Özgül AYYILDIZ

      Thermal Processing of Solid Wastes Combustion Systems Pyrolysis Gasification Case Studies Conclusion

“it can be defined as the conversion of wastes into gaseous, liquid and solid production, with or without energy valorization.”

Thermal processes with respect to air requirements:  combustion  gasification  pyrolysis

   Combustion is occurred by stoichiometric amount of oxygen or excess air.

Gasification is the partial combustion of materials, thus materials convert to combustible gases (such as carbon monoxide, hydrogen, and gaseous hydrocarbons).

Pyrolysis can be defined as destructive distillation; materials are combusted with absence of oxygen.

Combustion systems (Incinerators) are involves the application of combustion processes under controlled conditions to convert waste materials to inert mineral ash and gases.

Types of incinerators;   Fixed-Hearth Incinerators Rotary Kiln Incinerators   Refuse Derived Fuel Incinerators Fluidized Bed Incinerator

  Pyrolysis recycling is a non combustion heat treatment that chemically decomposes waste material by applying heat (directly or indirectly) to the waste material in an oxygen free environment. It is an endothermic reaction and requires an input of energy, which is typically applied indirectly through the walls of the reactor in which the waste material is placed for treatment.

the thermo-chemical conversion of a solid or liquid carbon-based material (feedstock) into a combustible gaseous product (combustible gas).

  Direct gasification occurs when an oxidant gasification agent is used to partially oxidize the feedstock. Indirect gasification occurs without an oxidizing agent and needs an external energy source.

  Gasification of municipal solid waste in the Plasma Gasification Melting (PGM) process from Israel.

Co-gasification of solid waste and lignite from Western Macedonia.

Plasma Gasification Melting Process

The combination of plasma melting and high temperature agent gasification.

Western Macedonia Plant -Co-gasification Direct co-gasification (Integrated gasification combined cycle) unit utilizing lignite and solid wastes in the form of RDF. In direct gasification, coal and solid wastes or biomass are mixed and then fed to the gasification unit.

  The designed capacity of the plant is 20 tons of MSW per day.

MSW is fed through airtight feeding chambers.

    The annual production of lignite is around 60 million tons, out of which 48 million tons derive from the coalfields of WMP. The annual amount of municipal solid waste in WMP is 117,000 ton.

RDF was selected instead of MSW because of its better quality characteristics.

RDF and lignite mixture in the form of pellets with 75:25 mass proportions.

Syngas compositions

  Power generation is accomplished by 67% in the gas turbine and by 33% in the steam turbine. The overall efficiency of the unit is 47%, while internal power consumption is up to 7.5%.

    Feeding high-temperature steam into the PGM reactor greatly increased syngas yield, with even higher gas LHV.

The technology of co-gasification can result in very clean and efficient power plants using a range of fuels, but there are considerable economic, environmental and technical challenges.

Concerning the environmental benefits, the operation of an co gasification unit in the region of Western Macedonia will contribute to the reduction of CO the same quality.

2 , SO 2 and NOx emissions, compared to a conventional combustion unit utilizing lignite of The main disadvantage of this plant is the need for a cleanup system for the control of corrosive gas phase compounds such as tar, acid gas and alkali metals.

      Belgiorno, V., Feo, G. D., Rocca, C. D., Napoli, R.M.A. (2003), Energy from gasification of solid wastes, Waste Management 23, pp.1–15 Hernandez-Atonal, F. D., Ryu, C., Sharifi, V. N., Swithenbank, J. (2007), Combustion of refuse-derived fuel in a fluidised bed, Chemical Engineering Science 62, pp.627 – 635 N. Koukouzas N., Katsiadakis, A., Karlopoulos, E., Kakaras, E. (2008), Co gasification of solid waste and lignite – A case study for Western Macedonia, Waste Management 28, pp.1263–1275 Qinglin Zhang, Q., Dor, L., Fenigshtein, D., Yang, W., Blasiak, W. (2012), Gasification of municipal solid waste in the Plasma Gasification Melting process, Applied Energy 90, pp.106–112 Tae-Heon Kwak, T. H., Lee, S., Maken, S., Shin, H. C., Jin-Won Park, J. W., Yoo, Y. D. (2005), A Study of Gasification of Municipal Solid Waste Using a Double Inverse Diffusion Flame Burner, Energy & Fuels 19, pp.2268-2272 Tchobanoglous, G.; Theisen, H. & Vigil, S. A. (1993). Integrated Solid Waste Management, McGraw-Hill International Editions, ISBN 0-07-063237-5, Singapore

Özgül AYYILDIZ