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

Abstract

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 °C to 190 °C and pressures from 5 to 22 bar and analyzed via FTIR with a dead time of 5–10 s. The system was successfully used to monitor the dehydration reaction of methanol to dimethyl ether in a reactive distillation column in a 170 h long-term experiment. The system has a measurement range of 1 × 10−4 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.