Optical detector for the presence of gas bubbles in a liquid

Abstract

The invention concerns a method for detecting gas bubbles in a liquid adapted to a device comprising a light source, a light detector and a data controlling and processing unit connected to a client system comprising the following steps: emitting light from the light source, acquiring successive measurements of the light intensity sensed by the light detector and calculating a variation between two successive measurements of said light intensity. In accordance with a first embodiment of the invention, the method further comprises a step which consists in comparing the variation between two successive measurements of light intensity to a threshold S. Advantageously, a warning counter is incremented by a value A when variation between two successive measurements is higher than the threshold S and decremented by a value B in the opposite case. A proportion of bubbles higher than a maximum authorized rate is detected when said warning counter exceeds a warning value C. In a second embodiment of the invention, the method further comprises a step which consists in calculating an average value between the variations between two successive measurements of light intensity. The client system is made aware of said average value proportional to said bubble content in the liquid.

1 . Process for detection of gas bubbles in a liquid adapted to a device comprising a light source ( 1 ), a light detector ( 2 ) and a data controlling and processing unit ( 6 ) linked to a client system ( 8 ) comprising the steps of emitting light from the light source ( 1 ), for acquisition of the successive measurements of light intensity perceived by the light detector ( 2 ) and for calculation of a variation between two successive measurements of said light intensity. 
   
   
       2 . Process according to  claim 1 , characterised in that it further comprises a comparison step of the time variation at a predefined threshold value S. 
   
   
       3 . Process according to  claim 2 , characterised in that it further comprises an incrementation step of an alarm counter ( 13 ) by a predefined value A when the variation in light intensity perceived by the light detector ( 2 ) between two successive measurements is greater than the threshold S and decrementation of said warning counter ( 13 ) by a predefined value B in the opposite case. 
   
   
       4 . Process according to  claim 3 , characterised in that it further comprises a step of sending to the client system ( 8 ) information indicating that a bubble content is greater than an authorised maximum content when said warning counter ( 13 ) exceeds a predefined value C known as the alarm value. 
   
   
       5 . Process according to  claim 3  characterised in that it further comprises a step consisting of sending to the client system ( 8 ) information indicating that a bubble content is greater than an authorised maximum content when said warning counter ( 13 ) exceeds a predefined value C′ known as the alarm value over a period greater than a predefined time delay period. 
   
   
       6 . Process according to any of  claims 4  or  5  characterised in that it further comprises a ceasing step of sending to the client system ( 8 ) information indicating that the bubble content is greater than the authorised maximum content when the warning counter ( 13 ) is less than a predefined value D known as the final alarm value. 
   
   
       7 . Process according to  claim 1 , characterised in that it further comprises a calculation step of an average value from a plurality of variations between two successive measurements of light intensity. 
   
   
       8 . Process according to  claim 7  characterised in that it further comprises a step of sending to the client system ( 8 ) information indicating the average value of the successive variations of the light intensity perceived by the light detector ( 2 ). 
   
   
       9 . Process according to any of the above claims, characterised in that the data controlling and processing unit ( 6 ) comprising a control module of the light source ( 15 ) capable of polarising said light source ( 1 ) on several polarisation levels, the light source ( 1 ) is polarised periodically by said control module ( 15 ) of the light source. 
   
   
       10 . Process according to  claim 9 , characterised in that a calibration of the sensor constituted by the source ( 1 ) and the light detector ( 2 ) is carried out synchronously on the periodic polarisation of the light source ( 1 ). 
   
   
       11 . Process according to any of the above claims, characterised in that the source ( 1 ) and the light detector ( 2 ) being arranged noticeably orthogonally, the acquisition step of the successive measurements of light intensity perceived by the light detector ( 2 ) makes it possible to acquire measurements of the quantity of light rays emitted by the light source ( 1 ) which are reflected should the case arise in the presence of bubbles on the surface of a gas bubble in a direction noticeably orthogonal to the direction of incidence towards the light detector ( 2 ). 
   
   
       12 . Process according to any of  claims 1  to  10 , characterised in that, the source ( 1 ) and the light detector ( 2 ) being arranged noticeably adjacently, the acquisition step of the successive measurements of light intensity perceived by the light detector ( 2 ) makes it possible to acquire measurements of the quantity of light rays emitted by the light source ( 1 ) which are reflected should the case arise in the presence of bubbles on the surface of a gas bubble in a direction noticeably parallel to the direction of incidence towards the light detector ( 2 ). 
   
   
       13 . Process according to any of  claims 11  or  12 , characterised in that, the device likewise comprising a temperature measuring element and at least one switch linked to said temperature measuring element, the switch is capable of changing state during the detection of a gas bubble. 
   
   
       14 . Process according to  claim 13 , characterised in that, the data controlling and processing unit ( 6 ) transmitting, via an interface module ( 7 ), to the client system ( 8 ) information on the temperature of the liquid and the presence of gas bubbles in the liquid, the interface module ( 7 ) and the client system ( 8 ) being linked only by a single wire, a high-amplitude level signal proportional to the temperature of the liquid when the presence of a bubble is not detected or low level when the presence of a bubble is detected is sent to the client system ( 8 ) by the interface module ( 7 ). 
   
