JPS6212769B2 - - Google Patents
Info
- Publication number
- JPS6212769B2 JPS6212769B2 JP55078346A JP7834680A JPS6212769B2 JP S6212769 B2 JPS6212769 B2 JP S6212769B2 JP 55078346 A JP55078346 A JP 55078346A JP 7834680 A JP7834680 A JP 7834680A JP S6212769 B2 JPS6212769 B2 JP S6212769B2
- Authority
- JP
- Japan
- Prior art keywords
- extractive distillation
- stage
- column
- distillation column
- hydrocarbons
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000895 extractive distillation Methods 0.000 claims description 80
- 229930195733 hydrocarbon Natural products 0.000 claims description 70
- 150000002430 hydrocarbons Chemical class 0.000 claims description 54
- 238000000034 method Methods 0.000 claims description 37
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 claims description 34
- 239000002904 solvent Substances 0.000 claims description 25
- 238000000605 extraction Methods 0.000 claims description 21
- 239000004215 Carbon black (E152) Substances 0.000 claims description 17
- -1 C 4 hydrocarbon Chemical class 0.000 claims description 16
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical group CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 11
- 238000000926 separation method Methods 0.000 claims 2
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 9
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 6
- 238000007796 conventional method Methods 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 238000004821 distillation Methods 0.000 description 4
- HYBBIBNJHNGZAN-UHFFFAOYSA-N furfural Chemical compound O=CC1=CC=CO1 HYBBIBNJHNGZAN-UHFFFAOYSA-N 0.000 description 4
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- KDKYADYSIPSCCQ-UHFFFAOYSA-N but-1-yne Chemical group CCC#C KDKYADYSIPSCCQ-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- VQTUBCCKSQIDNK-UHFFFAOYSA-N Isobutene Chemical compound CC(C)=C VQTUBCCKSQIDNK-UHFFFAOYSA-N 0.000 description 1
- IAQRGUVFOMOMEM-UHFFFAOYSA-N but-2-ene Chemical class CC=CC IAQRGUVFOMOMEM-UHFFFAOYSA-N 0.000 description 1
- 235000013844 butane Nutrition 0.000 description 1
- WFYPICNXBKQZGB-UHFFFAOYSA-N butenyne Chemical group C=CC#C WFYPICNXBKQZGB-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000003350 kerosene Substances 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical class CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- 239000002798 polar solvent Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- MWWATHDPGQKSAR-UHFFFAOYSA-N propyne Chemical group CC#C MWWATHDPGQKSAR-UHFFFAOYSA-N 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 229920003051 synthetic elastomer Polymers 0.000 description 1
- 238000010189 synthetic method Methods 0.000 description 1
- 239000005061 synthetic rubber Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
- B01D3/40—Extractive distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
- C07C7/05—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds
- C07C7/08—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds by extractive distillation
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Water Supply & Treatment (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Description
【発明の詳細な説明】
本発明は、極性抽出溶剤を用いて２段の抽出蒸
留工程によりC4炭化水素混合物から比較的易溶
性炭化水素である１・３−ブタジエンを分離する
方法において、先ず第１段目の抽出蒸留工程にお
いてパラフイン系及びオレフイン系炭化水素など
の比較的難溶性炭化水素を除去し、次いで第２段
目の抽出蒸留工程においてアセチレン系炭化水素
などの１・３−ブタジエンより易溶性の炭化水素
を除去することから成る２段の抽出蒸留法におけ
る改良方法に関するものである。なお、本発明で
いう比較的難溶性炭化水素及び比較的易溶性炭化
水素とは、抽出溶剤に対する炭化水素類の溶解性
の差を定性的に表現したもので、パラフイン系炭
化水素及びオレフイン系炭化水素は比較的難溶性
炭化水素であり、共役ジエン系炭化水素及びアセ
