Municipal Waste Incinerator Flue Gas Research Articles

HCl removal characteristics of calcium hydroxide at the dry-type sorbent reaction accelerator using municipal waste incinerator flue gas at a real site

A dry-type reactor was used to reduce the HCl emitted from a municipal waste incinerator. A real-scale reactor was installed downstream of the existing semi-dry reactor (SDR) as part of D local incineration plant, whose HCl removal efficiency was investigated by applying calcium hydroxide (Ca(OH)2). A test dry-type sorbent reaction accelerator (SRx) was designed, and the stoichiometric ratio (SR) of the sorbent and the secondary reaction characteristics of unreacted Ca(OH)2 in a baghouse were analyzed. For the results, the SRx showed higher HCl removal efficiency and more economic benefits than the other existing flue gas treatment facilities of the incinerator plant. Furthermore, the highest reduction efficiency of HCl was obtained when the differential pressure in the baghouse was maintained at 150mmH2O. This is because as the unreacted sorbent attached to the filter surface layer became thicker and the secondary reaction of the HCl removal increased.

A novel additive for the reduction of acid gases and NOx in municipal waste incinerator flue gas

The reduction of SO2, HCl, and NO(x) concentrations using calcium magnesium acetate (CMA) as a novel sorbent in a simulated municipal waste incinerator flue gas was investigated. The reduction of individual SO2, HCl, and NO(x) concentrations was tested at 850 degrees C and it was found that CMA could reduce the SO2 concentration by 74%, HCl concentration by 64%, or NO(x) concentration by 94%. It was observed that individual SO2 or HCl capture increased with increasing initial oxygen concentration in the reacting gas or increasing sorbent input. NO(x) reduction decreased with increasing initial oxygen concentration in the reacting gas. The simultaneous reduction of SO2, HCl, and NO(x) concentrations by CMA was also investigated. It was found that CMA could simultaneously capture 60% SO2 and 61% HCl and reduce NO(x) concentrations by 26%, when the initial oxygen concentration in the reacting gas was 4%. During the simultaneous reduction of SO2, HCl, and NO(x), it was noted that as the initial oxygen concentration in the reacting gas increased, the efficiency of SO2 capture increased too, but the efficiency of HCl capture and the efficiency of NO(x) destruction decreased.

Concentration and congener patterns of polychlorinated biphenyls in industrial and municipal waste incinerator flue gas, Korea

In the present study, individual PCB congeners were determined in the flue gases of 10 industrial and 5 municipal solid waste incinerators using HRGC/HRMS. The total PCBs concentration of all congeners (168 tetra to deca-chlorinated congeners) ranged from 26 to 343 ng/Nm 3, and from 36 to 1095 ng/Nm 3 in industrial waste incinerators (IWI) and municipal solid waste incinerators (MSWI), respectively. The total TEQ concentrations of PCBs, calculated using WHO-TEF values, varied from 0.001 to 0.55 ng-TEQ/Nm 3 and from 0.001 to 8.29 ng-TEQ/Nm 3 in the industrial waste incinerators and municipal solid waste incinerators, respectively. In all samples, the contribution of PCB 126 to total TEQ of PCBs was higher than 87%. The homologue pattern of PCBs in the incinerator flue gas samples was generally dominated by tetra- and penta-CBs. The distribution of other homologues was less than 15% in most of the incinerators. The fraction of co-PCBs against to total PCBs ranged from 1% to 19% and from 2% to 31% in IWI and MSWI flue gas samples. Results of the present study reveal that the presence of non-ortho PCB congeners in the flue gas originated form the combustion process.

Homologue and Isomer Patterns of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans from Phenol Precursors: Comparison with Municipal Waste Incinerator Data

The role of phenol precursors in polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) formation in municipal waste incinerators is assessed on the basis of homologue and isomer patterns. Homologue and isomer patterns of PCDD and PCDF congeners formed from phenols both in the gas phase and via particle-mediated reactions were studied in an isothermal flow reactor. A mixture of unsubsitituted phenol and 19 chlorinated phenols in relative concentrations found in a municipal waste incinerator (MWI) stack gas was used for this study. PCDD and PCDF homologue and isomer patterns obtained from the phenol experiments were compared with those observed in MWI data. From the phenol experiments, gas-phase formation at 600-700 degrees C favors PCDF formation whereas particle-mediated formation at 400 degrees C favors PCDD formation. Unsubstituted phenol, which was present in high concentration, played a significant role in the formation of PCDD/F congeners under both sets of experimental conditions. PCDD/F distributions in MWI flue gas and fly ash samples were differentfrom those observed in the phenol experiments, suggesting that direct phenol condensation was not the primary route of PCDD/F formation at the incinerators. Gas-phase phenol condensation is a source of dibenzofuran, with subsequent particle-mediated chlorination resulting in PCDF formation. In the case of PCDD formation, phenol condensation may be responsible for the formation of certain highly chlorinated congeners. In this paper we demonstrate the use of homologue and isomer patterns for PCDD/F formation mechanism attribution in municipal waste incinerators.

