CN102360024A - Paper pulp flow velocity and flow measuring method - Google Patents

Paper pulp flow velocity and flow measuring method Download PDF

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Publication number
CN102360024A
CN102360024A CN 201110245185 CN201110245185A CN102360024A CN 102360024 A CN102360024 A CN 102360024A CN 201110245185 CN201110245185 CN 201110245185 CN 201110245185 A CN201110245185 A CN 201110245185A CN 102360024 A CN102360024 A CN 102360024A
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China
Prior art keywords
paper pulp
concentration
concentration sensor
flow velocity
flow
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CN 201110245185
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Chinese (zh)
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周强
任鹏
王莹
袁文婷
徐立鑫
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Shaanxi University of Science and Technology
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Shaanxi University of Science and Technology
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Priority to CN 201110245185 priority Critical patent/CN102360024A/en
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Abstract

The invention relates to a paper pulp flow velocity and flow measuring method. According to the method, two concentration sensors which are in series connection in a pipeline are utilized to measure paper pulp concentration and calculate a paper pulp flow velocity simultaneously. Since a paper pulp concentration signal has fluctuation and continuity of fluctuation, through carrying out a cross correlation analysis on concentration signals outputted by the two concentration sensors, a present paper pulp flow velocity and flow can be accurately calculated. The method in the invention has high measuring precision.