チレン系炭化水素は比較的易溶性炭化水素という
ことができる。
共役ジオレフイン系炭化水素、特に１・３−ブ
タジエンは合成ゴム、繊維、樹脂等の重要な出発
原料となる。１・３−ブタジエンは、LPG、ナフ
サ、灯油等の熱分解によつてエチレン等を製造す
る際に副生するC4炭化水素留分中に可成りの量
が含まれている。また、パラフイン系又はオレフ
イン系炭化水素の脱水素あるいはその他の合成法
によつても得られるが、いずれにしても一般には
パラフイン系炭化水素、オレフイン系炭化水素、
共役ジオレフイン系炭化水素等の混合物として得
られる。これらの炭化水素混合物から１・３−ブ
タジエンを分離精製する方法として、ジメチルホ
ルムアミド、Ｎ−メチルピロリドン、フルフラー
ル、アセトニトリル等の抽出溶剤を用いる１段乃
至２段法による抽出蒸留法が知られている。
通常、抽出蒸留は抽出蒸留塔と放散塔よりなる
装置を用いて行なわれ、その際抽出蒸留塔は常圧
乃至加圧下にて操作され、また放散塔は抽出溶剤
に溶解している比較的易溶性炭化水素をできるだ
け完全に放散させるために常圧又は減圧下で操作
される。第１段目の抽出蒸留工程の放散塔塔頂よ
り回収された比較的易溶性炭化水素は更に精製す
るために第２段目の抽出蒸留工程の抽出蒸留塔へ
送られるが、その場合液化してポンプによつて送
るか圧縮機によつて昇圧したのち移送するのが常
である。第２段目の抽出蒸留工程において１・３
−ブタジエンより易溶性の炭化水素が抽出溶剤の
存在下にて蒸留分離され、１・３−ブタジエンは
第２段目の抽出蒸留塔塔頂より回収されて製品と
して取り出されるか、あるいは更に継続して微量
不純物の除去のための次の工程に付されることに
なる。
而して、本発明によれば抽出溶剤を用いて抽出
蒸留塔と放散塔とを有する抽出蒸留工程を２段に
組合せた２段抽出蒸留法により炭化水素混合物か
ら特定の比較的易溶性炭化水素を分離する方法に
おいて、第１段抽出蒸留塔塔底圧を第２段抽出蒸
留塔塔底圧より高い圧力にて操作すると共に、第
１段抽出蒸留塔と第１段放散塔との間にプレスト
リツピング塔を設け、該プレストリツピング塔を
第１段抽出蒸留塔塔底圧と等しいか或いは低く且
つ第２段抽出蒸留塔塔底圧と等しいか或いは高い
圧力にて操作することにより、プレストリツピン
グ塔において発生した比較的易溶性炭化水素ガス
を第１段放散塔と圧縮機あるいはポンプを経由す
ることなく直接第２段抽出蒸留塔へ圧送すること
を特徴とする方法が提供される。
本発明のこのような方法によれば、第１段目の
抽出蒸留工程と第２段目の抽出蒸留工程の間に介
在するポンプあるいは圧縮機の電力を削減し、か
つ第１段目の放散塔の負荷を軽減することができ
るなど大きな効果を奏する。本発明においては、
プレストリツピング塔にて放散される比較的易溶
性炭化水素の量を最大にすることが次の操作であ
る第１段放散塔のストリツピング操作及び第１段
放散塔から第２段抽出蒸留塔への比較的易溶性炭
化水素の移送のための圧縮機の負荷あるいは液輸
送のポンプの負荷を最少に軽減することになる。
それ故、本発明においては、プレストリツピング
塔における放散操作の補助としてプレストリツピ
ング塔内の抽出溶剤の液温を上げるためのリボイ
ラーをプレストリツピング塔に設置することが望
ましい。
次に図面に従つて本発明を説明するが、この例
はC4炭化水素から比較的易溶性炭化水素である
１・３−ブタジエンの分離方法を示す一例であつ
て、これによつて本発明が限定されるものでない
ことは明らかである。
第１図は本発明方法による抽出蒸留プロセスを
示しており、第２図は従来法による抽出蒸留プロ
セスを示している。原料炭化水素混合物はライン
１から第１段抽出蒸留塔DAの中間部へ供給され
る。抽出蒸留により比較的難溶性炭化水素は塔頂
部に濃縮され、全量がライン２を経由して留出物
として系外に取り出される。抽出溶剤は第１段抽
出蒸留塔DAの塔頂部にライン３により供給さ
れ、塔の下方に流下しながら抽出蒸留操作によつ
て比較的易溶性炭化水素に富む溶液となる。抽出
蒸留塔内の溶剤濃度は通常高濃度に維持する必要
があり、その供給量は原料炭化水素混合物の数倍
乃至十数倍を目安に蒸留計算により定められる。
本発明の方法においては、ジメチルホルムアミ
ド、Ｎ−メチルピロリドン、フルフラール、アセ
トニトリル等の極性溶剤、就中ジメチルホルムア
ミドが好適に使用できる。
第１段抽出蒸留塔は塔頂における比較的難溶性
炭化水素が冷却水によつて凝縮され得る温度に平
衡な圧力によつて操作されるのが通常であり、塔
底では塔内の圧力損失により塔頂より数気圧高く
なつている。第１段抽出蒸留塔塔底には抽出蒸留
により必要とされる熱を供給するためのリボイラ
ーEAが設備されており、このリボイラーは塔底
より抜き出される抽出溶剤中への比較的易溶性炭
化水素の溶解量をコントロールする役目をも果し
ている。すなわち、ライン４より抜き出される抽
出溶剤中の比較的易溶性炭化水素濃度は塔底にお
ける該炭化水素蒸気濃度と平衡関係にあり高温で
は溶解度が下り、低温では溶解度が上るので、比
較的易溶性炭化水素の抽出溶剤中への溶解量を温
度によつて増減させることができる。一方、比較
的易溶性炭化水素を溶解する抽出溶剤を一定以上
の高温に維持すると１・３−ブタジエンの重合が
促進され、生成したポリマーが装置内に付着し熱
交換器等の機能の低下をきたすので、実験的又は
経験的に塔底温度の上限は決められることにな
る。通常の抽出蒸留では第１段目の抽出蒸留塔塔
底温度をこの上限温度以下に保つため、必然的に
比較的易溶性炭化水素の抽出溶剤への溶解量は最
適な塔底抽出量よりも大きくなり抽出蒸留塔の物
質収支を取る必要上過剰に溶解した比較的易溶性
炭化水素を第１段目の放散塔DC、圧縮機Ｋを経
由して第１段目の抽出蒸留塔DAにライン８によ
り戻す方法がとられている。
第１段目の抽出蒸留塔塔底より抜き出された抽
出物を含む抽出溶剤はライン４を経て本発明方法
により新たに設けられたプレストリツピング塔
DBへ送り、該プレストリツピング塔を第１段抽
出蒸留塔塔底圧と等しいかより低く且つ第２段抽
出蒸留塔塔底圧と等しいかより高い圧力にて操作
することによつて抽出溶剤中の比較的易溶性炭化
水素の一部を蒸発せしめ、さらに好ましくはプレ
ストリツピング塔塔底部に設置したリボイラー
EBで比較的易溶性炭化水素の蒸発に要する熱を
補給することにより、できるだけ多くの比較的易
溶性炭化水素を蒸発せしめ、発生ガスを直接第２
段抽出蒸留塔へ圧力移送すれば、従来法における
第１段放散塔における比較的易溶性炭化水素のス
トリツピング操作及び第１段放散塔から第２段抽
出蒸留塔への比較的易溶性炭化水素の移送のため
の圧縮機の負荷を軽減させることが可能となる。
本発明で使用するプレストリツピング塔としては
空塔あるいはケトル型の熱交換器が適宜利用でき
る。
プレストリツピング塔塔底より抜き出された抽
出溶剤はライン５を通つて第１段放散塔DCに送
られ、ここで抽出溶剤より完全に比較的易溶性炭
化水素を分離回収する。放散された比較的易溶性
炭化水素は蒸気として圧縮機Ｋに導入し、第１段
抽出蒸留塔塔底圧力よりやや高い圧力まで昇圧さ
れ、圧縮された炭化水素ガスの全量あるいは大部
分がライン８により第１段抽出蒸留塔塔底に戻さ
れる。なお、第１段抽出蒸留塔における比較的易
溶性炭化水素中の比較的難溶性炭化水素の濃度は
圧縮機より排出されるガスの一部をライン９によ
り第２段抽出蒸留塔へ供給することによりコント
ロールされる。
第２段抽出蒸留工程は第１段抽出蒸留工程で分
離回収した比較的易溶性炭化水素類の内から更に
易溶性のアセチレン系炭化水素類などを抽出溶剤
の存在下にて抽出蒸留法により除去する工程であ
り、第２段抽出蒸留塔DEとアセチレン系炭化水
素類を含む抽出溶剤からアセチレン系炭化水素類
などを放散する第２段放散塔DFから構成されて
いる。第１段抽出蒸留工程からの比較的易溶性炭
化水素がライン１０によつて第２段抽出蒸留塔
DEへ供給され、ここで、ライン１２からの抽出
溶剤と向流に接触し、アセチレン系炭化水素類な
