Characteristics of Desulfurization Reaction by Shells.

Nishimura, Kiyoshi; Ohtake, Kazutomo; Kawabe, Teisuke

doi:10.1252/kakoronbunshu.21.904

Cited by 13 publications

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“…100 vol % CH 3 COOH(aq). Figure shows the differential pore volume of the samples (Okayama): the pore size distributions of the nonswelled−calcined sample observed almost agree with those previously reported; , the size of pore formed by the swelling method is distributed in three classes, from 10 to 100 nm, from ca. 0.2 μm to ca.…”

Section: Resultssupporting

confidence: 86%

“…Naruse et al reported that pores with an average diameter between 1 and 1.6 µm are responsible for the high SO 2 capture capacity of calcined shells. 15 Harman and Coughlin also reported that pores with diameters larger than 0.796 µm were responsible for the high capacity of calcined limestone. 8 This pore size range curiously coincided with that of the second class macropore produced by the swelling in this study.…”

Section: Resultsmentioning

confidence: 95%

“…In previous reports, the improvement of the reactivity of lime for SO 2 capture by the swelling method was thought to be induced by the formation of macropores shown in Figure . Naruse et al reported that pores with an average diameter between 1 and 1.6 μm are responsible for the high SO 2 capture capacity of calcined shells . Harman and Coughlin also reported that pores with diameters larger than 0.796 μm were responsible for the high capacity of calcined limestone .…”

Section: Resultsmentioning

confidence: 99%

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Preparation of Macroporous Lime from Natural Lime by Swelling Method with Acetic Acid for High-Temperature Desulfurization

Sasaoka

Sada

Uddin

1998

Ind. Eng. Chem. Res.

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To develop a highly active calcium oxide high-temperature desulfurization sorbent, a method of preparation of macroporous calcium oxides from lime was studied. This method is composed of two steps: swelling of the lime and calcination of the swelled sample. Swelling occurred when lime was exposed to the vapor of acetic acid. The swelling resulted from calcium acetate formation in the sample. The swelling rate was at a maximum in the presence of acetic acid and depressed by the presence of water vapor. The swelled sample was converted to macroporous calcium oxide by heating to 850 °C. The reactivity of the macroporous calcium oxide for the removal of SO2 or H2S in the presence of H2O vapor was higher than that of the calcined raw limestone. In particular, its SO2 removal capacity and the oxidative character of CaS to CaSO4 and CaO were greatly improved by this swelling method. These characteristics were also compared with those of a sample prepared from limestone by this swelling method.

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

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Preparation of Macroporous Lime from Natural Lime by Swelling Method with Acetic Acid for High-Temperature Desulfurization

Sasaoka

Sada

Uddin

1998

Ind. Eng. Chem. Res.

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“…One potential adsorbent is recycled scallop shell, which has been utilized previously as a removal agent for harmful substances; for example, as an aldehyde remover, 5)7) volatile organic compounds adsorbent, 5),6),8) desulfurization material, 9),10) and dephosphorization material. 11) It is expected that waste scallop shells, which are currently discarded, can be utilized as raw materials for inexpensive and environmentally friendly agents that remove harmful substances.…”

Section: Introductionmentioning

confidence: 99%

Removal of strontium from aqueous solutions using scallop shell powder

Mihara

Shuseki

Tamura

et al. 2019

J. Ceram. Soc. Japan

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It is important to efficiently remove radioactive substances contained in polluted waters before they are discharged from nuclear power plants. In particular, there is an urgent need for the development of technology that can adsorb radioactive Sr 2+ , but there are currently no inexpensive Sr 2+ adsorbents with low environmental burden. We found that scallop shell powder adsorbs Sr 2+ in aqueous solutions at various initial concentrations. In this study, to obtain fundamental knowledge of the mechanism of Sr 2+ removal using waste scallop shell, we analyzed the removability of Sr 2+ . Scallop shell showed the same capacity to remove Sr 2+ at a high initial concentration (²0.50 g/dm 3 ) as the reagent CaCO 3 , but a clear difference in removability appeared at a low initial concentration (0.010 g/dm 3 ), where scallop shell proved to be superior. In addition, scallop shell powder had slit-shaped pores and a specific surface area of 4.3 m 2 /g. Measurement of the adsorption isotherm in the low concentration aqueous solution showed that Sr 2+ removal occurred by chemisorption; the adsorbed Sr is present on the surface of the scallop shell powder particles.

