Apparatus for measuring an internal heat-transfer coefficient of a liquid medium, method for implementing such an apparatus and modelling of said coefficient

Abstract

The invention relates to a measuring apparatus comprising a probe (12) having a part (12a) that can be immersed in a reaction medium, which part is equipped with a member (15) for heating a first area (15a) of the probe (12) in which a first temperature-measuring member (16) is placed. A second temperature-measuring member (17) is placed in a second area (15b) of the probe (12) at a distance (D1) from the first area (15a). The first measuring member (16) and the second measuring member (17) deliver the value of a temperature difference between the first area (15a) and the second area (15b) of the probe (2) to a unit (13) for identifying the value of an internal heat-transfer coefficient of the reaction medium based on the temperature difference.

Description

DESCRIPTION APPARATUS FOR MEASURING AN INTERNAL HEAT TRANSFER COEFFICIENT OF A LIQUID MEDIUM, METHOD FOR IMPLEMENTING SUCH AN APPARATUS AND MODELING OF SAID COEFFICIENT. TECHNICAL FIELD

[0001] The invention relates to the field of identifying the thermal characteristics of a medium in the liquid state, such as a reaction medium during its reaction. More specifically, the invention relates to the laboratory determination of the value of the internal heat transfer coefficient of said medium during its reaction within a reaction calorimeter. The invention is particularly relevant, but not limited to, the application of thermal characteristics from a reaction calorimeter used in the laboratory to a larger-volume reactor, such as an industrial reactor—a pilot reactor or a reactor for the production of a chemical compound. STATE OF THE ART

[0002] It is common practice to evaluate and analyze in the laboratory the thermal reaction of a reaction medium contained within a double-jacketed reaction calorimeter. The calorimeter's double jacket consists of a peripheral shell and an inner shell that forms a reaction chamber containing the reaction medium. A thermal regulation chamber for the reaction medium is located between the peripheral and inner shells of the calorimeter. A heat transfer fluid circulates within this chamber to regulate the temperature of the reaction medium to a set temperature during its reaction. The inner shell, which forms the reaction chamber, has two faces: an inner face facing the inside of the chamber—that is, the reaction medium—and an outer face facing the thermal regulation chamber—that is, the heat transfer fluid.

[0003] The reaction medium, typically in a more or less dense liquid state and generally comprising at least one reactant and frequently also at least one solvent, is stirred during its reaction within the reaction vessel to promote homogeneity. A heat transfer fluid—usually a thermal oil—circulates within the control chamber to regulate the temperature of the reaction medium to the setpoint temperature during the reaction.

[0004] The reaction calorimeter is commonly used to measure the thermal power of the double jacket and deduce the thermal power of the chemical reaction of the reaction medium. From the results obtained in the laboratory with a reaction calorimeter, the aim is then to transpose them to the scale of an industrial reactor – such as a pilot reactor or a reactor producing the chemical compound to be produced – or in other words, to the product obtained at the end of the reaction of the reaction medium.

[0005] To this end, various calorimetry methods exist. For example, it is known to evaluate the overall heat transfer coefficient between the double jacket and the reaction medium using a heating element placed in the reaction medium outside of its active reaction phases. This allows for the calibration of the overall heat transfer coefficient between the reaction medium and the double jacket. With this overall heat transfer coefficient and the temperature measurements of the reaction medium and the double jacket as a function of time, it is possible to calculate the thermal power passing through the reactor jacket. However, this method only measures the overall heat transfer coefficient intermittently and outside of the reaction phases of the reaction medium. This results in a significant uncertainty in the actual measurement of the reaction power.

[0006] Another method disclosed in document FR2840986 uses heat flux sensors to measure the heat flow through the double jacket. This measurement allows the thermal power at the double jacket to be determined, and the thermal power of the reaction to then be calculated. chemical as a function of time. Despite the interest of such a measurement, it nevertheless provides no information regarding the value of the overall exchange coefficient.

[0007] It generally emerges that commonly used calorimetry methods do not provide reliable and precise information specifically regarding the internal heat transfer coefficient of the reaction medium. However, to estimate this overall heat transfer coefficient in an industrial reactor, it is necessary to have a reliable estimate of the internal heat transfer coefficient, which corresponds to the heat exchange between the reaction medium and the inner face of the reactor's inner shell, oriented towards the reaction medium. DESCRIPTION OF THE INVENTION

[0008] One object of the invention is to predict the temperature of the double jacket of an industrial reactor as a function of time during a chemical or physical reaction of a reaction medium contained inside the industrial reactor, and this in the context of a transfer of a chemical synthesis process from data obtained in the laboratory in a reaction calorimeter.

[0009] The invention aims in particular to exploit the identification of the value of the internal heat exchange coefficient of the reaction medium during its reaction from data obtained in the laboratory in a reaction calorimeter, to size an industrial reactor - in particular with regard to the thermal regulation system with which it is equipped - and / or to adjust the parameters of the chemical synthesis process carried out inside the industrial reactor, such as for example the flow rate of the reagent, the speed of stirring of the reaction medium and / or the dilution of the reagent in the reaction medium.

[0010] It is understood here, however, that this purpose is not exclusive to the use of a measuring device and / or its implementation method within the scope of the invention, in another framework of use aimed in its generality at identifying the internal heat transfer coefficient of any medium, such as in particular a liquid medium, whose temperature may vary according to its external environment and which must be regulated to a setpoint temperature.

[0011] Thus, in order to appreciate a specific application without being exclusive of the invention, the objects of the invention are presented here in the appropriate context of a reaction medium contained in the laboratory in a said tank of a reaction calorimeter, with a view to transposing the tests carried out in the laboratory to an industrial reactor producing a predefined chemical compound.

[0012] In light of the foregoing, the objects of the invention are at least the following: -) a measuring device enabling the identification of the value of the internal heat transfer coefficient of a medium, such as a reaction medium, or in other words the internal heat exchange coefficient between the reaction medium and the inner face of a double jacket of a reaction calorimeter used in a laboratory, said inner face being oriented towards the interior of the reaction calorimeter vessel containing said medium, in particular a reaction medium, -) a said reaction calorimeter providing a said receiving tank for a said medium, the reaction calorimeter being equipped with the said measuring device; -) a method for determining said internal heat transfer coefficient of a medium using said measuring device, and -) a model for identifying said internal heat transfer coefficient that can be implemented in a sizing and process control program for implementing said industrial reactor - pilot reactor or production reactor for a predefined chemical compound to be obtained.

[0013] The findings on which the invention is based are introduced here.

[0014] It is assumed that the overall heat transfer coefficient between the reaction medium and the thermal fluid is such that: P = Uglobal x A x (Tm - TDE). In this equation, P is the thermal power transferred between the reaction medium and the thermal fluid, Uglobal is the overall heat transfer coefficient between the reaction medium and the thermal fluid, A is the heat exchange surface area between the inner wall of the calorimeter enclosure and the reaction medium, Tm is the temperature of the reaction medium and TDE is the temperature of the thermal fluid.

[0015] Now, the said overall exchange coefficient Uglobal (also referred to below as UG) between the reaction medium and the thermal fluid is composed of three terms: -). The first term - designated hint - defines the internal heat exchange between the reaction medium and the inner face of the reactor jacket. -) The second term – designated ep / Lambdap – defines the heat exchange through the reactor's inner shell. More specifically, this second term identifies the thickness ep of the wall delimiting the vessel divided by the thermal conductivity Lambdap of said wall. -) The third term - designated HDE - determines the heat exchange between the internal envelope of the reaction calorimeter and the thermal fluid circulating inside said regulating chamber.

[0016] These three terms are linked, and it is possible to decompose the overall heat exchange coefficient between the reaction medium and the thermal fluid according to the following equation: Episode 1 UG ~ Hint Lambdap + HDE where UG is said overall heat transfer coefficient expressed in W / m 2°C, hint is the internal heat transfer coefficient, ep is the wall thickness expressed in m, Lambdap is the thermal conductivity expressed in W / m°C, and HDE is the heat transfer coefficient of the double envelope expressed in W / m 2 °C.

[0017] However, in this context, a problem arises in how to extrapolate laboratory results obtained using a reaction calorimeter to an industrial reactor. The internal heat transfer coefficient is very difficult to determine because it depends on numerous factors, including the viscosity and thermal conductivity of the reaction medium, its density, and its evolution during the reaction. Consequently, it is not possible to directly use an overall heat transfer coefficient measured at a single point on a reaction calorimeter to determine this coefficient. of global exchange on an industrial reactor from a transposition of the results obtained in the laboratory in a reaction calorimeter.

[0018] It can be accepted that the aforementioned terms relating to heat exchange through the reactor's inner shell and to heat exchange between the reaction calorimeter's inner shell and the heat transfer fluid circulating within the control chamber are terms whose values ​​are easily identifiable. However, their consideration alone is insufficient to identify, in the laboratory, the internal heat transfer coefficient of the reaction medium in a reaction calorimeter reactor, without also taking into account the internal heat transfer coefficient of the reaction medium contained within the reactor vessel.