どの濃縮を行い、目的回収物である１・３−ブタ
ジエンは第２段抽出蒸留塔DEの塔頂よりライン
１３によつて回収され、通常は微量不純物の除去
のために更に数次に及ぶ蒸留工程にかけられ最終
製品として系外に取り出されることになる。
一方、アセチレン系炭化水素類などを吸収した
溶剤溶液は、第２段抽出蒸留塔DEの塔底からラ
イン１４によつて第２段放散塔DFの塔頂に送ら
れ、アセチレン系炭化水素類は第２段放散塔中央
付近よりライン１７により抜き出され同伴する溶
剤を回収したのち、燃料などに供される。なお、
第２段放散塔塔頂ガスは１・３−ブタジエンを可
成り濃い濃度で含んでいるのでライン１５によつ
て圧縮機Ｋの吸込側に戻して回収することが望ま
しい。
第１放散塔DC及び第２放散塔DFの塔底から
夫々ライン１１，１６により抜き出された１・３
−ブタジエン及びアセチレン系炭化水素類などを
含まない抽出溶剤は、溶剤のもつ熱を回収した
後、水冷却器EGで所定の温度に調節され、流量
をコントロールした上で夫々第１段抽出蒸留塔及
び第２段抽出蒸留塔へ再循環される。
以上の如く、本発明の方法によれば第１段抽出
蒸留塔塔底において分離回収した比較的易溶性炭
化水素の大部分を第１段放散塔DC及び圧縮機を
経由させないで第２段抽出蒸留塔へ供給すること
ができるので、従来の２段抽出蒸留法よりも第１
段放散塔の負荷を下げ、かつ圧縮機の動力を著し
く軽減することができるなどの利点を有する。
以下、実施例を挙げて本発明を具体的に説明す
る。
実施例
第１図（本発明法）及び第２図（従来法）に示
す装置を用いた。各塔の段数は次の通りである。
第１抽出蒸留塔 140段
第１放散塔 15段
プレストリツピング塔 室塔
第２抽出蒸留塔 60段
第２放散塔 20段
第１段抽出蒸留塔の中段に、次の組成を有する
原料を毎時15.29Nm3の割合で供給し、塔頂より
ジメチルホルムアミド溶剤を毎時276の割合で
供給し抽出蒸留を行つた。
〔C4炭化水素混合物組成〕比較的難溶性炭化水素
重量％
ブタン類 2.5
１−ブテン 18.0
ｉ−ブテン 24.7
２−ブテン類 9.6比較的易溶性炭化水素
重量％
１・３−ブタジエン 43.6
メチルアセチレン 0.1
１・２−ブタジエン 0.2
エチルアセチレン 0.2
ビニルアセチレン 0.6
C5炭化水素類 0.5
第１段抽出蒸留塔、第２段抽出蒸留塔及びプレ
ストリツピング塔の操作条件は次表の通りであ
り、このとき圧縮機の吸込ガス量は毎時7.1Nm3
であつた。参考までに従来法による第２図の場
合、同一操作条件で圧縮機の吸込ガス量は毎時
11.4Nm3であつた。なお、本発明法及び従来法と
も第１段抽出蒸留塔塔頂の比較的難溶性炭化水素
の１・３−ブタジエン濃度は0.2重量％であり、
第２段抽出蒸留塔塔頂から回収分離された１・３
−ブタジエンの純度は96.5重量％であつた。
【表】DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for separating 1,3-butadiene, a relatively easily soluble hydrocarbon, from a C4 hydrocarbon mixture by a two-stage extractive distillation process using a polar extraction solvent. Relatively insoluble hydrocarbons such as paraffinic and olefinic hydrocarbons are removed in the first extractive distillation process, and then 1,3-butadiene such as acetylene hydrocarbons are removed in the second extractive distillation process. The present invention relates to an improved two-stage extractive distillation process consisting of removing easily soluble hydrocarbons. In addition, relatively poorly soluble hydrocarbons and relatively easily soluble hydrocarbons as used in the present invention qualitatively express the difference in solubility of hydrocarbons in an extraction solvent, and include paraffinic hydrocarbons and olefinic hydrocarbons. Hydrogen is a relatively poorly soluble hydrocarbon, and conjugated diene hydrocarbons and acetylene hydrocarbons can be said to be relatively easily soluble hydrocarbons. Conjugated diolefin hydrocarbons, especially 1,3-butadiene, are important starting materials for synthetic rubbers, fibers, resins, etc. A considerable amount of 1,3-butadiene is contained in the C4 hydrocarbon fraction produced as a by-product when producing ethylene and the like through thermal decomposition of LPG, naphtha, kerosene, and the like. It can also be obtained by dehydrogenating paraffinic or olefinic hydrocarbons or by other synthetic methods, but in any case, generally paraffinic hydrocarbons, olefinic hydrocarbons,
Obtained as a mixture of conjugated diolefin hydrocarbons, etc. As a method for separating and purifying 1,3-butadiene from these hydrocarbon mixtures, a one- or two-stage extractive distillation method using an extraction solvent such as dimethylformamide, N-methylpyrrolidone, furfural, or acetonitrile is known. . Normally, extractive distillation is carried out using a device consisting of an extractive distillation column and a stripping column. At this time, the extractive distillation column is operated under normal pressure or pressurized pressure, and the stripping column is a relatively simple device that is dissolved in the extraction solvent. It is operated under normal or reduced pressure in order to dissipate soluble hydrocarbons as completely as possible. The relatively easily soluble hydrocarbons recovered from the top of the stripping column in the first extractive distillation process are sent to the extractive distillation column in the second extractive distillation process for further purification, but in that case they are not liquefied. Usually, it is sent by a pump or after being pressurized by a compressor and then transferred. 