Simulation mixture

Abstract

The invention relates to a mixture having, under a pressure of between 5 and 6 bar and at a temperature of between 15 and 25°C, the following properties: - two-phase flow, with at least one liquid phase and one gas phase; - a liquid-phase density (ρliq) of between 700 and 800 kg.m-3; - a gas-phase density (ρgaz) of between 30 and 40 kg.m-3; - a surface tension (σ) of between 0.015 and 0.030 N.m-1. The invention also relates to a test model (1) for studying a vibratory behaviour when filled with such a mixture, and to a method for producing same. The invention also relates to a method for producing or modifying such an industrial facility including the use of such a model, and to the industrial facility thus obtained.

Description

Description Title: Simulation Mix Technical field

[0001] This disclosure relates to the field of metrology and physical simulations of fluid behaviors. Prior art

[0002] When studying industrial installations with severe operational or critical conditions involving fluid circulation, it is usual to carry out tests on a reduced scale and under less severe laboratory conditions. When the operational conditions include extreme temperatures and / or pressures, i.e. conditions far from ambient conditions, it is desirable to be able to conduct simulations and studies under laboratory conditions for obvious cost and safety reasons.

[0003] To maintain the relevance of fluid circulation studies, including vibration studies, carried out in the laboratory despite laboratory conditions that differ from operational conditions, it is known to replace the "operational fluid" with a "simulating fluid". Such a simulating fluid is selected to present, under laboratory conditions, properties and behaviors similar to those of the operational fluid under operational conditions. In other words, the differences in conditions are compensated for by the very nature of the fluid used to maintain the representativeness of the studies and simulations.

[0004] When the operating fluid has a two-phase flow, for example a water-steam mixture, and the simulating fluid is different from the water-steam mixture, this is called a "two-phase similarity" effect.

[0005] The known simulant fluids are known because they have a level of similarity considered satisfactory in their properties and behaviors with those of an operational fluid under given operational conditions. The applicant has tried to use some of these known simulant fluids in particular contexts, in particular that of a steam generator intended to equip a nuclear reactor, with temperatures of the order of 300°C and pressures of the order of 70 bars by means of a simulation at ambient temperature (of the order of 20°C) and under a pressure of between 5 and 6 bars. The level of similarity of the known simulant fluids was considered perfectible. Summary

[0006] This disclosure improves the situation.

[0007] A mixture is proposed with the following properties under a pressure between 5 and 6 bars and a temperature between 15 and 25°C: - two-phase flow, with at least one liquid phase and one gas phase; - a density of the liquid phase (piiq) between 700 and 800 kg.nr 3 ; - a density of the gas phase (p gaz ) between 30 and 40 kg.nr 3 ; - a surface tension (o) between 0.015 and 0.030 N.nr 1 .

[0008] According to another aspect, there is provided a test model for the study of a vibrational behavior comprising at least one vein within which a two-phase flow can be generated in a controlled manner, said vein being filled with a mixture as defined herein.

[0009] Also provided is a method of manufacturing such a model comprising filling a test model for the study of vibrational behavior comprising at least one vein within which a two-phase flow can be generated in a controlled manner, with a mixture as defined here.

[0010] A method of manufacturing or modifying an industrial installation is also proposed, comprising: A. carry out tests and / or measurements on such a model; B. determine a structure of an installation based on the results of said tests and / or measurements; C. manufacture or modify an installation so as to give it the structure thus determined.

[0011] Finally, an industrial installation obtained by implementing the above process is also proposed.

[0012] The features set out in the following paragraphs may, optionally, be implemented, independently of each other or in combination with each other:

[0013] In the mixture: - the liquid phase comprises, between 50% and 100% by volume of the liquid phase, a mixture of hydrocarbon-based solvents whose name according to the IUPAC nomenclature is “Hydrocarbons, C9-C10, n-alkanes, isoalkanes, cyclics, <2% aromatics”, bearing the EC number “927-241-2” and the REACH registration number “01-21 19471843-32”, and - the gas phase comprises, for at least 95% by volume of the gas phase, a chlorofluorocarbon (CFC) or a hydrochlorofluorocarbon (HCFC).

