JP4048737B2 - Method of purifying crude ethylene gas - Google Patents
Method of purifying crude ethylene gas Download PDFInfo
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- JP4048737B2 JP4048737B2 JP2001187927A JP2001187927A JP4048737B2 JP 4048737 B2 JP4048737 B2 JP 4048737B2 JP 2001187927 A JP2001187927 A JP 2001187927A JP 2001187927 A JP2001187927 A JP 2001187927A JP 4048737 B2 JP4048737 B2 JP 4048737B2
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- Prior art keywords
- ethylene gas
- crude ethylene
- gas
- alkali
- tower
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- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 title claims description 53
- 239000005977 Ethylene Substances 0.000 title claims description 53
- 238000000034 method Methods 0.000 title claims description 31
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 26
- 238000005406 washing Methods 0.000 claims description 24
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims description 19
- 238000004140 cleaning Methods 0.000 claims description 17
- 238000004519 manufacturing process Methods 0.000 claims description 15
- 239000001569 carbon dioxide Substances 0.000 claims description 13
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 13
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 239000002904 solvent Substances 0.000 claims description 9
- 239000012535 impurity Substances 0.000 claims description 8
- 239000004698 Polyethylene Substances 0.000 claims description 7
- -1 polyethylene Polymers 0.000 claims description 7
- 229920000573 polyethylene Polymers 0.000 claims description 7
- 150000004945 aromatic hydrocarbons Chemical class 0.000 claims description 4
- 230000000379 polymerizing effect Effects 0.000 claims description 2
- 238000009434 installation Methods 0.000 claims 1
- 239000003513 alkali Substances 0.000 description 30
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 18
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 15
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 10
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 6
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 238000006386 neutralization reaction Methods 0.000 description 6
- 229920000642 polymer Polymers 0.000 description 6
- 239000000243 solution Substances 0.000 description 4
- 238000005882 aldol condensation reaction Methods 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000011109 contamination Methods 0.000 description 3
- FYGHSUNMUKGBRK-UHFFFAOYSA-N 1,2,3-trimethylbenzene Chemical compound CC1=CC=CC(C)=C1C FYGHSUNMUKGBRK-UHFFFAOYSA-N 0.000 description 2
