CN1186599C - Method for continuously measuring flow of bulk particles with UHF resonant cavity - Google Patents

Abstract

The present invention relates to the application that the microwave technology is applied to an electronic scale, particularly to a method for continuously measuring flow quantity of bulk material (medium) by a UHF resonant cavity, wherein a cylindrical metallic resonant cavity of which the center is provided with an opening is provided with a hollow medium tube; a speed sensor is arranged outside the medium tube. When the material, the filling density and the moisture content are different, the present invention measures the frequency bias delta f of the resonant cavity in advance, stores a list in a computer and completes the process of calibration and standardization so as to lead the bulk material to continuously pass through the hollow medium tube. When the present invention takes samples, the present invention reads out the frequency deviation delta f from the computer when the material passes through the resonant cavity, and reflects the weight of the bulk material in the medium tube at the moment after treatments of searching the list, etc. The method of the present invention has the advantages of high stability of measurement, easy adjustment, no maintenance, no nuclear radiation and high measuring precision (better than 0.5%).

Description

The method of ultrahigh frequency resonator cavity continuous coverage bulk material flow.

Affiliated technical field

The present invention is the application of microwave technology on electronic scales, the method that specifically to be a kind of use ultrahigh frequency resonator cavity carry out continuous coverage to the flow of bulk material (medium).

Background technology

At present, the measurement to pipe tobacco or offal flow generally all is to adopt electronic scales to carry out on the production of cigarettes.This method measurement stability is poor, it is big to be difficult for adjustment, maintenance and maintenance load.Recently, reported the method for two kinds of continuous coverage bulk material flows again: uclear scale method and publication number are the described method of Chinese patent file of CN118534A.The major defect of uclear scale method is that micro-nuclear radiation is arranged.The described method of CN118534A is divided into main channel and secondary channels with material, measures weight of material with lever scale on secondary channels, is a kind of contact type measurement, because the deviation between sample and the parent exists in measurement all the time, has reduced the precision of measuring.

Summary of the invention

The objective of the invention is to overcome the weakness of prior art, a kind of no nuclear radiation is provided, the heed contacted measure method that measurement stability is good, precision is high is promptly used the method for ultrahigh frequency resonator cavity continuous coverage bulk material (medium) flow.

By Theory of Electromagnetic Field as can be known, TM in the cylindrical metal resonator cavity 1 shown in Figure 1 _MnpThe field distribution and the resonance frequency of mould are respectively

E _z＝2E ₀J _m(k _cr)cos?mcos?βze? ^jωt

H _z＝0

$f_{\mathrm{mnp}}=\frac{c}{\sqrt{{\mathrm{\ϵ}}_r{\mathrm{\μ}}_r}}\frac{1}{2\mathrm{\π}}\sqrt{({\left(\frac{\mathrm{p\π}}{l}\right)}^2+{\left(\frac{x_{\mathrm{mn}}}{a}\right)}^2)}$

$k_c=\frac{x_{\mathrm{mn}}}{a}\left[\begin{array}{c}m=\mathrm{0,1,2}...\\ n=\mathrm{0,1,2}...\end{array}\right]$

In the following formula: x _MnBe m rank Bessel's function J _m(x) n root; M, n and p are respectively the half-wave number of electromagnetic field along cylindrical coordinate φ, r and the variation of z axle; f _MnpResonance frequency for the cylindrical metal resonator cavity; μ _rRelative permeability for medium in the chamber; ε _rRelative dielectric constant for medium in the chamber; L is the height of cylindrical metal resonator cavity; A is the radius of cylindrical metal resonator cavity.Select the main mould pattern TM of cylindrical metal resonator cavity ₀₁₀, can meet design requirement.

