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The dynamic characteristics of an electromagnetic actuator used in a switching valve are influenced by self-induced effects, resulting in instability in its parameters when subjected to changes in working frequency, load, and other conditions. To quantitatively analyze the impact of variable working conditions, this study establishes an analytical expression for periodic signals through Fourier series expansion. It subsequently solves for transient current, yielding a new model for the response of the electromagnetic actuator under periodic signal excitation. Simulations and analyses are conducted to investigate the variation in action parameters of the electromagnetic actuator in the realm of compressor gas regulation when working conditions, such as rotation speed and load force, are altered. The results indicate that dynamic characteristics of the actuator change within the range of 8% to 35%, significantly affecting the gas regulation efficiency of the compressor. To mitigate this effect, a backstepping adaptive high frequency controller (BAHF) is proposed. Comparative assessments with the backstepping adaptive sliding model controller (BASM) and backstepping adaptive high gain controller (BAHG) reveal that the BAHF exhibits superior overall performance. An experimental platform is constructed to validate both the model's accuracy and the controller's effectiveness. The error between model simulations and experiments does not exceed 7.5%, confirming the accuracy of the model. The proposed BAHF reduces the fluctuation of compression and exhaust phase angles in the compressor by 21.6% and 6.6%, respectively, under variable working conditions. This reduction effectively suppresses the influence of working condition disturbances, yielding positive outcomes. [ABSTRACT FROM AUTHOR]

Faulty compressors must be timely detected to prevent excessive energy consumption, maintenance, and energy costs. Existing diagnostics models lack addressing the energy performance indicators and do not provide effective hybrid machine learning (ML) model for advanced fault diagnosis to prevent compressors from becoming energy hogs. Therefore, this study proposed a novel approach in the form of an energy-based diagnostic model for integrating energy performance indicators to detect the healthy and faulty behavior of the compressor using a hybrid ML model. The time series analysis and Isolation Forest techniques have been used to detect faulty and healthy behavior of centrifugal gas compressor. To obtain more insight and prevent false alarms the hybrid ML model was introduced. The Ridge regression was used as the meta-classifier in the suggested hybrid model, which receives the input from the base classifiers Decision Tree (DT), k-Nearest Neighbors (kNN), and Gradient Boosting (GB) to optimize the performance and accuracy of hybrid model. This study was conducted on a two-stage centrifugal compressor that compresses production gas for export powered by a gas turbine at Malaysia's PETRONAS Angsi oil and gas field. According to the findings, the energy efficiency predicted for the first stage was 84.2% for healthy behavior and 69.7% for faulty behavior, while for the second stage, it was 83.2% for healthy behavior and 68.1% for faulty behavior, indicating high energy efficiency during the healthy operation of a centrifugal compressor in comparison with faulty behavior. The slight difference between the proposed diagnostic model training, testing, and prediction performance accuracy 0.98, 0.97 and 0.99 proposes a model is efficient neither overfitting nor underfitting according to the value of co-efficient of determination (R2). The R2 values for training, testing, and prediction performance accuracy for the GB model were 0.95, 0.93, and 0.94; for kNN, 0.89, 0.87, and 0.86, and for Tree, 0.95, 0.94, and 0.93 respectively. According to the results, the proposed hybrid model performs more eloquently and efficiently than other single models DT, kNN, and GB. This study empowers operators to take critical measures to increase energy efficiency, reduce downtime, and schedule maintenance to improve the reliability of centrifugal gas compressor. [ABSTRACT FROM AUTHOR]

