RU2774441C1 - Method and apparatus for splitting starch - Google Patents

Abstract

FIELD: foodstuffs.

SUBSTANCE: invention relates to the starch processing industry. Method for splitting starch involves preparation of an aqueous suspension of powdered starch, introduction of the suspension into a cooker (4), processing of the suspension in the cooker (4) with water vapour. The suspension is therein subjected to mechanical impact of shear forces caused by a rotor (42) with a scattering disk (44) with ribs (45). The water vapour is therein supplied from a hollow ring (70) located below the rotor, wherein holes are provided for releasing water vapour, directed towards the rotor (42), and/or from a hollow displacement chamber (60) located in the cooker (4) through at least one hole (63) for releasing water vapour into the area of the rotor (42) in order to perform thermomechanical splitting. The starch, at least partially transformed into paste, is then removed from the cooker (4), and the paste is diluted, if necessary. Also proposed is an apparatus in the form of a cooker for implementing the proposed method.

EFFECT: invention is aimed at producing starch split to the desired degree by means of a physical processing method.

31 cl, 9 dwg, 1 tbl, 21 ex

Description

The invention relates to a method for the splitting of starch with the features indicated in the preamble of paragraph 1 of the claims.

In addition, the invention relates to a device that can be used in the implementation of the proposed method as a digester and which has the features indicated in the preamble of paragraph 16.

Known methods of processing starch by splitting starch. In the method of enzymatic digestion of starch, native starch powder is fed from a soft container ("BigBag") or from a hopper to a suspension unit, where starch powder is introduced into water and a suspension (suspension) is formed with a solids content of up to 35%. From the slurry station, the resulting starch slurry is pumped to the digester, wherein the degrading enzyme (amylase) is added to the slurry station either before or after a pump that pumps the slurry from the slurry station to the digester. Typically, when the slurry enters the digester, the slurry is heated to a temperature of 85°C-95°C by steam injection, and splitting is already taking place.

Static mixers or other internal devices may be provided in the feed line to the digester to prevent slurry slippage and/or to make the slurry feed more uniform.

In known methods, the residence time in the digester to achieve the desired degree of splitting is set by volume buffering. In various devices for implementing known methods for the enzymatic breakdown of starch (native starch), digesters are equipped with agitators and, if necessary, disc mixers to speed up the process.

The paste obtained from the breakdown of starch is withdrawn from the digester by means of a pump and, if enzymes were used, passed through an inactivation site. Typically, the site of inactivation is a tubular reactor, in which the paste is first heated by introducing steam to a temperature of 120°C-135°C. The inactivation time is controlled by the volume of the pipe and/or the power of the pump.

After the breakdown of the starch has been stopped by enzyme inactivation, the paste is diluted and then sent to storage.

It is also known to use, instead of the digester, a labyrinth tube installed after the introduction of steam, whereby a residence time sufficient for the desired degree of splitting can be achieved, and due to the sharp edges, an additional shear of the substance in the suspension is created.

In known methods, the digester, if suitably large, can also be used in batch mode.

The disadvantage of the known methods is that rather large installations are required, or only low productivity can be achieved.

In one known method for the digestion of cationic starch, cationic starch powder from a soft container (BigBags) or hopper is fed into a suspension unit and the powder is introduced into water, thereby forming a suspension (slurry) with a solids content of up to 15%. The starch slurry is pumped into a tubular digester.

In the known cationic starch digestion process, the tubular cooker is a tubular reactor in which the starch slurry is first heated to a temperature of 115°C-135°C by supplying steam. The residence time is controlled by the volume of the tubular reactor and/or the power of the pump. After the cooking process, dilution is most often carried out, and then the resulting paste is sent for storage.

When splitting cationic starch, it is also possible to use a labyrinth tube instead of a tubular cooker after the introduction of steam.

It is also known to replace the tubular digester with a digester which, if sufficiently large, can also be used in batch operation.

Apparatus and methods for the breakdown of starch are known from US 3371018 A, WO 2018/011401 A1 and CH 513980 A.

From US 3371018 A it is known to convert starch into a furnish for the paper industry using bacterial alpha-amylase (b-amylase) in water under the action of heat (225-350°F/107-177°C). A vertical reaction column is used, in which a rotor with propeller surfaces rotates. Horizontal and vertical reflective surfaces are provided. A stirring effect with an upward flow should be created. US 3371018 A relates to the continuous conversion of starch with bacterial amylases to obtain a product that can be used in the paper industry for paper sizing. A vertical reactor with baffles and a stirrer is used to create a turbulent flow. To inactivate the added amylase, it is necessary to inject steam, leaving open the place where the steam is introduced.

WO 2018/011401 A1 describes the enzymatic hydrolysis of starch. The starch to be hydrolyzed to which the enzyme has been added will be sheared during mixing. WO 2018/011401 A1 describes a method for producing hydrolyzed starch using an amylase-type enzyme. The required water may be supplied in the form of steam (direct steam injection), with the steam supplied by "suitable means". It is mentioned that during the hydrolysis, temperature setting can be performed simultaneously with "shear mixing".

