CN101726537B - The apparatus and method of the parameter of particulate/fluid mixture in measuring channel - Google PatentsThe apparatus and method of the parameter of particulate/fluid mixture in measuring channel Download PDF
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- CN101726537B CN101726537B CN200910222489.6A CN200910222489A CN101726537B CN 101726537 B CN101726537 B CN 101726537B CN 200910222489 A CN200910222489 A CN 200910222489A CN 101726537 B CN101726537 B CN 101726537B
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- RTAQQCXQSZGOHL-UHFFFAOYSA-N titanium Chemical compound data:image/svg+xml;base64,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 data:image/svg+xml;base64,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 [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
The divisional application of the application for a patent for invention that the application is the applying date is on April 24th, 2003, to be 03814770.X (international application no PCT/US03/12956) and denomination of invention be application number " measuring the apparatus and method in the fluid flowed in the duct with the parameter of the potpourri of the solia particle of suspension ".
The cross reference of related application
It the application's part is the continuation of the U.S. Patent application No.10/349716 (applicant's document code CC-0579) that on January 23rd, 2003 submits to, the U.S. Provisional Application No.60/351232 (applicant's document code CC-0410) that this application requires on January 23rd, 2002 to submit to, the U.S. Provisional Application No.60/359785 (applicant's document code CC-0403) that on February 26th, 2002 submits to, the U.S. Provisional Application No.60/375847 (applicant's document code CC-0468) that on April 24th, 2002 submits to, the U.S. Provisional Application No.60/425436 (applicant's document code CC-0538) that on November 12nd, 2002 submits to, and the right of priority of the U.S. Provisional Application No.60/426724 (applicant's document code CC-0554) of submission on November 15th, 2002, part is the continuation of the U.S. Patent application No.10/376427 (applicant's document code CC-0596) that on February 26th, 2003 submits to, the right of priority of the U.S. Provisional Application No.60/359785 (applicant's document code CC-0403) that this application requires on February 26th, 2002 to submit to, and be the extendible portion of the U.S. Patent application No.10/349716 (applicant's document code CC-0579) that on January 23rd, 2003 submits to, the U.S. Provisional Application No.60/351232 (applicant's document code CC-0410) that this application requires on January 23rd, 2002 to submit to, the U.S. Provisional Application No.60/359785 (applicant's document code CC-0403) that on February 26th, 2002 submits to, the U.S. Provisional Application No.60/375847 (applicant's document code CC-0468) that on April 24th, 2002 submits to, the U.S. Provisional Application No.60/425436 (applicant's document code CC-0538) that on November 12nd, 2002 submits to, and the right of priority of the U.S. Provisional Application No.60/426724 (applicant's document code CC-0554) of submission on November 15th, 2002, the whole of all these applications are incorporated at this, for reference.
The present invention relates to the device of the stream passed through in a kind of measuring channel, relate more particularly to the isoparametric apparatus and method of particulate/fluid ratio, particle size and volume flow rate that a kind of velocity of sound thus determine utilizing sound dynamic pressure measurement to propagate in stream flows in such as pipeline, described stream has the particulate suspended in the fluid continued.
The invention provides the method for the parameter of the fluid/particle mixture in a kind of measuring channel, the method can use in numerous applications, such as in chemistry, pharmacy, oil and power generation industries.Especially, the invention provides a kind of method of measurement fine coal of using in pulverized fuel transfer system and air mixture, this pulverized fuel transfer system is located at accounting in the coal-burning boiler of vast scale of using in power generation industries.
Current, in the U.S., the coal of the electricity more than 50% produces.Although in the U.S., coal is considered to save cost and rich in natural resources, and mainly for the consideration of protection of the environment, the use of coal is restricted.In order to alleviate this impact, american energy department and electricity power enterprise devise a large amount of plans and carry out development process to reduce coal-fired environmental impact.These Filter Tuber For Clean Coal plans comprise and being designed at decreasing pollution thing, such as coal-fired, ash and oxides of nitrogen (NO x) while improve combustion process with the technology of raising the efficiency.
The ability of the flow velocity in measurement coal pipeline and the composition of air/coal mixtures is any system of performance or importance of strategy of being designed to optimize PF transfer system.Enterprise has recognized this point, and is therefore developing various different technology to perform this measurement always.These technology comprise the detector based on sampling apparatus, and based on the real-time instrument of various different technology (comprise static charge, microwave, and ultrasound wave).
Summary of the invention
Object of the present invention comprises to be provided a kind of and in industrial boiler system and relevant process, such as coal-burning boiler system, measures the velocity of sound propagated by ducted particulate/fluid mixture thus determine the system of the special parameter of this potpourri.
According to the present invention, a kind ofly comprise for the device of at least one parameter of particulate/fluid mixture in measuring channel the space array be made up of at least two pressure transducers, described sensor along piping arrangement on axially different position.The transient pressure of each pressure transducer on corresponding axial location in measuring channel.The described axial location of the corresponding sensor in the sensor of sensor described in each provides the pressure signal of transient pressure in instruction pipeline.Signal processor provides the signal of at least one parameter of potpourri in instruction pipeline in response to described pressure signal.
According to the present invention, in measuring channel, the method for at least one parameter of particulate/fluid mixture is included in along the transient pressure in measuring channel at least two of pipeline predetermined axial measuring positions, thus each position at least two predetermined axial measuring positions provides the pressure signal of transient pressure in instruction pipeline.In addition, described method also comprises at least one parameter utilizing the transient pressure measured on axial measuring position to calculate particulate/fluid mixture in pipeline.
Above-mentioned and other objects, features and advantages of the present invention are according to becoming more apparent to the detailed description of its exemplary embodiment below.
Accompanying drawing explanation
Accompanying drawing 1 be according to of the present invention, for measuring the block scheme of the flowmeter of the velocity of sound of the fluid/particle mixture flowed in the duct.
Accompanying drawing 2 is the schematic diagram according to pulverized fuel (the PF)/air mixture parameter measurement system in coal-burning boiler system of the present invention.
Accompanying drawing 3 is photos of the amplification of the particle size representing the distinctive coal of attached system shown in Figure 2.
Accompanying drawing 4 is according to of the present invention, the velocity of sound of potpourri and the graph of relation of the frequency according to air/coal mass flow ratio.
Accompanying drawing 5 be according to of the present invention, as the real data of the velocity of sound of the function of air/coal mixtures frequency and the curve map of model.
