CN101477074A - Two-phase flow parameter monitoring method and system - Google Patents

Two-phase flow parameter monitoring method and system Download PDF

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Publication number
CN101477074A
CN101477074A CNA2008101726180A CN200810172618A CN101477074A CN 101477074 A CN101477074 A CN 101477074A CN A2008101726180 A CNA2008101726180 A CN A2008101726180A CN 200810172618 A CN200810172618 A CN 200810172618A CN 101477074 A CN101477074 A CN 101477074A
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phase
phase flow
dielectric
flow
pipe
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王玉涛
陆增喜
杨钢
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Northeastern University China
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Northeastern University China
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Priority claimed from KR1020090107161A external-priority patent/KR101224362B1/en
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Abstract

The invention discloses a method and a system for monitoring flow parameters of two-phase flow. According to the invention, a two-phase flow pipeline to be monitored comprises at least one dielectric material pipe formed by dielectric material; at least one pair of electrode plates is twisted into a spiral shape in the same way along the longitudinal direction on the outer surface of the dielectric material pipe; on the outer surface of the dielectric material pipe, an upstream position and a downstream position on one side of the at least one pair of electrode plates are provided with identical capacitance sensors in the same way; when the two-phase flow flows through the dielectric material pipe, capacitance induced on the at least one pair of electrode plates and random time sequence signals induced on an upstream capacitance sensor and a downstream capacitance sensor respectively are detected; and the volume concentration of a working-medium phase in the two-phase flow and the flow velocity of the two-phase flow are calculated according to the detected signals, and then the mass flow rate of the working-medium phase in the two-phase flow can be figured out.

Description

Two-phase flow parameter monitoring method and system
Technical field
The present invention relates to monitoring, especially to the monitoring of Dual-Phrase Distribution of Gas olid flow parameter to two-phase flow parameter.
Background technology
Two-phase flows such as Dual-Phrase Distribution of Gas olid are widely used in the industrial practices such as electric power, metallurgy, pharmacy.For example, in electric power and field of metallurgy, coal dust is carried by strength, is exactly the Dual-Phrase Distribution of Gas olid of a quasi-representative.Therefore this Pneumatic Conveying Technology can improve burning efficiency, improves production environment, reduce labor intensity, and helps to solve problems such as the coal-fired energy dissipation that becomes increasingly conspicuous and ecological deterioration.
In power industry, the reasonable distribution of Coal-fired capacity and combustion air is one of pacing items of large-sized boiler optimized combustion.For coal-burning boiler, the broken after wind-force of coal dust is carried and is evenly distributed in a plurality of burners by divider.If owing to the inconsistent coal-air ratio that can influence burner of pulverized coal flow in the pipeline, cause combustion rate to descend between each burner, increase unburned carbon level and high NO xDischarge capacity.Prolong after catching fire when serious, unstable combustion, cause boiler booster and burner to damage distortion, one time airduct stops up and firing accident.In addition, when coal powder density is higher, the combustion melting temperature of ash is reduced, and then cause local slagging scorification.
In metallurgical industry, pulverized coal injection in blast furnace is the great technical measures that reduce cost in the iron-smelting process, improve the quality of products.To the blast furnace pulverized coal conveying, coal dust is carried by a wind blast-furnace coal powder injection by blast-furnace tuyere winding-up arm, enters the burner hearth burning through coal powder injection air port arm, thereby coal powder density and speed have a significant impact the burning of blast furnace between each coal pipe.If the pulverized coal mass flow in each coal powder injection air port arm is inconsistent, then burning can not finely be organized, and causes eccentricity of fire, coking, unstable combustion etc. easily.If the air port arm stops up, may cause coal dust to overflow the air port, burn out the air port, coal dust burns in bustle pipe, cause local overheating and pipeline breaking, the damage hot blast is responsible for, even causes that coal dust blasts in warm-air pipe, stops up as long-time, can cause the long-time damping down of blast furnace, influence safety in production and furnace condition anterograde.
Therefore, must monitor,, perhaps accident be reported to the police with the flow state of Dual-Phrase Distribution of Gas olid in the monitoring pipeline to the coal dust-air Two-phase flow parameter that flows in the pipeline.
Yet there are reasons such as CONCENTRATION DISTRIBUTION inequality, flow pattern complexity in Dual-Phrase Distribution of Gas olid, and the solid phase parameter measurement is a universally acknowledged difficult problem, also is that electric power and metallurgy industry are badly in need of and are failed the difficult problem of fine solution always.
