装备主动磁力轴承的大功率电机压缩机机组的应用与配置

第61卷，2019年第6期
Vol.61，2019,No.6
Chinese Journal of Turbomachinery
Application and Configuration of High Power
Motor-compressor Units Equipped with Active Magnetic
Bearings*
Zeng-lin Guo1Yu-jing Wang2Richard Shultz3Andrea Masala4
(1.Waukesha Magnetic Bearings,Suzhou,China.zguo@,2.Shenyang Blower Works Group Corporation, Shenyang,China.sjwangyujing@,3.Waukesha Magnetic Bearings,Pawcatuck,USA.rshultz@,
4.Waukesha Magnetic Bearings,Worthing,UK.amasala@)
Abstract：With the high reliability and high availability they provide,active magnetic bearings(AMBs)have found increasing application in high-speed and high-performance turbomachinery.The oil&gas and energy industries represent core markets for AMB products and have been at the forefront of their deployment and innovation over the past three decades,driving the development of international standards for AMB-equipped turbomachinery.Typical machinery equipped with AMBs include electric motors and generators,centrifugal compressors,turboexpanders, blowers,and pumps.Among these,high-power motor-compressors have become a major application field for AMBs in the oil&gas industry over the past two decades.
Several configurations exist for motor-compressors,from standalone to hermetically sealed,and each configura-tion involves a different level of integration of the two machines.So too AMB system configurations vary,in system complexity and design challenges.This paper discusses the main motor-compressor configurations with their associat-ed challenges and benefits.The examples draw from more than20years of design,manufacturing and service experi-ence of high-power motor-compressors.Finally,the design framework and technical considerations driving the devel-opment of a new family of hermetically sealed motor-compressors are discussed in detail.
Keywords：Active Magnetic Bearing,Motor,Compressor,Integrated Motor-compressor,Vessel Compressor Line, Oil&Gas
DOI:10.16492/j.fjjs.2019.06.0014
Nomenclature
AMB MC VCL Active magnetic bearing Motor-compressor Vessel compressorline
0Introduction
Over the past two decades,high-power motor-compres-sors for the oil&gas industry have represented a major field of application for active magnetic bearing(AMB)systems (Jayawant,1997,Kasarda,2000,Kummlee,et al,2000,and Sietinga,et al,2008)[1-4].Challenging operating conditions, gas compositions and operating environments have continual-ly set new requirements for motor-compressor applications, driving the advancement of AMB technology(Masala,et al, 2013,Swann et al,2014,Al-Aidarous&Shultz,2014,Guo,et al,2016)[5-8].Subsea and sealed motor-compressors oper-ating with sour gas represent some of the leading-edge appli-cations.At the same time,the deployment and innovation of AMB product in the oil&gas and energy industries also drives the development of international standards for AMB-equipped turbomachinery(ISO,2002,2004,2006, 2012,and API,2014)[9-13].
Based on the combined experience of authors’compa-nies in AMB and compressor design and operation,this paperaddresses some of the key technical challenges,solu-tions and benefits associated with the application of AMB
*Fund Program：National Key R&D Program of China（Grant No.2018YFB0606105）
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systems in motor-compressors.Special focus is put on high-power integrated motor-compressors.The design scheme and technical considerations driving the develop-ment of a new hermetically sealed motor-compressor equipped with an AMB system are also discussed in detail.
1Levels of Complexity
AMB systems are typically applied to single or multiple shaft compressor trains with direct-drive configurations and variable speed ranges.The presence of a gearbox and its asso-ciated lubrication system normally leads to the use of con-ventional oil-film bearings for both the driver and the driven machine.
In a direct-drive centrifugal compressor configuration,the driver can be either a gas or steam turbine or an electric motor.Depending on the type of driver and the level of inte-gration between the driver and driven machine,different lev-els of complexity exist for the AMB system (Figure 1).
1.1Turbine-driven Centrifugal Compressors
The least complex configuration is a standalone centrif-ugal compressor supported by an AMB system and driven by a steam or gas turbine running on conventional fluid film bearings.This hybrid bearing solutionis popular among large OEMs and end-users in Russia and has been successfully ap-plied in more than a hundred high-power centrifugal com-pressors for pipeline or boosting service.A lubrication sys-tem is still required for the turbine bearings,but the applica-tion of AMBs on the compressor reduces the overall equip-ment volume and associated maintenance.The increased op-erating flexibility gained with the active magnetic bearings and the capacity to start the machine within a few minutes (normally less than two),and with limited or no operators on-site,represent additional benefits of this configuration for remote locations and extreme ambient temperature condi-tions.