Accompanying drawing 6 represents that basis the present invention is directed to the standard deviation of the velocity of sound and the graph of relation of frequency of the different arrays of PF/ air mixture parameter measurement system.
Accompanying drawing 7 is according to the curve map of the present invention as the velocity of sound of the function of frequency, and this frequency is the frequency of the air/coal mixtures of the air/fuel mass ratio with fixing particle size (50 millimeters) and change.
Accompanying drawing 8 is according to the curve map of the present invention as the velocity of sound of the function of frequency, and this frequency is the vicissitudinous particle size of tool and air/fuel mass ratio equals the frequency of the air/coal mixtures of 1.8.
Accompanying drawing 9 is curve maps of the velocity of sound according to the function as air/coal ratio of the present invention.
Accompanying drawing 10 is for determining the process flow diagram of the optimizing process of air/fuel ratio and particle size from analytical model and the sound velocity data of dispersion determined by test method according to the present invention.
Accompanying drawing 11 is applied to by the curve map of the result of the data of sensor array record by the optimizing process of accompanying drawing 10, and described sensor array monitors that particle size in 6 inches of circular ring pipes is 50 microns, airflow rate is 100 feet per seconds, air/fuel ratio is the stream of 1.8.
Accompanying drawing 12 is curve maps of the result of the data set optimizing process of accompanying drawing 10 being applied to the vicissitudinous air/fuel ratio of a series of tool.
Accompanying drawing 13 is that described pressure transducer is for measuring the velocity of sound of the coal/air mixture flowed in the duct according to the k ω curve map of the present invention by the data of array of pressure sensors process.
Accompanying drawing 14 is that described pressure transducer clips on the outside surface of pipeline according to the side view with multiple pressure transducers of PVDF of the present invention.
Accompanying drawing 15 is fragmentary, perspective views of a pressure transducer of accompanying drawing 14.
With reference to accompanying drawing 1, there is provided a kind of and implement flowmeter 10 of the present invention, multiple parameter/features of the potpourri 12 of this flowmeter survey solia particle, described solia particle is suspended in the continual fluid of flowing in pipeline or conduit 14, wherein, fluid is defined as liquid and/or gas.This flowmeter can be configured to and be designed to measure the velocity of sound propagated by potpourri.This flowmeter can measure at least one in the parameter below mixing logistics 12: fluid/particle concentration (volume phase mark volumetric phase fraction), volume flow rate, the size of solia particle, the mass rate of potpourri, and the speed of potpourri.In order to determine any one of these parameters, the transient pressure that the velocity of sound (SOS) propagated by the potpourri by flowing in pipeline 14 produces measured by flowmeter 10, and this will be described in more detail below.
The solia particle of potpourri 12 can be any size, shape and material.Such as, the size of this particulate may diminish to powder type, particle form, or size is larger.Use in the application of the solia particle that flowmeter 10 can suspend in any fluid be transmitted in by pipeline, such as, use in the application of chemistry, pharmacy, oil and generating.Such as, the present invention is highly suitable for the parameter (such as, air/coal ratio, particle size) measuring electricity generation system, and this electricity generation system uses fine coal to light the stove of steam boiler system.
As an example, the present invention discusses in the context of the pulverized fuel being used for generating electricity (PF) transfer system, but should be appreciated that this flowmeter also can be applied to many other application as described above.Typical PF transfer system 1 has been shown in the coal-burning boiler system 2 of accompanying drawing 2.Coal is pulverized and is carried secretly in atmosphere in flour mill 3, thus by PF/ air mixture being transferred to stove 6 for the pipeline 12 transmitted, and described air produces by multiple device, as fan 4.Typical stove has more than 50 coal pipelines, and the diameter of each coal pipeline is 12-20 inch.Typically, the Large Real boiler being greater than 300Mw can have the flour mill that 4-11 platform supplies to stove.PF transfer system by the fuel of right quantity and air jointly and be sent to the ability of stove separately by these multiple coal pipelines, has very strong impact to the performance of this coal-burning boiler and discharge.
As everyone knows, the unevenness in PF transfer system 1 can cause the change of fuel/air mixture ratio, causes focus, high NO xproduce region and unburned fuel.Contact between the performance must being familiar with PF fuel delivery system 1 and steam generator system 2 fully.Contain flowmeter 10 of the present invention can measure fuel/air mixture ratio and be supplied to the particle size of fine coal of stove, thus provide feedback to operator, to provide the more effective burning of coal.
As mentioned above, flowmeter 10 of the present invention can be configured and is designed to measure and processes the transient pressure P detected 1(t)-P n(t), thus determine the parameter mixing logistics 12, this transient pressure is produced by the sound wave propagated by potpourri.Figure 1 shows such flowmeter 10, the velocity of sound (SOS) of the one dimension sound wave that this flowmeter survey is propagated by fluid/particle mixture, thus determine the ingredients of a mixture, the namely fluid/particulate ratio of potpourri.This flowmeter also can determine the volume flow rate of the average-size of particulate, the speed of potpourri and potpourri.As everyone knows, in such as SONAR and RADAR field, sound is propagated with different speed by different media.The velocity of sound of the potpourri in pipeline 14 can use multiple known technology to determine, the title of such as authorizing on March 12nd, 2002 is the U.S. Patent No. 6354147 of " Fluid ParameterMeasurement in Pipes Using Acoustic Pressures " and the title of submission on November 7 calendar year 2001 is those technology stated in the U.S. Patent application No.10/007749 of " Fluid ParameterMeasurement in Pipes Using Acoustic Pressures ", and these two patented claims are incorporated in this as a reference.The present invention utilizes at least one flowmeter 10 to determine the different parameters of fluid/particle mixture, and wherein, a parameter is the speed that sound is advanced in mixture conduit system, and this speed will be described more fully below.
According to the present invention, by using transient pressure sensor array to monitor stream passively to measure the velocity of sound propagated by potpourri 12, thus determine the one dimension compression wave propagation velocity that the fluid/particle mixture by being included in pipeline 14 is propagated.
