Concentrating evaporators – Film type – Moving film
Patent
1998-07-24
2000-05-23
Manoharan, Virginia
Concentrating evaporators
Film type
Moving film
159 131, 159 132, 159 431, 159 49, 159DIG15, 203 1, 203 86, 203 89, 202236, 2022671, 568913, 568868, B01D 106, B01D 122, C07C 2726
Patent
active
060662328
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for evaporating a liquid containing vaporizable oxidation-sensitive compounds.
A variety of evaporators are used in industry for a very wide range of applications. Examples are kettle evaporators, tubular evaporators, thin-film evaporators, short-path evaporators, plate evaporators and special evaporators for very highly viscous solutions and for encrusting and corrosive solutions (cf. for example Ullmanns Enzyklopadie der Technischen Chemie, 4th Edition, Vol. 2, pages 650-663).
The tubular evaporators include self-circulation and forced-circulation evaporators, inclined evaporators, fast-circulation evaporators, through-circulation evaporators, rising-film evaporators and also downflow or falling-film evaporators.
These evaporators are also used for evaporating liquids containing vaporizable oxidation-sensitive compounds.
Such a liquid is obtained, for example, in the preparation of glycols, in particular ethylene glycol. In the industrial process for the preparation of ethylene glycol, ethylene oxide is reacted with a roughly tenfold molar excess of water, either at atmospheric pressure and 50-70.degree. C. in the presence of a catalyst or at a reduced pressure of 20-40 bar and 140-230.degree. C. without a catalyst. The preparation of ethylene glycol is carried out almost exclusively in a reactor downstream of the direct oxidation of ethylene. The aqueous crude glycol solution obtained is concentrated to about 30% in evaporators and subjected to fractional distillation in a plurality of columns at reduce pressure (K. Weissermel and H. -J. Arpe, Industrielle organische Chemie, VCH Verlagsgesellschaft, 3rd Edition, page 161).
Glycols are oxidation-sensitive, particularly at relatively high temperature. They are oxidized in particular to aldehydes. For certain uses, for example for the preparation of polyesters, particularly high purity of the ethylene glycol is required (99.9% by weight). These glycols must comply with specific values for the boiling limits, the water content and the acid number (cf. Ullmanns Enzyklopadie der Technischen Chemie, 4th Edition, Vol. 8, pages 200-210; K. Weissermel and H. -J. Arpe, loc cit, page 162).
It is furthermore known that a thermally gentle distillation can be carried out by means of a falling-film evaporator connected to a distillation column in order to obtain heat-sensitive products, the heat-sensitive product being obtained by removing the falling-film evaporator discharge separately from the circulation stream taken off from the distillation column. This distillation process leads to a reduction in the boiling point of the mixture to be separated and hence to thermally gentle evaporation (cf. German Patent 3,338,488).
It is an object of the present invention to provide a process for evaporating a liquid containing vaporizable oxidation-sensitive compounds, in which the oxidation of the oxidation-sensitive compound is avoided.
It is a further object of the present invention to provide a process for evaporating a liquid containing vaporizable oxidation-sensitive compounds, in which the evaporation is carried out under gentle conditions.
It is a further object of the present invention to provide a process for evaporating a liquid containing vaporizable oxidation-sensitive compounds, in which the evaporated liquid is rectified.
It is a further object of the present invention to provide a process for evaporating a liquid containing vaporizable oxidation-sensitive compounds, in which the oxidation-sensitive compound is obtained in a very high yield and there is only very little contamination with oxidation products.
It is a further object of the present invention to provide a process for evaporating a liquid containing vaporizable oxidation-sensitive compounds in an evaporator, in which the oxidation of the oxidation-sensitive compound in the evaporator is avoided.
It is a further object of the present invention to provide an evaporator which enables the abovementioned processes to be carried out.
We have found that the aboveme
REFERENCES:
patent: 3997389 (1976-12-01), Winkler
patent: 4264538 (1981-04-01), Moore et al.
patent: 4298041 (1981-11-01), Lagana et al.
patent: 4404928 (1983-09-01), Perot et al.
patent: 4842055 (1989-06-01), Ohtsu
patent: 4925526 (1990-05-01), Havukainen
patent: 5770020 (1998-06-01), Koistinen et al.
patent: 5904807 (1999-05-01), Ramm-Schmidt et al.
Ullmann's Enz., vol. 2, pp. 650-653.
Ind. Org. Chem., 3 Aufl., pp. 161-162.
Patent Abst. of Japan, vol. 9, No. 184 (JP 60054702; Mar. 29, 1985).
Kruger Siegfried
Mohr Jurgen
Polt Axel Werner
Scholl Stephan
Staatz Hartmut
BASF - Aktiengesellschaft
Manoharan Virginia
LandOfFree
Method and vaporizer for vaporizing oxidation-sensitive compound does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and vaporizer for vaporizing oxidation-sensitive compound, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and vaporizer for vaporizing oxidation-sensitive compound will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1834574