罗茨风机属于容积式回转风机，真空变压吸附制氧装置（VPSA-O2）普遍使用罗茨鼓风机和罗茨真空泵作为产氧过程气体输送的动力设备。实际生产中，罗茨风机在压力频繁突变的恶劣工况下运行，因而频繁发生振动超标的故障，引发制氧装置全面停车，对生产稳定造成严重影响。鉴于此，对制氧装置罗茨风机振动故障发生的原因进行查找分析，对维修技术改进进行摸索，从而有效减少振动故障的发生，保障生产长期稳定进行。

　　Roots blower belongs to the positive displacement rotary fan, and the vacuum pressure swing adsorption oxygen production unit (VPSA-O2) commonly uses Roots blower and Roots vacuum pump as power equipment for gas transportation in the oxygen production process. In actual production, Roots blowers operate under harsh conditions of frequent pressure fluctuations, resulting in frequent failures of vibration exceeding the standard, causing the oxygen production unit to shut down completely and seriously affecting production stability. In view of this, the causes of vibration faults in the Roots blower of the oxygen production unit were investigated and analyzed, and maintenance technology improvements were explored to effectively reduce the occurrence of vibration faults and ensure long-term stable production.

　　罗茨风机因其对生产工艺适应性强的优点，成为真空变压吸附制氧装置中使用最广泛的机械设备。产氧过程中，罗茨鼓风机和罗茨真空泵分别起到正压输送原料空气和真空解吸抽除废气的作用，需在空载压力到满载压力的状态下交替循环运行，极不稳定的负荷导致冲击大，罗茨风机频繁发生振动超标引发联锁停机的故障，对制氧装置作业率和下游工序生产组织影响严重。因此，只有查找罗茨风机振动故障根源，实施有效的措施加以改进，从而减少故障的发生，方能保障制氧装置的长期稳定运行。

　　The Roots blower has become the most widely used mechanical equipment in vacuum pressure swing adsorption oxygen production units due to its strong adaptability to production processes. During the oxygen production process, the Roots blower and Roots vacuum pump play the roles of positive pressure conveying of raw air and vacuum desorption and extraction of exhaust gas, respectively. They need to operate alternately in a cycle from no-load pressure to full load pressure. The extremely unstable load leads to large impact, and the Roots blower frequently experiences vibration exceeding the standard, causing interlock shutdown faults, which seriously affect the operation rate of the oxygen production unit and the production organization of downstream processes. Therefore, only by identifying the root cause of vibration faults in Roots blowers, implementing effective measures to improve them, and reducing the occurrence of faults, can the long-term stable operation of oxygen production equipment be guaranteed.

　　真空变压吸附制氧装置（VPSA-O2）工艺原理

　　Process principle of vacuum pressure swing adsorption oxygen production unit (VPSA-O2)

　　VPSA制氧是利用变压吸附法，以空气为原料制取氧气的一种新型常温气体分离技术。该法是基于分子筛对空气中的氧、氮组分进行选择性吸附而使空气分离获得氧气，通常称为真空变压吸附制氧法。当空气经过压缩、通过装有分子筛的吸附塔时，氮气分子优先被吸附，氧分子留在气相中，得到氧气。吸附达到平衡时，利用减压或抽真空将分子筛表面所吸附的氮分子驱除，恢复分子筛的吸附能力[1]。为了连续提供氧气，装置通常设置两个或两个以上的吸附塔，一个塔吸附产氧，另一个塔解吸。真空变压吸附制氧原理如图1所示。

　　VPSA oxygen production is a new ambient temperature gas separation technology that uses pressure swing adsorption to produce oxygen from air as raw material. This method is based on the selective adsorption of oxygen and nitrogen components in the air by molecular sieves to separate the air and obtain oxygen, commonly known as vacuum pressure swing adsorption oxygen production method. When air is compressed and passes through an adsorption tower equipped with molecular sieves, nitrogen molecules are preferentially adsorbed, while oxygen molecules remain in the gas phase to obtain oxygen. When adsorption reaches equilibrium, the nitrogen molecules adsorbed on the surface of the molecular sieve are removed by reducing pressure or vacuuming, restoring the adsorption capacity of the molecular sieve. In order to continuously provide oxygen, the device usually sets up two or more adsorption towers, with one tower adsorbing to produce oxygen and the other tower desorbing. The principle of vacuum pressure swing adsorption oxygen production is shown in Figure 1.