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“…In this case, the CO 2 produced during the calcination of the seashells is fixed again to the seashells and recycled naturally. Naruse et al, 4 reported that the desulfurization efficiency of the seashells was over twice as high as that of the limestone. This suggests that the seashells could be used as an effective desulfurizer.…”

Section: Introductionmentioning

confidence: 99%

Effect of Alkali Metal Compounds on Limestone Calcination in Desulfurization Process: Molecular Dynamics Simulations

Murakami

Kurita

2006

J. Ceram. Soc. Japan

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In this study, the change in the desulfurization characteristics of limestone induced by adding some alkali metal compounds and chlorides to limestone was investigated by thermobalance experiments. In addition, molecular dynamics MD simulations were performed to elucidate the effect of alkali-metal chloride additions on the CaO calcination for the desulfurization process. The experimental results obtained show that the addition of NaCl into the limestone is the most effective in improving the desulfurization efficiency. The X-ray diffraction analyses of the calcined seashell, limestone and NaCl-doped limestone found that the calcined seashell, as well as the calcined NaCl-doped limestone, have a similar structure as the CaO crystal. These two materials also show a high desulfurization efficiency. The MD simulations show that NaCl doping into the CaO contributes to the crystallization of CaO, while KCl and LiCl dopings have a small contribution. Therefore, the NaCl doping has a predominant effect on the CaO crystallization leading to a high desulfurization efficiency. Key-words : Desulfurization, Calcination, Limestone, Alkali metal compounds, Molecular dynamics simulation, Sodium chloride, Calcium oxide, Seashell 1. Introduction Recently, acid rain has been recognized as one of the most serious global environmental problems. Sulfur oxides SO x are one of the main sources of acid rain. In a bubbling and circulating fluidized bed coal combustors, limestone is directly supplied into the combustors as a desulfurizer in order to decrease the emissions of SO x from coal. Those combustors are operated at temperatures ranging from 1073 to 1173 K. The limestone is calcined and sulfurized optimally under this temperature condition. In practical boilers however, limestone, which mainly consists of CaCO 3 , is fed excessively to improve the contact efficiency between the CaO produced and the SO 2 emitted. When accomplishing more than 90! of the desulfurization efficiency, or burning coal with a sulfur content of more than 1 mass!, it is necessary to add limestone more than four times as much as Ca to S mole ratio. Otherwise, the particle size of the limestone should be fine. 1 ,2 This is because pores inside the CaO particles ought to be plugged as a result of CaSO 4 formation. 3 As the main component of the limestone is CaCO 3 , which is similar to that of seashells, it is possible to use wasted seashells as a desulfurizer. In this case, the CO 2 produced during the calcination of the seashells is fixed again to the seashells and recycled naturally. Naruse et al., 4 reported that the desulfurization efficiency of the seashells was over twice as high as that of the limestone. This suggests that the seashells could be used as an effective desulfurizer. To explain the mechanisms and reasons for the high desulfurization efficiency of the seashells, the chemical compositions and the mean pore size of the seashell and the limestone were analyzed. As a result, the seashell was found to

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Characteristics of Desulfurization Reaction by Shells.

Cited by 13 publications

References 0 publications

Preparation of Macroporous Lime from Natural Lime by Swelling Method with Acetic Acid for High-Temperature Desulfurization

Preparation of Macroporous Lime from Natural Lime by Swelling Method with Acetic Acid for High-Temperature Desulfurization

Removal of strontium from aqueous solutions using scallop shell powder

Effect of Alkali Metal Compounds on Limestone Calcination in Desulfurization Process: Molecular Dynamics Simulations

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