Characteristics And Mechanism Analysis Of Fluidized Bed Pyrolysis Of Two Typical Solid Wastes

The pyrolysis characteristics and thermal conversion mechanism of waste printed circuit boards and soapstock in a fluidized bed pyrolyser were studied.The transfer characteristics of key pollutants during pyrolysis were discussed.The basic process parameters of the fluidized bed were obtained by the comparison of characteristics of the two different wastes in fluidized bed pyrolysis.（1）250～380℃ was the main weight loss range of WPCBs pyrolysis,The weight loss was largest when K₂CO₃ was added,and the order was K₂CO₃>ZnO>CaO>Fe₂O₃.Pyrolysis products by Py-GC/MS could be divided into benzenes,phenols,bromophenols,bromobenzenes and oxygenated benzenes.Phenol,p-bromophenol,2,6-2 bromophenol,2,4,6-3 bromophenol and 2,4-Bis（dimethylbenzyl）-6-t-butylphenol were the main compounds.K₂CO₃ and CaO had better Br fixation ability,followed by ZnO.Fe₂O₃ had poor Br fixation ability,however,it could catalyze the fracture of organic matters better.In fluidized bed pyrolysis,the content of phenols was 82～91%,which mainly included tetrabromobisphenol A,phenol and m-isopropylphenol.Br was mainly distributed in pyrolysis oil in the form of inorganic-Br.Br·reacted with metal ions to form bromine salts that retained in pyrolysis char.（2）The sequestration efficiency of C in soapstock char was nearly 50%at>600℃,N was mainly distributed in soapstock char and soapstock oil,P and S were fixed in soapstock char.soapstock oil could be classified into alkanes,alkenes,aromatics and oxygenates.The content of hydrocarbons was 20～40%,oxygenates was60～76%,and benzenes was<8%.O was removed in the form of CO₂,CO and H₂O.Soapstock pyrolysis process could be divided into three stages,the main cracking reaction occurred in stage II.Ca delayed the pyrolysis reaction of fatty acids,which could lead to higher energy requirement in actual production,however,it promoted decarboxylation which was the main deoxygenation pathway.（3）Compared with the two solid wastes,the yield of pyrolysis char was stable at>600°C,the yield of pyrolysis oil reached the maximum at600～700°C.The gas yield increased at>700°C.Oxygenates tended to form alcohols and ketones.There were similar functional groups in pyrolysis char such as O-H,C-H and C-O.