Rapid Gas Hydrate Formation—Evaluation of Three Reactor Concepts and Feasibility Study

Abstract

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.

Intensification of Gas Hydrate Formation Processes by Renewal of Interfacial Area between Phases

“…Mixing and bubbling are traditionally used as mechanical initiation of GH synthesis processes [46][47][48][49][50][51][52][53][54][55]. The use of mechanical mixing improves gas-liquid contact since mixing contributes to the renewal of the gas-liquid interface to improve hydrate formation.…”

Controlled Production of Natural Gas Hydrates in an Experimental Device with an Internal Circulation Circuit

“…In the combination of injection and mixing is evaluated as the most suitable of the three different technical methods of hydrate formation and this is due to the largest gas intake into the hydrate structures. Measurements clearly show that injection led to immediate nucleation of the hydrates and additional mixing disturbed the surface tension of the mixture, which also strongly promoted hydrate formation [25].…”

Screening of metal‐organic frameworks for carbon capture based on life‐cycle assessment

“…It can be cal-culated using a force balance. For the calculation of the drag force, there are several semi-empiric correlations [1]. These correlations depend on the Reynolds number as well as on the viscosity ratio of the two liquid phases, and are based on experiments performed at room temperature.…”

“…Eng Spiral jet mills are used for fine and colloid grinding when particle sizes of < 10 μm are required [1]. The comminution performance depends on the velocity and the total size of the nozzle jets that are mainly determined by the grinding nozzle type and shape.…”

“…1) ETH Zu ¨rich, Department of Mechanical and Process Engineering, Tannenstrasse 3, 8092 Zu ¨rich, Switzerland…”