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Currently, the performance control of centrifugal compressors is mainly carried out using a throttle mechanism. However, this approach is associated with large losses of compressed gas energy and is economically unprofitable. In addition, throttling the compressed gas flow creates conditions for the occurrence of compressor surging. Therefore, the development of control systems for the electric drive of compressor units that prevent the occurrence of surge conditions is an urgent task. However, the creation of such a control system is impossible without creating an adequate compressor model. The dynamic model of the centrifugal compressor was refined taking into account the operation of the anti-surge valve. A model predictive controller was used to control surge and maintain them at a level below the acceptable level. Thanks to MPC ability to predict the behavior of the system, operation is ensured away from the surge boundary even in the presence of uncertainties. [ABSTRACT FROM AUTHOR]

Gas fuel from gas wells is burned in gas engines so that the resulting mechanical energy can drive compressors in gas fields. As the quantity of gas from gas wells decreases over time, associated gas is an attractive substitute. The purpose of this research is to obtain a safe and comply-to-government regulation emissions associated gas combustion without changing the ignition timing. This is achieved by setting the value of the air-to-fuel ratio in gas engines without changing the ignition timing. The air-to-fuel ratio range that provides the lower emissions than the government limit and the longer IDT than the existing gas is the recommended AFR range. The research method is to simulate the kinetics model of the oxidation and combustion of the associated gas. The associated gas in this research is that in a gas field that has been dehydrated in the previous unit. The gas engine in this research is that in the gas field that currently uses existing gas from gas wells to drive compressors. The results show that the combustion of the dehydrated associated gas with the CO2 mole fraction being 0.5325 in the gas engine is safe and releases the emissions that comply to government regulation if the AFR is set to less than 7.5 without changing the ignition timing. [ABSTRACT FROM AUTHOR]

The article proposes a nonlinear optimal control approach for the dynamic model of a gas centrifugal compressor being driven by an induction motor (IM). The dynamic model of the integrated compressor-induction motor system, being initially expressed in a nonlinear and multivariable state-space form, undergoes approximate linearization around a temporary operating point that is recomputed at each time-step of the control method. The linearization relies on first-order Taylor series expansion and on the computation of the associated Jacobian matrices. For the linearized state-space model of the compressor-IM a stabilizing optimal (H-infinity) feedback controller is designed. This controller stands for the solution to the nonlinear optimal control problem of the compressor-IM under model uncertainty and external perturbations. To compute the controller's feedback gains an algebraic Riccati equation is repetitively solved at each iteration of the control algorithm. The global stability properties of the control method are proven through Lyapunov analysis. [ABSTRACT FROM AUTHOR]

The compressor is an integral part of the mechanical process industry, widely used in the oil and gas sector. The tandem cylinder belongs to the class of small cylinders with a range of bore diameter from 1.8" to 1.25". Methane gas is compressed in a cylinder to transfer the gas from one place to another. In the three-stage reciprocating gas compressor, the tandem cylinder compresses the gas from 160 bar to 225 bar at an operating speed of 1800 rpm. The tandem cylinder is a single-acting cylinder connected to the three-stage compressor by a common connecting rod The present research work uses ASME codes and API 618 standards to design the tandem cylinder. The numerical investigation is carried out using a commercial tool to study the thermal stress concentration, total deformation, and modal analysis. In a tandem cylinder, the thermal stress ranges from 50 to 150 MPa, below the allowable stress, and the deformation all along the surface of the bore is 0.01 mm, below the maximum permissible deformation. The numerical investigation shows a frequency of 97 Hz, which is significantly higher than the natural frequency. Consequently, the tandem cylinder is stable under the specified operating conditions and won't resonate. [ABSTRACT FROM AUTHOR]