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 2
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- 230000005587 bubbling Effects 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000010887 waste solvent Substances 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- 238000004065 wastewater treatment Methods 0.000 description 2
- 239000008096 xylene Substances 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、粗エチレンガスの精製方法に関するものである。更に詳しくは、本発明は、不純物として酢酸ビニル及び二酸化炭素を含有する粗エチレンガスの精製方法であって、洗浄設備の汚れを防止することにより長期間の安定運転が可能であり、しかも洗浄用のアルカリの消費量を節減することができるという優れた特徴を有する粗エチレンガスの精製方法に関するものである。
【０００２】
【従来の技術】
石油化学工業において、エチレンを製造する方法として、エタン、プロパン、ナフサ、ガスオイル等を分解炉で熱分解する方法が知られている。エチレンの主用途のひとつとして、ポリエチレン製造用原料がある。ここで、エチレン製造設備とポリエチレン製造設備は、同じ又は隣接した工場内に設けられるのが一般である。ところで、ポリエチレン製造設備からは、未反応のエチレンを含む粗エチレンガスが回収される。該回収された粗エチレンガスには、酢酸ビニル、二酸化炭素等の不純物が含まれる。かかる不純物を含む粗エチレンガスを精製する方法として、アルカリ水溶液で洗浄する方法が知られている。しかしながら、従来の方法によると、使用中に重合物により洗浄設備が汚れ、よって長期間の安定運転が困難であるという問題があった。
【０００３】
【発明が解決しようとする課題】
かかる現状において、本発明が解決しようとする課題は、不純物として少なくとも酢酸ビニル及び二酸化炭素を含有する粗エチレンガスの精製方法であって、洗浄設備の汚れを防止することにより長期間の安定運転が可能であり、しかも洗浄用のアルカリ水溶液の消費量を節減することができるという優れた特徴を有する粗エチレンガスから酢酸ビニル及び二酸化炭素を除去する方法を提供する点にある。
【０００４】
【課題を解決するための手段】
すなわち、本発明は、不純物として少なくとも酢酸ビニル及び二酸化炭素を含有する粗エチレンガスの精製方法であって、下記の第一工程及び第二工程を含む粗エチレンガスの精製方法に係るものである。
第一工程：粗エチレンガスを炭素数６〜８の芳香族炭化水素を含む溶剤で洗浄する工程
第二工程：第一工程の洗浄後のガスをアルカリ水溶液で洗浄する工程
【０００５】
【発明の実施の形態】
本発明の原料である粗エチレンガスとしては、エチレンを重合してポリエチレンを得る設備から回収される粗エチレンガスをあげることができる。粗エチレンガスには、不純物として少なくとも酢酸ビニル及び二酸化炭素が含有される。酢酸ビニルの含有量は、通常１０００〜４０００ｍｏｌｐｐｍである。二酸化炭素の含有量は、通常１０００〜２０００ｍｏｌｐｐｍである。
【０００６】
本発明の第一工程は、粗エチレンガスを炭素数６〜８の芳香族炭化水素を含む溶剤で洗浄する工程である。炭素数６〜８の芳香族炭化水素としては、ベンゼン、トルエン、キシレン等を例示することができる。酢酸ビニルの、エチレン製造設備から回収される分解ガソリンへの溶解度は非常に大きく、かつ該分解ガソリンは酢酸ビニルを溶解したままでも製品として出荷できるため、溶剤としては該分解ガソリンを用いることが、溶剤入手及び廃溶剤処理が不要という観点から、好ましい。該分解ガソリンの組成としては、上記ベンゼン、トルエン及びキシレンの他にエチルベンゼン、スチレン、トリメチルベンゼン等をあげることができる。
【０００７】
第一工程を実施する方法及び条件の具体例としては、下記のものをあげることができる。
【０００８】
棚段塔或いは充填塔の塔底に粗エチレンガスを、塔頂には溶剤として分解ガソリンを供給する。粗エチレンガスは塔底に溜まった溶剤中へ吹き込まれ、バブリングした後に棚段部或いは充填部へ入る。塔底の分解ガソリンは液面を制御しながら抜き出される。棚段部或いは充填部で、バブリング後の粗エチレンガスと塔頂部のスプレーから供給される分解ガソリンの気液接触が行われた後、塔頂部より洗浄後の粗エチレンガスが第二工程へと抜き出される。
【０００９】
本工程の運転温度は供給する分解ガソリンの温度で制御できるが、酢酸ビニルの溶解度を向上させること及び後工程への酢酸ビニル及び分解ガソリンの混入を少なくするためにも、できるだけ運転温度を下げることが好ましく、海水熱交換器で分解ガソリンの冷却を行う観点から、運転温度は２５〜３０℃が好ましい。
【００１０】
本工程の運転圧力は洗浄設備の特性により決定されるものでは無く、粗エチレンガスの圧力やエチレン製造設備本体の運転圧力により自在に決定できる。
【００１１】
本発明の第二工程は、第一工程の洗浄後のガスをアルカリ水溶液で洗浄する工程である。アルカリとしては、水酸化ナトリウムを例示することができる。アルカリ水溶液中のアルカリ濃度は、ｐＨ１０．５〜１２．５であることが好ましい。該濃度が低すぎると二酸化炭素が後工程へリークする場合があり、一方該濃度が高すぎるとアルカリの浪費及びアルカリ排水のｐＨ上昇による排水処理設備の負荷上昇を招く場合がある。
【００１２】
第二工程を実施する方法及び条件の具体例としては、下記のものをあげることができる。