[0019] Indeed, the internal heat transfer coefficient is a crucial parameter for controlling the exothermicity of the reaction medium during its reaction. Furthermore, it has been observed that the value of this parameter can be used to determine the heat exchange between the reaction medium and the temperature control system within an industrial reactor. However, as previously mentioned, the value of the internal heat transfer coefficient of the reaction medium and its evolution during the reaction are difficult to determine precisely.

[0020] Consequently, it is common practice for professionals to estimate the overall heat transfer coefficient of the reaction medium by guesswork, based on the known characteristics of the reactant(s) and / or solvent(s) used in the reaction medium. As a result, the accuracy and reliability of the estimated value of the overall heat transfer coefficient of the reaction medium are affected.

[0021] This leads to disadvantages, such as: -) an oversizing of the industrial reactor cooling unit for safety reasons, -) a decrease in the reagent flow rate leading to a decrease in process productivity, -) an increase in the dilution of the reaction medium further affecting the productivity of the process.

[0022] The conclusion is that transposing the results obtained in the laboratory in a reaction calorimeter to the scale of an industrial reactor does not allow - without taking into account a precise value of the internal heat transfer coefficient of the reaction medium - to develop a mathematical model sufficiently relevant to define in particular a simulation of a sufficient without being excessive sizing of the industrial reactor - particularly with regard to the thermal unit with which it is equipped - and / or an adjustment of the parameters of the chemical synthesis process, and / or the speed of stirring of the reaction medium and / or the dilution of the reactant in the medium, as previously mentioned as an example.

[0023] Based on and in light of the observations presented above, the present invention proposes to measure, in real time and continuously in the laboratory, the internal heat transfer coefficient of a reaction medium inside the vessel of a reaction calorimeter. This will ultimately allow for the evaluation of the internal heat transfer coefficient of said reaction medium inside an industrial reactor and, consequently, the calculation of the temperature of the double jacket of an industrial reactor as a function of time during the reaction of the reaction medium produced inside the industrial reactor vessel.

[0024] More specifically, the invention proposes to develop in the laboratory in a reaction calorimeter a device for measuring the internal heat exchange coefficient of the reaction medium, the measurement being carried out specifically and exclusively inside the reaction medium during its reaction in the laboratory inside the tank of a reaction calorimeter.

[0025] Then, the data provided in the laboratory via the measuring device are used to develop a reliable and relevant model for identifying the internal heat transfer coefficient itself, one that is suitable for use by an industrial reactor while overcoming the previously mentioned drawbacks. This model can also be used to simulate the temperature of the double jacket of said reactor. industrial reactor, allowing the process of putting a reaction medium into reaction to be adapted to an existing industrial reactor.

[0026] To achieve this, according to a comprehensive presentation of the invention, the invention proposes—here summarized—a measuring device comprising essentially a probe that transmits, in particular, data on temperature differences of an immersible portion of the probe within a reaction medium during its reaction, to a unit that identifies the temperature difference of said immersible portion of the probe based on the data provided to said unit by the probe. From the value of said temperature difference of the immersible portion of the probe identified by said unit, the unit is capable of determining the value of the internal heat transfer coefficient of the reaction medium.

[0027] It should be noted from the outset that, incidentally, the measuring device may also include an auxiliary temperature sensor, which may be immersed directly in the reaction medium or—preferably—with which the probe is equipped. This auxiliary temperature sensor transmits the temperature of the reaction medium itself to the unit, advantageously refining the accuracy of the value of the internal heat transfer coefficient of the reaction medium, determined by the unit from the value of the temperature difference of the immersible portion of the probe identified by the unit.

[0028] To this end, a first zone of the probe's submersible portion is subjected to a temperature increase by a very low-power heating element. A second zone of the probe's submersible portion is located a short distance from the first zone subjected to a temperature increase by the heating element.

[0029] Temperature measuring devices in the first and second zones respectively transmit to the unit—for example, via electrical signals—the temperature difference between the first and second zones of the probe's submersible portion, and consequently, the temperature difference between the first and second zones of the probe's submersible portion. The unit then generates an electrical signal. proportional to the internal heat transfer coefficient of the reaction medium in which the submersible part of the probe is immersed, at least along its extension comprising said first zone and said second zone.

[0030] Thus, from the said temperature difference of the immersible part of the probe and secondarily by correlation with a measurement of the temperature of the reaction medium via said auxiliary temperature sensor carried out simultaneously in real time and continuously during the reaction of the reaction medium inside a reaction calorimeter, a reliable and precise value of the internal heat transfer coefficient of the reaction medium can be identified and then advantageously modeled.

[0031] Such a model can then be implemented in a simulation program for an industrial process involving the reaction of a reaction medium within an industrial reactor. This provides access to the overall heat transfer coefficient of a previously identified industrial reactor, taking into account the value of the internal heat transfer coefficient of the reaction medium as determined by laboratory modeling. This notably allows for a real-time estimation of the temperature of the double jacket to be applied to an industrial reactor.

[0032] The probe comprises a portion that is immersed in the reaction medium and features an architecture and operating principles that directly provide the measuring unit with the missing data. This allows the measuring unit to determine the internal heat transfer coefficient of the reaction medium in real time and continuously throughout the reaction process. This prediction, through modeling, will enable the sizing of heating and cooling units for industrial reactors, and also, for example, the specific modulation of the design process parameters and / or the implementation process of the industrial reactor so that the model can be effectively applied to a previously identified industrial reactor.

[0033] In other words, according to the previously indicated application of the invention in the context of the sizing and / or implementation process of a reactor Based on industrial tests carried out in the laboratory in a reaction calorimeter, the invention synthetically proposes a measuring device of simple and yet reliable structure, capable of identifying the value of the internal heat transfer coefficient of a reaction medium from temperature measurements carried out exclusively inside the reaction medium during its reaction inside the vessel of a reaction calorimeter.

[0034] Then, based on the identified value of the internal heat transfer coefficient of the reaction medium, a mathematical model is developed to determine its value. Such a mathematical model can then be easily implemented in a design program for an industrial reactor, minimizing the risk of oversizing the thermal unit with which it is equipped. This model can also be used to simulate the temperature of the double jacket in an industrial reactor, allowing the process to be adapted to an existing industrial reactor for a predefined chemical compound to be produced.

[0035] To illustrate this more precisely, the invention proposes a measuring device comprising a probe which houses—within a submersible portion of an elongated extension probe immersed vertically in a reaction medium contained in a reaction calorimeter vessel—temperature measuring elements that identify a temperature difference in the submersible portion of the probe between two distant zones. One of these distant zones is subjected to a slight temperature increase via a heating element located within it.

[0036] A first temperature measuring element is placed in thermal contact with the first zone and therefore with the heating element. A second temperature measuring element is placed in thermal contact with the second zone, which is located at a distance from the first zone. Consequently, the second temperature measuring element is not affected by the temperature rise produced by the heating element in the first zone of the probe. It follows that the second zone of the probe's submersible portion is not heated by at least one of the probe's heating elements.

[0037] Alternatively, as previously mentioned, the measuring device may also include an auxiliary temperature sensor for measuring the temperature of the reaction medium. Such an auxiliary temperature sensor may be an additional temperature sensor directly immersed exclusively in the reaction medium or, more advantageously, a secondary sensor fitted to the probe, preferably installed inside the lower end of the probe's immersible portion, which is blind-ended and preferably located near the second temperature measuring element.

[0038] The measuring device also includes a measuring unit to which are transmitted in real time and continuously during the reaction of the reaction medium, at least the temperature values ​​of the probe respectively detected by said temperature measuring devices and, where applicable - in the event of the presence of said auxiliary temperature sensor - the measurement of the temperature of the reaction medium by said auxiliary temperature sensor.

[0039] It is understood, but if necessary specified, that the probe is arranged and structured to provide the measuring unit exclusively with temperature values ​​to which the probe is subjected in its immerseable part inside the reaction medium, excluding in particular any temperature measurement of the inner face of the tank or of any other faces of the walls constituting the double jacket of the calorimeter.

[0040] At least based on the aforementioned probe temperature values, and secondarily on the temperature of the reaction medium during its reaction as measured by the auxiliary temperature sensor, the measuring unit identifies the temperature difference between the areas located away from the immersible portion of the probe during the reaction of the reaction medium. The identification of this temperature difference by the measuring unit generates an electrical signal that identifies the value of the internal heat transfer coefficient of the reaction medium.

[0041] Where applicable, said temperature difference is advantageously correlated with the temperature value of the reaction medium provided to the measuring unit by said auxiliary temperature sensor, thereby improving accuracy of the value of the internal heat transfer coefficient of the reaction medium identified by the unit of measurement.

