EP3638411B1 - Method and mixing device for controlling the introduction of a pulverulent material into a liquid for an inline mixing method - Google Patents

Description

TECHNICAL AREA

The invention relates to a first method for controlling the introduction of a powdery substance into a liquid consisting of at least one component for an inline mixing process according to independent claim 1 and a corresponding second method according to the preamble of independent claim 2, in which the introduction and treatment of the powdery Substance takes place under the reaction kinetic conditions of a residence time behavior of a continuously operating homogeneous reaction vessel, as well as a mixing device for carrying out the respective process.

STATE OF THE ART

With a view to the introduction of a powdery substance into a liquid and its uniform distribution and, if necessary, dissolution in the liquid, mixer technology knows mixing processes that are operated intermittently (so-called batch process) or continuously (so-called inline process).

In the batch process, the mixing of liquid and powdery substance is carried out kinetically in a so-called discontinuously operated reaction vessel (mixing vessel). A certain amount of liquid is placed in the mixing container and powdery substance is added until a desired or systematically predetermined dry substance concentration of the powdery substance is present in the liquid. Powdered 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 uniformly distributing the powdery substance. The powdery substance can be fed in continuously or discontinuously.

In the inline process, the mixing of liquid and powdery substance is kinetically reactive in a so-called continuously operated reaction vessel (Mixing tank) carried out. A distinction is made between a single-pass and a multi-pass process. In the single-pass process, liquid and powdery substance, the latter either continuously or discontinuously, is continuously fed to the mixing container, and a mixed product is continuously discharged from the mixing container in accordance with the supplied amounts of liquid and powdery substance. Stirring and / or mixing or shearing and homogenizing ensure, according to the theoretical postulate, 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 unchanged over the duration of the mixing process.

In the case of the multi-pass process, a mixed product produced in a first phase and corresponding to the single-pass process is recirculated through the mixing container in a second phase, with pulverulent material still being fed in either continuously or discontinuously. The mixed product is recirculated until it has a dry matter concentration that has grown to a predetermined end value. With regard to the recirculation, various forms of the method are known which provide that the entire mixed product discharged from the mixing container is either passed directly through the mixing process again or first passed through a storage volume and then likewise fed back into the mixing process. Any distribution ratios can be implemented between these two forms.

The present invention deals exclusively with mixing processes which are operated in the inline process and here in all possible forms (single pass and any variants of the multiple pass process). Mixing methods in this regard and the associated mixing devices were made known to the public, for example, at the following Internet link: "http://www.gea.com/de/products/High-Shear-Inline-Mixer.jsp".

the U.S. 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 in a controlled manner Quantities fed into a flow mixer and mixed there with one another. 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 supply of liquid takes place as a function of this measurement, the regulation of the supply of solids comprising separate control means.

The above-mentioned mixing devices preferably also include 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 in the mixing container can, for example, have a free fill level with a height of between 0.4 and 4 m, is subject to a negative pressure corresponding to this height range compared to atmospheric pressure of, for example, 0.2 to 0.8 bar, so that the Liquid can on the one hand be freed from gas components more easily during the mixing process and on the other hand has a negative pressure compared to atmospheric pressure in the bottom area of the mixing container under all operating conditions. The powdery substance is introduced into the mixing container 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, for example, to a powder storage container is connected. The inlet nozzle and thus the pipeline can be shut off via an inlet valve that controls the supply of the powdery substance, so that, on the one hand, the mixing device is closed off from its surroundings via this path and, on the other hand, an amount of the powdery substance in the powder storage container is automatically fed to the liquid if necessary due to the prevailing pressure conditions can be. A related mixing device with a preferably discontinuous supply of the powdery substance is in the document DE 10 2015 016 766 A1 described.

A discontinuous supply of the powdery substance, as for example in the DE 10 2015 016 766 A is disclosed, has the advantage that the supply always takes place via the fully open position of the inlet valve designed as a lift valve and thereby the risk of clogging of the inlet valve is minimized. Addicted from the duration of the respective open position, more or less large amounts of the powdery substance are introduced into the liquid in bursts, so that there is basically the risk that there will be corresponding agglomerations of the powdery substance, which are caused by the stirring and / or shearing and homogenizing The device must be completely dissolved until the subsequent entry of powdery substance, while at the same time striving for as uniform a distribution of the powdery substance as possible. In this context, it has been shown that the intermittent supply of the powdery substance is reflected in an increase in the stirring and / or shearing and homogenizing power (drive power for the associated devices), which is necessary to achieve this in this phase of the mixing process to treat temporarily present mixed product. The course of the related drive power, which is proportional to the current consumption of the assigned drive motors, corresponds approximately to a Gaussian normal distribution curve.

What makes the mixing process even more difficult is the fact that the residence time behavior of a continuously operated reaction vessel or mixing vessel theoretically postulates the same composition of the mixed product at every point, but in practice, reinforced by the operational discontinuous supply of the powdery substance, it leads to different residence times of the inhomogeneously distributed agglomerations of the powdery substance can come.

On the one hand, therefore, it cannot be ruled out that more or less large agglomerations, which leave the mixing container after a below-average residence time, do not completely dissolve and persist in the mixed product. Due to the above-described inhomogeneities of the powdery substance in the mixed product, there is also the risk of microbiological growth (germ growth), which is promoted in particular when the mixing container is heated and the inhomogeneities may remain in the mixing container for an above-average time under these thermal conditions . In addition, under the last-mentioned conditions, deposits (so-called product fouling) are increasingly formed on the heated walls of the mixing container, which on the one hand promote heat transfer and on the other hand shortens the service life of the mixing container until the next cleaning cycle.

DE 103 45 161 A1 also discloses a prior art method.

Since until now there has been a lack of targeted control mechanisms to avoid inhomogeneities with regard to the distribution and degree of dissolution of agglomerations of the powdery substance and disproportionately large fluctuations in the supply of the powdery substance and to prevent the mixing device from being blocked due to excessive dry substance concentration in the mixing container, so far In order to act supposedly on the safe side, with 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 necessary over long periods of time. On the one hand, this too intensive treatment can have a damaging effect on the product and, on the other hand, it is not energy-efficient.

The object of the present invention is to develop two generic methods for controlling the introduction of a powdery substance into a liquid consisting of at least one component for an inline mixing process 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

From a procedural point of view, this object is achieved by a first method with the features of independent claim 1 and by a second method with the features of independent claim 2. Furthermore, the object is achieved in terms of device technology by a mixing device for performing the respective method with the features of claims 12 and 13, respectively.

First procedure

With a view to a first method according to the invention, the invention is based on a method for controlling the introduction of a powdery substance into a liquid consisting of at least one component for an inline mixing method, where the term “component” is to be understood in such a way that it can generally involve discrete liquids that are separate from one another and that can also be fed to the mixing process separately from one another. This first process, a so-called single-pass process or a single-stage process, is typically used for the production of low-viscosity base sludge with a low dry matter concentration or, for example, for skimmed milk powder in water or cocoa powder in milk or, more generally, when a powdery substance with good solubility in needs to be resolved in a short time. In this case, the introduction and treatment of the pulverulent substance, from a reaction kinetic point of view, takes place under the conditions of a residence time behavior of a continuously operating homogeneous reaction vessel, namely in such a way that the liquid is fed continuously and the pulverulent substance discontinuously to a mixing container, the goal being a predetermined time constant dry matter concentration of the powdery substance in the liquid. The liquid and the powdery substance are continuously stirred and / or mixed to form a mixed product and the mixed product is homogenized. As a rule, the treatment processes "stirring", in which no or only a very low mechanical force is applied to the mixed product, and "mixing", in which a significant shear force is applied to the mixed product and therefore the "mixing" in this regard as well is classified as "shearing", with "homogenizing" mostly being an integral part of mixing. The mixed product is continuously discharged according to the added amounts of liquid and powdery substance. In the case of the mixing process in question, a recipe for the mixed product is given, at least with regard to the given dry matter concentration, and the reaction conditions are given in each case in the form of default data.

