WO2014057150A1 - Method and device for measuring the volume of objects made of hygroscopic materials with a complex geometry, by means of a pneumatic system. - Google Patents

Method and device for measuring the volume of objects made of hygroscopic materials with a complex geometry, by means of a pneumatic system. Download PDF

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Publication number
WO2014057150A1
WO2014057150A1 PCT/ES2013/070405 ES2013070405W WO2014057150A1 WO 2014057150 A1 WO2014057150 A1 WO 2014057150A1 ES 2013070405 W ES2013070405 W ES 2013070405W WO 2014057150 A1 WO2014057150 A1 WO 2014057150A1
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Prior art keywords
volume
boiler
measuring chamber
pressure
stopcock
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PCT/ES2013/070405
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Spanish (es)
French (fr)
Inventor
César PÉREZ CRUZADO
Alberto ROJO ALBORECA
Roque RODRÍGUEZ SOALLEIRO
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Universidade De Santiago De Compostela
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Publication of WO2014057150A1 publication Critical patent/WO2014057150A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
    • G01N9/02—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by measuring weight of a known volume
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F17/00—Methods or apparatus for determining the capacity of containers or cavities, or the volume of solid bodies
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
    • G01N9/02—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by measuring weight of a known volume
    • G01N2009/022—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by measuring weight of a known volume of solids

Definitions

  • the present invention is applicable in the sectors: of the forestry industry for the measurement of the volume of pieces of wood, shavings, barks or sawdust with different moisture contents; of solid biofuels for measuring volume of densified biofuels, chips or charcoal; of agriculture for the determination of the volume in grains or feed; and agricultural and forestry research to determine the volume of rocks, soils and plant tissues with different moisture contents.
  • the density of a material is a very important physical property, for whose determination it is essential to measure its volume.
  • materials that have hygroscopicity -defining this as the property to absorb moisture in its breast, and its volume may or may not vary in this process-, such as wood the relationship between volume to a certain moisture content is usually used and Dry weight at 105 ° C.
  • This parameter is defined as basic density when the volume is measured at maximum moisture content, and is very important for the forestry industry and for studies of biomass productivity or related to the natural environment [AJ Panshin, C de Zeeuw .; Textbook of wood technology, 4th Edition (1980) 722 pp; K. Senelwa, REH Sims .; Biomass Bioenerg.
  • Another problem with this methodology is the way in which the immersion of the object to be measured is achieved completely when it has a density lower than that of water.
  • the object to be measured consists of a single piece, needles are usually used, which are assumed to be an insignificant volume with respect to the object to be measured [R. Nygárd, B. Elfving .; Ann. For. Sci. 57 (2000) 143-153; J. Ilic, D. Boland, M. McDonald, G. Downes, P. Blakemore .; National coal accounting system. Tech. Rep. 18 (2000) 234 pp], but when the material is granular - such as chips - this system is not effective.
  • the main problems of these methodologies are: low measurement accuracy, conditioned by the scale of the level that marks the height of water displaced by the submerged object; the high water consumption when it is necessary to carry out many measurements, which can be solved by means of a filtering and storage system of the water used that allows its recycling; need for specific instruments and procedures to ensure complete immersion of the object to be measured when it has a density less than that of water and / or is a granular material; Depending on the object to be measured, the analysis can be destructive; Need to pre-treat the object to be measured when the material that constitutes it presents hygroscopicity, which complicates the measurement in granular materials, such as chips, pellets, floors or other elements.
  • EP 0 434 207 A2 describes a device and a procedure that solves part of the problems described for the methodology of immersion in water, but nevertheless presents a series of conditions that limit its practical application.
  • Some of these problems are: it requires the use of gases other than air for measurement, such as helium; there is no control over the operating temperature of the device, which affects the ideal behavior of the gas used for the measurement and therefore on the accuracy of the volume measurement, the measurement cycle causes air flow from the chamber of measurement towards the expansion chamber, assuming deposition of fine materials of the object to be measured in this part of the device, which is partially corrected by a system that ensures a progressive and controlled flow of gas between the measurement chamber and the chamber of expansion, but causes prolonged measurement times that may involve the evaporation of water on the surface of the material of the object to be measured, and therefore disturbances in the pressure measurement; and finally, the theoretical procedure that allows the measurement of the volume of the object to be measured based on the pressures that are reached in the measurement and expansion chambers does not take into account the number of mo
  • the inventors have developed a device and a procedure that allows the measurement of the volume in objects of hygroscopic materials of complex geometry by means of a pneumatic system that avoids the use of water and gases other than air.
  • the device is called pneumatic xilometer, and allows the volume of granular materials to be measured.
  • the practice of the present invention has the following advantages with respect to the devices and procedures already known: greater control over the accuracy of the measurement, by allowing to increase the filling factor of the measuring chamber by solids of incompressible materials of known volume while the useful volume of the measuring chamber remains unchanged; it does not consume water or helium due to a system of drying and cleaning of the ambient air that allows its use in the measurement; It is not affected by changes in temperature between the different parts of the device, as the cleaning system ensures air flow at a constant temperature, which will always be the same at ambient operating temperature;
  • the design allows a rapid balance of the pressures in the two chambers that form it at the time of the expansion, which allows reducing the measurement time and therefore the error made in the measurement of samples with high moisture content whose evaporation It could affect the pressure measurement;
  • the design guarantees that no deposition of fines occurs in the device between two measurement cycles, since there is positive pressure that expels them between two measurement cycles;
  • the present invention describes a method and a device for measuring the volume of objects of hygroscopic materials with complex geometry by pneumatic system.
  • Hygroscopic material is understood as any one that is capable of absorbing liquids in its breast, its volume may or may not vary in this process depending on the type of material and its moisture content, such as wood.
  • a pneumatic system is understood as the one based on the use of compressed air.
  • the present invention describes a process, comprising the following steps: a) Housing the object of hygroscopic material of complex geometry (1) in the container (9) of the measuring chamber (2).
  • the container (9) has a smaller diameter than the measuring chamber (2), so that it does not prevent the entry of pressurized air from the boiler (6) to all parts of the measuring chamber (2), but prevents the abrupt incorporation of that air produces an alteration or dragging of the finest parts of the object to be measured;
  • the container (9) has the function of facilitating the filling of material in the measuring chamber (2) for the measurement of its volume and preventing the occurrence of trawls of fine material of the object to be measured that can be deposited in the bottom of the chamber of measurement (2), being able to occupy volume that affects the measurement of the following object in the case of not being conveniently removed.
  • ⁇ is the pressure measured according to phase e) of the measuring cycle
  • P 2 is the pressure measured according to phase g) of the measuring cycle
  • P 0 is the pressure measured according to phase c) of the measuring cycle measurement
  • V is the useful volume of the boiler (6) with the stopcocks (5) and (6) closed
  • V 2 is the useful volume of the measuring chamber (2) with the stopcocks (4) and (5) closed and considering the inner container (9), and V , is the volume that displaces the mechanism of the stopcock (5) in its opening and closing in the pipe that connects the measuring chamber (2) with the boiler (6), as shown in Fig. 2.
  • the closing mechanism of the stopcock (5) must be solid, so as not to allow the accumulation of pressurized air within it between two measurement cycles. In this way, the volume occupied by the closing mechanism (V ,,) in the conduction between the measuring chamber (2) and the boiler (6), can be occupied by pressurized air P 2 at the time of opening of the stopcock (5) in phase f) of the measurement cycle.
  • Measuring cycle is understood as all the operations necessary for measuring the volume on the same object, and there may be more than one measuring cycle on the same object, both by reloading the boiler (6) with air up to the pressure working after the first measurement cycle, such as by the use of pressure P 2 in the boiler (6) after the first measurement cycle as pressure Pi in the second measurement cycle (P 2 1 st 2nd cycle), until the measurement cycle n in the pressure reboiler (6) Pi is below the threshold to estimate the volume of the object with the desired accuracy (P M IN), as shown in Fig 6.
  • P M IN desired accuracy
  • the maximum working pressure (P M AX) is established as that value, assuming that the material occupies the entire volume destined for its accommodation in the container (9) v n of the measuring chamber (2), The pressure P 2 that is reached in the volume ⁇ / + ⁇ / 2 + ⁇ / u when opening the stopcock (5) does not produce significant volume losses in the object to be measured, as shown in Fig. 6.
  • the minimum working pressure (P M IN) is also set as that value of Pi that allows the measurement of the volume (v) in the object (1) with sufficient precision, as shown in Fig. 6.
