Thermofuel process

The essential steps in the Thermofuel pyrolysis of plastics involve  

The catalyst is not consumed or poisoned, unlike zeolite type catalysts. The metal plates do however get fouled with a tar-like residue and terephthalic acid and therefore the reaction tower needs to be stripped down periodically and the plates polished back to their pristine form. 

The catalyst chamber is the heart of the Thermofuel process and is directly responsible for the high quality of the output fuel from this process. The technology in and around this unit is highly proprietary since competitive processes do not have this type of longlife catalytic converter. Many other pyrolysis processes add zeolite catalysts directly to the pyrolysis chamber, however, these are expensive and quickly become fouled and deactivated. 

A single-chamber demonstration plant in Fujioka City, used for running trials and process development, has been operational since 1996. Inspection of the inside of the 

A twin-chamber Thermofuel plant at the Total Company in Yamanashi Province has been in operation since 2002. The plant at this site processes post-industrial plastic packaging film based mainly on polyethylene, polypropylene and nylon. The plant operation is highly automated. 

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Dr John Scheirs is a polymer research specialist with an emphasis on plastic recycling and pyrolysis of waste plastics into fuels. He serves as a consultant for Ozmotech Australia and has worked on the development of their Thermofuel process which can convert unwashed mixed plastics into low-sulfur diesel transportation fuel. He has studied the pyrolysis of HDPE, PP, PET and engineering plastics. 

The core technology of the Thermofuel process is the catalytic reaction tower (or catalytic converter, Figure 15.7). The catalytic reaction tower contains a system of plates made from a special catalytic metal alloy. The metal plates are positioned so that the hot pyrolytic gases must travel a tortuous path, in order to maximize contact area and time. The catalyst chamber is heated to 220°C using the exhaust gases (not pyrolysis gases) from the furnace of the pyrolysis chamber. 

Figure 15.7 Close-up of catalytic reaction tower and condensers of the Thermofuel process. (Reproduced by permission of Ozmotech Pty Ltd)...

In the Thermofuel process the first reaction occurs in the pyrolysis chamber where the plastic is thermally pyrolyzed, causing random scission of carbon chain lengths. While secondary reactions occur in the catalytic converter (i.e. catalyst tower) where shorter carbon chains are reformed and further cracking of longer carbon chains occnrs such... 

In the Thermofuel process, carbon and coke deposits formed during the pyrolysis are continuously scraped from the pyrolysis chamber walls and reduced to a free-flowing black powder. Inorganic additives such as cadmium pigments from the plastics also end up in the char stream. The carbon matrix has a metal fixing effect and binds up the metal ions so that no leaching occurs after disposal. 

Ozmotech have developed a Thermofuel process whereby waste plastic is converted into diesel by thermal degradation in the absence of oxygen. In this process the plastic waste is first melted and then cracked in a stainless steel chamber at a temperature of 350-425°C under inert gas (nitrogen). The catalytic reaction tower is designed in such a way that hot pyrolytic gases take a spiral or zigzag path to maximize contact area and time with the metal catalyst. The metal catalyst cracks hydrocarbon chains longer than C25 and reforms chains shorter than Ce. This leads to the formation of saturated alkanes. 

ThermoFuel (2) A process for making fuel oil by the hydrothermal treatment of sewage sludge. Developed in 2005 by ThermoEnergy Corporation. 

Figure 15.6 Process flow for commercial pyrolysis plant (Thermofuel ) for converting waste plastics into diesel fuel. The plastic is heated to 375-425°C and the pyrolysis vapours are catalytically cracked and then selectively condensed. Note that the pyrolysis vessel is purged with nitrogen gas and that the hot pyrolytic vapours pass from the pyrolysis vessel to the catalytic reaction tower where they are cracked and reformed to give a high-purity diesel stream. (Reproduced by permission of Ozmotech Pty Ltd)...

A twin-chamber Thermofuel plant at an agricultural cooperative on the island of Okinawa has been in operation since 2003 (Figure 15.9). This plant processes agricultural... 

The Polymer-Engineering process is very similar to the Thermofuel system design, except that the main chamber contains a heavy thermal oil with a high boiling point. The waste plastic is continuously added as flake and it quickly melts in the thermal oil and pyrolyzes. The heavy oil is held at 390°C and the plastics quickly pyrolyze since it is an excellent heat transfer medium. 

ThermoFuel (1) A process for making diesel fuel from waste plastic. Preferred plastics are polyethylene and polystyrene. The plastic is first melted in an extruder and then pyrolyzed continuously in a cylindrical chamber at 370°C-420°C, giving a Cg to C g hydrocarbon mixture having a peak at C,g. An important feature is the incorporation of a catalytic reaction tower after the main pyrolysis reactor, which incorporates metal plates made from a proprietary catalytic metal alloy. Distillation yields an average of 930 L of diesel per ton of waste plastic. Developed by Ozmotech, Australia, and now offered by EnviroSmart Technologies of Roosendaal, the Netherlands. In 2006, there were plans for 31 installations in Europe to be made over the next 4 years. 

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