RU2621176C1 - Method of two-stage dosing and mixing of mixture components - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: when performing the two-stage dosing and mixing of the mixture components, which includes sequential dosing and mixing of the initial mixture components, preliminary dosing of the mixture components is performed at the first stage. After mixing, the homogeneity and composition of the resulting mixture are analyzed. Then, the amount of additives of the components is calculated to produce a mixture of the desired composition. At the second stage, precise dosing of the calculated amount of additives is performed to adjust the composition of the initial mixture, and the calculation is carried out according to the functional dependence.

EFFECT: possibility of obtaining high-quality mixtures of a given composition due to its adjustment and highly precise dosing of components.

7 tbl, 1 dwg

Description

The invention relates to a technology for the production of multicomponent mixtures and can be used in chemical, pharmaceutical, paint and varnish and other industries in the preparation and analysis of the degree of homogeneity of both the finished multicomponent composition and its semi-finished products.

A known method of dispensing a mixture, including forced mixing and weighing a control volume of the material, its comparison with a given value and the subsequent adjustment of the weight of the sample (Application No. 2008111428, publ. 09/27/2009).

The disadvantage of this method is the need to use only volumetric dispensers, which in some cases does not provide high precision metering of the mixture.

A known method for the continuous dosing of bulk materials, including the formation of individual portions of the dosed bulk material and the supply of these portions at certain intervals to a device for converting portions into a continuous stream (Patent No. 2366904, published on 09/10/2009).

The disadvantage of this method is the need for the formation of individual portions of the metered bulk material and the supply of these portions at certain intervals to the unit for converting the portions into a continuous stream, which increases the mixing time of materials, thereby reducing the accuracy of dosing-mixing due to strict reference to the time values through which supply of the collected portion of the dosed material.

The closest in technical essence to the claimed method is a two-stage dosing and mixing of feed components, including dosing of individual groups of components and their subsequent mixing, both stages of dosing-mixing are carried out sequentially on the same production line (Patent No. 2075300, publ. 20.03 .1997). This method is adopted as a prototype.

The disadvantage of this method, adopted as a prototype, is the inability to control the dosage of the components and to obtain mixtures of a given composition.

The technical result consists in the possibility of obtaining high-quality mixtures of a given composition due to its adjustment and high-precision dosing of components.

The technical result is obtained due to the fact that when implementing the method of two-stage dosing and mixing the components of the mixture, including sequential dosing and mixing the components of the initial mixture, according to the invention, at the first stage, preliminary dosing of the components of the mixture is carried out, after mixing, the homogeneity and composition of the resulting mixture are analyzed, then the calculation of the number of component additives to obtain a mixture of a given composition, and in the second stage carry out precision to zing the calculated amount of additives to correct the composition of the initial mixture.

In this case, the calculation is carried out according to the functional dependence:

under the constraints given in the form of equalities and / or inequalities of the form:

Δm _i ≥0

with normative condition

where m _{stage 1} is the mass of the mixture obtained in the first stage;

Δm _i - the addition of the i-th component to obtain a mixture of a given composition;

- масса i-го компонента в смеси, полученной на первой стадии;

- the mass of the i-th component in the mixture obtained in the first stage;

m _{stage 2} is the mass of the mixture obtained in the second stage;

- масса i-го компонента в смеси, полученной на второй стадии;

- the mass of the i-th component in the mixture obtained in the second stage;

ω ₁ , ω ₂ , ω ₃ , ..., ω _N - mass fraction of components in the mixture of a given composition;

N is the number of components.

At the first stage, preliminary dosing of the components of the mixture is carried out, i.e. rough dosing, carried out with high component costs. At the second stage, precision dosing is carried out using high-precision dispensers, which make it possible to bring the composition of the mixture to the desired one after mixing with the required accuracy. The composition and homogeneity of the mixtures obtained in the first and second stages are determined using an analyzer. The batching process is controlled according to the results of calculating the amount of additives obtained as a result of solving the linear programming problem, and the calculation is carried out according to the functional dependence:

The claimed order of operations allows to obtain the final product in the form of homogeneous mixtures of a given composition with high accuracy of their dosage.