  • the air incorporated into the boiler (6) in phase d) of the measuring cycle must be free of moisture, oil or particles, so that they do not occupy useful volume of the boiler (6) or the measuring chamber (2) , so that the volumes and V 2 that can be occupied by air in the different phases of the measurement and which are schematized in Fig. 2 remain invariant for several measurement cycles on the same object, without prejudice that the useful volume V 2 of the measuring chamber (2) can be varied by using solids of known volume to increase the filling factor, thereby increasing the accuracy in measuring the volume.
  • the measuring chamber (2) is of variable geometry, this referring to that part of the volume thereof can be occupied by an object of known volume v 0B j, which added to the volume (v) measuring object (1) assume that both occupy a greater proportion of the useful volume V 2 of the measuring chamber (2) Liquid Fill -factor, thereby increasing the variation in the pressure P 2 which is a positive variation or volume negative dv of the volume occupied by v + v 0B j in the measuring chamber (2), thus allowing to increase the precision in the volume measurement while maintaining the sensitivity of the absolute pressure transducers (3) and (8) ).
  • the volume measured in this way in the measurement phase h) would be the sum of the volume of the object to be measured (v) and the known volume (VOBJ) of the object used to reduce the useful volume of the measuring chamber (2).
  • the volume of the object V 0 BJ used for this purpose must not reduce the measurement process.
  • the air incorporated into the boiler (6) in phase d) of the measurement cycle must be at the same temperature as that of all the equipment - working temperature in the laboratory - so that the kinetic theory of the ideal gases and the Boyle-Mariotte principle, so that the cooling air dryer (17) must raise the temperature of the air at its outlet to the working temperature at which all the equipment is located.
  • Another aspect of the present invention is a device for measuring volume in hygroscopic materials of complex geometry by pneumatic system, characterized by the following elements shown in Fig.
  • the closing system of the stopcock (5) does not allow the accumulation of air inside the opening and closing procedure, and the insertion point of the conduction with the measuring chamber (2) is not more than 1 ⁇ 4 of the height of the inner vessel (9), so that the sudden entry of pressurized air into the measuring chamber (2) from the boiler (6) in phase f) of the measuring cycle does not directly affect the object to be measured (1) beyond the increase in pressure that occurs in the measuring chamber (2).
  • the pressure regulating valve (15) will allow the supply of pressurized air from the compressor (11) to be cut off at the moment when the pressure in the boiler (6) reaches the desired value of the working pressure P ⁇ , which will be accurately measured with the absolute pressure transducer (8) after closing the stopcock (7) in phase e) of the measurement cycle.
  • the calibrated non-return valve (16) will prevent the passage of air in the opposite direction to that of operation in the event that it is operated in the oil, moisture and solids removal system (12) with the stopcock (7) open and the compressor (11) off.
  • the cooling air dryer (17) must raise the air temperature to the operating temperature in the laboratory to ensure that the kinetic theory of the ideal gases and the Boyle-Mariotte principle, and the maximum air flow rate, apply of work must be superior to the operation of the compressor (11), so as to ensure efficient air drying.
  • the liquid elimination systems (13) and (14) have the function of allowing the elimination of water accumulation in the measuring chamber (2) or boiler (6) in the maintenance process.
  • stopcocks (4) and (7) which are the measuring chamber (2), the boiler (6) and the conduit that communicates them must be rigid, so that they must not see its volume varied with the pressures to which they are subjected in the measurement cycle, so that the volumes and V 2 remain constant.
  • the material of all components must have a high thermal conductivity, such as steel, so that heat dissipation and the permanence of all equipment at the air supply temperature is favored after treatment in the system cleaning (12), which will be equal to room temperature.
  • Figure 1 represents the general scheme of the device, characterized by a measuring chamber (2), a boiler (6), a device for controlling the loading pressure in the boiler (10), a device for oil removal , moisture and solids in the air (12), a compressor (11) and three stopcocks (4), (5) and (7).
  • Figure 2 represents the volume of the different parts of the device (V ⁇ , V 2 , 1 ⁇ 4), which are fundamental for the estimation of the volume (v) of the object to be measured (1).
  • Figure 3 represents the device in phase e) of the measurement cycle.
  • Figure 5 represents the device in phase g) of the measurement cycle.
  • Figure 6 represents the relationship between the pressures P ⁇ and P 2 that would be reached in the device in the measurement process, bounded by V max , theoretical situation in the case of that the object to be measured completely occupies the volume V 2 in the measuring chamber (2), and V Q in the event that it is operated with the device without an object (1) in the measuring chamber (2).

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Abstract

A method and a device for measuring the volume of objects made of hygroscopic materials with a complex geometry, by means of a pneumatic system. The device comprises a system of two chambers with built-in absolute pressure transducers, one chamber receiving the object to be measured and the other being the chamber where compressed air accumulates. The compressed air supplied to the system first passes through a cleaning system. The pressure of the air incorporated is controlled by means of a pressure limiter. The volume of the object is measured on the basis of the volume of the two chambers and the reading of the pressures reached in said chambers during the measuring cycle, as one of the chambers is pressurized and then the valve that places them in communication is opened. The method may be used for hygroscopic materials of complex geometry, such as wood, pellets, granular feed or soil.

Description

Procedimiento y dispositivo para la medición del volumen de objetos de materiales higroscópicos de geometría compleja mediante sistema neumático  Procedure and device for measuring the volume of objects of hygroscopic materials of complex geometry by pneumatic system
SECTOR TÉCNICO DE LA INVENCIÓN La presente invención es de aplicación en los sectores: de la industria forestal para la medición del volumen de piezas de madera, virutas, cortezas o serrines con distintos contenidos de humedad; de los biocombustibles sólidos para la medición de volumen de biocombustibles densificados, astillas o carbón vegetal; de la agricultura para la determinación del volumen en granos o piensos; y de la investigación agraria y forestal para determinar el volumen de rocas, suelos y tejidos vegetales con distintos contenidos de humedad. TECHNICAL SECTOR OF THE INVENTION The present invention is applicable in the sectors: of the forestry industry for the measurement of the volume of pieces of wood, shavings, barks or sawdust with different moisture contents; of solid biofuels for measuring volume of densified biofuels, chips or charcoal; of agriculture for the determination of the volume in grains or feed; and agricultural and forestry research to determine the volume of rocks, soils and plant tissues with different moisture contents.
ESTADO DE LA TÉCNICA STATE OF THE TECHNIQUE
La densidad de un material es una propiedad física muy importante, para cuya determinación se hace imprescindible la medición de su volumen. Para materiales que presentan higroscopicidad -definiéndose esta como la propiedad para absorber humedad en su seno, pudiendo o no variar su volumen en este proceso-, como por ejemplo la madera, se suele emplear la relación entre el volumen a un cierto contenido de humedad y el peso seco a 105°C. Este parámetro se define como densidad básica cuando el volumen es medido al máximo contenido de humedad, y es muy importante para la industria forestal y para estudios de productividad de biomasa o relativos al medio natural [A.J. Panshin, C de Zeeuw.; Textbook of wood technology, 4th Edition (1980) 722 pp; K. Senelwa, R.E.H. Sims.; Biomass Bioenerg. 17 (1999) 127-140; H.C. Muller-Landau.; Biotropica 36 (2004) 20-32; B. Klasnja, S. Kopitovic, S. Orlovic; Biomass Bioenerg. 23 (2002) 427-432]. La medición del volumen en objetos de geometría compleja se suele abordar mediante su inmersión en agua y determinación del volumen de líquido desalojado por el objeto a medir, según el principio de Arquímedes. Este procedimiento también es el habitual cuando el objeto a medir presenta higroscopicidad, como por ejemplo la madera, [P.O. Olesen.; For. Tree Improv. 3, (1971) 1-23]. Para este último caso, se ha descrito un dispositivo, denominado xilómetro, para la determinación del volumen de trozas grandes de madera [A. Martin.; For. Sci. 30 (1984) 41-50; D.R. Phillips, M.A. Taras.; For. Prod. Jour. 10 (1984) 37-42; Diccionario Forestal. Soc. Esp. Ciencias Forest. (2005) 1314 pp], donde el volumen de agua desplazado por la pieza de madera sumergida es medido en una escala graduada. En este caso es necesario efectuar una medición rápida, de forma que la absorción de agua por parte del material se pueda considerar como insignificante, y por lo tanto al material como impermeable. The density of a material is a very important physical property, for whose determination it is essential to measure its volume. For materials that have hygroscopicity -defining this as the property to absorb moisture in its breast, and its volume may or may not vary in this process-, such as wood, the relationship between volume to a certain moisture content is usually used and Dry weight at 105 ° C. This parameter is defined as basic density when the volume is measured at maximum moisture content, and is very important for the forestry industry and for studies of biomass productivity or related to the natural environment [AJ Panshin, C de Zeeuw .; Textbook of wood technology, 4th Edition (1980) 722 pp; K. Senelwa, REH Sims .; Biomass Bioenerg. 17 (1999) 127-140; HC Muller-Landau .; Biotropica 36 (2004) 20-32; B. Klasnja, S. Kopitovic, S. Orlovic; Biomass Bioenerg. 23 (2002) 427-432]. The measurement of the volume in objects of complex geometry is usually addressed by immersion in water and determining the volume of liquid dislodged by the object to be measured, according to the Archimedes principle. This procedure is also the usual procedure when the object to be measured has hygroscopicity, such as wood, [PO Olesen .; For. Tree Improv 3, (1971) 1-23]. For the latter case, a device, called a xilometer, has been described for the determination of the volume of large pieces of wood [A. Martin.; For. Sci. 30 (1984) 41-50; DR Phillips, MA Taras .; For. Prod. Jour. 10 (1984) 37-42; Forest Dictionary. Soc. Esp. Forest Sciences. (2005) 1314 pp], where the volume of water displaced by the submerged piece of wood is measured in A graduated scale. In this case it is necessary to make a rapid measurement, so that the absorption of water by the material can be considered as insignificant, and therefore to the material as impermeable.
