Actual Condition Of Equipment Research Articles

Ensuring Energy Efficiency of Thermal Power Plants and Heating Networks by Means of Digital Transformation

The article deals with the issue of state-of-the-art development of the energy industry enterprises of the Russian Federation with the introduction of innovative digital technologies. The relevance of the research on the chosen problem is due to the transformational processes in the energy industry, that occur under the influence of digital economy introduction and the development of digital technologies. A study of the current situation and features of domestic energy industry has been carried out to identify the main factors of low efficiency that encourage energy companies to digital transformation. One of the key directions of improving the production activities of energy sector enterprises of the Russian Federation for the development of energy efficiency management system due to digitalization processes is considered. Practical examples of the creation, implementation and development of digital technologies at existing thermal power plants and thermal networks aimed at reducing the energy intensity of electric and thermal energy production, the transition from a system of scheduled preventive repairs to repairs according to the actual condition of equipment: digital counterparts of thermal power plants, digital nodes of thermal networks, predictive analytics systems and remote monitoring. The purpose, functionality, principles and models of work, the effects obtained from the introduction of digital systems, promising directions for the development of digital technologies are considered. A comparative analysis was carried out to identify the advantages and disadvantages of foreign and domestic systems of digital doubles and predictive analytics developed under the sanctions of unfriendly countries. The key barriers hindering and constraining the processes of full-scale digital transformation of energy industry enterprises are presented. The necessary conditions and motivating factors of state support of domestic business for the successful implementation and development of digital technologies have been established.

Improved internal model control method for carbon content of argon–oxygen refining ferrochromium alloys

We propose an improved internal model control method for the carbon content in the production process of argon–oxygen refining ferrochromium alloys. In the actual process, the control output is restricted and cannot fully demonstrate the control effect. Therefore, by decomposing the traditional internal model controller, we achieved saturation compensation, overcoming this limitation. In addition, by referring to the current production process, the smelting stages with different carbon-content ranges were determined. Combined with the actual equipment conditions, an anti-saturation internal model controller structure and a controller saturation numerical expert system were constructed, forming a fully improved internal model control system. The proposed method fully utilizes the steady-state error-free characteristic of the internal model control, achieving the preset control goal and significantly shortening the smelting time and improving the smelting efficiency.

High-efficiency separation and analysis of monosaccharides in Pueraria polysaccharides by pressurized capillary electrochromatography

Pueraria polysaccharides have been proven to possess biological activities such as bacteriostasis, anti-oxidative, anti-tumor, and immunity boosting activities. The variation in the structure, composition, and amount of monosaccharides in these polysaccharides may lead to different spatial structures and biological activities. Therefore, extraction of Pueraria polysaccharides and determination of the monosaccharide composition are of great significance for activity analysis and quality control. Direct detection of saccharides is difficult because they are strongly polar and do not show absorption in the ultraviolet region. At present, the commonly used methods for saccharide detection are liquid chromatography-ultraviolet detection, gas chromatography-ultraviolet detection, and mass spectrometry. Pressurized capillary electrochromatography is a high-efficiency microseparation technology. In this study, two kinds of Pueraria polysaccharides were extracted by an ultrasonic-assisted method, and response surface methodology was performed to explore the conditions for ultrasonic-assisted extraction of polysaccharides from Pueraria. The interaction effects of four factors, the liquid-solid ratio, ultrasonic extraction time, ultrasonic extraction temperature, and ultrasonic power, on the extraction rate of the polysaccharides were analyzed. By combining the optimal conditions predicted by the software and the actual equipment conditions, the optimal extraction conditions for Pueraria polysaccharides were chosen as follows:ultrasonic extraction temperature, 90℃; liquid-solid ratio of Pueraria thomsonii Benth, 20 mL/g; liquid-solid ratio of Pueraria lobata Ohwi, 40 mL/g; ultrasonic extraction time, 30 min; ultrasonic power, 180 W. Through data fitting, the multiple quadratic regression equation of the four factors on the extraction rate of Pueraria polysaccharides was established. A novel method based on pressurized capillary electrochromatography for the separation and analysis of eight neutral monosaccharides has been established. The monosaccharides were derivatized by the 1-phenyl-3-methyl-5-pyrazolone pre-column derivatization method. The separation conditions for these monosaccharides were explored, and the buffer concentration, buffer pH, applied voltage, type of chromatographic column, and mobile phase ratio were optimized. Finally, the established pressurized capillary electrochromatography-ultraviolet detection method was applied to the detection and identification of two kinds of actual Pueraria polysaccharide samples. The results of response surface analysis showed that among the four experimental factors, ultrasonic extraction temperature had the greatest influence on the extraction rate of polysaccharides from the two kinds of Pueraria, followed by the liquid-solid ratio; the influence of the ultrasonic extraction time and ultrasonic power was relatively weak. The experimental conditions were determined as follows:the separation of eight neutral monosaccharide derivatives could be realized within 24 min on a Halo-2.7 μm core-shell C18 capillary column with acetonitrile-50 mmol/L ammonium acetate aqueous solution (18:82, v/v, pH 4.1) as the mobile phase, by detection at 250 nm under an applied voltage of-20 kV. The separation and detection speeds and the column efficiency achieved with this method were much better than those obtained with the traditional liquid chromatography method. The results show that the proposed method has a good linear relationship and good repeatability. The separation and identification results for the actual samples showed that the polysaccharides of Pueraria thomsonii Benth were mainly composed of glucose, mannose, rhamnose, and fucose in the molar ratio 1.00:0.16:0.14:0.07. The polysaccharides of Pueraria lobata Ohwi were mainly composed of glucose and mannose in the molar ratio 1.00:0.70. This study provides a novel method for the rapid and efficient separation and detection of neutral monosaccharides, and serves as a reference for analyzing the monosaccharide composition of Pueraria polysaccharides.

