EP3638411A1

EP3638411A1 - Method and mixing device for controlling the introduction of a pulverulent material into a liquid for an inline mixing method

Info

Publication number: EP3638411A1
Application number: EP18718687.9A
Authority: EP
Inventors: Uwe Schwenzow; Erwin S THOLD; 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: EP3638409A1; JP6952802B2; PL3638409T3; NZ758627A; JP2020523188A; AU2018285478A1; PL3638411T3; AU2018285478B2; NZ759145A; AU2018285004A1; WO2018228714A1; DK3638409T3; DK3638411T3; WO2018228713A1; EP3638411B1; EP3638409B1; AU2018285004B2

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 an inline mixing method according to the preamble of claim 1 or the preamble of sub-claim 2 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 first 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 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 while maintaining the ratio (V = Δt1/Δt2).

Description

Method and mixing device for controlling the introduction of a powdery substance into a liquid for an in-line mixing process

TECHNICAL AREA

The invention relates to a first method for controlling the introduction of a powdered substance in a liquid consisting of at least one component for an in-line mixing method according to the independent claim 1 and a corresponding second method according to the preamble of the independent claim 2, wherein the introduction and treatment the powdery substance is quasi under the reaction kinetic conditions of a residence time behavior of a continuously operating homogeneous reaction vessel takes place and a mixing device for performing the respective method.

STATE OF THE ART

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

In the batch process, the mixing of liquid and powdered substance is carried out kinetic reaction kinetically 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 uniform 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 pulverulent substance is carried out in a reaction-kinetic manner in a so-called continuously operated reaction vessel. be done (mixing container). A distinction is made between a single-pass and a multi-pass method. In the single-pass process, liquid and pulverulent material, the latter either continuously or discontinuously, are fed to the mixing container and a mixed product corresponding to the supplied quantities of liquid and pulverulent material is continuously removed from the mixing container. 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.

In the multi-pass process, a mixed product prepared in a first phase and adequately made to the one-pass process is recirculated in a second phase through the mixing vessel, wherein powdered material is further supplied either continuously or discontinuously. The mixed product is recirculated until it has a grown to a predetermined final dry matter concentration. With regard to the recirculation, various embodiments of the method are known, which provide that the entire mixed product discharged from the mixing container is either led again directly through the mixing process or first passed through a storage volume and then fed again to the mixing process. Between these two characteristics, any division ratios can be realized. The present invention is exclusively concerned with mixing processes, which are operated in the inline process and here in all possible forms (single pass and any variants of the multi-pass process). The mixing procedures and associated mixing equipment have been made public, for example, at the following Internet link: http://www.gea.com/products/ High-Shear-Inline-Mixer.isp ".

US Pat. No. 3,425,667 A describes a one-pass process for the continuous, controlled mixing of pigments and fillers with binder solutions or other liquids, in which solid and liquid components are controlled in a controlled manner. Herten quantities are fed into a flow mixing device and mixed there with each other. The control involves measuring the ratio of liquid and solid components in the mixture after the mixture has passed through the flow mixer. The regulation of the liquid supply takes place as a function of this measurement, with the regulation of the supply of solids comprising separate control agents.

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 vessel, is subject to a corresponding height range associated negative pressure to atmospheric pressure, for example, 0.2 to 0.8 bar, so that the Liquid on the one hand in the mixing process can be easily freed from gas components and on the other hand in the bottom region of the mixing container under all operating conditions has a negative pressure 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 pipeline leading to a powder reservoir, for example, is connected. The inlet nozzle and thus the pipeline are designed to be shut off via an inlet valve controlling the supply of the pulverulent material, so that on the one hand the mixing device is sealed off from its environment via this path and, on the other hand, an amount of pulverulent substance in the powder storage container in case of need 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 document DE 10 2015 016 766 A1.

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. depend gig greater than the duration of the respective open position more or less large amounts of the powdery substance are intermittently introduced into the liquid, so that in principle there is a risk that it comes to appropriate agglomerations of the powdery substance by the stirring and / or shearing and homogenizing -Form to dissolve completely to the subsequent entry of powdered material, while at the same time the greatest possible uniform distribution of the powdery substance is desirable. It has been found in this context that the intermittent supply of the pulverulent substance is reflected in an increase in the stirring and / or shearing and homogenizing power (drive power for the associated devices), which is necessary in order to achieve the treat this phase of 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 continuously operated reaction vessel or mixing container 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, at different residence times of inhomogeneously distributed Zusammenballungen the powdery substance can come.

Therefore, it can not be ruled out, on the one hand, that more or less large aggregates, which leave the mixing vessel after a below-average residence time, do not dissolve completely and persistently exist in the mixed product. By the above-described inhomogeneities of the powdery substance in the mixed product in this on the other hand, the risk of microbiological growth (germination), especially when the mixing vessel is heated and the inhomogeneities under these thermal conditions optionally dwell above average in the mixing container, is promoted , In addition, under the last-mentioned conditions, there is an increased formation of deposits (so-called product fouling) on the heated walls of the mixing vessel, which on the one hand leads to the heat transfer. on the other hand, the service life of the mixing container is shortened until the next cleaning cycle.