At present, the detection method to coal dust-air flow condition has two big classes, the one, contact method.This method is the monitoring that realizes the flow field in the pipeline by sensor directly is seated in.But contact method tends to influence the flow field, not only can not get real flow state, and may become the reason of fault.Sensor also is a shortcoming of contact method owing to directly be subjected to the easy damage of washing away of fluid.The 2nd, non-contact method.The noncontact method mainly contains temperature differential method and optical detection.The temperature that temperature difference ratio juris is based on blast furnace blowing system coal dust is higher than environment temperature, also is higher than the actual condition of dry and cold dehydration back compressed air temperature simultaneously, carries out status monitoring according to the difference variation before and after the fault.This method has certain applicability for each coal spraying pipeline of the blast furnace under enclosed environment.But,,, cause the temperature difference judgment rule of monitoring system to be difficult to conclude owing to season, wind direction, daylight, environment temperature influence difference for the coal spraying pipeline of diverse location for the coal spraying pipeline under the outdoor environment.Even under enclosed environment, temperature difference judgment rule also is difficult to determine.Optical detection adopts the fluorescence detector that fits into peep-hole front, air port conical space, monitors the state of blast-furnace tuyere.This method needs this device is carried out dismounting at blast furnace staying, when safeguarding the air port, causes inconvenience.And optical detection requires tested regional light transmission good, and the detected fluid solid concentration is suitable.Yet pipeline is opaque substantially in the practical application, and pulsating flow, density stream equal flow type often appear in coal dust in process of pneumatic transmission, become the major obstacle that optical detection is used.
Therefore, how to monitor two-phase flow parameter easily and accurately and remain a technical barrier that needs to be resolved hurrily.
In production practices, need the two-phase flow parameter of monitoring mainly to comprise solid volume concentration, two-phase flow speed, mass rate and temperature etc.Wherein, solid volume concentration, two-phase flow speed are still not have the flow parameter that accurate, reliable method is monitored up to now.
Summary of the invention
According to an aspect of the present invention, a kind of two-phase flow parameter monitoring method is provided, described two-phase flow comprises that working medium flows through mutually and in pipeline with carrier mutually, described pipeline comprises at least one section dielectric material pipe that is formed by dielectric material, described dielectric material pipe has identical internal diameter with described pipeline, described method is included in utilizes capacitance method to detect the volumetric concentration of described working medium phase of described two-phase flow and the flow velocity of described two-phase flow when described two-phase flow flows through described pipeline, wherein
The process that detects working medium phase volume concentration comprises: on described dielectric material tube outer surface, vertically inciting somebody to action at least in the same manner along described dielectric material pipe, the pair of electrodes plate is reversed into spiral-shaped; Detect the electric capacity that on described at least one pair of battery lead plate, generates when described two-phase flow flows through described dielectric material pipe; According to relational expression C=K[ε g+ (ε sg) β] calculate the volumetric concentration of the described working medium phase of described two-phase flow, wherein, C is by the detected capacitance of described at least one pair of battery lead plate, K is the characteristic parameter by the physical dimension decision, ε sAnd ε gBe respectively the described working medium phase and described carrier specific inductive capacity mutually of described two-phase flow, β is the volumetric concentration of described working medium phase,
The process that detects two-phase flow speed comprises: vertical along described dielectric material pipe on the outside surface of described dielectric material pipe, the upstream and downstream place in described at least one pair of battery lead plate one side is provided with identical capacitive transducer according to identical mode; The random time sequence signal that generates at upstream capacitive transducer and downstream capacitive transducer place respectively when detecting described two-phase flow and flowing through described dielectric material pipe; Described random time sequence signal is carried out correlation analysis, calculate the transit time of described two-phase flow by described upstream and downstream sensor; Calculate the flow velocity of described two-phase flow according to relational expression v=L/ τ, wherein, v is the flow velocity of described two-phase flow, and L is the distance between the sensor of described upstream and downstream, and τ is the described transit time.
According to another aspect of the present invention, a kind of two-phase flow parameter monitoring system is provided, it is characterized in that, described system comprises phase concentration sensor and flow sensor, wherein, described phase concentration sensor comprises: dielectric material pipe, and described dielectric material pipe is made by dielectric material, and two-phase flow can flow through from described dielectric material pipe; At least one pair of battery lead plate, described at least one pair of battery lead plate is incorporated on the outside surface of described dielectric material pipe, and vertically reversing in the same manner to spiral-shaped along described dielectric material pipe.Described flow sensor comprises: upstream capacitive transducer and downstream capacitive transducer, described upstream capacitive transducer is identical capacitive transducer with described downstream capacitive transducer, and vertically is arranged on the upstream and downstream place of described at least one pair of battery lead plate one side on the outside surface of described dielectric material pipe in the same manner along described dielectric material pipe.
