JP3569190B2

JP3569190B2 - Precise filling method of xenon gas

Info

Publication number: JP3569190B2
Application number: JP2000047122A
Authority: JP
Inventors: 卓男宮川; 芳弘栗生; 豊作本
Original assignee: Air Water Inc
Current assignee: Air Water Inc
Priority date: 2000-02-24
Filing date: 2000-02-24
Publication date: 2004-09-22
Anticipated expiration: 2020-02-24
Also published as: JP2001235097A

Description

【０００１】
【発明の属する技術分野】
本発明は、キセノンガスを原料ガスボンベから高圧ガス容器に充填する場合の精密充填方法に関する。
【０００２】
【従来の技術】
人工衛星等においては、その搭載物に厳しい重量管理が行われており、１物体に対してグラム単位での精度が要求される。また、人工衛星の軌道制御、姿勢制御には、イオンエンジンが多く使用されている。イオンエンジンは、推進剤をイオン化し、静電力で加速噴射して推力を発生する推進機で、化学ロケットより１桁高い比推力、数千〜１００００秒が容易に得られる。
【０００３】
イオンエンジンには、電子衝撃型イオンエンジン、ＲＦイオンエンジン、接触電離型セシウムエンジン、マイクロ波エンジン等がある。このうち、電子衝撃型イオンエンジンは、地上と宇宙での試験経験、性能、寿命上の優位性から世界の主流として研究開発が盛んである。電子衝撃型イオンエンジンは、放電をイオン源とし、推進薬としては電離し易い原子状気体あるいは容易にその状態になる水銀、セシウム、希ガスが選ばれる。性能上および貯蔵供給面からは、水銀が最良であるが、周囲への影響を考慮した次善のものとしてキセノン、クリプトン、アルゴンを採用する傾向にある。
【０００４】
推進薬を充填する人工衛星の燃料タンクは、エンジンとの配管接続の関係から推進薬充填前に衛星に搭載される。このため、燃料タンクへのキセノンガスの充填は、衛星に燃料タンクを搭載した後に行われるので、その重量を計ることはできない。経験的には、人工衛星の総重量の０．１％の精度が要求される事態も生じることがある。
【０００５】
従来、高圧ガス容器へのキセノンガスの充填は、原料ガスボンベからダイヤフラム型圧縮機を用いてキセノンガスを吸引圧縮したのち、高圧ガス容器に圧送して充填するのが一般的である。しかしながら、圧縮機は、ダイヤフラム型圧縮機に限らず、非常に複雑な構造を持つため、原料ガスボンベから高圧ガス容器（衛星の気蓄器等）へのキセノンガスの充填精度は、［高圧ガス容器充填重量＝原料ガスボンベ減少量−接続配管系内残量−圧縮機内残量］で表される。
【０００６】
このうち、原料ガスボンベ減少量は、通常秤量器によって正確に測定することができる。接続配管系内残量は、接続配管系内容積が正確に測定できていれば、キセノン物性（温度、圧力）よりかなりの精度で決定することができる。しかし、圧縮機内残量は、ダイヤフラム内の状況温度、残圧、ダイヤフラムの位置の不安定により残量測定に大きな誤差が生じることは避けられない。そのため、高圧ガス容器充填量の精密な決定は、殆ど不可能と考えられる。
【０００７】
一方、衛星の燃料タンクに充填されるキセノンガスは、大抵の場合原料ガスばかりでなく、充填系も含めて清浄に管理されていることが要求されている。このため、衛星の燃料タンクへのキセノンガスの充填に際しては、圧縮機を含めて配管系全てに亘って内部パーティクルパージ、ガス成分パージ等の清浄化およびその確認分析が必要となる。
【０００８】
【発明が解決しようとする課題】
上記したように圧縮機による高圧ガス容器へのキセノンガス充填においては、ダイヤフラム型はパーティクルが比較的少ないとはいっても、摺動部において発生すること、また、ガス成分パージにおいても、配管に比較してその複雑な構造のため、多大な時間を要するばかりでなく、高圧ガス容器への充填量の測定精度、清浄化の点で十分に満足できるものではなかった。
【０００９】
本発明の目的は、上記圧縮機による高圧ガス容器へのキセノンガス充填時の欠点を解消し、衛星に搭載される燃料タンクへキセノンガスを規定の重量精度で充填できるキセノンガスの精密充填方法を提供することにある。
【００１０】
【課題を解決するための手段】
本発明のキセノンガスの精密充填方法は、精密秤量器を備えた耐圧固化容器にキセノンガスを導入し、液体窒素により冷却固化して高密度に充填したのち、耐圧固化容器の温度を上昇させて残液体窒素を気化させた後、さらに昇温させて固化キセノンをガス化、昇温、昇圧させ、所定必要圧力に達した時点でキセノンガスの高圧ガス容器への充填を開始し、精密秤量器による耐圧固化容器のキセノン減少量と、配管系内容積とキセノン物性（温度・圧力）から求めた耐圧固化容器と高圧ガス容器間の接続配管系に残留するキセノンガス重量とから高圧ガス容器充填キセノンガス量を計算し、充填キセノンガス量が予め定めた設定量となった時点で充填を停止することを特徴とする。
