EP3638409A1

EP3638409A1 - Method and mixing device for controlling the introduction of a pulverulent material into a liquid for a batch mixing method

Info

Publication number: EP3638409A1
Application number: EP18718686.1A
Authority: EP
Inventors: Uwe Schwenzow; Ulrich ROLLE; Ludger Tacke; Mikkel Mork Nielsen; Claus Patscheider
Original assignee: GEA TDS GmbH
Current assignee: GEA TDS GmbH
Priority date: 2017-06-13
Filing date: 2018-04-03
Publication date: 2020-04-22
Anticipated expiration: 2038-04-03
Also published as: WO2018228714A1; EP3638409B1; AU2018285004B2; PL3638411T3; JP6952802B2; AU2018285478A1; NZ758627A; PL3638409T3; NZ759145A; AU2018285004A1; AU2018285478B2; DK3638409T3; DK3638411T3; JP2020523188A; WO2018228713A1; EP3638411A1; EP3638411B1

Abstract

The invention relates to a method for controlling the introduction of a pulverulent material (P) into a liquid (F) consisting of at least one component for a batch mixing method according to the preamble of claim 1 and to a mixing device for carrying out the method, said method and mixing device ensuring that the disadvantages of the prior art which have become known are prevented. This is achieved by a method in that, among others, • the pulverulent material (P) is supplied in a discontinuous manner in pulses by means of a chronological sequence of metering pulses (i), each of which is characterized by a mass flow of the pulverulent material (ṁ_P), a duration of the metering pulse (Δt1), and a time interval between adjacent metering pulses (Δt2), • a time-dependent power consumption (l(t)) is ascertained which is proportional to a stirring and/or shearing and homogenizing power required for a temporarily available mixing product (M*), and • at the end of the time interval between adjacent metering pulses (Δt2) and in the event of a deviation of the time-dependent power consumption (l(t)) from the respective assigned value in the time-dependent curve of a reference power consumption (l_o) by more than a specified tolerance, either upwards or downwards, the duration of the metering pulse (Δt1) for the following metering pulse (i) is shortened in the first case and lengthened in the second case.

Description

Method and mixing device for controlling the introduction of a powdered substance into a liquid for a batch mixing process

TECHNICAL AREA

The invention relates to a method for controlling the introduction of a powdered substance into a liquid consisting of at least one component for a batch mixing process according to the preamble of claim 1, wherein the introduction and treatment of the powdery substance quasi under the reaction kinetic conditions of a residence time of a discontinuous working homogeneous reaction vessel takes place and a mixing device for carrying out the method.

STATE OF THE ART

With regard to the incorporation of a pulverulent substance into a liquid and its uniform distribution and, if appropriate, dissolution in the liquid, the mixer technology knows mixing processes which are operated batchwise or continuously (so-called inline processes).

In the batch process, the mixing of liquid and pulverulent substance is carried out by reaction kinetics in a so-called batch-operated reaction vessel (mixing vessel). A certain amount of liquid is placed in the mixing container and it is so long supplied powdered substance until a desired or scheduled predetermined dry matter concentration of the powdered substance is present in the liquid. In this case, powdery substance and liquid are preferably continuously stirred and / or mixed to form a mixed product, and the mixed product is homogenized with the aim of equal distribution of the pulverulent substance. The supply of the powdery substance can take place continuously or discontinuously.

In the inline process, the mixing of liquid and powdered substance is carried out by reaction kinetics in a so-called continuously operated reaction tank (mixing tank). It becomes the mixing container steadily liquid and powdery substance, the latter either continuously or discontinuously fed, and it is continuously discharged from the mixing vessel, a mixed product according to the supplied amounts of liquid and powdered material. Stirring and / or mixing or shearing and homogenization ensure that the theoretical postulate is that the mixed product has the same composition (eg dry matter concentration) at every point and that no temperature differences occur. The dry matter concentration in the discharged mixed product remains constant over the duration of the mixing process. The present invention is exclusively concerned with mixing processes, which are operated in the batch process and here in all possible forms. For example, a blending method and associated blending apparatus have been made public to the public at the following Internet link: "https://www.gea.com/products/Hiqh-Shear-Batch-Mixer.jsp".

The mixing devices mentioned above preferably also comprise so-called vacuum mixers which have a mixing container with a stirring and / or shearing and homogenizing device. The free surface of the liquid, which may for example have a free fill level with a height between 0.4 to 4 m in the mixing container, is subject to this height range correspondingly assigned negative pressure to atmospheric pressure, for example, 0.2 to 0.8 bar, so that the On the one hand, liquid can be freed of gas constituents more easily during the mixing process and, on the other hand, in the bottom area of the mixing tank under all operating conditions it has a negative pressure relative to atmospheric pressure. The introduction of the powdery substance into the mixing container takes place via an opening in the container wall below the free fill level. This opening continues in a tubular inlet connection in the direction of the outside of the mixing container, to which a pipe leading, for example, to a powder reservoir is connected. The inlet nozzle and thus the pipe are formed shut off via a supply of the powdery material inlet valve controlling, on the one hand completed the mixing device on this way to their environment and on the other hand presented in a powder reservoir amount of the powdery substance in case of need of the liquid due to the prevailing Pressure conditions can be supplied automatically. A related mixing device with a preferably discontinuous supply of the powdery substance is described in the publication DE 10 2015 016 766 A1, the latter being generic.