The current research aims at finding a new appropriate way to optimize and reduce water consumption by using various forms of pinch technology in petrochemical complexes due to high rate of water consumption. For this purpose, precise studies were conducted on ethylene plant. In this research, cracked gas compressor (CGC) system was considered to analyze energy and minimize water consumption of heat exchanger network (HEN). Initially, process of the CGC system has been simulated with Aspen HYSYS. Next, Aspen Energy Analyzer software was used to identify cooling water (CW) heat exchangers and economic analysis of HEN. Consequently, composite curves and grand composite curves and other results of HEN simulation were examined. The results of HEN simulation indicate that 91% of cooling loads provided by CW utility is the most widely used fresh water. Despite water circulation system of cooling tower (CT), the rate of water loss is high in this utility. As the design temperature is 40 °C and the minimum approach temperature (ΔTmin) is 10 °C, the new utility pinch point has been estimated 50 °C. In proposed modified case, air coolers were considered before the CW heat exchangers of the CGC system. In this way, air-cooled (AC) utility covers up cooling loads up to 50 °C in the modified unit. Then, the modified unit was compared with main unit. In the modified unit, 78% of cooling loads of the HEN have been covered by AC utility in which this action leads to 86% reduction in energy and water consumption of CW heat exchangers and CT. By reducing the rate of water loss in CT circulation systems, cost of supplying fresh water reduced to the lowest possible which leads to 34% optimization in HEN operating cost in the modified unit. Also in the CGC system, steam turbine is used for supplying power consumption of compressor used to CW steam turbine condenser. This condenser is the most commonly used equipment in terms of water consumption, so that there is 32% more than the total water consumption of the HEN. In the last part of this study, AC steam turbine condenser replaced the CW steam turbine condenser in the modified case. So in this case, the use of AC steam turbine condenser with power consumption (980 kw) leads to 98% reduction in water consumption of the steam turbine condenser. [ABSTRACT FROM AUTHOR]

Gasoline produced by hydrotreating light and heavy naphtha and reforming hydrotreated heavy naphtha, hydrogen required for both processes produced by the reforming unit as a byproduct, compression, and recycling of hydrogen required for reforming reactions provided by recycle gas compressor (centrifugal multi-stages compressor), due to the design criteria of this compressor the anti-surge system pass 18000 kg/h, of hydrogen from discharge to suction of compressor with 3" control valve, at the low flow situation during the startup of the unit to avoid the lake of gas flow and avoid overpressure in the discharge of the compressor. Anti-surge system in this compressor contains no inter-stage cooler, the suction temperature of the compressor is designed at 43℃, and the discharge of the compressor is 79℃ when the anti-surge system is involved in the process, the suction temperature of the compressor becomes 70℃, and the discharge becomes 108℃ due to the heat accumulation of recycle gas out of the anti-surge system. In an aim to solve this problem, the outlet of the anti-surge system of the compressor connected with the process heat exchanger, to cool down the hydrogen inlet to suction of the compressor to approximately 46℃ and back to the design limits, the disadvantage of this solution is the absorption of the light end associated with recycle gas posing in the process heat exchanger, which reduces the total molecular weight of recycle gas through the anti-surge system from 13.336 to 10.51 kg/kg mol at start of the run, and from 16.155 to 12.15 kg/kg mol at the end of the run. [ABSTRACT FROM AUTHOR]

Digital twin (DT) is a research topic that gained momentum in the Industry 4.0 era. The goal of DT is to create a virtual real-time intelligent system that is a typical twin of the physical system. DT provides analysis, prognosis, planning, and rapid response when needed. Digital shadow (DS) is an artifact concept of DT that provides a real-time replica of the physical system. Information in a DS is passed in one direction only, from the physical system to the virtual one. While in DT, the information goes in both directions. The definition and roles of DS and DT are overlapping. However, DS can be defined as the main component of a DT system. In this paper, DS roles are specified. Based on these roles, A DS framework architecture is proposed, and the communication system between its components. The proposed framework design is built using distributed system concepts such as event-driven architecture, microservices, and containerization. These concepts are well defined and utilized in the software engineering domain. The originality of the proposed framework is the definition of a systematic approach for designing and integrating digital models (DMs) from different vendors and domains. An experiment is designed to prove the framework's ability to shadow a physical system in real-time. Multiple DMs are implemented and deployed on the proposed DS framework. These DMs are used to shadow a natural gas compressor system. Experimental results prove the practicality of our proposed DS framework to operate in real-time. [ABSTRACT FROM AUTHOR]

The paper presents a method for calculating the thermodynamic parameters of refrigerant vapors during their compression in a scroll compressor. The method takes the properties of a refrigerant as a real gas into account, as well as the process of mixing two vapor portions inside the scroll unit when the full geometric degree of compression is reached. [ABSTRACT FROM AUTHOR]