An 18MW gas turbine-driven,AMB-equipped compres-sor (Figure 2)that has been in operation since 2013has an outstanding track record of 98%availability.The AMB hard-ware is fitted inside the compressor casing but separated from the process gas by dry gas seals.The AMB hardware is purged by a continuous flow of low-pressure clean air (1.2to 1.3bar-a)that serves the double purpose of evacuating the heat generated in the AMB cavities and pressurizing the AMB housing to meet the EEx-p certification requirements
for hazardous area operation.
1.2Motor-compressors
The electric-motor-driven compressor is a natural appli-cation for AMB systems,as it can fully exploit the available benefits.When the electric motor and the compressor are in separate casings and are connected with a flexible coupling,the two machines can be treated as standalone units in the AMB system design and operation.The presence of the flexi-ble coupling separates the dynamics of the two machines,and overall the AMB system ’slevel of complexity is equiva-lent to the complexity in astandalone compressor driven by a steam or gas turbine.In the simplest configuration for the motor-driven compressor,each machine has an independent,separately housed AMB controller.
An increased level of complexity is normally experi-enced when the AMB controllers are housed in a single en-closure and some auxiliary systems,such as the UPS and transformers,are shared by the AMB controllers of the two machines.The benefits,however,in terms of footprint reduc-tion and overall cost reduction justifies the manageable in-crease of complexity deriving from the integration effort.
The level of complexity is further increased when the AMB controls of the two machines are integrated into a sin-gle AMB controller.In a 23MW motor-compressor train-which has been in operation since 1998(Figure 3),both the high-speed synchronous motor with exciter and high-speed centrifugal compressor are equipped with active magnetic bearings.The AMB system has 11control axes,six for the motor and five for the compressor,and a single AMB control-ler managesthe entire train dynamics,as well as the data stor-age and communication functions.On high-power mo-tor-compressors like this,having a single AMB controller im-proves reliability while reducing the footprint and both capi-tal and maintenance
costs.
Fig.1
Levels of complexity for AMB-equipped compressors,with the bottom level being the least complex
Fig.2AMB-equipped compressor driven by a gas
turbine
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Due to the development or customization costs,the sin-gle,integrated controller design is typically only justified
when a high number of units (10or more)with same charac-teristics are required.With a limited number of units,or where some degree of customization of the electrical interfac-es is required,a system integration at enclosure and auxiliary system level only is more appropriate.Having separate AMB controllers provides customers the opportunity to run the two machines independently and in different locations,for in-stance at the compressor and motor vendor workshops dur-ing internal factory acceptance tests and rotor balancing.This becomes a key factor in projects with short lead times.Another advantage of using separate controllers in a single enclosure is the opportunity to fit a spare AMB controller in-to the enclosure (Figure 4).When maintenance of one con-troller is required,the spare controller can readily replace the out-of-service controller,reducing machine downtime and in-creasing overall availability of the unit,as compared to a con-figuration with a single AMB controller for the entire mo-tor-compressor.
1.3Hermetically Sealed Motor-compressors
Within the larger category of motor-driven compres-sors,the ability of AMBs to operate within a pressurized gas environment has allowed the development of hermetically sealed motor-compressor units (Figure 5),where the entire shaft and the AMB hardware are immersed in the process gas and surrounded by the compressor and motor casing.The compressor and motor may be designed with a common shaft or separate shafts connected through rigid or flexible couplings.
On hermetically sealed (also known as integrated)mo-tor-compressor units,compressor configurations with two,three or four radial AMBs have been developed over the past
two decades to meet specific compressor bundle,power and rotordynamic performance requirements.Typically,four radi-al bearings are used on motor-compressor configurations with the compressor and motor shafts connected by a flexi-ble coupling.A three-bearing configuration is typically used on split compressor and motor shafts connected with a rigid coupling.Two radial bearings are typically used when motor and compressor are on a single shaft.