Parallel compressor gas operation mode is used when the natural gas pressure is still sufficient with one compression stage to reach high pressure; if the gas feed pressure is below the compressor design pressure, it is necessary to increase the pressure to two stages. The purpose of this study was to analyze the effect of changing the gas turbine compressor operating mode from parallel to series due to a decrease in gas well pressure. The ability of a compressor to compress gases under its design pressure can be simulated with a simulator. Parallel compressor operation can be simulated as two-stage compression by being connected in series using the ASPEN HYSYS. The simulation results of the compressor suction pressure drop from 318 psig to 200 psig at the compressor unit at the natural gas processing station of PT. Z show the compressor performance curve is still stable and far from the surge line when used in series operation mode. Recalculation of the surface facilities of the separator and scrubber units shows that the fluid retention is still under 5 minutes, the velocity and momentum of the fluid in the vessels are still below the maximum capacity of the equipment, and the required cooling load is still below the available duty coolers. In the piping system, when operating under compressor design pressure, the fluid velocity value is still below the pipe erosion velocity (for two-phase flow), while for single-phase flow it is below 60 ft/s for the gas phase and 15 ft/s for the liquid phase. Based on the simulation carried out and recalculation of the feasibility of surface facilities, changing the compressor operating mode from parallel to series is feasible and can be carried out safely. [ABSTRACT FROM AUTHOR]

The paper presents the results of CFD calculations of the gas flow in the exit nozzle of a single-stage compressor with a capacity of 32 MW, with polytropic efficiency at the design flow rate 90%. The exit nozzle, the so-called volute, has a specially designed design - features of the shape and size ratio were proposed by Yu. B. Galerkin. The efficiency of the volute was estimated by the loss coefficient based on the results of CFD calculations for five flow rates, covering the entire range of changes in the gas-dynamic characteristics of the compressor. The structure of the flow was analyzed in various modes of operation: a decrease in the overall level of velocities with an increase in the mass flow rate was noted, which did not contradict the physically expected result, the presence of gas recirculation zones near the volute's tongue at extreme modes in terms of mass flow and practically unimpressed flow around the tongue at the design mode, the presence of flow irregularities and vortex structures is estimated. Despite the noted high compressor efficiency, the analysis of the flow structure in the outlet device suggests the possibility of increasing efficiency due to the optimal design of the volute. Thus, the development of practical recommendations for the optimal design of the outlet devices of centrifugal compressors based on information on the flow structure obtained using CFD calculations in addition to the existing methods of mathematical modeling seems to be relevant. [ABSTRACT FROM AUTHOR]

Resource conservation tasks at various productions, including those connected with extraction and transport of natural gas determine the need for the development of efficient technologies during creation and operation of the required equipment. For booster compressor stations within the framework of complex gas treatment this along with application of two and more compression stages, interchangeable flow parts of gas compressors, low-temperature separation assumes application of modern heat exchange systems, new designs and layout of the heat exchange equipment. Achieving a comprehensive, balanced solution, taking into account all highlighted aspects on the way to developing a highly efficient plant process flow, requires maximizing the benefits of each technology. [ABSTRACT FROM AUTHOR]

The fleet of centrifugal compressors for the gas industry of the Russian Federation consists of more than 5,000 machines with a unit power of up to 32,000 kW and a service lifetime of 30 years or more. In 1990-2000 polytechnic scientists were involved in the gas-dynamic design of compressors and replaceable flow paths of a new generation as part of the Ural-Gazprom program. Having their own engineering method of optimal design and calculation, the polytechnics solved the problem by creating with industrial partners several dozen compressors and replaceable flow paths (RFP). Their power was in a range 10,000-25,000 kW and an efficiency of 3-4% higher than all analogues. A new stage of modernization is relevant now. Scientists-polytechnics by this time have realized for industrial partners more than 50 projects of the new compressors and RFPs, and also have accumulated a previous experience. The mathematical models of the Universal Modeling Method have been significantly developed and improved during last 20 years. At the expense of the Center for National Technological Initiative of SPbPU, the test rig was built the ECC-55 experimental rig for testing the most responsible and innovative projects. CFD-optimization techniques have confirmed their effectiveness in relation to stator elements of the flow path. The optimization of stator elements of an intermediate type stage with a vaneless diffuser is given as one of an example. [ABSTRACT FROM AUTHOR]

