DE2622520C2 - Process and system for the continuous pre-cleaning and bleaching of vegetable and animal oils and fats - Google Patents

Description

When refining oils and fats (TrI or Monoglycerides) unwanted accompanying substances are previously removed in several separate process stages! Such accompanying substances are mainly:

1. Oil-soluble mucilage (phosphatides, etc.)

2. low-boiling residues (water, solvent residues) and the like.

3. mechanical impurities

4. Dyes

5. Free fatty acids

6. Flavor and odor substances (mainly ketones and aldehydes)

Pesticide residues

7th

For some time now it has also been possible on a large scale to combine the accompanying substances mentioned under 5 to 7 in one single continuous work cycle through a deodorization combined with a destlllatlven deacidification to be eliminated economically and emission-friendly. This method according to DBP 11 17 804 has successfully found its way into the industry.

A prerequisite for this and other comparable processes is good pre-cleaning, i. H. the Removal of the accompanying substances mentioned under 1 to 3. For this, the use of acids, e.g. B. phosphoric acid, and alkalis, mainly NaOH, in batch or continuous centrifuge process known and customary. Such pre-cleaning processes are, however, with associated significant disadvantages.

From the combination of lye with free fatty acids This is because the result is a salt in the aqueous phase as an intermediate product with the internationally common name of “soapstock”. This salt must then be decomposed with sulfuric acid to make the so-called inferior To obtain refined fatty acid. In addition to corrosion, there are also air and wastewater emissions problems. These disadvantages should be reported.

The above-mentioned process is followed by the bleaching of the products with dye-absorbing bleaching agents (activated fuller's earth, activated carbon) Batch or continuously operating equipment with subsequent separation of the bleaching agent from the oil via filter.

The object of the invention is now the pre-cleaning with regard to the accompanying substances mentioned under I. to 3. and the bleaching with regard to the dyes mentioned under 4. to form a continuous process sen. Accordingly, in terms of method, the invention consists in that the product to be treated is sequentially is passed through several horizontal cylinders, a reaction with metered addition in the first cylinder Reagents for removing non-hydratable and hydratable sludge substances while avoiding the Lye is used, vacuum drying in the second cylinder with simultaneous swirling

Ϊ the mixture is carried out by means of superheated steam and heat supply and then, after a bleaching agent has been added, the mixture is fed into the third cylinder for a residence time that can also be selected.

A system that is used to carry out such a method according to the invention includes three cylinders lying one below the other, namely alternately slightly inclined in opposite directions, of which the first contains cascade-like built-in components, which expediently consist of perforated floors, I ο during the second and third cylinder connected on the one hand to a vacuum generator, on the other hand with; superheated steam heatable 1st. Furthermore, the first cylinder, into which the product to be treated and reactants are introduced, is directly connected to the second cylinder by a line, while the second cylinder is connected to the third cylinder via a ^: and is downstream.

Further details of the system and how it works result from the following explanation of an embodiment shown schematically in the drawing.

The product to be treated is conveyed by means of a pump 1 through a line 2 with the interposition of two heat exchangers 3 and 4 into the first cylinder 5. In the same cylinder open, also in the upper area, two further lines 6 and 7, which are used to supply reagents, the required amount of which can be adjusted by metering devices 8 and 9 , respectively. A short connecting line 7 to the product line 2 branches off from one line 7 before it flows into the cylinder S.

The cylinder 5 contains a plurality of perforated grooves 10, which are spaced one above the other, from the bottom of this Cylinder, at the slightly lower end, a line 11 leads into the upper area of the next lower one Cylinder 12. This cylinder contains a heating line 13 and a perforated tube 14 through which from a line 1: 'of superheated steam into the mixture' 0 is introduced. Also, this cylinder is in the top Area connected to a vacuum generator 17 via a vapor suction line 16.

From the bottom of the last-mentioned cylinder 12, namely at the slightly lower end, a line 18 'leads via a pump 19 to a mixing container 20. This container is designed in the manner of a cyclone in which the product from the line 18 is approximately tangential at high speed flows in. A bleaching agent fed centrally by means of a screw 21 is also entrained by this vortex flow, which continues from top to bottom, so that it mixes well with the product.

Then the mixture of oil or fat and Fuller's earth or the like. By means of a further pump 22 through a line 23 into the third (lowermost) cylinder 24 funded. This cylinder, like the cylinder 12 above it, contains a heating line 25 and a perforated one Tube 26, which is connected to the superheated steam! feeding Line 15 is connected; in addition, it is also connected to the vacuum generator via a vapor suction line 27 17 In connection.

From the bottom of the last (lowermost) cylinder 24, a line 28 finally leads via a pump 29 and the a heat exchanger 3 to filters (not shown).