As shown in Figure 1, flowmeter 10 comprises at least three sound pressure sensors 15,16, the array of 17, and described sensor is positioned at three position x along pipeline 14 axis 1, x 2, x 3place.Can recognize, as at position x nshown in the pressure transducer 18 at place, this sensor array can comprise more than three pressure transducers.The pressure produced by sound wave by the hole measurement communicated with external pressure sensor 15-18 in pipeline 14, or can pass through other commercial measurement hereinafter described.Pressure transducer 15-18 by circuit 20,21,22, the time dependent pressure signal P on 23 1(t), P 2(t), P 3(t), P nt () is supplied to signal processing unit 30, be then supplied to known fast fourier transform (FFT) logical circuit 26,27,28,29 respectively.This FFT logical circuit 26-29 calculates time-based input signal P 1(t)-P nthe Fourier transform of (t), and at circuit 32,33,34, complex frequency domain (or based on frequency) the signal P of the frequency content representing input signal is provided on 35 1(ω), P 2(ω), P 3(ω), P n(ω).Replace FFT logical circuit, also can use any other for obtaining signal P 1(t)-P nthe technology of the frequency domain character of (t).Such as, cross-spectral density and power spectrum density also can be used to form frequency domain transfer function hereinafter described (or frequency response or ratio).
By frequency signal P 1(ω)-P n(ω) a is delivered to mix-Mx calculation logic circuit 38, this logical circuit 38 will represent the signal a of the velocity of sound propagated by potpourri mix(ω) be provided to circuit 40, described signal is function frequency (discussing more below).By a mix(ω) signal is provided to mapping (or decile) logical circuit 42, and this logical circuit is by a mix(ω) be transformed into the percent composition of PF/ air mixture, and will represent that the %Comp signal of described percent composition (as mentioned below) is provided to circuit 44.Equally, if this Mach number Mx (ω) be can not ignore and be required, this calculation logic circuit 40 also can will represent that the signal Mx (ω) of Mach number Mx (ω) is provided to circuit 46, and this signal Mx (ω) is the function of frequency.
Concerning the ring duct shown in accompanying drawing 1 or pipeline 12, plane wave propagation (list of references Acoustics of Ducts andMufflers is only had lower than during cut-off (cut-on) frequency in frequency, M.J.Munjal, John Wiley & Sons, New York, 1987):
Concerning have in 18 inch conduit 500 meter per seconds the velocity of sound potpourri, this cutoff frequency is approximately 600Hz.Like this, in this example, only one dimension sound wave is propagated at below 600Hz.It should be noted that the very important point, one-dimensional wave still can be propagated on this frequency, but the pattern of the higher order of magnitude may exist or may not exist.
More particularly, concerning the plane one dimension sound wave in homogenous mixts, the known sonic pressure field P (x at the x place, position along pipeline, t) superposition of right lateral afferent echo and left lateral afferent echo can be expressed as, wherein, the wavelength X long (that is, λ/d > > 1) compared with the diameter d of pipeline 12 of sound wave to be measured, described sonic pressure field is expressed as follows:
Wherein, A, B are the complex amplitude based on frequency of right lateral afferent echo and left lateral afferent echo respectively, and x is the pressure measurement positions along pipeline, and ω is frequency (unit: rad/sec, wherein ω=2 π f), and k r, k lbe the wave number of right lateral afferent echo and left lateral afferent echo respectively, they are defined as:
Wherein, a mix(ω) be the velocity of sound of potpourri in pipeline, ω is frequency (unit: rad/sec), and M x(ω) be the axial Mach number mixing logistics in the duct, wherein:
Wherein, V mixit is the axial velocity of potpourri.Concerning non homogenous mixture, this axial Mach number represents the average velocity of potpourri, and low frequency sound field description remains unchanged substantially.
The frequency domain representation P (x, ω) of the time-based sonic pressure field P (x, t) in pipeline is the e of formula 1 i ω tthe coefficient of item, it is expressed as follows:
With reference to accompanying drawing 1, we find, to the pressure measurement positions x in three axial distribution along pipeline 12 1, x 2, x 3p (x, ω) the use formula 4 at place creates a of the function as the tonometric ratio based on frequency mixequation, this equation allows elimination factor A, B.Concerning optimum, A and B is essentially constant in Measuring Time, and in measure portion, there is no that sound (or acoustic energy) is produced or destroys.Acoustically-driven enters part of detecting by means of only the end of inspection part 51, and the acoustic environment outside can dividing independent of check portion like this measures the velocity of sound within measure portion 51.Especially, respectively at three position x along pipeline 12 1, x 2, x 3the frequency domain pressure survey P at place 1(ω), P 2(ω), P 3(ω) be expressed as follows, described frequency domain pressure survey uses the formula 1 being used for right lateral afferent echo and left lateral afferent echo:
Wherein, concerning given frequency, A and B describes sensor 14,16, the arbitrary constant of the sound field between 18.From formula 6, in 7, form P 1(ω)/P 2(ω) ratio, and obtain B/A, it provides expression formula below:
Wherein, R is defined as reflection coefficient.
P is formed from formula 5 and 7 1(ω)/P 3(ω) ratio, and obtain 0, obtain:
Wherein, R=B/A is defined by formula 8, and k rand k lwith a defined by formula 2 mixrelevant.Formula 9 can solve with numerical approach, and such as, by " error " or residual error item being defined as the amplitude on the left of formula 9, and iteration is to minimize this error term.
Data from sensor array can process in any territory, and described territory comprises frequency/spatial domain, time/spatial domain, time/wavenumber domain, or wave number/frequency (k-ω) territory.Similarly, if needed, any known array-processing techniques in these or other relevant territory also can be used in.
Equally, also the function of some or all in signal processing unit 30 can be realized with software (using microprocessor or computing machine) and/or firmware, or simulation and/or digital hardware can be utilized to realize described function, described hardware has sufficient internal memory, interface, and can perform function described here.
Acoustic pressure force snesor 15-18 detects sound pressure signal; measured sound pressure signal is the signal of frequency lower (longer with wavelength) compared with the signal for ultrasonic flowmeter of the prior art; even if therefore protection or coal " viscous " (roping) be impossible place, such as after bend; the present invention also more can tolerate the unevenness in stream, as the viscous in stream and At All Other Times with the unevenness of spatial domain.Term " viscous " is term known to one skilled in the art, and this term represents the bad distribution form of serious room and time, and described bad distribution form causes having the mixing logistics of extensively different component density.Under these conditions, most coal stream is positioned at the region flowed in the side along pipeline 14.