The idea of the solution is that the discontinuous supply of the powdery substance takes place in a manner known per se in pulses by a time sequence of metering pulses. In a preferred embodiment, the reaction conditions provide that the powdery substance is sucked in by a negative pressure (vacuum) in the head space of the mixing container compared to atmospheric pressure. The dosing pulses are each caused by a mass flow of the powdery substance ṁ _P , a duration of the dosing pulse Δt1 and a time interval between adjacent dosing pulses Δt2.

ist die vorgegebene Trockenstoff-Konzentration c nach Gleichung (1) definiert, wobei im allgemeinsten Falle der Mengenstrom des pulverförmigen Stoffes ṁ_P ein zeitabhängiger Mengenstrom pulverförmiger Stoff ṁ_P(t) und ein Mengenstrom Flüssigkeit ṁ_F ein zeitabhängiger Mengenstrom Flüssigkeit ṁ_F(t) sind: $$\mathrm{c}=\frac{{\stackrel{.}{\mathrm{m}}}_{\mathrm{P}}\left(\mathrm{t}\right)\mathrm{\Delta }\mathrm{t}1}{{\stackrel{.}{\mathrm{m}}}_{\mathrm{F}}\left(\mathrm{t}\right)\mathrm{\Delta }\mathrm{t}2}=\mathrm{k}\frac{\mathrm{\Delta }\mathrm{t}1}{\mathrm{\Delta }\mathrm{t}2}=\mathrm{k}\mathrm{V}=\mathrm{konstant}$$

By means of a fixed time duration / time interval ratio V between the duration of the metering pulse Δt1 and the assigned time interval Δt2 between adjacent metering pulses $\left(\mathrm{V}=\frac{\mathrm{<figure-callout\; id="1"\; label="\Delta \; t"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">\Delta </figure-callout>}\mathrm{t}\mathrm{}1}{\mathrm{<figure-callout\; id="2"\; label="\Delta \; t"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">\Delta </figure-callout>}\mathrm{t}\mathrm{}2}=\mathrm{constant}\right)$

the specified dry matter concentration c is defined according to equation (1), whereby in the most general case the mass flow of the powdery substance ṁ _{P is} a time-dependent mass flow of powdery substance ṁ _P (t) and a mass flow of liquid ṁ _{F is} a time-dependent mass of liquid ṁ _F (t) are: $$\mathrm{c}=\frac{{\stackrel{.}{\mathrm{m}}}_{\mathrm{P.}}\left(\mathrm{t}\right)\mathrm{\Delta }\mathrm{t}1}{{\stackrel{.}{\mathrm{m}}}_{\mathrm{F.}}\left(\mathrm{<figure-callout\; id="2"\; label="t\; \Delta \; t"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">t</figure-callout>},\right)\mathrm{\Delta }\mathrm{t}\mathrm{}2}=\mathrm{<figure-callout\; id="1"\; label="k\; \Delta \; t"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">k</figure-callout>}\frac{\mathrm{\Delta }\mathrm{t}}{}\frac{\mathrm{}1}{\mathrm{<figure-callout\; id="2"\; label="\Delta \; t"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">\Delta </figure-callout>}\mathrm{t}\mathrm{}2}=\mathrm{k}\mathrm{V}=\mathrm{constant}$$

ergibt. Da auch voraussetzungsgemäß das Zeitdauer-Zeitabstand-Verhältnis V konstant gehalten wird, ist auch die vorgegebene Trockenstoff-Konzentration c in der notwendigen Weise konstant.The time-dependent material flows ṁ _P (t) and ṁ _F (t) are constant over time in the mixing process in question (ṁ _P = constant; ṁ _F = constant), so that the quotient of the two quantities in turn becomes a constant $\mathrm{k}=\frac{{\stackrel{\mathrm{.}}{\mathrm{m}}}_{\mathrm{P.}}\left(\mathrm{t}\right)}{{\stackrel{\mathrm{.}}{\mathrm{m}}}_{\mathrm{F.}}\left(\mathrm{t}\right)}$

results. Since the time duration / time interval ratio V is also kept constant in accordance with the prerequisite, the specified dry matter concentration c is also constant in the necessary manner.

A significant technical control feature is that a time-dependent current consumption I (t) is determined, which is proportional to the 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 powdery substance m _{P is introduced} into the mixing process or the mixing container and treated in pulses.

As soon as the powdery substance is evenly distributed in the absorbing liquid, i.e. distributed as homogeneously as possible and possibly dissolved, the time-dependent current consumption I (t) subsides, to a reference current consumption I _o , which is characteristic of the completely homogenized mixed product performing stirring and / or shearing and homogenizing performance. The relevant reference current consumption I _o 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 time interval between adjacent metering pulses Δt2 and if the time-dependent current consumption I (t) deviates from the reference current consumption I _o by more than a specified tolerance, with a deviation either upwards or downwards, the calculation is carried out in compliance with the specified dry matter content. Concentration c resulting fixed ratio V = Δt1 / Δt2 the duration of the metering pulse Δt1 for the subsequent metering pulse is shortened in the first case and lengthened in the second case. This technical control measure inevitably leads in the same ratio to a corresponding shortening or lengthening of the time interval between adjacent metering pulses Δt2, based on the subsequent metering pulse.

The core of the control measure according to the invention is that the duration of the dosing pulse Δt1 and the time interval between adjacent metering pulses Δt2 are selected in such a way that at the end of the time interval between adjacent metering pulses Δt2, the time-dependent current consumption I (t) for stirring and / or shearing is determined and homogenizing the temporarily present mixed product _{approximates the reference current consumption I o} , which is required for the relevant treatment of the homogenized mixed product, within the scope of a practically relevant permissible tolerance.

Second method

With a view to a second method according to the invention, the invention is based on a known method for controlling the introduction of a powdery substance into a liquid consisting of at least one component for an inline mixing method, which is also classified as a multi-pass method or multi-stage process. The multi-pass process is typically used for mixed products that ultimately have a higher dry matter concentration and / or a higher viscosity, for example when larger amounts of powdery substance have to be emulsified, for example with oil, gum or aromas, because these mixed products with the single pass procieedings cannot be represented. In this case, the introduction and treatment of the pulverulent substance, from a reaction kinetic point of view, takes place again, as in the first method, under the conditions of a residence time behavior of a continuously operating homogeneous reaction vessel.

The second method is characterized in a manner known per se in such a way that in a first phase liquid is placed in a mixing container and the powdery substance is fed discontinuously to this liquid, with a dry substance concentration being reached at the end of the first phase that is below one for the The end value specified at the end of the entire mixing process is. The liquid and the powdery substance are continuously stirred and / or mixed into a mixed product in the first phase and the mixed product is homogenized.

In a second phase, the mixed product obtained in the first phase is recirculated via the mixing container and quantities of pulverulent material corresponding to the recirculated amount of mixed product are also added discontinuously. The quantity balance is accordingly designed in the second phase at a constant fill level 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 of mixed product routed via the recirculation plus the dosed mass flow of powdery 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 end value.

In the mixing process in question, a recipe for the mixed product is given, at least with regard to the time-dependent curve of a dry matter concentration associated with the given end value, and the reaction conditions are given in the form of default data.

The inventive solution concept consists in the second method that the discontinuous supply of the pulverulent substance in a manner known per se takes place in pulses by a chronological sequence of metering pulses. In this regard, the reaction conditions provide, in a preferred embodiment and in line with the first method, that the powdery substance is sucked in by a negative pressure (vacuum) in the head space of the mixing container compared to atmospheric pressure. The metering pulses are each characterized by a mass flow of the powdery substance ṁ _P , a duration of the metering pulse Δt1 and a time interval between adjacent metering pulses Δt2.

• Bei dem Verlauf ohne Sättigungscharakter lassen sich im Rahmen der Aufnahmekapazität oder der Löslichkeitsgrenze der Flüssigkeit in gleichen Zeitabständen gleiche Mengen pulverförmiger Stoff dosieren, sodass sich bei vollständiger Homogenisierung des Mischprodukts ein zeitabhängiger näherungsweise linear ansteigender Verlauf einer Trockenstoff-Konzentration einstellt.
• Bei dem Verlauf mit Sättigungscharakter lassen sich im Rahmen der Aufnahmekapazität oder der Löslichkeitsgrenze der Flüssigkeit in gleichen Zeitabständen nur stetig abnehmende Mengen pulverförmiger Stoff dosieren, sodass sich bei vollständiger Homogenisierung des Mischprodukts ein zeitabhängiger degressiv ansteigender Verlauf einer Trockenstoff-Konzentration einstellt.

Der in dem vorgegebenen Endwert endende zeitabhängige Verlauf einer Trockenstoff-Konzentration ist erfindungsgemäß durch die Abfolge eindeutig bestimmter Dosierimpulse definiert.The multi-stage process in the second phase of the second method results in a time-dependent course of a dry matter concentration c (t), which ends as planned in the specified end value, with between the course of a dry matter concentration without saturation character (approximately linear course) or with Saturation character (degressive course) is to be distinguished.

• In the case of the course without the character of saturation, within the framework of the absorption capacity or the solubility limit of the liquid, the same amounts of powdery substance can be dosed at the same time intervals, so that when the mixed product is completely homogenized, a time-dependent, approximately linearly increasing course of a dry matter concentration is established.
• In the case of the course with a saturation character, only steadily decreasing amounts of powdery substance can be dosed at the same time intervals within the framework of the absorption capacity or the solubility limit of the liquid, so that a time-dependent degressively increasing course of a dry matter concentration occurs when the mixed product is completely homogenized.

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 uniquely determined metering pulses.