Machine configurations may also differ in the number of compressor stages (i.e.,single or multiple stage),position of the thrust AMB (i.e.,between the two machines or on the compressor non-drive-end),or machine orientation (i.e.,ver-tical or horizontal).
Among AMB designs for hermetically sealed mo-tor-compressors,the canned AMB solution (Figure 6)is the summit of complexity,the reasons for which will be further addressed in the subsequent sections.
Fig.3
23MW motor-compressor supported by an 11-axis AMB
system
Fig.4
AMB enclosure with three AMB controllers,two active and one
spare
Fig.5Hermetically sealed AMB
motor-compressor
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2Design Considerations for Integrated Motor-compressors
A schematic of a typical hermetically sealed motor-com-pressor configuration with a single shaft is shown in Figure 7(Al-Aidarous&Shultz,2014).There are two radial bearings and one axial bearing for the whole machine,and the shaft seals have been eliminated.
Because the machine casing inherently creates a seal,gas leakages to the external environment are eliminated and no dry gas seals are required between the impellers and the AMB hardware.This has a positive effect on the reliability and availability of the machine.The elimination of dry gas seals also reduces the bearing span,making itpossible to in-crease the speed of the machine or the number of impellers to achieve a higher power density and higher efficiencyfor the motor-compressor.
Such performance improvements,however,are normal-ly associated with a higher complexity of motor-compressor and AMB system design,at both the machine or system level.At the machine level,complexity is determined by the expo-sure of the AMB stator and rotor parts to the pressurized gas environment.Exposure increases windage losses and re-quires cooling flows to evacuate the heat produced in the AMB cavities.The compatibility of stator and rotor materials with the process gas,throughout the entire operating life of the machine,must also be evaluated.At the system level,complexity is determined by the integration of the secondary cooling flows of the two machines and their effect on the axi-al loads of the machine.When the motor and compressor are on the same shaft,or rigidly coupled shafts,rotordynamic challenges also increase.
Materials used for the mechanical and electrical AMB components inside the machine and in contact with the gas are typically compatible with clean gas mixtures of hydrocar-bons,free of acidic components,chlorides and contaminants.If the gas is a clean mixture of hydrocarbons,standard,open AMB design construction can be used,with AMB stator and sensor parts directly exposed to the process gas.
When the process gas is sour or contains chlorides or contaminants not compatible with standard mechanical and electrical hardware materials,a canned AMB solution is pref-erable.In a canned AMB,a thin metallic lining,compatible with the process gas,separates and protects the sensitive AMB stator parts from the process gas aggression (Figure 8).
The canning completely protects the bearing electrical wind-ings,conductors,and wiring splices from contamination from the H2S and other liquid contaminants.In applications with sour or acid gas with possible liquid water content,cor-rosion resistant materials,as dictated by NACE MR0175/ISO15156Standards,are normally used for rotor laminations subject to high stresses during assembly and operation.
In addition,motor-compressors pumping corrosive and contaminated gas will benefit from corrosion resistant and fouling resistant auxiliary bearing systems.All materials in the auxiliary bearings must be corrosion resistant.For resis-tance to particulate fouling,such as sand ingress,a bushing type auxiliary bearings with no rolling elements may be ad-opted (Figure 9),as rolling elements may seize when particu-late fouling is present.
At the machine level,canned AMBs docreate some inte-gration challenges.First,the canned AMB construction and the materials compatible with the sour gas entail a degrada-tion of the static and dynamic load performances of the bear-ings.This normally requires larger bearing sizes and a longer bearing span to compensate for the reduced magnetic flux densities,resulting in more challenging rotordynamics de-sign,especially on flexible rotors.
Fig.6Canned AMB for sealed
MC
Fig.7
Hermetically sealed AMB motor-compressor.(Al-Aidarous &Shultz,
2014)[7]
Fig.8Canned AMB
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Limitations on allowable stresses of the AMB rotor
