Conversion Of Methane Gas Research Articles

Synergistic effect of ultrasound combined with bubble enhanced rapid nucleation and growth of methane hydrate

The synergistic effect between ultrasound and bubbles serves to amplify the nucleation-enhancing effect of bubbles, effectively addressing the crucial challenges of limited gas–liquid interface and intricate nucleation. Based on this, this study proposed a new method of ultrasound combined with microbubbles and bubbling to enhance hydrate nucleation and growth. A visualization experimental system for the growth of methane hydrates enhanced by ultrasound combined with bubbles was developed. The optimal conditions for ultrasound-enhanced methane hydrate nucleation were quantitatively determined. Subsequently, the enhancement effects of ultrasound combined with microbubbles and bubbling systems were systematically analyzed. Under the influence of ultrasound, the nucleation induction period was reduced from 860 min to 7.5 min, and the complete reaction time was shortened to less than 100 min, resulting in a 3.2-fold increase in methane gas conversion. The combination of ultrasound and microbubble method reduced the nucleation induction time to 6.7 min and increased the growth rate by 10.6%. Furthermore, the combination of ultrasound and bubbling method, by fragmenting large nuclei into smaller ones and inducing secondary nucleation, enhanced mass transfer and increased the growth rate of hydrates by 4.4–5.2 times, with a gas conversion increase of 77.5 %–80 %. A novel finding was made in this study, where under the combined effect of ultrasound and bubbling, the stable formation of slurry hydrates was discovered, providing a new idea for the promotion of high-efficiency energy storage technology for hydrates.

Computational fluid dynamics study of hydrogen production using concentrated solar radiation as a heat source

The purpose of this paper is to study the performance of the steam methane reformer (SMR) using solar energy as a heat source using a computational fluid dynamics (CFD) model. An analysis of the flow and heat transfer performance of scaled-up SMR with solar radiation is conducted using a CFD model. The reactor was operated under the predefined thermal conditions (800–1000 K) and steam to carbon ratio (S/C = 2.0–4.0) in order to investigate the effects of operating parameters on hydrogen production. The results indicated that the mass ratio of feed gas and temperature have a significant effect on methane conversion ratio, total hydrogen yield, and composition of reformate gas. Under the operating conditions of S/C = 4.0, 1000 K, 506.5 kPa, the highest CH4 conversion of methane gas is %99.78.The total hydrogen energy yield is 2.41 at this point. In this study, it is also demonstrated that concentrated solar power facilities can be integrated with SMR reactors to supply the energy required to produce H2.

Simulation of generate value for development of biomass plants in Indonesia: a feasibility study

The main purpose of this paper is to define the generating value of biomass plants in Indonesia by a feasibility study. It is important to measure the optimal location to build biomass plants in Indonesia. Besides that. the need of supply of electrical energy in Indonesia is always increase in recent years. Based on data. three cities in Indonesia that potential become location to build those biomass plant from total organic wastes to generate total electricity through conversion of methane gas that produced from waste. In this paper. proposed method of feasibility study performed to achieve optimal value in the construction of biomass power plants and the optimal location to implant. The analysis through the data of total electricity generated from gas that calculated on feasibility aspect values on NPV. IRR. and PI. The result show. in three cities of Indonesia produce a positive feasibility value based on value of IRR that greater than 20% tax so that the Government of Indonesia can implementing biomass plants on those three cities

Radical-initiated oxidative conversion of methane to methanol over metallic iron and copper catalysts