【００１１】
上記のように、精密秤量器を備えた耐圧固化容器にキセノンガスを導入し、液体窒素により冷却固化してガス体に比べて高密度に充填したのち、温度を上昇させて残液体窒素を気化させた後、さらに昇温させて固化キセノンをガス化、昇温、昇圧させ、高圧ガス容器に送り出す推進力を得るものである。高圧ガス容器にキセノンガスを充填中は、精密秤量器による耐圧固化容器キセノン減少量と、配管系内容積とキセノン物性（温度・圧力）から求めた耐圧固化容器と高圧ガス容器間接続配管系に残留するキセノンガス重量とから高圧ガス容器への充填キセノンガス量を計算し、充填キセノンガス量が予め定めた設定量となった時点で充填を停止することによって、高圧ガス容器への充填キセノンガス量を正確に計ることができる。
【００１２】
【発明の実施の形態】
本発明のキセノンガスの精密充填方法は、キセノンガスが融点−１１１．９℃、沸点−１０８．１℃であるので、沸点−１９５．８℃の液体窒素を用いて冷却することにより、キセノンガスを耐圧固化容器内で固化させれば、ガス体に比べて高密度（密度約３．０６／ｍｌ）に充填することができる。そして、温度を上昇させて固化キセノンをガス化し、昇圧させて高圧ガス容器に送り出す推進力を得るものである。
【００１３】
耐圧固化容器には、キセノンガスを冷却するための液体窒素槽部を重量軽減を目的として、耐圧固化容器上部の最適位置に設置し、最小容積により効率的にキセノンを固化できるようにしている。また、耐圧固化容器には、加熱設備を設置し、初期に液体窒素槽の残量液体窒素を気化させて追出し、その後固化キセノンのガス化昇圧、更にキセノンガスを１００℃以上に昇温させて昇圧させることによって、高圧ガス容器への充填後の耐圧固化容器のキセノン残量を最小とすることができる。
【００１４】
耐圧固化容器の下部には、精密秤量器を備えているので、導入されたキセノンガス量が精度よく測定でき、高圧ガス容器への充填可能量を決定することができる。高圧ガス容器へのキセノンガス充填時には、精密秤量器の減少量によって耐圧固化容器からのキセノンガスの払出し量を正確に計ることができる。なお、耐圧固化容器への配管等による重量測定時の影響は、正確に検討されたばね系ならびに切離し設備によって、完全に分離できる構造とするのがよい。
【００１５】
高圧ガス容器へのキセノンガス充填量は、耐圧固化容器のキセノン減少量から耐圧固化容器と高圧ガス容器間の配管系に残留するキセノン量を差し引くことによって行うが、配管系内容積とキセノン物性（温度・圧力）から自動的に計算し、常時フィードバックする。これによって、高圧ガス容器へのキセノン目標充填量とフィードバックされる高圧ガス容器へのキセノン充填量とを比較することによって、充填停止時間（タイミング）を正確に検出することができる。
【００１６】
本発明のキセノンガスの精密充填方法は、キセノンガスの高圧ガス容器への充填途中において、異常発生等により停止が生じても、中断後引続き充填を再開することが可能である。また、耐圧固化容器を液体窒素槽に液体窒素を導入して冷却すれば、それまでに充填したキセノンガスを耐圧固化容器に再度戻し、最初から再充填することもできる。
【００１７】
【実施例】
本発明のキセノンガスの精密充填方法の詳細を図１に基づいて説明する。図１は人工衛星の燃料タンクへのキセノンガスの精密充填工程の全体説明図である。図１において、１はキセノンガスボンベ、２は上部に加熱ヒータ３を有する液体窒素槽４と下部に加熱ヒータ５を付設した耐圧固化容器、６は耐圧固化容器２の重量を測定する精密秤量器、７は人工衛星に設置された燃料タンク、８は真空ポンプ、９は液体窒素容器である。
【００１８】
キセノンガスボンベ１と耐圧固化容器２は、手動弁Ｘ−０１、手動弁Ｘ−０２、減圧弁ＮＶ−０１、手動弁Ｘ−０３、フィルターＦ−０１、手動弁Ｘ−０４、緊急遮断弁ＸＥ−０１、手動弁Ｘ−０５を介してＳＵＳ配管により接続し、キセノンガスボンベ１から耐圧固化容器２へキセノンガスを導入できるよう構成している。また、手動弁Ｘ−０１と手動弁Ｘ−０２との間には、開閉弁Ｓ−０１を介して圧力指示計ＰＩ−１を、手動弁Ｘ−０３とフィルターＦ−０１との間には、開閉弁Ｓ−０２を介して圧力指示計ＰＩ−２を、フィルターＦ−０１と手動弁Ｘ−０４との間には、開閉弁Ｓ−０３を介して放散弁ＦＶ−０１を、手動弁Ｘ−０４と緊急遮断弁ＸＥ−０１との間には、開閉弁Ｓ−０４を介して圧力指示計ＰＩ−３を、緊急遮断弁ＸＥ−０１と手動弁Ｘ−０５との間には、開閉弁Ｓ−０８を有する精密圧力計ＰＴ−１と精密温度計ＴＨ−１を、手動弁Ｘ−０５と耐圧固化容器２との間には、開閉弁Ｓ−０５を介して放散弁ＦＶ−０２を連結している。
【００１９】
耐圧固化容器２に付設した液体窒素槽４と液体窒素容器９は、手動弁Ｎ−３１、フレキシブルホースＮ−３０、手動弁Ｎ−３２を介してＳＵＳ配管により接続し、液体窒素容器９より液体窒素槽４へ液体窒素を導入できるよう構成している。また、フレキシブルホースＮ−３０と手動弁Ｎ−３２との間には、開閉弁Ｓ−３０を介して放散弁ＦＶ−３０を連結している。液体窒素容器９には、圧力指示計ＰＩ−３０が設けられている。加熱ヒータ３、５には、温度指示制御警報計ＴＩＣＡ−１、ＴＩＣＡ−２が設けられている。
