JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Online ISSN : 1881-1299
Print ISSN : 0021-9592
Current issue
Displaying 1-5 of 5 articles from this issue
Editorial Note
Transport Phenomena and Fluid Engineering
  • Yuta Nakatsuchi, Haruka Kido, Akihiro Hamasaki, Shinji Fujimoto
    Article type: Research Paper
    2022 Volume 55 Issue 9 Pages 281-289
    Published: September 20, 2022
    Released on J-STAGE: September 20, 2022
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    In a gas turbine combined cycle power plant with a heat recovery steam generator, ammonia and hydrazine are injected into the boiler feed water, while sodium phosphate is used in the drum boiler water. However, hydrazine is feared to cause health problems, and sodium phosphate may cause phosphoric acid corrosion. An alternative method has been applied in recent years wherein only ammonia is used for water treatment. Although the ammonia concentration in the drum boiler water depends on the gas–liquid distribution coefficient of ammonia, the measured result of the gas–liquid distribution coefficient in the actual plants is found to be smaller than the reported value in the equilibrium state. This is because the boiler feed water passes through the drum boiler before attaining equilibrium. In this study, a novel dynamic model for the gas–liquid distribution of ammonia between the drum boiler water and the drum boiler steam was investigated by applying the two-film theory. Using this novel model, the ammonia gas–liquid distribution coefficient in the drum boiler can be estimated more accurately. Furthermore, the ammonia concentration of the boiler feed water can be determined, even in a water treatment system with only ammonia, which is effective in preventing flow-accelerated corrosion of the drum boiler.

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Chemical Reaction Engineering
  • Shigeru Sugiyama, Akihiko Koizumi, Takahisa Iwaki, Naohiro Shimoda, Yu ...
    Article type: Research Paper
    2022 Volume 55 Issue 9 Pages 290-299
    Published: September 20, 2022
    Released on J-STAGE: September 20, 2022
    JOURNAL RESTRICTED ACCESS

    The dehydrogenation of isobutane to isobutene was accomplished using a NiO/γ-Al2O3 catalyst. Furthermore, significant improvement in the time-on-stream yield of isobutene was achieved. During the normal catalytic dehydrogenation of alkanes, the catalyst is covered by carbon deposition generated during the reaction, which significantly reduces the activity with time-on-stream. Therefore, no examples of the catalytic dehydrogenation of isobutane have yet been reported. This study used either ethane or propane as a source of isobutane to examine whether the activity was improved with time-on-stream. As a result, in the dehydrogenations of both ethane and propane on a NiO/γ-Al2O3 catalyst, the catalytic activity decreased with time-on-stream when the supporting amount of NiO was small. In contrast, when the supporting amount of NiO was large, the catalytic activity improved with time-on-stream. Using a NiO/γ-Al2O3 catalyst with small and large NiO loadings led to similar results to those of isobutane dehydrogenation. In addition, it was confirmed that the dehydrogenation activity was improved with time-on-stream in the catalytic dehydrogenations of ethane, propane, and isobutane using high NiO loadings. The behavior using a moderate amount of NiO loading, which was not detected in the dehydrogenation of isobutane, was also observed, which resulted in a maximum yield of either ethylene or propylene at 2.0 or 3.25 h on-stream, respectively. We concluded that the reason the catalytic activity did not improve with time-on-stream when using a NiO/γ-Al2O3 catalyst was because the supporting amount of NiO was negligible. These results demonstrate that the activity with time-on-stream could also be improved in the dehydrogenations of other alkanes.

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Biochemical, Food and Medical Engineering
  • Takato Mori, Naoto Ishikawa, Hidenori Mimura
    Article type: Research Paper
    2022 Volume 55 Issue 9 Pages 300-306
    Published: September 20, 2022
    Released on J-STAGE: September 20, 2022
    JOURNAL RESTRICTED ACCESS

    The acoustic properties of conventional tissue-mimicking materials (TMMs) used as phantoms for ultrasonic diagnostic equipment are a sound speed of approximately 1540 m/s and an attenuation coefficient of approximately 0.5 dB/(cm·MHz). Although these values agree well with those of the human body, the acoustic properties of conventional TMMs deteriorate over time due to water desorption. Polyurethane (PU) gels are expected to be highly durable with a long lifetime because they do not contain water. However, the sound speed of conventional PU gels is approximately 1430 m/s, which is slower than 1540 m/s required for TMMs. This study develops a TMM using PU gel with acoustic properties similar to those of human tissue. A PU gel is prepared using a randomly copolymerized polyol of poly-tetramethylene-ether glycol and polyethylene glycol and propylene carbonate as a plasticizer. The developed gel has a sound speed of approximately 1540 m/s and an attenuation coefficient of approximately 0.5 dB/(cm·MHz), which are equivalent to the average values of human soft tissue.

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Environment
  • Takaomi Kobayashi, Phan Phuoc Tri
    Article type: Research Paper
    2022 Volume 55 Issue 9 Pages 307-315
    Published: September 20, 2022
    Released on J-STAGE: September 20, 2022
    JOURNAL RESTRICTED ACCESS

    Among various environmental contaminants, As is considered to be one of the most toxic heavy metal pollutants. Since the cleaning process of As-polluted soil has an adverse impact on human health and environment development of an efficient As removal process from soil is urgently required. In this study, high-power ultrasound (US) with 1,200 W at 28 kHz with HCl and NaOH was used for the elution of As from the polluted soil. To identify the optimum parameters, the US washing parameters such as power of exposure, exposure duration, and acid/alkaline concentration were systematically varied for the optimal washing process. An atomic absorption spectroscopy system combined with a hydride vapor generator was used to analyze As concentration in the liquid and solid parts after the washing extraction. When the US output power varied from 200 to 1,200 W, the 1,200 W US washing reached the As elution rate of 97% and 99.6% in the presence of 2 M HCl and 2 M NaOH, respectively for 1 h US operation. Compare to the soil washing method using the shaker, US washing method demonstrated the preferable results under the same experimental conditions. In the US washing extraction of As, the high-power US caused the pulverizing of soil lump enhancing the interaction of chemical additives with the contaminated soil. The result from the X-ray Diffraction and X-ray fluorescence analyses also indicated no significant change in terms of chemical composition and crystallite profile of the soil after treatment.

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