• Title/Summary/Keyword: Nitrogen bubbling

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Effects of Additional Bubbling on RH Vacuum Degassing Process with Water Model Experiment (수모델을 사용한 RH 진공 탈가스장치에서의 추가 버블링 효과)

  • Jang, Young-Hwan;Kim, Young-Tae;Yi, Kyung-Woo
    • Korean Journal of Metals and Materials
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    • v.48 no.5
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    • pp.424-429
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    • 2010
  • In the RH process, it is possible to obtain quicker processing times by enhancing the decarburization rates at a low carbon range of steel melt through Ar gas injection into the vacuum vessel. The RH decarburization reaction was simulated through a dissolved oxygen removal reaction by injecting nitrogen into a 1/8 scale RH water model system. The gas nozzles for the N$_{2}$ injection into the vacuum vessel were located at the lowest level of the vessel's outer wall. The nitrogen bubbling in the vacuum vessel resulted in an increase in the reaction rate constant, which rose in accordance with an increase in the bubbling flow rate and number of nozzles used. However, there was almost no variation in the reaction rate constant, which depended on the horizontal positions of the bubbling nozzles.

Extraction Equilibria and Solvent Sublation for Determination of Ultra Trace Bi(Ⅲ), In(Ⅲ) and TI(Ⅲ) in Water Samples by Ion-Pairs of Metal-2-Naphthoate Complexes and Tetrabutylammonium Ion

  • Kim, Young-Sang;Choi, Yoon-seok;Lee, Won
    • Bulletin of the Korean Chemical Society
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    • v.23 no.10
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    • pp.1381-1391
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    • 2002
  • The solvent sublation using ion pairs of metal-2-naphthoate(2-HNph) and tetrabutyl ammonium ($TBA^+$) ion has been studied for the concentration and determination of ultra trace Bi(III), In(III) and Tl(Ⅲ) ions in water samples. The partition coefficients ($K_p$) and the extraction percentages of 2-HNph and the ion pairs to methyl isobutyl ketone (MIBK) were obtained as basic data. After the ion pair $TBA^+$·M$(Nph)_4^-$ was formed in water samples, the analytes were concentrated by the solvent sublation and the elements were determined by GF-AAS. The pH of the sample solution, the amount of the ligand and counter ion added and stirring time were optimized for the efficient formation of the ion pair. The type and amount of optimum surfactant, bubbling time with nitrogen and the type of solvent were investigated for the solvent sublation as well. 10.0 mL of 0.1 M 2-HNph and 2.0 mL of 0.1 M $TBA^+$ were added to a 1.0 L sample solution at pH 5.0. After 2.0 mL of 0.2%(w/v) Triton X-100 was added, the ion pairs were extracted into 20.0 mL MIBK in a flotation cell by bubbling. The analytes were determined by a calibration curve method with measured absorbances in MIBK, and the recovery was 80-120%.

Solvent Sublation of Trace Noble Metals by Formation of Metal Complexes with 2-Mercaptobenzothiazole

  • Kim, Yeong Sang;Sin, Je Hyeok;Choe, Yun Seok;Lee, Won;Lee, Yong Il
    • Bulletin of the Korean Chemical Society
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    • v.22 no.1
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    • pp.19-24
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    • 2001
  • A solvent sublation has been studied for the determination of trace Au(III), Pt(IV) and Pd(II) in waste water with their complexes of 2-mercaptobenzothiazole (MBT). Experimental conditions such as the concentration of HCl, the amount of MBT as a ligand, the type and amount of surfactants, bubbling rate and time, and the type of organic solvent were optimized for the solvent sublation, i.e., 25.0 mL of 2.0 M HCl solution and 30mL of 0.4%(w/v) MBT ethanolic solution were added to a 1.0 L sample to form stable complexes. The addition of 4.0 mL of 1 ${\times}$$10^{-3}$ M CTAB (cetyltrimehtylammonium bromide) solution was needed for the effective flotation accomplished by bubbling nitrogen gas at the rate of 40.0 mL/min for 35 minutes. As a solvent, 20.0 mL of MIBK (methylisobuthylketone) was used to extract the floated complexes. The procedure was applied to three kinds of waste waters. Au(III) was determined as 0.68 ng/mL and 0.98 ng/mL respectively for final washed water of two plating industries in Banwol. Pd(II) and Pt(IV) were not detected in any of the three samples. The recovery, which was obtained with analyte-spiked samples, were 95-120%.

