Biomass catalytic fast pyrolysis can produce aromatics and olefins, which are used as petrochemicals. However, the yields of aromatics and olefins are still very low. In this work, catalytic co-pyrolysis of pine sawdust and plastics (polyethylene, polypropylene, and polystyrene) was conducted in a fluidized-bed reactor to improve the yields of aromatics and olefins. The effects of different temperatures, polyethylene/pine sawdust ratios, different catalysts, and plastics on the product distributions were studied. The results show there are some positive synergistic effects between the two feedstocks. The maximum carbon yield of petrochemicals (71%) was obtained at 600 °C with a spent fluidized catalytic cracking (FCC) catalyst and polyethylene/ pine sawdust ratio of 4:1. LOSA-1 presents better catalytic performances than Al 2 O 3 and spent FCC catalysts. The petrochemical carbon yield with LOSA-1 is almost 2 times that without catalyst. Catalytic co-pyrolysis of polystyrene and pine sawdust produced the highest and lowest yields of aromatics (47%) and olefins (11.4%), respectively.
A high-flux circulating fluidized bed coal gasifier cold model which consists of a vertical riser (0.06m-I.D.×5m-high), two downcomers (0.04m-I.D.×3.5m-high and 0.1m-I.D.×3m-high), an inertial separator, a cyclone and two solid feeding devices were established. Geldart group B particles with mean diameters of 140 ?m and densities of 2700 kg/m3 were used as bed materials. Flow behaviors were investigated with the solid mass flux ranges from 108 to 395 kg/m2 and the superficial gas velocity ranges from 7.6 to 10.2 m/s. The pressure drop, apparent solids holdups, average slip velocity and solids-to-air mass flow ratio under different operating conditions were obtained. The results showed that the riser total pressure drop increased sharply with bed height in the low elevation but slowly in the high elevation, since the solids holdup was higher in the low region than that in the high region. The solids holdup increased with the increasing of solids mass flux while it decreased with increasing superficial gas velocity. A dense suspension upflow flow (DSU) structure was found only existing in the low elevation while the rest upper region was still in the dilute phase, and the length of DSU flow structure increased with solids mass flux. The average slip velocity was found to be the strong function of apparent solids holdup; increasing apparent solids holdup leads to the increase of slip velocity. The riser total pressure drop and apparent solids holdup increase with the solids-to-air mass flow ratio.
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