CN201191270Y - Measurement apparatus for reconstructing fume concentration temperature distribution by relative spiral motion of laser - Google Patents

Abstract

The utility model relates to a measuring system of three dimensional space distribution of the concentration and the temperature of smoke, and aims to provide a measuring device of space distribution of the concentration and the temperature of the smoke which is reconstructed by a laser which spirally moves relatively. The measuring device comprises a signal generator, a laser source and an optical fiber output end, and further comprises a beam shaping lens which is arranged at the edge of an electric rotating platform, a focusing cylinder mirror is located at the edge of the other side of the electric rotating platform corresponding to the beam shaping lens, the electric rotating platform is parallel to the cross section of a smoke passage, the electric rotating platform and the smoke passage have a same rotating axle center, and the focusing cylinder mirror is sequentially connected with a linear transducer array and a computer via signal wires. The measuring device of the utility model can realize three-dimensional reconstruction to the concentration and the temperature of gas with certain volume passing through a measuring cross section in a short time, realize the three-dimensional reconstruction only through program calculation, which is low in system cost and simple in operation, and can three-dimensionally measure various gas.

Description

The measurement mechanism of flue gas concentration Temperature Distribution is rebuild in the relative helical motion of laser instrument

Technical field

The utility model relates to the measuring system of a kind of flue gas concentration and three dimension temperature space distribution.More particularly, the utility model relates to the measurement mechanism that flue gas concentration and temperature space distribution are rebuild in the relative helical motion of a kind of laser instrument.

Background technology

The flue gas on-line dynamic measurement has great importance to environmental protection and pollution control.The kinetic measurement of flue gas can on the other hand, also be the important means of research pollutant formation mechanism and control technology for environment monitoring department provides direct Monitoring Data on the one hand.Simultaneously, the dynamic monitoring of flue gas also is in process of production pollutant to be generated the prerequisite control, production run is optimized and adjusts.

Traditional gas measurement device, as utilize chemiluminescence principle or heat-conducted gas tester, need take a sample to gas, can't realize the gas in the process is carried out the online in real time Testing requirement.Therefore, adopting method optics, contactless to carry out the measurement of gas, thereby realize controlling to the monitoring of pollutant with to generative process, is the difficult point and the focus of combustion testing area research.After the nineties, because the fast development of optical information technology, some key componentses such as semiconductor laser and fiber optic component development are rapid, and performance improves greatly, and price declines to a great extent.The semiconductor laser of working and room temperature, long-life, unimodular property and broad wavelength tuning range can obtain from the commercial channel, and some highly sensitive spectral techniques (as wavelengthmodulation spectroscopy) are also ripe gradually, and tunable semiconductor laser absorption spectrum technology (Tunable diode laser absorption spectroscopy) beginning is applied to science and engineering research morely.When the laser beam that semiconductor laser is launched the specific wavelength of " narrow linewidth " is passed tested gas, tested gas absorbs laser beam and causes laser intensity to produce decay, the decay of laser intensity is directly proportional with tested gas content, therefore, just can analyze concentration and the temperature information that obtains tested gas by Laser Measurement strength retrogression information.

Present measurement is mostly carried out on single light path, and measurement result is the mean value on the light path, and can't know inner concrete distribution.Along with in a large amount of widespread uses of computer tomography technology (Computed Tomography) in medical diagnosis and industrial lossless detection field, make gas concentration and the Temperature Distribution of utilizing optical technology to rebuild in the flue become possibility.But for three-dimensional measurement, adopt chromatography imaging method that different cross section is measured respectively, accumulate the method for three-dimensional data again,, also lack real-time for dynamic combustion process.The utility model adopts detector around tested mobile flue gas rotation, can realize the space three-dimensional of one section flue gas is measured at a swing circle of laser instrument, and such measuring system yet there are no report.

The utility model content

The purpose of this utility model is to overcome deficiency of the prior art, provides the relative helical motion of a kind of laser instrument to rebuild the measurement mechanism of flue gas concentration Temperature Distribution.

In order to solve the problems of the technologies described above, the utility model is achieved through the following technical solutions.