A typical gas transmission system consists of multiple components, which are controlled to keep the system safe. A controller designed based on simple "If–Then Rules" cannot be guaranteed to be controllable or non-blocking, unless by formal verification. Formal verification is a difficult procedure, specifically in a gas transmission system. In this paper, a systematic method is proposed to construct the modular discrete-event model and to synthesize modular supervisors in a gas transmission system, in order to maintain the safety in the system. Two supervisors are synthesized in this paper: (1) the surge-avoidance supervisor, (2) the allowable discharge pressure supervisor. Both of them are synthesized for each compressor station through one trunk line. The constructed modular supervisors are non-conflicting. [ABSTRACT FROM AUTHOR]

This paper analyzes a number of events of recorded intense geomagnetically induced currents (GICs) in transformers at stations located on the Karelia–Kola power transmission line in northwestern Russia and in a magnetometer at a gas pipeline compressor station located near the city of Mäntsälä in Finland. Located in the auroral and subauroral zones, these two different GIC recording systems made it possible to trace the occurrence and dynamics of GICs from subauroral to high latitudes and compare them with the motion of the substorm westward electrojet according to data obtained by the Scandinavian network of IMAGE magnetometers. For a detailed study, two events were considered (March 15, 2012 and March 17, 2013), when intense GICs were observed in the technological networks under consideration. It is shown that the development of GICs on the meridional observation profile is consistent with the latitudinal motion of the westward electrojet and corresponded to the appearance of successive substorm intensifications. In addition, a relationship has been established between the appearance of GICs and an increase in the intensity and wave activity of a substorm, determined from the IL and Wp geomagnetic indices. [ABSTRACT FROM AUTHOR]

Probing the efficiency of Brayton cycle is of great importance to harbor maximum output from gas turbines. The efficiency of Brayton cycle largely depends on the maximum temperature of the cycle. However, maintaining a very high temperature in a gas turbine is restricted due to various metallurgical problems developed within the compressor blade surface, which result in the structural failure of gas turbine compressor. To address these problems, numerous prospective solutions are proposed among which materials' selection and preference for specific parts of a gas turbine are highly celebrated among researchers. Although many works are dedicated especially to the rotor blades of the turbine compressor, the stator blades which are integral component of the turbine compressor as they partially convert high velocity into high pressure to increase the pressure from the preceding stage and have both functional criteria and failure mechanism unlike the rotor blades—are yet to receive enough attention in terms of material research and development. On the other hand, recent advancements in the refractory properties of ultra-high-temperature ceramics make them highly potent materials to incorporate in the gas turbine and manufacturing industry. The proposed article seeks to explore this scope of material research specifically for the stator blades of gas turbine compressors through a numerically performed performance analysis. To provide better insight about future reach of the scope, the performance analysis is conducted among four different superalloys which are already established as rotor blade materials—Inconel 718, Ti–6Al–4V, Nimonic 80A, GTD 111 DS and an ultra-high temperature ceramic material—NbB2 as potential stator blade material in terms of thermal distribution, thermal stress and displacement over the blade surface. Reports showed that—NbB2 undergoes the least thermal displacement, whereas Ti–6Al–4V exhibits the least thermal stress during the operational stage. Considering the overall performance—Inconel 718 and Nimonic 80A failed as potential stator blade materials, whereas NbB2 and GTD 111 DS can only withstand the extreme condition inside the compressor with safety factor of one. The article concludes with Ti–6Al–4V as the most potent stator blade material to be incorporated into the gas turbine industry. [ABSTRACT FROM AUTHOR]

Novel methods for contingency analysis of gas transport networks are presented. They are motivated by the transition of our energy system where hydrogen plays a growing role. The novel methods are based on a specific method for topological reduction and so-called supernodes. Stationary Euler equations with advanced compressor thermodynamics and a gas law allowing for gas compositions with up to 100 % hydrogen are used. Several measures and plots support an intuitive comparison and analysis of the results. In particular, it is shown that the newly developed methods can estimate locations and magnitudes of additional capacities (injection, buffering, storage etc.) with a reasonable performance for networks of relevant composition and size. [ABSTRACT FROM AUTHOR]