A discontinuous supply of the powdered substance, as disclosed, for example, in DE 10 2015 016 766 A, has the advantage that the supply always takes place via the full open position of the inlet valve designed as a lifting valve, thereby minimizing the risk of clogging of the inlet valve. Depending on the length of time of the respective open position, more or less large quantities of the pulverulent substance are intermittently introduced into the liquid, so that in principle there is the danger that corresponding aggregations of the pulverulent substance are produced by the stirring and / or shearing and homogenizing device are to be completely dissolved up to the subsequent entry of powdered material, while at the same time the greatest possible uniform distribution of the powdery substance is to be strived for. It has been found in this context that the intermittent supply of the powdery substance in an increase of the stirring and / or shearing and homogenizing power (drive power for the associated facilities), maps, which is necessary to that in this phase to treat the mixing process temporarily present mixed product. The course of the relevant drive power, which is proportional to the current consumption of the associated drive motors, corresponds approximately to a Gaussian normal distribution curve. To make matters worse in the mixing process that the residence time behavior of a batch operated reaction vessel or mixing tank theoretically postulated at each point an equal composition of the mixed product, that it practically, however, reinforced by the operational discontinuous supply of the powdery substance, to inhomogeneously distributed agglomerations of the powdery substance can come, which have not completely dissolved at all points of the mixing container until the next supply of powdered material. As a result, there is a risk of blocking the mixing container due to excessive dry matter concentration. On the one hand, it can not be ruled out that more or less large concentrations do not dissolve completely and persist in the mixed product. By the above-described inhomogeneities of the powdery substance in the mixed product in this the other there is the risk of microbiological growth (germ growth), which is especially under the thermal conditions when the mixing container is heated. In addition, it comes under the latter conditions increasingly to the formation of deposits (so-called product fouling) on the heated walls of the mixing vessel, on the one hand hinders the heat transfer and on the other hand shortens the service life of the mixing vessel to the next due cleaning cycle.

Since there is still a lack of effective control mechanisms to avoid inhomogeneities in the distribution and the degree of dissolution of aggregates of the powdery substance and disproportionately large fluctuations in the supply of the powdery substance and to prevent blocking of the mixing device because of excessive dry matter concentration in the mixing container So far, in order to act on the safe side, in mixing devices of the type in question, the stirring and / or shearing and homogenizing of the temporarily present mixed product is operated more intensively over the entire duration of the mixing process than is required over long periods of time. This too intensive treatment can on the one hand have a product-damaging effect and on the other hand is not energy-efficient. It is an object of the present invention, a generic method for controlling the introduction of a pulverulent substances in a liquid consisting of at least one component for a batch mixing method and an associated mixing device for performing the method such that the above-mentioned disadvantages of the prior art be eliminated. SUMMARY OF THE INVENTION

This object is achieved in procedural terms by a method having the features of claim 1. Furthermore, the object is achieved in device-technical terms by a mixing device for carrying out the method with the features of the independent claim 9. An advantageous embodiment of the mixing device is the subject of the subclaim 10.

method

With regard to a method according to the invention, the invention is based on a known method for controlling the introduction of a pulverulent substance into a liquid consisting of at least one component for a batch mixing method, the term "component" being understood to mean here The batch mixing process is typically used for medium- to high-viscosity mixed products with a final medium to high dry matter concentration as well as for mixing processes with several Liquid components which require little or no further processing in the downstream process, the introduction and treatment of the powdery substance, as seen from a reaction kinetics point of view, virtually taking place under the conditions of a residence time behavior of a discontinuous color continuous homogeneous reaction vessel. The method is characterized in a manner known per se in such a way that a quantity of liquid is introduced and the pulverulent material is fed discontinuously into this liquid and the liquid and the powdery substance are continuously stirred and / or mixed to a mixed product and the mixed product is homogenized. The powdery substance is supplied until a time-dependent course of a dry matter concentration of the powdery substance in the mixed product has grown to a predetermined final value.

The inventive idea of solution in the method consists in that a formulation of the mixed product at least with respect to the predetermined end Value assigned time-dependent course of a dry matter concentration and the reaction conditions are each given in the form of default data. It is further provided that the discontinuous supply of the powdery substance is carried out in a pulse-wise manner in a manner known per se by a chronological sequence of metering pulses. The reaction conditions in this regard, in a preferred embodiment, that the powdery substance is sucked by a negative pressure (vacuum) in the headspace of the mixing vessel to atmospheric pressure. The metering pulses are each characterized by a flow rate of the pulverulent substance mp, a duration of the metering pulse At1 and a time interval of adjacent metering pulses At2.

The method results in a time-dependent course of a dry matter concentration c (t), which ends according to plan in the predetermined end value, with a distinction between the course of a dry matter concentration without saturation character (approximately linear course) or with saturation character (degressive course) ,

• In the course without saturation character equal amounts of powdered substance can be dosed within the absorption capacity or the solubility limit of the liquid at equal time intervals, so that a complete time of homogenization of the mixed product sets a time-dependent approximately linearly increasing course of a dry matter concentration.

• In the course of saturation, only steadily decreasing amounts of powdered material can be metered at equal intervals as part of the absorption capacity or the solubility limit of the liquid, so that, when the mixed product is completely homogenized, a time-dependent decreasing progression of a dry matter concentration occurs.

The time-dependent course of a dry matter concentration ending in the predetermined end value is defined according to the invention by the sequence of clearly defined metering pulses.

A significant control technical feature is that a time-dependent current consumption l (t) is determined which is proportional to a stirring and / or shearing and homogenizing power required for a temporarily present mixed product. The latter always occurs in the form of approximately one Gaussian normal distribution, when a defined amount of powdered substance is introduced in pulses in the mixing process or the mixing container and treated. As soon as the pulverulent substance in the receiving liquid or in the receiving mixed product is distributed uniformly, ie distributed as homogeneously as possible and possibly dissolved, the time-dependent current consumption l (t) sounds, namely on a time-dependent course of a reference current consumption l ₀ (t) which is characteristic of the stirring and / or shearing and homogenizing power to be produced on the homogenized mixed product under the conditions of the associated time-dependent course of a dry matter concentration (c (t)). The relevant time-dependent course of the reference current consumption l ₀ (t) is stored in the default data and can be drawn from there, and it depends on the recipe of the mixed product and the reaction conditions for the mixing process.

