DE102017005573B3 - Method and mixing device for controlling the introduction of a powdery substance into a liquid for an in-line mixing process - Google Patents

Abstract

The invention relates to a method for controlling the introduction of a pulverulent substance (P) into a liquid (F) consisting of at least one component for an in-line mixing method according to subclaim 1 or the preamble of subclaim 2 and a mixing device for carrying out the respective method, ensure that the previously known disadvantages of the prior art are avoided. This is achieved procedurally with a first method, inter alia, by the fact that the discontinuous supply of the powdered substance (P) is effected in pulses by a chronological sequence of metering pulses (i), each of which is determined by a mass flow of the powdered substance ( Dosing pulse (.DELTA.t1) and a time interval of adjacent metering pulses (.DELTA.t2) are characterized, • that a time-dependent current consumption (I (t)) is determined, which is proportional to a mixing product for a temporarily present (M *) required mixing and / or shear and homogenizing power, and • that at the end of the interval of adjacent dosing pulses (Δt2) and on deviation of the time dependent current consumption (I (t)) from the reference current consumption (I) by more than a predetermined tolerance, either upwards or downwards below, while maintaining the ratio (V = Δt1 / Δt2), the duration of the dosing pulse (Δt1) for the subsequent Dos pulse (i) is shortened in the first case and extended in the second case

Description

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 of the powdery Substantial 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 pulverulent substance is carried out by reaction kinetics in a so-called batch-operated reaction vessel (mixing vessel). A certain amount of liquid is placed in the mixing container and it is so long supplied powdered substance until a desired or scheduled predetermined dry matter concentration of the powdered substance is present in the liquid. In this case, powdery substance and liquid are preferably continuously stirred and / or mixed to form a mixed product, and the mixed product is homogenized with the aim of 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 powdered substance is carried out by reaction kinetics in a so-called continuously operated reaction vessel (mixing vessel). A distinction is made between a single-pass and a multi-pass method. In the single-pass process, liquid and pulverulent substance, 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 homogenizing provide the theoretical postulate that the mixed product has the same composition (e.g., dry matter concentration) at each location 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). Related blending methods and associated blending devices have been made public to the public, for example, at the following Internet link: "http://www.gea.com/products/High-Shear-Inline-Mixer.jsp".

The US 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 fed in controlled amounts into a flow mixer and mixed therewith. 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 in dependence on this measurement, whereby the regulation of the supply of solids comprises separate control means.

The mixing devices mentioned above preferably also comprise so-called vacuum mixers which have a mixing container with a stirring and / or shearing and homogenizing device. The free surface of the liquid, which may for example have a free fill level with a height between 0.4 to 4 m in the mixing container, is subject to this height range correspondingly assigned negative pressure to atmospheric pressure, for example, 0.2 to 0.8 bar, so that the Liquid on the one hand 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 pipe leading, for example, to a powder reservoir is connected. The inlet nozzle and thus the pipe are formed shut off via an inlet valve controlling the supply of the powdery material, on the one hand completed the mixing device over this way to their environment and on the other hand automatically supplied in the powder reservoir an amount of powdered substance in case of need of liquid 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 used for example in the DE 10 2015 016 766 A is disclosed, has the advantage that the supply always takes place over the full open position of the inlet valve designed as a lift valve and thereby the risk of clogging of the inlet valve is minimized. Depending on the length of time of the respective open position, more or less large quantities of the pulverulent substance are intermittently introduced into the liquid, so that in principle there is the danger that corresponding aggregations of the pulverulent substance are produced by the stirring and / or shearing and homogenizing -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 powdery substance in an increase of the stirring and / or shearing and homogenizing power (drive power for the associated facilities), maps, which is necessary to that in this phase to treat the mixing process temporarily present mixed product. The course of the relevant drive power, which is proportional to the current consumption of the associated drive motors, corresponds approximately to a Gaussian normal distribution curve.

To make matters worse in the mixing process that the residence time behavior of a 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. Due to the inhomogeneities of the pulverulent substance in the mixed product as described above, there is the risk of microbiological growth (germ growth) which, in particular when the mixing container is heated and the inhomogeneities dwell in the mixing container for an above-average time under these thermal conditions, is conveyed. In addition, it comes under the latter conditions increasingly to the formation of deposits (so-called product fouling) on the heated walls of the mixing vessel, on the one hand hinders the heat transfer and on the other hand shortens the service life of the mixing vessel to the next due cleaning cycle.

So far, there is a 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 material 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 task is in procedural terms by a first method with the features of the independent claim 1 and solved 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 regard 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 in-line mixing method, the term "component" being understood to mean here usually can be discrete, separate liquids, which can also be fed separately from the mixing process. This first process, a so-called one-pass process, is typically used to prepare low viscosity, low dry matter base slurries, or e.g. for skimmed milk powder in water or cocoa powder in milk or, more generally, when a powdery substance with good solubility has to be dissolved in a short time. The introduction and treatment of the powdery substance, as seen in reaction kinetics, takes place virtually under the conditions of a residence time behavior of a continuously operating homogeneous reaction vessel in such a way that the liquid is fed continuously and the powdery substance is discontinuously fed to a mixing container, the target being a predetermined time immutable dry matter concentration of the powdered substance in the liquid is. 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 is classified as "scissors", where "homogenizing" is usually an integral part of mixing. The mixed product is continuously removed according to the supplied amounts of liquid and powdered material. In the mixing process in question, a recipe of the mixed product are predetermined at least in terms of the predetermined dry matter concentration and the reaction conditions in each case 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 a pulse-wise manner by a chronological sequence of metering pulses. The reaction conditions in this regard, in a preferred embodiment, that the powdery substance is sucked by a negative pressure (vacuum) in the headspace of the mixing vessel to atmospheric pressure. The metering pulses are each characterized by a flow rate of the powdery substance ṁ _P , a period of the metering pulse .DELTA.t1 and a time interval of adjacent metering pulses .DELTA.t2.

