FR3043771A1 - APPARATUS FOR LEVEL MEASUREMENT OF AQUEOUS FRACTION - Google Patents

Abstract

Measuring device suitable for level measurement of an aqueous fraction in an enclosure for receiving two separate liquid fractions, namely an aqueous fraction (Wa), and a light fraction (Oi) of lower density, located above of the aqueous fraction, said measuring device comprising: - a float system (2), tared so as to follow the changes in the level of the aqueous fraction / light fraction interface, - a measurement sensor, targeting the displacement at the climbing or lowering said float system in said enclosure, delivering an analog or digital signal, representative of the position of the float in said enclosure.

Description

The invention relates to a device suitable for measuring the level of an aqueous fraction in an enclosure intended to receive two separate liquid fractions, namely an aqueous fraction, and a light fraction of lower density, greater than the aqueous fraction. . The invention also relates to an oil / water separator equipped with such a measuring device, as well as a remote monitoring system equipped with one or more devices according to the invention. The invention also relates to a method of monitoring the filling of an enclosure in a light fraction, said method implementing a measuring device according to the invention, said enclosure being intended to receive the two separate liquid fractions, namely a fraction aqueous, and a light fraction of lower density, located above the aqueous fraction.

The field of the invention is that of oil-water separators, also called hydrocarbon separators, namely equipment intended to retain light hydrocarbons, with a density of less than or equal to 0.95. These hydrocarbons are practically or completely insoluble in water, or unsaponifiable.

A hydrocarbon separator comprises a separator compartment defining an enclosure within which the hydrocarbons separate from the aqueous fraction. The lighter hydrocarbon fraction is located above the aqueous fraction. Today such separators find an application for the treatment of effluents, before discharge into the rainwater network. They are found especially in service stations, garages, washing areas, mechanical workshops, covered car parks, unloading docks etc ...

In normal operation, a lower outlet of the separator compartment allows the aqueous fraction to evacuate, the light fraction of hydrocarbon then remaining trapped in the enclosure. Gradually, the thickness of the hydrocarbon fraction grows to require maintenance by skimming this light fraction.

To avoid the inadvertent release of hydrocarbon, this type of oil / water separators conventionally comprises an automatic shutter system, which comprises a movable shutter secured to a float. The float assembly and its shutter is calibrated so as to follow the level of the aqueous fraction / light fraction interface; for this purpose the density of the float and shutter assembly has a density intermediate between that of the aqueous fraction and that of the hydrocarbons. Also, when the thickness of the light fraction of hydrocarbons becomes too great, and therefore the level of the aqueous fraction / light fraction interface decreases, the descent of the float causes that of the shutter to be below a value threshold, until closing the evacuation by the shutter. Such a safety avoids the nuisance release of hydrocarbons but makes the separator inoperative: emergency maintenance must be triggered by skimming of the light fraction, and so that the separator is again operational.

The separation chamber of the separating equipment is conventionally preceded by a sludge compartment operating a pre-treatment of the effluents by settling. Decanted effluent flows overflow and is conveyed towards the separator compartment via a coalescence cell. The function of the coalescence cell is to agglutinate the micro-droplets of hydrocarbons to form larger hydrocarbon droplets, more easily going up to the surface of the aqueous fraction / light fraction interface. The document FR.2.654.950 describes for guidance such a hydrocarbon separator.

In practice, the maintenance of the separator compartment and of the dewatering compartment requires the mobilization and movement of hydro-curators vehicles, to the various sites (service stations, washing station, etc.) where these equipment are located. . In Europe, and according to the European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR), the vehicle must be a vehicle with three certified tanks, including a first tank of clean water intended to re-water the separator ( after cleaning), a second tank intended to receive the clear waters of the separator, and finally, a third tank intended to contain the sludge, the hydrocarbons and the washing water. As of today, and according to the findings of the inventor, these expensive maintenance operations are programmed by the managers of these equipment, periodically, for example and at most every six months, as 'imposes the standard AFNOR NF P16-442 of August 2014. Classically, this programming is periodically performed blind, that is to say without knowing the need (or not) to operate such maintenance .

The above-mentioned Afnor NF P16-442 standard also requires an alarm to be installed near the automatic shut-off system of the hydrocarbon separator: the function of this alarm is to detect a critical level of hydrocarbon in the separator compartment. that is to say, very often, a hydrocarbon level corresponding to the automatic closure of the shutter system, or corresponding to a level just above this critical level. The state of the art thus knows alarm devices particularly intended for the monitoring of hydrocarbon separators: an example of such a monitoring apparatus is the level detection device for hydrocarbon separators -NivOil® / 230 V AC - marketed by the company BAMO MESURES (www.bamo.eu).