Sin embargo, cuando no se puede permitir que el material adquiera humedad en el proceso de medición de su volumen, son necesarios tratamientos adicionales cuando se quiere emplear el método del desplazamiento de agua. Estos tratamientos consisten en la saturación por completo en agua cuando el volumen que interesa medir es el que ocurre con el máximo contenido de humedad [I. lista.; Teknoloji.; 1-2 (2001) 1 1-18], o el tratamiento del material para que no absorba agua cuando el volumen interesa ser medido a humedades inferiores a las máximas que puede alcanzar el material. En este último caso se suele recurrir al recubrimiento de su superficie con materiales impermeabilizantes -como por ejemplo parafina-, o al congelado [R. Mákipáá, T. Linkosalo.; Silva Fenn. 45 (2011) 1135-1142], siendo este último método especialmente sensible a sobreestimaciones del volumen. Otro problema de esta metodología es la forma mediante la que se consigue la inmersión por completo del objeto a medir cuando éste presenta una densidad menor que la del agua. Cuando el objeto a medir consta de una única pieza se suelen emplear agujas, a las que se les supone un volumen insignificante con respecto al objeto a medir [R. Nygárd, B. Elfving.; Ann. For. Sci. 57 (2000) 143-153; J. Ilic, D. Boland, M. McDonald, G. Downes, P. Blakemore.; National carbón accounting system. Tech. Rep. 18 (2000) 234 pp], pero cuando el material es granular -como por ejemplo astillas-, este sistema no es efectivo. However, when the material cannot be allowed to acquire moisture in the process of measuring its volume, additional treatments are necessary when the water displacement method is to be used. These treatments consist of saturation completely in water when the volume of interest is the one that occurs with the maximum moisture content [I. list.; Teknoloji .; 1-2 (2001) 1 1-18], or the treatment of the material so that it does not absorb water when the volume is of interest to be measured at humidities lower than the maximum that the material can reach. In the latter case, the surface is usually covered with waterproofing materials - such as paraffin - or frozen [R. Mákipáá, T. Linkosalo .; Silva Fenn. 45 (2011) 1135-1142], the latter method being especially sensitive to overestimations of volume. Another problem with this methodology is the way in which the immersion of the object to be measured is achieved completely when it has a density lower than that of water. When the object to be measured consists of a single piece, needles are usually used, which are assumed to be an insignificant volume with respect to the object to be measured [R. Nygárd, B. Elfving .; Ann. For. Sci. 57 (2000) 143-153; J. Ilic, D. Boland, M. McDonald, G. Downes, P. Blakemore .; National coal accounting system. Tech. Rep. 18 (2000) 234 pp], but when the material is granular - such as chips - this system is not effective.
Los principales problemas de estas metodologías son: baja precisión en la medición, condicionada por la escala del nivel que marque la altura de agua desplazada por el objeto sumergido; el elevado consumo de agua cuando es necesario efectuar muchas mediciones, lo cual puede ser solventado mediante un sistema de filtrado y almacenamiento del agua utilizada que permita su reciclado; necesidad de instrumentos y procedimientos específicos para asegurar la inmersión completa del objeto a medir cuando éste presenta una densidad menor que la del agua y/o es un material granular; dependiendo del objeto a medir, el análisis puede ser destructivo; necesidad de pretratamiento del objeto a medir cuando el material que lo constituye presenta higroscopicidad, lo que complica la medición en materiales granulares, como por ejemplo astillas, pélets, suelos u otros elementos. En el documento EP 0 434 207 A2 se describe un dispositivo y un procedimiento que soluciona parte de los problemas descritos para la metodología de inmersión en agua, pero presenta sin embargo una serie de condicionantes que limitan su aplicación práctica. Algunos de estos problemas son: necesita el empleo de gases distintos del aire para la medición, como por ejemplo el helio; no hay control sobre la temperatura de funcionamiento del dispositivo, lo cual repercute en el comportamiento ideal del gas empleado para la medición y por lo tanto en la precisión de la medida del volumen, el ciclo de medición provoca que exista flujo de aire desde la cámara de medida hacia la cámara de expansión, suponiendo deposición de materiales finos del objeto a medir en esta parte del dispositivo, lo cual es corregido en parte mediante un sistema que asegura un flujo progresivo y controlado de gas entre la cámara de medida y la cámara de expansión, pero provoca tiempos de medición prolongados que pueden suponer la evaporación de agua en la superficie del material del objeto a medir, y por lo tanto perturbaciones en la medición de la presión; y por último, el procedimiento teórico que permite la medición del volumen del objeto a medir en base a las presiones que se alcanzan en las cámaras de medida y de expansión no tiene en cuenta el número de moles de gas que hay contenido en la cámara de expansión ni el volumen ocupado por el elemento de cierre de la válvula que los comunica. Otro problema de este tipo de dispositivos con volumen constante en la cámara de medida es que la precisión que se alcanza en la medición de la presión puede no ser la óptima, al no ocupar la muestra una proporción elevada de la cámara de medida [S. Tamari, A. Aguilar-Chávez.; Simposio de Metrología (2004) 1-6]. The main problems of these methodologies are: low measurement accuracy, conditioned by the scale of the level that marks the height of water displaced by the submerged object; the high water consumption when it is necessary to carry out many measurements, which can be solved by means of a filtering and storage system of the water used that allows its recycling; need for specific instruments and procedures to ensure complete immersion of the object to be measured when it has a density less than that of water and / or is a granular material; Depending on the object to be measured, the analysis can be destructive; Need to pre-treat the object to be measured when the material that constitutes it presents hygroscopicity, which complicates the measurement in granular materials, such as chips, pellets, floors or other elements. EP 0 434 207 A2 describes a device and a procedure that solves part of the problems described for the methodology of immersion in water, but nevertheless presents a series of conditions that limit its practical application. Some of these problems are: it requires the use of gases other than air for measurement, such as helium; there is no control over the operating temperature of the device, which affects the ideal behavior of the gas used for the measurement and therefore on the accuracy of the volume measurement, the measurement cycle causes air flow from the chamber of measurement towards the expansion chamber, assuming deposition of fine materials of the object to be measured in this part of the device, which is partially corrected by a system that ensures a progressive and controlled flow of gas between the measurement chamber and the chamber of expansion, but causes prolonged measurement times that may involve the evaporation of water on the surface of the material of the object to be measured, and therefore disturbances in the pressure measurement; and finally, the theoretical procedure that allows the measurement of the volume of the object to be measured based on the pressures that are reached in the measurement and expansion chambers does not take into account the number of moles of gas that is contained in the chamber of expansion or the volume occupied by the closing element of the valve that communicates them. Another problem with this type of devices with constant volume in the measuring chamber is that the precision achieved in the pressure measurement may not be optimal, since the sample does not occupy a high proportion of the measuring chamber [S. Tamari, A. Aguilar-Chávez .; Metrology Symposium (2004) 1-6].
Teniendo el conocimiento de estos problemas, los inventores han desarrollado un dispositivo y un procedimiento que permite la medición del volumen en objetos de materiales higroscópicos de geometría compleja mediante un sistema neumático que evita el empleo de agua y gases distintos del aire. El dispositivo tiene por nombre xilómetro neumático, y permite medir el volumen de materiales granulares. Having the knowledge of these problems, the inventors have developed a device and a procedure that allows the measurement of the volume in objects of hygroscopic materials of complex geometry by means of a pneumatic system that avoids the use of water and gases other than air. The device is called pneumatic xilometer, and allows the volume of granular materials to be measured.
