DEVICE AND METHOD FOR CALIBRATION OF DOSING DEVICES INTENDED FOR USE WITH FLOWING MIXTURES UNDER EXTREME THERMODYNAMIC CONDITIONS

Abstract

The for calibrating a metering device comprises a closed calibration loop adapted to circulate a primary fluid therein. The closed calibration loop comprises an inlet connection and an outlet connection, adapted to fluidly couple a metering device to be calibrated to the closed calibration loop. The calibration loop further includes a reference metering unit comprising an inlet and an outlet. A flow circulation device circulates a fluid in the closed calibration loop. A heater between the outlet of the reference metering unit and the inlet connection for the metering device to be calibrated; and a cooler between the outlet connection for the metering device to be calibrated and the inlet of the reference metering unit provide heat transfer in the facility.

Description

CALIBRATION FACILITY AND METHOD FOR METERING DEVICES TO BE USED WITH FLUID MIXTURES IN EXTREME THERMODYNAMIC CONDITIONSDESCRIPTIONTECHNICAL FIELD

[0001] The present disclosure relates to devices and methods for calibrating a metering device to be used under extreme thermodynamic conditions, for instance in a thermodynamic cycle using a CO2-based fluid in supercritical conditions, without knowing the equation of state of the fluid.BACKGROUND ART

[0002] The need to reduce carbon dioxide (CO2) emissions generated by mechanical and electrical power generation plants has fostered the research for innovative thermodynamic cycles. Among these, closed or semi-closed thermodynamic cycles which use CO2-based fluid blends in supercritical conditions are particularly promising. So- called oxy -fuel thermodynamic cycles, such as Allam cycles, for instance, use 002- based mixtures, in which the process fluid reaches supercritical conditions with temperatures around 500-600 °C and pressures around 300-350 barA.

[0003] These operating conditions are far beyond common conventional ranges of thermodynamic parameters, where the equation of state of the process fluid is known and metering devices, e.g., flowmeters, can be easily calibrated and tested. There is, in fact, a lack of knowledge of the properties of supercritical CO2 or CCL-based blends of fluids.

[0004] Even if some available flow measurement technologies, such as ultrasonic or vortex flowmeters, could work at supercritical conditions in terms of temperature and pressure, they cannot be tested and calibrated with supercritical carbon dioxide or supercritical CCL-based mixtures due to lack of such flow calibration facilities.

[0005] Several applications involving supercritical CO2 or supercritical CCL-based fluid blends currently under investigation, for instance in the field of power generation, would require accurate flow measurements. There is therefore a need for a facilitywhich allows calibration of metering devices under such extreme thermodynamic conditions, without a knowledge of the equation of state of the mixture used as a working fluid under the thermodynamic conditions at which the metering devices are required to operate.

[0006] As used herein “extreme thermodynamic conditions” can be conditions at which the equation of state of the process fluid flowing through the device under test are unknown or not sufficiently known. For instance, extreme thermodynamic conditions can be conditions present in a supercritical carbon dioxide thermodynamic cycle, wherein the process or working fluid is carbon dioxide with or without dopants, or a blend of carbon dioxide and one or more secondary fluid components. Blends of carbon dioxide and dopants or secondary components as working fluids in thermodynamic cycles are described for instance in E: Morosini et al. “ Adoption of the CO2+SO2 mixture as working fluid for transcritical cycles: A thermodynamic assessment with optimized equation of stale", in Energy Conversion and Management 255 (2022) 115263 available at https: / / doi.Org / 10.1016 / j.enconman.2022.115263.SUMMARY

[0007] According one aspect, disclosed herein is a facility for calibrating a metering device which comprises a closed calibration loop adapted to circulate a primary fluid therein.

[0008] In embodiments disclosed herein, the facility further comprises at least a first vessel adapted to contain at least a first one of a dopant and a secondary fluid component, to be added to a primary fluid circulating in the closed calibration loop.

[0009] The closed calibration loop in turn comprises an inlet connection and an outlet connection, adapted to fluidly couple a device to be calibrated to the closed calibration loop. The device will be referred to herein also as device under test. Moreover, the closed calibration loop includes a reference metering unit comprising an inlet and an outlet. A flow circulation device is adapted to circulate a fluid in the closed calibration loop. A heater is provided between the outlet of the reference metering unit and the inlet connection for the metering device to be calibrated. A cooler is provided between the outlet connection for the metering device to be calibrated and the inlet of thereference metering unit.

[0010] A device under test can be fluidly coupled to the closed calibration loop, between the inlet connection and the outlet connection. A process fluid can circulate in the closed calibration loop, which is divided into: a hot section extending between the heater and the cooler and including the device under test; and a cold section extending between the cooler and the heater and including the reference metering unit. The composition of the process fluid can be modulated by adding variable amounts of one or more dopants and / or one or more secondary fluid component to a primary fluid component, for instance carbon dioxide. This allows the device under test to be tested for process fluids having variable compositions.

