Method and arrangement in connection with separate sample taken from process liquid
A method and an arrangement are disclosed in connection with a measurement arrangement of optical parameters of a separate sample taken from a process liquid, in which method a sample is taken from the process liquid. The sample can be arranged into a sample vessel provided with at least one measurement window, and optical parameters of the sample in the sample vessel are measured through the measurement window. In the sample in the sample vessel, a flow is produced which can be used to mitigate (e.g., prevent) the measurement window surface in contact with the sample from getting dirty. A back-and-forth flow can be produced in the sample residing in the sample vessel by means of pressure variation focused on the sample, and the back-and-forth flow can be focused on the surface of the optical measurement window.
1. A method for measurement of optical parameters of a separate sample taken from a process liquid, the method comprising:
taking a sample from the process liquid;
arranging the sample into a sample vessel provided with at least one optical measurement window;
measuring optical parameters of the sample in the sample vessel through the at least one optical measurement window;
producing a flow in the sample in the sample vessel, such a flow configured to mitigate the surface of the at least one optical measurement window which is in contact with the sample, from becoming dirty;
generating a back-and-forth flow comprising a fast flowing pulse in the sample in the sample vessel by a pressure variation directed on the sample; and
directing the back-and-forth flow on the surface of the at least one optical measurement window wherein an angle of the flow directed on the surface of the at least one optical measurement window is divergent from an angle parallel to the surface of the at least one optical measurement window.
2. The method as claimed in claim 1 , comprising:
producing the pressure variation by one or more pistons moving back and forth.
3. The method as claimed in claim 1 , comprising:
producing the pressure variation by a diaphragm.
4. The method as claimed in claim 1 , comprising:
producing the pressure variation by a bellows.
5. The method as claimed in claim 1 , comprising:
directing the back-and-forth flow produced in the sample to the surface of the optical window by flow guide structures.
6. The method as claimed in claim 5 , wherein the structures guiding the flow comprise:
a guiding wall structure.
7. The method as claimed in claim 5 , wherein the structures guiding the flow comprise:
a nozzle structure.
8. The method as claimed in claim 1 , comprising:
producing the pressure variation by two pistons, which move simultaneously in opposite directions.
9. The method as claimed in claim 1 , comprising:
controlling a temperature of the sample vessel to produce a constant temperature of the sample.
10. The method as claimed in claim 1 , comprising:
transferring heat to the sample moving back and forth to avoid temperature gradients in the sample.
11. An arrangement for measuring optical parameters of a separate sample taken from a process liquid, the arrangement comprising:
a sample vessel having at least one optical measurement window, the at least one optical measurement window being configured and arranged to obtain a measurement of optical parameters of a sample once placed in the sample vessel through the at least one optical measurement window; and
means for producing a flow in the sample vessel to mitigate a surface of the at least one optical measurement window which is in contact with the sample from becoming dirty, wherein the means for producing the flow in the sample includes at least one structure for producing a back-and-forth flow comprising a fast flowing pulse in the sample with a pressure variation, flow guiding structures for directing the back-and-forth flow to the surface of the at least one optical measurement window wherein an angle of the flow directed on the surface of the at least one optical measurement window is divergent from an angle parallel to the surface of the at least one optical measurement window.
12. The arrangement as claimed in claim 11 , wherein the means for producing the back-and-forth flow in the sample by a pressure variation comprises:
a piston.
13. The arrangement as claimed in claim 11 , wherein the means for producing the back-and-forth flow in the sample by a pressure variation comprises:
a diaphragm.
14. The arrangement as claimed in claim 11 , wherein the means for producing the back-and-forth flow in the sample by pressure variation comprises:
a bellows.
15. The arrangement as claimed in claim 11 , wherein the structures guiding the flow comprise:
a guiding wall structure.
16. The arrangement as claimed in claim 11 , wherein the structures guiding the flow comprise:
a nozzle structure.
17. The arrangement as claimed in claim 11 , wherein the means for producing the back-and-forth flow in the sample by a pressure variation comprises:
two pistons which move simultaneously in opposite directions.
18. The arrangement as claimed in claim 11 , comprising
a temperature control for controlling a temperature of the sample vessel to produce a constant temperature of the sample.
19. The arrangement as claimed in claim 11 , comprising:
a heater for transferring heat to a sample when moving back and forth to avoid temperature gradients in the sample.
20. The arrangement as claimed in claim 11 , wherein the at least one optical measurement window comprises:
two optical measurement windows.