[0042] As a non-restrictive guideline, the heating power of the first zone developed by the heating element is in the order of between 0.001 W and 1 W (W: Watt), taking into account the separation distance between the first zone and the second zone of the submersible part of the probe, which as a non-restrictive guideline is in the order of at least 5 mm and more advantageously in the order of at least 1 mm (mm: millimeter), and preferably at most 3 cm (three centimeters).

[0043] These indicative values ​​should be considered in the context of a calorimeter with a tank capacity of approximately 1 L (one liter) to 1.5 L (one and a half liters). It should be noted, however, that the indicated separation distance between the first and second temperature measuring elements is potentially adjustable, taking into account the physicochemical characteristics of the reaction medium and / or the capacity of the reaction calorimeter and / or the separation distance between the first and second zones of the probe's immersible portion.

[0044] At least the first temperature measuring element—and possibly also the second temperature measuring element—may individually comprise sub-measuring elements, particularly in the advantageous case where the first and second temperature measuring elements together form a thermocouple. In other words, structurally, the first and second temperature measuring elements can constitute a temperature sensor formed by a thermocouple.

[0045] However, as previously mentioned, it is preferable to use one or more thermocouples, each forming a first and a second temperature measuring element. In other words, in this case, the constituent sub-elements of the first and / or second temperature measuring elements are formed from thermocouple half-cells. The sub-elements temperatures of the same group cooperating with each other then form the same temperature sensor structured as a thermocouple, with regard to the first measuring element and / or the second measuring element.

[0046] The thermocouple(s) are then connected, each at the cold junctions of the thermocouple(s), to the unit via a wire connection. The ends of the conducting wires located at the cold junctions of the thermocouple are preferably part of the temperature measuring element, which is placed in the first heated zone of the immersible portion of the probe—which extends partially along the length of the immersible portion of the probe—and are connected to the unit via the aforementioned wire connection.

[0047] In the advantageous case where the temperature sensors respectively assigned to the first and second zones of the probe's submersible portion each comprise several thermocouples, the thermocouples of each temperature sensor are individually connected to the unit via the wired connection, specifically at the cold junction points of the thermocouples located within the first heated zone of the probe's submersible portion. This at least optimizes the accuracy of the temperature difference between the first and second zones of the probe's submersible portion.

[0048] In the aforementioned case and according to one embodiment, the probe is equipped in its submersible zone with a set of a plurality of first thermocouple half-stacks placed in the first heated zone and a set of a plurality of second thermocouple half-stacks placed in the second unheated zone of the probe's submersible portion, which is located away from said first heated zone. Each set of thermocouple half-stacks, forming respective thermocouples, is distributed around the submersible portion of the probe, for example, along a circumference, the thermocouples being connected in series and linked to the unit via said wired connection.

[0049] Still in the aforementioned case, and according to another, more advantageous embodiment, each of the temperature sensors—each consisting of a thermocouple—includes a set of thermocouple half-cells. The set of half-cells The thermocouples placed in the second unheated zone are distributed around the circumference of the probe's immersible portion. The thermocouple half-cells placed in the first heated zone of the probe's immersible portion are distributed along the elongated extension of the probe's immersible portion. The thermocouples are individually connected to the unit via the aforementioned wired connection. Furthermore, the distribution of the thermocouple half-cells along the elongated extension of the probe advantageously allows for the evaluation of the reaction medium column's extension within the vessel and, consequently, the identification of the contact surface between the reaction medium and the vessel's inner wall.

[0050] The measuring unit is placed, in particular, at least outside the reaction medium and, more specifically, preferably outside the tank containing the reaction medium. To this end, the submersible part of the probe is extended by an emerging part of the probe outside the reaction medium—and more specifically outside the tank—to secure the measuring unit and the wired transmission of the data provided by the submersible part of the probe to the measuring unit, as well as the connection, via said wired connection, between an external electrical power source and the heating element, which notably consists of an electrical resistance.

[0051] This electrical resistance is advantageously arranged as a film approximately 0.1 mm thick, placed in close contact around the first temperature measuring element. Preferably, the measuring unit is equipped with a configurable device for regulating the electrical power delivered to the heating element, which then regulates the temperature of the first zone of the probe to a setpoint temperature that can vary according to the temperature rise of the reaction medium during its reaction.

[0052] To simplify the layout, organization, and structure of the probe, its deployment methods, and its manufacture, the submersible and emergent portions of the probe preferably extend in a continuous, elongated fashion. However, it is not excluded that the submersible and emergent portions of the probe may extend in divergent directions, taking into account the wired connection, considered more or less flexible, interfaced between said submersible part of the probe and the unit of measurement.

[0053] The emerging part of the probe can directly carry said unit or more advantageously be connected to said unit placed at a distance from the probe, in particular via said wired link, or potentially according to a variant by waves from a transmitter installed on the emerging part of the probe cooperating with a receiver equipping said unit installed at a distance from the emerging part of the probe.

[0054] In other words, the unit is advantageously structured and organized, at least as electronic hardware for real-time and continuous calculation of the value of the internal heat transfer coefficient of the reaction medium during its reaction. From the identification of the value of the internal heat transfer coefficient of the reaction medium, a model for identifying the value of the internal heat transfer coefficient of the reaction medium can be developed, as described later.

[0055] More specifically, the probe is advantageously tubular in shape, incorporating an internal channel housing a support and / or at least partially integrating the components equipping the probe's submersible portion. As a reminder, if clarification is needed, these components include at least one temperature measuring element, at least one second temperature measuring element, the heating element, and one end of the wired connection attached to the support, the other end of which is connected to the unit.

[0056] The probe's tubular wall is made of a very thin material, such as approximately 0.3 mm, and a very small diameter, such as approximately 3 mm. The probe wall has very high thermal conductivity, advantageously being made of a metallic material, such as stainless steel or Hastelloy. The probe's thermal conductivity is further optimized by the thinness of the tubular wall.

[0057] Consequently, the relevance of the temperature data and their evolution during the reaction of the reaction medium, provided to the unit by the first and second temperature measuring elements of the probe's submersible portion, is increased. The temperature difference measurement between the first and second zones of the probe's submersible portion is advantageously correlated with the temperature measurement of the reaction medium during its reaction by the auxiliary temperature sensor, thus providing a more accurate value for the internal heat transfer coefficient identified by the measuring unit.

[0058] The probe's internal channel is blind at the end of the probe's immersible portion, preferably located at the deepest point of the probe's immersible portion within the reaction medium. This effectively seals the channel within the reaction medium, preventing any risk of reaction medium seeping into the probe.

[0059] If necessary, the blind end of the probe can advantageously be used to house, within the probe's submersible portion, the auxiliary temperature sensor, and more specifically, the secondary temperature sensor for measuring the reaction medium that constitutes said auxiliary temperature sensor. Preferably, said secondary temperature sensor is potentially located inside the probe in close proximity to—but not at a distance from—the temperature measuring element of said second zone of the probe's submersible portion.

[0060] In this case, the wired connection is used to transmit the temperature value measured by the secondary sensor to the measuring unit. It should also be noted that this wired connection can be advantageously used to connect the heating element to a power source, particularly an electrical power source, through which the heating element can be powered, potentially providing regulation of its heating temperature.

[0061] The probe's internal channel extends inside the probe from its blind end to its other end, which has a vent. A passage outside the protruding part of the probe, through which the wired connection attached to said support emerges from the probe towards said unit. Said support and the components with which it is equipped are thus protected from any contact with the reaction medium, which is frequently corrosive.

[0062] The submersible part of the probe and at least part of the emerging part of the probe are preferably jointly oriented in extension of each other along the elongated extension of the probe, advantageously forming a monobloc body constituting the probe facilitating the manufacture of the probe and the preferably unidirectional architecture of the support - advantageously formed of a printed circuit - which can thus be easily threaded and installed inside the unidirectional internal channel of the probe from its said outlet towards its blind bottom.

[0063] The printed circuit board advantageously incorporates: -) the temperature measuring devices and, where applicable, said secondary sensor constituting the auxiliary temperature sensor of the reaction medium, -) conductive tracks for electrical signals, providing conductors for at least the temperature data respectively measured by the first temperature measuring device and by the second temperature measuring device, and where applicable, data provided by said secondary sensor, and the electrical power conductor supplying the heating element. Said electrical signal conductors are connected to said wired link, which is fixed to the printed circuit board, at its proximal end, which is its end closest to said unit.

[0064] The support is held in position inside said channel, at least via said at least one first temperature measuring element and said at least one second temperature measuring element - and preferably also via the heating element - which are advantageously fixed inside the internal channel of the probe on its internal face by means of a thermal paste with high thermal conductivity.

