Successful Technologies for the Pyrolysis of Automotive Shredder Residue
Pyrolysis Solutions for Automative Fluff Disposal

In a 2006 paper presented at Waste 2006, Stratford Upon Avon, UK, titled “Pyrolysis of Automotive Shredder Residue”, it is reported that after trials on a number of pyrolysis systems for ASR, extending over 5 years, only one is now considered to be fully commercial and that is the Ebara plant in Japan. Ebara co-processes SR with sewerage sludge (70/30) at around 100,000 tonnes per year using gasification followed by vitrification of the residue.

There are only three other pyrolysis processes which are reported in the same paper to be semi or fully commercial, and which clearly specify that they can handle ASR as a feed. They are the PKA process, the Pyromelt Process (Lurgi Ensorgung), and the TWR process (Siemens; Schwel-Brenn; TWR/Mitsui ).

However, it should be recognised that the Schwarze Pumpe (SVZ;Global Energy) process of gasification, producing methanol as a fuel, was then at a demonstrator level only, and may well have advanced further by now.

These few processes which have survived the last few years of evolution have all dealt with some of the difficult characteristics of ASR in the same manner. Common to them all is mixing ASR feed with other wastes to regulate the energy content and material variation. They also all make significant use of the gases given off, including during the pyrolysis process. And they all obtain significant material recovery by post-processing the char. Several make use of the available energy to resolve the difficulty of dealing with remaining char by vitrifing it.

Although this may look like a neat final solution it should be remembered that vitrification temperatures are so high that it is, in effect, no more than an expensive way to manufacture glass.

None of these solutions come cheaply and this makes commercial viability difficult. In, some the tolerance range and small particle size required from the shredder, brings significant additional financial and energy costs.

Transport costs are also important; large transport costs for an essentially light and bulky material like SR may be incurred for transport over large distances to a suitable thermal processing plant. If the energy produced can be utilised immediately on site or to an adjacent user, this will prove considerably more viable than it being utilised elsewhere.

From the evolutionary history of these processes we have mentioned previously for SR it may seem unlikely that in the future there will be facilities which deal with SR only, because none have survived development so far. Recent developments point instead to the likely mixture of ASR with other wastes such as MSW and biomasses, in large facilities, or alongside power stations or cement / steel industries where the char and energy can directly replace fossil fuels.

However, there is still a niche market for much smaller units that can take advantage of opportunities peculiar to the automotive shredding industry.

Although there is now growing information and knowledge on the suitability of various processes for
treating SR of which pyrolysis and gasification is just one contender, So far there is no clear emerging indication as to which will win out.

Nevertheless, the related technologies are now sufficiently developed to be able to provide solutions for SR overall after some further development and optimisation. Unfortunately, as often happens, the commercialisation of pyrolysis of ASR is being hindered not by technological developments, but by the complexity and the changing nature of the drivers, making it difficult for stakeholders to decide which technologies to invest in and apply.

by Steve Last - 4 August 2008

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