As moist gas enters a reciprocating compressor in the course of the operation of the compressor, heating of the gas depends on the degree of dryness of the gas and the rate of evaporation of the liquid droplets in the gas as well as on the coefficient of thermal conductivity of the moist gas and on the coefficient of heat transfer from the walls of the compressor cylinder to the gas. However, once the rotational speed of the compressor shaft reaches 300 min–1, the length of the gas intake process falls to one-tenth the length of the period of total evaporation of the droplets, hence the process of evaporation begins to exert a practical influence on the temperature of the gas. The gas temperature increases substantially due to the increase in the thermal conductivity coefficient of the moist gas and in the coefficient of heat transfer from the walls of the compressor cylinder to the gas. With a decrease in the degree of dryness of the gas from 1.0 to 0.6, preheating of the gas grows 7–8-fold, which leads to a reduction in the density of the gas in the filled work space of the cylinder and, as a consequence, to a decrease in the adiabatic efficiency of the compressor ηi by 14–16%, and this must be taken into account in the management of the production process. [ABSTRACT FROM AUTHOR]

The simplicity and effectiveness of a recently proposed metaheuristic, butterfly optimization algorithm (BOA) have gained huge popularity among research community and are being used to solve optimization problems in various disciplines. However, the algorithm is suffering from poor exploitation ability and has a tendency to show premature convergence to local optima. On the other hand, the mutualism phase of another popular metaheuristic symbiosis organisms search (SOS) is known for its exploitation capability. In this paper, a novel hybrid algorithm, namely m-MBOA is proposed to enhance the exploitation ability of BOA with the help of mutualism phase of SOS. To evaluate the effectiveness of m-MBOA, thirty-seven (37) classical benchmark functions are considered and the performance of m-MBOA is compared with the performance of ten (10) state-of-the-art algorithms. Statistical tools have been employed to observe the efficiency of the m-MBOA qualitatively, and obtained results confirm the superiority of the proposed algorithm compared to the state-of-the-art metaheuristic algorithms. Finally, four real-life optimization problem, namely gear train design problem, gas compressor design problem, cantilever beam design problem and three-bar truss design problem are solved with the help of the newly proposed algorithm, and the results are compared with the obtained results of different popular state-of-the-art optimization techniques and found that the proposed algorithm is more efficient than the compared algorithms. [ABSTRACT FROM AUTHOR]

Propagation of a semi-elliptical crack on the suction surface of a rotating blade of a gas turbine compressor is modelled and analysed. The analytical solution for the stress intensity factor (SIF) at the deepest point of the crack shows that the SIF increases with an increase in the crack depth and rotation speed, whereas the SIF decreases with an increase in the semi-elliptical aspect ratio and crack-rotation axis distance. The SIF increase rate with increasing crack depth is found to depend on the aspect ratio. Comparisons of theoretical and numerical calculation results reveal a relative error within 4%. The SIF distribution along the semi-elliptical surface crack front at different depths, positions, and aspect ratios are obtained by a numerical method. [ABSTRACT FROM AUTHOR]

Calculation formulas for estimating the influence of the state parameters of temperature, pressure, and moisture content on the operation of a piston compressor are obtained. It is shown that at the start of compression in a compressor temperature depends mainly on heating of the gas produced by the walls and its moisture content. The pressure at the start of compression depends on the speed of the piston and the moisture content of the gas. The principal factors responsible for a reduction of the feed rate and efficiency of the compressor are the increase in temperature and the decrease in pressure at the start of compression. [ABSTRACT FROM AUTHOR]

Effective use of low-temperature exhaust heat in the direct thermodynamic cycle with water and alternative working fluids is proposed. The calculations are performed for a compressor station and a gas turbine plant and the most optimal fluid for the direct cycle is selected. [ABSTRACT FROM AUTHOR]

Nowadays, there is a great interest in using active control methods to increase the compressor working range. The advantage of this controlling method is that the performance point can be located in the vicinity of maximum pressure and efficiency. However, most of the existing controllers require an awareness of compressor characteristic, disturbance upper bound, throttle gain, and throttle valve feature; this is why they are limited in engineering applications. In order to overcome the weakness of the existing controllers, this research employs a novel combined controlling method based on robust adaptive control, which is designed using backstepping technique because the compressor behavior is nonlinear. The increased efficiency and improved operational area for the compressor are provided by this controller without requiring any knowledge or information regarding the compressor characteristic, disturbance upper bound, throttle gain, and throttle valve feature. The adaptive controller has been used to compensate for uncertainties of the compressor characteristic and throttle valve as well as the un-modeled dynamics. Also, the controller robustness is a barrier against the time-varying disturbances in flow and pressure applied to the system. Finally, simulation results showed that the designed controller, in addition to assure the system stability, developed the compressor working range, and the convergence of system states was achieved after applying disturbance in flow and pressure. [ABSTRACT FROM AUTHOR]

