JPWO2003022389A1

JPWO2003022389A1 - Distillation apparatus and distillation method using the apparatus

Info

Publication number: JPWO2003022389A1
Application number: JP2003526513A
Authority: JP
Inventors: 野田　秀夫; 秀夫野田; 寛司山路
Original assignee: Kansai Chemical Engineering Co Ltd
Current assignee: Kansai Chemical Engineering Co Ltd
Priority date: 2001-09-10
Filing date: 2002-02-25
Publication date: 2004-12-24
Anticipated expiration: 2022-02-25
Also published as: JP4058410B2; WO2003022389A1

Abstract

省エネルギーおよび蒸留効率に優れた蒸留装置を提洪する。この蒸留装置は、液体散布装置を有する蒸発釜、蒸留塔、熱交換器、コンデンサーおよび留分受器を備えている、半連続式回分蒸留装置である。熱交換器は、蒸留塔とコンデンサーとの間に設けられ、蒸留塔に供給される原液と熱交換するように構成されている。蒸発釜からの蒸気は蒸留塔を通過し、熱交換器および／または該コンデンサーで液化され、液化された液体の一部は留分受器に回収され、残りの液体は蒸留塔に還流するように構成され、そして、蒸留塔の塔底液が該蒸発釜に戻るように構成されている。Providing distillation equipment with excellent energy saving and distillation efficiency. This distillation apparatus is a semi-continuous batch distillation apparatus provided with an evaporation kettle having a liquid spraying device, a distillation tower, a heat exchanger, a condenser and a fraction receiver. The heat exchanger is provided between the distillation column and the condenser, and is configured to exchange heat with the stock solution supplied to the distillation column. The vapor from the evaporation kettle passes through the distillation column and is liquefied by the heat exchanger and / or the condenser, a part of the liquefied liquid is recovered in the fraction receiver, and the remaining liquid is returned to the distillation column. And the bottom liquid of the distillation column is configured to return to the evaporation kettle.

Description

技術分野
本発明は、蒸留装置およびこの装置を用いる蒸留方法に関する。さらに詳しくは、本発明は、液体散布装置を有する蒸発釜および特定の位置に熱交換器を設けた蒸留装置、並びにこの装置を用いる蒸留方法に関する。
背景技術
一般に、回分蒸留は、蒸留釜に原液を入れ、加熱して原液を蒸発させる。蒸留塔の一番上の塔頂コンデンサーまで到達した蒸気が、冷却水を使用したコンデンサーで凝縮される。凝縮され、液化した液体を蒸留塔に還流することにより、蒸留が開始される。このような回分蒸留においてエネルギーの回収を図ることは非常に困難である。すなわち、まず、原液を加熱することから始めるため、蒸留開始まで長時間要し、エネルギーを多く消費する上、蒸留工程自体の時間が長くなる。さらに少量の原液を蒸留する場合、原液を蒸発装置に少量入れても、伝熱面として液体が入っている部分しか利用できないために、熱を液に与えることができず、なかなか装置が暖まらず、蒸留を開始するのに時間が掛かる。
さらに、多成分を含む原液を蒸留する場合、最も沸点の低い成分（最低沸点成分）から順に蒸留塔の塔頂から取り出される。そのため、最低沸点成分より沸点の高い成分の混合物は、いわゆるカットといわれ、まず、別の回収タンクに回収され、ついで、再度蒸留される。そして、再度、加熱から始めて、蒸留を行うの通常であるため、エネルギー効率が悪い。さらに、回収タンクが複数必要となる。そのうえ、多成分を分留して、蒸発装置内の残液量が減少すると、伝熱面積も液量に比例して減少する。従って、その分、蒸発量が減少し、蒸発に時間がかかる。また、蒸発量が少ないと、蒸留塔の効率の悪い条件下で運転することになり、還流を増加する必要がある。すなわち、蒸発速度が低下する上に、蒸留効率が悪化するため、より多くの液を還流で蒸留塔に戻す必要がある。そのために、蒸留時間がさらにかかる。従って、多成分の蒸留が進めば進むほど、蒸留効率（エネルギー効率）が悪くなるという問題がある。
多成分の蒸留効率を改善するための連続蒸留装置が、特開平１０−１３７５０２号公報に記載されている。この装置は、蒸留塔底部にリボイラーを設けて蒸発を行い、連続的に原液を供給しながら塔底液を中間釜液受器に戻す装置である。この装置は、２つの中間釜液受器を準備すれば良い点で、タンク数が減少するように工夫されている。しかし、中間釜液受器を複数用意するため、その分の配管およびポンプが必要となり、その上、配管に液が残るという問題がある。さらに、中間釜液受器に別の液を入れるために、配管および釜を十分に洗浄することが必要となる。従って、精密な蒸留などには不向きである。また、特開平１０−１３７５０２号公報に記載の方法は、蒸留塔と中間釜液受器との間に熱交換器を設け、この中間釜液受器から蒸留塔へ戻す液を、別の中間釜液受器へ流れる液の熱で暖めている。この装置における熱交換器は、塔底液をいったん中間釜液受器に回収する工程を導入したことに伴って、必要となったものである。中間釜液受器が必要とされなければ、熱交換器を設ける必要性はない。従って、本来必要とされない装置が付されている。さらに、蒸留塔に液を戻すためのポンプも必要となる。また、供給される原液を蒸発させるためにエネルギーが必要であり、そのためリボイラーが多量の熱を消費する。従って、多成分を含有する原液から効率的に各成分を分留し得る、簡単な蒸留装置は、いまだ提供されていないのが実情である。
発明の開示
