DE1927330A1 - Mixture flow analyzer - Google Patents

Description

Description
to the patent application

from Atomic Power Constructions Limited, 6/14 Sutton Court Road, Sutton, Surrey / England

concerning;
"Mixture flow analyzer"

The invention relates to a mixture flow analyzer, in particular to an analyzer for use with flow-through mixtures which are partially in the liquid phase and are partly in the gas phase.

In many cases it is necessary to analyze a flow in which there is a change in the physical status from liquid phase to vapor or gas phase. Case in point .is an aircraft ice detector because it is well known that the formation of ice on aircraft wings is potentially significant Moment of danger. A detector that shows the change in status between moist air and ice. In an air flow over the wings would be of considerable value.

Nuclear physics offers a second example. Dlehlorodifluromethane, commercially available as Arcton 12 (Trade Mark) is used as a model for the properties of liquids, that cook at high pressure, when examining

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Problems encountered with two phase conditions in a channel of a water-cooled nuclear reactor. Such investigations require an analyzer that is capable of the extent to which bubbles of gaseous freon form in liquid freon. The distinction between freon liquid and freon gas can essentially be done by a physical status detector, but only has one such instrument limited usefulness if it cannot analyze dynamic mixture flows. Detectors for the physical Status can have other disadvantages. For example, probes that are conductive are useful for d. this application is unusable, because both liquid and gaseous freon have a high electrical resistance. Hot wire probes can prove unsatisfactory, for example because of their slow response speed, their cost, and the like.

A third application is the study of chemical or fermentation processes that take place in a barrel or take place in a cauldron. An analyzer can determine the formation or the cessation of bubbles in the boiler and thus indicate that a certain stage in the process has been reached.

Many of the known arrangements which have been developed for these applications are difficult to manufacture and require undesirably long measuring tips. Such arrangements are generally based on the specific application in their usefulness limited and cannot be used for other applications without being recalibrated.

The object of the invention is to provide an analyzer for flowing To create mixtures that has a small probe tip, has a high response speed and without major difficulties can be produced. The analyzer should be versatile and can be used for a wide variety of purposes without the need for one specific calibration can be used.

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This object is achieved according to the invention by a light system for projecting a light beam onto a window, which is so designed and arranged that changes in the optical properties of the flow behind the window for control the level of light reflected from the window and by a level detector of the reflected light, as well as by an analyzing device to display the amplitude of the change in the level of the reflected Liehts.

In the following description, the word "light" is used to denote not only visible radiation, but also from radiation in the ultraviolet and infrared regions of the spectrum.

"Optical ^ properties" is used to denote both of reflective as well as refractive properties.

"Flow" or "flow" means relative movement between the window and the mixture and closes the flow off Thin layers.

The analyzer according to the invention can also be an analyzer to display the frequency of change in the level of the reflected Embrace light.

The light system can comprise a light guide.

The window and the light detector can be on opposite sides Ends of the light guide be arranged.

Alternatively, the light guide can also have a U or V shape, with the window in the base of the U or at the top of the V and the light detector at the other end of the Light guide is located.

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The window can consist of a curvature of the light guide that is sharp enough that light from the light guide can escape if this is made possible by the optical properties of the flow behind the window.

Alternatively, the window can be a right circular cone be transparent material, the base plane of which is perpendicular to the beam of light projected by the light system. Of the Refractive index of the transparent material and the semi-vertical one The angles of the cone are chosen so that they are matched to the optical properties of the flow behind the window.

When the analyzer is operated in reflection mode, the window is preferably made by a cylinder made of transparant Material formed, the end face of which is transverse to the light beam which is projected by the light system.

4th

The devices for detecting the light can be one Photocell, a phototransistor or other photosensitive Electrical components include to generate an electrical signal that is representative of the level of the thrown back Light, and the analyzing device can be an output display device as well as processing devices of the electrical signal for actuating the output indicator include.

The light system can comprise a solid-state lamp which is excited by an alternating electrical signal source.

The application can process the electrical signal a trigger circuit which is actuatable when the electrical signal exceeds a threshold level. The output of the trigger circuit can be connected to an integrator unit for the purpose of averaging over time of the exit.

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An analyzer according to the invention can also comprise scanning devices which can be actuated for adjusting the position of the window relative to the flow.

According to the invention, a multiple head mixture flow analyzer is also proposed with a plurality of flow mixture analyzers as described above, the windows in such a configuration according to the flow conditions, that are to be measured, are arranged, and the outputs of the Detectors are combined and manipulated so that a visual display of the mixture distribution profile is achieved, as well as the Ratio of the mixture components on a display device .

