) of the regenerator with the same regeneration system. Excellent effects can be obtained.
第１図は本発明方法の実施に使用する液化天然
ガス気化装置の一実施例を示す系統図、第２図は
他の実施例を示す系統図、第３図は比較例のフロ
ーシートを示す系統図、第４図は再生器における
温度と交換熱量の関係を示すグラフである。
１〜タンク、２〜ポンプ、３〜気化器、５〜膨
張タービン、６ａ，６ｂ〜液化天然ガス流路、７
〜再生器、８〜ポンプ。
Fig. 1 is a system diagram showing one embodiment of a liquefied natural gas vaporization device used to carry out the method of the present invention, Fig. 2 is a system diagram showing another embodiment, and Fig. 3 is a flow sheet of a comparative example. The system diagram, FIG. 4, is a graph showing the relationship between the temperature and the amount of heat exchanged in the regenerator. 1 - tank, 2 - pump, 3 - vaporizer, 5 - expansion turbine, 6a, 6b - liquefied natural gas flow path, 7
~Regenerator, 8~Pump.
Claims (1)
圧圧力と略等しい圧力の天然ガスとして系外へ送
出する気化方法であつて、気化した天然ガスの一
部を膨張タービンに供給し、これを駆動させて動
力回収を行なうと共に自らは断熱膨張させ、次い
で液化天然ガス気化系統の液化天然ガス流路に設
けた再生器により液化天然ガスと熱交換させて再
液化し、昇圧させた後前記再生器の入口側の液化
天然ガス流路に帰還させることを特徴とする液化
天然ガスの気化方法。 ２ 液化天然ガス流路に設けられた凝縮器により
二次媒体を液化天然ガスと熱交換させて液化し、
これを昇圧後気化させて膨張タービンを駆動し動
力回収を行なう特許請求の範囲第１項記載の方
法。[Claims] 1. A vaporization method in which liquefied natural gas is pressurized, then vaporized, and sent out of the system as natural gas at a pressure substantially equal to the boosted pressure, in which a portion of the vaporized natural gas is sent to an expansion turbine. The liquefied natural gas is then driven to recover power, expand itself adiabatically, and then exchange heat with the liquefied natural gas in a regenerator installed in the liquefied natural gas flow path of the liquefied natural gas vaporization system to re-liquefy and boost the pressure. A method for vaporizing liquefied natural gas, which comprises returning the liquefied natural gas to the liquefied natural gas flow path on the inlet side of the regenerator. 2 The secondary medium is liquefied by exchanging heat with the liquefied natural gas using a condenser installed in the liquefied natural gas flow path,
2. The method according to claim 1, wherein the pressure is increased and then vaporized to drive an expansion turbine to recover power.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14969180A JPS5773299A (en) | 1980-10-24 | 1980-10-24 | Gasification of liquefied natural gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14969180A JPS5773299A (en) | 1980-10-24 | 1980-10-24 | Gasification of liquefied natural gas |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5773299A JPS5773299A (en) | 1982-05-07 |
| JPS6255040B2 true JPS6255040B2 (en) | 1987-11-18 |
Family
ID=15480693
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14969180A Granted JPS5773299A (en) | 1980-10-24 | 1980-10-24 | Gasification of liquefied natural gas |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5773299A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EA010641B1 (en) * | 2004-09-22 | 2008-10-30 | Флуор Текнолоджиз Корпорейшн | Method for processing lpg and power generation and a plant therefor |
| KR20170027104A (en) * | 2015-09-01 | 2017-03-09 | 한국가스공사 | Reliquefaction Method For Boiled-Off Gas |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5142704A (en) * | 1974-10-11 | 1976-04-12 | Mitsui Toatsu Chemicals | Ekikatennengasuno kikahoho |
-
1980
- 1980-10-24 JP JP14969180A patent/JPS5773299A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5142704A (en) * | 1974-10-11 | 1976-04-12 | Mitsui Toatsu Chemicals | Ekikatennengasuno kikahoho |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5773299A (en) | 1982-05-07 |
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