A significant technical control feature is that a time-dependent current consumption I (t) is determined, which is proportional to the stirring and / or shearing and homogenizing power required for a temporarily present mixed product. The latter always occurs in the form of an approximately Gaussian normal distribution when a defined amount of powder Substance is introduced and treated in pulses in the mixing process or the mixing container.

As soon as the powdery substance is evenly distributed in the absorbing liquid (first phase) and in the absorbing mixed product (second phase), i.e. it has been distributed as homogeneously as possible and possibly dissolved, the time-dependent current consumption I (t) subsides, namely on a time-dependent course a reference _{current consumption I o} (t), which is characteristic of the stirring and / or shearing and homogenizing power to be provided on the homogenized mixed product under the conditions of the assigned time-dependent curve of a dry matter concentration c (t). The related course of a reference _{current consumption I o} (t) is stored in the specification 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 time interval between adjacent metering pulses Δt2 and when the time-dependent current consumption I (t) deviates from the respective assigned value in the time-dependent course of a reference current consumption I _o (t) by more than a specified tolerance, with a deviation either upwards or downwards , the duration of the dosing pulse Δt1 for the subsequent dosing pulse is shortened in the first case and lengthened in the second case.

For time-dependent curves of a dry matter concentration without the character of saturation, a first embodiment of the second method provides that these curves are each defined by a fixed duration-time interval ratio V between the duration of the metering pulse Δt1 and the assigned time interval between adjacent metering pulses Δt2 (V = Δt1 / Δt2 = constant).

In den meisten praxisrelevanten Fällen kann, weil der erste Term der nachfolgenden Relation in der Regel klein gegenüber dem zweiten Term ist, näherungsweise $${\stackrel{.}{\mathrm{m}}}_{\mathrm{P}}\frac{\mathrm{t}}{\mathrm{\Delta }\mathrm{t}2}\mathrm{\Delta }\mathrm{t}1\ll {\mathrm{m}}_{\mathrm{F}}$$

gesetzt werden, sodass sich nach Gleichung (2a) für den zeitabhängigen Verlauf einer Trockenstoff-Konzentration c(t) mit einer ersten Proportionalitätskonstante $\mathrm{k}1=\frac{{\stackrel{\mathrm{.}}{\mathrm{m}}}_{\mathrm{P}}}{{\mathrm{m}}_{\mathrm{F}}}$

näherungsweise ergibt: $$\mathrm{c}\left(\mathrm{t}\right)\approx \frac{{\stackrel{.}{\mathrm{m}}}_{\mathrm{P}}\frac{\mathrm{t}}{\mathrm{\Delta }\mathrm{t}2}\mathrm{\Delta }\mathrm{t}1}{{\mathrm{m}}_{\mathrm{F}}}=\frac{{\stackrel{.}{\mathrm{m}}}_{\mathrm{P}}}{{\mathrm{m}}_{\mathrm{F}}}\frac{\mathrm{\Delta }\mathrm{t}1}{\mathrm{\Delta }\mathrm{t}2}\mathrm{t}=\frac{{\stackrel{.}{\mathrm{m}}}_{\mathrm{P}}}{{\mathrm{m}}_{\mathrm{F}}}\mathrm{V}\mathrm{t}=\mathrm{k}1\mathrm{V}\mathrm{t}$$

The respective course of a dry matter concentration c (t) increases over time t, because the continuously pulsed flow of powdery substance ṁ _P , which in the most general case is a time-dependent flow of powdery substance ṁ _P (t), over the entire period of time t of the mixing process is constant (ṁ _P = constant). The mass flow of powdery substance ṁ _{P increases} in the time period t many times, namely (t / Δt2) times, with approximately unchanged The filling level in the mixing container is introduced into an unchangeable amount of liquid m _{F of} the present mixed product, the time-dependent course of a dry matter concentration according to equation (2) being represented as follows: $$\mathrm{c}\left(\mathrm{t}\right)=\frac{{\stackrel{.}{\mathrm{m}}}_{\mathrm{P.}}\frac{\mathrm{<figure-callout\; id="2"\; label="t\; \Delta \; t"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">t</figure-callout>}}{\mathrm{\Delta }\mathrm{t}}\mathrm{\Delta }\mathrm{t}1}{{\mathrm{m}}_{\mathrm{F.}}+{\stackrel{.}{\mathrm{m}}}_{\mathrm{P.}}\frac{\mathrm{<figure-callout\; id="2"\; label="t\; \Delta \; t"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">t</figure-callout>}}{\mathrm{\Delta }\mathrm{t}}\mathrm{<figure-callout\; id="1"\; label="\Delta \; t"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">\Delta </figure-callout>}\mathrm{t}\mathrm{}1}$$

In most practice-relevant cases, because the first term of the following relation is usually small compared to the second term, approximately $${\stackrel{.}{\mathrm{m}}}_{\mathrm{P.}}\frac{\mathrm{<figure-callout\; id="2"\; label="t\; \Delta \; t"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">t</figure-callout>}}{\mathrm{\Delta }\mathrm{t}}\mathrm{<figure-callout\; id="1"\; label="\Delta \; t"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">\Delta </figure-callout>}\mathrm{t}\mathrm{}1\ll {\mathrm{m}}_{\mathrm{F.}}$$

are set so that according to equation (2a) for the time-dependent course of a dry matter concentration c (t) with a first constant of proportionality $\mathrm{k}$$\mathrm{}1=\frac{{\stackrel{\mathrm{.}}{\mathrm{m}}}_{\mathrm{P.}}}{{\mathrm{m}}_{\mathrm{F.}}}$

approximately results in: $$\mathrm{c}\left(\mathrm{t}\right)\approx \frac{{\stackrel{.}{\mathrm{m}}}_{\mathrm{P.}}\frac{\mathrm{<figure-callout\; id="2"\; label="t\; \Delta \; t"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">t</figure-callout>}}{\mathrm{\Delta }\mathrm{t}}\mathrm{\Delta }\mathrm{t}1}{{\mathrm{m}}_{\mathrm{F.}}}=\frac{{\stackrel{.}{\mathrm{m}}}_{\mathrm{P.}}}{{\mathrm{m}}_{\mathrm{F.}}}\frac{\mathrm{\Delta }\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">t</figure-callout>}1}{\mathrm{\Delta }\mathrm{t}2}\mathrm{t}=\frac{{\stackrel{.}{\mathrm{m}}}_{\mathrm{P.}}}{{\mathrm{m}}_{\mathrm{F.}}}\mathrm{V}\mathrm{t}=\mathrm{k}1\mathrm{V}\mathrm{t}$$

This technical control measure with a fixed duration-time interval ratio V (V = Δt1 / Δt2 = constant) inevitably leads in the same ratio to a corresponding shortening or lengthening of the time interval between adjacent metering pulses Δt2, based on the subsequent metering pulse.

• bei Abweichung der zeitabhängigen Stromaufnahme I(t) von dem jeweils zugeordneten Wert im zeitabhängigen Verlauf einer Referenzstromaufnahme I_o(t) um mehr als die vorgegebene Toleranz nach oben das Zeitdauer-Zeitabstand-Verhältnis V verkleinert und
• bei Abweichung der zeitabhängigen Stromaufnahme I(t) von dem jeweils zugeordneten Wert im zeitabhängigen Verlauf einer Referenzstromaufnahme I_o(t) um mehr als die vorgegebene Toleranz nach unten das Zeitdauer-Zeitabstand-Verhältnis V vergrößert wird.

For time-dependent curves of a dry matter concentration with a saturation character, a second embodiment of the second method provides that these curves are defined by a variable time duration-time interval ratio V between the duration of the metering pulse Δt1 and the assigned time interval between adjacent metering pulses Δt2 (V = Δt1 / Δt2 ≠ constant), where

• if the time-dependent current consumption I (t) deviates from the respectively assigned value in the time-dependent course of a reference current consumption I _o (t) by more than the specified tolerance upwards, the duration-time interval ratio V is reduced and
• if the time-dependent current consumption I (t) deviates from the respectively assigned value in the time-dependent course of a reference current consumption I _o (t), the time-duration-time-interval ratio V is increased by more than the specified tolerance.

wie folgt, darstellt: $$\mathrm{c}\left(\mathrm{t}\right)=\frac{{\displaystyle {\sum }_{\mathrm{t}=0}^{\mathrm{t}}\left({\stackrel{.}{\mathrm{m}}}_{\mathrm{P}}\left(\mathrm{t}\right)\mathrm{\Delta }\mathrm{t}1\right)}}{{\mathrm{\rho }}_{\mathrm{M}}\left(\mathrm{t}\right){\mathrm{V}}_{\mathrm{M}}}=\frac{{\stackrel{.}{\mathrm{m}}}_{\mathrm{P}}}{{\mathrm{V}}_{\mathrm{M}}}\frac{{\displaystyle {\sum }_{t=0}^t\mathrm{\Delta }\mathrm{t}1}}{{\mathrm{\rho }}_{\mathrm{M}}\left(\mathrm{t}\right)}\approx \mathrm{k}2\frac{{\displaystyle {\sum }_{t=0}^t\mathrm{\Delta }\mathrm{t}1}}{{\mathrm{\rho }}_{\mathrm{M}}\left(\mathrm{t}\right)}.$$