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: $$\text{c}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}\left(\text{t}\right)\mathrm{\Delta }\text{t1}}{{\stackrel{\cdot }{\text{m}}}_{\text{F}}\left(\text{t}\right)\mathrm{\Delta }\text{t2}}=\text{k}\frac{\mathrm{\Delta }\text{t1}}{\mathrm{\Delta }\text{t2}}=\text{kV=konstant}$$

By a fixed time-interval ratio V between the duration of the dosing pulse .DELTA.t1 and the associated time interval .DELTA.t2 of adjacent dosing pulses $\text{V}=\frac{\mathrm{\Delta }\text{t1}}{\mathrm{\Delta }\text{t2}}=\text{constant}$

is the predetermined dry matter concentration c defined according to equation (1), wherein in the most general case, the flow rate of the powdery substance ṁ _{P is} a time-dependent flow rate powdered substance ṁ _P (t) and a flow rate liquid ṁ _F a time-dependent flow rate liquid ṁ _F (t) are: $$\text{c}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}\left(\text{t}\right)\mathrm{\Delta }\text{t1}}{{\stackrel{\cdot }{\text{m}}}_{\text{F}}\left(\text{t}\right)\mathrm{\Delta }\text{t2}}=\text{k}\frac{\mathrm{\Delta }\text{t1}}{\mathrm{\Delta }\text{t2}}=\text{kV = constant}$$

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 both variables again becomes a constant $\text{k}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}\left(\text{t}\right)}{{\stackrel{\cdot }{\text{m}}}_{\text{F}}\left(\text{t}\right)}$

results. Since the time-duration distance ratio V is also kept constant as required, the predetermined dry matter concentration c is also constant in the necessary manner.

A significant control technical feature is 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. 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 I _o which is characteristic for the completely homogenized mixed product 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 interval of adjacent metering pulses .DELTA.t2 and on deviation of the time-dependent current consumption I (t) from the reference current consumption I _o 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 = .DELTA.t1 / .DELTA.t2 shortened the duration of the dosing pulse .DELTA.t1 for the subsequent metering 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 .DELTA.t2, based on the subsequent metering pulse.

The inventive control measure therefore consists essentially in the fact that the time duration of the metering pulse .DELTA.t1 and the time interval of adjacent metering .DELTA.t2 are selected so that at the respective end of the interval of adjacent metering pulses .DELTA.t2 the time-dependent determined current consumption I (t) for stirring and / or shearing and homogenizing the temporarily present mixed product to the reference current input I _o , which is required for the relevant treatment of the homogenized mixed product, within a practically acceptable tolerance.

Second procedure

With a view to a second method according to the invention, the invention relates to 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 is also classified as a multi-pass or multi-stage process. 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 have to be emulsified with oil, gum or flavors, because these blended products are mixed with the throughfeed 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 such that the mass flow of mixed product discharged from the mixing process corresponds to the mass flow mixed product plus the metered mass flow of powdered material via the recirculation.

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 progression of a dry substance concentration assigned to the predetermined end value and the reaction conditions.

The inventive idea of solution in the second method is that the discontinuous supply of the powdery substance takes place in a manner known per se in pulses by a chronological sequence of metering pulses. The reaction conditions in this regard, in a preferred embodiment and adequately to the first method, that the powdery substance is sucked by a negative pressure (vacuum) in the headspace of the mixing vessel to atmospheric pressure. The metering pulses are each characterized by a flow rate of the powdery substance ṁ _P , a period of the metering pulse .DELTA.t1 and a time interval of adjacent metering pulses .DELTA.t2.

• • 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.

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, wherein 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 course without saturation character equal amounts of powdered substance can be dosed within the absorption capacity or the solubility limit of the liquid at equal intervals, so that upon complete homogenization of the mixed product, a time-dependent approximately linearly increasing course of a dry matter concentration is established.
• • In the course of saturation, only steadily decreasing amounts of powdered material can be metered at equal intervals as part of the absorption capacity or the solubility limit of the liquid, so that, when the mixed product is completely homogenized, a time-dependent decreasing progression of a dry matter concentration occurs.

The time-dependent course of a dry matter concentration ending in the predetermined final value is defined by the sequence of uniquely determined metering pulses.

A significant control technical feature is 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. The latter always occurs in the form of an approximately Gaussian normal distribution, when a defined amount of powdered substance is introduced and treated in pulses 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 I (t) from, on a time-dependent course a reference current consumption I _o (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 power. The relevant course of a reference current consumption I _o (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 of adjacent metering pulses .DELTA.t2 and deviation of the time-dependent current consumption I (t) from the respectively assigned value in the time-dependent course of a reference current consumption I _o (t) by more than a predetermined tolerance, wherein a deviation can be either up or down , the duration of the dosing pulse .DELTA.t1 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 courses are each defined by a fixed time-interval ratio V between the duration of the metering pulse .DELTA.t1 and the associated time interval of adjacent metering pulses .DELTA.t2 (V = .DELTA.t1 / Δt2 = constant).

The respective course of a dry matter concentration c (t) is increasing over time t, because the continuous pulsed metered flow of the powdery substance ṁ _P , which is in the most case a time-dependent flow rate powdered substance ṁ _P (t), over the entire period t seen the mixing process, constant (M _P = constant). The flow rate of powdered substance ṁ _P is in the period t many times, namely (t / Δt2) times, introduced at an almost constant level in the mixing vessel in an immutable amount of liquid m _{F of} the present mixed product, with the time-dependent course of a dry matter concentration according to equation (2), as follows: $$\text{c}\left(\text{t}\right)=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}\frac{\text{t}}{\mathrm{\Delta }\text{t2}}\mathrm{\Delta }\text{t1}}{{\text{m}}_{\text{F}}+{\stackrel{\cdot }{\text{m}}}_{\text{P}}\frac{\text{t}}{\mathrm{\Delta }\text{t2}}\mathrm{\Delta }\text{t1}}$$

gesetzt werden, sodass sich nach Gleichung (2a) für den zeitabhängigen Verlauf einer Trockenstoff-Konzentration c(t) mit einer ersten Proportionalitätskonstante $\text{k1}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}}{{\stackrel{\cdot }{\text{m}}}_{\text{F}}}$

näherungsweise ergibt: $$\text{c}\left(\text{t}\right)\approx \frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}\frac{\text{t}}{\mathrm{\Delta }\text{t2}}\mathrm{\Delta }\text{t1}}{{\text{m}}_{\text{F}}}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}}{{\text{m}}_{\text{F}}}\frac{\mathrm{\Delta }\text{t1}}{\mathrm{\Delta }\text{t2}}\text{t}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}}{{\text{m}}_{\text{F}}}\text{Vt}=\text{k1Vt}$$