The output display device can be a oscilloscope.

The invention shall hereinafter be considered with reference to the accompanying Drawings are explained in more detail, which represent embodiments of the subject matter of the invention.

Show it:

Fig. 1 in schematic form an arrangement according to the invention

• Finding suitable for use as a flow-through mixture analyzer suitable is, .

Fig. 2,

j5, and

4 alternative constructions of part of the assembly according to Fig. 1, where Fig. 4 is a sectional view,

Fig. 5 is a diagram for explaining the operation of the Arrangement according to Fig. 1,

6 shows part of the arrangement according to FIG. 1 for the application the reflection mode, '

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Pig. Figure 7 shows an alternative arrangement of part of the arrangement after Pig. 1,

Figure 8 is a vision chart division for another example of one Flow mixture analyzer according to the invention,

Fig. 9

and 10 alternative constructions of parts of the assembly according to Fig. 8,

Pig. 11 is a diagrammatic representation of an arrangement according to the invention useful for determining the formation of Ice crystals in a stream of moist air is suitable and '

Fig. 12 is a diagram of a multiple head flow mixture an- ' lysators according to the invention.

The arrangement of Figure 1 comprises a bundle of optical fibers 1, which at one end terminate in a tip 2 in a cone shape at an acute angle of 90 ° · The optical fibers 1 do not need to be coherently arranged. The refractive index the tip approaches that of the inner lining of the optical Fibers 1. A suitable fluid known in the art is placed on the inner surface between the fibers and at the top to reduce the light scattering. At the other end of the bundle, the wires are divided into two groups J5 and 4. One of the groups 3 is for receiving light from a light source 5 trained, while the other group 4 for the transmission of light to a light detector 6 is formed.

The light source comprises a light transmitter of a corresponding frequency, as well as an arrangement for aligning a light beam from the light transmitter along the fibers.der one group 3 of the fiber bundle I. A quartz iodide lamp is suitable as the light source

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whose light is focused through a lens with a large aperture on the branched end of one fiber group.

The tip 2 is formed as part of a probe 7; alternative constructions thereof are shown in Figs and 4 shown.

The probe according to FIGS. 2 or 2 consists of a glass rod about 2 mm in diameter, which is heated and pulled out is pointed to a diameter of 0.4 mm at the narrower end. The tip 2 is ground and polished, like this that there is a right-angled cone. Fig. 2 shows a straight probe construction and Fig. 3 shows an L-shaped construction » The probe can be bent barrel for certain other ways To be adapted to the purposes of the application that sharp kinks are avoided.

In certain applications it may be necessary for the tip to be particularly resistant to environmental conditions. The probe of Figure 4 was designed for this purpose. The tip 2 consists of sapphire at the end of a tapering sapphire rod 8. The rod 8 is protected by a metal cover which has been selected according to its physical properties. It is desirable to use a metal with thermal expansion properties that are compatible with Safir and by which the Safir is completely securely protected. In Fig. ^Ä a tapering titanium rod 9 is shown, which is soldered or welded to a section 10 of a pipe made of corrosion-resistant steel.

In operation, the probe tip 2 is in the closed position analyzing flow mixture. A scanning device 12 can be provided for adjusting the position of the tip 2. The probe tip is positioned relative to the flow so that its axis is coaxial with the flow and upstream

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directed or with the flow parallel to a surface of the pointed profile or in an intermediate position between these two limit positions.

The length of the probe 7 is determined by the required tip arrangement in the liquid or by the Area to be scanned by the tip if this condition exists. The cross-sectional area of the tip across The length of the bundle depends on the bubble size that is to be determined, taking for each tip cross-sectional area a minimum detectable bubble size exists for a given flow rate.

Before describing the detector 6 and the associated electrical equipment, the optical properties, of the arrangement will be explained with reference to FIG. Fig. 5 shows the end of a probe 7. A light beam, 'the * should actually run parallel to the axis of the fibers 1 in the direction of the tip 2 of the light source 5, is with the Reference numeral 13 denotes. The light beam 15 hits uie the interface 14 of the tip 2. The following from the The path traversing the light beam depends on the refractive and reflective properties of the interface 14.