[0011] The facility allows testing the metering device in such conditions which are as similar as possible to actual operating conditions in a thermodynamic cycle. The process fluid in the real thermodynamic cycle can in fact contain a main fluid, such as carbon dioxide and a secondary fluid, such as water steam. In some cases, the process fluid may contain one or more dopants, adapted modify the phase diagram of the process fluid, such as the critical point and / or the transition lines. The facility allows testing or calibrating the metering device under variable molar compositions of the process fluid.

[0012] According to further embodiments, the facility for calibrating a metering device can comprise a closed calibration loop adapted to circulate a primary fluid therein, and a heat recovery arrangement adapted to transfer heat from a cooler to a heater in the closed calibration loop, and release heat in the closed calibration loop.

[0013] The closed calibration loop comprises an inlet connection and an outlet connection, adapted to fluidly couple a metering device to be calibrated to the closed calibration loop. Moreover, the closed calibration loop includes a reference metering unit comprising an inlet and an outlet. A flow circulation device is adapted to circulate a fluid in the closed calibration loop. A heater is provided between the outlet of the reference metering unit and the inlet connection for the metering device to be calibrated. A cooler is provided between the outlet connection for the metering device to be calibrated and the inlet of the reference metering unit. Heat is removed from the process fluid circulating in the closed calibration loop through the cooler and re-introduced inthe closed calibration loop through the heater. Heat is transferred from the cooler to the heater by a heat transfer fluid circulating in the heat recovery loop.

[0014] The temperature of the process fluid flowing through the device under test can thus be increased and possibly modulated at will, to test the device under variable thermodynamic conditions, while heat removed from the process fluid upstream of the reference metering unit is recovered and used to heat the process fluid downstream of the reference metering unit and upstream of the device under test.

[0015] According to further embodiments disclosed the facility comprises a closed calibration loop adapted to circulate a primary fluid therein, and a pressure and temperature adjusting arrangement, adapted to adjust a temperature and a pressure of a fluid circulating in the closed calibration loop, such that a device under test fluidly coupled to the closed calibration loop can be tested under variable thermodynamic conditions, i.e., at different pressure and temperature values. Also in this embodiment, the closed calibration loop comprises an inlet connection and an outlet connection, adapted to fluidly couple a metering device to be calibrated to the closed calibration loop. Moreover, the closed calibration loop includes a reference metering unit comprising an inlet and an outlet. A flow circulation device is adapted to circulate a fluid in the closed calibration loop. A heater is provided between the outlet of the reference metering unit and the inlet connection for the metering device to be calibrated. A cooler is provided between the outlet connection for the metering device to be calibrated and the inlet of the reference metering unit. A heat recovery arrangement can be provided to transfer heat from the cooler to the heater.

[0016] Disclosed herein are also methods for calibrating a device under test under extreme thermodynamic conditions.

[0017] According to some embodiments, the method comprises the following steps: circulating a fluid mixture in a closed calibration loop through a metering device to be calibrated and through a reference metering unit, the fluid mixture comprising a primary fluid and at least one of a dopant and a secondary fluid; heating the fluid mixture circulating in the closed calibration loop in a heater arranged between an outlet of the reference metering unit and an inlet of the metering device to be calibrated; cooling the fluid mixture in a cooler arranged between an outlet of the metering device to becalibrated and an inlet of the reference metering unit; detecting a composition of the fluid mixture circulating in the closed calibration loop; calibrating the metering device to be calibrated based on the measuring data of the reference metering unit.

[0018] According to further embodiments, the method comprises the following steps: circulating a fluid in a closed calibration loop through a metering device to be calibrated and through a reference metering unit; heating the fluid circulating in the closed calibration loop in a heater arranged between an outlet of the reference metering unit and an inlet of the metering device to be calibrated; cooling the fluid in a cooler arranged between an outlet of the metering device to be calibrated and an inlet of the reference metering unit; and recovering heat from the closed calibration loop through a heat recovery fluid circulating in a heat recovery loop.

[0019] According to yet further embodiments, the method comprises the following steps: circulating a fluid in a closed calibration loop through a metering device to be calibrated and through a reference metering unit; heating the fluid circulating in the closed calibration loop in a heater arranged between an outlet of the reference metering unit and an inlet of the metering device to be calibrated; cooling the fluid in a cooler arranged between an outlet of the metering device to be calibrated and an inlet of the reference metering unit; and adjusting a pressure and a temperature of the fluid flowing through the metering device to be calibrated.

