An Integrated Biorefinery Pilot Plant

We offer a proprietary two-stage gasification technology for carbonaceous feedstock such as woody biomass, agricultural waste, Municipal Solid Waste (MSW) and young coals that has some unique attributes: production of a medium calorific value syngas, ability to dial in the H2 to CO molar ratio to match the synthesis reaction step for biofuels and/or biochemical production, feedstock flexibility, generation of the highest syngas flow for synthesis reaction due to the indirect heating method, and opportunity for superior thermal and process integration.

In order to validate and demonstrate the technology and generate scalable data that confirms the design and warrant the commercial system, we initially proposed to design and build a pilot plant gasification and gas cleanup system. Later, with a first commercial product target of Fischer-Tropsch (F-T) liquids it was realized that the pilot plant needed to represent and include every single unit operation envisaged in the commercial system for technology success. Therefore, we designed, constructed, commissioned and performed trials at an integrated biorefinery pilot plant at Durham, NC. This plant is designed to process 4 dry tons per day of carbonaceous feedstock, generate, clean up, compress and condition syngas, and catalytically convert it to F-T liquids. It comprises the following sub-systems: feedstock storage and feed system, gasification system, primary gas cleanup system, secondary gas cleanup and conditioning system, synthesis reactor system and a Regenerative Thermal Oxidizer (RTO). The feed system is capable of feeding a wide range of feedstocks. The gasification system uses proprietary indirectly heated gasification technology. The synthesis reactor is an Emerging Fuels Technology (EFT) F-T reactor with their proprietary cobalt catalyst to produce fuels and waxes. The PDU is designed to be integrated to any number of alternate downstream catalytic or fermentation processes to produce fuels and chemicals from syngas. Feedstocks tested to date include woody biomass, agricultural waste, switch grass and MSW.

The feed system and gasifier have operated for more than 8,000 h, and the pilot plant has operated in the fully integrated mode, generating F-T products for 2,800 h, all on woody biomass. The trials have demonstrated clean syngas production with stable H2 to CO molar ratio (~1.9), 60+% CO conversion in a single stage of F-T and the generation of high quality, sulfur-free, 100% renewable fuels i.e. pure white wax and water clear, medium fraction hydrocarbon liquids.

Many challenges were encountered in design, equipment selection, instrumentation, installation, commissioning, shakedown and operation. Standard engineering tools such as computer-aided engineering, design review, Hazop analysis, project management, quality control and root cause analysis were utilized to successfully complete the tasks. This story or experience from idea to results will be presented.