[0065] Based on the value of the internal heat transfer coefficient of the reaction medium, identified by this unit, the reaction can be modeled. The model The identification of the value of the heat transfer coefficient of the reaction medium can then be implemented in a sizing program for an industrial reactor - in particular the thermal group with which it is equipped - and for regulating its implementation process, allowing the prediction of the evolution of the temperature of the double jacket during the progress of a reaction and consequently allowing, for example, to control an excessive exothermic reaction of the reaction medium.

[0066] More specifically, the mathematical model is developed from the known equation for the heat transferred from the reaction medium during its reaction to the thermal cooling fluid of the reaction medium, which circulates within the space between the double jacket of the calorimeter. This equation takes the following form: P = Uglobal x Areactor x AT where P is the thermal power transferred between the reaction medium and the thermal fluid, Uglobal is the overall heat transfer coefficient between the reaction medium and the thermal fluid whose temperature is regulated by the thermal cooling or heating system of the thermal fluid equipping the calorimeter, Areactor is the heat exchange surface between the inner wall of the calorimeter enclosure and the reaction medium, and AT is the temperature difference between the reaction medium and the thermal fluid - such as commonly, but not limited to, an oil - contained in the thermal regulation chamber of the calorimeter.

[0067] The known equation for identifying the Ureactor is such that: Episode 1 UG Hint Lambdap HDE where UG - corresponding to Uglobal - is, as previously mentioned, the overall heat transfer coefficient between the reaction medium and the thermal fluid, hint is the internal heat transfer coefficient of the reaction medium, EPreactor is the thickness of the internal wall of the calorimeter enclosure interfaced between the thermal fluid and the reaction medium, Àp is the thermal conductivity coefficient of the material constituting the walls of the enclosure - in particular the internal wall - of the calorimeter, and Hde is the heat transfer coefficient thermal of the thermal fluid circulating inside the thermal system for heating or cooling the calorimeter enclosure via the thermal fluid.

[0068] It is accepted that Aréacteur, EPréacteur, Àp, and HDE are parameters that can be easily determined by those skilled in the art. However, hint—also known as hmr—is an unknown coefficient that varies depending on factors such as the composition of the reaction medium, its viscosity, thermal conductivity, density, and the rate of agitation within the reactor.

[0069] Therefore, as previously presented, an approximation of this hmr value is usually applied according to the known art, with the disadvantage of inducing, as previously mentioned, an oversizing of the thermal heating or cooling system of the thermal fluid with which an industrial reactor is equipped, and / or a decrease in the flow rate of the reagent inducing a decrease in the productivity of the process, and / or an increase in the dilution of the reaction medium further affecting the productivity of the process.

[0070] From the data provided by the measuring device relating to the invention, the equation for the thermal power transmitted by the heating element in the reaction medium can be determined according to the following equation Psonde = Usonde x Asonde x AT, where Psonde is the thermal power dissipated by the probe's heating element, Usonde is the overall heat transfer coefficient of the probe, Asonde is the effective exchange surface area at the heated part of the probe, and AT is the temperature difference between the heated area of ​​the probe and the unheated area of ​​the probe.

[0071] The following equation is also taken into account: Uso which Usonde is - as previously mentioned - the overall heat transfer coefficient of the probe, hmr is the internal heat transfer coefficient of the reaction medium during its reaction which is the value sought, EPsonde is the wall thickness of the tubular probe, Àpsonde (Lambdapsonde) is the thermal conductivity of the material constituting the wall of the probe, and Hintsonde is the heat transfer coefficient between the probe and the heated part of the probe.

[0072] It should be noted that the probe's EP value, related to the probe wall thickness, is relatively low compared to the thermal conductivity Àp of the probe wall material, as previously mentioned. The thermal paste used in the probe is specifically selected from among those with high thermal conductivity, resulting in a high Hint value. Therefore, it is assumed that Usonde is only slightly different from hmr.

[0073] It ultimately emerges that hmr is only slightly different from Psonde / (Asonde x ATsonde), or, after calibration with known reaction media, that hmr is equal to K / ATsonde, where K is a coefficient determined during said calibration. Based on the known factors identifying the aforementioned equation(s) for determining the hmr value, either of these equations can be used in a suitable sizing program for the thermal control system equipping an industrial reactor, to simulate and predict the temperature of the heat transfer fluid circulating inside the reactor's double jacket. The coefficient K advantageously depends on the temperature of the reaction medium in which the measuring probe is immersed.

[0074] In view of the foregoing, the invention relates to a device for measuring the value of the internal heat transfer coefficient of a medium, such as a reaction medium, that is to say the internal heat exchange coefficient between the reaction medium and the inner face of the reaction chamber of a calorimeter. The said measuring device comprises at least: a) a probe, said probe being at least equipped with: *) of at least one heating element of a first zone of a submersible part of the probe which is intended to be immersed within said medium, and *) of at least one first temperature measuring device and at least one second temperature measuring device, the first measuring device a) a temperature measuring element being placed in thermal contact with the first zone of the probe and the second temperature measuring element being placed in thermal contact with a second zone of the submersible part of the probe which is distant from said first zone, said at least one first temperature measuring element and said at least one second temperature measuring element being configured to provide a value relative to a temperature difference between said first zone of the submersible part of the probe and said second zone of the submersible part of the probe, b) a unit for identifying a temperature difference of the submersible part of the probe from the data provided to said unit by said probe, said unit being configured to retrieve the value relative to a temperature difference between said first zone of the submersible part of the probe and said second zone of the submersible part of the probe,and to identify the value of the internal heat transfer coefficient of said medium from a temperature value of the medium and said value relating to a temperature difference between said first zone of the submersible part of the probe and said second zone of the submersible part of the probe.

[0075] Preferably, said at least one first temperature measuring element and said at least one second temperature measuring element are spaced apart from each other on the submersible part of the probe by a distance greater than or equal to 5 mm, such advantageously greater than or equal to 1 cm.

[0076] According to an advantageous embodiment, said at least a first temperature measuring element comprises at least a first thermocouple half-cell and the second temperature measuring element comprises at least a second thermocouple half-cell, said at least a first thermocouple half-cell and said at least a second thermocouple half-cell being constitutive of a thermocouple for measuring said value relative to a temperature difference between said first zone of the submersible part of the probe and said second zone of the submersible part of the probe.

[0077] Preferably, the first temperature measuring device comprises at least two first half-stacks of thermocouples, and the second temperature measuring device comprises at least two second half-stacks of thermocouples, each first half-stack of thermocouple forming a thermocouple with an assigned second half-stack of thermocouple. The thermocouples formed by said at least two first half-stacks of thermocouples and said at least two second half-stacks of thermocouples respectively being connected in series.

[0078] According to one embodiment, the first temperature measuring element and the second temperature measuring element are respectively a first temperature sensor and a second temperature sensor arranged to provide a temperature respectively of the first zone and the second zone of the submersible part of the probe.

[0079] Preferably, the heating element is configured to transfer heat into the first zone of the submersible portion of the probe, this first zone being substantially elongated and intended to have a vertical orientation within the medium. The first temperature measuring element comprises a plurality of sub-measuring elements arranged to extend along the first zone of the submersible portion of the probe.

[0080] In an advantageous embodiment, each of the measuring sub-elements of the first measuring element is a first thermocouple half-cell. The second measuring element comprises, for each of said first thermocouple half-cells, a second thermocouple half-cell. The first thermocouple half-cell of each of the measuring sub-elements of the first measuring element is configured to be connected with the corresponding second thermocouple half-cell of the second measuring element to form respective thermocouples.

[0081] Furthermore, the probe also includes an emerging portion extending from the submersible portion of the probe along an elongated extension of the probe, the emerging portion of the probe being designed to extend at least beyond the medium. The probe advantageously has a tubular shape. by providing an internal channel housing said at least one heating element, said at least one first temperature measuring element and said at least one second temperature measuring element. The probe is further equipped with a wired connection for transmitting to said unit the value relating to a temperature difference between said first zone of the submersible part of the probe and said second zone of the submersible part of the probe, as well as a conductor for supplying power to the heating element.

[0082] In one embodiment, the probe is further equipped with a secondary temperature sensor capable of providing a temperature value for the medium. The unit is further configured to retrieve the temperature value of the medium provided by the secondary temperature sensor.

[0083] The invention also relates to a calorimeter comprising a reaction chamber for containing a medium, such as a reaction medium. This calorimeter further comprises at least one device for measuring the internal heat transfer coefficient of the medium as previously described.

