JP2681667B2 - Method for separating acetic acid / water / vinyl acetate mixture - Google Patents

Method for separating acetic acid / water / vinyl acetate mixture

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Publication number
JP2681667B2
JP2681667B2 JP24486688A JP24486688A JP2681667B2 JP 2681667 B2 JP2681667 B2 JP 2681667B2 JP 24486688 A JP24486688 A JP 24486688A JP 24486688 A JP24486688 A JP 24486688A JP 2681667 B2 JP2681667 B2 JP 2681667B2
Authority
JP
Japan
Prior art keywords
vinyl acetate
water
acetic acid
column
liquid
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 - Fee Related
Application number
JP24486688A
Other languages
Japanese (ja)
Other versions
JPH0291044A (en
Inventor
俊勝 高橋
博 船津
忠司 宮
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Synthetic Chemical Industry Co Ltd
Original Assignee
Nippon Synthetic Chemical Industry Co Ltd
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Priority to JP24486688A priority Critical patent/JP2681667B2/en
Publication of JPH0291044A publication Critical patent/JPH0291044A/en
Application granted granted Critical
Publication of JP2681667B2 publication Critical patent/JP2681667B2/en
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Description

【発明の詳細な説明】 [産業上の利用分野] 本発明は酢酸ビニル製造プラントの省エネルギー対策
に関するものである。
DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to energy saving measures for a vinyl acetate production plant.

[従来の技術] 酢酸ビニルはパラジウムあるいはパラジウム塩を主触
媒としてエチレン、酢酸及び酸素を気相下で反応させて
製造される。
[Prior Art] Vinyl acetate is produced by reacting ethylene, acetic acid and oxygen in the gas phase with palladium or a palladium salt as a main catalyst.

該反応において得られる反応生成ガスには酢酸ビニル
以外に未反応のエチレン、未反応の酸素、未反応の酢
酸、水、炭酸ガス更には不活性ガス等が含まれている。
In addition to vinyl acetate, the reaction product gas obtained in the reaction contains unreacted ethylene, unreacted oxygen, unreacted acetic acid, water, carbon dioxide gas and an inert gas.

これらの不純物を除去するために、まず反応生成ガス
混合物を多段階で冷却し、得られる酢酸/水/酢酸ビニ
ルを主成分とする凝縮物を蒸留に付し、一方未凝縮成分
は反応器に再循環される。蒸留はまず第1の蒸留塔で酢
酸ビニル/水の混合物を頂部から、一方酢酸を底部から
留去させ、上記混合物は更に蒸留され、純粋な酢酸ビニ
ルへと精製されるのである。
To remove these impurities, the reaction product gas mixture is first cooled in multiple stages and the resulting acetic acid / water / vinyl acetate-based condensate is subjected to distillation, while the uncondensed components are fed to the reactor. Is recycled. The distillation is carried out by first distilling off the vinyl acetate / water mixture from the top and acetic acid from the bottom in the first distillation column, the mixture being further distilled and purified to pure vinyl acetate.

[発明が解決しようとする課題] 省資源、省エネルギー時代の到来を迎えている今日、
化学プラントでも省エネルギー対策が重要な課題の1つ
として取り上げられてきており、酢酸ビニル製造プラン
トもその例外ではない。かかる対策として工程の改善や
各種装置の改善等、種々の方策がとられているが、最も
重要なエネルギー対策はプラントにつきものである利用
価値が殆どなく廃棄せざるを得ない低温蒸気、即ち、廃
蒸気の有効利用である。
[Problems to be solved by the invention] Today is the era of resource saving and energy saving.
Energy saving measures have been taken up as one of the important issues in chemical plants, and vinyl acetate production plants are no exception. As such measures, various measures such as improvement of processes and improvements of various devices have been taken, but the most important energy measure is the low-temperature steam that has almost no utility value and is unavoidable because it belongs to the plant, that is, This is the effective use of waste steam.

従来、酢酸ビニルプラントの省エネルギー対策を記載
した文献として、例えば、特開昭56−79639号公報に
は、酢酸/水/酢酸ビニル混合物の蒸留による分離の際
に、含水量の異なる該混合物を別々に蒸留塔へ供給する
方法が、又特開昭58−39643号公報には該混合物の分離
の際に、蒸留塔に水を補助的に添加する方法が示されて
いるが、いずれも従来技術に従い蒸留を行うよりも塔頂
留出液中の含水量を増加させ、結果として水の分離に使
用される熱量を削減することを目的としていて、廃蒸気
の利用を考慮したものではない。
Conventionally, as a document describing the energy saving measures of a vinyl acetate plant, for example, Japanese Patent Laid-Open No. 56-79639 discloses that when the acetic acid / water / vinyl acetate mixture is separated by distillation, the mixture having different water contents is separated. No. 58-39643 discloses a method of supplementarily adding water to the distillation column at the time of separating the mixture. The purpose is to increase the water content in the overhead distillate and to reduce the amount of heat used for water separation as compared with the case of performing the distillation according to the above, and it does not consider the use of waste steam.