The respective course of a dry matter concentration c (t) increases degressively over time t, because the continuously pulsed flow of the powdery substance ṁ _P , viewed over the entire time t of the mixing process, is constant (ṁ _P = constant), however, the duration of the dosing pulse Δt1 steadily decreases and thus a steadily decreasing amount of powdery substance is dosed. The mass flow of powdery substance ṁ _{P is introduced into an existing almost unchangeable volume of the mixed product V M} (V _M ≈ constant) in the time period t with an almost unchangeable fill level in the mixing container, with a density ρ _{M of} the mixed product corresponding to the time-dependent course of a dry matter concentration c (t) increases and the latter is determined by equation (3) with a second constant of proportionality $\mathrm{k}$$\mathrm{}2=\frac{{\stackrel{\mathrm{.}}{\mathrm{m}}}_{\mathrm{P.}}}{{\mathrm{v}}_{\mathrm{M.}}},$

as follows: $$\mathrm{c}\left(\mathrm{t}\right)=\frac{{\displaystyle {\sum }_{\mathrm{t}=0}^{\mathrm{t}}\left({\stackrel{.}{\mathrm{m}}}_{\mathrm{P.}}\left(\mathrm{<figure-callout\; id="1"\; label="t\; \Delta \; t"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">t</figure-callout>},\right)\mathrm{\Delta }\mathrm{t}\mathrm{}1\right)}}{{\mathrm{\rho }}_{\mathrm{M.}}\left(\mathrm{t}\right){\mathrm{V}}_{\mathrm{M.}}}=\frac{{\stackrel{.}{\mathrm{m}}}_{\mathrm{P.}}}{{\mathrm{V}}_{\mathrm{M.}}}\frac{{\displaystyle {\sum }_{t=0}^{\mathrm{<figure-callout\; id="1"\; label="t\; \Delta \; t"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">t</figure-callout>}}\mathrm{\Delta }\mathrm{t}\mathrm{}1}}{{\mathrm{\rho }}_{\mathrm{M.}}\left(\mathrm{t}\right)}\approx \mathrm{<figure-callout\; id="2"\; label="k"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">k</figure-callout>}2\frac{{\displaystyle {\sum }_{t=0}^{\mathrm{<figure-callout\; id="1"\; label="t\; \Delta \; t"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">t</figure-callout>}}\mathrm{\Delta }\mathrm{t}\mathrm{}1}}{{\mathrm{\rho }}_{\mathrm{M.}}\left(\mathrm{t}\right)}.$$

This technical control measure with a variable duration-time interval ratio V requires the control to be able to shorten or lengthen the duration of the metering pulse Δt1 with an unchanging time interval between adjacent metering pulses Δt2 or to adequately lengthen the time interval between adjacent metering pulses Δt2 with the same duration of the metering pulse Δt1 or shorten it.

The control-technical measure according to the invention therefore essentially consists in both embodiments of the second method in that the duration of the metering pulse Δt1 and the time interval between adjacent metering pulses Δt2 are selected in such a way that at the respective end of the time interval between adjacent metering pulses Δt2 the time-dependent determined current consumption I (t) for stirring and / or shearing and homogenizing the temporarily present mixed product _{approximates the time-dependent course of a reference current consumption I o} (t), which is required for the relevant treatment of the homogenized mixed product, within the scope of a practically relevant permissible tolerance.

The second method, which is primarily suitable for increasing the dry matter concentration to a predetermined final value, provides that the recirculated mixed product is divided into a first portion and a second portion, that the first portion is fed directly to the mixing process and that the complementary second portion is guided over a storage volume and then also fed to the mixing process. This division offers the possibility, as is proposed, of setting the first portion recirculated directly via 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 with the maximum possible first proportion (100%). Large quantities of mixed product are recirculated and concentrated with a large second portion over correspondingly large storage volumes, whereby the distribution ratio can be selected so that the first portion, which is recirculated directly via the mixing process, the mechanical agitators and / or shears installed in this mixing process - and homogenizing mechanisms supplemented and intensified by fluid mechanical mechanisms of action.

First and Second Procedure

In order to make the metering of the pulverulent substance as trouble-free as possible, it is proposed for the first and the second method that the mass flow of the pulverulent substance is constant over the duration of the metering pulse. This is ensured in particular by the fact that a controllable opening for the supply of the powdery substance only assumes either a fully open position or a closed position.

In order to make the control of the mixing process as manageable as possible, a different embodiment for both methods provides that the shortening or lengthening of the duration of the metering pulse takes place when a current corridor determined by a permissible current overrun or a permissible undercurrent through an upward deviating current corridor Current consumption or a current consumption deviating downwards is left. The permissible current excess and the permissible current shortfall are each represented by a percentage of the assigned reference current consumption or the assigned time-dependent course of a reference current consumption is determined. In order for the control to work as sensitively as possible in this regard, it is also 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 assigned reference current consumption or the assigned time-dependent course of a reference current consumption.

In order to make the operating data obtained in practice for a specific recipe usable for subsequent mixing processes with the same recipe, another embodiment for both methods provides that the control of the introduction of the powdery substance into the at least one liquid is based on further recipe-dependent default data from empirical values previous mixing processes are obtained and stored, these default data being 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 devices for stirring and / or shearing and homogenizing and a permissible current exceedance and a permissible current undercurrent are dependent on the assigned reference current consumption or the assigned time-dependent course of a reference current consumption.

In order to make the operating data obtained in practice for a certain recipe usable for subsequent mixing processes with the same recipe, a further embodiment provides for both methods that the target-oriented recipe-dependent control parameters obtained in the course of the control of the introduction of the powdery 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 controls 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, an outlet nozzle for discharging a mixed product and a stirring device and / or a shearing and homogenizing device. An inlet valve with a valve closing member is arranged on the mixing container. 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, with the valve closing element being able to be moved into the closed or open position with a control device assigned to the inlet valve.

According to the invention, the control device of the mixing device provides recipe-dependent specification data and recipe-dependent control parameters in the form of the duration of the metering pulse and the time interval between adjacent metering pulses. Furthermore, according to the invention, the control device has at least one signal pickup 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 closed or open position of the valve closing element as a function of the time-dependent power consumption and in relation to the specified data and the control parameters.

A mixing device for carrying out the second method is constructed essentially adequately to the mixing device for carrying out the first method. The difference results from the task on which the second method is based, to achieve the greatest possible concentration of small to large amounts of mixed product with powdery substance by recirculating the mixed product. For this purpose, a structural addition to the mixing device is provided in the form of a circulation line, which branches off from a line connected to the outlet connection and opens directly into the mixing container.

In order to further optimize the inlet valve designed as a lift valve, which only supplies the powdery substance in its fully open position and thus minimizes the susceptibility to clogging from the outset, and for example dead spaces and cavities in the powder-loaded area of the valve housing To avoid the inlet valve, an advantageous embodiment provides that the valve closing member is designed, at least in its powder-loaded area, as a cylindrical rod of the same diameter, on which a valve disk is molded with the same diameter. When the inlet valve is in its fully open position, the valve closing member with its valve disk is largely moved out of the fully developed flow of the powdery substance due to this embodiment, so that on the one hand it does not represent a flow obstacle and on the other hand there is a seat seal that is accommodated in the valve disk the vicinity of the wall of a valve housing and thus outside the fully developed flow area of the pipe flow and is therefore only affected by the stagnant flow close to the wall in this edge area.

