Maximum Hydrogen Content Research Articles

Evolution of microbial community structure during biohydrogen production process of palm oil anaerobic sludge

Anaerobic microbial communities and their functions can provide information about waste management practices, as well as reveal novel degradation metabolisms that can be utilized in wastewater treatment. This study was aimed towards sustainable palm oil industry with assessing the microbial evolution during the dark fermentative processing of palm oil anaerobic sludge and palm oil mill effluent (POME) in batch-mode over two-months with a distinct incubation time of 24 h. The process was designed using response surface methodology (RSM) by acclimatization of inoculum using POME with a chemical oxygen demand (COD) of 36 g-COD/l. The effect of mesophilic and thermophilic conditions and pH on COD removal, hydrogen content, and hydrogen yield (HY) were investigated. A potential sample was selected for microbial analysis after the first and second months of operation based on the maximum outputs achieved throughout the experiment. The bacterial community at pH 5.6 and temperature 55 °C with maximum hydrogen content of 64.13 %, and HY of 0.93 ml H2/g-COD was dominated by three phyla: Firmicutes, Actinobacteria, and Bacteroidota. The results obtained from high throughput pyrosequencing showed that how acclimatization period affects the microbial community structure towards Firmicutes phylum, which includes the majority of hydrogen-producing microorganisms.

Properties analysis on interlayer within lithium target and its beam uniformity for accelerator-based Boron Neutron Capture Therapy

In order to enhance the performance and lifetime of the lithium target used in accelerator-based neutron sources for Boron Neutron Capture Therapy (BNCT) treatment, an exploration of target design was conducted based on the 2.8 MeV, 20 mA proton beam. A comparison between scanning magnets and octupole magnets was performed for beam uniform, with octupole magnets selected to effectively avoid localized high thermal densities over short durations. Exploration was conducted on the performance of tantalum and vanadium as interlayers within the lithium target, considering aspects such as cooling, hydrogen diffusion, and neutron performances. This study revealed that, as the majority of energy deposition occurs within the interlayer, the presence of an appropriately thick tantalum or vanadium interlayer has minimal impact on cooling effectiveness, ensuring temperatures remain below 144 °C. The addition of an interlayer effectively reduces the maximum hydrogen concentration in copper, thus preventing copper blistering. Within the investigated thickness range, the interlayer does not affect neutron spectrum in the forward direction of the target, mitigating concerns regarding its impact on beam shaping.

Multi-scale approach to hydrogen susceptibility based on pipe-forming deformation history

Hydrogen-induced-cracking initiates without external loading due to residual stresses. Pipe manufacturing process composed of crimping, U-ing, O-ing, and expansion has a major impact on local hydrogen concentration, as strain pattern evolves from one forming step to another, causing residual stresses that serve as driving force for hydrogen diffusion. The novelty of the presented work lies in the development of a multi-scale approach that links the residual stresses from the macroscopic pipe-forming process with locally dissolved hydrogen atoms in microstructure under the consideration of microstructural heterogeneities to identify areas susceptible to hydrogen-induced-cracking. First, a 3d-pipe-forming-model was built. Second, representative volume elements with lattice defects were generated to analyze hydrogen trapping in microstructure. Third, representative volume elements were placed in the pipe via sub-modeling, so that local loading history of the pipe was assigned to microstructure models. At the end of the pipe-forming process, representative volume elements were loaded with hydrogen on the surface and final hydrogen concentration was simulated based on residual stresses, considering microstructural effects such as grain size/shape, crystallographic texture and hydrogen traps, e.g. dislocations, voids and inclusions. On meso-/macroscale, a combined isotropic–kinematic hardening material model was implemented, while on microscale, a phenomenological crystal-plasticity-hydrogen-diffusion model was coded. According to the multi-scale simulations under the consideration of microstructural effects the bottom center position in the pipe was detected to be critical to hydrogen-induced-cracking as the maximum local hydrogen concentration was predicted at that location. Based on the loading history hydrogen-induced-cracking susceptibility increases from voids to hard and soft non-metallic inclusions.