[0084] The invention also relates to a method for determining the internal heat transfer coefficient of a medium, such as a reaction medium, using a measuring device as previously described. The method of the invention comprises the following operations: -) heating of said first zone of the submersible part of the probe, -) provision by said at least a first temperature measuring device and said at least a second temperature measuring device of a value relating to a temperature difference between said first zone of the submersible part of the probe and said second zone of the submersible part of the probe, -) retrieval by the unit of the value relating to a temperature difference between said first zone of the submersible part of the probe and said second zone of the submersible part of the probe, -) retrieval by unit of a temperature value of the medium, -) identification by said unit of the value of the internal heat transfer coefficient of said medium from the temperature value of the medium and of said value relating to a temperature difference between said first zone of the part submersible part of the probe and said second zone of the submersible part of the probe.

[0085] Advantageously, the said process comprises an operation in which the value of the internal heat transfer coefficient of the medium is identified by said unit by application of any one of the following mathematical models according to which: Psonde hmr = Asonde x Tsonde^ arïS where Psonde is the power dissipated by the heating element of the probe, Asonde is the effective surface area of ​​the heating zone in relation to the reaction medium, and ATsonde is the measure of the temperature difference between the two zones of the probe, or K hmr = — Jans where AT is the measure of the temperature difference between the two said zones of the probe, and K is a coefficient determined during a calibration. The coefficient K advantageously depends on the temperature of the reaction medium in which the measuring probe is immersed.

[0086] Such calibration is performed in the factory, generally using a solvent or a pure substance that allows for a wide temperature range. Over this temperature range, the parameter K is determined by injecting a high power, on the order of tens of watts, into the reaction medium. This establishes a temperature difference between the reaction medium and the double jacket. Using, for example, heat flux sensors, the overall heat transfer coefficient can be determined at specific points using the following equation: Ug = Heat flux / (Tm-Tde). In this equation, Ug is the overall heat transfer coefficient in Wm 2 k, Heat flux is the heat flux in W / m 2 through the double jacket, Tm is the temperature of the reaction medium and Tde is the temperature of the thermal fluid.

[0087] For each temperature of the reaction medium, the stirring speed of the reaction medium is varied so as to vary only the coefficient internal heat exchange. This yields differences in the internal heat exchange coefficient, which can then be correlated with the identified temperature variations of the probe. Thus, the desired coefficients are identified, allowing the internal heat exchange coefficient of the reaction medium to be determined from the information provided by the probe.

[0088] Preferably, the process also allows the determination of an overall heat transfer coefficient between a double jacket and the medium, the process being implemented by means of a reactor comprising a reaction chamber containing the medium and a double jacket delimiting said reaction chamber, in which double jacket being provided a thermal regulation chamber for the medium, said process for determining a heat transfer coefficient of a medium further comprising an additional operation of determining, from a double jacket temperature TDE and the internal heat transfer coefficient identified for the medium, a thermal power of the double jacket, and possibly a thermal power of a chemical reaction of the medium.

[0089] Preferably, the process further includes an additional operation of determining an internal heat transfer coefficient of a medium for an industrial reactor or an overall heat transfer coefficient for the same industrial reactor from the internal heat transfer coefficient determined by the unit. PRESENTATION OF THE FIGURES

[0090] The invention will be better understood upon reading the following detailed description of examples of embodiments of the invention, in relation to the following figures in the attached plates: Figure 1 (FIG.1) illustrates a double-jacketed reaction calorimeter used in the laboratory. It comprises a vessel with a reaction chamber, which is delimited by the inner jacket of the calorimeter and contains a reaction medium. The reaction calorimeter is equipped with a measuring device according to the present invention, enabling the determination of the value of the internal heat transfer coefficient of the reaction medium during its reaction inside the reaction chamber of the calorimeter. Figure 2 (FIG.2) is a schematic illustration of an example of an embodiment of said measuring device according to the present invention, which is structured and organized to identify a temperature difference of a probe comprising said measuring device represented in Figure 1. A lower part of the probe is immersible within the reaction medium comprising two temperature measuring elements separated from each other, one of said measuring elements being placed in a heated area of ​​the immersible part of the probe. Figure 3 (FIG.3) is a partial schematic illustration of a first specific example of the realization of said probe shown in Figures 1 and 2. In Figure 3, the probe is equipped at its lower part, which is immersed in the reaction medium, with a thermocouple comprising a pair of thermocouple half-cells, of which a first thermocouple half-cell is placed in said heated zone and a second thermocouple half-cell is placed at a distance from said heated zone. Figure 4 (FIG.4) is a partial schematic illustration of a second specific embodiment of the probe shown in Figures 1 and 2. In Figure 4, the probe is equipped with a plurality of thermocouples at its lower, immersible portion in the reaction medium, each comprising a set of thermocouple half-cells. The thermocouple half-cells in each set are arranged around the circumference of the probe's immersible portion. Figure 5 (FIG.5) is a partial schematic illustration of a third specific embodiment of the probe shown in Figures 1 and 2. In Figure 5, the probe is equipped at its lower part, which is immersed in the reaction medium, with a set of five thermocouples, each comprising a set of thermocouple half-cells distributed along the elongated extension of the probe in one set of thermocouple half-cells, and in another set of thermocouple half-cells distributed along a circumference of the probe's immerseable part. Figure 6 (FIG.6) is a schematic illustration of an example of the overall architecture of a probe according to the present invention. In Figure 6, the probe is a tubular probe with an overall elongated extension, which provides an internal channel extending along a submersible lower portion of the probe. This lower portion is extended by an upper portion of the probe following its overall elongated extension, the upper portion of the probe being designed to emerge from the reaction medium. Figure 7 (FIG.7) is a schematic illustration of the lower part of the probe shown in Figure 6, housing inside the internal channel of the probe a support equipped with a two-zone temperature measurement device - one of which is heated - of the submersible part of the probe, the temperature measurement device being part of said measuring apparatus according to the invention. DETAILED DESCRIPTION OF THE FIGURES

[0091] The figures and their detailed, non-limiting descriptions illustrate the invention in specific ways that do not restrict its scope. The figures and their detailed descriptions may serve to better understand and define the invention, if necessary in conjunction with the general description above. It should be noted in particular that the use of the measuring device of the invention within the reaction chamber of a reaction calorimeter does not limit the use of the measuring device in other applications for measuring the temperature of any reactive medium during its reaction.Furthermore, to avoid overloading the figures and thus facilitate their reading, the reference numbers assigned to the terms and / or concepts used to describe the invention and indicated on any of the figures are potentially repeated in the description of any other figure without implying their presence on all the figures.

[0092] In Figure 1, a calorimeter 1 has a double jacket 2, consisting of an inner jacket 2a and an outer jacket 2b. The inner jacket 2a defines a vessel containing a reaction chamber 3 with a reaction medium 4. composed, for example, of a reactant and a solvent. The reaction chamber 3 is equipped with a stirrer 5 immersed in the reaction medium 4 and driven in motion by a motor 6 to promote the homogeneity of the reaction medium 4.

[0093] Figure 1 illustrates a measuring device 10 according to the invention equipping the calorimeter 1. Said measuring device 10 synthetically comprises at least one probe 12 and a unit 13 for measuring a value of the internal heat transfer coefficient of the reaction medium 4, from data of a temperature difference of the probe 12 transmitted to said unit 13, as described later in relation to Figures 2 to 7.

[0094] Alternatively, the measuring device 10 may also include an auxiliary temperature sensor measuring the temperature 11c of the reaction medium 4 itself during its reaction, which can advantageously be transmitted to said unit 13 and thus potentially used to refine the value of the heat transfer coefficient of the reaction medium 4 identified by the measuring device 10 from said temperature difference data provided by the probe 12 to the unit 13. According to the example of an embodiment of such an auxiliary temperature sensor illustrated in Figure 1, this is an additional qualified temperature sensor 11b which is independently of the probe directly immersed in the reaction medium 4.

[0095] It should be noted from the outset that the said additional sensor 11 b, constituting said auxiliary temperature sensor of the reaction medium 4, can be advantageously replaced by a secondary sensor 11 a equipping the temperature probe 12 illustrated in Figure 2 and in Figures 5 and 6 as described later.

[0096] Still in Figure 1, the volume delimited between the inner face 2b1 of the outer shell 2b and the outer face 2a1 of the inner shell 2a of the double shell 2 of the calorimeter 1 provides a thermal regulation chamber 7 for the reaction medium 4, which is subjected to a temperature difference during its reaction. The thermal regulation chamber 7 maintains the reaction medium 4 at a set temperature to obtain the product resulting from the reaction of the reaction medium 4. For this purpose, the calorimeter 1 is conventionally equipped with a thermal system at least comprising a thermal group 8 for regulating the temperature of a thermal fluid 9 - such as an oil for example - which circulates inside the thermal regulation chamber 7.

[0097] As shown in Figure 1, the probe 12 is primarily elongated and has at its base an immersible portion 12a in the reaction medium 4, oriented vertically along the column 4a of the reaction medium 4 within the reaction chamber 3 under the influence of gravity. Following the elongated length of the probe 12, its immersible portion 12a extends into the surface, forming an emergent portion 12b which is designed to extend out of the reaction medium 4 until it emerges from the reaction chamber 3 and then from the calorimeter 1.