In most practical cases, because the first term of the subsequent relation is usually small compared to the second term, it can approximate $${\stackrel{\cdot }{\text{m}}}_{\text{P}}\frac{\text{t}}{\mathrm{\Delta }\text{<figure-callout id="1" label="t2 Δ t" filenames="DE102017005573B3\_0017.png,DE102017005573B3\_0018.png" state="{{state}}">t2 </figure-callout>}}\mathrm{\Delta }\text{t}\mathrm{1\; <<}{\text{m}}_{\text{P}}$$

are set so that according to equation (2a) for the time-dependent course of a dry matter concentration c (t) with a first proportionality constant $\text{k1}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}}{{\stackrel{\cdot }{\text{m}}}_{\text{F}}}$

approximates: $$\text{c}\left(\text{t}\right)\approx \frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}\frac{\text{t}}{\mathrm{\Delta }\text{t2}}\mathrm{\Delta }\text{t1}}{{\text{m}}_{\text{F}}}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}}{{\text{m}}_{\text{F}}}\frac{\mathrm{\Delta }\text{t1}}{\mathrm{\Delta }\text{t2}}\text{t}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}}{{\text{m}}_{\text{F}}}\text{Vt}=\text{k1Vt}$$

This control measure with a fixed time-interval ratio V (V = .DELTA.t1 / .DELTA.t2 = constant) inevitably leads in the same proportion to a corresponding reduction or lengthening of the time interval of adjacent metering pulses .DELTA.t2, 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 courses of a dry matter concentration with a saturation character, a second embodiment of the second method provides that these courses are defined by a variable time-interval ratio V between the time duration of the metering pulse Δt1 and the associated time interval of 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 predetermined tolerance, the time-duration ratio V decreases and
• • in case of deviation of the time dependent current consumption I (t) of the respectively assigned value in the time-dependent course of a reference current consumption I _o (t) by more than the predefined tolerance down the time-interval ratio increases V

becomes.

wie folgt, darstellt: $$\text{c}\left(\text{t}\right)=\frac{{\displaystyle {\sum }_{\text{t=0}}^{\text{t}}\left({\stackrel{\cdot }{\text{m}}}_{\text{P}}\left(\text{t}\right)\mathrm{\Delta }\text{t1}\right)}}{{\mathrm{\rho }}_{\text{M}}\left(\text{t}\right){\text{V}}_{\text{M}}}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}}{{\text{V}}_{\text{M}}}\frac{{\displaystyle {\sum }_{t=\text{0}}^t\mathrm{\Delta }\text{t1}}}{{\mathrm{\rho }}_{\text{M}}\left(\text{t}\right)}\approx \text{k2}\frac{{\displaystyle {\sum }_{t=0}^t\mathrm{\Delta }\text{t1}}}{{\mathrm{\rho }}_{\text{M}}\left(\text{t}\right)}.$$

The respective course of a dry matter concentration c (t) is increasing over time t degressively, because the continuous pulsed metered flow of the powdery substance ṁ _P , seen over the entire time t of the mixing process, while constant (ṁ _P = constant), However, the duration of the metering pulse .DELTA.t1 steadily decreases and thus a steadily decreasing amount of powdered material is metered. The flow rate powdered substance ṁ _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 (V _M ≈ constant), wherein a density ρ _{M of} the mixed product according to the time-dependent course of a dry matter concentration c (t) increases and the latter according to equation (3) with a second proportionality constant $\text{k2}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}}{{\text{V}}_{\text{M}}}.$

as follows, represents: $$\text{c}\left(\text{t}\right)=\frac{{\displaystyle {\Sigma }_{\text{t = 0}}^{\text{t}}\left({\stackrel{\cdot }{\text{m}}}_{\text{P}}\left(\text{t}\right)\mathrm{\Delta }\text{t1}\right)}}{{\mathrm{\rho }}_{\text{M}}\left(\text{t}\right){\text{V}}_{\text{M}}}=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}}{{\text{V}}_{\text{M}}}\frac{{\displaystyle {\Sigma }_{t=\text{0}}^t\mathrm{\Delta }\text{t1}}}{{\mathrm{\rho }}_{\text{M}}\left(\text{t}\right)}\approx \text{k2}\frac{{\displaystyle {\Sigma }_{t=0}^t\mathrm{\Delta }\text{t1}}}{{\mathrm{\rho }}_{\text{M}}\left(\text{t}\right)},$$

This control measure with a variable time-distance ratio V requires the ability of the controller, the duration of the dosing pulse .DELTA.t1 at fixed time interval of adjacent dosing .DELTA.t2 to shorten or extend or with unchanged time duration of the dosing pulse .DELTA.t1 the time interval to the time interval of adjacent dosing .DELTA.t2 adequate to lengthen or shorten.

The control technical measure according to the invention therefore essentially consists in both embodiments of the second method in that the time duration of the metering pulse Δt1 and the interval of adjacent metering pulses Δt2 are selected so that the current-dependent current consumption I (t) is determined at the respective end of the interval of adjacent metering pulses Δt2. for stirring and / or shearing and homogenizing the temporarily present mixed product to the time-dependent course of a reference current absorption I _o (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 the fact that a controllable opening for the supply of the powdery substance only knows either a full open position or a closed position.

In order to make the control of the mixing process as manageable as possible, another embodiment provides for both methods that the shortening or extension of the duration of the metering pulse then takes place when a current corridor determined by an allowable current overflow or a permissible current undershoot is deviated by an upwardly deviating one Power consumption or a downward deviating power consumption is left. The permissible current exceeding and the permissible current underflow are each determined by a percentage of the associated reference current consumption or the associated time-dependent course of a reference current consumption. In order for the controller to operate as sensitively as possible in this regard, it is further proposed that the degree of shortening or lengthening of the duration of the metering pulse is determined as a function of the degree of deviation of the time-dependent current consumption from the associated 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 former mixing processes are obtained and stored, said default data, a flow rate of the at least one liquid, a reaction temperature, a reaction pressure, speeds of means for stirring and / or shearing and homogenizing and dependent on the associated reference current consumption or the associated time-dependent course of a reference current consumption allowable current exceeding and a permissible current underflow are.

