IMMERSION-TYPE ONLINE MULTIPHASE MEASURING INSTRUMENT AND METHOD

Abstract

The present invention provides an immersion-type online multiphase measuring instrument and method. The instrument comprises a package tube; a viewport; LED lamps and a brightness-adjustable light source system including a power supply, a signal generator and an oscilloscope; a telecentric lens and an image sensor; a controller; a signal processing and outputting system; and a display system. The LED lamps, the telecentric lens and the image sensor are located in the package tube. The exposure period of the image sensor is less than the pulse period of the signal generator. The photographic probe used in this measuring instrument has the advantages of online quantitative measurement, small size, portability, less-impact of fluid temperature and the surrounding environment, adaptability to transparent and opaque reactors with two-phase, three-phase and more than three-phase. It can capture the high contrast images of local fluid flow in multiphase reactor. And then the local characteristics such as concentration, particle size and velocity distribution of bubble, liquid droplets or solid particles can be obtained using corresponding measuring method and professional image processing software.

Claims

1. An immersion-type online multiphase measuring instrument comprising: a package tube; a viewport, sealedly installed at the front end of the package tube; an illumination system for illuminating multiphase flow, including LED lamps and a brightness-adjustable light source connected with the LED lamps, which comprises a power supply, a signal generator and an oscilloscope; a photographic system for taking pictures, including a telecentric lens and an image sensor; a controller connected with the signal generator and the image sensor; a signal processing and outputting system connected with the image sensor; a display system connected with the signal processing and outputting system; and the LED lamps, the telecentric lens and the image sensor are located in the package tube and the exposure period of the image sensor is less than the pulse period of the signal generator, controlled by the controller.

2. The online multiphase measuring instrument according to claim 1, wherein the work distance of the telecentric lens is 250-550 mm, and the depth of field is 1-3.7 mm.

3. The online multiphase measuring instrument according to claim 1, wherein the magnification of the telecentric lens is 0.5-1 time.

4. The online multiphase measuring instrument according to claim 1, wherein the external diameter of the telecentric lens is 19-25 mm.

5. The online multiphase measuring instrument according to claim 1, wherein the image sensor is a CCD camera or a CMOS camera.

6. The online multiphase measuring instrument according to claim 1, wherein the exposure time of the CCD camera or CMOS camera is less than or equal to 1 ms, and the resolution is 5-15 μm; the number of pixels in length and width is at least 800×600, and the frame frequency is at least 60 fps.

7. The online multiphase measuring instrument according to claim 1, wherein the number of the LED lamps is at least 12.

8. The online multiphase measuring instrument according to claim 1, wherein the LED lamps are evenly arranged circularly in the package tube.

9. The online multiphase measuring instrument according to claim 1, wherein the LED lamps are linked with the brightness-adjustable light source by a wire.

10. The online multiphase measuring instrument according to claim 1, wherein the package tube is composed of a front tube and a back tube with different diameters.

11. The online multiphase measuring instrument according to claim 10, wherein the external diameter of the front tube is 25-30 mm, and the length is 300-600 mm.

12. The online multiphase measuring instrument according to claim 10, wherein the external diameter of the back tube is 50 mm, and the length is 50 mm.

13. The online multiphase measuring instrument according to claim 1, wherein the material of the packaged tube is stainless steel.

14. The online multiphase measuring instrument according to claim 10, wherein the viewport, the LED lamps and the telecentric lens are packaged in the front tube; the viewport is arranged on the end of the front tube away from the back tube, followed by the LED lamps and telecentric lens; and the image sensor is packaged in the back tube.

15. The online multiphase measuring instrument according to claim 1, wherein the viewport is made up of a piece of circular glass coated by antireflection film.

16. The online multiphase measuring instrument according to claim 1, wherein the image sensor and the signal generator are connected to the controller by a high-speed data wire.

17. The online multiphase measuring instrument according to claim 1, wherein the display system comprises an LED screen.

18. The online multiphase measuring instrument according to claim 1, wherein the signal processing and outputting system, the controller and the display system are integrated into a computer.

19. A method of using the immersion-type online multiphase measuring instrument according to claim 1 for measuring the state of multiphase flow, wherein the method is: the immersion-type online multiphase measuring instrument is arranged in a multiphase flow reactor; then photography are conducted using the illumination system and the photographic system synchronously to obtain the image information of local flow in multiphase flow reactor; at last, the image information is analyzed using an image analysis software and the state information of the multiphase flow at the front face of the immersion-type online multiphase measuring instrument is obtained.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG. 1 is a schematic drawing of the structure of the immersion-type online multiphase measuring instrument provided in Example 1 according to the present invention.

[0044] As shown in FIG. 1, “1” is a viewport, “2” is LED lamps, “3” is a stainless steel package tube, “4” is a telecentric lens, “5” is a minisize high speed CMOS camera, “6” is a brightness-adjustable light source, “7” is a wire, “8” is a USB3.0 data line, “9” is a high speed image acquisition card, and “10” is a sampling computer.

[0045] FIG. 2 is a synchronization control mode of lighting flash and CMOS camera provided in Example 1.

