Synergistic Effects in Steam Gasification of Combined Biomass and Plastic Waste Mixtures

摘要

Steam gasification of combined biomass and plastics at different biomass to plastic mass ratios was investigated in a semi-batch reactor at 1173 K and atmospheric pressure using different types of plastics. The specific plastics examined were: black polycarbonate (BPC), polyethylene-terephthalate (PET), and polypropylene (PP). Synergistic effects were observed in the product gas yields and their composition, which were measured using a microGC. Such synergy was quantified by comparison of cumulative gas yields with their corresponding weighted aggregate results from the gasification of separate feedstock components. While the total syngas, H_2, CO, and CO_2 yields were enhanced using mixtures, the light hydrocarbon gas yields reduced with net reduction in the increasing order of PP, BPC and PET. The increase of H_2 and CO with the reduction in hydrocarbon yield revealed the synergistic enhancements from the secondary steam reforming reactions. The carbon conversion and energy efficiency results revealed no inhibitive effects for any of the plastics examined, except for the case of BPC, which increased. The absence of loss in efficiency with increase in product gas grade suggests further studies are required on both fundamental reaction mechanisms along with demonstrative gasifier studies to understand the kinetics and feasibility issues, respectively. The investigations of such mixtures is essential to support the biomass gasification plants in the presence plastics in wastes as all waste feedstock often contain such materials.