Description of drawings
Fig. 1 is according to condenser type solid concentration principle of sensors synoptic diagram of the present invention.
Fig. 2 is the left side view of Fig. 1 condenser type solid concentration sensor.
Fig. 3 is the right side view of Fig. 1 condenser type solid concentration sensor.
Fig. 4 is the longitudinal sectional view according to an embodiment of solid concentration sensor of the present invention.
Fig. 5 A is for utilizing the principle schematic of correlation measurement two-phase flow speed according to the present invention, and Fig. 5 B and Fig. 5 C are the time series signal synoptic diagram that the upstream and downstream sensor generates when two-phase flow flows through.
Fig. 6 is an embodiment according to two-phase flow parameter monitoring system of the present invention.
What Fig. 7 A and Fig. 7 B represented is the time series signal shown in Fig. 5 B and Fig. 5 C is transformed to the width random variation behind the zero passage testing circuit pulse train synoptic diagram.
Embodiment
The two-phase flow that in industrial and agricultural production practice, uses, general all by the carrier phase (air in for example above-mentioned coal dust-air two-phase flow) that plays carrier function with as the working medium of working medium mutually (coal dust in for example above-mentioned coal dust-air two-phase flow) form.In Dual-Phrase Distribution of Gas olid, solid phase is the working medium phase, and gas phase is the carrier phase.In this manual, be that the present invention will be described for example with the Dual-Phrase Distribution of Gas olid.But it will be understood by those skilled in the art that basis the instruction here, the present invention certainly is applied to other forms of two-phase flow, as biphase gas and liquid flow.
Below, introduce the method for measuring solid concentration, two-phase flow speed and mass rate according to the present invention.
Solid phase (working medium phase) concentration
From basic test in theory, the present invention utilizes capacitance method that the volumetric concentration of the working medium phase (solid phase) in the different two-phase flow of specific inductive capacity is detected.When the Dual-Phrase Distribution of Gas olid with differing dielectric constant by between the pole plate of phase concentration sensor during formed checkout area, because the variation of solid concentration can cause the change of two-phase flow effective dielectric constant, thereby the electric capacity output valve of phase concentration sensor is changed thereupon, so the size of capacitance promptly can be used as measuring of two-phase flow solid concentration.
But, in the practical application of a lot of two-phase flows (situation that the coal dust strength is carried in routine electric power, the metallurgy industry as previously mentioned), solid phase (working medium phase) is not to be evenly distributed in the gas phase (carrier phase), and its variations in flow patterns is extremely complicated, is not linear relationship one to one between measurement capacitance and the solid concentration; And capacitance type sensor itself has the non-uniformity problem of its intrinsic checkout area sensitivity profile, when flow pattern changes, will cause serious measuring error.Therefore, directly utilize traditional capacitive sensor structure to detect the solid concentration of two-phase flow, in production practices, can't realize.
Fig. 1~3 show according to condenser type phase concentration principle of sensors synoptic diagram of the present invention, and wherein, Fig. 1 is a front elevation, and Fig. 2 is a left side view, and Fig. 3 is a right side view.
According to phase concentration sensor of the present invention, form by spiral-shaped surface plates, comprise at least one pair of by the pole plate that source plates 1 and detection pole plate 2 constitute, described at least one pair of pole plate reverses to spiral-shaped by same way as.In order to overcome soft field effect, between the consecutive roots edges of boards of source plates 1 and detection pole plate 2, be formed with the limit protection pole plate 3 of strip, protection pole plate 3 in limit reverses to spiral-shaped by same way as with source plates 1 and detection pole plate 2.
In the preferred embodiment shown in Fig. 1~3, phase concentration sensor according to the present invention comprises 4 pole plates: source plates 1, detect two limits protection pole plates 3 of pole plate 2 and symmetry, all these pole plates have vertically reversed 180 ° along dielectric material pipe 4 simultaneously.
Because battery lead plate has taken place to reverse; causing also having taken place 180 ° along the dielectric material pipe direction by sensor source pole plate, detection pole plate and the both sides protection detection electric field that pole plate constituted reverses; thereby make the electric capacity output characteristics of phase concentration sensor also with the electric capacity output characteristics of traditional straight surface plates capacitance type sensor a great difference be arranged, also great changes have taken place for the distribution character of its sensitivity.The present invention is by redesign pole plate shape, promptly adopt spiral-shaped power supply pole plate and detect pole plate, replace the straight surface plates that the conventional condenser sensor uses, improved the homogeneity of checkout area, reduce the dependence of convection, thereby in the permissible error scope, make measurement capacitance only relevant and irrelevant, realized utilizing the detection of capacitance method two-phase flow concentration with its space distribution with solid concentration.By using limit protection pole plate, make phase concentration sensor of the present invention can further overcome the soft field effect problem that produces when utilizing electric field to detect, further improved the measuring accuracy and the reliability of phase concentration sensor of the present invention.