The method is illustrated by the installation diagram shown in the figure.

A technological installation that implements the inventive method includes a mixer 1 with a mixer, pre-dispensers 2, high-precision dispensers 3, an analyzer 4 and a control unit 5. The control unit 5 is configured to analyze the incoming data from the analyzer 4 about the component composition of the mixture after preliminary mixing of the components, data processing using software and supplying control signals to high-precision dispensers 3.

The inventive method is as follows.

At the first stage, preliminary dosing of the components of the mixture is carried out using "coarse" dispensers 2. We use dispensers for each component of the mixture (D ₁ , D ₂ , ... D _i ), which due to their design features cannot maintain the high accuracy of dosing of the components required to obtain mixtures of the required composition, as they provide high component costs for preparing a larger volume of the mixture and do not have high accuracy.

After mixing the components using a mixer, an analysis of the homogeneity and composition of the mixture obtained is carried out using analyzer 4. Based on the analysis of the component composition of the mixture obtained in the first stage, the number of corrective additives of the components is calculated. The calculation is made according to the functional dependence:

under the constraints given in the form of equalities and / or inequalities of the form:

Δm _i ≥0

with normative condition

where m _{stage 1} is the mass of the mixture obtained in the first stage;

Δm _i - the addition of the i-th component to obtain a mixture of a given composition;

- масса i-го компонента в смеси, полученной на первой стадии;

- the mass of the i-th component in the mixture obtained in the first stage;

m _{stage 2} is the mass of the mixture obtained in the second stage;

- масса i-го компонента в смеси, полученной на второй стадии;

- the mass of the i-th component in the mixture obtained in the second stage;

ω ₁ , ω ₂ , ω ₃ , ..., ω _N - mass fraction of components in the mixture of a given composition;

N is the number of components.

The signal from the analyzer 4 is fed to the control unit 5 with a program code that calculates the number of component additions Δm _i to obtain a mixture of a given composition according to the above functional dependence.

At the second stage, precision dosing of the calculated amount of additives Δm _i takes place to correct the composition of the initial mixture.

Precision dosing is carried out using high-precision precision dispensers 3 for each of the components (D ' ₁ , D' ₂ , ... D ' _i ) by the signal received from the control unit 5.

Next, in the mixer 1, the components are mixed to a homogeneous state and a ready-made mixture of a given composition is obtained, which is controlled by analyzer 4.

Examples of specific implementation

Example 1

It was required to obtain unleaded gasoline of the A-92 brand, having the specified three-component composition, which is presented in table 1.

Laboratory equipment was used to prepare A-92 gasoline.

At the first stage, preliminary (rough) dosing with increased component costs is realized. The error of laboratory dispensers used in the first stage was 5%. Using a laboratory analyzer 4, data were obtained on the component composition of the mixture and its degree of homogeneity.

The calculation of the number of component additives necessary for correcting the composition of the mixture was carried out using a computer.

соответственно:Using the above functional dependence, the mass of the mixture m _{stage 1} and the masses of components 1, 2, 3 in the mixture were calculated

respectively:

m _stage 1 = 5000 kg;

Denoting additives (mass gain) of the components as:

Δm ₁ = x ₁ ;

Δm ₂ = x ₂ ;

Δm ₃ = x ₃ ,

made up the objective function and limitations.

The objective function was:

The restrictions were:

x _i ≥0,

For convenience, the solutions were converted to the form:

As a result, the following solution to the problem was obtained:

Those. additives of components had the following meanings:

Δm ₁ = 21.223 kg;

Δm ₂ = 0.2295 kg;

Δm ₃ = 0 kg.

,

и

объемные добавки компонентов составили:With the density of individual components

,

and

volumetric additives of the components amounted to:

Δν ₁ = 0.029 m ³ ;

Δν ₂ = 0.0003 m ³ ;

Δν ₃ = 0 m ³ .

where T ₁ , T ₂ , T ₃ are the temperatures of components 1, 2, 3, respectively.

