Impact of Flow Configurations on Response Time and Data Quality in Real-Time, In-Line Fourier Transform Infrared (FTIR) Monitoring of Viscous Flows

Journal Article · 02 November 2023 · Organic Process Research & Development

DOI: https://doi.org/10.1021/acs.oprd.3c00299 · OSTI ID:2222583

Al Azri, Nasser  ^[1]; Clifford, Corey ^[2]; Enick, Robert M.  ^[2]; Veser, Götz  ^[2]

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1. University of Pittsburgh, PA (United States); University of Pittsburgh
2. University of Pittsburgh, PA (United States)

The real-time, in-line monitoring of continuous flow concentrations is widely conducted via infrared (IR) spectrometry by using a flow cell connected to a reactive flow stream. For protective purposes, the IR sensor tip is typically offset from the flow. This offset can cause the formation of a stagnant boundary layer above the sensor, especially when dealing with high-viscosity fluids. As a result, the IR signal response time is often controlled by the slow diffusional exchange of fluid in the boundary layer, as confirmed via 2D computational fluid dynamics (CFD) simulations. We evaluated several flow configuration modifications in a typical IR flow cell in order to identify the changes to the flow dynamics that enable improved response times with minimal changes to the cell configuration: the use of (i) vertical flow, where the standard horizontal flow over the sensor is redirected to contact vertically with the sensor, (ii) a static mixer to create radial flow momentum above the IR sensor, and (iii) horizontal or vertical nozzles to direct the flow toward the IR sensor. The vertical flow configuration did not show any significant improvement over the standard horizontal flow configuration. However, the static mixer, horizontal nozzle, and vertical nozzle configurations all resulted in markedly improved response times and signal quality, albeit at the expense of a higher pressure drop across the flow cell. These results point toward straightforward, user-accessible modifications of in-line IR flow cells that result in significant improvements in signal stability and acquisition times.

• Research Organization: RAPID Manufacturing Institute, New York, NY (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: EE0007888
• OSTI ID: 2222583
• Journal Information: Organic Process Research & Development, Journal Name: Organic Process Research & Development Journal Issue: 5 Vol. 28; ISSN 1083-6160
• Publisher: ACS PublicationsCopyright Statement
• Country of Publication: United States
• Language: English