Fluidized Bed Gasification Technology for Complete Recycling of Liquid Packaging Board - Power Production and Aluminium Recovery from LPB Reject

摘要

In Europe, about a million tons of liquid carton board is consumed annually. The majority of this still ends up in landfills due to lacking collecting systems and, furthermore, until now the recycling of used liquid cartons has been difficult because of problems in utilizing the remaining mixture of plastics and aluminium in energy production. A new concept based on bubbling fluidized bed (BFB) gasification technology capable of generating power from plastics and capable of recovering aluminium has been developed and the world's first plant is being built in Varkaus, Finland. Originally, the liquid packaging board (LPB) recycling plant was opened at the end of 1995 at Corenso United Oy Ltd's coreboard mill in Varkaus. The mill's fibre recycling plant separates used liquid packages and wrappings into their components: separated woodfibre is used for coreboard production and the remaining mixture of polyethene plastics and aluminium used to be incinerated in a power plant boiler. However, the incineration of this mixture in a normal boiler turned out to be very problematic due to the aluminium forming deposits on the heat transfer surfaces and on the grid of the boiler. These layers had to be removed at regular intervals, which caused interruptions in the power production and decreased the availability of the boiler. In order to overcome these problems, a new concept based on BFB gasification technology was developed by Corenso United Oy Ltd with Foster Wheeler Energia Oy and VTT (Technical Research Centre of Finland). The process development work started on a laboratory scale at VTT's test laboratory in 1997. After the process conditions were optimized, a 15MW demonstration scale gasification plant was built by Foster Wheeler Energia Oy at StoraEnso Varkaus mill late 1997/early 1998. This demonstration plant was operated in 1998 and in the spring of 1999, altogether 1400 hours. In these tests 19GWh of energy was produced simultaneously with 350tons of aluminium recovery. As a result of this development work, a full scale gasification plant is now under construction at StoraEnso Varkaus mill and it will have an output of 40 MW generating 165 GWh of syngas energy annually. The scheduled start-up of the gasification plant will take place in October, 2000. When operating the commercial scale gasification plant appr. 85000 ton/a of different types of packaging boards will be processed at the mill's fibre recycling plant. Of this amount appr. 18 000 ton/a of plastics is recovered and turned into the gaseous phase in a BFB gasifier and this product gas is then combusted in a separate boiler. This amount of energy will reduce the need of fossil and solid fuels by the equivalent of 16500 tons of oil annually. Simultaneously, 2100ton/a of metallic, non-oxidized aluminium is recovered and recycled to the aluminium industry. This paper presents the results of the test runs performed at the 15MW demonstration plant as well as the design of the 40MW world's first commercial scale recycled plastic gasification plant allowing the complete reutilization of composite packagings that were previously dumped in landfills.