本発明は、上記課題を解決するためになされたものであり、その目的とするところは、短時間で効率的に蒸留を行い、少ないエネルギーで多成分を効率的に分留できる蒸留装置を提供することにある。
すなわち、本発明は、液体散布装置を有する蒸発釜、蒸留塔、熱交換器、コンデンサーおよび留分受器を備えた半連続式回分蒸留装置であって、該熱交換器は、該蒸留塔と該コンデンサーとの間に設けられ、該蒸留塔に供給される原液と熱交換するように構成されており、該蒸発釜からの蒸気は該蒸留塔を通過し、該熱交換器および／または該コンデンサーで液化され、該液化された液体の一部は該留分受器に回収され、残りの液体は該蒸留塔に還流するように構成され、そして、該蒸留塔の塔底液が該蒸発釜に戻るように構成された、半連続式回分蒸留装置（以下、第１装置）を提供する。
また、本発明は、原液を、熱交換器を通過させて熱を回収しながら連続的に蒸留塔に供給し、該蒸留塔の塔底液を液体散布装置を有する蒸発釜に連続的に供給し、該蒸発釜からの蒸発成分を、蒸留塔、熱交換器、およびコンデンサーの順に通過させて分別蒸留する工程を含む、蒸留方法（以下、第１方法）を提供する。
好ましい実施態様においては、前記塔底液を回分蒸留する工程をさらに含む蒸留方法に関する。
さらに、本発明は、原液を、熱交換器を通過させて熱を回収しながら連続的に蒸留塔に供給し、該蒸留塔の塔底液を、液体散布装置を有する蒸発釜に連続的に供給し、該蒸発釜からの蒸発量を一定量に制御しつつ蒸発を行うか、または該蒸発釜の液量が一定となるように蒸発を行い、該蒸発釜からの蒸発成分を、蒸留塔、熱交換器、およびコンデンサーの順に通過させ、該蒸留塔に還流するかもしくは還流することなく分別蒸留する工程を含む蒸留方法（以下、第２方法）を提供する。
本発明は、さらに、液体散布装置を有する蒸発釜、熱交換器、コンデンサーおよび留分受器を備えた半連続式回分蒸留装置であって、該熱交換器は、該蒸発釜と該コンデンサーとの間に設けられ、該蒸発釜に供給される原液と熱交換するように構成されており、該蒸発釜からの蒸気は該熱交換器および／または該コンデンサーで液化されて留分受器に受け入れられるように構成された、半連続式回分蒸留装置（以下、第２装置）を提供する。
また、本発明は、原液を、熱交換器を通過させて液体散布装置を有する蒸発釜に連続的に供給し、該蒸発釜からの蒸発成分を、該熱交換器、およびコンデンサーの順に通過させて分別蒸留する工程を含む蒸留方法（以下、第３方法）を提供する。
発明を実施するための最良の形態
（第１装置）
本発明の蒸留装置（第１装置）を図１に示す。基本的には、液体散布装置１を有する蒸発釜２、蒸留塔３、熱交換器４、コンデンサー５および留分受器６、７の組み合わせである。熱交換器４は、蒸留塔３とコンデンサー５との間に配置され、この熱交換器４に原液９を通過させて加熱し、加熱した原液９を蒸留塔３に供給するように構成されている。
本発明の第１装置に用いる、液体散布装置１を有する蒸発釜２は、蒸発釜２の内面、特に伝熱面積にあたる部分を常に濡れた状態に保つ蒸発釜である。釜内面を常に濡れた状態に保つためには、ポンプで液体を釜内に散布し、循環させる方法でもよい。遠心力で液を持ち上げ、散布する方式が、液量が少なくなった場合および沸騰液を散布する場合、特に有効であるため好ましい。この遠心力を用いて液体を散布する方法は、本願発明者が発明した方法であり、詳しくは、日本国特許第３２５３２１２号公報（これに対応するヨーロッパ公開公報第１０３３１６４号など）に記載されている。
本発明に用いる蒸発釜２は、上記のように、伝熱面積にあたる部分が常に濡れた状態に保たれるように構成されているため、すべての伝熱面積が有効に使用され、加熱効率ひいては蒸発効率が極めて高い。従って、従来の回分法では、原液を一定量まで溜めて加熱しても、蒸発に至るまでには相当の時間を要していたが、本発明では、この時間が大幅に短縮される。しかも、本発明の装置は、加熱面が常に濡れているので、不揮発成分が乾燥して固着することも少なく、洗浄が楽な装置である。
本発明の第１装置は、多成分を含む原液を蒸留して、各成分を分留する場合、特に有効である。液体散布装置１を有する蒸発釜２を用いることにより、最後の成分を含む液の量が非常に少ない場合でも十分な伝熱面積で加熱ができる。従って、蒸発釜２に液が満たされているときと同様、ほぼ最大速度でかつ一定の蒸気量を蒸留塔３に供給することができる。従って、蒸留塔３は、ほぼ最高の効率で運転できる。従来の装置の場合、蒸気量が少なくなると、蒸留塔３自体の効率が低下するために、蒸留塔３の実効段数が減少し、還流量を増加しなければならない。従って、留分の回収に時間がかかるという問題がある。しかし、本発明の装置を用いると、蒸留塔にほぼ一定の蒸気量が提供されるので、蒸留塔の実効段数が多くなり、最適、かつ最高の効率で蒸留できるうえ、還流量も少なくてすむ。つまり、使用するエネルギー量が小さくなる。
蒸発釜２の内部に、例えば、コイル、プレートなどの伝熱体を設けることにより、さらに伝熱面積を大きくし、蒸発効率を大きくすることができる。このような伝熱体は、液体内部に設けてもよい。また、伝熱体を蒸発釜２内に配置する場合、反射板を設けておき、遠心力で持ち上げられた液体を、この反射板に当てて伝熱体上に落下させ、常に伝熱体の表面を濡れ面とすることもできる。さらに、蒸発釜自体を傾斜させることによって、伝熱面積を大きくしてもよい。また、蒸発量をモニターしながら、蒸発量が一定となるように、伝熱体の温度（加熱条件）を調整してもよい。このように伝熱面積を大きくし、一定量の蒸発量が得られるように調整することで、さらに蒸留効率が向上する。このような効果を奏し得るのは、蒸発釜が、液体散布装置、特に遠心力を用いて液体を散布する装置を有するからである。
（第１方法）
この蒸留装置（第１装置）を用いて、多成分を含む原液９を蒸留する場合（第１方法）について説明する。まず、少量の原液９を蒸発釜２に入れる。スタート時には蒸留塔３からの蒸気がないので熱交換器４に熱は供給されない。従って、原液９は低温のままである。しかし、原液９が液体散布装置１を有する蒸発釜２に入り、ある程度溜まり、液体散布装置１を有する蒸発釜２が稼動すると、蒸発釜２の液（原液９）は、すぐに温度が上昇して沸騰をはじめる。発生した蒸気は蒸留塔３を上昇して、熱交換器４および／またはコンデンサー５に到達する。そして、蒸気は凝縮されて、還流８となり、蒸留が開始される。原液９の蒸留塔３への供給が、物性に合致した計算された速度で行なわれる。蒸留塔３が安定すると一番沸点の低い成分（最低沸点成分）が蒸留塔３の塔頂を通過して、熱交換器４から直接、あるいは熱交換器４を通ってコンデンサー５で冷却されて、一部は還流され、残りは留分受器６に回収される。
原液９が供給されている間は、このように、熱が回収されながら最低沸点成分の蒸留が進行する。
最低沸点成分が留去された、蒸留塔３の塔底液には、残りの成分が含まれている。この塔底液は、液体散布装置１を有する蒸発釜２に移動する。塔底液は液体散布装置１で蒸発釜２の内壁に散布されるので、ほぼ一定速度で蒸発される。蒸留塔３はある蒸発速度で効率の最大値があり、それを外れると効率が下がる。この蒸発装置では、伝熱面積が装置内の液量にかかわらず一定、つまり、蒸発速度を常にほぼ一定にできる。従って、本発明の装置は、常に最高に近い効率で運転ができる。原液９の供給は、この蒸発釜２が一杯になるまで行われ、この間、最低沸点成分の蒸留ができる。原液９の供給が終了すると、熱回収のための熱交換器４は、効果を発揮しないが、後述のように、連続蒸留中（原液９を供給している間）は大きなエネルギーの節約に貢献している。