The detection of the critical level of hydrocarbon is thus permitted by the use of a hydrocarbon layer level probe, referenced NivOiL-OP / 10. This probe is intended to be immersed in the equipment compartment: it is conveniently positioned at a fixed height in the separator compartment, suspended by its cable specifically designed to resist hydrocarbons, and so as to position its measuring end, at the threshold level to be monitored. Capacitive measurement takes place only at the lower end of the probe. When the hydrocarbon layer is thin, and therefore the measurement end is positioned in the aqueous fraction, the capacity measurement is identified as that of water. As the hydrocarbon layer grows, and as the light fraction / aqueous fraction interface lowers, there comes a time when the measuring end of the probe passes from the water to the hydrocarbons: the capacity measurement is then identified as that of the hydrocarbon layer: such a change can trigger an alarm.

According to the findings of the inventor, such a level control device gives only an all or nothing information, namely either the information "critical hydrocarbon threshold level reached", or the information "critical threshold level not reached". Moreover, and according to the findings of the inventor, and when the critical threshold level is reached, it is often necessary to trigger an emergency maintenance of the hydrocarbon separator. In other words, and at this late stage, it is no longer possible to optimize maintenance programming, in particular in order to limit the movements of maintenance vehicles. Prior to this information, the level control devices of the state of the art therefore do not allow to know precisely the filling level of the hydrocarbon compartment. According to the findings of the inventor, there has long been a need for a level measuring device, suitable for ensuring better monitoring of the hydrocarbon filling of the separator compartment.

The object of the present invention is to overcome the aforementioned drawbacks of the prior art level detection devices of the hydrocarbon separators by proposing a device suitable for the level measurement of an aqueous fraction in an enclosure intended to receiving two separate liquid fractions, namely an aqueous fraction, and a lower density light fraction, located above the aqueous fraction.

Another object of the present invention is to provide such a measuring device, which, at least according to one embodiment is easy to install and allows integration into equipment, such as an oil / water separator, renovation.

Another object of the present invention is to provide an oil / water separator equipped with such a measuring device.

Another object of the present invention is to provide a method of monitoring the filling of an enclosure in a light fraction, intended to receive two separate liquid fractions, namely an aqueous fraction, and the light fraction of lower density, greater than the aqueous fraction, implemented by a measuring device according to the invention.

Another object of the present invention is to provide a remote monitoring system, liquid level comprising one or more devices) according to the invention, or even one or more separators according to the invention, which allows advantageously to the manager of these equipment to optimize the maintenance schedule and the mobilization of vehicles required for this maintenance. Other purposes and advantages of the description will become apparent from the following description which is given for information only and which is not intended to limit it. The invention firstly relates to a measuring device suitable for measuring the level of an aqueous fraction in an enclosure intended to receive two separate liquid fractions, namely an aqueous fraction, and a light fraction of lower density, located above the aqueous fraction, said measuring device comprising: - a float system, tared so as to follow the changes in the level of the aqueous fraction / light fraction interface, - a measurement sensor, targeting the displacement at the climbing or lowering said float system in said enclosure, delivering a signal, analog or digital, representative of the position of the float in said enclosure.

According to one embodiment, the float system comprises a shutter, movable, rigidly secured to the float, the shutter closing at least one discharge opening of the enclosure, in the lower position of the shutter.

According to one embodiment, the measuring sensor is a cable-type linear displacement sensor, comprising: a cable whose end is connected to said float; a rotating drum, around which the cable is able to wind under the cable; stress of a return spring, or to take place under the action of an external constraint, against the restoring force of the spring, - an encoder or a potentiometer targeting the rotation of the drum relative to a support fixed, delivering the measurement signal.

According to another alternative embodiment, the measuring sensor comprises: - a sealed envelope, such as a sealed tube, intended to be immersed in the liquid fractions received said enclosure, and whose internal volume constitutes a dry chamber, - a device measurement transfer comprising a mechanical transmission connecting the displacement of the float to the displacement of a witness, movable in said dry chamber, - said measuring sensor being contactless, in particular ultrasound or laser, able to measure a distance, targeting the control in said dry chamber, and in such a way that the sensor emits a proportional signal representative of the distance separating the control from said sensor, and thus, representative of the position of the float in said enclosure.