Since there are hitherto lack of effective control mechanisms to avoid inhomogeneities in the distribution and the degree of dissolution of clumps 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 agitation 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, two generic methods for controlling the introduction of a powdered substances in a liquid consisting of at least one component for an in-line mixing method and associated mixing devices for carrying out the respective process in such a way that the above-mentioned disadvantages of the prior art be eliminated.

SUMMARY OF THE INVENTION

This object is achieved in procedural terms by a first method with the features of the independent claim 1 and by a second method with the features of the independent claim 2. Furthermore, the object is achieved in device-technical terms by a mixing device for carrying out the respective method with the features of claim 12 or 13.

First procedure

With a view to a first method according to the invention, the invention relates to a method for controlling the introduction of a pulverulent substance into a liquid consisting of at least one component for an inline Mixing process, wherein the term "component" is to be understood as meaning that these can generally be discrete, separate liquids which can also be supplied separately from one another to the mixing process. A one-step procedure is typically used to prepare low viscosity basic low dry matter base slurries or, for example, for skimmed milk powder in water or cocoa powder in milk or, more generally, when a powdery material with good solubility needs to be dissolved in a short time Treatment of the powdery substance, kinetic reaction, quasi under the conditions of a residence time behavior of a continuous homogeneous reaction vessel, in such a way that the liquid continuously and the powdery substance discontinuously fed to a mixing container The goal being a predetermined, fixed time constant dry matter concentration of the powdered substance in the liquid. The liquid and the powdery substance are thereby continuously stirred and / or mixed to a mixed product and the mixed product is homogenized. In general, the treatment processes "stirring", in which no or only a very small mechanical force is applied to the mixed product, and "mixing", in which applied to the mixed product a significant shearing force and therefore the "mixing" subsequently in this regard also The mixing product is continuously removed in accordance with the supplied quantities of liquid and powdered material In the mixing method in question, a formulation of the mixed product is at least as far as the preset dry matter concentration and the reaction conditions are each specified in the form of default data.

The idea of solution consists in that the discontinuous supply of the pulverulent substance takes place in a manner known per se in pulses by a chronological succession 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 by a flow rate of the powdery substance rh _P , a duration of the dosing pulse At1 and a time interval of adjacent dosing pulses At2.

By a fixed time-distance ratio V between the duration of the metering pulse At1 and the associated time interval At2 adjacent metering pulses (V = = constant), the predetermined dry matter concentration c is defined according to equation (1), wherein in the most general case, the flow rate of the powder Substance ih _{P is} a time-dependent flow rate powdery substance ip (t) and a flow rate liquid rh _{F is} a time-dependent flow rate liquid rh _F (t):

c = = _k = _k = constant (1)

The time-dependent mass flows rh _P (t) and m _F (t) are constant over time in the mixing process in question (m _P = constant, m _F = constant), so that a constant k is obtained from the quotient of both variables = results. Also, since the premise of the time-Zeitabstand- rh _F (t)

Ratio V is kept constant, and the predetermined dry matter concentration c is constant in the necessary manner. 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 approximately in the form of a Gaussian normal distribution when a defined amount of powdered substance m _{P is} introduced and treated in pulses in the mixing process or the mixing container.

As soon as the pulverulent substance in the receiving liquid is distributed uniformly, ie distributed as homogeneously as possible and possibly dissolved, the time-dependent current consumption l (t) decays, namely to a reference current consumption l ₀ , which is characteristic for the completely homogenized one Mixed product to be provided stirring and / or shearing and homogenizing performance. The relevant Reference current consumption l ₀ is stored in the default data and can be used 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 dosing pulses At2 and deviation of the time-dependent current consumption l (t) from the reference current consumption l ₀ by more than a predetermined tolerance, wherein a deviation can be either up or down, is in compliance with the from the given dry matter Concentration c resulting fixed ratio V = At1 / At2 shortened the duration of the dosing pulse At1 for the subsequent dosing pulse in the first case and extended in the second case. This control measure 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.

The control measure according to the invention thus consists essentially in the fact that the duration of the metering pulse At1 and the time interval of adjacent metering pulses At2 are selected such that at the respective end of the interval of adjacent metering pulses At2 the time-dependent current consumption I (t) for stirring and / or or shearing and homogenizing of the temporarily present mixed product to the reference current absorption l ₀ , which is required for the relevant treatment of the homogenized mixed product, within a practically acceptable tolerance. Second procedure

With regard to a second 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 an in-line mixing process, which also classifies as a multi-pass process or a multi-stage process becomes. The multi-pass process is typically used for blended products which ultimately have a higher dry matter concentration and / or a higher viscosity, for example when larger amounts of powdered material need to be emulsified with oil, gum or flavors, because these blended products are mixed with the single pass feedstock. Method can not be displayed. In this case, the introduction and treatment of the powdery substance, kinetic reaction takes place, again, as in the first method, almost under the conditions of a residence time behavior of a continuously operating homogeneous reaction vessel.