If on wire chamber shown in Figure 1, open hole, a garden, insert medium tube in the hole, garden, and in medium tube, put into bulk material, as pipe tobacco or offal.Because the bulk material in the medium tube is the potpourri of water, clearance and pipe tobacco or offal, the bulk material equivalent relative dielectric constant is ε _r, and

${\mathrm{\ϵ}}_r=\underset{i}{\mathrm{\Σ}}{\mathrm{\ϵ}}_{\mathrm{ri}}{\mathrm{\α}}_i={\mathrm{\ϵ}}_{r1}{\mathrm{\α}}_1+{\mathrm{\ϵ}}_{r2}{\mathrm{\α}}_2+{\mathrm{\ϵ}}_{r3}{\mathrm{\α}}_3$

ε in the following formula _R1, ε _R2And ε _R3Be respectively the relative dielectric constant of water, clearance and pipe tobacco or offal; α ₁, α ₂And α ₃Be respectively the percent by volume of water, clearance and pipe tobacco or offal.

Theoretical analysis shows: the main mould TM of cylindrical metal resonator cavity 1 ₀₁₀Resonance frequency be

$f_0=\frac{2.405c}{2\mathrm{\πa}}$

C is the light velocity in the following formula; A is the radius of cylindrical metal resonator cavity.If on the cylindrical metal resonator cavity, open hole, a garden, and in the hole, garden, insert the medium tube of filling full bulk material (as pipe tobacco or offal), see shown in Figure 2.Perturbation theory by resonator cavity is known, compares with empty resonator cavity, and this moment, the resonance frequency of resonator cavity was changed to Δ f,

And

$\frac{\mathrm{\Δf}}{f_0+\mathrm{\Δf}}=\frac{\underset{\mathrm{\Δv}}{\∫\∫\∫}(\mathrm{\Δ\ϵE}{E}_0^{*}+\mathrm{\Δ\μH}{H}_0^{*})\mathrm{dv}}{\underset{v}{\∫\∫\∫}(\mathrm{\ϵE}{E}_0^{*}+\mathrm{\μH}{H}_0^{*})\mathrm{dv}}$

Δ v is the volume of interior medium tube of cylindrical metal resonator cavity and bulk material in the following formula; Electromagnetic field after the perturbation in the resonator cavity is E and H, and specific inductive capacity in the resonator cavity and magnetic permeability variation are respectively Δ ε and Δ μ; The volume of remaining space is v in the resonator cavity; Electromagnetic field before the perturbation in the resonator cavity is E ₀ ^*And H ₀ ^*, specific inductive capacity and magnetic permeability in the resonator cavity are respectively ε and μ.Be resonance frequency the f (=f of cylindrical metal resonator cavity ₀+ Δ f) with bulk material equivalent relative dielectric constant ε in the chamber _rIncrease and reduce.

Experimental result is as follows: under experiment condition shown in Figure 2, the radio frequency network analyser 8712ET measurement result of producing with U.S. Agilent company shows, during the empty medium tube of insertion in the hole, wire chamber garden in, and the resonance frequency f of cylindrical metal resonator cavity _o=250Mhz; (the pipe tobacco volume accounts for medium tube inner volume about 60% to fill bulk material in the medium tube, the clearance volume is about 40%, pipe tobacco water cut 12%) after, the resonator cavity resonance frequency is f=244Mhz, be that resonator cavity resonance frequency variation (Δ f) scope equals 6Mhz, experimental result is seen shown in Figure 3; When the pipe tobacco volume accounted for the medium tube inner volume than variation or pipe tobacco change of moisture content, the resonator cavity resonance frequency also changed.Be the variation of the variation of bulk material and composition ratio and water cut corresponding to resonator cavity resonance frequency f, consistent with notional result.

On the other hand, when the given volume of bulk material, through proving the percent by volume of the weight of bulk material behind the experiment measuring corresponding to bulk material, water and air gap.So the variation of cylindrical metal resonator cavity/resonance frequency f corresponding to the weight change of bulk material, promptly can be used for measuring the weight of bulk material after the calibration calibration.Increase a real-time continuous again and measure the speed pickup of bulk material flow velocity, get final product the flow of continuous coverage bulk material (medium).The calibration calibration process is as follows: when static, the frequency deviation Δ f of resonator cavity measures during to different pipe tobaccos or offal, different packed density and different moisture content, and tabulation deposits computing machine in, finishes the calibration calibration process; During successive dynamic measuring,, after processing such as table look-up, promptly know the weight of pipe tobacco in this moment medium tube or offal at the frequency deviation Δ f of the resonance frequency of sampling when constantly computing machine is read streams through resonator cavity from the RS-232 mouth.

