CH624854A5 - Process for removing water from an aqueous solution - Google Patents

Description

The invention relates to the removal of water from aqueous solutions.

It is known that solid hydrates can be formed from certain hydrate-forming liquids and water from aqueous solutions, such as sea water, and that after the solid hydrate has been separated off by filtration or a similar mechanical process, pure water can be obtained from the separated hydrate by decomposing it can be. For example, in the case of solutions where the solute solidifies at the temperatures maintained to form the solid hydrate, no filtration methods can be used to separate the solid hydrate from the rest of the mixture.

The object of the invention is therefore to provide a method for removing water from aqueous solutions of the type according to which a solid hydrate is formed, the solid hydrate being separated from the solid phase, preferably in a non-mechanical manner.

The invention relates to a method for removing water from an aqueous solution, which is defined in claim 1.

In performing a preferred separation process, the solid mixture resulting from the treatment of the aqueous solution with the hydrate-forming fluid is subjected to temperature and pressure conditions such that the solid hydrate breaks down into ice and hydrate-forming agents, the hydrate-forming agent being removed by vacuum evaporation while the mixture of ice and solid solute is preferably separated by differential sublimation or fractional sublimation. In the event that the solute is acetic acid and the hydrate-forming fluid is trichlorofluoromethane (also known under the trademark Freon 11, hereinafter referred to as TCFM), the decomposition of the hydrate-forming agent is usually at around 0 ° C or below and at a pressure of about 750 mm Hg or less at 0 ° C or a correspondingly lower pressure at lower temperatures.

Fractional sublimation to remove the ice can be performed at about 0 ° C and 4.5 mm Hg or below, for example at 0.0075 ° C and 4.5 mm Hg, but other suitable combinations can easily be made by preliminary tests and / or by using vapor pressure values at different temperatures to determine the conditions under which at the selected temperature the vapor pressure of the ice exceeds that of the selected pressure, while the vapor pressure of the solute is lower than the selected pressure and vice versa. If difficulties arise in the selection of suitable conditions, for example if the solute has a triple point similar to water, high yields can be achieved in such a way that the vapors are passed through a column with a water vapor-absorbing material such as silica gel or anhydrous copper sulfate ( that can be regenerated) can be sent while the non-aqueous vapor is being collected.

The term “sublimation” is to be understood as a process in which a solid is converted directly into a vapor. This includes measures in which the clathrate hydrate is decomposed into a hydrate-forming gas and water vapor or ice without passing through a liquid phase.

Another separation method is differential elution using a solvent or using solvents in which the solute is soluble, but in which the solid hydrate of the hydrate fluid used is essentially insoluble at the temperatures at which the hydrate is formed and is stable . In the event that the solute consists of acetic acid, suitable elution solvents are ethanol, formaldehyde and butanol.

A preferred method of differential elution is given when the magma of solid hydrate and solid solute is separated from the liquid component which contains one or more unreacted formers, unreacted aqueous solution and unreacted minor constituents which are present in the solution, that is concentrated. The latter fraction can be distilled to obtain any small constituents that may still be present, such as in the case of vinegar, and any solute that is still present.

Even if the constituents present in smaller quantities also include solutes of the aqueous solution from which water is removed, they are nevertheless referred to below as constituents present in smaller quantities, while for reasons of convenience the solute is characterized as the main constituent or as the main constituents.

The solid phase is then quickly dried by evaporation of the non-separated former, whereupon increasing the vacuum (i.e. decreasing pressure) makes the solid hydrate unstable and breaks down into ice and former. The former is evaporated immediately and can be collected for recycling. This leaves a mixture of ice and solid acetic acid. The ice melts at a temperature below 0 ° C due to a lowering of the freezing point by the solution of the solute. However, if the solute is highly soluble in water at this temperature, it is possible to achieve a marked degree of concentration if the solute is dissolved and the solution is removed before all of the ice melts. The unmelted ice obtained then represents the amount of water

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extracted from the original solution. An alternative method is to treat the mixture of ice and dissolved solid material with a solvent prior to such melting, which requires a quick dissolution of the solute but has little effect on the ice (examples are TCFM or methylene dichloride,

if the solute is acetic acid). The solution is then separated from the ice by filtration, while the solute is obtained by evaporation.