The second method is characterized in a conventional manner in such a way that presented in a first phase liquid in a mixing vessel and this liquid, the powdery substance is fed discontinuously, at the end of the first phase, a dry matter concentration is reached, which is below one for the End of the entire mixing process predetermined final value is. The liquid and the powdery substance are continuously stirred in the first phase and / or mixed to a mixed product and the mixed product is homogenized. In a second phase, the mixed product obtained in the first phase is recirculated through the mixing tank and it is further supplied to the recirculated amount of mixed product corresponding amounts of powdered material discontinuously. Accordingly, in the second phase at constant level level, the mass balance is designed according to the continuity condition in such a way that the mass flow of mixed product discharged from the mixing process corresponds to the mass flow mixed product passing through the recirculation plus the metered flow rate of pulverulent substance.

The mixed product is recirculated 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.

In the case of the mixing method in question, a formulation of the mixed product is predetermined in each case in the form of default data, at least with regard to the time-dependent course of a dry substance concentration assigned to the predetermined end value.

The inventive idea of solution in the second method is that the discontinuous supply of the pulverulent substance is known in a manner known per se. se pulse manner is carried out by a temporal sequence of dosing pulses. In this regard, in a preferred embodiment and appropriate to the first method, the reaction conditions provide for the powdery substance to be sucked in through a negative pressure (vacuum) in the headspace of the mixing container relative to atmospheric pressure. The metering pulses are each characterized by a flow rate of the powdered substance rh _P , a time duration of the metering pulse Et1 and a time interval of adjacent metering pulses At2.

The multi-stage sequence in the second phase of the second method results in a time-dependent course of a dry matter concentration c (t), which ends according to plan in the predetermined end value, being between the course of a dry matter concentration without saturation character (approximately linear course) or Saturation character (degressive course) is to be distinguished.

»In the course without saturation character equal amounts of powdered material can be dosed within the absorption capacity or the solubility limit of the liquid at equal intervals, so that upon complete homogenization of the mixed product sets a time-dependent approximately linearly increasing course of a dry matter concentration. · In the course of saturation character, only steadily decreasing amounts of powdery substance can be metered at equal intervals within the absorption capacity or the solubility limit of the liquid so that a time-dependent decreasing progression of a dry matter concentration occurs with complete homogenization of the mixed product.

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 Gaussian normal distribution, if a defined amount of powdered Pululsweise substance introduced and treated in the mixing process or the mixing container.

As soon as the powdery substance in the receiving liquid (first phase) and in the receiving mixed product (second phase) evenly distributed, that is distributed as homogeneously as possible and optionally dissolved, sounds the time-dependent current consumption l (t), namely on a time-dependent course a reference current consumption l ₀ (t), which is characteristic of the homogenized mixed product under the conditions of the associated time-dependent course of a dry matter concentration c (t) to be provided stirring and / or shearing and homogenizing performance. The relevant course of a 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 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 , the duration of the dosing pulse At1 for the subsequent dosing pulse is shortened in the first case and extended in the second case.

For time-dependent courses of a dry matter concentration without saturation character, a first embodiment of the second method provides that these runs 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 (V = At1 / At2 = constant).

The respective course of a dry matter concentration c (t) increases over time t, because the continuous pulse-wise metered flow of the pulverulent substance m _P , which in the most general case is a time-dependent flow rate pulp-shaped substance m _P (t) is constant over the entire time t of the mixing process (rh _P = constant). The mass flow of powdery substance m _P is in the period t often many times, and (t / At2) times, with approximately unchangeable Chem level level in the mixing vessel in an invariable amount of liquid ITIF of the present mixed product, wherein the time-dependent curve of a dry matter concentration according to equation (2), as follows is: c (t) = (2) m _F + mp- Atl

In most practice-relevant cases, since the first term of the subsequent relation is usually small compared to the second term, approximately t

rp-bxl «m _F

be set so that, according to equation (2a) for the time-dependent curve of a dry matter concentration c (t) with a first proportionality constant kl = - approximately results:

m

c _(t) * ίϋέ £ ϋ ₌ ίήΡ Atl _{t =} mp _{yt = kl vt (2a)} J m _F mp At2 m _F '

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

For time-dependent courses of a dry matter concentration with saturation character, a second embodiment of the second method provides that these courses are defined by a variable time-interval ratio V between the duration of the metering pulse At1 and the associated time interval of adjacent metering 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, the time-duration 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 predetermined tolerance downwards, the time-duration interval ratio V is increased. The respective course of a dry matter concentration c (t) is increasing over time t degressively, because the continuous pulse-wise metered flow rate of the powdery substance m _P , seen over the entire time period t of the mixing process, while constant (r _P = constant), However, the duration of the metering pulse At1 steadily decreases and thus a steadily decreasing amount of powdered material is metered. The flow rate of powdered material m _P is introduced in the period t at an almost constant level in the mixing vessel in a present almost invariable volume of the mixed product V _M (VM "constant), wherein a density P of the mixed product according to the time-dependent course of a dry matter concentration c ( t) increases and the latter is represented by equation (3) with a second proportionality constant k2 = -, as follows:

This control measure with a variable time-to-interval ratio V requires the controller the ability to shorten or lengthen the duration of the metering pulse At1 with constant time interval of adjacent metering pulses .DELTA.2 or, with unchanged duration of the metering pulse At1 the time interval of adjacent metering pulses Adequately lengthen or shorten At2.