[0020] Further features and embodiments of the calibration facilities and of the calibration methods according to the present disclosure are outlined in the following detailed description and set forth in the attached claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Reference is now made briefly to the accompanying drawings, in which:Fig.1 illustrates a schematic of a calibration facility according to the present disclosure in one embodiment;Fig.2 illustrates a temperature diagram showing the fluid temperatures in various sections of the two loops of the calibration facility;Fig.3 illustrates a schematic of a calibration facility according to the present disclosure in a further embodiment; andFigs.4 and 5 illustrate temperature diagrams showing the fluid temperatures along the path of the fluid in the closed calibration loop of Fig.3.DETAILED DESCRIPTION

[0022] Fig.1 illustrates a schematic of a calibration facility 1 according to the present disclosure in a first embodiment. The calibration facility 1 has the function of calibrating a generic device, e.g., a metering device, adapted to operate under extreme thermodynamic conditions, e.g., under supercritical CO2 conditions. The device to be calibrated (here below referred to also as DUT: Device Under Test) is shown at 3. The device under test (DUT) 3 does not per se form part of the facility 1 but becomes part of a calibration loop of the calibration facility 1, once it is fluidly coupled to the calibration facility 1 as described below.

[0023] Several different DUTs can be connected to the calibration loop (to be described) which forms part of the facility 1, for calibration purposes. The DUT 3 can be an ultrasonic flow meter, a differential pressure flow meter, a Venturi tube, or a Vortex flow meter, for instance.

[0024] The facility 1 comprises a closed calibration loop 5, which includes an inlet connection 5A and an outlet connection 5B, between which a device to be tested 3 can be connected to become temporarily part of the closed calibration loop 5.

[0025] The closed calibration loop 5 further comprises a reference metering unit 7, which in turn comprises an inlet 7A and an outlet 7B. In the embodiment of Fig.1 the reference metering unit 7 comprises a plurality of reference metering devices which are connected in parallel to one another and are all fluidly coupled to the inlet 7A and the outlet 7B. By way of non-limiting example, in Fig.l the reference metering unit 7 includes a first reference metering device 9 and a second reference metering device 11. A valve arrangement 13 is further provided between the set of reference metering devices 9, 11 and the inlet 7A and / or the outlet 7B.

[0026] In the exemplary embodiment of Fig. l the valve arrangement 13 comprises a first valve 15 in series with the first metering device 9, between the inlet 7A and the first metering device 9. The valve arrangement 13 further comprises a second valve 15 in series with the second metering device 11, between the inlet 7 A and the secondmetering device 11. The valve arrangement 13 allows to selectively isolate one or the other metering device 9, 11 from the closed calibration loop 5, such that a variable number of reference metering devices can be used during a calibration procedure, according to needs.

[0027] The closed calibration loop 5 further includes a flow circulation device 19, adapted to circulate a fluid in the closed calibration loop 5. The flow circulation device 19 can include a pump adapted to overcome the head losses along the closed calibration loop 5. The flow circulation device 19 can be arranged in any suitable position along the closed calibration loop 5. As will be described in detail below, the closed calibration loop 5 includes a hot section and a cold section. In preferred embodiments, the flow circulation device 19 is positioned along the cold section of the closed calibration loop 5, such that process fluid contacting the mechanical components of the flow circulation device 19 is at a lower temperature, such that damages or wear of the flow circulation device 19 are reduced.

[0028] In the embodiment of Fig. 1 the flow circulation device 19 is arranged between the outlet 7B of the reference metering unit 7 and the inlet connection 5A, and more specifically upstream a heater, to be described below, which heats the working fluid before entering the device under test 3.

[0029] The closed calibration loop 5 further includes a flow controller 21. In the embodiment of Fig.1 the flow controller 21 is arranged along the cold section of the closed calibration loop, upstream of the reference metering unit 7. In other embodiments the flow controller 21 can be positioned in a different location along the cold section of the closed calibration loop 5. For instance, the flow controller 21 can be arranged upstream or downstream of the flow circulation device 19, or can be integrated therein. Arranging the flow controller in the cold section of the closed calibration loop 5 reduces wear and damages to the flow controller 21.

[0030] The calibration facility 1 further comprises a heater and a cooler. The heater is positioned along the closed calibration loop 5, between the outlet 7B of the reference metering unit 7 and the inlet connection 5A for the metering device to be calibrated, i.e the DUT 3. The cooler is positioned between the outlet connection 5B for the DUT 3 and the inlet 7A of the reference metering unit 7.

[0031] More specifically, the embodiment of Fig.1 the heater is arranged between the circulation device 19 and the inlet connection 5 A. The cooler is arranged between the outlet connection 5B and the flow controller 21.

[0032] In some embodiments, the heater is formed by a cold side 23C of a first heat exchanger 23 comprising said cold side 23C and a hot side 23H. The cold side 23C of the first heat exchanger 23, i.e., the domain of the first heat exchanger 23 which receives heat from a hot side of the heat exchanger 23, forms part of the closed calibration loop 5. The hot side 23H, i.e., the domain of the first heat exchanger 23 which transfers heat to the cold side 23 C of the heat exchanger, forms part of a heat recovery loop 27. The heat recovery loop 27 represents, or forms part of, a heat recovery arrangement adapted to transfer heat from the cooler to the heater of the facility and labeled 6.

[0033] In general, as used herein, the “cold side” of a heat exchanger is the side where heat is absorbed by the fluid circulating therein, and the “hot side” of a heat exchanger is the side where heat is released by the fluid circulating therein.

