ES2358712B1 - AUTOMATIC SYSTEM OF REGULATION OF DENSITY AND VISCOSITY IN PRODUCTS OBTAINED BY CONTINUOUS GRINDING. - Google Patents

Abstract

Automatic density and viscosity regulation system in products obtained by continuous grinding. # Consists of continuously measuring the humidity of the mixture of solid raw materials entering the continuous mill, with which the amount of input water can be calculated necessary. If materials are provided in suspension, it is necessary to measure the solids content of that suspension. This is expected to maintain both the viscosity of the final slip at stable values. # Density and viscosity in the slip resulting from grinding will also be measured, using a continuous, not in-line system, that is, carrying out a Sampling of the slip to maintain a continuous measurement.

Description

Automatic system for regulating density and viscosity in products obtained by continuous grinding.

Object of the invention

The present invention, as expressed in the description of this specification, refers to an automatic system for regulating density and viscosity in products obtained by continuous grinding, being especially applicable in the field of the ceramic sector but also in any sector where wet milling is used continuously.

The proposed solution has an immediate application in continuous grinding due to the improvement of the quality and control of the process it provides. This will allow the elimination of rework to correct the characteristics of the slip once in the rafts, as long as the deviation allows, such as a high density that can be corrected by adding water. On the other hand, there may be deviations that are difficult to correct, as would be the case opposite to the previous one in which the density was below the setpoint, in which case the only way to recover it is by adding it to barbotine rafts that have a higher density than of work.

It can also be used to atomize that slip that is outside the working parameters, but of course in that case the next step of the process that is the atomization will be affected, affecting both in terms of productivity and quality, a low slip density leads to less tons / hour of atomizer production, and in terms of quality, for example, the particle size of the spray that is produced will not be within the correct parameters.

Background of the invention

Currently, there is no known system in operation that automatically performs this regulation of density and viscosity, not even the continuous measurement of the variables. Currently, the measurements of the slip resulting from grinding are carried out periodically by the operator and manually, which means that there will be differences in the results obtained by the different operators.

With the result obtained by the operator, the decision must be made to change the regulation in the event that the characteristics of the slip resulting from the grinding have changed, or, on the contrary, wait a certain time to repeat the measurements and to confirm that there really is a change in the characteristics of the slip to correct then. All this taking into account that the conditions at the entrance of the mill that produced that result, were those of about two hours before and that may have varied with respect to those of this moment. This is complicated when there is more than one contribution to the mill, as is the case of contribution of suspended materials, due to the difficulty involved in knowing which of the contributions has varied its conditions.

In any case, we know in what situation it is at that moment, but what we do not know is since when the conditions have changed, or what is the same, when the change occurred. Depending on the moment in which the change occurred, the amount of slip produced outside the control parameters will vary, which will have a greater or lesser influence on the process, also depending on the intermediate storage of slip that we have in order to homogenize. In addition, not knowing the exact moment in which the change occurred is difficult to find out the causes that caused it.

Description of the invention

In general, the automatic system for regulating density and viscosity in products obtained by continuous grinding, object of the present invention, is a solution based on the continuous measurement of the humidity of the mixture of solid raw materials entering the continuous mill, which could regulate the amount of water needed, for which the water must also be measured. In the event that suspended materials such as recycling sludge or some raw material are provided, it will be necessary to measure the solids content of that suspension, as it is another source of possible variations in the amount of water provided to the windmill. In this way it is expected to maintain both the density and the viscosity of the final slip at stable values.

Subsequently, the density and viscosity in the slip resulting from grinding will be measured, by means of a non-in-line system, that is, a device that allows a sampling of the slip to be carried out to maintain a continuous measurement, but minimizing the wear that it causes the abrasive action of the slip and facilitating the controlled cleaning of the sensors.

To carry out these measurements, the technologies to be used are:

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Microwave technology will be used to measure the humidity of the raw materials, as it is independent of the color, density and particle size of the mixture to be measured.

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An electromagnetic flowmeter will be used to measure the water flow.

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Density measurement technology uses the oscillation period of a mechanical oscillator through which the slip slip sample is used. The period of oscillation depends on the density of the sample within the mechanical oscillator and the mechanical properties of the oscillator.

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For the viscosity a vibrating sensor is used that provides a signal proportional to the viscosity.

With these measurements, the expected results are as follows:

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Measurement of the humidity of raw materials with an accuracy of 0.1%.

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Density measurement with an accuracy of 0.01 g / cm3.