The design of a compressor is very much dependent on its internal and external operating conditions throughout the design life. The properties of the process fluid introduced at the commissioning stage and throughout operation cycles as well as the external environment it operates are two significant factors that need to be considered in designing a gas compressor. The design basis should be clearly stated at an earlier stage to ensure all factors are considered and if necessary incorporated. In parallel, the importance to adhere to required specifications during overall manufacturing of the compressor before delivery to the construction site need to be ascertained through reliable assurance processes to ensure the compressor would be able to deliver its intended duties in term of capacities, safety, and expected service life. In the oil and gas industry, a significant proportion of rapid degradation of compressor performance is due to high vibration issues attributed to impeller failures. Hydrogen stress cracking, erosion, and erosion-corrosion are among the common types of damage mechanisms identified as immediate causes of impeller failures. Detailed assessments in form of failed component inspection and metallurgical laboratory analysis, overall equipment functionality checking, and operational philosophy validation were conducted to establish causes of the failures. This paper captures the investigation process undertaken after the failure of an impeller of a centrifugal compressor covering the aspects of design, fabrication, process changes, equipment functionality, and the associated outcome of each element. [ABSTRACT FROM AUTHOR]

Reliable operation of reciprocating compressors in wide ranges of operating parameters is one of the most important problems in the design, production and operation of compressor equipment. This article discusses the issues of utilization of organic waste, in particular the tree bark formed in large quantities during logging. The complexities and industrial methods of utilization, which ensure the production of synthesis gas from solid organic waste, are considered. The synthesis gas compression process is investigated to increase the efficiency of the utilization process. Ensuring the compressor operability in wide ranges of parameter variation requires multivariate calculations in order to find the best design parameters of the compressor. A compressor is proposed for the implementation of the task and its characteristics are calculated. [ABSTRACT FROM AUTHOR]

The article covers the issues of digital engineering of low flow rate centrifugal compressors. The additive technologies of parts and assembly units manufacture with the use of 3D-printing by metallic and non-metallic materials mastered by the Russian and foreign enterprises in different fields of industry (including aerospace construction and power engineering) have been revealed, the most prospective materials, achievements and trends of development have been analyzed. The experience in application of air and gas centrifugal compressors has been analyzed, the metallic and non-metallic materials used for their manufacture have been studied. The main factors determining the cost indexes and efficiency of centrifugal compressors have been revealed. Optimum structure and parameters of centrifugal compressors have been determined. The engineering and manufacturing methods providing decrease in the material consumption and increase in the strength of compressor parts and assemblies have been proposed. [ABSTRACT FROM AUTHOR]

The paper presents the numerical simulation results for the influence of output flow parameters downstream the compressor on the hydraulic losses in the separation diffuser of a combustion chamber. We have obtained the influence dependences of the input velocity profile asymmetry on the hydraulic losses in the diffuser. [ABSTRACT FROM AUTHOR]

Natural gas is one of the widely used sources of energy around the world. Gas transportation networks, which work at high pressure, use compressor stations to supply the needed energy to move gas between two distant sites. The present work describes a tool used to simulate the dynamic behavior of a gas compressor station. Possible transient situations can be due to the start-up or shutdown of the compressor, change of the gas flow required by the downstream gas network or switch of the station layout. The mathematical models of compressor, cooler, valve, pipe and anti-surge control are discussed. After that, the model of a one-stage gas compressor station is validated using data obtained by the Energy System Modular Solver, which was used to analyze compressor station, gas turbine and power plants in a lot of previous works. Lastly, the gas compressor station is simulated during a typical variation of the flow required by the downstream pipeline to predict its dynamic behavior. [ABSTRACT FROM AUTHOR]

The maximum efficiency cycle of the heat losses recovery system with multiple heat sources at the different temperature levels is presented in the paper. The efficiency equation was obtained on the basis of the cycle thermodynamic analysis. The analysis results were applied to the heat losses recovery system of the compressor unit comprising two sources of the compressed gas and compressor motor-drive exhaust gases heat losses. Consequently, the system cycle efficiency equation was obtained, as well as the fuel saving coefficient characterizing the recovery system performance was considered. The efficiency and fuel saving coefficient parametric analysis was carried out. [ABSTRACT FROM AUTHOR]

The present article deals with approaches to calculating a reciprocating gas engine-driven piston compressor for the contraction of natural gas for long-term extraction in conditions of depleted gas formations. Such a task is highly relevant for the gas extraction industries in terms of cost reduction of the extraction of gas. The application of the proposed methodology makes it possible to decrease the final cost of output, which implies an increase in business profitability. [ABSTRACT FROM AUTHOR]