La práctica de la presente invención presenta las siguientes ventajas con respecto a los dispositivos y procedimientos ya conocidos: mayor control sobre la precisión de la medición, al permitir aumentar el factor de llenado de la cámara de medida mediante sólidos de materiales incompresibles de volumen conocido mientras se mantiene invariable el volumen útil de la cámara de medida; no consume agua ni helio debido a un sistema de secado y limpieza del aire ambiental que permite su uso en la medición; no se ve afectada por cambios de temperatura entre las distintas partes del dispositivo, pues el sistema de limpieza asegura flujo de aire a temperatura constante, que será siempre igual a la temperatura ambiente de funcionamiento; el diseño permite un rápido equilibrado de las presiones en las dos cámaras que lo forman en el momento de la expansión, lo que permite reducir el tiempo de medición y por lo tanto el error cometido en la medición de muestras con elevado contenido en humedad cuya evaporación pudiera afectar a la medición de la presión; el diseño garantiza que no se producen deposiciones de finos en el aparato entre dos ciclos de medición, al existir presión positiva que expulsa a los mismos entre dos ciclos de medición; el procedimiento teórico para la determinación del volumen en base a las presiones medidas en el aparato en el ciclo de medición tiene en cuenta el número de moles contenido en la cámara de menor presión antes de la expansión del aire desde la cámara de mayor presión, así como el volumen del elemento de cierre entre ambas cámaras, lo que permite un calibrado más sencillo. Estas ventajas hacen al aparato válido para la medición de materiales que varían su volumen con distintos estados de humedad mediante un análisis no es destructivo, permitiendo la medición en materiales higroscópicos, granulares y de geometría compleja. DESCRIPCIÓN DE LA INVENCIÓN The practice of the present invention has the following advantages with respect to the devices and procedures already known: greater control over the accuracy of the measurement, by allowing to increase the filling factor of the measuring chamber by solids of incompressible materials of known volume while the useful volume of the measuring chamber remains unchanged; it does not consume water or helium due to a system of drying and cleaning of the ambient air that allows its use in the measurement; It is not affected by changes in temperature between the different parts of the device, as the cleaning system ensures air flow at a constant temperature, which will always be the same at ambient operating temperature; The design allows a rapid balance of the pressures in the two chambers that form it at the time of the expansion, which allows reducing the measurement time and therefore the error made in the measurement of samples with high moisture content whose evaporation It could affect the pressure measurement; The design guarantees that no deposition of fines occurs in the device between two measurement cycles, since there is positive pressure that expels them between two measurement cycles; The theoretical procedure for determining the volume based on the pressures measured in the device in the measurement cycle takes into account the number of moles contained in the lower pressure chamber before the air expansion from the higher pressure chamber, as well as the volume of the closing element between both chambers, which allows a simpler calibration. These advantages make the device valid for the measurement of materials that vary in volume with different humidity states by means of a non-destructive analysis, allowing measurement in hygroscopic, granular and complex geometry materials. DESCRIPTION OF THE INVENTION
La presente invención describe un procedimiento y un dispositivo para la medición del volumen de objetos de materiales higroscópicos con geometría compleja mediante sistema neumático. The present invention describes a method and a device for measuring the volume of objects of hygroscopic materials with complex geometry by pneumatic system.
Se entiende por material higroscópico todo aquel que es capaz de absorber líquidos en su seno, pudiendo o no variar su volumen en este proceso dependiendo del tipo de material y de su contenido en humedad, como por ejemplo la madera. Hygroscopic material is understood as any one that is capable of absorbing liquids in its breast, its volume may or may not vary in this process depending on the type of material and its moisture content, such as wood.
Se entiende por objeto de geometría compleja aquel que, debido a la irregularidad de su superficie, no puede ser asimilado a una figura geométrica que permita la estimación sencilla de su volumen en base a sus dimensiones. Se entiende por sistema neumático aquel que se basa en el uso del aire comprimido. The object of complex geometry is understood to be that which, due to the irregularity of its surface, cannot be assimilated to a geometric figure that allows the simple estimation of its volume based on its dimensions. A pneumatic system is understood as the one based on the use of compressed air.
La presente invención describe un procedimiento, que comprende las siguientes etapas: a) Alojamiento del objeto de material higroscópico de geometría compleja (1) en el recipiente (9) de la cámara de medida (2). El recipiente (9) tiene diámetro menor que la cámara de medida (2), de forma que no impide la entrada de aire a presión desde el calderín (6) a todas las partes de la cámara de medida (2), pero evita que la incorporación brusca de ese aire produzca una alteración o arrastres de las partes mas finas del objeto a medir; el recipiente (9) tiene la función de facilitar el llenado de material en la cámara de medida (2) para la medición de su volumen y evitar que se produzcan arrastres de material fino del objeto a medir que puedan depositarse en el fondo de la cámara de medida (2), pudiendo ocupar volumen que afecte a la medición del siguiente objeto en el caso de no ser retirado convenientemente. b) Cierre hermético de la cámara de medida (2) mediante un cierre tipo brida que asegure su estanqueidad durante todo el proceso. c) Medición con el transductor de presión absoluta (3) y registro manual o automatizado mediante un ordenador, de la presión (PQ) en la cámara de medida (2) con las llaves de paso (4) y (5) cerradas, lo cual se representa en la Fig. 3, donde n2 moles de aire están contenidos en la cámara de medida (2). d) Incorporación de aire en el calderín (6) mediante la apertura de la llave de paso (7) y cierre de la misma cuando se alcance la presión de trabajo, la cual se regulará mediante el sistema regulador de presión (10). e) Medición con el transductor de presión absoluta (8) y registro, manual o automatizado mediante un ordenador, de la presión (P^) en el calderín (6) con las llaves de paso (5) y (7) cerradas, lo cual se representa en la Fig. 3, donde r?1 moles de aire están contenidos en el calderín (6). f) Apertura de la llave de paso (5) que comunica la cámara de medida (2) y el calderín (6). g) Medición con el transductor de presión absoluta (8) y registro manual o automatizado mediante un ordenador, de la presión de equilibrio (P2) que se alcanza en la cámara de medida (2) y el calderín (6) cuando
Figure imgf000007_0001
moles de aire ocupan el volumen V^+ V2+ V||, siendo estos el volumen del calderín (6), la cámara de medida (2) y el que ocupaba el elemento de cierre de la llave de paso (5) en la posición de cerrado en el conducto que comunica la cámara de medida (2) y el calderín (6) respectivamente, como se muestra en la Fig. 2, con las llaves de paso (4) y (7) cerradas, lo cual se muestra en la Fig. 5. h) Determinación del volumen del objeto a medir (1 ). i) Cierre de la llave de paso (5). j) Despresurización de la cámara de medida (2) mediante la llave de paso (4) que la comunica con el exterior, terminando de esta forma un ciclo de medición. k) Apertura de la cámara de medida (2) y retirada del recipiente (9) que contiene el objeto a medir (1). I) En todos los casos será necesario hacer una purga que elimine los vapores de humedad que pudiera provocar el propio material sobre el que se esté efectuando la medición, la cual se realizará operando el dispositivo mediante los pasos a) - j) descritos en el procedimiento de medición, sin ser necesario efectuar las mediciones descritas en los apartados c), e) y g); una vez terminada la purga, se procederá a la medición mediante el inicio de la secuencia de operaciones descrita anteriormente. Este proceso sirve igualmente para uniformizar la temperatura en todas las partes del dispositivo. The present invention describes a process, comprising the following steps: a) Housing the object of hygroscopic material of complex geometry (1) in the container (9) of the measuring chamber (2). The container (9) has a smaller diameter than the measuring chamber (2), so that it does not prevent the entry of pressurized air from the boiler (6) to all parts of the measuring chamber (2), but prevents the abrupt incorporation of that air produces an alteration or dragging of the finest parts of the object to be measured; The container (9) has the function of facilitating the filling of material in the measuring chamber (2) for the measurement of its volume and preventing the occurrence of trawls of fine material of the object to be measured that can be deposited in the bottom of the chamber of measurement (2), being able to occupy volume that affects the measurement of the following object in the case of not being conveniently removed. b) Airtight closure of the measuring chamber (2) by means of a flange type closure that ensures its tightness throughout the process. c) Measurement with the absolute pressure transducer (3) and manual or automated recording by means of a computer of the pressure (P Q ) in the measuring chamber (2) with the stopcocks (4) and (5) closed, which is represented in Fig. 3, where n 2 moles of air are contained in the measuring chamber (2). d) Incorporation of air into the boiler (6) by opening the stopcock (7) and closing it when the working pressure is reached, which will be regulated by the pressure regulating system (10). e) Measurement with the absolute pressure transducer (8) and record, manually or automated by means of a computer, of the pressure (P ^) in the boiler (6) with the stopcocks (5) and (7) closed, which is represented in Fig. 3, where r? 1 mole of air is contained in the boiler (6). f) Opening of the stopcock (5) that communicates the measuring chamber (2) and the boiler (6). g) Measurement with the absolute pressure transducer (8) and manual or automated recording by means of a computer of the equilibrium pressure (P 2 ) reached in the measuring chamber (2) and the boiler (6) when
Figure imgf000007_0001
moles of air occupy the volume V ^ + V2 + V ||, these being the volume of the boiler (6), the measuring chamber (2) and the one that occupied the closing element of the stopcock (5) in the position closed in the conduit that communicates the measuring chamber (2) and the boiler (6) respectively, as shown in Fig. 2, with the stopcocks (4) and (7) closed, which is shown in Fig. 5. h) Determination of the volume of the object to be measured (1). i) Close the stopcock (5). j) Depressurization of the measuring chamber (2) by means of the stopcock (4) that communicates it with the outside, thus completing a measurement cycle. k) Opening of the measuring chamber (2) and removal of the container (9) containing the object to be measured (1). I) In all cases it will be necessary to carry out a purge that eliminates moisture vapors that could be caused by the material itself on which the measurement is being carried out, which will be carried out by operating the device through steps a) - j) described in the measurement procedure, without being necessary to carry out the measurements described in sections c), e) and g); Once the purge is finished, the measurement will proceed by starting the sequence of operations described above. This process also serves to standardize the temperature in all parts of the device.