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Measurement of static viscosity comparable to the measurement in Ford Cup No. 4.

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Stabilization of the setpoint density ± 0.01 g / cm3.

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Stabilization of the setpoint viscosity in Ford Cup No. 4 ± 2 seconds.

To facilitate the understanding of the features of the invention and as an integral part of this specification, a sheet of drawings is attached in whose unique figure, for illustrative and non-limiting purposes, the following has been represented:

Brief description of the fi gures

Figure 1.- It is a scheme of the installation to carry out the automatic density and viscosity regulation system in products obtained by continuous grinding, according to the invention.

Description of the preferred embodiment

Referring to the numbering adopted in the figure, we can see how the automatic system for regulating density and viscosity in products obtained by continuous grinding, which the invention proposes, employs the following components:

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Measuring equipment: -Sensor (1) to measure the humidity of the raw material mixture. - Electromagnetic flowmeter (2) for measuring the supply water flow. -Densimeter (3) for measuring the density of the slip and the contribution in suspension if

there would be. -Viscometer (4) for measuring the viscosity of the slip.

•

Process control, management and information storage equipment: -Programmable automaton (5) with different functions:

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Capture of moisture data.

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Control loop for regulation.

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Slip sampling management.

• Controlled cleaning system management. -Industrial computer (6).

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Slipper sampling and circulation equipment: -Peristaltic pump head (7) with adapted motorization. -Clean and sensor cleaning system.

• Sleeve valves (8) to avoid embossing and wear, ball valves with automatic actuation can also be installed.

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Pneumatic solenoid valves (9) for actuating the valves (8).

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Flowmeter (10) for cleaning water control.

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Pressure regulator (11) of the cleaning water.

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Small electrical equipment necessary for the operation of the above elements.

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All of the above mounted on a PVC or stainless steel circuit inside a cabinet with wheels, so that the prototype can be autonomous and transportable.

The first objective is to maintain the density and viscosity at stable values, for which it will be necessary to regulate at the time of the entry of raw materials to the continuous mill. This is important, because the residence time of the slip inside the mill is very high. So, if it were regulated based on the reading of the density of the slip, there is a risk that the conditions of the raw materials that caused that density that we found at the exit are not the same conditions that are entering this moment to the continuous mill. This displacement in time can cause an even greater destabilization than may exist through the normal supply of raw materials, water and flocculant.

In order to achieve this stability, the sensors available in the market have been adapted to achieve a sufficiently accurate measurement of the amount of water of both solid and unleashed raw materials at the entrance to the continuous mill.

In addition, at the entrance of the continuous mill we also have other very important data, such as the weight or flow of raw materials contributed to the mill. This data is obtained by means of a dosing belt (12) that has weighing cells, in the case of raw materials supplied in solid, and a mass flow meter for the discarded ones.

At this point we will have the necessary information to calculate the amount of water that needs to be provided. We will regulate the water through the system available in the mill installation (automated regulating valve, peristaltic pump, ...), and we will measure it by means of a flowmeter that provides us with the necessary precision. With this regulation of the water supply, it is expected to maintain the stable density, since the proportion of the different raw materials is assumed to be constant and the fluctuations that may occur in the flow of raw materials entering the mill can also be compensated with the regulation of the water flow, having them controlled by the extractor / dosing belt (12). The scheme also indicated the entry of water for cleaning

(13) and the air inlet and outlet (14).

Regarding viscosity, if we review the factors that can modify it, we find, basically:

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The properties and percentage of the components in the formula.

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The properties and quantity of the fl oculant that is dosed at the entrance of the mill.

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The amount of water provided by raw materials.

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The quantity and quality of the water that is added for grinding.

Of all these in fl uences some are measured and therefore should be kept constant such as the composition of the formula, the quality of the water supply and of the fl oculant, the constancy of the properties of the raw materials. Therefore, what we know can vary is the amount of water provided by raw materials and also not measured at present. That is, if we correctly regulate the water supply we will also keep the viscosity stable.

In spite of everything previously considered, it will be necessary to carry out a measurement of the density and viscosity after grinding, for which the sensors available in the market have been adapted to achieve a sufficiently accurate measurement. This will imply quality control of the process, but that control will also be necessary so that these stable density and viscosity values approximate the setpoint values that the process must respect.

It is very much to suppose that all the variables that we have assumed constant really are over time, such as the precision of the fl oculant contribution or even its behavior with respect to plastic raw materials, there is also the possibility of a deviation in the moisture reading of raw materials, including the load cell of the weighing tape.

