PT101314B

PT101314B - dosing process, in pseudo-continuous, and homogeneously mixing PULVERIFORM OR GRANULATED solids and apparatus for dosing, by weighing, and homogenous mixing of solid, solid

Info

Publication number: PT101314B
Application number: PT10131493A
Authority: PT
Original assignee: Ibe Ind De Bens E Equipamento
Priority date: 1993-07-20
Filing date: 1993-07-20
Publication date: 2000-04-28
Also published as: PT101314A

Description

DESCRIÇÃODESCRIPTION

Título: Processo de dosear, em pseudo-contínuo, e de misturar, de modo homogéneo, sólidos pui veriformes ou granulados e aparelho para dosear, por pesagem, e misturar, de modo homogéneo, tais sólidos.Title: Process of dosing, in pseudo-continuous, and mixing, in a homogeneous way, pui veriform or granular solids and apparatus for dosing, by weighing, and mixing, homogeneously, such solids.

O presente invento respeita tanto a um processo de dosear e misturar homogeneamente corpos sólidos, como a um aparelho que doseia e mistura tais sólidos segundo esse processo.The present invention relates both to a process of dosing and mixing homogeneously solid bodies, and to an apparatus that doses and mixes such solids according to that process.

Os aparelhos tradicionais de doseamento podem trabalhar segundo um de dois grandes princípios fundamentais, que são o do doseamento volumétrico e o do doseamento com base no peso do produto a dosear, vulgarmente conhecido por doseamento gravimétrico.Traditional dosing apparatus can work according to one of two main fundamental principles, namely volumetric dosing and dosing based on the weight of the product to be dosed, commonly known as gravimetric dosing.

Em qualquer dos referidos princípios, o doseamento é feito através da regulação do fluxo do material a dosear, só que, enquanto que no primeiro deles a regulação é feita de modo a medir o volume do material processado por unidade de tempo, já no segundo, ela é feita de modo a medir o peso de tal material, também por unidade de tempo.In any of the aforementioned principles, the dosing is done by regulating the flow of the material to be dosed, only that, while in the first one the regulation is done in order to measure the volume of the material processed per unit of time, in the second, it is made in order to measure the weight of such material, also per unit of time.

A implementação do princípio do doseamento volumétrico recorre, tradicionalmente, a extractores constituídos por um fuso roscado, ou por um par de fusos roscados, sendo o controlo do caudal volúmico feito em aberto - isto é, sem que o sistema tenha informação de retorno (feeed-back) - e sendo a velocidade do extractor calculada a partir da calibragem prévia do doseador.The implementation of the principle of volumetric dosing has traditionally resorted to extractors consisting of a threaded spindle, or a pair of threaded spindles, with the volume flow control being made open - that is, without the system having feedback information (feeed) -back) - and the speed of the extractor is calculated from the previous calibration of the doser.

Quanto à implementação do princípio do doseamento gravimétrico, ela é feita através de dois sistemas, um dos quais é vulgarmente designado por doseamento por perda de peso e caracteriza-se por ser indirecto - visto determinar o peso do material já escoado a partir de um recipiente com base na diferença entre o peso do material ainda não vazado desse recipiente e o peso do material inicialmente aí contido - caracterizando-se o outro por ser directo, uma vez que recorre à pesagem instantânea do material vazado a partir do dito recipiente.As for the implementation of the principle of gravimetric dosing, it is done through two systems, one of which is commonly referred to as weight loss dosing and is characterized by being indirect - as it determines the weight of the material already drained from a container based on the difference between the weight of the material not yet poured from that container and the weight of the material initially contained therein - the other being characterized by being direct, since it uses instantaneous weighing of the material poured from said container.

No primeiro daqueles sistemas o extractor existente à saída dú referido recipiente é tradicionalmente constituído por fusos do mesmo tipo dos atrás citados.In the first of those systems, the extractor existing at the outlet of said container is traditionally made up of spindles of the same type as those mentioned above.

Já no segundo sistema, o extractor é normalmente um tapete rolante formado por uma correia flexível.In the second system, the extractor is normally a conveyor belt formed by a flexible belt.

Independentemente do sistema utilizado no princípioRegardless of the system used at the beginning

gravimétrico, o doseamento é feito mediante o controlo da diferença entre o fluxo de material no escoamento real e o fluxo pretendido, e a correspondente actuação na velocidade do extractor, de modo a anular as diferenças encontradas.gravimetric, dosing is done by controlling the difference between the material flow in the actual flow and the desired flow, and the corresponding action on the extractor speed, in order to cancel the differences found.

