DE1005672B - Process and device for distilling technical glycerins - Google Patents

Description

GERMAN

The subject of the invention is an improvement of the process of distilling technical glycerins for the purpose of making savings as a whole the processes resulting in the distillation product.

The glycerol is known (° / ₀ Glycerin 3 to 20) obtained in the fat industry in the form of aqueous impure and dilute solutions. These solutions are concentrated by the manufacturers to a content of 80 or 88% (there are two types of technical raw glycerine). These highly concentrated technical glycerines, which contain ash and organic foreign bodies, therefore have no more than a few percent water.

The manufacturers of pure glycerine distill these technical glycerines to obtain pure glycerine. These Distillation not only requires indirect heating with steam but also the introduction of direct superheated Noticeable amounts of water vapor in order to avoid decomposition of the glycerine. The decomposition occurs under atmospheric pressure at 290 °, but starts already at 200 °. In the usual procedure, the Manufacturers of raw glycerine use a lot of heat in order to evaporate the water contained in the diluted glycerine, and the manufacturer of pure glycerine uses a lot of heat to generate the injection vapor.

This drawback is overcome by the invention.

The method according to the invention consists in that one glycerine-containing waters, the glycerine content below that of the usual concentrated crude glycerols of the trade, evaporated by without fractionation they are allowed to enter a vessel at sufficient speed, in which they are instantly concentrated appropriate evaporation temperatures and pressures are subjected, and that the glycerine is then separated from the vapor by fractional condensation.

According to the invention, therefore, the diluted technical glycerins with a medium water content are immediately obtained subjected to distillation to thereby use the water contained in these solutions as a source of water vapor to be able to use. This means that the heat only needs to be used once.

The mixtures of water and glycerine boil at lower temperatures than pure glycerine and so on lower, the greater the water content and the lower the pressure.

According to the invention, therefore, an aqueous dilute glycerol solution, such as is obtained as a by-product in industry, which may optionally be preheated, is introduced into a heated vessel and under vacuum in a continuous and semi-continuous manner. This solution is vaporized immediately upon contact, be it with the hot walls of the apparatus or with a bath of preheated glycerine, the temperature and pressure in the vessel being selected to suit the process and the apparatus
for distilling technical glycerine

Applicant:

Societe Anonyme: Savonnerie

et Manufacture de Produits Chimiques

de Port-ä-ΓAnglais Etablissements

Breton & Steinbach, Vitry-sur-Seine

(France)

Representative: Dr.-Ing. A. van der Werth,
Patent attorney, Hamburg-Harburg 1, Wilstorfer Str. 32

Claimed priority:
France from March 19, 1954

Jean-Jaques Vosganiantz, Villiers-sur-Marne

(France),
has been named as the inventor

to meet the conditions of evaporation of the mixture of water and glycerin in question. The vapor mixture distilling under these conditions has the same composition as that which is fed in Solution and is subjected to a fractional condensation in a known manner, which separates of pure glycerine allowed in the first place.

The essential feature of the invention is thus the distillation of aqueous glycerol solutions without any Injection of water vapor. This new process is remarkably economical because it has the Steam superheaters and even in the case of so-called cleavage glycerols, which are less mineral salts are contaminated than the lower lye glycerine, also the pre-concentrating of the glycerine is spared.

The invention also extends to technical systems for carrying out the method.

The special features and advantages of the invention are described in more detail with reference to the drawing.
Fig. 1 is a number table.

Figure 2 is a diagram made from this table.

3, 4 and 5 are schematic representations of three technical systems for carrying out the method.

According to the invention, a glycerol-containing liquid is therefore subjected to immediate distillation under reduced pressure, their water content is still relatively high

609 867/405

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is. To do this, the following conditions must be met maintaining the product at an agreed temperature

be: ■■ -..-... was brought, is in a vacuum vessel against

1. The liquid containing glycerine has to be injected into the distillation wall, which serves as a heat exchanger Conditions (high temperature and deep negative pressure) and the liquid evaporates almost instantly. the suddenly and not gradually, because 5 technical execution of such a process requires otherwise a simple concentration by evaporation of the naturally resistant scraping or cleaning of the for Water content takes place. Heat exchange wall.

2. Because of the instantaneous process, this must be preferred Continuous or semicontinuous way to carry out the process are described below are executed. io hand of the drawings described in more detail.