【００１３】
棚段塔或いは充填塔の塔底に第一工程を経た粗エチレンガスを、塔頂にはアルカリ水溶液として約５ｗｔ％の水酸化ナトリウム水溶液を供給する。棚段部或いは充填部では粗エチレンガスとアルカリ水溶液の向流接触が起き、二酸化炭素が化学吸収される。塔底部に溜まる炭酸塩を含んだアルカリ排水は、液面を制御しながら抜き出され、廃水処理設備へ送られる。塔頂部よりアルカリ洗浄後の粗エチレンガスが抜き出され、エチレン製造設備へ送られる。
【００１４】
アルカリ洗浄設備は、装置の汚れ防止対策として、２塔以上の洗浄塔を直列或いは並列に設置し、運転継続中でも個々の洗浄塔を単独に遮断し、内部を洗浄可能とすることができる。
【００１５】
本工程の運転温度は供給するアルカリ水溶液の温度で制御できるが、アルカリ排水に溶解している中和塩の析出を防ぐ観点から、温度を下げすぎることは好ましくなく、運転温度としては第一工程と同様の２５〜３０℃が好ましい。
【００１６】
本工程の運転圧力も第一工程と同様に、粗エチレンガスの圧力やエチレン製造設備本体の運転圧力により自在に決定できる。
【００１７】
一般に、エチレン製造設備では分解ガスを苛性洗浄するために多量の水酸化ナトリウム水溶液を扱っており、本発明においては、第一工程及び第二工程を行う設備が、エチレン製造設備のサイトに設けられていることが、溶剤入手、アルカリ水溶液入手及び廃溶剤処理が不要という観点から、好ましい。
【００１８】
本発明の最大の特徴は、第一工程を用いる点にある。つまり、本発明によらず、第二工程のみを用いた場合には、酢酸ビニルがアルカリ性雰囲気下おいて酢酸及びアセトアルデヒドへ加水分解する。ここで、生成した酢酸はアルカリと中和反応を起こしてアルカリを消費し、一方でアセトアルデヒドはアルカリ性雰囲気下においてアルドール縮合を生起し、その結果生成した重合物が徐々に蓄積し、設備を汚染するのである。そこで、該酢酸ビニルを本発明の第一工程で除去し、その後第二工程を用いるという特徴的な組み合わせを採用することにより、重合物の発生を防止し、更に酢酸の中和反応によるアルカリの消費を抑制することで、第二工程でのアルカリの消費量を節減することが可能となるのである。
【００１９】
【実施例】
比較例１
本発明の第二工程に相当するアルカリ洗浄塔のみから成る洗浄設備を用いて、ポリエチレン製造設備から回収される粗エチレンガスを精製した。なお、アルカリ洗浄塔は１塔単独で、棚段塔を用いた。通常状態の粗エチレンガス処理量は１．５〜２Ｔ／Ｈであり、アルカリ洗浄塔のｐＨが１０．５〜１２．５になるように約５ｗｔ％水酸化ナトリウム水溶液を供給した。その結果、アルカリ洗浄塔単独で粗エチレンガス中の酢酸ビニル及び二酸化炭素を処理するため、アルカリ洗浄塔内で酢酸ビニルの加水分解反応が進行して酢酸及びアセトアルデヒドが生成され、アルカリは二酸化炭素の中和に加えて酢酸の中和にも消費された。更に、アルカリ洗浄塔塔底部にはアセトアルデヒドのアルドール縮合により生成した重合物が析出したため、１日当たり３〜６回の頻度でアルカリ洗浄塔塔底液の抜き出し及び重合物の掻き取り作業が必要であった。
【００２０】
実施例１
本発明の第一工程としての分解ガソリン洗浄塔及び第二工程としてのアルカリ洗浄塔から成る洗浄設備を用いて、比較例１と同様にポリエチレン製造設備から回収される粗エチレンガスを精製した。なお、分解ガソリン洗浄塔及びアルカリ洗浄塔には充填塔を用い、アルカリ洗浄塔は２塔直列式とした。通常状態としては粗エチレンガス処理量は１．５〜２Ｔ／Ｈ、分解ガソリン供給量は２Ｔ／Ｈであり、１塔目のアルカリ洗浄塔塔底液のｐＨが１０．５〜１１．５、２塔目のアルカリ洗浄塔塔底液のｐＨが１１．５〜１２．５になる様に約５ｗｔ％水酸化ナトリウム水溶液を供給した。その結果、第一工程に当たるガソリン洗浄塔で粗エチレンガスから酢酸ビニルが除去されるため、第二工程に当たるアルカリ洗浄塔では酢酸ビニルの加水分解反応が起こらなくなった。従って、アルカリは二酸化炭素の中和のみに消費されることとなり、アルカリ消費量は比較例１で酢酸の中和に消費されていた量だけ減少した。更に、アルカリ洗浄塔内でのアセトアルデヒドのアルドール縮合も起こらず、アルカリ洗浄塔塔底部での重合物の生成は無くなったため、エチレン製造設備本体の定期修理間隔である２年間以上、該洗浄設備を遮断・洗浄すること無く連続で運転し続けることが可能となった。
【００２１】
【発明の効果】
以上説明したとおり、本発明により、不純物として酢酸ビニル及び二酸化炭素を含有する粗エチレンガスの精製方法であって、洗浄設備の汚れを防止することにより長期間の安定運転が可能であり、しかも洗浄用のアルカリの消費量を節減することができるという優れた特徴を有する粗エチレンガスの精製方法を提供することができた。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for purifying crude ethylene gas. More specifically, the present invention is a method for purifying crude ethylene gas containing vinyl acetate and carbon dioxide as impurities, which can be stably operated for a long period of time by preventing contamination of the cleaning equipment, and for cleaning. The present invention relates to a method for purifying crude ethylene gas having an excellent feature that the consumption of alkali can be reduced.