Fig. 4 is the longitudinal sectional view according to an embodiment of phase concentration sensor of the present invention.See for clear, each pole plate is not shown among Fig. 4.
Phase concentration sensor according to the present invention comprises the pipeline configuration part and is arranged on the draw bail part at pipeline configuration part one end or two ends.Be appreciated that when this pick-up unit places between Two-phase Flow Pipeline Transport entrance point and the endpiece, the draw bail part need be set at two ends.
Pipeline configuration partly comprises foregoing dielectric material pipe 4 and aforementioned each pole plate 1,2,3 that is combined on dielectric material pipe 4 outside surfaces.
Dielectric material pipe 4 has identical internal diameter with the pipeline of two-phase flow to be detected.It will be understood by those skilled in the art that according to different service conditions, different to the specific requirement meeting of dielectric material pipe 4.For example in metallurgical, power industry under the occasion of strength pulverized coal conveying, require that dielectric material pipe is wear-resistant, each to good uniformity, withstand voltage, interior finish is high, therefore, can use for example corundum, quartz, pottery etc.
Source plates 1, detection pole plate 2 and limit protection pole plate 3 can use the plate material of conventional condenser sensor, for example copper.The sheet copper or the Copper Foil of suitable thickness can be cut into the shape that needs, stick on then on the outside surface of dielectric material pipe 4; Perhaps, adopt technology such as vacuum coating on the outside surface of dielectric material pipe 4, to form each pole plate.The technology that forms battery lead plate on the outside surface of dielectric material pipe 4 is the known technology of this area, here repeats no more.
The effect of radome 15 provides the needed electromagnetic environment of phase concentration normal operation of sensor of the present invention, therefore, need make with the material that can prevent electromagnetic interference (EMI), for example stainless-steel tube.
Between radome 15 and dielectric material pipe 4, can be air.In order to prevent that reliably the pole plate position from play (the especially artificial situation of pasting of battery lead plate) taking place, and can fill filler 16 between radome 15 and dielectric material pipe 4 in processes such as carrying, installation.Filler 16 can be epoxy resin or other similar materials.
In addition, in practical application such as steel mill, power plant, condition of work is very poor sometimes.At this moment, need to use the protection tube 14 that effectively to resist bad working environments.Protection tube 14 can use the normally used material of any those skilled in the art, metal, nonmetal can, as long as can play a protective role.
In the embodiment shown in fig. 4, draw bail partly is included in the flange 10 of the two ends formation of above-mentioned pipeline structure division, is processed with connection holes 12 on flange 10.The flange of relative set is connected with connection holes/part on flange 10 and connection holes 12 and the Two-phase Flow Pipeline Transport to be measured, thereby makes two-phase flow phase-concentration detection apparatus of the present invention constitute complete two-phase flow transfer passage with Two-phase Flow Pipeline Transport to be measured.It is known utilizing the technology that flange connects or other modes are sealedly connected two pipe fittings, therefore, explains no longer in detail here.
Introduce the method for utilizing finite element numerical method design phase concentration sensor of the present invention below.
The driving voltage frequency that the phase concentration sensor adopts is that several KHz arrive several megahertzes, therefore can regard the responsive field of phase concentration sensor as electrostatic field.When ignoring the limited edge effect that brings of electrode pad axial length, this electrostatic field can be reduced to two dimensional field and handle.
Electrostatic field problem is described by Poisson equation:
Wherein, With Be respectively divergence and gradient operator, ε is that specific inductive capacity distributes, Be potential function, Γ sBe the set that point on the radome 15 is constituted, Γ iBe the set that point on the source plate plate 1 is constituted, Γ jFor detecting the set that point is constituted on the pole plate 2, Γ kFor putting the set that is constituted on the protection pole plate 3.
The finite element numerical method is to find the solution the functional extreme-value problem of following formula:
Wherein, D is the space in the radome 15.
Specifically, the output capacitance of phase concentration sensor of the present invention is to obtain as follows: a pair of spiral pole plate 1,2 is split into some small unit along Two-phase Flow Pipeline Transport (dielectric material pipe) cross-sectional direction, and spiral-shaped 1,2 total capacitances of surface plates condenser type phase concentration sensor two-plate (detecting pole plate 2 to the electric capacity between the source plates 1) can be obtained by the capacitance of all small unit.