TCFM is a particularly valuable hydrate-forming fluid, especially for use in the case of aqueous acetic acid solutions, because of its non-toxicity, its availability on an industrial scale, its low cost and the ease of handling due to the fact that it is a liquid at ambient temperature -Raturatures and -druckes acts, since this way no expensive pressure storage and no expensive Raktionsge-vessels are required, and due to the fact that this material can form a clathrate hydrate at ambient temperatures if the temperature is reduced to a sufficient extent. However, other hydrate-forming fluids can also be used. Known hydrate-forming fluids, along with their hydrate formulas, are given in Table I, in which M represents one of the individual hydrate-forming molecules in the given section.

Table I

Hydrate formula hydrate generator, M

M. 5.75 H20 A, Kr, N2, 02, H2S, H2Se, C02,

N20, PH3, Ash3, CH3F, CH3CI, CH4, M. 5.75 H20 or S02, CH2F2, C2H2, C2H4, M. 7.66 H20

M. 7.00 H20 Xe, Br2, NF2, CHF3, CF4, CH3Br,

M. 17 H20 C2H3F, CH3CHF2, C2H6,

CH2C12, CHC13, CC14, CH3I, C2H5C1, CH3CF3, CH3CHC12, CHBrF2, CC1F3, CC12F2, CBr2F2, CBrClF2,

CF3I, C3H6, C3Hs, Cyclo C5H10

The selection of the working conditions for the production of the solid hydrate are known. The actual working conditions for a given system are based on the pressure-temperature equilibrium line values for a given predetermined hydrate generator and are for a desired solution concentration. Working temperature and pressure limit using the following formula:

Plto = (P0 / xn) to calculated, where t0 = the preselected working temperature for the formation of the solid hydrate and the concentrated aqueous solution, Pj = minimum absolute pressure of the pressure exerted on the hydrate generator at a temperature t ° to achieve the Desired final concentration of the aqueous solution by the hydrate formation, P0 = absolute pressure of the pressure to be exerted on the hydrate former at a temperature t ° to achieve the formation of solid hydrate with pure water.

(It is believed that water is saturated with the hydrate generator but essentially contains no other solute).

x = mole fraction of water at the desired final concentration of the concentrated aqueous solution, n = number of water molecules which are associated with a molecule of the hydrate generator in the solid gas hydrate.

The values of P0 with the preselected t ° can be obtained from experimental and published values.

Although the formula is usually used to determine the working pressure P! For a preselected temperature t ° and the known pressure P0 of the formation of solid hydrate with pure water and a desired final solution concentration, as represented by a residual molar fraction of water x in the solution, it should be pointed out that in general when two of the process variables, namely Pl5 P and x with a predetermined T ° are known, the third variable can be determined by calculation using the above formula.

When TCFM is used to remove water as acetic acid solutions, essentially complete conversion of the water to form solid hydrate can be achieved in the presence of an excess of TCFM over the stoichiometrically required amount at atmospheric pressure, provided that the temperature is sufficiently low, preferably below 5 ° C, is maintained.

The choice of hydrate-forming fluid depends on various factors, such as safety, cost and availability, but depends primarily on the particular solute to be concentrated and its properties, as well as the method used for the separation of the solute concentrate is selected from the hydrate or vice versa. In general, the hydrate-forming fluid is selected to maximize the simplicity of the separation process, taking into account the other criteria mentioned above. For example, when differential sublimation is used, the hydrate-forming fluid is selected such that a solid hydrate is formed that is sublimed slightly preferentially over the solute. In the case of aqueous acetic acid solutions, where the separation process used is differential sublimation, particularly suitable hydrate-forming fluids are, besides TCFM, dichloromethane, trichloromethane and dichlorofluoromethane.

The amount of hydrate-forming fluid that is used in the initial solid hydrate generation stage of the process according to the invention can vary within wide limits. The amount used is expediently at least an amount which is sufficient to react with all the water in the solution to be concentrated, but an excess of the hydrate former is advantageously used, in particular if vinegar is to be concentrated, since in In this case, the minor components of the vinegar (which contribute to its taste and character) can be conveniently obtained in the excess of unreacted hydrate formers.

When the invention is carried out in practice, the reaction of the hydrate formers, such as TCFM, with water to form solid hydrates is essentially stoichiometric, so that the required amount of hydrate formers can be easily calculated.

If the hydrate generator is TCFM, the amount of TCFM required is at least 1 molecule of TCFM per 17 molecules of water, i.e. at least about 1 part TCFM per 2 parts vinegar by weight. Approximately equal parts of vinegar and TCFM, based on the volume, are expediently used.

