Economic Evaluation of Small Liquefaction Plants for Waste Plastics.

In Japan, the recycling rate of waste plastics by conversion into oil is less than 1%, suggesting inadequate performance of available liquefaction plants in view of the current economic and political demands. The capacities and costs of plants developed between 1990-2000 were investigated. The reactors of most small plants are the batch type. Only a few flow type reactors are currently in operation. The capacity of each plant for converting waste plastics to oil is generally less than 1.5 ton/day. The treatment capacity of tank reactors is less than 1.0 ton/day. The plastic treatment cost of each plant and the plastic treatment capacity were calculated to evaluate commercial operation producing fuel oil from waste plastics. The estimates showed that operation by a flow reactor process would run at a profit of (+)Y23.5/kg for a plant with a capacity of 2.4 ton/day (construction cost 50 million yen). In contrast, operation by a batch reactor process would result in a loss of (-)Y38.1/kg and (-)Y7.8/kg in the cases of plant capacity of 1.0 ton/day (construction cost 70 million yen) and 1.5 ton/day (construction cost 80 million yen), respectively. A small profit would result from running a batch reactor at 2.0 ton/day. These estimates of each reactor process indicate the economic superiority of the flow reactor process, which has a larger treatment capacity and a higher yield of fuel oil with the minimum formation of carbon.