No caso do doseamento e mistura de vários materiais diferentes, usam-se tradicionalmente máquinas que são constituídas por diversas unidades, do tipo das atrás descritas, dispostas em paralelo e debitando cada uma delas a quantidade de material necessária para que este esteja na correcta proporção na mistura final.In the case of the dosing and mixing of several different materials, machines that consist of several units, of the type described above, are traditionally used in parallel and debiting each of them the amount of material necessary for it to be in the correct proportion in the final mixture.

Os inconvenientes das máquinas e processos correspondentes aos princípios e sistemas descritos são, essencialmente, o menor rigor que se verifica no doseamento volumétrico, e a necessidade de, no caso do doseamento gravimétrico, se utilizarem meios de cálculo e de actuação muitíssimo rápidos, sob pena de o rigor da dosagem ser igualmente prejudicado.The disadvantages of the machines and processes corresponding to the principles and systems described are, essentially, the lesser rigor that is verified in the volumetric dosing, and the necessity, in the case of gravimetric dosing, to use very fast calculation and acting means, under penalty that the accuracy of the dosage is also impaired.

Segundo o processo e o aparelho inventados, o doseamento preciso dos componentes integrantes de uma dada mistura, que se pretende homogénea, é obtido mediante uma sucessão de dosagens elementares - que originam lotes elementares - em que, em cada uma delas, se compensam os erros que eventualmente se tenham cometido nas proporções de qualquer componente no lote elementar resultante do doseamento elementar imediatamente anterior.According to the invented process and apparatus, the precise dosing of the constituent components of a given mixture, which is intended to be homogeneous, is obtained through a succession of elementary dosages - which give rise to elementary batches - in which, in each of them, errors are compensated that may have been committed in the proportions of any component in the elementary lot resulting from the immediately preceding elementary dosage.

Desse modo, consegue-se uma mistura global (resultante da mistura dos diversos lotes elementares) com uma precisão muitíssimo elevada, uma vez que o eventual excesso ou defeito de um qualquer componente na mistura global é igual ao correspondente excesso ou defeito no último lote elementar processado.In this way, a global mixture (resulting from the mixture of the different elementary lots) is obtained with a very high precision, since the eventual excess or defect of any component in the global mixture is equal to the corresponding excess or defect in the last elementary lot. processed.

Por outro lado, a regulação das quantidades de cada componente da mistura, aquando da elaboração de um lote elementar, é feita através de uma medição directa do peso, efectuada de modo totalmente independente do tempo.On the other hand, the regulation of the quantities of each component of the mixture, when elaborating an elementary batch, is done through a direct measurement of the weight, carried out in a totally independent time.

Dessa forma, não só se consegue evitar o recurso a meios de pesagem com leitura muito rápida, que são sempre bastante caros, como se consegue ainda aumentar a precisão das proporções de cada componente na mistura, visto poder-se utilizar meios de pesagem mais sensíveis.Thus, not only can we avoid the use of weighing means with very fast reading, which are always quite expensive, but we can also increase the accuracy of the proportions of each component in the mixture, since we can use more sensitive weighing means .

Assim, a precisão da mistura é desde logo assegurada na constituição de cada lote elementar, o que garante a elevadíssima precisão da mistura global.Thus, the accuracy of the mixture is immediately guaranteed in the constitution of each elementary batch, which guarantees the very high precision of the overall mixture.

Por cada lote elementar, para além do doseamento atrás descrito, designado por doseamento principal, existe um outro, designado por secundário, que se destina exclusivamente a misturar, de modo homogéneo, os constituintes do referido lote.For each elementary batch, in addition to the dosage described above, called the main dosage, there is another one, called the secondary dosage, which is intended exclusively to mix, homogeneously, the constituents of that batch.

Tal doseamento é dependente do tempo, uma vez que com ele, basicamente, se regula o esvaziamento das tremonhas onde foram previamente depositados os componentes resultantes da dosagem principal, de modo a que todas fiquem vazias ao mesmo tempo.Such dosing is time-dependent, since it basically regulates the emptying of hoppers where the components resulting from the main dosage were previously deposited, so that all are empty at the same time.