   
       15 . Process according to any of  claims 11  or  12 , characterised in that, the device likewise comprising a system of electrodes capable of measuring the resistivity of the ambient conditions and since the data controlling and processing unit ( 6 ) being linked to the client system ( 8 ) via an interface module ( 7 ), the client system ( 8 ) is informed, via the interface module ( 7 ), by the data controlling and processing unit ( 6 ), that the sensor constituted by the source ( 1 ) and the light detector ( 2 ) is not immersed in the liquid when the system of electrodes identifies the ambient conditions as not being the liquid. 
   
   
       16 . Process according to  claim 15 , characterised in that, the device likewise comprising a temperature measuring element and at least one switch linked to said temperature measuring element, the switch is capable of changing state during the detection of a gas bubble and during the absence of liquid. 
   
   
       17 . Process according to  claim 16 , characterised in that, the data controlling and processing unit ( 6 ) transmitting, via the interface module ( 7 ), to the client system information on the temperature of the liquid, the presence of gas bubbles in the liquid and the non-immersion of the sensor in the liquid, the interface module ( 7 ) and the client system ( 8 ) being linked only by a single wire, a high-amplitude level signal proportional to the temperature of the liquid when the presence of a bubble is not detected and when the sensor is immersed in the liquid or low level when the presence of a bubble is detected or when the sensor is not immersed in the liquid is supplied to the client system ( 8 ) by the interface module ( 7 ). 
   
   
       18 . Process according to any of  claims 1  to  10 , characterised in that, the source ( 1 ) and the light detector ( 2 ) being arranged noticeably opposite each other, the step of light emission makes it possible to send out a light of specific wavelength from the light source ( 1 ) such that it is strongly (reciprocally weakly) absorbed by the liquid and slightly (reciprocally strongly) absorbed by the gas constituting the bubbles. 
   
   
       19 . Process according to any of  claims 1  to  10 , characterised in that, the source ( 1 ) and the light detector ( 2 ) being arranged noticeably opposite each other, the acquisition step of the successive measurements of light intensity perceived by the light detector ( 2 ) makes it possible to acquire measurements of the quantity of light rays emitted by the light source ( 1 ) which are deflected towards the light detector ( 2 ) should the case arise in the presence of bubbles due to the diffraction index differences between the liquid and the gas constituting the bubbles at the level of the surface of said bubbles. 
   
   
       20 . Process according to any of  claims 18  or  19 , characterised in that, the device likewise comprising a temperature measuring element and at least one switch linked to said temperature measuring element, the switch is capable of changing state periodically. 
   
   
       21 . Process according to  claim 20 , characterised in that, the data controlling and processing unit ( 6 ) transmitting, via an interface module ( 7 ), to the client system information on the temperature of the liquid and the presence of bubbles in the liquid, the interface module ( 7 ) and the client system ( 8 ) being linked only by a single wire, a periodic signal is supplied to the client system ( 8 ) by the interface module ( 7 ). 
   
   
       22 . Process according to  claim 21 , characterised in that the period of said periodic signal is formed by a first phase constituted by a constant high-amplitude level signal proportional to the temperature of the liquid and by a second phase constituted by a train of pulses of modulated width, the width of the impulses being modulated according to the average value of the successive variations in light intensity perceived by the light detector ( 2 ). 
   
   
       23 . Process according to any of  claims 18  or  19 , characterised in that the client system ( 8 ) is informed, via an interface module ( 7 ), that the sensor is not immersed in liquid when the polarisation value of the light source ( 1 ) is lower than a predefined threshold value T, known as the polarisation alarm threshold value. 
   
   
       24 . Process according to  claim 23 , characterised in that, the device likewise comprising a temperature measuring element and at least one switch linked to said temperature measuring element, the switch is capable of changing state periodically. 
   
   
       25 . Process according to  claim 24 , characterised in that the data controlling and processing unit ( 6 ) transmitting, via the interface module ( 7 ), to the client system the information on the temperature of the liquid, the presence of bubbles in the liquid and the non-immersion of the sensor in the liquid, the interface module ( 7 ) and the client system ( 8 ) being linked only by a single wire, a periodic signal is supplied to the client system ( 8 ) by the interface module ( 7 ). 
   
   
       26 . Process according to  claim 25 , characterised in that the period of said periodic signal is formed from a first phase constituted by a constant high-amplitude level signal proportional to the temperature of the liquid and a second phase constituted by a train of pulses of modulated width, the width of the impulses being modulated according to the average value of the successive variations in light intensity perceived by the light detector ( 2 ) and said width being maximum when the sensor is not immersed in the liquid. 
   
   
       27 . Device of detection of gas bubbles in a liquid comprising light emission means, light detection means and data controlling and processing means linked to the light detection means, characterised in that following emission of light by the light emission means and following the detection of light by the light detection means, the data controlling and processing means are capable of obtaining light detection means of the successive measurements of light intensity detected by the light detection means and of calculating a variation in light intensity between two successive measurements of light intensity.