The control measure according to the invention therefore essentially consists in both embodiments of the second method in that the duration of the metering pulse At1 and the time interval of adjacent metering pulses At2 are selected such that the current-dependent current consumption l (t) determined at the respective end of the interval of adjacent metering pulses At2 for stirring and / or shearing and homogenizing 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. The second method, which is primarily suitable for concentrating the dry matter concentration to a predetermined final value, comprises dividing the recirculated mixed product into a first portion and a second portion, feeding the first portion directly to the mixing process, and the complementary second portion passed over a storage volume and then also fed to the mixing process. This division offers the possibility, as suggested, to adjust the first fraction recirculated immediately above the mixing process between zero and one hundred percent of the recirculated mixed product. Such a configuration and mode of operation offers the possibility of concentrating smaller amounts of the desired mixed product exclusively in the mixing container at a maximum possible first proportion (100%). Large quantities of mixed product are recirculated and concentrated with a large second proportion over correspondingly large storage volumes, wherein the distribution ratio can be chosen such that the first portion, which is recirculated directly through the mixing process, the mechanical stirring and / or shear installed in this mixing process - And homogenizing mechanisms complemented by fluidic mechanisms of action and intensified.

First and second procedures

In order to make the metering of the powdery substance as trouble-free as possible, it is proposed for the first and the second method that the flow rate of the powdery substance over the period 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 assumes only either a full open position or a closed position.

In order to make the control of the mixing process as manageable, another embodiment provides for both method that the shortening or extension of the duration of the metering pulse then takes place when a by a permissible current exceedance or a permissible current underflow each determined Stromkorridor by an upward deviating power consumption or a downward deviating power consumption is left. The permissible current overshoot and the permissible current undershoot are each by a percentage of the associated reference current consumption or the associated time-dependent course of a reference current consumption determined. 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 reference current consumption or the associated time-dependent course of a reference current consumption.

In order to make operational data obtained in practice for a specific recipe usable for subsequent mixing processes having the same formulation, another embodiment provides for both methods that the control of the introduction of the powdered substance into the further recipe-dependent specification data underlying at least one liquid is based on empirical values Previous mixing processes are obtained and stored, these Vorga- a flow rate of the at least one liquid, a mixing or solution temperature (reaction temperature), a pressure above the liquid column, from which a reaction pressure results, speeds of means for stirring and / or shearing and Homogenize and one of the associated reference current consumption or the associated time-dependent course of a reference current consumption dependent allowable current exceedance and a permissible current underrun.

In order to make operational data obtained in practice for a specific recipe usable for subsequent mixing processes having the same formulation, another embodiment provides for both methods that the target-oriented recipe-dependent control parameters obtained during the control of the introduction of the pulverulent substance into the at least one liquid, namely, the duration of the metering pulse and the time interval between adjacent metering pulses, stored and used for subsequent control of the same recipes.

Mixing devices (first and second method)

A mixing device for carrying out the first method consists, in a manner known per se, of a mixing container which has an inlet connection for the supply for a liquid, a discharge nozzle 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 can be adjusted with the valve closing element either between completely closed (closed position) or completely open (open position). A powdery substance is introduced into the liquid with the inlet valve, wherein the valve closure member can be transferred into the closed position or into the open position by means of a control device associated with the inlet valve. According to the invention, the control device of the mixing device provides formulation-dependent default data and recipe-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 controls the closing or the open position of the valve closure member as a function of the time-dependent current consumption and in relation to the default data and the control parameters.

A mixing device for carrying out the second method is constructed substantially adequately to the mixing device for carrying out the first method. The difference results from the task underlying the second method, by recirculation of the mixed product to achieve the greatest possible concentration of small to largest amounts of mixed product with pulverulent material. For this purpose, a constructive supplement to the mixing device in the form of a circulation line is provided which branches off from a line connected to the outlet connection and opens directly into the mixing container.