A resposta do sistema de pesagem não precisa de ser muito rápida aquando da dosagem secundária, uma vez que qualquer imprecisão, que eventual mente se verifique, apenas se repercute na homogeneidade da mistura e nunca nas proporções dos seus diversos elementos, visto que estas ficam desde logo asseguradas pela dosagem principal.The response of the weighing system does not need to be very fast when secondary dosing, since any inaccuracy, which may occur, only affects the homogeneity of the mixture and never the proportions of its various elements, since these are since soon ensured by the main dosage.

Por seu turno, qualquer ligeira falta de homogeneidade é anulada pelo comportamento de certo modo aleatório dos componentes aquando da sua queda no funil de reunião dos diversos componentes - o qual, para ajudar à mistura homogénea dos vários elementos, poderá ter uma superfície interna com deflectores que desviem a direcção dos respectivos pós ou grãos em queda - bem como durante a mistura dos diversos lotes elementares no reservatório tampão normalmente colocado à saída do dito funil.In turn, any slight lack of homogeneity is canceled out by the somewhat random behavior of the components when they fall into the funnel of the various components - which, to help the homogeneous mixture of the various elements, may have an internal surface with deflectors that deviate the direction of the respective powders or falling grains - as well as during the mixing of the several elementary lots in the buffer tank normally placed at the exit of said funnel.

Na figura 1, apresentada a título exemplificativo e não limitativo, representa-se, de forma esquemática, um modo particular de concretização do aparelho objecto do presente pedido de patente.In figure 1, shown by way of example and not limiting, a schematic representation of a particular embodiment of the apparatus object of the present patent application is shown.

Aí podem ser vistos:There you can see:

- os reservatórios individuais (A), para cada um dos componentes da mistura final;- the individual reservoirs (A), for each of the components of the final mixture;

- as correspondentes válvulas (B), com os respectivos rotores (C) de palhetas e motores (D) de movimento reversível;- the corresponding valves (B), with the respective vane rotors (C) and motors (D) with reversible movement;

- as tremonhas (E) e respectivas células de carga (F);- hoppers (E) and their load cells (F);

- as válvulas (G) das tremonhas, com seus rotores (C), e os correspondentes motores (H) de velocidade variável e movimento reversível;- the valves (G) of the hoppers, with their rotors (C), and the corresponding motors (H) with variable speed and reversible movement;

- o funil (I) de reunião dos componentes da mistura;- the funnel (I) for gathering the components of the mixture;

- e o reservatório tampão (J).- and the buffer reservoir (J).

O funcionamento do aparelho segue o processo de dosear e homogeneizar que é igualmente objecto do presente pedido de patente, funcionamento esse que seguidamente se descreve com base no modo preferencial de execução do dito aparelho apresentado na referida figura.The operation of the apparatus follows the process of dosing and homogenizing which is also the subject of the present patent application, which operation is described below on the basis of the preferred mode of execution of said apparatus shown in said figure.

Escolhida a mistura pretendida, fornece-se a respectiva receita, isto é, a proporção (em volume ou em massa) em que cada componente entra na mistura final, ao centro de comando do aparelho (CCA)Once the desired mixture is chosen, the respective recipe is provided, that is, the proportion (by volume or mass) in which each component enters the final mixture, to the device's control center (CCA)

(constituído preferencialmente por um computador). De acordo com os elementos instalados na máquina designadamente, número de depósitos, capacidade dos depósitos, velocidade dos motores (H) de accionamento das válvulas (G) de extracção do material contido nas tremonhas (E) - o CCA, a que tais elementos são inicialmente fornecidos, calcula o peso ideal de um lote elementar, bem como o peso de cada componente nesse lote, cálculo este que assenta na receita inicialmente fornecida ao sistema .(preferably made up of a computer). According to the elements installed in the machine, namely, number of tanks, tank capacity, engine speed (H) for driving the valves (G) for extracting the material contained in the hoppers (E) - the CCA, to which these elements are initially supplied, calculates the ideal weight of an elementary lot, as well as the weight of each component in that lot, which calculation is based on the recipe initially supplied to the system.

Uma vez determinado o peso de cada elemento em cada lote elementar, o CCA acciona os motores (D), faz a leitura dos valores indicados pelas células de carga (F) das tremonhas (E) e compara para cada componente - o peso do material já despejado do respectivo reservatório (A) para a tremonha com o peso previsto para esse componente, que havia sido calculado pelo modo atrás descrito.Once the weight of each element in each elementary lot has been determined, the CCA drives the motors (D), reads the values indicated by the load cells (F) of the hoppers (E) and compares for each component - the weight of the material already poured from the respective reservoir (A) into the hopper with the expected weight for that component, which had been calculated by the method described above.