In addition, the present invention determines the effective sound velocity of pipeline/PF/ air mixture system in conjunction with the flexibility of pipeline 14.By multiple discrete source, such as remote machine, flour mill, fan 4 (accompanying drawing 2), valve, bend pipe and PF/ air mixture flow itself, in the PF/ air mixture of pipeline 14, produce sound pressure signal P 1(t)-P n(t).This last source, the PF/ air mixture 12 namely flowed in pipeline 14 ensure the minimum sound level of any PF/ air mixture piping system, and particular advantages of the present invention that Here it is, described PF/ air mixture is common noise source.The sound that flowing produces increases with mean flow rate, and OA overall noise level (sound pressure level) is the function of generation mechanism and humidity mechanism.Similarly, in the present invention, do not need outside discrete noise source, therefore can use passive monitoring to operate.When mixing logistics 12 monitored passively by flowmeter 10, the present invention attempts to increase sound source to be injected in stream to be measured by required sound wave by such as compressing, vibrating and/or beat the methods such as pipeline.
Concerning hereinafter by the pressure transducer of particular type, such as pipeline strain sensor, accelerometer, speed pickup or the displacement transducer discussed, pipeline 14 may be needed to show the pipeline flexibility of specified quantitative.
Selectively, in order to minimize any error effects (and needs of respective alignment) caused by pipeline flexibility, the axis inspection part 50 of pipeline 14 can be made hard as much as possible, and wherein, sensor 15-18 locates along this axis inspection part 50.In order to obtain required hardness, the thickness of the wall of inspection part 50 can be made to have predetermined thickness, or this inspection part 50 can be made up of stone material, described material is such as steel, titanium, pottery, or other has the material of high mode.
Length (aperture) the Δ X of pressure transducer (15-18) array is at least one live part of the measurement wavelength of just measured sound wave.As will be described in more detail, wave length of sound to be measured is at least the function of the dispersing characteristic of potpourri 12, and wherein, this dispersing characteristic is at least the size of particulate and the function of quality and fluid viscosity.The dispersion of potpourri is larger (such as size and quality are larger and/or fluid viscosity is less), and the length of required array is longer.On the contrary, the dispersion of potpourri is less (such as size and quality are less and/or fluid viscosity is larger), and the length of required array is shorter.
In addition, within the scope of the invention, if the position of sensor is known, then the spacing of pressure transducer can be known or arbitrary.As will be hereinafter described in more detail, sensor 15-18 also can place (as shown in Figure 1) equally spacedly, or the placement of any uneven or unequal-interval.Will be appreciated that, if known about the customizing messages of the sound characteristics of PF/ air mixture piping system, then only need few to two sensors.
As noted, the velocity of sound of the one dimension sound wave propagated by fluid/particle mixture measured by flowmeter 10, thus determines the ingredients of a mixture.Especially, the velocity of sound propagated by the solid/air mixture of dilution can be directly relevant to the mass fraction of the particulate of flowing.Typical PF fuel delivery system 1 can with the ratio work of air/coal of 1.5 to 2.5, wherein with the 1.2kg/m under normal atmospheric environment 3air is compared, and coal density is 1200 to 1400kg/m 3.Like this, meet required mass ratio and can cause coal mixtures very rare on volume basis, this is similar to the order of magnitude of 1/1000 of volume.
Suppose that coal particulate is enough little, and audio frequency and the interfering frequency relevant with sound enough little, so that solia particle shows insignificant slip (stable with instability), can assumed speed of sound be then nondispersive (namely frequency is constant), and the volume phase mark of Wood equation determination potpourri can be passed through:
(in this case, the modulus of ring pipe is E, and radius is R, and pipe thickness is t) to comprise the flexibility effect introduced by conduit 12
Utilize above-mentioned relation, attachedly Figure 4 shows that sound is having the speed of advancing in the piping system of the typical coal/air mixture function as air/coal mass ratio.Concerning this example, suppose that pure air has the density of 1.2kg/m^3 and the velocity of sound of 365.9m/s, and suppose that coal has the density of 1400kg/m^3 and the velocity of sound of 2439m/s.As shown in the figure, increase coal proportion, namely reduce the result of air/coal ratio and be reduction of the velocity of sound.Physically, effectively increase the quality that coal particulate is loaded with potpourri, and the compressibility of air can not be changed completely.In interested parameter area, the relation between the potpourri velocity of sound and air/coal ratio is showed well, and is monoatomic.
When the calibration curve predicted based on First Principle is inspirer, use the empirical data being mapped to air/coal ratio from the velocity of sound can improve the accuracy that the present invention measures the air/coal proportion of potpourri.
But, have been found that, the physical property of the coal/air mixture of powdery is generally: (be rated for the coal particulate of 50 μm in for air except very low frequency, be similar to frequency < 1-2Hz) outside all frequencies on all exist speed slide, this situation as shown in FIG. 7 and 8, and will be described in more detail below.
Accompanying drawing 5 represents the function of the measured velocity of sound as the frequency of the coal/air mixture 12 of reality.This velocity of sound utilizes passive monitoring technique of the present invention described here to measure.By the multiple narrow frequency scope between 50-300Hz applies Capon array process algorithms, determine the frequency dependence of this velocity of sound, thus determine the frequency of specific acoustic propagation velocity.In this specific example, these data obtain when coal/air mixture is to be nominally 100ft/sec flowing, and wherein, air/coal mass ratio equals 1.8.This coal particulate nominal size is 50 μm, represents the typical fine coal used in generating and other commercial Application.Figure 3 illustrates the view of the amplification of the coal particulate for this inspection.
In addition, as shown in Figure 5, the velocity of sound increases along with the frequency increased, and with asymptotic line close to steady state value.In the airborne velocity of sound that the velocity of sound asymptotic line of upper frequency is by means of only not having the particles interfere suspended substantially.Equally, significantly, the velocity of sound of coal/air mixture does not reach the quasi-steady boundary of the low-limit frequency measuring the velocity of sound.This velocity of sound continues to reduce by lower frequency limit.Great discovery of the present invention is, the velocity of sound propagated by the dilution particulate suspended in the fluid continued is dispersion.As defined in this, the speed that sound wave is propagated by the potpourri of dispersion changes with frequency.