Theoretically, the technical design in the system shown in Fig. 3, which is the one presented under 2

be carried out in the manner described below: corresponds to the type of execution of the procedure described,

1. According to one already used for other purposes under which is used to treat a glycerin-containing liquid, The term flash distillation is known, which consists of diluted cleavage glycerine and one th process is the possibly preheated glyce- 15 low content of ash and organic components Suddenly containing liquid in a vacuum vessel.

relaxed at a temperature that is equal to or greater than the system consists of a distillation vessel 1, the

than the distillation temperature. The atomized liquid is provided with a drain cock 2 at the bottom. The heating up

is immediately volatilized. The glycerin and is carried out by a steam coil in the lower part and

Water vapors are fed to condensers. The return 20 alternatively by a double jacket for the flow

stand settles itself in the expansion vessel. from steam or a hot liquid.

This, at first glance, appears to be advantageous. The cylindrical vessel is removed from the outside by a solution but the task is practically impossible to carry out, whatever means (steam coil or heating mantle) can be used in this way the liquid would have to be preheated too high. warms that no steam condensation can take place.

2. The glycerin-containing liquid, which was previously on the 25 The vapor discharge pipe extending from above 3 has a highest with the technical possibilities and the good as short as possible length and is careful against heat retention of the product is protected against the agreed loss of value. A separator 4 of any type holds warmed up, is violently in a vacuum vessel or in the entrained components and conducts them into the injected a bath that serves as a heat exchanger, vessel back. The distillation vessel is with a shovel. B. on or in a mercury bath, the temperature of which is 30 glass 5 and a level indicator 6 provided. The feed is equal to or higher than the distillation temperature. This can through a pipeline and a valve 7 for large theoretically possible solution but has a large after-flow rate or through a pipeline and a part: The remaining impurities (organic contamination) Injection nozzle 8 of any kind.

cleaning agents and mineral salts), which reduce the distillation pressure

stand up, the heating bath were quickly dirty, 35 made, and the floor is covered with glycerin

so that this would have to be cleaned frequently. A technical liquid up to the complete covering of the heating

cal underlye glycerine filled with snake glycerine. The heating steam is then gradually

from 40 to 50% contains, for example, 12 to 15% mineral, and the liquid is left in the usual way

salts. This solution is then evaporated practically perfectly. While maintaining the liquid level

possible if the heating bath is made of glycerine, which is from 40, the temperature becomes gradually with the increasing

originates from the product to be treated and is increased by deconcentration until it reaches the distillation value of the

stillation is recovered at the end of the process. Liquid reached at the pressure prevailing in the vessel

The table in Fig. 1 shows, for example, that or exceeds, for example at 60 mm Hg (Dia-

at the temperature of 170 ° and with the absolute undergram of Fig. 2):

pressure of 60 mm Hg the nature of the vapors the 45 ^ _{0 c för} ^ _{liquid with 10 0 /} glycerine

Sf ^{^:, 3} ^, 'IJ ^o> - ^ ^{ater' / o-,} and ¹⁴³ ° C for a liquid with 20% glycerol

- If the glycerine-containing liquid is such a ^ 90 η _{ffir dne liquid with 40} η glycerine

Content supplied before the vessel is _{ready to carry out the 166} o _{c for a liquid with 50} o / glycerin process, for example a much lower one

Temperature, a non-distilled 50 through the injection nozzle 8 is then the to be distilled

Tem Glycerin existing residue, the volume of rende liquid continuously let in and the amount through

can be set by the operator. The evaporation capacity of the system is set differently. In the

In other words, the distillation vessel works as one touch with the glycerine bath it is instantly evaporated,

fan evaporator. The feed is switched off, If the temperature and feed conditions are

as soon as the glycerine residue is considered sufficient, the vapor evolved is the same

is, and then switched on again as soon as the tempera composition as the supplied liquid. at

door and the pressure reach the appropriate value, d. H. a given negative pressure, too high a temperature

if they match the evaporation conditions of the liquid, the partial distillation of the glycerine bath and the

correspond, which cause lowering of the liquid level at 170 ° and a negative pressure. Too low one

Set 60 mm Hg. Under such conditions, the temperature remains 60, on the other hand, an increase in the liquid

the glycerine residue in the distillation vessel results in constant keitsvolumens. By precisely setting the

and serves as a heat exchange medium. According to the distillation-distillation ratio, which is created automatically

