EP0052218B1 - A process for treating soyabeans - Google Patents

Description

The invention relates to processing soybeans with crushing for flocculation before extraction in a method for extracting soybean oil and soybean meal.

The soybean contains a lecithin-containing oil of approx. 20% and protein of approx. 36%. In the processing of the soybean, the separation is carried out, whereby the oil is obtained and the extracted material is used as feed meal, the extraction usually being carried out by solvents. Today two types of meal are produced, a so-called normal meal with a protein content of approx. 44% and a high-quality meal whose protein or protein content is approximately between 49-50%. With the high-quality meal, the protein content is increased by separating the bean hulls, which mainly contain fibers and other fibers.

In today's large-scale process, the beans are heated in a shaft dryer cooler to approx. 90 ° C and then cooled in the cooler to temperatures of approx. 10 ° C above ambient temperature. The aim of this process step, which brings about a moisture reduction of approx. 2% by weight, is that the husks become brittle, burst open and detach from the actual bean kernel. In order to achieve a satisfactory separation result, however, it is necessary to temper the whole beans for at least 48 hours before further processing. This happens in tempersilos, which are large and expensive structures. After the tempering, the whole beans are broken in the cold state with two-stage corrugated roller mills with the aim of exposing the shell parts and the core parts. The broken material is separated into core parts and shells using vibrating sieves, whereby the shells are suctioned off according to the vacuum cleaner principle. However, the remaining fraction still contains too large a proportion of protein and oil-containing core particles and must therefore be divided into shells and core parts in two further stages. This material, cleaned from trays, is then conditioned. Here the product temperature is raised again to approx. 60-65 ° C, which lowers the viscosity of the oil enclosed in cells and the previously hard bean break becomes plastic, so that the fragments can be stabilized with as little effort as possible on the subsequent flaking roller mills, approx. 3 mm thin flakes can be rolled out.

The conventional method just described appears to be uneconomical for various reasons. On the one hand, the material is warmed up, but then immediately cooled and broken in the cold state on the corrugating rollers, which mechanically stresses this device, which affects its service life, and after the break, the material is warmed up again to approx. 65 ° C. The effort of the process is therefore considerable. This makes the process discontinuous due to the need for storage in the temperature silos. The silos are a large and complex investment.

From US-A-3220451 a process for peeling the soybeans is described, in which a short thermal attack during fluidization of the beans is intended to detach the husks from the kernels so that they can be separated from the kernels by conventional means . Obviously, this does not always succeed in the state in which the heated beans come from the pretreatment, so that it is prescribed to cool the beans before peeling. This may make it difficult to make the process continuous. In addition, the cores must be reheated after cooling for further processing.

A similar process is also described in DE-B-2 354 617. The briefly thermally pretreated beans should be thrown against a solid wall and thereby peeled. Obviously, this cannot be achieved with simple means, because air pulsators and electromagnetic waves are used for pretreatment. The centrifuge is followed by a fluid bed classifier in which the total volume of the material to be processed is to be viewed. Given the considerable proportion of fine and meal kernel particles to be expected, which is to be expected in the treatment in the centrifugal device, an unsatisfactory sighting result can be feared with this technique with the heterogeneous material layer.

The object of the present invention is to make the method of the type described in the introduction more economical. The process should run continuously and the complex buildings should be superfluous. The economy should mainly be achieved with savings in energy consumption. There should also be a smaller load on the rolling mill chairs and the separating devices used, so that their service life is extended and their function is facilitated.

• a) Gleichmäßiges Aufwärmen sämtlicher Sojabohnen in einem Fließbett, mittels heißen Luftstroms während einer kurzen, eine Wärmediffusion zum Kerninneren vermeidenden Verweilzeit zu einer Temperatur, bei der die Schalen brüchig werden und sich von den Kernen lösen;
• b) mechanisches Zerlegen der aufgewärmten Sojabohnen in einem Riffelwalzenstuhl und einer nachgeschalteten Hammermühle zum Trennen der Schalenteile von den angewärmten Kernen und Freilegen des Materials in Schalenteile, Keime und Kerneteile;
• c) Sichten des freigelegten Materials mittels eines heißen Luftstromes in gröbere Kerneteile und in ein abgetrenntes Gemisch von Schalenteilen, Keimen, Fein- und Mehlkerneteilen;
• d) gleichmäßiges Durchwärmen der gesichteten gröberen Kerneteile in einem zweiten Fließbett;
• e) Brechen der durchgewärmten gröberen Kerneteile in dem durchgewärmten, konditionierten Zustand, und Führen des Bruches zur Flockierung und anschließender Extraktion;
• f) Sichten des Gemisches von Schalenteilen, Keimen, Fein- und Mehlteilen zur Rückgewinnung der Keime und Fein- und Mehlteile und Zuleiten mindestens der Fein- und Mehlteile davon dem Fluß der durchgewärmten gröberen Kerneteile.