The mechanical transmission may comprise a pulley system (s) and flexible connection, said flexible connection connecting the float system, on the one hand, with said witness and a counterweight, internal to the dry chamber, on the other hand. The counterweight ensures the tensioning of the length section of said flexible connection connecting the float system, on the one hand, and the control / counterweight assembly, on the other hand. The device may comprise a frame supporting said mechanical transmission, including the float and said witness, the probe, as well as said sealed envelope, and so that the chassis, mechanical transmission, float / witness and sealed envelope assembly constitute a self-supporting assembly .

According to one embodiment, the float system, namely the float, or optionally the float and shutter assembly, has a density of between 0.95 and 0.99. The invention also relates to an oil-water separator comprising a dewatering compartment, and a separator compartment, the two compartments communicating with each other via a device ensuring the separation by coalescence. According to the invention, the oil / water separator comprises a measuring device according to the invention received in said enclosure formed by the separator compartment.

According to optional features of the oil / water separator, taken alone or in combination: - the separator compartment communicates with the outside via an automatic shutter system; - The automatic shutter system comprises the shutter, mobile fixed to the float of the measuring device according to the invention. The invention also relates to a method of monitoring the filling of an enclosure in a light fraction, intended to receive two separate liquid fractions, namely an aqueous fraction, and a light fraction of lower density, located above the fraction aqueous, implemented by a measuring device according to the invention internal said enclosure, said method comprising at least a first step of measuring the position of the float by reading the signal emitted by the sensor.

According to one embodiment, the method may comprise a second step of determining the thickness of the light fraction, starting from the measurement of the first step.

For example, the method may comprise a preliminary calibration step for which a relation is established between the position of the float in said enclosure and the thickness of the coarse fraction, according to the following formula: E = f (Pf) with E. Thickness the coarse fraction,

Pf. The position of the float in said enclosure, f. The function establishes a relationship between the thickness of the coarse fraction and the position of the float. and wherein this relationship is used in the second step for determining the thickness of the light fraction from the measurement of the first step.

The relationship between the position of the float in said enclosure and the thickness of the coarse fraction may be a non-linear relationship.

According to one embodiment, said enclosure communicates with the outside via an automatic shutter system, ensuring the closure of the evacuation when the level of the aqueous fraction / light fraction interface becomes less than one. determined level in said chamber, and in which an emergency warning is triggered when the measurement of the first measurement step is below said determined level.

According to one embodiment of the monitoring method, one or more level thresholds of the aqueous fraction / light fraction interface, intermediate (s) between the high position of the float and the low position of the float corresponding to the closure of the float, are determined. automatic shutter system, and in which a warning or several warnings are triggered when the measurement of the first step is lower than the intermediate threshold (s).

According to one embodiment, the method may comprise a calibration step in which a float upper position threshold is determined which corresponds to the high nominal position of the float Pnh when the chamber is completely filled with the aqueous fraction and a threshold of low position Pnb of the float which corresponds to the position of the float when the automatic shutter system is closed, and in which an alarm is triggered when the measurement of the first measurement step goes beyond the range defined between the low position threshold and the high position threshold of the float. The invention also relates to a liquid level remote monitoring system comprising one or more measuring devices according to the invention, or to one or more separators according to the invention comprising such a measuring device, and wherein the or each measuring device comprises communication means able to transmit to a remote central server a digital signal comprising measurement measurement sensor information.

According to one embodiment, said server is configured to relay the information of the received signal to one or more communication terminals.

According to one embodiment, said central server is connected to a computer processing module configured to analyze said measurement information included in each of the received signals and instructions for implementing the monitoring method according to the invention. The invention will be better understood on reading the following description accompanied by the appended figures, among which: FIG. 1 is a partial view of an oil / water separator according to the invention, according to an embodiment (FIG. measuring device being not illustrated), - Figure 2 is a schematic view of a measuring device according to the invention, according to one embodiment, finding a particular application in the enclosure of the separator compartment of the oil / water separator FIG. 3 is a schematic view of the architecture of the remote monitoring system, according to one embodiment of the invention; FIG. 4 is a schematic view of a measuring device according to FIG. the invention according to a second embodiment, said measurement sensor being a linear displacement sensor cable, - Figure 5 is a view of the device according to Figure 1, in situation in the enclosure of separator compartment, the float of the measuring device floating at the interface between the light fraction of hydrocarbon and the aqueous fraction; - Figure 6 is a graph illustrating the relationship between the thickness of the layer of the light fraction as a function of measuring the position of the float, the graph showing the ordinate the thickness of the light fraction, and the abscissa the position of the float, from its nominal high position for which the enclosure contains only the aqueous fraction, and up to its low nominal position for which the integral shutter of the float automatically closes the evacuation.