[0034] The cooler includes a hot side 25H of a second heat exchange 25. The second heat exchanger 25 includes said hot side 25H and a cold side 25C. The hot side 25H of the second heat exchanger 25 forms part of the closed calibration loop 5 and the cold side 25C of the second heat exchanger 25 forms part of the heat recovery loop 27. Heat is transferred from the fluid flowing in the closed calibration loop 5, and in the hot side 25H of the second heat exchanger 25, to a heat transfer fluid flowing in the heat recovery loop 27 and in in the cold side 25C of the second heat exchanger 25.

[0035] The heat recovery loop 27 is further in heat exchange relationship with a heat source 31, through which heat can be delivered to the heat recovery loop 27 and finally to the closed calibration loop 5. In some embodiments, the heat source 31 can include a furnace, a burner, a solar concentrator or the like, for instance, or can receive heat therefrom. The heat source 32 is adapted to transfer heat to the heat transfer fluid circulating in the heat recovery loop 27. Heat delivered to the heat recovery loop 27 by the heat source 31 is indicated as Qin.

[0036] In some embodiments, the heat recovery loop 27 is further in heat exchangerelationship with a heat sink 33, where through heat can be rejected from the heat recovery loop 27, and therefore from the closed calibration loop 5, for example by heat exchange with a cooling fluid, such as air or water. Heat removed from the heat recovery loop 27 through the heat sink 33 is indicated as Qout.

[0037] A further flow circulation device 35, for instance a pump, circulates the flow transfer fluid in the heat recovery loop 27.

[0038] In other embodiments, either one or both the heat sink 33 and the heat source 31 can be in heat exchange with the closed calibration loop 5, rather than with the heat recovery loop 27. The alternative position of the heat source and heat sink are shown in dotted lines in Fig.l and labeled 3 IX and 33X.

[0039] The facility 1 further includes at least a primary fluid tank or vessel 41 adapted to contain a main or primary fluid component, for instance carbon dioxide, at a suitable pressure. The primary fluid vessel 41 can be fluidly coupled with the closed calibration loop 5 through a control valve 43. The primary fluid vessel 41 can contain supercritical carbon dioxide (sCCh) and can be connected through control valve 43 with the cold section of the closed calibration loop, i.e., the section between the outlet of the hot side 25H of the second heat exchanger 25 and the inlet of the cold side 23C of the first heat exchanger 23.

[0040] In some embodiments, the facility 1 can include a mass measuring device, adapted to measure the mass of main fluid component dispensed into the calibration loop 5. For instance, the mass measuring device may include a Coriolis flowmeter 42 the vessel 41 and calibration loop 5. In other embodiments, the vessel 41 can be placed on a scale 46, which detects the wight reduction when the main fluid is dispensed from the vessel 41 into the calibration loop 5.

[0041] Since the calibration loop 5 is a closed volume, the final pressure depends on the initial mass of fluid fed into the calibration loop 5. Therefore, when the calibration loop 5 is filled for the first time, the initial mass of fluid dispensed therein shall be correctly dimensioned.

[0042] Through the control valve 43 the closed calibration loop 5 can be filled with carbon dioxide, or another main fluid component, at a desired pressure, equal to orlower than the pressure inside the vessel 41.

[0043] In embodiments, the facility 1 further includes one or more additional vessels 45 containing one or more dopants and / or secondary fluid components to be blended with the main fluid component in the closed calibration loop 5.

[0044] In the embodiment of Fig. 1 the facility 1 comprises one additional vessel 45, which can be fluidly coupled with the cold section of the closed calibration loop 5 through a control valve 47. A dopant or a secondary fluid component contained in vessel 45 can therefore be added at the desired pressure through valve 47 to the closed calibration loop 5.

[0045] It shall be understood that a plurality of such additional vessels 45 and relevant control valves 47 can be provided, each containing a different component, such as a different dopant or blend of dopants and / or a different secondary fluid component or blend of fluid components.

[0046] A fluid composition analyzer 49 can further be fluidly coupled to the closed calibration loop 5, to detect the molar composition of the process fluid circulating in the closed calibration loop 5. The analyzer 49 can comprise a gas chromatograph, a spectrometer, or any other analyzer adapted to operate at the temperature and pressure conditions of the fluid circulating in the cold section of the closed calibration loop 5.

[0047] The calibration loop 5 can further include an exhaust valve 51, adapted to vent fluid from the calibration loop 5 into the environment, in order to final pressure within the calibration loop 5 can be reduced.

[0048] The facility 1 described so far operates as follows. A device under test (DUT) 3, for instance a metering device such as a flowmeter, is fluidly coupled to the closed calibration loop 5 by connecting the inlet and the outlet thereof to the inlet connection 5A and the outlet connection 5B, respectively.