A procedure and proposed recommendations are developed for restoring VT8 titanium aircraft gas turbine engine compressor blades using powder surfacing with a fiber laser. A procedure is suggested for restoring defective sections and building up titanium blade vane elements on the example of alloy VT8 using powder materials PTOM-1 and VT25U. It is shown that a pulsed laser operating regime during surfacing and minimization of surfacing layer thickness reduces the time for metal in an overheated condition, which ensures a reduction in the possibility of crack and pore formation, and also formation of a coating ultrafine structure. [ABSTRACT FROM AUTHOR]

The article informs about the nuclear power plants (NPPs) Base Load Guarantors in Power Systems. Topics discussed include equipment in a compressor station with combined drive in a small-capacity air-storage power plant; combined drive of natural gas pumping units from electric motors during an off-peak period; and underground gas storage as an additional systems user-regulator.

When considering cost-optimal operation of gas transport networks, compressor stations play the most important role. Proper modeling of these stations leads to nonconvex mixed-integer nonlinear optimization problems. In this article, we give an isothermal and stationary description of compressor stations, state MINLP and GDP models for operating a single station, and discuss several continuous reformulations of the problem. The applicability and relevance of different model formulations, especially of those without discrete variables, is demonstrated by a computational study on both academic examples and real-world instances. In addition, we provide preliminary computational results for an entire network. [ABSTRACT FROM AUTHOR]

Similitude criteria of compression processes of real gases in the stages of compressors with dynamic compression are presented. A technique of compiling the thermal and caloric equations of state for gas mixtures and a technique of processing test data obtained in gaseodynamic tests are proposed. [ABSTRACT FROM AUTHOR]

We study the intense hydrogen-induced delamination in the wall of a bent branch pipe after long-term operation at the gas-compressor station of the system of gas mains. The factors playing the key role in the formation of this delamination are analyzed. It is shown that the abnormal readings of a thickness meter and a sharp decrease in the hardness and plasticity of steel are the diagnostic signs of this phenomenon. It was discovered that the degree of degradation of steel of the pipe bent is higher as compared with the straight section of the pipe regardless of their tension or compression. We establish the limitations for the use of the relative elongation and relative narrowing as characteristics of plasticity for the metal of the pipe wall with intense delamination. [ABSTRACT FROM AUTHOR]

This paper proposes a novel compensation algorithm of current offset error for single-phase linear compressor in home appliances. In a half-bridge inverter, current offset error may cause unbalanced DC-link voltage when the DC-link is comprised of two serially connected capacitors. To compensate the current measurement error, the synchronous reference frame transformation is used for detecting the measurement error. When an offset error occurs in the output current of the half-bridge inverter, the d-axis current has a ripple with frequency equal to the fundamental frequency. With the use of a proportional-resonant controller, the ripple component can be removed, and offset error can be compensated. The proposed compensation method can easily be implemented without much computation and additional hardware circuit. The validity of the proposed algorithm is verified through experimental results. [ABSTRACT FROM AUTHOR]

This paper presents a failure analysis performed to investigate the leak of heat exchanger tubes. The objectives of the investigation are to identify the failure mechanism and possible contributing factors and suggest corrective actions to prevent reoccurrence of similar failure. Thorough failure analysis showed that sulfur was obviously detected on both tube side surfaces (OD and ID). Probably, the source of this sulfur can be DMDS or the feedstock. The mechanism of the failures occurred in the heater exchanger tubes is due to external thinning that was most likely caused by combination of impact fretting and corrosion. It is recommended to ensure that the system is dry in heat exchangers shell side. Closely monitor sulfur contents in the heat exchanger stream. If possible, monitor the thickness of all tubes, especially area under/near the baffle to tube interface, during scheduled turnarounds to reduce the possibility of sudden failures. The condition of the other heat exchangers should be assessed. Ensure that the tube bundle as a whole 'tightens up' and will act as one rigid entity. Anti-Vibration Supports might be helpful to be inserted between tubes and close to the baffle plates to mitigate the vibration as a result of fluid flow. [ABSTRACT FROM AUTHOR]