To the designed as a lift valve inlet valve that supplies the powdered material only in its full open position and thus minimizes the risk of clogging from the outset, even further to optimize in this regard and, for example, dead and cavities in the powder-exposed area of the valve To avoid housing the inlet valve, provides an advantageous embodiment that the valve closing member is formed at least in its powder-loaded area as a diameter-equal cylindrical rod on 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. While the invention is embodied in various embodiments of a first and a second method for controlling the introduction of a pulverulent substance into a liquid consisting of at least one component for an inline mixing process, in the drawing a preferred first and second method and a Blending device for performing the respective method described. 1 shows a schematic representation of a mixing device for an in-line mixing method, which is operated as a first method, a so-called one-pass method;

1a shows a schematic representation of a mixing device for an in-line mixing method, which can be operated as a second method, a so-called multi-pass method;

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

Supply of the powdery substance in mixing devices according to Figures 1 and 1a without a control head housing; FIG. 3 is a qualitative representation for the first method of a time-dependent current consumption l (t) for a sequence of dosing pulses with a constant duration of the dosing pulse At1 and with a time interval of adjacent dosing pulses At2;

4 is a qualitative representation of the first method, a time-dependent current consumption l (t) for a sequence of metering pulses with a constant duration of the metering pulse At1 / 2 and with a time interval of adjacent metering pulses At2 / 2;

5 shows a qualitative depiction for the second method of a time-dependent current consumption l (t) for a 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) and Figure 6 in a qualitative representation for the second method, a time-dependent current consumption l (t) for a sequence of dosing pulses with a steadily decreasing duration of the dosing At1 and with a constant time interval of adjacent Dosierimpulse At2 to realize a time-dependent degressive course a desiccant concentration (with saturation character).

Mixing device for first method (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 100.4 for a mixed product M, which is removed with a mixed flow rh _M. The mixing tank 100 is fed via a feed port 100.5 a liquid F with a flow rate liquid m _F , which forms a free level N, above the usually in the subject mixing device 1000 (vacuum mixer), a pressure above the liquid column p, a negative pressure opposite atmospheric pressure, prevails. On the container shell 100.1 or the lower container bottom 100.3 an inlet valve 20 is arranged. The inlet valve 20 is used for the discontinuous supply of a powdered substance P with a mass flow of powdered material m _P , which is supplied via a feed 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 action can also be achieved by means of fluidics, for example by pumping the liquid F or the mixed product M via a circulation line, not shown in FIG. 1, or a circulation line 28 having a preferably tangential inlet of the liquid F or the mixed product as shown in FIG M in the mixing container 100, reached or supported.

In the following, if the statement is reduced to liquid F for the sake of simplicity, the mixed product M, if this is true, should be read and vice versa. 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 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 forms an outwardly inwardly directed circulation flow in the mixing vessel 100. When passing through the shearing and homogenizing device 26, liquid F and powdered substance P or the resulting mixed product M are very intensively mechanically mixed and preferably homogenized.

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 his end-side valve plate 8a and the associated seat seal 10 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, for example, the volume flow liquid rh _F , the pressure above the liquid column p in the mixing tank 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 shown in FIG. 1 by way of example for the time-dependent current consumption l (t). of the second drive motor 50 of the shearing and homogenizing device 26. In an analogous manner, additional or alternative further measuring devices can be provided which determine the other mixing parameters.

Mixing device for the second method (FIGS. 1a and 2)

A mixing device 1000 for the second method differs from that for the first method only in that a circulation line 28 is provided, which branches off from a line connected to the outlet connection 100.4 and directly into the mixing vessel 100, preferably via its own recirculation port 100.6, opens , The line connected to the outlet connection 100.4 can be guided via one or more storage containers and finally connected to the inlet connection 100.5. These structural measures serve procedural purposes, which have already been explained above. In order to avoid repetition, a complete description of the mixing device 1000 according to FIG. 1a is dispensed with and reference is made to the description of FIG. 1 in this regard.

First method (FIGS. 3 and 4 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 continuously operating homogeneous reaction vessel. It will be the liquid F via the inlet port 100.5 with the flow rate liquid m _F , which can be a time-dependent flow rate liquid (m _F (t)) in the most general case, and the powdered substance P via the inlet valve 20 discontinuously with the flow rate powdered substance m _P , in the In the most general case, a time-dependent flow rate of pulverulent substance (m _P (t)) may also be supplied to the mixing process in the mixing vessel 100, the target being the predetermined, unchanging, dry matter concentration c of the pulverulent substance P in the liquid F. The liquid F and the powdery substance P are continuously stirred and / or mixed to the mixed product M and the mixed product M is homogenized. The mixed product M is discharged continuously in accordance with the supplied amounts of liquid F and powdered substance P with the flow rate mixed product m _M. There are a recipe of the mixed product M at least with regard to the predetermined dry matter concentration c 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-wise by a chronological sequence of metering pulses i (FIGS. 3 and 4) which respectively characterize the flow rate of the pulverulent substance m _P , a duration of the metering pulse At1 and a time interval of adjacent metering pulses At2 are. The flow rate of the powdery 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 of a time-independent and thus constant flow rate powdered material m _{P is} assumed (rh _P = constant). According to equation (1), the predetermined constant dry matter concentration c is defined by a likewise fixed, ie constant time-to-space ratio V between the duration of the metering pulse At1 and the associated time interval of adjacent metering pulses At2 (V = At1 / At2 = constant ).