The measuring device 1 according to the invention is intended for measuring the level of an aqueous fraction in an enclosure Ec intended to receive two separate liquid fractions, namely an aqueous fraction Wa, and a light fraction Oi, of lower density. , greater than the aqueous fraction. As such, it finds particular application in the separator compartment of an oil / water separator equipment, also called hydrocarbon separator, to monitor the level of the aqueous fraction interface Wa / light fraction Oi. The lower this interface, the more the light fraction gets thicker.

The measuring device 1 comprises: a float system 2 calibrated so as to follow the changes in the level of the aqueous fraction interface Wa / light fraction Oi; a measurement sensor 6; 6 ', targeting the displacement at the climbing or lowering said float system in said enclosure.

The density of the float system 2 may be typically greater than or equal to 0.9 and strictly less than 1, for example between 0.95 and 1, such as for example 0.98 or 0.99. This density allows the float system to be at the interface between the light fraction Oi and the aqueous fraction Wa.

The measurement sensor 6; 6 'has the function of targeting the displacement on the rise (or the descent) of said float system 2, and in order to know its position in the enclosure Ec. For this purpose, the measurement sensor 6; 6 'delivers an analog or digital signal, representative of the position of the float in said enclosure Ec. In the case of an analog signal, it is a proportional signal which, after analysis, makes it possible to distinguish different level positions of said float system 2 in said enclosure.

In the case of a digital signal, and again, it is a progressive information that allows, after analysis, to distinguish different level positions of said float system in said chamber, from the same sensor. In both cases, a sensor resolution is chosen to detect variations preferably less than or equal to 5 cm, preferably less than or equal to 1 cm, such as 0.5 cm.

Such a measuring device finds particular application in the separator compartment of a hydrocarbon separator 20. When this compartment is completely filled in the aqueous fraction, that is to say free of the light hydrocarbon fraction, the float 2 (float system) is in a high nominal position Pnh, typically defined by an overflow of the exhaust system. As the separator traps the hydrocarbons, the light fraction Oi appears above the aqueous fraction Wa and thickens, the light fraction / aqueous fraction interface lowering in said chamber Ec, typically up to at the critical level or a shutter 10 of a closure system 24 automatically closes the evacuation. At this critical level, the float system 2 is in its nominal low position Pnb ·

The measurement sensor 6, 6 'is thus chosen (in particular in terms of resolution) so as to be able to follow the movement of the real position Pf of the float system 2 from this high nominal position Pnh, and to its nominal position. low Pnb- The measuring device, in particular its measuring sensor 6; 6 'can also be designed to detect an abnormal position of the float system 2, namely in particular a position of the float system 2 (slightly) above its nominal high position Pnh, a position which is typically encountered in case This measurement information can then be interpreted as abnormal hydraulic loading of the separator (obstructed output, downstream network overloaded, etc.). Conversely, and in the case where the measurement sensor 6,6 'returns a measurement corresponding to a position of the float system 2 lower than the nominal low position, this information can be interpreted as a total closure, with closure of the shutter beyond its nominal stroke. This over-sealing may be caused by a reason external to the separator (ie accidental spill) or representative of a defect of the separator, such as a shutter sucked to the bottom, or a malfunctioning float, in particular in case the system to float 2 includes the shutter 10 of the automatic shutter system. In this case, the float system 2 can not physically descend below this low nominal position Pnb during normal operation.

For example, and according to an embodiment illustrated for information in Figure 1, said measuring device 1 according to the invention comprises: - said float system 2, - a dry chamber 3, and a control 4, internal to said dry chamber 3, - a measurement transfer device comprising a mechanical transmission 5 connecting the movement of the float to the movement of the control 4 in said dry chamber 3, - the measurement sensor 6, which is non-contact, able to measure a distance, targeting the control in said dry chamber 3.

According to this embodiment, the measurement sensor 6 is a non-contact measurement device, for example of the ultrasonic type, or laser, ATEX. This measurement sensor is fixed, and makes it possible to measure a distance that varies when the float system 2 is lowered (or mounted) in the chamber: this sensor 6 does not directly target the float system, which can be covered with the light fraction, but a control 4 which is received in the dry chamber adapted to this measurement without contact, this chamber being traversed by the ultrasound of the ultrasonic sensor, or by the laser beam in the case of a sensor operating a measurement by laser.

