WO2000021387A1

WO2000021387A1 - A conditioner for flour substances

Info

Publication number: WO2000021387A1
Application number: PCT/DK1999/000509
Authority: WO
Inventors: Thomas Kniep JØRGENSEN
Original assignee: Sprout Matador AS
Current assignee: Sprout Matador AS
Priority date: 1998-09-28
Filing date: 1999-09-28
Publication date: 2000-04-20
Anticipated expiration: 2001-03-28
Also published as: AU5849999A

Abstract

For pre-treatment of starch holding flour mass to be extruded it is known to use a conditioner in the form of processing cylinder with a rotating mixing and agitating roller having projecting blade members, which additionally serve to convey the mass from the inlet end to the outlet end of the cylinder and to enable an effective treatment of the mass with steam, upon the flour being admixed with water. According to the invention it has been found that the efficiency of the treatment can be improved considerably by the following combination of features: 1) The cylinder being of the type provided with two or more rollers; 2) The cylinder being constructed in a pressure-resistant manner and supplied with hot steam; and 3) The rollers being driven by a speed of rotation of 150-250 rpm.

Description

A CONDITIONER FOR FLOUR SUBSTANCES

The present invention concerns a conditioner for pre-processing of starchy meal masses which are to be formed by further processing, i.e. by extrusion, expansion or pellet pressing, of the kind which consists of a mixing and agitati- on chamber with supply means for steam and possibly for diverse liquids such as water and oil. The conditioning applies especially to a thermally-conditioned agglutination or gela- tination of the content of starch in the mass, whereby the consistency of the mass is influenced in such a manner that the mass can subsequently by extruded etc. with considerably reduced mechanical effect and increased capacity. Such a conditioning can also be advantageous with regard to the product quality and nutritional value of the end product. As examples of relevant products can be mentioned certain breakfast cere- als, snack-food, pet food and feed stuff pellets, including fish foods.

With the known technique in this field, use is made of feed-through equipment with longitudinal rotation shafts which support extending blade parts for mixing, agitation and the forward transport of the material. With the associated introduction of steam, it is particularly important that the material is agitated so that the steam gains direct access to the widest possible extent to the particles of starch in the mass, which in itself is heat insulating. Various attempts have been made to increase the efficiency of the relevant types of apparatus, which basically appear as single-shaft units with the possibility of the supply of steam at 100°, i.e. at atmospheric pressure. It is thus known that the efficiency can be improved with a double- shafted configuration of the apparatus, in that this gives rise to an improved agitation effect as well as an extended processing space and herewith a longer retention time for the material in apparatus of a given length, so that the hot steam is given better possibility of influencing the whole content of starch in the mass.

According to other measures, in connection with said basic configuration it has been proposed that this be arranged in a pressure-tight manner so that operations can be carried out with a supply of hot steam at a temperature appreciably in excess of 100°, which will further the desired process to a considerable degree.

With reference to US-A-4 , 540, 592 , it has also been proposed that a certain conditioning can be effected in direct association with an extrusion process in connection with a long, double-shafted extrusion worm, i.e. by dividing the extent of the worm into a number of zones in which various process conditions can be created, e.g. by pressure build-up against the effect of reversing worm sections and supplying heat by using electrical heating elements, friction heating and steam, and where it is mentioned, however, that the latter is not necessary. While such equipment may well thus be configured with an integrated pre-conditioning section, it will nevertheless also have the character of an extruder, i.e. built up with a worm which requires a great deal of work in its manufacture and is thus expensive, and here more-or- less as a helical pump/compactor by co-operation between two parallel worms, which is extra costly. The mixing and agita- tion effect in an ordinary "conditioner" is quite important, and a corresponding effective influence will be expensive to achieve in connection with worm conveyors which must be driven with a view to the building up of pressure.

With the invention it is endeavoured to provide an improved conditioner of precisely the ordinary type, i.e. whereby the extending blade parts on the rotor shaft bring about a transport effect on the material, but not with any significant build up of pressure as a consequence; this is left to the subsequent extrusion unit or other processing machine for production of expandates .

With the invention it has been found that a significant improvement of the efficiency of the ordinary conditi- oner can be achieved by a combination of three different arrangements :

1) the use of a double or multi-shafted rotor system,

2) pressurisation of the rotor chamber by the introduction of hot steam at a temperature of 105-108°C, and 3) use of a drive system for rotation of the rotors at a speed of more than 100 rpm, preferably 150-250 rpm. Points 1) and 2) will thus be a combination of already- known individual arrangements, while in connection with point 3) it must be mentioned that there has not hitherto been any report concerning the use of speeds of more than 60 rpm in ordinary conditioners, regardless of whether these appear as single or double-shafted "conditioners" or as single-shafted, steam pressurised "pressure conditioners" . In the above-mentioned US-A-4, 540,592, it is disclosed that the speed of the relevant worms is 200-300 rpm, but it is also disclosed that this is less than when use is made of a conventional single worm, and thus there is no basis for a relevant comparison. The essential point in the present context is that by a marked increase in the number of revolutions in a conditioner which is both multi- shafted and pressurised, a significant improvement can be achieved in the processing result without deviation from the fundamental simple conditioner construction, and thus also without sub- stantially increased operation costs for the supply of heat by power-demanding friction or use of external sources of heat such as electrical heating elements, apart from the steam supply. With the double or multi-shafted configuration of the conditioner, the advantage is achieved from the processing point of view that the time for which the material is retained in the apparatus can be extended for apparatus of a given length, e.g. to a retention time of 15-320 seconds, and since the temperature is so high, provided by the introduction of steam heated to a temperature of up to 180°, typically of approx. 130°, there is thus achieved a significant improvement in the processing result . Trials which have been carried out would indicate that a significant improvement is not possible unless use is made of all three of the above- mentioned combination arrangements 1) - 3) .

