Spectroscopic determination of concentration in rectification column
The present invention relates to a method for determining the concentration in a rectification column by means of IR spectroscopy, wherein the sample is taken under hydrostatic control.
1 . Method for spectroscopically determining the concentration of a substance in a rectification column, comprising:
1) determining the concentration of the substance by means of IR spectroscopy,
2) conducting a sample loop of the rectification column at a certain height H o and introducing the sample back into the rectification column below the outlet at a height H u , resulting in a height differential ΔH,
3) taking the sample under hydrostatic control and via the sample loop by building up a hydrostatic pressure level in the sample loop which is higher than the pressure drop in the column section relevant to the height differential ΔH, and
4) branching off an analysis line (bypass line) from the sample loop and conducting back the line back into the sample loop, and conducting the liquid to be analysed past an IR analysis probe.
2 . The method according to claim 1 , wherein the rectification column is operated in the reduced pressure range.
3 . The method according to claim 1 , wherein the concentration is determined by means of NIR spectroscopy.
4 . The method according to claim 1 , wherein the analysis line
1) includes a degassing loop,
2) is designed for temperatures of from 0° C. to 180° C.,
3) can be heated and
4) calibration samples can be taken from the analysis line