The methods according to the invention described above are particularly suitable for the concentration of vinegar. Vinegar is essentially an aqueous acetic acid solution with an acetic acid content of the order of 5 to 10% (weight / volume), depending on the source and the method of production. Such a solution contains small amounts of various other natural products

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ingredients that contribute to the taste of each vinegar.

Special types of vinegar that are worth mentioning are, for example, distilled malt vinegar, alcohol (fermentation) vinegar, cereal vinegar, wine vinegar, apple cider vinegar and flavored vinegars. Malt vinegar usually contains at least 4% (weight / volume) acetic acid in England, while wine vinegar in France and Italy must contain at least 6% and at least 7% (weight / volume) acetic acid.

From the foregoing, it can be seen that vinegar generally contains 90 to 95% (w / v) water. Therefore, in order to drastically reduce the cost of vinegar transportation, it is necessary to concentrate the vinegar considerably. On the other hand, it should be borne in mind that many of the smaller quantities of natural product components of vinegar, which are essential for the taste of vinegar, tend to denature at elevated temperatures and under other harsh conditions.

The object of the invention is therefore to provide a method for concentrating vinegar, the vinegar components of which are not substantially denatured when it is carried out, and in addition there is no appreciable loss of the vinegar components with the exception of water.

According to a particular embodiment of the invention there is therefore provided a process for obtaining a vinegar concentrate by removing water from vinegar, which consists in

a) contacting the vinegar with a hydrate forming fluid at a temperature below the maximum temperature at which the hydrate forming fluid forms a solid hydrate in the presence of the vinegar at a temperature at which the amount of acetic acid in the vinegar affects the solubility of the vinegar in any solution that remains after hydrate formation, forming a magma consisting of solid hydrate, solid acetic acid and any unreacted hydrate generator, any unreacted aqueous vinegar solution and minor vinegar components, and b) 1. the hydrate generator and at least one Part of the aqueous constituents of the solid hydrate and any unconverted hydrate former still present and 2. separate at least part of the vinegar from one another to produce a substantially hydrate-free acetic acid concentrate, the vinegar constituents present in smaller quantities not with the acetic acid E-concentrate are separated, recover the vinegar components present in smaller quantities and combine them with the acetic acid concentrate to produce a vinegar concentrate.

A particularly preferred hydrate-forming fluid that is used to carry out this method consists of trichlorofluoromethane.

Preferably, the solid hydrate is from the concentrated vinegar and any solid acetic acid present, which has been precipitated from the vinegar solution by sublimation or solution of solid hydrate under those temperature and pressure conditions under which such a solid acetic acid which may be present does not substantially evaporate or dissolve and is essentially not denatured.

On the other hand, in some cases the minor components of the vinegar are expediently separated from the solute, for example in solution in the hydrate generator. Once recovered, they can be re-combined with the solute concentrate obtained after the concentration process is complete

(assuming the required final concentration).

It should be noted that if the highest levels of concentration are required, it may be necessary or appropriate to carry out the concentration in more than one step, i.e. by repeating the concentration process one or more times. In the event that minor constituents have been separated from the solute (e.g. in solution in excess hydrate formers), they do not need to be combined again with the concentrated aqueous solution of the solute until the final concentration cycle is complete.

The degree of concentration which can be achieved by the process according to the invention depends on various factors, for example the type of solute and the hydrate former used, the particular separation process and the number of concentration cycles carried out. Concentrations of 40, 60 or even 80% (weight / volume) acetic acid can be selected by selecting suitable conditions in the case of a vinegar concentration while observing the method according to the invention. After reconstitution with water, the concentrated vinegar is essentially indistinguishable from untreated vinegar.

example 1

Concentration of aqueous acetic acid A. Solid hydrate formation. 11 liquid trichlorofluoromethane (TCFM) is added to 11 of a 10% (weight / volume) acetic acid solution, and the mixture is cooled to 3 ° C. It is then stirred vigorously with external and internal cooling (addition of solid carbon dioxide) to ensure that the temperature of the mixture remains below 5 ° C during the hydrate formation step. After a few minutes, you get a magma of unused TCFM, solid acetic acid, remaining aqueous acetic acid and solid hydrate.

B. Separation of the hydrate The magma is subjected to vacuum evaporation (3 mm Hg at 0 ° C.) over a period of 60 minutes until no more hydrate sublimes. The unused TCFM is first removed after this step and then recovered together with the TCFM enclosed in the hydrate. The removal of the TCFM and the subsequent removal of the hydrate require a reduction in the temperature to 0 ° C. This temperature is then maintained by exposure to heat for rapid TCFM removal. This process provides a mixture of solid glacial acetic acid and residual aqueous acetic acid, which at ambient temperatures results in an 82% (weight / volume) aqueous acetic acid solution.

