Study on the Influence of Rotational Speed and Pad Temperature of Pumped-Storage Set on Oil Mist Leakage of Thrust Bearing

The accumulation of oil mist in the thrust bearings compromises the safety of the unit and prompts financial and environmental losses. To discuss the strategies for limiting its impact, the model uses the VOF approach to calculate the air-oil-oil mist three-phase flow, combined with the Lee model, to solve the evaporation and mass transfer process between the oil and oil mist. Our attention is drawn into the influence of unit speed and pad temperature, on the occurrence of external and internal leaks from the oil tank. A comparison of cases is made with five unit speeds (100 to 500 rpm) at constant temperature (60°C), and with one unit speed (500 rpm) at different temperatures (56°C,60°C,62°C). With constant speed, the rise of pad temperature promotes the evaporation of the lubricating oil in an uneven manner, augmenting the occurrence of oil leaks. From findings, the increase of speed reduces the pressure change rate at the wall of the inner tank (external oil leaks) by 5.95 %, and of the oil slinger (internal leaks), by 44.64%. The present results might help to suggest courses of action to reduce the oil mist leakage.

Analysis on the escape phenomenon of oil mist from turbine lower guide bearing based on VOF model

To analyze the cause and mechanism of oil mist escaping from the lower guide bearing during the operation of a turbine, the oil-gas mixture in the lower guide bearing was numerically simulated by using the VOF two-phase flow model and the SST turbulence model. The influences of different sealing clearances and speeds on the flow field and the oil-gas distribution in the oil tank were studied, and the escaping characteristics of oil mist were analyzed. The results show that increasing the clearance of the labyrinth seal will reduce the pressure difference between the inside and outside of the oil tank and reduce the driving force for the escape of the oil mist. However, increasing the clearance will increase the turbulence of the flow field, the number and volume of bubbles in the lubricating oil, which will lead to the uneven distribution of oil and gas and reduce the motion stability of the lower guide bearing. The change of speed will affect the normal use of the shaft-collar pump. High speed will aggravate the generation of bubbles in the oil tank and increase the possibility of cavitation in the lower guide bearing structure. In engineering practices, it is necessary to comprehensively consider factors such as oil mist escape phenomenon, economic benefits, process manufacturing and assembly, and adopt the lower guide bearing structure with a suitable labyrinth seal clearance.

Needleless electrospun mats based on polyamidoamine dendritic polymers for encapsulation of essential oils in personal respiratory equipment

The ever-increasing concern of air pollution triggered by broad-spreading contagious disease, bioterrorism, and release of dust particles in the air is targeted to be addressed in this paper by developing a novel personal respiratory equipment (PRE). For this purpose, polyamidoamine dendritic polymers (PAMAMs) were utilized not only for encapsulating tea tree essential oil (TEO), an antimicrobial material, but also for battling against perilous bioaerosols. Furthermore, TEO is encapsulated inside both PAMAM and polyacrylonitrile (PAN) electrospun nanofibers. Results clarified that electrospun samples containing both TEO and PAMAM possess thinner nanofibers with 440 nm reduction in their average diameter, and pursuantly higher filtration efficiency against both NaCl and paraffin oil mist particles about 98% and well above 99%, respectively. Herein, the electrospinning method is employed first for high porosity, enhanced surface area to volume ratio, and interconnected pores of resulted nanofibers, which are strongly useful in capturing the dust and allowing more air to flow and pass through, and creating a good air circulation. Second, the synergistic effect of using both electrospinning and PAMAM as the host molecules is also a promising approach for addressing the volatility of fragrances by producing a controlled release of TEO.

Identification of Deposited Oil Structures on Thin Porous Oil Mist Filter Media Applying µ-CT Imaging Technique

The identification of microscale oil structures formed from deposited oil droplets on the filter front face of a coalescence filter medium is essential to understand the initial state of the coalescence filtration process. Using µ-CT imaging and a deep learning tool for segmentation, this work presents a novel approach to visualize and identify deposited oil structures as oil droplets on fibers or oil sails between adjacent fibers of different sizes, shapes and orientations. Furthermore, the local and global porosity, saturation and fiber ratios of different fiber material of the oleophilic filter medium was compared and evaluated. Especially the local and global porosity of the filter material showed great accordance. Local and global saturation as well as the fiber ratios on local and global scale had noticeable differences which can mainly be attributed to the small field of view of the µ-CT scan (350 µm on 250 µm) or the minimal resolution of approximately 1 µm. Finally, fiber diameters of the investigated filter material were analyzed, showing a good agreement with the manufacturer’s specifications. The analytical approach to visualize and analyze the deposited oil structures was the main emphasis of this work.

Influence of the air pressure and oil amount to the temperature of the high-speed bearings lubricated by oil mist

Purpose The purpose of this paper is to improve the lubrication and remove as much as possible of the heat generated in the bearing assembly, embedded in the jet engine. Design/methodology/approach To determine the necessary values of the air pressure and oil amount, an experimental approach is used. For that purpose, a custom made test rig is developed. Findings Less amount of oil makes better lubrication conditions, reflected in the smaller temperature of the bearings. Concerning the air pressure, too high and too low air pressure deteriorates the lubrication parameters. An optimum value should be determined experimentally. The influence of oil amount is remarkably bigger than the influence of air pressure. Originality/value This experimental investigation provides an easy and fast way to improve the high-speed bearings lubrication parameters.

Are There Potentially Significant Long-Term Health Consequences of Exposure to Fine Airborne Particulate Matter PM10 to Personnel on the United Kingdom's Offshore Drilling Rigs?

Drilling mud is a slurry comprising oil, water, and chemical additives. Mud is critical to drilling a modern well as it is circulated down a wellbore to remove rock cuttings and to power the drill bit. A significant volume of this drilling mud is used and later recirculated. The drilling mud warms at depth, creating steam, which holds suspended PM and dissolved chemicals. Many of the pieces of equipment are open or only partially enclosed, allowing for steam generation, while other processes generate aerosolised sprays. There is a significant potential for petroleum workers to become exposed and potentially suffer health effects because of drilling mud exposure. This study aims to find the major sources of PM10 on petroleum wells and quantify the levels of exposure and health hazard associated with drilling mud on petroleum rigs. A literature search was performed, which included all available materials which contained static or mobile concentrations of PM10 or oil mist within the UK or international petroleum drilling sites with a preference for North Sea operations. The study predicts the total PM10 by estimating the combined impact of both solid PM and oil mist. Using this conversion, it is also possible to estimate PM10 concentrations when using water-based muds. The work designates and discusses the expected health ramifications of excess exposure. A quantitative assessment of the risk of silicosis 15 years post-exposure is also calculated, predicting dire consequences to petroleum personnel in the long term. The exposure assessment methods, hygienic standards, and preventive measures are also addressed briefly.