　　我司拥有两套真空变压吸附制氧装置，均采用五塔流程，型号为ZO-7500/80，由国内同一公司设计建造，为艾萨炉、转炉、阳极炉提供冶炼用氧气。装置由罗茨鼓风机、罗茨真空泵、吸附器、仪表控制、电气控制、切换阀门、仪表空气等7个部分和自控系统组成[2]。变压吸附法产氧过程分为吸附、解吸、顺向放压、逆向放压、均压5个阶段，每个塔不断循环交替，吸附阶段由罗茨鼓风机完成正压空气输送，解吸阶段由罗茨真空泵完成废气的负压抽送，由于产氧的5个阶段塔内所需压力不同，罗茨鼓风机和罗茨真空泵工作压力通过16个气动阀门自动切换来控制。罗茨鼓风机压力在0～49 kPa区间重复波动，罗茨真空泵压力在-55～0 kPa区间重复波动，波动周期均为1 min[3]。

　　Our company has two sets of vacuum pressure swing adsorption oxygen production units, both using a five tower process, model ZO-7500/80, designed and built by the same domestic company, providing oxygen for smelting in Isa furnaces, converters, and anode furnaces. The device consists of seven parts including Roots blower, Roots vacuum pump, adsorber, instrument control, electrical control, switching valve, instrument air, and an automatic control system. The process of oxygen production by pressure swing adsorption method is divided into five stages: adsorption, desorption, forward pressure release, reverse pressure release, and pressure equalization. Each tower continuously cycles and alternates. The adsorption stage is completed by a Roots blower for positive pressure air transportation, and the desorption stage is completed by a Roots vacuum pump for negative pressure pumping of exhaust gas. Due to the different required pressures inside the tower during the five stages of oxygen production, the working pressures of the Roots blower and Roots vacuum pump are automatically switched through 16 pneumatic valves to control. The pressure of the Roots blower fluctuates repeatedly in the range of 0-49 kPa, and the pressure of the Roots vacuum pump fluctuates repeatedly in the range of -55 to 0 kPa, with a fluctuation period of 1 minute [3].

　　2  罗茨风机振动故障情况

　　Vibration fault of Roots blower 2

　　罗茨风机系属容积回转式风机，属于旋转式机械。我司两套VPSA制氧变压吸附装置分别配置2台大型罗茨鼓风机和2台大型罗茨真空泵，总数共计8台，是制氧生产最主要的动力设备。罗茨鼓风机和罗茨真空泵技术参数如表1所示。

　　The Roots blower system is a volumetric rotary fan and belongs to rotary machinery. Our two VPSA oxygen production pressure swing adsorption units are equipped with 2 large Roots blowers and 2 large Roots vacuum pumps, totaling 8 units, which are the main power equipment for oxygen production. The technical parameters of Roots blower and Roots vacuum pump are shown in Table 1.

　　两套变压吸附制氧装置前后间隔两年时间建成，投用后工艺指标均能达到技术要求。8台罗茨风机在交变载荷下运行，其振动值并不是一个稳定值，一般在4～9.5 mm/s波动，只要其最高值和最低值相对稳定即视为正常。但在运行7 200 h后，罗茨鼓风机和罗茨真空泵相继出现振动值超标的故障，这远低于JB/T 8941.1-2014《一般用途罗茨鼓风机 第1部分：技术条件》[3]中要求的第一次大修前安全运行时间不少于15 000 h的标准。经检查，发现以下两种情况：

　　Two sets of pressure swing adsorption oxygen production units were built with a two-year interval between them, and after being put into use, the process indicators can meet the technical requirements. Eight Roots blowers operate under alternating loads, and their vibration values are not stable, usually fluctuating between 4-9.5 mm/s. As long as their highest and lowest values are relatively stable, it is considered normal. But after running for 7200 hours, the Roots blower and Roots vacuum pump successively experienced vibration value exceeding the standard, which is far below the standard of no less than 15000 hours of safe operation time before the first major overhaul required in JB/T 8941.1-2014 "General purpose Roots blower Part 1: Technical conditions" [3]. After inspection, the following two situations were found:

　　第一，风机突发振动联锁跳机。设备在运行振动、温度、压力等均较平稳的状态下，突然毫无征兆瞬间超过20 mm/s的振动联锁而跳机，人工无法盘动转子，从进气口检查两叶轮在某个角度咬死并有碰撞的痕迹。

　　Firstly, the fan suddenly vibrates and interlocks to trip. The equipment suddenly exceeded 20 mm/s vibration interlock without any warning while operating in a relatively stable state of vibration, temperature, pressure, etc., causing the machine to trip. The rotor could not be manually rotated, and the two impellers were checked from the air inlet for biting and collision marks at a certain angle.