En todo el documento, Ρ es la presión medida según la fase e) del ciclo de medición, P2 es la presión medida según la fase g) del ciclo de medición, P0 es la presión medida según la fase c) del ciclo de medición, V, es el volumen útil del calderín (6) con las llaves de paso (5) y (6) cerradas, V2 es el volumen útil de la cámara de medida (2) con las llaves de paso (4) y (5) cerradas y considerando el recipiente interior (9), y V,, es el volumen que desplaza el mecanismo de la llave de paso (5) en su apertura y cierre en la tubería que conecta la cámara de medida (2) con el calderín (6), según se muestra en la Fig. 2. Throughout the document, Ρ is the pressure measured according to phase e) of the measuring cycle, P 2 is the pressure measured according to phase g) of the measuring cycle, P 0 is the pressure measured according to phase c) of the measuring cycle measurement, V, is the useful volume of the boiler (6) with the stopcocks (5) and (6) closed, V 2 is the useful volume of the measuring chamber (2) with the stopcocks (4) and (5) closed and considering the inner container (9), and V ,, is the volume that displaces the mechanism of the stopcock (5) in its opening and closing in the pipe that connects the measuring chamber (2) with the boiler (6), as shown in Fig. 2.
Según la invención, el mecanismo de cierre de la llave de paso (5) ha de ser macizo, de forma que no permita la acumulación de aire a presión en su seno entre dos ciclos de medición. De esta forma, el volumen que ocupa el mecanismo de cierre (V,,) en la conducción entre la cámara de medida (2) y el calderín (6), puede ser ocupado por aire a presión P2 en el momento de la apertura de la llave de paso (5) en la fase f) del ciclo de medición. Se entiende por ciclo de medición a todas las operaciones necesarias para la medición del volumen sobre el mismo objeto, pudiendo haber más de un ciclo de medición sobre el mismo objeto, tanto por la carga de nuevo del calderín (6) con aire hasta la presión de trabajo después del primer ciclo de medición, como por el uso de la presión P2 en el calderín (6) después del primer ciclo de medición como presión Pi en el segundo ciclo de medición (P2 1er
Figure imgf000008_0001
2o ciclo), hasta el ciclo de medición n en el que la presión del calderín (6) Pi esté por debajo del umbral que permita estimar el volumen del objeto con la precisión deseada (PMIN), como se muestra en la Fig. 6. De esta forma, habrá tantas mediciones de volumen sobre el objeto como ciclos de medición sobre el mismo. Previo a cualquier ciclo de medición sobre un objeto, es necesario someter al sistema a la purga descrita anteriormente. According to the invention, the closing mechanism of the stopcock (5) must be solid, so as not to allow the accumulation of pressurized air within it between two measurement cycles. In this way, the volume occupied by the closing mechanism (V ,,) in the conduction between the measuring chamber (2) and the boiler (6), can be occupied by pressurized air P 2 at the time of opening of the stopcock (5) in phase f) of the measurement cycle. Measuring cycle is understood as all the operations necessary for measuring the volume on the same object, and there may be more than one measuring cycle on the same object, both by reloading the boiler (6) with air up to the pressure working after the first measurement cycle, such as by the use of pressure P 2 in the boiler (6) after the first measurement cycle as pressure Pi in the second measurement cycle (P 2 1 st
Figure imgf000008_0001
2nd cycle), until the measurement cycle n in the pressure reboiler (6) Pi is below the threshold to estimate the volume of the object with the desired accuracy (P M IN), as shown in Fig 6. In this way, there will be as many volume measurements on the object as there are measurement cycles on the object. same. Prior to any measurement cycle on an object, it is necessary to subject the system to the purge described above.
Varios ciclos de medición sobre el mismo objeto darán lugar a la misma estimación del volumen (v) del objeto a medir (1), siempre y cuando su material no se vea comprimido por efecto de la presión que se alcanza en la cámara de medida en alguna de las fases de la medición. Por ello, se establece la presión máxima de trabajo (PMAX) como aquel valor de que, suponiendo que el material ocupa todo el volumen destinado para su alojamiento en el recipiente (9) vn de la cámara de medida (2), la presión P2 que se alcanza en el volumen \/ + \/2+\/u al abrir la llave de paso (5) no produce mermas de volumen significativas en el objeto a medir, como se muestra en la Fig. 6. Se establece igualmente la presión mínima de trabajo (PMIN) como aquel valor de Pi que permite la medición del volumen (v) en el objeto (1) con la suficiente precisión, como se muestra en la Fig. 6. Several measurement cycles on the same object will give rise to the same estimate of the volume (v) of the object to be measured (1), as long as its material is not compressed due to the pressure reached in the measuring chamber in Some of the phases of the measurement. Therefore, the maximum working pressure (P M AX) is established as that value, assuming that the material occupies the entire volume destined for its accommodation in the container (9) v n of the measuring chamber (2), The pressure P 2 that is reached in the volume \ / + \ / 2 + \ / u when opening the stopcock (5) does not produce significant volume losses in the object to be measured, as shown in Fig. 6. The minimum working pressure (P M IN) is also set as that value of Pi that allows the measurement of the volume (v) in the object (1) with sufficient precision, as shown in Fig. 6.
La medición del volumen del objeto a medir (v) que constituye la fase h) del ciclo de The measurement of the volume of the object to be measured (v) that constitutes phase h) of the cycle of
(ρ1 -ρ2)- ν1 +(ρΰ -ρ2)- ν2 -ρ2 .νιι medición es determinada en base a la expresión (ρ 1 -ρ 2 ) - ν 1 + (ρ ΰ -ρ 2 ) - ν 2 -ρ 2 .ν ιι measurement is determined based on the expression
P - P  P - P
que se deduce de que el número total de moles nt0^^+n2 de aire que hay en la cámara de medida (2) y en el calderín (6) en la fase del ciclo de medición e), y que se representa en la Fig. 3, puede ser calculado mediante la expres■ió■n nx + n2 =— ΡΛ—- ^Λ -— + Pn-- ty^? -v) '- = nT0T , which follows that the total number of moles n t0 ^^ + n 2 of air in the measuring chamber (2) and in the boiler (6) in the phase of the measuring cycle e), and represented in Fig. 3, can it be calculated by the expression ■ io ■ nn x + n 2 = - ΡΛ—- ^ Λ -— + Pn-- ty ^? -v) '- = n T0T ,
R · T  R · T
en aplicación de la teoría cinética de los gases ideales al encontrarse la cámara de medida (2) y el calderín (6) a la misma temperatura T. Si los ntot moles de aire estuvieran contenidos en el calderín (6), situación que se esquematiza en la Fig. 4, la presión teórica n el calderín (6) en ese caso sería
Figure imgf000009_0001
in application of the kinetic theory of ideal gases to meet the measuring chamber (2) and the cylinder (6) at the same temperature T. If n to t moles air were contained in the boiler (6), situation is schematized in Fig. 4, the theoretical pressure n the boiler (6) in that case would be
Figure imgf000009_0001
teoría cinética de los gases ideales. Cuando los ntot moles de gas ocupan el volumen útil al abrir la llave de paso (5) en la fase g) del ciclo de medición, situación que se muestra en la Fig. 5, se cumple la relación P -V1 = P2 ■(yi + V2 + V„ -v) en aplicación de laKinetic theory of ideal gases. When n t moles of gas to occupy the working volume when opening the stopcock (5) in step g) the measurement cycle, situation shown in Fig. 5, the P -V 1 is met = P 2 ■ (and i + V 2 + V „-v) in application of the
Ley de Boyle Mariotte, lo que permite al despejar obtener el volumen (v) del objeto a medir. Boyle Mariotte's Law, which allows clearing to obtain the volume (v) of the object to be measured.