Nagynyomású hidrogénatmoszférás kemence gyártása szénacélok elridegedésének vizsgálatához

Összefoglalás. A hidrogén tárolása iránti igény egyre növekszik, melynek oka az, hogy a hidrogén mint alternatív energiahordozó jelentős szerepet játszik a szén-dioxidkibocsátás-csökkentési törekvésekben. Azonban, az elridegedési folyamatok körében a hidrogén által előidézett károsodások jelentik a legkomolyabb problémát az acélokra nézve. Kutatómunkánk során egy nagynyomású hidrogénatmoszférás hőkezelésre alkalmas autoklávot terveztünk, majd gyártottunk. Az autoklávban P355 NH minőségű alapanyagból kimunkált szabványos Charpy-féle ütőpróbatesteket hőkezeltünk 150 °C-on, 40 bar túlnyomáson, 200 órán keresztül, tiszta hidrogén atmoszférában. A vizsgálatok eredményei alapján megállapítottuk, hogy a jelentős mértékű elridegedés a hidrogénezési folyamat után sem történt. Summary. The demand for hydrogen storage is growing. The primary reason for this is that hydrogen as an alternative energy carrier is playing a significant role in carbon reduction efforts as a fuel for road and maritime transport. In addition, hydrogen can be seen as a long-term flexible energy storage option. Hydrogen as an energy carrier is expected to play a significant role in residential and industrial use in the future. A first step in this development is the mixing of hydrogen with natural gas in small quantities. Increasing the share of hydrogen would not only reduce CO2 emissions, but would also facilitate the development of different hydrogen production methods and thus reduce production costs. The upper safety limit for hydrogen blending with natural gas is set by the national specification of the natural gas supply, possible material quality restrictions and the tolerance of the most sensitive equipment in the network. For this reason, the maximum allowable hydrogen content in natural gas is generally limited to 2,5%. However, among the embrittlement processes, hydrogen-induced damage is the most serious problem for both non-alloy and low-alloy steels. Atomic hydrogen diffuses in steel at high rates. The diffusion rate is orders of magnitude higher than that of other elements; this is due to the small atomic diameter of hydrogen. To investigate the degradation of different carbon steels in a high-pressure hydrogen atmosphere, a hydrogenation furnace was designed and fabricated at the Department of Materials Science and Engineering at BME. The hydrogenation furnace is the main part of a complex mechanical engineering system, for the operation of which the mechanical, heating, electrical supply, control and gas handling components are indispensable. The entire design process of the furnace was led by József Blücher, Professor Emeritus at BME, with the help of the engineers and technicians working on the project. Standard Charpy impact test specimens were machined from P355 NH grade material to test the embrittlement of carbon steels. The hydrogenation temperature was 150 °C, the internal overpressure in the chamber was 40 bar, the hydrogenation time was 200 hours and the atmosphere was hydrogen gas of purity 5.0. The impact test was carried out at -20, 0 and +20 °C. Based on the results of the tests, it can be concluded that there was no significant degree of degradation both before hydrogenation and after prolonged exposure to hydrogen. It can be concluded that the tube material used as a sample is suitable for operation in a hydrogen medium. Based on the analysis of the burst areas and impact values of the impact test specimens, it was concluded that hydrogen did not cause any observable damage to the test material.

Hydrogen diffusivity, uptake and embrittlement of solution annealed and cold deformed austenitic stainless steel 1.4435 at hydrogen pressures up to 1000 bar and 200 °C

Austenitic stainless steel 1.4435, a candidate material for high-pressure tubing for hydrogen applications, was investigated in two different stages of cold deformation (0 and 27 %) regarding its hydrogen embrittlement tendency. The determination of effective diffusion coefficients revealed slightly increased diffusion kinetics at 60°C for the cold-reduced material (8.0 · 10−15 m²/s) compared to the solution annealed one (5.0 · 10−15 m²/s). High-pressure gaseous hydrogen charging shows no differences regarding the degree of cold deformation with a maximum hydrogen concentration of 112 wt.-ppm. Furthermore, a significant ductility loss expressed by the ratio of the reduction of area was observed.