[0046] FIG. 3 is a double-exposure image of the liquid-solid system provided in Example 2.

[0047] FIG. 4 is a processed result of the double-exposure image in FIG. 3.

[0048] FIG. 5 is a velocity profile of the solid particle obtained by the measuring method of particle velocity in Example 2.

[0049] FIG. 6 is an image of the gas-liquid-solid system captured by the immersion-type online multiphase measuring instrument, where (a) the instantaneous image at the measuring point; (b) the results of the solid particle diameter measurement; and (c) the results of the bubble diameter measurement.

Embodiments

[0050] Further description of the technical scheme is as follows by specific examples combining with the drawings.

EXAMPLE 1

[0051] A schematic drawing of an immersion-type online multiphase measuring instrument for multiphase reactors is shown in FIG. 1. The structure of the instrument is described as below.

[0052] A stainless steel package tube 3;

[0053] a viewport 1, sealedly installed at the front end of the stainless steel package tube 3;

[0054] an illumination system for illuminating multiphase flow, including LED lamps 2 and a brightness-adjustable light source connected with the LED lamps 2, which comprises a power supply, a signal generator and an oscilloscope;

[0055] a photographic system for taking pictures, including a telecentric lens 4 and an image sensor; the image sensor is a high speed CMOS camera 5;

[0056] a controller connected with the signal generator and the image sensor;

[0057] a signal processing and outputting system connected with the image sensor; and

[0058] a display system connected with the signal processing and outputting system.

[0059] The LED lamps, the telecentric lens and the image sensor are located in the stainless steel package tube, the brightness-adjustable light source, the controller, the signal processing and outputting system and the display system are located outside the stainless steel package tube, and the exposure period of the image sensor is less than the pulse period of the signal generator, controlled by the controller.

[0060] The signal processing and outputting system, the controller and the display system are integrated into a sampling computer 10.

[0061] Specifically, the first element is a viewport 1, which is a piece of circular sapphire glass coated by antireflection film. Twenty LED lamps 2 are arranged uniformly behind the viewport 1, which composes a ring. A telecentric lens 4 is installed behind the LED lamps 2, and the parameters are listed as: the magnification is 1; both vision fields of objects and images are φ 8 mm; the work distance is 250 mm; the telecentricity is less than 0.1°; the depth of field is 2.1 mm; the resolution is 14.3 μm and the optical aberration is less than 0.12%. A work distance is between the outside surface of the viewport (1) and the front side of the telecentric lens 4, in order to take sharp pictures. A standard C port connects the telecentric lens 4 to the high speed CMOS camera 5. Parameters of the CMOS are that the resolution is 1280×1024, the colors are monochrome, the frame rate is 150 fps and a USB 3.0 is applied. The viewpoint 1, the LED lamps 2, the telecentric lens 4 and the high-speed CMOS camera 5 are packaged inside the stainless steel package tube 3. A brightness-adjustable light source 6 is configured outside of the measuring instrument, connecting to the LED lamps 2 by a wire (7). The telecentric lens 4 connects to the sampling computer 10 by a USB3.0 data line (8), and the computer is equipped with high speed image acquisition card.

[0062] In order to obtain a clear image by such an instrument, the way to control the synchronization of LED lamps flashing and CMOS camera is shown in FIG. 2: opening source switch, then setting the intensity and period of pulse light by the light source driver; next, setting the exposure time, light balance, frame rate and gain to match the pulse period of the illumination signal and the exposure time of the image sensor (the exposure period of the image sensor is less than the pulse period of the signal generator) by the controller in computer. Thus, the synchronization of pulse light and image capturing is realized.

EXAMPLE 2

[0063] Velocity distribution of solid particles in liquid-solid system is measured by the immersion-type online multiphase measuring instrument, which was described in Example 1.

[0064] The experiment was carried out in an elliptical-bottom plexiglass stirred tank with an inner diameter of T=280 mm stirred by a six-leaf pitched-blade turbine with a diameter of D=T/3 with 4 standard baffles (the baffle width B=T/10). The turbine height off bottom is C=T/3. The impeller speed is 480 rpm. Static liquid height is H=1.2T. The average solid holdup (volume ratio) is 0.01. The measured points are at r=0.025, 0.045, 0.065, 0.085, 0.105, 0.125 m, and z=0.045, 0.090, 0.135, 0.180, 0.220, 0.260, 0.300 m.

