WO2020212868A1 - Dispositif de dosage en continu de matières solides ou liquides et procédé de fonctionnement associé - Google Patents

Dispositif de dosage en continu de matières solides ou liquides et procédé de fonctionnement associé Download PDF

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Publication number
WO2020212868A1
WO2020212868A1 PCT/IB2020/053554 IB2020053554W WO2020212868A1 WO 2020212868 A1 WO2020212868 A1 WO 2020212868A1 IB 2020053554 W IB2020053554 W IB 2020053554W WO 2020212868 A1 WO2020212868 A1 WO 2020212868A1
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WO
WIPO (PCT)
Prior art keywords
hopper
dosing device
weighing system
weight
loader
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2020/053554
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English (en)
Inventor
Gabriele Caccia
Paolo Rizzotti
Enrico NAPPA
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SYNCRO Srl
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SYNCRO Srl
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Publication date
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Publication of WO2020212868A1 publication Critical patent/WO2020212868A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G11/00—Apparatus for weighing a continuous stream of material during flow; Conveyor belt weighers
    • G01G11/08—Apparatus for weighing a continuous stream of material during flow; Conveyor belt weighers having means for controlling the rate of feed or discharge
    • G01G11/086—Apparatus for weighing a continuous stream of material during flow; Conveyor belt weighers having means for controlling the rate of feed or discharge of the loss-in-weight feeding type
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G13/00—Weighing apparatus with automatic feed or discharge for weighing-out batches of material
    • G01G13/02—Means for automatically loading weigh pans or other receptacles, e.g. disposable containers, under control of the weighing mechanism
    • G01G13/022—Material feeding devices
    • G01G13/024—Material feeding devices by gravity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B7/00—Mixing; Kneading
    • B29B7/02—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type
    • B29B7/22—Component parts, details or accessories; Auxiliary operations
    • B29B7/24—Component parts, details or accessories; Auxiliary operations for feeding
    • B29B7/242—Component parts, details or accessories; Auxiliary operations for feeding in measured doses
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B7/00—Mixing; Kneading
    • B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
    • B29B7/58—Component parts, details or accessories; Auxiliary operations
    • B29B7/60—Component parts, details or accessories; Auxiliary operations for feeding, e.g. end guides for the incoming material