【００２０】
耐圧固化容器２と燃料タンク７は、手動弁Ｘ−０５、流量調整弁ＰＣＶ−１、緊急遮断弁ＸＥ−０２、手動弁Ｘ−０６、フィルターＦ−０２、手動弁Ｘ−０７、フレキシブルホースＨ−１、手動弁Ｘ−０８、フィルターＦ−０３、燃料タンク７の受入れ弁である注排弁Ｔ−０１を介してＳＵＳ配管により接続し、耐圧固化容器２から燃料タンク７へキセノンガスを充填できるよう構成している。また、緊急遮断弁ＸＥ−０２と手動弁Ｘ−０６との間には、開閉弁Ｓ−０６を介して圧力指示計ＰＩ−４を、開閉弁Ｓ−０７を介して放散弁ＦＶ−０４を設置している。手動弁Ｘ−０６とフィルターＦ−０２の間には、開閉弁ＳＰ−１を介してサンプルガス導入ポートを接続できるよう構成している。フィルターＦ−０２と手動弁Ｘ−０７との間には、開閉弁Ｓ−０９を有する精密圧力計ＰＴ−２と精密温度計ＴＨ−２を設けている。
【００２１】
キセノンガスボンベ１から耐圧固化容器２へのキセノンガス導入系、耐圧固化容器２から燃料タンク７へのキセノンガス充填系には、系内の不純物除去パージのために、系内の随所に真空ポンプ８のラインとの接続ポートを設け、短時間で確実なパージが行えるよう構成している。すなわち、手動弁Ｘ−０３とフィルターＦ−０１の間と真空ポンプ８とは、手動弁Ｖ−０１を、手動弁Ｘ−０４と緊急遮断弁ＸＥ−０１の間と真空ポンプ８とは、手動弁Ｖ−０２を、手動弁Ｘ−０５と耐圧固化容器２の間と真空ポンプ８とは、手動弁Ｖ−０３を、緊急遮断弁ＸＥ−０２と手動弁Ｘ−０６の間と真空ポンプ８とは、手動弁Ｖ−０４を、フィルターＦ−０３と燃料タンク７の間と真空ポンプ８とは、手動弁Ｖ−０５、フレキシブルホースＨ−２、手動弁Ｖ−０６を介在させ、手動弁Ｖ−０７を介してＳＵＳ配管により接続している。
【００２２】
１１はシーケンサで、開閉弁Ｘ−０５と緊急遮断弁ＸＥ−０１、流量調整弁ＰＣＶ−１の間の配管系の精密圧力計ＰＴ−１と精密温度計ＴＨ−１、耐圧固化容器２の出口の圧力指示警報計ＰＩＡ−１、耐圧固化容器２内の温度指示警報計ＴＩＡ−１、液体窒素槽４と耐圧固化容器２下部の加熱ヒータ３、５の温度指示制御警報計ＴＩＣＡ−１、ＴＩＣＡ−２、秤量器６、精密圧力計ＰＴ−２、精密温度計ＴＨ−２の実測値が入力される。シーケンサ１１は、入力されたこれらの圧力、温度に基づいて、燃料タンク７へキセノンガスを充填する際の過剰な温度上昇の防止、急激な圧力上昇の防止のための流量制御、耐圧固化容器２の急激な圧力上昇の防止のための加熱ヒータ３、５の温度制御と、充填システム側および燃料タンク７側に要求される制御条件を満足させるため、緊急遮断弁ＸＥ−０１、流量調整弁ＰＣＶ−１、緊急遮断弁ＸＥ−０２の制御を実施するよう構成している。
【００２３】
上記のように構成したことによって、キセノンガスボンベ１から耐圧固化容器２へのキセノンガスの充填は、先ず真空ポンプ８を起動して手動弁Ｖ−０１、Ｖ−０２、Ｖ−０３を開放して充填ラインをパージしたのち、手動弁Ｖ−０１、Ｖ−０２、Ｖ−０３を閉じ、真空ポンプ８を停止する。しかるのち、手動弁Ｘ−０１、Ｘ−０２、Ｘ−０３、Ｘ−０４、緊急遮断弁ＸＥ−０１、手動弁Ｘ−０５を開放し、キセノンガスボンベ１から耐圧固化容器２へキセノンガスを充填する。耐圧固化容器２の液体窒素槽４には、手動弁Ｎ−３１、Ｎ−３２を開放して液体窒素容器９から液体窒素を導入し、耐圧固化容器２および耐圧固化容器２内のキセノンガスを冷却する。
【００２４】
耐圧固化容器２内のキセノンガスは、液体窒素により冷却されて固体化し、高密度で耐圧固化容器２内に蓄積される。シーケンサ１１は、燃料タンク７が要求するキセノン量と耐圧固化容器２およびキセノン充填ライン系に残留するキセノン量を、秤量器６から入力される秤量値に基づいて耐圧固化容器２内へ導入蓄積し、目標値に達した時点で緊急遮断弁ＸＥ−０１を遮断する。しかるのち、手動弁Ｘ−０１、Ｘ−０２、Ｘ−０３、Ｘ−０４、Ｘ−０５を閉じ、キセノンガスの耐圧固化容器２への導入を停止し、手動弁Ｎ−３１、Ｎ−３２を閉じて液体窒素容器９から液体窒素槽４への液体窒素の供給を停止し、キセノンガスの耐圧固化容器２への充填を終了する。
【００２５】
しかるのち、シーケンサ１１は、液体窒素槽４に付設した加熱ヒータ３により液体窒素槽４を所定温度に加熱し、液体窒素槽４内に残留する液体窒素をガス化し、液体窒素槽４よりの追い出しを実施する。そして、耐圧固化容器２は、液体窒素の導入ならびにブローラインおよび真空ラインと接続部の切離しまたはバネ系により独立した状態とし、精密秤量器６によって初期重量の測定を実施する。その後、シーケンサ１１は、加熱ヒータ３および耐圧固化容器２下部の加熱ヒータ５によって耐圧固化容器２およびキセノンガスの加熱を継続し、耐圧固化容器２内のキセノンガス圧力を所定必要圧力まで昇圧する。
【００２６】
