CN104897221B - The solid flow continuous measurement system and measuring method of process of pneumatic transmission - Google Patents

The solid flow continuous measurement system and measuring method of process of pneumatic transmission Download PDF

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CN104897221B
CN104897221B CN201410084357.2A CN201410084357A CN104897221B CN 104897221 B CN104897221 B CN 104897221B CN 201410084357 A CN201410084357 A CN 201410084357A CN 104897221 B CN104897221 B CN 104897221B
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gas
solid flow
measuring
venturi tube
formula
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CN104897221A (en
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陆海峰
郭晓镭
龚欣
梁钦锋
代正华
刘海峰
许建良
于广锁
王辅臣
王亦飞
陈雪莉
李伟锋
周志杰
王兴军
赵辉
李超
龚岩
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SHANGHAI YINENG GAS TECHNOLOGY Co Ltd
East China University of Science and Technology
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SHANGHAI YINENG GAS TECHNOLOGY Co Ltd
East China University of Science and Technology
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Abstract

The invention discloses the solid flow continuous measurement system and measuring method of a kind of process of pneumatic transmission.Described solid flow continuous measurement system includes an input channel, a Venturi tube and an output channel;Point-blank, the length of the input channel and the output channel is separately more than or equal to 80D for the input channel, the Venturi tube and the output channel;A contraction section, a larynx section and an expansion segment, the input channel that described Venturi tube includes being sequentially communicated are connected with the contraction section, and the expansion segment is connected with the output channel;The length L of the larynx sectiontIt is more than or equal to 40 with the ratio between the diameter d of the larynx section;Described solid flow continuous measurement system also includes a first pressure tester, a second pressure tester, one the 3rd pressure tester and a temperature measuring set.The present invention can meet that deviation is only within ± 5% from dilute phase to the continuous measurement of the solid flow of close phase.

Description

The solid flow continuous measurement system and measuring method of process of pneumatic transmission
Technical field
The present invention relates to Dual-Phrase Distribution of Gas olid field, is continuously measured more particularly to a kind of solid flow of process of pneumatic transmission The measurement of induction system pulverized coal flow in the powdered coal pressuring gasified technique of system and measuring method, more particularly to air flow bed.
Background technology
Geldart-D particle is an ancient and effective technology using gas energy conveying solid substance particle, chemical industry, metallurgy, The fields such as food processing, medicine and the energy are widely applied.In practical application, in order to meet the company needed for production process Continuous measurement and Automated condtrol, reach safe efficient and economical operation requirement, the online transient measurement of powder quality flow is As key subject urgently to be resolved hurrily in air-transport system.If it can be realized with certain confidence level to powder quality flow On-line measurement, the controlling and regulating system of powder flow can be set up.
But due to Presence of an interface effect and relative velocity between gas-particle two-phase in air-transport system, and boundary exists Time and spatially there is randomness, cause its flow behavior and detection method more than single-phase flow system complex.Existing measurement Method can not meet continuous measurement and the requirement of Automated condtrol mostly.Although all having done substantial amounts of research work both at home and abroad, It is most of also in the laboratory research development phase but the multiphase flow rate of commercialization is calculated as number seldom.
At present, the mass flow of pulverized coal injection in blast furnace is to calculate one section using the method for electronic scale weighing in metallurgical industry Average value in time, it is impossible to realize real-time continuous measurement, directly obtain instantaneous value.The powdered coal pressuring gasified technique of air flow bed uses Import solid mass flow meter measures the mass flow of coal dust, and instrument uses the mark in kind for preceding needing to carry out it under applying working condition It is fixed, complex operation, instrument price costliness.And calibration result is influenceed by pulverized coal conveying property, when coal dust physical property changes, Different degrees of deviation occurs in measurement result.
Differential pressure flowmeter, especially Venturi tube due to it is simple in construction, be easily installed, be easy to maintenance, stable performance, warp The advantages that durable of helping, is favored by researcher and engineers and technicians.Carlson, Farbar et al. pass through many experiments and reason By research, shown that gas particles mixture has corresponding relation by differential pressure and granule content caused by Venturi tube, i.e., it is famous Farbar pressure differences-gas-solid ratio empirical equation Δ Pmix/ΔPgas=1+mZ.The formula has been widely used for low pressure, dilute phase gas Power induction system, by gas flowmeter or the densitometer of arranging in pairs or groups, the measurement request of solid flow can be met.For high pressure dense phase gas Power course of conveying, the influence of carrier gas density and solid-gas ratio are larger.Now, it is if still public using Farbar pressure differences-gas-solid ratio experience Formula measures solid flow, then can produce larger error.
