Polyurethane Energy Recovery and Feedstock Recycling Technology A Summary Overview of Latest European Technologies
The implementation of the European waste sector regulations: packaging, automotive and electrical and electronic goods with specific targets for recycling and energy recovery warrant a summary overview of current installed and developing technologies for plastics in general and more specific for Polyurethane (PU) The quotas are very demanding and extremely ambitious with respect to the mile stones at 2006 and 2015. In addition landfill phase out regulations put additional pressure on the owners of PU waste to find a home. There is a great lack of energy recovery capacities due to a phase out of landfill in most central European countries by the 2005 to 2007 time frame. Total capacity of WtE facilities in Europe is about 47 Million t in 2002. This is only 20 of total municipal solid and other similar waste. The solution to bridge the gap between waste supply and waste treatment capacity is linked to the low cost approach building mechanical sorting plants and mechanical biological treatment plants. These plants do recover a mixed organic fraction to which the PU belongs after a mass reduction. Opportunities exist to do recover energy through fuel substitution in co firing substituting traditional fuels in power, cement and lime production plants. This is due to the large substitution potential for solid recovered fuels (SRF) Economics of gate fees depend very much on incremental investment, new co incineration legislation and fuel characteristics of PU. PU specific combustion and energy recovery characteristics have been documented and analyzed to match up technological and operational requirements with fuel characteristics to such a degree that their fuel character is known to the market. Besides WtE and the classical thermal co treatment routes selected few integrated facilities are available with limited capacity. PU applications in the various market sectors are numerous. There are many feedstock recycling technologies specific to PU streams like glycolysis, which require a dismantling and separation of PU. The raw material and converting industry favors large scale operations to avoid high dismantling, logistics and recycling costs. The alternative to separated polymer streams is to treat shredder residue containing PU with the rest of non metallic materials either directly or after refinement depending on the user. A number of feedstock recycling technologies like traditional gasification, pyrolysis and new thermal or feedstock process developments are available and could be commercialized. But they require significant capital investment and carry the risk of scale up problems. Outlets for the produced gas are known and can be a feedstock for chemicals and plastics production. The investment cannot be paid through today's level of disposal cost or gate fees in the market. Metallurgical processes are also suitable when using the produced gas for reduction purpose. The amount of coal and heavy fuel oil which can to be substituted is favorably high. INTRODUCTION The areas of interest for a deeper understanding of PU energy recovery and feedstock recycling in Europe and other parts of the world are characterized through 1. Available treatment capacities 2. Technologies: PU specific or general to organic materials 3. Waste markets The paper [1] summaries and analysis with special emphasis to the amount of PU waste arising, waste markets and gives an update on European regulations. But the paper did at that time not present the overview on the technology,it concentrated more on the waste characteristics description. PU is one of the larger polymer product groups within the plastics family. The producers of PU are organized within ISOPA (www.isopa.org) the Isocyanate Producers Association in Europe and API in North America www.polyurethane.org Total production volume of PU in Europe is 2.5 Million tons per year. The European plastics producers association formerly APME and today PlasticsEurope does support the demonstration of existing technology for plastics and the development of new technology as part of their environmental program. A general overview of the plastics family with the phases production, life time use, inventory and end of life operations can be seen in the Figure Nr. 1. The plastics producer industry does advocate a position that many of the high efficiency energy recovery processes match up with the feedstock recycling process in terms of eco efficiency. This has been shown in a number of studies done by PlasticsEurope for the market sectors packaging, automotive and electrical and electronic goods (2,3) A political hierarchy between high efficiency energy recovery and feedstock recycling processes can hence not be justified on environmental as well as economic arguments. Figure Nr. 1 Life Cycle of Plastics EUROPEAN LEGISLATIONS The most important change in European waste sector regulations recently is the switch from specific waste sector regulations to the Thematic Strategies. The two important upcoming Thematic Strategies which influence PU industry at large are on Waste prevention and recycling and Natural resources use It is expected that the EU commission will publish their first draft after the summer of 2005. Other important legislative developments are the modification of the waste frame work directive as well as the discussion about the recognition of waste to energy (WtE) as called in the USA or energy from waste abbreviated in Europe (EfW) potential reclassification of EfW as a disposal operation D and not recovery R potential reclassification of plastics recycling in steel plants as energy recovery pre treated waste plastics stays as a waste and cannot be classified as fuel substitute The official classification and the understanding for Europe are shown in Figure Nr. 2 below. European Definitions Recovery Disposal (EfW in D, Life Cycle of Plastics Energy Recovery Material Plastics Production Use Plastics Processing End of life available for collection 21 Mio t 1.5 Mio t PU Disposal 13 Mio t incl. 1.15 Mio t PU EfW 5 Mio t incl. 0.205 Mio t PU Recycling Feedstock 0.3 Mio t incl. PU very small Mechanical 2.5 Mio t incl. 0.14 Mio t PU 38 Mio t incl. 2.5 Mio t PU Inventory 500 Mio t into Inventory 17 Mio t incl. 1.0 Mio t PU Co incineration power, Mechanica l Feedstock Chemical Incineration with Energy from Waste/ Waste to Energy Figure Nr. 2 European Definitions INTEGRATED WASTE MANAGEMENT The current EU statistics for waste management from http:/epp.eurostat.cec.eu.int does characterize the total of EU 15 through the following routes: 20 to incineration with energy recovery, 47 landfill and the rest recovery. The main technology routes are explained in the schematic diagram below. The classical WtE route technology is today advanced by specific combustion techniques such as the (I) post grate ash treatment to achieve a grate ash which is considered by all EPAs to be of no concern to the environment and beneficial use when land filled without protection against ground water contamination, the (II) oxygen enrichment to achieve higher throughput in existing plants and the (III) recovery of salt products from a WtE facility. Mechanical sorting (MS) of different depth, types and degrees can produce a residue with a very high quality solid recovered fuel (SRF) or a hydro carbon feedstock for metal reducing furnaces to achieve a reducing reaction to produce iron or other non ferrous metals such as zinc. The development of combined mechanical biological processes (MBA) can have different conditions: aerobic, anaerobic, medium to low temperature or just a drying step to remove moisture. The product is also a type of SRF with product characteristics to be used in the same applications as mentioned before derived from the MS operation. PU end of life article are in many cases part of the waste mixtures coming from the sector or sub sector application. Due to that mixture composition the physical form does not lead to critical processing issues as long as the amount of PU is lower than 20 In some applications such as bedding and furniture where PU articles become separated and have a larger market share the processing step to come from the waste stream to a SRF stream a PU specific densification is needed. Processing technologies for low density foams have been described in [1] Figure Nr. 3 Integrated Waste Mgt. Overview The advances standardization of SFR has made and the recognition it received within the last 4 years is [4] remarkable due to the official nature of the European standardization approach under the guidance of CEN. The amount SRF today produced in Europe is about 5 Million t/ 2004.