Integrated maintenance and operations decision making with imperfect degradation state observations

In highly flexible and integrated manufacturing systems, such as semiconductor fabs, strong interactions between the equipment condition, operations executed on the various machines and the outgoing product quality necessitate integrated decision making in the domains of maintenance scheduling and production operations. Furthermore, in highly complex manufacturing equipment, the underlying condition is not directly observable and can only be inferred probabilistically from the available sensor readings. In order to deal with interactions between maintenance and production operations in Flexible Manufacturing Systems (FMSs) in which equipment conditions are not perfectly observable, we propose in this paper a decision-making method based on a Partially Observable Markov Decision Processes (POMDP's), yielding an integrated policy in the realms of maintenance scheduling and production sequencing. Optimization was pursued using a metaheuristic method that used the results of discrete-event simulations of the underlying manufacturing system. The new approach is demonstrated in simulations of a generic semiconductor manufacturing cluster tool. The results showed that, regardless of uncertainties in the knowledge of actual equipment conditions, jointly making maintenance and production sequencing decisions consistently outperforms the current practice of making these decisions separately.

A Fuzzy Logic-Possibilistic Methodology to Analyze the Main Corrosion Damages Mechanisms in Pipes and Equipment Installed in an Oil and Gas Platform

Industrial accidents in recent years, particularly in the 1980s, have contributed significantly to the attention of government authorities, industry and society as a whole, in order to seek mechanisms to prevent such episodes that compromise safety of people and the quality of the environment. Currently one of the most discussed topics in various industries is process safety. Not all hazards and risks are the same or can have the same consequences. Process hazards and risks can cause major accidents, involving the release of potentially hazardous materials, fires, and explosions, or both. Accident studies have shown that equipment malfunctions are one of the major causes of unexpected and undesirable events, and so the inspection has been a technique to examine the actual condition of equipment exposed to corrosion damage mechanisms. One of the outputs from the inspection process is the observation of which damage mechanism is acting more intensely on the equipment or the piping. Having this information can help in forecasting the corrosion rates, which consequently assists in the design of a better inspection and maintenance plan. This work presents a methodology based on the Fuzzy logic, to analyze which are the corrosion damages mechanisms that contribute most to the deterioration of the equipment and pipes in an oil platform.

Retrofitting Steam Turbines with Expired Service Life

Many pieces of equipment installed at thermal power stations (TPS) have an expired service life or are close to expiry and are obsolete. In addition, the structure of heat consumption by end users has changed. Among the ways for solving the problem of aging equipment is the retrofitting of turbines that allows for service life recovery and improvement of their performance to the modern level. The service life is recovered through replacement of high-temperature assemblies and parts of a turbine, and the performance is improved by retrofitting and major overhaul of low-temperature assemblies. Implementation of modern engineering solutions and numerical methods in designing upgraded flow paths of steam turbines considerably improves the turbine effectiveness. New flow paths include sabre-like guide vanes, integrally-machined shrouds, and effective honeycomb or axial-radial seals. The flow paths are designed using optimization and hydraulic simulation methods as well as approaches for improving the performance on the turbine blading and internal steam flow paths. Retrofitting of turbines should be performed to meet the customers' needs. The feasibility of implementation of one or another alternative must be determined on a case-by-case basis depending on the turbine conditions, the availability of reserves for generating live steam and supplying circulation water, and the demands and capacities for generation and delivery of power and heat. The main principle of retrofitting is to retain the foundation and the auxiliary and heat-exchange equipment that is fit for further operation. With the example of PT-60-130 and T-100-130, the experience is presented of a comprehensive approach to retrofitting considering the customer’s current needs and the actual equipment conditions. Due to the use of modern engineering solutions and procedures, retrofitting yields updating and upgrading of the turbine at a relatively low cost.