Logo que, para um dos ditos componentes, esse peso previsto tenha sido atingido, o CCA inverte momentaneamente o sentido de rotação do correspondente motor (D), obrigando a válvula (B) a rodar ligeiramente para trás, de modo a impedir que caia para a tremonha (E) o material ainda existente no(s) alvéolo(s) da válvula que esteja(m) a ser despejado(s).As soon as, for one of the said components, that predicted weight has been reached, the CCA momentarily reverses the direction of rotation of the corresponding engine (D), forcing the valve (B) to turn slightly backwards, in order to prevent it from falling to the hopper (E) the material still in the valve socket (s) that is being poured.

Estas operações, que se realizam simultaneamente para todos os componentes, constituem o doseamento principal, findo o qual o CCA, com base nos pesos de material efectivamente despejado para as tremonhas, calcula os desvios relativamente aos valores inicialmente previstos.These operations, which are carried out simultaneously for all components, constitute the main dosage, after which the CCA, based on the weights of material actually poured into the hoppers, calculates the deviations from the initially predicted values.

Seguidamente, o CCA, previamente informado das características dos motores e válvulas acoplados à saída das tremonhas - designadamente, as cilindradas da válvulas (G), isto é, o volume arrastado por cada volta do seu rotor (C), e a curva de resposta dos servomotores (H), em termos de velocidade - calcula o período previsto para o vazamento de todas as tremonhas (tendo em conta as quantidades de material efectivamente contidas nestas) e a velocidade das respectivas válvulas (G), de modo a que todos os escoamentos não só terminem no fim do referido período mas mantenham, durante tal período, fluxos cuja proporção relativa entre si seja igual à proporção do peso dos diversos componentes realmente contidos nas tremonhas no final da dosagem principal.Then, the CCA, previously informed of the characteristics of the engines and valves coupled to the hopper outlet - namely, the cylinder sizes of the valves (G), that is, the volume dragged by each turn of its rotor (C), and the response curve of the servomotors (H), in terms of speed - calculates the expected period for the leakage of all hoppers (taking into account the amounts of material actually contained in them) and the speed of the respective valves (G), so that all flows not only end at the end of the said period but maintain, during that period, flows whose relative proportion to each other is equal to the proportion of the weight of the various components actually contained in the hoppers at the end of the main dosage.

Concluído o referido cálculo, são postos em funcionamento os motores (H) e os fluxos sãoAfter the aforementioned calculation is completed, the engines (H) are started and the flows are

controlados de modo análogo ao utilizado no sistema de doseamento gravimétrico por perda de peso.controlled in a manner similar to that used in the gravimetric dosing system for weight loss.

Durante este período, que constitui a dosagem secundária, o material despejado pelas várias tremonhas mistura-se no funil (I), caindo em seguida para o reservatório tampão (J), terminando-se assim a constituição de um lote elementar e fechando-se um ciclo de funcionamento do aparelho.During this period, which constitutes the secondary dosage, the material dumped by the various hoppers mixes in the funnel (I), then falls into the buffer reservoir (J), thus ending the constitution of an elementary batch and closing a device operating cycle.

No ciclo seguinte, outro lote elementar será constituído, de modo análogo ao acabado de descrever, com a única e fundamental diferença de o CCA, no cálculo do peso de cada componente para a constituição do lote elementar, entrar em conta com o desvio medido para esse componente no lote anterior.In the following cycle, another elementary lot will be constituted, similar to the one just described, with the only and fundamental difference that the CCA, in calculating the weight of each component for the constitution of the elementary lot, will take into account the deviation measured for that component in the previous batch.

No caso especial em que, para um determinado conjunto de componentes em particular, o rigor tenha de estar no peso da respectiva mistura e não no peso de cada um deles em particular, poderá ser utilizada uma solução do tipo da representada na figura 1, onde se utiliza uma só tremonha para todos os componentes que integrem o referido conjunto.In the special case in which, for a particular set of components in particular, the rigor must be in the weight of the respective mixture and not in the weight of each of them in particular, a solution of the type represented in figure 1 can be used, where a single hopper is used for all components that make up the set.

