CN100363321C - Rectification method in acetic acid synthesis process by low-pressure methanol carbonylation - Google Patents
Rectification method in acetic acid synthesis process by low-pressure methanol carbonylation Download PDFInfo
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- CN100363321C CN100363321C CNB200510022447XA CN200510022447A CN100363321C CN 100363321 C CN100363321 C CN 100363321C CN B200510022447X A CNB200510022447X A CN B200510022447XA CN 200510022447 A CN200510022447 A CN 200510022447A CN 100363321 C CN100363321 C CN 100363321C
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Abstract
The present invention discloses a rectifying method for a technology utilizing low-pressure carbonyl of methanol to synthesize acetic acids. The method comprises the steps that the vapor material generated by flash evaporation or evaporation is orderly delivered into a dehydrogenation tower, a dewatering tower and a finished product tower; when the vapor at the top of the finished product tower is condensed in a heat exchange device, and the discharged heat is used as a heating source for the dewatering tower; the condensing temperature of the finished product tower is higher than the boiling temperature of tower bottom liquid of the dewatering tower. The double-effect energy-saving process of the rectification is formed by the method, 50% of heating vapor is saved, and the energy consumed by the circulating water of the condenser of the original finished product tower is saved.
Description
Technical field
The present invention relates to the rectificating method in a kind of acetic acid synthesis process by low-pressure methanol carbonylation.
Background technology
Rectifying comprises three rectifying tower in the existing carbonyl synthesis acetic acid technology: lightness-removing column (also claiming just to steam tower), dehydration tower (drying tower) and finishing column (weight-removing column).Its technical process is as shown in Figure 1: the vapor-phase material that flasher or vaporizer produce enters lightness-removing column 1, is divided into two liquid phases, heavy phase Returning reactor after condenser of light component removal column 2 condensations in quantizer 3; A part of Returning reactor of light phase, a part is back to lightness-removing column 1 cat head.Lightness-removing column 1 tower bottoms heats with lightness-removing column reboiler 4, and tower bottoms is sent back to reactor.Draw thick acetic acid from lightness-removing column 1 rectifying section side line and be sent to dehydration tower 6, dehydration tower 6 overhead products are back to dehydration tower 6 cats head, rest part Returning reactor through dehydration tower condenser 7 condensation rear sections.Dehydration tower 6 tower bottomss heat with dehydration column reboiler 81, and tower bottoms is admitted to finishing column 9 further rectifying.A part of liquid return finishing column 9 cats head after 11 condensations of finishing column 9 overhead products process finishing column condenser, rest part returns dehydration tower 6 opening for feeds, and the acetic acid finished product is drawn by the side line near finishing column 9 cats head.Finishing column 9 tower stills are by finishing column reboiler 10 heating, and extraction contains acetic acid, the propionic acid waste liquid of heavy seeds at the bottom of the tower.
It is unreasonable that above-mentioned flow process weak point is that the energy of rectifying utilizes, and finishing column overhead vapours temperature is higher than 130 ℃, and this heat is taken away by the recirculated water of condenser, do not made full use of, and also need the required energy of consume water circulation.And the heating steam amount of dehydration tower and finishing column consumption accounts for 90% of quantity of steam that whole rectification process consumes.
Summary of the invention
The technical problem to be solved in the present invention provides the Finestill energy-saving method in a kind of acetic acid synthesis process by low-pressure methanol carbonylation.
For solving the problems of the technologies described above, technical solution of the present invention comprises that the vapor-phase material of flash distillation or evaporation generation is sent into lightness-removing column, dehydration tower and finishing column successively carries out rectifying, liberated heat is as the heating source of dehydration tower during condensation in heat exchanger for the steam of finishing column cat head, and the condensing temperature of finishing column is higher than the boiling temperature of dehydration tower tower bottoms.