その間に、真空ポンプ８を起動して手動弁Ｖ−０４、Ｖ−０５、Ｖ−０６を開放し、燃料タンク７へのキセノンガスの供給ラインをパージしたのち、手動弁Ｖ−０４、Ｖ−０５、Ｖ−０６を閉じ、真空ポンプ８を停止する。耐圧固化容器２内のキセノンガス圧力が所定必要圧力に達した時点で、手動弁Ｘ−０５、手動弁Ｘ−０６、手動弁Ｘ−０７、手動弁Ｘ−０８、注排弁Ｔ−０１を開放する。シーケンサ１１は、流量調整弁ＰＣＶ−１、緊急遮断弁ＸＥ−０２を制御して燃料タンク７へのキセノンガスの供給を開始する。
【００２７】
この場合、シーケンサ１１は、燃料タンク７の過剰な温度上昇の防止、急激な圧力上昇の防止のため、精密圧力計ＰＶ−１、ＰＶ−２、精密温度計ＴＨ−１、ＴＨ−２から入力される実測値に基づき、流量調整弁ＰＣＶ−１による流量制御と、耐圧固化容器２の急激な圧力上昇の防止のため、温度指示制御警報計ＴＩＣＡ−１、ＴＩＣＡ−２から入力される実測値に基づき、加熱ヒータ３、５の温度制御を実施する。この燃料タンク７へのキセノンガスの充填は、系内の状態、特にキセノン充填ラインのバラツキを避けるため、できる限り遅くすることが望ましい。
【００２８】
また、シーケンサ１１は、精密秤量器６から入力される耐圧固化容器２の重量に基づき計算されるキセノン減少量と、精密圧力計ＰＴ−１、ＰＴ−２、精密温度計ＴＨ−１、ＴＨ−２から入力されるキセノン物性（温度・圧力）と予め設定されている耐圧固化容器２と燃料タンク７間の配管系内容積から耐圧固化容器２と燃料タンク７間に残るキセノン量との差により、燃料タンク７へのキセノンガスの充填量を常時計算する。そして、シーケンサ１１は、燃料タンク７へのキセノンガスの充填量が、燃料タンク７充填要求キセノン量に一致、すなわち、（燃料タンク７充填要求キセノン量）＝（耐圧固化容器２重量減少量）−（キセノン充填ライン残量）が一致した時点で、緊急遮断弁ＸＥ−０２を閉じる。そして、手動弁Ｘ−０８、注排弁Ｔ−０１を閉じたのち、手動弁Ｘ−０５、手動弁Ｘ−０６、手動弁Ｘ−０７、流量調整弁ＰＣＶ−１を閉じ、燃料タンク７へのキセノンガスの充填を完了する。なお、キセノン充填ラインのキセノンガス残量は、精密圧力計ＰＴ−１、ＰＴ−２および精密温度計ＴＨ−１、ＴＨ−２に基づくキセノン物性と、予め設定されている耐圧固化容器２と燃料タンク７間の配管系内容積によって、キセノン充填ラインの配管系内残量が精度良く算出することができる。
【００２９】
上記のように、本発明方法は、キセノンガスを燃料タンク７に送り出す推進力を、従来のように圧縮機を用いず、耐圧固化容器２内にキセノンを固化させて高密度に充填したのち、耐圧固化容器２の温度を上昇させ、固化キセノンのガス化昇圧、さらに昇温（１００℃以上）させて昇圧させて得るから、圧縮機に起因するパーティクルの混入を防止できる。また、系内にフィルターＦ−０１、Ｆ−０２、Ｆ−０３を設けたから、パーティクル、不純物成分を除去することができる。
【００３０】
さらに、精密秤量器によるキセノン減少量と、精密圧力計ＰＴ−１、ＰＴ−２および精密温度計ＴＨ−１、ＴＨ−２に基づくキセノン物性と予め設定されている耐圧固化容器２と燃料タンク７間の配管系内容積によって計算されるキセノン充填ラインの配管系内残量に基づき、燃料タンク７へのキセノンガスの充填量を算出するから、燃料タンク７の総重量の０．１％の精度でキセノンガスを充填することができる。
【００３１】
【発明の効果】
本発明のキセノンガスの精密充填方法は、キセノンガスを燃料タンクに送り出す推進力を耐圧固化容器内にキセノンを固化させて高密度に充填したのち、耐圧固化容器の温度を上昇させ、固化キセノンをガス化し、さらに昇温（１００℃以上）させて高圧のガス化したキセノンを得られることから、パーティクルの混入を大幅に抑制できると共に、燃料タンクの総重量の０．１％以下の精度でキセノンガスを充填することができる。
【図面の簡単な説明】
【図１】人工衛星の燃料タンクへのキセノンガスの精密充填工程の全体説明図である。
【符号の説明】
１キセノンガスボンベ
２耐圧固化容器
３、５加熱ヒータ
４液体窒素槽
６精密秤量器
７燃料タンク
８真空ポンプ
９液体窒素容器
１１シーケンサ
Ｘ−０１、Ｘ−０２、Ｘ−０３、Ｘ−０４、Ｘ−０５、Ｘ−０６、Ｘ−０７、Ｘ−０８、Ｓ−０９手動弁
ＮＶ−０１減圧弁
Ｆ−０１、Ｆ−０２、Ｆ−０３フィルター
ＸＥ−０１、ＸＥ−０２緊急遮断弁
Ｓ−０１、Ｓ−０２、Ｓ−０３、Ｓ−０４、Ｓ−０５、Ｓ−０６、Ｓ−０７、Ｓ−０８、Ｓ−０９、Ｓ−３０、ＳＰ−１開閉弁
ＰＩ−１、ＰＩ−２、ＰＩ−３、ＰＩ−４、ＰＩ−３０圧力指示計
ＦＶ−０１、ＦＶ−０２、ＦＶ−０４、ＦＶ−３０放散弁
Ｎ−３１、Ｎ−３２、Ｖ−０１、Ｖ−０２、Ｖ−０３、Ｖ−０４、Ｖ−０５、Ｖ−０６、Ｖ−０７手動弁
Ｎ−３０、Ｈ−１、Ｈ−２フレキシブルホース
ＴＩＣＡ−１、ＴＩＣＡ−２温度指示制御警報計
ＰＣＶ−１流量調整弁
Ｔ−０１注排弁
ＰＴ−１、ＰＴ−２精密圧力計
ＴＨ−１、ＴＨ−２精密温度計[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a precision filling method for filling xenon gas from a raw material gas cylinder into a high-pressure gas container.