The content of the invention
The technical problems to be solved by the invention are that overcoming existing several e measurement technologies has the defects of limitation, And provide the solid flow continuous measurement system and measuring method of a kind of process of pneumatic transmission.Measuring method provided by the invention Meet from dilute phase to close phase, in the air-transport system from low pressure to high pressure solid flow measurement request, suitable for powder Carry out real-time continuous flow measurement.The measurement apparatus of the present invention is simple in construction, without arranging in pairs or groups gas flowmeter or densitometer makes With, and do not influenceed by the change of pumped (conveying) medium physical property.
The invention provides a kind of solid flow continuous measurement system of process of pneumatic transmission;Described solid flow is continuous Measuring system includes an input channel, a Venturi tube and an output channel;The input channel, the Venturi tube and described Output channel point-blank, the length of the input channel and the output channel be separately more than or equal to 80D, D are the diameter of the input channel and the output channel;Described Venturi tube include be sequentially communicated a contraction section, One larynx section and an expansion segment, the input channel are connected with the contraction section, and the expansion segment is connected with the output channel It is logical;The length L of the larynx sectiontIt is more than or equal to 40 with the ratio between the diameter d of the larynx section;Described solid flow, which continuously measures, is System also includes a first pressure tester, a second pressure tester, one the 3rd pressure tester and a temperature measuring set;Its In, the first pressure tester is installed on the input channel, the gas phase pressure of the porch for measuring the contraction section Power P1;The second pressure tester is installed in the larynx section, and the distance with the porch of the larynx section is 20d~40d, is used In measure this at gaseous pressure P2;3rd pressure tester is installed in the larynx section, the porch with the larynx section Distance be 40d~60d, for measuring the gaseous pressure P at this3;The temperature measuring set is installed on the input channel, For the gas solid-state temperature T for the porch for measuring the contraction section1
In the present invention, the angle of throat θ of described contraction section is preferably 3~25 °, is more preferably 3~10.5 °.Described The angle of flare α of expansion segment is preferably 1~12 °, is more preferably 1~8 °.The Throttling ratio d/D of described Venturi tube is preferably 0.3~0.8, it is more preferably 0.4~0.7.The length L of the larynx sectiontWith the ratio between the diameter d of larynx section Lt/d(It is hereinafter referred to as long Footpath ratio)Preferably 40~80.
In the present invention, the input channel and the output channel are the conventional pipe for being used to convey gas-solid phase in this area Road.
In the present invention, it is preferred that the solid flow measuring system also includes a data collecting system, the data acquisition System also successively with an A/D transition cards(Analog-to-digital conversion card, for converting analog signals into data signal)Connect with a computer Connect;The first pressure tester includes a first pressure sensor;The second pressure tester passes including a second pressure Sensor;3rd pressure tester includes one the 3rd pressure sensor;The temperature measuring set includes a temperature sensor;Institute State first pressure sensor, the second pressure sensor, the 3rd pressure sensor and the temperature sensor respectively with The data collecting system connection, and analog signal is inputted to the data collecting system.
Wherein, described computer is preferably comprised memory module and computing module, consolidating after being handled for real-time output Phase flow rate data.Wherein, described memory module is used for the pressure drop equation for storing input, and described computing module is used for will collection To flow velocity, pressure and temperature data substitute into pressure drop equation in further solve solid flow.
Wherein, the first pressure sensor is preferably primary diaphragm formula pressure sensor, and passes through one first impulse Hole is installed on the input channel;On the bearing of trend along the Venturi tube, first tracting pressuring hole and the contraction The distance of the porch of section is conventional for this area, preferably within 20D, more preferably within 5D.The second pressure sensing Device is preferably secondary diaphragm formula pressure sensor, and is installed on by one second tracting pressuring hole in the larynx section of the Venturi tube. 3rd pressure sensor is preferably tertiary membrane chip pressure sensor, and is installed on the text by one the 3rd tracting pressuring hole In the larynx section of venturi.
Wherein, the temperature sensor is arranged on the input channel preferably by a thermometer hole;The thermometer hole It is conventional for this area with the distance of the porch of the contraction section, preferably within 20D, more preferably within 5D.
