Method and arrangement for measuring flow rate of optically non-homogenous material
A method and arrangement are disclosed for measuring a flow rate of optically non-homogeneous material in a process pipe. The non-homogeneous material can be illuminated through a window. Images are taken with a camera, through a window, of illuminated non-homogeneous material. Correlation between temporally successive images determines travel performed by the non-homogeneous material in the process pipe between capture of temporally successive images. Velocity of the non-homogeneous material is determined by the time difference between the successive images and the travel.
1. A method for measuring a flow rate of optically non-homogeneous material in a process pipe, the method comprising:
illuminating a measuring area of the optically non-homogeneous material in the process pipe, through a window in the process pipe that is in contact with the non-homogeneous material, with a light source;
imaging with a camera, through the same window in the process pipe, illuminated non-homogeneous material in the process pipe wherein the camera and the light source are arranged on a same side of the process pipe;
determining through correlation between temporally successive images, travel performed by the non-homogeneous material in the process pipe between capture of temporally successive images; and
determining a velocity of the non-homogeneous material in the process pipe by a time difference between the successive images and the travel.
2. The method of claim 1 , comprising:
calculating a two-dimensional correlation between the temporally successive images; and
calculating a distance travelled by the non-homogeneous material at an interval between successive images at a maximum point of correlation.
3. The method of claim 1 , comprising:
calculating a two-dimensional correlation between the temporally successive images; and
calculating a direction of travel performed by the non-homogeneous material at an interval between successive images at a maximum point of correlation.
4. The method of claim 1 , comprising:
determining an amount of turbulence in the non-homogeneous material based on a degree of correlation.
5. The method of claim 1 , wherein the measuring area of the non-homogeneous material is substantially uniformly illuminated.
6. An arrangement for measuring a flow rate of optically non-homogeneous material in a process pipe, comprising:
a light source for illuminating a measuring area of non-homogeneous material in the process pipe through a window arranged in the process pipe that will contact with the non-homogeneous material during measurement;
a camera for imaging, through the same window in the process pipe, illuminated non-homogeneous material in the process pipe wherein the camera and the light source are arranged on a same side of the process pipe; and
means for determining, through correlation between temporally successive images, travel performed by the non-homogeneous material in the process pipe between capture of temporally successive images and for determining a velocity of the non-homogeneous material in the process pipe by a time difference between the successive images and the travel.
7. The arrangement of claim 6 , wherein the means for determining is configured for calculating a two-dimensional correlation between successive images for calculating a distance travelled performed by the non-homogeneous material at an interval between the successive images at a maximum point of correlation.
8. The arrangement of claim 6 , wherein the means for determining is configured for calculating a two-dimensional correlation between successive images and for calculating a direction of travel performed by the non-homogeneous material at an interval between the successive images at a maximum point of correlation.
9. The arrangement of claim 8 , wherein the means for calculating the correlation determine an amount of turbulence in the non-homogeneous material based on a degree of the correlation.
10. The arrangement of claim 6 , wherein the light source is configured to illuminate the measuring area of the non-homogeneous material substantially uniformly.
11. The arrangement of claim 6 , comprising:
a mirror for transmitting light from the light source to the window.
12. The arrangement of claim 11 , wherein the mirror is arranged for directing light to a beveled surface formed in the window.
13. The arrangement of claim 12 , wherein the light source is arranged on the beveled surface formed in the window.
14. The arrangement of claim 6 , wherein the window comprises:
a viewing glass in the process pipe.