[0002]
[Prior art]
In an artificial satellite or the like, strict weight control is performed on the mounted object, and accuracy of one object in units of grams is required. Further, ion engines are often used for orbit control and attitude control of artificial satellites. An ion engine is a thruster that ionizes a propellant and accelerates and injects it with an electrostatic force to generate a thrust. A specific thrust one digit higher than that of a chemical rocket and thousands to 10,000 seconds can be easily obtained.
[0003]
The ion engine includes an electron impact ion engine, an RF ion engine, a contact ionization type cesium engine, a microwave engine, and the like. Among them, the electron impact ion engine has been actively researched and developed as the world's mainstream due to its superiority in test experience, performance and life on the ground and in space. The electron impact type ion engine uses discharge as an ion source, and as a propellant, an easily ionized atomic gas or mercury, cesium, or a rare gas which easily enters that state is selected. Mercury is the best in terms of performance and storage and supply, but there is a tendency to use xenon, krypton, and argon as the next best considering the influence on the surroundings.
[0004]
The fuel tank of the artificial satellite to be filled with propellant is mounted on the satellite before filling with propellant due to the connection of piping to the engine. For this reason, since the filling of the fuel tank with xenon gas is performed after the fuel tank is mounted on the satellite, its weight cannot be measured. Empirically, there may be situations where an accuracy of 0.1% of the total weight of the satellite is required.
[0005]
Conventionally, when filling a high-pressure gas container with xenon gas, it is general that the xenon gas is suction-compressed from a raw material gas cylinder using a diaphragm-type compressor and then fed by pressure to a high-pressure gas container for filling. However, since the compressor is not limited to a diaphragm type compressor and has a very complicated structure, the accuracy of filling xenon gas from a raw material gas cylinder to a high-pressure gas container (such as a gas storage device of a satellite) is as follows. Filling weight = reduced amount of raw material gas cylinder−remaining amount in connection piping system−remaining amount in compressor].
[0006]
Of these, the reduction amount of the raw material gas cylinder can usually be accurately measured by a weighing device. The remaining amount in the connection piping system can be determined with considerably higher accuracy than the xenon physical properties (temperature and pressure) if the volume in the connection piping system can be accurately measured. However, as for the remaining amount in the compressor, it is inevitable that a large error occurs in the remaining amount measurement due to the situation temperature in the diaphragm, the residual pressure, and the unstable position of the diaphragm. Therefore, it is considered almost impossible to precisely determine the filling amount of the high-pressure gas container.
[0007]
On the other hand, xenon gas filled in a fuel tank of a satellite is required to be managed not only in a raw material gas but also in a clean manner including a filling system in most cases. For this reason, when filling xenon gas into the fuel tank of the satellite, it is necessary to clean internal particle purge, gas component purge, etc., and to analyze and confirm the purge throughout the entire piping system including the compressor.
[0008]
[Problems to be solved by the invention]
As described above, when filling xenon gas into a high-pressure gas container using a compressor, the diaphragm type generates particles in the sliding part, even though it has relatively few particles. In addition, due to its complicated structure, not only does it take a great deal of time, but it is not sufficiently satisfactory in terms of measurement accuracy of the filling amount in the high-pressure gas container and cleaning.
[0009]
An object of the present invention is to solve the drawbacks of filling the high-pressure gas container with xenon gas by the above-described compressor, and to provide a method for precisely filling xenon gas into a fuel tank mounted on a satellite with specified weight accuracy. To provide.
[0010]
[Means for Solving the Problems]
The method for precisely filling xenon gas of the present invention comprises introducing xenon gas into a pressure-resistant solidification container equipped with a precision weighing device, cooling and solidifying with liquid nitrogen, filling the mixture with high density, and then raising the temperature of the pressure-solidification container. After the residual liquid nitrogen is vaporized, the temperature is further increased to gasify the solidified xenon, the temperature is increased, and the pressure is increased.When the required pressure is reached, the filling of the xenon gas into the high-pressure gas container is started, and the precision weighing device is used. Xenon filling in a high-pressure gas container based on the amount of xenon reduced in the pressure-resistant solidification container due to pressure, and the weight of xenon gas remaining in the connection piping system between the pressure-resistant solidification container and the high-pressure gas container obtained from the piping system volume and xenon physical properties (temperature and pressure) The gas amount is calculated, and charging is stopped when the charged xenon gas amount reaches a predetermined set amount.
[0011]
As described above, xenon gas is introduced into a pressure-resistant solidification container equipped with a precision weighing device, cooled and solidified with liquid nitrogen, filled at a higher density than the gas body, and then heated to evaporate the remaining liquid nitrogen. After that, the temperature is further increased to gasify the solidified xenon, increase the temperature, and increase the pressure, thereby obtaining a driving force for sending the xenon to a high-pressure gas container. While the high-pressure gas container is being filled with xenon gas, the pressure-solidifying container xenon reduction by a precision weighing device and the piping system between the pressure-solidifying container and the high-pressure gas container determined from the piping system volume and xenon physical properties (temperature / pressure). By calculating the amount of xenon gas charged into the high-pressure gas container from the weight of the remaining xenon gas and stopping the charging when the amount of charged xenon gas reaches a predetermined set amount, the amount of xenon gas charged into the high-pressure gas container is calculated. The amount can be measured accurately.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Since the xenon gas has a melting point of −111.9 ° C. and a boiling point of −108.1 ° C., it is cooled by using liquid nitrogen having a boiling point of −195.8 ° C. Is solidified in a pressure-resistant solidification vessel, it can be packed at a higher density (density of about 3.06 / ml) than a gas body. Then, the temperature is increased to gasify the solidified xenon, and the pressure is increased to obtain a propulsive force to be sent to the high-pressure gas container.