Procedure of conductance calculation of radial channels formed by moving walls in non-contact pumps and compressors in viscous gas flow regime is developed. Comparison of calculated data and data obtained by numerical solution of gas flow is carried out for inlet pressures from 100 to 105 Pa and wall velocities 5–40 m/s. Formula for approximate conductance calculation of channels with moving walls used as the initial approximation in the presented procedure is obtained for faster calculation. [ABSTRACT FROM AUTHOR]

The article describes the experience of JSC "Compressor" in creation of advanced compressor equipment employing reciprocating compressors for the oil and gas sector. Issues of 3D modelling, calculation, survey and improvement of reciprocating compressor valves with account of gas real properties and actual operation conditions are considered by the example of a multi-stage reciprocating compressor with the use of computer gas dynamics methods. Efficient and reliable operation of reciprocating compressors within the wide range of operating conditions is one of the most important problems in design, production, and operation of the compressor equipment. Reciprocating compressors used as part of mobile gas filling tanks are intended for compression of natural gas up to the final pressure of 20-25 MPa. When such equipment is being designed, real properties of the fluid to compress have to be determined. The paper surveys theoretical influence of initial gas parameters on the working process of the compressor. Compression of both ideal and real gas has been surveyed, with its results provided herein. The mathematical model developed is briefly described, and methods to determine thermodynamic properties of methane are provided, with comparison results of calculated and tabular data available. Results of adequacy analysis of the mathematical model are given. Improvement of valves at the design stage enhances energy efficiency of the compressor operation and allows avoiding such negative phenomenon as flutter at high-pressure stages. Efficient stripping and dehydration of high-pressure natural gas downstream of the compressor with the use of PSA modified technology and batch heating of recycle gas is considered. [ABSTRACT FROM AUTHOR]

Energy efficiency in refrigeration and air conditioning vapor compression systems has been focused on the development of modulation methods allowing variation of compressor energy consumption according to refrigeration requirements, or the use of alternative energies for running those compression systems. However, even when a compressor comes with frequency inverter, improper selection can lead the user to spend more energy during low cooling loads; or force the compressor to work under conditions for which it was not designed. Thus, the present article shows how the determination of the return gas temperature of the compressor can affect its performance and may vary according to the type of application. Therefore, the operation of reciprocating and rotary compressors was simulated and monitored under the same nominal conditions and determined its cooling effect and its compression capacity. The results show that for the same type of compressor, differences in system capacity are approximately constant regardless of the type of refrigerant used in low temperature applications. The compressor capacity for medium and low temperature systems is independent of return gas temperature using R-22. [ABSTRACT FROM AUTHOR]

The subject of research was the oil-associated gas high pressure compressor station. Operation of two-cycle centrifugal compressor installation at limit working conditions with using advanced method of gas-dynamic characteristics simulation (recalculation) for other operation conditions has been considered. Considered limit the compressor installation operation modes allowed to prove selection of design pressure for pipelines and equipment. [ABSTRACT FROM AUTHOR]

The present article deals with a possibility of using metal hydride materials for the hydrogen compression and points out the necessity for the interim hydrogen storage when changing the temperature of a pair of tanks containing the La0.85Ce0.15Ni5 alloy in a tandem arrangement. For the purpose of the required heating and cooling, the tank is equipped with a pair of the Peltier modules with water cooling. The analysis of the measured operational parameters facilitated obtaining the thermal, output, and kinetic parameters of the thermal field balancing necessary for the operation of a hydrogen compressor. [ABSTRACT FROM AUTHOR]

This article focuses on the results of the research on the wear of air turbo-compressor engine blades operated in a dusty environment. In detail, the mechanism of the dust influence on the geometric characteristics of the axial compressor blades is discussed. De-pending on the operating time of the engine, basic laws on the dimensions of the wear of the blades in different degrees of the axial compressor are mentioned. Based on the experimental results, the possibilities of modeling the erosive wear of compressor blades are solved. [ABSTRACT FROM AUTHOR]