In order to make operational data obtained in practice for a specific recipe usable for subsequent mixing processes having the same formulation, a further 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 dosing pulse and the time interval of adjacent dosing 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 comprises, in a manner known per se, a mixing container which has an inlet connection for the supply of a liquid, an outlet connection for removal of a mixed product and a stirring device and / or a shearing and homogenizing device. At the mixing container an inlet valve is arranged with a valve closure member. The inlet valve is adjustable with the valve closure member either fully closed (closed position) or fully open (open position). A powdery substance is introduced into the liquid with the inlet valve, wherein the valve 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 powdery substance exclusively in its full open position and thus minimizes the constipation susceptibility from the outset to optimize even further in this regard and to avoid dead and cavities, for example, provides an advantageous embodiment that the valve closing member at least is formed in its powder-loaded area as a diameter-equal cylindrical rod, at the same diameter a valve plate is formed. When the inlet valve in is its full open position, the valve closure member is due to this embodiment largely moved out of the fully formed flow of the powdery substance so that it is not a flow obstacle on the one hand and on the other hand is a seat seal, which is recorded in the valve plate, 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 affected only by the near-wall, stagnant flow in this edge region.

list of figures

• 1 in schematischer Darstellung eine Mischvorrichtung für ein Inline-Mischverfahren, das im Eindurchgang-Verfahren betrieben wird;
• 1a in schematischer Darstellung eine Mischvorrichtung für ein Inline-Mischverfahren, das im Mehrdurchgang-Verfahren betrieben werden kann;
• 2 in perspektivischer Darstellung und im Halbschnitt ein Einlaufventil zur Zuführung des pulverförmigen Stoffes in Mischvorrichtungen gemäß den 1 und 1a ohne ein Steuerkopfgehäuse;
• 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;
• 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 und mit einem Zeitabstand benachbarter Dosierimpulse Δt2/2;
• 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
• 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 will become apparent from the following description and the accompanying drawings of the drawings and from the claims. While the invention is implemented in various embodiments of a first and a second method for controlling the introduction of a powdery substance in a liquid consisting of at least one component for an in-line mixing method, in the drawing a preferred first and second method and a mixing device for Implementation of the respective method described. Show it

• 1 a schematic representation of a mixing device for an in-line mixing process, which is operated in the one-pass process;
• 1a a schematic representation of a mixing device for an in-line mixing process, which can be operated in a multi-pass process;
• 2 in a perspective view and in half section, an inlet valve for supplying the powdery substance in mixing devices according to the 1 and 1a without a steering head housing;
• 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 time duration of the metering pulse .DELTA.t1 and with a time interval of adjacent metering pulses .DELTA.t2;
• 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 time duration of the metering pulse .DELTA.t1 and with a time interval of adjacent metering pulses .DELTA.t2 / 2;
• 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 .DELTA.t1 and with a constant time interval of adjacent metering pulses .DELTA.t2 for realizing a time-dependent approximately linearly increasing course of a dry matter concentration (without saturation character ) and
• 6 in a qualitative representation for the second method, a time-dependent current consumption I (t) for a sequence of metering pulses with a steadily decreasing duration of the metering pulse .DELTA.t1 and with a constant time interval of adjacent metering pulses .DELTA.t2 for realizing a time-dependent degressive course of a dry matter concentration (with saturation character) ,

Mixing device for first method (FIGS. 1 and 2)

A mixing device 1000 has, inter alia, a mixing container 100 on, from a preferably cylindrical container shell 100.1 , an upper tank bottom 100.2 and a lower tank bottom 100.3 consists. The bottom tank bottom 100.3 preferably tapers downwards, usually cone-shaped or in the form of a circular cone, and has at the lower end an outlet connection 100.4 for a mixed product M on top of that with a mass flow mixed product ṁ _M is dissipated. The mixing container 100 is via an inlet connection 100.5 a liquid F with a flow of liquid ṁ _F continuously supplied, which is a free level N forms, above the usually at the mixing device in question 1000 (Vacuum mixer) a pressure p , a negative pressure relative to atmospheric pressure, prevails.

On the container jacket 100.1 or the bottom of the container 100.3 is an inlet valve 20 arranged. The inlet valve 20 serves the discontinuous supply of a powdery substance P with a flow rate powdered substance ṁ _P , which via a feed line 18 is fed into the liquid F or in the mixed product M , The inlet valve 20 is a control device 30 associated with a control head housing 14 the inlet valve 20 communicates via a signal line 22 and the inlet valve 20 if necessary, converted into its open or closed position. In the mixing container 100 is located above a first drive motor 40 with a rather low first speed n1 driven stirring device 24 , preferably centrally arranged and mechanically acting, which preferably into the region of the lower container bottom 100.3 reaches down. The required stirring effect can also be achieved by fluid mechanical means, for example by pumping the liquid F or the mixed product M via a circulation line and preferably tangential entry of the liquid F or the mixed product M in the mixing container 100 , reached or supported.

The following is meant to be for convenience when referring to liquid F is reduced, the mixed product M If so, 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 off-center in this one via a second drive motor 50 with a rather high second speed n2 powered shearing and homogenizing device 26 intended. This sucks the liquid F preferably on the one hand from above and on the other hand throws them annularly near the wall near the bottom of the container 100.3 such that preferably a directed from outside to inside circulation flow in the mixing container 100 formed. When passing through the shearing and homogenizing device 26 become liquid F and powdered substance P or the resulting mixed product M very intensive mechanical mixing and preferably homogenized.

The inlet valve 20 is designed as a lifting valve ( 2 ). It points in a valve housing 2 a valve seat 2a and a cooperating with this valve disc 8a on, on a valve closing member 8th is trained. As a rule, the valve closing member takes 8th a seat seal 10 on, in the closed position of the inlet valve 20 in cooperation with the valve seat 2a the seal causes. The valve seat 2a has a seat opening 2 B through which the via a pipe connection 2c from the supply line 18 supplied powdery substance P into the liquid F is introduced. The above the junction of the inlet valve 20, preferably directly in the wall of the mixing container 100 is arranged, pending liquid F forms a height with its liquid column H so that the static pressure in the area of the connection point and thus also in the area of the seat opening 2 B from the pressure p (preferably negative pressure) and the static pressure resulting from the height of the liquid column H results, composed. In a vacuum mixer with a negative pressure of, for example, p = 0.2 to 0.8 bar and a height of the liquid column corresponding to this pressure range H = 0.2 to 4 m prevails in the area of the seat opening 2 B always a negative pressure to atmospheric pressure, so the seat opening 2 B from the mixing container 100 out sucked and thus the powdery substance P is sucked in. The seat opening 2 B is with the valve plate 8a between completely closed, the closed position, or fully open, the open position, adjustable. The valve housing 2 is over a Latemen housing 4 with a drive housing 6 for driving the valve closing member 8th connected. It is preferably a pressure medium-loaded spring / piston drive, wherein a return spring 12 the valve closure member 8th usually transferred to its closed position when the drive housing 6 not with pressure medium, preferably compressed air, is acted upon. A valve rod 8b , on the valve plate 8a of the valve closing member 8th attacks and through the drive housing 6 through and into the steering head housing 14 is guided, serves on the drive side, the axial guidance of the valve closure member 8th , The valve closure member 8th is formed at least in its powder-loaded area as the same diameter cylindrical rod, at the same diameter of the valve disc 8a is formed. Through this structural design hollow and dead spaces in the valve housing 2 in the range of movement of the valve closure member 8th avoided, with the valve closing member 8th with its end valve disk 8a and the associated seat seal 10 as far as possible from the fully flowed through area of the valve housing 2 pull back.