[0014] In the mixture: - the liquid phase comprises, for at least 95% by volume of the liquid phase, a product marketed under the commercial reference “Neutralene 2012” and the brand “iBiotec ®” by “Tec Industries ® Service” bearing the code “160812” and the UFI “KECC-9FFW-000T-EXYM”, and - the gas phase comprises, for at least 95% by volume of the gas phase, Hexafluoroethane.

[0015] The mixture also has at least one of the following properties under a pressure of between 5 and 6 bars and a temperature of between 15 and 25°C: - a dynamic viscosity of the liquid phase (piiiq) between 5 and 6.10 -4 Not ; - a dynamic viscosity of the gas phase (p gaz ) between 1 and 2.10 -5 Not ; - a ratio of the density of the liquid phase (piiq) to the density of the gas phase (p gaz ) between 20 and 27; - a ratio of the dynamic viscosity of the liquid phase (piiiq) to the dynamic viscosity of the gas phase (p ga z) between 40 and 45. Brief description of the drawings

[0016] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which: Fig. 1

[0017] [Fig. 1] shows a diagram of a steam generator for which the use of a model according to one embodiment may be particularly relevant. Fig. 2

[0018] [Fig. 2] shows a longitudinal sectional view of a portion of vein of a model according to one embodiment. Context and Genesis

[0019] The applicant specializes in electricity production, which involves studying, designing, building, maintaining and improving electricity production facilities, including nuclear power plants. In this context, it conducts studies on the flow phenomena occurring within steam generators equipping said power plants in order to better understand, anticipate and prevent possible mechanical effects (fatigue phenomena under vibration for example) resulting from the two-phase flow of a water-steam mixture. In operational conditions, these steam generators are subjected to temperatures of around 300°C and pressures of around 70 bars. In critical conditions, to be avoided but studied, the conditions can be even more severe. Such conditions are expensive and dangerous to reproduce in the laboratory.The applicant therefore set about identifying “simulating fluids” enabling it to carry out tests representative of the behavior of the water-steam mixture at 300°C and 70 bars while working at reduced temperature (preferably ambient, such as 20°C) and reduced pressures of between 5 and 6 bars.

[0020] Although the studies and tests were carried out by the applicant in a specific and particular context described here (steam generators in nuclear power plants), it appears that the solutions identified are easily transposable and likely advantageous when applied in other contexts and / or in other temperature and pressure conditions.

[0021] In particular with regard to the nature (composition) of the simulant fluids proposed below, it would appear that these compositions are themselves innovative independently of the use as simulant fluid, which explains the applicant's wish to obtain general protection on such two-phase fluid compositions.

[0022] It is specified here that the use of the terms "simulation" or "simulant" refers to the conditions of tests on physical models as opposed to operational or critical conditions. industrial installations. However, the simulations also remain real and physical: these terms do not refer to purely digital or computer simulations. Application to a steam generator

[0023] Reference is now made to [Fig. 1], an example of a steam generator 100 such as those used in nuclear power plants is shown therein. From bottom to top in the figure, the following assemblies are shown: - a bundle of exchanger tubes 101; - cyclone separators 102; - dryers 103.

[0024] The vertical arrow 104 on the left represents, very schematically, the increase in the steam rate within the generator (from 0 to 100%). The small unreferenced arrows represent the circulation of the heat transfer fluid (generally a water-steam mixture), the dark (solid) arrows representing a “hot” fluid (of the order of 300°C in the example described here) while the light arrows represent a cold fluid. Finally, the circled zone 105 is a zone within which a transverse flow takes place (around the tubes) in operation while the circled zone 106, called “bun”, is a zone within which a transverse flow (around the tubes) also takes place in operation and this flow is, often, two-phase.