The measurement mechanism of flue gas concentration Temperature Distribution is rebuild in the relative helical motion of a kind of laser instrument, comprise signal generator, lasing light emitter and fiber-optic output, also comprise the beam shaping lens of being located at the electric rotary table edge, focus on cylindrical mirror and be positioned at and the corresponding electric rotary table opposite side of beam shaping lens edge; The transverse cross-section parallel of electric rotary table and flue, electric rotary table and flue have same axis of rotation; Focusing on cylindrical mirror is connected with computing machine with linear array detector successively by signal wire.

As a kind of improvement of the present utility model, there is a universal stage controller to be connected with electric rotary table.

Compared with prior art, the beneficial effects of the utility model are:

(1) uses device of the present utility model, the characteristics of utilizing flue gas in flue, to flow, make the laser flue gas of shape scanning certain-length in the shape of a spiral, be implemented in the short time (usually less than 1 second) three-dimensional reconstruction through the gas concentration temperature of the certain volume of measuring the cross section.

(2) use device of the present utility model, need not mobile laser instrument-detector cross section, only calculate and realize three-dimensional reconstruction by program, system cost is low, and the operation operation is simple.

(3) by increasing or changing laser diode, can be to various gas (as O ₂, H ₂O, CO, CO ₂, NO, NO ₂, NH ₃, HF, H ₂S and CH ₄Deng) carry out three-dimensional measurement.

Description of drawings

Fig. 1 is the structural representation of measuring system in the utility model;

Fig. 2 is the facade structures synoptic diagram of measuring system in the utility model;

Fig. 3 is the synoptic diagram of laser scanning implementation in the utility model.

Embodiment

With reference to the accompanying drawings, will be described in detail the utility model below.

The measurement mechanism of flue gas concentration Temperature Distribution is rebuild in the relative helical motion of a kind of laser instrument, comprise signal generator 1, lasing light emitter 2 and fiber-optic output 3, also comprise the beam shaping lens 4 of being located at electric rotary table 10 edges, focus on cylindrical mirror 6 and be positioned at and beam shaping lens 4 corresponding electric rotary tables 10 opposite side edges.The transverse cross-section parallel of electric rotary table 10 and flue 5, electric rotary table 10 has same axis of rotation with flue 5, has a universal stage controller 9 to be connected with electric rotary table 10.Focusing on cylindrical mirror 6 is connected with computing machine 8 with linear array detector 7 successively by signal wire.

The step of utilizing above-mentioned measurement mechanism and spiral CT principle to rebuild gas concentration and three dimension temperature distribution is:

(1) utilize 4 pairs of laser signals of beam shaping lens to carry out shaping and make it to form fan-shaped sheet type hot spot, fan-shaped sheet type hot spot pass axial flue 5 and with flue 5 transverse cross-section parallel;

(2) make beam shaping lens 4 do circle-shaped rotation around the axle center of flue 5;

(3) utilize flue 5 opposite sides and beam shaping lens 4 corresponding focusing cylindrical mirrors 6 to converge laser signal, and by linear array detector 7 measuring-signal is sent to computing machine 8 and obtains data for projection on the fault plane; Obtain the projected dataset of 360 ° rebuilding plane of a constant position with the projected dataset of 360 ° of two continuous rotations; This rebuilding plane is positioned at the centre of twice rotation, and perpendicular to turning axle; Utilize the projected dataset of 360 ° of two continuous rotations, obtain the required projection value of rebuilding plane between the data for projection under the same angle, carrying out linear interpolation according to interpolation formula;

(4), obtain gas concentration and three dimension temperature distributed data according to the image reconstruction of reconstruction algorithm to flue gas concentration and temperature.

Detailed process is: the optical fiber that passes through of lasing light emitter 2 is connected on the electric rotary table 10, and its Wavelength of Laser and sweep limit thereof are regulated by the voltage signal that is carried on the laser controller.The laser signal of output carries out shaping by beam shaping lens 4, makes it to form a fan-shaped sheet type hot spot, thereby covers the zone, outlet of flue 5.The hot spot of dispersing of transmission converges by focusing on cylindrical mirror 6, and is finally received by linear array detector 7, by data processing and analog to digital conversion, is finally handled by computing machine 8.During measurement, electric rotary table 10 carries out 360 ° of rotations, thereby makes linear array detector 7 to obtain data for projection in all angles, and finally utilizes the CT technology to reconstruct image.

But in electric rotary table 10 rotations, flue gas also will axially be moved, so the data for projection that obtains in all scopes is not positioned on the same cross section, scan around flue gas twist but be equivalent to laser, as shown in Figure 3.