At the end of the interval between adjacent metering pulses Et2 and when the time-dependent current consumption l (t) deviates from the respectively assigned value in the time-dependent course of a reference current consumption l ₀ (t) by more than a given tolerance, with a deviation either up or down can be present, the duration of the metering pulse At1 for the subsequent metering pulse is shortened in the first case and extended in the second case.

For time-dependent courses of a dry matter concentration c (t) without saturation character, a first embodiment of the method provides that these courses are respectively defined by a fixed time-interval ratio V between the duration of the metering pulse At1 and the associated time interval of adjacent metering pulses At2 are (V = At1 / At2 = constant). The respective profile of a dry matter concentration c (t) is increasing over time t, because the continuous pulsed metered flow of the powdered substance rh _P , which is in the most case a time-dependent flow rate powdered substance rhp (t), over the entire Time duration t of the mixing process, is constant (rh _P = constant). The mass flow of powdered substance rh _P is introduced in the time period t many times, namely (t / At2) times, at an almost constant level in the mixing vessel in an invariable amount of liquid rri _{F of} the present mixed product, wherein the time-dependent course of a dry matter concentration c (t) according to equation (1), as follows:

^{F mp} Et 2

In most practical cases, because the first term of the subsequent relation is usually small compared to the second term, it can approximate

t

m _P - Atl «m _F

are set so that according to equation (1a) for the time-dependent curve of a dry substance concentration c (t) with a first proportionality constant kl = approximately results: c _{(t) w} * pi _{t =} ni ^p _{vt = kl yt (1 a)} mp mp at2 mp

This control measure with a fixed time-interval ratio V (V = At1 / At2 = constant) inevitably leads in the same proportion to a corresponding shortening or lengthening of the time interval of adjacent metering pulses At2, based on the subsequent metering pulse.

For time-dependent curves of the dry matter concentration c (t) with saturation character, a second embodiment of the method provides that these curves are defined by a variable time-distance ratio V between the duration of the metering pulse At1 and the associated time interval of adjacent metering pulses At2 (V = At1 / At2 Φ constant), where

• If the time-dependent current consumption l (t) deviates from the respectively assigned value in the time-dependent course of a reference current consumption l ₀ (t) by more than the predetermined tolerance, the time-duration ratio V decreases and

In the case of a deviation of the time-dependent current consumption l (t) from the respective assigned value in the time-dependent course of a reference current consumption l ₀ (t) is increased by more than the predetermined tolerance down the time-distance ratio V is increased.

The respective profile of a dry matter concentration c (t) is increasing over time t, because the continuous pulse-wise metered flow rate of the powdery substance m _P , seen over the entire time t of the mixing process, while constant (m _P = constant ), the duration of the metering pulse At1 but steadily decreases and thus a steadily decreasing amount of powdered material is metered. The flow rate of powdered substance m _P is in the time t at an almost constant level in the mixing vessel in a present almost invariable volume of the mixed product V _M introduced (V _M «constant), wherein a density p _{M of} the mixed product according to the time-dependent course of a dry matter Concentration c (t) increases and the latter according to equation (2) with a second proportionality constant k2 = ^, as follows:

This control measure with a variable time-to-interval ratio V requires the controller to shorten or lengthen the duration of the metering pulse At1 with a constant interval of adjacent metering pulses At2 or, if the metering pulse At1 has not changed, the time interval between adjacent metering pulses At2 is adequate to lengthen or shorten. The control technical measure according to the invention therefore basically consists in both embodiments of the method in that the duration of the metering pulse At1 and the time interval of adjacent metering pulses At2 are selected so that the current-dependent current consumption I (t) determined at the respective end of the interval of adjacent metering pulses At2 Stirring and / or shearing and homogenizing of the temporarily present mixed product to the time-dependent course of a reference current absorption l ₀ (t), which is required for the relevant treatment of the homogenized mixed product, within a practically acceptable tolerance approaches. In order to make the metering of the powdery substance as trouble-free as possible, it is proposed for the method that the flow rate of the powdery substance over the duration of the metering pulse is constant. This is ensured, in particular, by virtue of the fact that a controllable opening for the supply of the pulverulent substance only assumes either a full open position or a closed position.

In order to make the control of the mixing process as manageable as possible, provides another embodiment of the method that the shortening or extension of the duration of the metering pulse then takes place when a by an allowable current exceedance or a permissible current underflow respectively determined Stromkorridor by an upward divergent power consumption or leave a downward different current consumption. In this case, the permissible current overshoot and the permissible current undershooting are each determined by a percentage of the associated time-dependent course of a reference current consumption. In order for the controller to operate as sensitively as possible in this regard, it is further proposed that the degree of shortening or lengthening of the duration of the metering pulse is determined as a function of the degree of deviation of the time-dependent current consumption from the associated profile of a reference current consumption.