1.3 in the second stage extractive distillation process
- Hydrocarbons that are more easily soluble than butadiene are separated by distillation in the presence of an extraction solvent, and 1,3-butadiene is recovered from the top of the second stage extractive distillation column and taken out as a product, or further continued. The sample is then subjected to the next step to remove trace impurities. According to the present invention, specific relatively easily soluble hydrocarbons can be extracted from a hydrocarbon mixture by a two-stage extractive distillation method in which an extractive distillation process having an extractive distillation column and a stripping column is combined into two stages using an extraction solvent. In this method, the bottom pressure of the first-stage extractive distillation column is operated at a pressure higher than the bottom pressure of the second-stage extractive distillation column, and the pressure between the first-stage extractive distillation column and the first-stage stripping column is By providing a pre-stripping column and operating the pre-stripping column at a pressure equal to or lower than the first-stage extractive distillation column bottom pressure and equal to or higher than the second-stage extractive distillation column bottom pressure, Provided is a method characterized in that a relatively easily soluble hydrocarbon gas generated in a pre-stripping column is directly pumped to a second stage extractive distillation column without passing through a first stage stripping column and a compressor or pump. . According to such a method of the present invention, the power of the pump or compressor interposed between the first-stage extractive distillation process and the second-stage extractive distillation process can be reduced, and the power consumption of the first-stage extractive distillation process can be reduced. This has great effects, such as being able to reduce the load on the tower. In the present invention,
The next operation is to maximize the amount of relatively easily soluble hydrocarbons stripped in the pre-stripping column.The stripping operation of the first stage stripping column and from the first stage stripping column to the second stage extractive distillation column. The load on the compressor for transferring relatively easily soluble hydrocarbons or the load on the pump for liquid transfer is reduced to a minimum.
Therefore, in the present invention, it is desirable to install a reboiler in the pre-stripping column to increase the liquid temperature of the extraction solvent in the pre-stripping column as an aid to the dispersion operation in the pre-stripping column. Next, the present invention will be explained according to the drawings. This example is an example showing a method for separating 1,3-butadiene, which is a relatively easily soluble hydrocarbon, from C4 hydrocarbons. It is clear that this is not a limitation. FIG. 1 shows the extractive distillation