According to DE 10/2007 011409 A1, upon receipt of an enzymatically decomposed starch paste, a starch paste is fed into a reaction vessel in which a turbulent flow is created. Starch paste is formed in the Venturi type gelatinization module as a result of the action of enzymes and steam heating. DE 10/2007 011409 A1 describes a process for producing a starch paste from enzymatically degraded starch. In this case, it is necessary to achieve good mixing of the enzyme with the starch paste in the reaction vessel due to the turbulent flow. The starch paste is fed into or produced in the reaction vessel. By means of a stirrer, a controlled turbulent state can be created in the reaction vessel. In DE 10/2007 011409 A1, gelatinization is carried out in a gelatinization module that does not include a stirrer, to which steam is supplied. It is not steam that is fed into the reaction vessel, but a starch paste.

US 2010/159104 A1 describes the preparation of a colloidal solution of starch in a cooking chamber at a temperature between 120°C and 180°C. Paragraph [0021] mentions "the breaking of intermolecular hydrogen bonds and the dissolution of macromolecules". Paragraph [0039] mentions the introduction of steam under pressure into the colloidal solution of starch in the second stage (see also paragraph [0066]). Paragraph [0057] mentions that a mixing device must be used. Paragraphs [0068] and [0069] state that the introduction of steam "at the bottom of the chamber" should be avoided in order to avoid clogging of the steam distribution ring. In the device shown in figure 3 in US 2010/159104 A1, steam is supplied once through a pipeline to the double wall of the digester and once into the colloidal solution (paragraphs [0101] and [0102]). This also applies to boilers shown in other figures in US 2010/159104 A1. In US 2010/159104 A1 there is no indication of the supply of steam to the area of the mixing tool, which is not described in detail.

According to US 3308037 A, starch "decomposition products" are formed, which can be used for gelatinization or enzymatic hydrolysis. In US 3308037 And it is proposed to supply steam to the device through a pipeline. In FIG. 1, the device supplies steam to the boiler from below, and in FIG. 2 on top. According to US 3308037 A stirrers are not provided in the boilers.

A publication by Guglielmo Santi proposes a mechanically agitated bioreactor into which saturated steam must be introduced. Steam is supplied through a pipeline that opens from below to the bottom of the reactor. The stirrer ends at some distance above the bottom of the reactor.

According to CH 513980 A, the starch slurry is subjected to an enzymatic digestion, wherein the starch slurry becomes a paste by heating to 140-150°C. The resulting "paste" is cooled, combined with an enzyme and decomposed to obtain a maltose syrup. A reaction vessel in the form of a rapid mixer with a rotor and baffles should be used. Accordingly, CH 513980 A describes a process in which starch is gelatinized at 120-160° C. and digested with an enzyme to obtain a maltose syrup. The starch slurry is heated by direct or indirect introduction of steam. A plant is shown for carrying out the method with stirring and direct and indirect heating. The mixer is equipped with blades. Steam is supplied to the unit from below in the area of the diffuser. Above the diffuser are the guide plates, and above the guide plates are the agitator. The agitator shown in CH 513980 A is not suitable for generating shear forces, so shear forces are not mentioned.

The object of the invention is to provide an improved and more economical process for the digestion of starch and to provide a digester suitable for use in the process.

According to the invention, this problem is solved by means of a method with features according to paragraph 1 and a device with features according to paragraph 17 of the claims.

The advantage of the process according to the invention is that the heating of the starch slurry takes place directly in the digester by supplying steam to the digester and shear forces are applied to the slurry, so that more favorable process control is possible.

In this case, it is preferable, in particular, to heat the suspension in the digester to a gelatinization temperature, which is from 85°C to 135°C.

Preferred and advantageous embodiments of the method according to the invention and the device according to the invention are the subject matter of the dependent claims.

The method and apparatus according to the invention improves the known digestion methods, namely the enzymatic digestion of starch, the oxidative digestion of starch and the decomposition of starch by means of thermomechanical digestion.

The advantage of the thermomechanical digestion according to the invention is that, in contrast to the oxidative and enzymatic breakdown of starch to produce a paste, no chemical additives are required, so only a slight change in molecular weight occurs. This, in turn, is advantageous in that the thermomechanically treated native starch has a higher adhesive strength, so that higher paper strength can be achieved. In addition, due to the small change in molecular weight, a higher yield of starch is achieved.

A further advantage of the invention is that no inactivation is required in the thermomechanical breakdown of starch according to the invention. By "thermomechanical breakdown of starch" is meant the processing of starch by applying heat and shear to form a paste.