　　第二，风机振动值持续升高。设备在运行中温度、压力等均较平稳的状态下，振动值呈小幅持续上升态势，直至触发报警值，停机后能够正常盘车，从进气口检查两叶轮各间隙，除在45°时间隙偏小外，其他位置间隙均符合技术要求。

　　Secondly, the vibration value of the fan continues to increase. When the temperature and pressure of the equipment are relatively stable during operation, the vibration value shows a slight and continuous increase until the alarm value is triggered. After shutdown, the equipment can be turned normally. The clearance between the two impellers is checked from the air inlet, and except for a small clearance at 45 °, the clearance at other positions meets the technical requirements.

　　在拆解风机后发现，第一种故障情况为同步齿轮轮毂发生松动，主、从动齿轮发生错位使两叶轮相对啮合位置改变而导致相撞；第二种情况为衬套与轴颈出现松动，衬套内孔磨损后晃动冲击不断加重导致振动值持续升高。按设备使用说明书中的相关技术要求，前述故障需要对风机进行完全解体，在确认轴承没有损坏的前提下一般通过更换密衬套和调整主、从动齿轮相对位置并重新铰孔定位的方法处理。修理后，风机在试机和初期运行均正常，超过6个月后又会不定时发生相同故障，需要5～8天的维修时间，以至于设备处于反复不停的修理当中。故障处理期间只能被迫采取运行半套装置的方式降负荷生产，对产氧经济指标和下游生产组织造成严重影响，同时在高噪声环境下进行设备抢修作业，对维修人员身心健康也造成了一定影响。

　　After disassembling the fan, it was found that the first type of malfunction was the loosening of the synchronous gear hub, which caused the displacement of the main and driven gears, resulting in a change in the relative meshing position of the two impellers and causing a collision; The second scenario is when the bushing and shaft neck become loose, and the inner hole of the bushing wears out, causing the shaking and impact to increase continuously, resulting in a continuous increase in vibration values. According to the relevant technical requirements in the equipment manual, the aforementioned malfunction requires complete disassembly of the fan. Generally, after confirming that the bearings are not damaged, the problem can be resolved by replacing the bushing, adjusting the relative position of the main and driven gears, and repositioning the hinge holes. After repair, the fan operated normally during the trial run and initial operation. However, after more than 6 months, the same malfunction may occur irregularly, requiring 5-8 days of maintenance time, resulting in the equipment being repeatedly repaired. During the fault handling period, only half of the equipment was forced to operate to reduce the load production, which had a serious impact on the oxygen production economic indicators and downstream production organizations. At the same time, equipment repair operations were carried out in a high noise environment, which also had a certain impact on the physical and mental health of maintenance personnel.

　　3  罗茨风机振动故障维修改进

　　Repair and improvement of vibration faults in Roots blower

　　根据ARMH型罗茨风机结构，其装配顺序为叶轮穿入机壳→前后墙板安装→涨圈及衬套安装→轴承座安装→轴承安装→同步齿轮安装→两叶轮间隙调整→同步齿轮定位→甩油盘及润滑油管安装→主、副油箱安装→润滑油泵安装→油冷却器安装→联轴器安装。在风机使用技术说明中，仅对叶轮与机壳间隙、叶轮与墙板间隙、两叶轮“啮合”间隙作出明确的数值要求，而其他装配环节只用文字进行了一般性说明，没有具体指标[4]。在多次对风机振动故障的处理中，分析过程中的现象，以采取措施改进装配质量。

　　According to the structure of the ARMH Roots blower, the assembly sequence is as follows: impeller insertion into the casing → installation of front and rear wall panels → installation of expansion rings and bushings → installation of bearing seats → installation of bearings → installation of synchronous gears → adjustment of the gap between the two impellers → positioning of synchronous gears → installation of oil slingers and lubricating oil pipes → installation of main and auxiliary oil tanks → installation of lubricating oil pumps → installation of oil coolers → installation of couplings. In the technical instructions for using the fan, only clear numerical requirements are made for the clearance between the impeller and the casing, the clearance between the impeller and the wall panel, and the "meshing" clearance between the two impellers, while other assembly processes are only described in general text without specific indicators [4]. In the handling of fan vibration faults multiple times, analyze the phenomena during the process to take measures to improve assembly quality.

