Hydrogen Ultra Acoustic Kit Download

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Mozell Gentges

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Jul 4, 2024, 10:05:57 AM7/4/24
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Hydrogen is enjoying an unprecedented momentum as many countries directly support investment in hydrogen technologies. Hydrogen production, storage and transportation pose technical challenges, as hydrogen is highly flammable and checking for leaks is an essential step for its safe use.

Hydrogen gas detectors requires the gas to enter the detector. Portable sniffers put operators at risks by being within potential dangerous zones. Outdoors, fixed detectors have high chance of missing hydrogen leaks, as the gas is lighter than air and quickly escape. Infrared detectors (including OGI cameras) do not detect hydrogen, as H2 does not absorbs infrared, like any homonuclear diatomic molecules (N2, O2, etc.).

We gained in terms of reactivity during interventions and in terms of production. For instance, the search for hydrogen leaks used to take 4 to 5 days, but with the Distran camera, 2 to 3 hours are enough.

In addition to being the main driver of lowering CO2 emissions, new ironmaking technologies need to be able to process any type of iron ore directly, preferably in the form of ultra-fines, owing to the steadily increasing amount of ultra-fines resulting from the intensified beneficiation of low-grade ore deposits [13]. Directly using iron ore ultra-fines further decreases energy consumption and CO2 emissions due to the omission of the agglomeration process (e.g., pelletizing) [3,8,14]. Based on these technological circumstances, the fluidized bed technology using hydrogen is of interest [5,15]. Schenk classified direct reduction processes according to the iron ore and energy source, gas production and reactor system for the reduction stage, given in Figure 1 [5].

The Finmet and Circored processes are identified as direct reduction technologies that directly use a hydrogen-rich reducing gas and iron ore fines. The feed material for the Finmet process is sinter feed ore, meaning a particle size distribution mainly between 0.05 and 8 mm, while the feed material for the Circored process is between 0.1 and 2.0 mm, meaning crushing of oversized sinter feed ore and microgranulation of undersized pellet feed ore [5,15,16,17,18]. The newly developed HYFOR process shows similarities to Finmet and Circored by means of a direct reduction technology using a hydrogen-rich gas or even 100% hydrogen as the reducing gas and iron ore fines directly [19]. However, the feed material is in the form of ultra-fines, such as pellet feed ore, i.e., a particle size distribution of

To achieve these advantages, technological challenges need to be solved in the HYFOR process development. The main issue for a direct reduction process based on fluidized bed technology is to keep the fluidization stable throughout the transformation of the iron oxide phases of the ore to metallic iron. Several authors have reported fluidization problems caused by changing surface morphology of the iron ore particles during reduction and due to sticking [20,21,22,23,24,25,26,27,28,29,30,31,32]. In addition, forming a dense iron layer around the particles prolongs the reduction [21,29,33,34]. Hence, for hydrogen-based reduction of iron ore ultra-fines in a fluidized bed, it is critical to focus on the fluid dynamics of the fluidization and the reduction in terms of morphological evolution of the material.

In the first type of sticking, the generated iron whiskers are fibrous metallic iron precipitation. Interlocking of these whiskers from particles causes the formation of agglomerates [28,52,61,62]. The conditions are given for the reaction-controlled situation when the generation rate of iron ions on the surface of the particles is much slower than the solid-state diffusion rate [23,34,63,64]. The entire particle is like a reservoir for storing iron ions until the critical lowest nucleation free energy at the surface is reached. At this point, the iron nuclei form and with the continuous supplement of iron ions, the whiskers grow away from the surface. Gong et al. explained the growth of iron whisker via vacancy defects on the surface of the iron whisker, which favors the diffusion of iron atoms und thus the sticking of the iron particles [28]. Gudenau et al. and Du et al. claimed that this type is not relevant for iron oxide reduction with hydrogen [23,58]. In contrast, Moujahid and Rist as well as Gransden and Sheasby reported the formation of iron whiskers for hydrogen-based reduction [34,51]. Hayashi and Iguchi found that the formation of iron whiskers during reduction with hydrogen can be suppressed by additional hydrogen sulfide in the gas [22,65]. The practical usage of this action is, however, questionable.