Because the data of spiral CT are to obtain when Z-direction moves in Measuring Object, therefore except the projection of a direction just in time is on the rebuilding plane, the data for projection that other directions collect is then in the both sides of rebuilding plane, promptly on any one fault plane, only obtained the part data for projection.If can obtain the whole data for projection on a fault plane, so just can utilize the reconstruction algorithm of traditional CT to rebuild.The utility model adopts the data processing method of spiral CT, utilizes the data for projection that obtains in rotary course to carry out 360 ° of interpolations.Estimate 360 ° projected dataset with two 360 ° projected dataset a constant position.Rebuilding plane is positioned at the middle of twice rotation, and perpendicular to turning axle.Carry out linear interpolation between the data for projection under the same angle, interpolation formula is:

P′(L，M)＝wP(L，M)+(1-w)P(L，M+2π) (1)

In the formula: P (L, M) for position number is L, the rotation number of degrees are the projection value at M place; P (L, M+2 π) is for position number is L, the projection value when the rotation number of degrees are M+360 °; P ' (L, M) for position number be between twice projected dataset at L place projection value, w is an interpolation coefficient.Promptly come interpolation to obtain other projection value by the projection value that utilizes two anglecs of rotation to differ 360 °.

Like this, all data for projection are converted on the same rebuilding plane, just can find the solution according to the tomographic reconstruction algorithm.Reconstruction algorithm is broadly divided into two classes: converter technique-come reconstructed image with given a series of analytic expressions (operator or functional transformation) inversion formula, thunder commonly used are stepped on (Randon) invert discrete form of formula, as filtered back projection (FBP) algorithm; Another kind of is Series Expansion Method-directly to formula " discretize ", obtain a large-scale sparse linear system of equations, as algebraic reconstruction (ART) algorithm.ART algebraic reconstruction algorithm is simple, is applicable to that the sampled data of different-format is rebuild; Can also find the solution in conjunction with some prioris in addition.Therefore rebuilding for the gas parameter in the flue adopts ART algebraically iterative algorithm to realize.

Algebraic reconstruction technique is the process of an iteration, and it carries out in discrete domain at the very start.At first the problem discretize, be about to the unknown images f (x that desire is rebuild, y) be separated into a n * n=N reconstructed image grid, physical process and corresponding mathematical model according to imaging, set up the Algebraic Equation set that concerns between reconstructed image and the data for projection, the image reconstruction problem just is converted into separates system of linear equations.

For utilizing the tunable semiconductor LASER Light Source to carry out gasmetry, its ultimate principle is according to the Beer-Lambert law:

$\frac{I_t}{I_0}=\exp (-\mathrm{PS}\left(T\right)\mathrm{\φXL})---\left(2\right)$

In the formula: P[atm] be the stagnation pressure of gas; L[cm] distance in gas, propagated for laser; X is the volumetric concentration of gas; (v) be linear function, it has represented the shape of tested absorption line to φ, and is relevant with each component content in temperature, general pressure and the gas; And satisfy:

${\∫}_{-\∞}^{+\∞}\mathrm{\φdv}=1---\left(3\right)$

In the formula: S (T) [cm ^-2Atm ^-1] be the line strength of this spectral line, it represents the absorption intensity of this spectral line, only relevant with temperature, its value can utilize following formula to calculate:

$S\left(T\right)=S\left(T_0\right)\frac{Q\left(T_0\right)}{Q\left(T\right)}\exp [-\frac{{{\mathrm{hcE}}_i}^{\′\′}}{k}(\frac{1}{T}-\frac{1}{T_0})]\×\left[\frac{1-\exp (-{\mathrm{hcv}}_{0,i}/\mathrm{kT})}{1-\exp (-{\mathrm{hcv}}_{0,i}/k{T}_0)}\right]---\left(4\right)$

T wherein ₀Be reference temperature, Q is total intramolecule segmentation function; E _i" for hanging down the energy of activated state; v _{0, i}Be jump frequency; H is a Planck's constant, and k is a Boltzmann constant, and c is the light velocity.Be lower than 2500K in temperature, under the situation of wavelength less than 2.5 μ m, last can be left in the basket.

