• Transactions of the Korean hydrogen and new energy society
• /
• v.15 no.3
• /
• pp.187-193
• /
• 2004

In this study, Anaerobic sewage sludge in a batch reactor operation at $35^\circ{C}$ was used as the seed to investigate the effect of pretreatments of waste activated sludge and to evaluate its hydrogen production potential by anaerobic fermentation. Various pretreatments including physical, chemical and biological means were conducted to utilize for substrate. As a result, SCODcr of alkali and mechanical treatment was 15 and 12 times enhanced, compared with a supernatant of activated sludge. And SCODcr was 2 time increase after re-treatment with biological hydrolysis. Those were shown that sequential hybridized treatment of sludge by chemical & biological methods to conform hydrogen production potential in bath experiments. When buffer solution was added to the activated sludge, hydrogen production potential increased as compare with no addition. Combination of alkali and mechanical treatment was higher in hydrogen production potential than other treatments.

• Transactions of the Korean hydrogen and new energy society
• /
• v.17 no.1
• /
• pp.90-97
• /
• 2006

Hydrogen is used as a chemical feedstock in several important industrial processes, including oil refineries and petro-chemical production. But, nowadays hydrogen is focused as energy carrier on the rising of problems such as exhaustion of fossil fuel and environmental pollution. Thermochemical hydrogen production by nuclear energy has potential to efficiently produce large quantities of hydrogen without producing greenhouse gases, and research of nuclear hydrogen, therefore, has been worked with goal to demonstrate commercial production in 2020. The oil refineries and petro-chemical plant are very large, centralized producers and users of industrial hydrogen, and high-potential early market for hydrogen produced by nuclear energy. Therefore, it is essential to investigate and analyze for state of domestic hydrogen market focused on industrial users. Hydrogen market of petro-chemical industry as demand site was investigated and worked for demand forecast of hydrogen in 2020. Also we suggested possible supply plans of nuclear hydrogen considered regional characteristics and then it can be provided basis for determination of optimal capacity of nuclear hydrogen plant in 2020.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.9
• /
• pp.136-141
• /
• 2010

In this paper, after the third electrode type oxidant generator which could format non-uniform electric field in water had been manufactured and installed, by direct electrolysis, the effects of the hydrogen potential and oxidation reduction potential characteristics attendant upon electric field change on a higher concentration oxidant generation characteristics were investigated. Consequently, as the third electrode was installed in the middle of two slit electrodes and the polarity of applied power was changed, it was observed that the third electrode system with the positive electrode can generate a higher concentration oxidant, hydrogen potential and oxidation reduction potential as compared with that of the negative electrode. It is because the positive electrode was bombarded mostly energetic electrons and the negative electrode was bombarded mainly by less energetic positive ions.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.11 no.4
• /
• pp.97-104
• /
• 2003

Hydrogen fermentation of food waste and sewage sludge was performed in serum bottles under various volatile solids(VS) concentrations(0.5~5.0%) and mixing ratios of two substrates(0:100-100:0, VS basis). Full quadratic equations, optimal conditions, and 90% acceptable conditions for hydrogen production potential and rate were obtained using cumulative methane production data and response surface methodology. The specific hydrogen production potential of food waste was higher than that of sewage sludge. However, hydrogen production potential increased as sewage sludge composition increased up to 13~19% at all the VS concentrations. The maximum specific hydrogen production potential of 122.9 mL/g $carbohydrate_{added}-COD$ was found at the waste composition of 87:13(food waste:sewage sludge) and the VS concentration of 3.0%. The relationship between carbohydrate concentration, protein concentration, and hydrogen production potential indicated that enriched protein by adding sewage sludge might enhance hydrogen production potential. The maximum specific hydrogen production rate was 111.2 mL $H_2/g$ VSS/h. Food waste and sewage sludge were, therefore, considered as a suitable main substrate and a useful auxiliary substrate, respectively, for hydrogen production.

• Journal of the Korean Institute of Gas
• /
• v.25 no.4
• /
• pp.43-48
• /
• 2021

This study was conducted using FLACS, a specialized gas accident analysis program. Hydrogen refueling stations subject of safety analysis, consist of compression facilities, storage tanks, and hydrogen piping. The safety analysis of potential risk factors was conducted after reflecting the design specifications of major facilities and components, environmental conditions around hydrogen refueling stations, etc. As of 2021, about 70 refueling stations in Korea are available, and 1,200 are scheduled to be introduced in the next 2040. To prepare for possible accidents caused by potential hazards for the safe distribution of hydrogen refueling stations, we intend to derive hydrogen leakage diffusion scenarios and review their safety.

