| Bio-oil is a liquid production from fast pyrolysis of biomass. Compared to biomass itself, bio-oil is more convenient to be transferred and has higher energy densities. But it also has some disadvantages to utilize bio-oil directly in many fields, because of its high oxygen and moisture contents, complex compositions and instability. Nowadays, researchers pay much attention to utilizing syngas from bio-oil gasification because syngas can be widely used in Fischer Tropsch synthesis. However, there are also a lot of work on bio-oil gasification to do in China. In this work, some experiments have been conducted to explore the effects of different conditions on product distribution from fast pyrolysis, especially we considered the yield of bio-oil. On the other hand, we also studied the characteristic of bio-oil gasification and the gas quality in many conditions.Two kinds of pyrolysis style have been conducted to study the characteristic of straw in this work:one was one-stage fast pyrolysis, and another was solid heat carrier pyrolysis. In one-stage pyrolysis, the effects of pyrolysis temperature, particle size and flow rate of N2 on products distribution were investigated, and the composition of bio-oil was analyzed by GC-MS. The results showed that modest temperature and smaller particle size were beneficial for getting the highest yield of bio-oil, and the effect of flow rate of N2 on bio-oil production was not obvious, respectively. The highest yield of bio-oil was obtained when the pyrolysis temperature was 450? and particle size was less than 0.5 mm. In the solid heat carrier pyrolysis, the effects of temperature of solid heat carrier, particle size and heat carrier size were studied. The best yield of bio-oil was achieved when the heat carrier temperature was 700? and particle size of straw and solid heat carrier was less than 0.5 mm. Compared with one-stage pyrolysis, the lower yield of char and higher yield of gas were gained in the solid heat carrier pyrolysis.The bio-oil gasification experiments were conducted in a two-stage reactor with a fixed bed pyrolyzer and a fixed bed gasifier. Firstly, the effect of temperature on bio-oil gasification in N2 atmosphere was investigated and the results showed that the yield of bio-oil would decrease rapidly with increasing temperature. The yield of bio-oil decreased from 19.8% to 11.0% with the temperature increased from 450? to 850?. Accordingly, the yield of gas increased from 10.5% to 34.1%, yield of H2+CO from 41.3 mL/g to 170.2 mL/g, the gas calorific value from 10.47 MJ/m3 to 19.14 MJ/m3, and the total volume fraction of H2+CO was about 65%.In the oil shale ash catalytic gasification experiments, the effects of temperature, ash size, amount of ash and different compounds were investigated. The results showed that the yield of bio-oil was lower than 1% when temperature was 850?, yield of H2+CO was 200 mL/g with the yield of H2 as twice as that in thermal cracking. With the amount of ash increasing, the ratio of H2/CO was increased but the mass yield of syngas was decreased. The chemical compositions in ash played an important role in bio-oil gasification. Fe2O3 would benefit the H2 production but consume CO, hence resulting in higher ratio of H2/CO. When water was used in the ash catalytic gasification, the highest yield of syngas and ratio of H2/CO were found as 231.8 mL/g and 1.77, respectively.Using simulative biomass syngas as the raw material, the process of syngas methanation reaction were conducted in a fixed bed reactor. The results showed that with the increasing of temperature, the conversion of CO increased firstly than decreased and the rule of CH4 formation was the same. |
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