Definitions

  • the present invention concerns a continuous dosing device for solid or liquid materials, and in particular a dosing device that allows to control in a substantially continuous way the feeding of the material by a so-called "loss-in-weight" process.
  • this dosing device is particularly advantageous in the simultaneous dosing of multiple materials, its structure and method of operation can also be applied to the dosing of a single material to achieve greater dosing accuracy. Therefore, the use of the term“component” is also intended to cover the case where the dosed component is the only material contained in the single hopper of the dosing device.
  • each component is loaded into a hopper without a weighing device and the material is discharged from the hopper by gravity through the timed opening of a bottom gate, so that the material is loaded onto an underlying scale having a capacity defined in volume which determines the batch of dosing.
  • the sequential opening of the different hoppers allows to obtain the dosing batch with the recipe obtained as the sum of partial weighings of the different components, hence "gain- in- weight", until the batch is ready to be discharged into a mixer where the materials are mixed to feed homogeneously and continuously, for example, the screw of the extruder.
  • the main advantage of the batch feeder is the simplicity of the components used and therefore the reduced cost, while its main limitation is the slowness in achieving the accuracy of the dosing and its hourly flow rate.
  • the extruder flow rate is measured and adjusted in terms of the number of batches discharged over time, therefore the batch feeder opposes a great "inertia" to any error correction.
  • the quantity of each component is dosed by estimating the opening time of the gate, i.e. the fall time necessary for the component to escape from the hopper and reach the scale where it is weighed, therefore the measurement is approximate and strongly dependent on the granulometry and density of the material, which are parameters that influence the fall speed.
  • This type of dosing device therefore has the disadvantage of not allowing the formation of precise mixtures and of requiring long times for the preparation of each batch, due to the need to carry out a series of sequential weighings with the relative settlement transients of the scale between two successive weighings to allow the damping of the vibrations caused by the fall of the previous component.
  • each component is loaded into a hopper equipped with an independent weighing device (e.g. load cells), and by adjusting the transport system associated with the hopper outlet (e.g. motorized auger) it is possible to keep the feeding flow of each component making up the recipe constant over time in the due ratio with the other components.
  • an independent weighing device e.g. load cells
  • the transport system associated with the hopper outlet e.g. motorized auger
  • the weight of the material in the collection hopper can be measured constantly in order to detect level changes due, for example, to changes in extruder performance, or a discrepancy between the component feeder and the extruder performance.
  • the feeders are individually controlled to maintain the pre-set dosing ratios of the various components of the recipe, and globally to maintain a constant level in the collection hopper and consequently the correct extruder flow rate.
  • a critical aspect of the continuous dosing device is represented by the charging phase of the weighed hopper of the component because in this phase the degrees of freedom of the system increase, since to the outgoing flow through the auger calculated up to now is added the incoming flow from the loader, and the variables of the problem increase to two while the data acquisition signal coming from the hopper load cells continues to remain one.
  • the problem therefore remains undetermined and the dosing device works temporarily without an effective weight loss control but simply assuming a constant auger feeding value, since there is no way to predict and compensate what happens during the loading phase.
  • the first hopper continuously feeds the second hopper and the control unit can control the weight loss of the latter as it receives information both of the incoming and outgoing flow into it.
  • the system operates during the refilling phase as a normal continuous dosing device with a single hopper per component by detecting the weight of the second hopper feeding the collection hopper.
  • FR 2572520 describes a continuous dosing device of this type in which the second hopper is hanging from the first hopper, so that a first weighing system connected to the first hopper detects the total weight loss of the two connected hoppers while a second weighing system connected to the second hopper detects only the weight loss of the latter.
  • the connection between the two hoppers is interrupted and the auger control only proceeds with the second hopper according to its weighing system signal while the first hopper is refilled. After that, when the connection between the two hoppers is restored, the auger control is again based on the first weighing system.
  • the two weighing systems are not independent and the quantity of material loaded into the first hopper cannot be measured separately but only by difference between the total weight and the weight detected by the second weighing system, so that any errors or malfunctions of one of the weighing systems are not easily detected and affect the continuous operation of the entire dosing device. Furthermore, since the two hoppers are continuously connected until the first hopper empties and the latter is as large as the second hopper, there is a considerable difference in the weight of the material in the two hoppers as a whole between when the first hopper is full and when it is almost empty.
  • DE 3742229 describes a continuous dosing device with a similar structure in which, however, it is the second hopper that supports the first hopper, so that a first weighing system connected to the first hopper only detects the weight loss of the first hopper while a second weighing system connected to the second hopper detects the total weight loss of the two hoppers.
  • the two hoppers are not constantly connected, since the first hopper is opened only when it is necessary to recharge the second hopper, and the auger control is always performed according to the signal of the second "total" weighing system.
  • this "total" signal is compensated by subtracting from it the signal of the first weighing system, which is then reset to zero when said refilling of the first hopper is completed.
  • the signal of the second weighing system again corresponds to the weight of the material contained in both hoppers, even before the second hopper is refilled from the first hopper and regardless of when the refilling takes place.
  • this dosing device therefore, has the same drawbacks due to the fact that the two weighing systems are not independent, and both of the above mentioned dosing devices do not solve the problem of the settlement transients of the weighing system at each refilling of the first or second hopper, creating anyway an uncertainty in the system.
  • the signal of the first weighing system that detects the weight of both hoppers is disturbed by the transient due to the fall of the material when the two hoppers are reconnected to refill the second hopper, while the signal of the first weighing system that detects only the weight of the first hopper, as in DE 3742229, being subtracted from the signal of the second weighing system disturbs it by transmitting thereto its transient during the refilling of the first hopper.
  • WO 99/63310 describes a continuous dosing device of this type in which the auger feed hopper alternately receives material from a first of two filling hoppers which is continuously connected to it until it is almost empty.