In the phase concentration sensor, the change in dielectric constant of the arbitrary subregion medium in the surveyed area all can cause the variation of capacitance between pole plate, the foundation that Here it is measures with the phase concentration sensor.In a preferred embodiment of the invention, the purpose of design is the influence that is not subjected to variations in flow patterns and phase changes in distribution for the measurement that makes working medium phase concentration (solid concentration) basically, in other words, in whole checkout area, the sensor output that the concentration increment that tiny area produced of equal volume causes changes equal or is tending towards equal.That is, on the basis of satisfying the requirement of phase concentration transducer sensitivity, make homogeneity error reach minimum as far as possible.
Suppose that with whole checkout area subdivision be M unit.Sensor relative sensitivity (S ε, avg) implication be meant the mean value of each unit relative sensitivity in the checkout area, be a normalized numerical value, be defined as:
S ϵ , avg = 1 M Σ j = 1 M S ϵ , j
S ε, jBe the unit relative sensitivity, as the specific inductive capacity (ε that changes one of them unit 0→ ε), other unit (ε that remains unchanged 0), it is defined as:
S i , j = ( C ϵ , j - C 0 ) / C 0 β j
In the formula, C 0: natural capacity value during blank pipe;
C ε, j: the absolute capacitance values when j unit is full of discrete phase material (j=1,2 ... M);
β j: the volumetric concentration of j unit.
According to the notion of standard deviation in the statistical analysis and rate of change, definition checkout area homogeneity error parameter (SVP) is:
SVP = S ϵ , dev S ϵ , avg · 100 %
In the formula, S ε, devBe the standard deviation of each unit relative sensitivity in the checkout area, its mathematic(al) representation is:
S ϵ , dev = ( 1 M Σ j = 1 M ( S ϵ , j - S ϵ , avg ) 2 ) 1 / 2
Obviously, the SVP value is littler, and promptly homogeneity error is littler, represents that the detection sensitivity of this condenser type phase concentration sensor distributes more evenly, and the measuring error of sensor is littler.
At present, the finite element analysis common computer software bag of a lot of commercializations is arranged both at home and abroad, these software packages can be used for according to above-mentioned instruction of the present invention, at concrete condition of work, calculate the concrete structure parameter of capacitive transducer.Certainly, also coding calculating voluntarily.
Theoretical analysis and test show, utilize phase concentration sensor of the present invention and two-phase flow phase-concentration detection apparatus to detect the solid concentration of Dual-Phrase Distribution of Gas olid, homogeneity error may diminish to 3.9% (if use traditional straight plate capacitor, homogeneity error is then up to more than 40%), therefore, the present invention has solved the non-uniformity problem of checkout area sensitivity profile effectively, can overcome soft field effect effectively, thereby reliably, measurement volumes concentration parameter accurately.
Two-phase flow speed
Fig. 5 A is for utilizing the principle schematic of correlation measurement two-phase flow speed according to the present invention, Fig. 5 B and Fig. 5 C are the time series signal synoptic diagram that the upstream and downstream sensor generates when two-phase flow flows through.
The flow sensor that is used to measure two-phase flow speed according to the present invention comprises identical upstream and downstream sensor, and the upstream and downstream sensor can be the sensor that can generate time series signal when two-phase flow flows through.Can use traditional capacitive transducer in the present invention, the length along pipeline axial of capacitive transducer is the smaller the better.