[課題を解決するための手段] 本発明者らは、酢酸ビニル製造プラントにおける酢酸
/水/酢酸ビニル混合物の分離蒸留において廃蒸気利用
を鋭意研究した結果、酢酸/水/酢酸ビニル混合物を蒸
気塔に導入して、頂部より酢酸ビニル/水混合物を、底
部より酢酸をそれぞれ取り出す分離法において、蒸留塔
原料供給段より下の段の液を、塔底部の蒸発のために使
用される蒸気の温度より低い温度の蒸気を用い蒸発させ
ることにより、その目的が達成できることを見出し本発
明を完成した。
[Means for Solving the Problems] The inventors of the present invention have earnestly studied utilization of waste steam in the separation distillation of an acetic acid / water / vinyl acetate mixture in a vinyl acetate production plant, and as a result, the acetic acid / water / vinyl acetate mixture was converted into a vapor column. In the separation method in which the vinyl acetate / water mixture is introduced from the top and the acetic acid is taken out from the bottom, the liquid at the stage lower than the distillation column raw material feed stage is used to evaporate the temperature of the vapor used for evaporation at the bottom of the column. The present invention has been completed by finding that the object can be achieved by evaporating by using a lower temperature steam.

本発明は酢酸ビニル製造方法における酢酸/水/酢酸
ビニル混合物の蒸留に対して有効に利用され、廃蒸気の
利用によって従来使用されている高温の蒸気は使用量の
一部を減少させることができ、しかも各留分の分離効果
には何の影響も与えない点に大きな特徴を有するのであ
る。
INDUSTRIAL APPLICABILITY The present invention is effectively used for distillation of an acetic acid / water / vinyl acetate mixture in a vinyl acetate production method, and the high temperature steam conventionally used by utilizing waste steam can reduce a part of the usage amount. Moreover, it has a great feature that it has no effect on the separation effect of each fraction.

一般に本発明の酢酸/水/酢酸ビニル混合物の組成
は、主成分として約25〜50重量%の酢酸ビニル、約5〜
15重量%の水、35〜70重量%の酢酸を含有するのである
が、それ以外に酢酸エチル、ジアセテート類、ポリマ
ー、アセトアルデヒド及び/又は酢酸メチルをそれぞれ
0.5重量%以下の割合で含んでいる場合もある。
Generally, the composition of the acetic acid / water / vinyl acetate mixture of the present invention comprises about 25 to 50% by weight of vinyl acetate as a main component and about 5 to
It contains 15% by weight of water and 35 to 70% by weight of acetic acid, but other than that, ethyl acetate, diacetates, polymers, acetaldehyde and / or methyl acetate are added, respectively.
It may be contained in a proportion of 0.5% by weight or less.

本発明の酢酸/水/酢酸ビニル混合物を蒸留する蒸留
塔としては、実段としては通常40〜80段、好ましくは50
〜70段の蒸留塔が用いられる。又、蒸留は通常、常圧下
で操作される。この際塔底を加熱するには一般に約125
℃以上の蒸気が必要である。
As a distillation column for distilling the acetic acid / water / vinyl acetate mixture of the present invention, the actual stage is usually 40 to 80 stages, preferably 50
A ~ 70-stage distillation column is used. Further, the distillation is usually operated under normal pressure. At this time, generally about 125
Steam above ℃ is required.

