Evolution of HCl from KCl, CaCl2 and NaCl in an SO2-O2-H2O Atmosphere under a Simulated Condition of Municipal Wastes Incineration.

Ozawa, Shoji; Naruse, Kazumasa; Ito, Keisuke; Kojima, Yoshihiro; Matsuda, Hitoki; Mishima, Shun-ichi; Endo, Masato; Yanase, Tetsuya

doi:10.1252/jcej.36.867

Cited by 6 publications

(4 citation statements)

References 10 publications

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“…They found no effect of quartz wool, but little catalytic effect of the alumina particles, and a strong catalytic effect of the steel chips. The sulfation of solid KCl is known to be slow in the presence of SO 2 , − but orders of magnitudes faster in the presence of SO 3 . , Dennis and Hayhurst investigated the effects of silica sand bed material (particles of 425−500 μm) on the oxidation of SO 2 in a fluidized bed reactor made of 321 stainless steel, in the temperature range of 700−950 °C (1292−1742 °F), and measured SO 2 oxidation rates of approximately 100 times faster than expected for gas-phase oxidation. On the basis of these findings and modeling results, they concluded that the SO 3 was mainly produced on the surface of the quartz sand.…”

Section: Resultsmentioning

confidence: 99%

Lab-scale Investigation of Deposit-induced Chlorine Corrosion of Superheater Materials under Simulated Biomass-firing Conditions. Part 1: Exposure at 560 °C^†

Lith¹,

Frandsen²,

Montgomery³

et al. 2009

Energy Fuels

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Deposit-induced chlorine corrosion was studied under well-controlled laboratory conditions, simulating the conditions in straw-fired boilers and boilers cofiring coal and straw. This was done by exposing pieces of superheater tube (TP 347H FG) covered with synthetic deposits of known Cl content to gas mixtures simulating straw-firing and cofiring of coal and straw, at 560°C (1040°F), for 3 days. The corroded specimens, and the reacted deposits, were studied in detail using a scanning electron microscope to determine the corrosion rate, investigate the chemistry and morphology of the corrosion attack, and study the sulfation behavior. Besides the gas compositions, various parameters were studied systematically. Most specimens suffered some internal attack, mostly by selective corrosion and in some cases by grain boundary attack. In all experiments with KCl and KCl-SiO 2 deposits, the corrosion products consisted of an oxide scale, containing oxides of Cr and Fe, and on top of that a characteristic mixed layer of iron oxide threads in a potassium sulfate matrix. However, the thickness and shape of this layer was found to be strongly dependent on the experimental conditions. An increase of the percentage of KCl in the deposit resulted in a more uniform and deeper internal corrosion attack. The presence of HCl in the flue gas did not seem to be essential for chlorine-induced corrosion to occur, when a deposit containing KCl was present, but it enhanced the corrosion rate. The degree of sulfation of KCl in the deposits after exposure was quantified by wet chemical analysis and was shown to be dependent on many parameters, including the SO 2 concentration in the gas flow, the concentration of KCl in the deposit, and the SiO 2 and KCl particle sizes in the deposit. No simple relation was observed between the degree of sulfation in the deposit and the depth of internal attack or the thickness of the oxide or mixed layer. Whereas SiO 2 particles were found to be chemically inert with respect to the flue gas and the corrosion attack, CaO particles reacted with HCl from the flue gas, and the resulting CaCl 2 played an important role in the corrosion mechanism. As a result, the corrosion rate was strongly enhanced when CaO was present in the deposit, instead of SiO 2 .

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Section: Resultsmentioning

confidence: 99%

Lab-scale Investigation of Deposit-induced Chlorine Corrosion of Superheater Materials under Simulated Biomass-firing Conditions. Part 1: Exposure at 560 °C^†

Lith¹,

Frandsen²,

Montgomery³

et al. 2009

Energy Fuels

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“…When the temperature was increased to 823 K or more, K 2 S 2 O 7 would decompose, which is endothermic. However, there are also some studies concluding that a phase transition occurs at high temperatures. ,, The sulfation at low temperatures may involve a condensed-phase intermediate, perhaps a potassium sulfite. In fact, at low temperatures, K 2 S 2 O 7 was not found in the sulfation products (Figure ).…”

Section: Resultsmentioning

confidence: 99%

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO₂/O₂/H₂O at 523–1023 K

Wang

et al. 2014

Energy Fuels

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Sulfation of condensed alkali chloride significantly affects deposition and corrosion in heat transfer surfaces during biomass combustion. This study investigates the heterogeneous sulfation of condensed potassium chloride (KCl) in a fixed-bed reactor at 523−1023 K with levels of 0.1−2% sulfur oxide (SO 2 ), 2.5−10% oxygen (O 2 ), and 5−15% water vapor. The sulfation rate is determined by measuring the sulfur content in solid residues. No other potassium species are found, and potassium sulfate (K 2 SO 4 ) is the only sulfation product. The KCl sulfation within the temperature range of 523−1023 K was divided into three stages: (1) slow sulfation rate increase below 723 K, (2) slight decline at 723−773 K, and (3) rapid increase over 823 K. The sulfation mechanism transformation occurs between 723 and 823 K. This change in the reaction mechanism is further proven by investigating the effects of SO 2 and O 2 reactants and water vapor at 723 and 923 K. The KCl−K 2 SO 4 mixture forms a eutectic to change the reaction mode at high temperatures, thereby explaining the phenomenon, which is further confirmed by the results of scanning electron microscopy. The sulfation reaction rate of condensed KCl is described by the following expressions: dX/dt = 5.3 × 10 −3 exp(−2120/T)(1 − X) 2/3 (C O 2 ) 0.27 (C SO 2 ) 0.27 (C H 2 O ) 0.42 at 523−723 K and dX/dt = 1.20 × 10 4 exp(−14180/T)(1 − X) 2/3 (C O 2 ) 0.92 (C SO 2 ) 0.39 (C H 2 O ) 0.12 at 823−1023 K.