components (i.e.,the rotor laminations and thrust collar)set limits on the rotating speed of the machine or require special design of the components to reduce the level of stresses to within acceptable limits.For the reasons stated above,when corrosion resistant materials are used for the AMB rotor parts,a vertical rotor machines provide some advantages compared to horizontal axis machines,because the static ra-dial loads due to the rotor weight are eliminated and the over-all diameter and axial length of the bearings can be reduced.
Further complexities involve the cable routing and inter-faces with the external connectors of the machine.
For this reason,while canned AMBs have been quali-fied and in continuous operation for more than 10years,they represent the summit of complexity for AMB motor-com-pressor e of this design should be carefully considered and balanced against alternative solutions.
3VCL Integrated AMB Motor-compressor
A new family of high-power hermetically sealed mo-tor-compressors,the Vessel Compressor Line (VCL),is now in development for pipeline compressor applications in oil &gas (Figure 10).
3.1Machine Design
The VCL unit comprises a compressor and a high-speed electric motor,each equipped with an AMB system and cool-ing system.The motor shaft and the compressor shaft is con-nected by a flexible coupling.A typical single-layer configu-ration for pipeline compressors,where the pressurized cas-ings are assembled to the base to form a single skid,has been adopted.
The compressor is designed as a cylinder structure with vertical split designs at each end.The compressor casing is connected to the pressurized casing of the motor at the drive end by a flange,fastened by bolts and positioned by rabbets,to form an integrated pressurized casing.At the non-drive end,the flange and the casing body are installed with a clasp ring,which can effectively reduce the weight of the machine unit and save on material costs.
The sealed cooling systems are arranged inside the skid.The cooling gas is extracted from the outlet of the first stage impeller of the compressor,which,by filtration,provides the cooling to the stators and rotors of the magnetic bearing sys-tems and to the high-speed motor to ensure the normal opera-tion of the machine unit.
The compressor adopts upper inlet and upper outlet de-sign configuration,where the inlet flange and the outlet flange of the compressor are directly arranged on the top of the pressurized casing.
In the structural design of the machine unit,CFD analy-sis on the inlet volute and outlet volute is conducted to en-sure even distributions of gas flows in inlet and outlet flow channels for improved efficiency of the unit.The calcula-tions and analysis on the strength of the impellers,rotor un-balance response,stability of the centrifugal compressor ro-tor-bearing-seal system,and torsional vibrations of the mo-tor-compressor train are performed with advanced software to ensure the stable and reliable operation of the machine unit.
Figure 11shows a schematic of the VCL compressor and AMB design.The compressor comprises the stator (pres-surized casing,inner casing,diaphragms,seals,balance drum seal,end flanges,etc.),rotor (main shaft,impellers,spacer sleeves,balance drum,rotor sleeves,half coupling,etc.),and magnetic bearing system.The compressor AMB hardware consists of two radial AMBs,one axial AMB,one radial/axial auxiliary bearing,and one radial auxiliary bear-ing,all with the requisite position sensors,temperature sen-sors,and speed sensors.The motor AMB hardware has the same components except for the axial AMB.The compressor ’s axial magnetic bearing is a double acting type thrust bear-ing located at non-drive end of the compressor.
The main mechanical sub-assemblies of the bearing sys-tems are the actuator stator assemblies and the rotor assem-blies located at the drive end and the non-drive end of the compressor and the motor.The mechanical system also in-cludes the auxiliary bearing system that supports the rotors during standstill condition or during a rotor landing
event.
Fig.9Bushing-type corrosion-resistant auxiliary bearings
Fig.10VCL integrated
motor-compressor
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3.2AMB Solutions
Given the size and design pressure of the machine,the following key technical issues will be addressed in the appli-cation of the magnetic bearings:
Due to the larger component and surfaces,small differ-ences between actual and predicted internal pressures may re-sult in high static and dynamic loads.Therefore,the internal flows and pressure distribution for the integrated machines must be properly evaluated for different operating points, and sensitivity analysis must be conducted.Adequate safety margins must be guaranteed by the thrust bearings.Alterna-tively,the customer can adopt an automatic thrust balancing system for the machine by controlling the pressure drop
across the balance line with a valve.