[0002]
[Prior art]
In the petrochemical industry, a method of thermally decomposing ethane, propane, naphtha, gas oil or the like in a cracking furnace is known as a method for producing ethylene. One of the main uses of ethylene is as a raw material for producing polyethylene. Here, the ethylene production facility and the polyethylene production facility are generally provided in the same or adjacent factories. By the way, crude ethylene gas containing unreacted ethylene is recovered from the polyethylene production facility. The recovered crude ethylene gas contains impurities such as vinyl acetate and carbon dioxide. As a method for purifying crude ethylene gas containing such impurities, a method of washing with an alkaline aqueous solution is known. However, according to the conventional method, there is a problem that the washing equipment is soiled by the polymer during use, and thus it is difficult to operate stably for a long time.
[0003]
[Problems to be solved by the invention]
Under such circumstances, the problem to be solved by the present invention is a method for purifying crude ethylene gas containing at least vinyl acetate and carbon dioxide as impurities, which prevents long-term stable operation by preventing contamination of the cleaning equipment. The object of the present invention is to provide a method for removing vinyl acetate and carbon dioxide from crude ethylene gas, which has the excellent feature of being capable of reducing consumption of an aqueous alkaline solution for cleaning.
[0004]
[Means for Solving the Problems]
That is, the present invention relates to a method for purifying crude ethylene gas containing at least vinyl acetate and carbon dioxide as impurities, and relates to a method for purifying crude ethylene gas including the following first step and second step.
First step: A step of washing crude ethylene gas with a solvent containing an aromatic hydrocarbon having 6 to 8 carbon atoms. Second step: A step of washing the gas after washing in the first step with an alkaline aqueous solution.
DETAILED DESCRIPTION OF THE INVENTION
Examples of the crude ethylene gas that is a raw material of the present invention include crude ethylene gas recovered from equipment for polymerizing ethylene to obtain polyethylene. The crude ethylene gas contains at least vinyl acetate and carbon dioxide as impurities. The content of vinyl acetate is usually 1000 to 4000 molppm. The content of carbon dioxide is usually 1000 to 2000 molppm.
[0006]
The first step of the present invention is a step of washing crude ethylene gas with a solvent containing an aromatic hydrocarbon having 6 to 8 carbon atoms. Examples of the aromatic hydrocarbon having 6 to 8 carbon atoms include benzene, toluene, xylene and the like. Since the solubility of vinyl acetate in cracked gasoline recovered from ethylene production facilities is very large, and the cracked gasoline can be shipped as a product even with vinyl acetate dissolved, it is necessary to use the cracked gasoline as a solvent. It is preferable from the viewpoint that solvent acquisition and waste solvent treatment are unnecessary. Examples of the composition of the cracked gasoline include ethylbenzene, styrene, trimethylbenzene and the like in addition to the above benzene, toluene and xylene.
[0007]
Specific examples of the method and conditions for carrying out the first step include the following.
[0008]
Crude ethylene gas is supplied to the bottom of the plate tower or packed tower, and cracked gasoline is supplied to the top of the tower as a solvent. Crude ethylene gas is blown into the solvent accumulated at the bottom of the tower, and after bubbling, enters the shelf or the filling section. The cracked gasoline at the bottom of the column is extracted while controlling the liquid level. After the bubbling of the crude ethylene gas and the cracked gasoline supplied from the spray at the top of the tower are brought into gas-liquid contact at the shelf or filling section, the washed crude ethylene gas is passed from the top of the tower to the second step. Extracted.