The inventive method is as follows:

1, in the cylindrical metal resonator cavity of middle perforate a hollow medium tube is set, medium tube peripheral hardware speed sensor,

The frequency deviation Δ f of resonator cavity measures during 2, in advance to different material, different packed density and different moisture content, and tabulation deposits computing machine in, finishes the calibration calibration process;

3, make the bulk material continuous stream cross the hollow medium tube, the frequency deviation Δ f when sampling is constantly read streams through resonator cavity from computing machine promptly knows the weight of bulk material in this moment medium tube after processing such as table look-up.

According to top method, this professional those of ordinary skill just can be implemented the technology of the present invention, realizes goal of the invention.

Advantage of the present invention:

Compare good, the easy adjustment of measurement stability of the present invention, non-maintaining with electronic scales;

Compare with uclear scale, the present invention does not have nuclear radiation;

With publication number be the method introduced of the patent of invention of CN118534A relatively, the present invention is a kind of heed contacted measure, good, the easy adjustment of measurement stability, non-maintaining, measuring accuracy height (being better than 5/1000ths).

Description of drawings

Fig. 1 is cylindrical metal resonator cavity and coordinate system thereof.

Fig. 2 is provided with the cylindrical metal resonator cavity of a hollow medium tube in being.

Fig. 3 is the measurement result under experiment condition shown in Figure 2

Apparatus structure synoptic diagram among Fig. 4 embodiment.

Circuit block diagram among Fig. 5 embodiment.

Embodiment

Seeing Figure 4 and 5, is the method embodiment of a usefulness ultrahigh frequency resonator cavity continuous coverage pipe tobacco or offal flow.The height of cylindrical metal resonator cavity 3 is 200mm, and radius is 450mm, and material is a stainless steel.The length of hollow medium tube 4 is 900mm, and internal diameter is 140mm, and wall thickness is 10mm, and material is a pvc pipe.Speed pickup 5 is the microwave Doppler speed pickup.Magnetic couple cyclization 6 is the round ring of radius 50mm, is the copper cash coiling of 3mm with diameter.The flow direction of pipe tobacco or offal when Fig. 4 hollow core arrow is represented to measure.

Among this embodiment, the ultrahigh frequency resonant circuit contains the ultrahigh frequency resonator cavity, high performance filter, amplifier, automatic gain controller and automatic phase-shift controller.

Above embodiment only is described further invention, and scope of the present invention is not subjected to the limitation of illustrated embodiment.

Claims (6)

1, a kind of method of ultrahigh frequency resonator cavity continuous coverage bulk material flow, it is characterized in that employed device comprises that the ultrahigh frequency resonant circuit that contains the ultrahigh frequency resonator cavity, intelligent frequency meter, real-time continuous measure the speed pickup and the computing machine of the flow velocity of bulk material, the cylindrical metal resonator cavity that said ultrahigh frequency resonator cavity is middle perforate, one hollow medium tube is set in this cylindrical metal resonator cavity, said speed pickup is arranged on outside this medium tube, and this method comprises following step:

The frequency deviation Δ f of resonator cavity measures during (1) in advance to different material, different packed density and different moisture content, and tabulation deposits computing machine in, finishes the calibration calibration process,

(2) make the bulk material continuous stream cross the hollow medium tube, the frequency deviation Δ f when sampling is constantly read streams through resonator cavity from computing machine learns the weight of bulk material in this moment medium tube after data processing,

(3) flow that calculates bulk material according to the flow velocity and the described weight of speed pickup measurement.

2,, it is characterized in that said bulk material is pipe tobacco or offal as the said method of claim 1.

3,, it is characterized in that reading the frequency deviation Δ f of the resonance frequency of streams when the resonator cavity from computing machine RS-232 mouth as the said method of claim 1.

4,, it is characterized in that speed pickup is the microwave Doppler speed pickup as the said method of claim 1.

5,, it is characterized in that said ultrahigh frequency resonant circuit also comprises high performance filter, amplifier, automatic gain controller and automatic phase-shift controller as the said method of claim 1.

6,, it is characterized in that the hollow medium tube is a pvc pipe as the said method of claim 1.

Images