If the beam 13 has an angle of incidence (perpendicular to the interface 14) of i ° and the tip material has a refractive index yes (at a certain light frequency) and the material at the interface has a refractive index u (at the same frequency) ₃ then it is Angle to the normal of the externally exiting refracted beam (if one exists) r ° and given by the known equation

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It is obvious that the angle i_ is given by the angle of the conical tip 2. Since the beam IJ enters the base of the cone perpendicularly (or at least very close to the perpendicular), the angle i_ is equal to (90 - half-perpendicular angle to the cone) ° *) i, is given by the choice of material for the conical tip 2., u has a first value, for example u, when the outer material is in the liquid phase and a second value, for example .ju, when it is in the vapor phase. By appropriately selecting the values for the cone angle and μ, the vapor value μ can be set in such a way that there is a total internal reflection in the conical tip. In this case, the beam is reflected against the interface 15, where it is reflected again in the direction of the light detector 6. By correctly defining the value μ , it is possible that there is no total internal reflection, in which case less light reaches the light detector 6. Accordingly, a change in the phase from liquid to gas causes a change in the external refraction index value es from μ to μ and a corresponding change in the light detected by detector 6,

It can accordingly be seen that the design of the probe 7 depends on which application is envisaged. However, the embodiment described is suitable for a wide range of applications.

If a cone of 90 ° vertical angle and a refractive index of 1.62 are used, the arrangement can distinguish between almost all liquids and gases. Total internal reflection takes place for these values if the external refractive index is less than 1.5. Accordingly, the probe is particularly suitable for mixtures of water (refractive index μ = and air (μ = 1.00) or, for example, Freon liquid

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(μ = 1.25 at and 67 ° C.) and Freon vapor (u = 1.02).

It can be seen that all mixtures of constituents with refractive indices which are sufficiently different that there is a noticeable change in the light level reflected by the probe tip can be analyzed with the arrangement according to the invention. Accordingly, there is no theoretical limitation on the arrangement with respect to the analysis of mixtures of different phases. Assuming that the refractive indices are appropriate, mixtures of liquids which are insoluble in one another can be analyzed. An analysis of liquid mixtures that are insoluble in one another can be of interest when pipelines are used in batches.

The above explanations dealt with 'the case that a change in the substances or their phase was accompanied by a change in the refractive index alone, while another too. The factor to be taken into account is when there is a change in phase or substance from a change in reflective properties is accompanied.

Fig. 6 shows a probe structure which for the loading) operating in reflection mode is suitable. The light guide 1 is terminated by a probe 27 which does not have a conical tip, as in the construction described above, but a flat surface 27 transversely to the axis of the light meter. Such a construction can be used in the analysis of mercury / air mixtures. When the surface 27 is surrounded by mercury, light from the light source 5 is reflected back through the surface 27 to the light detector 6. If, however, the surface 27 is surrounded by air, no light will be reflected on the surface 27 (or not to a noticeable degree and the beam will escape into the air reaches the detector 6. The

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Reflection mode of operation can be used in analysis of mixtures of components with sufficiently different reflection values.

It is envisaged that the probe will operate in reflection mode can be used for the analysis of liquid sodium / sodium vapor mixtures, for example in a cooling circuit sodium-cooled nuclear reactor.

In all embodiments, the light level at the light detector 6 is an indication value for the optical properties of the Substances at the end of the probe. The arrangement analyzes mixtures on the basis of different components of the mixture with different optical properties. The light will converted into a representative electrical signal using a phototransistor, e.g. The signal is then amplified and fed to a trigger unit 16. The trigger unit 16 is set above a predetermined value of the noise set (as a result of undesired light scattering), so that with changing conditions at the cone point 2 a series of square-wave pulses that change in width is produced.

An integrator unit 17 averages the output pulses from the trigger unit 16 to display the ratio of the constituents of the mixture. The integrator comprises a field effect transistor / fed by the trigger output pulses is used to control the charge of a capacitor through a Constant current wave. A discharge resistor across the capacitor allows the capacitor to hang up at a potential proportional to the mean pulse width. This potential is displayed on an output instrument l8 and represents the Ratio of the constituent parts. The integration period can be changed to suit a particular application adapt by changing the capacitor value.

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If a vapor / liquid mixture is analyzed, ' the probe can be used to plague bubbles. The output of the detector can be fed to an oscilloscope in the form of pulses, the width of which indicates the bubble size and the pulse rate of which gives some indication of the nature and rate resulting in blistering.

It will be appreciated that the arrangement can be used to indicate a void period of liquid flow. A Counter that is gated from the output of the trigger unit and counts the output pulses of a clock oscillator can be " are turned, and with appropriate calibration it gives a direct digital display of empty periods.

A digital indication of the number of bubbles that will form in a given period can be achieved through application a digital "event counter", which the Anza ^ hl the pulses in the output of the trigger counts.

