Contaminants removal by hot vapour filtration
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Journal Title
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Kemian tekniikan korkeakoulu |
Master's thesis
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Authors
Date
2019-10-22
Department
Major/Subject
Biomass Refining
Mcode
CHEM3021
Degree programme
Master's Programme in Chemical, Biochemical and Materials Engineering
Language
en
Pages
68+8
Series
Abstract
Ongoing interest in producing high quality fast pyrolysis oil is the drive behind this subject. This thesis is set to investigate the separation of solids contaminants by incorporating a hot vapour filter in a bench-scale (1kg/h) fast pyrolysis setup. The hot filter consists of ceramic candles and moving granules for filtration and cake regeneration purposes, respectively. Qualitative and quantitative analysis of pyrolytic products have been carried out; to investigate the influence of different filtration temperatures. Furthermore, upscaling and integration of the hot filter with an existing pilot-scale plant have been studied. Recycled wood containing solid contaminants, alkali and alkaline earth metals (AAEM) was pyrolysed in a bubbling fluidised-bed reactor. The optimum pyrolysis temperature for recycled wood was 500 °C, which resulted in a maximum organic yield of 55 wt. % on dry basis. Incorporating the hot filter led to significant reduction in organic yield. Among the tested filtration temperatures, 360 °C was the optimal temperature yielding 48 wt. % of organics on dry basis. Filtered bio-oil exhibited lower alkali and alkaline earth metals than unfiltered bio-oil. Furthermore, filtered bio-oils demonstrated better stability during storage. However, despite the low solids content and the reduction of AAEM, ageing reactions continued to develop during storage, but at a lower rate than unfiltered bio-oil. Constant differential pressure across the hot filter was maintained during 6 h run at 360 °C; implying an efficient regeneration of char cake over filtration candles. Moving granules break down the accumulated chars over the ceramic surface, and act as filtration media for particle-laden vapours. Upscaling of hot filter and its integration with a circulating fluidised-bed is considered at the end of the study. Preliminary design of pilot filter is based on a calculated face velocity of 2.03 cm/s. Such a scalability study is necessary to evaluate the viability of the technology at a large scale.Description
Supervisor
Alopaeus, VilleThesis advisor
Lindfors, ChristianKeywords
fast pyrolysis, hot vapour filtration, bio-oil, contaminants, alkali and alkaline earth metals, upgrading technology