When the whole filling is poured back into the vessel, this glycerine, which is used as a heating bath, is

the remaining residue was kept constant even by blowing in the required amount. The temperature to be maintained

borrowed amount of water or steam distilled or better, but 65 must be higher than the theoretical temperature

to avoid unnecessary waste because of the low backflow from the separator 4. The

Heat, by injecting a suitable amount of water supply through the injection pipe 8, can with an appropriate

with low glycerine content. warmed liquid take place under a

3. The glycerin-containing liquid previously applied to the pressure that is equal to, higher or lower than the pressure

highest with the technical possibilities and the good 7 ° of the outside air. If the injection tube is completely in the heating bath,

5 6

the pipe can reach the barometer height under the shape of coils of a salty mud, that is

go through a more or less long way. The liquid 6 to 7 m taking into account the sludge density,

The first stage of the distillation process can also be used in one of the glycerol condensers

System must be preheated. For a liquid with 30% substantial proportion of the glycerine in the salty

Glycerin, for example, has the heat of vaporization 5 sludge, which reduces the volume of the set.

about 200 WE and the mean specific heat that is reduced. This continues until the salty

Liquid 0.85 WE. The condensation of the glycerine sludge reaches the centrifuge 10. In this first stage

then allows the liquid to be supplied to be heated - it is therefore essential to adjust the temperature of the system

ability to keep 70 ° C below normal working temperature,

As soon as the process is completed or as soon as the io thus the vapors formed have a glycerin content.

Glycerine bath after excessive contamination by organisms, which is lower than that of the supplied ones

niche substances and (or) ashes to continue the work liquid, the excess compensating for the losses,

becomes unsuitable, the feed is switched off and the system according to Fig. 5 is used to carry out the un-

This glycerine bath is stimulated by injecting water, as described in the 3 example. The sudden increase in

Steam or better, to avoid unnecessary temperature of the glycerin-containing substances introduced into the vessel

Waste of heat by injecting a liquid is done by spraying it on a hot wall,

thin water containing glycerine. Under these conditions, this plant also permits the treatment of dilute substances

nits, the glycerine is made almost entirely from the still solutions of sub-lye glycerine with a high content of

eliminated. For this last part of the process or some mineral residue. The cylindrical vessel 1

Before doing this, it is advisable to heat the stand slightly above the surface by circulating the liquid. To the

borrowed stand to let rise so that the heating coil lower end is a trigger valve 2 of large passage

always completely submerged. The distillation residues connected cross-section. From the top comes in

are drawn off through the valve 2 of large diameter exhaust pipe 3 for the distillation vapors, which is connected to a

calmly. Separator 4 is connected. One or more show

The system according to FIG. 4, which is used for the execution of the un- 25 glass 5, one of which is located in the lower cone of the

ter 2 described example is intended to be located to the con-vessel, allow observation of the correct

serve centering of diluted underlye glycerine. Course of the process. A helical scraper

It is especially important for the elimination of the essential 12 and keeps the evaporation surface always in a sufficiently clean

Mineral residues are formed, resulting from the distillery rem condition. The shaft of the scraper is hollow and serves

tion of these glycerols result. It goes without saying that it can be used as a feed pipe for one or more spray nozzles 13.

also serve to distill the cleavage glycerols. The basic idea of the process is that

Parts 1, 2,3,4,5, 6,7,8 are the same as for the vessel on the temperature and pressure of the evaporation system according to FIG. 3, however, a further sight glass 5 'is to be brought to the function of the supplied liquid. Preferably lower end of the conical bottom of the distillation it would of course be the vessel wall to a temperature vessel, a device 9 for removing the sludge, 35 bring, in which the glycerine and the water of the cereal Centrifugal device or separator 10 and a dusty liquid would be instantly volatilized, wherein Liquid pump 11 is provided. so only the one from organic and mineral constituents

The start-up is carried out as in the case of the system by dividing composite residue on the wall

Fig. 3. Immediately at the beginning of the operation, but would stay in. However, experience has shown that the

lower cone of the vessel from a salty sludge, 4 ° complete evaporation of the glycerine in a single

which can be observed through the sight glass 5 'in the last stages large amounts of organic

can. The level of this sludge will pass over by removing niche components that affect the quality of the

held at the height of this sight glass, whereby equally distilled glycerine has a harmful effect,

The liquid level can be adjusted in time by an appropriate addition. A dry residue would also be removed

