EP0208014A1 - Process and plant for deodorizing and/or deacidifying relatively small intermittent volumes of high boiling liquids - Google Patents

Abstract

The deodorization and / or deacidification of relatively small, changing batches of high-boiling liquids, namely fatty acids, edible oils, fats, glycerides and other high-boiling esters, is carried out continuously in a single- or multi-stage falling film column (20), through the trickle channels (23) of which propellant steam is passed in countercurrent becomes. A plug flow of the liquid is maintained in the feed line (15, 15 ', 15 ", 15 ‴) leading to the falling film column and in the outlet line (30, 30', 30", 30 ‴) leading away from the sump (26) of the falling film column . When changing batches, the new liquid to be treated is introduced into the feed line immediately after the liquid from the previous batch, without any idle batch. The application of the liquid to the distributor (22) in the head (21) of the falling film column is interrupted for a short period of time after the front face of the liquid of the new batch has reached a shut-off valve (16) arranged adjacent to this distributor.

Description

Description:

The invention relates to the deodorization and / or deacidification of relatively small, changing batches of high-boiling liquids, namely fatty acids, edible oils, fats, glycerides and other high-boiling esters. To this end, the invention provides a new method and a new system for carrying out the method.

Without being restricted thereby, the invention is explained below in particular with reference to the deodorization and / or deacidification of relatively small, changing batches of edible oils. However, it will be apparent to those skilled in the art that the invention can equally be applied to the deodorization and / or deacidification of relatively small, changing batches of the other high-boiling liquids and brings the same or similar advantages there.

The usual systems for deodorization and / or deacidification of relatively small, changing batches of cooking oils are mostly designed for a throughput of about 2 to 3 tons of crude oil per hour. In practice, a "relatively small" batch of cooking oil comprises an amount of about 10 to 50 tons. In most edible oil refineries, it is necessary for operational and economic reasons to switch to different oil qualities several times a day. In the majority of cases, both the starting oils and the finished oils differ in their key figures, e.g. Iodine number, glyceride composition, titer, etc. so strong that a noticeable mixing of the successive batches is not permitted when changing from one oil quality to another.

So far, the deodorization and / or deacidification of relatively small, changing batches of edible oils has mostly been carried out in semi-continuously operated systems with a plurality of exchanger stages arranged one above the other. Typically, the edible oil heated to 240 to 270 ° C is treated with stripping steam under various working time containers under a working pressure of less than 10 mbar. The dwell time in each stage is typically 20 to 60 minutes. In order to avoid mixing of the successive types of oil when operating such systems when changing batches, intermediate empty batches are provided. With an average duration of stay of the oil particles of a batch of about 80 to 220 minutes for going through, for example, five stages arranged one above the other, to be passed through in succession, such an empty batch causes a throughput loss which corresponds to the oil throughput to be achieved in 30 to 40 minutes. If, for example, the product is changed three times a day, the throughput losses attributable to the empty batches add up to a few tons of crude oil; in a system with a capacity of 3 tons, these throughput losses due to the batch change can add up to values of 10% and more of the total throughput. The invention is based on a process for deodorization and / or deacidification of relatively small, changing batches of high-boiling liquids, namely pet acids, edible oils, fats, glycerides and other high-boiling esters, the liquid being heated to 180 to 280 ° C. under an operating pressure of less than 10 mbar is treated with motive steam.

Proceeding from a method of this type, the object of the invention is to avoid any noteworthy mixing of the respective liquids when changing batches and nevertheless to reduce the throughput losses considerably compared to the conventional method of operation. Furthermore, a system for implementing this improved method is to be provided.

The solution to this problem according to the invention is a method with the measures specified in claim 1 and / or a system with the features specified in claim 11. Advantageous refinements and developments of the invention result from the subclaims.

• durch diese Rieselkanäle geführt wird; in der auf die Fallfilmkolonne zuführenden Zuführleitung und in der aus dem Sumpf der Fallfilmkolonne wegführenden Ablaufleitung eine Pfropfenströmung der Flüsssigkeit eingehalten wird;
• bei einem Chargenwechsel im Regelfalle die neue, zu behandelnde Flüssigkeit - ohne jegliche Leerlaufcharge - unmittelbar an die Flüssigkeit der vorausgegangenen Charge anschließend, in die Zuführleitung eingeführt wird; und die Aufgabe der Flüssigkeit auf den Verteiler im Kopf der Fallfilmkolonne für eine kurze Zeitspanne unterbrochen wird, nachdem die Stirnfront der Flüssigkeit der neuen Charge ein benachbart zu diesem Verteiler angeordnetes Absperrventil erreicht hat.

In particular, the development according to the invention of the above-mentioned method consists in that the motive steam treatment is carried out continuously in a single- or multi-stage falling film column, the trickle channel walls of which are kept at a higher temperature than the liquid film coming down and motive steam in countercurrent

• is led through these trickle channels; a plug flow of the liquid is maintained in the feed line leading to the falling film column and in the discharge line leading away from the bottom of the falling film column;
• in the event of a batch change, the new liquid to be treated is introduced into the feed line immediately after the liquid of the previous batch, without any idle batch; and the task of the liquid on the distributor in the head of the Falling film column is interrupted for a short period of time after the front of the liquid of the new batch has reached a shut-off valve arranged adjacent to this distributor.