[0049] The closed calibration loop 5 is then filled with a process fluid at the desired pressure. The process fluid can be carbon dioxide, carbon dioxide containing one or more dopants, a blend containing carbon dioxide as a primary fluid and one or more secondary fluids (such as water steam), with or without additional dopants, forinstance. As understood herein, a dopant is usually a component of the process fluid which is added for the purpose of modifying the phase diagram of the process fluid, such as the critical point and / or the transition lines. As understood herein, a secondary fluid is a fluid which is present in the process fluid in a real thermodynamic cycle (e.g., water in an oxyfuel thermodynamic cycle). More than one dopant and / or more than one secondary fluid can be present in the process fluid circulating in the closed calibration loop 5.

[0050] The composition of the process fluid in closed calibration loop 5 is selected on a case-by-case basis, depending on the actual composition of the process fluid which will be used in the thermodynamic cycle, wherein the DUT 3 will be used after calibration. The composition can be changed during a calibration procedure, if required or desirable.

[0051] The pressure in the closed calibration loop 5 is selected based on the actual pressure which will be present in the section of the thermodynamic cycle, in which the DUT 3 will be installed after calibration. Typically, if the DUT 3 is used in an oxyfuel combustion cycle, the pressure can range between 300 and 400 barA, for instance. The pressure in the closed calibration loop 5 can be varied during the calibration procedure, if required or desirable.

[0052] The composition and pressure of the process fluid in the closed calibration loop 5 are achieved by selectively operating the valves 43, 47. As noted above, while in Fig.l a single vessel 45 for a dopant or a secondary fluid component is shown, in other embodiments, a larger number of vessels 45 and relevant valves 47 can be provided in the facility 1, so that variable compositions of the process fluid can be used for calibrating the same or different DUTs 3.

[0053] The circulation device 19 circulates the process fluid in the closed calibration loop, overcoming the head losses along the closed calibration loop 5. Depending upon the kind of DUT 3, one or more reference metering devices of the reference metering unit 7 can be activated, by selectively opening one or more valves 15, 17 of the valve arrangement 13.

[0054] The pressure of the process fluid and the composition thereof can be selectedaccording to needs and can be varied during the same calibration procedure of the same DUT 3 by adding one or more fluid components or dopants during the test procedure through valves 43, 47. The actual composition of the process fluid can be continuously or discontinuously detected by the fluid composition analyzer 49.

[0055] The temperature of the process fluid flowing through the DUT 3 is achieved and maintained, or varied during the calibration procedure, using the heat recovery loop 27 and relevant heat source 31 and heat sink 33. Specifically, the heat source 31 delivers thermal power Qin to the heat transfer fluid circulating in the heat recovery loop 27 and the heat sink 33 removes thermal power Qout from the transfer fluid circulating in the heat recovery loop 27.

[0056] Hot heat transfer fluid exiting the heat source 31 circulates in the hot side 23H of the first heat exchanger 23 in heat exchange with the process fluid, which circulates in the cold side 23C of the first heat exchanger 23. Heat is thus transferred from the heat transfer fluid circulating in the heat recovery loop 27 to the process fluid circulating in the closed calibration loop 5. The process fluid in the closed calibration loop 5 is heated till the required temperature is achieved, at which the DUT 3 shall be tested and calibrated. For instance, if the DUT 3 is intended to be used in an oxy-fuel combustion cycle, the test temperature can be between 500°C and 600°C, e.g., between 550°C and 570°C.

[0057] The temperature as well as the pressure values mentioned herein are by way of example and shall not be considered as a limitation of the present disclosure.

[0058] The second heat exchanger 25 is used to cool the process fluid exiting the DUT 3 upstream of the reference metering unit 7. The process fluid flows though the hot side 25H of the second heat exchanger 25 in heat exchange with the cold side 25C of the second heat exchanger 25, such that heat is removed from the process fluid, recovered through the heat transfer fluid circulating in the heat recovery loop 27 and transferred to the first heat exchanger 23.

[0059] The process fluid exiting the hot side 25H of the second heat exchanger 25 is at a temperature lower than the temperature of the process fluid flowing through the DUT 3. For instance, the temperature of the process fluid exiting the second heatexchanger 25 can be between 100 °C and 200 °C.

[0060] The thermodynamic conditions (temperature and pressure) of the process fluid flowing though the reference metering unit 7 are such that they fall within a range where the equation of state of the process fluid is known or the flow can be accurately measured

[0061] Heat removed from the process fluid in the second heat exchanger 25 is recovered and used to heat the process fluid in the first heat exchanger 23 arising the temperature of the process fluid from the low temperature present in the reference metering unit 7 to the high temperature required in the DUT 3.

[0062] The first heat exchanger 23 and the second heat exchanger 25 therefore divide the closed calibration loop 5 in a hot section and a cold section. The hot section extends from the outlet of the cold side 23 C of the first heat exchanger 23 to the inlet of the hot side 25H of the second heat exchanger and includes the DUT 3, which temporarily forms part of the closed calibration loop 5. The cold section of the closed calibration loop 5 extends from the outlet of the hot side 25H of the second heat exchanger 25 to the inlet of the cold side 23C of the first heat exchanger 23 and includes the reference metering unit 7, the flow circulation device 19 and the flow controller 21.

