WO1999026911A1 - Procede de condensation - Google Patents

Procede de condensation Download PDF

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Publication number
WO1999026911A1
WO1999026911A1 PCT/EP1998/007491 EP9807491W WO9926911A1 WO 1999026911 A1 WO1999026911 A1 WO 1999026911A1 EP 9807491 W EP9807491 W EP 9807491W WO 9926911 A1 WO9926911 A1 WO 9926911A1
Authority
WO
WIPO (PCT)
Prior art keywords
gas
acrolein
condensation
gas mixture
column
Prior art date
Application number
PCT/EP1998/007491
Other languages
German (de)
English (en)
Inventor
Michael-Dieter Ulbrich
Armin Schraut
Ulrich Hammon
Volker Schliephake
Original Assignee
Basf Aktiengesellschaft
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Basf Aktiengesellschaft filed Critical Basf Aktiengesellschaft
Publication of WO1999026911A1 publication Critical patent/WO1999026911A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D301/00—Preparation of oxiranes
    • C07D301/32—Separation; Purification
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0027—Condensation of vapours; Recovering volatile solvents by condensation by direct contact between vapours or gases and the cooling medium
    • B01D5/003—Condensation of vapours; Recovering volatile solvents by condensation by direct contact between vapours or gases and the cooling medium within column(s)
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/78—Separation; Purification; Stabilisation; Use of additives
    • C07C45/81—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives

Definitions

  • the invention relates to a method for the condensation of one or more components from a gas mixture.
  • Such processes are used, for example, in the processing of gaseous reaction mixtures, with condensable by-products or impurities first being removed by condensation.
  • the main product remaining in the gas phase is then taken up in a suitable absorbent and separated therefrom, for example by stripping.
  • Such a sequence of work-up steps is common, for example, in the production of (meth) acrolein or (meth) acrylic acid.
  • EP-B 0 559 227 discloses a process for the preparation of acrolein by working up a gas mixture which is formed in the catalytic gas phase oxidation of propene.
  • the condensation conditions are set here so that the condensate from the bottom of the column has a temperature between 35 ° and 50 ° C., the gas drawn off at the top has a temperature between 35 ° and 55 ° C., and that the temperature of the gas separated off at the top is approximately the same or is greater than the temperature of the condensate in the column bottom.
  • the condensate stream to be fed to the column is separated into two partial streams, a first partial stream being fed to the lower column part after prior cooling and a second partial stream to the upper column part without being cooled.
  • the residence time of the condensate in the cooling column and the circulating section is limited to 0.5 to 3 hours.
  • the procedure described is intended to form acrolein hydrate in the condensate which is obtained when the product mixture is worked up for the production of acrolein. be inhibited.
  • a disadvantage of this procedure is that, due to the large temperature difference between supercooled condensate and saturated gas, fog droplets can form in the presence of condensation nuclei.
  • the object of the invention is therefore to provide a process for working up gaseous reaction products which avoids the formation of mist, reduces the loss of gaseous reaction product in the condensate and reduces the formation of by-products.
  • the solution is based on the known method for condensing one or more components from a gas mixture in a condenser.
  • the method according to the invention is then characterized in that the temperature difference between the gas mixture and the cooling surface at each point of the condenser is less than 25 ° C, in particular less than 20 ° C.
  • a condenser is known in a known manner in which condensation takes place on a cooling surface.
  • the cooling surface can be generated as a cold wall, for example in a tube bundle or plate heat exchanger, or as a liquid film, for example in a column with falling film internals.
  • Hot gaseous reaction products are often worked up by evaporating a solvent, for example water, in a quench column in a first cooling step, the heat of vaporization being used for gas cooling.
  • a solvent for example water
  • the reaction gas saturated with the solvent must be cooled further become.
  • the evaporated solvent and also gaseous by-products are condensed from the reaction gas by contact with supercooled condensate. If the temperature difference between supercooled condensate and reaction gas is too large, the reaction gas is cooled down faster than the solvent and by-products can condense. The heat transfer is then faster than the mass transfer belonging to the thermodynamic equilibrium. An imbalance in the gas phase occurs, which is called supersaturation.
  • the method is not restricted in terms of temperature: it can be carried out in the range from 50 Kelvin to 600 Kelvin, preferably from 200 Kelvin to 400 Kelvin, usually in the range from 270 to 370 Kelvin.
  • the components of the gas mixture as a rule only the portion corresponding to the thermodynamic equilibrium at the temperature of the process is condensed, so partial condensation generally takes place.
  • the method is particularly suitable for condensation in the presence of at least 100 condensation nuclei per cm 3 , preferably at least 1000 nuclei per cm, particularly preferably of at least 10,000 germs per cm 3 .
  • the method is particularly suitable for condensation from gas mixtures with a Lewis index of 0.8 to 5.0, preferably 0.9 to 3.0, particularly preferably 5 0.9 to 1.5.
  • the Lewis index is defined as the ratio between the temperature conductivity a of the gas mixture and the diffusion coefficient of the condensing substance A in the gas phase:
  • the Lewis index expresses the relationship between heat transfer and material transfer in a gas mixture.
  • the value used as the coefficient of diffusion D is that of the components of the gas mixture
  • the temperature difference between the gas phase and the cooling surface at each point of the condenser is less than 15 ° C., in particular less than
  • the Lewis index is approximately 0.9. With a concentration of condensation nuclei of at least 1000 nuclei per cm, fog formation at a temperature gradient of maximum 25 ° C between the gas mixture and the cooling surface is avoided.
  • a liquid film in particular an aqueous liquid film and / or a cold wall, is equally suitable as the cooling surface.
  • Another application of the process is the partial water vapor condensation from water vapor-saturated flue gases with supercooled washing solutions. The supersaturated water vapor forms very quickly on the fine dust usually present in flue gases.
  • the process can be carried out in such a way that the gas phase and liquid film are carried out in cocurrent or in countercurrent.
  • the condensation can take place in one or more stages, preferably in two stages.
  • two-stage or multi-stage cooling and condensation in the case of countercurrent flow of gas and liquid, a first partial flow of the condensate from the bottom of the column into the lower part of the column and a further partial flow of condensate from the bottom of the column after prior cooling in the upper part of the column as cooling medium to be led back.
  • the process is particularly suitable for the separation of condensable organic substances from gas mixtures which have been produced in particular in gas phase reactions, preferably for the separation of (meth) acrylic acid and / or (meth) acrolein and / or glyoxal and / or ethylene oxide and / or aniline from gas mixtures .
  • FIG 1 shows the dependence of the fog formation in the condensation of
  • Figure 2 shows a process scheme for the production of acrolein
  • FIG. 3 shows a section of the process diagram for the production of acrolein, which relates to the condensation from the reaction gas, which is the focus of the present invention (FIG. 3a),
  • FIG. 3b shows the diagram of a condensation according to the prior art
  • FIG. 4 shows the temperature difference between the gas phase and the liquid phase, which are in direct contact with one another, plotted over the column height h, curve a representing the method according to the invention and curve b representing the prior art
  • the reaction gas contained about 3 x 10 nuclei per cm with an average diameter of 0.13 ⁇ m, the number and size of nuclei using an SMPS device (Scanning Mobile Particle Sizer) according to the "Scanning Electrical Mobility Spectrometer” in SC Wang and RC Flagen “, Aerosol Science and Technology 13, pages 230 to 30 240, (1990).
  • the signal of a transmitted light probe was determined depending on the temperature difference between the reaction gas and with measured in this cooling water in direct contact.
  • the signal of the transmitted light probe in mV is a measure of the amount of fog formed. At temperature differences between the reaction gas and cooling water below about 20 ° C, the transmitted light probe no longer showed any fog.
  • reaction gas contained nitrogen, oxygen, carbon dioxide, carbon monoxide and the starting material methacrolein.
  • Example 1 The predominantly condensing component in Example 1 is water vapor.
  • Example 2 relates to a two-stage procedure for the condensation of water and by-products from the reaction gas which is particularly suitable for the reaction gas cooling in the production of acrolein.
  • Acrolein is technically produced by the heterogeneously catalyzed oxidation of propene with atmospheric oxygen:
  • reaction gas from the propene oxidation is worked up in a system shown schematically in FIG. 2:
  • the approximately 220 ° C hot reaction gas which mainly contains nitrogen (76.6% by weight), acrolein (8.9% by weight) and water (4.7% by weight), is fed 1 in via a feed line the upper part of a quench column K 1, and brought into contact with a quench circulation solution 2, which consists predominantly of water, and also acrolein, acrylic acid, acetic acid and aldehydes.
  • the reaction gas is cooled to about 70 ° C. at a pressure of 1.8 bar by partial evaporation of the aqueous quench circuit solution.
  • the approximately 70 ° C hot, water vapor-saturated reaction gas 3 is fed from the bottom of the quench column K 1 to the bottom part of the absorption column K 2.
  • the steam-saturated reaction gas 3 predominantly contains nitrogen (71.5% by weight), water (10.8% by weight) and acrolein (8.7% by weight).
  • the water vapor-saturated reaction gas 3 is cooled in two stages to about 30 ° C. in the lower part I of the absorption column K 2.
  • the work-up step of the saturated reaction gas in the lower part 1 of the absorption column K 2 by cooling and condensation is essential for the present invention: Therefore the lower part 1 of the absorption column K 2 with the associated process parameters was shown separately in FIG. 3a.
  • the condensate flowing out of the absorption column K 2 is separated into two partial streams, a partial stream 4 being fed to the second condensation stage 7 of the lower column part I after cooling in a cooler 5.
  • the rest of the still hot condensate 6 is led to the first condensation stage 8 of the lower column part I and mixed there with the colder condensate stream flowing out of the second condensation stage 7.
  • the acrolein is absorbed from the reaction gas with a circulated aqueous solution 9.
  • the exhaust gas 10 is removed via the top of the absorption column K 2.
  • the circulating water 9 loaded with acrolein is separated in the distillation column K 3 into the acrolein / water azeotrope 11 at the top of the column K 3 and the circulating water 12 containing the high boilers at the bottom of the column.
  • the circulating water 12, which has largely been freed from acrolein, is used again after absorption to about 30 ° C. for the absorption of acrolein in the absorption column K 2.
  • Fresh water 13 is fed to the circulating water 9 to discharge by-products.
  • the cycle water purge 14 loaded cycle water reaches the lower part I of the absorption column K 2. From the condensation circuit, this purge runs together with the condensate as the condensate purge 15 into the quench circuit.
  • the final removal of by-products and water from the process is carried out via a purge 16 in the quench circuit.
  • FIG. 3a represents the process control according to the prior art.
  • a reaction tion gas stream of 31.5 m / h cooled from 72 ° C to 30 ° C in two stages.
  • a first partial stream 4 of the condensate circuit was cooled from 180 I / h in a cooler 5 to 30 ° C and in the second condensation stage 7 with the Reaction gas brought into contact from the first condensation stage 8 In the first condensation stage 8, the remaining partial stream 6 of the condensate of 300 l / h was passed uncooled to the first condensation stage 8 and mixed there with the colder condensate stream running out of the second condensation stage 7
  • curve a shows the course of the temperature difference for the procedure according to FIG. 3a
  • curve b shows the course of the temperature difference for the procedure according to FIG. 3b.
  • the condensate TL1 drawn off at the bottom of the column is hotter according to the inventive method (57 ° C.) compared to the known method (41 ° C.); therefore less product in the gas phase, for example acrolein, can dissolve in the condensate and less product is available in the liquid phase for undesired reactions of the product, for example the acid-catalyzed hydrolysis of acrolein.

