Injection of water into wells is a common practice in offshore oil and gas installations, and here as in many other industries the water has to be deaerated before it is sent through miles of pipelines to reduce the risk of corrosion in those pipelines and other downstream equipment. It requires extremely low concentrations of dissolved oxygen for the corrosion of metals to begin, and removing the dissolved oxygen is currently done in large vacuum deaeration towers, a highly energy demanding process, along with additional injection of chemical oxygen scavengers. In many instances these processes are controlled in a feed-forward manner, where the operators rely on infrequent sampling and corresponding measurements to control the process. The possibilities for optimization in this field are thus numerous. The main challenges are online measurements of dissolved oxygen and their use in feedback control. This article gives a brief review of the state-of-the-art and investigates the potential of using dissolved oxygen as a reliable feedback parameter, taking inspiration from onshore waste water industries which have been dealing with dissolved oxygen feedback control since the 1970's.
From the process control point of view, any reliable and online Oil-in-Water (OiW) measurement could provoke a brand new control paradigm for produced water treatment. However, the real-time OiW monitoring is still an open and ad-hoc situation in recent decades. The fundamental issue, ie, the OiW measurement is methodology dependent, leads to numerous challenges, such as (i) how to verify the reliability and accuracy of a specific methodology/instrument; (ii) how to handle and interpret the measured data in a most objective manner; and (iii) how to keep a cost-effective on-site calibration and maintenance under the harsh offshore conditions etc. The paper reports our latest achievements and observations in usage of fluorescence- and microscopybased OiW monitoring technologies for advanced Produced Water Treatment (PWT) control and evaluation, particularly by focusing on the de-oiling hydrocyclone installations.
Thermal energy storage, with its low energy storage cost and wide distribution in industrial processes, is an effective way to improve the operational flexibility of power plants. Due to colossal energy storage capacity and small deployment costs, this article proposes connecting district heating networks to combined cycle gas turbine (CCGT) plants as a thermal energy storage capacity, improving the flexibility of CCGTs. The main focus here is on developing an appropriate control strategy to effectively control the power-heat conversion, meet the heat and power demands of the connected network, and the operational flexibility of the plant. The major problem is that the intrinsic static and dynamic conversion relationship of power and heat in the CCGT and district heating network and the buildings are multi-factor interactive and unknown. Therefore, the CCGT bottom cycle and district heating network, and building models were built to obtain the power-heat conversion parameters and the dynamic model for control design. Then, the energy storage coefficient of 0.105 MW/kg/s is obtained through the model simulation instead of a complex thermodynamic calculation, corresponding to the 113.22 GJ energy storage capacity of the district heating network. Based on the obtained conversion rules, a new control strategy called ‘conversion coordinated control’ is designed and applied, using load signal decomposition and synergistic load response of flue gas mass flow rate and steam extraction valve. The simulation results show that the proposed method can promote a ramping load rate of 8.6 MW/min in the first 30 s with only 0.3 °C building temperature variation. The control strategy can effectively reduce the gap between the grid demand and CCGT power and ensure grid stability without compromising thermal users’ comfort.
A new power-to-X desulfurization technology has been examined. The technology uses only electricity to oxidize the hydrogen sulfide (H2S) found in biogas to elemental sulfur. The process works by using a scrubber where the biogas comes into contact with a chlorine containing liquid. This process is capable of removing close to 100% of H2S in biogas. In this paper a parameter analysis of process parameters has been carried out. In addition a long term test of the process has been performed. It has been found that the liquid flow rate has a small but notable influence on the process’ performance on removing H2S. The efficiency of the process largely depends on total amount of H2S flowing through the scrubber. As the H2S concentration increases, the amount of chlorine required for the removal process is also increased. A high amount of chlorine in the solvent may lead to unwanted side reactions.
The European Commission recently proposed requirements for the production of renewable fuels as these are required to decarbonize the hard-to-electrify parts of the industrial and heavy transport sectors. Power-to-X (P2X) energy hubs enable efficient synergies between energy infrastructures, production facilities, and storage options. In this study, we explore the optimal operation of an energy hub by leveraging the flexibility of P2X, including hydrogen, methanol, and ammonia synthesizers by analyzing potential revenue streams such as the day-ahead and ancillary services markets. We propose EnerHub2X, a mixed-integer linear program that maximizes the hub’s profit based on current market prices, considering the technical constraints of P2X, such as unit commitment and non-linear efficiencies. We investigate a representative Danish energy hub and find that without price incentives, it mainly sells renewable electricity and produces compressed hydrogen. A sufficient amount of renewable ammonia and methanol is only produced by adding a price premium of about 50% (0.16 €/kg) to the conventional fuel prices. To utilize production efficiently, on-site renewable energy sources and P2X must be carefully aligned. We show that renewable power purchase agreements can provide flexibility while complying with the rules set by the European Commission.