Because the condensing temperature of finishing column is higher than the boiling temperature of dehydration tower tower bottoms, makes the heat-transfer surface of heat exchanger that enough temperature heads be arranged, thus the thermal source that the steam of realization finished product column overhead boils as dehydration tower again, the economic benefits and social benefits energy-saving process of composition rectifying.Not only can save nearly 50% heating steam, also save the energy that recirculated water consumed of former finishing column condenser.Described heat exchanger can adopt again and boil-condenser.
The boiling temperature that is optimized for dehydration tower of concrete processing condition and operation absolute pressure are respectively 115～145 ℃ and normal pressure～200kPa, and the condensing temperature of finishing column and operation absolute pressure are respectively 120～160 ℃ and 150～500kPa.The concrete operations force value of finishing column is decided by the needed temperature head of heat exchanger heat-transfer surface.
In the prior art, the principal goods material of lightness-removing column is drawn charging as dehydration tower from the rectifying section side line, wherein contain noncondensable gases such as carbon monoxide, because reactor is to the instability of flow of the noncondensable gas of vaporizer, the resistance on absorption tower changes thereupon, and cause the pressure surge of dehydration tower, thereby reduce the separation accuracy of dehydration tower.Must control the pressure of dehydration tower for this reason, make its pressure much higher, to cut down the influence of pressure surge than lightness-removing column.So just caused the temperature of dehydration Tata still to raise, greater than 150 ℃.Among the present invention, the de-gassing vessel of a reduction dehydration tower working pressure is installed on the dehydration tower feeding line, this de-gassing vessel can or have carrying for a short time of fractionation section for degassing vessel and heat up in a steamer tower, non-condensable gases such as dissolved carbon monoxide in the charging are sloughed, making does not have dissolved gases to discharge in the dehydration tower condenser, its blow-down pipe also needn't cause absorption tower and flare system again.The working pressure of dehydration tower can drop to normal pressure or near normal pressure like this, thereby can reduce the temperature of dehydration tower.
Degassing vessel or carry heats up in a steamer the condenser that gas that tower produces can be sent lightness-removing column or lightness-removing column back to, and optimum is sent lightness-removing column back to.Degassing vessel or carry and heat up in a steamer tower and should not outgas by decompression is because after pressure reduced, non-condensable gas that flashes off and methyl iodide, acetic acid just can not have been got back to lightness-removing column and absorption system.Thereby should adopt the external heating mode degassing, odd thermal source can be used for heating herein, as the steam condensate of finishing column reboiler.
Dehydration tower in the rectifying and finishing column can be tray columns, also can be packing towers.The pressure of packing tower falls less, can reduce the pressure of the required heating steam of finishing column, further cut down the consumption of energy, but the more board-like tower height of its investment, therefore concrete selection will be decided according to economic comprehensive evaluation result.
Below embodiment by Fig. 2 and embodiment the present invention is further detailed explanation.
Description of drawings
Fig. 1 is the rectification process schematic flow sheet in the prior art synthesizing acetic acid by methanol low-pressure carbonylation;
Fig. 2 is a rectification process schematic flow sheet of the present invention.