The advantages of the device according to the invention for carrying out the method according to the invention are that it has a compact design, so that low volumes of circulating medium and short residence times are achieved. Another advantage is that process parameters such as speed, temperature, stator/rotor design provide good controllability.

Finally, highly concentrated starch suspensions can be processed in the device according to the invention. A further advantage of the device according to the invention is that a direct metered supply of steam to the device is provided, and the enzyme, if used, can be added after the device (digestor). The apparatus according to the invention provides significant advantages over conventional starch digesters (cylindrical digester, converter, etc.) due to the additional input of mechanical energy (shear forces).

The fact that the device according to the invention uses a rotor in combination with a stator and simultaneously introduces steam leads to fast and well controlled starch gelatinization due to shear forces acting on the starch slurry. This in turn means that the duration of the process can be reduced. Another advantage is that many types of starch (eg corn, wheat, potato) can be processed.

When using an increased reaction temperature (cooking temperature) in the device according to the invention, the viscosity of the obtained starch paste is reduced and a more stable mode of operation is achieved.

Under the action of mechanical shear, the size of large colloidal starch particles decreases, which leads to a decrease in the viscosity of the resulting starch paste.

By choosing the shape of the rotor in the device according to the invention (height and diameter of the rotor, speed), it is possible to purposefully set the viscosity of the resulting starch paste .

One advantage of the starch digestion process according to the invention is that at least one enzyme can be added to the digest resulting from the digestion, so that after enzymatic digestion and thereby achieving the desired low viscosity of the paste, a product can be obtained that can be used, for example, in paper industry.

If an enzyme is used in the process according to the invention, it is rendered inactive either during or after the process by inactivation.

In one possible embodiment, the process according to the invention may be characterized in that the water vapor exits the hollow displacement chamber, which is located in the digester, through at least one steam outlet into the region of the rotor.

In one possible embodiment, the process according to the invention may be characterized in that the starch-containing slurry in the digester is heated in step c) to a temperature of 85° C.-135° C. by introducing steam.

In one possible embodiment, the method according to the invention may differ in that the duration of step c) is from 1 to 5 hours.

In one possible embodiment, the method according to the invention may differ in that in step a) a suspension is obtained with a starch powder content as a solid phase of not more than 35-45%.

In one possible embodiment, the method according to the invention may be characterized in that the suspension before step b) is heated to a temperature of 85°C-95°C.

In one possible embodiment, the process according to the invention may differ in that, in step c), the degree of starch degradation is set by selecting the rotation speed at which the slurry is stirred in the digester.

In one possible embodiment, the process according to the invention may differ in that, in step c), the degree of starch degradation is determined by selecting the flow rate of the slurry.

In one possible embodiment, the process according to the invention may differ in that, in step c), the degree of starch degradation is set by selecting the temperature of the slurry.

In one possible embodiment, the method according to the invention may differ in that after step d) the enzyme is inactivated.

In one possible embodiment, the method according to the invention may differ in that the inactivation of the enzyme is carried out by heating the paste to a temperature of 120°C-135°C.

In one possible embodiment, the method according to the invention may be characterized in that the temperature is raised by introducing steam.

In one possible embodiment, the process according to the invention may be characterized in that the flow rate of the slurry through the digester in step c) is controlled by restricting the flow of the slurry through the digester and/or by statically agitating the slurry in or after the digester.

In one possible embodiment, the process according to the invention may differ in that in step a) a cationic starch powder is used to obtain the suspension.

In one possible embodiment, the method according to the invention may differ in that in step a) native starch powder is used to obtain the suspension.

In one possible embodiment, the device according to the invention can be characterized in that the steam supply line terminates in a hollow displacement chamber and in that the displacement chamber has at least one steam outlet on its opposite side of the line mouth and adjacent to the rotor.

In one possible embodiment, the device according to the invention may be characterized in that there are outlets distributed around the annular end surface of the displacement chamber facing the rotor.

In one possible embodiment, the device according to the invention may be characterized in that the steam supply line terminates in a hollow ring with at least one steam outlet.

In one possible embodiment, the device according to the invention may be characterized in that the ring is located on the opposite side of the rotor from the displacement chamber.

In one possible embodiment, the device according to the invention may be characterized in that the outlet is located on the wall of the ring facing the rotor.

In one possible embodiment, the device according to the invention may be characterized in that the ring comprises a plurality of outlets distributed along its length.

In one possible embodiment, the device according to the invention may be characterized in that the stator laminations are spaced from the displacement chamber and reach the inner surface of the boiler.

In one possible embodiment, the device according to the invention may be characterized in that the rotor has ribs on at least one of its sides.

In one possible embodiment, the device according to the invention can be characterized in that the hole in the displacement chamber, which is coaxial to the rotor shaft, has the shape of a funnel, with the enlarged section of the hole facing towards the boiler cover.

In one possible embodiment, the device according to the invention may be characterized in that the axis of the line is coaxial with the axis of the annular displacement chamber and directed towards the rotor.