Inhibition of Photooxidation by Breakdown of ChlorophyII in Oil Model System Using Gamma Irradiation (감마선 조사된 유지 model system의 chlorophyII 제거 및 광산화 억제)

  • Lee, Kyong-Haeng;Jo, Cheo-Run;Yook, Hong-Sun;Byun, Myung-Woo
    • Korean Journal of Food Science and Technology
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    • v.33 no.6
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    • pp.693-699
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    • 2001
  • ChlorophyII destruction by irradiation in linoleic acid in methanol system was studied. ChlorophyII b standard (3 ppm) was added into methanol solution containing 1% of linoleic acid, and the sample was irradiated up to 20 kGy with or without nitrogen gas-bubbling. The content of chlorophyII b was analyzed by HPLC, and Hunter color value and UV-visible spectra were analyzed during 6 hr of photooxidation. The content of chlorophyll was reduced by irradiation and completely destroyed at 2.517 kGy. The model system with nitrogen gas-bubbling did not develop the lipid oxidation after irradiation or photooxidation at 20 kGy UV-visible spectra showed decreasing values of optical density by increase of irradiation doses, supporting the destruction of chlorophyII b. The results indicate that irradiation technology can be applied to reduce or eliminate the residual chlorophyII and to prolong the shelf-life of oil products.

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Inhibition of Pitting Corrosion Failure of Copper Tubes in Wet Sprinkler Systems (스프링클러 구리배관의 공식 파손 억제)

  • Suh, Sang Hee;Suh, Youngjoon;Lee, Jonghyuk;Kwon, HyukSang
    • Corrosion Science and Technology
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    • v.19 no.2
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    • pp.89-99
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    • 2020
  • The inhibition of pitting corrosion failure of copper sprinkler tubes in wet sprinkler systems was studied. First, an apparatus and technology for removing air in the sprinkler tubes by vacuum pumping and then filling the tubes with water were developed. Using this apparatus and technology, three methods for inhibiting the pitting corrosion of the copper sprinkler tubes installed in several apartment complexes were tested. The first one was filling the sprinkler tubes with water bubbled by high-pressure nitrogen gas to reduce the dissolved oxygen concentration to lower than 2 ppm. In the second method, the dissolved oxygen concentration of water was further reduced to lower than 0.01 ppm by sodium sulfite. In the third method, the sprinkler tubes were filled with benzotriazole (BTAH) dissolved in water. The third method was the most effective, reducing the failure frequency of the sprinkler tubes due to pitting corrosion by more than 80%. X-ray photoelectron spectroscopy analyses confirmed that a Cu-BTA layer was well coated on the inside surface of the corrosion pit, protecting it from corrosion. A potentiodynamic polarization test showed that BTAH should be very effective in reducing the corrosion rate of copper in the acidic environment of the corrosion pit.

Catalytic Fast Pyrolysis of Tulip Tree (Liriodendron) for Upgrading Bio-oil in a Bubbling Fluidized Bed Reactor

  • Ly, Hoang Vu;Kim, Jinsoo;Kim, Seung-Soo;Woo, Hee Chul;Choi, Suk Soon
    • Clean Technology
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    • v.26 no.1
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    • pp.79-87
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    • 2020
  • The bio-oil produced from the fast pyrolysis of lignocellulosic biomass contains a high amount of oxygenates, causing variation in the properties of bio-oil, such as instability, high acidity, and low heating value, reducing the quality of the bio-oil. Consequently, an upgrading process should be recommended ensuring that these bio-oils are widely used as fuel sources. Catalytic fast pyrolysis has attracted a great deal of attention as a promising method for producing upgraded bio-oil from biomass feedstock. In this study, the fast pyrolysis of tulip tree was performed in a bubbling fluidized-bed reactor under different reaction temperatures, with and without catalysts, to investigate the effects of pyrolysis temperature and catalysts on product yield and bio-oil quality. The system used silica sand, ferric oxides (Fe2O3 and Fe3O4), and H-ZSM-5 as the fluidized-bed material and nitrogen as the fluidizing medium. The liquid yield reached the highest value of 49.96 wt% at 450 ℃, using Fe2O3 catalyst, compared to 48.45 wt% for H-ZSM-5, 47.57 wt% for Fe3O4 and 49.03 wt% with sand. Catalysts rejected oxygen mostly as water and produced a lower amount of CO and CO2, but a higher amount of H2 and hydrocarbon gases. The catalytic fast pyrolysis showed a high ratio of H2/CO than sand as a bed material.

A Study on Characteristics of Direct Contact LNG Evaporator (직접접촉식 액화천연가스 기화기의 특성에 관한 연구)

  • 한승탁;김종보
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.4
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    • pp.903-911
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    • 1994
  • This study addresses the phenomena of bubbling, icing, eruption, component varieties of the evaporated natural gas, and volumetric heat transfer coefficients obtained during the operation of a proposed LNG evaporator between LNG and water in direct contact. In the present investigation, the explosive and eruption phenomena within the water column were not observed during the entire operation of the heat exchanger. Compared with the natural gas produced by conventional LNG evaporator, the analysis of the gas produced by the direct contact LNG evaporator shows that nitrogen, methane, and ethane components were reduced by 0.002~0.007mol%(4~14%), 1.6~1.92mol%(1.9~2.3%) and 0.17~1.28mol%(1.1~8.4%) respectively, while the moisture content was rather increased by 0.51~0.76mol%. The maximum volumetric heat transfer coefficient of the direct contact heat exchanger was found to be $21, 800kW/m^3\cdotK$.