The control device 30 ( 1 ) has at least one signal sensor 16 on. The at least one signal sensor 16 is a measuring device, for example, for mixing parameters, such as the flow rate liquid ṁ _F , the pressure p in the mixing container 100 , a mixing or solution temperature T 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) the stirring and / or shearing and homogenizing device 24 , 26. The signal sensor 16 for the time-dependent current consumption I (t) of the second drive motor 50 the shearing and homogenizing device 26 is in 1 exemplified. 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, from one to the outlet 100.4 branched line and directly into the mixing vessel 100 , preferably via its own recirculation connection 100.6 , opens. The line connected to the outlet connection 100.4 can be routed via one or more storage containers and finally to the inlet connection 100.5 be connected. These structural measures serve procedural purposes, which have already been explained above. To avoid repetition, go to a complete description of the mixing device 1000 according to 1a waived and in this regard to the description 1 directed.

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

The introduction and treatment of the powdery substance P occurs almost under the kinetic reaction conditions of a residence time behavior of a continuously operating homogeneous reaction vessel. It will be the liquid F via the inlet connection 100.5 with the flow of liquid ṁ _F which, in the most general case, is a time-dependent volume flow of liquid ( ṁ _F (t) ) may be continuous and the powdered substance P via the inlet valve 20 discontinuously with the flow rate powdered substance ṁ _P , which in the most general case also a time-dependent flow rate powdered material ( ṁ _P (t) ), the mixing process in the mixing tank 100 supplied, the target the predetermined, fixed time immutable dry matter concentration c of the powdery substance P in the liquid F is. The liquid F and the powdery substance P are constantly stirred and / or to the mixed product M mixed and the mixed product M is homogenized. The mixed product M is according to the supplied amounts of liquid F and powdered substance P with the mass flow of mixed product ṁ _M continuously dissipated. It is a recipe of the mixed product M at least with regard to the given dry matter concentration c and the reaction conditions are each specified in the form of default data D.

The discontinuous supply of the powdery substance P takes place over a period of time t in pulses by a chronological sequence of dosing pulses i ( 3 and 4 ), each by the flow rate of the powdery substance ṁ _P , a period of the metering pulse .DELTA.t1 and a time interval between adjacent metering pulses .DELTA.t2 are characterized. The mass flow of the powdery substance ṁ _P is basically a time-dependent flow rate of powdery substance ṁ _P (t) as already stated above, wherein the present application subject due to the design and the switching characteristic of the inlet valve 20 Approximately from a time-independent and thus constant flow rate powdered substance ṁ _{P is} assumed (ṁ _P = constant). According to equation (1), the predetermined constant dry matter concentration c by a likewise fixed, ie constant time-space-time ratio V between the duration of the dosing pulse .DELTA.t1 and the associated time interval of adjacent metering pulses Δt2 ( V = .DELTA.t1 / .DELTA.t2 = constant).

For the duration of the dosing pulse .DELTA.t1 according to 3 is for example on the second drive motor 50 the shearing and homogenizing device 26 the same in 3 over time t applied time-dependent current consumption l (t) is determined or measured. The latter is proportional to one in the mixing vessel 100 immediately after the metering pulse i temporarily present mixed product M * required shearing and homogenizing performance ( 1 ), from the shear and homogenizer facility 26 at this stage of the treatment. The course of the time-dependent current consumption I (t) is similar to a Gaussian distribution curve, it increases with the intermittently entering mass flow of powdery substance ṁ _P , reaches a maximum, and then after dissolution of the powdery substance P , ie at a then achieved homogenized mixed product M to gradually decrease to an initial value.

This typical behavior is used in accordance with the invention in terms of control engineering, by using the default data D a reference current consumption I _o is used, which is characteristic of the homogenized mixed product M stirring and / or shearing and homogenizing power to be provided.

If the interval between adjacent metering pulses .DELTA.t2 is not sufficient to a metered amount of powdered substance ṁ _P = ṁ _P .DELTA.t1 Dissolve, mix and homogenize, is a time-dependent upward different current consumption I * (t) measured so that in this state of temporarily present mixed product M * at the end of the time interval of adjacent metering pulses .DELTA.t2 a new dosing pulse i not yet displayed. Will under comparable conditions a time-dependent downward different current consumption I ** (t) determined, then this may be an indication that the by the interval between adjacent metering pulses .DELTA.t2 also defined stirring and / or shearing and homogenizing phase is excessively long or that no phase adequate amount of powdered substance m _p was dosed.

The method described above is taken into account by the method of control according to the invention in that at the end of the time interval of adjacent metering pulses .DELTA.t2 and in case of deviation of the time-dependent power consumption I (t) from the time-independent and therefore constant reference current consumption I _o ( I _o = constant) by more than a predetermined tolerance, either up or down, and in compliance with the fixed time-to-space ratio V ( V = .DELTA.t1 / .DELTA.t2 = constant) the duration of the dosing pulse .DELTA.t1 for the subsequent dosing pulse i shortened in the first case and extended in the second case. The tolerance consists in a specification of a permissible current violation ΔI1 and in a permissible current underflow .DELTA.I2 ( 3 ).

The case of shortening is in 4 represented, wherein in the illustrated case example, the duration of the metering pulse .DELTA.t1 and thus also the associated period of adjacent metering pulses .DELTA.t2 was halved. Also in this dosing is again at the end of the period of adjacent metering pulses .DELTA.t2 a check made, whether within the given tolerance, a time-dependent up or down current consumption I * (t) . I ** (t) is present, which requires a necessary correction in the sense outlined above.

