The relationship between HCL and mercury speciation in flue gas from municipal solid waste incinerators

Noji, Takashi; Fukunaga, Isao; Itoh, Hisao; Nomura, Taishin

doi:10.1016/s0045-6535(98)00583-9

Cited by 21 publications

(14 citation statements)

References 7 publications

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“…The high level of HCl generated from various municipal solid-waste incinerators is a major cause of environmental pollution and corrosion of incineration equipment. The process forms low-melting metal chlorides in the presence of heavy metals, which undesirably increases the heavy-metal content of the fly ash. , Capturing HCl from industrial flue gas is one of the major issues in China. This can be achieved at low operating temperatures, but damage caused by HCl at high incineration temperatures is challenging to mitigate.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of HCl on Calcined Ca and Zn Hydrotalcite-like Compounds (HTLs) at Medium-High Temperature in Flue Gas

Cao

Chen

Jin

et al. 2018

Ind. Eng. Chem. Res.

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The high level of HCl generated from municipal solid-waste incinerators at 350–650 °C is considered a primary chlorine source for emitted toxic polychlorinated dibenzodioxins and polychlorinated dibenzofurans. Herein, calcium (Ca) and zinc (Zn) hydrotalcite-like compounds (HTLs) were prepared to remove HCl at different reaction temperatures and initial HCl concentrations. The mechanism of the adsorption of HCl by the HTLs and calcined HTLs (HTOs) was investigated using thermogravimetric analysis, X-ray powder diffraction, scanning electron microscopy, and surface-area measurements. The Ca- and Zn-HTLs had similar structures and physicochemical properties. Both sorbents had good adsorption capacities for HCl that exceeded 90% over 456 min at 550 °C in an HCl concentration of 750 mg/g. The adsorption capacity of Zn-HTOs was better than that of Ca-HTOs at 350 °C. The removal efficiency of Ca-HTLs was higher than that of Zn-HTLs at temperatures above 550 °C. The Freundlich isotherm provided a good fit to the experimental data for the HTLs.

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Section: Introductionmentioning

confidence: 99%

Adsorption of HCl on Calcined Ca and Zn Hydrotalcite-like Compounds (HTLs) at Medium-High Temperature in Flue Gas

Cao

Chen

Jin

et al. 2018

Ind. Eng. Chem. Res.

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“…The Hall et al (1990) studies were performed with simple simulated flue gases, but may be used to explain the high mercury removal in incinerators observed by Brna and Kilgroe (1990). On the other hand, another study conducted in a number of MWCs in Japan (Nishitani et al, 1999) showed that a considerable amount of Hg 0 (30-90%) can exist in the waste combustion flue gas in the presence of HCl concentrations lower than 1,000 ppm. The relatively poor mercury removal observed in the Taiwanese MWCs (Chang et al, 2000) may be due to relatively high Hg 0 concentration in the flue gas.…”

Section: Introductionmentioning

confidence: 99%

Effects of Fly Ash Transition Metal Content and Flue Gas HCl/SO₂ Ratio on Mercury Speciation in Waste Combustion

Ghorishi

Lee

Jozewicz

et al. 2005

Environmental Engineering Science

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Understanding the transformation of mercury species (elemental and oxidized forms) in stationary combustion sources is of interest to both those responsible for developing control technologies and those responsible for setting regulations. Elemental mercury (Hg 0 ) poses a challenging flue gas control issue, and oxidized forms of mercury (Hg 2ϩ ) are of concern due to local deposition potential. In a previous study, mercury speciation, or more specifically oxidation of Hg 0 , was studied in simulated flue gases and in the presence of three-component model fly ashes. Gas-phase studies indicated that oxidation of Hg 0 in the presence of hydrogen chloride (HCl) is rather slow, and proceeds at measurable rates only at temperatures Ͼ700 °C and HCl concentrations in the range of 100-200 ppm. The effect of fly ash composition was investigated using a fixed-bed reactor containing different synthetic model fly ash components such as alumina (Al 2 O 3 ), silica (SiO 2 ), ferric oxide (Fe 2 O 3 ), copper oxide (CuO), and calcium oxide (CaO). Transition metal oxides, CuO and Fe 2 O 3 , exhibited significant catalytic activity in the surface-mediated oxidation of Hg 0 in the presence of HCl. The observed Hg 0 oxidation activities of the two oxides are possibly caused by the Deacon process in which chlorine gas (Cl 2 ) is produced via catalytic oxidation of HCl over these two oxides. In the present follow-up study, the effect of sulfur dioxide (SO 2 ) to HCl ratio on Hg 0 oxidation was investigated. The addition of SO 2 to the moist flue gas at high SO 2 :HCl ratios (10:1 to 4:1) caused a decrease in oxidation of Hg 0 . This is attributed to a scavenging effect of SO 2 and H 2 O on Cl 2 . Addition of CaO to the synthetic fly ashes also caused a drop in Hg 0 oxidation. It is possible that due to the partial removal of HCl by reaction with CaO less HCl is available for the catalytic Deacon reaction. The Hg 0 oxidation activity of a cement kiln dust (CKD) sample collected from a full-scale hazardous waste incinerator was also studied. Qualitatively, it exhibited Hg 0 oxidation catalytic behavior sim-221