BRIEF DESCRIPTION OF THE DRAWINGS

Figur 1

in schematischer Darstellung eine Mischvorrichtung für ein Inline-Mischverfahren, das als erstes Verfahren, einem sogenannten Eindurchgang-Verfahren, betrieben wird;

Figur 1a

in schematischer Darstellung eine Mischvorrichtung für ein Inline-Mischverfahren, das als zweites Verfahren, einem sogenannten Mehrdurchgang-Verfahren, betrieben werden kann;

Figur 2

in perspektivischer Darstellung und im Halbschnitt ein Einlaufventil zur Zuführung des pulverförmigen Stoffes in Mischvorrichtungen gemäß den Figuren 1 und 1a ohne ein Steuerkopfgehäuse;

Figur 3

in einer qualitativen Darstellung für das erste Verfahren eine zeitabhängige Stromaufnahme I(t) für eine Abfolge von Dosierimpulsen mit einer konstanten Zeitdauer des Dosierimpulses Δt1 und mit einem Zeitabstand benachbarter Dosierimpulse Δt2;

Figur 4

in einer qualitativen Darstellung für das erste Verfahren eine zeitabhängige Stromaufnahme I(t) für eine Abfolge von Dosierimpulsen mit einer konstanten Zeitdauer des Dosierimpulses Δt1/2 und mit einem Zeitabstand benachbarter Dosierimpulse Δt2/2;

Figur 5

in einer qualitativen Darstellung für das zweite Verfahren eine zeitabhängige Stromaufnahme I(t) für eine Abfolge von Dosierimpulsen mit einer konstanten Zeitdauer des Dosierimpulses Δt1 und mit einem konstanten Zeitabstand benachbarter Dosierimpulse Δt2 zur Realisierung eines zeitabhängigen näherungsweise linear ansteigenden Verlaufs einer Trockenstoff-Konzentration (ohne Sättigungscharakter) und

Figur 6

in einer qualitativen Darstellung für das zweite Verfahren eine zeitabhängige Stromaufnahme I(t) für eine Abfolge von Dosierimpulsen mit einer stetig abnehmenden Zeitdauer des Dosierimpulses Δt1 und mit einem konstanten Zeitabstand benachbarter Dosierimpulse Δt2 zur Realisierung eines zeitabhängigen degressiven Verlaufs einer Trockenstoff-Konzentration (mit Sättigungscharakter).

A more detailed description of the invention can be found in the following description and the attached figures of the drawing and in the claims. While the invention is implemented in a wide variety of configurations of a first and a second method for controlling the introduction of a powdery substance into a liquid consisting of at least one component for an inline mixing method, the drawing shows a preferred first and second method and a mixing device for Implementation of the respective procedure is described. Show it

Figure 1

a schematic representation of a mixing device for an inline mixing process, which is operated as the first process, a so-called single-pass process;

Figure 1a

a schematic representation of a mixing device for an inline mixing process, which can be operated as a second process, a so-called multi-pass process;

Figure 2

In a perspective view and in half-section, an inlet valve for feeding the powdery substance into mixing devices according to FIGS Figures 1 and 1a without a control head housing;

Figure 3

in a qualitative representation for the first method, a time-dependent current consumption I (t) for a sequence of metering pulses with a constant duration of the metering pulse Δt1 and with a time interval between adjacent metering pulses Δt2;

Figure 4

in a qualitative representation for the first method, a time-dependent current consumption I (t) for a sequence of metering pulses with a constant duration of the metering pulse Δt1 / 2 and with a time interval between adjacent metering pulses Δt2 / 2;

Figure 5

In a qualitative representation for the second method, a time-dependent current consumption I (t) for a sequence of metering pulses with a constant duration of the metering pulse Δt1 and with a constant time interval between adjacent metering pulses Δt2 to achieve 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 I (t) for a sequence of metering pulses with a continuously decreasing duration of the metering pulse Δt1 and with a constant time interval between adjacent metering pulses Δt2 to achieve a time-dependent degressive course of a dry matter concentration (with a saturation character) .

Mixing device for the first process (Figures 1 and 2)

A mixing device 1000 has, inter alia, a mixing container 100 which consists of a preferably cylindrical container jacket 100.1, an upper container base 100.2 and a lower container base 100.3. The lower container bottom 100.3 preferably tapers downwards, mostly conically or in the form of a circular cone, and at the lower end has an outlet connection 100.4 for a mixed product M, which is discharged _{with a mass flow of mixed product ṁ M.} A liquid F with a flow rate of liquid ṁ _{F is} continuously fed to the mixing container 100 via an inlet connection 100.5, which forms a free fill level N above which, in the case of the mixing device 1000 in question (vacuum mixer), a pressure above the liquid column p, a negative pressure, is usually compared to atmospheric pressure, prevails.

An inlet valve 20 is arranged on the container jacket 100.1 or the lower container base 100.3. The inlet valve 20 is used for the discontinuous supply of a powdery substance P with a _{mass flow of powdery substance ṁ P} , which is fed via a feed line 18, into the liquid F or into the mixed product M. The inlet valve 20 is assigned a control device 30, which has a control head housing 14 of the inlet valve 20 communicates via a signal line 22 and, if necessary, the inlet valve 20 is transferred into its open or closed position. In the mixing container 100 there is a stirring device 24 driven by a first drive motor 40 at a rather low first speed n1, preferably arranged centrally and acting mechanically, which preferably extends down into the area of the lower container bottom 100.3. The required stirring effect can also be achieved by fluid mechanical means, for example by pumping the liquid F or the mixed product M through an in Figure 1 circulation line, not shown, or one as in Figure 1a The circulation line 28 shown, having a comparable effect, with preferably tangential entry of the liquid F or the mixed product M into the mixing container 100, can be 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 the case, is also to be read and vice versa. As an alternative or in addition to the stirring device 24, a shearing and homogenizing device 26 driven by a second drive motor 50 with a rather high second speed n2 is preferably provided in the lower region of the lower container bottom 100.3 and preferably eccentrically in this. This preferably sucks in the liquid F on the one hand from above and on the other hand ejects it in the form of a ring in the area of the lower container bottom 100.3 close to the wall in such a way that a circulation flow directed from the outside inward is preferably formed in the mixing container 100. When passing through the shearing and homogenizing device 26, liquid F and powdery substance P or the mixed product M resulting therefrom are mechanically mixed very intensively and preferably homogenized in the process.

The inlet valve 20 is designed as a lift valve ( Figure 2 ). In a valve housing 2, it has a valve seat 2a and a valve disk cooperating with it 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, effects the seal. The valve seat 2a has a seat opening 2b through which the powdery substance P supplied from the supply line 18 via a pipe connection 2c is introduced into the liquid F ( Figure 1 ).

The liquid F 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 ( Figure 1 ), so that the static pressure in the area of the aforementioned connection point and thus also in the area of the seat opening 2b is made up of the pressure above the liquid column p (preferably negative pressure) and the static pressure resulting from the height of the liquid column h. In the case of a vacuum mixer with a negative pressure of, for example, p = 0.2 to 0.8 bar and a height of the liquid column h = 0.2 to 4 m assigned to this pressure range, there is always a negative pressure compared to atmospheric pressure in the area of the seat opening 2b, so that the seat opening 2b is sucked out of the mixing container 100 and thus the powdery substance P is sucked in. The seat opening 2b can be adjusted with the valve disk 8a between completely closed, the closed position, or completely open, the open position. The valve housing 2 is connected via a lantern housing 4 to a drive housing 6 for driving the valve closing member 8. It is preferably a spring / piston drive acted upon by pressure medium, a return spring 12 usually moving the valve closing member 8 into its closed position when the drive housing 6 is not acted upon by pressure medium, preferably compressed air. A valve rod 8b, which engages the valve plate 8a of the valve closing element 8 and is guided through the drive housing 6 and into the control head housing 14, serves on the drive side for the axial guidance of the valve closing element 8. The valve closing element 8 is at least in its powder-loaded area as a cylindrical rod of the same diameter formed on which the valve disk 8a is formed with the same diameter. This structural design avoids cavities and dead spaces in the valve housing 2 in the range of movement of the valve closing member 8 that is exposed to powder, the valve closing member 8 moving with it its end valve disk 8a and the associated seat seal 10 can be withdrawn as far as possible from the area of the valve housing 2 through which there is a full flow.

The control device 30 ( Figure 1 ) has at least one signal pickup 16. The at least one signal sensor 16 is a measuring device, for example for mixing parameters, such as the volume flow of liquid ṁ _F , the pressure above the liquid column p in the mixing container 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), speeds n1, n2 and a time-dependent current consumption I (t) of the stirring and / or shearing and homogenizing device 24, 26. The signal pick-up 16 is shown in FIG Figure 1 shown by way of example for the time-dependent current consumption I (t) of the second drive motor 50 of the shearing and homogenizing device 26. In an analogous manner, additional or alternatively further measuring devices can be provided which determine the other mixing parameters.

Mixing device for the second process (Figures 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 nozzle 100.4 and opens directly into the mixing container 100, preferably via its own recirculation connection 100.6 . The line connected to the outlet connection 100.4 can be routed through one or more storage tanks and finally connected to the inlet connection 100.5. These constructive measures serve procedural purposes that have already been explained above. In order to avoid repetition, a complete description of the mixing device 1000 according to FIG Figure 1a waived and in this regard to the description Figure 1 referenced.