Present invention also offers a kind of solid flow method for continuous measuring of process of pneumatic transmission, described measuring method bag Include following steps:
(1)Dual-Phrase Distribution of Gas olid is passed through above-mentioned solid phase continuously measuring flow system, and starts the solid flow and continuously surveys Amount system, measurement parameter P1、P2、P3And T1
(2)By step(1)The parameter P measured1、P2、P3And T1Substitute into Venturi tube pressure drop equation group 1.:
The gas velocity V of contraction section porch can be calculatedg1(Unit is m/s)With solid and gas mass ratio Z, then according to public affairs FormulaCalculate to obtain gas phase flow rate Mg, then according to formula 2.:
Ms=ZMg
Further calculate to obtain solid flow Ms(Unit is Kg/s);
Equation group 1. in, ρsFor solid Density (unit Kg/m3), M is the molal weight of the gas molecule of gas phase(Unit For g/mol), R is mol gas constant, and β is Venturi tube Throttling ratio, is the larynx footpath d of the Venturi tube and the input pipe The ratio between the diameter D in road;
Equation group 1. in, C, C ' be efflux coefficient, they are all the functions of reynolds number Re, and C and Re functional relation can tables It is shown as formula 3.:
C=f (Re)=aReb
Formula 3. in, reynolds number Re calculates according to equation below:Re=DVg1ρg1g1, ρg1、μg1It is the literary mound respectively In pipe porch gas density(Unit is Kg/m3), gas viscosity(Unit is Pa/s), ρg1、μg1Respectively according to following public affairs Formula is calculated:ρg1=P1M/RT1Wherein dgIt is gas molecule diameter(Unit is m), Tabling look-up to obtain;
Formula 3. in, coefficient a, b are determined as follows:Using described solid flow continuous measurement system collection two The test data of pure gas phase stream, is designated as operating mode one and operating mode two respectively under the different operating modes of group, and continuous in described solid flow A gas flowmeter is added on the input channel of measuring system, for measuring the flow mass M of gasg, according to equation 4.
The efflux coefficient C under operating mode one and operating mode two is calculated respectively1、C2, and reynolds number Re corresponding to calculating1、Re2, generation Coefficient a, b are calculated in entering formula 3.;Equation 4. in, Δ Pgas=P1-P2(Pressure unit is Pa), ρgFor density of gas phase(It is single Position is Kg/m3), A2For the cross-sectional area at Venturi tube larynx section, A22A1, wherein A1For Venturi tube contraction section porch Cross-sectional area(Unit is m2);MgMeasured by the gas flowmeter(Unit is Kg/s);
Similarly, to C ' there is also functional relation 5.:
C’=f'(Re)=a'Reb'
Coefficient a ', b ' determination method are same as above, the difference is that when 4. being calculated according to equation, Δ Pgas=P1-P3
Equation group 1. in, m, m ' be sensitivity coefficient, they are all the functions for correcting stokes number St, and functional relation is Formula is 6.:
M=f (St)=cStd
Formula 6. in, amendment stokes number St calculated according to equation below: Wherein, dsIt is particle diameter(Unit is m), μg1It is venturi tube inlet gas viscosity(Unit is Pas-1), LcAnd LtRespectively It is the contraction section of the Venturi tube and the length of larynx section(Unit is m);
Formula 6. in, coefficient c, d are determined as follows:Institute is gathered using described solid flow continuous measurement system Operating mode one, the test data of two times gas-solid mixing stream of the operating mode are stated, and in the input pipe of described solid flow measuring system A gas flowmeter and a Weight-measuring device are added on road, a m and Z equation is 7. obtained according to formula:
Formula 7. in, Δ PgasValue(Pressure unit is Pa)With formula 4., Δ PmixValue(Pressure unit is Pa)Calculating side Method with formula 4.;Mass ratio Z, wherein M are 2. calculated to obtain according to formulagValue is measured by the gas flowmeter, MsValue is by the weight Measurement apparatus measures, formula 7. in, calculate two groups of m values, and according to amendment stokes number St calculation formula, calculate Two groups of St values, then substitute into formula 6., you can calculate coefficient c, d;
Similarly, to m ' there is also functional relation 8.:
M'=f'(St)=c'Std'
Coefficient c ', d ' determination method are same as above, the difference is that when 7. being calculated according to equation, Δ Pmix=P1-P3
Flow Measuring System provided by the invention is preferably applied to the gas under different pressures various concentrations with measuring method Power delivery system, the pumped (conveying) medium of described Geldart-D particle system are preferably powder material, are more preferably coal dust, petroleum coke powder Or biomass powder;The gas medium of described Geldart-D particle system is preferably compressed air, nitrogen or carbon dioxide.
When the pumped (conveying) medium of described Geldart-D particle system is coal dust, described Flow Measuring System and measuring method compared with It is applied to 0~10MPa of pressure limit, 0~500Kg/m of concentration range goodly3Situation.
In the present invention, described porch, exit are that mutually stream passes sequentially through the input channel, institute relative to gas-solid For stating Venturi tube and the order of the output channel.
In the present invention, described Venturi tube passes through screw thread or flange method and the input channel, the output channel Connection.
