Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
  • G01N21/53—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
  • G01N21/534—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke by measuring transmission alone, i.e. determining opacity

Definitions

• the present invention relates to an apparatus for measuring the evolution of the optical characteristics of a circulating liquid or gaseous medium, by measuring the light scattered through the medium.
• the invention relates to the field of measurement and control of turbidity and particle counting.
• the turbidity of a liquid or gaseous medium is defined as the expression of the optical property of the medium in dispersing or absorbing light rather than transmitting it in a straight line.
• the dispersion and absorption of light is caused by the interaction of light with particles suspended in the medium.
• the measure of turbidity was the measure of the attenuation of the light transmitted through a liquid sample.
• this mitigation measure is not significant for low turbidity.
• the device is recalibrated for each measurement using a model for comparison.
• Known turbidimeters operate discontinuously by sampling. They use a small tank. Some comparisons are done manually, others are done automatically but always discontinuously.
• a new regulation for example the French standard NF EN 27027 provides for comparing the medium to be measured with a sample medium based on formazine constituting the primary standard of turbidity.
• the amount of light scattered by a particle depends among other things on its size, shape, orientation, composition and refractive indices, that liquid and that of particles. In these conditions it is necessary to calibrate the measuring device.
• the purpose of the present invention is to remedy the drawbacks of known techniques and proposes to create a device for measuring counting and analyzing a fluid allowing continuous measurement of a liquid or gaseous medium to determine its evolution. and take the appropriate measures according to this development, in particular for the monitoring and control of fluids such as drinking water and water discharged after treatment, of household or industrial origin, edible liquids, milk, fruit juice.
• a sensor having a passage crossed by the medium to be measured, - a monochromatic light source and stabilized on a wavelength directed through the passage,
• an operating circuit formed by a supply circuit for the source and for shaping the signals from the photodetector and the flow meter, and a processing circuit for evaluating the signals from the sensor and the flow meter and providing data representative.
• the flow meter is an ultrasonic flow meter; - the flow meter includes a temperature probe;
• the flow meter includes an ultrasonic generator for permanent or periodic cleaning of the interior of the sensor through which the fluid flows.
• the measuring device allows continuous operation, that is to say permanent monitoring or evaluation of the fluid (liquid or gas) charged or whose turbidity and more generally the concentration of particles is to be monitored, which is an extremely important advantage and security. This considerably reduces the risks, in particular of pollution or industrial accident without requiring the permanent presence of an agent.
• the processing circuit contains the calibration curve and preferably a theoretical model, chosen according to the analysis to be carried out.
• Several models can be stored in the device, which allows it to immediately validate the measurement provided by the sensor.
• the device is calibrated at the factory once and for all. It does not require any recalibration for each measurement. Its factory calibration can be done by a programmable automaton to allow the device to carry out different types of analyzes or particle counts or turbidity measurements, for example in different ranges such as those defined by the standards. Despite this almost final calibration in the factory, it is still desirable to carry out a regular control of the device as imposed by certain national standards relating to measuring instruments or similar devices. As this device takes into account the flow rate for particle counting, a result independent of the flow rate is obtained. This is very important for continuous measurements since the flow rates of the fluids analyzed can vary.
• the source is a laser diode
• the photodetector signal shaping circuit consists of a filter and an amplifier
• the device measures the temperature of the fluid analyzed
• FIG. 1 is a block diagram of the measuring device according to the invention
• FIG. 2 is a block diagram of the device of Figure 1
• - Figure 3 is a perspective view, cut, of an embodiment of a sensor
• the sensor 100 consists of a body 110 in which a passage 111 is made through which the medium to be measured (arrow A) (axis YY) is produced.
• This body 110 houses a source of monochromatic light and stabilized on a wavelength 112 formed by a diode 113 and its optical equipment (lens) 114.
• the diode 113 is connected to the operating circuit 200 which stabilizes its length d wave and its power.
• the source 112 is directed across the passage 111 along the axis XX.
• the sensor 100 also includes a photodetector 120 aligned, at an angle depending on the applications, on the source 112, on the other side of the passage 111.
• This photodetector 120 comprises a semiconductor photodetector 121 such as a phototransistor preceded by an optic 122
• This photodetector 120 supplies a measurement signal S 1 to the operating circuit 200.
