Process Simulation and Cost Analysis for Removing Inorganics from Wood Chips Using Combined Mechanical and Chemical Prep
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Process Simulation and Cost Analysis for Removing Inorganics from Wood Chips Using Combined Mechanical and Chemical Preprocessing Hongqiang Hu 1 & Tyler L. Westover 1 & Robert Cherry 1 & John E. Aston 1 & Jeffrey A. Lacey 1 & David N. Thompson 1
Published online: 3 October 2016 # The Author(s) 2016. This article is published with open access at Springerlink.com
Abstract Inorganic species (ash) in biomass feedstocks negatively impact thermochemical and biochemical energy conversion processes. In this work, a process simulation model is developed to model the reduction in ash content of loblolly logging residues using a combination of air classification and dilute-acid leaching. Various scenarios are considered, and it is found that costs associated with discarding high-ash material from air classification are substantial. The costs of material loss can be reduced by chemical leaching the high-ash fraction obtained from air classification. The optimal leaching condition is found to be approximately 0.1 wt% sulfuric acid at 24 °C. In example scenarios, total process costs in the range of $6–9/dry tons of product are projected that result in a removal of 14, 62, 39, and 88 % of organics, total ash (inorganics), alkaline earth metals and phosphorus (AAEMS + P), and silicon, respectively. Sensitivity analyses indicate that costs associated with loss of organic material during processing (yield losses), brine disposal, and labor have the greatest potential to impact the total processing cost.
Keywords Biofuels . Air classification . Leaching . Ash reduction . Technoeconomic analysis
Electronic supplementary material The online version of this article (doi:10.1007/s12155-016-9794-3) contains supplementary material, which is available to authorized users. * Tyler L. Westover [email protected]
1
Idaho National Laboratory, 2525 Fremont Ave, Idaho Falls, ID 83415, USA
Introduction Lignocellulosic biomass from agricultural residues, forest residues, urban wastes, and dedicated energy crops are recognized as renewable and sustainable energy sources that can be converted to liquid fuels, heat, and power through biological, chemical, and thermal conversion processes [1, 2]. Approximately 500 million dry tons of residues and energy crops are available annually in the USA, and this quantity could increase to more than a billion dry tons by 2030 [3]. Inorganic species, whether physiological or exogenously introduced, are a notable component of biomass resources and are often referred to as ash. Thermochemical and biochemical conversions can both be affected by ash, although differently. During fast pyrolysis, alkali metals and alkaline earth metals catalyze the degradation of biomass to gaseous products and decrease oil yields. Several studies have correlated increasing content of alkali and alkaline earth metals (AAEMs), including potassium, sodium, calcium, and magnesium, with decreasing oil yield [4–6]. Inorganic species can also poison or foul catalysts that promote the conversion of biological carbon to oil and also pr
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