WO2007071825A1 - Measuring suspension - Google Patents
Measuring suspension Download PDFInfo
- Publication number
- WO2007071825A1 WO2007071825A1 PCT/FI2006/050570 FI2006050570W WO2007071825A1 WO 2007071825 A1 WO2007071825 A1 WO 2007071825A1 FI 2006050570 W FI2006050570 W FI 2006050570W WO 2007071825 A1 WO2007071825 A1 WO 2007071825A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- measuring
- sample
- measuring device
- measurement
- suspension
- Prior art date
Links
- 239000000725 suspension Substances 0.000 title claims abstract description 27
- 238000005259 measurement Methods 0.000 claims abstract description 71
- 238000000034 method Methods 0.000 claims abstract description 64
- 239000000126 substance Substances 0.000 claims abstract description 34
- 239000012530 fluid Substances 0.000 claims description 24
- 239000007787 solid Substances 0.000 claims description 19
- 239000002245 particle Substances 0.000 claims description 9
- 238000001514 detection method Methods 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 239000000945 filler Substances 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 5
- 229920002522 Wood fibre Polymers 0.000 claims description 3
- 238000009413 insulation Methods 0.000 claims description 2
- 230000003247 decreasing effect Effects 0.000 abstract description 5
- 238000012545 processing Methods 0.000 description 5
- 238000005070 sampling Methods 0.000 description 5
- 230000001419 dependent effect Effects 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000005611 electricity Effects 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
- 230000035515 penetration Effects 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000013500 data storage Methods 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000001117 sulphuric acid Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/06—Investigating concentration of particle suspensions
-
- 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
- G01N9/24—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by observing the transmission of wave or particle radiation through the material
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/10—Devices for withdrawing samples in the liquid or fluent state
- G01N1/20—Devices for withdrawing samples in the liquid or fluent state for flowing or falling materials
- G01N1/2035—Devices for withdrawing samples in the liquid or fluent state for flowing or falling materials by deviating part of a fluid stream, e.g. by drawing-off or tapping
- G01N2001/2071—Removable sample bottle
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/34—Paper
Definitions
- the invention comprises measuring a suspension which is to be processed in a process and which contains at least one substance to be measured that is mixed into fluid used as a medium.
- filtrate samples are taken from stock for monitoring and controlling a process.
- Stock is a suspension which contains fluid (water), solid particles, such as fibres and possibly shives, fines removed from fibres, fillers, such as kaolin, talc, calcium carbonate or titan oxide, dissolved substances and some gas.
- pulp consistency may be measured by a two-shaft measuring device, for example, where the shafts may rotate with respect to each other.
- the measurement is based on shearing forces and on determining them so that at the end of the measuring shafts, there are various projections whose movement the pulp to be measured tries to decelerate at a force dependent on fibre consistency. Since the device measures the force required to break a fibre network, its result is dependent on the pulp type and fibre length, for instance.
- Pulp may also be measured optically, in which case either penetration measurement is performed on attenuation of light caused by pulp or reflection measurement on scattering of light caused by pulp.
- the result of optical measurement also depends on the pulp type and, in particular, on the filler type as their optical properties vary according to the type.
- the measuring interval must be very small due to strong attenuation of light. For this reason, penetration measurements are not suitable for measuring relatively high consistencies.
- Measuring devices of the above kind are typically fixed in a process pipe system and their operation depends on the process and external sources as they, for example, receive electric power from a public electricity network or an electricity network connected to the process. These measuring devices are conventionally used in continuous measurement of consistency. Due to the fixed installation, price of measuring devices, and changing needs, etc., it is in practice impossible to install continuous measuring devices in all process points where pulp consistency is to be determined. In addition to the measurement by measuring devices, it may be desirable to perform comparison measurements, which are used to calibrate continuous measurements, for instance. For this reason, the process pipe system is further provided with sampling points (samplers). Consistency determination is performed in a laboratory on samples taken from the sampling points in accordance with a standardized method, such as TAPPI T 240 om-93. Such measurement is, however, slow and complicated.
- the object of the invention is to provide an improved method and a measuring device implementing the method. This is achieved by a method of measuring a suspension which is processed in a process and contains fluid as a medium and solid particles mixed into the fluid.
- the method further comprises taking a sample from the suspension in the process into an open measuring space in the measuring device and enclosing the sample in the measuring space; transmitting a radio frequency electromagnetic measuring signal by the transceiver of the measuring device through a portion of a representative sample in the measuring space at least in the vertical direction; performing at least one operation to reduce the influence of gas bubbles on the measurement; measuring sample temperature; determining the relative proportion of solids in the sample by means of the travel time of the measuring signal and the measured temperature in the measuring unit of the measuring device.
- the invention further relates to a measuring device for measuring a suspension, the suspension to be measured being processed in a process and containing fluid as a medium and solid particles mixed into the fluid.
- the measuring device comprises an openable and closable measuring space, and when the measuring space of the measuring device is open, the measuring device is arranged to receive a sample from the suspension in the process into the measuring space; a transceiver which is arranged to transmit a radio frequency electromagnetic measuring signal through a portion of a representative sample in the measuring space in the vertical direction; a gas bubble remover which is arranged to perform at least one operation to reduce the influence of gas bubbles on the measurement; at least one temperature sensor which is arranged to measure sample temperature; a measuring unit which is functionally connected to the transceiver and temperature sensor and arranged to determine the relative proportion of solids in the sample by means of the travel time of the measuring signal and the measured temperature.
- the method and system according to the invention provide several advantages.
- the solution is also independent of pulp types, in which case all different pulp types may be measured by the same calibration. It also enables measuring a sufficiently large pulp sample by one rapid measurement, in which case the measured sample is representative. Since the device may also be portable, it may be taken to the sampling point, where determination may be performed. In that case, it is not necessary to submit a plurality of samples to a laboratory for consistency determination.
- Figure 1A illustrates a measuring device
- Figure 1B illustrates a measuring space of the measuring device
- Figure 2 illustrates sampling from a process pipe
- Figure 3 illustrates sampling from a container
- Figure 4 is a flow chart illustrating a method of measuring a suspension.
