Compressor System Research Articles

Use of experimental and numerical simulation methods for rational design of the air cooling apparatus for lubrication systems of compressors

The objective of the present work was to study heat and hydraulic parameters of an air cooling apparatus of oil (ACAO), whose geometry of its flow-through part is changed to decrease hydraulic losses in its air conduit and to increase the cooling efficiency of oil. Using numerical simulation methods of heat transfer, we have developed and tested the computational techniques applied in a wide class of heat exchange apparatuses, including those consisting of the sections of finned flat tubes manufactured by extrusion with subsequent deforming cutting. We have proposed to make a finned part of a heat-exchange surface in the form of porous inserts. This has allowed us to reduce numerical simulation equipment requirements and to decrease computational time. Predicted results well agree with experimental data; their analysis shows that the calculated value of thermal performance of the oil cooler due to the revealed construction drawbacks of the air conduit is by 19 % less than that of the designed one. Based on the results of the numerical simulation studies, a number of recommendations have been made how to improve the layout inside the air cooling apparatus for oil in order to enhance its thermal performance and aerodynamic quality. In particular, we have proposed to mount new fan blades to enhance its performance; to change the construction of the air outlet valve by taking away a baffle that partially overshadows the exit area of the bottom fan; to modify the shape of the bottom collector of the oil cooler in order to make a uniform velocity profile at the entrance of cooling sections. Connecting in series heat exchange sections may be a perspective engineering decision. The outcomes of all proposed engineering decisions can be assessed by numerical simulation methods that will allow us not to design expensive equipment.

Performance optimization of a heat pump integrated with a single-screw refrigeration compressor with liquid refrigerant injection

Refrigerant injection is a good method for reducing the exhaust temperature of a single-screw refrigeration compressor (SSRC). In this paper, an accurate method is proposed to calculate the variation of the injection area for different initial positions and different sizes of injection holes. Furthermore, a mathematical model describing the internal working process of an SSRC with liquid refrigerant injection (LRI) is established to evaluate the performance of an SSRC and heat pump with a variety of injection hole geometries and working conditions. This theoretical model is verified by comparing the calculation results with experimental data. The results show that LRI can markedly reduce the exhaust temperature and improve the performance of the SSRC and heat pump to some extent. The injection-hole radius is the most important factor affecting the performance of the compressor and heat-pump system. The variations of different performance parameters of the SSRC and heat pump at low ambient temperature can be obtained. This work provides a theoretical method for optimizing the injection process in SSRCs.

Influence on the Electrical Efficiency of a Hybrid MGT-SOFC-System by μ-fogging in a-Two-Staged Compressor System

Hybrid combinations of solid oxide fuel cell and recuperated micro gas turbines can convert the chemical energy of hydrocarbon-based fuels in electrical energy with high electrical efficiency. With an integrated and improved cycle management, more than 70% of the energy content of the fuel could be converted. Therefore, the systems are highly suitable for the Power-To-Gas conversion. In particular, a pressure charging of the SOFC fuel cell leads to an increase in stack performance. By a downstream turbo set, after residual fuels are intentionally oxidized with an afterburner, additional electrical energy can be gained from the expansion of the hot exhaust gas stream and the overall efficiency can be increased. In order to increase the electrical efficiency of the system, it is proposed, to ensure the required compression of the process air in particular by a-two-staged turbo compressor with an intermediate cooling system. By thus achievable reduction of the dissipation of the compressor and by targeted condensation of finest drops in front of the second compressor stage affected by intermediate cooling, an increase in efficiency of the system is possible. This is achieved by targeted cooling of the process air behind a low pressure compression, so that it is saturated over 100% relative air humidity. As a result, a slightly supersaturated airflow is available for the second compressor stage, which enters the compressor after heat removal via an intermediate cooling having a small number of microdroplets. Therefore, the condensed water evaporates again by the heat of compression in the second stage and the compressed flow ultimately enters the recuperation at a lower temperature than during normal compression. Thus, more heat can be recovered within the recuperation system. Therefore, the electrical energy of the system can be produced having higher efficiency, because the heat dissipation of the overall system decreases. In this article it is presented, how such a process is thermodynamically modelled and how a technical realization can be built after optimization by simulations. Finally, in this study, the process-influencing factors are analyzed to show the highest possible electrical yield of such a system.