[0098] The submersible portion 12a of the probe 12 is designed to detect a temperature difference in the reaction medium 4 during its reaction, following the vertical extension of the elongated submersible portion 12a of the probe 12 within the reaction medium 4. The emergent portion 12b of the probe 12 is connected to the unit 13, in particular by a wired connection 13a as illustrated in the embodiments of the invention shown in Figures 1 to 6.

[0099] Unit 13 then identifies the value of a temperature difference of the submersible part 12a of the probe 12 and its continuous and real-time evolution during the reaction of the reaction medium 4, from temperature data which are measured by temperature measuring devices equipping the submersible part 12a of the probe 12, as described later in relation to Figures 2 to 7. Preferably, unit 13 also has said temperature data 11c provided by said auxiliary temperature sensor - secondary sensor 11a or additional sensor 11b - to refine the value of the internal heat transfer coefficient of the reaction medium 4 during its reaction which is essentially obtained from the temperature data provided by the probe 12 to unit 13.

[0100] Consequently, from the identification by unit 13 during the reaction of the reaction medium 4, on the one hand, of the temperature difference of the submersible part 12a of the probe 12 in two distinct zones of the probe 12 as described later in relation to figures 2 to 7, and on the other hand preferably also from the temperature of the reaction medium 4 measured by a said auxiliary temperature sensor - secondary sensor 11 a or additional sensor 11 b - unit 13 determines the value of the heat transfer coefficient specific to the reaction medium 4.

[0101] In Figure 2, probe 12 is schematically represented in a vertical position along its elongated extension. Probe 12 is equipped, at its submersible portion 12a, with a means for detecting a temperature difference in its submersible portion 12a during the reaction of the reaction medium 4. Note in Figure 2 the presence of said secondary sensor 11a with which it is equipped, replacing the additional sensor 11b previously mentioned in relation to Figure 1.

[0102] According to the embodiment illustrated in Figures 2, 6, and 7, the secondary sensor 11a is installed inside the submersible portion 12a of the probe 12 at its base, or in other words, inside the lower end 12e of the probe 12, which is blind as described hereafter. As shown in Figure 2, the submersible portion 12a of the probe 12 is equipped with a measuring device 14 for measuring the temperature difference to which the wall 12d of the probe 12 is subjected at its submersible portion 12a.

[0103] As illustrated in Figures 2 to 7, said measuring device 14 comprises at least: -) a low-power heating element 15, by way of non-restrictive indication, with a heating power of the order of between 0.001 W and 1 W (W: Watt). The heating element 15 generates heat in a first zone 15a of the submersible part 12a of the probe 12, which extends partially along the submersible part 12a of the probe 12 according to its elongated extension. -) a first temperature measuring element 16 equipping the submersible part 12a of the probe 12, which is in thermal contact with said first zone 15a which is heated by the heating element 15. -) a second temperature measuring element 17 equipping the submersible part 12a of the probe 12, which is in thermal contact with a second zone 15b of probe 12 being placed at a distance D1 from the first zone 15a which is referenced on figure 2 to 5 and 7.

[0104] As a non-restrictive guideline, the separation distance D1 between the first measuring element 16 and the second measuring element 17 is potentially between 5 mm and 3 cm, for example as an indication in the non-exclusive context of a reaction calorimeter 1 whose reaction chamber volume 3 is on the order of between 1 litre and 1.5 litre.

[0105] The first measuring element 16 identifies the temperature of the first heated zone 15a, and the second measuring element 17 identifies the temperature of the second zone 15b of the submersible portion 12a of the unheated probe 12. The first temperature measuring element 16 and the second temperature measuring element 17 enable the detection of a temperature difference between the first zone 15a and the second zone 15b of the lower portion 12a of the probe 12, and provide the measuring unit 13, notably via an electrically conductive wire 21, with the data relating to such a temperature difference.

[0106] The measuring unit 13 then identifies the value of the temperature difference of the submersible part 12a of the probe 12 located between the first temperature measuring element 16 and the second temperature measuring element 17, at least from said value of the temperature difference of the submersible part 12a of the probe 12, preferably subsidiarily correlated with the temperature measurement of the reaction medium by an auxiliary temperature sensor, such as the secondary temperature sensor 11a illustrated.

[0107] It should be noted that the first temperature measuring element 16 and the second temperature measuring element 17 – or, as referred to later, their potential components 18 and 19 – as well as the heating element 15, are fixed to the inner face of the wall of the submersible part 12a of the probe 12 by means of a thermal paste with a high coefficient of thermal conductivity. Since the wall of the probe 12 is preferably tubular and of thin thickness – as illustrated in Figures 3 to 7 – the thermal conductivity of the wall of the probe 12 is optimized.

[0108] According to the various advantageous embodiments respectively illustrated in Figures 2 to 5 and 7, the first temperature measuring element 16 is formed of at least one first thermocouple half-stack 18 and the second temperature measuring element 17 is formed of at least one second thermocouple half-stack 19. Said at least one first thermocouple half-stack 18 and said at least one second thermocouple half-stack 19 jointly constitute at least one thermocouple 18-19-20 forming a temperature sensor, such a thermocouple 18-19-20 being typically arranged as a pair of electrically conductive wires.

[0109] According to the various embodiment examples illustrated in Figures 2 to 5, the hot junction area of ​​said at least one thermocouple 18-19-20 is provided by said at least one second thermocouple half-cell 19 and the cold junction area of ​​thermocouple 18-19-20 is provided by said at least one first thermocouple half-cell 18. This simplifies the transmission via said electrically conductive wire 21 of the data provided by said at least one thermocouple 18-19-20 to the measuring unit 13, which in this case at least includes a voltmeter which is connected via the wire link 13a to said electrically conductive wire 21.

[0110] Figures 3 to 5 illustrate different respective embodiments of the arrangement of the submersible part 12a of the probe 12 having at least one said first thermocouple half-cell 18 and at least one said second thermocouple half-cell 19, which according to the embodiment examples illustrated in these figures 3 to 5 respectively constitute the first temperature measuring element 16 and the second temperature measuring element 17 connected to each other by at least one electrical wire link 20 formed by the pair of electrically conductive wires constituting the thermocouple half-cells.

[0111] According to the embodiment illustrated in Figure 3, the submersible part 12a of the probe 12 comprises a single thermocouple 18-19-20 including a single first thermocouple half-stack 18 and a single second thermocouple half-stack 19 located at a distance D1 from the first heated zone 15a. The first thermocouple half-stack 18 and the second thermocouple half-stack 19 are connected together via a said electrical wire link 20 formed by the said pair of electrically conductive wires constituting at their ends the thermocouple half-cells 18 and 19.

[0112] The first thermocouple half-pile 18 is electrically connected via the electrically conductive wire 21 equipping the submersible part 12a of the probe 12, the electrically conductive wire 21 being itself electrically connected to said unit 13 via said wire link 13a.

[0113] According to the embodiment illustrated in Figure 4, the probe comprises several thermocouples 18-19-20 including: -) a plurality of first thermocouple half-stacks 18 which are constitutive of temperature-measuring sub-elements comprising the first temperature-measuring element 16. The first thermocouple half-stacks 18 are placed in the first zone 15a of the submersible part 12a of the probe 12, which is heated by the heating element 15, and -) a plurality of second thermocouple half-stacks 19 which are constitutive of temperature measuring sub-organs composing the second temperature measuring organ 17. The second thermocouple half-stacks 19 are placed in the second unheated zone 15b of the submersible part 12a of the probe 12 which is at a distance D1 from said first heated zone 15a.

[0114] Each of the plurality of first thermocouple half-stacks 18 and second thermocouple half-stacks 19 is distributed along the circumference of the inner face of the tubular wall of the probe 12 at its lower submersible portion 12a. Each thermocouple half-stack 18 is connected to a second thermocouple half-stack 19 by an electrical wire 20, thus collectively forming several thermocouples 18-19-20 connected in series. The first thermocouple half-stacks 18 are electrically connected to the electrically conductive wire 21 equipping the submersible portion 12a of the probe 12, which is itself electrically connected to the unit 13 via the wire 13a.

[0115] According to the embodiment illustrated in Figure 5, probe 12 comprises ) a plurality of first thermocouple half-stacks 18 which are constitutive of temperature measuring sub-organs composing the first temperature measuring organ 16 which is placed in the first heated zone 15a of the submersible part 12a of the probe 12. The first thermocouple half-stacks 18 are successively distributed along the elongated extension of the submersible part 12a of the probe 12. -) a plurality of second thermocouple half-cells 19 constituting sub-temperature measuring elements comprising the second temperature measuring element 17 located in the second zone 15b of the submersible portion 12a of the probe 12, at a distance D1 from the first heated zone 15a. The thermocouple half-cells 19 are arranged in the second zone 15b of the submersible portion 12a of the probe 12, distributed along the circumference of the inner face of the tubular wall of the probe 12.