Due to total length (the Δ x of pressure transducer 15-18 array aperature) diminish compared with the wavelength of sound, thus measure the degree of accuracy step-down inherently of the velocity of sound of potpourri 12 when frequency is more and more lower gradually, described total length (Δ x aperature) limit the aperture of this array.Usually, this aperture at least should be the live part of the wavelength of the velocity of sound interested.In specific embodiment, when total aperture is 3 feet, be the An arrayed recording sound velocity data of four sensors of 12 inches by spacing.When 50Hz, the sound wave of 100ft/sec has the wavelength of 20ft.Like this, 3/20 of wavelength is only crossed in the aperture (about 36 inches) of this specific array, and slackens the ability that this array accurately differentiates the velocity of sound under described aperture significantly.Importance of the present invention is, the ability differentiating the velocity of sound when low frequency is directly relevant with the aperture of this array.Therefore, longer array is used for differentiate in more low-frequency velocity of sound.As shown in Figure 6, the standard deviation relevant with the velocity of sound determined in air is expressed as the function of the frequency of three arrays with different pore size, i.e. 1.5ft, 3ft and 10ft.
The physical constraints of the velocity of sound is accurately measured when specifying in ultra-low frequency, these data propose, utilize quasi-steady model explanation may be problematic higher than the relation can applied between the velocity of sound measured in the frequency of those frequencies of quasi-steady model and air/fuel ratio, and in fact may be unpractical.Like this, understood by acoustic velocity measutement and explain that the key of the composition of coal/air mixture is the dispersing characteristic of this coal/air mixture.
According to the present invention, the dispersing characteristic of this system utilizes the interactional First Principle model between air and particulate.This model is regarded as the representative seeking the model I that dispersion effect is described.When not changing the object of present disclosure, also can by other model for illustration of dispersion effect (such as, see by R.L.Gibson, Jr. and M.N. the title shown is the article of " Viscous Attenuation of Acoustic Waves in Suspensions "), be incorporated in this as a reference.This model allows the slip between the local velocity of continual fluid phase place and the local velocity of particulate.Carry out modeling by the power proportional with the difference of local fluid velocities and fluid fine particle speed to the pulling force be applied to by continual fluid on particulate, described pulling force is by balance of shaking force:
Wherein, K=proportionality constant, U f=fluid velocity, U p=particle speed, ρ p=density of particle, and v p=particulate volume.
The effect of the acting force of fluid fine particle in continual fluid phase place is modeled as the power item of axial momentum equation.The axial momentum equation of the control volume sum length Δ x of region A is provided by following formula:
Wherein, P=at the pressure at position x and Δ x place, φ pthe volume fraction of=particulate, ρ f=fluid density.
This particulate pulling force is provided by following formula:
Wherein, C d=tension coefficient, A pthe front face area of=particulate, and ρ f=fluid density.
Use stoke (Stokes) law for the sphere upper pulling force when low Reynolds (Reynold) counts, produce following tension coefficient:
Wherein, D p=mean particle dia, and μ=fluid viscosity.
In this model, solve K, produce:
Use relation of plane and 1 dimension Acoustic Modeling technology, can the lower relation of plane of dispersing characteristic of derived ideal fluid fine particle potpourri.
In superincumbent relation, fluid SOS, density (ρ) and viscosity (φ) are all pure phase bit stream bodies, v pthe volume of single particulate, and φ pit is the volume phase mark of particulate in potpourri.
In fine coal is measured, primarily interested two parameters are particle size and air/fuel mass ratio.For this reason, interested is the dispersing characteristic of inspection as the potpourri of the function of this Two Variables.Accompanying drawing 7 and 8 represents the dispersing characteristic of coal/air mixture, and its parameter is the parameter that those often use in fine coal transfer system.
Especially, accompanying drawing 7 represent for certain limit air/fuel ratio there is in air the prediction characteristic of the coal of 50 Am nominal sizes.As shown in the figure, the impact of air/fuel ratio is limited fully in low frequency boundary.But in higher frequency, the impact of air/fuel ratio becomes and is difficult to differentiate, and when high frequency (higher than ~ 100Hz) close to the velocity of sound in pure air.
Similarly, accompanying drawing 8 represents the prediction characteristic with the air/fuel ratio of 1.8 and the coal/air mixture of different particle size.This accompanying drawing represents, particle size does not all affect the low frequency boundary (quasi-steady) of the velocity of sound or the high frequency boundary of the velocity of sound.But particle size has significant impact in zone of transition.
Accompanying drawing 7 and 8 represents importance of the present invention.In other words, the dispersion property of the dilution mixture thing of the particulate suspended in continual fluid can be divided into three frequency ranges roughly: low-frequency range, high-frequency range, and transition frequency range.Preferably as shown in Figure 8, in low-frequency range, the velocity of sound propagated by potpourri is identical substantially, and has nothing to do with particle size.In low-frequency range, this potpourri shows quasi-steady model, or fricton-tight (non-dispersive) characteristic.As shown in intermediate frequency range, the velocity of sound propagated by potpourri depends on the size of particulate, and therefore shows dispersing characteristic.Concerning high-frequency range, the velocity of sound propagated by potpourri is not by the impact of particulate.In other words, the velocity of sound propagated within the scope of higher-frequency by potpourri is substantially equal to the velocity of sound propagated by fluid, and wherein particulate can not have an impact, and this will be described in more detail below.
Be aware of the dispersion effect of the velocity of sound as described above by potpourri, will be appreciated that, preferably as shown in Figure 7, in order to determine the concentration of potpourri (such as, air/fuel ratio), tested sound wave frequency should in low-frequency range, and this low-frequency range shows small slip or fricton-tight (non-dispersive/quasi-stationary state).In addition, will be appreciated that, as shown in Figure 8, in order to determine the particle size in potpourri 12, tested sound wave frequency should be positioned at intermediate frequency range, and this intermediate frequency range shows dispersing characteristic.
Although the impact of particle size and the impact of air/fuel ratio interrelated, the major effect of air-fuel ratio is the low frequency boundary determining the velocity of sound to be measured, and the major effect of particle size is the frequency range determining zone of transition.Along with particle size increases, occur that the frequency of dispersion property reduces.Concerning typical fine coal application, this zone of transition starts at quite low frequency place, is ~ 2Hz for the particulate being of a size of 50 microns.
In low-frequency range, this particulate reveals inappreciable slip relative to fluid meter.Fricton-tight, quasi-steady is similar to the function that effective frequency range is multiple parameter, and this parameter comprises particle size, continues phase place viscosity, particulate form, and density of particle.