（第２方法）
次に、本発明の第２方法について、説明する。第１方法が低沸点の成分から逐次蒸留していく装置であるのに対して、第２の方法は、高沸点の成分から順にリボイラー、すなわち、蒸発釜２に蓄積し、回収する方法である。特に、少量の高沸点成分を原液９から回収するのに、優れた方法である。
図１に基づいて、本発明の第２方法を説明する。まず、一定量の原液９を蒸発釜２に入れる。蒸発釜２を加熱し、液体散布装置１を稼動させると、蒸発釜２の伝熱面積が全部使用できるので、液はすぐに温度が上昇して、沸騰をはじめる。本発明の装置では、蒸発量は液面に関係なく最大であり、蒸留塔３はすぐに安定する。蒸留塔３が安定したら、熱交換器４を通過させた原液９が一定速度で蒸発釜２に供給される。このとき、蒸発量が一定になるように熱の供給が制御される。すなわち、原液９の供給を続けると、高沸点の成分が蒸発釜２に溜まるため、沸騰温度が上昇する。そこで、加熱温度を上昇させることにより、蒸発量を増加させる。この操作により、蒸発量が増加され、蒸発釜２の液量が一定に保たれる。蒸留塔３への原液９の供給は、蒸留塔３の中段からトップ（蒸留塔の蒸留棚または充填物の一番上部）にかけての部位から行うことが好ましい。蒸留する物質により変わるが、最も好ましいのは、蒸留塔３のトップから原液９の供給を行うことである。なお、還流８は行ってもよく、行わなくてもよい。特に、還流８が不要な場合には、熱交換器４を使用せずに原料９を蒸留塔３のトップから供給しても熱を直接回収することができるので、有利な場合がある。
多成分を含む原液９をこの操作で分留する場合、原料９の供給が終了し、留分受器６に受け入れられた蒸留物中に含まれる最も沸点の高い成分（最高沸点成分）の濃度が規定値以下であれば、一回目の蒸留は終了する。最高沸点成分の濃度が規定値以上であれば、再度、蒸留する必要がある。留分受器６の蒸留物を、熱交換器４を通過させて、再度、蒸発釜２に供給し、留分受器７に回収し、留分受器７中の最高沸点成分が規定値以下になるように蒸留を行う。この操作により、最高沸点成分が蒸発釜２に回収される。なお、２成分系であれば、留分受器６の蒸留物は低沸点成分であり、蒸発釜２中に回収されたものは、高沸点成分である。
蒸留終了後、塔内温度が安定してから、蒸留塔３の塔底液と蒸発釜２との間の配管のバルブを閉めて、塔底液が蒸発釜２に入らないようにする。その後、蒸発釜２の加熱を止めて、最高沸点成分を蒸発釜２から抜きだす。最高沸点成分を蒸発釜２から抜き出した後に、前記バルブを開け、塔底液を蒸発釜２に入れる。次に、蒸発釜２（リボイラー）の加熱を開始して、蒸発釜２を洗浄し、その後に、洗浄した液を取り除く。ついで、留分受器７の液を、熱交換器４を通過させて蒸留塔３に供給し、同じ操作を繰り返すと、２番目の高沸点成分が蒸発釜２に回収される。この蒸留操作を順次繰り返すことによって、原液９中の沸点の異なる種々の成分が、分離、回収される。
高沸点成分が最後まで加熱されることになるという問題はあるが、この第２方法のメリットは、原液９の低沸点物質が長時間加熱されない点である。従来の方法であれば、蒸発釜２（リボイラー）に原料を全量入れて蒸留するので、原料（特に低沸点成分）が長時間、沸騰温度に曝されることになる。しかし、この方法では、低沸点成分は、蒸留塔３を通過する間しか加熱されないので、熱に弱い物質の蒸留に最適である。
（第２装置）
本発明の第２装置は、液体散布装置を有する蒸発釜、熱交換器、コンデンサーおよび留分受器を備えた半連続式回分蒸留装置であって、該蒸発釜からの蒸気は該熱交換器および／または該コンデンサーで液化されて留分受器に受け入れられるように構成され、該熱交換器は該蒸発釜と該コンデンサーとの間に設けられ、原液が該熱交換器を通過して該蒸発釜に供給されるように構成されている。第１装置とは、蒸留塔３がない点で異なる。すなわち、第１装置において、蒸留塔の機能を停止させた装置でもある。第２装置を構成するそれぞれの要素は、第１発明と同じ機能を有している。
（第３方法）
図１に基いて、本発明の第２装置を用いる蒸留方法（第３方法）を説明する。ただし、蒸留塔３はなく、蒸発釜２からの蒸気は、直接、熱交換器４に供給され、還流８はない。まず、一定量の原液９を蒸発釜２に入れる。蒸発釜２を加熱し、液体散布装置１を稼動させると、蒸発釜２の液（原液９）はすぐに温度が上昇して、沸騰を開始する。蒸発釜２からの蒸気が熱交換器４に供給されるので、供給原液９は、この熱交換器４を通過するときに、熱を回収することができる。この方法では、原液９を蒸発釜２に入れると同時に蒸発が開始できるので、運転時間の短縮になる。従来の回分式の蒸発では、蒸発釜２に液を溜めた後、加熱しているため、液を溜める時間が必要である。しかし、この方法では原液９を供給しながら加熱出来るので、原液９を蒸発釜２に溜める時間は少なくて済む。
この装置は、蒸留塔あるいは還流が不要な、高沸点成分と低沸点成分との沸点差が大きく異なる物質が含まれる原液９から低沸点成分を蒸留回収する場合に、特に有効である。熱交換器４を通過させた原液９は、蒸発釜２に連続的に供給される。原液９が供給されている間、蒸留液は留分受器６に受け入れられ、蒸留が続けられる。原液９の供給が終了しても、留分受器６の低沸点成分の濃度が規定値内である限り、蒸留は継続される。この操作は、蒸発釜２に原料９を全部入れてから蒸発させていた従来の場合に比較して、熱回収をしながら蒸留できる点で優れている。さらに、低沸点成分を除去しながら原液９を供給し得るので、低沸点成分の量に相当する量の原液９を、さらに蒸発釜２に供給できる。従って、原液９の処理量を増加し得る点でも、上記従来の場合と比べて、優れている。
本発明の蒸発釜２が液体散布装置１を備えることにより、少量の液体で伝熱面を最大利用できる。従って、従来の回分式蒸留装置のように、蒸留すべき原液９の全量を予め蒸発釜２に入れておく必要がない。また、蒸気と原液９との間で熱交換することにより、供給する原液９に熱を回収することができる。例えば、原液９が、２５℃、１０００Ｌの水である場合、発生した蒸気で供給する原液の温度を９０℃まで上昇させることにより、従来のように原液９を蒸発釜２に入れてから加熱を開始する方式（回分式）と比較して、約７４２５０Ｋｃａｌの熱が回収できる。全部の水を蒸発するとすれば、必要なエネルギーは５３９０００Ｋｃａｌであるので、回収エネルギーは１３％以上になる。
原液９の供給が終われば熱回収は無くなる。本発明の装置を用いた場合、原液９を供給し終わるときには、蒸発がかなり進行し、蒸発釜２の液量が減少しているため、従来の回分式と比較すると、蒸発釜２の容積が小さくて済む。容積が同じか、より大きい装置であっても、よいことは言うまでもない。
（実施例）
以下、実施例を挙げて本発明を説明するが、本発明はこの実施例に限定されない。
実施例１および比較例１
図１に示す第１装置を用いて２成分系の半連続回分蒸留を行う（実施例１）。実用量１０００Ｌ、ジャケットの伝熱面積が４ｍ^２の、液体散布装置１を備えた蒸発釜２を用いて、２成分系の原液９を蒸留する場合を説明する。ただし、説明の都合上、低沸点成分の沸点を１００℃として、説明する。
