Modeling residence-time distribution in horizontal screw hydrolysis reactors

Journal Article · 12 October 2017 · Chemical Engineering Science

DOI: https://doi.org/10.1016/j.ces.2017.10.012 · OSTI ID:1407460

Sievers, David A. ^[1]; Stickel, Jonathan J. ^[1]

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1. National Renewable Energy Lab. (NREL), Golden, CO (United States)

The dilute-acid thermochemical hydrolysis step used in the production of liquid fuels from lignocellulosic biomass requires precise residence-time control to achieve high monomeric sugar yields. Difficulty has been encountered reproducing residence times and yields when small batch reaction conditions are scaled up to larger pilot-scale horizontal auger-tube type continuous reactors. A commonly used naive model estimated residence times of 6.2-16.7 min, but measured mean times were actually 1.4-2.2 the estimates. Here, this study investigated how reactor residence-time distribution (RTD) is affected by reactor characteristics and operational conditions, and developed a method to accurately predict the RTD based on key parameters. Screw speed, reactor physical dimensions, throughput rate, and process material density were identified as major factors affecting both the mean and standard deviation of RTDs. The general shape of RTDs was consistent with a constant value determined for skewness. The Peclet number quantified reactor plug-flow performance, which ranged between 20 and 357.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Sustainable Transportation Office. Bioenergy Technologies Office (BETO)
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1407460
• Alternate ID(s): OSTI ID: 1576063
• Report Number(s): NREL/JA-5100-68272
• Journal Information: Chemical Engineering Science, Vol. 175, Issue C; ISSN 0009-2509
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English