• - eine ein- oder mehrstufige Fallfilmkolonne;
• - eine Zuführleitung, die von einer Anzahl Flüssigkeits-Zulauftanks zu einem Verteiler im Kopf der Fallfilmkolonne führt;
• - eine Ablaufleitung, die vom Sumpf der Fallfilmkolonne zu einer Anzahl Produkt-Tanks führt;

wobei die Zuführleitung und die Ablaufleitung - in Abhängigkeit von der Kapazität der Fallfilmkolonne - einen solchen Durchmesser hat, daß die Flüssigkeit in diesen Leitungen mit einer Pfropfenströmung strömt; und in die Zuführleitung benachbart zum Verteiler im Kopf der Fallfilmkolonne ein Absperrventil eingesetzt ist.The system according to the invention for carrying out the new method provides at least the following parts of the apparatus:

• - a single or multi-stage falling film column;
• a feed line leading from a number of liquid feed tanks to a distributor in the top of the falling film column;
• - A drain line leading from the bottom of the falling film column to a number of product tanks;

the feed line and the outlet line - depending on the capacity of the falling film column - have a diameter such that the liquid in these lines flows with a plug flow; and a shut-off valve is inserted in the feed line adjacent to the distributor in the head of the falling film column.

The explanations below relate specifically to the deodorization and / or deacidification of palm oil, but the basic experience can also be applied to the treatment of other triglycerides and other high-boiling liquids. In addition to the fatty acid triglycerides, palm oil and other vegetable oils contain a proportion of low boilers in the order of about 5% by weight. The majority of the low boilers consist of free fatty acids and a large number of other constituents, such as water, pigments, stabilizers, odor and / or taste-forming compounds and the like. In the course of physical deacidification, in particular the lower fatty acids causing the unpleasant smell and other odor-forming compounds, some of which are formed by autoxidation, must be removed. Deodorization alone is considered if the 01 already has been chemically deacidified beforehand. With hydrogenated fats such as fish oils, deodorization and / or deacidification also serves to remove the unpleasant smell of hydrogenation. In the course of the high-temperature steam treatment, these low boilers and the high-temperature-related degradation products such as hydrocarbons, methyl ketones, aldehydes and the like accumulate in the vapor stream and are removed with it. In the above-described, for the deodorization and / or deacidification of relatively small, changing batches of cooking oils, semi-continuously operated plants can at a temperature of about 240 to 270 ° C under a working pressure of about 3 to 6 mbar with a motive steam amount of 1.5 to 4% by weight of the palm oil throughput, the content of light boilers in the treated oil can be reduced to less than 0.03% by weight.

Insofar as there is no restriction to relatively small, changing batches, it has already been proposed that the deodorization and / or deacidification of edible oils under the conditions of continuous countercurrent propellant steam falling film distillation in an externally forced temperature field in a single-stage falling film column (cf. DE- OS 29 14 101) or in a multi-stage falling film column (cf. DE-PS 32 27 669). With reference to DE-PS 32 27 669, the content thereof - insofar as it is helpful and expedient to explain the present invention - should also be made part of the present documents.

Under the known conditions of continuous countercurrent propellant steam falling film distillation, the liquid heated to 220 to 280 ° C. typically flows down under a working pressure between 2 and 10 mbar as a thin layer with a layer thickness of less than 1.0 mm on the wall from vertically arranged surfaces forming trickle channels , at least some of which are kept at a higher temperature than the flowing liquid, and in counter Water vapor is conducted through these trickle channels. If a multi-stage falling film column is provided, larger hydraulic trickle channel diameters are preferably provided for the trickle channels in the upstream starting zone than for the trickle channels in the closing zone. Due to the resulting flow conditions and viscosities of the trickling liquid, the residence time of individual liquid particles in such a single- or multi-stage falling film column is less than 20 seconds. Nevertheless, a satisfactory deodorization and / or deacidification up to low boiler contents of less than 0.03 wt. -% of the finished oil reached.

The falling film columns which have become known for the deodorization and / or deacidification of edible oils are mostly designed for considerable throughputs. According to the examples of DE-PS 32 27 669, the initial stage of such a falling film column consists of 60 tubes (length 4 m) with an inner diameter of 84 mm and is designed for a throughput of 10 tons of palm oil per hour. Although such a falling film column does not at first glance lend itself to deodorization and / or deacidification of relatively small, changing batches of edible oils, it has been found in the context of the present invention that within a period of time after the end of the supply of oil to the distributor in the head of such a column from about 2 minutes the amount of oil remaining on the inner walls of the tubes has surprisingly decreased to less than 15 kg of oil, provided the viscosity of the oil film is less than 1 cP. Experiments with different sized falling film columns have also confirmed that the remaining amount of oil remaining in the falling film column has decreased to 1 to 2 per thousand of the nominal throughput per hour within a few minutes after the end of the oil supply.