- the presented solution may be applied, for example, in the wood processing industry or in industries involved in environment maintenance, such as purification of waste water, but the solution is not limited to these.
- FIG. 1A illustrates a feasible implementation of a measuring device.
- the measuring device 100 comprises a measuring space 102, where a sample from a suspension in a process may be taken.
- the measuring space 102 may consist of a space defined inside the measuring device by its walls 96, bottom 98 and cover 104.
- the measuring space 102 is openable and closable, for which purpose the measuring device 100 may comprise an openable and closable cover 104.
- the cover 104 is closed, but the cover illustrated with a broken line illustrates the cover in an open position.
- the measuring device 100 may take a sample from fluid substance in the process or a sample of fluid substance from the process may be fed into the measuring space 102 of the measuring device 100.
- the sample may be suspension which contains at least one of the following raw materials used in the paper, board and pulp industry: fibres (plant fibres, such as wood fibres), filler, fines.
- the sample may also be suspension which contains industrial or municipal waste in water.
- Temperature compensation may be performed for the measurement on the basis of the temperature of the sample to be measured.
- the measuring space 102 may be encased with a thermal insulation or a thermally insulating structure (see Figure 1B) to prevent temperature differences inside the sample due to cooling at the edges in the case of warm or hot samples. Cooling may also be reduced by heating the walls of the measuring space. If temperature differences are generated in the sample, the temperature may be measured by several temperature sensors at different locations to determine the temperature distribution. The sample may also be stirred by a mechanical mixer, for example, to balance temperature differences.
- the measuring space 102 can be closed tightly by closing the cover 104.
- the cover may further be shaped to fit accurately in an opening provided in the measuring device. Tightness may be improved by seals.
- the measuring device comprises a gas bubble remover 106 for reducing the influence of gas bubbles on the measurement.
- the gas bubble remover 106 may be a pressurization device, ultrasonic device, a device for adding fluid that reduces gas bubbles, or a mechanical mixer, which may be the same device as the mixer that balances the temperature or a different one.
- the pressurization device may be used to increase the pressure in the measuring space 102 when the measuring device is closed. The purpose of increasing the pressure is to dissolve the gas contained in the sample in the sample, in which case the dissolved gas does not interfere with the measurement.
- the pressurization device may comprise a compressor for pumping air or gas into the upper part of the measuring device to increase the pressure in the measuring space 102 of the measuring device.
- the pressurization device may be a connector connectable to the pneumatic system of a plant, for example.
- the pressurization device may also be a mechanical arrangement for decreasing the volume of the measuring space through a piston movement, for example, by rotating a lever or a wheel outside the measuring device.
- the pressurization device may also comprise rubber bellows for decreasing the measuring space.
- a carbon dioxide cartridge may be used to increase the pressure. The pressure may be increased higher than e.g. 150 kPa.
- the number of gas bubbles in the sample may be decreased.
- the number of gas bubbles may also be decreased by adding a suitable fluid to the sample.
- the sample may be stirred by a mechanical mixer, which removes at least some of the gas bubbles from the sample.
- Measurement is performed by transmitting a measuring signal through the sample before reducing the number of gas bubbles. Furthermore, the measuring signal may be transmitted through the sample after the number of gas bubbles has been reduced. The number of gas bubbles in the sample may be determined by comparing measurement results.
- the measuring device comprises a transceiver unit 108 and antennas 110 and 112, which transmit and receive a radio frequency electromagnetic measuring signal through the sample in the measuring device 100 in the vertical direction.
- the vertical direction is a preferred measuring direction since any sedimentation of the sample does not affect the measurement. For this reason, there is thus no need to stir the sample during measuring.
- the frequency range of radiation for performing measurement may be 1 to 5 GHz, but frequencies outside these limits are also feasible, for example between 100 MHz and 10 GHz.
- Measurement is performed so that the measuring signal has a vertical component and it penetrates a representative portion of the sample.
- the measuring signal 150 does not need to travel completely in parallel with the earth's gravity field but the measurement signal 150 may also propagate diagonally.
- the measuring signal may propagate from top to bottom or from bottom to top. Representativiness is achieved in the measurement when the measuring signal 150 penetrates the whole or nearly the whole sample in the vertical direction. No specific representativeness is required in the horizontal direction.
- the walls 96, bottom 98 and cover 104 of the measuring space may be thermally insulated, which is illustrated by the thick walls in Figure 1B.
- the transceiver unit 108 generates a radio frequency signal, which may be fed over a cable to a transmitting antenna 110 in the top.
- the transmitting antenna 110 transmits the radio frequency signal from the top through the sample and down to the receiving antenna 112, which transmits the signal it has received back to the transceiver unit 108.
- the transceiver unit 108 generates a measuring signal from the received radio frequency signal and uses it to determine the travel time or phase of the radio frequency signal.
- the transmitting antenna may be in the bottom and the receiving antenna in the top.
- the travel time of the radio frequency signal may be determined by an FMCW technique (Frequency Modulated Continuous Wave), for example, where frequency scanning is transmitted through the substance to be measured to the RF port (Radio Frequency) of the receiver mixer and through the inner signal path of the transmitter to the LO port (Local Oscillator) of the receiver mixer. Since the delay between the measuring path and the internal signal path is not the same, frequency f is obtained from the mixer's IF port. The following holds true for the difference between the delays of the measuring path and the inner signal path
- the phase may also be determined by measuring the phase of one or more dot frequencies that have passed through the measuring path. This may be carried out by a "heterodyne technique", for example, where microwave signals that have passed through the inner signal path and have frequency f1 are converted by their own mixers into frequency f2, in which case the LO port of the mixers outputs a signal whose frequency is f1 to f2 and the phase is proportional to the distance travelled by the microwave signal. Since the distance travelled by the inner signal path is constant, phase changes in the signal that has travelled through the measuring path may be measured by measuring the phase difference between the mixer's IF signal of the measuring path and the mixer's IF signal of the inner signal path.
- the inner signal path may be omitted if signal f2 is generated by a phase lock, which locks the phase of signal f2 to the clock frequency.