Finalmente, convém ainda referir que, na eventualidade de qualquer encravamento de uma das válvulas - assinalado pelo correspondente detector de encravamento (por exemplo, um contador de impulsos acoplado a um interruptor magnético em que o elemento de fecho se encontra preso ao veio do motor) - o CCA inverterá momentaneamente o sentido de rotação do motor e da válvula em causa. Se o encravamento persistir, o CCA interromperá o ciclo, avisando o operador do aparelho desse facto.Finally, it should also be noted that, in the event of any jamming of one of the valves - signaled by the corresponding interlocking detector (for example, a pulse counter coupled to a magnetic switch where the closing element is attached to the motor shaft) - the CCA will momentarily reverse the direction of rotation of the engine and the valve concerned. If the jam persists, the CCA will interrupt the cycle, notifying the operator of the fact.

Independentemente de a solução preferencial utilizada no aparelho ser a que passa pela utilização das válvulas anteriormente indicadas, outras poderão ser utilizadas em sua substituição, sendo disso exemplo as válvulas rotativas de esfera, as válvulas rotativas de palhetas, dotadas de eixo vertical, ou mesmo as válvulas de guilhotina.Regardless of whether the preferred solution used in the device is the one that involves the use of the previously indicated valves, others may be used instead, such as ball rotary valves, vane rotary valves with a vertical axis, or even the guillotine valves.

Claims

I ^a . Apparatus for dosing by weighing and homogeneously mixing powdered or granular solids in a homogeneous manner with a solids collecting funnel (I) to be homogeneously mixed as well as for each type of solids or set of solids, a storage tank (A) with extractor (B) and a hopper (E) with quantity meter (F), namely of weight, in particular a load cell characterized by extractors (G) at the outlet of the hoppers (E), driven by variable speed motors (H), which extractors only start when said extractors (B) are deactivated.

2 ^a . Apparatus according to the first claim, characterized in that the extractors (B) of the reservoirs (A) and / or extractors (G) of the hoppers (E) are rotary valves with a static shell and a rotor (C) with vanes always keep the valve inlet and outlet openings separate from each other.

3 ^a . Apparatus according to one of the preceding claims, characterized in that the rotors (C) of the valves (B) of the reservoirs (A) invert the direction of rotation for a very short time, immediately after their respective stop.

4 ^a . Apparatus as claimed in any one of the preceding claims, characterized by rotor movement locking detectors (C).

5 ^a . Apparatus according to any one of the preceding claims, characterized in that a buffer reservoir (J) is provided at the outlet of the funnel (I) for meeting the intermittent flows of the various solids.

6 ^a . A method of dosing, in a pseudo continuum, and homogeneously mixing pulverized or granular solids, wherein there is a separate measuring step of the amount of each solid or set of solids, said main dosage, wherein only the extractors (B) are moved and wherein the quantity of each of said solids or solids assemblies is measured, by positive addition, from the values given by the respective meter (F) connected to the corresponding hopper (E) characterized by if a secondary dosing step is followed by the simultaneous and homogeneous mixing of all the solid components or sets of solid components, the dimensions of which have already been previously measured and are located in said hoppers (E), by the action of the corresponding extractors (G) with variable speed corresponding to the percentage of the respective solid or set of solids in the overall mixture and controlled based on the decrease of qu antiquity of said solids or solids assemblies within the respective hopper, as determined on the basis of the values given by the same quantity meter (F), now operating by decreasing quantity.

7 ^a . A process according to claim 1, characterized in that, in each cycle, the actual quantity of each solid processed in the batch formation is rigorously measured, because the differences between the measured value for each solid (or set of solids) and corresponding value are compensated in the following cycle by correcting the values predicted for each solid in that cycle and in each cycle the values of the flows provided for the secondary dosages are corrected, compensating the error measured in the corresponding main dosages already made in that cycle .

8 ^a . Method according to any of the preceding two claims, characterized in that the quantity measured by the meter (F) is the weight.

9 ^a . A method according to any one of the preceding three claims, characterized in that the intermittent supply of material resulting from the overall mixture is eliminated by placing a buffer reservoir (J) at the outlet of the funnel (I) of the intermittent flows of the various solids, always that a continuous output stream is desired.

10 ^a . A process according to any one of the preceding four claims, characterized in that each cycle is constituted by an elementary dosage consisting of a main dosage followed by a secondary dosage, in that the overall dosage is the result of mixing the elementary batches corresponding to the elementary dosages, accuracy of the overall blend is a function exclusive to the accuracy and number of main dosages of its constituent batches and in that the homogeneity of this mixture is essentially a function of the accuracy of the secondary dosages and is substantially independent of the accuracy of the main dosages.

11 ^a . Measurements made according to any of the five characterized in that, at each respective end, they are, at the main dosage level, time independent, with well defined doses of solids being measured.