Naturally circulated helium loop is a device designed for a decay heat removal from fast nuclear reactors of the type ALLEGRO. The flow is provided by a potential energy difference between hot and cold piping branch. Here we introduce a 1D model of flow in the loop. The model describes the flow of a highly compressed gas with changing density in straight pipes and in the obstacles. The results of the model are compared with experiment. [ABSTRACT FROM AUTHOR]

Vibrations are a very typical feature of all compressors and are given great attention in the industry. The reason for this interest is primarily the negative influence that it can have on both the operating staff and the entire machine's service life. The purpose of this work is to describe the methodology of screw compressor analysis from a vibration point-of-view. This analysis is an essential part of the design of vibro-diagnostics of screw compressors with regard to their service life. [ABSTRACT FROM AUTHOR]

The paperdeals with use of LOOP thermosyphonheat pipe to transfer heat from electrotechnical box and describe of construction individual types ofLOOP heat pipes. The LOOP heat pipe is very good cooling device which requires no mechanical parts in their design. LOOP heat pipe use only phase change during heat transfer, without a compressor, fan orpump. LOOP heat pipe is more energy saving compared to conventional cooling systems with forced convection. The main advantage of cooling by heat pipe is that electrotechnical box canbe hermetically closed (dust-free construction), because dust reduces the lifetime of electrotechnical elements in box Lifetime ofLOOP heat pipeequals to the lifetime of construction material. The paper describes mathematical model of LOOP thermosyphon heat pipe (condenser). Compares selectedtypes of working fluids which are filled with a heat pipe and construction materials of heat pipe. [ABSTRACT FROM AUTHOR]

The developed experimental bench allows using the known calculation technique to determine the conventional clearance in the valves of compressor units. The obtained results will provide their use in the developed method for calculating the operating processes of slow-speed long-stroke reciprocating compressors. [ABSTRACT FROM AUTHOR]

Based on the results of experimental studies of the operating processes of the air slow speed stage of a reciprocating compressor under water and air cooling, verification of the calculation technique of the operating processes of this stage has been performed, which takes into account the influence of the operating mode and design parameters of the stage on the heat exchange process in its working chamber and on the temperature mode of the stage as a whole under discharge pressures up to 3 MPa. [ABSTRACT FROM AUTHOR]

In the framework of this paper, there have been analyzed power station building methods to construct a power station for utilities for gas-main pipelines compressor stations. The application efficiency of turbo expanders in them to expand the power gas of compressor stations' gas compressor units has been shown. New schemes for gas-turbine expander power generating systems have been proposed. [ABSTRACT FROM AUTHOR]

The article deals with some improper performance reasons of reciprocating compressors which are in yearround operation. The possibilities and recommendations for design optimization of some details and components and compressor operating parameters under existing industry conditions by means of the upgraded volumetric machine calculation program KOMDET-M designed for analyzing processes occurring in volumetric machines are represented. The calculation result agreement with parameters claimed by vendor and actual ones of gas reciprocating compressors which are in operation is shown. The scientific and practical value of the research for any designed, upgradable or operating unit is demonstrated. Necessary calculations have been performed by means of the application calculation program. Some examples of volumetric machine reliability and efficiency improvement are represented. [ABSTRACT FROM AUTHOR]

Oil and gas are the main sources of Russian national wealth. Russia has the greatest reserves of oil and gas in the world. It gives the status of energy stowage of the Earth. This is especially true concerning natural gas. Transportation of natural gas from the gas field and its supply to the end user is carried out by means of pipelines. [ABSTRACT FROM AUTHOR]

A systematic approach with proper statistical analysis techniques for analyzing maintenance data can give insight on how well the performance of the existing system. The objective of this study is to present a methodology for systematically analyzing the maintenance data of offshore gas compressor system to gain insight about the system performance and identify the critical factors influencing the performance. The study approach is based on problem and data-lead rather than technique-driven. The results of trend test propose that the system under studied can be modeled using a simple Homogeneous Poisson process (HPP) process where the failure rate is constant. Analyses of covariates are done using Kaplan Meier and Proportional hazards models. The results indicate that the preventive maintenance (PM) plus engine wash has a significance influence on the system failure distribution. This covariate is found to play a positive role in extending the inter-arrival failure times thus improving the system performance. [ABSTRACT FROM AUTHOR]