If as a procedures system, upstream sensor output signal X (t) is as system's input with the pipeline space between the upstream and downstream sensor, downstream sensor output signal Y (t) has so as the output of system:
y ( t ) = ∫ 0 ∞ h ( t , α ) X ( t - α ) d α + n ( t ) - - - ( 1 )
Here h (t a) is the unit impulse response of system, n (t) be among the Y (t) with the irrelevant noise of X (t).For the smooth flow state, the unit impulse response of system and time are irrelevant, so formula (1) becomes:
y ( t ) = ∫ 0 ∞ h ( t ) X ( t - α ) d α + n ( t ) - - - ( 2 )
According to definition, the cross correlation function of upstream and downstream flowing noise signal is:
R xy ( τ ) = lim T → ∞ 1 T ∫ 0 T X ( t - τ ) y ( t ) d t + n ( t ) - - - ( 3 )
In formula (2) substitution formula (3):
R xy ( τ ) = ∫ 0 T h ( α ) R xx ( τ - α ) y ( t ) d α + R xn ( τ ) - - - ( 4 )
Because x (t) and n (t) are irrelevant, so when integral time is fully big, R Xn(τ) go to zero, this pattern (4) becomes:
R xy ( τ ) = ∫ 0 ∞ h ( α ) R xx ( τ - α ) d α - - - ( 5 )
If detected fluid satisfies " coagulating type (the frozen pattern) " of Taylor's proposition and supposes that this system is a linear system so, its impulse response only is the unit pulse that postpones:
h(α)=δ(τ-τ 0) (6)
Here, τ 0=L/v is the transit time of solid phase stream group by distance between two sensors.To get in formula (6) the substitution formula (5):
R xy(τ)=R xx(τ-τ 0) (7)
Cross correlation function equals system input signal x (t) delay τ like this 0Autocorrelation function.According to theory of random processes, work as R Xx(0) auto-correlation function value is maximum the time, so as τ=τ 0The time, cross correlation function is maximum.Utilize this principle,, can determine the transit time τ of fluid according to the cross correlation function peak value 0Thereby, calculate flow rate of fluid v=L/ τ 0
The two-phase flow parameter monitoring system
Fig. 6 is an embodiment according to two-phase flow parameter monitoring system of the present invention.The phase concentration sensor 20 access Two-phase Flow Pipeline Transport that are used for measuring solid concentration according to the present invention, become the part of Two-phase Flow Pipeline Transport, the flow sensor 21 that is used to measure two-phase flow speed according to the present invention is arranged in pipeline along vertical (being the Two-phase flow direction) of Two-phase Flow Pipeline Transport, can be positioned at the upstream or the downstream of phase concentration sensor 20.The structure and the principle of phase concentration sensor 20 and flow sensor 21 are explained in the above, repeat no more here.
The electric signal of phase concentration sensor 20 and flow sensor 21 outputs is analyzed and is handled by data handling system.In specific embodiment shown in Figure 6, the I/O interface 23 that the electric signal of phase concentration sensor 20 and flow sensor 21 outputs is used through signal isolation system 22 and data transmission is sent to data acquisition system (DAS) 24.Signal isolation system 22 plays the protective effect to the downstream signal disposal system, can adopt general signal isolation system to realize fully.Data acquisition system (DAS) 24 can for example be a Single Chip Microcomputer (SCM) system, and according to concentration signal that is collected and flow velocity signal, the method for utilizing the present invention to introduce calculates the concentration of working medium phase and the flow velocity of two-phase flow.Through data communication systems 25 such as for example 485 buses, be sent to data handling system 26 through data acquisition system (DAS) 24 pretreated data.Data handling system 26 is carried out data analysis and system state and is judged according to concentration and the flow velocity of two-phase flow and the abnormality judgment method under the concrete operating mode of working medium phase.The result who analyzes and judge can be exported by output devices such as display 27 and printers 28 according to various known modes.
Field data comprises the technical parameter in the various actual production process, for example, diphasic stream parameters such as the specific inductive capacity of solid phase and gas phase, density in the two-phase flow, pipeline configuration parameters such as the diameter of Two-phase Flow Pipeline Transport, specific inductive capacity, the structural parameters of phase concentration sensor and flow sensor.
In the embodiment shown in fig. 6, also comprise temperature sensor 30, simultaneously temperature parameter is monitored.Monitoring for temperature parameter can utilize art technology known prior art scheme to carry out, and introduces no longer in detail here.
If the effective dielectric constant of two-phase flow is ε Eff, the specific inductive capacity of solid phase (working medium phase) and gas phase (carrier phase) is respectively ε sAnd ε gIf solid phase is evenly distributed on (as mentioned above, phase concentration sensor design of the present invention can guarantee the establishment of this prerequisite effectively), then ε in the gas phase EffVolume ratio decision by the gas-solid two-phase:
ϵ eff = V s V ϵ s + V g V ϵ g
V in the formula sAnd V gBe respectively the volume that solid phase (working medium phase) and gas phase (carrier phase) respectively account for, V is the cumulative volume of checkout area between the phase concentration sensor plate, and V=V s+ V g, can draw by following formula:
ϵ eff = V s V ϵ s + V - V s V ϵ g = ϵ g + ( ϵ s - ϵ g ) V s V = f ( V s / V )
If solid volume concentration is β, then
β=V s/V
Therefore have:
C=K·ε eff=K·[ε g+(ε sg)·β]
K is the characteristic parameter by the decision of phase concentration sensor construction size in the formula, ε sAnd ε gBe all knownly, so capacitance C is only relevant with solid concentration β.Because data acquisition system (DAS) 24 has obtained capacitance C from the phase concentration sensor, so, can calculate solid concentration β.