- the clock frequency of the phase lock may be used instead of the mixer's IF signal of the inner signal path.
- Measurement may also be performed as a direct travel time measurement by means of a signal pulse by measuring the time between transmitting and receiving a pulse.
- This measuring technique is generally used in surface level measurements, for example, where the distance of the surface causing reflection from the transceiver antenna is measured on the basis of the measured travel time.
- the travel time may also be determined by a correlation technique.
- the object is to find the largest possible correlation by moving signals with respect to each other.
- the extent to which the signals need to be moved with respect to each other in time to obtain the largest possible correlation determines the difference of travel times between the reference measurement (signal that has propagated along the inner signal path, or a constant signal otherwise independent of the measurement) and the actual sample measurement.
- phase measurement does not indicate the number of complete cycle lengths in the measuring path, but this is not even necessary since for calculating consistency, it is sufficient to measure the change in the travel time or phase compared to a known reference point, which is typically the device's calibration point.
- the measuring device may further include at (east one temperature sensor 120, which is functionally connected to the measuring unit 114 for measuring sample temperature.
- the temperature measurement may be useful since the temperature considerably affects the travel time of microwaves in water. The effect of the temperature may be compensated for either on the basis of an experimental or a theoretical model. In a temperature range of 25°C to 100 0 C, a first-order linear model is usually sufficient, whereas in a temperature range below 25 0 C, a multi-order polynomial is usually required due to the non-linear dependence between the travel time and the temperature.
- the measured travel time and temperature are transmitted to the measuring unit 114, which calculates the relative proportion of the substance to be measured in the sample on the basis of measurement results.
- Temperature may be measured by several temperature sensors at several points in the measuring space 102. A temperature distribution may be determined from the measurements and utilized in determining the relative proportion of the substance to be measured in the sample.
- the measuring device may further comprise a detection unit 116, which presents the measurement result of the relative proportion of the substance to be measured in the sample to the user.
- the detection unit 116 may be a display.
- the detection unit 116 may also include a keyboard, mouse or another user interface for feeding data.
- the measuring device may further comprise a power source 118, which feeds electric power into the transceiver, measuring unit, detection unit, gas bubble remover, any compressor, etc., in the measuring device for performing the measurement.
- the power source may be, for example, a dry- cell battery or a battery charged by a power-supply device. If the measuring device has no dedicated power source, it may take the required electric power from a public electricity network, for example.
- the measuring device may comprise a contact component 122 for connecting the measuring device 100 to an external data processing system.
- the contact component 122 may be a mechanical connector to which the counterpart of the data processing system is connected.
- the contact component 122 may also be a transmitter, receiver or transceiver part of a wireless system through which the measuring device communicates with the data processing system.
- the contact component 122 may operate optically, via a radio path, acoustically, inductively or capacita- tively.
- One solution that operates via the radio path is the Bluetooth® technique.
- the measuring device may be connected to an automation system controlling the process, for example.
- the battery of the measuring device may also be charged through the contact component.
- the measuring device may further comprise a handle 124, which facilitates its handling.
- the measuring device may be movable and possibly small enough for carrying by hand.
- the measuring device further comprises a memory 126, where the determined relative proportion of the substance to be measured may be stored. If necessary, the data stored in the memory 126 can be transferred to another data processing system or data storage system through the contact component, for instance.
- the measuring device may be made of metal, plastic or composite. Since the measuring device operates at radio frequencies, it is useful to make the measuring space impermeable to radio frequencies. This way it is possible to avoid external interference in the measurement and to prevent the measuring signal from escaping outside the measuring space.
- the transceiver unit 108 may be arranged to measure, in addition to the travel time, attenuation of electromagnetic radiation in a sample. Since attenuation of microwaves is proportional to the electric conductivity of the sample, the attenuation measurement may be used to determine the sample's conductivity. Conductivity depends on the amount of electrically charged substances that have dissolved in the fluid substance. In particular, different bases, acids and salts, such as sodium hydroxide and sulphuric acid, produce conductivity-increasing ions in the fluid substance.
- Model parameters may be determined using experimental measurements, although they may also be determined on the basis of dielectricity constants found in the literature, provided that sufficiently accurate values are available for a sufficiently wide temperature range.
- the model parameters are substance specific, and when a good accuracy is desirable, they may be determined separately for each substance to be measured.
- the model parameters may also be specified on the basis of follow-up results.
- conductivity can be determined by feeding the measured attenuation of microwaves and possibly also the temperature into the model.
- Figure 2 illustrates filling of a measuring device through a process pipe.
- the fluid substance to be measured may flow in the process pipe 200 and the process pipe may be provided with a valve 202, which is opened to allow fluid substance flowing in the process pipe 200 to flow out of the process pipe 200.
- a sample of the fluid substance may be allowed to flow through the valve 202 into the measuring device 100 for measurement. After a desired amount of the sample has been taken, the valve 202 may be closed.
- the sample of fluid substance may first be allowed to flow into a scoop, bucket or another vessel, from which the sample may be poured or otherwise transferred into the measuring device 100 for measurement.
- the measuring device may be provided with a connection piece 204 for attaching the measuring device to a process pipe, process container or sampler.
- the process pipe, process container or sampler is provided with an attachment point 206 to which the connection piece 204 is attached by bolts and/or nuts, for example. Bayonet contacts may also be used.
- the attachment point 206 and connection piece 204 may also be provided with mutually suitable threads, in which case the measuring device 100 may be attached to the attachment point by means of the threads in the connection piece.
- the measuring space of the measuring device may be filled with fluid substance for measurement. The measuring device may be left in its place and used in carrying out successive measurements.
- Figure 3 illustrates one way of taking a sample from a container.
- the sample may be taken from fluid substance 302 in the container 300 by an open measuring device 100.
- the electronic and mechanical parts of the measuring device are protected so that the measuring device withstands immersion in fluid substance.
- a sufficiently tight structure also enables rinsing and washing of the measuring device.
- the measuring device 100 may be lifted from the container 300.
- the measuring device may be lifted from the container 300 by holding the handle 124 by hand.