According to the invention, this object is achieved by the following process steps which immediately follow one another and run continuously:

• a) uniform heating of all soybeans in a fluidized bed, by means of hot air flow, during a short residence time, which avoids heat diffusion to the core, to a temperature at which the shells become brittle and detach from the kernels;
• b) mechanical disassembly of the warmed up soybeans in a corrugated roller mill and a downstream hammer mill to separate the shell parts from the warmed cores and exposed the material in shell parts, germs and core parts;
• c) sifting the exposed material by means of a hot air stream into coarser core parts and into a separated mixture of shell parts, germs, fine and flour core parts;
• d) uniform heating of the sighted coarser core parts in a second fluid bed;
• e) breaking the warmed, coarser core parts in the warmed, conditioned state, and leading the fracture to flocculation and subsequent extraction;
• f) sifting the mixture of shell parts, germs, fine and flour parts to recover the germs and fine and flour parts and supplying at least the fine and flour parts thereof to the flow of the warmer coarser core parts.

Energy savings are achieved simply by bringing the material to be processed only once, in the fluidized beds, to the highest level of the thermal process of the technology. Also due to the fact that there are already smaller objects with short diffusion paths when heated.

The mechanical disassembly takes place in two steps and in the plastic state of the core parts, so that there are few fine and flour core parts. Since the material is sighted before it is warmed up, the system for recovering the oil and protein-containing particles only needs to be designed for a fraction of the total volume of the material to be processed. A practically perfect separation of the shell parts is achieved, so that a better quality of the high-quality soybean meal can be produced.

The process is continuous, expensive silo structures are unnecessary and the mechanical load on the device used for breaking is reduced, since the processing, the breaking, is carried out in a warm state. The subject matter of the invention is explained in more detail below on the basis of a description of an exemplary embodiment of a system provided for carrying out the method.

The description relates to a drawing, in which a diagram of an advantageous system for carrying out the method according to the invention is shown.

The beans to be processed come via a line 25 into a first fluidized bed 1, to which a further fluidized bed 2 is assigned. The two fluid beds are arranged one behind the other. With the system shown, the high-quality meal can be produced with a protein content of approx. 49-50%.

The soybeans are heated uniformly in the first fluidized bed 1 with a hot air temperature of 165-170 ° C to 75 ° C. The residence time of the material in the fluidized bed is less than 2 minutes. Due to this dwell time, no significant diffusion occurs, so that a maximum of 0.5% moisture is removed from the imported beans. This is very desirable for reasons of mass balance. It has been shown that this rapid heating of the beans is sufficient for the shells to become evenly brittle and to be detached from the kernels. All imported beans are warmed up evenly.

The heated beans are fed from the fluidized bed 1 via a line 26 to a single-stage corrugating roller mill 3 and from there to a downstream hammer mill 4. On these two devices, the beans with the loosened shells are mechanically disassembled, which is a first step for separating the shells from represents the cores. By appropriately selecting the roller gap and the corrugation, as well as the sieve of the hammer mill, the beans are divided into two halves in this processing stage. At the same time, the previously thermally detached shells detach and are exposed. The bean sprouts are also exposed. The material processed in this way is now led into the second fluidized bed 2 against the exhaust air flow from the second fluidized bed 2, in such a way that the shells and the fine to flour parts produced during processing are discharged with the exhaust air.

The material is guided against the exhaust air flow via a distribution controller 5, where it is entered into a number of viewing channels 6 in the fluidized bed hood.

A suitable device for evenly distributing the material to be introduced into the exhaust air flow would also be exhaust air pipes designed as sifters on the fluidized bed hood of the fluidized bed 2.

By a suitable choice of the visual speed, that is, the speed of the exhaust air flow, which is simply regulated by a throttle valve in the exhaust port 7, both the shells and the fine and meal core parts and, in the case of extreme sighting, the germs can still be separated. In the latter case, a mixture of shell parts, germs and fine and flour parts on the order of 15% of the throughput A falls on the shell side. This value can be reduced to at least 10% if the germs are not extracted.

At the same time, this value also means that the further separation of shells and the material to be recovered has to be designed for only 15% of the system output.

