(87b) Modular System for Converting Lignocellulose into Pyrolytic Sugars and Phenolic Oil

Easy Energy Systems and Iowa State University are collaborating on the design, construction, and demonstration of a 50 ton per day pyrolysis system based on modular manufacturing principles. The goal is to commercialize a system suitable for processing distributed resources of lignocellulosic biomass into pyrolytic sugars and phenolic oil. Success is premised on intensification of several processes and designing major unit operations and subsystems as modules that fit into standard ISO shipping containers. The modules are field assembled into a complete biomass processing plant at scales much smaller than once imagined for commercial production of cellulosic biofuels and biobased chemicals.

Processes to be intensified include: provision of energy to the pyrolysis process through autothermal operation; production of sugars through thermal deconstruction of plant polysaccharides; and anaerobic digestion of the aqueous phase produced during pyrolysis. In contrast to conventional pyrolysis in which oxygen is excluded from the reactor, autothermal pyrolysis adds air at equivalence ratio less than 10% (considerably lower than autothermal gasification, for example) to provide the enthalpy of pyrolysis without the need for external heat transfer equipment, greatly simplifying system design. Autothermal operation removes the heat transfer bottleneck in fast pyrolysis, increasing biomass throughput by several fold compared to conventional pyrolysis in a similarly sized reactor. Pyrolysis sugars are levoglucosan (a dehydrated form of glucose) from cellulose and principally xylose from hemicellulose. Although sugar yields from pyrolysis of lignocellulosic biomass is normally very low, a simple pretreatment prior to pyrolysis enhances sugar production several fold. The sugar is recovered as a syrup contaminated with phenolic monomers. The syrup is cleaned with a resin adsorption filter, which allows its use as fermentation substrate. The phenolic oil, derived from lignin in the biomass feedstock, has several applications. It can be cured to a solid known as Lignocol, which has applications as a renewable fuel substitute for coal in electric power generation. It can also be emulsified with diesel fuel or dissolved in ethanol to produce a low-viscosity fuel oil suitable for small-scale power generation. With suitable hydroprocessing the phenolic oil can also be converted into renewable gasoline and diesel fuel. The aqueous phase is anaerobically digested to bio-methane after removal of fermentation inhibitors.

This presentation will describe pilot-scale tests and design activities to support construction of the 50 ton per day demonstration plant in 2018.