Organic Precipitate Flotation of Trace Metallic Elements with Ammonium Pyrrolidinedithiocarbamate (II). Application of Solvent Sublation for Determination of Trace Cd, Co, Cu and Ni in Water Samples

  • 김영상;정용준;최희선
    • Bulletin of the Korean Chemical Society
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    • v.19 no.1
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    • pp.50-56
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    • 1998
  • A solvent sublation was studied for the determination of trace Cd, Co, Cu and Ni in water samples. Ammonium pyrrolidine dithiocarbamate (APDC) was used as a complexing agent. Experimental conditions such as pH of solution, amounts of APDC, the type and amount of surfactant, the type of solvent, etc. were optimized for the effective sublation of analytes. After metal-PDC complexes were formed in sample solutions of pH 2.5, the precipitate-type complexes were floated in a flotation cell with an aid of sodium lauryl sulfate as a surfactant and by bubbling with nitrogen gas. The precipitates were dissolved and separated into the surface layer of methyl iso-butyl ketone (MIBK). The analytes preconcentrated were determined by a graphite furnace atomic absorption spectrophotometry (GF-AAS). Extractability of each element was 88% for Cd(Ⅱ), 86% for Co(Ⅱ), 95% for Cu(Ⅱ) and 76% for Ni(Ⅱ), respectively. And this procedure was applied to the analysis of real samples. From the recoveries of more than 92%, it was concluded that this method could be simple and applicable for the determination of trace elements in various water samples of a large volume.

Experimental Study of Co-firing and Emission Characteristics Fueled by Sewage Sludge and Wood Pellet in Bubbling Fluidized Bed (기포 유동층 반응기를 이용한 하수슬러지 및 우드펠렛 혼소에 관한 연소 특성 분석 및 비교)

  • Lee, Youngjae;Kim, Jongmin;Kim, Donghee;Lee, Yongwoon
    • Clean Technology
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    • v.23 no.1
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    • pp.80-89
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    • 2017
  • The bubbling fluidized bed (BFB) reactor with a diameter of 0.1 m and a height of 1.2 m was used for experimental study of co-firing and emission characteristics fueled by sewage sludge (SS) and wood pellet (WP). The facility consists of a fluidized bed reactor, feeding system, cyclone, condenser and gas analyzer, The mean particle diameter and minimum fluidization velocity are $460{\mu}m$ and $0.21ms^{-1}$ respectively. SS produced from Korea and WP from Canada were examined. The various mixing ratios of WP were 20, 50, and 80% based on HHV. The equivalence ratio of 1.65, reactor temperature of $800^{\circ}C$, air flow rate of $100Lmin^{-1}$, and fluidization number of 4 were fixed in the BFB experiment. In TGA, the range of combustion temperature of SS was wider than that of WP. It represents that the combustibility of WP is higher than that of SS. The BFB reactor temperature was maintained between 800 and $900^{\circ}C$. CO emission of SS was high because of lower combustibility. $NO_X$ and $SO_X$ formation of SS were higher than that of WP since high nitrogen and sulfur contents of SS. CO, $NO_X$, and $SO_X$ formation were suppressed as the mixing ratio of WP was increased. The slagging and fouling tendencies show high in all test conditions.

Study on the Measurement of Emission Spectrum and Reaction Mechanism of OH Radical in the Nitrogen Corona Discharge System for Removal of $NO_x$ in Flue Gas (배연가스의 $NO_x$제거용 코로나 방전장치에서 OH 발광 스펙트럼 측정 및 관련 반응 연구)

  • Park, Chul-Woung;Hahn, Jae-Won;Shin, Dong-Nam
    • Journal of the Korean Society of Combustion
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    • v.4 no.1
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    • pp.27-38
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    • 1999
  • We constructed a wire-cylinder type pulsed corona discharge system for $NO_x$ removal, which was operated in room temperature. A emission spectrometer was built with a boxcar averager and monochrometer equipped with photo-multiplier tube detector. The sensitivity of the emission spectrometer was greatly improved by synchronizing the emission spectrometer with pulsed corona discharge system using a triggered spark-gap switch. $N_2$ spectrum($c^3{\Pi}_u{\rightarrow}X^1{\Sigma}_g{^+}$) was measured in the range of 300 - 450 nm and oxidizing OH radical emission($A^2{\Sigma}^+{\rightarrow}X^2{\Pi}$) was measured in case $N_2$ was supplied with water bubbling. As wet gas composition of inlet $N_2$ supplied in the discharge system increased, the intensity of OH emission was increased and saturated at wet gas composition 50%. We also investigated additive effect of $C_2H_4,\;H_2O,\;H_2O_2$ on the intensity of OR emission and $NO/NO_2/NO_x$ reduction and analysed the related reaction mechanism in corona discharge process. $H_2O_2$ additive increased the intensity of OH emission and $NO/NO_x$ reduction.

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