In order to make operational data obtained in practice for a specific recipe usable for subsequent mixing processes with the same recipe, another embodiment of the method provides that the control of the introduction of the powdered substance into the further formulation-dependent default data on which at least one fluid is based can be based on past experience Mixing processes are obtained and stored, these default data, a mixing or solution temperature, a pressure above the liquid column, from which a reaction pressure results, speeds of means for stirring and / or shearing and homogenizing and dependent on the associated time-dependent course of a reference current consumption permissible current exceedance and a permissible current underflow are. In order to make available the operating data obtained in practice for a specific recipe for subsequent mixing processes having the same formulation, a further embodiment of the method provides that the target-oriented recipe-dependent control parameters obtained in the course of controlling the introduction of the powdered substance into the at least one liquid , namely the duration of the dosing pulse and the time interval of adjacent metering pulses, stored and used for subsequent control of the same recipes. mixing device

A mixing device for carrying out the method consists, in a manner known per se, of a mixing container which has an inlet connection for the supply of a liquid, an outlet connection for removal of a mixed product and a stirring device and / or a shearing and homogenizing device. At the mixing container an inlet valve is arranged with a valve closure member. The inlet valve is adjustable with the valve closure member either fully closed (closed position) or fully open (open position). A powdery substance is introduced into the liquid with the inlet valve, wherein the valve closing element can be transferred into the closed position or into the open position by means of a control device assigned to the inlet valve.

According to the invention, the control device of the mixing device provides formulation-dependent default data and formulation-dependent control parameters in the form of the duration of the metering pulse and the time interval of adjacent metering pulses. Furthermore, the control device according to the invention has at least one signal sensor designed as a measuring device, which detects a time-dependent current consumption of the stirring device and / or the shearing and homogenizing device. Equipped with these properties, the control device activates the closing or the open position of the valve closing member as a function of the time-dependent current consumption and in relation to the default data and the control parameters.

To the designed as a lift valve inlet valve that supplies the powdered material only in its full open position and thus the constipation maturity minimized from the outset to optimize even further in this regard and to avoid, for example, dead and cavities in the powder-exposed area of the valve housing of the inlet valve, provides an advantageous embodiment, that the valve closure member is formed at least in its powder-loaded area as a diameter-equal cylindrical rod, at the same diameter a valve plate is formed. When the inlet valve is in its full open position, the valve closing member is due to this embodiment largely moved out of the fully formed flow of the powdered substance so that it is not a flow obstacle on the one hand and on the other hand is a seat seal, which is in the valve plate recording, in the vicinity of the wall of a valve housing and thus outside of the fully formed flow region of the pipe flow and is at most only affected by the near-wall, stagnant flow in this edge region.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed description of the invention will become apparent from the following description and the accompanying drawings of the drawings and from the claims chen. While the invention is embodied in a variety of embodiments of a method for controlling the introduction of a powdered substance into a liquid comprising at least one component for a batch mixing process, a preferred process and a mixing device for carrying out the process are described in the drawing. Show it

Figure 1 shows a schematic representation of a mixing device for a batch mixing process;

Figure 2 in perspective and in half section, an inlet valve for

Feeding the powdery substance in a mixing device according to

Figure 1 without a control head housing;

Figure 3 is a qualitative representation of the process and the basic representation of the control features of the invention, a time-dependent current consumption l (t) for a sequence of dosing pulses with a constant duration of the metering pulse At1 and with a time interval of adjacent metering pulses At2, wherein a time-dependent course of a dry matter concentration c (t) without saturation character is taken as the basis;

Figure 4 in a qualitative representation of the method a time-dependent

Current consumption l (t) for a sequence of dosing pulses with a constant time duration of the dosing pulse At1 / 2 and with a time interval of adjacent dosing pulses At2 / 2, the time-dependent curve being based on a dry matter concentration c (t) according to FIG. 3; Figure 5 in a qualitative representation of the method a time-dependent

Current consumption l (t) for a larger sequence of metering pulses with a constant duration of the metering pulse At1 and with a constant time interval of adjacent metering pulses At2 for realizing a time-dependent approximately linearly increasing course of a dry matter concentration (without saturation character) according to FIGS. 3 and 4 and

Figure 6 in a qualitative representation of the method a time-dependent

Current consumption l (t) for a sequence of metering pulses with a steadily decreasing duration of the metering pulse At1 and with a constant time interval of adjacent metering pulse At2 for realizing a time-dependent degressive curve of a dry matter concentration (with saturation character).

Mixing device (FIGS. 1 and 2)

A mixing device 1000 has inter alia a mixing container 100, which consists of a preferably cylindrical container casing 100.1, an upper container bottom 100.2 and a lower container bottom 100.3. The lower container bottom 100.3 preferably tapers downwards, usually conically or in the form of a circular cone, and has at the lower end an outlet connection piece 100.4 for a mixed product M. In the mixing vessel 100, a liquid F in an amount of liquid m _F is introduced via a feed connection 100.5, which forms a free filling level N, above which, as a rule, in the speech in question standing mixing device 1000 (eg vacuum mixer), a pressure above the liquid column p, a negative pressure to atmospheric pressure prevails.

An inlet valve 20 is arranged on the container casing 100.1 or the lower container bottom 100.3. The inlet valve 20 is used for the discontinuous supply of a powdered substance P with a flow of powdered substance rh _P , which is supplied via a supply line 18, into the liquid F or into the mixed product M. The inlet valve 20 is associated with a control device 30, which is provided with a control head housing 14 of the inlet valve 20 communicates via a signal line 22 and the inlet valve 20, if necessary, transferred to its open or closed position. In the mixing container 100 is a via a first drive motor 40 with a rather low first speed n1 driven agitator 24, preferably centrally located and mechanically acting, which preferably extends down to the area of the lower container bottom 100.3. The required stirring effect can also be achieved or assisted by fluidic means, for example by pumping the liquid F or the mixed product M via a not shown circulation line with preferably tangential entry of the liquid F or the mixed product M in the mixing vessel 100.

Alternatively or in addition to the stirring device 24 is preferably in the lower region of the lower container bottom 100.3 and preferably eccentrically in this a driven by a second drive motor 50 at a rather high second speed n2 shearing and homogenizing device 26 is provided. This sucks the liquid F or the mixed product M preferably on the one hand from above and throws them on the other hand ring in the near-wall region of the lower tank bottom 100.3 such that preferably an outwardly inwardly directed circulation flow in the mixing tank 100 is formed. When passing through the shearing and homogenizing device 26, liquid F and pulp P or the resulting mixed product M are mixed very intensively mechanically, preferably homogenizing.