An algorithm and results of analysis of gas compressor piston rod failure causing shutdown of the compressor are elucidated. It is shown that the rod failure occurred due to formation and growth of fatigue fractures in the thread roots having design incongruity. Recommendations are offered for increasing fatigue life and prevention of compressor piston rod failure. [ABSTRACT FROM AUTHOR]

It has been experimentally established that the instability in the performance properties of Tp-22 s mineral turbine oil is due to the different catalytic activities of the original base stocks used to produce the commercial oil. The catalytic activity factor shows by how many times iron (the catalyst) increases the oxidation rate of the oil. A higher catalytic activity factor for the original base stock means poorer performance properties for the commercial oil obtained from it. Introducing additives into the composition of the mineral base stock that block the catalytic effect of iron makes it possible to reduce the catalytic activity factor. [ABSTRACT FROM AUTHOR]

This study presents the results of failure analysis of a 28 MW gas turbine at the Rei electrical power plant. The gas turbine failed during the shutdown period and near its second natural frequency at 4200 rpm. Initial inspections revealed that the compressor disk of stage 15 was fractured, and all of the stationary and rotary blades of stages 14-18 of the compressor had been detached or broken from the dovetail region of the disks. The fracture roots were investigated by performing finite element modeling and fractography analysis. It was shown that a crack was initiated from the disk edge on its interface with the rotor shaft and was propagated under cyclic loading. As a result of the malfunction of the compressor bleed valves, which led to compressor surge, the amplitude of vibration of the turbine rotor increased under aerodynamically induced forces. This increase in the natural frequency of the turbine, near the second natural frequency of the turbine, led to final ductile fracture of the compressor disk of stage 15. Finally, the turbine rotor stopped with the loud noise produced by the direct shearing of the fractured disk on the stator casing. Some recommendations are proposed to prevent similar failures in the future. [ABSTRACT FROM AUTHOR]

The present article treats different phenomena taking place in a steelmaking converter through the development of two separate models. The first model describes the cavity produced at the free surface of the metal bath by the high-speed impinging oxygen jet. The model is based on a zonal approach, where gas compressibility effects are taken into account only in the high velocity jet region, while elsewhere the gas is treated as incompressible. The volume of fluid (VOF) method is employed to follow the deformation of the bath free surface. Calculations are presented for two- and three-phase systems and compared against experimental data obtained in a cold model experiment presented in the literature. The influence on the size and shape of the cavity of various parameters and models (including the jet inlet boundary conditions, the VOF advection scheme, and the turbulence model) is studied. Next, the model is used to simulate the interaction of a supersonic oxygen jet with the surface of a liquid steel bath in a pilot-scale converter. The second model concentrates on fluid flow, heat transfer, and the post-combustion reaction in the gas phase above the metal bath. The model uses the simple chemical reaction scheme approach to describe the transport of the chemical species and takes into account the consumption of oxygen by the bath and thermal radiative transfer. The model predictions are in reasonable agreement with measurements collected in a laboratory experiment and in a pilot-scale furnace. [ABSTRACT FROM AUTHOR]

We present the numerical design of a two-cascade target. The desired target design is intended to provide a shock-free compression of the central DT core, where the fusion reactions take place. We obtain the formula for the energy deposition into each cascade internal layer for both known and unknown energy depositions into the external target layer. The two-cascade target design helps to increase the energy deposition into the DT layer and therefore decrease the energy required for the target ignition. [ABSTRACT FROM AUTHOR]

This work aims to study the effectiveness of NH-SCR after-treatment systems, initially developed for a Diesel application, on Heavy duty natural gas engines working in lean conditions for exhaust gas pollutants abatement. Commercial oxidation and NH-SCR catalysts were investigated for respectively CH, CO oxidation and NO reduction. In this study, we showed that the NH-SCR coupled with an oxidation catalyst lead to significant conversion of CH, CO and NO, and can be used as after-treatment system for pollutants providing from CNG lean burn engines. [ABSTRACT FROM AUTHOR]