In one possible embodiment, the device according to the invention may be characterized in that the ribs on the scattering disk increase in height from the inside out.

In one possible embodiment, the device according to the invention may be characterized in that the ribs are mounted obliquely to the radial planes passing through the rotor shaft.

In one possible embodiment, the device according to the invention may be characterized in that the rotor protrudes through the bottom of the boiler into the interior of the boiler.

In one possible embodiment, the device according to the invention may be characterized in that a constriction is provided in the region of the mouth of the line, acting as a diffuser.

In one possible embodiment, the device according to the invention may be characterized in that the constriction is formed by an annular protrusion, in particular an annular protrusion with a triangular cross section.

Other features and features of the invention appear from the following description with reference to the drawings, which show by way of example known plants and methods, methods and plants according to the invention, as well as a digester suitable for use in accordance with the invention. On the drawings:

fig. one: scheme of a well-known installation for the enzymatic cleavage of native starch, fig. 2: scheme of a well-known installation for the splitting of cationic starch, fig. 3: installation for the implementation of the (continuous) method of enzymatic cleavage of native starch, fig. four: installation for the implementation of the proposed invention, the method of splitting cationic starch, fig. 5: block diagram of a known method for the enzymatic breakdown of starch, fig. 6: block diagram of a known process for the breakdown of cationic starch, fig. 7: block diagram of the method proposed by the invention for the splitting of cationic starch, fig. eight: a partial sectional view of two embodiments of a digester that can be used in carrying out the method according to the invention, and fig. 9: a plant suitable for carrying out the method according to the invention.

The known process for the enzymatic digestion of starch, which can be carried out continuously in the plant of FIG. 1 in accordance with the block diagram of FIG. 5 can be described as follows.

As initial components are used:

- native starch powder,

- water,

- steam and

- enzyme (amylase).

The starch powder is stored in soft containers (BigBags) 1 or hopper 2. From this stock, the starch powder is fed to the suspension unit 3. In the specified unit 3, the starch powder is introduced into the water and a suspension (suspension) is formed with a solids content of up to 35%. From there, the slurry (starch slurry) is pumped into the digester 4 using pump 5. Enzymes can be dosed from the storage tank 6 to the suspension unit 3 before or after pump 5. In most installations, the suspension is brought to the gelatinization temperature before being introduced into the digester 4 ( 85°C-95°C) by steam injection 9.

In addition, static mixers or other internal devices can be installed in the feed line to the digester 4 to prevent slurry slippage and make the feed more uniform. Actually in the digester 4 by volume buffering set the residence time (8-20 minutes), necessary to achieve the desired degree of splitting. Agitators and/or disc mixers are built into the digester 4 to speed up the splitting process by applying shear forces to the slurry in the digester 4.

Using the pump 7, the paste is continuously pumped out of the digester 4 and pumped through the inactivation section 8. The inactivation section 8 is a tubular reactor in which the paste is first heated up to 120° C.-135° C. by injection of steam 9, while the inactivation time can be adjusted through the volume of the pipe and/or the pump capacity. After stopping the splitting process, the resulting paste is diluted if necessary with water from line 15 and then sent to storage.

It is known that after injection of steam instead of the digester 4, it is possible to provide a labyrinth tube, in which, firstly, it is possible to achieve the required residence time, and secondly, to create an additional shear of the suspension due to sharp edges.

The digester, if sufficiently large, can also be used in batch mode. In this case, all technological steps are carried out, starting with the preparation of the suspension in the digester 4. The disadvantage is that relatively large installations are needed or, accordingly, only a small amount of raw material can be processed per unit of time.

In the known process for cooking cationic starch, which can be carried out in the apparatus shown in FIG. 2 and which can proceed according to the block diagram of FIG. 7, the procedure described below can be used.

As initial components are used:

- cationic starch powder,

- water and

- steam.

The starch powder is stored in soft containers (BigBags) or hopper 2. From this stock it is fed to the suspension unit 3. In the specified unit 3, the starch powder is introduced into the water and a suspension (suspension) is formed with a solids content of up to 15%. From there, the starch slurry is pumped into the tubular cooker 10.

The tube cooker 10 is a tube reactor in which the starch slurry is first heated to 115° C.-135° C. by introducing steam 9, while the residence time can be controlled through the tube volume and/or the pump capacity. After the cooking process, the resulting paste (decomposed starch) is diluted if necessary with water (water from line 15) and then sent to storage.

It is known that after the injection of steam 9, instead of the tubular cooker 10, it is possible to provide a labyrinth tube, in which, firstly, it is possible to achieve the required residence time, and secondly, to create an additional shear of the suspension due to sharp edges.

The tubular digester can be replaced by a digester 10. If it is suitably large, the digester 10 can also be used in intermittent operation. In this case, all technological steps are carried out, starting with the preparation of the suspension in the digester 10. The disadvantage is that relatively large installations are needed or, accordingly, only a small amount of raw material can be processed per unit of time.