El aire incorporado al calderín (6) en la fase d) del ciclo de medición ha de ir libre de humedad, aceite o partículas, de forma que éstos no ocupen volumen útil del calderín (6) o de la cámara de medida (2), de manera que los volúmenes y V2 que pueden ser ocupados por aire en las distintas fases de la medición y que se esquematizan en la Fig. 2 se mantengan invariantes para varios ciclos de medición sobre el mismo objeto, sin menoscabo de que el volumen útil V2 de la cámara de medida (2) pueda ser variado mediante el uso de sólidos de volumen conocido para aumentar el factor de llenado, aumentando de esta forma la precisión en la medición del volumen. The air incorporated into the boiler (6) in phase d) of the measuring cycle must be free of moisture, oil or particles, so that they do not occupy useful volume of the boiler (6) or the measuring chamber (2) , so that the volumes and V 2 that can be occupied by air in the different phases of the measurement and which are schematized in Fig. 2 remain invariant for several measurement cycles on the same object, without prejudice that the useful volume V 2 of the measuring chamber (2) can be varied by using solids of known volume to increase the filling factor, thereby increasing the accuracy in measuring the volume.
Queda dentro del alcance de la invención que la cámara de medida (2) sea de geometría variable, refiriéndose esto a que parte del volumen de la misma pueda ser ocupado por un objeto de volumen conocido v0Bj, que sumado al volumen (v) del objeto a medir (1) suponga que ambos ocupen una mayor proporción del volumen útil V2 de la cámara de medida (2) -factor de llenado-, aumentando de esta forma la variación en la presión P2 que supone una variación positiva o negativa de volumen dv del volumen ocupado por v+v0Bj en la cámara de medida (2), permitiendo de esta forma incrementar la precisión en la medición del volumen manteniendo constante la sensibilidad de los transductores de presión absoluta (3) y (8). El volumen medido de esta forma en la fase de medición h) sería la suma del volumen del objeto a medir (v) y el volumen conocido (VOBJ) del objeto empleado para reducir el volumen útil de la cámara de medida (2). El volumen del objeto V0BJ empleado para este fin no ha de presentar mermas en el proceso de medición. It is within the scope of the invention that the measuring chamber (2) is of variable geometry, this referring to that part of the volume thereof can be occupied by an object of known volume v 0B j, which added to the volume (v) measuring object (1) assume that both occupy a greater proportion of the useful volume V 2 of the measuring chamber (2) Liquid Fill -factor, thereby increasing the variation in the pressure P 2 which is a positive variation or volume negative dv of the volume occupied by v + v 0B j in the measuring chamber (2), thus allowing to increase the precision in the volume measurement while maintaining the sensitivity of the absolute pressure transducers (3) and (8) ). The volume measured in this way in the measurement phase h) would be the sum of the volume of the object to be measured (v) and the known volume (VOBJ) of the object used to reduce the useful volume of the measuring chamber (2). The volume of the object V 0 BJ used for this purpose must not reduce the measurement process.
El aire incorporado al calderín (6) en la fase d) del ciclo de medición ha de estar a la misma temperatura que la que se encuentra todo el equipo -temperatura de trabajo en laboratorio-, de forma que sea de aplicación la teoría cinética de los gases ideales y el principio de Boyle-Mariotte, por lo que el secador de aire por enfriamiento (17) ha de elevar la temperatura del aire a su salida hasta la temperatura de trabajo a la que se encuentra todo el equipo. Otro aspecto de la presente invención es un dispositivo para la medición de volumen en materiales higroscópicos de geometría compleja mediante sistema neumático, caracterizado por los siguientes elementos que se muestran en la Fig. 1 : a) Una cámara de medida hermética (2) de volumen útil conocido V2 con las llaves de paso (4) y (5) cerradas, la cual lleva incorporado un transductor de presión absoluta (3) para la medición de la presión (P0) una vez se ha introducido el objeto a medir (1) y cerrado la cámara de medida (2), un recipiente interior (9) para alojar el objeto a medir (1), y un sistema de eliminación de líquidos (13). b) Un calderín (6) para el almacenamiento de aire a presión de volumen útil conocido V^ con las llaves de paso (5) y (7) cerradas, y que lleva incorporado un transductor de presión absoluta (8) para la medición de las presiones y P2, un sistema de eliminación de líquidos (14), y una válvula de seguridad (19) que protege al sistema frente sobrepresiones. c) Una tubería de conexión entre la cámara de medida (2) y el calderín (6), con una llave de paso (5) que controla el paso de aire. El sistema de cierre de la llave de paso (5) no permite la acumulación de aire en su seno en el procedimiento de apertura y cierre, y el punto de inserción de la conducción con la cámara de medida (2) es no superior a ¼ de la altura del recipiente interior (9), de forma que la entrada brusca de aire a presión en la cámara de medida (2) procedente del calderín (6) en la fase f) del ciclo de medición no afecte directamente al objeto a medir (1) más allá del incremento de la presión que se produce en la cámara de medida (2). d) Un sistema regulador de presión (10) de carga del calderín (6), situado fuera de éste en una posición inmediatamente anterior a la llave de paso (7) con respecto al compresor (11), caracterizado por que consta de una válvula reguladora de presión (15) y una válvula antirretorno calibrada (16). La válvula reguladora de presión (15) permitirá que el suministro de aire a presión procedente del compresor (11) se corte en el momento en el que la presión en el calderín (6) alcance el valor deseado de la presión de trabajo P^, la cual será medida con precisión con el transductor de presión absoluta (8) después de cerrar la llave de paso (7) en la fase e) del ciclo de medición. La válvula antirretorno calibrada (16) evitará el paso de aire en dirección contraria a la de funcionamiento en el caso de que se opere en el sistema de eliminación de aceite, humedad y sólidos (12) con la llave de paso (7) abierta y el compresor (11) apagado. e) Un sistema de eliminación de aceite, humedad y sólidos (12) en el aire incorporado al calderín (6), situado entre el compresor (11) y el sistema regulador de presión en el calderín (10), caracterizado porque consta de un purgador automático con filtro (18), y de un secador de aire por enfriamiento (17). El secador de aire por enfriamiento (17) ha de elevar la temperatura del aire hasta la temperatura de operación en laboratorio para asegurar que sea de aplicación la teoría cinética de los gases ideales y el principio de Boyle-Mariotte, y el caudal de aire máximo de trabajo ha de ser superior al de funcionamiento del compresor (11), de forma que se asegure un secado eficiente del aire. f) Un compresor (11), con una presión mínima de trabajo de 8 bar. Los sistemas de eliminación de líquidos (13) y (14) tienen por función el permitir la eliminación de acumulación de agua en la cámara de medida (2) o calderín (6) en el proceso de mantenimiento. The air incorporated into the boiler (6) in phase d) of the measurement cycle must be at the same temperature as that of all the equipment - working temperature in the laboratory - so that the kinetic theory of the ideal gases and the Boyle-Mariotte principle, so that the cooling air dryer (17) must raise the temperature of the air at its outlet to the working temperature at which all the equipment is located. Another aspect of the present invention is a device for measuring volume in hygroscopic materials of complex geometry by pneumatic system, characterized by the following elements shown in Fig. 1: a) A hermetic measuring chamber (2) of volume known tool V 2 with the stopcocks (4) and (5) closed, which incorporates an absolute pressure transducer (3) for pressure measurement (P 0 ) once the object to be measured has been introduced ( 1) and closed the measuring chamber (2), an inner container (9) to house the object to be measured (1), and a liquid removal system (13). b) A boiler (6) for the storage of air at pressure of known useful volume V ^ with the stopcocks (5) and (7) closed, and incorporating an absolute pressure transducer (8) for the measurement of pressures and P 2 , a liquid elimination system (14), and a safety valve (19) that protects the system against overpressures. c) A connection pipe between the measuring chamber (2) and the boiler (6), with a stopcock (5) that controls the air passage. The closing system of the stopcock (5) does not allow the accumulation of air inside the opening and closing procedure, and the insertion point of the conduction with the measuring chamber (2) is not more than ¼ of the height of the inner vessel (9), so that the sudden entry of pressurized air into the measuring chamber (2) from the boiler (6) in phase f) of the measuring cycle does not directly affect the object to be measured (1) beyond the increase in pressure that occurs in the measuring chamber (2). d) A pressure regulating system (10) for loading the boiler (6), located outside it in a position immediately before the stopcock (7) with respect to the compressor (11), characterized in that it consists of a valve pressure regulator (15) and a calibrated non-return valve (16). The pressure regulating valve (15) will allow the supply of pressurized air from the compressor (11) to be cut off at the moment when the pressure in the boiler (6) reaches the desired value of the working pressure P ^, which will be accurately measured with the absolute pressure transducer (8) after closing the stopcock (7) in phase e) of the measurement cycle. The calibrated non-return valve (16) will prevent the passage of air in the opposite direction to that of operation in the event that it is operated in the oil, moisture and solids removal system (12) with the stopcock (7) open and the compressor (11) off. e) An oil, moisture and solids removal system (12) in the air incorporated into the boiler (6), located between the compressor (11) and the pressure regulating system in the boiler (10), characterized in that it consists of a automatic drain with filter (18), and a cooling air dryer (17). The cooling air dryer (17) must raise the air temperature to the operating temperature in the laboratory to ensure that the kinetic theory of the ideal gases and the Boyle-Mariotte principle, and the maximum air flow rate, apply of work must be superior to the operation of the compressor (11), so as to ensure efficient air drying. f) A compressor (11), with a minimum working pressure of 8 bar. The liquid elimination systems (13) and (14) have the function of allowing the elimination of water accumulation in the measuring chamber (2) or boiler (6) in the maintenance process.