The connection line T serves to mix some of the reagent substances supplied through the line 7 with the product conveyed through the line 2 before it enters the uppermost cylinder 5. While the product then flows over the perforated channels 10, which act as cascades, the reaction process essentially takes place. This is further promoted by the fact that the channels 10 are alternately the same or slightly inclined towards the associated cylinder 5, so that the product mixed with the reagents in the desired proportion also executes a longitudinal flow to opposite sides of the cylinder. The desired dwell time of the product in this cylinder 5 can also be set by a level regulator (not shown), by means of which a certain overflow level of the amount of product that collects on the bottom is ensured.

In the middle cylinder 12, the product after the reaction process in the upper cylinder 5 effected pre-cleaning dried. For this purpose, the evacuation of the vapors via line 16 is used, while through the heating line 13 heat? supplied and through the perforated tube 14 superheated steam into the Mixture is introduced to swirl the same.

The product which has been pre-dried in this way, possibly only a partial amount of it, is passed through the line 18 is fed to the container 20 by means of the pump 19. In this it is cyclone with the through bleach supplied to the screw 21; then the product is by means of the further Pump 22 is conveyed through line 23 into lower cylinder 24. Also in this cylinder are used for further Drying of the mixture, the vapors are sucked off via a line 27, while through the heating line 25 Heat is supplied and superheated steam is introduced through the perforated tube 26.

The residence time of the product in the lower cylinder 24 and thus the bleaching effect can be adjusted accordingly the level control in the upper cylinder 5 and possibly also in the middle cylinder 12, by means of a suitable, known device with adjustable overflow height.

All three cylinders 5, 12 and 24 are otherwise set up so that their fixtures can be easily removed from one end face by means of a removable flange Have catfish installed and removed. To do this, z. T. only the connections to those on the opposite side Cables opening into the front are temporarily released.

The particular advantages of the new method according to the invention and one for carrying out this method Serving system consist primarily in the fact that now the two operations that were previously carried out separately Pre-cleaning and bleaching of such a product into one continuous, in a single one System carried out are summarized. Furthermore, a decantation of the after Reaction process in the liquid state product in special settling containers as well as on the use Mechanical mixing devices are dispensed with after the supply of bleach. In the end Is still the thermally advantageous arrangement of the heat exchanger 3 to be mentioned, on the one hand from the Ehisatzprodukt supplied through the line 2, on the other hand, the finished product discharged through line 28 flows through it.

The implementation of> .r individual procedural steps does not generally need to be done in one cylinder each.

1 sheet of drawings

Claims (7)

installment claims; 1. Process for pre-cleaning (removal of oil- soluble residues, low-boiling residues and mechanical impurities) and bleaching (removal of dyes) of vegetable and animal oils and fats, characterized by the continuous sequence of process steps that in a first stage reagents are added and dosed Are mixed into the crude product that the mixture is kept in a second and third stage with vapor extraction under reduced pressure, during which superheated steam is added to the mixture at the same time, and that between the second and third stage bleaching agent is added to the mixture while swirling the mixture, whereby low-boiling constituents are continuously withdrawn as vapors and finally the dyes bound to the bleaching agent and the sludge substances precipitated by the action of the reagents and by hydration and solidified by the removal of moisture, as well as other Fe substances are excreted by filtration. 2. Plant for carrying out the method according to claim 1, characterized in that it consists of three treatment rooms (5, 12, 24) connected to one another by pipelines, the first (5) of which with means (8, 9) for metered addition and means ( 10) is provided for mixing in reagents, the second (12) and third (24) treatment room of which is connected to a vacuum generator (17) via vapor extractors (16, 27) and has perforated pipes (14, 26) below the liquid level for addition : n steam, and that in the transition from the second (12) to the third (24) treatment room a mixing container (20) for mixing in bleaching agents is arranged, while the third treatment room (24) is followed by a filter. 3. Plant according to claim 2, characterized in that the first treatment room is a lying one Cylinder (5) is used, in which perforated channels (10) are installed in a cascade-like arrangement, the Bores in the channels (10) are dimensioned in terms of number and dimensions for partial overflow and partial rain of the product. 4. Plant according to claim 3, characterized in that the cylinder (5) and at least the lower the channels (10) are slightly inclined to the horizontal and opposite to each other and from the bottom of the At the lower end of the cylinder (5) a drain (11) leads to the second treatment room. 5. Installation according to one of the preceding claims, characterized in that between the Perforated channels (10) in the cylinder (5) spray tubes for the addition of some of the reagents are arranged. 6. Installation according to Ans ^- uch 2, characterized in that the transition from the second (12) to the third (24) treatment room arranged mixing vessel (20) having an upstream and downstream pump (19, 22) is provided. 7. Plant according to claim 6, characterized in that the mixing container (20) as known per se cyclonic mixer is designed, in which a screw (21) with central to the mixing container (20) located outlet for supplying the bleach Is seen while an approximately tangential into the container (20) opening feed for the high The speed of the product conveyed and an outlet for the product mixed with the bleaching agent is provided at the bottom of the container (20), S. Plant according to claim 6, characterized in that for conveying the product from the third treatment room (24) via the pipeline (28) a pump (29) is provided, which ducts the PiL> Filtering promotes.