In the present invention, described D, d each mean the internal diameter of pipeline(Unit is m).
It on the basis of common sense in the field is met, above-mentioned each optimum condition, can be combined, it is each preferably real to produce the present invention Example.
Agents useful for same and raw material of the present invention are commercially available.
The positive effect of the present invention is:
The present invention considers the influence of pressure and solid-gas ratio in process of pneumatic transmission, establishes Venturi tube pressure drop side Journey, pass through the real-time continuous measurement solid flow of double pressure difference solid flow measurement apparatus of long throat venturi.The features of the present invention It is that venturi pressure drop equation is applied widely, breaches the limitation in conventional low dilute phase field, disclosure satisfy that different pressures, difference The solid flow test request of process of pneumatic transmission under concentration;Flow measurement device is simple in construction need not arrange in pairs or groups gas flowmeter or Densitometer, stable performance, economy and durability and not by pumped (conveying) medium physical property change influenceed.
Brief description of the drawings
Fig. 1 is the schematic diagram of the solid flow continuous measurement system of the present invention.
Fig. 2 is the structural representation of the long throat Venturi tube of the present invention.
Embodiment
The present invention is further illustrated below by the mode of embodiment, but does not therefore limit the present invention to described reality Apply among a scope.The experimental method of unreceipted actual conditions in the following example, conventionally and condition, or according to business Product specification selects.
Embodiment 1
Fig. 1 is the schematic diagram of the solid flow continuous measurement system of the process of pneumatic transmission of the present invention.Described solid phase stream Amount continuous measurement system includes an input channel 1, a Venturi tube 2 and an output channel 3;The input channel 1, the literary mound In pipe 2 and the output channel 3 point-blank, the input channel 1, the length of the output channel 3 are 100D, and D is The diameter of the input channel 1 and the output channel 3.Fig. 2 is the structural representation of the Venturi tube 2 in the system, described Venturi tube 2 include the contraction section 201, a larynx section 202 and the expansion segment 203 that are sequentially communicated, the input channel 1 and institute State contraction section 201 to be connected, the expansion segment 203 is connected with the output channel 3;The length L of the larynx section 202tWith institute The ratio between diameter d of larynx section 202 is stated as 45;Described solid flow continuous measurement system also includes a first pressure tester 4, one Second pressure tester 5, one the 3rd pressure tester 6 and a temperature measuring set 7;Wherein, the first pressure tester 4 is installed In on the input channel 1, the distance with the porch of the contraction section 201 is 5D, for measuring entering for the contraction section 201 Gaseous pressure P at mouthful1;The second pressure tester 5 is installed in the larynx section 202, the porch with the larynx section 202 Distance be 22d, for measuring the gaseous pressure P at this2;3rd pressure tester 6 is installed in the larynx section 202, Distance with the porch of the larynx section 202 is 40d, for measuring the gaseous pressure P at this3;The temperature measuring set 7 is installed In on the input channel 1, the distance with the porch of the contraction section 201 is 5D, for measuring entering for the contraction section 201 Gas solid-state temperature T at mouthful1
In Fig. 2, θ be the contraction section 201 angle of throat, α be the expansion segment 203 the angle of flare, Lc、Lt、LdRespectively The length of contraction section 201, larynx section 202 and expansion segment 203.In the present embodiment, angle of throat θ is 5 °, and angle of flare α is 8 °, contraction section Length LcFor 50mm, larynx segment length LtFor 270mm, expansion segment length LdFor 30mm.
In the present embodiment, Fig. 1 solid flow measuring system also includes a data collecting system 8, the data acquisition system System also successively with an A/D transition cards 9(Analog-to-digital conversion card, for converting analog signals into data signal)Connect with a computer 10 Connect;The first pressure tester 4 includes a first pressure sensor;The second pressure tester 5 includes a second pressure Sensor;3rd pressure tester 6 includes one the 3rd pressure sensor;The temperature measuring set 7 includes a TEMP Device;The first pressure sensor, the second pressure sensor, the 3rd pressure sensor and the temperature sensor point It is not connected with the data collecting system 8, and analog signal is inputted to the data collecting system 8.
Wherein, described computer 10 also includes memory module and computing module, the solid phase after being handled for real-time output Data on flows.Wherein, described memory module is used for the pressure drop equation for storing input, and described computing module is used to collect Flow velocity, pressure and temperature data substitute into pressure drop equation in further solve solid flow.