Todos aquellos elementos comprendidos entre las llaves de paso (4) y (7), que son la cámara de medida (2), el calderín (6) y el conducto que los comunica han de ser rígidos, de forma que no han de ver variado su volumen con las presiones a las que se encuentran sometidos en el ciclo de medición, de forma que los volúmenes y V2 permanezcan constantes. El material de todos los componentes ha de presentar una elevada conductividad térmica, como por ejemplo el acero, de forma que se favorezca la disipación del calor y la permanencia de todo el equipo a la temperatura de suministro de aire después de su tratamiento en el sistema de limpieza (12), que será igual a la temperatura ambiente. All those elements between the stopcocks (4) and (7), which are the measuring chamber (2), the boiler (6) and the conduit that communicates them must be rigid, so that they must not see its volume varied with the pressures to which they are subjected in the measurement cycle, so that the volumes and V 2 remain constant. The material of all components must have a high thermal conductivity, such as steel, so that heat dissipation and the permanence of all equipment at the air supply temperature is favored after treatment in the system cleaning (12), which will be equal to room temperature.
BREVE DESCRIPCIÓN DE LAS FIGURAS Para facilitar la comprensión de la invención, se describen las figuras en las que se ha representado, a titulo de ejemplo ilustrativo y no limitativo, un caso de realización de dispositivo para la medición de volumen en materiales higroscópicos de geometría compleja mediante sistema neumático. BRIEF DESCRIPTION OF THE FIGURES To facilitate the understanding of the invention, the figures are described in which, by way of illustrative and non-limiting example, a device embodiment for volume measurement in hygroscopic materials of complex geometry has been depicted by pneumatic system.
La figura 1 representa el esquema general del dispositivo, caracterizado por una cámara de medida (2), un calderín (6), un dispositivo para el control de la presión de carga en el calderín (10), un dispositivo para la eliminación de aceite, humedad y sólidos en el aire (12), un compresor (11) y tres llaves de paso (4), (5) y (7). Figure 1 represents the general scheme of the device, characterized by a measuring chamber (2), a boiler (6), a device for controlling the loading pressure in the boiler (10), a device for oil removal , moisture and solids in the air (12), a compressor (11) and three stopcocks (4), (5) and (7).
La figura 2 representa el volumen de las distintas partes del dispositivo (V^ , V2, ¼), que son fundamentales para la estimación del volumen (v) del objeto a medir (1). La figura 3 representa el dispositivo en la fase e) del ciclo de medición. Figure 2 represents the volume of the different parts of the device (V ^, V 2 , ¼), which are fundamental for the estimation of the volume (v) of the object to be measured (1). Figure 3 represents the device in phase e) of the measurement cycle.
La figura 4 representa la situación teórica que se alcanzaría si ηΜ=η +η2 moles de aire estuvieran contenidos en el calderín (6), y la presión P que se alcanzaría en ese caso. Figure 4 represents the theoretical situation that would be reached if η Μ = η + η 2 moles of air were contained in the boiler (6), and the pressure P that would be reached in that case.
La figura 5 representa el dispositivo en la fase g) del ciclo de medición. La figura 6 representa la relación entre las presiones P^ y P2 que se alcanzaría en el dispositivo en el proceso de medición, acotado por Vmax, situación teórica en el caso de que el objeto a medir ocupara por completo el volumen V2 en la cámara de medida (2), y VQ en el caso de que se opere con el dispositivo sin objeto (1) en la cámara de medida (2). Figure 5 represents the device in phase g) of the measurement cycle. Figure 6 represents the relationship between the pressures P ^ and P 2 that would be reached in the device in the measurement process, bounded by V max , theoretical situation in the case of that the object to be measured completely occupies the volume V 2 in the measuring chamber (2), and V Q in the event that it is operated with the device without an object (1) in the measuring chamber (2).

Claims

REIVINDICACIONES
1. Un procedimiento para la medición de volumen en materiales higroscópicos de geometría compleja mediante sistema neumático, que comprende las siguientes etapas:  1. A procedure for measuring volume in hygroscopic materials of complex geometry by means of a pneumatic system, comprising the following steps:
a) alojamiento del objeto de material higroscópico de geometría compleja (1) en la cámara de medida (2);  a) housing the hygroscopic object of complex geometry (1) in the measuring chamber (2);
b) cierre hermético de la cámara de medida (2);  b) airtight closure of the measuring chamber (2);
c) medición y registro de la presión (P0) con el transductor de presión absoluta (3) en la cámara de medida (2) con las llaves de paso (4) y (5) cerradas, c) measuring and recording the pressure (P 0 ) with the absolute pressure transducer (3) in the measuring chamber (2) with the stopcocks (4) and (5) closed,
d) incorporación de aire en el calderín (6) mediante la apertura de la llave de paso (7) y cierre de la misma cuando se alcance la presión de trabajo; e) medición y registro de la presión ( i) en el calderín (6) con el transductor de presión absoluta (8) con las llaves de paso (5) y (7) cerradas; f) apertura de la llave de paso (5) que comunica la cámara de medida (2) y el calderín (6);  d) incorporation of air into the boiler (6) by opening the stopcock (7) and closing it when the working pressure is reached; e) measuring and recording the pressure (i) in the boiler (6) with the absolute pressure transducer (8) with the stopcocks (5) and (7) closed; f) opening the stopcock (5) that communicates the measuring chamber (2) and the boiler (6);
g) medición y registro de la presión de equilibrio (P2) en la cámara de medida (2) y el calderín (6) con el transductor de presión absoluta (8); g) measurement and recording of the equilibrium pressure (P 2 ) in the measuring chamber (2) and the boiler (6) with the absolute pressure transducer (8);
h) determinación del volumen del objeto a medir (1), caracterizado porque el volumen del objeto a medir (v) es determinado en base a la expresión v =— (Pl—- P2—)—- Vl -—+ (—P0—- P2—)—- V2 -—- P2 -—- Vl -l , donde Ρ π es la presión medida según la reivindicación 1 , apartado e), P2 es la presión medida según la reivindicación 1 , apartado g), PQ es la presión medida según la reivindicación 1 , apartado c), es el volumen útil del calderín (6) con las llaves de paso (5) y (6) cerradas, V2 es el volumen útil de la cámara de medida (2) con las llaves de paso (4) y (5) cerradas y considerando el recipiente interior (9), y Vn es el volumen que desplaza el mecanismo de la llave de paso (5) en su apertura y cierre en la tubería que conecta la cámara de medida (2) con el calderín (6); h) determination of the volume of the object to be measured (1), characterized in that the volume of the object to be measured (v) is determined based on the expression v = - ( P l—- P 2 -) —- V l -— + (- P 0—- P 2 -) —- V 2 -—- P 2 -—- V l -l, where Ρ π is the pressure measured according to claim 1, section e), P 2 is the pressure measured according to claim 1, section g), P Q is the pressure measured according to claim 1, section c), is the useful volume of the boiler (6) with the stopcocks (5) and (6) closed, V 2 is the useful volume of the measuring chamber (2) with the stopcocks (4) and (5) closed and considering the inner vessel (9), and V n is the volume that displaces the mechanism of the stopcock (5) in its opening and closing in the pipe that connects the measuring chamber (2) with the boiler (6);
i) cierre de la llave de paso (5);  i) closing the stopcock (5);
j) despresurización de la cámara de medida (2) mediante la llave de paso (4) que la comunica con el exterior;  j) depressurization of the measuring chamber (2) by means of the stopcock (4) that communicates it with the outside;
k) apertura de la cámara de medida (2) y retirada del recipiente (9) que contiene al objeto a medir (1); y I) purga de los vapores de humedad del objeto sobre el que se efectúa la medición (1) previo a la realización de las medidas de presión descritas en las etapas c), e) y g). k) opening of the measuring chamber (2) and removal of the container (9) containing the object to be measured (1); Y I) purging the moisture vapors of the object on which the measurement is made (1) prior to carrying out the pressure measurements described in steps c), e) and g).