According to what has been described, there are 2 coarser core parts and possibly the germs in the fluidized bed. Everything else, if it got into the fluidized bed 2, was carried out of the fluidized bed 2 by means of suitable exhaust air flow regulation, possibly also the germs. This in the fluidized bed 2 kept warm and thus warmed, conditioned material is then ge via a line 28 or 36 to the break rollers 23 to break ge leads and continues via a connection 37 to the flocculation device 24 for flocculation. The flocculated material is passed through line 38 for extraction.

The mixture of shell, germ and core parts, i. H. Fine and flour parts is led via lines 44 to a cyclone device with cellular wheel locks 12 and is separated from the air. A particle mixture is also added to this mixture, which has been separated from the exhaust air of the first fluidized bed 1 in the cyclone devices 8 and 10 and is brought here via a transport device 15. The mixture comes from a transport device 16 via a line 29 into a classifier 17. Here, the separation into a germ or germ parts -fine core parts fraction and a shell / flour fraction takes place. After a further cyclone separation in the apparatus 18, shells and flour are separated from one another in a 1-deck sieve 21 with a 1 mm sieve and the valuable oil- and protein-containing flour is returned to the main product stream via line 32 before flocculation or via line 49 before extraction fed. The amount of flour produced is approx. 1% of the plant output. The seed parts / fine core parts fraction, which was obtained on the classifier 17, is fed via line 33 to the main product stream from line 28 via the common line 36 together for breaking onto the roller mill 23.

It is possible, and indicated in dashed lines in the diagram, to separate the germ parts / fine core parts fraction obtained on the classifier 17 on a 1-decker sieve 22, the fine core parts being introduced via line 34 into line 36 and the separated germ parts via a line 35 to be eliminated from the process.

The shell-free half or coarser core parts, which have entered the second fluidized bed via the viewing channels 6, are fluidized there, the shell parts, which may still be adhering, being detached by the mutual friction of the particles and being discharged with the exhaust air. The final product temperature is also regulated in this fluidized bed 2 and at the same time, in conjunction with the regulation of the first stage, moisture reductions of between 1 and 2% can be set.

The amount of air required for fluidizing the fluidized beds 1 and 2 is essentially circulated, specifically through lines 42, 43, 46 and 40. Only the moisture removed from the material, ie. H. The amount of air required for the extracted water is fed to the system as fresh air via line 47 and discharged as exhaust air via lines 41 and 24. Due to the small amount of exhaust air, a minimal environmental impact is achieved, the lowest possible energy consumption is guaranteed and an optimal use of the energy is ensured.

The air is heated in the system shown here by direct combustion of gaseous or liquid fuels.

In addition to this air heating solution, there is also the option of supplying the heat required to heat the material to the fluidized bed via heat exchangers. There are heat exchanger tubes built into the fluidized bed, which are heated with steam, thermal oil or the like.

As described, the material comes from the fluidized bed 2, as does the material after the classifier 17 or after the 1-decker screen 22 through the lines 33 or 34 in the warm state into the commercially available two-stage roller mills 23, in order to be broken warm there . This hot crushing results in an increase in throughput and a saving in specific energy costs compared to conventional cold crushing. In any case, there is a significant improvement in the abrasion in the case of husk-free soft beans and thus a significantly longer service life of the rollers. The break obtained in this way corresponds to that of the cold-broken beans except for the flour content in the sieve analysis and is just as easy to flake. The total flour content in cold-broken beans is approx. 5%, that in warm-broken half beans is only approx. 1%, ie together with the additional share of 1% from the preparation or processing of the mixture from the exhaust air, only approx. 2% . Compared to the conventional method, the method according to the invention simplifies and reduces the number of process stages by combining individual stages and eliminating other facilities. On the one hand, this is the elimination of the tempering level and thus the temperature silos. Furthermore, the material is only warmed up once and not cooled in between. The process is ongoing. The separation devices for processing the mixture that is discharged with the exhaust air are only to be designed for 15% instead of 100% of the plant throughput, as is the case with the conventional method. The flour content in the material to be extracted is only a maximum of 50% compared to today's methods. This may be expected to improve the operating conditions, for. B. in extraction, a better percolation can take place, which on the one hand leads to a higher possible throughput of the plant and on the other hand to better drainage of the scrap. The cleaning of the oil from its scrap particles is also simplified. The air volumes are largely recirculated and only small amounts of exhaust air are released into the environment. The amount of exhaust air released to the environment in the conventional process by drying and cooling in the shaft dryer and by the shell separation is more than twice as large. In addition, the air contains a larger amount of dust, since the amount of flour on the raw gas side is over 5%, in contrast to 1% in the process of the plant throughput according to the invention. The higher dust content on the raw gas side inevitably leads to the same type of dedusting a higher dust content on the clean gas side. The total emission of the conventional system is consequently several times higher than the emission of the method according to the invention. Even if the dedusting rate that can be achieved by the higher exposure to the cyclones is twice as good, it is still five times higher. It contains the previously necessary conditioning by reheating the material for flocculation. In the method according to the invention, the removal of moisture can be regulated at least between 1% and 2%. In the conventional method, moisture regulation is only possible within very narrow limits and is inevitably at least 2%; this makes the method according to the invention much more flexible. Drying in a fluidized bed is much more economical and leads to a much more evenly warmed and therefore more uniform product. The degree of demolding in the method according to the invention is at least equally good. In the method according to the invention there is less loss of good product on the shell side. In the method according to the invention, germs can be separated and possibly used further in the process or can be eliminated from it. Processing the material when it is warm results in a longer service life of the corrugated roller mill.

