Chlorine Input and Chlorophenol Emission in the Lab-Scale Combustion of Municipal Solid Waste

Abstract

Incineration of municipal solid waste (MSW) yields a variety of chlorinated aromatics such as chlorophenols. In this study, regular and modified samples of MSW have been processed in a micromodel reactor mimicking the primary combustion chamber of a practical MSW incinerator. To understand the relationships between the origin of chlorine in the feed and the formation of products of incomplete combustion (PICs) and HCl, emitted chlorophenols (CPs) and HCl have been measured. With humidified air as the carrier gas, the chlorine load of regular MSW (ca. 50% due to inorganic chloride, ca. 45% due to PVC) entailed a net CP production of ca. 110 µg/ kg wet MSW. With an (up to 8-fold) increase of the PVC load in the MSW, only a slight increase of this CP emission level has been observed. Also, in replacing the compostables and the other important chlorine carrying fractionssincluding PVCsby cellulose and NaCl, the level of CP emission does not change. Enrichment of the combustion air with HCl leads to twice as high CP levels. Removal of 70% of the PVC and 80% of the compostables results in a reduction of the CP production by a factor of 2.

Chlorine characterization and thermal behavior in MSW and RDF

“…For the Amsterdam MSW incineration plant TCC of 4.1 g/kg raw waste is reported (3.1 g/kg raw waste in stack emission, 0.4 g/kg in slag, 0.5 g/kg in fly ash, and 0.1 g/kg in fly dust) [22]. Based on the data presented here, plastics (Pl1, Pl2, Pl3 in total) contribute to one third of the TCC, and organic waste (Org1, Org2) contains approximately 50% of TCC.…”

“…Based on the data presented here, plastics (Pl1, Pl2, Pl3 in total) contribute to one third of the TCC, and organic waste (Org1, Org2) contains approximately 50% of TCC. Kanters et al [22] reported that ca. 50% of the chlorine load of regular MSW is due to inorganic chloride and ca.…”

“…On the other hand, less HCl was formed as the equilibrium constant become smaller at higher temperature [21]. Kanters et al [22] investigated how NaCl transforms into HCl, and found that after 1.5 h at 780 • C 55% of the NaCl intake was emitted as HCl, while 40% remained in the sand. Wang et al [23] found that the conversion of NaCl into HCl is much lower than that of PVC and that temperature plays a key role in the chlorine volatilization both for PVC and NaCl.…”

The formation of dioxins in combustion systems

“…In most attempts to study the reaction system, the concentration of Cl in the solid fuel or the concentration of HCl in the gas phase has been the variable controlled and monitored. The concentration of HCl in the gas phase was found to be proportional to the quantity of chlorine added (as PVC) to the feed of both a lab furnace [129] and a 220 kg h −1 incinerator [63]. In the pilot incinerator at Umeå, no distinction was found [130] between the types of chlorine, i.e., organic (PVC) or inorganic (CaCl 2 ·6H 2 O) added to synthetic MSW.…”

“…The form of chlorine released during the pyrolysis of PVC has been investigated by Kanters et al [129]. Various amounts of PVC up to 5 wt% were added to a simulated MSW containing 0.46% of Cl, and incinerated batchwise under air at 850 • C. The quantity of chlorophenols released into the gas remained virtually constant at 3.3 µmol/kg of dry waste at all levels of PVC addition.…”