[0063] The temperature of the process fluid in the hot section of the closed calibration loop 5 can be controlled by increasing or decreasing the amount of thermal power delivered thereto through the first heat exchanger 23. A portion of said thermal power is recovered from the process fluid through the second heat exchanger 25. If additional thermal power is required, for instance to compensate for heat losses in the closed calibration loop 5, or because a higher testing and calibrating temperature is required, additional thermal power can be supplied by the heat source 31.

[0064] Conversely, if the testing temperature in the hot section of the closed calibration loop 5 shall be reduced, heat can be removed from the process fluid through the heat transfer fluid circulating in the heat recovery loop 27 and through the heat sink 33.

[0065] With continuing reference to Fig.1, Fig.2 illustrates a diagram showing the temperature in various points of the heat recovery loop 27 and of the calibration loop5. Specifically, A and B are the inlet and outlet of the cold side 23 C of the first heat exchanger 23, E and F are the inlet and outlet of the hot side 25H of the second heat exchanger 25. Correspondingly, A’ and B’ are the outlet and the inlet of the hot side 23H of the first heat exchanger 23, and F’ and E’ are the inlet and the outlet of the cold side 25C of the second heat exchanger 25. D’ and C’ are the inlet and the outlet of the heat source 31; and EF and G’ are the inlet and outlet of the heat sink 33. The temperature of the two fluids circulating in the closed calibration loop 5 and in the heat recovery loop 27 are plotted on the vertical axis and are expressed in °K. The curve C5 represents the temperature trend in the closed calibration loop 5 and curve C27 represents the temperature trend in the heat recovery loop 27.

[0066] Operation flexibility of the calibration facility 1 is thus obtained in terms of thermodynamic testing conditions as well as in terms of chemical composition of the process fluid. Heat recovery through the heat recovery loop 27 increases the thermal efficiency of the facility 1.

[0067] A further calibration facility 1 according to the present disclosure is shown schematically in Fig.3. The same reference numbers indicate the same elements as already described in connection to Fig.1 , or elements having the same or similar function.

[0068] In the embodiment of Fig.3 the facility 1 comprises a closed calibration loop 5, which includes an inlet connection 5A and an outlet connection 5B, between which a device to be tested 3 can be connected to become temporarily part of the closed calibration loop 5.

[0069] The closed calibration loop 5 further comprises a reference metering unit 7, which in turn comprises an inlet 7A and an outlet 7B. In the embodiment of Fig.1 the reference metering unit 7 comprises a plurality of reference metering devices which are connected in parallel to one another and are all fluidly coupled to the inlet 7A and the outlet 7B. By way of non-limiting example, in Fig.3 the reference metering unit 7 includes a first reference metering device 9 and a second reference metering device 11. A valve arrangement 13 is further provided between the set of reference metering devices 9, 11 and the inlet 7A and / or the outlet 7B.

[0070] In the exemplary embodiment of Fig.3 the valve arrangement 13 comprises a first valve 15 in series with the first metering device 9, between the inlet 7A and the first metering device 9. The valve arrangement 13 further comprises a second valve 15 in series with the second metering device 11, between the inlet 7 A and the second metering device 11. The valve arrangement 13 allows to selectively isolate one or the other metering device 9, 11 from the closed calibration loop 5, such that a variable number of reference metering devices can be used during a calibration procedure, according to needs.

[0071] The closed calibration loop 5 further includes a flow circulation device 19, adapted to circulate a fluid in the closed calibration loop 5. The flow circulation device 19 can include a pump adapted to overcome the head losses along the closed calibration loop 5. The flow circulation device 19 can be arranged in any suitable position along the closed calibration loop 5. As will be described in detail below, the closed calibration loop 5 includes a hot section and a cold section. In preferred embodiments, the flow circulation device 19 is positioned along the cold section of the closed calibration loop 5, such that process fluid contacting the mechanical components of the flow circulation device 19 is at a lower temperature, such that damages or wear of the flow circulation device 19 are reduced.

[0072] In the embodiment of Fig. 3 the flow circulation device 19 is arranged between the outlet 7B of the reference metering unit 7 and the inlet connection 5A, and more specifically upstream of a heat-recovery heat exchanger 61, to be described below and which forms part of a heat recovery arrangement, labeled 6.

[0073] The closed calibration loop 5 further includes a flow controller 21. In the embodiment of Fig.3 the flow controller 21 is arranged along the cold section of the closed calibration loop, upstream of the reference metering unit 7. In other embodiments the flow controller 21 can be positioned in a different location along the cold side of the closed calibration loop 5. For instance, the flow controller 21 can be arranged upstream or downstream of the flow circulation device 19, or can be integrated therein. Arranging the flow controller in the cold section of the closed calibration loop 5 reduces wear and damages to the flow controller 21.