[0025] [Fig. 1] therefore represents a real but non-limiting example for which the use of a model 1 as described below has particular advantages. The applicant has in fact observed, in practice, phenomena of wear and degradation that are faster than initially predicted in the circled zone 105 and even more pronounced in the circled zone 106. By implementing models as described below, it has succeeded in generating localized vibrations which, themselves, have made it possible to reproduce the phenomena of interest, in particular vibration, wear, or even premature degradation. The applicant has therefore observed and quantified these phenomena which were non-existent, therefore unpredictable and inevitable by the use of purely digital simulations or models of the prior art.

[0026] Reference is now made to [Fig. 2] schematically and partially representing a model 1. The model 1 may be to scale (1:1) or be a reduced model of an installation or part of an installation, whether the installation is existing or in the design or construction phase. The model 1 comprises at least one vein 2 inside which, in operation, a fluid flows. The flow 3 (or flux) is represented by arrows. The vein 2 is delimited by a wall 4. In the part represented in [Fig. 2], the wall 4 and the vein 2 which it delimits extend according to the flow direction referenced Z (vertical direction of [Fig. 2]).

[0027] Model 1 includes, or is shaped to be connected to, a system (not shown) capable of generating a two-phase flow in a controlled manner.

[0028] In the example described here, the model 1 further comprises obstacles 5 arranged in the flow. The obstacles 5 here take the form of elongated elements, for example a bundle of elements elongated. The elongated elements extend in a direction transverse to that of the flow 3, here in the direction referenced Y (direction perpendicular to the plane of [Fig. 2]). Thus, the obstacles 5 are visible in [Fig. 2] in section according to their own cross sections. The obstacles 5 of the model 1 of [Fig. 2] correspond for example to the pipes present in the generator represented in [Fig. 1], Preliminary tests

[0029] An air-water mixture can be considered as a simulating fluid, including at atmospheric pressure. The two-phase flow behavior of an air-water mixture under ambient conditions is not comparable to that of a water-steam mixture at 300°C and 70 bars of pressure: the representativeness of the tests thus carried out is poor.

[0030] A water-freon mixture has a better representativeness than an air-water mixture, considered conservative for the applications described above, probably thanks to a density ratio equivalent to that of the operating fluid. But the surface tension remains quite different, which further limits the representativeness. In addition, the implementation cost remains high because operating pressures can reach 10 bars.

[0031] Saturated chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), more commonly known as "Freon," can also be used as a simulant fluid. Like the water-steam operating fluid, saturated Freon is a single-component, two-phase fluid. It has an interesting level of similarity, although it is not entirely satisfactory. Its implementation remains expensive because a pressurized loop is required to give it densities close to those of the operating fluid. Working pressures remain high, reaching up to 30 bars for good representativeness.

[0032] A water-steam mixture, identical in nature to the operational fluid, can also be used as a simulating fluid. Of course, achieving good representativeness involves approaching operational temperature and pressure conditions, which we want to avoid for reasons already mentioned. It should also be noted that high temperatures (around 300°C) present another significant metrological disadvantage: a large number of sensors required for studies are unusable. The instrumentation of a model is therefore expensive and complex. Example of mixing

[0033] The applicant tried to use, as a simulating fluid, a first mixture called here “Neutralene® 2012-Freon”.

[0034] “Neutralene® 2012” is the trade name of a substance marketed under the brand name “iBiotec®” by “Tec Industries ® Service”. According to a safety data sheet revised on December 23, 2022, with version number “20”, it has the internal code “160812” and the unique formulation identifier (UFI) “KECC-9FFW-000T-EXYM”.