When a flexible coupling between the motor and com-pressor is present,the coupling will be immersed in the high-pressure process gas.The coupling must be designed to reduce windage and turbulence losses.High turbulence from the coupling can result in high excitation of the rotor and im-pact on the dynamic performances of the machine.Coupling designs other than disc and diaphragm type may be consid-ered for this purpose.
To reduce the windage losses,the magnetic bearing and auxiliary bearing air gaps are to be increased10%to20% compared to the AMB operating at ambient pressure.Second-ary cooling flow distributions must be evaluated for different operating conditions to guarantee that enough cooling flow is provided to the AMB cavities.
Experience on large compressors operating at high pres-sure and compression ratios has shown that uneven pressure distribution at the inlet volute and scroll of the compressor can generate high static radial loads.Such loads can be com-parable to or higher than rotor weight loads and must be properly estimated by the compressor vendor(possibly by means of CFD analysis)for normal operating and off-design conditions.
High shaft power increases the rotor mass and applied forces,requiring larger active magnetic bearings and auxilia-ry bearings to manage the large static and dynamic loads. The radial and axial dynamic load capacity of the magnetic bearings is dependent on the amplifier power rating.If high dynamic loads are predicted,an AMB controller with a pow-er rating up to600V/60A(Figure12)can be selected.
EEx-d penetrators for AMBs are available for the inte-grated motor-compressor.This solution is generally more ex-pensive than the EEx-p solution typically adopted for stand-alone machines with AMBs operating at quasi-ambient pres-sure.Alternative penetrators and protection schemes,suit-able for operation in the hazardous area identified for the ma-chine,can be applied but must be weighed against other fac-tors,including price,delivery time,and certification require-ments.
High performance hybrid auxiliary bearings solution,ro-tor mounted,are typically not suitable for high-pressure gas applications such as hermetically sealed motor-compressors, due to associated windage losses and dragging torques on the rolling bearings.For this reason stator mounted rolling bear-ings or bushing type auxiliary bearings are normally used.
Testing of the motor and compressor as standalone units may require special equipment and consideration of the me-chanical interfaces,cooling system and rotordynamics.Con-versely on standalone motor and compressor the two ma-chines can be tested independently in a configuration more closely representative of the final assembled condition.
Due to the radial clearances required in the auxiliary bearing system,conventional seals in the compressor require larger than normal clearances.The increased clearances can lead to decreased compressor efficiency.As an optional solu-tion,brush seal technology may be integrated with the com-pressor ing brush seals throughout the compressor can increase compressor efficiency by2to3points,due to the tighter clearances and decreased leakage.
Fig.11VCL compressor and AMB
design
(a)390V/28A AMB Controller
(b)600V/60A AMB Controller
Fig.12AMB controllers for
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4Conclusions
Different configurations for motor-compressors equipped with AMB systems,from standalone to hermetically sealed machines,have found their applications in industry.Each configuration involves a different level of integration of the two machines and entails increasing system complexity and design challenges.Starting with standalone centrifugal com-pressor supported by an AMB system as the least complex configuration,the level of complexity of AMB motor-com-pressors is increased when AMB controllers are housed in a single enclosure and some auxiliary systems,such as the UPS and transformers,are shared by the AMB controllers for two machines.The level of complexity is further in-creased when the AMB controls of the two machines are inte-grated into a single AMB controller.At last,the hermetically sealed motor-compressors equipped with canned AMB in ap-plications with sour or acid gas or with possible liquid water content,corrosion resistant materials,represent the summit of complexity for AMB motor-compressor applications The optimized design of the machine configuration, structure,cooling system,and magnetic bearing systems,has been conducted in the design framework and overall techni-cal considerations driving the development of a new family of hermetically sealed motor-compressors,VCL integrated motor-compressors,to achieve high compressor performance and efficiency.The special attentions to AMB systems shall be paid in such high power motor-compressor units as ad-dressed in detail in the paper in terms of magnetic bearing de-sign,auxiliary bearing design,controllers,couplings,penetra-tors and seals.
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700kW磁悬浮离心鼓风机转子动力学设计与测试/沙宏磊俞天野何毅张志华
摘要：磁悬浮轴承以其无摩擦、不需润滑的特点，成为离心鼓风机的最佳方案之一。