The cationic starch digestion process according to the present invention can be carried out in the apparatus shown in FIG. 4, which uses the brewing vessel of FIG. 9, the method may be carried out in accordance with the flowchart shown in FIG. 8. More specifically, you can proceed as follows.

As initial components are used:

- cationic starch powder,

- water and

- steam.

The starch powder is stored in a soft container (BigBags) 1 or hopper 2. From this stock, the starch powder is fed to the suspension unit 3. In the specified unit 3, the powder is introduced into the water from line 11, and a suspension (suspension) is formed with a solids content of up to 35% . From there, the starch slurry is pumped into the digester 4 by pump 5.

Steam 9 is injected through line 13 directly into the digester 4, where the suspension is brought to the gelatinization temperature (85°C-135°C).

In addition, static mixers or other built-in components can be installed downstream to prevent the slurry from leaking through the digester 4 and/or to make the cooking process more uniform. In the boiler 4 the desired degree of splitting can be set by changing the speed, throughput and/or cooking temperature.

The resulting paste, if necessary, is diluted with water from line 15 and then sent to storage.

The device (digestor 4) which can be used to break down cationic starch in the process according to the invention may be of the construction shown in FIG. eight.

The device according to the invention, which is used as a digester 4, contains a container 40, which is closed on the upper side with a lid 41. From below, a rotor 42 protrudes into the container 40, which is installed in a carrier housing (not shown) located under the container 40.

The input of the rotor 42 into the container 40 is sealed with sliding sealing rings 43.

Rotor 42 is mounted in a bearing housing on rolling bearings (not shown).

In its part located in the lower region of the vessel 40, the rotor 42 has a scattering disk 44, which on its upper side bears ribs 45 arranged obliquely with respect to the radial direction. Thus, in one embodiment, the orientation of the ribs 45 relative to the direction of rotation of the rotor 42 is chosen so that the radially inner ends of the ribs 45 are further forward with respect to the direction of rotation than the radially outer ends of the ribs.

In a modified embodiment, the ribs 45 are oriented so that their radially outer ends are farther rearward relative to the direction of rotation than their radially inner ends.

In addition, the height of the ribs 45 may increase from the inside to the outside.

The ribs 45 on the upper side of the diffuser disc 44 are, for example, curved. The curved ribs 45 are aligned either so that the convex side of the ribs 45 faces forward with respect to the direction of rotation of the diffuser disc 44, or so that the convex side faces rearward with respect to the direction of rotation of the diffuser disc. 44.

Thus, the ribs 45 on the upper side of the diffusing disk 44 can be bent so that the concave side of the ribs 45 is directed forward or backward relative to the direction of rotation of the diffusing disk 44.

The ribs 45 on the upper side of the diffuser disk 44 may also be straight ribs.

The rotating rotor 42 provided in the brewing vessel 40 (digestor) with the diffusing disc 44 generates shear forces on the starch slurry introduced into the brewing vessel 40, which favors starch breakdown.

The rotor 42 has, for example, a diameter of 100 to 150 mm, preferably 130 mm, and a height including ribs 45 on the diffusing disk 44, for example 3 to 10 mm, in particular 5 to 7 mm. Rotor 42 is driven at a speed of, for example, 3000 to 5000 rpm. The number of revolutions of the rotor 42 is selected depending on its diameter in order to achieve the desired circumferential speed.

A propeller 46 with blades 47 is provided on the rotor 42 above the scatter disk 44, which creates a flow in the processed suspension towards the scatter disk 44. The propeller 46 is optional.

A line 50 coaxial with the rotor 42 ends in the cover 41, along which the suspension flows into the container 40.

On the inside of the lid 41 there is provided an inwardly facing conical protrusion 51, in the center of which the slurry supply line 50 terminates.

This arrangement of line 50 ensures that the slurry circulating in vessel 40 is optimally mixed with the new slurry fed into vessel 40.

By providing a constriction 52 acting as a diffuser at the end of the line 50 (terminating in the container 40) (formed by an annular projection with a triangular cross section), the aforementioned mixing of the supplied slurry with the slurry already in the container 40 and being processed is advantageously facilitated. .

Outflow lines (or at least one) are provided around the inlet line 50 to drain the treated slurry (decomposed starch).

The lid 41 is screwed to the container 40.

Inside the container 40, an annular displacement chamber 60 is provided, the inner opening of which is made in the shape close to a funnel. Between the outer surface of the displacement chamber 60 and the inner side of the wall of the container 40 is an annular channel in which the suspension after exiting the scattering disc 44 flows upward. Through the inner opening of the displacement chamber 60, the slurry flows, optionally supported by the propeller 45 of the rotor 42, downwards in the direction of the scattering disk 44.

In the exemplary embodiment shown, the upper end of the rotor 42 is covered by a streamlined lid that is attached to the rotor 52 with an Allen screw.