According to a preferred embodiment of the present invention, the random signal of upstream and downstream sensor output is transformed to the pulse train of the width random variation shown in Fig. 7 A and Fig. 7 B through the zero passage testing circuit.Because the zero-crossing pulse sequence is a time series at random, therefore can assert that the pulse of distinct pulse widths in limited Measuring Time all can only occur once, can not repeat.Again because upstream and downstream zero-crossing pulse sequence has corresponding relation, so,, can conclude that then this pulse pulse corresponding with the upstream is by being produced with first-class group if in the downstream, can find the identical pulse of width with it for a certain pulse of upstream.Thereby available following condition as identification with the condition of first-class group: (t j-t i)-(t n-t m)=0.T in the formula j, t iBe respectively the moment of two adjacent saltus steps from low to high in the zero-crossing pulse sequence of upstream, Dui Ying pulse is X with it it n, tm is two jumping moments from low to high in the zero-crossing pulse sequence of downstream, corresponding pulse is Y mIf the following formula condition satisfies, and just can conclude Y mAnd X iBe by being produced with first-class group.Thereby transit time τ 0For: τ 0=t m-t i=t n-t j
Owing in the measurement of reality, can not accomplish ideal state completely, thereby the criterion of the corresponding stream of searching group changes correspondingly into: (t j-t i)-(t n-t m)<± Δ.In the formula, i and m are respectively with first-class group and cross the zero-crossing pulse that zero passage produces in upstream and downstream, and satisfy the limiting case of following formula, and promptly two pulse widths differ Δ, suppose upstream pulse broad, that is:
Δ=(t j-t i)-(t n-t m)
=t j-t i-t n+t m
=(t m-t i)-(t n-t j),
Elapsed time poor (transit time) τ then 0Can be represented by the formula: τ 0=(τ 1+ τ 2)/2, wherein, τ 1=t m-t i, τ 2=t n-t jSo, have:
τ 0=[(t m-t i)+(t n-t j)]/2
=[Δ+(t n-t j)+( tn-t j)]/2
=Δ/2+(t n-t j)
=Δ/2+τ 2
Or:
τ 0=[(t m-t i)+(t n-t j)]/2
=[(t m-t i)+(t m-t i)-Δ]/2
=(t m-t i)-Δ/2
=τ 1-Δ/2
So: the maximum absolute error of systematic survey=± Δ/2
The maximum relative error of systematic survey=(± Δ/2)/τ Min
Wherein, τ MinBe the measurement lower limit of system, for the maximum relative error that makes measurement less than ± 0.5%, select Δ=0.01 * τ Minμ s.The situation of downstream pulse similarly.
So, calculate two-phase flow speed v=L/ τ 0, wherein, L is the longitudinal length between the sensor of upstream and downstream in the flow sensor.
Based on solid concentration that calculates and flow velocity, and then obtain the mass rate Q=Av β of solid phase, wherein, A is the cross-sectional area of Two-phase Flow Pipeline Transport.
Though described principle of the present invention and embodiment at gas-solid biphase flow above; but; under above-mentioned instruction of the present invention; those skilled in the art can carry out various improvement and distortion on the basis of the foregoing description, and these improvement or distortion drop in protection scope of the present invention.It will be understood by those skilled in the art that top specific descriptions just in order to explain purpose of the present invention, are not to be used to limit the present invention.Protection scope of the present invention is limited by claim and equivalent thereof.

Claims (10)

1. two-phase flow parameter monitoring method, described two-phase flow comprises that working medium flows through mutually and in pipeline with carrier mutually, described pipeline comprises at least one section dielectric material pipe that is formed by dielectric material, described dielectric material pipe has identical internal diameter with described pipeline, described method is included in utilizes capacitance method to detect the volumetric concentration of described working medium phase of described two-phase flow and the flow velocity of described two-phase flow when described two-phase flow flows through described pipeline, wherein
The process that detects working medium phase volume concentration comprises: on described dielectric material tube outer surface, vertically inciting somebody to action at least in the same manner along described dielectric material pipe, the pair of electrodes plate is reversed into spiral-shaped; Detect the electric capacity that on described at least one pair of battery lead plate, generates when described two-phase flow flows through described dielectric material pipe; According to relational expression C=K[ε g+ (ε sg) β] calculate the volumetric concentration of the described working medium phase of described two-phase flow, wherein, C is by the detected capacitance of described at least one pair of battery lead plate, K is the characteristic parameter by the physical dimension decision, ε sAnd ε gBe respectively the described working medium phase and described carrier specific inductive capacity mutually of described two-phase flow, β is the volumetric concentration of described working medium phase,
The process that detects two-phase flow speed comprises: vertical along described dielectric material pipe on the outside surface of described dielectric material pipe, the upstream and downstream place in described at least one pair of battery lead plate one side is provided with identical capacitive transducer according to identical mode; The random time sequence signal that generates at upstream capacitive transducer and downstream capacitive transducer place respectively when detecting described two-phase flow and flowing through described dielectric material pipe; Described random time sequence signal is carried out correlation analysis, calculate the transit time of described two-phase flow by described upstream and downstream sensor; Calculate the flow velocity of described two-phase flow according to relational expression ν=L/T, wherein, ν is the flow velocity of described two-phase flow, and L is the distance between the sensor of described upstream and downstream, and τ is the described transit time.