Example 2 Concentration of Malt Vinegar A. Formation of the Solid Hydrate 500 ml of liquid trichlorofluoromethane (TCFM) are added to 500 ml of malt vinegar. The mixture is stirred vigorously for 3 minutes at 3 ° C. Excess TCFM as well as other liquids are then drained from the solid hydrate and acetic acid, which are then divided into two equal parts.

B. Removal of the Hydrate 1. A portion of the solids is subjected to vacuum evaporation (3.4 mm Hg at -0.5 ° C.) until no further TCFM or water is removed. This stage provides an aqueous acetic acid solution containing 69% (w / v) acetic acid.

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2. The other part of the solids is homogenized with a small amount of ice-cold water over a period of 10 minutes in a cold room at -4 ° C. The liquid phase is then filtered off under vacuum. The remaining solids, under ambient conditions, result in an aqueous solution containing 42.5% (weight / volume) acetic acid.

The liquids from the first stages are then, after removal of the TCFM by evaporation, added with acetic acid solutions which are obtained after the hydrate has been separated off. Finally you get concentrated malt vinegar.

Example 3 Concentration of fermentation vinegar A. Formation of the solid hydrate

250 ml of liquid trichlorofluoromethane (TCFM) are added to 250 ml of fermentation vinegar. The mixture is stirred vigorously for 3 minutes at 3 ° C. Excess TCFM and other liquids are then separated from the solid hydrate and acetic acid.

B. Separation of the hydrate

The solids obtained in the first stage are subjected to vacuum evaporation (10 mm Hg at -5 ° C) until no further TCFM is released. The pressure is then reduced to 3 mm Hg and the temperature raised to -1 ° C. First, ethanol and acetaldehyde are removed and collected. Evaporation continues until no more water can be removed. This process yields a residue which, at ambient temperature, gives an aqueous solution containing 68% (w / v) acetic acid.

The recovered ethanol and acetaldehyde as well as the liquids from the first stage after the evaporation of TCFM are then added to the aqueous acetic acid solution. Ultimately, concentrated fermentation vinegar is obtained.

Example 4 Concentration of fermentation vinegar Formation of the solid hydrate a) 50 ml fermentation vinegar are added to 50 ml TCFM. The mixture is heated to 0 ° C. and stirred with an air jet until virtually the entire aqueous phase has reacted. The excess TCFM is then run off and stored for recovery of dissolved materials. The solid magma is similarly stored at 0 ° C until it is needed for evaporation and sublimation.

b) A second method of clathrate hydrate formation is used:

75 ml of TCFM are added dropwise to 100 ml of fermentation vinegar at a temperature of 0 ° C. over a period of 6 hours. The temperature is kept at 0 ° C. It is stirred by means of an air jet. After 6 hours, excess TCFM and dissolved constituents are filtered off from the solid magma constituents and stored until they are required for the recovery of solutes. The solid magma is stored at 0 ° C until it is needed for evaporation and sublimation.

Separation of the hydrate

The solid magmas from the hydrate formations a) and b) are placed in a freeze dryer, whereupon a vacuum is applied. The excess former is first removed. Then the vacuum is increased until the citrate hydrate decomposes and the former is released. The temperature is kept below 0 ° C by infrared radiation. When the hydrate decomposes, ice and gaseous TCFM are formed. The TCFM is condensed for later reuse. After a substantial part of the former has been removed, the thin magma layer consists of ice crystals and solid acetic acid. The pressure is then reduced to sublimate the ice (3 mm Hg at 0 ° C). This leaves a considerable part of the acetic acid, which is allowed to come to room temperature at normal atmospheric pressure.

The excess TCFM from the clathrate formation stage io is carefully distilled at 20 ° C. until all traces of TCFM have been removed, as can be determined by examining the product by gas liquid chromatography. The hydrate formation method b) provides higher yields of dissolved acetic acid than the method a). After combining the 15 distillates and the sublimed samples, the former method gives a concentrate with 84% (weight / volume) glacial acetic acid, while the latter gives a concentration of 89%.

Example 5

20 A 100 ml aliquot of malt vinegar is reacted with 100 ml TCFM as in Example 4. The excess of TCFM, which contains the minor amounts of malt vinegar, is drained from the solid magma. The dissolved acetic acid and the constituents present in smaller quantities are obtained by distillation at 20 ° C. until TCFM is no longer determined by an analysis of the residue by gas-liquid chromatography.