蒸発釜２に１０Ｌの原液９を供給し、液体散布装置１を使用して原液９を蒸発釜２の内壁に散布する。この蒸発釜２のジャケットに、１５０℃の蒸気を通して加熱を開始すると、１０Ｌの原液９は、常温（２５℃）から１分以内に１００℃まで昇温し、直ちに、約１００Ｌ／ｈｒ程度の速度で、蒸発が開始される。蒸留塔３が暖まり、還流８が開始されると、原液９を、熱交換器４を通して加熱しながら、蒸留塔３に供給する。熱交換器４で凝縮した液およびコンデンサー５で凝縮された液の一部は、蒸留塔３に還流され、一部は留分受器６に回収される。
比較例１として、実施例１と同じ容積および伝熱面積の蒸発釜で、液体散布装置１を用いない蒸発釜を用いる。この蒸発釜に原液を１０００Ｌ入れ、実施例１と同様に加熱する。伝熱面積は液体散布装置を使用する場合と液が一杯に満たされている時とは同じであるので、１０００Ｌの原液が１００℃になるまで、１００分要する。
従って、蒸発が開始するまでの時間（昇温時間）を比較すると本発明の装置では、９９分早くなる。他方、本発明の装置を用いる場合の低沸点成分の蒸留時間と、比較例１のように原液を予め全量仕込んでおく場合の低沸点成分の蒸留時間は、理論的には同じ時間である。しかし、比較例１は、液面がさがり、伝熱面積が減少するに従い、蒸発速度が遅くなり、蒸留時間が本発明の装置よりも長くなる。これに対して、本発明の装置は、液体散布手段１を有しているので、液量の多少にかかわらず、常に全ての伝熱面積を使用することができる。従って、比較例１よりも、蒸留時間が短くてすむ。このように、本発明の蒸留装置を用いると、従来の回分法と比べて少なくとも９９分＋αの蒸留時間が短縮される。
本発明の装置を用いた場合、熱交換器４において蒸気と原液９との間で熱交換されるので、その分が省エネとなる。この場合、省エネ量（ＱＫｃａｌ）は、原液（ＷＫｇ）とその上昇温度（ΔＴ）から、式Ｑ＝Ｗ×ΔＴで表される。従って、この実施例における省エネ量は、約９９０×７５＝７４２５０Ｋｃａｌである。その上、少なくとも９９分の蒸留時間の節約が図られる。
すなわち、本発明の装置を用いることにより、省エネと時間の節約という二つの効果が生み出される。本発明の装置を用いると、２成分のみならず、多成分の原液を用いた場合には、さらに時間とエネルギーが大きく節約されることが理解される。
実施例２および比較例２
Ａ成分を４５重量％、Ｂ成分を４５重量％、およびＣ成分を１０重量％含有する原液を蒸留する場合について説明する。沸点はＡ＜Ｂ＜Ｃである。この場合も、説明の都合上、Ａ成分の沸点を１００℃として説明する。
実用量１００００Ｌ、伝熱面積が約２５ｍ^２である蒸発釜を用い、本発明の液体散布装置１を有する蒸発釜２と熱交換器４とを有する装置を用いて半連続回分蒸留する場合（実施例２の方法）と、液体散布装置１および熱交換器４を有しない蒸発釜２に、当初から１００００Ｌの原液を入れて蒸留した場合（比較例２の方法）との比較を行う。
実施例２の場合、原液を１００Ｌ程度蒸発釜に仕込み、ジャケットを１５０℃の蒸気で加熱し、液体散布装置１を回転させると、温度の上昇が始まり、常温（２５℃）から１００℃まで、１分以内に上昇する。これに対して、比較例２の方法では、１００００Ｌの液が１００℃まで到達する時間は１００分かかることになる。蒸発を開始して、蒸留塔３が暖まる時間は、どちらの方法でも同じであるので、実施例２の方法は、比較例２の方法と比較して、９９分短縮される。
次に、蒸留を開始し、原液９を熱交換器４を通して供給する本発明の方法では、熱回収は７４２５００Ｋｃａｌとなる。４５重量％のＡ成分を除去する時間は、実施例２の方法を用いると、比較例２の方法を用いるよりも短くなる。これは、実施例２は液体散布装置１を使用するため、液量が少なくなっても、伝熱面積として最大の２５ｍ^２使用できるからである。液体散布装置１を使用しない比較例２では、Ａ成分の蒸発に伴って、液量が減少し、伝熱面積が減少するため、時間は余分にかかり、エネルギーロスがおこる。従って、本発明の方法の方が、エネルギーが効率良く回収され、熱効率が高いことが明らかである。
１００００Ｌの原液を処理して、Ａ成分が留去されると、実施例２および比較例２ともに、４５重量％分の容量が減少する。この残りの液にはＢ成分とＣ成分とが含まれているので、Ｂ成分を次に蒸留する。Ｂ成分の蒸留速度は、本発明の方法も比較例の方法も理論的には同じである。しかし、液体散布装置を使用しない従来法（比較例２）では、４５重量％のＡ成分が蒸発することによって、その量に相当する伝熱面積が使用されないので蒸発速度が減少する。そのため蒸留時間がさらに必要となる。
Ｂ成分が蒸留されると、最後のＣ成分は１０００Ｌ程度残る。
このＢ成分の回収が終了するころに、さらに熱交換器４を通した、Ａ成分、Ｂ成分およびＣ成分を含む原液を連続的に供給することにより、さらに、９０００Ｌの原液を連続的に処理し、Ａ成分、Ｂ成分およびＣ成分を分離することができる。すなわち、本発明の方法を用いれば、昇温の時間と昇温のためのエネルギーを最小にして（すなわち、熱回収を行いながら）、さらに９０００Ｌの原液を処理できる。これに対して比較例２の方法では、昇温時間と昇温のためのエネルギーが必要となる。
産業上の利用可能性
従来、回分蒸留では原液を蒸発釜に入れて加熱を開始しなければならなかったが、本発明の液体散布装置を有する蒸発釜を用いる場合には、連続的にしかも早い蒸発速度で蒸留できるので、蒸発釜の大きさは原液の量よりも小さい容量でよい。たとえば、低沸点成分が原液中に５０容量％含まれている場合、低沸点成分が除去された液（塔底液）が蒸発釜一杯になるまで原液を供給できる。つまり、従来の２倍の液量を処理できることになり、設備が２倍の能力となる。
従来の外部循環式の加熱法でも低沸点成分の蒸留はできるが、それは液が循環できる間だけである。さらに、この従来の方法は、最初から相当量の液量が必要であり、液量が少なくなる後半では外部循環ができなくなり、蒸留塔が運転できなくなる。これに対して、本発明の蒸留装置には液体散布装置が備えられているので、液量が少なくなっても遠心力で液体を汲み上げ、蒸発釜の内壁に散布することにより、蒸発釜の伝熱面積がすべて利用できる。従って、たとえ少量になっても蒸気量が一定となり、蒸留塔は最高の効率で運転できる。
【図面の簡単な説明】
図１は、本発明の蒸留装置の一例を示す図である。Technical field
The present invention relates to a distillation apparatus and a distillation method using this apparatus. More specifically, the present invention relates to an evaporation pot having a liquid spraying device, a distillation apparatus provided with a heat exchanger at a specific position, and a distillation method using the apparatus.