[0074] The heat-recovery heat exchanger 61 comprises a hot side 61H and a coldside 61C in heat exchange relationship. The hot side 61H of the heat-recovery heat exchanger 61 forms part of the cooler of the closed calibration loop 5, while the cold side 61C of the heat-recovery heat exchanger 61 forms part of the heater of the closed calibration loop. The process fluid which circulates in the closed calibration loop is heated when circulating through the cold side 61C of the heat-recovery heat exchanger ad is cooled when circulating though the hot side 61H thereof.

[0075] More specifically, the process fluid in the closed calibration loop 5 circulates sequentially through the cold side 61C, through the device under test 3 and through the hot side 61H of the heat exchanger. In operation, hot process fluid flows from the device under test 3 through the hot side 61H of the heat exchanger 61 and exchanges heat against cold process gas from the circulation device 19, which flows through the cold side 61C of the heat exchanger 61. With this arrangement the temperature of the process fluid can be reduced before entering the reference metering unit 7. Heat removed from the process fluid is recovered through the heat exchanger 61 and used to heat the process gas flowing from the reference metering unit 7 in the device under test 3.

[0076] The recovery of heat thus achieved reduces the amount of thermal energy which shall be provided to the facility 1 during a test process.

[0077] The heat exchanger 61 divides the closed calibration loop 5 in a cold section and a hot section. The cold section extends from the outlet of the hot side 61H of the heat exchanger to the inlet of the cold side 61C of the heat exchanger. The hot section extends from the outlet of the cold side 61C to the inlet of the cold side 61H of the heat exchanger.

[0078] Similarly to what is described with reference to Fig.1, also in the embodiment of Fig.3 the facility 1 comprises a heat source 31 and a heat sink 33. Contrary to the embodiment of Fig.1, however, the heat source 31 and the heat sink 33 are arranged along the closed calibration loop 5, i.e., in direct heat exchange therewith, rather than with a heat transfer loop. The heat sink 33 is adapted to remove heat from the process fluid circulating in the closed calibration loop 5 and the heat source 31 is adapted to supply heat to the process fluid circulating in the closed calibration loop 5.

[0079] In this arrangement, therefore, the heat source 31 forms part of the heater, in combination with the cold side 61C of the heat-recovery heat exchanger 61. Similarly, the heat sink 33 forms part of the cooler, in combination with the hot side 61H of the heat-recovery heat exchanger 61.

[0080] Other elements of the embodiment of Fig.3 which are the same as in Fig.l, are labeled with equal reference numbers and are not described again.

[0081] Fig. 4 illustrates a diagram showing the temperature of the process fluid in various points of the closed calibration loop 5. Letters A, B, C, D, E, F, G, H, I, L in the diagram of Fig.4 correspond to positions labeled with the same letters A to L in Fig.3. Heat is transferred by the heat-recovery heat exchanger 61 from the hot side of the heat-recovery heat exchanger 61 between points G and H to the cold side of the heat-recovery heat exchanger between the points A and B. Recovered heat is pictorially represented by arrows Qrec in Fig.4. Fig.5 illustrates the temperature of the fluid in the cold side and hot side of the heat-recovery heat exchanger 61.

[0082] While in Figs.to facilities 1 are disclosed, which include heat recovery, in combination with optional ancillary devices, adapted to vary the testing temperature and pressure, as well as the chemical composition of the process fluid, in other embodiments some of the ancillary components can be omitted.

[0083] Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various changes, omissions and additions may be made to that which is specifically disclosed herein without departing from the scope of the invention as defined in the following claims.

Claims

1. A device for calibrating a dosing device, comprising a closed calibration circuit configured to circulate a primary fluid therein; wherein the closed calibration circuit comprises an input connection and an output connection configured to connect the fluid medium of the dosing device to be calibrated to the closed calibration circuit; a reference dosing unit containing an inlet and an outlet; a flow circulation device configured to circulate a fluid medium in a closed calibration loop; a heater between the outlet of the reference dosing unit and the inlet connection of the dosing device to be calibrated; and a cooler between the outlet connection of the dosing device to be calibrated and the inlet of the reference dosing unit; and at least a first vessel configured to accommodate therein at least the first of a dopant and a secondary component of a fluid medium, which are added to a primary fluid medium circulating in a closed calibration circuit to change the chemical composition of the primary fluid medium circulating in a closed calibration circuit.

2. The device according to claim 1, in which the flow circulation device is located between the outlet of the reference dosing unit and the heater.

3. The device according to item 1 or 2, further comprising a fluid composition analyzer configured to analyze the composition of a fluid circulating in a closed calibration circuit.

4. The device according to any of the preceding claims, further comprising a heat source configured to transfer heat to the device.

5. The device according to any of the preceding claims, further comprising a heat sink configured to remove heat from the device.

6. The apparatus according to any of the preceding claims, further comprising a heat recovery system configured to transfer heat from the cooler to the heater.

7. The device according to paragraphs 4, 5 or 6, in which the heat recovery system comprises a closed heat recovery loop configured to remove heat from the closed calibration loop through a cooler and release heat in the closed calibration loop through a heater.

