Inline process monitoring of the moisture content in propylene oxide

Significance of Inline Moisture Monitoring in Propylene Oxide

Propylene oxide is a key feedstock in the chemical industry with over ten million tons produced annually. Its hygroscopic and flammable nature makes precise moisture control essential to prevent side reactions, ensure product quality, and maintain safe operations. Real time inline analysis offers rapid feedback, minimizes manual handling, and supports high throughput production environments.

Objectives and Study Overview

The primary goal of this application was to establish a reliable, explosion proof inline method for continuous measurement of trace moisture in propylene oxide streams. The study focused on integrating near infrared spectroscopy into the process line, calibrating models against a primary reference method, and demonstrating the approach under industrial conditions.

Methodology

Measurements were performed in the 1850 to 1950 nanometer wavelength range using stainless steel flow cells designed for hazardous areas. Real time spectral data from multiple process points were acquired via a multiplexed near infrared analyzer and correlated to reference values obtained by Karl Fischer titration. Calibration models accounted for spectral variations and process dynamics to predict moisture content in milligrams per liter.

Used Instrumentation

• NIRS XDS Process Analyzer SingleFiber 9 Channel configuration for up to nine measurement points
• Explosion proof stainless steel flow cells mounted directly in the process line
• Laboratory Karl Fischer titrator and inline KF module for reference moisture determination

Main Results and Discussion

Inline NIRS predictions closely matched reference titration values when models were built using online KF data, avoiding bias from atmospheric moisture pickup in manual samples. Typical moisture concentrations ranged from 20 to 30 milligrams per liter. The inline system delivered fast response to process changes and maintained model accuracy across varying operating conditions.

Benefits and Practical Applications

• Immediate detection of moisture deviations supports tighter process control and higher yields
• Elimination of manual sampling reduces personnel exposure to hazardous chemicals
• Reagent free spectroscopy lowers operating costs and environmental impact
• Multipoint monitoring enables comprehensive surveillance of critical process streams
• Rapid return on investment through optimized production and quality assurance

Future Trends and Opportunities

Emerging developments include advanced chemometric algorithms for dynamic model adaptation, integration with inline KF titration for enhanced reference accuracy, and miniaturized sensor designs for broader deployment. Artificial intelligence driven analytics and cloud based data handling will further enhance process insight, predictive maintenance, and remote monitoring capabilities.

Conclusion

Inline near infrared spectroscopy has proven to be a safe, accurate, and cost effective solution for monitoring low moisture levels in propylene oxide. The approach enhances process control, reduces manual intervention, and increases profitability. Ongoing advances in instrumentation and data analysis promise even greater performance and adaptability.

References

1. Kawabata T, Yamamoto J, Koike H, Yoshida S. Trends and Views in the Development of Technologies for Propylene Oxide Production. Sumitomo Kagaku. 2019;4–11.
2. Kleimeier. Near Infrared Spectroscopy of Production Processes. GIT Labor Fachzeitschrift. 2018;36–38.