Description

The measuring method of a kind of paper pulp flow velocity and flow
Technical field
The present invention relates to light industry and field of measuring technique, relate in particular to the measuring method of a kind of paper pulp flow velocity and flow.
Background technology
In paper industry; The speed flowrate of paper pulp is to measure maximum physical quantitys; The measurement of paper pulp flow velocity is all significant for nearly all links such as the making beating on the paper production line, pulp washing, metering, stir-fry paper; At present, several different methods such as electromagnetic flowmeter, Digital image technology (DIT), ultrasonic pulse Doppler method (PUD), nuclear magnetic resonance (NMR) method are used to the measurement of paper pulp flow velocity.But; Use maximum electromagnetic flowmeter survey precision to hang down in the production and only can reach 1%; Ultrasonic pulse Doppler method (PUD) only is suitable for the measurement of low concentration (0.5%), and Digital image technology (DIT) is inappropriate for online use, and the price of nuclear magnetic resonance (NMR) method is too expensive.Therefore, above method all discomfort be combined into paper production line standard paper pulp flow velocity be provided.
In paper; Pulp density is measured next in number only to the paper pulp flow velocity, and these two parameters are often measured simultaneously, and the measuring technique of pulp density is quite ripe; Therefore on the basis of original 1 concentration sensor, add the high-acruracy survey that 1 concentration can be used for the paper pulp flow velocity again.
Summary of the invention
The object of the present invention is to provide and a kind ofly can accurately measure the paper pulp flow velocity of paper pulp real-time flow rate and flow and the measuring method of flow.
For achieving the above object, the present invention provides the measuring method of a kind of paper pulp flow velocity and flow, and described measuring method is carried out according to following steps:
Step 1): obtain the sampled concentrations signal C that disperses respectively through being arranged on the first adjacent concentration sensor and second concentration sensor on the paper pulp pipeline A(n) and C B(n); Wherein n represent time t discrete magnitude (n=1,2 ... N), C A(n) concentration value of representing first densimeter to measure constantly at n, C B(n) represent second densimeter n measure constantly concentration value;
Step 2): according to formula (1) and (2) difference calculating sampling concentration signal C A(n) and C B(n) DFT C A(k), C B(k):
C A(k)＝FFT[C A(n)] (1)；
C B(k)＝FFT[C B(n)] (2)；
Wherein k is a discrete frequency, represents the discrete magnitude of frequency spectrum independent variable;
Step 3): according to formula (3), by step 2) C that obtains A(k), C B(k) calculate the power spectrum S that adopts concentration signal AB(k):
S AB ( k ) = C A ( k ) C ‾ B ( k ) N - - - ( 3 ) ;
Step 4): according to formula (4), through power spectrum S AB(k) inverse discrete Fourier transformer inverse-discrete is calculated C A(n), C B(n) related function R AB(τ):
R AB(τ)＝IFFT|S AB(k)| (4)；
Step 5): obtain R according to formula (5) ABMaximal value R (τ) ABmax(τ) and corresponding transit time τ,
R ABmax(τ)＝max[R AB(τ)] (5)；
Wherein transit time τ is that paper pulp flows to the used time of densimeter B by densimeter A in the pipeline;
Step 6):, can obtain paper pulp real-time flow rate v with τ substitution formula (6); τ substitution formula (2) can be obtained paper pulp real-time traffic F:
v = L τ - - - ( 6 ) ;
F = LS τ - - - ( 7 ) ;
Wherein L is the duct length between adjacent two concentration sensors; S is the cross-sectional area of pipeline.
Preferably, the front and back of said adjacent two concentration sensors should have 1 meter straight pipeline at least.
Preferably, the duct length L between said adjacent two concentration sensors satisfies: 1m＜L＜2.5m.
The measuring method of paper pulp flow velocity of the present invention and flow utilizes two concentration sensors that are connected on the pipeline when measuring pulp density, to calculate the paper pulp flow velocity.Because the pulp density signal has the continuation of undulatory property and fluctuation, carry out cross-correlation analysis through concentration signal to two concentration sensor outputs, can accurately calculate current paper pulp flow velocity.This method obtains paper pulp stream through the fixed range required time through the cross-correlation analysis to the pulp density signal, and then obtains the real-time flow rate of paper pulp.Method of the present invention has the advantage of measuring accuracy high (measuring accuracy can reach 0.2%), not only can be used for industry spot, can also be used to demarcate other sensor as a kind of proving flowmeter.
Description of drawings
Fig. 1 is the schematic diagram of the measuring method of paper pulp flow velocity according to the invention and flow;
Fig. 2 is the analysis chart of pulp density of the measuring method of paper pulp flow velocity and flow; Wherein figure (a) is the concentration signal C of concentration sensor 1 output among Fig. 1 AOscillogram; Figure (b) is the concentration signal C of concentration sensor 2 outputs among Fig. 1 BOscillogram; Figure (c) is to concentration signal C AAnd C BThe analysis result synoptic diagram.
