During the Laux-Process, Aniline, which is an important substance for many production processes, is synthesized as a byproduct. The separation of Aniline out of the Laux-process is a multi-stage method, including a steam-distillation. The monitoring of the Aniline concentration as a means of quality control is crucial and until now has been a elaborate task, including a laboratory offline measurement of the refractive index, which stands in distinctive correlation to its concentration levels.
First trials in changing from laboratory to inline measurement systems have not been very successful for a production plant in the Netherlands due to the employed types of Process Refractometers. The previously used systems have been working according to the same principle as the laboratory systems - measuring the refractive index through the total reflection at the critical angle. The big disadvantage of this technique is that within the process, the build-up of media on the prism leads to complete failures of the measurement even after very short exposure times.
By changing to FLEXIM's PIOX R Process Refractometer, the client has now been able to reliably measure the concentration / refractive index due to the special optical technology employed within the PIOX R.
PIOX R measures according to the unique transmitted light principle instead of the critical angle method. This means, that the system does not rely on measuring the very thin interface layer between the prism and the medium, but measures the real refraction of the light beam when being transmitted through the medium.
PIOX R is thus totally independent against any fouling on the prism and allows for very stable measurements without zero drift - even at strong temperature and pressure variations.