8. The device according to paragraph 7, in which the heater comprises a cold side of a first heat exchanger, wherein the cold side of the first heat exchanger forms part of a closed calibration circuit, and wherein the hot side of the first heat exchanger forms part of a closed heat recovery circuit; and the cooler comprises a hot side of a second heat exchanger, wherein the hot side of the second heat exchanger forms part of a closed calibration circuit, and wherein the cold side of the second heat exchanger forms part of a closed heat recovery circuit.

9. The device according to any one of paragraphs 7 or 8, depending on paragraph 4, in which the heat recovery circuit is in heat exchange interaction with the heat source and is designed with the possibility of receiving heat from the heat source and transferring heat from the heat source to the closed calibration circuit.

10. The device according to any one of paragraphs 7, 8 or 9, depending on paragraph 5, in which the heat recovery circuit is in heat exchange interaction with the heat sink and is designed with the possibility of transferring heat removed from the closed calibration circuit to the heat sink.

11. The apparatus of claim 6, wherein the heat recovery system comprises a heat exchanger-utilizer having a cold side and a hot side; wherein the cooler comprises the hot side of the heat exchanger-utilizer, and the heater comprises the cold side of the heat exchanger-utilizer.

12. The device according to paragraph 4 or 11, in which the heat source is in heat exchange interaction with the closed calibration circuit and is designed with the possibility of transferring heat directly to the closed calibration circuit.

13. The device according to paragraph 5, or 11, or 12, in which the heat sink is in heat exchange interaction with the closed calibration circuit and is designed with the possibility of removing heat directly from the closed calibration circuit.

14. The device according to any one of the preceding claims, further comprising a first pressure control valve between the first vessel and the closed calibration loop, wherein the first pressure control valve is configured to control the pressure of said alloying additive or said secondary component of the fluid in the closed calibration loop.

15. The device according to any one of the preceding claims, further comprising a primary fluid vessel configured to contain therein the primary fluid supplied to the closed calibration loop.

16. The device of claim 15, further comprising a second pressure control valve between the primary fluid vessel and the closed calibration loop, wherein the second pressure control valve is configured to control the pressure of the primary fluid in the closed calibration loop.

17. A device according to any one of the preceding claims, wherein the reference dosing unit comprises at least a first reference dosing device.

18. A device according to any one of the preceding claims, wherein the reference dosing unit comprises a plurality of reference dosing devices connected in parallel and a valve system configured to selectively connect one or more of said reference dosing devices in a closed calibration loop.

19. A method for calibrating a dosing device, comprising the following stages: circulating a fluid mixture in a closed calibration circuit through a dosing device to be calibrated and through a reference dosing unit, wherein the fluid mixture comprises a primary fluid medium and at least one alloying additive or one secondary fluid medium, or a combination thereof; wherein at least one alloying additive or one secondary fluid medium is added to the primary fluid medium to change its chemical composition; heating the fluid mixture circulating in a closed calibration circuit in a heater located between the outlet of the reference dosing unit and the inlet of the dosing device to be calibrated; cooling the fluid mixture in a cooler located between the outlet of the dosing device to be calibrated and the inlet of the reference dosing unit; calibration of the dosing device to be calibrated based on the measurement data of the reference dosing unit.

20. The method according to claim 19, further comprising the step of determining the composition of the fluid mixture circulating in the closed calibration circuit.

21. The method according to claim 19 or 20, further comprising the step of recovering heat removed by the cooler and transferring the recovered heat to the heater.

22. The method of claim 21, wherein the heat recovery step includes the step of transferring heat from the cooler to the heater through a heat recovery fluid circulating in the heat recovery circuit.

23. The method according to claim 22, wherein the heat recovery step comprises the following steps: removing heat from a fluid medium circulating in a closed calibration circuit through a cooler, wherein the fluid medium for heat recovery circulates in the cold side of the cooler, performing heat exchange with the fluid medium circulating in the closed calibration circuit; transferring the recovered heat to a fluid medium circulating in a closed calibration circuit through a heater, wherein the fluid medium for heat recovery circulates in the hot side of the heater, performing heat exchange with the fluid medium circulating in the closed calibration circuit.

24. The method of claim 21, wherein the cooler comprises a hot side of the heat exchanger-utilizer, and the heater comprises a cold side of the heat exchanger-utilizer; wherein the hot side and the cold side of the heat exchanger-utilizer are located in a closed calibration loop; wherein the dosing device to be calibrated is located in the closed calibration loop between the cold side and the hot side of the heat exchanger-utilizer; and wherein the hot fluid mixture circulating in the hot side of the heat exchanger-utilizer transfers heat to the cold fluid mixture circulating in the cold side of the heat exchanger-utilizer.

25. The method according to any one of paragraphs 19-24, further comprising at least one of the following steps: supplying heat to the fluid mixture through a heat source; and heat removal from the fluid mixture through a heat sink.