Background art
In general, batch distillation is performed by putting a stock solution in a distillation kettle and evaporating the stock solution by heating. The vapor that reaches the top condenser of the distillation tower is condensed in the condenser using cooling water. Distillation is started by refluxing the condensed and liquefied liquid to the distillation column. It is very difficult to recover energy in such batch distillation. That is, first, since the stock solution is heated, it takes a long time to start distillation, consuming a lot of energy, and the time of the distillation process itself becomes longer. Furthermore, when distilling a small amount of undiluted solution, even if a small amount of undiluted solution is put into the evaporator, only the part containing the liquid can be used as the heat transfer surface, so heat cannot be given to the solution and the device does not warm up easily. It takes time to start the distillation.
Furthermore, when distilling a stock solution containing multiple components, components having the lowest boiling point (lowest boiling point component) are taken out from the top of the distillation column in order. Therefore, a mixture of components having a boiling point higher than the lowest boiling component is called a so-called cut, and is first recovered in another recovery tank and then distilled again. And since it is normal to start distillation again and to perform distillation, energy efficiency is bad. Furthermore, a plurality of recovery tanks are required. In addition, when multiple components are fractionated and the residual liquid amount in the evaporator decreases, the heat transfer area also decreases in proportion to the liquid amount. Therefore, the amount of evaporation decreases correspondingly, and it takes time to evaporate. Further, if the evaporation amount is small, the distillation column is operated under inefficient conditions, and it is necessary to increase the reflux. That is, since the evaporation rate is lowered and the distillation efficiency is deteriorated, it is necessary to return more liquid to the distillation column by reflux. For this reason, it takes more time for distillation. Therefore, there is a problem that the distillation efficiency (energy efficiency) becomes worse as the multi-component distillation progresses.
A continuous distillation apparatus for improving the multicomponent distillation efficiency is described in JP-A-10-137502. In this apparatus, a reboiler is provided at the bottom of the distillation column to evaporate, and the column bottom liquid is returned to the intermediate kettle liquid receiver while continuously supplying the stock solution. This device is devised to reduce the number of tanks in that two intermediate pot liquid receivers are prepared. However, since a plurality of intermediate pot liquid receivers are prepared, there is a problem that the pipes and pumps corresponding to the intermediate pot liquid receivers are required, and the liquid remains in the pipes. Further, in order to put another liquid into the intermediate pot liquid receiver, it is necessary to sufficiently clean the pipe and the hook. Therefore, it is not suitable for precise distillation. Further, in the method described in JP-A-10-137502, a heat exchanger is provided between the distillation column and the intermediate kettle liquid receiver, and the liquid returned from the intermediate kettle liquid receiver to the distillation tower is transferred to another intermediate tank. It is warmed by the heat of the liquid flowing to the pot receiver. The heat exchanger in this apparatus became necessary with the introduction of a step of once collecting the column bottom liquid into the intermediate kettle liquid receiver. If an intermediate pot receiver is not required, there is no need to provide a heat exchanger. Therefore, a device which is not originally required is attached. Furthermore, a pump for returning the liquid to the distillation column is also required. Also, energy is required to evaporate the supplied stock solution, so that the reboiler consumes a large amount of heat. Therefore, a simple distillation apparatus that can efficiently fractionate each component from a stock solution containing multiple components has not yet been provided.
Disclosure of the invention
The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a distillation apparatus that can efficiently perform distillation in a short time and efficiently fractionate multiple components with less energy. There is to do.
That is, the present invention is a semi-continuous batch distillation apparatus provided with an evaporation kettle having a liquid spraying apparatus, a distillation tower, a heat exchanger, a condenser and a fraction receiver, and the heat exchanger includes the distillation tower and the distillation tower. Provided between the condenser and configured to exchange heat with a stock solution supplied to the distillation column, and steam from the evaporation kettle passes through the distillation column, and the heat exchanger and / or the A condenser is liquefied, a part of the liquefied liquid is recovered in the fraction receiver, the remaining liquid is configured to reflux to the distillation column, and the bottom liquid of the distillation column is evaporated. A semi-continuous batch distillation apparatus (hereinafter referred to as a first apparatus) configured to return to a kettle is provided.
In the present invention, the stock solution is continuously supplied to a distillation column while passing through a heat exchanger and recovering heat, and the bottom liquid of the distillation column is continuously supplied to an evaporation kettle having a liquid spraying device. And a distillation method (hereinafter referred to as a first method) comprising a step of subjecting the evaporation component from the evaporation kettle to fractional distillation through a distillation column, a heat exchanger, and a condenser in this order.
In a preferred embodiment, the present invention relates to a distillation method further comprising a step of batch distillation of the column bottom liquid.
Further, in the present invention, the stock solution is continuously supplied to a distillation column while passing through a heat exchanger and recovering heat, and the bottom liquid of the distillation column is continuously supplied to an evaporation kettle having a liquid spraying device. And evaporating while controlling the evaporation amount from the evaporation kettle to a constant amount, or evaporating so that the liquid amount of the evaporation kettle becomes constant, and evaporating components from the evaporation kettle , A heat exchanger, and a condenser, and a distillation method (hereinafter referred to as a second method) including a step of refluxing to the distillation column or fractional distillation without refluxing.
The present invention further comprises a semi-continuous batch distillation apparatus comprising an evaporation kettle having a liquid spraying device, a heat exchanger, a condenser and a fraction receiver, wherein the heat exchanger comprises the evaporating kettle, the condenser, The steam from the evaporating kettle is liquefied by the heat exchanger and / or the condenser and sent to the fraction receiver. Provided is a semi-continuous batch distillation apparatus (hereinafter, second apparatus) configured to be accepted.
In the present invention, the stock solution is continuously supplied to the evaporation kettle having the liquid spraying device through the heat exchanger, and the evaporated components from the evaporation kettle are passed in the order of the heat exchanger and the condenser. A distillation method including a step of fractional distillation (hereinafter referred to as a third method).
BEST MODE FOR CARRYING OUT THE INVENTION
(First device)
A distillation apparatus (first apparatus) of the present invention is shown in FIG. Basically, it is a combination of an evaporation kettle 2 having a liquid spraying device 1, a distillation column 3, a heat exchanger 4, a condenser 5 and fraction receivers 6 and 7. The heat exchanger 4 is disposed between the distillation column 3 and the condenser 5, and is configured so that the stock solution 9 is passed through the heat exchanger 4 and heated, and the heated stock solution 9 is supplied to the distillation column 3. Yes.
The evaporating pot 2 having the liquid spraying apparatus 1 used in the first apparatus of the present invention is an evaporating pot that always keeps the inner surface of the evaporating pot 2, particularly the portion corresponding to the heat transfer area, wet. In order to keep the inner surface of the kettle always wet, a method may be used in which liquid is sprayed into the kettle with a pump and circulated. The method of lifting and spraying the liquid by centrifugal force is preferable because it is particularly effective when the amount of liquid decreases and when the boiling liquid is sprayed. The method of spraying a liquid using this centrifugal force is a method invented by the present inventor, and is described in detail in Japanese Patent No. 3253212 (European Publication No. 1033164 corresponding thereto). Yes.
