Gas analyzer for continuous monitoring of carbon dioxide in gas streams

• Published in: Sensors and actuators. B, Chemical Chemical, 2010-03, Vol.145 (1), p.398-404
• Main Authors: Marzouk, Sayed A.M., Al-Marzouqi, Mohamed H.
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Carriers; CO 2 gas analyzer; Contactors; Detectors; Downstream effects; Gas streams; Hollow fiber membrane contactors; In-line gas analysis; Monitoring; Monitors; pH detector
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2009.12.045

The construction and characterization of a simple and inexpensive gas analyzer setup for direct measurement of CO 2 concentration in gas streams are presented. The analyzer was based on a hollow fiber membrane (HFM) contactor which served as a mean for continuous gas sampling and preconcentration of CO 2 from the gas stream into a dilute buffer carrier solution. The resultant pH changes of the carrier solution were measured downstream by a pH flow-through detector. A Nernstian response of 55.5 mV/log[CO 2] was obtained over a wide dynamic range of 0.1–100% CO 2 in nitrogen. Moreover, the presented analyzer offered several favorable performance characteristics such as fast response (45 s) and recovery times (1–2 min), excellent signal stability and reproducibility (RSD = 1.2%) and intrinsic high selectivity in the presence of most common neutral gases (e.g., CH 4, N 2, O 2, CO, etc.). H 2S and SO 2 which are potentially interfering acidic gases were efficiently removed by a simple prior in-line treatment using acidified potassium permanganate bubbler. The analyzer was applied successfully to monitor the treatment process of CO 2 removal from CO 2–CH 4 gas mixtures. The merits of the developed analyzer suggest its reliable use in various applications requiring continuous carbon dioxide monitoring in gas streams for several hours.