2. El procedimiento según la reivindicación 1 , en el que el apartado a), está caracterizado porque el objeto a medir (1) es depositado en un recipiente interior (9) a la cámara de medida (2), de diámetro menor que la cámara de medida.  2. The method according to claim 1, wherein section a) is characterized in that the object to be measured (1) is deposited in an inner container (9) to the measuring chamber (2), of smaller diameter than the measuring chamber
3. El procedimiento según la reivindicación 1 , en el que el apartado d), está caracterizado porque el aire incorporado al calderín (6) ha de ir libre de humedad, aceite o partículas.  3. The method according to claim 1, wherein section d) is characterized in that the air incorporated into the boiler (6) must be free of moisture, oil or particles.
4. El procedimiento, según la reivindicación 1 , en el que el apartado d), está caracterizado por que el secador de aire por enfriamiento (17) que procesa el aire incorporado al calderín (6) eleva la temperatura del aire hasta la temperatura de operación en laboratorio.  4. The method according to claim 1, wherein section d) is characterized in that the cooling air dryer (17) that processes the air incorporated into the boiler (6) raises the temperature of the air to the temperature of Laboratory operation
5. El procedimiento según la reivindicación 1 , en el que el apartado g), está caracterizado porque el mecanismo de cierre de la llave de paso (5) ha de ser macizo.  5. The method according to claim 1, wherein section g) is characterized in that the locking mechanism of the stopcock (5) has to be solid.
6. Un dispositivo para la medición de volumen mediante sistema neumático en materiales higroscópicos de geometría compleja, caracterizado por los siguientes elementos:  6. A device for measuring volume by means of a pneumatic system in hygroscopic materials of complex geometry, characterized by the following elements:
a) una cámara de medida hermética (2) de volumen conocido V2 con las llaves de paso (4) y (5) cerradas, donde la cámara de medida (2) lleva incorporado: un transductor de presión absoluta (3) para la medición de la presión (P0) una vez se ha introducido el objeto a medir y cerrado la cámara de medida (2), un recipiente interior (9) para alojar el objeto a medir (1), y un sistema de eliminación de líquidos (13); a) a hermetic measuring chamber (2) of known volume V 2 with the stopcocks (4) and (5) closed, where the measuring chamber (2) is incorporated: an absolute pressure transducer (3) for Pressure measurement (P 0 ) once the object to be measured has been introduced and the measuring chamber (2), an inner container (9) to house the object to be measured (1), and a liquid removal system have been closed (13);
b) un calderín (6) para el almacenamiento de aire a presión de volumen conocido V con las llaves de paso (5) y (7) cerradas, donde el calderín (6) lleva incorporado un transductor de presión absoluta (8) para la medición de las presiones Ρ y P2, y un sistema de eliminación de líquidos (14); c) una tubería de conexión entre la cámara de medida (2) y el calderín (6), con una llave de paso (5) que controla el paso de aire, donde el mecanismo de apertura y cierre de la llave de paso (5) ha de ser macizo, y donde el volumen de aire que desplaza la llave de paso (5) en su apertura y cierre tenga un volumen conocido V,,; d) un sistema regulador de presión (10) de carga del calderín (6), situado fuera de éste en una posición inmediatamente anterior a la llave de paso (7) con respecto al compresor (1 1); b) a boiler (6) for the storage of pressurized air of known volume V with the stopcocks (5) and (7) closed, where the boiler (6) incorporates an absolute pressure transducer (8) for measurement of pressures Ρ and P 2 , and a liquid elimination system (14); c) a connection pipe between the measuring chamber (2) and the boiler (6), with a stopcock (5) that controls the air passage, where the opening and closing mechanism of the stopcock (5 ) must be solid, and where the volume of air that moves the stopcock (5) in its opening and closing has a known volume V ,,; d) a pressure regulating system (10) for loading the boiler (6), located outside it in a position immediately before the stopcock (7) with respect to the compressor (1 1);
e) un sistema de eliminación de aceite, humedad y sólidos (12) en el aire incorporado al calderín (6), situado entre el compresor (1 1) y el sistema regulador de presión en el calderín (10); y  e) an oil, moisture and solids removal system (12) in the air incorporated into the boiler (6), located between the compressor (1 1) and the pressure regulating system in the boiler (10); Y
f) un compresor (11).  f) a compressor (11).
7. El dispositivo, según la reivindicación 6, en el que el apartado c), está caracterizado porque el sistema de cierre de la llave de paso (5) no permite la acumulación de aire en su seno en el procedimiento de apertura y cierre, y porque el punto de inserción con la cámara de medida es no superior a ¼ de la altura del recipiente interior (9).  7. The device according to claim 6, wherein section c) is characterized in that the stopcock closure system (5) does not allow the accumulation of air within it in the opening and closing process, and because the insertion point with the measuring chamber is not more than ¼ of the height of the inner container (9).
8. El dispositivo, según la reivindicación 6, en el que el apartado d), está caracterizado por que consta de una válvula reguladora de presión (15) y una válvula antirretorno calibrada (16).  The device according to claim 6, wherein section d) is characterized in that it consists of a pressure regulating valve (15) and a calibrated non-return valve (16).
9. El dispositivo, según la reivindicación 6, en el que el apartado e), está caracterizado porque consta de un purgador automático con filtro (18), y de un secador de aire por enfriamiento (17).  9. The device according to claim 6, wherein section e) is characterized in that it consists of an automatic trap with filter (18), and a cooling air dryer (17).
10. El dispositivo según la reivindicación 6; en el que el apartado e), está caracterizado porque el aire incorporado al calderín (6) está a la misma temperatura que la que se encuentra todo el equipo -temperatura de trabajo en laboratorio-.  10. The device according to claim 6; in which section e), is characterized in that the air incorporated into the boiler (6) is at the same temperature as that found in all the equipment - working temperature in the laboratory.
PCT/ES2013/070405 2012-06-21 2013-06-21 Method and device for measuring the volume of objects made of hygroscopic materials with a complex geometry, by means of a pneumatic system. WO2014057150A1 (en)

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Citations (8)

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Publication number Priority date Publication date Assignee Title
DD265685A1 (en) * 1987-10-30 1989-03-08 Foerdertechnik Freital Veb VOLUME MEASURING DEVICE
JPH04339221A (en) * 1991-05-15 1992-11-26 Toshiba Corp Volume measuring apparatus for cavity in object to be measured
WO1993014383A1 (en) * 1992-01-20 1993-07-22 Ebbe Lindberg Method, plant and system for measuring the solid volume of a load
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EP1271112A2 (en) * 2001-06-21 2003-01-02 National Institute of Advanced Industrial Science and Technology Apparatus for measuring volume under microgravity
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US20100269577A1 (en) * 2007-12-27 2010-10-28 Commissariat A L'energie Atomique Et Aux Energies Alternatives Pycnometer

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD265685A1 (en) * 1987-10-30 1989-03-08 Foerdertechnik Freital Veb VOLUME MEASURING DEVICE
JPH04339221A (en) * 1991-05-15 1992-11-26 Toshiba Corp Volume measuring apparatus for cavity in object to be measured
WO1993014383A1 (en) * 1992-01-20 1993-07-22 Ebbe Lindberg Method, plant and system for measuring the solid volume of a load
JPH09126855A (en) * 1995-11-06 1997-05-16 Ishikawajima Harima Heavy Ind Co Ltd Method for measuring storage volume by gas
EP1271112A2 (en) * 2001-06-21 2003-01-02 National Institute of Advanced Industrial Science and Technology Apparatus for measuring volume under microgravity
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US20100269577A1 (en) * 2007-12-27 2010-10-28 Commissariat A L'energie Atomique Et Aux Energies Alternatives Pycnometer

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