The glycerine-containing liquid is kept constant 45 to maintain the negative pressure in the vessel

will. As soon as the glycerine bath has a sufficient concentration, great difficulties arise. It will therefore only be one

tration, the temperature is gradually aimed at until the glycerol has partially evaporated, and the

sludge containing salt is continuously scraped off into

increases. The continuation of the process takes place as in the direction of the trigger valve 2 displaced and arrives in

the system according to FIG. 3, but the salty 50 is a take-off device 9, a centrifuge 10 and a

Sludge during the entire operation by the pump 11, which is in the same way as with the system after

Device 9 withdrawn and pressed into the centrifuge 10, Fig. 4 shows the conveyance, washing out and reinsertion

where they are ejected and, through the added glycerine, cause the recovered glycerine,

containing liquid is washed out by itself. In this case, the following are special features

Recovered salt contains only small amounts of glycerine and 55 to be emphasized: As the heating surface to eliminate the

can still be used. The supplied liquid, mineral residue scraped off continuously

which must be prepared with the salt obtained by washing, it is imperative that a simple geometrical

is rich, goes into the spray tube 8 by simply looking at the shape obtained in the present example

suction or is lifted by the pump 11. Under is cylindrical, but it can also be conical or a

In such circumstances, of course, the shape suitable for scraping off is obtained by selecting

see obtained glycerin and, accordingly, the sentence could. In all cases the heat exchange surface is

enriched in the cone with soluble impurities, relatively small compared to the volume of the vessel

especially with organic ingredients. As soon as the vessel. All other things being equal, in particular

Bath becomes unsuitable for further use, proceeds with the same volume, the performance of the system is after

one as in the system according to FIG. 3 by flushing 65 FIG. 5 less than that of the system according to FIG

with water, steam or a diluted glycerine content - a powerful heating coil is provided.

for water. The glycerol content of the liquid to be distilled is

There are some peculiarities of this system and it depends only on economic reasons. Does it

To highlight the way of working. The device for separating to cleavage glycerol can be used with any

draw 9 can of course be omitted if the downpipe of the 70 salary is working. The procedure then allows the de-

instilling a liquid with 10% glycerine at 130 ° C, at a negative pressure of 60 mm Hg, which would be impossible with known methods because the use of 9 parts of injection steam for 1 part of glycerine is an unacceptable expenditure.

For under-lye glycerins, it is better to reduce the liquid to a level of about 40% in order to remove most of the dissolved mineral salts.

The uppermost limit of the content of glycerin is DieJ give few of the commercially available raw cleavage Glycerine at 88% and the lye Glycerine with 80 ° / _0, however, such a high concentration is due to previous no economic advantage.

The above-described systems must of course for technical operation through stages for fractional condensation be added, which are used to recover the glycerine. The known arrangement of these Steps are not part of the invention and are therefore neither described nor illustrated.

Claims (7)

Patent claims: 1. A method for obtaining glycerine from technical glycerine-containing waters, characterized in that that one glycerine-containing waters, their glycerine content is below that of the usual concentrated raw glycerols on the market, without fractionation evaporates by letting it enter a vessel at sufficient speed, where they instantly have evaporation temperatures and pressures corresponding to their concentration are subjected, and that the glycerol is then separated from the vapor by fractional condensation will. 2. The method according to claim 1 for Unterlaugenglycerin, characterized in that when using of Unterlaugenglycerin this pre-concentrated to a content of about 40%. 3. The method according to claim 1, characterized in that the instant evaporation of the glycerol-containing Water in the evaporation vessel by introducing it into a hot liquid bath or by atomizing done against a hot wall. 4. The method according to claims 1 and 3, characterized in that the hot bath of anhydrous, there is glycerine obtained in a first process stage. 5. The method according to claims 1, 3 and 4, characterized in that the to be evaporated Glycerine-containing water is introduced into the evaporation vessel through a coil in the heating bath will. 6. Device for performing the method according to claims 1 and 5, consisting of one heated cylinder, a rotatably mounted shaft with radially arranged nozzles for atomizing the glycerin-containing water on the walls of the cylinder, a scraper arranged on the shaft to scrape off the walls and an extraction device located at the lower part of the vessel for the scraped off Mud. 7. Apparatus according to claim 6, characterized in that the continuously operating device from an exhaust pump connected to the lower end of the vessel, a centrifuge and one another pump for reintroducing the glycerine-containing liquid into the distillation vessel. Considered publications:
French Patent No. 822,840;
Schlenker, The Glycerin. 1932, p. 113ff. For this purpose 2 sheets of drawings © 609 867/405 3.57