[0035] “Neutralene® 2012” essentially contains (50 to 100% by volume) a mixture of hydrocarbon-based solvents whose name, according to the nomenclature of the International Union of Pure and Applied Chemistry (IUPAC), is “Hydrocarbons, C9-C10, n-alkanes, isoalkanes, cyclics, < 2% aromatics”, has the EC number “927-241-2” and the REACH (“Registration, Evaluation, Authorization and restriction of CHemicals”) registration number “01-21 19471843-32”.

[0036] “Neutralene® 2012” may also contain traces (less than 1% by volume) of 1-methoxy-2-propanol, bearing the CAS number “107-98-2”, the EINECS (“European Inventory of Existing Commercial Chemical Substances”) number “203-539-1” and the REACH (“Registration, Evaluation, Authorization and restriction of CHemicals”) registration number “01-21 19457435-35”.

[0037] "Neutralene® 2012" is known and presented as a degreasing solvent, typically used as a machine cleaner in various industries. Therefore, there was no reason to consider it as a component of a simulant mixture.

[0038] "Freon" is the trade name for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). In the example described here, hexafluoroethane C2F6 is used (also called "perfluoroethane" or "R1 16"; IUPAC name: "1,1,1,2,2,2-hexafluoroethane; CAS number "76-16-4"; EC number "200-939-8").

[0039] When Neutralene® 2012 and Freon are combined and brought to the conditions of the simulating fluid (20°C and between 5 and 6 bars), they form two immiscible phases: they do not dissolve or only slightly dissolve in each other and do not react together.

[0040] Neutralene® 2012 forms a liquid phase, has a density at 5 bars close to that of water at 70 bars and a low surface tension close to that of the operating fluid (water-steam at 300°C and 70 bars). It also has the advantage of being non-flammable.

[0041] Freon, on the other hand, forms a gaseous phase with a density at 5 bars roughly equal to that of water at 70 bars. It remains heavier than air and non-combustible, which facilitates its use in laboratory conditions. Freons are particularly known for their use as a refrigerant.

[0042] The relative proportion of Neutralene® 2012 (liquid phase) and Freon (gaseous phase) in the mixture is selected according to the operating point (temperature and pressure of the simulating fluid under test conditions) so that this proportion, by volume, corresponds to that of the operating fluid (water-steam in the example) at the operational operating point (300°C and 70 bars in the example). Of course, this relative proportion of the liquid phase and the gaseous phase will be adapted according to the operating fluid, the operational conditions and the simulation conditions so as to correspond to that of the operating fluid.

[0043] The following comparative table shows some remarkable physical properties of various fluids.

[0044] [Table 1]

[0045] In [Table 1], the physical properties are as follows: - piiq is the density of the liquid phase in kg.nr 3 ; - Pgaz is the density of the liquid phase in kg.nr 3 ; - Ap is the difference in densities between the liquid and gas phases in kg.nr 3 ; ■ Piiq / Pg az is the ratio of the density of the liquid phase to that of the gas phase (unitless); - o is the surface tension in N.nr 1 ; - piiiq is the dynamic viscosity of the liquid phase in Pa.s expressed with a factor of 10 -6 ; - pgaz is the dynamic viscosity of the gas phase in Pa.s; ■ Piiq / Pg az is the ratio of the dynamic viscosity of the liquid phase to that of the gas phase (unitless).

[0046] Besides the fact that the components of the simulant fluid must be chemically stable over the timescale of the intended tests (so as not to degrade or react with each other) and preferably inexpensive and not very hazardous, only the physical properties of the mixture have a significant influence on the representativeness (the level of similarity) during the tests. As it appears in the values ​​of [Table 1], the mixture "Neutralene® 2012-Freon", as a simulant fluid, has densities equal to that of the operational fluid (water-steam at 300°C and 5 bar) and a similar surface tension, at least closer than that of other simulant fluids such as water-air or water-Freon mixtures. However, densities and surface tension are key properties in the choice of a simulant fluid to present a good representativeness of tests, measurements and studies of fluidic behavior.