The inlet valve 20 is designed as a lifting valve (Figure 2). It has a valve seat 2 a in a valve housing 2 a and a cooperating with this valve plate 8a, which is formed on a valve closing member 8. As a rule, the valve closing member 8 receives a seat seal 10, which in the closed position of the inlet valve 20 in cooperation with the valve seat 2a causes the seal. The valve seat 2a has a seat opening 2b, through which the pulverulent substance P supplied via a pipe connection 2c from the supply line 18 is introduced into the liquid F (FIG. 1).

The liquid F present above the connection point of the inlet valve 20, which is preferably arranged directly in the wall of the mixing container 100, forms a height h with its liquid column (FIG. 1), so that the static pressure in the area of the aforementioned connection point and thus also in the region of the seat opening 2b from the pressure above the liquid column p (preferably negative pressure) and the static pressure resulting from the height of the liquid column h, composed. In a vacuum mixer with a negative pressure of, for example p = 0.2 to 0.8 bar and a corresponding height of the liquid column h = 0.2 to 4 m corresponding to this pressure range prevails in the region of the seat opening 2b always a negative pressure to atmospheric pressure, so the seat opening 2b is sucked out of the mixing container 100 and thus the powdered substance P is sucked in. The seat opening 2b is with the valve plate 8a between fully closed, the closed position, o- fully open, the open position, adjustable. The valve housing 2 is connected via a lantern housing 4 with a drive housing 6 for driving the valve closure member 8. It is preferably a pressure medium-loaded spring / piston drive, wherein a return spring 12, the valve tilschließglied 8 usually transferred to its closed position when the drive housing 6 is not pressurized, preferably compressed air, acted upon. A valve rod 8b, which engages the valve disk 8a of the valve closing member 8 and is guided through the drive housing 6 and into the control head housing 14, serves on the drive side the axial guidance of the valve closure member 8. The valve closure member 8 is at least in its powder-loaded area as a diameter-equal cylindrical rod formed on the diameter equal to the valve plate 8a is formed. Through this structural design cavities and dead spaces in the valve housing 2 are avoided in the powder-loaded range of motion of the valve closure member 8, wherein the valve closure member 8 with its end-side valve plate 8a and the associated seat seal 0 can largely withdraw from the fully flowed through area of the valve housing 2. The control device 30 (FIG. 1) has at least one signal sensor 16. The at least one signal sensor 16 is a measuring device, for example for mixing parameters, such as the pressure above the liquid column p in the mixing vessel 100, a mixing or solution temperature T of the liquid F, a dry matter concentration c or a time-dependent course of a dry matter concentration c (t ), Rotational speeds n1, n2 and a time-dependent current consumption l (t) of the stirring and / or shearing and homogenizing device 24, 26. The signal sensor 16 is exemplary in FIG. 1 for the time-dependent current consumption l (t) of the second drive motor 50 the shearing and homogenizing device 26 shown. In an analogous manner, additional or alternative further measuring devices can be provided which determine the other mixing parameters.

Method (FIGS. 3 to 6 in conjunction with FIGS. 1 and 2)

The introduction and treatment of the powdery substance P takes place quasi under the reaction kinetic conditions of a residence time behavior of a discontinuously operating homogeneous reaction vessel. The method is characterized in a conventional manner in such a way that a lot of liquid m _{F presented} in the mixing vessel 100 (supply via the inlet port 100.5) and the powdered substance P of this liquid F via the inlet valve 20 with the Mengenstrom ström powdered substance rh _Pl in the most general case, a time-dependent flow rate powdered substance rh _P (t) may be fed discontinuously. The liquid F and the powdery substance P are continuously stirred and / or mixed to a mixed product M and the mixed product M is homogenized. The powdery substance P is supplied until the time-dependent course of a dry matter concentration c (t) of the powdered substance P in the mixed product M has grown to a predetermined final value CE.

In the mixing process in question, a recipe of the mixed product M are at least in terms of the predetermined end value CE assigned Time-dependent course of a dry matter concentration c (t) and the reaction conditions in each case in the form of default data D specified.

The discontinuous supply of the powdery substance P takes place over a period of time t pulse by a time sequence of dosing pulses i (Figures 3 and 4), each by the flow rate of the powdered substance m _P , a period of dosing At1 and a time interval of adjacent dosing pulses At2 are characterized. The flow rate of the powdered substance m _P is basically a time-dependent flow rate powdered substance rh _P (t), as already stated above, wherein the present application subject due to the design and the switching characteristic of the inlet valve 20 approximately from a time-independent and thus constant flow rate powdered substance m _P. is assumed (m _P = constant). For the duration of the metering pulse At1 according to FIG. 3, the time-dependent current consumption l (t), likewise plotted in FIG. 3 over the corresponding time duration t, is determined or measured, for example, on the second drive motor 50 of the shearing and homogenizing device 26. The latter is proportional to a mixing and / or shearing and homogenizing power (FIG. 1) which is required for a mixing product M * temporarily present in mixing vessel 100 immediately after metering pulse i, and which is produced by the stirring and / or shearing Homogenizing device 24, 26 is applied. The course of the time-dependent current consumption l (t) is similar to a Gaussian distribution curve, it increases with the intermittently entering mass flow of powdered substance m _P , reaches a maximum, and then after dissolution of the powdered substance P, ie at a then reached homogenized mixed product M to gradually decrease to a time required for this homogenized mixed product M current consumption l (t). This typical behavior is used in accordance with the invention in terms of control technology, in that a time-dependent course of a reference current consumption l ₀ (t) is used from the default data D, which is characteristic for the stirring and / or shearing and homogenizing power to be produced on the homogenized mixed product M. If the time interval between adjacent metering pulses At2 is insufficient to dissolve, mix and homogenize a metered quantity of pulverulent substance m _P = rh _P Atl, a time-dependent upward-divergent current draw l ^* (t) is measured, so that in this state the temporary present mixed product M ^* at the end of the interval of adjacent dosing pulses At2 a renewed dosing pulse i is not yet displayed. If, under comparable conditions, a time-dependent, downwardly differing current consumption l ** (t) is determined, then this can be an indication that the dosing pulses At2 adjacent to the time interval also contain defined stirring and / or shearing and homogenizing. Phase is measured excessively long or that no phase adequate amount of powdered substance m _{P was} metered.

