Online Residence Time Distribution Measurement of Thermochemical Biomass Pretreatment Reactors

David Sievers, Erik Kuhn, Jonathan Stickel, Edward Wolfrum, Melvin Tucker

Research output: Contribution to journalArticlepeer-review

27 Scopus Citations


Residence time is a critical parameter that strongly affects the product profile and overall yield achieved from thermochemical pretreatment of lignocellulosic biomass during production of liquid transportation fuels. The residence time distribution (RTD) is one important measure of reactor performance and provides a metric to use when evaluating changes in reactor design and operating parameters. An inexpensive and rapid RTD measurement technique was developed to measure the residence time characteristics in biomass pretreatment reactors and similar equipment processing wet-granular slurries. Sodium chloride was pulsed into the feed entering a 600 kg/d pilot-scale reactor operated at various conditions, and aqueous salt concentration was measured in the discharge using specially fabricated electrical conductivity instrumentation. This online conductivity method was superior in both measurement accuracy and resource requirements compared to offline analysis. Experimentally measured mean residence time values were longer than estimated by simple calculation and screw speed and throughput rate were investigated as contributing factors. A semi-empirical model was developed to predict the mean residence time as a function of operating parameters and enabled improved agreement.

Original languageAmerican English
Pages (from-to)330-336
Number of pages7
JournalChemical Engineering Science
StatePublished - 2 Feb 2016

Bibliographical note

Publisher Copyright:
© 2015 Elsevier Ltd.

NREL Publication Number

  • NREL/JA-5100-63452


  • Biomass pretreatment
  • Electrical conductivity
  • Residence-time distribution
  • Screw-conveyed reactor


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