For the duration of the metering pulse At1 according to FIG. 3, the shearing and homogenizing device 26, for example, is connected to the second drive motor 50 in the same way. if, in FIG. 3, the time-dependent current consumption l (t) applied over the corresponding time duration t is determined or measured. The latter is proportional to a mixing and / or shearing and homogenizing power (FIG. 1) required for a mixing product M * temporarily present in the mixing container 100 immediately after the metering pulse i, which is produced by the stirring and / or shearing and homogenizing Device 24, 26 is applied at this stage of the treatment. 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 powdery substance rp, reaches a maximum, and then after dissolution of the powdered substance P, ie at a then achieved homogenized mixed product M to gradually decrease to an initial value.

According to the invention, this typical behavior is utilized in terms of control technology in that a reference current consumption I _{0 is} used which is characteristic of 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 upwardly-differing current consumption I * (t) is measured, so that in this state of the temporarily present mixed product M * at the end of the interval of adjacent metering pulses At2 a renewed metering 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 stirring and / or shearing and homogenizing phase also defined by the interval between adjacent metering pulses At2 is excessively long or that no adequate amount of powdered substance mp has been metered into this phase. The method described above assumes that the process according to the invention takes account of the fact that, at the end of the interval between adjacent metering pulses At2 and deviation of the time-dependent current consumption l (t) from the time-independent and thus constant reference current consumption l ₀ (l ₀ = constant) by more than one given tolerance, either upwards or down, and in compliance with the fixed time-distance ratio V (V = At1 / At2 = constant) 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. The tolerance consists in a specification of a permissible current overshoot AM and in a permissible current undershoot ΔΙ2 (FIG. 3).

The case of the shortening is illustrated in FIG. 4, whereby in the illustrated case example the time duration of the metering pulse At1 and thus also the assigned period of adjacent metering pulses At2 were halved by way of example (At1 / 2; At2 / 2). In this dosing mode, again, at the end of the period of adjacent dosing pulses At2 / 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, which is a necessary correction in the sense described above is required.

The shortening or the extension of the duration of the metering pulse At1 takes place when a current corridor determined by the permissible current excess ΔΙ1 or the permissible current shortage ΔΙ2 is determined by the time-dependent current consumption l * (t), l ** (t) deviating upwards or downwards. is left. The permissible excess current and the permissible current undershoot AM, ΔΙ2 are preferably each determined by a percentage of the associated reference current consumption l ₀ . Furthermore, the degree of shortening or extension of the duration of the metering pulse At1 is preferably determined as a function of the degree of deviation of the time-dependent current consumption l (t) from the associated reference current consumption l ₀ . The permissible excess current AM, which is ultimately determined by the respective recipe of the mixed product M, and the permissible current shortage ΔΙ2 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 in the at least one liquid F obtained targeted recipe-dependent control parameters S, namely the duration of the metering pulse ΔΜ and the time interval of adjacent metering pulses At2 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.

Second Method (FIGS. 5 and 6 in conjunction with FIGS. 1a and 2) In order to avoid repetition, in the following description of figures for the second method in its two embodiments only those solution features are used in which the second differs from the first method , Otherwise, reference is made to the description of the figures for the first method. The introduction and treatment of the powdery substance P takes place under the reaction kinetic conditions of a residence time behavior of a continuously operating homogeneous reaction vessel. In a first phase, liquid F is introduced into the mixing container 100 (feed via the feed connection 100.5) and the powdered substance P is fed discontinuously to this total introduced liquid F via the inlet valve 20 with the mass flow of pulverulent substance m _P , at the end of the first Phase a dry matter concentration c is reached, which is below a predetermined end of the entire mixing process final value c _E. The liquid F and the powdery substance P are continuously stirred by means of the stirring device 24 and / or mixed by means of the shearing and homogenizing device 26 to the mixed product M and the mixed product M is homogenized.

In a second phase, the mixed product M obtained in the first phase is recirculated via the mixing tank 100 and it is further recirculated Amount of mixed product M corresponding amounts of powdered substance P fed discontinuously. The amount of mixed product M discharged into the recirculation can be divided into a first portion a and a second portion b ((a + b) M). Accordingly, in the second phase at constant level N, the mass balance is necessarily based on the continuity condition. The mixed product M is recirculated 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 the predetermined final value CE. In the mixing method in question, a formulation of the mixed product M are predetermined at least in terms of the time-dependent course of a dry matter concentration c (t) assigned to the predetermined end value CE and the reaction conditions in each case in the form of the default data D. The inventive idea of solution corresponds in essential features to that according to the first method. The multi-stage sequence in the second phase of the second 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 course of a dry matter concentration c (t) without saturation character 5) or with a saturation character (degressive time-dependent progression, see FIG. The time-dependent course of a dry substance concentration c (t) ending in the predetermined final value c _E is defined by the sequence of specific metering pulses i, ie uniquely determined by the duration of the metering pulse At1 and the interval of adjacent metering pulses At2.