Process Integration of Hydrogen Production Using Steam Gasification and Water-Gas Shift Reactions: A Case of Response Surface Method and Machine Learning Techniques

An equilibrium-based steady-state simulator model that predicts and optimizes hydrogen production from steam gasification of biomass is developed using ASPEN Plus software and artificial intelligence techniques. Corn cob’s chemical composition was characterized to ensure the biomass used as a gasifier and with potential for production of hydrogen. Artificial intelligence is used to examine the effects of the significant input variables on response variables, such as hydrogen mole fraction and hydrogen energy content. Optimizing the steam-gasification process using response surface methodology (RSM) considering a variety of biomass-steam ratios was carried out to achieve the best results. Hydrogen yield and the impact of main operating parameters were considered. A maximum hydrogen concentration is found in the gasifier and water-gas shift (WGS) reactor at the highest steam-to-biomass (S/B) ratio and the lowest WGS reaction temperature, while the gasification temperature has an optimum value. ANFIS was used to predict hydrogen of mole fraction, 0.5045 with the input parameters of S/B ratio of 2.449 and reactor pressure and temperature of 1 bar and 848°C, respectively. With the steam-gasification model operating at temperature (850°C), pressure (1 bar), and S/B ratio of 2.0, an ASPEN simulator achieved a maximum of 0.5862 mole fraction of hydrogen, while RSM gave an increase of 19.0% optimum hydrogen produced over the ANFIS prediction with the input parameters of S/B ratio of 1.053 and reactor pressure and temperature of 1 bar and 850°C, respectively. Varying the gasifier temperature and S/B ratio have, on the other hand, a crucial effect on the gasification process with artificial intelligence as a unique tool for process evaluation, prediction, and optimization to increase a significant impact on the products especially hydrogen.

Hydrogen production promotion and energy saving in anaerobic co-fermentation of heat-treated sludge and food waste.

The objective of this paper is to gain insights into the synergistic advantage of anaerobic co-fermentation of heat-treated sludge (HS) with food waste (FW) and heat-treated food waste (HFW) for hydrogen production. The results showed that, compared with raw sludge (RS) mixed with FW (RS-FW), the co-substrate of HS mixed with either FW (HS-FW) or HFW (HS-HFW) effectively promoted hydrogen production, with HS-HFW promoted more than HS-FW. The maximum specific hydrogen production (MSHP) and the maximum hydrogen concentration (MHC) of HS-HFW were 40.53mL H2/g dry weight and 57.22%, respectively, and 1.21- and 1.45-fold as high as those from HS-FW. The corresponding fermentation was ethanol type for HS-HFW and butyric acid type for HS-FW. The net energy production from RS-FW and HS-FW was both negative, but it was positive (2.57MJ) from 40% HFW addition to HS-HFW. Anaerobic fermentation was more viable for HS-HFW.

In situ measurement of hydrogen concentration in steel using laser-induced breakdown spectroscopy (LIBS)

AbstractThe ISO 3690 standard “Determination of hydrogen content in arc weld metal” requires a thermal activation of the diffusible hydrogen in a piece of weld metal for the subsequent ex situ concentration measurement by carrier gas hot extraction CGHE or thermal desorption spectroscopy (TCD). Laser-induced breakdown spectroscopy (LIBS) offers a time and spatially resolved, almost non-destructive, in situ measurement of hydrogen at surfaces without sample preparation. We measured hydrogen in steels, which were charged either electrochemically or by high-pressure hydrogen gas, and compared the results. Further, the feasibility of quantitative hydrogen line scan measurements with LIBS was demonstrated by measuring hydrogen at water jet cut surfaces. The hydrogen concentrations measured with the help of LIBS were compared with CGHE measurements. It was observed that hydrogen can be reliably measured with LIBS for concentrations larger than 2 wt.-ppm. The maximum hydrogen concentration achieved using electrochemical charging was 85.1 ppm. The results show that LIBS is a promising technique for time- and spatially resolved measurements of hydrogen in steels.

Optimizing hydrogen gas concentration using response surface methodology (RSM) with design expert 6.0.9 application

The MQ-8 sensor will be used in this investigation to estimate the maximum hydrogen gas concentration generated during the dry cell generators’ electrolysis procedure. The process of water electrolysis involves breaking down the water molecule H2O using direct electric current, into hydrogen gas and oxygen gas. Utilizing DC generators with 4/4 plate electodes (Cu/Al) as the cathodes and NaNO3 solutions as the electrolytes, hydrogen gas production by electrolysis is achieved. 0.6 amps and 2 volts are employed in this electrolysis procedure for a duration of 1 hour. The ideal conditions for hydrogen gas concentration are NaNO3 1 M concentration and 60 minutes with a maximum hydrogen concentration of 143.393 ppm generated. The hydrogen gas concentration verification result value is 144 ppm.