Since the evaporating pot 2 used in the present invention is configured so that the portion corresponding to the heat transfer area is always kept wet as described above, all the heat transfer areas are effectively used, and the heating efficiency and therefore Evaporation efficiency is extremely high. Therefore, in the conventional batch method, even if the stock solution is accumulated and heated up to a certain amount, it takes a considerable time to evaporate. However, in the present invention, this time is greatly shortened. In addition, since the heating surface is always wet, the apparatus of the present invention is less likely to dry and stick to the non-volatile components, and is easy to clean.
The first apparatus of the present invention is particularly effective when a stock solution containing multiple components is distilled to fractionate each component. By using the evaporation pot 2 having the liquid spraying device 1, heating can be performed with a sufficient heat transfer area even when the amount of the liquid containing the last component is very small. Therefore, as in the case where the evaporation kettle 2 is filled with the liquid, a constant amount of steam can be supplied to the distillation column 3 at a substantially maximum speed. Therefore, the distillation column 3 can be operated with almost the highest efficiency. In the case of a conventional apparatus, when the amount of steam decreases, the efficiency of the distillation column 3 itself decreases, so the effective number of stages of the distillation column 3 decreases, and the reflux rate must be increased. Therefore, there is a problem that it takes time to collect the fraction. However, when the apparatus of the present invention is used, a substantially constant amount of steam is provided to the distillation column, so the number of effective stages of the distillation column is increased, and distillation can be performed with optimum and maximum efficiency, and the reflux amount can be reduced. . That is, the amount of energy used is reduced.
For example, by providing a heat transfer body such as a coil or a plate inside the evaporation pot 2, the heat transfer area can be further increased and the evaporation efficiency can be increased. Such a heat transfer body may be provided inside the liquid. In addition, when the heat transfer body is arranged in the evaporation pot 2, a reflection plate is provided, and the liquid lifted by the centrifugal force is applied to the reflection plate and dropped onto the heat transfer body. The surface can also be a wetted surface. Furthermore, the heat transfer area may be increased by inclining the evaporation kettle itself. Further, while monitoring the evaporation amount, the temperature of the heat transfer body (heating condition) may be adjusted so that the evaporation amount becomes constant. In this way, the distillation efficiency is further improved by increasing the heat transfer area and adjusting so as to obtain a certain amount of evaporation. The reason why such an effect can be obtained is that the evaporating pot has a liquid spraying device, particularly a device for spraying liquid using centrifugal force.
(First method)
The case (1st method) of distilling the undiluted | stock solution 9 containing a multicomponent using this distillation apparatus (1st apparatus) is demonstrated. First, a small amount of the stock solution 9 is put into the evaporation kettle 2. Since there is no steam from the distillation column 3 at the start, heat is not supplied to the heat exchanger 4. Therefore, the stock solution 9 remains at a low temperature. However, when the stock solution 9 enters the evaporating pot 2 having the liquid spraying device 1 and accumulates to some extent and the evaporating pot 2 having the liquid spraying device 1 is operated, the temperature of the liquid in the evaporating pot 2 (raw solution 9) immediately rises. Start boiling. The generated steam ascends the distillation column 3 and reaches the heat exchanger 4 and / or the condenser 5. Then, the steam is condensed to reflux 8 and distillation is started. The stock solution 9 is supplied to the distillation column 3 at a calculated speed that matches the physical properties. When the distillation column 3 is stabilized, the component having the lowest boiling point (lowest boiling point component) passes through the top of the distillation column 3 and is cooled by the condenser 5 directly from the heat exchanger 4 or through the heat exchanger 4. , Part is refluxed and the rest is collected in the fraction receiver 6.
While the stock solution 9 is being supplied, distillation of the lowest boiling point component proceeds in this way while heat is recovered.
The bottom component of the distillation column 3 from which the lowest boiling point component has been distilled off contains the remaining components. This tower bottom liquid moves to the evaporation pot 2 having the liquid spraying device 1. Since the column bottom liquid is sprayed on the inner wall of the evaporation pot 2 by the liquid spraying device 1, it is evaporated at a substantially constant speed. The distillation column 3 has a maximum value of efficiency at a certain evaporation rate, and the efficiency decreases when the value is exceeded. In this evaporator, the heat transfer area is constant regardless of the amount of liquid in the apparatus, that is, the evaporation rate can be kept almost constant. Therefore, the device of the present invention can always be operated with efficiency close to the maximum. The stock solution 9 is supplied until the evaporation kettle 2 is full, during which the lowest boiling point component can be distilled. When the supply of the stock solution 9 is completed, the heat exchanger 4 for heat recovery does not exhibit an effect, but contributes to a great energy saving during continuous distillation (while the stock solution 9 is being supplied), as will be described later. doing.
(Second method)
Next, the second method of the present invention will be described. Whereas the first method is an apparatus that sequentially distills from components having a low boiling point, the second method is a method of accumulating and collecting in the reboiler, that is, the evaporation kettle 2 in order from the component having a high boiling point. . In particular, it is an excellent method for recovering a small amount of high-boiling components from the stock solution 9.
The second method of the present invention will be described based on FIG. First, a certain amount of the stock solution 9 is put into the evaporation kettle 2. When the evaporation kettle 2 is heated and the liquid spraying device 1 is operated, the entire heat transfer area of the evaporation kettle 2 can be used, so that the temperature immediately rises and begins to boil. In the apparatus of the present invention, the amount of evaporation is maximum regardless of the liquid level, and the distillation column 3 is stabilized immediately. When the distillation column 3 is stabilized, the stock solution 9 passed through the heat exchanger 4 is supplied to the evaporation kettle 2 at a constant speed. At this time, the supply of heat is controlled so that the evaporation amount is constant. That is, when the supply of the stock solution 9 is continued, the boiling point rises because the high boiling point component accumulates in the evaporation pot 2. Therefore, the amount of evaporation is increased by increasing the heating temperature. By this operation, the evaporation amount is increased, and the liquid amount in the evaporation pot 2 is kept constant. The supply of the stock solution 9 to the distillation column 3 is preferably performed from a portion from the middle stage of the distillation column 3 to the top (the top of the distillation column or the top of the packing). Although it depends on the substance to be distilled, it is most preferable to supply the stock solution 9 from the top of the distillation column 3. The reflux 8 may or may not be performed. In particular, when the reflux 8 is unnecessary, it may be advantageous because heat can be recovered directly even if the raw material 9 is supplied from the top of the distillation column 3 without using the heat exchanger 4.
When fractionating the stock solution 9 containing multiple components by this operation, the supply of the raw material 9 is completed, and the concentration of the highest boiling component (highest boiling component) contained in the distillate received in the fraction receiver 6 If is below the specified value, the first distillation is finished. If the concentration of the highest boiling point component is not less than the specified value, it must be distilled again. The distillate of the fraction receiver 6 is passed through the heat exchanger 4 and supplied again to the evaporation kettle 2 and recovered in the fraction receiver 7. The highest boiling point component in the fraction receiver 7 is the specified value. Distill so that: By this operation, the highest boiling point component is recovered in the evaporation pot 2. In the case of a two-component system, the distillate in the fraction receiver 6 is a low-boiling component, and the one recovered in the evaporation kettle 2 is a high-boiling component.