Embodiment 2
The structural representation of solid flow continuous measurement system in the present embodiment is as depicted in figs. 1 and 2.Utilize the test The method that system carries out solid flow test is as follows:
(1)Establish pressure drop ratio equation of the Dual-Phrase Distribution of Gas olid by Venturi tube
For the Venturi tube shown in Fig. 1, gross energy equation is established to Dual-Phrase Distribution of Gas olid:
Wherein, Mg、MsThe respectively mass flow of gas phase and solid phase(Kg/s), P1、P2The respectively contraction section of Venturi tube Pressure at entrance and larynx section(N/m2), H1、H2Height respectively at the contraction section entrance of Venturi tube and larynx section(m), ρgFor Density of gas phase(Kg/m3), ρsFor solid Density(Kg/m3), Vg1、Vs1The respectively gas phase of the contraction section entrance of Venturi tube, solid The average speed of phase(m/s), Vg2、Vs2Gas phase, the average speed of solid phase respectively at the larynx section of Venturi tube(m/s), Kg、Ks The respectively coefficient of friction of gas phase and solid phase(Dimensionless).
If Venturi tube Throttling ratio is β=d/D, Venturi tube pressure drop Δ P=P1-P2, equation(1)It can simplify and be transformed into Following form:
For pure gas phase media, formula(2)There is following form:
With formula(2)Divided by formula(3)If quality solid-gas ratio is Ms/Mg=Z,It can then obtain:
Wherein, Δ PmixIn pressure drop caused by contraction section entrance and larynx section, Δ when flowing through Venturi tube for gas-solid mixture PgasPressure drop caused by Venturi tube is flowed through for pure gas phase media.M represents sensitivity level of the Venturi tube pressure drop to solid flow, Referred to as sensitivity coefficient.Equation(4)Considering pressure and solid-gas ratio influences, and can be applied to the powder Pipe in Dense Phase Pneumatic of different pressures Induction system.
(2)Establish the pure gas-phase pressure drop equation of Venturi tube
Pure gas phase flows through Venturi tube, and its mass flow has following relation with pressure difference:
Wherein, A2For the sectional area at Venturi tube larynx section.Further conversion obtains the pressure that pure gas phase flows through Venturi tube Equation drops:
In formula, M is gas molecule quality, T1For the thermodynamic temperature of gas(Unit is K), R is mol gas constant, C For efflux coefficient.
(3)Establish double pressure difference Venturi tube pressure drop equation groups
The pure gas phase and mixture pressure drop equation that gas-particle two-phase passes through Venturi tube be respectively(6)With(4).Research finds, Efflux coefficient C has preferable functional relation, C=f (Re) with reynolds number Re;Sensitivity coefficient m has with stokes number St Preferable functional relation, m=f (St).
By equation(6)And the functional relation C=f (Re) and m=f of Venturi tube efflux coefficient and sensitivity coefficient (St) it is brought into equation(4),
For long throat Venturi tube, such as accompanying drawing 2, venturi tube inlet pressure P can be measured respectively1, larynx section pressure P2、P3, So as to form equation(8)Double pressure difference Venturi tube pressure drop equation groups:
F (Re), f'(Re in formula), f (St) and f'(St) be characterize efflux coefficient C and sensitivity coefficient m functional expression, root Determined according to specific application system.
(4)Solid flow is measured by double pressure difference solid flow measurement apparatus of long throat venturi.
Tested again by the solid flow continuous measurement system of embodiment 1, and the computing module pair for passing through computer Particle speed and pressure data are handled in real time, are solved pressure drop equation group and are obtained and export solid flow.
Embodiment 3
The structural representation of solid flow continuous measurement system in the present embodiment as depicted in figs. 1 and 2, below with this hair It is bright to have particular application as implementation in fine coal pressurization dense phase pneumatic conveying process and be described in more detail.
In the present embodiment, the double pressure difference solid flow continuous measurement systems for including long throat Venturi tube are mounted On the transfer pipeline of Dense Phase Pneumatic Conveying System, pipe diameter D is 15mm, the input pipe being connected with the Venturi tube The length of road and output channel is 100D.
The structural parameters of Venturi tube:Angle of throat θ is 5 °, and angle of flare α is 8 °, and larynx footpath d is 6mm, larynx segment length LtFor 45d;Temperature sensor is apart from venturi tube inlet 5D;Pressure sensor P1Apart from venturi tube inlet 5D, P2And P3Distance respectively Venturi tube larynx section entrance 22d and 40d.