In the second stage, laboratory high-precision small-sized precision dosing units with a low error of 0.1% were used. The use of such dispensers in the first stage was impossible, because they are not able to dose the large volumes required in the first stage.

Using the analyzer, data were obtained on the component composition of unleaded gasoline A-92 at the second stage of the dosing-mixing process, based on which the mass of the final mixture m _{stage 2} and the mass of the components in the mixture were calculated

m _{stage 2} = 5021.45 kg;

For a comparative analysis, the dosage obtained as a result of solving the linear programming problem of the number of components was carried out by dispensers similar to the dispensers used in the first stage. Thus, the dosing-mixing scheme was simulated by the prototype method, i.e. excluding precision dosing. Thus, data were obtained on the component composition of unleaded gasoline A-92:

m _{stage 2} = 5021.33 kg;

Based on the data obtained, the percentage of the mixture components was calculated. The calculation results are presented in table 2.

The result of the claimed method coincides with the required composition with an accuracy of hundredths of a percent.

Example 2

It was required to get acrylic paint. In the manufacture of acrylic paint used a solution of ethylene glycol having the composition shown in table 3.

In the process of preparing a solution of ethylene glycol, water and ethylene glycol were mixed in a ratio (for one of the compositions) 5: 1.

To prepare a solution of ethylene glycol, the claimed method and processing unit were used.

Preliminary dosing of liquid components was carried out using a float level gauge. The components are mixed using a periodic mixer with an anchor mixer in a container with a volume of V = 1 m ³ .

According to the technology for the preparation of paints and varnishes, an indirect indicator, on the basis of which it is possible to judge the component composition of the paint and varnish mixture, is density. Therefore, the FDM density transducer manufactured by Metran-Emerson was used as a composition analyzer. It carries out direct measurement of the density and concentration of liquids and has the limits of the main relative density error of ± 1.0 kg / m ³ .

The relationship of some values of the density of the solution and the concentration of ethylene glycol in it are presented in table 4.

The calculation of the number of component additives necessary for correcting the composition of the mixture was carried out using a computer.

Precise dosing of additives of components 1 and 2 was carried out using rotameters DK32 manufactured by KROHNE, having an accuracy class of 0.4.

соответственно, дозирование которых было осуществлено на первой стадии:After mixing the components of the mixture in the first stage, a sample was taken and an analysis of the density of the mixture was carried out. Based on the analysis, the mass of the mixture m _{stage 1} and the masses of components 1 and 2 in the mixture were calculated

accordingly, the dosing of which was carried out in the first stage:

m _stage 1 = 600 kg;

Denoting additives (mass gain) of the components as:

Δm ₁ = x ₁ ;

Δm ₂ = x ₂ ,

compiled the objective function and limitations.

The objective function has the form:

where x ₁ and x ₂ - the increment of the masses of the components of water and ethylene glycol, respectively.

The restrictions are of the form:

x _i ≥0,

For convenience, the solutions are converted to the form:

As a result, we obtained the following solution to the problem:

Those. additive components have the following meanings:

Δm ₁ = 10.78 kg;

Δm ₂ = 0 kg.

и ρ₂(T₂) объемные добавки компонентов составят:You can also get bulk additives components. With the density of individual components

and ρ ₂ (T ₂ ) volumetric additives of the components will be:

Δν ₁ = 0.01078 m ³ ;

Δν ₂ = 0 m ³ .

where T ₁ , T ₂ are the temperatures of components 1 and 2, respectively.

After calculating the required amount of additives at the second dosing-mixing stage, the component composition of the ethylene glycol solution was corrected.

соответственно, дозирование которых было осуществлено на второй стадии:Using a density analyzer, data were again obtained on the component composition of the solution, based on which the mass of the final mixture m _{stage 2} and the masses of components 1 and 2 in the mixture were calculated

accordingly, the dosing of which was carried out in the second stage:

m _{stage 2} = 610.78 kg;

For comparative analysis, the dosing of the number of components obtained as a result of solving the linear programming problem was carried out in a manner similar to the first stage. Thus, the dosing-mixing scheme was simulated, similar to the prototype, i.e. without taking into account the accuracy of the dispensers used in the first and second stages. Data were obtained on the component composition of the ethylene glycol solution:

m _{stage 2} = 617.9 kg;

Based on the data obtained, the percentage of the mixture components was calculated. The calculation results are presented in table 5.