磁悬浮鼓风机的行业标准和工业需求，对磁悬浮轴承的设计提出了较高的要求。

针对鼓风机的特点，设计了5自由度主动控制的磁悬浮轴承，通过转子动力学计算分析了转子的动力学特性，通过系统辨识获得了准确的系统模型，通过主动控制达到了良好的控制效果。

实验测量表明，采用磁悬浮轴承支承的高速离心鼓风机的性能完全达到了工业要求。

非轴对称端壁造型对叶片端壁综合传热特性的影响/祝培源陶志姚韵嘉宋立明李军
摘要：结合双控制型线端壁造型方法，建立了带有槽缝射流和非轴对称端壁造型的燃气透平叶片端壁的数值研究模型。

在验证数值方法正确性的基础上，开展了不同非轴对称端壁设计对叶片端壁综合传热性能影响的研究。

结果表明，不同的非轴对称端壁造型会对所研究的大转折角叶片的二次流结构产生不同的影响。

在叶栅通道前部造型会降低槽缝射流对端壁前部的气膜冷却作用，而叶栅通道后部的端壁造型能够有效提高整个端壁的气膜冷却作用。

对传热特性而言，在叶栅通道前部进行端壁造型能够有效降低通道前部的端壁传热强度，在端壁后部造型可以减小通道中后部的端壁传热强度。

综合考虑冷却和传热特性，在叶栅通道后部进行非轴对称端壁造型能够有效提高端壁的综合传热性能，降低热负荷，更加有利于叶片端壁的热防护。

某声学风洞轴流风扇设计/屈晓力余永生吕金磊张文清
摘要：采用试验研究的方式，对某声学风洞的轴流风扇性能进行验证。

该风扇采用了任意涡设计方法以达到所要求的气动指标要求；通过降低风扇转速、合理匹配桨叶-止旋片数目、调整桨叶-止旋片间距及止旋片后掠等方式，降低风扇噪声。

风扇的性能测试结果表明，风扇满足了风洞试验段的最高风速要求，当风扇转速为650r/min时，风扇的级间效率达到90%、风扇段气动效率达到84%；当试验段风速达到70m/s时，风扇出口的声压级为114dB。

该风扇的研制，表明采用任意涡风扇设计方法结合上述提到的降噪措施，能够设计出气动效率高、风扇噪声低的风扇系统，可很好的运用于其他的声学风洞设计中。

集成式透平压缩机在海底压缩的应用/熊文凌Gabriel Franci
摘要：介绍了集成式压缩机的历史、起源、技术优势及在海底压缩系统的进展。

该压缩机不含润滑油系统和轴端密封系统，因此可靠性及可用性高，停机和检修时间短；转速调节范围宽，因此运行范围广阔；能够快速响应变化的运行条件；运行周期成本低；环境中性，运行时不影响环境也不受环境影响；整体性价比高，非常适合于海底压缩应用。