- the lifting may also be performed by a lifting device.
- the sample may be taken by a scoop, bucket or another vessel, from which the sample may then be poured or otherwise FI2006/050570
- Figure 4 is a flow chart illustrating a method of measuring a suspension.
- a sample is taken from a suspension in a process into an open measuring space of the measuring device and enclosed in the measuring space.
- the transceiver of the measuring signal transmits a radio frequency electromagnetic signal through the sample in the measuring space so that the measuring signal penetrates a representative portion of the sample at least in the vertical direction.
- at least one operation is performed to reduce the influence of gas bubbles on the measurement.
- sample temperature is measured.
- the relative proportion of solids in the sample is determined by means of the travel time of the measuring signal and the measured temperature in the measuring unit of the measuring device.
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Abstract
A sample is taken of a suspension in a process into a measurement device (100), and the sample is closed into a measurement receptacle (102). A radio frequency signal is led through the sample in a vertical direction by means of a transceiver (108 - 112). The impact of air bubbles on the measurement is decreased. The transit time of the measurement signal and the temperature are measured, and the relative proportion of the substance to be measured in the sample is determined by means of these in a measurement unit (114).
Description
MEASURING SUSPENSION
FIELD
[0001] The invention comprises measuring a suspension which is to be processed in a process and which contains at least one substance to be measured that is mixed into fluid used as a medium.
BACKGROUND
[0002] In the paper, board and pulp industry, for example, filtrate samples are taken from stock for monitoring and controlling a process. Stock is a suspension which contains fluid (water), solid particles, such as fibres and possibly shives, fines removed from fibres, fillers, such as kaolin, talc, calcium carbonate or titan oxide, dissolved substances and some gas.
[0003] In the process industry, pulp consistency may be measured by a two-shaft measuring device, for example, where the shafts may rotate with respect to each other. The measurement is based on shearing forces and on determining them so that at the end of the measuring shafts, there are various projections whose movement the pulp to be measured tries to decelerate at a force dependent on fibre consistency. Since the device measures the force required to break a fibre network, its result is dependent on the pulp type and fibre length, for instance.
[0004] Pulp may also be measured optically, in which case either penetration measurement is performed on attenuation of light caused by pulp or reflection measurement on scattering of light caused by pulp. The result of optical measurement also depends on the pulp type and, in particular, on the filler type as their optical properties vary according to the type. In penetration measurement, the measuring interval must be very small due to strong attenuation of light. For this reason, penetration measurements are not suitable for measuring relatively high consistencies.
[0005] Consistency measurement by means of microwave radiation is also feasible. Solution of this kind is described in Finnish Patent No. 84402, for instance, which is incorporated herein by reference. In the solution, microwave radiation is emitted through pulp and the travel time of a microwave signal is measured, the time being dependent on consistency. Since the travel time of microwaves depends on the dielectricity constant of the substance to be measured, which is the same for different pulp types, the microwave measurement measures different pulp types in the same manner. The microwave
measurement also provides relatively long measuring distances and thus a large measurement volume and representative measurement since attenuation of microwaves in pulp is considerably smaller than attenuation of light, for example.
[0006] Measuring devices of the above kind are typically fixed in a process pipe system and their operation depends on the process and external sources as they, for example, receive electric power from a public electricity network or an electricity network connected to the process. These measuring devices are conventionally used in continuous measurement of consistency. Due to the fixed installation, price of measuring devices, and changing needs, etc., it is in practice impossible to install continuous measuring devices in all process points where pulp consistency is to be determined. In addition to the measurement by measuring devices, it may be desirable to perform comparison measurements, which are used to calibrate continuous measurements, for instance. For this reason, the process pipe system is further provided with sampling points (samplers). Consistency determination is performed in a laboratory on samples taken from the sampling points in accordance with a standardized method, such as TAPPI T 240 om-93. Such measurement is, however, slow and complicated.
BRIEF DESCRIPTION
[0007] The object of the invention is to provide an improved method and a measuring device implementing the method. This is achieved by a method of measuring a suspension which is processed in a process and contains fluid as a medium and solid particles mixed into the fluid. The method further comprises taking a sample from the suspension in the process into an open measuring space in the measuring device and enclosing the sample in the measuring space; transmitting a radio frequency electromagnetic measuring signal by the transceiver of the measuring device through a portion of a representative sample in the measuring space at least in the vertical direction; performing at least one operation to reduce the influence of gas bubbles on the measurement; measuring sample temperature; determining the relative proportion of solids in the sample by means of the travel time of the measuring signal and the measured temperature in the measuring unit of the measuring device.
[0008] The invention further relates to a measuring device for measuring a suspension, the suspension to be measured being processed in a
process and containing fluid as a medium and solid particles mixed into the fluid. The measuring device comprises an openable and closable measuring space, and when the measuring space of the measuring device is open, the measuring device is arranged to receive a sample from the suspension in the process into the measuring space; a transceiver which is arranged to transmit a radio frequency electromagnetic measuring signal through a portion of a representative sample in the measuring space in the vertical direction; a gas bubble remover which is arranged to perform at least one operation to reduce the influence of gas bubbles on the measurement; at least one temperature sensor which is arranged to measure sample temperature; a measuring unit which is functionally connected to the transceiver and temperature sensor and arranged to determine the relative proportion of solids in the sample by means of the travel time of the measuring signal and the measured temperature.
[0009] Preferred embodiments of the invention are disclosed in the dependent claims.
[0010] The method and system according to the invention provide several advantages. The solution is also independent of pulp types, in which case all different pulp types may be measured by the same calibration. It also enables measuring a sufficiently large pulp sample by one rapid measurement, in which case the measured sample is representative. Since the device may also be portable, it may be taken to the sampling point, where determination may be performed. In that case, it is not necessary to submit a plurality of samples to a laboratory for consistency determination.
LIST OF FIGURES
[0011] The invention will now be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which
Figure 1A illustrates a measuring device, Figure 1B illustrates a measuring space of the measuring device; Figure 2 illustrates sampling from a process pipe, Figure 3 illustrates sampling from a container, and Figure 4 is a flow chart illustrating a method of measuring a suspension.