[0116] The thermocouple half-stacks 19 are respectively connected to the first thermocouple half-stacks assigned to them, via said electrical wire link 20, forming a plurality of thermocouples which are electrically connected via the electrically conductive wire 21 which is itself electrically connected to said unit 13 via said wire link 13a.

[0117] Such an assembly on the submersible part 12a of the probe 12 of the first thermocouple half-piles 18 and the second thermocouple half-piles 19 makes it possible to detect the level of the reaction medium 4 contained in the reaction chamber 3, and consequently to identify the heat exchange surface between the reaction medium 4 and the inner face 2a2 of the inner envelope 2a of the calorimeter 1 delimiting the reactor - or in other words the reaction chamber 3 - which is oriented towards the reaction medium 4.

[0118] Access to the heat exchange surface between the reaction medium 4 and the inner face 2a of the inner envelope allows the thermal power through the double envelope 2 of the calorimeter 1 to be measured, exclusively or in other words only via the probe 12 partially immersed inside the reaction medium 4, in real time and continuously during the reaction of the reaction medium 4 inside the reaction chamber 3.

[0119] Figures 6 and 7 illustrate the overall architecture and organization of a probe 12 representing an advantageous embodiment of the invention. The wall 12d of the probe is tubular, providing an internal channel 12c within the probe 12. The lower end 12e of the probe 12 is closed, making the internal channel 12c of the probe 12 blind, thus preventing any infiltration of the reaction medium 4 into the probe 12.

[0120] In Figure 6, the probe 12 is shown in its entirety, without a detailed illustration of its entire internal arrangement, particularly with regard to its lower submersible part 12a. Figure 7 illustrates a detail of the probe 12 shown in Figure 6, and more specifically its submersible part 12a and the components of the temperature measurement device 14 with which it is equipped - such as, for example, those illustrated in Figure 3 - which are housed inside the internal channel 12c of the probe 12 at its lower submersible part 12a.

[0121] In Figure 6, the internal channel 12c of the probe 12 extends from the lower blind end 12e of the probe 12 to the upper end 12f of the probe 12. The internal channel 12c of the probe 12 houses a support 22 on which the components of the measuring device 14 are installed inside the internal channel in its extension part of the submersible part 12a of the probe 12, as illustrated in Figure 7.

[0122] The upper end 12f of the probe 12 has an opening 12g intended to be oriented towards the outside of the reaction medium 4 - and more specifically preferably out of the calorimeter 1 - to allow the passage of the wire link 13a connecting to said unit 13 the measuring device 14 equipping the submersible part 12a of the probe 12.

[0123] In Figure 7, the support 22 is advantageously formed of a printed circuit board having electroconductive tracks and on which are etched or fixed – via thermal paste – a first thermocouple half-cell 18 and a second thermocouple half-cell 19 constituting a thermocouple 18-19-20. The heating element 15 – advantageously formed of a heating film – is fixed to the inner face of the wall 12d of the probe 12 via a thermal paste surrounding the first half-stack thermocouples 18.

[0124] The first thermocouple half-pile 18 is connected to a trace on the printed circuit board forming the electrically conductive wire path 21 for its connection to said unit 13 via said wire link 13a fixed at one of its ends to the support 22 and connected to the unit 13. A power conductor 23 – in particular electrical power and potentially preferably formed from a trace on the printed circuit board – extends from the heating element 15 to the outside of the probe 12, being connected to said wire link 13a jointly with said electrically conductive wire path 21 connecting the measuring device 14 to said unit 13. It should be noted that said electrical power conductor 23 can be used to regulate the temperature of the heating element 15 under the control of said unit 13.

[0125] It should be noted that the measuring device 10 identifies the value of the internal heat transfer coefficient of the medium 4, and that the parameters relating to the thickness and thermal conductivity of the inner wall 2a2 of the double jacket 2 of the calorimeter 1, as well as the heat transfer coefficient between the heat transfer fluid 9 and the outer face 2a1 of the inner jacket 2a, are readily accessible. Consequently, the measuring device 10 is not only capable of identifying the internal heat transfer coefficient of the reaction medium 4, but also of calculating in real time and continuously during the reaction of the reaction medium 4 the overall heat transfer coefficient between the reaction medium 4 and the heat transfer fluid 9.This allows the heat exchange power to be calculated through the double jacket 2, without using any equipment other than the measuring device 10 such as, for example, heat flow sensors and / or a calibration probe for said overall heat exchange coefficient.

[0126] This is achieved in particular by the direct and continuous measurement, advantageously by at least one thermocouple, of the temperature difference between the first zone 15a of the probe 12 heated by the heating element 15 and the second zone 15b of the probe 12 not heated by the heating element 15, without determining the absolute temperature value in each of the first zone 15a and the second zone 15b. This direct measurement at Using at least one thermocouple ensures increased accuracy compared to two independent temperature measurements that would be subtracted electronically to obtain a temperature difference value. The determination of the internal heat transfer coefficient (hmr) is therefore made more precise.

[0127] An example of an additional operation to determine an internal heat transfer coefficient (hmr') of a medium for an industrial reactor or an overall heat transfer coefficient (UG') for the same industrial reactor from the internal heat transfer coefficient (hmr) determined by unit 13 using a calculation system will now be described.

[0128] In calorimeter 1, the internal heat transfer coefficient hmr determined by unit 13 can, for example, be expressed by the following equation [EQC]:

[0129] hmr = N 2 ^ 3 x in which N is a coefficient dependent on the stirring speed in revolutions per minute in the calorimeter, "calorimeter" is a coefficient dependent on the shape of the stirring wheel used in the calorimeter, zcalorimeter is a geometric coefficient corresponding to the ratio of the transverse extent of the stirring wheel in calorimeter 1 to the internal transverse extent of the calorimeter 1 vessel and v(t) is a coefficient which depends on the evolution of the reaction medium during the reaction, in particular its viscosity, specific heat capacity, thermal conductivity and density.

[0130] For the same reaction medium, the internal heat transfer coefficient (hmr') of the medium in the industrial reactor can be expressed by the following equation [EQR]: In which N CSt is a coefficient dependent on the stirring speed in revolutions per minute in the industrial reactor, oc 'industrial reactori' is a coefficient dependent on the shape of the stirring impeller used in the industrial reactor, z'industrial reactori' is a geometric coefficient corresponding to the ratio of the transverse extent of the stirring impeller in the industrial reactor to the internal transverse extent of the reactor vessel. industrial reactor and v(t) is the same coefficient of evolution of the reaction medium during the reaction as that of equation [EQC].

[0132] Knowing the value of hmr determined by unit 13 in calorimeter 1, and the coefficients N,catorimeter, and zcatorimeter !which depend only on the characteristics of calorimeter 1, the calculation system determines v(t) from the equation [EQC] above.

[0133] Then, the value of v(t) and the values ​​of the coefficients N', oc 'industrial reactorei and z' industrial reactor which depend solely on the characteristics of the industrial reactor are then used by the calculation system to calculate the internal heat transfer coefficient hmr' of the medium in the industrial reactor via equation [EQR],

[0134] Knowing the value of hmr', and the characteristics of the industrial reactor, including its cooling system, the calculation system can then conventionally calculate the overall heat transfer coefficient UG' using the following equation: in which UG' is the overall heat transfer coefficient between the reaction medium and the industrial reactor thermal fluid, hmr' is the internal heat transfer coefficient of the reaction medium determined by equation [EQR] from measurements made in calorimeter 1, ep' is the thickness of the internal wall of the industrial reactor enclosure interfaced between the thermal fluid and the reaction medium, Àp' is the thermal conductivity coefficient of the material constituting the walls of the enclosure - in particular the internal wall - of the industrial reactor, and HDE is the heat transfer coefficient of the thermal fluid circulating inside the thermal system for heating or cooling the industrial reactor enclosure via the thermal fluid.

[0135] It is then possible to determine the evolution of the temperature of the cooling fluid during the reaction in the industrial reactor and to adjust, for example, the flow rate in the industrial reactor according to the thermal power that can be evacuated.