Shortening or lengthening the duration of the dosing pulse .DELTA.t1 occurs when one through the allowable current overshoot ΔI1 or the permissible current underflow .DELTA.I2 particular current corridor by the time-dependent upward or downward deviating current consumption I * (t) . I ** (t) will leave. The permissible current exceeded and the permissible current underflow ΔI1 . .DELTA.I2 are preferably each by a percentage of the associated reference current consumption I _o certainly. Furthermore, the degree of shortening or lengthening the duration of the metering pulse is preferably .DELTA.t1 depending on the degree of deviation of the time-dependent current consumption I (t) from the assigned reference current consumption I _o certainly. The ultimately by the respective recipe of the mixed product M certain permissible excess current ΔI1 and permissible current underflow .DELTA.I2 can be part of the default 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 gained targeted recipe-dependent control parameters S , namely the duration of the metering pulse .DELTA.t1 and the time interval between adjacent metering pulses .DELTA.t2 , are saved and used for subsequent control of the same recipes.

The control device 30 the mixing device 100 According to the invention, it is set up in such a way that these are the formulation-dependent default data D and the recipe-dependent control parameters S in the form of the duration of the metering pulse .DELTA.t1 and the time interval of adjacent metering pulses .DELTA.t2 can provide. The control device 30 furthermore has at least the signal sensor designed as a measuring device 16 on ( 1 ), the time-dependent current consumption I (t) of the stirring device 24 and / or the shearing and homogenizing device 26 detected ( 3 . 4 ). The control device 30 controls the closing or the open position of the valve closure member according to the invention 8th ( 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 at.

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 occurs under the reaction kinetic conditions of a residence time behavior of a continuously operating homogeneous reaction vessel. It becomes liquid in a first phase F in the mixing container 100 submitted (feed via the inlet port 100.5) and the powdery substance P this total liquid F is introduced via the inlet valve 20 fed discontinuously with the flow rate powdered substance ṁ _P , wherein at the end of the first phase, a dry matter concentration c is reached, which is below an end value specified for the end of the entire mixing process c _E lies. The liquid F and the powdery substance P be by means of the stirring device 24 continuously stirred and / or by means of the shearing and homogenizing device 26 to the mixed product M mixed and the mixed product M is homogenized.

In a second phase, the mixed product obtained in the first phase becomes M over the mixing container 100 recirculates and it will continue to recycle the amount of mixed product M corresponding amounts of powdered substance P fed discontinuously. The amount of mixed product removed in the recirculation M can in a first share a and in a second share b be split ((a + b) M). The mass balance is therefore in the second phase at a constant level N mandatory according to 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 to the preset final value c _E grew up.

In the mixing process in question are a recipe of the mixed product M at least in terms of the given final value c _E associated time-dependent course of a dry matter concentration c (t) and the reaction conditions each in the form of the default data D specified.

The inventive idea of solution corresponds in essential features to that according to the first method. Through the multi-level Sequence in the second phase of the second method results in the time-dependent course of a dry matter concentration c (t) which is according to plan in the specified final value c _E ending, being between the course of a dry matter concentration c (t) without saturation character (approximately linear time-dependent course, see 5 ) or with saturation character (degressive time-dependent course, see 6 ) is to be distinguished. The in the given final value c _E ending time-dependent course of a dry matter concentration c (t) is due to the sequence of certain dosing pulses i , ie clearly defined by the duration of the dosing pulse .DELTA.t1 and the time interval of adjacent metering pulses .DELTA.t2 , defined (see 5 . 6 ).

As soon as the powdery substance P in the receiving liquid F (first phase) and in the receiving mixed product M (second phase) evenly distributed, ie distributed as homogeneously as possible and possibly dissolved it sounds the time-dependent current consumption I (t) from, on a time-dependent course of a reference current consumption I _o (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 stirring and / or shearing and homogenizing performance (see 5 : Approximately linear time-dependent course of a reference current consumption I _o (t) ; 6 : degressive time-dependent course of a reference current consumption I _o (t) ). The time-dependent course of a reference current consumption I _o (t) starts at the time t = 0, to which only the pure liquid F is present, with an initial value I _o ( t = 0) (see 5 . 6 ). The relevant course of a reference current consumption I _o (t) is in the default data D deposited, and it depends on the recipe of the mixed product M and the reaction conditions for the mixing process.

At the end of the time interval of adjacent metering pulses .DELTA.t2 and in the case of a deviation of the time-dependent current consumption l (t) from the respectively assigned value in the time-dependent course of a reference current consumption I _o (t) by more than a given tolerance, with a deviation either up or down (see 5 . 6 ), the duration of the dosing pulse .DELTA.t1 shortened for the subsequent metering pulse in the first case and extended 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 ( 5 ), as can be described by the equations (2, 2a) given above ( c (t) = k1 V t), provides an embodiment of the second method that this course by a fixed time-space ratio V between the duration of the dosing pulse .DELTA.t1 and the associated time interval of adjacent metering pulses .DELTA.t2 is defined ( V = .DELTA.t1 / .DELTA.t2 = constant). For deviations from the time-dependent course of a reference current consumption I _o (t) is according to the invention at a constant time-space ratio V the duration of the dosing pulse .DELTA.t1 shortened (as in 4 in contrast to 3 exemplified qualitatively) or extended. This control measure with a fixed time-space ratio V inevitably leads in the same proportion to a corresponding shortening or lengthening of the time interval of adjacent metering pulses .DELTA.t2 , based on the following 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 ( 6 ) as can be described by equation (3) given above $\left(\text{c}\left(\text{t}\right)\approx \text{k2}\frac{{\displaystyle {\Sigma }_{t=0}^t\mathrm{\Delta }\text{t1}}}{{\mathrm{\rho }}_{\text{M}}\left(\text{t}\right)}\right).$

provides a further embodiment of the second method, that this course by a variable time-distance ratio V between the duration of the dosing pulse .DELTA.t1 and the associated time interval of adjacent metering pulses .DELTA.t2 is defined ( V = .DELTA.t1 / .DELTA.t2 ≠ constant), where

• • if the time-dependent current consumption deviates I (t) from the respective assigned value in the time-dependent course of a reference current consumption I _o (t) by more than the given tolerance up the time-space ratio V scaled down and
• • if the time-dependent current consumption deviates I (t) from the respective assigned value in the time-dependent course of a reference current consumption I _o (t) by more than the predetermined tolerance down the time-to-space ratio V is enlarged.