Practical Limitation of Mercury Speciation in Simulated Municipal Waste Incinerator Flue Gas

Wet scrubbers on municipal waste incinerators can be effective at capturing mercury; however, their effectiveness decreases in systems where rapid thermal quenching of the hot furnace gases are employed. Since wet scrubbers are more effective at capturing soluble mercury species, such as mercuric chloride, than they are at removing elemental mercury, it is proposed that quench rate, or time at temperature, is a factor in the gas phase oxidation of mercury to mercuric chloride. The fate of mercury was studied at different temperatures in a simulated municipal solid waste incinerator exhaust gas. The composition was approximately 10% O2 and CO2, 8% H20 and balance N2, HCl was introduced at two concentrations: 300 and 3000ppmV, and elemental Hg was introduced at a target concentration of 3000 μ/m3. Mercury speciation was determined using EPA method 29. Results indicate that mercury speciation approaches equilibrium at 800°C when sufficient residence time is provided. At temperature below 800°C, conversion of mercury to the oxide is kinetically limited, and the data are fit very well by an Arrhenius correlation with an activation energy of 45.4 k3/mol. The impact of HCl concentration on mercury conversion to the chloride is at least as strong as the effect of temperature. At lower HCI concentrations, coversion is limited by thermodynamics at higher temperatures and by kinetics at lower temperatures.

Polychlorinated Benzene, Phenol, Dibenzo-p-dioxin, and Dibenzofuran in Heterogeneous Combustion Reactions of Acetylene

Acetylene was reacted with HCl/air under heterogeneous combustion conditions between 300 and 600 °C. Model catalyst mixtures of SiO2/metal oxides (Al2O3, Fe2O3, TiO2, and CuO) were compared with municipal waste incinerator (MWI) fly ash. Chlorinated benzenes (ClxBz), chlorinated phenols (ClxPh), and PCDD/F were detected in both gas-phase products as well as catalyst-adsorbed products. ClxBz production increased exponentially to 600 °C (HCB: 4 × 104 ng/g of C2H2), while ClxPh production (2.5 × 104 ng/g of C2H2) was maximized at 500 °C (ca. 104−105 ng/g of C2H2). PCDF displayed a dramatic peak at 500 °C (TCDF: 2 × 106 pg/g of C2H2), in contrast to the generally accepted de novo and aromatic precursor formation temperature of 300 °C. Comparison of gas-phase ClxBz congener distribution patterns revealed that the CuO-catalyzed reaction closely matched the ClxBz pattern produced in the reactions with MWI fly ash, providing further evidence of the importance of Cu in the fly ash matrix. Comparison of fly ash-catalyzed gas-phase ClxBz with MWI flue gas and 300 °C de novo synthesized ClxBz demonstrated the relevance of mid-temperature (600 °C) heterogeneous combustion reactions of C2 aliphatics in real combustion systems.

Distribution of halogenated phenols including mixed brominated and chlorinated phenols in municipal waste incineration flue gas

Incineration of municipal waste yields a variety of halogenated phenols including chlorinated, brominated and mixed brominated and chlorinated phenols in raw and stack gas. A total of 14 chlorinated, 3 brominated and 31 mixed brominated and chlorinated phenols could be characterized by high resolution gas chromatography high resolution mass spectrometry (HRGC-HRMS). A significant molar fraction of halogenated phenols in raw and stack gas was found to be monobrominated (12% and 8%) and dibrominated (2% and 1%). The monitored fraction of polyhalogenated phenols can be characterized with an elemental composition of C 6H 2.6Br 0.2Cl 3.2O in raw and C 6H 2.5Br 0.1Cl 3.4O in stack gas.

Pilot-plant for NO x, SO 2 and HC⪋ removal from flue-gas of municipal waste incinerator by electron beam irradiation

According to the basic research performed using a small size reactor at TRCRE of JAERI, the electron beam irradiation process was proved to be very effective for NO x, SO 2 and HC⪋ removals from flue-gas of municipal waste incinerators. Based on this result, a pilot-plant was constructed for the demonstration of NO x, SO 2 and HC⪋ removal performance using electron accelerator of maximum energy 0.95 MeV and maximum power 15kW. The pilot-plant was constructed at Matsudo City waste Disposal Center. The flue-gas of 1,000 Nm 3/hr is guided from the waste incinerator flue-gas line of 30,000Nm 3/hr to the pilot-plant to be processed by spraying Ca(OH) 2 slurry or powder and irradiation with high-energy electron beam of the accelerator. NO x, SO 2 and HC⪋ are removed simultaneously from the flue-gas by the enhanced reaction with Ca (OH) 2 under irradiation. A brief explanation of the pilot-plant and preliminary results of the experiments are introduced in this paper.