DESCRIPTION OF EMBODIMENTS
[0012] The presented solution may be applied, for example, in the wood processing industry or in industries involved in environment maintenance, such as purification of waste water, but the solution is not limited to these.
[0013] Figure 1A illustrates a feasible implementation of a measuring device. The measuring device 100 comprises a measuring space 102, where a sample from a suspension in a process may be taken. The measuring space 102 may consist of a space defined inside the measuring device by its walls 96, bottom 98 and cover 104.
[0014] The measuring space 102 is openable and closable, for which purpose the measuring device 100 may comprise an openable and closable cover 104. In Figure 1 , the cover 104 is closed, but the cover illustrated with a broken line illustrates the cover in an open position. When the cover 104 is open, the measuring device 100 may take a sample from fluid substance in the process or a sample of fluid substance from the process may be fed into the measuring space 102 of the measuring device 100. The sample may be suspension which contains at least one of the following raw materials used in the paper, board and pulp industry: fibres (plant fibres, such as wood fibres), filler, fines. The sample may also be suspension which contains industrial or municipal waste in water.
[0015] Temperature compensation may be performed for the measurement on the basis of the temperature of the sample to be measured. In that case, the measuring space 102 may be encased with a thermal insulation or a thermally insulating structure (see Figure 1B) to prevent temperature differences inside the sample due to cooling at the edges in the case of warm or hot samples. Cooling may also be reduced by heating the walls of the measuring space. If temperature differences are generated in the sample, the temperature may be measured by several temperature sensors at different locations to determine the temperature distribution. The sample may also be stirred by a mechanical mixer, for example, to balance temperature differences.
[0016] The measuring space 102 can be closed tightly by closing the cover 104. The cover may further be shaped to fit accurately in an opening provided in the measuring device. Tightness may be improved by seals.
[0017] The measuring device comprises a gas bubble remover 106 for reducing the influence of gas bubbles on the measurement. The gas bubble
remover 106 may be a pressurization device, ultrasonic device, a device for adding fluid that reduces gas bubbles, or a mechanical mixer, which may be the same device as the mixer that balances the temperature or a different one. The pressurization device may be used to increase the pressure in the measuring space 102 when the measuring device is closed. The purpose of increasing the pressure is to dissolve the gas contained in the sample in the sample, in which case the dissolved gas does not interfere with the measurement. The pressurization device may comprise a compressor for pumping air or gas into the upper part of the measuring device to increase the pressure in the measuring space 102 of the measuring device. The pressurization device may be a connector connectable to the pneumatic system of a plant, for example. The pressurization device may also be a mechanical arrangement for decreasing the volume of the measuring space through a piston movement, for example, by rotating a lever or a wheel outside the measuring device. The pressurization device may also comprise rubber bellows for decreasing the measuring space. In addition to or instead of these, a carbon dioxide cartridge may be used to increase the pressure. The pressure may be increased higher than e.g. 150 kPa.
[0018] By feeding ultrasound into the sample, the number of gas bubbles in the sample may be decreased. The number of gas bubbles may also be decreased by adding a suitable fluid to the sample. In addition or alternatively, the sample may be stirred by a mechanical mixer, which removes at least some of the gas bubbles from the sample.
[0019] Measurement is performed by transmitting a measuring signal through the sample before reducing the number of gas bubbles. Furthermore, the measuring signal may be transmitted through the sample after the number of gas bubbles has been reduced. The number of gas bubbles in the sample may be determined by comparing measurement results.
[0020] The measuring device comprises a transceiver unit 108 and antennas 110 and 112, which transmit and receive a radio frequency electromagnetic measuring signal through the sample in the measuring device 100 in the vertical direction. The vertical direction is a preferred measuring direction since any sedimentation of the sample does not affect the measurement. For this reason, there is thus no need to stir the sample during measuring. The frequency range of radiation for performing measurement may be 1 to 5 GHz,
but frequencies outside these limits are also feasible, for example between 100 MHz and 10 GHz.
[0021] Measurement is performed so that the measuring signal has a vertical component and it penetrates a representative portion of the sample. As shown in Figure 1B, the measuring signal 150 does not need to travel completely in parallel with the earth's gravity field but the measurement signal 150 may also propagate diagonally. The measuring signal may propagate from top to bottom or from bottom to top. Representativiness is achieved in the measurement when the measuring signal 150 penetrates the whole or nearly the whole sample in the vertical direction. No specific representativeness is required in the horizontal direction. The walls 96, bottom 98 and cover 104 of the measuring space may be thermally insulated, which is illustrated by the thick walls in Figure 1B.
[0022] The transceiver unit 108 generates a radio frequency signal, which may be fed over a cable to a transmitting antenna 110 in the top. The transmitting antenna 110 transmits the radio frequency signal from the top through the sample and down to the receiving antenna 112, which transmits the signal it has received back to the transceiver unit 108. The transceiver unit 108 generates a measuring signal from the received radio frequency signal and uses it to determine the travel time or phase of the radio frequency signal. Alternatively, the transmitting antenna may be in the bottom and the receiving antenna in the top. When the transmitting antenna 110 and receiving antenna 112 are in contact with the sample, the influence of air or the like between the sample and the transmitting or receiving antenna on the measurement is avoidable (see Figure 1B).
[0023] The travel time of the radio frequency signal may be determined by an FMCW technique (Frequency Modulated Continuous Wave), for example, where frequency scanning is transmitted through the substance to be measured to the RF port (Radio Frequency) of the receiver mixer and through the inner signal path of the transmitter to the LO port (Local Oscillator) of the receiver mixer. Since the delay between the measuring path and the internal signal path is not the same, frequency f is obtained from the mixer's IF port. The following holds true for the difference between the delays of the measuring path and the inner signal path
t = f * T / B,
where B is the bandwidth (Hz) of frequency scanning and T = frequency scanning time (s).