Experimental behaviour of a three-stage metal hydride hydrogen compressor

A three-stage metal hydride hydrogen compressor (MHHC) system based in AB2-type alloys has been set-up. Every stage can be considered as a Sieverts-type apparatus. The MHHC system can work in the pressure and temperature ranges comprised from vacuum to 250 bar and from RT to 200 °C, respectively. An efficient thermal management system was set up for the operational ranges of temperature desired. It drops temperature shifts due to hydrogen expansion during stage coupling and hydrogen absorption/desorption in the alloys. Each reactor consists of a single and thin stainless-steel tube to maximize heat transfer. These were filled with similar amount of AB2 alloy. The MHHC system was able to produce a compression ratio as high as 84.7 for inlet and outlet hydrogen pressures of 1.44 and 122 bar for a temperature span of 23 °C – 120 °C.

Experiments on the Pulse Repetition Frequency Optimization of 1.3-GHz, 100-kW Microwave Pulse Compressor

A microwave pulse compressor (MPC) system formed by an inductive iris, a straight rectangular waveguide, and an H-plane T-junction is experimentally studied. The MPC design, which is based on an equivalent circuit simulation model, ensures the optimum cavity-storage gain at 1.3 GHz. A low-pressure gas discharge tube (GDT) that is placed at the side arm of the T-junction implements the switching trigger for the cavity energy extraction. The experimental results show that high pulse repetition frequency (PRF) operation together with optimal cavity-extraction gain is feasible by carefully selecting the GDT gas type, pressure level, and flow rate. Under optimal conditions, the MPC system approaches the theoretically predicted cavity-extraction gain of 19 dB and a PRF up to 300 Hz.

Sulzer invests in Finnish compressor company Tamturbo

Sulzer has taken a 25% stake in Tamturbo Plc, a Finnish technology company that develops and manufactures oil-free industrial air compressor systems.

Developing a mathematical tool for hydrogen production, compression and storage

Among the few lessons learned presented in the literature, authors put in evidence the on-going need to investigate on station components and their integration. The specific power consumption of station units with on-site hydrogen generation is often subject to uncertainty, and it would have been desirable to find more details about the energy contribution of each component. To address this gap, this paper focuses on the development of a mathematical modeling as a dynamic and multi-physical design tool to predict the energy performance of hydrogen production systems. Particularly, the model aims to describe and analyze the energy performance of two different electrolyzer technologies (PEM and Alkaline), integrated with a compressor system and gaseous buffer storage. Multiple tank options and a switching strategy are investigated, as well as a control system to simulate a real infrastructure operation. Auxiliaries and components related to the thermal management system have been also included. A carbon-footprint analysis follows the energy one, focusing on the CO2 emission reduction. Comparisons between literature data and model show that the hydrogen system proposed model is suitable to evaluate systems with respect to energy efficiency and system performance. The model could be a powerful tool for exploring control strategies and understanding the contributions to the overall energy consumption from the various internal components as a guide to researchers aiming for improved performance.

A hybrid solid oxide fuel cell-gas turbine fed by the motive steam of a multi-effects desalination-thermo vapor compressor system

It is known that the production of electrical power and water is a challenging issue. In this article, the feasibility study of a new configuration of a solid oxide fuel cell-gas turbine coupled with a multi-effect desalination thermo vapor compressor is performed. In this method, the generated steam by a heat recovery steam generator is utilized directly to a solid oxide fuel cell. This condition causes a water pump protrudes from the solid oxide fuel cell cycle, and the internal pressure of the heat recovery steam generator is kept equal to the solid oxide fuel cell pressure. In the proposed model, the effects of some design parameters such as the inlet temperature of the solid oxide fuel cell, cycle pressure, fuel utilization factor, steam to methane ratio on electrical power and water generation of the system have been theoretically investigated. The mathematical model of the system is created in Engineering Equation Solver software. The two main parts of the system have been validated with the available literature. The results showed that while increasing the pressure ratio of air and fuel compressors leads to decreasing the mass flow rate of the distilled water, the gain output ratio of the desalination system increases. Moreover, in the proposed model, capital cost of the system and the corresponding cost per unit of time are decreased by 224,844 USD and 6.37%, respectively.

A Comprehensive View to Surge Frequencies and Stall Stagnations in Axial Flow Compressor Systems

A Comprehensive View to Surge Frequencies and Stall Stagnations in Axial Flow Compressor Systems

Podešavanje intervala održavanja temeljem iskustva, studija slučaja sustava brodskih kompresora

Podešavanje intervala održavanja temeljem iskustva, studija slučaja sustava brodskih kompresora

Application of Gaussian pulsed beam decomposition in modeling optical systems with diffraction grating.