In practice, the oil throughput per batch is hardly less than 5 tons. Under these conditions, approximately two minutes after the oil supply has ended, the in The remaining amount of oil remaining in the falling film column is so small that it can safely be mixed with the oil of the subsequent batch without fear of any noticeable changes in the oil parameters. Consequently, the deodorization and / or deacidification of relatively small, changing batches of cooking oils and other high-boiling liquids can be carried out in the falling-film columns known from DE-OS 29 14 101 or DE-PS 32 27 669 under the conditions described there, provided that in addition, certain measures are taken.

These additional measures include interrupting the oil supply to the falling film column for a short period of time when changing batches. In the context of the present invention, it has been found that even in the case of falling film columns with a length of 8 to 10 m, an interruption of a maximum of 4 minutes is completely sufficient to avoid mixing the different oil qualities with a noticeable change in the oil index when changing the batch, provided that subsequent batch comprises at least 5 tons of oil. In most cases, a brief interruption of the oil supply of about 1 to 2 minutes is sufficient to reliably avoid such a detectable mixture.

Therefore, the short period of time for which the application of the liquid to the distributor in the head of the falling film column is interrupted after the front face of the liquid of the new, subsequent batch has reached a shut-off valve arranged adjacent to this distributor is 4 minutes or less, particularly preferably 2 minutes or less.

The measures mentioned, which must also be taken, also include preventing the successive oil batches from mixing in the other remaining parts of the system when changing batches.

In addition to the usual components, such as pumps, fittings, valves and the like, these other parts of the system include in particular the feed line leading to the falling film column and the discharge line leading out of the bottom of the falling film column. According to a further aspect of the invention, a plug flow of the liquid is maintained in this feed line and in this drain line in order to avoid any noteworthy mixing of the successive oil batches when the batch is changed. Such a plug flow is ensured, for example, by a sufficient flow velocity of the oil, which ensures turbulent flow conditions in these lines. For this purpose, the flow rate of the oil in these pipes should be at least 1 m / sec. Flow velocities of at least 1.5 to 2.5 m / sec in these pipelines are even better; such flow rates are particularly preferred in the context of the invention.

When designing the pipelines, smooth inner walls with a uniform hydraulic diameter are aimed for. Grooves and other "dead" spaces in which liquid residues separated from the main fluid line could accumulate should be avoided. Insofar as changes in the hydraulic diameter of the effective line cross-section cannot be avoided in the area of pumps, valves and the like, these changes - in the direction of flow - should lead to smaller hydraulic diameters, thus increasing the flow velocity and increasing the turbulent flow characteristics.

If these two additional measures are taken and adhered to, the new liquid to be treated can be introduced into the feed line immediately after the liquid of the previous batch when the batch is changed, without any idle batch. Thereby a higher throughput per unit of time is achieved because the empty batches required according to the prior art are no longer necessary to avoid mixing of the different oil qualities when changing batches. Furthermore, the operation of pumps, heat exchangers and the like is simplified because the system can be operated practically continuously with a full liquid line.

Avoiding any empty batches when changing batches is an expedient and advantageous measure within the scope of the present invention, but not a necessary one. If it is desirable in individual cases, a tightly dimensioned empty batch could also be provided when changing the batch in order to avoid direct contact between the previous and the subsequent liquid. Alternatively, in order to avoid such direct contact, an inert buffer substance could also be introduced after the previous liquid, to which the subsequent liquid then connects in order to avoid a decrease in pressure within the pipelines when the batch is changed. In the context of the invention, it is preferably provided in the event of a batch change that the new liquid to be treated is introduced into the feed line immediately after the liquid from the previous batch, without any idle batch.

In the deodorization and / or deacidification of cooking oils, it is common practice to use the sensible heat of the hot finished oil to heat the crude oil. Typically, the hot finished oil is passed as a "heat medium" through a heat exchanger in which the crude oil is brought to a temperature which is approximately 20 to 30 ° K below the intended working temperature. The rest of the heating to the working temperature then takes place in a downstream high-temperature heat exchanger. According to an advantageous embodiment of the invention, this takes place Heat exchange between hot finished oil and crude oil in one or more double tube exchanger (s) whereby a plug flow of the liquid is maintained both in the inner tube and in the outer tube of the double tube exchanger. A suitable double tube exchanger can have a straight or curved configuration; for example, a spiral configuration can be provided to accommodate a larger heat exchange capacity in a given volume. Because the exchange performance of a double tube exchanger often does not reach that of the otherwise conventional heat exchangers, two or more double tube exchangers are expediently provided in order to transfer the sensible heat of the hot finished oil completely to the crude oil to be heated.

