• Example of the maintenance of a machine pero (D 2504-019) for cleaning metal parts in the working conditions of OEM company from the autotive industry

    pg(s) 255-258

    In this article, it will present a example of the maintenance of a machine PERO (D 2504-019) for cleaning metal parts in the working conditions of renowned OEM company in producing filters from automotive industry. The maintenance process is of particular importance in order to use production capacities to the maximum extent. Maintenance is an indispensable segment of any production system. It follows that maintenance should be adapted to these conditions, and be economical and efficient, so as not to slow down the progress of the production system. Various maintenance methods have developed alongside the development of technology, all with the aim of increasing efficiency and reducing costs. This entails the need for increasing knowledge and skills of the workers themselves in the maintenance system. Large sums of money are invested in modern industry, in order to prevent monetary losses caused by system failures. If the machine tools, devices, and accessories are not maintained on time and adequately, there will be a stoppage of production, which is extremely inconvenient for the company. When the machine stops, delivery is delayed, which leads to a psychological effect on the worker, who is then put under pressure to make up for lost time. In this article, the whole procedure of cleaning, mantenance and inspection of machine PERO (D 2504-019) through 13 steps has been studied. The indicators of the reliable operation of the analyzed machine through the analysis of the machine’s operation, the analysis of downtime, and the analysis of the occurrence of failures through the obtained values of MTTR (Mean Time to Repair) and MTBF (Mean Time Between Failures) are presented in details.

  • Design of lng tank Type C

    pg(s) 244-254

    Cylindrical tank-type c is designed for cruise passenger ships trying to adopt hull space and meet the requirements of propulsion. Tank must be a double wall with the vacuum space in between, which is also fulfilled with the perlite as insulation. The main input for the design was a tank capacity of 430 m3, vapor pressure, and available space inside of hull structure. The holding period of the boil-off gas is limited to 21 days of ship voyage. Trying to satisfy the volume capacity of the inner tank different dished end of tank was observed. The inner tank is divided into segments for the calculation of hydrodynamic pressure. According to classification rules, dnv and igc rules tank thickness, supports, stiffening and vacuum rings are determined to satisfy bending and buckling requirements. Some of the requirements were according to british standards for validation of the results. The material that is used for calculation is stainless steel 304 l. The main goal of this paper is to provide the optimal design of the lng tank type c considering the mass of the whole lng tank, with attendance to reduce the steel mass of the structure by optimizing shell thicknesses and the number of vacuum rings. After analytical calculations are made finite element analysis is used for verification of the given results. According to the given results space for improvements of tank-type c was observed.

  • Methods of Identifying Air Leaks in Pneumatically Operated Equipment in the Industry

    pg(s) 207-211

    In recent decades, it has become commonplace to automate assembly operations, often linked to production technologies within a single flexible production and assembly system. Assembly has a significant impact on global production, both in terms of its share of the total production cost of assembled products and in terms of the number of people employed in this area. The challenge for scientific and technical intelligence is to rapidly acquire production and assembly know-how to achieve target parameters in the shortest possible time. The use of all machinery and equipment forces people to think about how to use energy in the most efficient way, with the least possible loss, either in terms of money or in terms of energy. Every year the cost of energy increases, whether due to depletion of supplies or climate changes.
    Compressed air leaks are a serious problem in many industrial and manufacturing environments. These leaks not only increase operating costs but can also have a negative impact on the environment and the health of workers. Compressed air is the most expensive medium and when all basic costs are included, compressed air is many times more expensive than the equivalent of electricity. Therefore, it is necessary to analyse how to prevent high losses in the industry.

  • Improvement of the design of the string extrusion machine based on the modernization of the worm

    pg(s) 171-173

    An option to modernize the worm of the strand extrusion machine is proposed. The technical solution of this worm of the string extrusion machine is the improvement of the mixing section of the extruder worm, which is located in the gap of the screw line in the homogenization zone of the extruder. This design of the mixing section of the worm of the strand extrusion machine allows to intensify the process of dispersion of agglomerates and mixing of the dispersed phase in the dispersed medium and as a result to obtain a homogeneous structure of the polymer, which in turn allows to improve the quality of the final product.

  • Experimental setup for studying the behavior of sheet blanks during cyclic alternating bending for roller levelling application

    pg(s) 139-140

    Roller levelling is a technological process of metal forming, used to minimize the flatness of sheet blanks and reduce the level of residual stresses. When levelling, the workpiece is subjected to cyclic alternating bending with decreasing amplitude. The report presents an experimental testing set-up designed and used to determine the mechanical response of sheet steel blanks under different loading modes. The equipment is described and the first results are presented.

  • Analysis of the influence of internal forces and moments on the nozzle of the main downcomer of a steam boiler drum

    pg(s) 135-138

    The present work deals with the analysis of the influence of internal forces and moments on the nozzle of the main boiler of a steam boiler used in the waste incineration industry. The analysis is carried out analytically by performing calculations using standards, and later numerically using finite element method software. As results of the analyses, equivalent von Mises stresses, displacements and buckling eigenvalues are obtained and compared with analytical solutions.