A diffraction grating is one of the most commonly used components in ultrafast optical systems such as pulse stretchers and compressors. Hence, modeling the temporal dispersion and spatiotemporal distortions associated with the angular dispersion of a diffraction grating is very crucial for wave optical modeling of such systems. In this paper, the Gaussian pulsed beam decomposition (GPBD) method is extended to handle the propagation of ultrashort pulses, with arbitrary spatial and spectral profiles, through complex ultrashort pulse shaping systems containing diffraction gratings. Although the diffraction efficiencies are not rigorously computed, the GPBD method enables modeling of the large angular dispersion of idealized diffraction gratings without running into an impractically large number of spectral samples as in the case of Fourier-transform-based methods. The application of the extended method is demonstrated by performing the wave optical propagation of an ultrashort pulse through a single diffraction grating and then through a Treacy compressor system. By combining the Treacy compressor with the Martinez grating pair stretcher with internal lenses, the pulse shaping through a complete chirped pulse amplification (CPA) setup is modeled. Finally, the effects of using real dispersive lenses in the Martinez stretcher on the output pulse of the CPA setup are presented. For analysis of the output pulses, methods of computing the spatiotemporal and spatio-spectral amplitudes of the output pulse from the phase correct superposition of individual Gaussian pulsed beams are presented.

STUDY OF THE EFFECT OF A NEW COMBINED INHIBITOR AND A PERMANENT MAGNETIC FIELD ON CORROSION AND SALT DEPOSITION

This academic article encompasses the investigation results concerning, the composite acquired from the mixture of hydrated technical phosphatide, cubic thickness of polypropylene glycol, and sodium hexametaphosphate. According to the outcomes of laboratory researches, it was determined that the developed new composite provides not only prevention of equipment from corrosion, but also protection of those from salt deposition. Furthermore, as a result of the joint effect of a stable magnetic field of 280 kA/m, high protective efficiency was determined. Thus, the optimum consumption was found to be 150 mg/l. In this case, the protection effectiveness against corrosion and salt deposition accounted for 93% and 85% accordingly. Commercial tests of the combined action of the reagent and the permanent magnetic field were carried out on the cooling system of compressors “Bibiheybatneft” OGED (Oil and Gas Extraction Department). In the field with the combined use of a magnetic field and inhibitors the protective effect is 90%, and the protective effect of salt deposition is 73%. Keywords: oilfield equipment, salt deposition, inhibitor, aggression, composite, corrosion.

Subsurface Compression Lifts Liquids, Increases Gas Production in Unconventional Well Trial

It is well known that liquid loading in unconventional gas wells can dramatically reduce production and lead to premature abandonment. Liquid loading creates a “vicious cycle” that occurs when liquid blockage creates backpressure in the wellbore or pore space in the formation, resulting in reduced gas velocity and leading to more liquid accumulation over time. Electrical submersible pumps (ESPs) and other artificial lift technologies are typically unable to remove liquids in both the vertical and horizontal sections of the well. A new downhole compressor solution, based on advanced magnetic technologies, was developed by Upwing Energy and recently completed its first field trials in an unconventional gas well operated by Riverside Petroleum. Analysis of results during the trial revealed a 62% increase in gas production and significant increase in liquid production over its steady­state performance using a rod pump prior to the subsurface compressor system (SCS) installation. Subsurface Compressor System The SCS is designed to provide reliable performance in the downhole environment by eliminating the common points of failure in conventional ESPs. It is based on proven magnetic technologies used in topside and subsea oil and gas applications (Fig. 1), which were deployed downhole successfully for the first time during the Riverside trial, including: A high­speed permanent magnet (PM) motor A shaftless magnetic coupling between the motor and compressor Passive noncontact magnetic bearings with electronic dampers A sensorless wide­frequency variable speed drive at the surface controls the motor at speeds up to 50,000 rpm via a long stepout. The hybrid axial wet­gas compressor is driven by the hermetically sealed high­speed PM motor. Torque is conveyed from the motor to the compressor with no mechanical shaft or seals, eliminating the need for a motor protector to isolate the motor from downhole fluids. This “protector­less” architecture eliminates a frequent source of vulnerability for conventional downhole artificial lift systems. The SCS lowers the bottomhole well pressure, increasing the velocity of the gas stream, removing liquids from the vertical and horizontal sections of the well, and preventing vapor condensation by increasing the temperature of the gas when exiting the compressor. Decreased backpressure from liquid loading results in increased gas production, which in turn accelerates liquid unloading. Once the liquid is carried by the gas stream, the lower pressure at the compressor intake and the higher temperature at the compressor discharge prevents vapor condensation and enhances the carryover of liquids to the surface by the gas stream. Field Trial The SCS was deployed in an unconventional shale gas well owned by Riverside Petroleum in Indiana. The trial period started at the end of October 2019, and the SCS was removed in early December. The well has a 2,000-ft vertical wellbore and a 5,000-ft horizontal wellbore, where liquid had accumulated (Fig. 2). The compressor was installed at the bottom of the vertical section with a tail pipe extending approximately 1,000 ft into the horizontal section to provide sufficient velocity to carry liquids while minimizing friction losses. A shroud was used to be able to carry the extended length of the tail pipe.