On the outer side of the displacement chamber 60, stator blades 61 are provided in the form of guide vanes, which cover the annular channel (gap) between the outer side of the displacement chamber 60 and the inner side of the wall of the container 40 (in particular, in its lower part), that is, with their free edges, they adjoin to the inner side of the vessel wall 40.

In order to hold the displacement chamber 60 inside the container, fixing screws can be provided.

In the embodiment of the digester 4 shown on the left in FIG. 8, the displacement chamber 60 is hollow and is filled with steam along a line 62 passing through the cover 41 of the body 40 of the digester 4. Line 62 ends in the upper end surface of the hollow chamber 60 displacement. The displacement chamber 60 has on its underside a plurality of outlet openings 63 distributed around the inner opening of the displacement chamber 60 so that the steam introduced via line 62 into the interior of the displacement chamber 60 can exit inside the container 40 in the region of the rotor 42, in particular in the region of its scattering disk 44.

In the embodiment shown in FIG. 8 on the right, a hollow ring 70 (annular diffuser) is provided in which openings are provided for discharging water vapor. As shown on the right in FIG. 8, the ring 70 is located on the opposite side of the diffusing disc 44 of the rotor 40 from the displacement chamber 60, with the outlet openings in the ring 70 pointing upwards, i. in the direction of the displacement chamber 60 . For clarity, the line along which steam (steam) is supplied to ring 70 in FIG. 9 is not shown.

For some applications, it may be advantageous if the supply of steam into the vessel 40 of the digester 4 occurs both through the hollow displacement chamber 60 and through the ring 70.

In the shown in FIG. In the starch processing plant (starch digestion), starch is made into a paste without adding enzyme in a starch dispersing kettle (eg digester 4). After gelatinization, the enzyme is added to the paste at the outlet of the starch cooker and homogeneously distributed by means of a static mixer. After a residence time, depending on the respective tube design, the enzyme is inactivated by raising the temperature. At the same time, the advantage is that

a) the starch is gelatinized in the dispersion kettle (eg digester 4) with almost no reduction in molecular weight, and

b) Thanks to the post-treatment with enzymes, the properties of the starch, such as viscosity and degree of splitting, can be individually adjusted according to customer requirements.

In addition, the contribution of shear energy to the starch dispersing apparatus (eg digester 4) can also be used to influence further use.

In FIG. 9 shows a plant in which the above-described embodiment of the method according to the invention can be carried out.

The installation shown in Fig. 9 includes a digester 4 (starch dispersing digester) which may be constructed like the digester 4 shown in FIG. 8. A line 20 terminates in the digester 4, through which the enzyme is supplied by a pump 22 from an enzyme storage tank 21 (not according to the invention).

Through the next line 23, starch is supplied to the digester 4 by means of a pump 24.

Through line 25, steam (water) is introduced into the digester 4.

The starch, boiled into a paste, is removed from the digester 4 through line 26. Before the static mixer 27, enzyme is added (using a pump 29) from the storage tank 28.

Water can be supplied to the lower part of the digester 4 via line 30 by means of a pump 31 as seal water for the sliding ring seal 43.

The following are examples of the method according to the invention.

Example 1

Wheat starch (Collamyl 7411) with a moisture content of 13% was mixed with water, obtaining a suspension with a wheat starch content of 30 wt.%. The resulting slurry was made into a paste at a rate of 750 l/h at a cooking temperature of 115°C in the apparatus shown in FIG. 9. Immediately after the device of FIG. 9, Warozym A152 enzyme V was added before the static mixer at a constant flow rate of 4.28 l/h. The rotor 42 used in the device of FIG. 9 had a height of 7 mm.

At a rotor speed of 4200 rpm, a rotor diameter of 42 130 mm and a current consumption of the motor driving the rotor of 42.35 amperes, a paste with a viscosity of 12500 mPa⋅s was obtained.

Example 2

The treatment was carried out as described in example 1, with the rotor speed increased to 4400 rpm, and the current consumption of the motor was 41 amperes. A paste with a viscosity of 9700 mPa⋅s was obtained.

Example 3

The treatment was carried out as in example 1, with the rotation speed of the rotor was increased to 4400 rpm, and the enzyme was added in an amount of 2.14 l/h. A paste was obtained with a viscosity of 9500 mPa.s.

Example 4

The treatment was carried out as described in example 3, with the addition of the enzyme was increased to 4.28 l/h. A paste with a viscosity of 7800 mPa⋅s was obtained.

Example 5

The treatment was carried out as described in example 3, with the addition of the enzyme was increased to 8.56 l/h. A paste was obtained with a viscosity of 7400 mPa.s.

Example 6

The treatment was carried out as described in example 1, using a rotor speed of 4400 rpm and a rotor 42 with a diameter of 130 mm. The reaction temperature was set at 100° C., and the current consumption of the motor driving the rotor 42 was 38 amps. The resulting paste had a viscosity of 13950 mPa.s.