[0009]
The operating temperature of this process can be controlled by the temperature of the cracked gasoline to be supplied, but the operating temperature should be lowered as much as possible in order to improve the solubility of vinyl acetate and to reduce the mixture of vinyl acetate and cracked gasoline in the subsequent process. From the viewpoint of cooling cracked gasoline with a seawater heat exchanger, the operating temperature is preferably 25 to 30 ° C.
[0010]
The operating pressure in this step is not determined by the characteristics of the cleaning equipment, but can be freely determined by the pressure of the crude ethylene gas or the operating pressure of the ethylene production equipment main body.
[0011]
The second step of the present invention is a step of cleaning the gas after the cleaning in the first step with an alkaline aqueous solution. Sodium hydroxide can be illustrated as an alkali. The alkali concentration in the aqueous alkali solution is preferably pH 10.5 to 12.5. If the concentration is too low, carbon dioxide may leak to the subsequent process, while if the concentration is too high, waste of alkali and an increase in load on the wastewater treatment facility due to an increase in pH of the alkaline wastewater may be caused.
[0012]
Specific examples of the method and conditions for carrying out the second step include the following.
[0013]
Crude ethylene gas that has undergone the first step is supplied to the bottom of the plate tower or packed tower, and about 5 wt% sodium hydroxide aqueous solution is supplied to the top of the tower as an alkaline aqueous solution. Countercurrent contact between the crude ethylene gas and the alkaline aqueous solution occurs in the shelf or filling portion, and carbon dioxide is chemically absorbed. Alkaline wastewater containing carbonate that accumulates at the bottom of the tower is withdrawn while controlling the liquid level and sent to a wastewater treatment facility. The crude ethylene gas after alkali washing is extracted from the top of the column and sent to an ethylene production facility.
[0014]
The alkali cleaning equipment can install two or more cleaning towers in series or in parallel as a measure for preventing the contamination of the apparatus, and even while the operation is continued, the individual cleaning towers can be shut off independently so that the inside can be cleaned.
[0015]
The operating temperature of this step can be controlled by the temperature of the aqueous alkali solution to be supplied, but from the viewpoint of preventing the precipitation of the neutralized salt dissolved in the alkaline drainage, it is not preferable to reduce the temperature too much. The same temperature as 25 to 30 ° C is preferable.
[0016]
Similarly to the first step, the operation pressure in this step can be freely determined by the pressure of the crude ethylene gas and the operation pressure of the ethylene production facility main body.
[0017]
In general, ethylene production facilities handle a large amount of aqueous sodium hydroxide solution for caustic cleaning of cracked gas. In the present invention, facilities for performing the first step and the second step are provided at the site of the ethylene production facility. It is preferable from a viewpoint that a solvent acquisition, alkaline aqueous solution acquisition, and a waste solvent process are unnecessary.
[0018]
The greatest feature of the present invention is that the first step is used. That is, regardless of the present invention, when only the second step is used, vinyl acetate is hydrolyzed into acetic acid and acetaldehyde in an alkaline atmosphere. Here, the produced acetic acid causes a neutralization reaction with the alkali to consume the alkali, while the acetaldehyde causes the aldol condensation in an alkaline atmosphere, and as a result, the produced polymer gradually accumulates and contaminates the equipment. It is. Therefore, by adopting a characteristic combination in which the vinyl acetate is removed in the first step of the present invention and then the second step is used, the generation of a polymer is prevented, and further, the alkali is removed by neutralization reaction of acetic acid. By suppressing the consumption, it is possible to reduce the consumption of alkali in the second step.