process according to the method of the present invention, and FIG. 2 shows the extractive distillation process according to the conventional method. The raw hydrocarbon mixture is fed from line 1 to the middle part of the first stage extractive distillation column DA. Relatively insoluble hydrocarbons are concentrated at the top of the column by extractive distillation, and the entire amount is taken out of the system as a distillate via line 2. The extraction solvent is supplied to the top of the first-stage extractive distillation column DA through line 3, and as it flows down the column, it is subjected to extractive distillation operations to become a solution relatively rich in easily soluble hydrocarbons. The concentration of the solvent in the extractive distillation column usually needs to be maintained at a high concentration, and its supply amount is determined by distillation calculations, with the amount being several to ten times as large as the raw material hydrocarbon mixture.
In the method of the present invention, polar solvents such as dimethylformamide, N-methylpyrrolidone, furfural, and acetonitrile, especially dimethylformamide, can be suitably used. The first-stage extractive distillation column is normally operated at a pressure that is equilibrated to the temperature at which relatively insoluble hydrocarbons at the top of the column can be condensed by cooling water, and at the bottom of the column there is a pressure loss within the column. Therefore, the temperature is several atmospheres higher than the top of the tower. A reboiler EA is installed at the bottom of the first-stage extractive distillation column to supply the heat required for extractive distillation. It also plays a role in controlling the amount of hydrogen dissolved. In other words, the concentration of relatively easily soluble hydrocarbons in the extraction solvent drawn out from line 4 is in an equilibrium relationship with the hydrocarbon vapor concentration at the bottom of the column, and the solubility decreases at high temperatures and increases at low temperatures. The amount of hydrocarbon dissolved in the extraction solvent can be increased or decreased depending on the temperature. On the other hand, if the extraction solvent that dissolves relatively easily soluble hydrocarbons is maintained at a high temperature above a certain level, the polymerization of 1,3-butadiene will be promoted, and the resulting polymer will adhere to the inside of the equipment, causing a decline in the functionality of heat exchangers, etc. Therefore, the upper limit of the bottom temperature must be determined experimentally or empirically. In normal extractive distillation, the temperature at the bottom of the extractive distillation column in the first stage is kept below this upper limit temperature, so the amount of relatively easily soluble hydrocarbons dissolved in the extraction solvent is inevitably higher than the optimal amount extracted from the bottom. Due to the need to balance the mass of the extractive distillation column, the relatively easily soluble hydrocarbons dissolved in excess are passed through the first-stage stripping column DC and compressor K to the first-stage extractive distillation column DA. 8 has been adopted. The extraction solvent containing the extract extracted from the bottom of the first-stage extractive distillation column passes through line 4 to a pre-stripping column newly installed by the method of the present invention.