First method (Figures 3 and 4 in conjunction with Figures 1 and 2)

The introduction and treatment of the pulverulent substance P takes place quasi under the reaction kinetic conditions of a residence time behavior of a continuously operating homogeneous reaction vessel. The liquid F Via the inlet connection 100.5 with the flow rate of liquid ṁ _F , which in the most general case can be a time-dependent flow rate of liquid (ṁ _F (t)), continuously and the powdery substance P via the inlet valve 20 discontinuously with the flow rate of powdery substance ṁ _P , which is in In the most general case, a time-dependent mass flow of powdery substance (ṁ _P (t)) can also be fed to the mixing process in the mixing container 100, the goal being the predetermined, time-unchangeable dry matter concentration c of the powdery substance P in the liquid F. The liquid F and the powdery substance P are continuously stirred and / or mixed to form the mixed product M and the mixed product M is homogenized in the process. The mixed product M is continuously removed _{with the mixed product ṁ M} according to the supplied amounts of liquid F and powdery substance P. A recipe for the mixed product M, at least with regard to the specified dry matter concentration c, and the reaction conditions in each case in the form of specified data D are specified.

The discontinuous supply of the powdery substance P takes place over a period of time t in pulses by a time sequence of metering pulses i ( Figures 3 and 4 ), which are each characterized by the mass flow of the powdery substance ṁ _P , a duration of the dosing pulse Δt1 and a time interval between adjacent dosing pulses Δt2. The mass flow of the powdery substance ṁ _P is basically a time-dependent mass flow of powdery substance ṁ _P (t), as already stated above, whereby in the present application subject due to the design and the switching characteristics of the inlet valve 20, approximately from a time-independent and thus constant mass flow of powdery substance ṁ _P is assumed (ṁ _P = constant). According to equation (1), the given constant dry matter concentration c is defined by an equally fixed, i.e. constant time duration / time interval ratio V between the duration of the metering pulse Δt1 and the assigned time interval between adjacent metering pulses Δt2 (V = Δt1 / Δt2 = constant).

For the duration of the dosing pulse Δt1 according to Figure 3 is, for example, the same on the second drive motor 50 of the shearing and homogenizing device 26 in Figure 3 Time-dependent current consumption I (t) plotted over the corresponding period t is determined or measured. The latter is proportional to a stirring and / or shearing and homogenizing power required for a mixing product M * temporarily present in the mixing container 100 immediately after the dosing pulse i ( Figure 1 ), which is to be applied by the stirring and / or shearing and homogenizing device 24, 26 in this phase of the treatment. The course of the time-dependent current consumption I (t) is similar to a Gaussian normal distribution curve, it increases with the intermittent flow of powdery substance ṁ _P , reaches a maximum, and then after dissolution of the powdery substance P, i.e. with a homogenized mixed product that is then reached M to gradually decrease to an initial value.

According to the invention, this typical behavior is used for control purposes in that a reference _{current consumption I o is} used from the specification data D, which is characteristic of the stirring and / or shearing and homogenizing power to be provided on the homogenized mixed product M.

If the time interval between adjacent metering pulses Δt2 is not sufficient to _{dissolve, mix in and homogenize a metered amount of powdery substance m P} = ṁ _P Δt1, a time-dependent, upwardly deviating current consumption I * (t) is measured, so that in this state of the temporarily present mixed product M * at the end of the time interval between adjacent dosing pulses Δt2 a new dosing pulse i is not yet displayed. If, under comparable conditions, a time-dependent, downwardly deviating current consumption I ** (t) is determined, this can be an indication that the stirring and / or shearing and homogenizing phase, which is also defined by the time interval between adjacent metering pulses Δt2, is excessively long is or that no adequate amount of powdery substance m _{P was} dosed in this phase.

According to the invention, the method for controlling takes account of the facts presented above in that at the end of the time interval between adjacent metering pulses Δt2 and when the time-dependent current consumption I (t) deviates from the time-independent and therefore constant reference current consumption I _o (I _o = constant) by more than one specified tolerance, either upwards or downwards, and while maintaining the fixed duration-time interval ratio V (V = Δt1 / Δt2 = constant) the duration of the dosing pulse Δt1 for the subsequent dosing pulse i is shortened in the first case and lengthened in the second case. The tolerance consists of a specification of a permissible current exceedance ΔI1 and a permissible current undercurrent ΔI2 ( Figure 3 ).

The case of foreshortening is in Figure 4 shown, whereby in the case example shown, the duration of the dosing pulse Δt1 and thus also the associated time segment of adjacent dosing pulses Δt2 have been halved by way of example (Δt1 / 2; Δt2 / 2). In this metering mode, too, at the end of the period of adjacent metering pulses Δt2 / 2, a check is carried out to determine whether a time-dependent current consumption I * (t), I ** (t) is present within the specified tolerance makes necessary correction in the sense described above.

The shortening or lengthening of the duration of the dosing pulse Δt1 occurs when a current corridor determined by the permissible current exceedance ΔI1 or the permissible current undercurrent ΔI2 due to the time-dependent current consumption I * (t), I ** (t) deviating upwards or downwards. is left. The permissible current excess and the permissible current shortfall ΔI1, ΔI2 are preferably each determined by a percentage of the assigned reference current consumption I _o . Furthermore, the amount of shortening or lengthening of the duration of the metering pulse Δt1 is preferably determined as a function of the amount of deviation of the time-dependent current consumption I (t) from the assigned reference current consumption I _o . The permissible current excess ΔI1 and permissible current shortfall ΔI2 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 controlling the introduction of the powdery substance P into the at least one liquid F, targeted, recipe-dependent control parameters S, namely the duration of the dosing pulse Δt1 and the time interval between adjacent dosing pulses Δt2, are stored and used for subsequent controls of the same recipes.

The control device 30 of the mixing device 100 is set up according to the invention so that it can provide the recipe-dependent default data D and the recipe-dependent control parameters S in the form of the duration of the metering pulse Δt1 and the time interval between adjacent metering pulses Δt2. The control device 30 also has at least the signal pick-up 16 designed as a measuring device ( Figure 1 ), which records the time-dependent current consumption I (t) of the stirring device 24 and / or the shearing and homogenizing device 26 ( Figures 3, 4 ). According to the invention, the control device 30 controls the closed or open position of the valve closing element 8 ( Figure 2 ) as a function of the time-dependent current consumption I (t) and in relation to the default data D and the control parameters S.

Second method (Figures 5 and 6 in conjunction with Figures 1a and 2)

In order to avoid repetition, the following description of the figures for the second method in its two embodiments focuses only on those solution features in which the second method 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 pulverulent 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 placed in the mixing container 100 (supply via the inlet connection 100.5) and the powdery substance P is _{fed to this total liquid F via the inlet valve 20 discontinuously with the mass flow of powdery substance ṁ P} , at the end of the first Phase a dry matter concentration c is reached, which is below a predetermined end value c _E for the end of the entire mixing process. 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 form 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 container 100 and the recirculated product continues to be used Amount of mixed product M corresponding amounts of powdery substance P supplied 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). In the second phase, with a constant fill level N, the quantity balance is therefore compulsorily 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 end value c E.}

In the mixing process in question, a formulation of the mixed product M is given, at least with regard _{to the time-dependent curve of a dry matter concentration c (t) assigned to the given end value c E} , and the reaction conditions are given in the form of the default data D in each case.

The inventive solution concept corresponds in essential features to that according to the first method. The multi-stage process in the second phase of the second method results in the time-dependent course of a dry matter concentration c (t), which _{ends as planned in the specified end value c E} , with between the course of a dry matter concentration c (t) without saturation character ( approximately linear time-dependent course; see Figure 5 ) or with saturation character (degressive time-dependent course; see Figure 6 ) is to be distinguished. The time-dependent course of a dry matter concentration c (t) ending in the predetermined end value c _E is defined by the sequence of specific metering pulses i, ie clearly defined by the duration of the metering pulse Δt1 and the time interval between adjacent metering pulses Δt2.

As soon as the powdery substance P is evenly distributed in the absorbing liquid F (first phase) and in the absorbing mixed product M (second phase), ie has been distributed as homogeneously as possible and possibly dissolved, the time-dependent current consumption I (t) subsides on a time-dependent curve of a reference _{current consumption I o} (t), which is characteristic of the stirring and / or shearing and homogenizing power to be provided on the homogenized mixed product M under the conditions of the assigned time-dependent curve of a dry matter concentration c (t) ( please refer Figure 5 : approximately linear time-dependent Course of a reference current consumption I _o (t); Figure 6 : degressive time-dependent course of a reference current consumption I ₀ (t)). The time-dependent course of a reference current consumption I _o (t) begins at time t = 0, at which only the pure liquid F is present, with an initial value I _o (t = 0) = I ₀ (see FIG Figures 5 , 6th ). The related course of a reference _{current consumption I o} (t) is stored in the specification data D, and it is dependent on the recipe of the mixed product M and the reaction conditions for the mixing process.