Evaluation of breakdown characteristics of gas insulated switchgears for non-standard lightning impulse waveforms under diverse conditions

To lower the lightning impulse withstand voltage of gas insulated switchgear (GIS) while maintaining the high reliability of its insulation performance, it is important to define in an organized way the insulation characteristics for non-standard lightning impulse voltage waveforms that represent actual surge waveforms in the field and compare them with the characteristics for the standard lightning impulse waveform quantitatively. In the preceding researches, the dielectric breakdown voltage-time characteristics were measured under several different conditions on the quasi-uniform SF6 gas gap and partly the cone-shaped insulating spacers that represent an insulation element of GIS for six kinds of non-standard lightning impulse waveforms associated with lightning surges and disconnector switching surges. As a result, in the tested range, the dielectric breakdown values for non-standard lightning impulse waveforms were higher than those for the standard lightning impulse waveform by 3% to 36%. In these experiments, parameters other than waveforms were fixed to standard conditions. In this paper insulation characteristics on quasi-uniform SF6 gas gaps were examined while changing conditions on gas pressures, gap lengths, electrode surface roughness, voltage polarities, and bias voltages. As a result, it was confirmed that the results under standard experimental conditions in the preceding experiments can be applied widely to the GIS actual equipment conditions.

Fundamental insulation characteristic of high-pressure CO/sub 2/ gas under actual equipment conditions

SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas has been widely used in electrical power equipment such as circuit breakers and transformers due to its superior insulation and interruption characteristics. However since 1997, SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas has been designated a greenhouse gas subject to emission restrictions at COP3 (The 3rd session of the Conference Of the Parties to the United Nations Framework Convention on Climate Change) so a new insulating gas is needed as a substitute for SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas. This research considers the use of high-pressure CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas as an insulator while stressing the environment aspects. Fundamental insulation data for the insulating gas acquired supposing gas insulated switchgears (GIS) consists of; (1) insulation breakdown characteristics under clean conditions and, (2) insulation breakdown characteristics with metallic particle contamination. The parameters in this case were assumed from an actual apparatus viewpoint, to be a high gas pressure up to 2.0 MPa, an electrode size capable of determining the surface area effect, the electrode surface roughness, and metallic particle length, etc. at the base electrode of the 72 kV GIS. As a result, experiments using these parameters revealed insulation characteristics for high-pressure CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas and that negative lightning impulse decided the insulation design, as well as the present SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> GIS. The need for taking measures to suppress PD under AC voltage and also the need for restricting metallic foreign particles around the central conductor and insulating spacer were recognized

Problems of reliability of mechanical equipment of hydraulic structures

1. When creating mechanical equipment of hydraulic structures it is necessary to take into account not only the one-time expenditures on its creation and assembly but also its operational reliability, maintainability, annual costs for upkeep and repair of equipment, labor efficiency, and working conditions of the operating personnel. 2. One of the ways to increase the reliability of mechanical equipment is to develop standard criteria of its condition, such as longevity, technical life, no-failure operation, maintainability, keeping qualities, etc., which permit a confident determination of the actual reliability indices and prediction of its operational capability. 3. For developing the said criteria, determining numerical reliability indices of operating equipment, and determining the regularities of the change of these indices with time or as a function of the actual cumulative operating time of the equipment, it is necessary to generalize the available and collect missing data on the actual condition of mechanical equipment, its operation, and repair. 4. To increase the quality of evaluating the technical condition of mechanical equipment it is necessary to develop on the basis of technical diagnostic principles a method of evaluating the actual condition of equipment (with an indication of the composition of inspected elements for various types of equipment, criteria of their evident and indirect diagnosis, etc.) and instructions on predicting its further operational capability. 5. It is necessary to create portable diagnostic and monitoring and measuring equipment for conducting inspections in a volume sufficient for an objective evaluation of the condition and for predicting the actual reliability indices of mechanical equipment.