As soon as the powdered substance P in the receiving liquid F or in the receiving mixed product M is uniformly distributed, ie possibly homogeneously distributed and possibly dissolved, the time-dependent current consumption l (t) sounds, namely on the time-dependent course of a reference current consumption l ₀ (t), which is characteristic for the stirring and / or shearing and homogenizing power to be produced on the homogenized mixed product M under the conditions of the associated time-dependent course of the dry substance concentration c (t) (see FIGS. 3 to 5: approximately linear time-dependent course of a reference current consumption l ₀ (t); FIG. 6: degressive time-dependent profile of a reference current consumption l ₀ (t)). The time-dependent course of a reference current consumption l ₀ (t) begins at time t = 0, to which only the pure fluid F is present, with an initial value of a reference current consumption l ₀ (t = 0) = l ₀ (see FIGS. 3 to 6). , The relevant course of a reference current consumption l ₀ (t) is stored in the default data D, and it depends on the recipe of the mixed product M and the reaction conditions for the mixing process. At the end of the interval between adjacent metering pulses At2 and deviation of the time-dependent current consumption l (t) from the respective assigned value in the time-dependent course of a reference current consumption l ₀ (t) by more than a predetermined tolerance, wherein a deviation can be either up or down (see Figures 3, 4), the duration of the dosing pulse At1 for shortened the subsequent metering pulse in the first case and extended in the second case. The tolerance consists in a specification of an allowable current exceedance ΔΙ1 and in a permissible current underflow ΔΙ2 (FIG. 3). The case of the shortening is illustrated in FIG. 4, wherein in the illustrated case example the duration of the metering pulse At1 and thus also the associated period of adjacent metering pulses Δί2 have been halved by way of example (ΔΪ1 / 2; At2 / 2). In this dosing mode, again at the end of the time interval of adjacent dosing pulses Δί2 / 2, a check is made as to whether there is a time-dependent up or down current consumption l * (t), l ^** (t) within the given tolerance necessary correction in the sense described above is required.

The shortening or extension of the duration of the metering pulse Δί1 occurs when a current corridor determined by the permissible current excess ΔΙ1 or the permissible current shortage ΔΙ2 is limited by the time-dependent current consumption l * (t), l ** (deviating upwards or downwards). t) is left. The permissible excess current and the permissible current undershoot ΔΙ1, ΔΙ2 are preferably each determined by a percentage of the associated time-dependent course of a reference current consumption l ₀ (t). Furthermore, the extent of shortening or lengthening the duration of the metering pulse Δί1 as a function of the degree of deviation of the time-dependent current consumption l (t) from the associated time-dependent course of a reference current consumption l ₀ (t) is preferably determined. The permissible excess current ΔΙ1 and permissible current undershoot ΔΙ2, which are ultimately determined by the respective formulation of the mixed product M, can be part of the specification data D for the mixing process.

In the course of the control of the introduction of the powdered substance P into the at least one liquid F obtained targeted recipe-dependent control parameters S, namely the duration of the metering pulse Δί1 and the time interval of adjacent metering pulses Δί2 are stored and used for subsequent control of the same recipes. The control device 30 of the mixing device 100 according to the invention is set up so that it can provide the formulation-dependent default data D and the formulation-dependent control parameters S in the form of the duration of the metering pulse At1 and the time interval of adjacent metering pulses At2. The control device 30 furthermore has at least the signal sensor 16 designed as a measuring device (FIG. 1) which detects the time-dependent current consumption l (t) of the stirring device 24 and / or the shearing and homogenizing device 26 (FIGS. 3, 4). According to the invention, the control device 30 controls the closing or the open position of the valve closing member 8 (FIG. 2) as a function of the time-dependent current consumption l (t) and in relation to the default data D and the control parameters S.

The method results in the time-dependent course of a dry matter concentration c (t), which ends according to plan in the predetermined end value CE, wherein between the time-dependent course of a dry matter concentration c (t) without saturation character (approximately linear time-dependent course; 5) or the time-dependent course of a dry matter concentration with a saturation character (degressive time-dependent course, see FIG. The time-dependent course of a dry substance concentration c (t) ending in the predetermined end value CE is defined by the sequence of specific metering pulses i, that is to say clearly defined by the duration of the metering pulse At1 and the time interval of adjacent metering pulses At2.