The respective course of a dry matter concentration c (t) is about the time t , starting at c (t = 0) = 0 for the pure liquid F ( 6 ), degressively increasing, because of the continuous impulsively metered flow rate of the powdery substance ṁ _P , over the entire period of time t Although the mixing process is preferably constant (ṁ _P = const), the duration of the metering pulse .DELTA.t1 However, steadily decreasing and thus a steadily decreasing amount of powdery substance m _p is metered. The mass flow of powdery substance ṁ _P is in the period t the entire mixing process at an almost constant level N in the mixing container 100 in a present almost invariable volume of the mixed product V _M brought in ( V _M ≈ constant), where a density ρ _M of the mixed product M increases, according to the time-dependent course of a dry matter concentration c (t) which is at the preset final value c _E grows up.

6 illustrates as a function of the time-dependent course of a dry matter concentration c (t) how the respectively metered amount of powdered substance m _P = ṁ _P Δt1 steadily decreases, wherein the respectively associated time-dependent current consumption I (t) each at the end of the time interval of adjacent metering pulses .DELTA.t2 to the associated time-dependent course of a reference current consumption I _o (t) has approximated or is largely congruent with this. A related course describes a successful mixing process, on the one hand the mixed product M on the other hand is energy-efficient. It does not require control measures in the sense explained above. Only if deviations from the permissible current overshoot or undershoot ΔI1 . .DELTA.I2 occur analogously, the control mechanisms, as they relate to the first method in connection with the 3 and 4 have been described.

These control measures with a variable time-space ratio V require from the controller 30 the ability to set the duration of the dosing pulse .DELTA.t1 at constant time interval of adjacent metering pulses .DELTA.t2 shorten or extend or with unchanged duration of the dosing pulse .DELTA.t1 the time interval between adjacent metering pulses .DELTA.t2 adequately extend or shorten.

The control technical measures according to the invention thus exist in essence in both embodiments of the second method in that the duration of the metering pulse .DELTA.t1 and the time interval of adjacent metering pulses .DELTA.t2 be selected so that at the respective end of the time interval of adjacent metering pulses .DELTA.t2 the time-dependent determined power consumption I (t) for stirring and / or shearing and homogenizing the temporarily present mixed product M * to the time-dependent course of a reference current consumption I _o (t) for the treatment of the homogenized mixed product M is required, within a practice-relevant permissible tolerance approaches.

LIST OF REFERENCE NUMBERS

1000

mixing device

100

mixing tank

100.1

container jacket

100.2

upper tank bottom

100.3

lower tank bottom (conical, cone-shaped)

100.4

outlet connection

100.5

inflow connection

100.6

Rezirkulationsanschluss

20

inlet valve

30

control device

40

first drive motor

50

second drive motor

2

valve housing

2a

valve seat

2 B

seat opening

2c

pipe connection

4

lantern housing

6

drive housing

8th

Valve closure member

8a

valve disc

8b

valve rod

10

seat seal

12

Return spring

14

Control head housing

16

signal sensor

18

feed

22

signal line

24

agitator

26

Shearing and homogenizing device

28

circulation line

D

default data

F

liquid

I _o

Reference current consumption (for the homogenised mixed product M )

I _o (t)

Time-dependent course of a reference current consumption

I (t)

time-dependent current consumption (for the temporarily present mixed product M * )

I * (t)

time-dependent upwards deviating current consumption

I ** (t)

time-dependent downwards deviating current consumption

ΔI1

permissible current exceeded

.DELTA.I2

permissible current underflow

M

mixed product

M *

temporarily present mixed product

N

filling level

P

powdery substance

S

control parameters

T

Mixing or solution temperature

V

Duration-time interval ratio ( V = .DELTA.t1 / .DELTA.t2 )

V _M

Volume of the mixed product

ρ _M

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

c _E

predetermined final value (of the time-dependent course)

H

Height of the liquid column

i

metering pulse

k

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

k1

first proportionality constant $\left(\text{<figure-callout id="1" label="k" filenames="DE102017005573B3\_0017.png,DE102017005573B3\_0018.png" state="{{state}}">k</figure-callout>}1=\frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}}{{\stackrel{\cdot }{\text{m}}}_{\text{F}}}\right)$

k2

second proportionality constant $\left(\text{k2}\approx \frac{{\stackrel{\cdot }{\text{m}}}_{\text{P}}\left(\text{t}\right)}{{\mathrm{\rho }}_{\text{M}}{\text{V}}_{\text{M}}}\right)$

m _F

Amount of liquid

ṁ _F

Flow of liquid

ṁ _F (t)

time-dependent volume flow of liquid

ṁ _M

Mass flow of mixed product

m _p

Amount of powdery substance

ṁ _p

Flow rate of powdery substance

ṁ _P (t)

Time-dependent flow rate of powdery substance

n1

first speed

n2

second speed

p

Pressure above the liquid column

t

Time

.DELTA.t1

Duration of the dosing pulse

.DELTA.t2

Time interval of adjacent dosing pulses

Claims (14)