[0024] The phase may also be determined by measuring the phase of one or more dot frequencies that have passed through the measuring path. This may be carried out by a "heterodyne technique", for example, where microwave signals that have passed through the inner signal path and have frequency f1 are converted by their own mixers into frequency f2, in which case the LO port of the mixers outputs a signal whose frequency is f1 to f2 and the phase is proportional to the distance travelled by the microwave signal. Since the distance travelled by the inner signal path is constant, phase changes in the signal that has travelled through the measuring path may be measured by measuring the phase difference between the mixer's IF signal of the measuring path and the mixer's IF signal of the inner signal path. The inner signal path may be omitted if signal f2 is generated by a phase lock, which locks the phase of signal f2 to the clock frequency. In that case, the clock frequency of the phase lock may be used instead of the mixer's IF signal of the inner signal path.
[0025] Measurement may also be performed as a direct travel time measurement by means of a signal pulse by measuring the time between transmitting and receiving a pulse. This measuring technique is generally used in surface level measurements, for example, where the distance of the surface causing reflection from the transceiver antenna is measured on the basis of the measured travel time.
[0026] The travel time may also be determined by a correlation technique. In correlation measurement, the object is to find the largest possible correlation by moving signals with respect to each other. The extent to which the signals need to be moved with respect to each other in time to obtain the largest possible correlation determines the difference of travel times between the reference measurement (signal that has propagated along the inner signal path, or a constant signal otherwise independent of the measurement) and the actual sample measurement.
[0027] Also other prior art methods or ready-made circuits exist for measuring the travel time and phase of microwaves. The device according to the presented solution may be implemented by any technique that measures the phase or travel time of microwaves with a sufficient accuracy.
[0028] Since the travel time and phase are directly proportional to each other, the relative proportion of the substance to be measured, such as consistency, can be calculated on the basis of either one of them. The connection between the travel time and the phase may be expressed by the following equation, for instance
t = n * T + f / 2 p * T,
[0029] where t = travel time, T = cycle length of the used frequency, n = number of complete cycle lengths in the measuring path, f = signal phase, and p «3.14159265.
[0030] The phase measurement does not indicate the number of complete cycle lengths in the measuring path, but this is not even necessary since for calculating consistency, it is sufficient to measure the change in the travel time or phase compared to a known reference point, which is typically the device's calibration point.
[0031] Since the travel time and phase express the same thing, in the following we will only refer to the travel time even though the measurement could also be carried out by using the phase.
[0032] The measuring device may further include at (east one temperature sensor 120, which is functionally connected to the measuring unit 114 for measuring sample temperature. The temperature measurement may be useful since the temperature considerably affects the travel time of microwaves in water. The effect of the temperature may be compensated for either on the basis of an experimental or a theoretical model. In a temperature range of 25°C to 1000C, a first-order linear model is usually sufficient, whereas in a temperature range below 250C, a multi-order polynomial is usually required due to the non-linear dependence between the travel time and the temperature.
[0033] The measured travel time and temperature are transmitted to the measuring unit 114, which calculates the relative proportion of the substance to be measured in the sample on the basis of measurement results.
[0034] Temperature may be measured by several temperature sensors at several points in the measuring space 102. A temperature distribution may be determined from the measurements and utilized in determining the relative proportion of the substance to be measured in the sample.
[0035] The measuring device may further comprise a detection unit 116, which presents the measurement result of the relative proportion of the substance to be measured in the sample to the user. The detection unit 116 may be a display. The detection unit 116 may also include a keyboard, mouse or another user interface for feeding data.
[0036] The measuring device may further comprise a power source 118, which feeds electric power into the transceiver, measuring unit, detection unit, gas bubble remover, any compressor, etc., in the measuring device for performing the measurement. The power source may be, for example, a dry- cell battery or a battery charged by a power-supply device. If the measuring device has no dedicated power source, it may take the required electric power from a public electricity network, for example. The measuring device may comprise a contact component 122 for connecting the measuring device 100 to an external data processing system. The contact component 122 may be a mechanical connector to which the counterpart of the data processing system is connected. The contact component 122 may also be a transmitter, receiver or transceiver part of a wireless system through which the measuring device communicates with the data processing system. The contact component 122 may operate optically, via a radio path, acoustically, inductively or capacita- tively. One solution that operates via the radio path is the Bluetooth® technique. By means of the contact component 122, the measuring device may be connected to an automation system controlling the process, for example. The battery of the measuring device may also be charged through the contact component.
[0037] The measuring device may further comprise a handle 124, which facilitates its handling. The measuring device may be movable and possibly small enough for carrying by hand.
[0038] The measuring device further comprises a memory 126, where the determined relative proportion of the substance to be measured may be stored. If necessary, the data stored in the memory 126 can be transferred to another data processing system or data storage system through the contact component, for instance.
[0039] The measuring device may be made of metal, plastic or composite. Since the measuring device operates at radio frequencies, it is useful to make the measuring space impermeable to radio frequencies. This way it is possible to avoid external interference in the measurement and to prevent
the measuring signal from escaping outside the measuring space.
[0040] The transceiver unit 108 may be arranged to measure, in addition to the travel time, attenuation of electromagnetic radiation in a sample. Since attenuation of microwaves is proportional to the electric conductivity of the sample, the attenuation measurement may be used to determine the sample's conductivity. Conductivity depends on the amount of electrically charged substances that have dissolved in the fluid substance. In particular, different bases, acids and salts, such as sodium hydroxide and sulphuric acid, produce conductivity-increasing ions in the fluid substance.
[0041] To determine conductivity, the influence of conductivity and temperature on the attenuation of microwaves must be determined by a model with a sufficiently large scale. Model parameters may be determined using experimental measurements, although they may also be determined on the basis of dielectricity constants found in the literature, provided that sufficiently accurate values are available for a sufficiently wide temperature range. The model parameters are substance specific, and when a good accuracy is desirable, they may be determined separately for each substance to be measured. The model parameters may also be specified on the basis of follow-up results.
[0042] After the model parameters have been determined, conductivity can be determined by feeding the measured attenuation of microwaves and possibly also the temperature into the model.