Embodiment
As shown in Figure 2, rectification process flow process of the present invention is as follows: the vapor-phase material that flasher or vaporizer produce enters lightness-removing column 1, is divided into two liquid phases in condenser of light component removal column 2 after the condensation in quantizer 3, and heavy phase contains methyl iodide, Returning reactor; Gently be dilute acetic acid mutually, a part of Returning reactor, a part is back to lightness-removing column 1 cat head.Lightness-removing column 1 tower bottoms heats with lightness-removing column reboiler 4, and tower bottoms is the dense acetic acid that contains hydrogen iodide, is sent back to reactor.Draw thick acetic acid from lightness-removing column 1 rectifying section side line and be sent to degassing vessel 5, the liquid major part of deviating from behind the non-condensable gas is sent to dehydration tower 6, small portion returns next column plate of lightness-removing column 1 side line extraction plate, and the gas that degassing vessel 5 produces draws back the top vapor phase space of lightness-removing column 1 side line extraction plate.Dehydration tower 6 overhead products are dilute acetic acid, and through dehydration tower condenser 7 condensation rear section Returning reactors, partial reflux is to dehydration tower 6 cats head.Dehydration tower 6 tower kettle products are Glacial acetic acid, are admitted to finishing column 9 further rectifying.The introducing of the acetic acid finished product steam of finishing column 9 cats head is boiled-condenser 82 again, in order to thermal dehydration tower 6 tower bottomss.Boil again-the phlegma part of condenser 82 passes back into finishing column 9 cats head, and a part is drawn as finished product.When containing micro-iodide in the phlegma, the sub-fraction phlegma can be drawn back dehydration tower 6 chargings, rest part passes back into finishing column 9 cats head, and by the side line extraction acetic acid finished product near finishing column 9 cats head.Finishing column 9 tower stills are by finishing column reboiler 10 heating, and extraction contains acetic acid, the propionic acid waste liquid of heavy seeds at the bottom of the tower.
The vapor-phase material flow that flasher produces is 68.81t/h, forms (weight percent, below identical) to be: condensing 1.02%, hydrogen iodide 0.06%, methyl iodide 37.98%, ritalin 1.55%, water 11.64%, acetic acid 47.62%, propionic acid 0.13%.Lightness-removing column 1 tower top pressure 190kPa (absolute pressure, below identical), the liquid flow rate (mol/h) that reflux ratio promptly enters rectifying section is 2.0 with the ratio of overhead distillate flow (mol/h), lightness-removing column reboiler 4 adds heat 1.633Mw.Dehydration tower 6 tower top pressure 110kPa, reflux ratio 1.2.Finishing column 9 tower top pressure 250kPa, reflux ratio 3.0, finishing column reboiler 10 adds heat 12.903Mw.Dehydration tower 6 tower bottomss and finishing column 9 overhead vapours are boiling again-carry out heat exchange in the condenser 82, dehydration tower 6 tower bottomss are boiling again-condenser 82 in boiling, need to add heat 11.020Mw, boiling temperature is 130.3 ℃; Finishing column 9 overhead vapours are boiling again-condenser in 8 condensations, heat 12.602Mw is emitted in condensation, 150.6 ℃ of condensing temperatures are boiled-20 ℃ of the condenser 82 heat-transfer surface temperature difference again.Through obtaining acetic acid finished product 21.1t/h after three tower rectifying, wherein moisture＜0.01% contains propionic acid＜0.007%.Waste liquid consists of acetic acid 39.4% at the bottom of the finished product Tata, propionic acid 60.6%.The gross calorific value of three tower reboiler needs is 14.536Mw, and it is 20.81Mw that three tower condensers need be removed the heat total value.
The comparative example 1
The vapor-phase material flow that flasher produces is 68.81t/h, and consist of: condensing 1.02%, hydrogen iodide 0.06%, methyl iodide 37.98%, ritalin 1.55%, water 11.64%, acetic acid 47.62%, propionic acid 0.13%.Lightness-removing column 1 tower top pressure 190kPa, reflux ratio 2.0, lightness-removing column reboiler 4 adds heat 1.633Mw.Dehydration tower 6 tower top pressure 110kPa, reflux ratio 1.2.Dehydration column reboiler 81 adds heat 11.020Mw.Finishing column 9 tower top pressure 250kPa, reflux ratio 3.0, finishing column reboiler 10 adds heat 12.903Mw.The gross calorific value of three tower reboiler needs is 25.556Mw, and it is 31.70Mw that three tower condensers need be removed the heat total value.
Contrast shows: after using flow process of the present invention, can save dehydration column reboiler 81 heating steams 43%, and can save the required recirculated water of finishing column condenser 11.In the rectification working process of the present invention the heat exchange total amount of condenser only be in the traditional technology heat exchange total amount 66%.