The question of when and how international orders change remains a pertinent issue of International Relations theory. This article develops the model of pragmatic ordering to conceptualise change. The model of pragmatic ordering synthesises recent theoretical arguments for a focus on ordering advanced in-practice theory, pragmatist philosophy, and related approaches. It also integrates evidence from recent global governance research. We propose a five-stage model. According to the model, once a new problem emerges (problematisation), informality allows for experimenting with new practices and developing new knowledge (informalisation and experimentation). Once these experimental practices become codified, and survive contestation, they increasingly settle (codification) and are spread through learning and translation processes (consolidation). We draw on the rise of the maritime security agenda as a paradigmatic case and examine developments in the Western Indian Ocean region to illustrate each of these stages. The article draws attention to the substantial reorganisation of maritime space occurring over the past decade and offers an innovative approach for the study of orders and change.
Carriers in liner shipping markets frequently make public announcements of general rate increase (GRI) intentions, based on which EU authorities have concerns as to whether this harms market competition. This paper aims to empirically investigate how well the GRI system works from an industrial competition perspective, which will indirectly indicate whether carriers are able to manipulate spot rates following GRI announcements. Taking the Far East–North Europe trade between 2009 and 2013 as an example, the paper first reveals the gradual increase of GRI frequency and size, which reflects carriers’ attempts to restore profitability against overcapacity. However, out of all the GRI events only 28.6% were observed to be successful. Since these GRI successes must be the results of either price collusion (if any) and/or normal rate change by carriers in response to fundamental market developments, the effective collusion, if it exists, is actually lower than 28.6%. Next, we identify eight factors influencing GRI successes. To further assess their impact, we applied an ordered logit regression analysis, which, based on four of the factors involved, yields good predictability for GRI success. The four factors, in sequence of explanation power, are the total capacity of GRI carriers, the idling fleet size, the spot rate level, and the average ship-loading factor. Clearly the latter three factors are market fundamentals, which are unlikely to be influenced by an individual carrier in the short term. In actual fact, the conclusion reached is that there is little evidence that carriers can manipulate and distort spot rates through GRIs.
Seafarers and fishers have inequity in health at work, with a higher risk of having metabolic syndrome. They are at increased risk of developing prediabetes, which can be reversed to normoglycemia based on the evidence from other industries. This study aims to educate and activate seafarers and fishermen with the support of coaches to reverse their prediabetes to stop the further development of diabetes type 2.
Methods
Random samples of seafarers and fishermen with newly diagnosed prediabetes and HbA1c levels ranging from 5.7%-6.4% from the maritime medical health examinations constitute the study population in a 16-week prediabetes coaching program. In addition to monthly Zoom meetings, they are asked to provide weekly reports via questionnaires on personal measurements and improvements in physical activity and diets.
Results
The preliminary data from 2 maritime clinics (n=405) show prevalences of prediabetes 18.8%, 36.4%, and 49.2% in the ages 20-29, 30-49, and 50+ years respectively, all p-values < 0.02.
Analysis of the clinical data from the maritime health clinics and the questionnaires from the seafarers collected weekly will formulate the effect of the intervention. Summarizing data from various national prediabetes coaching fora will be the evidence base for remission of prediabetes.
Conclusions
A significant portion of seafarers have prediabetes with the potential to achieve remission of their pre-diabetes by eating healthy and being physically active. The goals are to lose at least 5%–7% of their starting weight, be accustomed to doing at least 150 min. of physical activity weekly, and follow a pre-diabetes-relevant dietary plan.
Fishing and sand mining in Cambodia may not appear to have much in common. However, digging deeper reveals important parallels. Both fishing and sand mining support livelihoods and are connected to a limited natural resource. Meanwhile, they are both typified by precarious livelihoods, on the one hand, and overexploitation, on the other. In bringing these two topics together, the paper combines empirical qualitative research from two separate studies conducted by the co-authors in Cambodia, one in coastal fishing villages and another in the sand mining industry along the Mekong River. We argue that the interplay between fishing and sand mining has paradoxical impacts on livelihoods, supporting one group while undermining another. Using a precarity analysis lens, we show how an unconventional, and largely invisible frontier of natural resource exploitation—sand mining—is intertwined with fisheries, and expands our understanding of the relationship between precarious labour, environmental change, and livelihoods.
Marine flexible pipe/cables, such as umbilicals, flexible pipes and cryogenic hoses, are widely adopted in ocean engineering. The reinforcing armor layer in these pipe/cables is the main component for bearing loads, which is a typical multi-layer helically wound slender structure with different winding angles for different devices. There has been no general theoretical methodology to describe the tensile performance of these flexible pipe/cables. This paper first introduces a theory to solve the tensile mechanical behavior of a helically wound structure. Based on the curved beam theory, a solution of the tensile stress of a helically wound slender is derived. Then, the deformation mechanism of the marine flexible pipe/cables structure with different winding angles is studied. Through comparing theoretical and numerical results, the deformation characteristic of the helically wound slender structure is further explained. It is found that a sectional torsional deformation generates when the structure with a larger winding angle is under tension condition, while the sectional deformation of the structure with a smaller winding angle is mainly tension. Finally, a couple types of marine flexible pipe/cables under the tension condition are provided to analyze the mechanical performance and compare the difference between different theoretical models. The research conclusion from this paper provides a useful reference for the structural analysis and design of marine flexible pipe/cables.