[0043] In addition to the attenuation of microwaves, conductivity and the amount of dissolved substances affect the travel time of microwaves, which can thus also be observed in the consistency measurement described above. If only solids concentration is to be determined from a sample, as in consistency measurements in the paper, board and pulp industry, dissolved substances cause errors in the consistency measurement. This error can be compensated for by modelling the effect of conductivity and temperature on the consistency measurement. The modelling may be performed as in the conductivity measurement described above by using a polynomial having a sufficiently high order. Model parameters may be determined experimentally. After the model parameters have been determined, the consistency error caused by dissolved conducive substances can be calculated by feeding the determined conductivity and measured temperature into the model. As in the conductivity model, the model parameters depend on the substance to be measured and they can be determined separately for each substance to be measured when a
good accuracy is aimed at. Model parameters may also be specified on the basis of follow-up results.
[0044] Figure 2 illustrates filling of a measuring device through a process pipe. The fluid substance to be measured may flow in the process pipe 200 and the process pipe may be provided with a valve 202, which is opened to allow fluid substance flowing in the process pipe 200 to flow out of the process pipe 200. A sample of the fluid substance may be allowed to flow through the valve 202 into the measuring device 100 for measurement. After a desired amount of the sample has been taken, the valve 202 may be closed. The sample of fluid substance may first be allowed to flow into a scoop, bucket or another vessel, from which the sample may be poured or otherwise transferred into the measuring device 100 for measurement.
[0045] In addition to or instead of the cover, the measuring device may be provided with a connection piece 204 for attaching the measuring device to a process pipe, process container or sampler. In that case, the process pipe, process container or sampler is provided with an attachment point 206 to which the connection piece 204 is attached by bolts and/or nuts, for example. Bayonet contacts may also be used. The attachment point 206 and connection piece 204 may also be provided with mutually suitable threads, in which case the measuring device 100 may be attached to the attachment point by means of the threads in the connection piece. After the measuring device has been attached to the process pipe, process container or sampler, the measuring space of the measuring device may be filled with fluid substance for measurement. The measuring device may be left in its place and used in carrying out successive measurements.
[0046] Figure 3 illustrates one way of taking a sample from a container. The sample may be taken from fluid substance 302 in the container 300 by an open measuring device 100. The electronic and mechanical parts of the measuring device are protected so that the measuring device withstands immersion in fluid substance. A sufficiently tight structure also enables rinsing and washing of the measuring device. After the measuring space of the measuring device has been filled with fluid substance 302, the measuring device 100 may be lifted from the container 300. The measuring device may be lifted from the container 300 by holding the handle 124 by hand. The lifting may also be performed by a lifting device. The sample may be taken by a scoop, bucket or another vessel, from which the sample may then be poured or otherwise
FI2006/050570
12 transferred into the measuring device 100 for measurement.
10047] Figure 4 is a flow chart illustrating a method of measuring a suspension. In step 400, a sample is taken from a suspension in a process into an open measuring space of the measuring device and enclosed in the measuring space. In step 402, the transceiver of the measuring signal transmits a radio frequency electromagnetic signal through the sample in the measuring space so that the measuring signal penetrates a representative portion of the sample at least in the vertical direction. In step 404, at least one operation is performed to reduce the influence of gas bubbles on the measurement. In step 406, sample temperature is measured. In step 408, the relative proportion of solids in the sample is determined by means of the travel time of the measuring signal and the measured temperature in the measuring unit of the measuring device.
[0048] Even though the invention was described above with reference to an example according to the accompanying drawings, it is clear that the invention is not limited thereto but it may be modified in various ways within the scope of the claims.
Claims
1. A method of measuring a suspension which is processed in a process and contains fluid used as a medium and solid particles mixed into the fluid, characterized by taking (400) a sample from the suspension in the process into an open measuring space (102) of a measuring device (100) and enclosing the sample in the measuring space (102): transmitting (402) a radio frequency electromagnetic signal by a transceiver (108-112) of the measuring device (100) through a representative portion of the sample in the measuring space (102) at least in the vertical direction; performing (404) at least one operation to reduce the influence of gas bubbles on the measurement; measuring (406) sample temperature; determining (408) the relative proportion of solids in the sample by means of the travel time of the measuring signal and the measured temperature in a measuring unit (114) of the measuring device (100).
2. A method according to claim 1 , characterized by presenting a result of the relative proportion of solids in the sample to a user by a detection device (116) of the measuring device (100).
3. A method according to claim 1, characterized by feeding electric power from a power source (118) of the measuring device into the transceiver (108-112), measuring unit (114), gas bubble remover (106) and/or detection device (116) of the measuring device for performing measurement,
4. A method according to claim 1 , characterized by measuring a suspension of the paper, board or pulp industry where the medium is water and the solid particles are wood fibres.
5. A method according to claim 1 , characterized by measuring a suspension of the paper, board or pulp industry where the medium is water and the solid particles are fillers.
6. A method according to claim 1 , characterized by measuring attenuation caused by the sample in the measuring signal and determining sample conductivity by means of the measured temperature and attenuation.
7. A method according to claim 6, characterized by taking sample conductivity into account in determining the relative proportion of solids in the sample.
8. A method according to claim 1 , characterized by storing the determined relative proportion of the substance to be measured in a memory (126).
9. A method according to claim 1 , characterized by performing at least one of the following operations to reduce the influence of gas bubbles on the measurement: increasing pressure in the measuring space (102) of the measuring device (100) by the gas bubble remover (106) provided in the measuring device, feeding an ultrasonic signal into the sample in the measuring space (102), stirring the sample mechanically.
10. A method according to claim 1 , characterized by using a thermally insulated measuring space in the measurement.
11. A method according to claim 1 , characterized by measuring temperature at several points of the measuring space (102), determining a temperature distribution in the sample on the basis of the measurements, and utilizing the temperature distribution in determining the relative proportion of the substance to be measure in the sample.
12. A method according to claim 1 , characterized by stirring the sample to balance temperature differences.
13. A method according to claim 1 , characterized by further determining the gas content of the sample by measuring the travel time of the measuring signal before and after reducing the influence of gas bubbles.
