The work deals with the optimization of methane hydrate storage in fixed-bed reactor systems made up of modified silica beads. Under transient conditions, rapid hydrate growth is achieved at 4 °C. Glass beads are modified via silanization and treated with peroxymonosulfuric acid. It is proven that the fixed-bed surface properties significantly determine the gas hydrate growth and final gas uptake and therefore determine the successful technical design of the system. The capillary pressure is calculated in each bed configuration and is set in relation to the overall gas uptake. A negative capillary pressure leads to a holdback of water in the fixed-bed system. A high water-to-hydrate conversion is obtained for an untreated fixed bed with a positive capillary pressure. In the presence of SDS, the capillary effects are negated by the kinetic promotion effects. An inhibiting behavior is observed when using hydrophilic beads after treatment with peroxymonosulfuric acid.

This work deals with the influences of surface‐active coatings made by silanization with an increasing hydrophobicity on methane hydrate formation in view of induction times, gas uptake, and rate of gas consumption. Hydrate formation was performed in a stirred pressure autoclave under stationary and transient conditions in presence of different coatings made from diverse silanes. With increasing carbon chain length of the silanes, promoting effects were observed while using stationary formation conditions.

Clathrates of natural gases, also called “gas hydrates”, are ice-like solids made up of water and gas molecules. They have become increasingly interesting in science and industry in the last decades, because of their potential as an energetic resource as well as because of their ability to block and damage pipelines (so-called “plugging”) under certain conditions. The mechanism of hydrate formation, however, is not fully explored yet, especially regarding the formation in the presence of substances other than gas and water molecules. Therefore, in this paper, the influence of substances with OH-molecular groups on methane hydrate formation has been thoroughly investigated in high-pressure experiments.

Gas hydrates show great potential with regard to various technical applications, such as gas conditioning, separation and storage. Hence, there has been an increased interest in applied gas hydrate research worldwide in recent years. This paper describes the development of an energetically promising, highly attractive rapid gas hydrate production process that enables the instantaneous conditioning and storage of gases in the form of solid hydrates, as an alternative to costly established processes, such as, for example, cryogenic demethanization. In the first step of the investigations, three different reactor concepts for rapid hydrate formation were evaluated. It could be shown that coupled spraying with stirring provided the fastest hydrate formation and highest gas uptakes in the hydrate phase. In the second step, extensive experimental series were executed, using various different gas compositions on the example of synthetic natural gas mixtures containing methane, ethane and propane. Methane is eliminated from the gas phase and stored in gas hydrates. The experiments were conducted under moderate conditions (8 bar(g), 9–14 °C), using tetrahydrofuran as a thermodynamic promoter in a stoichiometric concentration of 5.56 mole%. High storage capacities, formation rates and separation efficiencies were achieved at moderate operation conditions supported by rough economic considerations, successfully showing the feasibility of this innovative concept. An adapted McCabe-Thiele diagram was created to approximately determine the necessary theoretical separation stage numbers for high purity gas separation requirements.

This study provides the influence of different heat exchanger internals (helical pipe coils, heating plugs, pipe registers) and reactor bottom shapes (torispherical/dished (Kloepper-shape), hemispherical, and flat) on the flow field, the turbulent kinetic energy, and the ratio of tangential flow in stirred vessels, based on extensive stereo PIV measurement series in refractive index-matched, optically completely accessible systems. The investigations impressively show advantages and disadvantages of the various equipment, which have a massive influence on both heat transport and the flow.

No abstract

Suspending particles in liquids is an important and versatile case for industrial stirring processes. By using advanced optical, non‐invasive measurement techniques like particle image velocimetry (PIV), it is possible to gain deep insights into the involved fluid dynamics without affecting the flow. However, for suspensions, the application of PIV is not trivial since both, suspended and tracer particles are present and need to be discerned during experiments. The here presented method development solves this problem and thus leads to a better insight into turbulent kinetic energy distribution, which can be utilized for process optimization through improved stirred vessel design.

Hydrates of natural gases like methane have become subjects of great interest, mainly because of their potential as an energetic resource. Another important discussion topic is carbon dioxide and its function as greenhouse gas. Extracting methane from gas hydrates while simultaneously storing carbon dioxide in them (reformation) could be a promising means to solve both problems at the same time. Here, reformation of natural gas hydrates has been examined to realize technically feasible reformation processes and promising results regarding the saturation of hydrates with carbon dioxide have been achieved.