From the data of table 5 it follows that in comparison with the prototype of the proposed method has significant advantages. The proposed dosing-mixing scheme made it possible to achieve the required component composition of the solution with an accuracy of tenths of a percent.

Example 3

The basis for the preparation of acrylic paint was a heterogeneous mixture of a solution of ethylene glycol and the third component - water-soluble hydroxyethyl cellulose.

The component composition of the basis of acrylic paint is presented in table 6.

For feeding water-soluble hydroxyethyl cellulose to the mixer, i.e. component in the solid phase, the processing unit was equipped with a screw dispenser of small additives DMD "Gamma", with an accuracy class of 0.2.

Based on the analysis of the composition of the mixture obtained in the first stage, the mass of the mixture and the components in it were:

m _stage 1 = 600 kg;

For the linear programming problem, we denote

Δm ₁ = x ₁ ;

Δm ₂ = x ₂ ;

Δm ₃ = x ₃ .

The objective function has the form:

where x ₁ , x ₂ and x ₃ - the increment of the masses of components 1, 2 and 3.

The restrictions are of the form:

x _i ≥0,

For convenience, the solutions are converted to the form:

The calculation of the number of component additives necessary for correcting the composition of the mixture was carried out using a computer.

As a result, we obtained the following solution to the problem:

Those. additive components have the following meanings:

Δm ₁ = 11.93 kg;

Δm ₂ = 0 kg;

Δm ₃ = 5.12 kg.

соответственно, дозирование которых было осуществлено на второй стадии:After adding the calculated amount of components and performing the mixing process using a density analyzer, data were obtained on the component composition of the solution, based on which the mass of the final mixture m _{stage 2} and the masses of components 1, 2 and 3 in the mixture were calculated

accordingly, the dosing of which was carried out in the second stage:

m _{stage 2} = 617.05 kg;

For a comparative analysis, the dosing of the number of components obtained as a result of the calculations was carried out in a manner similar to the first stage. Thus, the dosing-mixing scheme was simulated, similar to the prototype, i.e. without taking into account the accuracy of the dispensers used in the first and second stages.

Data were obtained on the component composition of the base of acrylic paint:

m _{stage 2} = 620.4 kg;

Based on the data obtained, the percentage of the mixture components was calculated. The calculation results are presented in table 7.

From the data of table 7 it follows that in comparison with the prototype of the proposed method allowed to achieve the required component composition of the basis of acrylic paint with an accuracy of hundredths of a percent.

An example illustrates the possibilities of the proposed dosing-mixing scheme to obtain a given component composition of acrylic paint with high accuracy.

Thus, the presented examples illustrate that the claimed method allows to obtain high-quality mixtures of a given composition with high accuracy.

Claims (16)

A method of two-stage dosing and mixing the components of the mixture, comprising sequential dosing and mixing the components of the initial mixture, characterized in that at the first stage, preliminary dosing of the components of the mixture is carried out, after mixing, an analysis of the homogeneity and composition of the mixture obtained is carried out, then the number of additives of the components is calculated to obtain a mixture of a given composition, and at the second stage, precision dosing of the calculated amount of additives is performed to correct the composition of the initial mixture, while lead according to the functional dependence:

under the constraints given in the form of equalities and / or inequalities of the form:

Δm _i ≥0 with normative condition

where m _{stage 1} is the mass of the mixture obtained in the first stage; Δm _i - the addition of the i-th component to obtain a mixture of a given composition;

- the mass of the i-th component in the mixture obtained in the first stage; m _{stage 2} is the mass of the mixture obtained in the second stage;

- the mass of the i-th component in the mixture obtained in the second stage; ω ₁ , ω ₂ , ω ₃ , ..., ω _N - mass fraction of components in the mixture of a given composition; N is the number of components.

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