As soon as the powdery substance P has uniformly distributed in the receiving liquid F (first phase) and in the receiving mixed product M (second phase), ie distributed as homogeneously as possible and possibly dissolved, the time-dependent current consumption l (t) decays, namely on a time-dependent course of a reference current consumption l ₀ (t), which is characteristic of the homogenized mixed product M under the conditions of the associated time-dependent course of a dry matter concentration c (t) to be provided agitating and / or shearing and homogenizing Performance (see Figure 5: approximately linear time-dependent Course of a reference current consumption l ₀ (t); Figure 6: degressive time-dependent course 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 liquid F is present, with an initial value l ₀ (t = 0) = lo (see FIGS. 5, 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 FIGS. 5, 6), the duration of the dosing pulse At1 for the subsequent dosing pulse is shortened in the first case and longer in the second case!

For a time-dependent course of a dry matter concentration c (t) without saturation character, starting at c (t = 0) = 0 for the pure liquid F (Figure 5), as can be described by the above equations (2, 2a) (c (t) = k1 V t), an embodiment of the second method provides that this course is defined by a fixed 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 = 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 according to the invention at constant time-interval ratio V (as qualitatively shown by way of example in FIG. 4 in contrast to FIG. 3) or extended. This control measure with a fixed time-interval ratio V 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 i. For a time-dependent course of a dry matter concentration c (t) with saturation character (Figure 6), as it can be described by the above equation (3) (c (t) "k2 ^Σί = ° ^Δί1 ), sees a further embodiment of MW

In the second method, this profile 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)

• 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), decreasing progressively, because the continuous pulsed metered mass flow of the powdery substance m _{P> is seen} over the entire time 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 flow rate of powdered material m _P is introduced in the period t of the entire mixing process at approximately constant level N in the mixing vessel 100 in a present almost invariable volume of the mixed product V _M (V _M »constant), with a density P 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 matter concentration c (t), how the respectively metered quantity of pulverulent substance mp = riipAtl steadily decreases, with the associated time-dependent current flow At the end of the time interval between adjacent metering pulses At2, the pickup l (t) has approximated to the associated time-dependent course of a reference current pickup I ₀ (t) or is largely congruent therewith. 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 ΔΜ, ΔΙ2 occur, the control mechanisms, as described for the first method in connection with FIGS. 3 and 4, apply mutatis mutandis.

These control measures with a variable time-interval ratio V require the control device 30 to be able to shorten or lengthen the duration of the metering pulse At1 with a constant interval of adjacent metering pulses Δί2 or, if the metering pulse At1 has not changed, the interval between adjacent metering pulses Δί2 adequately extend or shorten.

The control measures according to the invention thus consist essentially in both embodiments of the second method in that the time duration of the metering pulse At1 and the interval between adjacent metering pulses .DELTA..2 are selected so that at the respective end of the interval of adjacent metering pulses .DELTA.2 the time-dependent determined power consumption l (t) for stirring and / or mixing and homogenizing the temporarily present mixing 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, 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

00.3 lower tank bottom (conical, cone-shaped)

100.4 outlet nozzle

100.5 inlet connection

100.6 recirculation 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

28 circulation pipe

D default data

F liquid l ₀ Initial value of a reference current consumption

(for the homogenized mixed product M; l ₀ (t = 0) = l ₀ ) 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 shortfall M mixed product

M * temporary mixed product

N level level

P powdery substance

S control parameters

T mixing or solution temperature

V Time-distance ratio (V = At1 / At2) V _M Volume of the mixed product Density of mixed product a first fraction (immediate recirculation)

b second fraction (indirect recirculation) c dry matter concentration (powdered substance P in the liquid F) c (t) time-dependent course of a dry matter concentration

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

i dosing pulse k constant (k = ^) k1 first proportionality constant (k1 = - itip) k2 second proportionality constant (k2 «-)

"M

m _F amount of liquid

rh _F flow of liquid

m _F (t) time-dependent flow rate liquid

m _M mass flow of mixed product

m _P amount of powdered substance

riip flow rate powdered substance

rhp (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 an in-line 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 continuously operating homogeneous reaction vessel,

o that the liquid (F) continuously and the powdery substance (P) are discontinuously fed to a mixing container (100), the target a predetermined, fixed time constant dry matter concentration (c) of the powdery substance (P) in the liquid (F) is

o that 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 and

o that the mixed product (M) according to the amounts supplied

Liquid (F) and powdered substance (P) is continuously discharged,

In which a formulation of the mixed product (M) at least with regard to the predetermined dry matter concentration (c) and the reaction conditions in each case in the form of default data (D) are given,

In which the discontinuous supply of the pulverulent substance P is effected in a pulse-wise manner by a chronological sequence of metering pulses i), which are in each case represented by a flow rate of the pulverulent substance (rh _P ), a duration of the metering pulse (At1) and a time interval between adjacent metering pulses ( At2) are characterized

In which the predetermined dry matter concentration (c) is defined by a fixed 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 = constant), In which 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 *),

In which from the default data (D) is a reference current consumption (l ₀ ) is used, which is characteristic of the homogenized mixed product (M) to be provided stirring and / or shearing and homogenizing power, and

• at the end of the interval between adjacent metering pulses (Et 2) and deviation of the time-dependent current consumption (l (t)) from the reference current consumption (l ₀ ) by more than a predetermined tolerance, either up or down, and in compliance the fixed time-interval ratio (V) the duration of the dosing pulse (At1) for the subsequent dosing pulse (i) in the first case is shortened and extended in the second case.

