Comparison of direct and indirect contact heat exchange to improve recovery of bio-oil

Dalluge, Dustin L.; Whitmer, Lysle E.; Polin, Joseph P.; Choi, Yong Seok; Shanks, Brent H.; Brown, Robert C.

doi:10.1016/j.apenergy.2019.113346

Cited by 23 publications

(12 citation statements)

References 26 publications

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“…35−40 Recent work has examined different methods of condensing the volatile products via direct and indirect heat exchange, showing increased recovery of heavy ends for direct water-quenched cases. 41 However, the scope of this review is limited to the upstream pyrolysis chemistry, making downstream recovery outside the scope of this work.…”

Section: Mechanism and Kineticsmentioning

confidence: 99%

“…The stability of this mixture is a concern, because the mixture of hydrophobic and hydrophilic species can phase-separate, continue to react, and potentially damage equipment as a result of its inherent acidity . A number of experimental and modeling − studies have been performed over the years to unravel the complex reaction networks and predict the quantity and composition of the pyrolysis effluent. − Recent work has examined different methods of condensing the volatile products via direct and indirect heat exchange, showing increased recovery of heavy ends for direct water-quenched cases . However, the scope of this review is limited to the upstream pyrolysis chemistry, making downstream recovery outside the scope of this work.…”

Section: Mechanism and Kineticsmentioning

confidence: 99%

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Progress in Modeling of Biomass Fast Pyrolysis: A Review

Kostetskyy

Broadbelt

2020

Energy Fuels

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Fast pyrolysis of biomass is an important technology in the conversion of lignocellulosic feedstocks to value-added fuels and chemicals. Significant efforts have been dedicated to modeling of these processes to improve the viability of large-scale operation through reactor design, feedstock selection and processing, and optimization of operating conditions, among others. This work is a review of the current progress in the field of modeling of biomass fast pyrolysis processes across multiple length and time scales. Enclosed are summaries of the current state of the art in atomistic and kinetic modeling of biomass fast pyrolysis toward production of fuels and chemicals. Decomposition of aggregate biomass and its individual components was reviewed for models at various scales, highlighting important considerations. Recent applications of machine learning methods to couple multiscale phenomena with the goal of reducing computational complexity were also included. Historical context was provided for existing models and correlations, highlighting some of those most widely applied. Some of the shortcomings and bottlenecks in existing models were identified as areas for further study. Finally, potential future directions for the field are suggested with the goal of improving the viability and sustainability of pyrolysis processes and the applications of multiscale modeling toward this goal.

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Section: Mechanism and Kineticsmentioning

confidence: 99%

Section: Mechanism and Kineticsmentioning

confidence: 99%

Progress in Modeling of Biomass Fast Pyrolysis: A Review

Kostetskyy

Broadbelt

2020

Energy Fuels

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“…In the concept of the cloudy zone mentioned in introduction, liquid exists in the forms of liquid or liquid films, and hence a critical temperature may be used appropriately for the identification of the cloudy zone as a criterion. In the work of Dalluge et al, 16 pure cellulose was pyrolyzed in the fluidized bed, and the products were cooled in the heat exchange system. The temperature of the products after being cooled was lower than the dew‐point temperature of the bio‐oil, and therefore, the bio‐oil was recovered and collected.…”

Section: Resultsmentioning

confidence: 99%

Dynamic characteristics of the volatile cloudy zone in a gas–solid fluidized bed with hydrocarbon liquid spray

et al. 2021

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In a gas–solid fluidized bed with continuous hydrocarbon liquid spray, a volatile “cloudy zone” could be formed, defined as a dynamically steady liquid‐affected zone, including droplets, wet particles, and the gas which passes through the zone. A new flow pattern with the dynamic coexistence of cloudy zone and non‐cloudy zone (gas–solid zone), is accordingly established. The temperature, particle concentration, and particle velocity fields are measured in real‐time via infrared thermography and particle imaging velocimetry, respectively. Results show that the area and range of central position of the cloudy zone illustrate a heavier fluctuant trend with the increasing velocity of liquid spray, and the main frequency of area fluctuation is close to that of the bubble rising. Moreover, the particle concentration and particle velocity in the cloudy zone are lower than those in the non‐cloudy zone, breaking the conventional symmetrical distributions of hydrodynamic parameters of particles in a gas–solid fluidized bed.

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“…First, two counter-current spray condensers are placed in series which exploit the direct-contact heat exchange to maximize liquid yields due to the simultaneous transfer of heat and mass. In depth details of heat exchange mechanism are provided by Dalluge et al [15]. During the experiments, the temperature of the vapors leaving the condenser and the produced liquids were measured through thermocouples placed at the inlet and the outlet of each section.…”

Section: Condensation Unitsmentioning

confidence: 99%

Experimental study of fast pyrolysis vapors fractionation through different staged condensation configurations

et al. 2021

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The quality of biocrudes from fast pyrolysis of lignocellulosic biomass can be improved by optimizing the downstream condensation systems to separate and concentrate selected classes of compounds, thus operating different technological solutions and condensation temperatures in multiple condensation stages. Scientific literature reports that fractional condensation can be deployed as an effective and relatively affordable step in fast pyrolysis. It consists in a controlled multiple condensation approach, which aims at the separated collection of classes of compounds that can be further upgraded to bio-derived chemicals through downstream treatments. In this study, fractional condensation has been applied to a fast pyrolysis reactor of 1 kg h-1 feed, connected to two different condensation units: one composed by a series of two spray condensers and an intensive cooler; a second by an electrostatic precipitator and an intensive cooler too. Fast pyrolysis of pinewood was conducted in a bubbling fluidized bed reactor at 500 °C, while condensable vapours were collected by an interchangeable series of condensers. Using the first configuration, high boiling point compounds – such as sugars and lignin-derived oligomers – were condensed at higher temperatures in the first stage (100 – 170 °C), while water soluble lighter compounds and most of the water were condensed at lower temperatures and so largely removed from the bio-oil. In the first two condensing stages, the bio-oil water content remained below 7 wt % (resulting in 20 MJ kg-1 of energy content) maintaining about 43% of the liquid yield, compared to the 55% of the single step condensation runs. The work thus generated promising results, confirming the interest on upscaling the fractional condensation approach to full scale biorefinering.

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Comparison of direct and indirect contact heat exchange to improve recovery of bio-oil

Cited by 23 publications

References 26 publications

Progress in Modeling of Biomass Fast Pyrolysis: A Review

Progress in Modeling of Biomass Fast Pyrolysis: A Review

Dynamic characteristics of the volatile cloudy zone in a gas–solid fluidized bed with hydrocarbon liquid spray

Experimental study of fast pyrolysis vapors fractionation through different staged condensation configurations

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