Preferably, approximately the same hydraulic diameters are provided for the cross section of the inner tube and the effective cross section of the outer tube of such a double tube exchanger. Such values are preferably provided for these hydraulic diameters so that the same flow velocity of the liquid as in the feed line also prevails in the inner tube of the double tube exchanger; Accordingly, such dimensions are provided for the effective cross section of the outer tube of the double tube exchanger so that here the liquid flows at the same speed as in the drain line. The same flow velocities of the liquid are particularly preferably provided in the feed line, in the outlet line, in the inner tube and in the outer tube of the double tube exchanger or tubes. In order to ensure a plug flow with turbulent flow characteristics, this flow speed should be at least 1 m / sec. Flow velocities of at least 1.5 to 2.5 m / sec are even better. Therefore, the flow velocity of the liquid in these parts of the plant should particularly preferably be at least 2 m / sec. be.

Falling film columns of the type known from DE-OS 29 14 101 or DE-PS 32 27 669 are typically designed for deacidifying 5 or 10 tons of cooking oil per hour. These falling film columns can also be adapted without difficulty to a larger throughput, for example to the deacidification of 50 tons of cooking oil per hour. With the method according to the invention, it is also possible to economically carry out the deodorization and / or deacidification of relatively small, changing batches of high-boiling liquids, in particular edible oils, in these relatively large, highly effective systems. Even small batches of edible oil can now be de-acidified quickly and gently, ie with a residence time of less than 1 minute in the high temperature area of the system at temperatures above 200 ⁰ C and / or deodorized. Under these conditions, most of the natural stabilizers such as tocopherols, sterols and other similar compounds are retained, so that an oil treated in this way has an improved shelf life. A batch change can be carried out in a few minutes, for example in 6 minutes or even less. The empty batches necessary according to the state of the art are neither required, nor do any significant product losses occur. Despite this extremely rapid batch change, there is no noticeable mixing of the successive batches when changing from one oil quality to another, which would lead to a demonstrable change in the key indicators of an oil quality.

Within the scope of the present invention, modifications and alterations to the above-described process for deodorization and / or deacidification of relatively small, changing batches of high-boiling liquids are possible.

In the event of a batch change, it is possible to switch directly from one supply tank with a certain liquid to another supply tank with another specific liquid. A feed pump closes the new one Treating liquid in the feed line, so that its front side directly connects to the liquid of the previous batch. After the end face of the subsequent batch has reached the shut-off valve located adjacent to the distributor in the head of the falling film column in the course of a batch change, this shut-off valve is closed in order to shut off the oil supply to the falling film column. This shut-off valve is preferably designed as a quick-switching valve. After blocking, the contents of the falling film column, which still consist of the previous batch, can be emptied in two different ways. During a first period within this short period of interruption of the liquid feed, the liquid collecting in the bottom of the falling film column is still pressed into the discharge line. This is followed by a switchover of a valve inserted into this drain line, and the amount of liquid that still accumulates in the bottom of the falling film column during this subsequent second period of time during the interruption of the liquid feed passes into a separate container. With the opening of the valve adjacent to the distributor in the head of the falling film column in order to treat the subsequent liquid batch in the falling film column, a valve inserted into the line leading to the container is closed. The treated liquid from the subsequent batch, which is now accumulating in the bottom of the falling film column, is again pressed into the discharge line.

This container for holding a second residual amount of the falling film column content after the liquid feed has been blocked on the distributor in the head of this falling film column can be equipped with a cooling device. Furthermore, the addition of a complexing agent such as citric acid can be provided in this container in order to stabilize the liquid accumulated therein. The container is also connected to various stages of the vacuum system. The contents of this container will eventually appear in the product tank for the finished oil of the previous batch transferred. While the second part of the falling film column contents are draining into the container, the discharge line can be blown free with an inert gas, as will be explained in more detail below with reference to FIG. 2.

It is also possible to blow out the plant parts next to the falling film column with an inert gas such as nitrogen. This can be expedient in particular for the discharge line in order to avoid any possibility of mixing the finished oil of the previous batch with the front of the treated oil of the subsequent batch within this discharge line. The discharge line is expediently blown out within the second time period, while the second part of the falling film column contents runs into the container.

The invention relates to the deodorization and / or deacidification of relatively small, changing batches of high-boiling liquids, namely fatty acids, edible oils, fats, glycerides and other high-boiling esters. In this context, "high-boiling" means that the liquid to be treated would boil at a negative pressure of 12 mbar above its decomposition temperature of about 300 ^° C. Suitable fatty acids include, for example, higher-boiling, anhydrous fish oil fatty acids and other hydrogenated fatty acids in order to remove their hydrogenation odor. Suitable edible oils include, for example, palm oil, soybean oil, cottonseed oil, coconut oil, palm kernel oil, rapeseed oil, olive oil, wheat oil, hydrogenated fish oil and the like. Suitable fats include, for example, beef tallow, lard, "muttontallow" (= sheep tallow) and the like. In addition to the triglycerides, suitable glycerides include the mono- and di-glycerides of any fatty acids, for example synthetically produced triglycerides, which melt at body temperature (for example for supositorial masses). Other high-boiling esters include, for example the esters of phthalic acid, sebacic acid and the like which are suitable as plasticizers, and the esters of higher alcohols with fatty acids, such as butyl stearate and similar esters. In addition, the method according to the invention is suitable for eliminating the hydrogenation odor of other hydrogenated fats and oils.