Abstract

L'invention concerne un procédé permettant de réaliser la condensation d'un ou de plusieurs composants, à partir d'un mélange gazeux, dans un condenseur, la différence de température entre le mélange gazeux et la surface de refroidissement de chaque point du condenseur étant inférieure à 25 DEG C, en particulier inférieure à 20 DEG C. Le procédé présenté convient particulièrement pour la séparation de produits de réaction condensables et/ou de leurs produits secondaires, à partir de gaz de réaction, de préférence pour la séparation d'acide (méth)acrylique et/ou de (méth)acroléine et/ou de glyoxal et/ou d'oxyde d'éthylène et/ou d'aniline.
PCT/EP1998/007491 1997-11-25 1998-11-20 Procede de condensation WO1999026911A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19752199.1 1997-11-25
DE1997152199 DE19752199A1 (de) 1997-11-25 1997-11-25 Verfahren zur Kondensation

Publications (1)

Publication Number Publication Date
WO1999026911A1 true WO1999026911A1 (fr) 1999-06-03

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1998/007491 WO1999026911A1 (fr) 1997-11-25 1998-11-20 Procede de condensation

Country Status (2)

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DE (1) DE19752199A1 (fr)
WO (1) WO1999026911A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6596129B1 (en) 1999-11-08 2003-07-22 Nippon Shokubai Co., Ltd. Distillation process for easily polymerizable substance-containing solution

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4925981A (en) * 1982-01-22 1990-05-15 Nippon Shokubai Kagaku Kogyo Co., Ltd. Method of isolating methacrylic acid
EP0559227A2 (fr) * 1992-03-06 1993-09-08 Sumitomo Chemical Company Limited Procédé de préparation d'acroleine

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4925981A (en) * 1982-01-22 1990-05-15 Nippon Shokubai Kagaku Kogyo Co., Ltd. Method of isolating methacrylic acid
EP0559227A2 (fr) * 1992-03-06 1993-09-08 Sumitomo Chemical Company Limited Procédé de préparation d'acroleine

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
BARTHOLOME ET AL.: "Ullmanns Encyclopädie der technischen Chemie Band 2", 1972, VERLAG CHEMIE, WEINHEIM, XP002099564 *
FALBE, REGITZ: "Römpp Chemie Lexikon", 1993, G. THIEME VERLAG, STUTTGART-NEW YORK, XP002099565 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6596129B1 (en) 1999-11-08 2003-07-22 Nippon Shokubai Co., Ltd. Distillation process for easily polymerizable substance-containing solution

Also Published As

Publication number Publication date
DE19752199A1 (de) 1999-05-27

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