Mobile demonstration unit for fast- and catalytic pyrolysis: The combustion reduction integrated pyrolysis system (CRIPS)

摘要

A mobile pyrolysis unit, designed to process biomass at a rate of 83.3 kg h(-1) (two metric tons per day, MTPD) has been developed, constructed and its operation demonstrated for on-farm or in-forest production of pyrolysis oil (bio-oil). The trailer-mounted pyrolysis apparatus is based on the combustion reduction integrated pyrolysis system (CRIPS), a patented, dual fluidized bed, biomass pyrolysis design developed by USDA and the University of Pretoria. The mobile design goal was to demonstrate efficacy of on-farm production and coordinate station-to-station operation to simulate a collective system of several unit operations within a distributed/satellite system of pyrolysis biorefinery. Key design features that provide utility for remote operations including in-situ (on-trailer) generation of heat and electric power required for self-sufficiency were tested at this scale. Extensive trials on three feedstocks important to US agriculture, namely woody biomass, switchgrass and horse litter, were conducted. The results show that a processing rate of up to 40 kg h(-1) (approximately 1 MTPD) was successful and easily achievable for the said biomass on the trailer; however, beyond this rate operational problems such as pressure imbalances between the dual-bed reactors were encountered, hampering process control. The operation of the CRIPS under catalytic pyrolysis conditions was also successful with catalyst regeneration readily achievable with the design. Bio-oil yield for neat/traditional and catalytic pyrolysis were in the 45% and 5-10% ranges respectively, similar to lab scale, demonstrating production of large volumes of bio-oil on-farm. Bio-oil quality for catalytic pyrolysis was consistent over several hours on stream due to continuous catalyst regeneration that the design affords yielding high levels of BTEX compounds; however, deactivation due to alkali contamination was noticeable at cumulative biomass to catalyst ratios of 6/1. Compared with laboratory scale results, non-catalytic pyrolysis product quality for the demonstration scale wavered between that of regular pyrolysis oil produced under nitrogen atmosphere and that of the tail-gas reactive pyrolysis (TGRP) as partial recycle of effluent gas was possible with the mounted CRIPS design. With successful demonstration at 1 MTPD capacity the mobile system meets the technology readiness level for pre-commercial design suggested for blueprints (i.e. development of full-scale prototype), however more testing is underway to remove the bottlenecks impeding operation at the full-scale design.