DB and operating the pre-stripping column at a pressure equal to or lower than the first stage extractive distillation column bottom pressure and equal to or higher than the second stage extractive distillation column bottom pressure. A reboiler is preferably installed at the bottom of the prestripping column to evaporate a portion of the relatively easily soluble hydrocarbons in the prestripping column.
By replenishing the heat required to evaporate relatively easily soluble hydrocarbons with EB, as much relatively easily soluble hydrocarbons as possible can be evaporated and the generated gas can be directly
Pressure transfer to the stage extractive distillation column eliminates the stripping operation of relatively easily soluble hydrocarbons in the first stage stripping column and the transfer of relatively easily soluble hydrocarbons from the first stage stripping column to the second stage extractive distillation column in the conventional method. It becomes possible to reduce the load on the compressor for transfer.
As the pre-stripping column used in the present invention, an empty column or a kettle type heat exchanger can be used as appropriate. The extraction solvent extracted from the bottom of the pre-stripping tower is sent through line 5 to the first stage stripping tower DC, where relatively easily soluble hydrocarbons are completely separated and recovered from the extraction solvent. The released relatively easily soluble hydrocarbons are introduced as vapor into the compressor K, and the pressure is increased to a pressure slightly higher than the bottom pressure of the first stage extractive distillation column. is returned to the bottom of the first stage extractive distillation column. The concentration of relatively poorly soluble hydrocarbons in the relatively easily soluble hydrocarbons in the first stage extractive distillation column is determined by supplying a portion of the gas discharged from the compressor to the second stage extractive distillation column via line 9. controlled by. The second stage extractive distillation process further removes easily soluble acetylene hydrocarbons from among the relatively easily soluble hydrocarbons separated and recovered in the first stage extractive distillation process in the presence of an extraction solvent. This process consists of a second-stage extractive distillation column DE and a second-stage stripping column DF that dissipates acetylene hydrocarbons and the like from the extraction solvent containing acetylene hydrocarbons. Relatively easily soluble hydrocarbons from the first stage extractive distillation process are transferred via line 10 to the second stage extractive distillation column.
The 1,3-butadiene is supplied to the DE, where it comes into contact with the extraction solvent from line 12 in a countercurrent flow to concentrate acetylene hydrocarbons, etc. It is recovered from the top of the column via line 13, and is usually subjected to several further distillation steps to remove trace impurities, and then taken out of the system as a final product. On the other hand, the solvent solution that has absorbed acetylene hydrocarbons is sent from the bottom of the second extractive distillation column DE to the top of the second stripping column DF via line 14, and the acetylene hydrocarbons are After being extracted from near the center of the second stage stripping tower through line 17 and collecting the accompanying solvent, it is used as fuel. In addition,
Since the second-stage stripping column top gas contains 1,3-butadiene at a fairly high concentration, it is desirable to return it to the suction side of the compressor K via line 15 and recover it. 1 and 3 extracted from the bottoms of the first stripping tower DC and the second stripping tower DF through lines 11 and 16, respectively.
- After recovering the heat of the extraction solvent that does not contain butadiene or acetylene hydrocarbons, it is adjusted to a predetermined temperature with a water cooler EG, and after controlling the flow rate, it is passed through the first extractive distillation column. and recycled to the second stage extractive distillation column. As described above, according to the method of the present invention, most of the relatively easily soluble hydrocarbons separated and recovered at the bottom of the first stage extractive distillation column are extracted in the second stage without passing through the first stage stripping column DC and the compressor. Since it can be supplied to the distillation column, the first
It has the advantage of lowering the load on the stage stripping tower and significantly reducing the power of the compressor. The present invention will be specifically described below with reference to Examples. Example The apparatus shown in FIG. 1 (method of the present invention) and FIG. 2 (conventional method) was used. The number of stages in each tower is as follows. 1st extractive distillation column 140-stage 1st stripping tower 15-stage pre-stripping column Chamber 2nd extractive distillation column 60-stage 2nd stripping tower 20-stage 1st extractive distillation column Into the middle stage of the 1st extractive distillation column, a raw material having the following composition is charged every hour. Extractive distillation was carried out by feeding dimethylformamide solvent at a rate of 276 / hour from the top of the column. [C 4 hydrocarbon mixture composition] Relatively poorly soluble hydrocarbons ( wt% ) Butanes 2.5 1-butene 18.0 i-butene 24.7 2-butenes 9.6 Relatively easily soluble hydrocarbons (wt %) 1,3-butadiene 43.6 Methylacetylene 0.1 1・2-Butadiene 0.2 Ethyl acetylene 0.2 Vinyl acetylene 0.6 C5 hydrocarbons 0.5 The operating conditions of the first stage extractive distillation column, second stage extractive distillation column and pre-stripping column are as shown in the table below. The suction gas amount is 7.1Nm 3 per hour.