Through this system the density and viscosity deviations are detected, when these deviations are recorded in the readings and also the changes in the regulations, the operator can look for the problem that causes the deviation, since, the system corrects the effect of those problems about density or viscosity but it doesn't correct the problem itself. While it is ascertained which of the working conditions has deviated, we will be sure that the density and viscosity will be within the control parameters, since there are several possibilities, the solution to the problem may not be immediate. Of course, when the deviation is resolved, the system should be able to detect the new change and redirect the process, usually with a correction in the opposite direction to the previous one.

Claims (10)

1. Automatic system for regulating density and viscosity in products obtained by continuous grinding, especially applicable to the technical sector of the ceramic industry and in general in any field where wet milling is used continuously, in which it is interesting to know these density and viscosity, and there is a continuous mill with at least one input of raw materials and supply water and at least one output of product obtained after milling called slip; characterized in that it comprises:

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means for continuously measuring humidity (1) of the mixture of solid raw materials entering the continuous mill;

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means for measuring the amount of water (2) of necessary input;

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density and viscosity measuring means (3, 4) of the resulting slip at the exit of said mill;

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a process control, management and information storage team (5, 6);

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a sampling and circulation equipment of the slip (7 to 11, 13, 14);

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a unit for measuring weight and flow of raw materials provided (12) to the mill.

2.

Automatic system for regulating density and viscosity in products obtained by continuous grinding, according to claim 1, characterized in that, in addition to said means and equipment, it comprises means for measuring solids content in the raw materials for entering the mill for cases in which suspended materials are provided in these raw materials entering the mill.

3.

Automatic density and viscosity regulation system in products obtained by continuous grinding, according to claim 1 or 2, characterized in that said measuring means and equipment are mounted in a PVC or stainless steel circuit inside a cabinet provided with wheels that facilitates autonomy and portability in the system.

Four.

Automatic system for regulating density and viscosity in products obtained by continuous grinding, according to any one of the preceding claims, characterized in that the means of continuous moisture measurement of the mixture of solid raw materials entering the continuous mill consist of a humidity sensor

(1) that employs microwave technology that facilitates measurements irrespective of the color, density and granulometry of the mixture.

5.

Automatic system for regulating density and viscosity in products obtained by continuous grinding, according to any one of the preceding claims, characterized in that the means for measuring the amount of input water consist of an electro-magnetic flowmeter (2).

6.

Automatic system for regulating density and viscosity in products obtained by continuous grinding, according to any one of the preceding claims, characterized in that the density and viscosity measuring means of the slipper consist of a densimeter (3) that uses measurement technology of the oscillation period of a mechanical oscillator, and in a viscometer (4) that uses a vibrating sensor that produces a signal proportional to the viscosity.

7.

Automatic system for regulating density and viscosity in products obtained by continuous grinding, according to any one of the preceding claims, characterized in that the control equipment for the management and information storage process comprises an industrial computer (6) and an automaton programmable (5) which include humidity data capture functions, control loop for regulation, slip management, and management of a controlled cleaning system.

8.

Automatic density and viscosity regulation system in products obtained by continuous grinding, according to any one of the preceding claims, characterized in that the sampling and circulation equipment of the slip has a peristaltic pump head (7) with adapted motorization and a sensor and circuit cleaning system that includes:

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sleeve valves (8) to avoid embossing and wear, or ball valves with automatic actuation;

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pneumatic solenoid valves (9) for actuating said valves with air inlet and outlet (14);

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control flow meter (10) for cleaning water;

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pressure regulator (11) for cleaning water with inlet for cleaning water (13).

9. Automatic system for regulating density and viscosity in products obtained by continuous grinding, according to any one of the preceding claims, characterized in that the equipment for measuring weight and flow of raw materials provided to the mill includes a dosing belt (12) which has weighing cells for materials supplied in solid and mass flow meter for materials that are dislodged. SPANISH OFFICE OF THE PATENTS AND BRAND Application no .: 200803667 SPAIN Date of submission of the application: 23.12.2008 Priority Date: REPORT ON THE STATE OF THE TECHNIQUE 51 Int. Cl.: See Additional Sheet RELEVANT DOCUMENTS

Category

Documents cited Claims Affected

X E A

GB 2390154 A (MILLENNIUM VENTURE HOLDINGS LT) 31.12.2003, pages 2-67; Figures 1-7. EN 2343500 A1 (EUROELETTRA S L) 02.08.2010, page 3, lines 38-47; page 4, lines 28-66. JP 5017270 A (INAX CORP) 26.01.1993, Summary of the EPODOC database. Recovered from EPOQUE. 1-9 1-3,7,8 1,3-5,9