2015年9月，第一台海底压缩机在挪威Åsgard油气田海底成功运行（第一个达到技术成熟度/TRL7的海底压缩系统），标志着集成式压缩机发展的一个新时代的到来。

刀具磨损状态识别与智能监测方法综述/董江磊代月帮雍建华李宏坤
摘要：刀具作为机械生产中机床加工所使用的关键执行件，其磨损状态识别和智能监测技术对于提高生产效益具有重要意义。

传统的刀具磨损信号分析都是利用经验方法分解提取出信号特征来对信号特征进行解析，无法实现智能化监测。

随着大数据时代的到来和深度学习算法的不断优化和改进，诸如卷积神经网络、深度置信网络、稀疏自动编码器等算法的应用越来越广泛，因此可以利用大数据平台，将深度学习算法与现代传感器技术、计算机技术、信号采集存储技术相结合，实现刀具磨损状态识别和智能监测。

大数据技术和人工智能技术在机械工业生产中的结合应用是当今时代的必然发展趋势。

离心压缩机组底座模态分析技术研究/李洪臣张程张忠伟太兴宇张驰
摘要：本文对某离心压缩机组的底座进行了固有频率分析，阐述了在不同安装条件下，底座固有频率的差异。

首先建立机壳底座三维模型，模型导入ANSYS Workbench进行有限元网格剖分，将电机、齿轮箱和压缩机等效为质量点施加在相应的支腿位置上，根据不同的约束形式，分别就试车工况和实际运行工况进行频率分析以及Campbell判别，通过进一步的优化分析，得到约束形式对底座频率的影响，进而避免了压缩机组运行在全转速范围内的共振风险。

装备主动磁力轴承的大功率电机压缩机机组的应用与配置/郭增林王玉旌Richard Shultz Andrea Masala
摘要：主动磁力轴承（AMB）由于其具有的高可靠性和高可用性，已在高转速和高性能的涡轮机械中得到日益广泛的应用。

石油天然气和能源工业代表了磁力轴承产品的核心市场，在过去三十多年中一直处于应用和创新的前沿，并推动了磁力轴承涡轮机械国际标准的制定。

装备磁力轴承的典型机械包括了电机和发电机、离心式压缩机、涡轮膨胀机、鼓风机和泵。

其中，大功率电机压缩机在近二十年来已成为磁力轴承在油气工业中的主要应用领域。

磁力轴承电机压缩机具有多种不同的配置设计，从分体机到封装式一体机，每种配置涉及到两台机器的不同级别的集成程度。

同时，与之相配套的磁力轴承系统的配置复杂性与设计挑战性也不相同。

本文讨论了装备磁力轴承的电机与压缩机的主要配置设计及其相关的设计挑战性和该设计所具有的优点。

应用实例来自于近二十多年来的大功率电机压缩机机组的设计、制造和服务经验。

文中最后详细讨论了一种新型的封装式电机压缩机一体机的设计框架和技术考虑。

离心压缩机轴系悬臂振型对振动影响的实例分析/李品威杨国林杨杰霖史家杰李健伟
摘要：离心压缩机组在临近工作转速时出现振动波动，排除了对中不好、轴瓦间隙超差和不平衡等问题后，找出原因为联轴器质量过重及联轴器重心距离临近的压缩机支撑轴承过远。

当外激励源的质量和力矩较大时，可以在很低转速下激发出轴系的悬臂振型，当该振型的固有频率与工作转速的转率比较接近时，就会使离心压缩机组在工作转速附近振动过大且无法保持稳定。

结合现场实例分析了联轴器在改造前后的轴系无阻尼振型特征和不平衡响应特征。

通过对联轴器的改造，减少了联轴器重心质量及改变了联轴器重心位置，即减少了悬臂振型对机组轴系振型的影响，使压缩机的悬臂振型固有频率与工频的隔离裕度满足了API要求，压缩机振动恢复正常。