  • Dynamic stability of a fluid-immersed, cracked pipe conveying fluid and resting on a Winkler elastic foundation

    pg(s) 102-104

    The dynamic stability of a cracked pipeline resting on a Winkler elastic foundation and immersed in fluid that is moving with a particular velocity is investigated. The Galerkin method is employed to approach numerically the problem. Conclusions are drawn on the influence of the rigidity of the Winkler elastic foundation on the critical flow velocity of the pipe.

  • Exergy analysis of steam turbine from ultra-supercritical power plant

    pg(s) 98-101

    In this paper is presented an exergy analysis of steam turbine (along with analysis of each cylinder and cylinder part) from ultrasupercritical power plant. Observation of all the cylinders shows that IPC (Intermediate Pressure Cylinder) is the dominant mechanical power producer (it produces mechanical power equal to 394.44 MW), it has the lowest exergy loss and simultaneously the highest exergy efficiency (equal to 95.84%). HPC (High Pressure Cylinder) has a very high exergy efficiency equal to 92.37% what confirms that ultrasupercritical steam process is very beneficial for the HPC (and whole steam turbine) operation. LPC (Low Pressure Cylinder) is a dissymmetrical dual flow cylinder, so both of its parts (left and right part) did not produce the same mechanical power, did not have the same exergy loss, but their exergy efficiency is very similar and in a range of entire LPC exergy efficiency (around 82.5%). Whole observed steam turbine produces mechanical power equal to 928.03 MW, has exergy loss equal to 93.45 MW and has exergy efficiency equal to 90.85%. The exergy efficiency of the whole analyzed steam turbine is much higher in comparison to other steam turbines from various conventional power plants.

  • Design and CFD simulation of the exhaust manifold of the Formula Student vehicle

    pg(s) 54-57

    One of the biggest challenges in the FSAE competition is adapting the power unit to the strict regulations of the competition. The task of the exhaust manifold is to enable the best possible flow of exhaust gases from the engine to the environment. A properly designed vehicle exhaust manifold is of great importance for enabling better performance of the power unit. There are several different concepts for designing exhaust manifolds. Each concept has its advantages and disadvantages. One of the main guidelines when designing the exhaust manifold is to enable air flow with as little local resistance as possible so that the exhaust gases are released into the environment as soon as possible. In this work, a 3D model of three types of exhaust manifolds was created, and then a CFD simulation of airflow through exhaust manifolds was performed using ANSYS Fluent software. CFD simulations help to a great extent with a better design of the exhaust manifold.

  • Visualization and analysis of worm gear drives efficiency and load capacity

    pg(s) 50-53

    Scientific methodologies have been created and applied during the analysis upon worm gear drives. Important parameters have been selected in order to make significant investigations in the area of worm gear efficiency and load capacity. The efficiency coefficient and maximal torque values have been studied for several combinations of modules, ratios, center distances, etc. The results have been presented and analysed through three-dimensional graphics. Conclusions are made.

  • Improving wellbore stability by applying drilling mud with Fe2O3 nanoparticles

    pg(s) 14-17

    Since 90% of all problems related to the wellbore instability occur during drilling through shales, which are mostly consisted of clay minerals, the filtrate from drilling mud penetrate into shale rocks and lead to their destabilization, so the industry is considering the possible application of new types of additives because conventional additives, due to their size, cannot enter in pores of shales, plug them and reduce further filtrate penetration. The oil industry in last few years turns to investigate possible application of nanoparticles because they can enter in small shale pores and plug them, thus increasing the wellbore stability. In this paper the influence of the size (50 nm and between 20 and 30 nm) and concentration (0.5, 1, 3 and 5 wt%) of Fe2O3 nanoparticles on density, rheology, API filtration, and swelling of laboratory prepared pellets in contact with mud without and with nanoparticles was determined. Due to the fact that the rheological properties are significantly increased at higher concentrations, and that smaller particles give better results with an emphasis on increasing the wellbore stability further tests should be carried out with nanoparticles Fe2O3 which size is between 20 and 30 nm in maximum concentration of 1 wt%.

  • The prospects for the use of liquefied gas in maritime transport

    pg(s) 12-13

    If a fuel mixture consisting of a liquefied gas fuel is prepared in the water transport diesel engines, i.e. the gas-diesel process occurs, where methanol is used as an explosive fuel, resulting in the reduction of the self-ignition delay period and fuel combustion duration, the limits of the working mixture combustion are expanded (hybrid combustion), and the mixture formation process is improved, resulting in an increase in the combustion speed, i.e., the complete combustion of the fuel mixture occurs during the active combustion period, and the cycle in the engine is closer to the Otto cycle, which improves the environmental and efficient indicators of diesel engine compared to the gas-diesel engine, where the diesel fuel is used as an explosive fuel.