"Relatively small batches" in this context means that a batch of a certain liquid with matching key figures such as iodine number, glyceride composition, titer etc. comprises an amount of at least 5 tons. Typically, a "relatively small batch" comprises about 20 to 50 tons of liquid. In the context of the invention, the deodorization and / or deacidification takes place in falling film columns, which can typically be designed for a throughput of 5, 8 or 10 tons per hour, but in individual cases also for a throughput of 50 tons per hour. Under these conditions, a batch change is necessary after a few hours. Under the conditions provided by the invention, such batch changes can be carried out within six minutes or in a shorter period of time, so that the throughput losses customary in the prior art when changing batches are very considerably reduced. Nevertheless, mixing of the successive batches, which would lead to a noticeable change in the key figures, can be largely or completely avoided; A complete avoidance of the mixing is possible if the second part of the falling film column contents is collected in a separate container within the second period of short-term interruption of the liquid application to the falling film column, and the discharge line is blown free with inert gas during this second period. The second part of the falling film column contents collected in the separate container can be discharged into the product tank of the previous batch at a later time during the treatment of the second batch. In this way, when the batch is changed, not only does the mixture mix up completely avoided subsequent batches, but there is also no product loss.

• Fig. 1: ein erstes Fließschema einer Anlage zur Durchführung des erfindungsgemäßen Verfahrens; und
• Fig. 2: ein zweites Fließschema einer Anlage zur Durchführung des erfindungsgemäßen Verfahrens, wobei zusätzlich ein Auffangbehälter für einen Teil des Fallfilmkolonneninhalts vorgesehen ist.

The system for carrying out the method according to the invention is explained below on the basis of preferred embodiments with reference to the drawing; it shows:

• 1: a first flow diagram of a plant for carrying out the method according to the invention; and
• 2: a second flow diagram of a plant for carrying out the method according to the invention, a collecting container for a part of the falling film column contents being additionally provided.

As can be seen from FIG. 1, the overall system for deodorization and / or deacidification of relatively small, alternating batches consists in the main parts - in addition to the usual components of such systems such as pipelines, pumps, fittings, regulators and the like which are not mentioned in detail - mainly from the crude oil Storage or inlet tanks 10, the feed line 15, the falling film column 20, the outlet line 35, the heat exchanger 40 and the product tanks 45.

In detail - as can be seen from FIG. 1 - there are several feed tanks 10, 10 ', 10 "in which the various batches of the oils to be treated one after the other are located. After the valves 11, 11', 11" have been switched accordingly, the desired crude oil is obtained pressed by the feed pump 12 into the feed line 15. The feed line consists of several feed line sections 15, 15 ', 15 ", 15"' and finally leads to the distributor 22 in the head 21 of the falling film column 20. The feed line section 15 leads to a first double-tube heat exchanger 40. In the illustrated embodiment, the crude oil to be heated flows through the outer jacket tube 41, which surrounds the inner tube 42 of this double tube exchanger 40. By the inner tube 42 is passed hot finished oil. Alternatively, the opposite liquid flow could also be provided, ie the cold crude oil flows through the inner tube 42 and the hot finished oil through the outer jacket tube 41. A second feed line section 15 'leads to a second, essentially analog, double-tube heat exchanger 43, in which heat exchange is carried out hot finished oil there is a further heating of the crude oil. Again, this second double-tube heat exchanger 43 has an outer jacket tube 41 'and an inner tube 42'. From the second double-tube heat exchanger 43, the crude oil passes through a second section of the feed line 15 ″ into a high-temperature heat exchanger 44, in which the remaining heating to the intended working temperature takes place. The high-temperature heat exchanger 44 is also expediently designed as a double-tube heat exchanger Heating medium is supplied to the high-temperature heat exchanger 44 and led away via the connecting piece 46. In the intended temperature range, high-pressure steam or a high-temperature oil such as "HT oil" (higher aromatic compounds) can be used A third feed line section 15 "'finally leads to the distributor 22 in the head 21 of the falling film column 20. Adjacent to the distributor 22, the shut-off valve 16 is inserted in this third feed line section 15"'. The shut-off valve 16 is preferably designed as a quick-acting valve to control the Liquid Interrupt the task on the falling film column immediately after the front face of a subsequent batch reaches this shut-off valve 16. After the length of the supply line 15, 15 ', 15 ", 15"' from the valves 11, 11 ', 11 "to the shut-off valve 16 and the flow rate of the liquid are known, the switching of the shut-off valve 16 can be time-dependent with a certain delay after actuation of the valves 11, 11 'and / or 11 ".