Annealing cracking in Zr and a Zr-alloy with low hydrogen concentration

Hydrogen embrittlement, also known as hydrogen-induced cracking, is a longstanding concern for zirconium (Zr) and its alloys. The affinity for hydrogen in zirconium results in the formation of brittle hydrides. Hydrides are conventionally thought to facilitate crack propagation, and the prevailing recommendation to hinder hydride embrittlement involves reducing the hydrogen concentration in the material and applying slow cooling to reduce thermal stresses. Here, in Zr with a maximum hydrogen concentration of 43 wppm, we show that cracks initiate unexpectedly after annealing, a step that involves slow cooling and no external stress. With a suite of high-resolution microscopy, we show that annealing cracks initiate at prismatic δ-hydrides, whose presence is unexpected. The microscopic annealing crack paths are consequently crystallographic, following the habit plane of these prismatic δ-hydrides. The commonly reported γ-hydride and δ-hydrides that develop on the basal plane are found not to initiate cracks. We rationalize that prismatic δ hydrides result from the intergranular thermal residual stresses that develop during slow cooling. This finding of uncommon annealing cracking further advances the mechanistic understanding of hydride embrittlement in zirconium and can lead to new strategies for design and fabrication of advanced zirconium alloys for harsh environments.

European Green Deal: An Experimental Study of the Biomass Filtration Combustion in a Downdraft Gasifier

This study presents the experimental results obtained from hybrid filtration combustion using biomass pellets. The experiments were carried out using a porous media gasifier filled with pellets and inert material. The gasifying agent used was an air–steam mixture, with 40% being steam. The dependence of the temperature in the gasifier’s reaction zone from the volume percentage of inert porous material in the gasifier, the specific heat capacity of this material, as well as the air–steam blowing rate, was investigated. The multifactor experiment method was used. A maximum temperature of 1245 °C was achieved using 28 vol% of porous material with a heat capacity of 1000 J/(kg·°C) and at a blowing rate of 42 m3/h. The maximum hydrogen content in the syngas was 28 vol%. This was achieved at an air–steam blowing rate of 42 m3/h and 40 vol% porous material, with a heat capacity of 1000 J/(kg·°C). The calorific value of the syngas was 12.6 MJ/m3. The highest CO content in the gas was 28 vol% and was obtained at 20 vol% porous material with a heat capacity of 1000 J/(kg·°C) and a blowing rate of 42 m3/h. The obtained information is applicable in the design, management, and control of gas production by way of a hybrid filtration combustion process in a downdraft gasifier.

Hydrogen embrittlement behavior of two mining chain steels by slow strain rate test

Two mining chain steels 23MnNiMoCr5-4 and 0.3C0.2Si0.3Mn4.2(Cr+Ni+Mo) with tensile strengths of 1200 MPa and 1250 MPa, respectively, were employed to investigate their hydrogen embrittlement behaviors by slow strain rate tests combined with thermal desorption analyses. It is shown that at initial stage the fracture stress decreases linearly as the hydrogen content increases, and the turning points occur at hydrogen content of 1.2 wppm for 0.3C0.2Si0.3Mn4.2(Cr+Ni+Mo) and 0.26 wppm for 23MnNiMoCr5-4. The fractured surface observation suggests that the ratio of intergranular fracture area to quasi-cleavage area increases dramatically at the turning points. The maximum hydrogen contents resulting from the corrosive HCl solutions with pHs of 2 are approximately 0.6 wppm 0.3C0.2Si0.3Mn4.2(Cr+Ni+Mo) and 0.11 wppm for 23MnNiMoCr5-4, corresponding to the activation energies for hydrogen desorption are 21.57 kJ/mol and 14.53 kJ/mol, respectively.

A local stress criterion to assess the effects of hydrogen embrittlement on the fracture strength of notched tensile specimens

This work addresses the applicability of a local criterion incorporating the coupling of critical stress and a critical hydrogen concentration to predict hydrogen embrittlement effects on the fracture strength of high strength steels using notched round specimens with different notch root radii. The numerical simulations incorporating a relatively simple hydrogen transport model provide strong support for the adoption of a failure criterion in terms of achieving a critical level of tensile stress coupled to the local hydrogen concentration, which, in turn, enable the construction of a failure locus for the degraded material. For the cases analyzed here, construction of such a failure locus based on a critical combination of maximum principal stress and hydrogen concentration enabled predictions of fracture strength for hydrogen-charged tensile specimens which are in very good agreement with experimental data. Overall, the results presented here lend additional support for further developments of a local stress-based criterion to predict hydrogen embrittlement effects on the fracture strength of high strength steels.