本発明の塔底部の蒸発のために使用される蒸気(以
後、高温蒸気と略記する)の温度より低い温度の蒸気
(以後、低温蒸気と略記する)を用いて蒸発される液の
取り出しは、通常原料供給段(以後、仕込み段と略記す
る)以下の液なら、どの段の液でもよいのであるが60段
の蒸留塔で塔頂より5〜50段目で、かつ仕込み段より下
の段の液が望ましい。尚、原料の仕込み段が塔頂に近付
き過ぎると、塔頂からの留出液中に酢酸が混入し、蒸留
の目的にそぐわないし、逆に塔底に近付き過ぎると高温
蒸気と低温蒸気の温度差が少なくなり、殆ど本願の目的
を果たさなくなるので、通常、抜き取り段は塔頂より10
〜40段目の範囲が採用される。
The removal of the liquid vaporized by using a vapor (hereinafter abbreviated as low temperature vapor) having a temperature lower than that of the vapor used for vaporization of the column bottom of the present invention (hereinafter abbreviated as high temperature vapor) Any liquid can be used as long as it is a liquid below the normal raw material supply stage (hereinafter abbreviated as a charging stage), but in a 60-stage distillation column, it is 5 to 50 stages from the top of the distillation column and below the charging stage. Liquid is desirable. If the raw material charging stage is too close to the top of the column, acetic acid is mixed in the distillate from the top of the column, which does not serve the purpose of distillation. Since the difference is small and the purpose of the present application is almost lost, the extraction stage is usually 10
The range from the 40th stage is adopted.

原料を蒸留塔の2箇所以上の段に分割して仕込む場合
は、そのうちの最上段の仕込み段以下の液について低温
蒸気による蒸留を適用する。
When the raw material is divided into two or more stages of the distillation column and charged, the distillation using the low temperature steam is applied to the liquid below the uppermost charging stage.

仕込み段より上段の液について本発明と同様な操作を
行っても、高温蒸気のみを使用した場合よりかえって全
使用熱量が増加するので、省エネルギー化は達成できな
い。
Even if the same operation as in the present invention is performed on the liquid above the charging stage, the total amount of heat used is increased rather than the case where only high temperature steam is used, so energy saving cannot be achieved.

本発明の蒸留塔仕込み段より下段の液を、低温蒸気を
用い蒸発させる具体的方法としては、該液を蒸留塔から
抜き出し、蒸発器に導入して抜取液の一部、又は全部を
蒸発させて、再びこの留出物及び残液を蒸留塔に戻す方
法、及び蒸留塔内へ直接蒸発器を挿入する方法等があ
る。
As a specific method for evaporating a liquid lower than the distillation column charging stage of the present invention using low-temperature steam, the liquid is extracted from the distillation column and introduced into an evaporator to evaporate a part or all of the extracted liquid. Then, there are a method of returning the distillate and the residual liquid to the distillation column again, a method of directly inserting an evaporator into the distillation column, and the like.

次に本発明の方法の1例として、仕込み段より下の段
の液の一部を抜き出して蒸発器に導入し、抜取液の一
部、又は全部を蒸発させたのち、再びこの留出物及び蒸
発残液を塔にもどす場合について、図面に基づいて詳し
く説明するが、勿論、本発明の方法がこれに限定される
ものではない。
Next, as an example of the method of the present invention, a part of the liquid in the stage below the charging stage is extracted and introduced into an evaporator, and part or all of the extracted liquid is evaporated, and then this distillate is again extracted. The case of returning the evaporation residual liquid to the column will be described in detail with reference to the drawings, but of course the method of the present invention is not limited to this.

酢酸/水/酢酸ビニル混合物を管1から蒸留塔2に供
給する。塔頂9からは酢酸ビニル/水を主成分とする留
出物を塔2の塔底部より管3を通して酢酸を主成分とす
る缶出液を取り出すことによって蒸留が行われる。缶出
液の一部は高温蒸気を用いたリボイラー4で加熱されて
再び塔2に供給され、残りは管16より次工程へ送られ
る。原料仕込み段より下部の位置にある管5から塔内の
液を一部抜き蒸発器6に導入する。蒸発器6は低温蒸気
を用いて加熱され、抜取液を蒸発させて得られる蒸気を
管7から、一方蒸残液は管8を通して抜き出したと同じ
段へ戻す。
The acetic acid / water / vinyl acetate mixture is fed via tube 1 to the distillation column 2. The distillate containing vinyl acetate / water as a main component is distilled from the column top 9 through the pipe 3 from the bottom of the column 2 through a pipe 3 to remove a bottom product containing acetic acid as a main component. Part of the bottoms is heated by the reboiler 4 using high-temperature steam and supplied to the tower 2 again, and the rest is sent from the pipe 16 to the next step. A part of the liquid in the tower is removed from a pipe 5 located below the raw material charging stage and introduced into the evaporator 6. The evaporator 6 is heated with the low-temperature steam, and the vapor obtained by evaporating the extracted liquid is returned from the pipe 7 while the residual liquid is returned through the pipe 8 to the same stage as it was extracted.

