Project No: FE0005476
Performer: Virginia Polytechnic Institute and State University


Contacts

Jenny Tennant
Coal and Coal/Biomass to Liquids Technology Manager
National Energy Technology Laboratory
3610 Collins Ferry Road
P.O. Box 880
Morgantown, WV 26507-0880
304-285-4830
jenny.tennant@netl.doe.gov

Steven Markovich
Project Manager
National Energy Technology Laboratory
626 Cochrans Mill Road
P.O. Box 10940
Pittsburgh, PA 15236-0940
412-386-7537
steven.markovich@netl.doe.gov

Francine Battaglia
Principal Investigator
Virginia Polytechnic Institute and State
University
Mechanical Engineering
100 Randolph Hall
Blacksburg, VA 24061
540-231-0077
fbattaglia@vt.edu

Duration
Award Date:  10/01/2010
Project Date:  09/30/2015

Cost
DOE Share: $999,888.00
Performer Share: $252,504.00
Total Award Value: $1,252,392.00

Performer website: Virginia Polytechnic Institute and State University - http://www.vt.edu

Advanced Energy Systems - Coal and Coal/Biomass to Liquids

Investigation of Coal-Biomass Catalytic Gasification Using Experiments, Reaction Kinetics and Computational Fluid Dynamics

Project Description

The proposed work is a collaborative effort involving experiments, kinetic modeling, and computational fluid dynamics that incorporates efficient methods for solving complex heterogeneous chemistry. The goal is to determine the key reactive properties for coal-biomass mixed fuels. To achieve this goal, sub-bituminous coal will be mixed with biomass feedstocks of hybrid poplar wood, switchgrass, or corn stover and catalysts added to lower the gasification temperatures, thereby improving the gasification process. The outcome of this research will be characterization of the chemical kinetics and reaction mechanisms of the co-gasification fuels and development of a set of models that can be integrated into other modeling environments. Finally, the reaction kinetics modeling will be implemented into NETL’s multiphase flow code—Multiphase Flow with Interphase Exchange (MFIX)—to efficiently simulate the chemistry and recommendations will be made regarding fluidization characteristics.

SEM photograph of biomass char from pyrolysis of oak wood without catalyst
(Source: Virginia Tech). 

SEM photograph of biomass char from pyrolysis of pine with catalyst
(Source: Virginia Tech).


Program Background and Project Benefits

The Department of Energy (DOE) is committed to supporting research focused on making use of the nation's coal and biomass resources. The Coal and Coal Biomass to Liquids (C&CBTL) Technology Program at DOE's National Energy Technology Laboratory (NETL) is developing advanced technologies to remove technical barriers that will foster the commercial adoption of coal and coal/biomass gasification technologies for the production of affordable hydrogen and liquid fuels (such as gasoline, diesel, aviation, and military fuels). The hydrogen can be used in advanced systems for efficient power generation produced with near-zero emissions and with the potential to significantly reduce greenhouse gas emissions. The synthesis gas (syngas) produced by the gasification of coal and coal/biomass mixtures can be converted by chemical processes to generate clean liquid hydrocarbon fuels. To successfully complete the development of C&CBTL technologies from the present state to the point of commercial readiness, the C&CBTL Program efforts are focused on two Key Technologies: (1) Coal/Biomass Feed and Gasification, and (2) Advanced Fuels Synthesis.

The Coal and Coal Biomass to Liquids Key Technology is advancing scientific knowledge of the production of liquid hydrocarbon fuels from coal and/or coal-biomass mixtures. Activities support research for handling and processing of coal/biomass mixtures, ensuring those mixtures are compatible with feed delivery systems, identifying potential impacts on downstream components, catalyst and reactor optimization, and characterizing the range of products and product quality from the fuels conversion processes. Liquid fuels produced from coal/biomass feedstock not only reduce the nation’s dependency on foreign oil but also are cleaner burning than comparable petroleum products.

This Virginia Polytechnic Institute and State University project will use experimental reactor data to develop kinetic rate expressions for pyrolysis and char gasification for the coal-biomass blends under conditions free from transport limitations to develop a detailed understanding of the effect of pyrolysis conditions on the porous char structure.  The impact of this project will be to develop a cost-effective gasification-based CBTL process to produce renewable liquid fuels that will provide diversity of fuel supply and energy security while resulting in lower future capital and operating costs. Specifically, this project will build mathematical models that combine true kinetic rate expressions with transport models for predicting gasification behavior for a broad range of pressures and temperatures, and investigate the physical and chemical parameters that might lead to synergistic effects in coal-biomass blends gasification.

Project Scope and Technology Readiness Level

Gasification experiments will be conducted in bench-scale (2-inch diameter) and pilot-scale (4-inch diameter) fluidized bed reactors under a range of temperatures and atmospheric pressure. Several acidic catalysts, including nickel, will be used catalysis?ed gasification temperatures a byproduct of the n temperatures?to lower gasification temperatures during the pyrolysis reaction. Slag formation also will be examined. Researchers will analyze the composition of the fuels, which will guide the development of the detailed reaction kinetics models. The molecular kinetic modeling will be used to identify the important reaction pathways and convert the molecules to a set of attributes that provide the molecular detail needed to convert those attributes into a set of equations describing the chemical reaction occurring in the system. A reaction module will be coupled with CHEMKIN, a software tool for solving complex chemical kinetics problems, and built using the equations that describe the co-gasification process. Decoupling the transport and chemical source terms using a fractional step approach will provide an efficient method for solving the complex chemistry. Finally, MFIX will be coupled with an efficient reaction module to provide an excellent computational fluid dynamics tool for analyzing co-gasification, providing valuable information related to fluidization characteristics (including mixing and segregation), and supporting gasifier design.

The Technology Readiness Level (TRL) assessment identifies the current state of readiness of the key technologies being developed under the DOE’s Clean Coal Research Program. In FY 12, this project was assessed a TRL of 3.

The TRL assessment process and its results including definition and description of the levels may be found in the "2012 Technology Readiness Assessment-Analysis of Active Research Portfolio".


Accomplishments

The research team has pyrolyzed/gasified biomass under different atmospheres and studied coal/poplar mixtures under different pressures and temperatures in the two-inch fluidized bed reactor. The yields were determined gravimetrically by weighing the coal-biomass mixed fuels used in the reactor before and after each experiment before and after each experiment. Preliminary results indicate that there is a component in the poplar wood that may be increasing the projected gasification yield. Work to determine the effect of CO2 on these reactions is ongoing. Under the modeling task, the reaction kinetics and mechanisms have been determined and researchers are ready to progress to the final phase of model investigation.  The MFIX code is being developed for parallel processing of the coal portion of the coal and biomass reaction. The model has been developed and is being validated. Researchers continue to simulate the biomass portion of the reaction.