Provided the velocity of sound of this quasi-steady (fricton-tight condition) by the low frequency boundary of relation above, wherein, AFR is air/fuel ratio:
It should be noted that particle size does not affect the low frequency boundary of the velocity of sound.With reference to accompanying drawing 9, for the air/coal mass ratio of certain limit, utilize embodiments of the present invention to measure the velocity of sound, this embodiment has and is spaced apart 20.5 inches, 8 sensors of average 20-40Hz.Indicate the velocity of sound of the coal/air mixture using quasi-steady model prediction simultaneously.As shown in the figure, although capture trend substantially, namely the velocity of sound reduces with the growth of coal loading amount, and error is also very significant, makes the First Principle based on quasi-steady model explain abundant not.
In high frequency boundary, dispersion relation predicts towards the asymptotic velocity of sound of pure fluid sound speed.
Enjoyably, this high frequency boundary is independent of particle size and air-fuel ratio.
The fully low frequency of known measurement is to apply quasi-steady model and to recognize that the high frequency velocity of sound does not comprise the difficulty of the direct information about particle size or air/fuel ratio, obviously, the dispersing characteristic of coal/air mixture should be utilized determine the particle size based on acoustic velocity measutement and air/fuel ratio.
As mentioned above, flowmeter 10 of the present invention comprises the average particle size of the coal accurately determined in pipeline 14 in PF/ air mixture and the ability of air/fuel ratio.If significantly do not slide between air and solid coal particulate, then by the one dimension sound wave propagation of the multiphase mixture impact by the effective mass and effective compressibility that are subject to potpourri.Concerning air delivery system, the degree of fricton-tight hypothesis application is the majorant of particle size and frequency.In small particle and low-frequency boundary, this fricton-tight hypothesis is effective.Along with the size of particulate increases, and the frequency gets higher of sound wave, this fricton-tight hypothesis little by little becomes invalid.Concerning given average coal particle size, the slip increased with frequency gets higher causes dispersion, or in other words, the velocity of sound of potpourri changes with frequency change.By suitably calibrating, the dispersing characteristic of potpourri will provide the measurement of average particle size, and the measurement of the air/fuel ratio of potpourri (particulate/fluid ratio).
Utilize the equational above-mentioned model shown in below producing, and the velocity of sound of the function as frequency experimentally determined, the present invention includes the optimizing process simultaneously determining particle size in coal/air mixture and AFR:
With reference to accompanying drawing 10, illustrate according to optimizing process of the present invention, wherein, the free parameter of optimizing and analyzing model minimizes to make error function.For illustrative purposes, the error function utilized be velocity of sound difference between analytical model and the velocity of sound of the function as frequency experimentally determined and:
Accompanying drawing 11 represents the result after data optimizing process being applied to sensor array record, and this sensor monitors that particle size in 6 inches of ring pipes is 50 microns, airflow rate is 100ft/sec, air/fuel ratio is the stream of 1.8.Show the velocity of sound that is measured and that predict with Optimized model.As shown in the figure, this model captures transition frequency range preferably, and provides the good assessment of air/fuel ratio.
Accompanying drawing 12 represents the result of data group optimizing process being applied to the vicissitudinous air/fuel ratio of a series of tool.For this optimization, it should be noted that particle size is retained as constant in the scope of this data group.
As mentioned above, the length of this array of pressure sensors should be at least the live part of the wavelength of the interested velocity of sound.The live part of this wavelength can be at least 30% of this wavelength, but this part also can be less than 30%, and this depends on required measuring accuracy, measured wavelength, and/or sound wave intensity (such as, low signal-to-noise ratio).Therefore, the length of this array depends on the frequency (frequency and wavelength are inversely proportional to) of the interested velocity of sound, wherein, the frequency of the interested velocity of sound depends on measurement (such as, air/particulate ratio and particle size) undetermined and the dispersing characteristic of potpourri.Such as, as shown in Figure 7, due to the growth of potpourri dispersion, the low-frequency range measuring the velocity of sound (quasi-stationary state) curve of mixture concentration (as air/particulate ratio) is lower.As previously mentioned, the dispersing characteristic of this potpourri depends on many factors, and one of them is particle size.When particle size becomes large, this dispersion becomes large, and when particle size reduces, this dispersion step-down.Therefore, the length of array is the function of particle size in potpourri, and therefore, preferably as shown in Figure 8, along with particle size increases, transition point (low-frequency cutoff) frequency between low-frequency range and intermediate frequency reduces.
Such as, when measuring the concentration of potpourri, along with the size of particulate increases, low-frequency cutoff reduces, and therefore interested wave length of sound increases, thus needs the length of this array to become longer.On the contrary, along with the size of particulate reduces, low-frequency cutoff increases, and therefore the wavelength of interested sound wave reduces, thus needs the length of this array to become shorter.Briefly, particulate is larger, and array is longer, and vice versa.When determining the size of particulate in potpourri, identical is more also correct.But, the optimum performance of flow meter, measurement due to concentration is positioned at frequency (longer wavelength) place lower than the intermediate frequency (shorter wavelength) of particle size, and thus the measurement of mixture concentration may need the array more grown compared with the measurement of particle size.
The actual low-limit frequency scope surveyed is approximately 10-25Hz, and thus perhaps the measurement of large particulate can not measure quasi-steady model, and described quasi-steady model can be less than 10Hz (that is, cutoff frequency is less than 10Hz) in some cases.In these cases, interested velocity of sound frequency is positioned on this cutoff frequency.But as shown in Figure 10, by changing size and the ingredients of a mixture of particulate, make the disperal pattern curve of the measured velocity of sound and potpourri, thus determine the concentration of particle size and/or potpourri, this will be described in more detail below.
When the length of array depends on particle size, this length also can depend on other parameter limiting dispersion amount, the quality of such as particulate, and the viscosity of potpourri inner fluid.
The factor of the length of another restriction (or impact) pressure transducer 15-18 array comprises the signal intensity of the sound wave received by processor.When signal intensity improves or be larger, the length of this array must be shorter.This signal intensity depends on multiple factor, as the intensity of sound wave itself, and the signal to noise ratio (S/N ratio) of sensor, coupling of sensor etc.
As shown in Figure 1, this spacing can be equally spaced, but flowmeter of the present invention 10 considers that this sensor can have not grade or uneven spacing.If the position of sensor or orientation known, then this sensor can with any required distance interval.For the pressure transducer communicated, minimum spacing is limited by the mechanical constraint of sensor.Concerning based on the sensor strained, the PVDF such as described hereinafter band, the flexibility of pipeline limits the closeness at this interval.Such as, pipeline is harder, and the spacing of sensor must be larger, and on the contrary, pipeline flexibility is larger, and the necessary interval of sensor is nearer.
