Influence of different stirring setups on mass transport, gas hydrate formation, and scale transfer concepts for technical gas hydrate applications

Abstract

AbstractThis contribution describes the influence of turbulent flow conditions in the liquid and/or gas phase and directly in the phase interface, different flow patterns (axial/radial), volume‐specific power inputs, mass‐specific energy consumptions, as well as volume‐specific mass transfer coefficients on the gas hydrate formation, derived from an experimental investigation of five different reactor setups. The results correspond to all fields of gas hydrate research, especially actually discussed technical hydrate applications, like hydrate‐based desalination, gas storage, gas separation, biogas and green hydrogen handling, carbon dioxide deposition, new phase transfer materials, and even electrical power supply. Two main objectives, first, to determine favorable hydrate forming conditions in stirred systems to provide competitive hydrate formation processes, and second, the search for a concept to enable the transfer of experimental results, for example, from a stirred reactor to a pipeline system for inhibitor research, through the targeted adjustment of similar and comparable turbulent flow conditions in different reactor setups could be achieved. So far, the targeted formation of gas hydrates has been investigated essentially from the point of view of optimizing the formation conditions with regard to pressure and temperature as well as the addition of auxiliary materials and promoters. In addition, some studies consider different reactor types and setups, for example, spray reactors or bubble columns. In many publications, stirred and cooled pressure autoclaves are described, whereby the gas and the liquid phase are brought into contact with each other by mixing to a greater or lesser extent by an agitator, then forming a solid gas hydrate phase. Often missing in previous research work is a systematic approach for determining the influence of flow conditions on gas hydrate formation. Many different influencing factors in a stirred reactor system can strongly affect the kinetics and formation of gas hydrates, for example, stirrer type, rotational frequency, stirrer and reactor geometry, and filling level. This is the starting point of the present investigation that deals with the influence of the flow conditions on the formation of gas hydrates. Tests were performed in a stirred autoclave to measure the effects of different stirrer configurations. The results obtained contribute to the explanation of the hydrate formation mechanism and can be used to optimize the targeted production of gas hydrates in technical hydrate applications. A rapid, immediate, hydrate formation is advantageous and can be achieved by suitable flow conditions in stirred reactors, which is successfully proven within this study contribution.