For the time-dependent course of a dry matter concentration c (t) without saturation character, starting at c (t = 0) = 0 for the pure liquid F (FIG. 5), as described by equations (1, 1a) given above (c (t) = k1 V t), an embodiment of the method provides that this profile is defined by a fixed time-interval ratio V between the duration of the dosing pulse At1 and the associated time interval of adjacent dosing pulses At2 ( V = At1 / At2 = constant). In the case of deviations from the time-dependent course of a reference current consumption l ₀ (t), the duration of the dosing pulse At1 is shortened (as shown by way of example qualitatively in FIG. 4 in contrast to FIG. 3) at a constant time-interval ratio V or extended. This control measure with a fixed time-interval ratio V inevitably leads in the same proportion to a corresponding reduction or lengthening of the time interval of adjacent metering pulses At2, based on the subsequent metering pulse i. For the time-dependent course of a dry matter concentration c (t) with saturable (Figure 6), as can be described by the above equation (2) (c (t) "k2 ~ _^)> ^{SIENT another} embodiment of the

This process is defined by a variable time-interval ratio V between the duration of the dosing pulse At1 and the associated time interval of adjacent dosing pulses At2 (V = At1 / At2 constant), where

• If the time-dependent current consumption l (t) deviates from the respectively assigned value in the time-dependent course of a reference current consumption l ₀ (t) by more than the predetermined tolerance downwards, the time-duration interval ratio V is increased.

The respective course of a dry matter concentration c (t) over the period of time t, starting at c (t = 0) = 0 for the pure liquid F (Figure 6), increasing digressive because of the continuous pulsed metered mass flow of the powdery substance rhp , seen over the entire time period t of the mixing process, although preferably constant (m _P = const), the duration of the metering pulse At1 but steadily decreases and thus a steadily decreasing amount of powdered substance m _{P is} metered. The mass flow of powdered substance rh _P is introduced in the period of time t of the entire mixing process at an almost constant level level N in the mixing vessel 100 into a present almost invariable volume of the mixed product V _M (V _M "constant), whereby a density p _{M of} the mixed product M increases. namely according to the time-dependent course of a dry matter concentration c (t), which grows to the predetermined end value CE. FIG. 6 illustrates, as a function of the time-dependent progression of a dry substance concentration c (t), how the respectively metered quantity of powdered substance rrip = i pAtl steadily decreases, with the respectively associated time-dependent current consumption l (t) in each case at the end of the time interval Adjacent dosing At2 on the associated time-dependent course of a reference current consumption l ₀ (t) has approximated or is largely congruent with this. A related course describes a successful mixing process, which on the one hand protects the mixed product M and on the other hand is designed to be energy-efficient. It does not require control measures in the sense explained above. Only when deviations from the permissible current exceeding or current undershooting ΔΙ1, ΔΙ2 occur, the control mechanisms, as described in the first method in connection with FIGS. 3 and 4, apply mutatis mutandis.

These control measures with a variable time-to-time ratio V require the control device 30 to be able to shorten or lengthen the duration of the metering pulse At1 with an unchanging interval of adjacent metering pulses At2 or, if the metering pulse At1 is not changed, the time interval adjacent Adequately lengthen or shorten dosing pulses At2.

The control measures according to the invention thus consist essentially in both embodiments of the method in that the time duration of the metering pulse At1 and the time interval of adjacent metering pulses At2 are selected such that the time-dependent determined current consumption I (t) at the respective end of the time interval of adjacent metering pulses At2 Stirring and / or shearing and homogenizing of the temporarily present mixed product M * to the time-dependent course of a reference current absorption l ₀ (t), which is required for the relevant treatment of the homogenized mixed product M, approximates within a practically acceptable tolerance. REFERENCE LIST OF ABBREVIATIONS USED

1000 mixing device

100 mixing tanks

100.1 container jacket

100.2 upper tank bottom

100.3 lower tank bottom (conical;

100.4 outlet nozzle

100.5 inlet connection

20 inlet valve

30 control device

40 first drive motor

50 second drive motor

2 valve housing

2a valve seat

2b seat opening

2c pipe connection

4 lampshades

6 drive housing

8 valve closure member

8a valve plate

8b valve rod

10 seat seal

12 return spring

14 steering head housing

16 signal transducers

18 feed line

22 signal line

24 stirring device 26 Shearing and homogenizing device

D default data

F liquid l ₀ Initial value of a reference current consumption

(for the homogenized mixed product M; l ₀ (t = 0) = lo) l ₀ (t) time-dependent course of a reference current consumption l (t) time-dependent current consumption

(for the temporarily present mixed product M *) l * (t) time-dependent upwards deviating current consumption l ** (t) time-dependent downwards deviating current consumption

ΔΙ1 permissible current exceeded

ΔΙ2 permissible current underflow

M mixed product

M * temporary mixed product

N level level

P powdery substance

S control parameters

T mixing or solution temperature

V duration-time interval ratio (V = Et1 / At2)

V _M Volume of the mixed product

P Density of the mixed product c Dry matter concentration

c (t) time-dependent course of a dry matter concentration

CE specified final value (of the time-dependent course) h height of the liquid column

i dosing pulse k1 first proportionality constant (k1 = - m) k2 second proportionality constant (k2 «-) m _F quantity of liquid

m _P amount of powdered substance

rh _P flow of powdery material

rh _P (t) time-dependent flow rate powdered substance n1 first speed

n2 second speed p pressure above the liquid column t time (general) or duration of the mixing process

At1 duration of the dosing pulse

At2 Time interval between adjacent dosing pulses

Claims

claims

1. A method for controlling the introduction of a powdery substance (P) into a liquid (F) consisting of at least one component for a batch mixing process,

In which the introduction and treatment of the pulverulent substance (P) takes place under the conditions of a residence time behavior of a discontinuously operating homogeneous reaction vessel,

o that an amount of liquid (ITIF) presented and the powdered substance (P) is discontinuously fed into this liquid (F), o that the liquid (F) and the powdery substance (P) continuously stirred and / or to a mixed product (M ) are mixed and the mixed product (M) is homogenized and

o that the powdery substance (P) is supplied until a time-dependent course of a dry matter concentration (c (t)) of the powdery substance (P) in the mixed product (M) has grown to a predetermined end value (CE),

characterized,

• that a formulation of the mixed product (M) at least in terms of the predetermined end value (CE) associated time-dependent curve of a dry matter concentration (c (t)) and the reaction conditions are each given in the form of default data (D)