2. two-phase flow parameter monitoring method as claimed in claim 1, wherein, described at least one pair of electrode reverses 180 °.
3. two-phase flow parameter monitoring method as claimed in claim 2; also comprise at least one pair of spiral-shaped battery lead plate of formation on the described dielectric material tube outer surface: between the consecutive roots edges of boards at described at least one pair of battery lead plate; the limit protection pole plate of strip is set, and described limit protection pole plate is reversed into spiral-shaped according to the mode identical with described at least one pair of battery lead plate.
4. as claim 1,2 or 3 described two-phase flow parameter monitoring methods, behind the described random time sequence signal that obtains place, described upstream and downstream, make described random time sequence signal be transformed to the pulse sequence signal of width random variation, then described transit time τ=(τ through the zero passage testing circuit 1+ τ 2)/2,
Wherein, τ 1=t m-t i, τ 2=t n-t j, t j, t iIt is respectively the moment of two adjacent saltus steps from low to high in the zero-crossing pulse sequence of upstream; t n, t mBe two adjacent jumping moments from low to high in the zero-crossing pulse sequence of downstream, and, (t j-t i)-(t n-t m)<± Δ, ± Δ are 2 times of maximum absolute error of systematic survey.
5. as claim 1,2 or 3 described two-phase flow parameter monitoring methods, also comprise the mass rate of calculating described two-phase flow according to relational expression Q=A ν β, wherein, Q is the mass rate of described two-phase flow, and A is the cross-sectional area of described Two-phase Flow Pipeline Transport.
6. a two-phase flow parameter monitoring system is characterized in that, described system comprises phase concentration sensor and flow sensor, wherein,
Described phase concentration sensor comprises: dielectric material pipe, and described dielectric materials pipe is made by dielectric material, and two-phase flow can flow through from described dielectric material pipe; At least one pair of battery lead plate, described at least one pair of battery lead plate is incorporated on the outside surface of described dielectric material pipe, and along vertically the reversing in the same manner to spiral-shaped of described dielectric material pipe,
Described flow sensor comprises: upstream capacitive transducer and downstream capacitive transducer, described upstream capacitive transducer is identical capacitive transducer with described downstream capacitive transducer, and vertically is arranged on the upstream and downstream place of described at least one pair of battery lead plate one side on the outside surface of described dielectric material pipe in the same manner along described dielectric material pipe.
7. two-phase flow parameter monitoring system as claimed in claim 6 is characterized in that, described at least one pair of battery lead plate reverses 180 °.
8. two-phase flow parameter monitoring system as claimed in claim 7; it is characterized in that; described phase concentration sensor also comprises the strip limit protection pole plate between the consecutive roots edges of boards of described at least one pair of battery lead plate; described limit protection pole plate is incorporated on the outside surface of described dielectric material pipe, and reverses to spiral-shaped according to the mode identical with described at least one pair of battery lead plate.
9. as claim 6,7 or 8 described two-phase flow parameter monitoring systems, it is characterized in that the described upstream capacitive transducer of described flow sensor and described downstream capacitive transducer are the capacitance sensor array of arranging in the same manner.
10. two-phase flow parameter monitoring system as claimed in claim 9, it is characterized in that, described monitoring system also comprises: data acquisition system (DAS), described data acquisition system (DAS) receive from the signal of described phase concentration sensor and described flow sensor and calculate the working medium concentration mutually and the flow velocity of two-phase flow in the two-phase flow; Data communication system is connected with described data acquisition system (DAS), is used to transmit concentration and flow speed data; Data handling system is connected with described data communication system, and the concentration and the flow speed data that send according to described data communication system carry out analyzing and processing.
CNA2008101726180A 2008-11-06 2008-11-06 Two-phase flow parameter monitoring method and system Pending CN101477074A (en)

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KR1020090107161A KR101224362B1 (en) 2008-11-06 2009-11-06 Device for Measuring Two-phase Flow Phase Concentration, System and Method for Measuring Flow Parameters of Two-phase Flow
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