[0013]
In the pressure-resistant solidification vessel, a liquid nitrogen tank for cooling the xenon gas is installed at an optimum position above the pressure-solidification vessel for the purpose of weight reduction, so that xenon can be efficiently solidified with a minimum volume. In addition, a heating facility is installed in the pressure-resistant solidification vessel, and the remaining liquid nitrogen in the liquid nitrogen tank is vaporized and expelled at first, and then the gasification pressure of solidified xenon is increased, and the temperature of xenon gas is further increased to 100 ° C. or more. By increasing the pressure, the remaining amount of xenon in the pressure-resistant solidification container after filling the high-pressure gas container can be minimized.
[0014]
Since a precision weighing device is provided at the lower part of the pressure-resistant solidification container, the amount of the introduced xenon gas can be measured accurately, and the amount that can be charged into the high-pressure gas container can be determined. At the time of filling the high-pressure gas container with xenon gas, the amount of xenon gas discharged from the pressure-resistant solidification container can be accurately measured by the reduced amount of the precision weighing device. In addition, it is preferable that the influence at the time of weight measurement due to piping or the like to the pressure-resistant solidification container be completely separated by a spring system and separation equipment that have been accurately studied.
[0015]
The amount of xenon gas charged into the high-pressure gas container is determined by subtracting the amount of xenon remaining in the piping system between the pressure-resistant solidification container and the high-pressure gas container from the amount of xenon reduced in the pressure-resistant solidification container. Temperature / pressure), and always feedback. Thus, the charging stop time (timing) can be accurately detected by comparing the xenon target filling amount in the high-pressure gas container with the xenon filling amount in the high-pressure gas container fed back.
[0016]
According to the method for precisely filling xenon gas of the present invention, even if a stop occurs due to an abnormality or the like during the filling of the xenon gas into the high-pressure gas container, the filling can be resumed after the interruption. Further, if the pressure-solidifying vessel is cooled by introducing liquid nitrogen into the liquid nitrogen tank, the xenon gas filled up to that time can be returned to the pressure-solidifying vessel again and refilled from the beginning.
[0017]
【Example】
The details of the method for precisely filling xenon gas of the present invention will be described with reference to FIG. FIG. 1 is an overall explanatory diagram of a process of precisely filling xenon gas into a fuel tank of an artificial satellite. In FIG. 1, reference numeral 1 denotes a xenon gas cylinder, 2 denotes a pressure-resistant solidification container provided with a liquid nitrogen tank 4 having a heater 3 at an upper part and a heater 5 at a lower part, 6 denotes a precision weigher for measuring the weight of the pressure-resistant solidification container 2, Reference numeral 7 denotes a fuel tank installed on an artificial satellite, 8 denotes a vacuum pump, and 9 denotes a liquid nitrogen container.
[0018]
The xenon gas cylinder 1 and pressure-resistant solidification container 2 are provided with a manual valve X-01, a manual valve X-02, a pressure reducing valve NV-01, a manual valve X-03, a filter F-01, a manual valve X-04, and an emergency shutoff valve XE-. 01, connected by a SUS pipe via a manual valve X-05, so that xenon gas can be introduced from the xenon gas cylinder 1 to the pressure-resistant solidification vessel 2. Further, a pressure indicator PI-1 is provided between the manual valve X-01 and the manual valve X-02 via the on-off valve S-01, and a pressure indicator PI-1 is provided between the manual valve X-03 and the filter F-01. , A pressure indicator PI-2 via an on-off valve S-02, a dissipating valve FV-01 between a filter F-01 and a manual valve X-04 via an on-off valve S-03, and a manual valve. Between X-04 and the emergency shutoff valve XE-01, a pressure indicator PI-3 is provided via an on-off valve S-04, and between the emergency shutoff valve XE-01 and the manual valve X-05, A precision pressure gauge PT-1 having an on-off valve S-08 and a precision thermometer TH-1 are provided between the manual valve X-05 and the pressure-resistant solidifying container 2 via an on-off valve S-05 for a dissipation valve FV-. 02 is connected.
[0019]
The liquid nitrogen tank 4 and the liquid nitrogen container 9 attached to the pressure-resistant solidification container 2 are connected by a SUS pipe via a manual valve N-31, a flexible hose N-30, and a manual valve N-32, and the liquid from the liquid nitrogen container 9 It is configured so that liquid nitrogen can be introduced into the nitrogen tank 4. Further, a dissipation valve FV-30 is connected between the flexible hose N-30 and the manual valve N-32 via an on-off valve S-30. The liquid nitrogen container 9 is provided with a pressure indicator PI-30. The heaters 3 and 5 are provided with temperature instruction control alarm meters TICA-1 and TICA-2.
[0020]
The pressure-resistant solidification container 2 and the fuel tank 7 are composed of a manual valve X-05, a flow control valve PCV-1, an emergency shutoff valve XE-02, a manual valve X-06, a filter F-02, a manual valve X-07, and a flexible hose H. -1, Connected by a SUS pipe via a manual valve X-08, a filter F-03, and an injection valve T-01 which is a receiving valve of the fuel tank 7, and filling the fuel tank 7 with the xenon gas from the pressure-resistant solidification container 2 It is configured to be able to. Further, between the emergency shutoff valve XE-02 and the manual valve X-06, a pressure indicator PI-4 is provided via an on-off valve S-06, and a dissipation valve FV-04 is provided via an on-off valve S-07. Has been installed. A sample gas introduction port can be connected between the manual valve X-06 and the filter F-02 via the on-off valve SP-1. Between the filter F-02 and the manual valve X-07, a precision pressure gauge PT-2 having an on-off valve S-09 and a precision thermometer TH-2 are provided.