Anion exchange membrane water electrolysis: Numerical modeling and electrochemical performance analysis

In this paper, a three-dimensional numerical model is developed for an anion exchange membrane electrolyser cell (AEMEC) with a double serpentine flow field pattern. The focus on the AEMEC is due to its benefits, including the solid membrane, inexpensive catalysts and membrane, and high stability. The effect of important operating parameters, i.e. cell temperature and cathode pressure, on the performance of the electrolyser is numerically modeled by considering different causes of performance degradation. The polarization curve, uniformity index, and the distribution of the hydrogen concentration, current density, temperature, and pressure in different operating conditions are presented. By increasing the operating temperature and decreasing the cathode pressure, the voltage of the elctrolyser decreases. Due to the higher concentration of water at the inlet of the cathode channel, more hydrogen is produced, and the current density is higher. The maximum current density and hydrogen concentrations are 7868Am2 and 0.898molm3, respectively, when the operating condition is set to the temperature of 343 K, the pressure of 1 bar, and the cell voltage of 1.85 V.

Development of softening and melting testing conditions simulating blast furnace operation with hydrogen injection

ABSTRACT Softening and Melting (S&M) experiments have evolved alongside the blast furnace as a crucial tool for burden characterisation and optimisation. Modern blast furnaces derive a base load of hydrogen from various sources. However, with hydrogen-enrichment of the blast furnace being considered to mitigate emissions, new S&M test conditions are required. In this study, a 2-D axisymmetric CFD model is used to simulate the internal conditions of a modern blast furnace operation, and a future operation with tuyere level hydrogen injection. The model results are used to guide the development of novel S&M test conditions, inclusive of H2, H2O, CO, CO2 and N2. The maximum hydrogen concentration under hydrogen enrichment was 20%, with the hydrogenous fraction of the gas primarily replacing nitrogen. A particular focus was given to the importance of including water vapour in the inlet gas, andits impact on reactions occurring in the S&M test.

Effect of distance of vertical barrier wall to the release nozzle on the hydrogen concentration profile induced by impingement of unignited release of cryogenic hydrogen

As a recognized clean energy source with advantages of non-pollution, high energy density and less energy loss during the cooling process, cryogenic hydrogen is widely used worldwide. The barrier wall is an effective means of preventing the backward diffusion of jets. However, the effect of distance of vertical barrier wall to the release nozzle on the hydrogen concentration profile is still unknown. In this work, cryogenic hydrogen is released with different distances of the barrier wall (0.20, 0.25, 0.30, 0.35, 0.40 m) and temperatures of cryogenic hydrogen (140, 180, 220, 260, 300 K) experimentally. 10 hydrogen concentration sensors are placed in the horizontal and vertical directions on the barrier wall, respectively, to record the hydrogen concentration. It is found that the maximum hydrogen concentration increases as the distance of the vertical barrier wall decreases. Models of the maximum hydrogen concentration in volume and mass fraction are proposed. The hydrogen concentration increases significantly in the horizontal and vertical directions as the vertical barrier wall is placed closer to the release nozzle. The hydrogen concentration in the horizontal and vertical directions of the vertical barrier wall follows the Gaussian and exponential distribution, respectively. The prediction models of hydrogen concentration in the horizontal and vertical directions are proposed as well. The research results can provide a theoretical basis and data support for the design of safety codes for cryogenic hydrogen storage and the safety distance of barrier walls in hydrogen refueling stations.