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Section: Chlorine Release Difference Between Organic and Inorganic Ch...mentioning

confidence: 99%

“…The controlling step is the Langmuir-type adsorption of SO 2 on the NaCl surface, which is kinetically controlled and not that strongly temperature-dependent. Ozawa et al 76 compared the HCl evolution behavior through the sulfation of KCl, NaCl, and CaCl 2 in the presence of SO 2 (0.3−1.3 vol %), O 2 (2.5−15 vol %), and H 2 O (5−20 vol %) in a tubular reactor at 350−850 °C. Figure 9 showed the conversion of each chloride as a function of the reaction time at three temperatures in a fixed atmosphere of 0.9 vol % SO 2 , 5 vol % O 2 , and 10 vol % H 2 O.…”

Section: Energy and Fuelsmentioning

confidence: 99%

Critical Review on the Chemical Reaction Pathways Underpinning the Primary Decomposition Behavior of Chlorine-Bearing Compounds under Simulated Municipal Solid Waste Incineration Conditions

2019

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Incineration has been proven as one of the most viable and efficient waste-to-energy strategies for the handling of rapidly mounting municipal solid waste (MSW). However, as a generic and key element in MSW, chlorine (Cl) brings about severe corrosion in boilers and the presence of Cl-containing species induces the release of toxic dioxins and furans by acting as chlorine donors. The chlorine release behavior from MSW during incineration has thus drawn plenty of attention. This paper has critically reviewed the origin of different chlorine-bearing species in MSW and their respective thermal decomposition behavior. In general, chlorine in MSW has two primary sources: plastics, mainly polyvinyl chloride (PVC), as the source of organic chlorine and household kitchen and garden waste as the source of inorganic chlorine, mainly chlorides. Distinct chlorine liberation properties have been observed for these two different chlorine groups. Chlorine in PVC converts to HCl gas easily at 300 °C as a result of the thermal decomposition combined with a depolymerization of the polymer chain. In contrast, the release of chlorine from inorganic chloride salts is much lower than that from PVC, mainly attributing to either strong volatilization properties of alkali chlorides (NaCl and KCl) or the high ionic bonding energies between some cations, such as Ca2+/Ni2+ and Cl–. Meanwhile, the decomposition of FeCl2, CoCl2, and MgCl2 is easier with the onset temperature for HCl release being around 180, 300, and 415 °C, respectively. Additionally, the addition of SO2, O2, or acidic solids (such as SiO2 and Al2O3) has been found to promote the chlorine release from chlorides appreciably. However, the exploitation of the underpinning mechanism is far from completion, especially for CaCl2 and CoCl2. This requests extra and intensive studies to elucidate the chlorine liberation mechanism from these inorganic species, even from the molecular level in terms of their ionic bonding propensity and breakage at high temperatures.

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Evolution of HCl from KCl, CaCl2 and NaCl in an SO2-O2-H2O Atmosphere under a Simulated Condition of Municipal Wastes Incineration.

Cited by 6 publications

References 10 publications

Lab-scale Investigation of Deposit-induced Chlorine Corrosion of Superheater Materials under Simulated Biomass-firing Conditions. Part 1: Exposure at 560 °C^†

Lab-scale Investigation of Deposit-induced Chlorine Corrosion of Superheater Materials under Simulated Biomass-firing Conditions. Part 1: Exposure at 560 °C^†

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO₂/O₂/H₂O at 523–1023 K

Critical Review on the Chemical Reaction Pathways Underpinning the Primary Decomposition Behavior of Chlorine-Bearing Compounds under Simulated Municipal Solid Waste Incineration Conditions

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Evolution of HCl from KCl, CaCl2 and NaCl in an SO2-O2-H2O Atmosphere under a Simulated Condition of Municipal Wastes Incineration.

Cited by 6 publications

References 10 publications

Lab-scale Investigation of Deposit-induced Chlorine Corrosion of Superheater Materials under Simulated Biomass-firing Conditions. Part 1: Exposure at 560 °C†

Lab-scale Investigation of Deposit-induced Chlorine Corrosion of Superheater Materials under Simulated Biomass-firing Conditions. Part 1: Exposure at 560 °C†

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO2/O2/H2O at 523–1023 K

Critical Review on the Chemical Reaction Pathways Underpinning the Primary Decomposition Behavior of Chlorine-Bearing Compounds under Simulated Municipal Solid Waste Incineration Conditions

Contact Info

Product

Resources

About

Lab-scale Investigation of Deposit-induced Chlorine Corrosion of Superheater Materials under Simulated Biomass-firing Conditions. Part 1: Exposure at 560 °C^†

Lab-scale Investigation of Deposit-induced Chlorine Corrosion of Superheater Materials under Simulated Biomass-firing Conditions. Part 1: Exposure at 560 °C^†

Segmented Kinetic Investigation on Condensed KCl Sulfation in SO₂/O₂/H₂O at 523–1023 K