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, wherein the introduction and treatment of the pulverulent substance (P) under the conditions of a residence time behavior of a continuously operating homogeneous Reaction vessel takes place in such a way o that the liquid (F) continuously and the powdery substance (P) are discontinuously fed to a mixing vessel (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) accordingly the amount of liquid (F) and powdered substance (P) supplied is continuously removed in which a recipe of the mixed product (M) at least with respect to the predetermined dry matter concentration (c) and the reaction conditions are given in the form of default data (D), • in which the discontinuous supply of the powdery substance (P) in pulses by a temporal sequence Metering pulses (i) are carried out, which are each characterized by a flow rate of the powdery substance (ṁ _P ), a time duration of the metering pulse (.DELTA.t1) and a time interval of adjacent metering pulses (.DELTA.t2), • in which the predetermined dry matter concentration (c) a fixed time-distance ratio V between the duration of the metering pulse (.DELTA.t1) and the associated time interval of adjacent metering pulses (.DELTA.t2) is defined (V = .DELTA.t1 / .DELTA.t2 = constant), • in which a time-dependent current consumption (I (t)) determined which is proportional to an agitator and / or shear required for a temporary mixed product (M *) Homogenizing power is •, in which from the default data (D) a reference current consumption (I _o ) 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 of adjacent metering pulses (.DELTA.t2) and deviation of the time-dependent current consumption (I (t)) of the reference current consumption (I _o ) by more than a predetermined tolerance, either up or down, and in compliance with the fixed time-to-space ratio (V), the duration of the dosing pulse (Δt1) for the subsequent dosing pulse (i) is shortened in the first case and in the second Case is extended. 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, wherein the introduction and treatment of the pulverulent substance (P) under the conditions of a residence time behavior of a continuously operating homogeneous Reaction vessel takes place in such a way o that in a first phase liquid (F) presented in a mixing vessel (100) and this liquid (F) the powdery substance (P) is discontinuously supplied, o that the liquid (F) and the powdery substance (P ) are continuously stirred and / or mixed into 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 container (100) and further the recirculated amount of mixed product (M) corresponding amounts of powdered material (P) fed discontinuously be, and o that the mixed product (M) is recirculated until a time-dependent curve of a dry matter concentration (c (t)) of the powdered substance (P) in the mixed product (M) to a predetermined final value (c _E ) is grown , And in which a recipe of the mixed product (M) at least in terms of the predetermined end value (c _E ) associated time-dependent curve of a dry matter concentration (c (t)) and the reaction conditions are each given in the form of default data (D), characterized characterized in that the discontinuous supply of the pulverulent substance (P) is effected in pulses by a chronological sequence of metering pulses (i), in each case by a mass flow of the pulverulent substance (ṁ _P ), a duration of the metering pulse (Δt1) and a time interval between adjacent metering pulses (At2) are characterized in that • in the predetermined final value (C _e) ending time-dependent course of a dry matter concentration (c ( t)) 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 mixing and / or shear rate required for a temporarily present mixed product (M *) and homogenizing power is, • that from the default data (D) is a time-dependent course of a reference current consumption (I _o (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 power, and • that at the end of the time interval of adjacent metering pulses (.DELTA.t2) and deviation of the time-dependent current consumption (I (t)) of the respectively associated value in the time-dependent course of a reference current consumption (I _o (t)) by more than a predetermined tolerance, either up or down, the duration of the dosing pulse (.DELTA.t1 ) is shortened for the subsequent metering pulse (i) in the first case and extended in the second case. Method according to Claim 2 , characterized in that time-dependent curves of a dry matter concentration (c (t)) without saturation character are defined by a fixed time-space ratio (V) between the duration of the metering pulse (Δt1) and the associated time interval of adjacent metering pulses (Δt2) ( V = Δt1 / Δt2 = constant). Method according to Claim 2 , characterized in that time-dependent curves of a dry matter concentration (c (t)) having a saturation character are defined by a variable time-interval ratio (V) between the duration of the metering pulse (Δt1) and the associated time interval of adjacent metering pulses (Δt2) ( V = .DELTA.t1 / .DELTA.t2), where • in the case of a deviation of the time-dependent current consumption (I (t)) from the respectively assigned value in the time-dependent course of a reference current consumption (I _o (t)) by more than the predetermined tolerance upwards, the time duration interval Ratio (V) reduced and • in the case of a deviation of the time-dependent current consumption (I (t)) from the respectively assigned value in the time-dependent course of a reference current consumption (I _o (t)) by more than the predetermined tolerance downwards, the time-space / time interval ratio ( V) is increased. Method according to one of the preceding claims, characterized in that the flow rate of the powdery substance (ṁ _P ) over the period of the metering pulse (.DELTA.t1) is constant. Method according to one of the preceding claims, characterized in that the shortening or the extension of the duration of the dosing pulse (Δt1) then takes place when a by an allowable current exceeding (ΔI1) or a permissible current drop (ΔI2) in each case certain current corridor is left by an upwardly deviating current consumption (I * (t)) or a downward deviating current consumption (I ** (t)), wherein the permissible excess current and the permissible current undershooting (ΔI1, ΔI2 ) are each determined by a percentage of the associated reference current consumption (I _o ; I _o (t)). Method according to one of the preceding claims, characterized in that the degree of shortening or lengthening of the duration of the metering pulse (Δt1) as a function of the degree of deviation of the time-dependent current consumption (I (t), I * (t), I ** (t)) is determined by the associated reference current consumption (I _o ; I _o (t)). Method according to one of the preceding claims, characterized in that the control of the introduction of the powdery substance (P) in the at least one liquid (F) underlying further formulation-dependent specification data (D) are obtained from empirical values of previous mixing processes and stored, said default data (D) • a flow rate of the at least one liquid (ṁ _F ), • a reaction temperature (T), • a reaction pressure (p), • speeds (n1, n2) of devices for stirring and / or mixing and homogenizing and • one of the associated reference current consumption (I _o ; I _o (t)) dependent allowable current exceedance (.DELTA.I1) and an allowable current underflow (.DELTA.I2) are. Method according to one of the preceding claims, characterized in that in the course of the control of the introduction of the powdery substance (P) in the at least one liquid (F) obtained targeted formulation-dependent control parameters (S) • duration of the dosing pulse (.DELTA.t1) and • time interval of adjacent Dosing pulses (Δt2) stored and used for subsequent control of the same recipes. Method according to Claim 2 , characterized in that the recirculated mixed product (M) in a first portion (a) and in a second portion (b) is divided, that the first portion (a) is fed directly to the mixing process and that the second portion (b) via led a storage volume and then also fed to the mixing process. Method according to Claim 10 , characterized in that the proportion of the mixing product (M) recirculated immediately above the mixing process is between zero and one hundred percent of the recirculated mixed product (M). Mixing device for performing the method according to Claim 1 with a mixing container (100) having a feed connection (100.5) for the supply of a liquid (F), a discharge connection (100.4) for removal of a mixed product (M) and a stirring device (24) and / or a shear and homogenizer Means (26) having an inlet valve (20) disposed on the mixing vessel (100) with a valve closure member (8), with the valve closure member (8) either closing the inlet valve (20) fully closed (closed position) or complete is open (open position) is adjustable, with the inlet valve (20) through which a powdered substance (P) is introduced into the liquid (F) with a inlet valve (20) associated with the control device (30), with which the valve closing member (8 ) in the closed or in the open position, characterized in that • the control device (30) recipe-dependent default data (D) and formulation-dependent control parameters (S) in the form de r the duration of the metering pulse (.DELTA.t1) and the time interval of adjacent metering pulses (.DELTA.t2) provides, • that the control device (30) has at least one designed as a measuring device Signalaufnehmer (16) having a time-dependent current consumption (I (t)) of the stirring device (24) and / or the shearing and homogenizing device (26) detected, and • that the control device (30) the closing or the open position of the valve closing member (8) in dependence on the time-dependent current consumption (I (t)) and in relation to the default data (D) and the control parameters (S) controls. Mixing device for performing the method according to Claim 2 with the characteristics of Claim 12 , characterized in that 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). Mixing device after Claim 12 or 13 , characterized in that the valve closing member (8) is formed at least in its powder-loaded area as a diameter-equal cylindrical rod, on the same diameter a valve plate (8a) is formed.

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