The average grain diameter of pumped (conveying) medium coal dust is about 42 μm, and grain density is about 1400Kg/m3
The efflux coefficient of high-pressure powdered coal dense gas solid flow and the functional relation of sensitivity coefficient that the present embodiment obtains The detailed process of formula is as follows:
Formula C=f (Re)=aRebIn, reynolds number Re calculates according to equation below:Re=DVg1ρg1g1, ρg1、μg1Respectively It is the gas density of the porch of the Venturi tube(Unit is Kg/m3), gas viscosity(Unit is Pa/s), ρg1、μg1Respectively Calculated according to equation below:ρg1=P1M/RT1Wherein dgIt is that gas molecule is straight Footpath, tabling look-up to obtain.Wherein, coefficient a, b is determined as follows:Gathered using described solid flow continuous measurement system The test data of pure gas phase stream under two groups of difference operating modes, is designated as operating mode one, operating mode two respectively, and continuous in described solid flow A gas flowmeter is added on the input channel of measuring system, according to equationCalculate efflux coefficient C1、C2, wherein, Δ Pgas=P1-P2, ρgFor density of gas phase(Unit is Kg/m3), A2For the cross-sectional area at Venturi tube larynx section, A22A1, wherein A1For the cross-sectional area of Venturi tube contraction section porch;MgMeasured by the gas flowmeter;And calculating pair The reynolds number Re answered1、Re2, substitute into formula C=f (Re)=aRebIn coefficient a, b is calculated.
Similarly, to C ', there is also functional relation C '=f'(Re)=a'Reb', wherein coefficient a ', b ' determination method be same as above, The difference is that according to equationDuring calculating, Δ Pgas=P1-P3
M, m ' is sensitivity coefficient, and they are all the functions for correcting stokes number St, functional relation For formula:M=f (St)=cStd, wherein, amendment stokes number St calculates according to equation below:Wherein, dsIt is particle diameter(Unit is m), μg1It is venturi tube inlet gas Viscosity(Pa·s-1), LcAnd LtIt is the contraction section of the Venturi tube and the length of larynx section respectively(Unit is m);
Wherein, coefficient c, d is determined as follows:The work is gathered using described solid flow continuous measurement system The test data of two times condition one, operating mode gas-solid mixing stream, and on the input channel of described solid flow measuring system A gas flowmeter and a Weight-measuring device are added, according to formulaM and Z Equation.Wherein, Δ PgasIt is worth same formulaΔPmixComputational methods be same as above;According to Ms=ZMgCalculate Mass ratio Z, wherein MgValue is measured by the gas flowmeter, MsValue is measured by the Weight-measuring device, in formulaIn, two groups of m values are calculated, and according to amendment stokes number St calculation formula, calculate Go out two groups of St values, then substitute into formula m=f (St)=cStd, you can calculate coefficient c, d;
Similarly, to m ', there is also functional relation:M'=f'(St)=c'Std'.Coefficient c ', d ' determination method are same as above, The difference is that according to equationDuring calculating, Δ Pmix=P1-P3
Finally, the efflux coefficient for double pressure difference solid flow continuous measurement systems of long throat venturi that the present invention obtains with The functional relation of sensitivity coefficient is respectively C=f (Re)=14.07Re-0.185, m=f (St)=2.0St-1.29;C'=f' (Re)=194.72Re-0.36, m'=f'(St) and=1.3St-1.74.In discharge pressure 921KPa, concentration 326Kg/m3Under the conditions of, The parameter value that solid flow measuring system measures:P1=747KPa, P2=405KPa, P3=276KPa, T=293K, substitute into equation(8) Solid flow M can be calculatedsFor 936Kg/h.It is 938Kg/h to measure actual solid flow by weighing sensor, shows this The flow deviation that solid flow measuring system obtains is -0.22%, can preferably be applied to fine coal pressurization dense phase Geldart-D particle work Skill.
Embodiment 4
In the present embodiment, described fine coal pressurization dense phase pneumatic conveying process is as described in Example 3.Described fine coal it is dense Spend for 60Kg/m3, remaining test condition and method are the same as embodiment 3.As a result show, measured using the solid flow of the present invention and real The deviation of border solid flow is 5.88%.Illustrate that the present disclosure applies equally to the measurement of the solid flow of diluted phase transport process.
Effect example 1
In this effect example, described fine coal pressurization dense phase pneumatic conveying process is as described in Example 3.Pumped (conveying) medium coal The average grain diameter of powder is about 42 μm, and grain density is about 1400Kg/m3.The efflux coefficient of solid flow continuous measurement system and spirit The functional relation of sensitivity coefficient is respectively C=f (Re)=14.07Re-0.185, m=f (St)=2.0St-1.29;C'=f'(Re) =194.72Re-0.36, m'=f'(St) and=1.3St-1.74
Solid flow continuous measurement system is installed on the transfer pipeline of air-transport system, and pipe diameter D is 15mm.In solid flow continuous measurement system, input and output channel hair length are 100D;Venturi tube angle of throat θ is 5 °, is expanded Subtended angle α is 8 °, and larynx footpath d is 6mm, and larynx segment length Lt is 45d;Temperature sensor is apart from venturi tube inlet 5D;Pressure sensor P1Apart from venturi tube inlet 5D, P2And P3Respectively apart from Venturi tube larynx section entrance 22d and 40d.