In the embodiment shown, the falling film column 20 has a single stage, and its trickle channels 23 have uniform, constant trickle channel diameters over the entire length. The trickle part of the falling film column 20 can be constructed from a tube bundle with 60 tubes 23, which have a length of 8 m and a diameter of 50 mm. The individual tubes 23 are washed around their outer circumference by heating medium, which is supplied via the nozzle 24 and discharged via the nozzle 25. As shown, a countercurrent flow of the heating medium to the flowing liquid film is provided; High-temperature oil is preferably used as the heating medium in order to produce a temperature gradient on the heating medium side. In this way, an optimal heat exchange can be guaranteed and, on the other hand, overheating of the liquid can be avoided.

The motive steam supply 27 is located in the sump chamber 26 of the falling film column 20. In countercurrent to the flowing down liquid film, the motive steam flows through the trickle channels 23 and collects in the head together with the low boilers removed from the oil. From there, the steam mixture is drawn off via the steam line 28 which leads to the vacuum system via an injection condenser (not shown).

The treated finished oil collecting in the sump 26 of the falling film column 20 is pressed into the discharge line 30 by the feed pump 29. The drain line 30 leads to the double-tube heat exchangers 43 and 40, in which the hot finished oil transfers part of its sensible heat to the crude oil to be heated. After passing through the double-tube exchanger 40, the largely cooled finished oil passes through a further drain line section 30 ″ into a final cooler 47, to which cooling water is supplied as coolant. The finished oil then passes into one of the product storage tanks 45, 45 ′ or 45 ″.

In addition, a stabilization container 32 can be provided, in which a complexing agent serving for stabilization, such as citric acid, is added to the finished oil. In the illustrated embodiment, this stabilization tank is inserted between the two double-tube heat exchangers 43 and 40, so that the finished oil has already partially cooled when it reaches the stabilization tank 32 via the second drain line section 30 '. The stabilizing agent, such as, for example, citric acid, is fed to this stabilizing container 32 from a corresponding supply (not shown) via a metering valve 33 and the metering line 34. The stabilization tank 32 is vented to the vacuum system via the steam line 35. The finished oil mixed with stabilizer is drawn off from this stabilization tank 32 by means of the pump 36 and pressed in the form of a plug flow into the second drain line section 30 ″, which leads to the double tube exchanger 40.

In the illustrated embodiment, the single-stage falling film column 20 is designed for a palm oil throughput of approximately 8 to 10 tons per hour. In relation to this throughput, the various supply line sections 15, 15 ', 15 "and 15"', the different discharge line sections 30, 30 ', 30 "and 30"' and the liquid-carrying pipes within the heat exchangers 40, 43, 44 and 47, a hydraulic diameter of about 44 to 52 mm was provided to maintain a plug flow of the liquid within these tubes. With a pipeline diameter of 50 mm and a mass flow of 8,300 kg of palm oil per hour, a flow rate of approximately 1.5 m / sec will occur in these pipelines. Such a flow velocity provides a turbulent flow characteristic and thus certainly the desired plug flow. Thanks to this plug flow, the valve 11 can be closed and changed immediately after the feed tank 10 has been emptied For example, the valve 11 'leading to the feed tank 10' can be opened, so that the front face of the subsequent batch from the crude oil tank 10 'is pressed by the feed pump 12 immediately after the previous batch through the feed line sections 15, 15', 15 "and 15"' becomes.

After this front end has reached the shut-off valve 16, it is closed for a short period of time in order to interrupt the supply of crude oil to the distributor 22 of the falling film column 20. Because of the preferably provided design of the shut-off valve 16 as a quick-switching valve, a precise and instantaneous interruption of the liquid flow is possible. During this brief interruption, propellant steam continues to be introduced into the falling film column 20, so that the falling film column contents are completely deacidified and / or deodorized and reach the discharge line section 30.

FIG. 2 shows a further installation for carrying out a modified embodiment of the method according to the invention. Essentially, the plant according to FIG. 2 is constructed analogously to the plant according to FIG. 1; to the extent that there are similarities, reference is made to the explanation of corresponding plant parts in FIG. 1.

The main differences are that the falling film column is of two stages, in addition there is a container for holding part of the falling film column contents during the short-term interruption of the liquid supply to this falling film column, and devices are provided for blowing out the feed line and in particular the discharge line using inert gas .

Deviating from this, the falling film column 50 is of two stages. In the head 51 of this two-stage falling film column 50 is the distributor 52, via which the feed Liquid is first distributed over the wide trickle tubes 53 of the initial zone of this falling film column 50. These wide trickle pipes 53 can have a length of 4 m and a trickle channel diameter of 84 mm, for example. Following these wide trickle tubes 53, the trickling down liquid film is collected again in a second distributor 54 and from there distributed to the narrow trickle tubes 55 of the closing zone of this falling film column 50. This closing zone can be formed, for example, from 153 pipes with a length of 7 m and a pipe diameter of 33 mm. With such a falling film column, 10 tons of palm oil per hour can be deacidified. Again, the outer walls of the wide trickle pipes 53 and the narrow trickle pipes 55 are flushed with heating medium, which is supplied via the sockets 56 and 58 and discharged via the sockets 57 and 59, respectively. The introduction of motive steam takes place exclusively by means of the motive steam supply 61 into the sump chamber 60 of the end zone of the falling film column 50. The motive steam first flows through the narrow trickle channels 55, then through the wide trickle channels 53 and is finally removed from the steam line 38 together with the separated low boilers Head 51 removed and fed to the vacuum system after cooling in an injection condenser (not shown).

