| Summary: | 碩士 === 逢甲大學 === 環境工程與科學所 === 100 === This study investigated the feasibility of enhanced energy yield and bio-oil production in a catalytic pyrolysis of sewage sludge by controlling different particle size (ranged between 0.3 mm and 2.0 mm) and catalysts addition ratio (0%~15%) in a batch fixed-bed system .The experiments were conducted by controlling the pyrolysis temperature at 500℃ and adding Fe/Mn sludge derived from drinking water treatment plant used as a tested catalyst. The experimental results indicated that the bio-oil production increased from 13.44 wt.% to 15.96 wt.% with an decrease in particle size of sewage sludge from 0.8~2.0 mm to 0.3~0.5 mm. Based on the results of energy density, the energy density of bio-oil was also slightly increased from 0.74 to 0.79. It can concluded that reducing particle size of sewage sludge can promote the efficiency of pyrolysis reaction and enhance the energy yield and energy density of bio-oil
In the case of larger particle size range (0.8 mm~2.0 mm) and adding Fe/Mn sludge catalyst, the Fe/Mn sludge could act as a catalyst to promote the efficiency of char conversion, but also reduce bio-oil yield. This is because large amounts of gaseous products generated by the secondary pyrolysis of bio-oil. The bio-oil production decreased from 13.44 wt.% to 10.97 wt.% with Fe/Mn sludge addition increasing from 0 wt.% to 15 wt.%. However, in the case of smaller particle size range (0.3 mm~0.5 mm), the bio-oil production increased from 15.96 wt.% to 16.09 wt.% with an increase in Fe/Mn sludge addition. In addition, the energy density of bio-oil was insignificantly influenced by adding Fe/Mn sludge. In summary, in the case of larger particle size of sewage sludge, the catalyst addition effects on the bio-oil yield in catalytic pyrolysis were relatively significant. That is, in the case of smaller particle size of sewage sludge, the particle size effects on bio-oil yield more important than that of catalysts addition.
According to the characteristic results of bio-oil, the H/C and O/C ratio of bio-oil were ranged from 1.48 to 1.66 and from 0.09 to 0.26, respectively. The ageing potential of the bio-oil could be higher due to the bio-oil containing higher oxygen content. The tested catalyst can reduce the viscosity of bio-oil, but also the viscosity of bio-oil decreasing with an increase in catalyst addition. In the case of 15% catalyst addition, the viscosity of light bio-oil was ranged between 491 cP and 734 cP. It can comply with current criteria of diesel fuel and fuel oil. Based on the analysis results of functional groups of bio-oil, the tested catalyst can decrease the yield of oxygenated and cyclic compounds of light bio-oil. Meanwhile, the tested catalyst could also promote cyclic compounds to convert into chain compounds of heavy bio-oil. In addition, the tested catalyst can enhance aliphatic compounds content and decrease contents of nitrogenous, oxygenated compounds and/or aromatic compounds in bio-oil. Therefore, the Fe/Mn sludge used in this research can act as a usable catalyst that it can help upgrade the bio-oil in pyrolysis of sewage sludge.
|
|---|