14. A measuring device for measuring a suspension, the suspension to be measured being processed in a process and containing fluid used as a medium and solid particles mixed into the fluid, characterized in that the measuring device (100) comprises: an openable and closable measuring space (102), and when the measuring space (102) of the measuring device (100) is open, the measuring device (100) is arranged to receive a sample from the suspension in the process into the measuring space (102); a transceiver (108-112) arranged to transmit a radio frequency electromagnetic measuring signal through a representative portion of the sample in the measuring space (102) in the vertical direction; a gas bubble remover (106) arranged to perform at least one operation to reduce the influence of gas bubbles on measurement; at least one temperature sensor (12) arranged to measure sample temperature; a measuring unit (114) which is functionally connected to the transceiver (108-112) and temperature sensor (120) and arranged to determine the relative proportion of solids in the sample by means of the travel time of the measuring signal and the measured temperature.
15. A measuring device according to claim 14, characterized in that the measuring device comprises a detection device (116) for presenting a result of the relative proportion of solids in the sample to a user.
16. A measuring device according to claim 14, characterized in that the measuring device comprises a power source (118) arranged to feed electric power into the transceiver (108-112), measuring unit (114), gas bubble remover (106) and/or detection device (116) of the measuring device for performing the measurement.
17. A measuring device according to claim 14, characterized in that the measuring device (100) is arranged to measure a suspension which is a suspension in a process of the paper, board or pulp industry, the medium being water and solid particles at least partly wood fibres.
18. A measuring device according to claim 14, characterized in that the measuring device (100) is arranged to measure suspension which is suspension in a process of the paper, board and pulp industry, the medium being water and the solid particles being fillers.
19. A measuring device according to claim 14, characterized in that the measuring unit (114) is arranged to measure attenuation of the measuring signal in the sample and determine sample conductivity from the measured temperature and attenuation.
20. A measuring device according to claim 19, characterized in that the measuring unit (114) is arranged to take sample conductivity into account in the determination of the relative proportion of solids.
21. A measuring device according to claim 14, characterized in that for reducing the influence of gas bubble, the gas bubble remover (106) is arranged to perform at least one of the following operations: increasing pressure in the measuring space (102) of the measuring device (100) by means of the gas bubble remover (106) provided in the measuring device, feeding an ultrasonic signal into the sample in the measuring space (102), stirring the sample mechanically.
22. A measuring device according to claim 14, characterized in that the measuring space (102) is provided with thermal insulation.
23. A measuring device according to claim 14, characterized in that for reducing the influence of gas in order to the measuring device comprises several temperature sensors at several points of the measuring space (102), and the measuring unit is arranged to determine a temperature distribution in the sample on the basis of the measurements and utilize the temperature distribution in determining the relative proportion of the substance to be measure in the sample.
24. A measuring device according to claim 14, characterized in that the gas bubble remover (106) is arranged to stir the sample to balance temperature differences before the measurement.
25. A measuring device according to claim 14, characterized in that the measuring device is arranged to transmit a measuring signal before and after the reduction of the gas bubbles, and the measuring unit (114) is arranged to determine the gas content in the sample by measuring the travel time of the measuring signal before and after the reduction of the influence of gas bubbles.
26. A measuring device according to claim 14, characterized in that the measuring device comprises a memory (126) for storing the determined relative proportion of the substance to be measured.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI20055694 | 2005-12-22 | ||
FI20055694A FI20055694A (en) | 2005-12-22 | 2005-12-22 | Measurement of suspension |
Publications (1)
Publication Number | Publication Date |
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WO2007071825A1 true WO2007071825A1 (en) | 2007-06-28 |
Family
ID=35510772
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/FI2006/050570 WO2007071825A1 (en) | 2005-12-22 | 2006-12-20 | Measuring suspension |
Country Status (2)
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FI (1) | FI20055694A (en) |
WO (1) | WO2007071825A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107340209A (en) * | 2016-04-28 | 2017-11-10 | 富士电机株式会社 | Generating source analytical equipment and generating source analysis method |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FI84299C (en) * | 1989-05-05 | 1991-11-11 | Ahlstroem Oy | Method and apparatus for determining the content of different fractions in pulp suspension |
US5864240A (en) * | 1996-01-31 | 1999-01-26 | Kabushiki Kaisha Toshiba | Method and apparatus for measuring concentration of matter in liquid by using microwaves |
FI104447B (en) * | 1998-07-10 | 2000-01-31 | Valmet Automation Inc | Method and instrument for measuring the gas content of a liquid substance |
JP2002357566A (en) * | 2002-05-17 | 2002-12-13 | Toshiba It & Control Systems Corp | Microwave concentration-measuring instrument |
WO2004086006A1 (en) * | 2003-03-24 | 2004-10-07 | Katz, Elisabeth | Method and device for determining the solid content in a suspension |
-
2005
- 2005-12-22 FI FI20055694A patent/FI20055694A/en not_active Application Discontinuation
-
2006
- 2006-12-20 WO PCT/FI2006/050570 patent/WO2007071825A1/en active Application Filing
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FI84299C (en) * | 1989-05-05 | 1991-11-11 | Ahlstroem Oy | Method and apparatus for determining the content of different fractions in pulp suspension |
US5864240A (en) * | 1996-01-31 | 1999-01-26 | Kabushiki Kaisha Toshiba | Method and apparatus for measuring concentration of matter in liquid by using microwaves |
FI104447B (en) * | 1998-07-10 | 2000-01-31 | Valmet Automation Inc | Method and instrument for measuring the gas content of a liquid substance |
JP2002357566A (en) * | 2002-05-17 | 2002-12-13 | Toshiba It & Control Systems Corp | Microwave concentration-measuring instrument |
WO2004086006A1 (en) * | 2003-03-24 | 2004-10-07 | Katz, Elisabeth | Method and device for determining the solid content in a suspension |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107340209A (en) * | 2016-04-28 | 2017-11-10 | 富士电机株式会社 | Generating source analytical equipment and generating source analysis method |
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FI20055694A (en) | 2007-06-23 |
FI20055694A0 (en) | 2005-12-22 |
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