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In the upstream sector of the modern offshore industry, mainly packed columns are used for gas purification purposes, such as the removal of CO2, SOx, NOx, and other impurities. Offshore conditions are known for their harsh environment conditions that pose extra challenges for stable process operations and can lead to inefficient separation. To make use of the newly explored offshore energy resources, floating vessels, namely, Floating Production Storage and Offloading (FPSO) units, are currently gaining dominance due to their technological and economic advantages over conventional offshore platforms. These floating vessels with their unique design can be operated in deeper locations by means of advanced technologies, i.e. mooring system and remote control mechanisms. Despite aforementioned facts, the impact of sea states and strong winds on the floating production systems cannot be fully suppressed, and these conditions affect the performance of onboard packed columns. To have a highly efficient separation process, the interfacial mass transfer area between the gas and liquid phases in packed columns must be sufficiently large, and for this reason, a uniform distribution of the phases in characteristic packing channels is required. However, realizing uniform flow distribution in the packings becomes more difficult during ship motions. When considering the geometric arrangement of column internals, structured packings are likely to have relatively better performance than random packings under these circumstances. Nevertheless, it is still unclear to what extent the flow distribution deviates from its ideal pathway under motion conditions and how this deviation degrades the separation performance. In this study, most predominant sea conditions are considered to experimentally analyze the effect of ship motions on the mass transfer efficiency of packed columns. Therefore, air dehumidification with triethylene glycol (TEG) desiccant is chosen as an example of an absorp

Charakterisierung des Einflusses neigungsinduzierter Strömungsformen mit dem Ansatz der hydrodynamsichen Analogie

In this work, an approach is proposed to study the influence of floating conditions on the fluid flow behavior of separation columns. A structured packing (Mellapak 250Y) air dehumidifier was embarked on a hexapod ship motion emulator with six-degree-of-freedom motions to mimic swell. A novel flow imaging sensor has been developed to visualize the flow morphology dynamics of triethylene glycol evolving on the corrugated sheets of packings. Furthermore, a numerical model was developed based on the hydrodynamic analogy concept to evaluate the separation performance using experimentally observed flow patterns. In our contribution, we describe the flow imaging sensor design as well as the impact of tilt on efficiency losses in comparison with the conventional upright stationary column.

Environmental and economic constraints for oil and gas production necessitate the development of cost-effective operating facilities in the modern offshore industry. For this reason, floating production systems are increasingly used to operate oil and gas fields in deepwater locations, whereby high submarine pipeline expenditures of fixed offshore platforms are eliminated. Apart from economic advantages, floating production systems maintain a safe operation and continuous production under severe ocean conditions, i.e. cyclones, huge waves and floating icebergs. Whilst traditional fossil energy sources are continuously losing their dominance, liquefied natural gas (LNG) is gaining popularity in the energy market owing to the comparatively lower greenhouse gas emissions. For LNG production, Floating Production Storage and Offloading (FPSO) units combine the feature of onshore LNG plants and that of storage tankers in a single large marine vessel. Thus, the number of FPSOs for LNG production has been growing in the offshore industry. The design principles for land-based process units cannot be directly applied to FPSO topside equipment because of wind-generated wave effects. Separation columns are more susceptible to the motion impact than most of the onboard process equipment, and consequent product quality losses represent the main concern. Separation columns with structured packings are mostly used on floating platforms due to their low pressure drop, high capacity and performance. To study the dynamics of the flow morphology in the packing and the corresponding mass transfer performance, a structured packing column is embarked on a hexapod motion simulator, which mimics the six-degree-of-freedom ship motion (cf. Fig. 1). The process of air dehumidification by triethylene glycol (TEG) solutions is used as an example. A novel flow imaging sensor was developed to visualize the flow morphology dynamics evolving on the corrugated sheets of the structured packing (Fig. 2

Modellierung des Stofftransportes in einer geneigten Kolonne mit dem Ansatz der hydrodynamischen Analogien