The project addresses development of environmentally sound FBC of low-calorific value wastes (incineration). Technology proposed is primarily important from environmental point of view, since it enables efficient and environmentally sound removal of wastes and ballasts generated in industrial processes, in that way solving the problem of their controlled/uncontrolled disposal. Another advantage of the technology considered is that it enables utilization of the energy potential of low-calorific value wastes, a goal found very difficult or even impossible to achieve with other technologies due to low calorific value of the considered waste types, their non uniform composition and presence of unburned components in the ash produced.

Initial project related investigations have been successfully completed within the scope of the project financed by the Ministry of Science and Technological Development (MSTD) (NPEE 232004, 01/05/2005-30/06/2008), when trial experiments analyzing combustion of sludge deposits from crude oil storage tank of Pančevo Oil Refinery have been conducted. Sludge deposits were combusted in a 100 kW fluidized bed (FB) pilot plant. In the next project phase (01/04/2009-31/12/2010) investigations have been continued within the scope of a MSTD project (??18219) when a 300 kW industrial-scale demonstration boiler burning sludge deposits from crude oil storage tanks and some other types of wastes was built in the complex of Boiler Manufacturing Plant TIPO, Belgrade.

Further investigations shall focus on improving thermal disintegration of wastes in FBC, including widening the spectrum of waste types that can be combusted in the FB combustor constructed. The said shall be primarily accomplished through installation of additional fuel dosing systems for fuel distribution on and in the FB, as well as installation of auxiliary fuel feeding line aimed to support combustion when burning waste with particularly low calorific value or waste of pronouncedly non-uniform composition. Upgrade and further development of demonstration FBC facility shall enable a data base of industrial-scale FBC of different types of waste to be assembled. In addition, special attention shall be paid to normative boiler calculation and development of computer software to be used in the boiler optimization. The said boiler optimization shall provide construction cost reduction and operating regime optimization aimed towards more efficient and environmentally sound waste elimination.

Current situation in Serbian industry indicate that the following materials need to be removed/utilized from the production processes: waste coal fractions from several underground coal mines, off-balance coal reserves, deposits of wet coal separation, waste coal fractions from Kolubara lignite drying plant in Vreoci, deposits in refinery crude oil storage tanks, deposits in heavy oil and fuel storage tanks at gas stations, waste from fruit and vegetable treatment (pulp produced by fruit pressing-squeezing, fruit stones and similar), contaminated glycerin from biodiesel production, waste from pulp and paper industry, oily waters from metal industry, used oils from rolling mills, residues from paint and varnish production etc.

Investigation of waste combustion shall include laboratory analyses, carried out prior to experiments conducted on the industrial facility. Laboratory analyses shall include proximate and ultimate fuel (waste) analyses, analysis of fuel behavior in storage and dosing systems, waste classification and adjustment of combustion process to satisfy the norms defined for the waste class in question. A detail analysis of national and international regulations and limitations related to controlled combustion of waste shall be performed and maps of different waste classes developed. Combustion of different wastes in the upgraded demonstration boiler shall be analyzed, steady state heat and mass balances calculated, temperature field distribution modeled and continuous gas emission analysis performed. Concentration and composition of solid particles in the combustion products shall be measured as well. Experimental investigation shall provide important data on the effects of combustion conditions on energy efficiency and environmental aspects of the combustion process, in that manner contributing to a better understanding of FBC processes. Possibilities for permanent, environmentally sound disposal of FBC fly ash shall be analyzed as well.

In order to be able to better understand processes occurring in the FB combustor and more comprehensively analyze effects of FBC conditions on the overall efficiency of the FBC facility, 2D numerical CFD model of the processes occurring in the FB combustor shall be further developed. During the preceding project phases development of 2D numerical fluid - porous medium model, based on the open CFD code jointly developed by Vinča Institute, LTE and LSTM Erlangen, was initiated. The model can be used for improved fuel dosing directly in the FB. In the next project phase, the model shall be further developed through introduction of single-phase and heterogeneous chemical reactions. Together with modified commercial code based on utilization of a two-fluid Euler model for FB process modeling, the CFD model developed shall enable CFD simulation of FBC of solid and liquid fuels, with special consideration of the intense combustion zone and the overall combustion efficiency of the boiler.