Near-infrared (NIR) spectroscopy is a high throughput, non-destructive analysis method that can eliminate lost time and product with real-time quality control. The real-time results make NIR spectroscopy an ideal process analytical tool for process control. The main advantages of NIR spectroscopy are high throughput, high precision, and high accuracy, as well as the ability to monitor multiple chemical and physical properties in a matter of seconds. A process NIR analyser can run unattended and the cost of ownership is very low as it is virtually maintenance-free. In addition, a NIR analyser does not consume chemicals nor does it produce any chemical waste. Operators do not require specific skills and do not need to follow an elaborate training programme to understand and operate a NIR analyser. Using automated data analysis, a NIR analyser system can be successfully used to assess the purity of ethylene, butane, and propane produced, as well as optimise the speed and quality control of the refinement process itself.
How does spectroscopy work?
NIR spectroscopy is the process of transmitting light through a sample. Portions of the light are absorbed by various compounds in the sample, with the remaining transmitted light being sent to either a dispersive grating spectrometer (DG-NIR), a Fourier transforms spectrometer (FT-NIR), or other techniques for analysis. For practical purposes, the difference between FT-NIR and DG-NIR analysers only lies in the underlying technology. Both methods produce comparable readings that a technician or area manager can use to make informed decisions. The spectrometer measures the difference between the pure spectrum of the light source and the light that passed through the sample, resulting in an absorbance spectrum. By varying the known concentration of specific chemicals between samples the absorbance will vary and a calibration curve can be generated using chemometrics routines.
Online analysis with NIR spectroscopy
One of the best techniques for rapid screening and analysis of hydrocarbon-based mixtures is NIR spectroscopy. Many petrochemical compounds absorb NIR light very strongly, and each chemical has...
Written by Ryan Lerud and Hans Buytaert, Guided Wave, Inc.
This article was originally published in the February 2021 issue of Hydrocarbon Engineering magazine. To read the full article, view the February issue here. And to sign up to receive a free regular copy of the magazine, click here.
Read the article online at: https://www.hydrocarbonengineering.com/special-reports/03022021/making-light-work-of-product-validation/