Method for controlling the introduction of a powdery substance (P) into a liquid (F) consisting of at least one component for an in-line mixing process,

o that in a first phase liquid (F) presented in a mixing vessel (100) and this liquid (F) of the powdery substance (P) is fed discontinuously,

o that 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,

o that in a second phase, the mixed product (M) obtained in the first phase is recirculated via the mixing vessel (100) and further, the recirculated amount of mixed product (M) corresponding amounts of powdered material (P) are fed discontinuously, and o that the mixed product (M) is recirculated until a time-dependent course of a dry matter concentration (c (t)) of the puiverformigen substance (P) in the mixed product (M) to a predetermined final value (CE) has grown,

• and in which a formulation of the mixed product (M) is predetermined in each case in the form of default data (D), at least with regard to the time-dependent course of a dry matter concentration (c (t)) assigned to the predetermined end value (CE),

characterized,

• that the discontinuous feeding of the powdery substance (P) is effected in a pulse-wise manner by a time sequence of metering pulses (i) which are respectively represented by a mass flow of the powdery substance (m _P ), a duration of the metering pulse (At1) and a time interval between 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 from the default data (D) a time-dependent course of a reference current consumption (l ₀ (t)) is used, which is characteristic of the homogenized mixed product (M) under the conditions of the associated time-dependent course of a dry matter concentration (c (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 respective 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.

3. The method according to claim 2,

characterized,

that time-dependent curves of a dry matter concentration (c (t)) without a saturation character are defined by a fixed 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 = constant).

4. The method according to claim 2,

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

• 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 distance ratio (V) is reduced and

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

5. The method according to any one of the preceding claims,

characterized,

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

6. The method according to any one of the preceding claims,

characterized,

that the shortening or the extension of the duration of the metering pulse (At1) takes place when a current corridor determined by a permissible excess current (AM) or a permissible current shortfall (ΔΙ2) is determined by an upwardly deviating current consumption (l * (t)) or a downwardly deviating current consumption (l ** (t)) is left, wherein the permissible current overshoot and the permissible current undershoot (ΔΙ1, ΔΙ2) are respectively represented by a percentage of the assigned reference current consumption (l ₀ ; l ₀ (t) ) are determined.

7. The method according to any one of the preceding claims,

characterized,

the degree of shortening or lengthening of the duration of the metering pulse (At1) as a function of the degree of deviation of the time-dependent current consumption (l (t), l * (t), l ** (t)) from the assigned reference current consumption (l ₀ ; l ₀ (t)) is determined.

8. The method according to any one of the preceding claims,

characterized,

in that the further formula-dependent specification data (D) on which the powdery substance (P) is introduced into the at least one liquid (F) is obtained and stored from empirical values of earlier mixing processes, whereby this specification data (D)

A mass flow of the at least one liquid (ih _F ),

A mixing or solution temperature (T),

A pressure above the liquid column (p),

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

• a permissible excess current (ΔΙ1) dependent on the assigned reference current consumption (l ₀ ; l ₀ (t)) and a permissible current undershooting (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

• the duration of the dosing pulse (At1) and

• the interval between adjacent dosing pulses (At2)

stored and used for subsequent control of the same recipes.

Method according to claim 2,

characterized,

that the recirculated mixed product (M) is divided into a first portion (a) and a second portion (b),

that the first portion (a) is fed directly to the mixing process and that the complementary second portion (b) is passed over a storage volume and then also fed to the mixing process.

11. The method according to claim 10,

characterized,

the first fraction (a) is between zero and one hundred percent of the recirculated mixed product (M).

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 ) is adjustable either between completely closed (closed position) or fully open (open position), with the inlet valve (20), through which a powdery substance (P) is introduced into the liquid (F), with an inlet Valve (20) associated control device (30), with which the valve closure member (8) can be converted into the closed or in the open position,

characterized,

• that the control device (30) provides formulation-dependent default data (D) and recipe-dependent control parameters (S) in the form of the duration of the metering pulse (At1) 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) controls 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).

13. A mixing device for carrying out the method according to claim 2 with the features of claim 12,

characterized,

a circulation line (28) is provided which branches off from a line connected to the outlet connection (100.4) and opens directly into the mixing container (100).

14. Mixing device according to claim 12 or 13,

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.