According to one embodiment, this dry chamber can be returned into the chamber by the insertion of a sealed envelope 7, such as a sealed tube, intended to be immersed in the liquid fractions received said enclosure Ec, and whose internal volume constitutes the dry chamber 3.

The measurement transfer device comprises a mechanical transmission 5 whose function is to link the displacement of the control 4 in said dry chamber 3 to the displacement of the float system 2. Thus the displacement of the control 4 in the dry chamber 3 is representative of the displacement float in the enclosure: the mechanical transmission connects the float and the witness so that the movements are proportional to each other, for example identical (that is to say, a ratio 1/1). This ratio of proportionality then makes it possible, by calculation, to know the variation of the float system 2 from the knowledge of the position of the control 4 in the dry chamber 3, measured by the sensor 6. The sensor 6 thus emits a representative signal the distance separating the indicator 4 from the probe 6, and therefore the position of the float 2 in said enclosure Ec.

The measurement sensor 6 is configured so as to obtain as a measurement signal a proportional (or progressive) information, that is to say allowing the knowledge of the position of the indicator 4, (and therefore of the float 2 by measurement transfer), in different intermediate positions between, at least from the high nominal position of the float system 2, on the one hand, and the low nominal position of the float system 2, on the other hand. The mechanical transmission 5 may, by way of example, comprise a system with pulleys and flexible connection, said flexible connection such as a cable connecting the float 2 of the float system 2, on the one hand, with said control 4 and a counterweight 8 , on the other hand, internal to the dry chamber 3. The counterweight ensures the tensioning of the length section of said flexible connection connecting the float 2, on the one hand, and the control / counterweight assembly 4,8, on the other hand.

The pulleys guide and suspend the flexible link, minimizing friction. According to this embodiment, and when the float system 2 descends, according to a certain stroke in the chamber following the level of the aqueous fraction / light fraction interface, the control and the counterweight rise together in a race, in particular identical, in the dry chamber 3. As illustrated by way of example in Figure 1, the counterweight 8 and the control 4 can be constituted by the same element, for example in the form of a horizontal disc.

According to one embodiment, the measuring device 1 may be constituted by a self-supporting assembly, and so as to facilitate the installation of the measuring device in said enclosure, by the installation and attachment of an element of a single taking. Such a design also facilitates a pose in renovation. For this purpose, and according to one embodiment, the device comprises a frame 9 supporting said mechanical transmission 5, including the float 2 and said witness 4, the probe 6, as well as said sealed envelope 7, and so that the assembly - chassis, mechanical transmission, float / witness and sealed envelope - constitutes a self-supporting assembly meeting this objective.

According to an alternative embodiment, the measuring sensor 6 'may be a linear displacement sensor of the cable type, comprising: a cable 61 whose end is connected to said float 2 (float system 2), a drum 62 rotatable, around which the cable is able to wind under the constraint of a return spring, or to take place under the action of an external stress, against the return force of the spring, - an angular encoder (or a potentiometer) targeting the rotation of the drum relative to a fixed support, delivering the measurement signal.

Such an embodiment with a linear displacement sensor of the cable type is illustrated by way of non-limiting example in FIGS. 4 and 5.

According to this embodiment, the rotary drum and its support are fixed, in particular in the separator above the liquid levels, the end of the cable being connected to the float system 2, in particular directly to the float 2.

When the float system 2 descends, the latter pulls on the cable 61 and causes the unwinding of the cable 61 and thus the rotation of the drum 62 in the unwinding direction, against the restoring force of the spring. Conversely, and if the float system 2 rises, the return spring causes the winding of the cable on the drum 62, and thus the rotation of the drum 62 in the winding direction. The potentiometer (or the linear digital encoder) targets this rotation, and thus makes it possible to deduce the vertical displacement of the float system 2, on the ascent or descent.

Such linear cable displacement sensors are known per se, for example marketed by the company SCAIME (http://www.scaime.eom/y The invention also relates to an oil / water separator 20 having at least one separator compartment 22 in which the measuring device 1 according to the invention is integrated.

The separator 20 may be of the type comprising a dewatering compartment 21, and the separator compartment 22, the two compartments 21,22 communicating with each other via a device 23 ensuring the separation by coalescence. This device 23 may be a honeycomb structure, for example with hexagonal mesh. The scrubber compartment 21, precedes the separator compartment 22, according to the flow direction of the liquids.