The first discharge line section 30 branches off from a line 62 which leads from the sump 60 of the falling film column 50 via a shut-off valve 63 to a container 70. This container 70 serves to temporarily hold part of the contents of the falling film column 50 after the supply of the liquid to the distributor 52 by means of the shut-off valve 16 has been interrupted for a short period of time. As indicated schematically, this container 70 can be equipped with a cooling device 71 in order to cool the absorbed, completely deacidified and / or deodorized finished oil. The container 70 is connected to the vacuum system (not shown) via a damping line 72, depending on the position of the valves 73 or 74 a connection to the 120 mbar level or to the 4 mbar level of the vacuum system is possible. From a reservoir 80 a serving as the stabilizing agent may _complex-b ildner such as citric acid over a Doslerventil 81 and a metering are introduced into the container 70 82nd Furthermore, in contrast to the embodiment according to FIG. 1, stabilizing agent can be added to the finished oil in the first drain line section 30 via the second metering valve 83 and the second metering line 84 from this reservoir 80; alternatively, this second metering line 84 could also open into the second drain line section 30 ', so that the stabilizing agent is introduced into already partially cooled finished oil.

After a batch change has been made by appropriately switching the valves 11, 11 'or 11 "and the front face of the subsequent batch has reached the shut-off valve 16 adjacent to the distributor 52 in the head 51 of the two-stage falling film column 50, the shut-off valve 16 is closed for a short period of time During a first period of time within this brief interruption, the valve 37 in the first discharge line section 30 remains open, so that the feed pump 29 continues to draw the first part of the deacidified content of the falling film column 50 from its sump 60 and press it into the discharge line remains closed, a switchover then takes place, valve 37 being closed and valve 63 being opened, and the second part of the deacidified content of falling film column 50 now enters container 70, where it is cooled and stored for a while Valves 63 will we Iterhin supplied propellant steam so that the second part of the content of the falling film column 50 is completely deacidified and / or deodorized. After the falling film column 50 has been largely emptied, the shut-off valve 16 is opened again, the valve 63 is closed and the valve 37 is ge opens; for this purpose, a schematically indicated control system is provided between these valves, which also detects the fill level in the sump 60 of the two-stage falling film column 50.

Furthermore, devices are available for blowing parts of the system, in particular the discharge line 30, 30 ', 30 "', with an inert gas. Examples of suitable inert gases are nitrogen, argon, helium and the like, preferably using dried nitrogen Drain line 30, 30 ', 30 "' nitrogen can be blown into the first drain line section 30 via the connector 90 and the valve 91 and presses the liquid into the intended product tank 38, 38 'or 38".

Excess gas escapes via the nozzle 92 and the valve 93. Nitrogen is preferably injected via the nozzle 90 and the valve 91 into the first discharge line section 30, while the second part of the contents of the falling film column 50 is emptied into the container 70, the valve 37 closed and the valve 63 is open.

If required, the feed line 15, 15 ', 15 "and 15"' can also be blown free, for which purpose nitrogen can be blown into the third feed line section 15 "'via the nozzle 94 and the valve 95.

Finally, it is possible to blow nitrogen into the container 70 via the nozzle 96 and the valve 97 in order to press the oil therein into the line 75. Because this is completely deacidified and / or deodorized oil, it can be drained into the respective product tank 38, 38 'or 38 ".

Claims (19)