The solid magma is then subjected to vacuum distillation under 30 mild conditions until the excess TCFM is removed. The vacuum is then increased until the hydrate has decomposed. Solid acetic acid and ice remain. At -1 ° C you notice that some ice melts. In addition, 1 ml of ice-cold water is added. The slurry is stirred briefly, after which the liquid is removed by vacuum filtration.

This liquid consists of concentrated acetic acid. When combined again with the dissolved components from the excess TCFM, concentrated vinegar is obtained. 40 The degree of concentration of the acetic acid and the aqueous solution depends on the amount of ice that has melted into the liquid that may have run off the slurry. After adding the acetic acid dissolved in TCFM and the components present in smaller quantities, the acetic acid content of the samples is 54% (weight / volume).

Example 6

The hydrate formation is carried out as in Example 4a). The solid magma is then subjected to an initially low vacuum to remove excess TCFM. Then the hydrate is quickly destroyed to produce ice and solid acetic acid. An equal volume of TCFM at 1 ° C is added to the mixture of ice and acetic acid at a recorded temperature of 55 -4 ° C, after which the mixture is stirred. The TCFM is then removed from the ice by filtration. The liquid is evaporated at 20 ° C until no further TCFM is found. After re-combining 60 with the minor amounts of components obtained from the distilled TCFM, this method provides an acetic acid content of 89% (weight / volume).

An analysis of the reconstituted concentrated vinegar products by gas liquid chromatography shows that the 65 concentrated product largely resembles the original vinegar. The compounds acetaldehyde and ethanol found in the vinegar are determined individually. The rest of the volatile components are determined in groups.

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The quantitative determinations are obtained on the basis of the gas liquid, which is determined by the method according to the example of chromatogram peak areas. 6 have been obtained, however, the procedure in one. In the table below are the acetic acid content (%, small scale using 10 ml of vinegar samples by weight / volume) and the percentages (based on the result. The error that occurred in the determination the 5 smaller amounts of ingredients present in the weight) of the ingredients present in smaller quantities, which is made using 5 vinegar concentrates, is of the order of magnitude of ± 7 to 8%.

Vinegar type Acetic acid% acetaldehyde% ethanol% other volatile concentration

%, Weight / volume * components

Fermentation vinegar 67 94 89 93

Wine vinegar 71 64 76 77

Wine vinegar (white wine) 61 81 73 82

Meager 82 92 98 102

Apple cider vinegar 58 84 86 91

* The acetic acid concentrations are determined by an acid-base titration and also reflect any smaller acidic components that may be present and which may be present in the concentrated vinegar.

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Claims (27)