After the distillation is completed, after the temperature in the column is stabilized, the valve of the pipe between the column bottom liquid of the distillation column 3 and the evaporation kettle 2 is closed so that the column bottom liquid does not enter the evaporation kettle 2. Thereafter, the heating of the evaporation kettle 2 is stopped, and the highest boiling point component is extracted from the evaporation kettle 2. After extracting the highest boiling point component from the evaporation kettle 2, the valve is opened and the bottom liquid is put into the evaporation kettle 2. Next, heating of the evaporating pot 2 (reboiler) is started to wash the evaporating pot 2, and then the washed liquid is removed. Next, the liquid in the fraction receiver 7 is supplied to the distillation column 3 through the heat exchanger 4 and the same operation is repeated. Then, the second high boiling point component is recovered in the evaporation kettle 2. By sequentially repeating this distillation operation, various components having different boiling points in the stock solution 9 are separated and recovered.
Although there is a problem that the high boiling point component is heated to the end, the merit of the second method is that the low boiling point substance of the stock solution 9 is not heated for a long time. In the case of the conventional method, since all the raw material is distilled in the evaporation kettle 2 (reboiler), the raw material (particularly low boiling point component) is exposed to the boiling temperature for a long time. However, in this method, the low boiling point component is heated only while passing through the distillation column 3, and is optimal for distillation of a material that is weak against heat.
(Second device)
The second apparatus of the present invention is a semi-continuous batch distillation apparatus having an evaporation kettle having a liquid spraying device, a heat exchanger, a condenser and a fraction receiver, wherein the vapor from the kettle is the heat exchanger. And / or configured to be liquefied by the condenser and received by the fraction receiver, the heat exchanger being provided between the evaporation kettle and the condenser, and the stock solution passing through the heat exchanger and the It is comprised so that it may be supplied to an evaporation pot. It differs from the first device in that there is no distillation column 3. That is, in the first apparatus, the function of the distillation column is also stopped. Each element constituting the second device has the same function as the first invention.
(Third method)
Based on FIG. 1, a distillation method (third method) using the second apparatus of the present invention will be described. However, there is no distillation column 3, the steam from the evaporation kettle 2 is directly supplied to the heat exchanger 4, and there is no reflux 8. First, a certain amount of the stock solution 9 is put into the evaporation kettle 2. When the evaporation kettle 2 is heated and the liquid spraying device 1 is operated, the temperature of the liquid in the evaporation kettle 2 (stock solution 9) immediately rises and starts boiling. Since the steam from the evaporation kettle 2 is supplied to the heat exchanger 4, the supply stock solution 9 can recover heat when passing through the heat exchanger 4. In this method, since the evaporation can be started at the same time as the stock solution 9 is put into the evaporation kettle 2, the operation time is shortened. In the conventional batch-type evaporation, since the liquid is stored in the evaporation pot 2 and then heated, it takes time to store the liquid. However, in this method, heating can be performed while supplying the stock solution 9, so that the time for storing the stock solution 9 in the evaporation kettle 2 can be reduced.
This apparatus is particularly effective when distilling and recovering a low boiling point component from a stock solution 9 containing a substance having a large difference in boiling point between a high boiling point component and a low boiling point component, which does not require a distillation column or reflux. The stock solution 9 that has passed through the heat exchanger 4 is continuously supplied to the evaporation kettle 2. While the stock solution 9 is being supplied, the distillate is received by the fraction receiver 6 and distillation is continued. Even if the supply of the stock solution 9 is completed, the distillation is continued as long as the concentration of the low-boiling component in the fraction receiver 6 is within the specified value. This operation is superior in that it can be distilled while recovering heat, as compared with the conventional case where all the raw material 9 is put in the evaporation pot 2 and evaporated. Furthermore, since the stock solution 9 can be supplied while removing the low-boiling components, the stock solution 9 corresponding to the amount of the low-boiling components can be further supplied to the evaporation kettle 2. Therefore, it is also superior to the conventional case in that the processing amount of the stock solution 9 can be increased.
When the evaporation pot 2 of the present invention is provided with the liquid spraying device 1, the heat transfer surface can be utilized to the maximum with a small amount of liquid. Therefore, unlike the conventional batch distillation apparatus, it is not necessary to put the whole amount of the stock solution 9 to be distilled in the evaporation kettle 2 in advance. Further, heat can be recovered in the supplied stock solution 9 by exchanging heat between the steam and the stock solution 9. For example, when the undiluted solution 9 is water at 25 ° C. and 1000 L, the temperature of the undiluted solution supplied with the generated steam is increased to 90 ° C. Compared to the starting method (batch method), about 74250 Kcal heat can be recovered. If all the water is evaporated, the required energy is 539000 Kcal, so the recovered energy is 13% or more.
When the supply of the stock solution 9 is finished, the heat recovery is lost. When the apparatus of the present invention is used, when the undiluted solution 9 is completely supplied, the evaporation proceeds considerably and the amount of the liquid in the evaporating pot 2 is reduced. Therefore, the volume of the evaporating pot 2 is smaller than that in the conventional batch type. It's small. It goes without saying that devices with the same or larger volume may be used.
(Example)
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to this Example.
Example 1 and Comparative Example 1
A two-component semi-continuous batch distillation is performed using the first apparatus shown in FIG. 1 (Example 1). Practical amount 1000L, jacket heat transfer area 4m ² A case where the two-component stock solution 9 is distilled using the evaporation pot 2 equipped with the liquid spraying device 1 will be described. However, for convenience of explanation, the boiling point of the low boiling point component is assumed to be 100 ° C.
A 10 L stock solution 9 is supplied to the evaporation kettle 2, and the stock solution 9 is sprayed on the inner wall of the evaporation kettle 2 using the liquid spraying device 1. When heating is started through steam at 150 ° C. through the jacket of the evaporating pot 2, 10 L of the stock solution 9 is heated from room temperature (25 ° C.) to 100 ° C. within 1 minute, and immediately at a rate of about 100 L / hr. Then evaporation starts. When the distillation column 3 is warmed and the reflux 8 is started, the stock solution 9 is supplied to the distillation column 3 while being heated through the heat exchanger 4. A part of the liquid condensed in the heat exchanger 4 and a part of the liquid condensed in the condenser 5 are refluxed to the distillation column 3, and a part is collected in the fraction receiver 6.
As Comparative Example 1, an evaporation pot having the same volume and heat transfer area as in Example 1 and not using the liquid spraying device 1 is used. 1000 L of stock solution is put into this evaporation kettle and heated in the same manner as in Example 1. Since the heat transfer area is the same as when the liquid spraying device is used and when the liquid is fully filled, it takes 100 minutes for the 1000 L stock solution to reach 100 ° C.
Therefore, when the time until the evaporation starts (temperature rising time) is compared, the apparatus of the present invention is 99 minutes earlier. On the other hand, the distillation time of the low boiling point component when using the apparatus of the present invention and the distillation time of the low boiling point component when the whole amount of the stock solution is charged in advance as in Comparative Example 1 are theoretically the same time. However, in Comparative Example 1, as the liquid level decreases and the heat transfer area decreases, the evaporation rate becomes slower and the distillation time becomes longer than the apparatus of the present invention. On the other hand, since the apparatus of the present invention has the liquid spraying means 1, it can always use the entire heat transfer area regardless of the amount of liquid. Therefore, the distillation time is shorter than in Comparative Example 1. Thus, when the distillation apparatus of the present invention is used, the distillation time of at least 99 minutes + α is shortened as compared with the conventional batch method.