The separator compartment 22 communicates with the outside via an automatic shutter system 24, ensuring the closure of the discharge when the level of the aqueous fraction / light fraction interface becomes lower than a determined level. The position of this evacuation in the chamber is located in a lower position, and so as to avoid the inadvertent release of oil. According to one embodiment, the automatic shutter system 24 comprises the shutter 10, movable integral with the float 2 of the measuring device 1. Thus, the float 2 used in the measuring device 1 may be the same as that forming part An automatic shutter system 24. The maximum liquid level in the separator compartment 22 may be defined by an overflow of the exhaust.

Thus, and generally for the measuring device 1, and according to one embodiment, the float 2 is integral with a shutter 10, movable, closing at least one discharge opening of the enclosure Ec, in the position low shutter. Such an embodiment illustrated in Figure 1 comprises the float 2 and the shutter 10, disposed below the float, the shutter being secured to the float by means of a rod. The invention also relates to a method of monitoring the filling of an enclosure Ec in a light fraction, intended to receive two separate liquid fractions, namely an aqueous fraction, and a light fraction of lower density, located above the aqueous fraction.

This method is implemented by a measuring device according to the invention, internal to said enclosure Ec. According to the invention, the method comprises at least a first step of measuring the position of the float of the float system by reading the signal emitted by the sensor 6 or 6 '.

According to one embodiment, the method may comprise a second step of determining the thickness of the light fraction, starting from the measurement of the first step. In particular, the method may comprise a prior calibration step for which a relation is established between the position of the float (float system) in said enclosure and the thickness of the coarse fraction, according to the following formula: E = f (Pf ) with E. Thickness of the coarse fraction,

Pf. The position of the float in said enclosure.

The function f establishes a relation between the thickness of the coarse fraction and the position of the float. This relationship is then used in the second step for determining the thickness of the light fraction from the measurement of the first step. The calibration step may consist essentially in voluntarily filling the separator compartment 22 in the light fraction, and in consecutive additions of determined volumes. With each addition of hydrocarbon, the position Pf of the float system 2 measured is read and recorded. By proceeding in this manner, the inventor has discovered that the relationship between the displacement of the float system 2 and the thickness of the light fraction is not strictly linear. In particular, and at the beginning of the filling, the inventor found that the float system 2 did not descend, but could go up slightly, and as illustrated in FIG. 6. According to the inventor's observations, this relationship Linear was found, as long as the float 2 is not completely covered by the light hydrocarbon fraction. Past this phenomenon, the relationship approaches a linear relationship and can be simplified as it is.

Thus and according to one embodiment, said relationship between the position of the float system in said enclosure and the thickness of the coarse fraction may be a non-linear relationship. The determination of the thickness of the light fraction can be obtained from the position Pf by the implementation of a nonlinear regression.

According to one embodiment, said enclosure communicates with the outside via said automatic shutter system 24, ensuring the closure of the evacuation when the level of the aqueous fraction / light fraction interface becomes less than a level. determined in said enclosure. According to one embodiment, an emergency warning is triggered when the measurement of the first measurement step is less than said determined level.

According to one embodiment, one or more level thresholds of the aqueous fraction / light fraction interface, intermediate (s) between the high nominal position Pnh of the float and the nominal low position Pnb of the float corresponding to the closure, are determined. of the automatic shutter system, and in which a warning or several warnings are triggered when the measurement of the first measurement step is less than the intermediate threshold (s).

The creation of one or more intermediate level thresholds, and associated automatic warning (s), may allow the manager to have relevant information on the state of the hydrocarbon separators, and thus allow a optimized management of maintenance. This information makes it possible to schedule the maintenance of the separators, in order to limit their number, and at the very least to limit the travel of the vehicles used to carry out this maintenance. According to one embodiment, the method may provide a calibration step in which a float upper position threshold is determined which corresponds to the maximum nominal position of the float when the chamber is completely filled with the aqueous fraction and a position threshold. float float that corresponds to the float position when the automatic shutter system is closed.