Embodiment 2 lightness-removing columns, dehydration tower, finishing column are the porcelain corrugated-plate packed tower
The vapor-phase material flow that flasher produces is 6.525t/h, and consist of: condensing 0.98%, hydrogen iodide 0.04%, methyl iodide 37.38%, ritalin 1.61%, water 11.97%, acetic acid 47.9%, propionic acid 0.12%.Lightness-removing column 1 tower top pressure 190kPa, reflux ratio 2.0, lightness-removing column reboiler 4 adds heat 0.06Mw.Dehydration tower 6 tower top pressure 110kPa, reflux ratio 1.4.Finishing column 9 tower top pressure 200kPa, reflux ratio 2.8, finishing column reboiler 10 adds heat 1.30Mw.Dehydration tower 6 tower bottomss and finishing column 9 overhead vapours are boiling again-carry out heat exchange in the condenser 82, dehydration tower 6 tower bottomss are boiling again-condenser 82 in boiling, need to add heat 1.15Mw, boiling temperature is 121.4 ℃; Finishing column 9 overhead vapours are boiling again-condenser 82 in condensation, heat 1.27Mw is emitted in condensation, 141.9 ℃ of condensing temperatures are boiled-20 ℃ of the condenser 82 heat-transfer surface temperature difference again.Through obtaining acetic acid finished product 2.25t/h after three tower rectifying, wherein moisture＜0.01% contains propionic acid＜0.005%.Waste liquid consists of at the bottom of the finished product Tata: acetic acid 44.9%, propionic acid 55.1%.The gross calorific value of three tower reboiler needs is 1.36Mw, and it is 2.04Mw that three tower condensers need be removed the heat total value.
The comparative example 2
The vapor-phase material flow that flasher produces is 6.525t/h, and consist of: condensing 0.98%, hydrogen iodide 0.04%, methyl iodide 37.38%, ritalin 1.61%, water 11.97%, acetic acid 47.9%, propionic acid 0.12%.Lightness-removing column 1 tower top pressure 190kPa, reflux ratio 2.0, lightness-removing column reboiler 4 adds heat 0.06Mw.Dehydration tower 6 tower top pressure 110kPa, reflux ratio 1.4, dehydration column reboiler 81 adds heat 1.15Mw.Finishing column 9 tower top pressure 200kPa, reflux ratio 2.8, finishing column reboiler 10 adds heat 1.30Mw.The gross calorific value of three tower reboiler needs is 2.51Mw, and it is 3.07Mw that three tower condensers need be removed the heat total value.
Contrast shows: after using flow process of the present invention, can save dehydration column reboiler 81 heating steams 46%, and can save the required recirculated water of finishing column condenser 11.In the rectification working process of the present invention the heat exchange total amount of condenser only be in the traditional technology heat exchange total amount 66%.
Claims (6)
1. the rectificating method in the acetic acid synthesis process by low-pressure methanol carbonylation, comprise that the vapor-phase material of flash distillation or evaporation generation is sent into lightness-removing column, dehydration tower and finishing column successively carries out rectifying, it is characterized in that, liberated heat is as the heating source of dehydration tower during condensation in heat exchanger with the steam of finishing column cat head, and the condensing temperature of finishing column is higher than the boiling temperature of dehydration tower tower bottoms.
2. the rectificating method in a kind of acetic acid synthesis process by low-pressure methanol carbonylation according to claim 1 is characterized in that, described heat exchanger is for boiling-condenser again.
3. the rectificating method in a kind of acetic acid synthesis process by low-pressure methanol carbonylation according to claim 1 and 2, it is characterized in that, the boiling temperature of described dehydration tower and operation absolute pressure are respectively 115～145 ℃ and normal pressure～200kPa, and the condensing temperature of finishing column and operation absolute pressure are respectively 120～160 ℃ and 150～500kPa.