It was hot. For reference, in the case of the conventional method shown in Figure 2, the amount of gas sucked into the compressor per hour under the same operating conditions is
It was 11.4Nm3 . In addition, in both the method of the present invention and the conventional method, the concentration of 1,3-butadiene in the relatively poorly soluble hydrocarbon at the top of the first stage extractive distillation column is 0.2% by weight.
1 and 3 collected and separated from the top of the second stage extractive distillation column
- The purity of the butadiene was 96.5% by weight. 【table】
第１図は本発明の方法に従う抽出蒸留法の一例
を示す線図、第２図は従来法に従う抽出蒸留法を
示す線図である。
図において、DAは第１段抽出蒸留塔、DBはプ
レストリツピング塔、DCは第１段放散塔、DEは
第２段抽出蒸留塔、DFは第２段放散塔、EA，
EB，EC，EE，EF及びEGは熱交換器、Ｋは圧
縮機、１〜１７は導管である。
FIG. 1 is a diagram showing an example of the extractive distillation method according to the method of the present invention, and FIG. 2 is a diagram showing an example of the extractive distillation method according to the conventional method. In the figure, DA is the first extractive distillation column, DB is the pre-stripping column, DC is the first stripping column, DE is the second extractive distillation column, DF is the second stripping column, EA,
EB, EC, EE, EF and EG are heat exchangers, K is a compressor, and 1 to 17 are conduits.
Claims (1)
とを有する抽出蒸留工程を２段に組合せた抽出蒸
留法によりC4炭化水素混合物から１・３−ブタ
ジエンを分離する方法において、第１段抽出蒸留
塔塔底圧を第２段抽出蒸留塔塔底圧より高い圧力
で操作すると共に、第１段抽出蒸留塔と第１段放
散塔との間にプレストリツピング塔を設けて該プ
レストリツピング塔を第１段抽出蒸留塔塔底圧と
等しいか或いは低く且つ第２段抽出蒸留塔塔底圧
と等しいか或いは高い圧力で操作することによ
り、プレストリツピング塔において発生した比較
的易溶性炭化水素ガスを直接第２段抽出蒸留塔へ
圧送することを特徴とするC4炭化水素混合物か
ら１・３−ブタジエンを分離する方法。 ２ 極性抽出溶剤がジメチルホルムアミドである
特許請求の範囲第１項記載の分離方法。[Claims] 1. Separation of 1,3-butadiene from a C 4 hydrocarbon mixture in the presence of a polar extraction solvent by an extractive distillation method that combines two stages of extractive distillation steps having an extractive distillation column and a stripping column. In the method, the bottom pressure of the first-stage extractive distillation column is operated at a pressure higher than the bottom pressure of the second-stage extractive distillation column, and a pre-stripping column is provided between the first-stage extractive distillation column and the first-stage stripping column. and operating the prestripping column at a pressure equal to or lower than the bottom pressure of the first stage extractive distillation column and equal to or higher than the bottom pressure of the second stage extractive distillation column. A method for separating 1,3-butadiene from a C 4 hydrocarbon mixture, characterized in that the relatively easily soluble hydrocarbon gas generated is directly pumped to a second stage extractive distillation column. 2. The separation method according to claim 1, wherein the polar extraction solvent is dimethylformamide.