Results of investigation of a fundamentally new type of cryogenerator in which the energy of the active flow is transferred to a passive flow are presented. The cryogenerator is called rotor-wave generator. A nonlinear mathematical model describing processes that occur in a rotor-wave cryogenerator (RWCG) is developed. Its distinguishing feature is the fact that it takes the properties of the actual gas into account in calculating the integral characteristics of the RWCG and in the method employed by Academician of the Russian Academy of Sciences S. K. Godunov (fracture-disintegration method). Results of calculations are presented as plots of gas parameters in the extreme computational cells, an indicator diagram, and the wave pattern of energy exchange in the RWCG. Analysis of the results obtained for mathematical modeling indicated good convergence with experimental results. Basic processes that occur in the energy-exchange channel of the cryogenerator are brought to light. In our opinion, the type of cryogenerators investigated is of major practical interest. This paper has a direct relationship to the problem of thesearch for optimal production schemes for liquefaction of natural gas. [ABSTRACT FROM AUTHOR]

The dynamics of the interaction of two oppositely directed plasma flows generated by miniature gas-discharge magnetoplasma compressors is studied. The maximum plasma electron temperature and density in the region where the plasmas interact are found to be 4.5 eV and 1.4⋅10 cm. Exposure of samples to this kind of plasma near the interaction region leads to an energy flux at the surface of 2-8 J/cm, which is sufficient for modification of the surface properties of various materials. [ABSTRACT FROM AUTHOR]

The problem of stable motion of a real gas that obeys the van der Waals state equation in a vertical pipe is considered with allowance for the gas compressibility. The dependences obtained allow contributions of different processes to the formation of the pressure field and the character of density and velocity variations depending on the observation point to be judged as functions of the pipe length. [ABSTRACT FROM AUTHOR]

The present-day techniques for design and development of the embedded systems for monitoring and prediction of a technical condition of MW electrically driven units are examined with a case study at synchronous machines at gas-compressor stations. The statistical analysis of damageability and operational factors of aging of the insulation at stator windings of gas-compressor unit motors is cited. The example of an automated monitoring system for the STD-12 500 synchronous motor, based on innovative electric equipment and an automated process control system (APCS), is shown. [ABSTRACT FROM AUTHOR]

Different heat-engineering systems are examined for making use of low-potential secondary energy resources (SER) to supply heat and cold to a metallurgical combine. The article also examines the use of steam-compression heat pumps operating on the return-main water of industrial heat and power plants to supply heat to a city. It demonstrates the energy efficiency of combining the positive characteristics of steam-compression heat pumps and absorption heat pumps to supply heat and cold to the combine and the city. [ABSTRACT FROM AUTHOR]

The special features of diagnostics of turbine discs of ΓTK-10-4 gas compressor units tested by the dye penetrant flaw detection method are considered. It is shown that disc blades must be dismantled and carefully mechanically cleaned, the spots in discs where such flaws as cracks are generated most often being analyzed, thereby reducing the searching and detection time. [ABSTRACT FROM AUTHOR]

Major differences are pointed out between the design and working principles of a piston acoustic gas compressor and piston-based pumps and compressors. Working forms are given for the amplitude of the gas speed oscillation in the tube and the compressor throughput. The throughput is calculated for a tube of length 3.5 m with internal diameter 0.04 m and piston stroke length of 0.004 m. It exceeds that of a normal piston compressor with the same energy consumption by a factor of 8. [ABSTRACT FROM AUTHOR]

Work is presented and analyzed for vibration diagnostics and vibration adjustment using the example of the GPA-10DKS-04K Ural unit, developed and manufactured by NPO Iskra, on the site of DKS-3 Orenburggazprom. Recommendations are given for provision of a normal vibration state for shafting in the planning stage for units and compressor station equipment, factory tests, start-up and operation. [ABSTRACT FROM AUTHOR]

Complex chemical-engineering systems are analyzed as a class of control entities. Formalized formulations are presented for problems associated with optimal control of an equipment cascade, gas-compressor system, plasmochemical plant, and activation furnace. Use of typical classical methods of control optimization is substantiated on the basis of experimental problems analyzed. [ABSTRACT FROM AUTHOR]

A technology has been developed for repairing the worn cast-iron cylinder and piston in a motorized gas compressor: if the surface wear is more than 1.5 mm, sleeving is used, while with wear not more than 1.5 mm, gas-thermal coating is employed. Tests have been performed on a proposed material for plasma coating. There is a considerable increase in the working life of the repaired cylinders. [ABSTRACT FROM AUTHOR]

The purpose and basic tasks of tests included in the test programs and procedures are enunciated. A list of the most frequently measured parameters of gas pumping unit (GPU) and measuring instruments is given. The main organizational and technical problems of GPU dataware are formulated. [ABSTRACT FROM AUTHOR]