塔頂の留分は管9を通して冷却器10で凝縮され、タン
ク11中に導入されて二層に分離する。凝縮液の下層の水
層部は管12により抜き出される。上層部の酢酸ビニル層
は管13により抜き出され一部は管14を通して還流され、
残部は管15を通して次工程にまわされて純粋な酢酸ビニ
ルへと精製される。
The fraction at the top of the column is condensed in a cooler 10 through a pipe 9 and introduced into a tank 11 to separate it into two layers. The lower aqueous layer portion of the condensate is withdrawn through the pipe 12. The vinyl acetate layer in the upper layer is extracted by a pipe 13 and a part is refluxed through a pipe 14,
The remainder is passed through the tube 15 to the next step and purified to pure vinyl acetate.

[作用] 本発明の方法では廃蒸気を利用し、高温蒸気の使用量
の一部を減少させることによって、酢酸/水/酢酸ビニ
ル混合物の分離を効率良く実施でき、プラントの省エネ
ルギー化に有用である。
[Operation] In the method of the present invention, waste steam is used, and by reducing a part of the amount of high temperature steam used, separation of an acetic acid / water / vinyl acetate mixture can be efficiently carried out, which is useful for energy saving of a plant. is there.

[実施例] 次に実施例を挙げて本発明の方法を更に具体的に説明
する。
[Example] Next, the method of the present invention will be described more specifically with reference to examples.

実施例1 シリカに担持されたパラジウム主触媒の存在下、エチ
レンと酢酸及び酸素を気相で反応させた。得られた反応
生成ガスを凝縮し、酢酸55重量%、水10重量%、酢酸ビ
ニル35重量%の組成の凝縮液を得た。
Example 1 Ethylene was reacted with acetic acid and oxygen in the gas phase in the presence of a palladium main catalyst supported on silica. The obtained reaction product gas was condensed to obtain a condensate having a composition of 55% by weight of acetic acid, 10% by weight of water and 35% by weight of vinyl acetate.

この凝縮液を径100mm、高さ6m、実段60段のキャップ
トレイ蒸留塔の塔頂部から実段で15段目に毎時10000gの
割合で供給し、塔頂部から20段目より、蒸留塔内の液を
毎時7900gの割合で抜き出し、蒸発器でこの抜取液を一
部蒸発させて蒸気部は毎時5600g(87℃)で液部は毎時2
300g(87℃)で抜き出したと同じ段に戻した。還流比を
4.5とし、常圧にて蒸留を行った。
This condensate is supplied from the top of the cap tray distillation column with a diameter of 100 mm, a height of 6 m and a real stage of 60 stages at a rate of 10,000 g per hour at the 15th stage in the actual stage, and from the 20th stage at the top of the column to the inside of the distillation column. The liquid is extracted at a rate of 7900g / h, and the extracted liquid is partially evaporated by an evaporator, the vapor part is 5600g / h (87 ° C) and the liquid part is 2h / h.
It was returned to the same stage as when it was extracted at 300 g (87 ° C). The reflux ratio
It was set to 4.5 and distilled at normal pressure.

塔頂部から酢酸ビニル/水の混合液(酢酸ビニル95.5
重量%、水4.5重量%)を毎時4400g、塔底部から酢酸
(酢酸98重量%、水2重量%)を毎時5600gの割合で得
た。
Mixture of vinyl acetate / water from the top of the tower (vinyl acetate 95.5
% By weight and 4.5% by weight of water) at a rate of 4400 g / hr and acetic acid (98% by weight of acetic acid, 2% by weight of water) at a rate of 5600 g / hr from the bottom of the column.

この時の蒸留塔の塔頂温度68℃、塔頂温度128℃、塔
底に使用されている蒸気の温度は150℃であり、使用量
は毎時5430gであった。また、蒸発器で使用されている
(水)蒸気の温度は100℃であり、使用量は毎時1000gで
あった。
At this time, the top temperature of the distillation column was 68 ° C, the top temperature was 128 ° C, the temperature of the vapor used at the bottom was 150 ° C, and the amount used was 5430 g / hr. The temperature of the (water) steam used in the evaporator was 100 ° C, and the amount used was 1000 g / hr.

実施例2〜6、対照例1〜3 実施例1の方法に準じて、第1,2表に示す条件で実験
を行い、結果を第1,2表に併せて示した。
Examples 2 to 6 and Comparative Examples 1 to 3 According to the method of Example 1, an experiment was conducted under the conditions shown in Tables 1 and 2, and the results are also shown in Tables 1 and 2.