4. the rectificating method in a kind of acetic acid synthesis process by low-pressure methanol carbonylation according to claim 1 and 2 is characterized in that, the de-gassing vessel of a reduction dehydration tower working pressure is set on the feeding line of described dehydration tower.
5. the rectificating method in a kind of acetic acid synthesis process by low-pressure methanol carbonylation according to claim 4 is characterized in that, described de-gassing vessel is degassing vessel or has carrying of fractionation section and heat up in a steamer tower.
6. the rectificating method in a kind of acetic acid synthesis process by low-pressure methanol carbonylation according to claim 4 is characterized in that, the gas that described de-gassing vessel produces is admitted to the condenser of lightness-removing column or lightness-removing column.
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| US8637698B2 (en) * | 2010-11-19 | 2014-01-28 | Celanese International Corporation | Production of acetic acid with an increased production rate |
| KR101264603B1 (en) * | 2011-09-15 | 2013-05-24 | 강기준 | Apparatus and method for recovering of carboxylic acid and removing of water from reactor emission in the oxidation process of aromatic compound by using energy contributing combined distillation |
| CN104805290B (en) * | 2015-03-27 | 2017-11-03 | 中国昆仑工程有限公司 | The method of recovery of acetic acid and cobalt manganese from PTA thin film evaporator blanking residues |
| CN111348998A (en) * | 2020-04-17 | 2020-06-30 | 湖北三里枫香科技有限公司 | Energy-saving environment-friendly acetic acid production process |
| CN115634637B (en) * | 2022-10-26 | 2023-12-29 | 西南化工研究设计院有限公司 | Control system for propionic acid content in methanol low-pressure oxo-synthesis acetic acid product |
| CN115634636B (en) * | 2022-10-26 | 2024-03-15 | 西南化工研究设计院有限公司 | Automatic control system and method for synthesizing acetic acid by methanol low-pressure carbonyl |
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| CN1069262A (en) * | 1992-08-13 | 1993-02-24 | 化学工业部西南化工研究院 | Process for synthesis of acetic acid by methanol carbony lation under lower pressure in liquid phase |
| US5750007A (en) * | 1993-03-26 | 1998-05-12 | Bp Chemicals Limited | Process for the recovery of a carbonylation product |
| CN1247852A (en) * | 1998-08-06 | 2000-03-22 | 赫多特普索化工设备公司 | Method for preparing and purifying acetate by reaction distillation effect |
| WO2005085163A1 (en) * | 2004-03-02 | 2005-09-15 | Celanese International Corporation | Process for producing acetic acid |
| JP2005289936A (en) * | 2004-04-02 | 2005-10-20 | Daicel Chem Ind Ltd | Method of separating hydrogen iodide |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1069262A (en) * | 1992-08-13 | 1993-02-24 | 化学工业部西南化工研究院 | Process for synthesis of acetic acid by methanol carbony lation under lower pressure in liquid phase |
| US5750007A (en) * | 1993-03-26 | 1998-05-12 | Bp Chemicals Limited | Process for the recovery of a carbonylation product |
| CN1247852A (en) * | 1998-08-06 | 2000-03-22 | 赫多特普索化工设备公司 | Method for preparing and purifying acetate by reaction distillation effect |
| WO2005085163A1 (en) * | 2004-03-02 | 2005-09-15 | Celanese International Corporation | Process for producing acetic acid |
| JP2005289936A (en) * | 2004-04-02 | 2005-10-20 | Daicel Chem Ind Ltd | Method of separating hydrogen iodide |
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Application publication date: 20060719 Assignee: Serra nice (Nanjing) Chemical Co., Ltd. Assignor: Southwest Chemical Research & Design Institute Co., Ltd. Contract record no.: 2013990000015 Denomination of invention: Rectification method in acetic acid synthesis process by low-pressure methanol carbonylation Granted publication date: 20080123 License type: Exclusive License Record date: 20130114 |
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