[0019]
【Example】
Comparative Example 1
The crude ethylene gas recovered from the polyethylene production facility was purified using a cleaning facility consisting only of an alkali cleaning tower corresponding to the second step of the present invention. In addition, the alkali washing tower was one tower alone, and the plate tower was used. The processing amount of the crude ethylene gas in a normal state is 1.5 to 2 T / H, and about 5 wt% sodium hydroxide aqueous solution is supplied so that the pH of the alkali washing tower is 10.5 to 12.5. As a result, since the vinyl acetate and carbon dioxide in the crude ethylene gas are treated by the alkali washing tower alone, the hydrolysis reaction of vinyl acetate proceeds in the alkali washing tower to produce acetic acid and acetaldehyde. In addition to neutralization, it was also consumed for neutralization of acetic acid. Furthermore, since the polymer produced by the aldol condensation of acetaldehyde was deposited at the bottom of the alkali washing tower, it was necessary to extract the alkali washing tower bottom liquid and scrape the polymer at a frequency of 3 to 6 times per day. It was.
[0020]
Example 1
The crude ethylene gas recovered from the polyethylene production facility was purified in the same manner as in Comparative Example 1, using a cleaning facility comprising a cracked gasoline cleaning tower as the first step and an alkali cleaning tower as the second step. In addition, the cracking gasoline washing tower and the alkali washing tower used a packed tower, and the alkali washing tower was a two-column series type. As a normal state, the amount of crude ethylene gas treated is 1.5 to 2 T / H, the supply amount of cracked gasoline is 2 T / H, and the pH of the first alkali washing tower bottom liquid is 10.5 to 11.5, About 5 wt% aqueous sodium hydroxide solution was supplied so that the pH of the bottom alkali wash tower bottom liquid was 11.5 to 12.5. As a result, since vinyl acetate was removed from the crude ethylene gas in the gasoline washing tower corresponding to the first step, the hydrolysis reaction of vinyl acetate did not occur in the alkali washing tower corresponding to the second step. Therefore, the alkali was consumed only for neutralization of carbon dioxide, and the alkali consumption was reduced by the amount consumed for neutralization of acetic acid in Comparative Example 1. Furthermore, since no aldol condensation of acetaldehyde occurred in the alkali washing tower and no polymer was formed at the bottom of the alkali washing tower, the washing equipment was shut off for more than two years, which is the regular repair interval of the ethylene production equipment body. -It has become possible to continue to operate continuously without washing.
[0021]
【The invention's effect】
As described above, according to the present invention, the present invention is a method for purifying crude ethylene gas containing vinyl acetate and carbon dioxide as impurities. It was possible to provide a method for purifying crude ethylene gas having an excellent feature that the consumption of alkali for use can be reduced.
Claims (4)
第一工程：粗エチレンガスを炭素数６〜８の芳香族炭化水素を含む溶剤で洗浄する工程
第二工程：第一工程の洗浄後のガスをアルカリ水溶液で洗浄する工程A method for purifying crude ethylene gas containing at least vinyl acetate and carbon dioxide as impurities, the method comprising purifying crude ethylene gas comprising the following first step and second step.
1st process: Process which wash | cleans crude ethylene gas with the solvent containing C6-C8 aromatic hydrocarbon 2nd process: The process which wash | cleans the gas after washing | cleaning of 1st process with alkaline aqueous solution
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| Application Number | Priority Date | Filing Date | Title |
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| JP2001187927A JP4048737B2 (en) | 2001-06-21 | 2001-06-21 | Method of purifying crude ethylene gas |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001187927A JP4048737B2 (en) | 2001-06-21 | 2001-06-21 | Method of purifying crude ethylene gas |
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| JP2003002849A JP2003002849A (en) | 2003-01-08 |
| JP4048737B2 true JP4048737B2 (en) | 2008-02-20 |
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| JP2001187927A Expired - Fee Related JP4048737B2 (en) | 2001-06-21 | 2001-06-21 | Method of purifying crude ethylene gas |
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| JP4901025B2 (en) * | 2001-06-22 | 2012-03-21 | 株式会社ナリス化粧品 | Elastase inhibitor |
| EP1963464A1 (en) * | 2005-12-23 | 2008-09-03 | Ineos Europe Limited | Process for the removal of oxygenates from a gaseous stream |
| EP2566937A2 (en) * | 2010-05-07 | 2013-03-13 | Total Petrochemicals Research Feluy | Use of solvent to decrease caustic scrubber fouling |
| CN102516006B (en) * | 2011-11-11 | 2014-07-02 | 天津大学 | Method and device for recovering ethylene in vinyl acetate production process |
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