  • the continuous dosing method proposed in this document is based on the sum of the weight loss signals of the feed hopper and the filling hopper connected thereto so that the feed hopper is always full and there is continuity of material flow between the two connected hoppers.
  • the object of the present invention is therefore to provide a continuous dosing device that is free from the above-described drawbacks.
  • This object is achieved by means of a continuous dosing device in which each weighed hopper of a component is not reloaded directly by the relative loader but indirectly through an intermediate weighed hopper, which is arranged between the component hopper and the loader so as to receive from the latter the material to be reloaded and discharge it into the component hopper through its own bottom gate only after weighing it with its own weighing system independent of the weighing system of the component hopper.
  • the main advantage of this dosing device is therefore that, thanks to the presence of the intermediate weighing hopper equipped with an independent weighing system, the period of absence of weight control is practically eliminated or at least considerably reduced during the refilling phase because the amount of material that is discharged into the component hopper is known having already been weighed in the intermediate hopper, so that the above-mentioned problem of the non-determination of the two- variable equations is solved.
  • the weighed quantity contained in the intermediate hopper when discharged, will be added to the quantity of material in the component hopper allowing to keep active the evaluation of weight loss even during the settlement transient.
  • a second advantage of this dosing device is that it allows more frequent component hopper refilling cycles, since the problem of the settlement transient is overcome by the upstream weighing in the intermediate hopper, with reduced quantities of material and very short times resulting in very short uncertainty periods and a considerable increase in the accuracy of the control of the whole system.
  • the variation in the level of material in the component hopper is reduced, making the feeding and flow conditions of the conveyor screw more stable, since the material density and the head at the hopper outlet undergo less variations.
  • a third advantage of the above mentioned dosing device is that since the amount of material discharged from the intermediate hopper has been weighed beforehand and is therefore known, any small transient variations can be compensated for immediately.
  • Another advantage of the dosing device in question is the verification of consistency between the hourly flow rates measured independently by the two weighing systems of the intermediate hopper and the component hopper, which introduces an innovative self-diagnosis function since the two systems measure the same flow over time and must indicate the same hourly flow rate.
  • data misalignment it is possible to report the anomaly, identify the load cell or the element subject to deviation and in some cases proceed, with the consent of authorized personnel, to compensate the error.
  • Another advantage of this dosing device is that it can be easily realized with the addition of small, simple and cheap devices. In this way, its cost and overall dimensions compared to a prior art continuous dosing device are only slightly higher, while they are considerably lower than the above-mentioned solution with the doubling of the continuous feeding hoppers. Further advantages and characteristics of the dosing device according to the present invention will be evident to those skilled in the art from the following detailed and not limiting description of an embodiment thereof with reference to the annexed drawings in which:
  • Fig.l is a frontal schematic view of a dosing device according to the present invention when loading the material into the intermediate hopper;
  • Fig.2 is a frontal schematic view of a pair of dosing devices like the one in Fig.l applied to a continuous extrusion plant of a two -component material;
  • Figs.3 and 4 are diagrams showing the trend over time of the quantity of material present in the component hopper and of the specific flow rate of the relevant feeding screw, respectively for a traditional dosing device and for a dosing device according to the invention.
  • a continuous dosing device traditionally includes a hopper 1 that feeds a component of the material to be extruded to an underlying collection hopper 2 through a feeding screw 3 that flows into a cascade mixer 8.
  • a hopper 1 that feeds a component of the material to be extruded to an underlying collection hopper 2 through a feeding screw 3 that flows into a cascade mixer 8.
  • a control unit (not shown) which also controls screws 3 to ensure the accuracy of the mixture to be extruded.
  • hoppers 1 could be more and collection hopper 2 could be without weighing systems.
  • a loader 5 is located above hopper 1 to load therein a given quantity of material when the quantity contained in hopper 1 falls below a set threshold, according to the commands received from the control unit.
  • loader 5 shown in Fig.l is a simple hopper equipped with a bottom gate that dispenses the material by gravity
  • other types of loaders could be used in the same way (e.g. pneumatic, auger, vibrating channel, etc.).
  • Hopper 1 does not receive the material directly from loader 5 because an intermediate hopper 6 is located between hopper 1 and the overlying loader 5, in order to receive the material from loader 5 and discharge it by gravity into hopper 1 by opening its own bottom gate according to the commands received from the control unit.
  • the innovative aspect of the dosing device according to the present invention lies in the fact, as mentioned above, that the intermediate hopper 6 is an independently weighed hopper whose weight is constantly detected by a relative weighing system, for example load cells 7, operationally connected to the control unit. In this way, the weight of the quantity of material contained in the intermediate hopper 6 can be added to the weight of the material contained in hopper 1 below when reloading the latter.
  • the two dosing devices according to the invention feed the collection hopper 2 through the cascade mixer 8, they could also be used to directly feed an extruder or other type of machine or to fill containers for the preparation of batches of multi-component material to be used on other machines.
  • the diagram in Fig.3 shows the weight of the material in hopper 1 of a traditional continuous dosing device with a capacity of 425 kg/h and a replenishment quantity of 30 kg (from a minimum of 8 kg to a maximum of 38 kg), which results in a replenishment interval of about 254 seconds and a replenishment time of about 5 seconds.
  • the diagram in Fig.4 shows the weight of the material in hopper 1 of a continuous dosing device according to the invention with a capacity of 405 kg/h and a replenishment quantity of 5 kg (from a minimum of 5.9 kg to a maximum of 10.9 kg), which results into a replenishment interval of about 44 seconds and a replenishment time of less than 1.5 seconds.
  • the feeding screw operates at a speed of 77.8 rotations per minute (rpm) and the line indicating the value of the specific screw capacity displays considerable undulations, with an average value of 5.463 kg/h per rpm and a maximum semi-dispersion of 1.116 kg/h per rpm, which corresponds to 20.43%.
  • said line is very little wavy, with an average value of 5.344 kg/h per rpm and a maximum semi-dispersion of 0.168 kg/h per rpm, which corresponds to 3.14%.
  • the capacity of the intermediate hopper 6 is not more than 50% of the capacity of the material hopper 1, more preferably not more than 30%, so as to maintain a high frequency of refilling with small quantities of material that minimize the variations in the feeding conditions of auger 3.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Weight Measurement For Supplying Or Discharging Of Specified Amounts Of Material (AREA)
  • Filling Or Emptying Of Bunkers, Hoppers, And Tanks (AREA)

