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View of the Ecoloop large scale pilot plant. In this shaft kiln plant, 50,000 tons of waste plastic can be processed per year.
© Ecoloop
Materially and energetically processing problematic plastic waste
Projektinfo 05/2016

Schematic diagram of the shaft reactor: 1. Input material is mixed with lime before it passes into the hot reactor zone. 2. Material is fed by gravity and controlled by a turntable discharge system. 3. After the gasification in the upper zones, the remaining pyrolysis coke moves into the combustion zone and provides energy for the process. 4. In the cooling zone, the lime is cooled by air and water. 5. Syngas is suctioned off at the upper reactor head and pollutants remain bound to the fine-ground lime. 6. Pollutants are sieved out with the fine-ground lime and ash. 7. Coarse-ground lime is recycled in the process.
© Ecoloop
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Generating syngas from plastic wastes

A newly developed gasification process utilises waste plastics, carbon-containing sorting residues and rubber parts as well as shredded materials in the automotive industry. It can also process chlorine-containing plastic streams with PVC fractions in an environmentally friendly and efficient manner. It produces a purified syngas without flue gas emissions. In the process, lime serves as a transport medium and simultaneously binds halogens and other harmful substances. The gas generated in the shaft kiln can replace valuable primary energy sources such as natural gas in high-temperature processes or be used to generate electricity in efficient gas engines.

The process utilises diverse residues, including problematic plastic wastes or contaminated materials, without them having to undergo complex processing in advance. Potential feedstocks include sorting residues from recycling bins, heavy and light fractions of shredded materials, plastic composites or contaminated waste wood, miscellaneous biomass, roofing felts, lignite, salt coal, oil shale, tar lakes, contaminated soils, bituminous waste and, in particular, sewage sludge. Some waste, such as sewage sludge or plastic-containing e-waste fractions, contains valuable materials such as phosphorus, precious metals and rare earths. These can be enriched, separated and recycled by binding them with fineground lime.

Roland Möller, head of the research project and Director of the Ecoloop company, says: „We make gas from waste. Our technology does not have to limit the use Of chlorine-producing feedstocks for the combustion processes as is usually the case. With Ecoloop we want to supplement the waste and recycling technology in a sensible manner.“ The energy efficient utilisation of plastic waste in the new gasification plant provides a cheap alternative to incineration in waste incinerators with the subsequently necessary flue gas cleaning.

Syngas is produced in the shaft kiln

The furnace plant combines proven technical systems and methods that mainly stem from the lime industry to provide an innovative, flexible recycling process. Here the residues are mixed with coarse-ground lime and converted into syngas in a bulk material moving bed using the counter flow principle. The moving bed gasifier system does not require complex rotating parts or fixtures that are susceptible to damage. Under its own gravity, the material is transported from top to bottom in a bulk material moving bed comprising lime and substitute fuels, just as in the lime burning process.

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Lime plays key role in the process

Lime plays a crucial role in the conversion process in the shaft kiln: it is both a transport medium for the fuel and gas permeable scaffold within the bulk material moving bed, and its catalytic effect increases the generation of syngas. In addition, the lime absorbs chlorine, preventing not only the formation of dioxins and furans but also the resulting dangerous fumes during the subsequent use of the syngas. Between 400 and 800 °C and in the presence of water vapour as a catalyst, the lime facilitates the reforming of long-chain polymers and polycyclic derivatives. This therefore considerably reduces the formation of undesirable oil and tar-containing cleavage products. Acidic pollutants such as hydrochloric or sulphur compounds are bound to the lime and, after their heat is recovered, they are then separated with the ashes as fines from the course-ground lime. This can then be reused as part of the bulk material moving bed. During the gas cleaning, the raw syngas is freed from flue dust using hot gas filters and is then cooled to room temperature. The purified syngas can replace, for example, natural gas or be used as a raw material to produce basic chemicals such as alcohols or various hydrocarbons.

Projektinfo 05/2016:
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Addresses

Project management, system development
ecoloop GmbH

Development of the simulation model
TU Clausthal, IEVB

Project partner
Fels-Werke GmbH

Info tips

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Links

Video
The Technology of Ecoloop (in German)