At the end of the time interval between adjacent metering pulses Δt2 and when the time-dependent current consumption I (t) deviates from the respective assigned value in the time-dependent course of a reference current consumption I _o (t) by more than a specified tolerance, with a deviation either upwards or downwards (please refer Figures 5 , 6th ), the duration of the dosing pulse Δt1 for the subsequent dosing pulse is shortened in the first case and lengthened 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 it can be described by the equations (2, 2a) given above (c (t) = k1 V t), an embodiment of the second method provides that this course is determined by a fixed time duration-time interval ratio V between the Duration of the dosing pulse Δt1 and the assigned time interval between adjacent dosing pulses Δt2 is defined (V = Δt1 / Δt2 = constant). In the event of deviations from the time-dependent course of a reference _{current consumption I o} (t), the duration of the metering pulse Δt1 is shortened according to the invention with a constant duration-time interval ratio V (as shown in FIG Figure 4 in contrast to Figure 3 is shown qualitatively as an example) or extended. This technical control measure with a fixed time duration / time interval ratio V inevitably leads in the same ratio to a corresponding shortening or lengthening of the time interval between adjacent metering pulses Δt2, based on the subsequent metering pulse i.

sieht eine weitere Ausgestaltung des zweiten Verfahrens vor, dass dieser Verlauf durch ein variables Zeitdauer-Zeitabstand-Verhältnis V zwischen der Zeitdauer des Dosierimpulses Δt1 und dem zugeordneten Zeitabstand benachbarter Dosierimpulse Δt2 definiert ist (V = Δt1/Δt2 ≠ konstant), wobei

• bei Abweichung der zeitabhängigen Stromaufnahme I(t) von dem jeweils zugeordneten Wert im zeitabhängigen Verlauf einer Referenzstromaufnahme I_o(t) um mehr als die vorgegebene Toleranz nach oben das Zeitdauer-Zeitabstand-Verhältnis V verkleinert und
• bei Abweichung der zeitabhängigen Stromaufnahme I(t) von dem jeweils zugeordneten Wert im zeitabhängigen Verlauf einer Referenzstromaufnahme I_o(t) um mehr als die vorgegebene Toleranz nach unten das Zeitdauer-Zeitabstand-Verhältnis V vergrößert wird.

For a time-dependent course of a dry matter concentration c (t) with saturation character ( Figure 6 ) as can be described by equation (3) given above $\left(\mathrm{c}\left(\mathrm{t}\right)\approx \mathrm{<figure-callout\; id="2"\; label="k"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">k</figure-callout>}2\frac{{\displaystyle {\sum }_{\mathbf{t}=0}^{\mathbf{<figure-callout\; id="1"\; label="t\; \Delta \; t"\; filenames="imgf0004.png,imgf0005.png"\; state="\{\{state\}\}">t</figure-callout>}}\mathrm{\Delta }\mathrm{t}\mathrm{}1}}{{\mathrm{\rho }}_{\mathrm{M.}}\left(\mathrm{t}\right)}\right),$

A further embodiment of the second method provides that this course is defined by a variable time duration / time interval ratio V between the time duration of the metering pulse Δt1 and the associated time interval between adjacent metering pulses Δt2 (V = Δt1 / Δt2 ≠ constant), where

• if the time-dependent current consumption I (t) deviates from the respectively assigned value in the time-dependent course of a reference current consumption I _o (t) by more than the specified tolerance upwards, the duration-time interval ratio V is reduced and
• if the time-dependent current consumption I (t) deviates from the respectively assigned value in the time-dependent course of a reference current consumption I _o (t), the time-duration-time-interval ratio V is increased by more than the specified tolerance.

The respective course of a dry matter concentration c (t) is over the time period t, starting with c (t = 0) = 0 for the pure liquid F ( Figure 6 ), increasing degressively, because the continuously pulsed flow of the powdery substance ṁ _P , viewed over the entire period t of the mixing process, is preferably constant (ṁ _P = const), but the duration of the dosing pulse Δt1 steadily decreases and thus a steadily decreasing one Amount of powdery substance m _{P is} metered in. The mass flow of powdery substance ṁ _{P is introduced into an existing almost unchangeable volume of the mixed product V M} (V _M ≈ constant) in the time period t of the entire mixing process with an almost unchangeable fill level N in the mixing container 100, with a density ρ _{M of} the mixed product M increasing, namely according to the time-dependent course of a dry matter concentration c (t), which grows _{to the predetermined end value c E.}

Figure 6 illustrates, as a function of the time-dependent course of a dry matter concentration c (t), how the respectively dosed amount of powdery substance mp = ṁ _P Δt1 steadily decreases, with the respectively assigned time-dependent current consumption At the end of the time interval between adjacent metering pulses .DELTA.t2, I _{(t) has approached the associated time-dependent course of a reference current consumption I o} (t) or is largely congruent with it. 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 any control measures in the sense explained above. Only when deviations from the permissible current excess or current shortfall ΔI1, ΔI2 occur, do the control mechanisms, as used in the first method in connection with the Figures 3 and 4 have been described.

These control measures with a variable duration-time interval ratio V require the control device 30 to be able to shorten or lengthen the duration of the metering pulse Δt1 with an unchanging time interval between adjacent metering pulses Δt2 or to adequately adjust the time interval between adjacent metering pulses Δt2 with the same duration of the metering pulse Δt1 lengthen or shorten.

The control measures according to the invention therefore essentially consist in both embodiments of the second method in that the duration of the metering pulse Δt1 and the time interval between adjacent metering pulses Δt2 are selected in such a way that at the end of the time interval between adjacent metering pulses Δt2 the time-dependent determined current consumption I (t) for stirring and / or mixing and homogenizing the temporarily present mixed product M * _{approximates the time-dependent course of a reference current consumption I o} (t), which is required for the relevant treatment of the homogenized mixed product M, within the scope of a practically relevant permissible tolerance.

LIST OF REFERENCE SIGNS OF THE ABBREVIATIONS USED

1000

Mixing device

100

Mixing tank

100.1

Container jacket

100.2

upper container bottom

100.3

lower container bottom (conical; conical)

100.4

Outlet nozzle

100.5

Inlet connection

100.6

Recirculation connection

20th

Inlet valve

30th

Control device

40

first drive motor

50

second drive motor

2

Valve body

2a

Valve seat

2 B

Seat opening

2c

Pipe connection

4th

Lantern housing

6th

Drive housing

8th

Valve closing member

8a

Valve disc

8b

Valve stem

10

Seat seal

12th

Return spring

14th

Control head housing

16

Signal pickup

18th

Feed line

22nd

Signal line

24

Stirring device

26th

Shearing and homogenizing device

28

Circulation line

D.

Default data

F.

liquid

Io

Initial value of a reference current consumption (for the homogenized mixed product M; I ₀ (t = 0) = I ₀ )

Io (t)

time-dependent course of a reference current consumption

I (t)

Time-dependent power consumption (for the temporarily present mixed product M *)

I * (t)

time-dependent current consumption deviating upwards

I ** (t)

time-dependent current consumption deviating downwards

ΔI1

permissible current excess

ΔI2

permissible current shortfall

M.

Mixed product

M *

temporarily available mixed product

N

Level

P.

powdery substance

S.

Control parameters

T

Mixing or dissolving temperature

V

Duration-time interval ratio (V = Δt1 / Δt2)

VM

Volume of the mixed product

ρM

Density of the mixed product

a

first part (immediate recirculation)

b

second part (indirect recirculation)

c

Dry matter concentration (powdery substance P in the liquid F)

c (t)

Time-dependent course of a dry matter concentration

cE

specified end value (of the time-dependent course)

H

Height of the liquid column

i

Dosing pulse

k

constant $\left(\mathrm{k}=\frac{{\stackrel{\mathrm{.}}{\mathrm{m}}}_{\mathrm{P.}}\left(\mathrm{t}\right)}{{\stackrel{\mathrm{.}}{\mathrm{m}}}_{\mathrm{F.}}\left(\mathrm{t}\right)}\right)$

k1

first constant of proportionality $\left(\mathrm{k}\right)$$\left(\mathrm{}1=\frac{{\stackrel{\mathrm{.}}{\mathrm{m}}}_{\mathrm{P.}}}{{\mathrm{m}}_{\mathrm{F.}}}\right)$

k2

second constant of proportionality $\left(\mathrm{k}\right)$$\left(\mathrm{}2\approx \frac{{\stackrel{\mathrm{.}}{\mathrm{m}}}_{\mathrm{P.}}}{{\mathrm{v}}_{\mathrm{M.}}}\right)$

mF

Amount of liquid

ṁF

Volume flow of liquid

ṁF (t)

time-dependent volume flow of liquid

ṁM

Volume flow of mixed product

mP

Amount of powdery substance

ṁP

Mass flow of powdery substance

ṁP (t)

Time-dependent mass flow of powdery substance

n1

first speed

n2

second speed

p

Pressure above the liquid column

t

Time (general) or duration of the mixing process

Δt1

Duration of the dosing pulse

Δt2

Time interval between adjacent dosing pulses

Claims (14)