Oxidative conversion of methane gas into value-added chemicals such as methanol is of great interest due to high economic feasibility of liquid fuel molecules for storage and transportation purpose. Activation and conversion of methane occur at very high temperatures due to its strong CH bonding and hence the process is highly energy intensive. Therefore, homolytic cleavage of methane to produce CH3 and H radicals and subsequent conversion to methanol could be an alternative way to catalyze the reaction through a less energy-intensive process. In this work, radical-based conversion of methane to methanol was conducted in water-diluted 1-butyl-3-methylimidazolium chloride ionic liquid (IL) using metallic iron and copper as catalysts. The acidic IL, besides producing the high oxidation potential radicals from K2S2O8, enhanced their longevity. ZV Cu was found to be highly active in the reaction catalyzing with steady rate at a lower activation energy (Ea=31.5kJ/mol) and retains its oxidation state even after the reaction. On the other hand, ZV Fe, catalyzed the reaction with slightly slow initial rate ultimately resulting in moderate activation energy (40.77kJ/mol). However, it was observed that ZV Fe fails to retain its oxidation state after reaction.

Membrane reactor system model for gas conversion to benzene

In the direct nonoxidative conversion of methane gas to liquid chemicals, it has been shown that continuous removal of produced hydrogen is a way to overcome the thermodynamic limit of low equilibrium methane conversion. A plug-flow, isothermal membrane reactor model was developed for the conversion of methane gas to aromatics over Mo/H-ZSM5 and integrated in an Aspen Plus process model using COCO (CAPE-OPEN to CAPE-OPEN) Simulator. Parameters such as reaction rate constants and equilibrium coefficients required by the model were obtained using experimental data. The reactor employs a simplified reaction network whose product distributions agree well with other models and published results. Damkohler number of 0.5 and a dimensionless hydrogen removal parameter δ of 10 were found to be the optimum parameters for benzene selectivity. The reactor model being embedded in the process allows for more detailed exploration of the impact of reactor parameters on the process as a whole. Methane conversion remains at 10.9% and 20% for each case with or without recycle. Benzene molar flow increases by 72% for the single pass configuration when Da=0.5 and δ=10 are used; however, naphthalene molar flow increases by 215%.

Gas-liquid mass transfer coefficient of methane in bubble column reactor

Biological conversion of methane gas has been attracting considerable recent interest. However, methanotropic bioreactor is limited by low solubility of methane gas in aqueous solution. Although a large mass transfer coefficient of methane in water could possibly overcome this limitation, no dissolved methane probe in aqueous environment is commercially available. We have developed a reactor enabling the measurement of aqueous phase methane concentration and mass transfer coefficient (k L a). The feasibility of the new reactor was demonstrated by measuring k L a values as a function of spinning rate of impeller and flow rate of methane gas. Especially, at spinning rate of 300 rpm and flow rate of 3.0 L/min, a large k L a value of 102.9 h−1 was obtained.

Methane conversion in surface- and volume-type dielectric barrier discharges generated in the presence of metal-mesh electrodes

Methane gas conversion was studied in customized flow-type reactors with different dielectric barrier discharge generated in Ar-CH4-O2 gas mixtures. Different reactor geometries (with either volume or surface-type discharges) and different electrode materials were compared, and gas temperatures during methane conversion processes were evaluated. The discharge was generated by applying either a conventional sinusoid or nanosecond-pulsed voltage. The methane conversion rate was as high as ∼99% with the total gas flow rate of 15 sccm, while the temperatures did not exceed 450 K. No significant effect of electrode material (stainless steel, aluminum, or CuO coated copper) was found, confirming that the conversion temperatures were much lower than those required for activity of typical catalysts. The reactor geometry, flow rate, and oxygen amount could be used to govern both the methane conversion rate and the fractions of components in the final product.

Hollow Silica: A novel Material for Methane Storage

Methane gas storage in the form of Methane Hydrate (MH) in hollow silica was studied and compared with solid silica and pure water systems. The gas hydrate growth/dissociation was monitored by following the pressure (gas intake) – temperature variations in a classical isochoric process. The effect of stirring on the hydrate formation kinetics and yield was clearly evidenced in the case of solid and pure water systems, whereas it did not show any influence in hollow silica; and in fact, the yields remained identical in both stirring and non-stirring experiments. Approximately 3.6 m.mol of methane per gram of water was consumed as MH in the hollow silica matrix and the formation kinetics was extremely fast (~180 min). However, the methane gas conversion into MH in solid silica and pure water systems was ~ 10 times higher in a stirred reactor when compared with a non-stirred system.