[0021]
A xenon gas introduction system from the xenon gas cylinder 1 to the pressure-resistant solidification vessel 2 and a xenon gas filling system from the pressure-resistant solidification vessel 2 to the fuel tank 7 are provided with a vacuum pump 8 everywhere in the system for purging impurities in the system. A connection port to the line is provided so that a reliable purge can be performed in a short time. That is, the manual pump V-01 is connected between the manual valve X-03 and the filter F-01 and the vacuum pump 8, and the manual pump V-01 is connected between the manual valve X-04 and the emergency shutoff valve XE-01. The valve V-02 is connected between the manual valve X-05 and the pressure-resistant solidification container 2 and the vacuum pump 8. The manual valve V-03 is connected between the emergency shutoff valve XE-02 and the manual valve X-06 and the vacuum pump 8. Means a manual valve V-04, a manual valve V-05, a flexible hose H-2, and a manual valve V-06 interposed between the filter F-03 and the fuel tank 7 and the vacuum pump 8. They are connected by SUS piping via V-07.
[0022]
Reference numeral 11 denotes a sequencer, which is a precision pressure gauge PT-1 and a precision thermometer TH-1 in a piping system between an on-off valve X-05 and an emergency shutoff valve XE-01, a flow control valve PCV-1, and an outlet of the pressure-resistant solidification vessel 2. Pressure indicator PIA-1; temperature indicator TIA-1 in the pressure-resistant solidification vessel 2; and temperature indicator control alarms TICA-1 and TICA for the liquid nitrogen tank 4 and the heaters 3 and 5 below the pressure-resistant solidification vessel 2. -2, the measured values of the weighing device 6, the precision pressure gauge PT-2, and the precision thermometer TH-2 are input. Based on these input pressures and temperatures, the sequencer 11 prevents excessive temperature rise when filling the fuel tank 7 with xenon gas, controls flow rate to prevent sudden pressure rise, Temperature control of the heaters 3 and 5 for preventing a rapid pressure rise of the fuel cell and an emergency shutoff valve XE-01 and a flow control valve PCV in order to satisfy control conditions required for the filling system and the fuel tank 7. -1, It is configured to execute control of the emergency shutoff valve XE-02.
[0023]
With the above-described configuration, the filling of the pressure-resistant solidification vessel 2 from the xenon gas cylinder 1 with the xenon gas is performed by first activating the vacuum pump 8 and opening the manual valves V-01, V-02, and V-03. After purging the filling line, the manual valves V-01, V-02, and V-03 are closed, and the vacuum pump 8 is stopped. Thereafter, the manual valves X-01, X-02, X-03, X-04, the emergency shutoff valve XE-01, and the manual valve X-05 are opened, and the xenon gas cylinder 1 fills the pressure-resistant solidification container 2 with xenon gas. I do. In the liquid nitrogen tank 4 of the pressure-resistant solidification container 2, liquid nitrogen is introduced from the liquid nitrogen container 9 by opening the manual valves N-31 and N-32, and the xenon gas in the pressure-solidification container 2 and the pressure-solidification container 2 is supplied. Cooling.
[0024]
The xenon gas in the pressure-resistant solidification vessel 2 is cooled by liquid nitrogen and solidified, and is accumulated in the pressure-resistant solidification vessel 2 at high density. The sequencer 11 introduces and accumulates the amount of xenon required by the fuel tank 7 and the amount of xenon remaining in the pressure-resistant solidification container 2 and the xenon filling line system into the pressure-resistant solidification container 2 based on the weighing value input from the weighing device 6. When the target value is reached, the emergency shutoff valve XE-01 is shut off. Thereafter, the manual valves X-01, X-02, X-03, X-04 and X-05 are closed, the introduction of xenon gas into the pressure-resistant solidification vessel 2 is stopped, and the manual valves N-31 and N-32 are stopped. Is closed, the supply of liquid nitrogen from the liquid nitrogen container 9 to the liquid nitrogen tank 4 is stopped, and the filling of the xenon gas into the pressure-resistant solidification container 2 is terminated.
[0025]
Thereafter, the sequencer 11 heats the liquid nitrogen tank 4 to a predetermined temperature by the heater 3 attached to the liquid nitrogen tank 4, gasifies the liquid nitrogen remaining in the liquid nitrogen tank 4, and drives out the liquid nitrogen from the liquid nitrogen tank 4. Is carried out. Then, the pressure-resistant solidification container 2 is made independent by introducing liquid nitrogen and disconnecting or connecting a blow line and a vacuum line to a connection portion, or by a spring system, and measures the initial weight by the precision weigher 6. Thereafter, the sequencer 11 continues to heat the pressure-resistant solidification container 2 and the xenon gas by the heater 3 and the heater 5 below the pressure-resistant solidification container 2, and increases the xenon gas pressure in the pressure-resistant solidification container 2 to a predetermined required pressure.
[0026]
In the meantime, the vacuum pump 8 is started to open the manual valves V-04, V-05, and V-06, and the xenon gas supply line to the fuel tank 7 is purged, and then the manual valves V-04, V- 05, V-06 is closed, and the vacuum pump 8 is stopped. When the xenon gas pressure in the pressure-resistant solidification container 2 reaches a predetermined required pressure, the manual valve X-05, the manual valve X-06, the manual valve X-07, the manual valve X-08, and the injection / discharge valve T-01 are opened. Open. The sequencer 11 controls the flow control valve PCV-1 and the emergency shutoff valve XE-02 to start supplying xenon gas to the fuel tank 7.