1. Process for deodorising and / or deacidifying relatively small, changing batches of high-boiling liquids, namely fatty acids, edible oils, fats, glycerides and other high-boiling esters,
the liquid heated to 180 ° to 280 ° C being treated with motive steam under a working pressure of less than 10 mbar,
characterized in that
the propellant steam treatment is carried out continuously in a single or multi-stage falling film column (20, 50), the trickle channel walls of which are kept at a higher temperature than the liquid film coming down, and propellant steam is conducted in countercurrent through these trickle channels (23; 53, 55);
a plug flow in the feed line (15, 15 ', 15 ", 15"') leading to the falling film column and in the discharge line (30, 30 ', 30 ", 30"') leading away from the sump (26, 60) of the falling film column the liquid is kept;
in the event of a batch change, the new liquid to be treated is introduced into the feed line immediately after the liquid from the previous batch, without any idle charge; and
the task of the liquid on the distributor (22, 52) in the head (21, 51) of the falling-flame column is interrupted for a short period of time after the front face of the liquid of the new batch has reached a shut-off valve (16) arranged adjacent to this distributor. 2. The method according to claim 1
characterized in that
the task of the liquid on the distributor (22, 52) in the head (21, 51) of the falling film column (20, 50) is interrupted for four minutes or less after the Front end of the liquid of the new batch has reached a shut-off valve (16) arranged adjacent to this distributor. 3. The method according to claim 1 or 2,
characterized in that
the application of the liquid to the distributor (22, 52) in the head (21, 51) of the falling film column (20, 50) is interrupted for two minutes or less after the front face of the liquid of the new batch has a shut-off valve arranged adjacent to this distributor ( 16) has reached. 4. The method according to any one of claims 1 to 3, wherein the treated hot finished liquid withdrawn from the falling film column transfers its sensible heat in the heat exchange at least partially to the raw liquid to be treated,
characterized in that
the heat exchange takes place in one or more double tube heat exchangers (40, 43); and a plug flow of the liquid is maintained both in the inner tube (42) and in the outer tube (41) of the double-tube heat exchanger. 5. The method according to any one of claims 1 to 4,
characterized in that
to ensure the plug flow of the liquid in the feed line (15, 15 ', 15 ", 15"') in the drain line (30, 30 ', 30 ", 30"') and, if necessary, in the tubes (41, 42; 41 ' , 42 ') of the double tube heat exchanger (40, 43) the flow rate of the liquid is at least 1 m / sec. 6. The method according to claim 5,
characterized in that
the flow rate of the liquid is at least 2 m / sec. 7. The method according to any one of claims 1 to 6,
characterized in that during a first period of time within the brief interruption of the liquid application onto the falling film column (20, 50), a first part of the falling film column contents is still pressed into the discharge line (30);
there is then a switchover; and a second portion of the falling film column contents is passed into a container (70) within the brief interruption of the liquid application to the falling film column. 8. The method according to claim 7,
characterized in that
the introduction of motive steam into the sump (26, 60) of the falling film column (20, 50) is also continued during the second period. 9. The method according to any one of claims 1 to 8,
characterized in that
after a batch change, the parts of the system carrying the liquid are blown free with an inert gas next to the falling film column. 10. The method according to any one of claims 7 to 9, characterized in that
within the second time interval the discharge conduit (30, 30 ', 30 ", 30"') including, the treated finished liquid-carrying pipe sections (41, 41 'or 42, 42') of / the double tube Wärmetau _- shear (40 , 43) are blown free with an inert gas. 11. Plant for performing the method according to one of claims 1 to 10,
with a single or multi-stage falling film column (20, 50), with a feed line (15, 15 ', 15 ", 15"") from a number of liquid feed tanks (10, 10', 10") to a distributor (22, 52) in the head (21, 51) of the falling film column to lead,
with a drain line (30, 30 ', 30 ", 30"') leading from the sump (26, 60) of the falling film column to a number of product tanks (38, 38 ', 38 ").
characterized in that
the feed line and the outlet line - depending on the capacity of the falling film column - have a diameter such that the liquid in these lines flows with a plug flow; and a shut-off valve (16) is inserted into the feed line (15 "') adjacent to the distributor in the head of the falling film column. 12. Plant according to claim 11,
characterized in that
the feed line (15, 15 ', 15 ", 15"') and the outlet line (30, 30 ', 30 ", 30"') have a diameter of 44 to 52 mm, provided that the falling film column (20, 50) for one Throughput of 8 to 10 tons of cooking oil per hour is designed. 13. Plant according to claim 11 or 12, wherein heat exchangers (40, 43) for heat exchange between hot finished liquid and raw liquid to be heated are present,
characterized in that
these heat exchangers are designed as double-tube heat exchangers (40, 43). 14. Installation according to claim 13,
characterized in that
the inner tube (42, 42 ') and the effective cross section of the outer tube (41, 41') of the double tube heat exchangers (40, 43) have approximately the same hydraulic diameter. 15. Plant according to claim 14,
characterized in that
the hydraulic diameter corresponds to a pipe cross section of 44 to 52 mm, provided that the falling film column (20, 50) is designed for a throughput of 8 to 10 tons of cooking oil per hour. 16. Plant according to one of claims 11 to 15,
characterized in that
the high-temperature heat exchanger (44) and the final cooler (47) are designed as double-tube heat exchangers, through the inner tube of which the liquid can flow with a plug flow. 17. Plant according to one of claims 11 to 16,
characterized in that
the sump (60) can be connected via a line (62) to a container (70) which serves to hold the second part of the contents of the falling film column (50) after the valves (16 and 37) have closed and the valve (63) has been opened. 18. Installation according to one of claims 11 to 17,
characterized in that
Shut-off valve (16) adjacent to the distributor (22, 52) in the head (21, 51) of the falling film column (20, 50) is a quick-acting valve. 19. Plant according to one of claims 11 to 18,
characterized in that
Devices are provided to blow the system parts apart from the falling film column (20, 50), in particular the discharge line (30, 30 ', 30 ", 30"'), with an inert gas.

Images