Embodiment
Please with reference to Fig. 1, whole measuring system comprises that being installed in distance on the paper pulp pipeline is first concentration sensor 1, second concentration sensor 2 of L and the secondary instrument 3 that is connected with second concentration sensor 2 with first concentration sensor 1.Because it is very high that method of the present invention requires the arithmetic capability of microprocessor, so secondary instrument 3 is a core with DSP.The front and back of first concentration sensor 1 and second concentration sensor 2 should have 1 meter straight pipeline at least.Duct length L between first concentration sensor 1 and second concentration sensor 2 satisfies: 1m≤L≤2.5m.
The measuring method of paper pulp flow velocity according to the invention and flow, carry out according to following steps:
The first step: first concentration sensor and second concentration sensor are arranged on the paper pulp pipeline apart from certain distance, obtain the sampled concentrations signal C that disperses through this first concentration sensor and second concentration sensor respectively A(n) and C B(n).Wherein n represent time t discrete magnitude (n=1,2 ... N), C A(n) concentration value of representing first concentration sensor to measure constantly at n, C B(n) concentration value of representing second concentration sensor to measure constantly at n.
Second step: according to formula (1) and (2) difference calculating sampling concentration signal C A(n) and C B(n) DFT C A(k), C B(k):
C A(k)＝FFT[C A(n)] (1)；
C B(k)＝FFT[C B(n)] (2)；
Wherein k is a discrete frequency, represents the discrete magnitude of frequency spectrum independent variable.
The 3rd step: according to formula (3), by step 2) C that obtains A(k), C B(k) calculate the power spectrum S that adopts concentration signal AB(k):
S AB ( k ) = C A ( k ) C ‾ B ( k ) N - - - ( 3 ) .
The 4th step: according to formula (4), through power spectrum S AB(k) inverse discrete Fourier transformer inverse-discrete is calculated C A(n), C B(n) related function R AB(τ):
R AB(τ)＝IFFT|S AB(k)| (4)。
The 5th step: obtain R according to formula (5) ABMaximal value R (τ) ABmax(τ) and corresponding transit time τ,
R ABmax(τ)＝max[R AB(τ)] (5)；
Wherein transit time τ is that paper pulp flows to the used time of densimeter B by densimeter A in the pipeline.
The 6th step:, can obtain paper pulp real-time flow rate v with τ substitution formula (6); τ substitution formula (7) can be obtained paper pulp real-time traffic F:
v = L τ - - - ( 6 ) ;
F = LS τ - - - ( 7 ) ;
Wherein L is the duct length between adjacent two concentration sensors; S is the cross-sectional area of pipeline.
Theoretical foundation of the present invention is:
1. the pulp density signal c (t) of concentration sensor output comprises mean concentration signal d (t), system noise s (t) and measurement noise v (t) two parts, can be expressed as formula (8):
c(t)＝d(t)+s(t)+v(t) (8)；
Because the existence of s (t) makes the pulp density signal have undulatory property.
2. the fluctuation pattern of pulp density can exist in the paper pulp pipeline for a long time, and is visible by Fig. 2, and Fig. 2 (b) is the concentration signal C of second concentration sensor, 2 outputs BOscillogram; Fig. 2 (a) is the concentration signal C of first concentration sensor, 1 output AOscillogram.Fig. 2 (b) and Fig. 2 (a) are compared the concentration signal C that can know 2 outputs of second concentration sensor BConcentration signal C with first sensor output AHave identical wavy shape, the time τ that just lagged behind, and τ just paper pulp stream through two times that concentration sensor is used, i.e. transit time.τ can obtain through correlation analysis.By the visible C of Fig. 2 (c) AAnd C BCross correlation function R ABPeak value moment corresponding τ (τ) is the transit time of paper pulp just.In transit time substitution formula (6) and (7):
v = L τ - - - ( 6 ) ;
F = LS τ - - - ( 7 ) ;
Can calculate the flow velocity v and the flow F of paper pulp, wherein S is the cross-sectional area of pipeline.
Be to use the method for this patent to measure a specific embodiment of the paper pulp flow velocity on the production line below, in the present embodiment, first concentration sensor and second concentration sensor are the XDBN-1000 concentration sensor, and the measurement of concetration precision is 0.5%.Distance between this two concentration sensor is 1.5 meters.True paper pulp flow velocity in this paper pulp pipeline is 0.8167m/s.According to transit time τ=1.8337m that this patent method is surveyed, calculating the paper pulp flow velocity is 0.8181m/s, and measuring error is 0.17%.And according to the method for testing of prior art, the flow that uses electromagnetic flowmeter to record is 25.4466L/s, and being converted into flow velocity is 0.8104m/s, and measuring error is 0.65%.Can know from contrast, use the measuring accuracy of the method for this patent to be higher than the data of using electromagnetic flowmeter to record far away.

