Process Design and Economics for the Conversion of Lignocellulosic Biomass to Hydrocarbon Fuels: Thermochemical Research Pathways with In Situ and Ex Situ Upgrading of Fast Pyrolysis Vapors

Abstract

The dry basis elemental composition of the feedstock, shown in Table 2, is identical to previous NREL and PNNL design reports [20,21]. The composition was originally assumed to come from pulpwood. Recent feedstock logistics work at the Idaho National Laboratory (INL) suggests that the use of blended material may be required to meet a cost target of $80/dry U.S. ton while still meeting these specifications [22]. For the purpose of this report, it is assumed that any blended material provided to meet this feedstock elemental composition will not adversely affect fast pyrolysis conversion efficiencies. Ongoing studies being conducted jointly by INL, NREL, and PNNL will provide experimental evidence of the impact of blended feedstocks on fast pyrolysis and gasification processes. Future TEA will be modified to reflect conversion impacts inferred from such studies.This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. not considered in this design in order to focus on the core technology of in situ and ex situ fast pyrolysis vapor upgrading. Aspen Plus ModelAn Aspen Plus Version 7.2 simulation was used as the basis for this report. Since the products in pyrolysis are numerous and varied, only selected model compounds were used to represent the product slate. Additional hydrocarbon species were added to represent hydroprocessing products. Many of the desired molecular species in the desired boiling ranges for light and heavy fractions did not exist in Aspen Plus databanks and physical property parameters needed to be estimated. The biomass feedstock, ash, char, and coke were modeled as non-conventional components. Appendix F provides information about compounds selected to represent the process. The Peng-Robinson with Boston-Mathias modifications (PR-BM) equation of state was used throughout most of the process simulation. The ASME 1967 steam table correlations (STEAM-TA) were used for the steam cycle calculations. Combustor/Regenerator Temperature, °C (°F) 650 (1,202) 720 (1,328) 650 (1,202) Pressure, psia (bar) 117 (8.1) 117 (8.1) 113 (7.8) Excess air (%) 20 20 20 Solids temperature before transfer to reactor, °C (°F) 650 (1,202) 720 (1,328) 341 (645) No. of cyclones per combustor 2 2 2 Area 200 Equipment Cost EstimationsCapital costs for the equipment in this area were estimated by Harris Group. A previously developed spreadsheet tool for gasifier costs was leveraged for this exercise. Cost estimates from this tool were compared with order of magnitude estimates from technology vendors and documented in Appendix I of Worley et al.

Conceptual Process Design and Techno-Economic Assessment of Ex Situ Catalytic Fast Pyrolysis of Biomass: A Fixed Bed Reactor Implementation Scenario for Future Feasibility

“…2. The hot gas filter (HGF) and fixed bed reactors were added, replacing the fluidized bed system in the design report [5]. Detailed discussions for these additions are provided in following sections, including a discussion of catalyst options.…”

“…Detailed discussions for these additions are provided in following sections, including a discussion of catalyst options. Brief descriptions of the other process areas are included below; the interested reader can find further information in the detailed design report [5]. Process conditions are provided in Table 1 with further details in Table B1 in the supplementary material.…”

“…Further details can be found in a detailed report by the Idaho National Laboratory [6]. As mentioned in the design report [5], experimental verification of the performance of this feedstock in specific processes is a necessity.…”

“…These process configurations were detailed in a recent design report led by the National Renewable Energy Laboratory (NREL) [5]. A circulating fluidized bed configuration, using metal-modified acidic zeolite (HZSM5) as the catalyst, was the basis for the ex situ vapor upgrading reactor in that study.…”

“…The results from this work identify the trade-offs between circulating fluidized bed and fixed bed systems, provide guidance for selection of process operating conditions, highlight existing research gaps, and provide insight on catalyst development for ex situ upgrading. [5]. Configuration c is the subject of this study Top Catal (2016) 59:2-18 3 2 Process Design and Techno-Economic Assessment…”