Because the integration of linear function in whole frequency domain scope is constant 1, so formula (2) is expressed as:

$A={\∫}_{-\∞}^{+\∞}-\ln \left(\frac{I_t}{I_0}\right)\mathrm{dv}=\mathrm{PXS}\left(T\right)L---\left(5\right)$

A is for measuring the spectral absorption integrated value that calculates.Equation (5) has provided the relation between spectral absorption integrated value and the tested gas parameter, comprises gas concentration, temperature (line strength value) etc.Measure when can realize temperature and concentration, therefore need to select two gas absorption spectrum lines to measure.By in measured zone, dividing grid, and, set up system of equations according to the spectral absorption integrated value that under the different rotary angle of different measuring units, calculates:

$\left\{\begin{array}{c}A(v_1,1)={\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{1,1}}{L}_{v\mathrm{1,11}}+{\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{1,2}}{L}_{v\mathrm{1,12}}+\·\·\·+{\left(\mathrm{PS}\left(T\right)X\right)}_{v1,N}{L}_{v\mathrm{1,1}N}\\ A(v_1,2)={\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{1,1}}{L}_{v\mathrm{1,21}}+{\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{1,2}}{L}_{v\mathrm{1,22}}+\·\·\·+{\left(\mathrm{PS}\left(T\right)X\right)}_{v1,N}{L}_{v\mathrm{1,2}N}\\ \·\\ \·\\ \·\\ A(v_1,M)={\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{1,1}}{L}_{v1,M1}+{\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{1,2}}{L}_{v1,M2}+\·\·\·+{\left(\mathrm{PS}\left(T\right)X\right)}_{v1,N}{L}_{v1,\mathrm{MN}}\end{array}\right.---\left(6\right)$

$\left\{\begin{array}{c}A(v_2,1)={\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{2,1}}{L}_{v\mathrm{2,11}}+{\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{2,2}}{L}_{v\mathrm{2,12}}+\·\·\·+{\left(\mathrm{PS}\left(T\right)X\right)}_{v2,N}{L}_{v\mathrm{2,1}N}\\ A(v_2,2)={\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{2,1}}{L}_{v\mathrm{2,21}}+{\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{2,2}}{L}_{v\mathrm{2,22}}+\·\·\·+{\left(\mathrm{PS}\left(T\right)X\right)}_{v2,N}{L}_{v\mathrm{2,2}N}\\ \·\\ \·\\ \·\\ A(v_2,M)={\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{2,1}}{L}_{v2,M1}+{\left(\mathrm{PS}\left(T\right)X\right)}_{v\mathrm{2,2}}{L}_{v2,M2}+\·\·\·+{\left(\mathrm{PS}\left(T\right)X\right)}_{v2,N}{L}_{v2,\mathrm{MN}}\end{array}\right.---\left(7\right)$

Wherein, (v1 M) for spectral line v1 is a spectral absorption integrated value under the M in the angle sequence number, obtains by measuring to calculate A; L _{V1, MN}Be the contribution margin of each grid, when carrying out grid dividing, determine, so just obtained two system of equations about gas concentration X and temperature T (line strength S (T)) for projection.When rebuilding calculating, suppose that at first initial temperature distributes, and in conjunction with the data for projection of article one spectral line, utilizes numerical computation method at first to reconstruct the distribution of concentration of gas; On the distribution of concentration that obtains, utilize the data of second spectral line to revise, obtain the temperature field and distribute, and the like, restrain in iterative process up to temperature field and concentration field, export its reconstructed results.

At last, it is also to be noted that what more than enumerate only is specific embodiment of the utility model.Obviously, the utility model is not limited to above embodiment, and many distortion can also be arranged.All distortion that those of ordinary skill in the art can directly derive or associate from the disclosed content of the utility model all should be thought protection domain of the present utility model.

Claims (2)

1, the measurement mechanism of flue gas concentration Temperature Distribution is rebuild in the relative helical motion of a kind of laser instrument, comprise signal generator, lasing light emitter and fiber-optic output, it is characterized in that, also comprise the beam shaping lens of being located at the electric rotary table edge, focus on cylindrical mirror and be positioned at and the corresponding electric rotary table opposite side of beam shaping lens edge; The transverse cross-section parallel of electric rotary table and flue, electric rotary table and flue have same axis of rotation; Focusing on cylindrical mirror is connected with computing machine with linear array detector successively by signal wire.

2, the measurement mechanism of flue gas concentration Temperature Distribution is rebuild in the relative helical motion of laser instrument according to claim 1, it is characterized in that having a universal stage controller to be connected with electric rotary table.

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