The spacing of this pressure transducer also can be limited by the quantity of the sensor be arranged in the array of given length.The sensor arranged in the array of given length is more, then this spacing is nearer.The quantity being arranged in the sensor in array depends on degree of accuracy that is required or that want the flowmeter 10 obtained.The quantity of array inner sensor is more, then can obtain measuring more accurately of sonic pressure field.In other words, in given array length (or wavelength), the sampling of the acoustic pressure wave provided or the quantity of measurement more, the resolution that sensor can realize in the measurement of the sound wave of to be measured or characterization is larger.
Fluid/the particulate carrying out the potpourri 12 in measuring channel 14 except using the velocity of sound that records than and particle size except, flowmeter 10 comprises further to be broadcast and one dimension sound wave measures the ability of volume of mixture flow rate against on average spreading the speed difference broadcast along with on average spreading by comparing one dimension sound wave.
This determines that the method for the volume flow rate of particulate/fluid mixture 12 in pipeline 14 depends on this and on average flows the interaction with sonic pressure field.This interaction causes adding convection velocity with the velocity of sound (supposing that this particulate/fluid mixture does not flow) advance along with on average spreading the sound wave broadcast, and on the contrary, against on average popular enter sound wave subtract convection velocity with the velocity of sound and propagate.That is,
a R＝a mix+u
a L＝a mix-u
Wherein, a r=sound the wave propagation velocity of advancing to the right relative to fixing observer's (i.e. pipeline 14), a l=sound the wave propagation velocity of advancing left relative to fixing observer, a mix=fluid sound speed (if fluid does not flow), and u=mean flow rate (in this case, supposing to flow from left to right).These two equations are combined the equation producing average velocity,
Therefore, as previously mentioned, by relative to measurement sound velocity of wave propagation in the both direction of fixed-piping, this mean flow rate can be calculated by being multiplied with the area of section of pipeline 14 by mean flow rate.
This practicality on average flowed is based on fully accurately differentiating the velocity of sound to determine the ability of volume flow in the two directions to utilize this method to determine.Concerning typical fluid measurement, flow velocity typically is ~ 10ft/sec, and the velocity of sound is ~ 4000ft/sec.Like this, axial Mach number is approximately 0.0025 10/4000.Concerning the accuracy of the +/-10% of flow velocity (+/-1ft/sec), inverse trip and the resolution of the velocity of sound of ripple propagated along trip need for +/-1/0.5/4000th or 8000.
But for PF/ air mixture flow, axial flow velocity is nominally about 70ft/sec, and not there is ~ stream the velocity of sound of 700ft/sec.Which results in ~ the Mach number of 0.1, this Mach number is approx than large two orders of magnitude of typical fluid flowing.Concerning pulverized fuel stream, in order to flow velocity being differentiated to the degree of accuracy (or +/-7ft/sec) of 10%, have to the velocity of sound to differentiate +/-3.5ft/sec, or 3.5/700, or 1/200th.
Concerning acoustic velocity measutement, flowmeter 10 utilizes the Processing Algorithm similar to those used algorithms above.The Time and place frequency content of the sound propagated in process pipeline 14 is relevant with dispersion relation.
Wave number is k, and this wave number is defined as k=2 π/λ, and ω is temporal frequency, and unit is radian per second (rad/sec), and a mixfor the speed that sound is propagated in process pipeline.For this situation that sound is propagated in the two directions, acoustical power swells (ridges) location along two sound, and one in described sound protuberance is with a mix+ V mixthe speed sound of advancing together with stream, and another is with a mix-V mixspeed against popular enter sound.
K-w curve shown in accompanying drawing 13 expresses support for the ultimate principle of the flow measurement based on sonar, namely, can be combined axle pressure sensor array and sonar treatment technology to determine speed, naturally with this speed generation turbulent eddy convection current in pipeline.Accompanying drawing 13 represents the k-w curve that the sound field flowing through the coal/air mixture of pipeline produces.Two sound protuberances clearly.Each gradient of shown two sound protuberance limit respectively accordingly along with on average popular enter and the velocity of sound of carrying out against average stream.Employ parameter optimization method to determine " best " line representing this sound protuberance gradient.
In addition, accompanying drawing 13 represents that the present invention determines the ability of the fluid velocity of movement in the duct.Accompanying drawing 14 represents the wave number-frequency curve (k-w curve) of transient pressure.This profile represents the relative signal power in all combinations of frequency and wave number.The highest power " protuberance " represents sound wave by the protuberance gradient equal with velocity of propagation.Dotted line represents the maximization of the Two Variables of the best-fit of power, and described Two Variables is the velocity of sound and flow velocity.Right side protuberance represents the sound wave of advancing in the same way with bulk flow, and thus its gradient is more precipitous than left side protuberance, and described left side protuberance represents the sound wave be reversed with bulk flow.This means, relative to the fixation of sensor be positioned on pipeline, the sound wave of the acoustic ratio of advancing in the same way with bulk flow and bulk flow negative line feed is advanced faster.
Pressure transducer 15-18 described here can be the pressure transducer of any type, such as piezo-electric pressure sensor, optical pressure sensor, capacitance pressure transducer, resistive pressure sensor (such as Wheatstone bridge), accelerometer (or seismoreceiver), velocity measuring device, displacement measuring devices etc., described pressure transducer can instability in measuring channel 14 (or exchange or dynamically) pressure.If use optical pressure sensor, then sensor 15-18 can be the pressure transducer based on Prague (Brgg) grating, such as, at the pressure transducer of title described in the U.S. Patent application No.08/925598 of " High Sensitivity Fiber Optic Pressure SensorFor Use In Harsh Environments ", namely present United States Patent (USP) 6016702 that on September 8th, 1997 submits to.Selectively, sensor 14 can be the strainometer of electricity or optics, and described strainometer is attached to or embeds outer wall or the inwall of pipeline, and measure the strain of tube wall, described sensor comprises microphone, nautical receiving set, or other any can the sensor of transient pressure in measuring channel 14.In an embodiment of the invention, use optical fiber as pressure transducer 14, described optical fiber can connect individually, or Wave division multiplexing (WDM), time division multiplexing (TDM) or other any optically multiplexed technology can be used multiplexing along one or more fiber optic.
