Study on dechlorination technology for municipal waste plastics containing polyvinyl chloride and polyethylene terephthalate

Abstract

It is necessary to remove chlorine effi ciently from municipal waste plastics (MWP) that contain polyvinyl chloride (PVC) and other plastics containing chlorine. In this article we consider thermal degradation liquefaction technology. In Japan, the chlorine content of reclamation oil products must be kept below 100 ppm owing to the quality standard for pyrolysis oil. Liquefaction dechlorination technology for MWP is still an important issue to study. The twin-screw extruder that has been developed as dechlorination technology for blast furnaces and coke ovens has a shorter residence time for dechlorination than other dechlorination technologies. In this article, we used a single-screw extruder for the dechlorination process because it also has a short residence time. Experiments on the dechlorination process were carried out by using a single-screw extruder to assess its dechlorination performance. Practical use of the single-screw was demonstrated by the operation of a commercial oil reclamation plant operated by Sapporo Plastic Recycle Co., Ltd. (SPR). Moreover, an investigation of cascade recycling was carried out in 2008 in which material recycle wastes were mixed with MWP and processed by chemical recycling (liquefaction). It was demonstrated that cascade recycling is an effi cient recycling combination and contributes to local feedstock recycling. However, it was shown that MR wastes affect the quality of the reclamation oil when they make up more than 40% of the feed mix. If the quantity of MR wastes is kept below 40%, the reclamation oil is able to meet the quality standard. The SPR plant can be operated safely and in a stable manner.

Waste Polyolefins to Liquid Fuels via Pyrolysis: Review of Commercial State-of-the-Art and Recent Laboratory Research

“…They found that a single screw extruder can sufficiently dechlorinate waste plastics to meet the 18 strict CPRL standards [6]. Nonetheless some technical challenges remain like corrosion and generation 19 of metallic oxides which clog pipes, strainers and heat exchangers.…”

“…Therefore 15 it is proposed that this fraction would be mixed with the concentrated MPW stream and pyrolysed. The 16 resulting pyrolysis products can then be upgraded in a refinery generating standard refinery products 17 [6]. 18 The first attempts to produce liquid fuels from plastic occurred during the mid 70's and early 80's [7].…”

Feedstock Recycling <i>via</i> Waste Plastic Pyrolysis

“…Pyrolysis allows the avoidance of solvent use, but PET produces high boiling point organic acids such as terephthalic acid (TPA) and benzoic acid (BA), along with a large amount of carbonaceous residues during pyrolysis 98) 101 ) , which cause corrosion and clogging of the treatment facilities 58 ) . FeOOH catalysts decompose these sublimating products into acetophenone, benzene, and phenol rich oils 102), 103 ) .…”

Feedstock recycling of waste polymeric material

“…Fukushima et al [70] carried out the dehydrochlorination of MSW using a single screw extruder. At a temperature of about 360°C, the chlorine content was successfully reduced to less than 0.5 wt% in 2 min.…”