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“…Hydrochloric acid (HCl) is a primary gas pollutant emitted from municipal solid waste (MSW) incineration. In an industrial environment, it can react with metals in processing equipment during combustion, forming alkali chlorides and accelerating equipment corrosion. − The initial concentration of HCl in incineration wastes ranges from 815 to 1630 mg·m –3 in China and from 163 to 815 mg·m –3 in developed countries . Inorganic compounds with high selectivity and good adsorption capacity for HCl at relatively high temperatures, i.e., 250–450 °C, are being actively investigated .…”

Section: Introductionmentioning

confidence: 99%

Structural Effects of HCl Adsorption on Mg–Fe Hydrotalcite-like Oxides at 350–650 °C in Flue Gas

Cao

Chen

Jin

et al. 2018

Ind. Eng. Chem. Res.

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Calcined Mg–Fe hydrotalcite-like compounds (HTLs), hydrotalcite-like oxides (HTOs), have shown potential performance for removing hydrochloric acid (HCl) from flue gas at medium-high temperatures. The adsorption of HCl on Mg–Fe HTOs was studied from 350 to 650 °C. The average removal efficiency of HCl on Mg–Fe HTOs is affected primarily by temperature-dependent structural changes. Structural changes in pristine and calcined HTL samples were characterized using various analytical techniques. The pyrolysis kinetics of Mg–Fe HTLs were also studied using Kissinger–Akahira–Sunose and Flynn–Wall–Ozawa methods at temperatures ranging from room temperature to 700 °C. The layered structure of HTLs was maintained at 255 °C, where the activation energy of decomposition was approximately 35–38 kJ·mol–1. At 350 °C, the removal efficiency of HCl adsorption on the HTOs was as high as 92.4%. Upon heating to 495 °C, the activation energy was 65–70 kJ·mol–1, and the HTL structure was destroyed by the decomposition of carbonate and hydroxyl functional groups, resulting in a slight decrease in HCl adsorption capacity but still exceeding 90%.

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The relationship between HCL and mercury speciation in flue gas from municipal solid waste incinerators

Cited by 21 publications

References 7 publications

Adsorption of HCl on Calcined Ca and Zn Hydrotalcite-like Compounds (HTLs) at Medium-High Temperature in Flue Gas

Adsorption of HCl on Calcined Ca and Zn Hydrotalcite-like Compounds (HTLs) at Medium-High Temperature in Flue Gas

Effects of Fly Ash Transition Metal Content and Flue Gas HCl/SO₂ Ratio on Mercury Speciation in Waste Combustion

Structural Effects of HCl Adsorption on Mg–Fe Hydrotalcite-like Oxides at 350–650 °C in Flue Gas

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The relationship between HCL and mercury speciation in flue gas from municipal solid waste incinerators

Cited by 21 publications

References 7 publications

Adsorption of HCl on Calcined Ca and Zn Hydrotalcite-like Compounds (HTLs) at Medium-High Temperature in Flue Gas

Adsorption of HCl on Calcined Ca and Zn Hydrotalcite-like Compounds (HTLs) at Medium-High Temperature in Flue Gas

Effects of Fly Ash Transition Metal Content and Flue Gas HCl/SO2 Ratio on Mercury Speciation in Waste Combustion

Structural Effects of HCl Adsorption on Mg–Fe Hydrotalcite-like Oxides at 350–650 °C in Flue Gas

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Effects of Fly Ash Transition Metal Content and Flue Gas HCl/SO₂ Ratio on Mercury Speciation in Waste Combustion