[0047] Of course, the "Neutralene-Freon" mixture described above remains one example among others of simulant fluids. Other simulant fluids, of a different chemical nature, can present satisfactory levels of similarity. For example, other Freons than hexafluoroethane can be used. Indeed, all Freons have physical properties at moderate pressure, particularly in terms of densities and surface tension, which correspond particularly well to those of (water) steam at higher pressure (for example 70 bar). The example of hexafluoroethane is particularly well suited to tests under a pressure between 5 and 6 bar. For different test pressures, other Freons can for example be used, or vice versa, by referring to the thermodynamic tables of the components considered.

[0048] The multiplicity of possible combinations and levels of similarity considered satisfactory depending on the context of the studies makes it difficult to strictly delineate the physical properties to be respected in the choice of components of a simulating fluid. However, it would seem that adapting the composition of mixtures while respecting the following ranges of properties makes it possible to achieve, during simulations, particularly high levels of similarity, at least in the context of operational mixtures based on water-steam under pressures of the order of 70 bars and temperatures of the order of 300°C.

[0049] Mixtures with the following properties are particularly targeted. Under a pressure of between 5 and 6 bars and a temperature of between 15 and 25°C: - two-phase flow, with at least one liquid phase and one gas phase; - a density of the liquid phase (piiq) between 700 and 800 kg.nr 3 ; - a density of the gas phase (p gaz ) between 30 and 40 kg.nr 3 ; - a surface tension (o) between 0.015 and 0.030 N.nr 1 .

[0050] It should be noted here that the Water-air and Water-Freon mixtures in [Table 1] do not meet the properties indicated above. There may be a factor of approximately 4 between the values ​​of the operating fluid and the simulating fluid for densities and / or surface tension. On the contrary, the example of the “Neutralene® 2012-Freon” mixture as a simulating fluid has densities and surface tension values ​​that have a maximum difference of 20% with the corresponding values ​​of the operating fluid.

[0051] By selecting a simulant fluid with densities and surface tension equal to or nearly equal to those of the operating fluid, it becomes unnecessary to make assumptions (and therefore approximations) that are otherwise usual regarding the inlet flow rates of two-phase fluids.

[0052] Preferably, the mixture is selected so that the following physical properties are also respected (under a pressure between 5 and 6 bars and a temperature between 15 and 25°C): - a dynamic viscosity of the liquid phase (piiiq) between 5 and 6.10 -4 Not ; - a dynamic viscosity of the gas phase (p gaz ) between 1 and 2.10 -5 Not ; - a ratio of the density of the liquid phase (piiq) to the density of the gas phase (p gaz ) between 20 and 27; - a ratio of the dynamic viscosity of the liquid phase (piiq) to the dynamic viscosity of the gas phase (p gaz ) between 40 and 45.

[0053] Once the composition of the mixture has been determined, a model can be filled with it. Such a model comprises at least one vein 2 within which a two-phase flow 3 can be generated in a controlled manner. Once such a model is filled with the mixture, it can be used as a test model for the study of vibration behavior.

[0054] These tests may include, in particular: A. carry out tests and / or measurements on such a model 1; B. determine a structure of an installation based on the results of said tests and / or measurements; C. manufacture or modify an installation so as to give it the structure thus determined.

[0055] It is specified here that the term "installation" refers to any equipment or set of industrial equipment, for example a nuclear power plant for generating electricity and the heat exchangers that make it up.

[0056] The use of the mixtures described above as a simulating fluid, within a test model, makes it possible to achieve an excellent level of similarity of behavior in two-phase flow with laboratory conditions that are significantly less severe than those of the real installation, particularly in terms of temperature and pressure. The implementation of the tests is therefore much less expensive and less dangerous while being more reliable. In addition, standard (inexpensive) measuring instruments can be implemented (accelerometer, video capture, optical probes, etc.).