Example 7

Processing was carried out as described in example 6, and the reaction temperature was set to 115°C. The current consumed by the motor was 35 amperes. The paste had a viscosity of 9700 mPa.s.

Example 8

The treatment was carried out as described in example 1, with the reaction temperature being 115° C. and the rotor 42 running at 4400 rpm. Rotor 42 had a diameter of 130 mm and a height of 5 mm. The current consumed by the motor was 37 amperes. A paste viscosity of 10700 mPa⋅s was obtained.

Example 9

The treatment was carried out as described in example 8, using a rotor 42 with a height of 7 mm, and the current consumed by the motor was 41 amperes. As a result, a paste with a viscosity of 9700 mPa⋅s was obtained.

Example 10

Potato starch (Collamyl 9100) with a moisture content of 13% was introduced into water to obtain a suspension with 20 wt.% potato starch. The resulting slurry was made into a paste at a rate of 750 l/h at 115°C in the apparatus shown in FIG. 9. The enzyme from Example 1 was added after the apparatus of FIG. 9, but before the static mixer.

The suspension exiting the device of FIG. 9 was passed through a tubular reactor with a reaction length of 7500 mm. As a result, a paste was obtained with a viscosity of 1660 mPa.s, and the resulting starch paste was transparent and optimally dissolved.

Example 11

The treatment was carried out as in example 10, but under conditions where the reaction length of the tubular reactor was 10,000 mm. The viscosity of the resulting starch paste was 1540 mPa⋅s. The starch paste was transparent and the starch was dissolved in an optimal way.

Example 12

The treatment was carried out as in example 10, using a suspension of potato starch with a concentration of 25 wt.%. The resulting starch paste was clear and the starch dissolved in an optimal manner.

Example 13

Wheat starch with a moisture content of 13% was mixed with water to form a 30% slurry and boiled at 98°C in the apparatus of FIG. 9. The height of the rotor in the device of FIG. 9 was 7 mm. Enzyme (Warozym A152) was added immediately after the device of FIG. 9, the temperature after the slurry has left the device of FIG. 9 was maintained at 95°C. Then further diluted with water heated to 60°C at a flow rate of 240 l/h. At a constant rotor speed of 4200 rpm and the addition of enzyme in the amount of 1400 ml/h, it was possible to achieve a paste viscosity of 440 mPa⋅s.

Example 14

The treatment was carried out as in example 13, with the addition of enzyme in the amount of 1800 ml/h. The viscosity of the resulting starch paste was 240 mPa.s.

Example 15

The treatment was carried out as in example 13, with the addition of the enzyme increased to 2200 ml/h. The viscosity of the resulting starch paste was 140 mPa.s.

Example 16

The treatment was carried out as in example 13, using a rotor speed of 3800 rpm and a rotor with a diameter of 130 mm. A starch paste viscosity of 580 mPa.s was achieved.

Example 17

The treatment was carried out as in example 16, using a rotor speed of 4200 rpm. A starch paste with a viscosity of 270 mPa.s was obtained.

Example 18

The treatment was carried out as in example 16, with the rotor speed being increased to 4800 rpm. A starch paste viscosity of 250 mPa.s was achieved.

Example 19

The treatment was carried out as in example 16, using a rotor speed of 5000 rpm. The resulting starch paste had a viscosity of 180 mPa.s.

Example 20

Cationized potato starch (Cationamyl 9853K) was mixed with water to form a 7.5% potato starch slurry. The resulting slurry was digested at a rate of 500 l/h in the apparatus of FIG. 9 at 98°C and then diluted to 4%. In this example, due to internal friction at increased consistency, better splitting is achieved.

Example 21

A slurry containing 15% potato starch was processed as in Example 20, the cooking being carried out in the apparatus of FIG. 9 at 110°C. Starch paste showed a lower porosity with increased paper strength.

In summary, an embodiment of the invention can be described as follows:

In the method for digesting starch (native starch or processed starch such as cationic starch), an aqueous starch slurry is treated in the digester 4 with steam and shear forces are applied, wherein the starch-containing slurry in the digester 4 is heated to a temperature of 85°C-110° C by introducing steam, and the splitting step is carried out until the desired degree of splitting is reached.