[0065] The measuring method includes the following steps:

[0066] (1) the online multiphase measuring instrument is placed in a multiphase reactor; the exposure time t.sub.1 of the image sensor and the pulse period t.sub.2 of the signal generator are controlled to meet the condition t.sub.1>2t.sub.2, and a double-exposure particle image is obtained, as shown in FIG. 3;

[0067] (2) the actual size of individual pixel in the image is calibrated using a graduated ruler with an accuracy of 0.1 mm scale;

[0068] (3) valid particles are determined using the following steps: first, the focal plane position of the telecentric lens is determined; then, the object to be measured is respectively arranged on the front of the package tube, the l/2 positions ahead of or behind the focal plane, where l is the telecentric lens depth of field (mm); the object to be measured is photographed by the online multiphase measuring instrument, and the image of the object is obtained and the gray gradient Grad(Φ.sub.l/2) around the boundary of the object is determined, where Φ.sub.l/2 is the gray value at the ±l/2 positions ahead of or behind the focal plane; if Grad(Φ) is greater than or equal to Grad(Φ.sub.l/2), the particle is labeled as a valid one; and

[0069] (4) the double-exposure image of the same valid particle is identified using a particle matching algorithm; the lower left corner of the particle image is set as coordinate origin; in accordance with the order “binarization, interception of part of the area and centroid extraction”, the centroid coordinates (m.sub.t,i, n.sub.t,i) and (m.sub.t+Δt,i, n.sub.t+Δt,i) are read; then the centroid coordinates are conversed to the actual length of the coordinates (x.sub.t,i, y.sub.t,i) and (x.sub.t−Δt,i, y.sub.t+Δt,i) using the actual size of individual pixel obtained in step (2),

[0070] so the instantaneous velocity of particles is calculated by:

[00001]$V_i=\frac{\sqrt{{\left(x_{t+\Delta .Math..Math.t,i}-x_{t,i}\right)}^2+{\left(y_{t+\Delta .Math..Math.t,i}-y_{t,i}\right)}^2}}{\Delta .Math..Math.t},$

[0071] where Δt is the time interval between twice exposures.

[0072] According to the analysis of nearly 4000 particles, the velocity distribution of solid particles in liquid-solid system is shown in FIG. 5. Compared to the CFD simulation of the invasive error analysis, all of the errors of measuring results are less than 15%.

EXAMPLE 3

[0073] The particle diameter distribution of solid particles and bubbles in a gas-liquid-solid three-phase stirred tank is measured by the immersion-type online multiphase measuring instrument, which is described in Example 1.

[0074] The experiment is carried out in the stirred tank. The solid particles are white plastic beads with a diameter of about 1 mm, and the average solid holdup (volume ratio) is 0.01. The measuring point is at r=0.07 m and z=0.055 m. The air is vented by the annular gas distributor at a rate of flow of 800 L/h. The impeller speed is set as 480 rpm.

[0075] The measuring method comprises the following steps:

[0076] (1) the online multiphase measuring instrument is arranged in the gas-liquid-solid system, and an image is obtained as shown in FIG. 6-(a);

[0077] (2) valid particles are determined using the following steps:

[0078] First, the focal plane position of the telecentric lens is determined: a graduated ruler with an accuracy of 0.1 mm is placed in the same medium with the system; the medium is photographed using the online multiphase measuring instrument, the distance between the graduated ruler and the online multiphase measuring instrument is adjusted and the clarity of the graduated ruler in the photograph is observed; the position where the graduated ruler is clearest is the focal plane position;

[0079] then, the object to be measured is respectively arranged on the front of the package tube, the l/2 positions ahead of or behind the focal plane, where l is the telecentric lens depth of field (mm); the object to be measured is photographed by the online multiphase measuring instrument, and the image of the object is obtained and the gray gradient Grad(Φl/2) around the boundary of the object is determined, where Φ.sub.l/2 is the gray value at the ±l/2 positions ahead of or behind the focal plane; if Grad(Φ) is greater than or equal to Grad(Φ.sub.l/2), the particle is labeled as a valid one; and

[0080] (3) a graduated ruler with an accuracy of at least 0.1 mm is arranged on the front of the online multiphase measuring instrument; then its image is captured; the number of pixels N.sub.10 corresponding to 10 mm distance in the graduated ruler is picked up by an image processing software so as to determine the actual length of individual pixel; and the number of pixels occupied by the valid particle is measured;

[0081] the diameter of the valid particle is calculated by d.sub.i=10×n.sub.i/N.sub.10where d.sub.i is the particle diameter (mm); n.sub.i is the number of pixels occupied by the valid particle; N.sub.10 is the number of pixels occupied by the 10 mm-long scale in the graduated rule;

[0082] according to the equation

[00002]$\alpha =\frac{V_c}{V}=\frac{\underset{i}{\overset{n}{.Math.}}.Math.\frac{1}{6}.Math.\pi .Math..Math.d_i^3}{S\times l},$

the concentration of the valid particles is calculated, where S is the effective area of the photosensitive area of the image sensor (mm.sup.2); l is the lens depth of field (mm); d.sub.i is the particle diameter (mm); V.sub.c is the total volume of the valid particles, Vis the volume of the measured area; n is the number of the valid particles.

[0083] The solid particles and bubble diameter distributions at the measuring point are gained by processing the image, and the results are shown in FIGS. 6-(b) and 6-(c). The diameter of solid particles is in the range of 0.9-1.1 mm, and that of the bubbles is in the range of 0.5-2.8 mm. The holdups of bubbles and solid particles at this point are 0.016 and 0.0115, respectively.

[0084] The above are only specific examples of the present invention but the present invention is not limited thereto. Those skilled in the art to which the present invention belongs should appreciate that any change or replacement which can be easily thought by those skilled in the art within the technical scope disclosed by the present invention all fall into the scope protected and disclosed by the present invention.