Claims

DEMANDS 1) A measuring apparatus (10) for the value of the internal heat transfer coefficient of a medium (4), such as a reaction medium, said measuring apparatus (10) comprising at least: a probe (12), said probe (12) being at least equipped with: *) of at least one heating element (15) of a first zone (15a) of a submersible part (12a) of the probe (12) which is intended to be immersed within said medium (4), and *) of at least one first temperature measuring element (16) and at least one second temperature measuring element (17), the first temperature measuring element (16) being placed in thermal contact with the first zone (15a) of the probe (12) and the second temperature measuring element (17) being placed in thermal contact with a second zone (15b) of the submersible part (12a) of the probe (12) which is at a distance (D1) from said first zone (15a), said at least one first temperature measuring element (16) and said at least one second temperature measuring element (17) being configured to provide a value relative to a temperature difference between said first zone (15a) of the submersible part (12a) of the probe (12) and said second zone (15b) of the submersible part (12a) of the probe (12), - a unit (13) for identifying a temperature difference in the submersible portion (12a) of the probe (12) from the data provided to said unit (13) by said probe (12), said unit (13) being configured to retrieve the value relating to a temperature difference between said first zone (15a) of the submersible portion (12a) of the probe (12) and said second zone (15b) of the submersible portion (12a) of the probe (12), and to identify the value of the internal heat transfer coefficient of said medium (4) from a temperature value of the medium (4) and said value relating to a temperature difference between said first zone (15a) of the submersible portion (12a) of the probe (12) and said second zone (15b) of the submersible part (12a) of the probe (12). 2) Measuring apparatus (10) of claim 1, wherein said at least a first temperature measuring element (16) and said at least a second temperature measuring element (17) are spaced apart from each other on the submersible part (12a) of the probe (12) by a distance (D1) greater than or equal to 5 mm, such advantageously greater than or equal to 1 cm. 3) Measuring apparatus (10) according to any one of claims 1 to 2, wherein said at least a first temperature measuring element (16) comprises at least a first thermocouple half-cell (18) and the second temperature measuring element (17) comprises at least a second thermocouple half-cell (19), said at least a first thermocouple half-cell (18) and said at least a second thermocouple half-cell (19) being constitutive of a thermocouple (18,19,20) for measuring said value relating to a temperature difference between said first zone (15a) of the submersible part (12a) of the probe (12) and said second zone (15b) of the submersible part (12a) of the probe (12). 4) Measuring apparatus (10) according to claim 3, wherein the first temperature measuring element (16) comprises at least two first thermocouple half-stacks (18) and the second temperature measuring element (17) comprises at least two second thermocouple half-stacks (18), each first thermocouple half-stack (18) forming with a second thermocouple half-stack (19) assigned to it a thermocouple (18,19,20), the thermocouples (18,19,20) respectively formed by said at least two first thermocouple half-stacks (18) and said at least two second thermocouple half-stacks (19) being connected in series. 5) Measuring apparatus (10) according to any one of claims 1 to 3, wherein the first temperature measuring element (16) and the second temperature measuring element (17) are respectively a first temperature sensor and a second temperature sensor arranged to provide a temperature respectively of the first zone (15a) and of the second zone (15b) of the submersible part (12a) of the probe (12). 6) Measuring apparatus (10) according to any one of claims 1 to 5, wherein: -) said heating element (15) is configured to transfer heat into said first zone (15a) of the submersible part (12a) of the probe (12), said first zone (15a) being substantially elongated and intended to have a vertical orientation within the medium (4), and -) the first temperature measuring element (16) comprises a plurality of sub-measuring elements (18) arranged to extend along said first zone (15a) of the submersible part (12a) of the probe (12). 7) Measuring apparatus (10) according to claims 3 and 6, wherein each of the measuring sub-elements of the first measuring element (16) is a first thermocouple half-cell (18), the second measuring element (17) comprising, for each of said first thermocouple half-cells (18), a second thermocouple half-cell (19), the first thermocouple half-cell (18) of each of the measuring sub-elements of the first measuring element (16) being shaped to be connected (20) with the corresponding second thermocouple half-cell (19) of the second measuring element (17) in order to form respective thermocouples. 8) A measuring apparatus according to any one of claims 1 to 7, wherein: -) said probe (12) further comprises an emerging portion (12b) extending as a continuation of said submersible portion (12a) of the probe (12) along an elongated extension of the probe (12), the emerging portion (12b) of the probe (12) being intended to extend at least outside the medium (4), and -) said probe (12) is tubular in shape, providing an internal channel (12c) housing said at least one heating element (15), said at least one first temperature measuring element (16) and said at least one second temperature measuring element (17), and is further equipped with a wired connection (13a) for transmitting the value to said unit (13) relating to a temperature difference between said first zone (15a) of the submersible part (12a) of the probe (12) and said second zone (15b) of the submersible part (12a) of the probe (12), as well as a conductor (23) for supplying power to the heating element (15). 9) Measuring apparatus (10) according to any one of claims 1 to 8, wherein the probe (12) is further equipped with a secondary temperature sensor (11 a) capable of providing a temperature value of the medium (4), the unit (13) being further configured to retrieve the temperature value of the medium (4) provided by the secondary temperature sensor (11 a). 10) Measuring apparatus (10) according to any one of claims 1 to 9 wherein the second zone (15b) of the submersible part (12a) of the probe (12) is an unheated zone of the probe (12). 11) Measuring apparatus (10) according to any one of claims 1 to 10 in which the unit (13) is configured to identify the value of a temperature difference of the submersible part (12a) of the probe (12) and its evolution continuously and in real time, during a reaction of the reaction medium (4) from temperature data which are measured by at least one first temperature measuring element (16) and at least one second temperature measuring element (17) equipping the submersible part (12a) of the probe (12). 12) Calorimeter (1) comprising a reaction chamber (3) intended to contain a medium (4), such as a reaction medium, said calorimeter (1) further comprising at least one measuring device (10) for an internal heat transfer coefficient of the medium (4) according to any one of claims 1 to 11. 13) Calorimeter (1) according to claim 12, wherein said temperature difference between said first zone (15a) of the submersible part (12a) of the probe (12) and said second zone (15b) of the submersible part (12a) of the probe (12), and the temperature of the reaction medium via an auxiliary temperature sensor are configured to be measured simultaneously in real time and continuously during the reaction of the reaction medium (4) inside the reaction calorimeter (1). 14) A method for determining an internal heat transfer coefficient of a medium (4), such as a reaction medium, employing a measuring apparatus according to any one of claims 1 to 12, comprising the following operations: -) heating of said first zone (15a) of the submersible part (12a) of the probe (12), -) supply by said at least a first temperature measuring device (16) and said at least a second temperature measuring device (17) of a value relating to a temperature difference between said first zone (15a) of the submersible part (12a) of the probe (12) and said second zone (15b) of the submersible part (12a) of the probe (12), the second zone (15b) of the submersible part (12a) of the probe (12) preferably being an unheated zone of the probe (12), -) retrieval by unit (13) of the value relating to a temperature difference between said first zone (15a) of the submersible part (12a) of the probe (12) and said second zone (15b) of the submersible part (12a) of the probe (12), -) retrieval by unit (13) of a temperature value of the medium (4), - the method advantageously comprising the identification of the value of a temperature difference of the submersible part (12a) of the probe (12) and its continuous and real-time evolution, during a reaction of the reaction medium (4) from the temperature data which are measured by at least one first temperature measuring element (16) and at least one second temperature measuring element (17) equipping the submersible part (12a) of the probe (12) -) identification by said unit (13) of the value of the internal heat transfer coefficient (hmr) of said medium (4) from the temperature value of the medium (4) and of said value relating to a temperature difference between said first zone (15a) of the submersible part (12a) of the probe (12) and said second zone (15b) of the submersible part (12a) of the probe (12). 15) A method for determining an internal heat transfer coefficient (hmr) of a medium (4) according to claim 14, wherein the value of the internal heat transfer coefficient (hmr) of the medium (4) is identified by said unit (13) by applying any one of the following mathematical models according to which: HMR probe = - - : - — - — Asonde x T probe -) where Psonde is the power dissipated by the probe's heating element, Asonde is the effective surface area of ​​the heating zone facing the reaction medium, and ATsonde is the temperature difference between the two probe zones, or K hmr = — -) in which AT is the measure of the temperature difference between the two said probe zones, and K is a coefficient determined during calibration. 16) A method for determining an internal heat transfer coefficient (hmr) of a medium (4) according to claim 14 or 15 further enabling the determination of an overall heat transfer coefficient between a double jacket and the medium (4), wherein the method is carried out by means of a reactor (1) comprising a reaction chamber (3) containing the medium (4) and a double jacket (2) delimiting said reaction chamber, in which double jacket (2) is provided a thermal regulation chamber for the medium (4), said method for determining an internal heat transfer coefficient (hmr) of a medium (4) further comprising an additional operation of determining, from a double jacket temperature TDE and the internal heat transfer coefficient identified for the medium (4), a thermal power of the double jacket (2), and optionally a thermal power of a chemical reaction of the medium (4). 17) Method for determining an internal heat transfer coefficient (hmr) of a medium (4) according to any one of claims 14 to 16, wherein it further includes an additional operation of determining an internal heat transfer coefficient of a medium for an industrial reactor or an overall heat transfer coefficient for the same industrial reactor from the internal heat transfer coefficient (hmr) determined by the unit (13).

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