Low-interference real-time at-line spectroscopic composition analysis for chemical plants

Abstract

A novel system for composition analysis in chemical plants at high temperatures and pressures has been developed. The system uses heated capillaries to extract and transport liquid and gaseous samples to a Fourier-Transform-Infrared-Spectrometer (FTIR) for analysis. The samples are extracted from pressure vessels at temperatures ranging from 20 to 190°C and pressures from 5 to 22 bar and analyzed via FTIR with a dead time of 5 to 10 seconds. The system was successfully used to monitor the dehydration reaction of methanol to dimethyl ether in a 170-hour long-term experiment. The system has a measurement range of 1E-4 mol mol-1 to 1 mol mol-1 and is accurate and fast enough for real-time product quality assessment and control in high purity chemical processes where inline measurements are challenging due to harsh environments.

Demonstration and experimental model validation of the DME synthesis by reactive distillation in a pilot-scale pressure column

“…Within the time frame of steady state operation, every sampling point was analysed multiple times to ensure a reproducible measurement of the gas phase composition. Details of this column analysis system developed by ASG Analytik Service AG can be found in Bogatykh et al 19 In addition to the FT-IR measurements, an online gas chromatograph (Agilent 8860, thermal conductivity detector) was used to analyse the composition of the distillate product and to validate the FT-IR measurements.…”