Influence of glass and gold sealants materials on oxygen permeation performances in La 0.8Sr 0.2Fe 0.7Ga 0.3O 3− δ perovskite membranes

Gas dissociation with a ceramic membrane is an economical and environmental attractive process for methane gas conversion into syngas (mixture of H 2 and CO). For this application, the membrane materials require mixed ionic and electronic conductivities in a large range of pO 2 resulting in an excellent oxygen semi-permeation of the membrane to improve methane conversion. In this paper, particular attention is given to the influence of sealant materials on oxygen semi-permeation performances of membrane materials. For instance, oxygen semi-permeation measurements have been performed with La 0.8Sr 0.2Fe 0.7Ga 0.3O 3− δ membranes under an oxygen partial pressure gradient at temperatures from 700 °C to 1000 °C with different sealing materials (glass or gold ring sealant) between the membrane and the support. The result leads to a better understanding of the effects of sealing on oxygen transport through the La 0.8Sr 0.2Fe 0.7Ga 0.3O 3− δ membrane. Indeed, a gold sealing material is required for accurate measurements of oxygen semi-permeation flux.

Effect of cooling rate on methane hydrate formation in media

In order to study gas hydrate in media, formation of methane hydrate in three different media including loess, fine and coarse sands were studied. Five cooling rates were applied to form the methane hydrate. The nucleation time of the formation of methane hydrate with each cooling rate were measured for comparison. The experimental results show that the cooling rate is a significant factor affecting nucleation of methane hydrate and gas conversion. Under the same initial conditions, the faster the cooling rate, the shorter the nucleation time and the lower the methane gas conversion rate. The media also affect the formation process of methane hydrate within it. In loess, the gas conversion rate is lowest; in coarse sand, the gas conversion rate is the greatest; and in fine sand, it is in between. According to the study, it is found that the smaller the particle size of the media, the harder the methane hydrate forms within it.

Experimental studies of the formation and dissociation of methane hydrate in loess

In order to study the nature of gas hydrate in porous media, the formation and dissociation processes of methane hydrate in loess were investigated. Five cooling rates were applied to form methane hydrate. The nucleation times of methane hydrate formation at each cooling rate were measured for comparison. The experimental results show that cooling rate is a significant factor affecting the nucleation of methane hydrate and gas conversion. Under the same initial conditions, the faster the cooling rate, the shorter the nucleation time, and the lower the methane gas conversion. Five dissociating temperatures were applied to conduct the dissociation experiment of methane hydrate formed in loess. The experimental results indicated that the temperature evidently controlled the dissociation of methane hydrate in loess and the higher the dissociating temperature, the faster the dissociating rates of methane hydrate.

Treatment Feasibility of NSSC Pulping Effl uent using UASB Reactor

The safe disposal of black liquor generating from Neutral Sulfide Semi-Chemical pulping section of the paper mills is one of the challenging issue in the developing countries. A treatment feasibility study was conducted on a laboratory scale UASB (Upflow Anaerobic Sludge Blanket) reactor running on continuous flow basis for about 30 weeks at neutral pH and at constant temperature of 33°C. It is observed that about 35% of black-liquor COD could be reduced at a hydraulic retention time of 38 hours and at an organic loading rate of 2.75 kg-COD/m3-day. The average gas production and methane gas conversion at optimum conditions was observed to be 0.17 m3/kg-CODrem-day and 0.88 L-CH4/g-CODrem-day, respectively. The overall methane composition was noticed to be 61% of the biogas. This study suggests that the post-treatment of NSSC pulping effl uent is required to meet the safe effl uent disposal standards. Key words: NSSC pulping; UASB; Anaerobic digestion; Lignin-COD; PakistanDOI: 10.3126/hn.v5i0.2489Hydro Nepal Vol. 5, July 2009 Page:46-49