[0027]
In this case, the sequencer 11 receives inputs from the precision pressure gauges PV-1, PV-2, and the precision thermometers TH-1, TH-2 in order to prevent an excessive rise in the temperature of the fuel tank 7 and a sharp rise in pressure. Based on the actual measured values, the actual measured values input from the temperature indicating control alarms TICA-1 and TICA-2 to control the flow rate by the flow regulating valve PCV-1 and to prevent the pressure in the pressure-resistant solidification vessel 2 from increasing sharply. , The temperature of the heaters 3 and 5 is controlled. It is desirable to fill the fuel tank 7 with xenon gas as late as possible in order to avoid variations in the state of the system, particularly the xenon filling line.
[0028]
In addition, the sequencer 11 calculates the amount of xenon reduction calculated based on the weight of the pressure-resistant solidification container 2 input from the precision weigher 6 and the precision pressure gauges PT-1, PT-2, and the precision thermometers TH-1, TH-. The difference between the xenon physical properties (temperature and pressure) input from Step 2 and the amount of xenon remaining between the pressure-resistant solidification vessel 2 and the fuel tank 7 from the preset volume of the piping system between the pressure-resistant solidification vessel 2 and the fuel tank 7 , The amount of xenon gas charged into the fuel tank 7 is constantly calculated. Then, in the sequencer 11, the amount of xenon gas charged into the fuel tank 7 matches the required amount of xenon to be filled in the fuel tank 7, that is, (the required amount of xenon required to fill the fuel tank 7) = (the amount of weight reduction in the pressure-resistant solidification container 2) − When (the remaining amount of the xenon filling line) coincides, the emergency shutoff valve XE-02 is closed. Then, after closing the manual valve X-08 and the injection / discharge valve T-01, the manual valve X-05, the manual valve X-06, the manual valve X-07, and the flow regulating valve PCV-1 are closed, and the fuel tank 7 is closed. Xenon gas filling is completed. The remaining amount of xenon gas in the xenon filling line is based on the xenon physical properties based on the precision pressure gauges PT-1 and PT-2 and the precision thermometers TH-1 and TH-2, and the preset pressure-resistant solidification container 2 and fuel. The remaining amount in the piping system of the xenon filling line can be accurately calculated based on the volume of the piping system between the tanks 7.
[0029]
As described above, according to the method of the present invention, the driving force for sending xenon gas to the fuel tank 7 is obtained by solidifying xenon in the pressure-resistant solidification container 2 at a high density without using a compressor as in the related art. Since the temperature of the pressure-resistant solidification container 2 is increased to increase the gasification pressure of the solidified xenon, and further to the temperature (100 ° C. or higher) to increase the pressure, it is possible to prevent the mixing of particles caused by the compressor. Further, since the filters F-01, F-02, and F-03 are provided in the system, particles and impurity components can be removed.
[0030]
Further, the pressure-resistant solidification container 2 and the fuel tank 7, which are preset with the amount of xenon depletion by the precision weigher, the xenon physical properties based on the precision pressure gauges PT-1 and PT-2, and the precision thermometers TH-1 and TH-2. Since the amount of xenon gas charged into the fuel tank 7 is calculated based on the remaining amount in the xenon filling line in the xenon filling line calculated by the volume of the xenon gas line between the tanks, an accuracy of 0.1% of the total weight of the fuel tank 7 is obtained. Can be filled with xenon gas.
[0031]
【The invention's effect】
The method for precisely filling xenon gas of the present invention is characterized in that the driving force for sending xenon gas to a fuel tank solidifies xenon in a pressure-resistant solidification vessel and fills it at a high density, then raises the temperature of the pressure-resistant solidification vessel to increase the temperature of the solidified xenon. Since gasification is performed and the temperature is raised (100 ° C. or higher) to obtain high-pressure gasified xenon, mixing of particles can be significantly suppressed, and xenon can be accurately controlled to 0.1% or less of the total weight of the fuel tank. Gas can be filled.
[Brief description of the drawings]
FIG. 1 is an overall explanatory diagram of a process of precisely filling xenon gas into a fuel tank of an artificial satellite.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Xenon gas cylinder 2 Pressure-resistant solidification container 3, 5 Heater 4 Liquid nitrogen tank 6 Precision weigher 7 Fuel tank 8 Vacuum pump 9 Liquid nitrogen container 11 Sequencer X-01, X-02, X-03, X-04, X- 05, X-06, X-07, X-08, S-09 Manual valve NV-01 Reducing valve F-01, F-02, F-03 Filter XE-01, XE-02 Emergency shut-off valve S-01, S-02, S-03, S-04, S-05, S-06, S-07, S-08, S-09, S-30, SP-1 Open / close valve PI-1, PI-2, PI -3, PI-4, PI-30 Pressure indicators FV-01, FV-02, FV-04, FV-30 Discharge valves N-31, N-32, V-01, V-02, V-03, V-04, V-05, V-06, V-07 Manual valve N-30, H-1, H-2 Shiburuhosu TICA-1, TICA-2 temperature indicator control alarm meter PCV-1 flow control valve T-01 Note exhaust valve PT-1, PT-2 precision pressure gauge TH-1, TH-2 Precision Thermometer

Claims

Xenon gas is introduced into a pressure-resistant solidification vessel equipped with a precision weighing device, cooled and solidified with liquid nitrogen, and filled at a high density.Then, the temperature of the pressure-solidification vessel is increased to evaporate the remaining liquid nitrogen, and then further increased. The solidified xenon is gasified by heating, the temperature is increased, and the pressure is increased.When the required pressure is reached, the xenon gas is filled into the high-pressure gas container, the xenon reduction amount of the pressure-resistant solidified container by a precision weigher, and piping The amount of xenon gas charged into the high-pressure gas container is calculated from the amount of xenon gas remaining in the connection piping system between the pressure-resistant solidification container and the high-pressure gas container determined from the internal volume of the system and the xenon physical properties (temperature and pressure). A method for precisely filling xenon gas, wherein filling is stopped when a predetermined set amount is reached.