The so-called normal meal can also be produced from the soybeans on the basis of the information provided.

The beans are quickly warmed up in the first fluidized bed 1 and fed directly into the second fluidized bed 2. The two fluidized beds are shown separately in the diagram, but can also, and usually are, combined in an apparatus separated by partitions. The beans are kept warm in the second fluidized bed 2 and then they are guided via line 28 to break at the roller mill 23. In this process, in which the whole, unshelled soybeans are processed, the so-called normal meal with a protein content of about 44% is obtained after the subsequent flocculation on the flocculation apparatus 24 and the extraction, since the bean shells are included.

In this process, too, similar energetic and technological advantages are achieved as in the process described above, in which the high-quality soybean meal with a protein content of approx. 49-50% is obtained.

Claims (8)

1. Processing of soya beans with fracture (in 23) for flocculation (in 24) prior to extraction (after 38) in the method to obtain soya oil and soya meal, characterized by the following immediately successive and continuously running process steps:

a) Uniform heating up of all the soya beans in a fluidized bed (1) by means of a hot current of air during a brief period of dwell avoiding a heat diffusion to the interior of the seed, to a temperature at which the hulls become brittle and detach themselves from the seeds;

b) mechanical breaktdown of the heated up soya beans in a corrugated roll mill (3) and a hammer mill (4) connected thereafter for the separation of the hull parts from the heated seeds and exposing the material into hull parts, germ- and seed parts;

c) sifting (at 5, 6) of the exposed material by means of a hot current of air into coarser seed parts and into a separated mixture of hull parts, germs, fine and flour seed parts;

d) uniform heating through of the sifted coarser seed parts in a second fluidized bed (2);

e) fracture (in 23) of the heated coarser seed parts in their heated through, conditioned state, and directing the fractured material for flocculation (in 24) and subsequent extraction (after 38);

f) sifting (in 17) of the mixture of hull parts, germs, fine and flour parts, to recover the germs and fine and flour parts and passing (in 33) at least the fine and flour parts thereof to the flow (in 36) of the heated-through, coarser seed parts.

2. Method according to Claim 1, characterized in that the sifting (at 5, 6) of the exposed material is carried out by means of the current of exhaust air from the second fluidized bed (2).

3. Method according to Claim 2, characterized in that the exhaust air pipes of the second fluidized bed (2) are constructed as sifters (5,6).

4. Method according to Claim 1, characterized in that from the sifted hull parts, germs, fine and flour parts, the hull and flour parts are separated and the germs and fine parts (in 34) are passed to the flow (in 36) of the heated-through coarser parts prior to fracture (23).

5. Method according to Claim 4, characterized in that after separation of the germs and fine parts, the germs are separated therefrom (in 22) and are eliminated from the process (in 35).

6. Method according to Claim 4, characterized in that after the separation of the hull parts and flour parts, the hull parts are eliminated from the process (at 31), the flour parts (in 32, 49), however, are passed to the flow of the coarser seed parts prior to flocculation (in 24) or prior to extraction (after 38).

7. Method according to Claim 1, characterized in that the hot air required for the fluidizing of the fluidized beds (1, 2) is carried in a circuit (in 42, 43, 46), to which circulating amount in each case only such a quantity of fresh air is added (in 47) as is necessary to replace the quantity of air to be removed from the process with the humidity extracted from the material during processing.

8. Method according to Claim 1, characterized in that the supply of heat to the material in the fluidized bed takes place by means of heat exchangers incorporated in the respective fluidized bed.

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