A proposed configuration of biomass based combined power and cooling plant and its 6E analyses

The paper reports 6E analyses (energy, exergy, economic, environmental, exergo-economic and exergo-environmental) of a biomass based combined power and cooling plant that uses sawdust as its fuel, steam as its sole gasifying agent. The gasification model includes tar in the producer gas and yields maximum hydrogen content when steam-to-biomass ratio (STBM) and reactor temperature are set to 2 and 800 °C respectively. The performance of the cogeneration plant is assessed by varying different input parameters viz. air compressor pressure ratio (pr) and turbine inlet temperature (TIT). Simulation results show that the optimum performance is achieved when TIT is 1100 °C and pr is in the range of 6 to 8. The exergo-economic factor and exergo-environmental factor are evaluated by considering these optimised conditions. Exergy analysis suggests that the gasifier is subjected to maximum exergy destruction. From economic analysis, the computed effective price of electricity (EPOE) is 0.064 USD/kWh with the discounted payback period of the plant being 8.5 years. The exergo-economic and exergo-environmental factors obtained are 51.5 % and 0.0288 % respectively at the favourable operating conditions.

Innovative Design of Residual Stress and Strain Distributions for Analyzing the Hydrogen Embrittlement Phenomenon in Metallic Materials.

Round-notched samples are commonly used for testing the susceptibility to hydrogen embrittlement (HE) of metallic materials. Hydrogen diffusion is influenced by the stress and strain states generated during testing. This state causes hydrogen-assisted micro-damage leading to failure that is due to HE. In this study, it is assumed that hydrogen diffusion can be controlled by modifying such residual stress and strain fields. Thus, the selection of the notch geometry to be used in the experiments becomes a key task. In this paper, different HE behaviors are analyzed in terms of the stress and strain fields obtained under diverse loading conditions (un-preloaded and preloaded causing residual stress and strains) in different notch geometries (shallow notches and deep notches). To achieve this goal, two uncoupled finite element (FE) simulations were carried out: (i) a simulation by FE of the loading sequences applied in the notched geometries for revealing the stress and strain states and (ii) a simulation of hydrogen diffusion assisted by stress and strain, for estimating the hydrogen distributions. According to results, hydrogen accumulation in shallow notches is heavily localized close to the wire surface, whereas for deep notches, hydrogen is more uniformly distributed. The residual stress and plastic strains generated by the applied preload localize maximum hydrogen concentration at deeper points than un-preloaded cases. As results, four different scenarios are established for estimating "a la carte" the HE susceptibility of pearlitic steels just combining two notch depths and the residual stress and strain caused by a preload.

Optimization of up-flow velocity and feed flow rate in up-flow anaerobic sludge blanket fixed-film reactor on bio-hydrogen production from palm oil mill effluent

The present study aims to optimize key operational parameters of the up-flow anaerobic sludge blanket fixed-film (UASFF) reactor using response surface methodology (RSM). A central composite design (CCD) has been applied to accomplish thirteen experimental runs given two main variables, namely feed flow rate (Qf), and up-flow velocity (Vup). The maximum hydrogen content, hydrogen production rate (HPR), hydrogen yield (HY), and COD removal were achieved at 55%, 4800 mL H2/cycle, 321 mL H2/g-COD, and 24.33%, respectively at Qf 8 L/cycle (HRT = cycle = 10.5 h) and Vup 2.0 m/h. The performance of the parameters from the optimum identified area was assessed at Qf 5.5 L/cycle (HRT = 15.3 h), and Vup 1.8 m/h, resulted in a maximum hydrogen content, HY, and HPR of 72%, 340 mL H2/g-COD, and 5100 mL H2/cycle, respectively. At optimum conditions, Clostridium sensu stricto 1 was found to be the dominant hydrogen-producing bacteria in the system. The results of this study may provide a practical basis for developing a UASFF reactor prototype based on empirical data.

Effect of initial pH and substrate to inoculum ratio on the production of methane and hydrogen from food waste

“Anaerobic co-digestion of food waste, cow dung, and sludge solution is experimented by varying the pH to produce hydrogen and methane as a source of renewable energy. The substrate to inoculum ratio (v/v) of 1:1(S1), 1:2(S2), 1:3(S3), 1:4(S4) and 1:5(S5) are investigated in separate fermentative and methanogenic reactors. A maximum hydrogen and methane concentration of 19.73% and 64.81% respectively are obtained in S3. The methane concentration of 53.67%, 64.81% and 59.64% is observed at the pH variation of 6.5, 7, and 7.5 respectively. The obtained result shows the substrate to inoculum ratio of 1:3 to be the optimal combination for the highest methane and hydrogen production during the anaerobic co-digestion process”.