Claims (3)

1. the measuring method of paper pulp flow velocity and flow, it is characterized in that: described measuring method is carried out according to following steps:
Step 1): first concentration sensor and second concentration sensor are arranged on the paper pulp pipeline apart from certain distance, obtain the sampled concentrations signal C that disperses through this first concentration sensor and second concentration sensor respectively A(n) and C B(n); Wherein n represent time t discrete magnitude (n=1,2 ... N), C A(n) concentration value of representing first concentration sensor to measure constantly at n, C B(n) concentration value of representing second concentration sensor to measure constantly at n;
Step 2): secondary instrument receives the sampled concentrations signal C that is obtained by step 1) A(n) and C B(n), according to formula (1) and (2) difference calculating sampling concentration signal C A(n) and C B(n) DFT C A(k), C B(k):
C A(k)＝FFT[C A(n)] (1)；
C B(k)＝FFT[C B(n)] (2)；
Wherein k is a discrete frequency, represents the discrete magnitude of frequency spectrum independent variable;
Step 3): according to formula (3), by step 2) C that obtains A(k), C B(k) calculate the power spectrum S that adopts concentration signal AB(k):
S AB ( k ) = C A ( k ) C ‾ B ( k ) N - - - ( 3 ) ;
Step 4): according to formula (4), through power spectrum S AB(k) inverse discrete Fourier transformer inverse-discrete is calculated C A(n), C B(n) related function R AB(τ):
R AB(τ)＝IFFT|S AB(k)| (4)；
Step 5): obtain R according to formula (5) ABMaximal value R (τ) ABmax(τ) and corresponding transit time τ,
R ABmax(τ)＝max[R AB(τ)]?(5)；
Wherein transit time τ is that paper pulp flows to the used time of densimeter B by densimeter A in the pipeline;
Step 6):, can obtain paper pulp real-time flow rate v with τ substitution formula (6); τ substitution formula (2) can be obtained paper pulp real-time traffic F:
v = L τ - - - ( 6 ) ;
F = LS τ - - - ( 7 ) ;
Wherein L is the duct length between adjacent two concentration sensors; S is the cross-sectional area of pipeline.
2. the measuring method of paper pulp flow velocity according to claim 1 and flow is characterized in that: the front and back of first concentration sensor and second concentration sensor should have 1 meter straight pipeline at least.
3. the measuring method of paper pulp flow velocity according to claim 1 and flow is characterized in that: the duct length L between first concentration sensor and second concentration sensor satisfies: 1m≤L≤2.5m.
CN 201110245185 2011-08-24 2011-08-24 Paper pulp flow velocity and flow measuring method Pending CN102360024A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103630175A (en) * 2013-12-16 2014-03-12 云南大学 Three-stage ring-shaped flexible chain-shaped related rapid-flow measuring device
CN105403268A (en) * 2015-12-15 2016-03-16 陕西科技大学 Slurry type fluid high-precision flow measuring device and method
CN105698881A (en) * 2016-03-15 2016-06-22 江苏华海测控技术有限公司 High-precision electromagnetic flowmeter based on fast Fourier transform

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1139209A (en) * 1995-06-29 1997-01-01 江苏省镇江船厂 Fluid-detecting measuring device
CN1229157A (en) * 1999-04-07 1999-09-22 中国计量科学研究院 Instrument for measuring and controlling wood pulp concentration

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1139209A (en) * 1995-06-29 1997-01-01 江苏省镇江船厂 Fluid-detecting measuring device
CN1229157A (en) * 1999-04-07 1999-09-22 中国计量科学研究院 Instrument for measuring and controlling wood pulp concentration

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
《中国造纸》 20051231 周强等 基于互相光理论的纸浆流量测定新方法 第29-33页 1-3 第24卷, 第7期 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103630175A (en) * 2013-12-16 2014-03-12 云南大学 Three-stage ring-shaped flexible chain-shaped related rapid-flow measuring device
CN103630175B (en) * 2013-12-16 2016-04-20 云南大学 A kind of three-level annular flexible chain is correlated with torrent current surveying device
CN105403268A (en) * 2015-12-15 2016-03-16 陕西科技大学 Slurry type fluid high-precision flow measuring device and method
CN105403268B (en) * 2015-12-15 2018-10-16 陕西科技大学 A kind of the high-precision flow measuring device and method of slurry type fluid
CN105698881A (en) * 2016-03-15 2016-06-22 江苏华海测控技术有限公司 High-precision electromagnetic flowmeter based on fast Fourier transform

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Application publication date: 20120222