According to the invention, an alarm is triggered when the measurement of the first measurement step is outside the range defined between the low nominal position threshold and the high nominal position threshold of the float. The position Pf of the float 2 above this high nominal position Pnh, namely Pf> PNH + Δ can be interpreted as an overload downstream of the separator compartment, in particular an evacuation problem. Δ here represents a margin of safety, in particular to take into account the behavior of the float at the beginning of filling. On the other hand, if Pf <PNB, this information can be interpreted as a defect of the measuring device or the presence of an accidental spill. The invention also relates to a liquid level remote monitoring system 30 comprising one or more measuring devices according to the invention, or one or more separators) according to the invention comprising such a measuring device. monitoring system according to the invention, each measuring device 1 comprises communication means 31 able to transmit to a remote central server 32 a digital signal comprising measurement information of the measurement sensor 6; 6 '; 6 "The architecture of such a monitoring system is illustrated by way of indicative example in FIG. 3. The communication means may be of the radio type and, for example, use the mobile telephone network, for example according to FIG. GPRS or UMTS standard, to transmit the measurement signal to the central server 32.

The central server 32 collects the measurement data acquired by the sensors 6, 6 ', 6n. It is configured to relay the information of the received signal to one or more communication terminals 33, 34, such as for example a smartphone, or a personal computer. Access to information from the communication terminals 33, 34 can be made via the internet network and a WEB site.

Said central server 32 may be connected to a computer processing module configured to analyze said measurement information included in each of the received signals.

This computer processing module can implement the steps of the monitoring method, namely all or some of the following functions: - determine the thickness of the light fraction, from the measurement information and calibration information specific to the enclosure of the separating equipment in which the measuring device 1 is installed, and / or - generating one or more warning signals (s) when the measurement corresponds to a position of the float 2 in the level enclosure Ec less than a specified intermediate threshold or one of the determined intermediate thresholds, and for which the automatic shut-off system remains open, and / or - generate an emergency warning when the measurement corresponds to a critical level threshold for which the automatic shutter system closes, and / or, - generate a fault alarm, in particular an overload alarm and / or an alarm device fault alarm. when the measurement is outside the range defined between the low nominal position threshold and the high nominal position threshold of the float 2, the range defining the positions of the float 2 during normal operation.

Naturally other embodiments could have been envisaged by the skilled person without departing from the scope of the invention as defined by the claims below.

NOMENCLATURE E Measuring device, 2. Float, 3. Dry chamber, 4. Warning lamp, 5. Mechanical transmission, 6. Measuring sensor (non-contact probe), 6 '. Measuring sensor (Linear displacement sensor with cable) 7. Waterproof enclosure, 8. Counterweight, 9. Frame, 10. Shutter. 20. Oil / water separator, 21. Sludge compartment, 22. Separator compartment, 23. Apparatus providing separation by coalescence, 24. Automatic shut-off system, 30. Remote monitoring system, 31. Means of communication, 32. Central server, 61. Cable (Sensor 6 '), 62. Drum (Sensor 6'),

Ec. Pregnant.

Wa: Water fraction Oi: Light fraction

Pnb: Low nominal position (float system)

Pnh: High nominal position (float system)

Pf: Actual position of the float E: Light fraction thickness

Claims (20)