624 854 2nd PATENT CLAIMS 1. A method of removing water from an aqueous solution by contacting an aqueous solution with a hydrate-forming fluid at a temperature below the maximum temperature at which the hydrate-forming fluid forms a solid hydrate in the presence of the solution and at a temperature at which exceeds the amount of dissolved material present in the original aqueous solution, the solubility of the dissolved material in any solution remaining after hydrate formation, forming a magma of solid hydrate, solid dissolved material, such as any unreacted hydrate former still present, and so forth unconverted aqueous solution still present, and mutual separation 1) the hydrate former and at least part of the aqueous constituents of the solid hydrate and 2) at least part of the dissolved material to produce a substantially hydrate-free product and any residual water still present, characterized in that the separation is carried out by fractional sublimation and / or evaporation and / or elution. 2. The method according to claim 1, characterized in that the aqueous solution contains acetic acid as the dissolved material and said separation is carried out by a method which comprises fractional elution. 3. The method according to claim 1 or 2, characterized in that the solid hydrate is decomposed before the separation by increasing the temperature and / or by reducing the pressure to produce temperature and pressure conditions at which the solid hydrate decomposes, and at which the dissolved material is essentially not influenced. 4. The method according to claim 3, characterized in that the decomposition is carried out under those temperature and pressure conditions under which the dissolved material remains substantially. 5. The method according to any one of claims 1 to 4, characterized in that the dissolved material and at least part of the ice are separated from one another by fractional sublimation under temperature and pressure conditions which are such that the ice is volatilized while the dissolved material remains essentially in the liquid and / or solid phase. 6. The method according to any one of claims 1 to 4, characterized in that the dissolved material and at least part of the ice are separated from one another by sublimation under such temperature and pressure conditions that both the ice and the dissolved material are volatilized, whereupon a Contact is made with a water vapor absorbing material. 7. The method according to claim 2, characterized in that the dissolved material is separated from the solid hydrate by differential elution using a solvent in which the dissolved material is substantially more soluble than the solid hydrate. 8. The method according to claim 7, characterized in that the eluting solvent used consists of ethanol, formaldehyde, butanol, trichlorofluoromethane or methylene dichloride. 9. The method according to claim 3 or 4, characterized in that at least part of the ice is kept in the solid state and the dissolved material is mechanically separated from the ice in the solid state in the form of a concentrated aqueous solution. 10. The method according to claim 9, characterized in that a part of the ice can be melted in liquid water, in which dissolved material dissolves to form a concentrated aqueous solution of the dissolved material. 11. The method according to claim 9 or 10, characterized in that liquid water is added and the dissolved material is allowed to dissolve in the added water to form a concentrated aqueous solution of the dissolved material. 12. The method according to any one of claims 9 to 11, characterized in that the concentrated aqueous solution is separated from the solid ice by filtration. 13. The method according to claim 3 or 4, characterized in that at least part of the ice is kept in a solid state and a non-aqueous solvent in which the ice is considerably less soluble than the dissolved material is added to form a solution of the dissolved material , this solution is then mechanically separated from the solid ice and the dissolved material is then obtained from the solution by separation from the eluting solvent. 14. The method according to claim 13, characterized in that the dissolved material consists of acetic acid and the non-aqueous solvent used consists of trichlorofluoromethane or methylene dichloride, the acetic acid being obtained by evaporation of the non-aqueous solvent. 15. The method according to any one of claims 1 to 14, characterized in that the hydrate former used consists of dichloromethane, trichloromethane or dichlorofluoromethane. 16. The method according to any one of claims 1 to 14, characterized in that the hydrate former used consists of trichlorofluoromethane. 17. The method according to any one of claims 1 to 16, wherein an excess of hydrate former compared to the amount required for reaction with all the water in the aqueous solution is used, characterized in that the liquid phase after the solid hydrate formation remains and contains the excess of unreacted former, filtered off from the solid phase and then evaporated to obtain any small constituents of the concentrated solution which are still present and which remain in the liquid phase during the solid hydrate formation, the constituents present in smaller quantities being present the concentrated aqueous solution of the dissolved material are combined again. 18. The method according to any one of claims 1 to 17, characterized in that the aqueous solution from which water is removed consists of vinegar. 19. The method according to claim 18, in the implementation of which hydrate generator consists of trichlorofluoromethane, characterized in that the hydrate decomposition is carried out at a temperature of not more than 0 ° C. and a pressure of not more than approximately 750 mm Hg, the hydrate decomposing and the trichlorofluoromethane is volatilized while the solid acetic acid is maintained in a substantially solid form. 20. The method according to claim 19, characterized in that the hydrate decomposition is carried out at such a temperature and under such a pressure that the hydrate decomposes to ice and hydrate formers, and that the ice is then fractionated by reducing the pressure to a value of not more than 4.5 mm Hg is sublimed if a temperature of approximately 0 ° C is maintained. 21. The method according to claim 20, characterized in that the ice sublimation at about 3 mm Hg and about 0 ° C is carried out. 22. The method according to claim 18, for the production of a vinegar concentrate by removing water from vinegar, characterized in that 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 3rd 624 854 a) after the formation of a magma of solid hydrate, solid acetic acid and / or solid acetic acid solution, any unreacted hydrate generator still present, any unreacted aqueous vinegar solution and minor vinegar components b) 1. the hydrate generator and at least some of the aqueous components of the solid hydrate and any remaining unreacted hydrate formers and 2. at least part of the acetic acid are separated from one another and, if the vinegar components are not separated off with the acetic acid concentrate, these minor vinegar components are recovered and combined with the acetic acid concentrate. 23. The method according to claim 22, characterized in that the hydrate former used consists of trichlorofluoromethane. 24. The method according to claim 22 or 23, characterized in that the vinegar is concentrated to achieve a final concentration of acetic acid of at least 40% (weight / volume). 25. The method according to claim 24, characterized in that the final concentration is set to at least 60% (weight / volume). 26. The method according to claim 25, characterized in that the final concentration is set to at least 80% (weight / volume). 27. The method according to any one of claims 1 to 26, characterized in that the water removal process is carried out at least twice using the aqueous solution from which water is to be removed.