PCDD/F Emissions from Co-Combustion of RDF with Peat, Wood Waste, and Coal in FBC Boilers

Abstract

The use of refuse derived fuel (RDF) as additional fuel in multifuel fluidized bed boilers (FBC) is a promising way for rational waste management. Several combustion experiments using RDF as additional fuel have been carried out in the research program of combustion and gasification technologies in Finland under the title Liekki 2.The size of fluidized bed combustors used in these experiments ranged from 15 kW* up to 117 MW*. The chlorine content of fuel rose up to 0.35% as a measured dry base (db). The emissions of the toxic PCDD/F compounds were found to follow fuel-Cl content trendwise, as expected. However, quantitatively the relative emission levels varied with the factor of 103 at the same Cl-content in fuel. Using statistical analysis correlations between PCDD/F emissions and combustion conditions (Tg, CO etc.) as well as fuel and ash properties were found.Most ofthe earlier measurements in commercial plants have been conducted usually after an electrostatic precipitator (ESP), which has made it difficult to relate emission results to corresponding combustion conditions. According to the laboratory scale fluidized bed reactor (15 kWn,) using normal (primary and secondary) and staged (primary + secondary + tertiary) combustion air feeding, it was found that in the staged condition (higher vertical temperature profile) the total amount of PCDD/F compounds (gas and particles) decreased, but the amount ofPCDD/F in solid phase increased.

Fluidized bed waste incinerators: Design, operational and environmental issues

“…heating value and moisture content), in order to reach high combustion efficiency and steady combustion characteristics [60][61]. A large number of papers discuss the co-incineration of MSW, RDF or biomass in existing coal fired FBCs for energy production [55,60,57,[62][63][64][65][66][67][68][69][70][71][72][73][74][75][76]. One of the advantages of this form of co-incineration is that the waste can be energetically valorized without high investment costs.…”

“…The parameters influencing PCDD/F reformation in FBCS were investigated by different research groups [66][67][136][137]. Huotari and Vesterinen [67] demonstrated that in a lab scale FBC co-incinerating RDF with peat, wood bark and coal the following variables positively correlated with the PCDD/F concentration in the flue gas: CO and PAH concentration in the flue gas, the number of CO concentration peaks in the flue gas during the measuring period, the chlorine concentration in the fuel and the Cl/S of the fuel, the concentration of PCBz, PCPh and PCBs in the flue gas and the copper concentration in the fly ash. The combustion temperature was negatively correlated with the PCDD/F concentration in flue gas.…”

Co-Combustion of Tannery Sludge in a Bench-Scale Fluidized-Bed Combustor: Gaseous Emissions and Cr Distribution and Speciation

“…The co-combustion of hazardous wastes in fluidized-bed combustion (FBC) systems is a potential technology for effective disposal of hazardous wastes. Co-combustion in FBC systems has been widely applied to many kinds of wastes, such as biomass, municipal solid waste (MSW), refuse-derived fuel (RDF), and sewage sludge, and extensively characterized on the basis of combustion, emission, ash deposition, and trace element transformation. − However, few studies have investigated the co-combustion of hazardous wastes in FBC systems. , Thus, the need remains for more meaningful results.…”

Co-combustion of tannery sludge in a commercial circulating fluidized bed boiler

“…Previous studies Huotari and Vesterinen (1996), Philippek and Werther (1997), Laursen and Grace (2002), Tsai et al (2002), Wagland et al (2011) and Leckner et al (2004) have investigated co-combustion in FBC with a variety of materials like biomass, MSW, RDF and sewage sludge. Several co-incineration experiments of hazardous wastes in FBC have also been reported and hazardous wastes co-firing included automotive shredder residue and bioferment residue (Van Caneghem et al, 2010;Jiang et al, 2012).…”