Claims (36)

1. The method of splitting starch, characterized by the following technological stages: a) preparation of an aqueous suspension of powdered starch, b) introducing the suspension into the digester (4), c) treatment of the slurry in the digester (4) with water vapor, the slurry being mechanically sheared by a rotor (42) with a scatter disk (44) with ribs (45), and the water vapor being supplied from the hollow ring below the rotor (70), in which holes are provided for the release of water vapor directed towards the rotor (42) and / or from the hollow chamber (60) displacement located in the digester (4), through at least one hole (63) for the release of water vapor into the region of the rotor (42) in order to carry out thermomechanical splitting, d) withdrawing at least partially gelatinized starch from the digester (4), e) if necessary, thinning the paste. 2. Method according to claim 1, characterized in that the starch-containing slurry in the digester (4) is heated in step c) to a temperature of 85°C-135°C by introducing steam. 3. Method according to claim 1 or 2, characterized in that the duration of step c) is from 1 to 5 hours. 4. The method according to one of paragraphs. 1-3, characterized in that at stage a) a suspension is obtained with a content of starch powder as a solid phase of not more than 35-45%. 5. The method according to one of paragraphs. 1-4, characterized in that the suspension before stage b) is heated to a temperature of 85°C-95°C. 6. The method according to one of paragraphs. 1-5, characterized in that in the implementation of stage c) the degree of starch splitting is set by choosing the rotation speed at which the suspension is mixed in the digester. 7. The method according to one of paragraphs. 1-6, characterized in that during the implementation of stage c) the degree of starch splitting is set by choosing the flow rate of the suspension. 8. The method according to one of paragraphs. 1-7, characterized in that in the implementation of stage c) the degree of starch splitting is set by choosing the temperature of the suspension. 9. The method according to one of paragraphs. 1-8, characterized in that an enzyme is added to the paste obtained in step d) according to paragraph 1, and the starch contained in the paste is decomposed by the action of the enzyme. 10. The method according to claim 9, characterized in that the enzyme is inactivated. 11. The method according to p. 10, characterized in that the inactivation of the enzyme is carried out by heating the paste to a temperature of 120°C-135°C. 12. The method according to p. 11, characterized in that the temperature is increased by introducing water vapor. 13. The method according to one of paragraphs. 1-12, characterized in that the slurry flow through the digester (4) in step c) is controlled by restricting the slurry flow through the digester (4) and/or by static stirring of the slurry in or after the digester (4). 14. The method according to one of paragraphs. 1-13, characterized in that at stage a) cationic starch powder is used to obtain a suspension. 15. The method according to one of paragraphs. 1-13, characterized in that at stage a) native starch powder is used to obtain a suspension. 16. A device in the form of a digester (4) for carrying out stage c) of the method according to claim 1, containing a container (40), a lid (41), a slurry line (50) ending in the lid, a drain line provided in the lid (41) at least partially reacted starch (paste), located inside the tank (40) stator plates (61), made in the form of guide plates, a rotor (42) and an annular displacement chamber (60), the outer surface of which is at a distance from the inner surface of the tank (40), and its inner hole is located coaxially with the rotor (42), and a water vapor supply line (62) is provided, which ends inside the tank (40). 17. The device according to claim 16, characterized in that the water vapor supply line (62) ends in a hollow displacement chamber (60), and in that the displacement chamber (60) is at its opposite mouth of the line (62) and adjacent to the rotor (42) side has at least one hole (63) for the release of water vapor. 18. The device according to claim 17, characterized in that there are outlets (63) distributed along the annular end surface of the displacement chamber (60) facing the rotor (42). 19. Device according to claim 16, characterized in that the steam supply line (62) terminates in a hollow ring (70) with at least one steam outlet. 20. Device according to claim 19, characterized in that the ring (70) is located on the opposite side of the rotor (42) from the displacement chamber (60). 21. The device according to claim 19 or 20, characterized in that the outlet is located on the wall of the ring (70) facing the rotor (42). 22. The device according to one of paragraphs. 19-21, characterized in that the ring (70) contains several outlet holes distributed along its length. 23. The device according to one of paragraphs. 16-22, characterized in that the stator plates (61) are spaced from the displacement chamber (60) and reach the inner surface of the container (40). 24. The device according to one of paragraphs. 16-23, characterized in that the rotor (42) has ribs (45) on at least one of its sides. 25. The device according to one of paragraphs. 16-24, characterized in that the hole coaxial to the rotor shaft (42) in the displacement chamber (60) has the shape of a funnel, and the expanded portion of the hole faces towards the cover (41) of the container (40). 26. The device according to one of paragraphs. 16-25, characterized in that the axis of the line (50) is coaxial to the axis of the annular displacement chamber (60) and is directed towards the rotor (42). 27. The device according to one of paragraphs. 16-26, characterized in that the ribs (45) on the scattering disk (44) increase in height from the inside out. 28. The device according to one of paragraphs. 16-27, characterized in that the ribs (45) are installed obliquely to the radial planes passing through the rotor shaft (42). 29. The device according to one of paragraphs. 16-28, characterized in that the rotor (42) protrudes through the bottom of the container into the container (40). 30. The device according to one of paragraphs. 16-29, characterized in that in the area of the mouth of the line (50) a constriction (52) is provided, which acts as a diffuser. 31. The device according to one of paragraphs. 16-30, characterized in that the constriction (52) is formed by an annular protrusion, in particular an annular protrusion with a triangular cross section.

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