In the embodiment described above, the light was fed from the light source 5 to a branch end 3 of the light guide 1, while the other end 4 was fed to a detector 6. Alternative constructions are possible, with one example is shown in FIG. Here e: n single bundle of optical fibers 33 transmits light from a source 30 to a tip 29. The light returning from the tip 29 is fed to a light detector J51 (the other electrical ones described above Devices, as described above, is connected upstream). A half-silvered mirror 32 is switched into the light path, around in a known way the sent and the returning. To separate light from each other and to prevent light from falling Source 30 reaches detector j51 directly.

Each of the exemplary embodiments described above can be operated with a solid-state lamp as the light source. The lamp can be driven by a high frequency source so that the light output is effectively chopped up. The use of cer-

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■ chopped light is particularly beneficial as the use by AC voltage amplifiers, which are connected downstream of the detector, is made possible. A specific example of a sol The system is shown in FIG.

The high-frequency source 33 for feeding the lamp 34 has a frequency of 100 MHz, and the lamp 34 is of the gallium-arsenide type. Block 35 represents an optical system comprising a mixture analyzer probe, as described above, from which the light returns to the detector and trigger circuitry 36. The output of the trigger circuit consists of a high frequency signal (due to the chopped nature of the light) that is pulse modulated according to changes in the optical properties at the probe tip. A counter 37 can be used to count the number of high-frequency oscillations in the trigger output, which take place during a predetermined period of time for the purpose of displaying the proportions of the mixture components. An "event counter"J> Q (with an appropriate low pass filter) can be used to count the changes in the optical properties of the window during a given period.

The use of a gallium arsenide lamp enables that the optical parts of the arrangement are very compact can be, as shown in Figs. A GaI lium arsenide lamp 39 is directly in a probe 4θ of the one described Type used so that the light is emitted in the direction of the probe tip '. The surface of the lamp 39 in contact with the probe 40 covers only part of the area of the probe cross-section, while the remaining part of the area is in use takes place for the reception of the returning light from the tip through a detector 4l. In Fig. 9 is the lamp 39 inserted centrally and surrounded by an annular detector 41.

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A slightly modified construction is in Pig. IO shown in which the lamp is arranged on an extended end portion Ser probe 40. It is believed that constructions are possible in those using Gallium-Ar --.- _:. ■ senid lamp is an integral part of the probe.

Mixture flow analyzers according to the invention can be used for the analysis of water / water vapor _{mixtures (for example in distillation or in VeT--:} ■ steam control), preon gas / freon liquid analysis (nuclear .. ■ physics), water / air analysis (cavitation problems), such as also in many other cases. The analyzers according to the invention are characterized by their versatility in that they do not have to be specially calibrated for each particular application.

The arrangement can be in clear or milky liquids work, regardless of their electrical conductivity or resistance.

The embodiment described above after the refraction mode can also be used to determine the formation of bubbles in liquid in a barrel or a kettle in which a. chemical or fermentation process is taking place, the formation of bubbles indicating that a certain stage of the process is taking place has been achieved. Similarly, the arrangement can be used to determine the cessation of the Blistering.

11 shows an ice detector according to the invention similar characteristics to the embodiments described above. A bundle of optical fibers 19 ends in a detector head 20 of a right-angled conical shape with an acute angle of 90 °. At the other end of the bundle 19 are the fibers divided into two groups 21 and 22. The group receives light

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from one source 23 while the other group is on a display panel 24 is attached. A hemispherical shield 25 shields the detector from contamination (e.g. to keep mud away from road surfaces, if the Detector is attached to a vehicle).

In operation, the detector is mounted on an aircraft wing, on a motor vehicle or, for example, a ship attached that a flow of air sweeps over the detector head. The air is then analyzed by the arrangement. determines whether there are ice crystals.

If there is moist air on the detector head, that is light occurring at the end of the fiber group 22 is low. However, when ice forms, much more light appears at the end of the fiber group 22. The increasing light serves as a warning to the observer of ice formation. Alternatively, an electronic Arrangement can be used to determine the light level according to the ice formation.

Fig. 12 shows four sets of flow analyzers similar to those of the first embodiment combined to form a multi-head mixture flow analyzer. The flow analyzer A includes an optical fiber 26a, probe 27a, and detector and trigger circuitry 28a. The flow analyzers B, C and D are of identical design and are provided with corresponding reference numerals. A common light source ^w: rd for feeding the optical fibers 26a, 26b used, 26c una 26d. The probes 27a, 27b, 27c and 27d are arranged in a configuration corresponding to the flow conditions to be measured. The outputs of the detectors and trigger circuits 28a, 28b, 28c, and 28d are combined in a combining unit so that there is a visual display of the mixture distribution profile and the mixture constituent ratios on an external display arrangement J> 1 (which can be an oscilloscope).