1. 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,

   • in which the introduction and treatment of the pulverulent material (P) take place under the conditions of a dwell time behavior of a continuously working homogenous reaction tank such that

   o the liquid (F) is continuously fed to a mixing container (100), wherein
   the goal is a specified, temporally unchanging dry material concentration (c) of the pulverulent material (P) in the liquid (F),

   ∘ the liquid (F) and the pulverulent material (P) are constantly stirred and/or mixed to form a mixed product (M) and the mixed product (M) is homogenized, and

   ∘ the mixed product (M) is continuously discharged corresponding to the fed amounts of liquid (F) and pulverulent material (P),

   • in which a formulation of the mixed product (M), at least regarding the specified dry material concentration (c), and the reaction conditions are each specified in the form of default data (D),
   characterized in that

   • the pulverulent material (P) is discontinuously fed to the mixing container (100),

   • the discontinuous feeding of the pulverulent material (P) takes place in a pulsed manner by a chronological sequence of metering pulses (i) which are each characterized by a mass flow of the pulverulent material (ṁ_P), a duration of the metering pulse (Δt1), and a time interval between neighboring metering pulses (Δt2),

   • the specified dry material concentration (c) is defined by a fixed duration-to-time interval ratio V between the duration of the metering pulse (Δt1) and the associated time interval between neighboring metering pulses (Δt2) (V = Δt1/Δt2 = constant),

   • a time-dependent current consumption (I(t)) is ascertained which is proportional to a stirring and/or shearing and homogenizing power required for a temporarily present mixed product (M*),

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

   • at the end of the time interval between neighboring metering pulses (Δt2) and when the time-dependent current consumption (I(t)) deviates from the reference current consumption (I_o(t)) by more than a specified tolerance, either higher or lower, and in compliance with the fixed duration-to-time interval ratio (V), the duration of the metering pulse (Δt1) for the following metering pulse (i) is shortened in the first case and extended in the second case.
2. 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,

   • in which the introduction and treatment of the pulverulent material (P) take place under the conditions of a dwell time behavior of a continuously working homogenous reaction tank such that

   ∘ in a first phase, liquid (F) is presented in a mixing container (100) and the pulverulent material (P) is discontinuously fed to this liquid (F),

   ∘ the liquid (F) and the pulverulent material (P) are constantly stirred and/or mixed to form a mixed product (M) and the mixed product (M) is homogenized, and

   ∘ in a second phase, the mixed product (M) obtained in the first phase is recirculated via the mixing container (100) and corresponding amounts of pulverulent material (P) continue to be discontinuously fed to the recirculated amount of mixed product (M), and

   ∘ the mixed product (M) is recirculated until a time-dependent progression of a dry material concentration (c(t)) of the pulverulent material (P) in the mixed product (M) has grown to a specified end value (c_E),

   • and in which a formulation of the mixed product (M), at least regarding the time-dependent progression of a dry material concentration (c(t)) associated with the specified end value (c_E), and the reaction conditions are each specified in the form of default data (D),
   characterized in that

   • the discontinuous feeding of the pulverulent material (P) takes place in a pulsed manner by a chronological sequence of metering pulses (i) which are each characterized by a mass flow of the pulverulent material (ṁ_P), a duration of the metering pulse (Δt1), and a time interval between neighboring metering pulses (Δt2),

   • the time-dependent progression of a dry material concentration (c(t)) ending in the specified end value (c_E) is defined by the sequence of clearly determined metering pulses (i),

   • a time-dependent current consumption (I(t)) is ascertained which is proportional to a stirring and/or shearing and homogenizing power required for a temporarily present mixed product (M*),

   • a time-dependent progression of a reference current consumption (I_o(t)) is used from the default data (D) which is characteristic of the stirring and/or shearing and homogenizing power to be delivered to the homogenized mixed product (M) under the conditions of the associated time-dependent progression of a dry material concentration (c(t)), and

   • at the end of the time interval between neighboring metering pulses (Δt2) and when the time-dependent current consumption (I(t)) deviates from the respective associated value in the time-dependent progression of a reference current consumption (I_o(t)) by more than a specified tolerance, either higher or lower, the duration of the metering pulse (Δt1) for the following metering pulse (i) is shortened in the first case and extended in the second case.
3. The method according to claim 2,
   characterized in that
   time-dependent progressions of a dry material concentration (c(t)) without saturation are defined by a fixed duration-to-time interval ratio (V) between the duration of the metering pulse (Δt1) and the associated time interval between neighboring metering pulses (Δt2) (V = Δt1/Δt2 = constant).
4. The method according to claim 2,
   characterized in that
   time-dependent progressions of a dry material concentration (c(t)) with saturation are defined by a variable duration-to-time interval ratio (V) between the duration of the metering pulse (Δt1) and the associated time interval between neighboring metering pulses (Δt2) (V = Δt1/Δt2), wherein

   • when the time-dependent current consumption (I(t)) deviates from the respective associated value in the time-dependent progression of a reference current consumption I_o(t) by more than the specified upper tolerance, the duration-to-time interval ratio (V) is reduced, and

   • when the time-dependent current consumption I(t) deviates from the respective associated value in the time-dependent progression of a reference current consumption I_o(t) by more than the specified lower tolerance, the duration-to-time interval ratio (V) is increased.
5. The method according to one of the preceding claims,
   characterized in that
   the mass flow of the pulverulent material (ṁ_P) over the duration of the metering pulse (Δt1) is constant.
6. The method according to one of the preceding claims,
   characterized in that
   the shortening or the extending of the duration of the metering pulse (Δt1) takes place when a current corridor, determined by a permissible current excess (ΔI1) or a permissible current undershoot (ΔI2), respectively, is departed from by a current consumption that deviates upwards (I*(t)) or a current consumption that deviates downwards (l**(t)), wherein the permissible current excess and the permissible current undershoot (ΔI1, ΔI2) are each determined by a percentage of the associated reference current consumption (I_o; I_o(t)).
7. The method according to one of the preceding claims,
   characterized in that
   the measure of the shortening or the extending of the duration of the metering pulse (Δt1) is determined depending on the measure of the deviation of the time-dependent current consumption (I(t), I*(t), I**(t)) from the associated reference current consumption (I_o; I_o(t)).
8. The method according to one of the preceding claims,
   characterized in that
   the further formulation-dependent default data (D) on which the control of the introduction of the pulverulent material (P) into the at least one liquid (F) is based are obtained and saved from empirical values from earlier mixing processes, wherein these default data (D) are

   • a mass flow of the at least one liquid (ṁ_F),

   • a mixing or solution temperature (T),

   • a pressure above the liquid column (p),

   • rotational speeds (n1, n2) of apparatuses for stirring and/or mixing and homogenizing, and

   • a permissible current excess (ΔI1) and a permissible current undershoot (ΔI2) dependent on the associated reference current consumption (I_o; I_o(t)).
9. The method according to one of the preceding claims,
   characterized in that
   the expedient formulation-dependent control parameters (S) obtained over the course of controlling the introduction of the pulverulent material (P) into the at least one liquid (F), i.e.

   • the duration of the metering pulse (Δt1) and

   • the time interval between neighboring metering pulses (Δt2) are saved and used for following controls of identical formulations.
10. The method according to claim 2,
    characterized in that
    the recirculated mixed product (M) is divided into a first proportion (a) and into a second proportion (b),
    the first proportion (a) is fed directly to the mixing process, and
    the complementary second proportion (b) is guided via a storage volume and then also fed to the mixing process.
11. The method according to claim 10,
    characterized in that
    the first proportion (a) is between zero and one hundred percent of the recirculated mixed product (M).
12. A mixing device for performing the method according to claim 1, with a mixing container (100) that has an intake connection (100.5) for feeding in for a liquid (F), an outlet spigot (100.4) for discharge for a mixed product (M), and a stirring apparatus (24) and/or a shearing and homogenizing apparatus (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) can be adjusted either between fully closed (closed position) or fully open (open position), with the inlet valve (20) through which a pulverulent material (P) is introduced into the liquid (F), with a control apparatus (30) associated with the inlet valve (20) with which the valve closing member (8) can be transitioned to the closed or to the open position,
    characterized in that

    • the control apparatus (30) provides formulation-dependent default data (D) and formulation-dependent control parameters (S) in the form of the duration of the metering pulse (Δt1) and the time interval between neighboring metering pulses (Δt2),

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

    • the control apparatus (30) controls the closed or the open position of the valve closing member (8) depending on the time-dependent current consumption (I(t)) and in relation to the default data (D) and the control parameters (S).
13. The mixing device for performing the method according to claim 2 with the features of claim 12,
    characterized in that
    a circulation line (28) is provided, which branches off from a line attached to the outlet spigot (100.4) and discharges directly into the mixing container (100).
14. The mixing device according to claim 12 or 13,
    characterized in that
    the valve closing member (8) is designed, at least in its region that is in contact with powder, as a cylindrical rod with a constant diameter on which a valve disk (8a) is formed with a constant diameter.

Images