[0057] Thus, the applicant plans not only to manufacture and / or have manufactured such models but also the use of such models in the study, design, manufacture and modification of real installations, for example but not limited to: heat exchangers, steam generators and power plants, for example nuclear. The applicant also plans the design and manufacture of real installations based on data obtained by carrying out tests on such models. Industrial application

[0058] These technical solutions may be applied in particular to the manufacture of the mixtures thus defined, the filling of a vibration study model with such mixtures, the tests and results of tests carried out on such models, the use of the mixtures as a simulating fluid and the construction / modification of real installations based on data obtained by the implementation of such models.

[0059] This disclosure is not limited to the examples of models, methods of manufacturing models, use of such models and construction / modification of real installations based on data obtained by the implementation of such models described above, only by way of example, but it encompasses all the variants that may be envisaged by those skilled in the art within the framework of the protection sought. List of reference signs

[0060] - 1: model - 2: vein - 3: flow - 4: wall - 5: elongated element - 100: steam generator - 101: bundle of exchanger tubes - 102: cyclone separators - 103: dryers - 104: vertical arrow - 105: circled area - 106: circled area.

Claims

Claims

1. Mixture having the following properties under a pressure of between 5 and 6 bars and a temperature of between 15 and 25°C: - two-phase flow, with at least one liquid phase and one gas phase; - a density of the liquid phase (piiq) between 700 and 800 kg.nr 3 ; - a density of the gas phase (p gaz ) between 30 and 40 kg.nr 3 ; - a surface tension (o) between 0.015 and 0.030 N.rrr 1 .

2. Mixture according to claim 1, including: - the liquid phase comprises, between 50% and 100% by volume of the liquid phase, a mixture of hydrocarbon-based solvents whose name according to the IUPAC nomenclature is “Hydrocarbons, C9-C10, n-alkanes, isoalkanes, cyclics, <2% aromatics”, bearing the EC number “927-241-2” and the REACH registration number “01-21 19471843-32”, and - the gas phase comprises, for at least 95% by volume of the gas phase, a chlorofluorocarbon (CFC) or a hydrochlorofluorocarbon (HCFC).

3. Mixture according to one of the preceding claims, including: - the liquid phase comprises, for at least 95% by volume of the liquid phase, a product marketed under the commercial reference “Neutralene 2012” and the brand “iBiotec ®” by “Tec Industries ® Service” bearing the code “160812” and the UFI “KECC-9FFW-000T-EXYM”, and - the gas phase comprises, for at least 95% by volume of the gas phase, Hexafluoroethane.

4. Mixture according to one of the preceding claims, further having at least one of the following properties under a pressure of between 5 and 6 bars and a temperature of between 15 and 25°C: - a dynamic viscosity of the liquid phase (piiiq) between 5 and 6.10 4 Not ; - a dynamic viscosity of the gas phase (p gaz ) between 1 and 2.10 -5 Not ; - a ratio of the density of the liquid phase (piiq) to the density of the gas phase (p gaz ) between 20 and 27; - a ratio of the dynamic viscosity of the liquid phase (piiq) to the dynamic viscosity of the gas phase (p gaz ) between 40 and 45.

5. Test model (1) for studying vibratory behavior comprising at least one vein (2) within which a two-phase flow (3) can be generated in a controlled manner, said vein (2) being filled with a mixture according to one of the preceding claims.

6. Method for manufacturing a model according to the preceding claim comprising filling a test model (1) for studying vibratory behavior comprising at least one vein (2) within which a two-phase flow (3) can be generated in a controlled manner, with a mixture according to one of claims 1 to 4.

7. Method of manufacturing or modifying an industrial installation comprising: A. carrying out tests and / or measurements on a model (1) according to claim 5; B. determine a structure of an installation based on the results of said tests and / or measurements; C. manufacture or modify an installation so as to give it the structure thus determined.

8. Industrial installation obtained by implementing a method according to claim 7.

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