Category of the documents cited X: of particular relevance Y: of particular relevance combined with other / s of the same category A: reflects the state of the art O: refers to unwritten disclosure P: published between the priority date and the date of priority submission of the application E: previous document, but published after the date of submission of the application

This report has been prepared • for all claims • for claims no:

Date of realization of the report 27.04.2011

Examiner B. Weaver Miralles Page 1/4

REPORT OF THE STATE OF THE TECHNIQUE Application number: 200803667 CLASSIFICATION OBJECT OF THE APPLICATION G01N9 / 36 (2006.01) G01N11 / 00 (2006.01) B28B11 / 04 (2006.01) Minimum documentation sought (classification system followed by classification symbols) G01N, B28B Electronic databases consulted during the search (name of the database and, if possible, terms of search used) INVENES, EPODOC, WPI, INTERNET State of the Art Report Page 2/4  WRITTEN OPINION Application number: 200803667 Date of Completion of Written Opinion: 04.27.2011 Statement

Novelty (Art. 6.1 LP 11/1986)

Claims Claims 1-9 IF NOT

Inventive activity (Art. 8.1 LP11 / 1986)

Claims Claims 1-9 IF NOT

The application is considered to comply with the industrial application requirement. This requirement was evaluated during the formal and technical examination phase of the application (Article 31.2 Law 11/1986).  Opinion Base.- This opinion has been made on the basis of the patent application as published. State of the Art Report Page 3/4  WRITTEN OPINION Application number: 200803667 1. Documents considered.- The documents belonging to the state of the art taken into consideration for the realization of this opinion are listed below.

Document

Publication or Identification Number publication date

D01

GB 2390154 A (MILLENNIUM VENTURE HOLDINGS LT) 12.31.2003

2. Statement motivated according to articles 29.6 and 29.7 of the Regulations for the execution of Law 11/1986, of March 20, on Patents on novelty and inventive activity; quotes and explanations in support of this statement Claim 1: Document D01 is considered as the closest state of the art. This document discloses an automatic measurement system of different variables in a phased process, such as in products obtained by continuous grinding. Said system comprises means of continuous measurement of humidity, means of measurement of the amount of water, means of measurement of density and viscosity, control equipment, sampling and circulation equipment of the slipper, equipment for measuring the weight and flow of materials premiums provided (page 11, line 19 - page 12, line 11; page 12, lines 30-32; page 13, line 1-31; page 23, line 4). Therefore, claim 1 is novel in accordance with article 6 of patent law 11/1986. Dependent claims 2-9: Claim 2 refers to means for measuring solids content in raw materials entering the mill when suspended materials are provided. Document D01 has in its system such means consisting of a dosing belt, weight measuring equipment, a mass flow meter (22; 249; page 36, table 2; figure7; page 4, line 8-9, page 12, line 30). Therefore, said claim is not new according to article 6 of patent law 11/1986. Claim 3 refers to the materials used and the place where the system is located. These are mere design options that an expert in the field would choose as suitable for the purposes of their use. Therefore, said claim lacks inventive activity according to article 8.1 of patent law 11/1986. Claims 4, 5, and 6 refer to the type of sensor incorporated. A person skilled in the art would select the claimed sensors taking into account the precision that is to be achieved in the measurements since said sensors are on the market. Document D01 discloses different types of sensors for measuring the variables it performs, in particular for humidity (page 37, line 5) such as a microwave sensor and density (page 36, table 2;). Therefore, claim 4 is novel, according to article 6 of patent law 11/1986; and claims 5 and 6 do not possess inventive activity according to article 8.1 of patent law 11/1986. Claim 7 refers to a computer and an automaton for capturing and managing different data, as disclosed in document D01 (page 11, line 19-page 12, line 11). Therefore, said claim is not new according to article 6 of patent law 11/1986. Claim 8 discloses other elements such as a peristaltic pump, sleeve valves, solenoid valves, water control flowmeter, pressure regulator. These are elements included in the system disclosed in document D01, so said claim is not new according to article 6 of patent law 11/1986. Claim 9 describes the inclusion of a dosing belt, weighing cells and a mass flowmeter. Document D01 has such elements (22; 249; page 36, table 2; figure 7; page 4, line 8-9). Therefore, said claim is not new according to article 6 of patent law 11/1986. State of the Art Report Page 4/4