Plastic wastes gasification

Closely related to the previous process is the plastic waste gasification facility being set up at Rotterdam with a capacity of 150 tonnes day-1 of plastic wastes.13 The feed of this plant will be a mixture of polyethylene, polypropylene and polystyrene with minor amounts of other polymers (2.4 wt% of PVC) and a significant proportion of cellulose. The plan is that an injection of ammonia into the gasifier will neutralize the chlorides entering with the plastic wastes, which will lead to the formation of ammonium chloride salt as a by-product. A production of 350 000 m3 day -1 of synthesis gas is estimated, which will be used in chemical synthesis. 

Texaco gasification is based on a combination of two process steps, a liquefaction step and an entrained bed gasifier. In the liquefaction step the plastic waste is cracked under relatively mild thermal conditions. This depolymerisation results in a synthetic heavy oil and a gas fraction, which in part is condensable. The noncondensable fraction is used as a fuel in the process. The process is very comparable to the cracking of vacuum residues that originate from oil recycling processes. 

Coal used in power stations has the potential to be partly replaced by fuels derived from pre-treated plastics and paper waste, reducing both dependency on fossil fuels and reliance on landfill. APME reports on a project in the Netherlands which it co-sponsored to develop a substitute fuel from plastics. The environmental assessment of the project compared the environmental impacts of coal substitution with other plastics recovery methods, including gasification in feedstock recycling and energy recovery from plastics waste in cement kilns. The study also compared coal substitution with the generation of power from burning biomass. 

The present state of technology is reviewed (mainly from German literature of 1993 -4) in the Add of three principal thermal methods used for plastics wastes, namely pyrolysis (high-temperature carbonisation, coking), hydrocracking and gasification. 36 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. 

Feedstock recycling is examined as a method of plastics recovery. The range of techno logics currently employed are described, and include pyrolysis, hydrogenation, gasification, and chemolysis. Methods for the recycling of mixed plastics wastes are discussed, which include work by BP Chemicals, VEBA Oil, Shell Chemicals and Leunawerke. 

This reports on the developments by a German company in the use of gasification in the chemical recycling of plastics waste. Brief details are given. 

Current methods of feedstock recovery are reviewed. Brief details are given of pyrolysis, hydrogenation, gasification, and chemolysis. Activities of some European companies are briefly discussed in the areas of recycling mixed plastics waste and closed-loop recycling. 

MeLean, Va., 3rd-4th June 1993, p.189-200. 8(13) GASIFICATION PROCESS FOR MIXED PLASTICS WASTE Simons en K Texaeo Ine. 

Sorting of plastics is often manual and can cause allergic and health problems. Remarkably, plastic waste is not without a smell, and air extracted from storage and handling is thermally deodorized, e.g. at the Ube Industries gasification plant. Part of the pyrolysis products can be regarded as toxic. 

Texaco has recently adapted its gasification process to plastics waste [76]. The project is to develop a capacity of 40-50 kt/yr in Pemis (Netherlands). This process consists in two parts a liquefaction step and an entrained bed gasifier. The plastic waste is depolymerized... 

It can be seen that a significant proportion of the energy content of the waste is recovered by the gasification of the char and that the ultimate residue is decreased in comparison with the quantity of bottom ash produced compared with direct incineration. Solid plastic waste represents a significant stream for conversion back to energy [89]. 

High-temperature pyrolysis (650-800°C) of plastic waste, fed into the rotary kiln via a screw feeder. Solid cokes and pyrolytic vapours are sent to further treatments in gasification or hydrogenation plant... 

Prior to the erection of the pilot plant at Velsen, a small test reactor consuming up to 60 kg/h of solid waste was installed at Neunkirchen next to an incinerator, which was to prove feasibility of solid waste gasification. During 2 1/2 years of test runs amounting to about 10 000 hours, all kinds of materials were charged to this reactor. For instance rubber, plastics, wood, used lubricating oil mixed with household waste. A reasonable gas composition could be maintained for any length of time ... 

In 1996, the so-called economic circulation and waste law was introduced in Germany. It was orientated towards different possibilities of plastic waste exploitation recycling by thermoplastic processing, conversion into low molecular weight substances, or alternatively gasification in order to use the synthetic gases or to use... 

Lack of a regional plastic waste volume to support the continuous operation of large-scale plants. For gasification, a minimum capacity about 400 000-500 000 tonnes per year is necessary. 

Campbell P, Vans RH, McMullen JT and Williams BC (2001) The potential for adding plastic waste fuel at a coal gasification power plant. Waste Management Res 19 526-532. 

M. Gebauer and D. Stannard, Gasification of Plastics Wastes in J. Brandrup, M. Bittner, W. Michaeli, and G. Menges, eds.. Recycling and Recovery of Plastics, Hanser/Gardner, Cincinnati, OH, 455-480 (1996). 

Aznar MR Caballero MA, Sancho JA, Francs E. Plastic waste elimination by co-gasification with coal and biomass in fluidized bed with air in pilot plant. Fuel Process Technol 2006 87 (5) 409 20. 

Kim JW, Mun TY, Kim JO, Kim JS. Air gasification of mixed plastic wastes using a two-stage gasifier for the production of producer gas with low tar and a high caloric value. Fuel 2011 90 2266-2272. 

Mastellone ML, Arena U. Olivine as a tar removal catalyst during fluidized bed gasification of plastic waste. AIChE J 2008 54 1656-1667. 

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