When the apparatus of the present invention is used, heat is exchanged between the steam and the stock solution 9 in the heat exchanger 4, so that energy is saved. In this case, the energy saving amount (QKcal) is expressed by the equation Q = W × ΔT from the stock solution (WKg) and its rising temperature (ΔT). Therefore, the energy saving amount in this embodiment is about 990 × 75 = 74250 Kcal. In addition, a distillation time saving of at least 99 minutes is achieved.
That is, by using the apparatus of the present invention, two effects of energy saving and time saving are produced. It is understood that when the apparatus of the present invention is used, not only two components but also a multicomponent stock solution is used, time and energy are further saved.
Example 2 and Comparative Example 2
The case of distilling a stock solution containing 45% by weight of component A, 45% by weight of component B, and 10% by weight of component C will be described. The boiling point is A <B <C. In this case as well, for convenience of explanation, the boiling point of the component A is assumed to be 100 ° C.
Practical use 10,000L, Heat transfer area is about 25m ² When the semi-continuous batch distillation is performed using the evaporating pot which is the above and using the apparatus having the evaporating pot 2 having the liquid spraying apparatus 1 and the heat exchanger 4 of the present invention (method of Example 2), the liquid spraying apparatus 1 Comparison is made with the case where 10000 L of the stock solution is put into the evaporation kettle 2 not having the heat exchanger 4 and distilled from the beginning (method of Comparative Example 2).
In the case of Example 2, when the stock solution is charged in an evaporation pot of about 100 L, the jacket is heated with steam at 150 ° C., and the liquid spraying device 1 is rotated, the temperature starts to rise, from room temperature (25 ° C.) to 100 ° C., Ascend within 1 minute. On the other hand, in the method of Comparative Example 2, it takes 100 minutes for the 10000 L of liquid to reach 100 ° C. Since the time for starting the evaporation and warming the distillation column 3 is the same for both methods, the method of Example 2 is shortened by 99 minutes compared to the method of Comparative Example 2.
Next, in the method of the present invention in which distillation is started and the stock solution 9 is supplied through the heat exchanger 4, the heat recovery is 742500 Kcal. The time for removing 45% by weight of the A component is shorter when the method of Example 2 is used than when the method of Comparative Example 2 is used. This is because the second embodiment uses the liquid spraying device 1, so even if the amount of liquid decreases, the maximum heat transfer area is 25 m. ² This is because it can be used. In Comparative Example 2 in which the liquid spraying device 1 is not used, the amount of liquid decreases and the heat transfer area decreases as the A component evaporates, so that it takes time and energy loss occurs. Therefore, it is clear that the method of the present invention recovers energy more efficiently and has higher thermal efficiency.
When the 10000 L undiluted solution is processed and the component A is distilled off, the volume corresponding to 45% by weight is reduced in both Example 2 and Comparative Example 2. Since this remaining liquid contains the B component and the C component, the B component is then distilled. The distillation rate of the component B is theoretically the same in the method of the present invention and the method of the comparative example. However, in the conventional method that does not use the liquid spraying device (Comparative Example 2), the evaporation rate is reduced because 45% by weight of the A component evaporates, and the heat transfer area corresponding to the amount is not used. Therefore, further distillation time is required.
When the B component is distilled, about 1000 L of the last C component remains.
When the recovery of the B component is completed, the stock solution containing the A component, the B component, and the C component, which is further passed through the heat exchanger 4, is continuously supplied to further process 9000L of the stock solution. In addition, the A component, the B component, and the C component can be separated. That is, by using the method of the present invention, it is possible to further process 9000 L of the stock solution while minimizing the time for heating and the energy for heating (that is, while performing heat recovery). On the other hand, the method of Comparative Example 2 requires a temperature raising time and energy for temperature raising.
Industrial applicability
Conventionally, in batch distillation, it has been necessary to start heating by putting the stock solution in an evaporation kettle, but when using an evaporation kettle having the liquid spraying device of the present invention, it can be distilled continuously and at a high evaporation rate. The capacity of the evaporation pot may be smaller than the amount of the stock solution. For example, when the low boiling point component is contained in 50% by volume in the stock solution, the stock solution can be supplied until the liquid from which the low boiling point component has been removed (column bottom liquid) is full. That is, twice the amount of liquid as before can be processed, and the capacity of the facility is doubled.
The conventional external circulation heating method can still distill low boiling components, but only while the liquid can be circulated. Furthermore, this conventional method requires a considerable amount of liquid from the beginning, and in the latter half when the amount of liquid decreases, external circulation cannot be performed and the distillation column cannot be operated. On the other hand, since the distillation apparatus of the present invention is equipped with a liquid spraying device, even if the amount of liquid is reduced, the liquid is pumped up by centrifugal force and sprayed on the inner wall of the evaporation pot. All thermal areas are available. Therefore, even if the amount is small, the amount of steam is constant, and the distillation column can be operated with the highest efficiency.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a distillation apparatus of the present invention.

Claims

A semi-continuous batch distillation apparatus comprising an evaporation kettle having a liquid spraying device, a distillation column, a heat exchanger, a condenser and a fraction receiver, wherein the heat exchanger is disposed between the distillation column and the condenser. Provided, and configured to exchange heat with the stock solution supplied to the distillation column, and the steam from the evaporation kettle passes through the distillation column and is liquefied by the heat exchanger and / or the condenser, Part of the liquefied liquid is collected in the fraction receiver, the remaining liquid is configured to reflux to the distillation column, and the bottom liquid of the distillation column is configured to return to the evaporation kettle. A semi-continuous batch distillation apparatus.

The stock solution is continuously supplied to the distillation column while passing through the heat exchanger and the heat is recovered, and the bottom liquid of the distillation column is continuously supplied to the evaporation kettle having the liquid spraying device, A distillation method comprising the step of fractionally distilling the evaporation component from the column through a distillation column, a heat exchanger, and a condenser in this order.

The method according to claim 2, further comprising batch distillation of the bottom liquid.

The stock solution is continuously supplied to the distillation column while passing through the heat exchanger and the heat is recovered, and the bottom liquid of the distillation column is continuously supplied to the evaporation kettle having the liquid spraying device, Evaporating while controlling the amount of evaporation from a constant amount, or evaporating so that the amount of liquid in the evaporation kettle is constant, and evaporating components from the evaporation kettle into a distillation column, heat exchanger, and A distillation method comprising a step of passing in the order of a condenser and refluxing to the distillation column or fractional distillation without refluxing.

A semi-continuous batch distillation apparatus comprising an evaporation kettle having a liquid spraying device, a heat exchanger, a condenser and a fraction receiver, the heat exchanger being provided between the evaporating kettle and the condenser; It is configured to exchange heat with the stock solution supplied to the evaporating kettle, and the vapor from the evaporating kettle is configured to be liquefied by the heat exchanger and / or the condenser and received by the fraction receiver. Semi-continuous batch distillation equipment.

A step of continuously feeding the undiluted solution to an evaporation kettle having a liquid spraying device through a heat exchanger, and fractionally distilling the evaporated components from the evaporation kettle in order of the heat exchanger and a condenser. Including a distillation method.