The Reduction of Dioxin Emissions from the Processes of Heat and Power Generation

Abstract

The first reports that it is possible to emit dioxins from the heat and power generation sector are from the beginning of the 1980s. Detailed research proved that the emission of dioxins might occur during combustion of hard coal, brown coal, and furnace oil as well as coke-oven gas. The emission of dioxins occurs in wood incineration; wood that is clean and understood as biomass; or, in particular, wood waste (polluted). This paper thoroughly discusses the mechanism of dioxin formation in thermal processes, first and foremost in combustion processes. The parameters influencing the quantity of dioxins formed and the dependence of their quantity on the conditions of combustion are highlighted. Furthermore, the methods of reducing dioxin emissions from combustion processes (primary and secondary) are discussed. The most efficacious methods that may find application in the heat and power generation sector are proposed; this is relevant from the point of view of the implementation of the Stockholm Convention resolutions in Poland with regard to persistent organic pollutants.

Review of the current state and main sources of dioxins around the world

“…It is our opinion that inventories that express their releases in the form of emission factors (EF) are more concrete and give better knowledge from particular sources than expressions like grams per /year from other inventories (Pacyna et al, 2003;Chen, 2004;Quass et al, 2004;Pulles et al, 2006;Van der Gon et al, 2007;Wielgosinski, 2011;Cao et al, 2013;Relvas et al, 2013), where a value of the total raw emission is given, without considering the actual emission rate from each of the estimated sources, which can be influenced by feed materials, abatement technologies, economical reasons, geography, and so on (Chen, 2004;Pulles et al, 2006;Chiu et al, 2011;Trivedi and Majumbdar, 2013).…”

“…Besides that, only few studies fall upon the importance that non-industrial sources have nowadays and how they ought to be considered in the immediate future (Fiedler, 2007;Shih et al, 2008;Wielgosinski, 2011;Kaivojosa et al, 2012;Cao et al, 2013). The "European dioxin air emission inventory project" (Quass et al, 2004) is another exception that reached the same conclusion.…”

Combustion of Agricultural Biomass - Issues and Solutions

“…Chlorine reacts with metals such as K and Na, forming vapors and aerosols, which can during the cooling processes lead to deposits on the furnace walls. Chlorine, in form of HCl, can also react with organic constituents producing dioxins [25]. Dioxins and dioxin-like compounds are compounds that are highly toxic and environmental persistent organic pollutants.…”

“…Furthermore, as the dioxins are not chemical substances of high thermal stability, authors in [26] proved that temperatures greater than 900 °C and oxygen deficiency can bring to the complete decomposition of dioxins and other dioxin-like compounds. On the other hand, most of the emitted dioxins and dioxin-like compounds are formed behind the combustion zone in so called de novo synthesis, at the temperatures below 500°C, as a result of a series of catalytic reactions proceeding on the surface of dust that contains metals such as Cu, Fe, Ni, Al, Zn [25]. …”

Reburning Treatment of the Froths Obtained after the Flotation of Incinerator Fly Ash

“…2). Furthermore, PCDD/Fs are prone to decomposition at 850°C under combustion conditions (i.e., the presence of oxygen, mixing, and flow) (Wielgosinski et al, 2011). Thus, the PCDD/Fs adsorbed on PAC pores might be rapidly and efficiently decomposed after the complete combustion of the carbon constituents.Thus, the high content of the carbon constituents in the froths contributed to the high destruction efficiency of PCDD/Fs in the froths.…”