[効果] 酢酸/水/酢酸ビニル混合物を蒸留塔に導入して、頂
部より酢酸ビニル/水混合物を底部より酢酸を留出させ
る分離法において、蒸留塔の原料供給段より下の段の液
を、塔底部の蒸発のために使用される蒸気の温度より低
い温度の蒸気を用い蒸発させることを特徴とする分離法
を用いることによって、従来の塔底部の液のみを加熱蒸
発させる分離法と比較して、分離能も変わらず、かつ、
利用価値の低い低温の蒸気で一部代替できるという効果
を有し、産業上化学プラント等での省エネルギー対策と
して有用である。
[Effect] In a separation method in which an acetic acid / water / vinyl acetate mixture is introduced into a distillation column and a vinyl acetate / water mixture is distilled from the top to distill acetic acid from the bottom, a liquid in a stage lower than a raw material supply stage of the distillation column is used. Compared with the conventional separation method in which only the liquid in the bottom of the column is heated and evaporated by using a separation method characterized in that vaporization is performed using a vapor having a temperature lower than that of the vapor used for vaporization of the bottom of the column. And the resolution is the same, and
It has the effect that it can be partially replaced by low-temperature low-temperature steam, and is useful as an energy-saving measure in industrial chemical plants.

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

図面は本発明の一実施態様を示すフローシートである。 1……原料供給管、2……蒸留塔 3……塔底液抜出し管、4……リボイラー 5……側部液抜出し管、6……蒸発器 7……抜出し液蒸気供給管、8……抜出し液蒸発残液供
給管 9……塔頂部蒸気抜出し管、10……冷却器 11……相分離タンク、12……下層部液抜出し管 13……上層部液抜出し管、14……還流管 15……酢酸ビニル/水混合液留出管 16……酢酸留出管
The drawings are flow sheets showing one embodiment of the present invention. 1 ... Raw material supply pipe, 2 ... Distillation tower 3 ... Tower bottom liquid extraction pipe, 4 ... Reboiler 5 ... Side liquid extraction pipe, 6 ... Evaporator 7 ... Extracted liquid vapor supply pipe, 8 ... … Extracted liquid evaporation residual liquid supply pipe 9 …… column top vapor extraction pipe, 10 …… cooler 11 …… phase separation tank, 12 …… lower layer liquid extraction pipe 13 …… upper layer liquid extraction pipe, 14 …… reflux Tube 15 …… Vinyl acetate / water mixture distillation tube 16 …… Acetic acid distillation tube

Claims (2)

(57)【特許請求の範囲】(57) [Claims] 【請求項1】酢酸/水/酢酸ビニル混合物を蒸留塔に導
入して、頂部より酢酸ビニル/水混合物を、底部より酢
酸をそれぞれ取り出す分離法において、蒸留塔原料供給
段より下の段の液を塔底部の蒸発のために使用される蒸
気の温度より低い温度の蒸気を用い蒸発させることを特
徴とする酢酸/水/酢酸ビニル混合物の分離法。
1. A separation method in which an acetic acid / water / vinyl acetate mixture is introduced into a distillation column and a vinyl acetate / water mixture is taken out from the top and acetic acid is taken out from the bottom, respectively. A method for separating an acetic acid / water / vinyl acetate mixture, characterized in that is vaporized with a vapor having a temperature lower than that of the vapor used for vaporizing the bottom of the column.
【請求項2】蒸留塔原料供給段より下の段の液の一部を
抜き出して蒸発器に導入し、抜取液の一部又は全部を蒸
発させた後、再びこの留出物及び蒸発残液を塔にもどす
ことを特徴とする特許請求の範囲第1項記載の方法。
2. A part of the liquid below the distillation column raw material supply stage is withdrawn and introduced into an evaporator to evaporate a part or all of the withdrawn liquid, and then the distillate and the evaporation residual liquid are again provided. The method according to claim 1, wherein the column is returned to the column.
JP24486688A 1988-09-29 1988-09-29 Method for separating acetic acid / water / vinyl acetate mixture Expired - Fee Related JP2681667B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP24486688A JP2681667B2 (en) 1988-09-29 1988-09-29 Method for separating acetic acid / water / vinyl acetate mixture

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JP24486688A JP2681667B2 (en) 1988-09-29 1988-09-29 Method for separating acetic acid / water / vinyl acetate mixture

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DE102005054411A1 (en) * 2005-11-15 2007-05-16 Wacker Chemie Ag Process for the preparation of vinyl acetate using the released heat of reaction
CN106905156B (en) * 2015-12-22 2020-07-24 中国石化集团四川维尼纶厂 Vinyl acetate rectification device and method

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