Priority Applications (11)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7834680A JPS574926A (en) | 1980-06-12 | 1980-06-12 | Separation of relatively easily soluble hydrocarbon from hydrocarbon mixture |
| YU01134/81A YU113481A (en) | 1980-06-12 | 1981-05-04 | Process for the separation of relativey easily soluble hydrocarbons from a hydrocarbon mixture |
| AR81285219A AR242624A1 (en) | 1980-06-12 | 1981-05-06 | Process for extractive distillation of hydrocarbons |
| AU70300/81A AU541746B2 (en) | 1980-06-12 | 1981-05-08 | Extractive distillation of hydrocarbons e.g. isoprene butadiene |
| HU811276A HU187335B (en) | 1980-06-12 | 1981-05-11 | Process for the separation of easily soluble hydrocarbon components from hydrocarbon mixtures |
| GB8114421A GB2077753B (en) | 1980-06-12 | 1981-05-12 | Process for extractive distillation of hydrocarbons |
| IN498/CAL/81A IN152086B (en) | 1980-06-12 | 1981-05-12 | |
| NO811982A NO156447C (en) | 1980-06-12 | 1981-06-11 | PROCEDURE FOR SEPARATION OF RELATIVELY EASY LOOSED HYDROCARBONES FROM A HYDROCARBON MIXTURE. |
| CA000379589A CA1180301A (en) | 1980-06-12 | 1981-06-11 | Process for separating relatively easily soluble hydrocarbons from a hydrocarbon mixture |
| MX187764A MX159551A (en) | 1980-06-12 | 1981-06-11 | IMPROVED PROCEDURE FOR SEPARATING 1,3-BUTADIENE |
| AT0264881A AT375330B (en) | 1980-06-12 | 1981-06-12 | METHOD FOR SEPARATING RELATIVELY EASILY SOLUBLE HYDROCARBONS FROM A HYDROCARBON MIXTURE |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7834680A JPS574926A (en) | 1980-06-12 | 1980-06-12 | Separation of relatively easily soluble hydrocarbon from hydrocarbon mixture |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS574926A JPS574926A (en) | 1982-01-11 |
| JPS6212769B2 true JPS6212769B2 (en) | 1987-03-20 |
Family
ID=13659421
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7834680A Granted JPS574926A (en) | 1980-06-12 | 1980-06-12 | Separation of relatively easily soluble hydrocarbon from hydrocarbon mixture |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS574926A (en) |
| AR (1) | AR242624A1 (en) |
| AT (1) | AT375330B (en) |
| AU (1) | AU541746B2 (en) |
| CA (1) | CA1180301A (en) |
| GB (1) | GB2077753B (en) |
| HU (1) | HU187335B (en) |
| IN (1) | IN152086B (en) |
| MX (1) | MX159551A (en) |
| NO (1) | NO156447C (en) |
| YU (1) | YU113481A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4134391B2 (en) * | 1998-04-07 | 2008-08-20 | 日本ゼオン株式会社 | Separation and purification apparatus and method for separation and purification of unsaturated hydrocarbons |
| PL201117B1 (en) * | 2003-10-20 | 2009-03-31 | Polski Koncern Naftowy Orlen S | Method for releasing butadiene |
| US8080140B2 (en) | 2007-04-18 | 2011-12-20 | Exxonmobil Chemical Patents Inc. | Process for debottlenecking a system for the separation of a conjugated diolefin |
| JP5246027B2 (en) * | 2009-05-12 | 2013-07-24 | Ｊｓｒ株式会社 | Method for producing butadiene |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54138508A (en) * | 1978-04-05 | 1979-10-27 | Goodyear Tire & Rubber | Separation of conjugate dioleffin |
-
1980
- 1980-06-12 JP JP7834680A patent/JPS574926A/en active Granted
-
1981
- 1981-05-04 YU YU01134/81A patent/YU113481A/en unknown
- 1981-05-06 AR AR81285219A patent/AR242624A1/en active
- 1981-05-08 AU AU70300/81A patent/AU541746B2/en not_active Ceased
- 1981-05-11 HU HU811276A patent/HU187335B/en not_active IP Right Cessation
- 1981-05-12 GB GB8114421A patent/GB2077753B/en not_active Expired
- 1981-05-12 IN IN498/CAL/81A patent/IN152086B/en unknown
- 1981-06-11 CA CA000379589A patent/CA1180301A/en not_active Expired
- 1981-06-11 NO NO811982A patent/NO156447C/en unknown
- 1981-06-11 MX MX187764A patent/MX159551A/en unknown
- 1981-06-12 AT AT0264881A patent/AT375330B/en not_active IP Right Cessation
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54138508A (en) * | 1978-04-05 | 1979-10-27 | Goodyear Tire & Rubber | Separation of conjugate dioleffin |
Also Published As
| Publication number | Publication date |
|---|---|
| IN152086B (en) | 1983-10-15 |
| AR242624A1 (en) | 1993-04-30 |
| YU113481A (en) | 1983-12-31 |
| AU541746B2 (en) | 1985-01-17 |
| JPS574926A (en) | 1982-01-11 |
| HU187335B (en) | 1985-12-28 |
| NO156447B (en) | 1987-06-15 |
| MX159551A (en) | 1989-07-03 |
| CA1180301A (en) | 1985-01-02 |
| NO156447C (en) | 1987-09-23 |
| AT375330B (en) | 1984-07-25 |
| GB2077753B (en) | 1983-09-21 |
| AU7030081A (en) | 1981-12-17 |
| GB2077753A (en) | 1981-12-23 |
| ATA264881A (en) | 1983-12-15 |
| NO811982L (en) | 1981-12-14 |
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