The second type of sticking results from the increased adhesion and friction among particles caused by the high surface energy and viscosity of the highly active new metallic iron [55,61,62,66]. Tardos et al. define the adhesive properties for a softened material with the surface viscosity of the particle, assuming its surface behaves as a Newtonian fluid, so surface deformation occurs under a given shear field [67]. Authors have also found that the solid-state diffusion of the freshly formed metallic iron results in interconnected solid bridges between the particles [56,66,68]. Consequently, the particles tend to agglomerate, especially at high reduction rates and temperatures. This type of sticking dominates for the reduction with hydrogen.

The effect of the complex acoustic-radio wave treatment of water on the index of activity of the hydrogen ions, the rheological characteristics of the cement-sand mixtures tempered by this water, and the technological parameters of the obtained plasticized fine-grained concretes was studied. Two methods were used to reach the maximum effect on the index of the activity of the hydrogen ions of the water, the mobility, the storability of the prepared concrete mixes, and the density and compressive strength of the concretes. The first method was a four-minute complex acoustic-radio wave treatment of the water (high frequency (5.28MHz) + ultra sound (44 kHz)) that was followed by the four-minute additional impact of a high-frequency field. The second method used was a four-minute complex treatment of used water (high frequency (5.28 MHz) + ultra sound (1 MHz)) followed by the two-minute extra impact of a high frequency field. The assumptions concerning the mechanism of the acoustic-radio waves activation of the water and the effect of this water on the process of hardening used and the structure of the Portland cement systems are expressed.

RMIT researchers say they've unlocked cheaper, more energy-efficient green hydrogen production with a new electrolysis technique boosted by sound waves. With these high-frequency vibrations active, standard electrolysis produces 14x more hydrogen.

Where batteries can't carry enough energy, or take too long to charge, green hydrogen is rising as an important zero-emissions fuel that carries a higher density of electrons and supports fast refueling. Green hydrogen is created through electrolysis; splitting water molecules into hydrogen and oxygen using renewable energy to attract each gas to a different electrode, where the hydrogen can be captured, compressed and stored.

So this isn't a situation where, for a given amount of energy put into an electrolyzer, you get 14 times more hydrogen. It's a situation where the water gets split into hydrogen and oxygen more quickly and easily. And that does have an impressive effect on the overall efficiency of an electrolyzer. "With our method, we can potentially improve the conversion efficiency leading to a net-positive energy saving of 27%," said Professor Leslie Yeo, one of the lead researchers.

Abstract:Hydrogen is receiving increasing attention as a versatile energy vector to help accelerate the transition to a decarbonised energy future. Gas turbines will continue to play a critical role in providing grid stability and resilience in future low-carbon power systems; however, it is recognised that this role is contingent upon achieving increased thermal efficiencies and the ability to operate on carbon-neutral fuels such as hydrogen. An important consideration in the development of gas turbine combustors capable of operating with pure hydrogen or hydrogen-enriched natural gas are the significant changes in thermoacoustic instability characteristics associated with burning these fuels. This article provides a review of the effects of burning hydrogen on combustion dynamics with focus on swirl-stabilised lean-premixed combustors. Experimental and numerical evidence suggests hydrogen can have either a stabilising or destabilising impact on the dynamic state of a combustor through its influence particularly on flame structure and flame position. Other operational considerations such as the effect of elevated pressure and piloting on combustion dynamics as well as recent developments in micromix burner technology for 100% hydrogen combustion have also been discussed. The insights provided in this review will aid the development of instability mitigation strategies for high hydrogen combustion.Keywords: hydrogen; gas turbines; combustion; thermoacoustic instabilities; lean premixed; micromix

Intensive research has been conducted on hydrogen-involved combustion instability. Matsuyama et al.10 conducted LES (large eddy simulations) on a single-element atmospheric combustor. It is found that the primary driving mechanism of 1k Hz combustion instability is the acoustically coupled pulsating motion of the inner H2/O2 flame or periodic ignition of H2/O2 mixture. Recently, Hemchandra et al.11 discovered that there are two different mechanisms driving combustion instability. One is a strong coupling between acoustics and hydrodynamic modes. The other one is a weak coupling resulting in semi-open-loop forcing of the flame by a self-sustained hydrodynamic mode. Urbano and Selle12 analyzed transverse combustion instabilities in a reduced-scale rocket motor. The interaction between acoustics and vorticity is found to be the main damping mechanism for coaxial H2/O2 flame-sustained instability. Injector-driven combustion instabilities are experimentally observed in a hydrogen/oxygen rocket motor13. The observed instabilities are a result of the interaction between the injector resonant frequencies and the combustion chamber resonant frequencies.

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