• Transactions of the Korean hydrogen and new energy society
• /
• v.15 no.1
• /
• pp.12-22
• /
• 2004

In order to evaluate the potential of partial hydrocarbon substitution to improve the safety of hydrogen use in general and the performance of internal combustion engines in particular, the outward propagation and development of surface cellular instability of spark-ignited spherical premixed flames of mixtures of hydrogen, hydrocarbon, and air were experimentally studied at NTP (normal temperature and pressure) condition in a constant-pressure combustion chamber. With propane being the substituent, the laminar burning velocities, the Markstein lengths, and the propensity of cell formation were experimentally determined, while the laminar burning velocities and the associated flame thicknesses were computed using a recent kinetic mechanism. Results show substantial reduction of laminar burning velocities with propane substitution, and support the potential of propane as a suppressant of both diffusional-thermal and hydrodynamic cellular instabilities in hydrogen-air flames.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.11
• /
• pp.3265-3268
• /
• 2013

The multi-hydrogen bonded systems with the solvated electrons are investigated at the B3LYP/6-311++$G^{**}$ basis set level. The symmetrical linear geometrical characteristic is common for the dimer systems, while for the tetramer system, the tetrahedron configuration is generated. The NBO charge analyses demonstrate that the multi-hydrogen-multi-electron (mH-ne) coupling exist in these anion systems, as is supported by the electrostatic potential and the molecular orbital analyses. The positive chemical shift value of the central hydrogen ($H_c$) and the negative chemical shift value of the terminal hydrogen ($H_t$) indicate that the $H_c$ is electronegative while the $H_t$ is electropositive, respectively. Strong coupling between two central hydrogen atoms is demonstrated by the large spin-spin coupling constants. The solvated electron donates significant contributions for the stability of these systems.

• Corrosion Science and Technology
• /
• v.2 no.6
• /
• pp.283-288
• /
• 2003

The cathodic protection method is being widely used in marine structural steel, however a high tensile steel like RE 36 steel for marine structural steel is easy to get hydrogen embrittlement due to over protection during cathodic protection as well as preferential corrosion of HAZ(Heating Affected Zone) part. In this paper, corrosion resistance and mechanical properties such as elongation and hydrogen embrittlement were investigated with not only in terms of electrochemical view but also SSRT(Slow Strain Rate Test) method with applied constant cathodic potential, analysis of SEM fractography in case of both As-welded and PWHT(Post-Weld Heat Treatment) of $550^{\circ}C$. The best effect for corrosion resistance was apparently indicated at PWHT of $550^{\circ}C$ and elongation was increased with PWHT of $550^{\circ}C$ than that of As-welded condition. On the other hand. Elongation was decreased with applied potential shifting to low potential direction which may be caused by hydrogen embrittlement, however the susceptibility of hydrogen embrittlement was decreased with PWHT of $550^{\circ}C$ than that of As-welded condition and Q.C(quasi cleavage) fracture mode was also observed significantly according to increasing of susceptibility of hydrogen embrittlement. Eventually it is suggested that an optimum cathodic protection potential range not causing hydrogen embrittlernent is from -770 mV(SCE) to -850 mV(SCE) in As-welded condition while is from -770 mV(SCE) to -875 mV(SCE) in PWHT of $550^{\circ}C$.

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.11a
• /
• pp.299-306
• /
• 2005

Anaerobic fermentation of food waste (FW) and waste activated sludge (WAS) for hydrogen production was performed in CSTR (Continuous Stirred tank reactor) under various HRTs and volumetric mixing ratio (V/V) of two substrates, FW and WAS. The specific hydrogen production potential of FW was higher than that of WAS. However, pH drop in the CSTR for hydrogen production from FW was higher than that from WAS. The maintenance of desired pH during fermentative hydrogen production is regarded as the most important operation parameter for the stable hydrogen production. Therefore, when the potential of hydrogen production from FW and better buffer capacity of WAS, the proper mixture of FW and WAS for fermentative hydrogen production were considered as a useful complementary substrate. The maximum yield of specific hydrogen production, 140 mL/g VSS, was found at HRT of 2 day and the volumetric mixing ratio of 20:80 (WAS : FW). The spatial distribution of hydrogen producing bacteria was observed in anaerobic fermentative reactor using fluorescent in situ hybridization (FISH) method.

• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.5
• /
• pp.58-68
• /
• 2000

When SS400 steel was welded with low hydrogen type and ilmennite type welding, the effect of post-weld heat treatment(PWHT) was investigated with parameters such as micro vickers hardness, corrosion potential, polarization behaviors, galvanic current, Al anode generating current and Al anode weight loss etc. Hardness of each parts(HAZ, BM, WM) by PWHT in case of low hydrogen type and ilmennite type welding was lower than that of each parts by As-welded However hardness of WM area in case of low hydrogen type and ilmennite type welding was the highest among those three parts regardless of PWHT, Whereas in case of ilmennite type welding, WM area was the highest potential among these three parts on galvanic potential series with As-welded while BM area was the highest potential among these three parts by PWHT on the contrary. And in case of low hydrogen type welding, galvanic corrosion and micro cell corrosion of welding parts was decreased with PWHT. However, It was increased with PWHT in case of ilmennite type welding. Moreover Al anode generating current and anode weight loss in case of low hydrogen type was decreased by PWHT compared to As-wedled but, which was increased than that of As-welded in case of ilmennite type welding. Therefore, it is suggested that Corrosion resistance property in case of low hydrogen type welding is increased by PWHT. However its property was devreased with PWHT in case of ilmennite type welding.