In the following, the invention is explained in more detail with reference to the drawing, in which fig. 1 is a side section view of an extrusion plant with associated conditioner, and fig. 2 is a perspective view of the conditioner's rotor system.

The plant shown in fig. 1 comprises a feed hopper 2 which via a feed-worm 4 in a housing 6 stands in connection with the input end of a conditioner 8 consisting of an elongated housing 10 for a rotor shaft 12 with extending, inclined blades 14. The rotor 12, 14 is driven by a motor 16 which does not need to be particularly powerful. During the rotation, the material introduced is conveyed forwards towards an outlet 18 at the front end of the housing 10 while being vigorously mixed and agitated. Water can be added to the introduced dry-matter at an inlet 20, or at several such inlets along the rotor housing. The angle at which the blades 14 are set is preferably adjustable, whereby the feed-through time is adjustable. An angle of inclination of approx. 20° will often be suitable. The outlet 18 leads to an inlet on a machine unit 20 for extrusion of the conditioned material, shown here as a worm extruder with a powerful drive motor 22. The material discharged at 24 can be cut off in pellet form. So far de- scribed, the plant shown is completely conventional. As discussed, with the invention there is here introduced a combination of modifications, i.e.:

1) construction of the conditioner in double or multi- shafted configurations, c.f. the example shown in fig. 1,

2) construction of the conditioner housing in pressure- resistant configuration and arrangement of the material supply 4, 6 as pressure-resistant sluice,

3) addition of one or more inlets 26 for hot steam in the range of 105-180°C, and

4) changing of the motor drive for the rotors 12, 14 for rotation of these at a speed of at least 100 rpm, preferably 150-250 rpm.

The conditioner shown in fig. 2 has two rotor shafts 12 which rotate in the same direction, and which have extending blades 14 which at the centre engage between one another without any mutual contact arising with the oppositely-directed movements. In this centre area there will thus arise an intense mixing/agitation/kneading of the material. In this dou- ble-shafted plant, at half-filling the material will appear with a relatively large surface which is open to influence from the introduced heated steam, and to some degree the steam will also be whipped-down or kneaded into the material. According to the invention, it is on this basis that a spe- cial effect will be achieved by the steam pressurisation of precisely double or multi-shafted apparatus

The relatively high rotation speed of the shafts 12, 14 will also contribute towards good contact between the steam and all parts of the material during its transport through the apparatus, so that the desired processing effect can be brought to an end within a few minutes, generally within 15-320 seconds when use is made of an apparatus of reasonably short length, e.g. 300 cm. It has been ascertained that improved results will not normally be achieved by a further extension of the time for which the material is retained in the apparatus. Correspondingly, it applies that apparatus which is known beforehand to be required for use only for tasks where the required retention time is less than e.g. 45 seconds, will be able to be configured with shortened length and herewith in a significantly cheaper manner.

It will be understood that precisely this combination of a processing result of high quality and a corresponding apparatus with relatively low purchase price and operation costs will appear as a result of the special combination according to the invention.

The temperature is of great importance for achieving a good result. With comparative trials with one and the same mass consisting of 73% wheat flour

20% soya 5% oil

2% other ingredients the following values have been measured: Test no. Temp. Pressure Time H₂0 Agglutination

C° bar sees. % %

1 100 0/0 90 21 14

2 122 1/15 90 22 21

3 137 2/30 90 22 43

4 146 3/45 90 24 75

With corresponding comparative measurements, the following values have been found: Single -shafted Single-shafted Double-shafted Double-shafted atmospheric pressurised atmospheric pressurised pressure pressure

Feed-through time 55 sees. 55 sees. 118 sees. 120 sees. Gelation 35% 45% 55% 70%

Claims

C L A I S

1. Conditioner for pre-processing of starchy meal masses which are to be formed by further processing, i.e. by extrusion or the like, and of the kind which consists of a processing cylinder with rotating mixing and agitation shafts with extending blades which also have a transporting effect, said cylinder having a material inlet at the one end and a material outlet at the opposite end, and an inlet opening for water, c h a r a c t e r i z e d by the combination of,

1) that the processing cylinder is of the type which is configured with two or more rotating shafts,

2) that the processing cylinder is configured in a pressure- tight and pressure-resisting manner and has one or more inlet openings for hot steam, and

3) that a motor drive for the rotating shafts is arranged to drive these at a speed of at least 100 rpm, preferably 150-250 rpm.

2. Method for the operation of a conditioner according to claim 1, c h a r a c t e r i z e d in that the double- shafted or multi-shafted conditioner is driven in pressurised condition under the influence of hot steam at a temperature of between 100 and 180°, and that the conditioner's rotors are driven at a speed of more than 100 rpm, preferably at 150-250 rpm.