• the senor also includes a temperature probe 150, when for example the temperature of the fluid is likely to vary significantly for the resulting signal.
• the signal S 3 from the temperature probe is also supplied to circuit 200.
• the operating circuit 200 consists of a circuit 210 for shaping the signals from the sensor 100 and a processing circuit 220 for the signal thus formed.
• the shaping circuit 210 receives the signals S 1 # S, S 3 from the photodetector 120 of the flow meter 140 and from the temperature sensor 150 to filter and amplify them then supply the shaped signals S 4 , S 5 , S ⁇ , to the processing circuit 220 constituted by a microprocessor.
• This processing circuit 220 compares the signal obtained with one or more reference signals, to form a signal representative of the turbidity of the fluid in FAU units, after having corrected it taking account of the flow rate and, where appropriate, of the temperature. of the fluid analyzed.
• the senor 100 comprises a part of the operating circuit, namely the supply circuit 15 of the diode 113 of the source 112 as well as the means for shaping the signals supplied by the photodetector 121. To this end , it includes a filter 123 which filters the signals to separate the parasites. The filter 123 is followed by an amplifier 124 and an output 125.
• the cable 300 which makes the connection between the sensor
• the operating circuit 200 is preferably a shielded cable grounded 301 by its shield 302.
• the operating circuit 200 consists of a general supply 201 which supplies electrical energy in the form requested by the different users; in particular this general supply 201 is connected to the regulated supply 115 of the diode 113.
• the general supply 201 is also connected to the microprocessor 202 constituting the data processing circuit.
• the input of the general supply 201 is, for example, the voltage at 220 volts from the network.
• the microprocessor 202 receives, via an analog / digital converter 203, the signals from the sensor transmitted by the line 300 connected to an input circuit 204.
• the data processed by the microprocessor 202 from information supplied by the analog / digital converter 203 are transmitted either to a resetting means 205 which manages the various commands for setting up alarms in the event of the thresholds being exceeded. turbidity or pumps and in particular circulation and lifting pumps.
• the microprocessor 202 also supplies the information to a display means 206 making it possible to immediately display the measured turbidity.
• the microprocessor 202 is connected to a recorder output by a digital / analog converter 207 and an input / output circuit 208. Finally, the microprocessor 202 is connected by an interface 209 to an RS 232C output ensuring the connection with a computer or a automaton.
• the device can give turbidity measurements or carry out a particle count, giving a histogram or an average as well as other accessory information such as for example the flow rate and the temperature of the fluid.
• FIG. 3 shows an example of a sensor of the measuring device according to the invention.
• This sensor 100 consists of a cylindrical assembly with an inlet 131 and outlet 132 nozzle, for example threaded, by which the sensor 100 is connected to a main pipe if the liquid flow rate is not significant or bypassing the main line if the fluid flow in the main line is high.
• the diode 133 directs its beam through the passage 135 traversed by the medium to be measured.
• the detector 136 On the other side and aligned with the diode 133 is the detector 136 in the form of a photodiode; this photodiode 136 is blocked in a housing by a stop nut 137 just as the source is blocked in its housing by a nut 138.
• the flow meter 140 and the temperature probe 150 are also provided in this example.
• the sensor 100 also includes a card 139 provided with the part of the processing circuit which must be killed in the immediate vicinity of the signal source, that is to say the diode 133 and the photodiode 136.
• the circuit thus comprises the supply for regulating the source, a filter followed by an amplifier and the unit for exit.
• the cable 300 exiting the sensor is also shown in this figure.
• the senor proper is mounted between two flanges 141, 142, not symmetrical but cylindrical, and which one carry the inlet nozzle 131, the other the outlet nozzle 132 These flanges are joined by screws. There are also seals 143 which seal the assembly tightly.
• the source 133, its lens and the detector are aligned at right angles to the axis of circulation of the fluid inside the housing.
• the end flanges are made of PVC. They are each held by 145 screws.
• the actual box can have a brass body and the PVC casing. In the case of an aggressive environment, the assembly will be made of stainless steel.
• the sensor according to the invention makes it possible to measure, according to the theoretical model which it contains, different turbidities. Thus, it can measure:

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• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Optical Measuring Cells (AREA)

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• 1997
  • 1997-05-23 FR FR9706315A patent/FR2763685B1/fr not_active Expired - Fee Related
• 1998
  • 1998-05-19 EP EP98925739A patent/EP0983502A1/de not_active Withdrawn
  • 1998-05-19 JP JP55004598A patent/JP2001526785A/ja active Pending
  • 1998-05-19 WO PCT/FR1998/000992 patent/WO1998053302A1/fr not_active Ceased
  • 1998-05-19 CA CA002290674A patent/CA2290674A1/fr not_active Abandoned
  • 1998-06-19 AU AU77743/98A patent/AU7774398A/en not_active Abandoned

Non-Patent Citations (1)

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