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The embodiments described above all include a light guide with a window in the form of a ground conical tip, however other shapes are possible according to the invention. For example, the window are formed by bending a small diameter light guide through an angle which, in conjunction with the radius of curvature of the window zone, is large enough that a substantial Disturbance of the total internal reflection properties of the light guide results. The window can be chisel-shaped or have some shape of an optical surface at an angle.

It is not necessary that the light from the light source be transmitted to the window via a light guide. It would be possible to use a narrow beam of light that passes through the medium between the source and the window is projected into the base of the window. It will be understood that changes in the transmission medium and outside light that modulates the light in the path to or from the window is prohibited could. In particular, the flow medium must not flow between the source source and the window in such a way that it changes of the light level. A coherent light source can prove to be advantageous for this operating mode. The operation in the invisible part of the spectrum has already been mentioned and could prove to be practical Prove in applications where visible light excludes.

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Claims (17)

Claims .Mixed flow analyzer ;, characterized by a Light system for projecting a light beam onto a window, which is designed and arranged so that changes in the optical Characteristics of the flow behind the window control, effect of the level of light -that bounced back from the window and by detector devices for the level of the reflected light, as well as analyzing devices to display the amplitude of the level changes of the reflected light Light. 2. Analyzer according to claim 1, characterized by analyzing devices to display the frequency of changes in level of the reflected light. = vt α - ■ ·; ■ ■ ■ 3. Analyzer according to one of Claims 1 or 2, characterized in that the light system comprises a light guide. 4. Analyzer according to claim 3> dadUKh indicated that the window is located at one end of the light guide and the detector device at the other end of the light guide. 5 * analyzer according to claim 3 * characterized in that the light guide is U- or V-shaped and the window is in the base of the 'U or at the top of the V and the light detector means is at the other end of the light guide. 6. Analyzer according to one of the preceding claims, characterized characterized in that the window is formed by a bend in the light guide which has a sufficiently sharp curvature has that light can escape from the light guide if this is made possible by the optical properties of the flow behind the window. 9 0 9 8 8 S / 1 flffl J. Analyzer according to one of the. Claims 1 to 5- ,. characterized in that the window is formed by a right circular cone made of transparent material with the plane of its base transverse to the light beam which is projected by the light system. 8. Analyzer according to claim 7, characterized in that the tip angle of the cone is 90 °. ■ zm: ^r 9. Analyzer according to one of claims 1 to 5, characterized * indicated that the window is covered by a cylinder made of transparent The material is geo-formed with its surface perpendicular to the light beam projected by the light system. · 10. Analyzer according to one of the preceding claims', characterized in that the light system is a solid-state lamp which is excited by a pulsating electrical source. 11. Analyzer according to one of the preceding claims, characterized characterized in that the detector device for generating the light is a photosensitive electrical component k includes an electrical signal representative of the The level of the reflected light is, and that the analyzing device has a display device and an arrangement for Processing of the electrical signal for the actuation of the Includes display device. 12. Analyzer according to claim 11, characterized in that that a trigger circuit for processing the electrical signal is provided, which can be actuated by the electrical signal when a threshold level is exceeded. - 19 - 909885/1058 BAD ORfGlNAL 13. Analyzer according to claim 12, characterized in that the trigger circuit output with. an integrator unit for the determination of the mean value of the output over time. 14. Analyzer according to one of the preceding claims, characterized by scanning devices for adjusting the position of the window relative to the flow. 15 · Analyzer according to claims 5, 11, 13 and 7 or 9> characterized in that the transparent material is Safir, that the photosensitive electrical component is a phototransistor and that the integrating unit comprises a capacitor with a parallel resistor which is controlled by the Trigger output is loaded from a constant current generator. . 16. Analyzer according to claims Ί, 10, 13 and 7 or 9> characterized in that the light guide is a solid, that the solid-state lamp is a gall ium arsenide lamp, that the window! In part of the "", ichtleiters formed is that the lamp and the detector device are both arranged at the end of the light guide facing away from the window, and that the integrator consists of a counter for counting the changes in the output of the trigger circuit, corresponding to the changes in the light output of the lamp in response to the Exchange of the same. 17. Analyzer according to one of the preceding claims, formed as a multi-head mixture flow analyzer, characterized in that several windows are arranged in one configuration s "'nd according to the flow conditions which are measured should be, and that the outputs of the detectors so combined and manipulated that a visual display of the Mixture distribution profile and the mixture constituent ratios is achieved on a display device. 909885/1058. BAD ORiGSNAL l8. Analyzer according to Claim IJ, characterized in that the display device is an oscilloscope. 909885/1 058 ORIGINAL BATHROOM