Yuan Hongfu

In-Line Monitoring of Several Pilot Scale Catalytic Reforming Units Using a Short-Wavelength near Infrared Analyser

This paper reports a novel application of in-line, short wavelength, near infrared (SW-NIR) spectroscopy to monitor eight pilot scale reforming units, for real-time determination of research octane number (RON) and aromatic compositions (benzene, toluene, xylene and total aromatics) of reforming gasoline, by an on-line SW-NIR system constructed by ourselves. Robust partial least squares calibration models for sample composition and measurement conditions were built using a global calibration set including off-line and in-line samples. Prediction results of the global models, over a six month period, for the eight units show excellent correlation with the corresponding reference data. The spectral pretreatment method of mean sample residual spectrum correction was used to remove spectral difference among multi-channels caused by small coupling differences among fibres and the multiplexer in the analyser. The prediction statistics showed consistency among the eight channels without any systematic errors. The applications of the NIR analyser can rapidly reflect the state of the process at a given time without any operator intervention. Moreover, the high stability and ruggedness of the CCD array-based on-line instrumentation guarantees easy and reliable operation.

Rapid determination of reactivity of natural cellulose pulp for viscose rayon by diffuse reflectance near infrared spectroscopy

The reactivity of natural cellulose pulp is a key parameter in dissolving pulp in the viscose-fibre production process. Traditional analytical methods of the pulp are time-consuming, laborious and polluting. A rapid method for reactivity using a combination of near infrared diffuse reflectance spectroscopy and chemometrics is proposed in this paper. For this study, 92 samples of natural cellulose pulp (reactivity range 2 s to >250 s) were collected, and their reactivity values were determined as reference data by the standard method FZ/T 50010.13. A principal component analysis (PCA)-based model for distinguishing qualified samples from unqualified samples and a soft independent modelling of class analogy (SIMCA)-based model were constructed, respectively. The discrimination power of the SIMCA model was higher than that of the PCA model in all the samples. A quantitative calibration model of reactivity was established by PLS1 with a coefficient of determination of 0.84, standard error of calibration of 1.76 s, standard error of prediction of 2.12 s and ratio of prediction to deviation of 2.53. The new method is rapid, environmentally friendly, low cost and sufficiently accurate to be of value to the textile industry.

Research and development of near infrared spectroscopy technology and its application in the Chinese petrochemical industry

In the past decade, near infrared (NIR) spectroscopy has expanded and been applied widely in many fields in the world. In China, NIR analytical technology has also been studied and applied in several fields since 1991, especially in the petrochemical industry. Our NIR R&D group was established in 1995; since then the group has been devoted to the research and development of packaged NIR technology, including hardware, software and calibration models. Based on a charge coupled device (CCD) linear array detector, we have developed a series of short wavelength near infrared analysers including a laboratory analyser (NIR-3000 Analyser), a portable analyser (NIR-5000 Analyser) and an on-line process analyser (Online NIR-6000 Analyser). A typical chemometrics software package was designed and written for these products. The software offers many spectral pre-processing methods, multivariate calibration methods, pattern recognition methods and calibration transfer methods. The analysers combined with the software have been used to determine physical properties and chemical composition of various petroleum products in many Chinese refineries.