An Essential Cause of Stall Stagnations in Compressor Surges

The author has proposed in the preceding study on the behaviors of infinitesimal perturbations of surge in simplified compressor systems that the occurrences of stagnations could be closely related with the travelling wave conditions of the surge oscillations through the phase-differences and the propagations along the flowpaths. The concept was applied to real situations of systems of compressors and flowpaths in the present study. It resulted in a non-dimensional parameter named flowpath-average reduced resonance frequency, fSUBRav/SUB, which is an equivalent of the phase-propagation parameter proposed in the preceding study. It is finally a product of the resonance frequency of the system and the time required for the fluid particles to pass through the whole flowpath, namely, the total number of excitations that the fluid particles suffer in the time. A number of numerical experiments on compressor surges have demonstrated that the fSUBRav/SUB parameter could explain the cause of surge stagnations very simply and clearly. It has values of 1.5 – 3 at the stagnation boundaries for variations in flowpath configurations and compressors having a single-stage to nine stages. It means that the stagnations occur for the total number of the excitation cycles less than 1.5-3. It could be the most essential cause of the stagnations. In other words, deep surges could develop only after the fluid particles have experienced more number of cycles of the excitations in the passing time. In further, the fSUBRav/SUB parameter is made more comprehensive by multiplication of the compressor tip Mach number Mt, i.e., fSUBRav/SUB×MSUBt/SUB, which gives a nearly constant value of 1.5 over a wide range of flowpath configurations and tip speeds of compressors, for relatively small number of stages. Those parameters not only suggest the essential cause of surge stagnations, but also are the simplest and clearest measurers of stagnation boundaries. It is much easier to apply in real situations of the systems than any of the parameters proposed so far. However, for multi-stage compressors in long delivery flowpaths and in off-design operations, the parameters appear to deviate somewhat from the constant value.

Comparison and analysis of two processes for BOG re-liquefaction in LNG carrier with normal-temperature compressor

Two processes for boil-off gas (BOG) re-liquefaction of liquefied natural gas (LNG) carrier with normal-temperature compressor are proposed and compared: (1) the re-liquefaction system with the single mixed refrigerant process (SMRP), (2) the re-liquefaction system with the dual mixed refrigerant process (DMRP). The main thermodynamic parameters to be compared are specific energy consumption, exergy efficiency, coefficient of performance, heat transfer curves and exergy losses of main equipment in optimized case and base case. The result shows that the performance of the DMRP is better than that of the SMRP and the specific energy consumption of DMRP is 0.5635 kWh/kgLNG. In addition, by comparing the thermodynamic parameters of the re-liquefaction system with the normal-temperature compressor and the cryogenic compressor, it can be found that not only the cooling capacity of BOG is used effectively, but also the energy consumption is reduced and the efficiency is improved for the normal-temperature compressor system. Therefore, for the two mixed refrigerant re-liquefaction systems, the performance of the normal-temperature compression system is better than that of the low-temperature compression system.

FRIB helium compression system commissioning and performance test results

The design for the FRIB helium compressor system, used for the cryogenic refrigeration, was mainly based on the advancements developed for NASA James Webb project, improving the efficiency, reliability and maintainability from previous helium compression systems. The skid designs were further improved, first for the JLab 12 GeV project, and now with additional improvements for the FRIB project. The FRIB helium compression system has five operating compressors at maximum refrigeration capacity with an additional spare compressor. This spare can be configured to align its suction to any one of the three pressure levels of the five, discharging to the high pressure (4.5 K cold box supply) stream. This compressor system can support the 4.5 K cold box operation with a supply pressure varying from 6 to 21 bar, and without complex-sophisticated control of the gas management valves. This paper will briefly review several of the skid improvements and discuss some of the recent commissioning and test results.