Application effect of the solid flow continuous measurement system of the present invention in fine coal pressurization dense phase pneumatic conveying process is such as Shown in table 1.The present invention can preferably be applied to the Geldart-D particle solid flow of measurement concentration from low to high, and flow deviation is most Only within ± 5%, meet engineer applied requirement.Compared with the method for electronic scale weighing, the present invention can realize real-time continuous survey Amount, directly obtains instantaneous value;Compared with the method for import solid mass flow meter, the present invention have it is simple in construction, be easily installed, The advantages that being easy to maintenance, stable performance, economy and durability.
The measurement result of the effect example 1 of table 1

Claims (14)

1. the solid flow continuous measurement system of a kind of process of pneumatic transmission, it is characterised in that it includes an input channel, a text Venturi and an output channel;The input channel, the Venturi tube and the output channel are point-blank, described defeated The length for entering pipeline and the output channel is separately that D is the input channel and the output more than or equal to 80D The diameter of pipeline;Described Venturi tube includes a contraction section, a larynx section and the expansion segment being sequentially communicated, the input channel It is connected with the contraction section, the expansion segment is connected with the output channel;The length L of the larynx sectiontWith the larynx section The ratio between diameter d be more than or equal to 40;Described solid flow continuous measurement system also includes a first pressure tester, one the Two pressure testers, one the 3rd pressure tester and a temperature measuring set;Wherein, the first pressure tester is installed on described On input channel, the gaseous pressure P of the porch for measuring the contraction section1;The second pressure tester is installed on institute State in larynx section, the distance with the porch of the larynx section is 20d~40d, for measuring the gaseous pressure P at this2;Described 3rd Pressure tester is installed in the larynx section, and the distance with the porch of the larynx section is 40d~60d, for measuring at this Gaseous pressure P3;The temperature measuring set is installed on the input channel, the gas of the porch for measuring the contraction section Solid-state temperature T1
2. solid flow continuous measurement system as claimed in claim 1, it is characterised in that the angle of throat θ of described contraction section For 3~25;The angle of flare α of described expansion segment is 1~12 °;The Throttling ratio d/D of described Venturi tube is 0.3~0.8;Institute State the length L of larynx sectiontWith the ratio between the diameter d of larynx section Lt/ d is 40~80.
3. solid flow continuous measurement system as claimed in claim 2, it is characterised in that the angle of throat θ of described contraction section For 3~10.5 °;The angle of flare α of described expansion segment is 1~8 °;The Throttling ratio of described Venturi tube is 0.4~0.7.
4. solid flow continuous measurement system as claimed in claim 1, it is characterised in that the solid flow measuring system is also Including a data collecting system, the data collecting system is also connected with an A/D transition cards and a computer successively;Described first Pressure tester includes a first pressure sensor;The second pressure tester includes a second pressure sensor;Described Three pressure testers include one the 3rd pressure sensor;The temperature measuring set includes a temperature sensor;The first pressure Sensor, the second pressure sensor, the 3rd pressure sensor and the temperature sensor are adopted with the data respectively Collecting system is connected, and analog signal is inputted to the data collecting system.
5. solid flow continuous measurement system as claimed in claim 4, it is characterised in that the first pressure sensor is the One diaphragm type pressure sensor, and be installed on by one first tracting pressuring hole on the input channel;Along the Venturi tube On bearing of trend, the distance of first tracting pressuring hole and the porch of the contraction section is within 20D.
6. solid flow continuous measurement system as claimed in claim 5, it is characterised in that in the extension along the Venturi tube On direction, the distance of the porch of first tracting pressuring hole and the contraction section is within 5D.
7. solid flow continuous measurement system as claimed in claim 4, it is characterised in that the second pressure sensor is the Two diaphragm type pressure sensors, and be installed on by one second tracting pressuring hole in the larynx section of the Venturi tube.
8. solid flow continuous measurement system as claimed in claim 4, it is characterised in that the 3rd pressure sensor is the Three diaphragm type pressure sensors, and be installed on by one the 3rd tracting pressuring hole in the larynx section of the Venturi tube.
9. solid flow continuous measurement system as claimed in claim 4, it is characterised in that the temperature sensor is surveyed by one Warm hole is arranged on the input channel;The distance of the thermometer hole and the porch of the contraction section is within 20D.