Abstract

L'invention concerne un dispositif de dosage en continu comprenant une trémie (1) équipée d'un premier système de pesée (4) et configurée pour distribuer un matériau par l'intermédiaire d'un dispositif d'alimentation en continu (3) et pour recevoir ledit matériau à partir d'un appareil de chargement (5), une trémie intermédiaire (6) étant disposée entre la trémie (1) et l'appareil de chargement (5) pour recevoir le matériau de l'appareil de chargement (5) et le charger dans la trémie de matériau (1), la trémie intermédiaire (6) étant équipée d'un second système de pesée (7) indépendant du premier système de pesée (4).
PCT/IB2020/053554 2019-04-15 2020-04-15 Dispositif de dosage en continu de matières solides ou liquides et procédé de fonctionnement associé Ceased WO2020212868A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT102019000005790A IT201900005790A1 (it) 2019-04-15 2019-04-15 Dosatore continuo per materiali solidi o liquidi e relativo metodo di funzionamento
IT102019000005790 2019-04-15

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WO2020212868A1 true WO2020212868A1 (fr) 2020-10-22

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IT (1) IT201900005790A1 (fr)
WO (1) WO2020212868A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113819983A (zh) * 2021-10-21 2021-12-21 安徽天膜科技有限公司 一种水溶肥防结块剂用精度可调的添加装置
US12402554B2 (en) 2019-07-29 2025-09-02 KSi Conveyor, Inc. Methods for maintaining a metered flow rate of fluid treated seed
US12434917B2 (en) 2021-10-13 2025-10-07 KSi Conveyor, Inc. Continuously flowing seed metering and discharge system
US12433188B2 (en) 2023-01-16 2025-10-07 KSi Conveyor, Inc. Seed metering and discharge system with adjustable gate control

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2572520A1 (fr) * 1984-10-31 1986-05-02 Cellier Sa Installation de dosage en continu par pesage par perte de poids d'un produit en vrac
DE3742229A1 (de) * 1987-12-12 1989-06-22 Pfister Gmbh Dosiergefaesswaage
WO1999063310A1 (fr) * 1998-05-29 1999-12-09 Raute Precision Oy Regulation d'un dispositif d'alimentation par mesure de perte de poids

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2572520A1 (fr) * 1984-10-31 1986-05-02 Cellier Sa Installation de dosage en continu par pesage par perte de poids d'un produit en vrac
DE3742229A1 (de) * 1987-12-12 1989-06-22 Pfister Gmbh Dosiergefaesswaage
WO1999063310A1 (fr) * 1998-05-29 1999-12-09 Raute Precision Oy Regulation d'un dispositif d'alimentation par mesure de perte de poids

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US12402554B2 (en) 2019-07-29 2025-09-02 KSi Conveyor, Inc. Methods for maintaining a metered flow rate of fluid treated seed
US12402555B2 (en) 2019-07-29 2025-09-02 KSi Conveyor, Inc. Incline belt conveyor with longitudinal belt guards and methods of preventing seed entering between the belt and a curvilinear structure
US12434917B2 (en) 2021-10-13 2025-10-07 KSi Conveyor, Inc. Continuously flowing seed metering and discharge system
CN113819983A (zh) * 2021-10-21 2021-12-21 安徽天膜科技有限公司 一种水溶肥防结块剂用精度可调的添加装置
CN113819983B (zh) * 2021-10-21 2023-12-22 安徽天膜科技有限公司 一种水溶肥防结块剂用精度可调的添加装置
US12433188B2 (en) 2023-01-16 2025-10-07 KSi Conveyor, Inc. Seed metering and discharge system with adjustable gate control

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