Concerning any embodiment described here, pressure transducer can be attached to ensure contact suitable between sensor and pipeline 14 on pipeline by bonding agent, glue, epoxy resin, adhesive tape or other suitable setting tool, and described pressure transducer comprises electrical strain gauge described here, optical fiber and/or grating.Selectively, this sensor removably or for good and all can be adhered to by the technology of known mechanical technique, such as machanical fastener, loading spring, clamp, clamp housing equipment, strapping or other equivalence.Selectively, this strainometer can be embedded in complex pipe, and described strainometer comprises optical fiber and/or grating.If needed, for some applications, if needed, this grating can be separated with pipeline 14 (or strain or sound is isolated).
Within the scope of the invention, the change strained in the strain induction technology measuring channel that other also can be used any, as highly sensitive piezoelectricity, electronics or electric strainometer, described strainometer is attached to or is embedded in pipeline 14.
In some embodiments of the present invention, can use one or more as in pressure transducer 15-18 of piezoelectron pressure transducer, described piezoelectron pressure transducer can carry out instability in measuring channel 14 (or dynamically or exchange) pressure change by the pressure stage in measuring channel.In an embodiment of the invention, this sensor 14 comprises the pressure transducer manufactured by PCBPiezotronics.In a pressure transducer, have the sensor of integrated circuit piezoelectric voltage mode type, this sensor characteristics is embedded microelectronic amplifier, and high impedance electric charge is transformed into low-impedance voltage output.Especially, use and manufacture Model 106B by PCBPiezotronics, this device is integrated circuit piezoelectric quartz pressure sensor that is highly sensitive, acceleration compensation, is suitable for measuring low pressure voice phenomenon in hydraulic system and pneumatic system.Under high static condition, it has the unique ability measuring the little pressure change being less than 0.001psi.106B has the sensitivity of 300mV/psi, and the resolution of 91dB (0.0001psi).
This pressure transducer comprises the MOSFET microelectronic amplifier of embedding, thus the output of high impedance electric charge is transformed into voltage signal in low impedance.This sensor obtains power from constant current source, and coaxially or on flat cable can operate in length, and does not have signal attenuation.Voltage signal in low impedance is not by the cable noise of friction electricity or the impact of insulation resistance degradation of contaminant.The power supply operating integrated circuit piezoelectric sensors usually take low cost, 24 to 27VDC, the constant current source form of 2 to 20 milliamperes.Data acquisition system (DAS) of the present invention can be incorporated to constant current source, to provide power supply directly to integrated circuit piezoelectric sensor.
Most piezo-electric pressure sensor is made up of the compact model quartz crystal be preloaded in stiff case or unconfined tourmaline crystal.These are designed to the resonant frequency that sensor provides microsecond response time and hundreds of KHz, and have minimum overshoot or ring.Small vibration film diameter ensure that the spatial resolution of narrow shock wave.
The output characteristics of piezoelectric pressure sensor systems i.e. the output characteristics of AC coupling system, wherein, the signal attenuation of repetition, until on original baseline and below there is equal region.Because the order of magnitude of monitored event can fluctuate, so output signal keeps stable around baseline, and the positive negative region of curve keeps equal.
And as shown in figure 14, the present invention imagines, and flowmeter 10, each in the pressure transducer 15-18 of 70 comprises piezoelectric sensor 104-107, and described piezoelectric sensor provides piezoelectric 110 to measure the transient pressure of fluid/particle mixture 12.The strain of inducting in process pipeline 14 measured by the fluoropolymer, polyvinylidene fluoride (PVDF) etc. of this piezoelectric, such as polymkeric substance, polarization, and described strain is owing to the change of transient pressure in process potpourri 12.Strain in pipeline is transformed into output voltage or electric current by the piezoelectric sensor 104-107 of attachment.
Preferably as shown in figure 15, PVDF material 110 is attached to the outside surface of steel band 112, and described steel band extends around the outside surface of pipeline 14, and clips on described outside surface.The conformal typically of this piezoelectricity sensing element, thus allow measuring completely or close to circumference completely of the strain of inducting.This sensor can be made up of PVDF thin film, interpolymer film or flexible PZT sensor, and be similar to by Measurement Specialties, Inc. provide the sensor described in " Piezo FilmSensors technical Manual ", this sensor merges as a reference at this.The advantage of this technology is as follows:
1. non-invasive flow is measured
2. low cost
3. measuring technique does not need driving source.Ambient flow moving noise is used as source.
4. in various configurations mode, flexible piezoelectric sensor can be installed, thus strengthen input scheme.These configuration modes comprise the sensor of a) colocated, b) there is the segmenting sensor of opposite polarity configuration, c) wide sensor, thus strengthen the detection of acoustical signal, and minimize the detection of vortex noise, sensor geometry d) customized, thus minimize the sensitivity to pipeline model, e) difference of sensor, thus from vortex signal stress release treatment.
5. higher temperature (140C) (interpolymer)
Although present invention illustrates that array of pressure sensors comprises multiple similar sensor, the present invention imagines, and also can use any combination of different or similar pressure transducer in array.
Although the present invention can measure the solia particle suspended in a fluid, will be appreciated that, sensor array also can be used to measure other leggy potpourri or stream, as steam flow.Should recognize further, in convection cell, the impact of the dispersion of large solia particle is similar to the large drop of the liquid disperseed in gas or air, therefore when measuring quality of steam and drop size, should solve similar consideration.
Should be appreciated that and also can apply, use about any feature described by particular implementation, characteristic, alternatives or amendment, or be merged in other embodiment any described here.
Although describe examples according to exemplary embodiment to describe the present invention, without departing from the spirit and scope of the present invention, also can form aforesaid and multiple other interpolation and omission.
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|US10/349,716 US7359803B2 (en)||2002-01-23||2003-01-23||Apparatus and method for measuring parameters of a mixture having solid particles suspended in a fluid flowing in a pipe|
|US10/376,427 US7032432B2 (en)||2002-01-23||2003-02-26||Apparatus and method for measuring parameters of a mixture having liquid droplets suspended in a vapor flowing in a pipe|
|CN 03814770 CN1708674A (en)||2002-04-24||2003-04-24||Apparatus and method for measuring parameters of a mixture having solid particles suspended in a fluid flowing in a pipe|
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|CN103336050A (en) *||2013-06-06||2013-10-02||重庆大学||Coal-bed gas seepage experimental device under action of controllable high-power sound wave|
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