10. solid flow continuous measurement system as claimed in claim 9, it is characterised in that the thermometer hole and the contraction The distance of the porch of section is within 5D.
11. a kind of solid flow measuring method of process of pneumatic transmission, described solid flow measuring method comprises the following steps:
(1) Dual-Phrase Distribution of Gas olid is passed through the solid flow continuous measurement system as described in claim any one of 1-7, and starts institute State solid flow continuous measurement system, measurement parameter P1、P2、P3And T1
(2) the parameter P for measuring step (1)1、P2、P3And T1Substitute into Venturi tube pressure drop equation group 1.:
The gas velocity V of contraction section porch can be calculatedg1With solid and gas mass ratio Z, then according to formulaCalculate to obtain gas phase flow rate Mg, then according to formula 2.:
Ms=ZMg
Further calculate to obtain solid flow Ms
Equation group 1. in, ρsFor solid Density, M is the molal weight of the gas molecule of gas phase, and R is mol gas constant, and β is text Venturi Throttling ratio, it is the larynx footpath d of the Venturi tube and the ratio between the diameter D of the input channel;
Equation group 1. in, C, C ' be efflux coefficient, they are all the functions of reynolds number Re, and C and Re functional relation are represented by Formula is 3.:
C=f (Re)=aReb
Formula 3. in, reynolds number Re calculates according to equation below:Re=DVg1ρg1g1, ρg1、μg1It is the Venturi tube respectively The gas density of porch, gas viscosity, ρg1、μg1Calculated respectively according to equation below:ρg1=P1M/RT1Wherein dgIt is gas molecule diameter, tabling look-up to obtain;
Formula 3. in, coefficient a, b are determined as follows:Two groups are gathered using described solid flow continuous measurement system not With the test data of pure gas phase stream under operating mode, operating mode one and operating mode two are designated as respectively, and continuously measure in described solid flow A gas flowmeter is added on the input channel of system, for measuring the flow mass M of gasg, according to equation 4.
The efflux coefficient C under operating mode one and operating mode two is calculated respectively1、C2, and reynolds number Re corresponding to calculating1、Re2, substitute into public Formula 3. in coefficient a, b is calculated;Equation 4. in, △ Pgas=P1-P2, ρgFor density of gas phase, A2At Venturi tube larynx section Cross-sectional area, A22A1, wherein A1For the cross-sectional area of Venturi tube contraction section porch;
Similarly, to C ' there is also functional relation 5.:
C '=f'(Re)=a'Reb'
Coefficient a ', b ' determination method are same as above, the difference is that when 4. being calculated according to equation, △ Pgas=P1-P3
Equation group 1. in, m, m ' be sensitivity coefficient, they are all the functions for correcting stokes number St, and functional relation is formula ⑥:
M=f (St)=cStd
Formula 6. in, amendment stokes number St calculated according to equation below:Its In, dsIt is particle diameter, μg1It is venturi tube inlet gas viscosity, LcAnd LtIt is the contraction section and larynx of the Venturi tube respectively The length of section;
Formula 6. in, coefficient c, d are determined as follows:The work is gathered using described solid flow continuous measurement system The test data of two times condition one, operating mode gas-solid mixing stream, and on the input channel of described solid flow measuring system A gas flowmeter and a Weight-measuring device are added, a m and Z equation is 7. obtained according to formula:
Formula 7. in, △ PgasIt is worth with formula 4., △ PmixComputational methods with formula 4.;Mass ratio Z is 2. calculated to obtain according to formula, Wherein MgValue is measured by the gas flowmeter, MsValue is measured by the Weight-measuring device, formula 7. in, calculate two groups of m Value, and according to amendment stokes number St calculation formula, two groups of St values are calculated, then substitute into formula 6., you can calculate and be Number c, d;
Similarly, to m ' there is also functional relation 8.:
M'=f'(St)=c'Std'
Coefficient c ', d ' determination method are same as above, the difference is that when 7. being calculated according to equation, △ Pmix=P1-P3
12. solid flow measuring method as claimed in claim 11, it is characterised in that described solid flow measuring method is fitted For the Geldart-D particle system under different pressures, various concentrations;The pumped (conveying) medium of described Geldart-D particle system is powder material; The gas medium of described Geldart-D particle system is compressed air, nitrogen or carbon dioxide.
13. solid flow measuring method as claimed in claim 12, it is characterised in that the conveying of described Geldart-D particle system Medium is coal dust, petroleum coke powder or biomass powder.
14. solid flow measuring method as claimed in claim 13, it is characterised in that defeated when described Geldart-D particle system When to send medium be coal dust, described solid flow measuring method is applied to 0~10MPa of pressure limit, 0~500Kg/ of concentration range m3Operating mode.
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