• that the discontinuous supply of the powdery substance (P) in pulses by a temporal sequence of metering pulses (i), each by a flow rate of the powdered material (m _P ), a period of the metering pulse (At1) and a time interval of adjacent metering pulses (At2 ) are characterized

That the time-dependent course of a dry matter concentration (c (t)) ending in the predetermined end value (CE) is defined by the sequence of uniquely determined metering pulses (i), That a time-dependent current consumption (I (t)) is determined which is proportional to a stirring and / or shearing and homogenizing power required for a temporarily present mixed product (M *),

That a time-dependent course of a reference current consumption (l ₀ (t)) which is characteristic for the homogenized mixed product (M) under the conditions of the associated time-dependent course of a dry substance concentration (c (c) is used from the specification data (D) t)) to be provided stirring and / or shearing and homogenizing performance, and

· That at the end of the interval of adjacent metering pulses (At2) and deviation of the time-dependent current consumption (l (t)) of the respectively assigned value in the time-dependent course of a reference current consumption (l ₀ (t)) by more than a predetermined tolerance, either up or down, the duration of the dosing pulse

(At1) for the subsequent dosing pulse (i) is shortened in the first case and extended in the second case.

Method according to claim 1,

characterized,

that time-dependent courses of a dry matter concentration (c (t)) without

Saturation character is defined by a fixed time-to-space ratio (V) between the duration of the dosing pulse (At1) and the associated time interval of adjacent dosing pulses (At2) (V = At1 / At2 = constant).

Method according to claim 1,

characterized,

in that time-dependent curves of a saturation-type dry matter concentration (c (t)) are defined by a variable time-interval ratio (V) between the duration of the metering pulse (At1) and the associated interval of adjacent metering pulses (At2) (V = At1 / At2), where • in the case of a deviation of the time-dependent current consumption (l (t)) from the respectively assigned value in the time-dependent course of a reference current absorb (l ₀ (t)) by more than the predetermined tolerance up the time-space ratio (V) decreases and

• If the time-dependent current consumption (l (t)) deviates from the respectively assigned value in the time-dependent course of a reference current consumption (l ₀ (t)) by more than the specified tolerance downwards

Duration-time interval ratio (V) is increased.

Method according to one of the preceding claims,

characterized,

the mass flow of the pulverulent substance (rh _P ) is constant over the duration of the metering pulse (At1).

Method according to one of the preceding claims,

characterized,

that the shortening or the lengthening of the duration of the metering pulse (At1) takes place when a current corridor determined in each case by an allowable current excess (ΔΙ1) or an allowable current shortage (ΔΙ2) is limited by an upward current consumption (l * (t)) or a downwards deviating current consumption (l ** (t)) is left, the permissible current exceeding and the permissible current undershooting (ΔΙ1, ΔΙ2) are each determined by a percentage of the associated time-dependent course of a reference current consumption (l ₀ (t)). Method according to one of the preceding claims,

characterized,

the degree of shortening or lengthening of the duration of the metering pulse (Δί1) as a function of the degree of deviation of the time-dependent current consumption (l (t), l ^* (t), l ^** (t)) depends on the associated time-dependent History of a reference current consumption (l ₀ (t)) is determined. Method according to one of the preceding claims,

characterized,

that the control of the introduction of the pulverfömriigen substance (P) in the at least one liquid (F) underlying further recipe-dependent specification data (D) are obtained from empirical values of previous mixing processes and stored, said default data (D)

A mixing or solution temperature (T),

A pressure above the liquid column (p),

• Speeds (n1, n2) of equipment for stirring and / or shearing and homogenizing and

• an allowable current exceeding (ΔΙ1) dependent on the assigned curve of a reference current consumption (l ₀ (t)) and an admissible drop below the current (ΔΙ2)

are.

Method according to one of the preceding claims,

characterized,

that in the course of the control of the introduction of the powdery substance (P) in the at least one liquid (F) obtained targeting formulation-dependent control parameters (S), namely

• Duration of the dosing pulse (At) and

• time interval of adjacent dosing pulses (At2),

stored and used for subsequent control of the same recipes.

Mixing device for carrying out the method according to claim 1, with a mixing container (100) having an inlet connection (100.5) for the supply of a liquid (F), an outlet connection (100.4) for removal of a mixed product (M) and a stirring device (24) and / or a shearing and homogenizing device (26), with an inlet valve (20) arranged on the mixing container (100) with a valve closing member (8), with the valve closing member (8) with which the inlet valve (20 ) either between fully closed (closed position) or fully open (open position). is adjustable with the inlet valve (20), through which a pulverulent substance (P) is introduced into the liquid (F), with a control device (30) associated with the inlet valve (20), with which the valve closing member (8 ) is convertible into the closed or in the open position,

characterized,

• that the control device (30) provides recipe-dependent default data (D) and formulation-dependent control parameters (S) in the form of the duration of the metering pulse (Δί1) and the time interval of adjacent metering pulses (At2),

• that the control device (30) has at least one signal sensor (16) designed as a measuring device, which detects a time-dependent current consumption (l (t)) of the stirring device (24) and / or the shearing and homogenizing device (26), and

• that the control device (30) the closing or the open position of the valve closing member (8) in dependence on the time-dependent current consumption (L (t)) and in relation to the default data (D) and the control parameters (S). controls.

10. Mixing device according to claim 9,

characterized,

the valve closing member (8) is designed, at least in its powder-exposed area, as a cylindrical rod of the same diameter, on which a valve disk (8a) is integrally formed on the same diameter.