CLAIMS E Measuring device (1) suitable for measuring the level of an aqueous fraction in an enclosure (Ec) intended to receive two separate liquid fractions, namely an aqueous fraction, and a light fraction of lower density, located at above the aqueous fraction, said measuring device (1) comprising: - a float system (2) calibrated so as to follow the changes in the level of the aqueous fraction / light fraction interface, - a measurement sensor, targeting the upward or downward movement of said float system in said enclosure (Ec), delivering an analog or digital signal, representative of the position of the float in said enclosure (Ec). 2. Device according to claim 1, wherein the float system (2) comprises a shutter (10), movable, rigidly secured to the float (2), the shutter (10) closing at least one discharge opening of the speaker (Ec), in the low position of the shutter. 3. Device according to claim 1 or 2, wherein the measuring sensor (6 ') is a linear displacement sensor of the cable type, comprising: - a cable whose end is connected to said float - a rotating drum, around which the cable is able to wind under the constraint of a report spring, or to unwind under the action of an external stress, against the restoring force of the spring, - an encoder or a potentiometer targeting the rotation of the drum relative to a fixed support, delivering the measurement signal 4. Device according to claim 1 or 2, comprising - a sealed envelope (7), such as a sealed tube, intended to be immersed in the liquid fractions received said enclosure (Ec), and whose internal volume is a dry chamber (3), - a measurement transfer device comprising a mechanical transmission (5) connecting the displacement of the float (2) to the displacement of a witness (4), movable in said dry chamber (3), - said measuring sensor being non-contact, in particular ultrasonic or laser, able to measure a distance, targeting the control in said dry chamber (3), and in such a way that the sensor (6) emits a proportional signal representative of the distance separating the control (4) said sensor (6), and thus, representative of the position of the float (2) in said enclosure (Ec). 5. Device according to claim 4, wherein the mechanical transmission (5) comprises a pulley system (s) and flexible connection, said flexible connection connecting the float (2), on the one hand, with said witness (4) and a counterweight (8), internal to the dry chamber, on the other hand, the counterweight ensuring the tensioning of the length section of said flexible connection connecting the float (2), on the one hand, and the control assembly / counterweight (4,8), on the other hand. 6. Device according to one of claims 4 or 5, comprising a frame (9) supporting said mechanical transmission (5), including the float (2) and said witness (4), the probe (6), and said sealed envelope (7), and so that the frame assembly, mechanical transmission, float / witness and sealed envelope constitute a self-supporting assembly. 7. Device according to one of claims 1 to 6, wherein the float system, namely the float (2) or optionally the float assembly (2) and shutter (10) is of density between 0.95 and 0.99. 8. separator (20) oil / water comprising a scrubber compartment (21), and a separator compartment (22), the two compartments communicating with each other via a device (23) providing separation by coalescence, characterized in it comprises a measuring device (1) according to one of claims 1 to 7 received in said enclosure (Ec) formed by the separator compartment (22). 9. Oil / water separator according to claim 8, wherein the separator compartment (22) communicates with the outside through an automatic shutter system (24), ensuring the closure of the discharge when the level of the aqueous fraction / light fraction interface becomes below a certain level. 10. Oil / water separator according to claim 9, wherein the automatic shutter system (24) comprises the shutter (10) movable integral with the float (2) of the measuring device (1) according to claim 2. 11. A method for monitoring the filling of an enclosure in a light fraction, intended to receive two separate liquid fractions, namely an aqueous fraction, and a light fraction of lower density, located above the aqueous fraction implemented. by a measuring device according to one of claims 1 to 7 internal to said enclosure, said method comprising at least a first step of measuring the position of the float by reading the signal emitted by the sensor (6; 6 '). 12. The monitoring method according to claim 11 comprising a second step of determining the thickness of the light fraction, from the measurement of the first step. 13. The monitoring method as claimed in claim 12, comprising a prior calibration step for which a relationship is established between the position of the float in said chamber and the thickness of the coarse fraction, according to the following formula: E = f (Pf) with E. Thickness of the coarse fraction, Pf. The position of the float in said enclosure, f. The function establishing a relationship between the thickness of the coarse fraction and the position of the float. and wherein this relationship is used in the second step for determining the thickness of the light fraction from the measurement of the first step. 14. The monitoring method according to claim 13, wherein said relationship between the position of the float in said enclosure and the thickness of the coarse fraction is a non-linear relationship. 15. Monitoring method according to one of claims 11 to 14 wherein said enclosure communicates with the outside through an automatic shutter system (24), ensuring the closure of the evacuation when the level of the aqueous fraction / light fraction interface becomes lower than a determined level in said chamber, and in which an emergency warning is triggered when the measurement of the first measurement step is below said determined level. 16. The monitoring method according to claim 15, wherein one or more level thresholds of the aqueous fraction / light fraction intermediate interface between the high position of the float and the lower position of the float corresponding to the shutter of the automatic shutter system, and in which a warning or several warnings are triggered when the measurement of the first measurement step is less than the intermediate threshold (s). 17. The monitoring method according to one of claims 11 to 16, having a calibration step in which is determined a float upper position threshold which corresponds to the high nominal position of the float (Pnh) when the chamber is completely filled. of the aqueous fraction and a low position threshold (Pnb) of the float which corresponds to the nominal position of the float when the automatic shutter system is closed, and in which an alarm is triggered when the measurement of the first measurement step leaves the range defined between the low nominal position threshold (Pnb) and the nominal high position threshold (Pnh) of the float. 18. System (30) for remote monitoring of liquid level comprising one or more measuring devices according to one of claims 1 to 7, or one or more separator (s) according to one of claims 8 to 10. comprising such a measuring device according to one of claims 1 to 7, and wherein the or each measuring device comprises communication means (31) adapted to transmit to a remote central server (32) a digital signal comprising information measuring the probe (6; 6 '; 6n). The system of claim 18, wherein said server is configured to relay the received signal information to one or more communication terminals (33, 34). 20. The system of claim 18 or 19, wherein said central server (32) is connected to a processing computer module configured to analyze said measurement information included in each of the received signals and instructions for the implementation of the method of monitoring according to any one of claims 11 to 17.