Failure modes, effects and criticality analysis of a 3kW@4.5K helium refrigerator

The comprehensive research facility for key systems of fusion reactors was included in the “13th Five-Year Plan” priority project in China. In order to meet the requirements of cryogenic testing of large superconducting magnets, it is proposed to build a 3kW@4.5K refrigerator and carry out research on 3kW@4.5K superfluid helium cryogenic system. In order to evaluate the reliability of the 3kW refrigerator, the FMECA analysis was performed on the helium refrigerator. The refrigerator system is divided into three subsystems: the compressor system, the monitoring and control system and the cold box, to identify the failure mode and the impact on the refrigerator system related functions. The critical value is calculated and the critical matrix is drawn by the severity and the occurrence of the rating criteria. Identify the parts with high and medium risks and propose corresponding risk mitigation measures.

Commissioning of the Warm Compressor System for the ESS Accelerator Cryoplant

The accelerator cryoplant (ACCP) providing the cooling for the cryomodules and the cryogenic distribution system for the cold part of the ESS proton linac is being built and commissioned at the European Spallation Source (ESS) in Lund, Sweden. The ACCP warm compressor system (WCS) consists of several compression stages. The sub-atmospheric pressure stage (SP) is used to compress helium coming from the cold compressors directly to middle pressure (MP) level. The low pressure stage (LP) compresses the helium from LP level to the same MP level, being merged with additional flow from the cold box and the flow from the SP stage. The total flow is compressed in a single compression stage (HP) from MP to HP. The oil-flooded screw compressors are chosen in a way that the flow in each stage SP, LP and MP is compressed by a single screw compressor. Both, SP and LP compressors are equipped with a variable frequency drive (VFD) to adapt the compressor capacities to the various load cases. The ACCP had been contracted to Linde Kryotechnik AG in 2015 and all compressors are made by the Aerzener Maschinenfabrik GmbH, Germany. Following successful installation and commissioning in 2018, the final 100 hours test run at maximum nominal design condition and the part load tests under various ACCP operation modes were carried out at the beginning of 2019. The key parameters, including mass flow, power consumption, isothermal and volumetric efficiencies, are well fulfilled with the design data. The paper describes the system features, project challenges, lessons learned and acceptance test results.

The ESS Test and Instruments Cryoplant – First test results and operation experiences

The European Spallation Source (ESS) is a neutron-scattering facility being built with extensive international collaboration in Lund, Sweden. The world’s most powerful linear proton accelerator shoots protons against a rotating tungsten target where neutrons are knocked off (“spallate”) and are guided to the neutron instrument suites. Three cryogenic plants and a vast cryogenic distribution system serve the cooling needs of the superconducting RF cavities in the accelerator, the cold hydrogen moderators in the target, a cryomodule test stand and the sample environments for neutron instruments. The project’s demand of schedule and economic feasibility requires a high degree of parallel work for installation and commissioning of the cryogenic and auxiliary systems. The first of the three plants, the Test and Instrumentation Cryoplant (TICP) has been installed, commissioned and acceptance tested in 2018 by Air Liquide Advanced Technologies (ALAT). The plant consists not only of a standard compressor system and coldbox but also of a process vacuum system for 2K operation, internal and external helium purifiers, liquid helium tank, filling and boil of station and a helium recovery system. It is heavily integrated in the overall cryogenic installations at ESS. The paper describes some project challenges, acceptance test results and first operation experience.

FRIB cryogenic system status

The Facility for Rare Isotope Beams (FRIB) cryogenic plant has been successfully commissioned, including compressor system, 4.5 K cold box system, sub-atmospheric (2 K) cold box system, and the distribution system for two of the three linear accelerator (Linacs) segments. This plant uses the Ganni-Floating pressure process, allowing the compressor discharge and 4.5 K cold box supply pressure to automatically vary from 6 to 21 bar, without introducing additional exergetic losses to reduce the capacity (e.g., throttling turbine inlet valves, load heaters, etc.). The 2 K (31 mbar) load is supported using five stages of centrifugal compressors, housed within the sub-atmospheric cold box, which recompress the helium to 1.15 bar (and around 30 K). In 2012, FRIB assumed the responsibility, in collaboration with JLab to design and procure the sub-systems after the decision to move away from an industry supplied turn-key system. FRIB was responsible for procurement of all systems, all onsite activities, including the installation and integration of all the subsystems, development of the control systems, as well as, the integration, commissioning, and testing of each sub-system. At present this has culminated in the production of the first beam through the first Linac segment. An overview of the planning and execution of the project will be presented, which allowed meeting of scheduled goals and anticipated performance, and prevented the need to store or ‘double-handle’ any equipment.