Recycling of waste plastics by ultrapyrolysis using an internally circulating fluidized bed reactor

The recycling of plastic waste through pyrolysis offers great potential for dealing with this problematic waste stream. Previous work on the ultra-rap id pyrolysis of polyethylene in a micro-scale reactor indicated that reacto r residence time is an important consideration in optimizing product yield. A pilot-plant scale internally circulating fluidized bed (ICFB) reactor, c apable of achieving the residence time required for the high yield conversi on of waste plastics to olefins, has been investigated. The pyrolysis of lo w density polyethylene (LDPE) was studied at temperatures ranging from 780 to 860 degrees C and residence times of 400-600 ms. Total gas yields in exc ess of 90 wt.% were achieved with total olefin yields as high as 75 wt.%, d emonstrating the effectiveness of the ICFB reactor as a means of waste plas tics recycling. (C) 1999 Elsevier Science B.V. All rights reserved.