　　3.1涨圈式轴封衬套松动

　　3.1 Loose ring type shaft seal liner

　　1）轴封衬套内孔与轴颈松动。衬套安装于叶轮主轴的最里处，内端面与叶轮端面紧密贴合，在其外圆加工有4个槽用于安装高弹性的涨圈，风机运行时叶轮主轴带动衬套同步旋转，涨圈则不随衬套转动，在张力作用下紧贴于墙板孔内壁，从而达到防止气体外泄的作用，其结构如图2所示。衬套前端内孔铣制有一个φ14的径向槽，在与之配合的叶轮主轴相对应位置钻孔并安装一颗φ8的圆形销，其作用是使叶轮主轴的旋转力带动密封衬套同步转动。在安装时需要将涨圈随密封衬套同时装入主轴和墙板内，为减小装配难度，密封衬套内孔与轴颈设计为间隙配合，两者之间有0.10～0.12 mm间隙，密封衬套径向槽与定位销有6 mm间隙，在此种配合条件下，密封衬套在交变强冲击载荷下运行一段时间后很容易出现晃动，并敲击定位销使其松动，对此，需要围绕减小配合间隙进行改进。

　　1) The inner hole of the shaft seal liner and the shaft neck are loose. The liner is installed at the innermost part of the impeller main shaft, with the inner end surface closely attached to the impeller end surface. There are four grooves machined on the outer circumference for installing high elasticity expansion rings. When the fan is running, the impeller main shaft drives the liner to rotate synchronously, while the expansion ring does not rotate with the liner and tightly adheres to the inner wall of the wall panel hole under tension, thereby preventing gas leakage. Its structure is shown in Figure 2. There is a radial groove with a diameter of 14 milled into the inner hole at the front end of the liner. A circular pin with a diameter of 8 is drilled and installed at the corresponding position of the impeller spindle that matches it. Its function is to drive the sealing liner to rotate synchronously with the rotational force of the impeller spindle. During installation, the expansion ring needs to be installed into both the main shaft and the wall panel along with the sealing liner. To reduce assembly difficulty, the inner hole of the sealing liner and the shaft neck are designed to have a clearance fit, with a clearance of 0.10-0.12 mm between the two. The radial groove of the sealing liner has a clearance of 6 mm with the positioning pin. Under this fitting condition, the sealing liner is prone to shaking after running under alternating strong impact loads for a period of time, and knocking the positioning pin can loosen it. Therefore, improvements need to be made to reduce the fitting clearance.

　　2）轴封衬套轴向松动。衬套在安装时内端面紧贴叶轮端面，在轴承装入后靠锁紧螺帽将压紧力传递到衬套端面，达到轴向固定的作用。如果在装配时衬套与叶轮、轴承端面与衬套贴合不严密，会造成轴向压紧力的假象，在长时间冲击振动力的作用下产生轴向间隙而导致衬套松动。因此，在安装衬套前必须把衬套两个端面和与之接触的叶轮端面的毛刺及高点彻底清除，保证接触面大于75%；轴承经加热装入主轴和轴承座过程中，应对称均匀用力敲击，通过声响辨别推入到位后，立即旋入锁紧螺母并拧紧，使衬套、轴承与叶轮端面有足够的轴向压紧力，弥补轴承冷却后的收缩量。因衬套安装时涂抹了密封胶，从衬套安装到轴承锁紧，整个装配过程应在2 h内完成，以免时间过长密封胶固化产生卡阻导致装配失败。

　　2) The shaft seal liner is loose in the axial direction. The inner end face of the liner is tightly attached to the impeller end face during installation, and after the bearing is installed, the clamping force is transmitted to the liner end face by the locking nut, achieving axial fixation. If the liner and impeller, as well as the bearing end face and liner, do not fit tightly during assembly, it will create a false impression of axial compression force, resulting in axial clearance and loosening of the liner under long-term impact vibration force. Therefore, before installing the liner, the burrs and high points on both end faces of the liner and the impeller end face in contact with it must be thoroughly removed to ensure that the contact surface is greater than 75%; During the process of heating and installing the bearing into the main shaft and bearing seat, it should be symmetrically and uniformly struck with force. After being pushed into place through sound recognition, the locking nut should be immediately screwed in and tightened to provide sufficient axial compression force between the bushing, bearing, and impeller end face, compensating for the shrinkage of the bearing after cooling. Due to the application of sealant during the installation of the liner, the entire assembly process from liner installation to bearing locking should be completed within 2 hours to avoid assembly failure caused by prolonged curing of the sealant.

　　3.2

　　three point two

　　两叶轮撞击

　　Two impellers collide

　　1）轮毂与轴颈配合接触差。拆卸同步齿轮轮毂后，轴颈表面有局部黑块及细微斑点，与之配合的内孔表面对应位置也有相同情况，这说明运行中轮毂出现了偏摆与轴颈产生拍击，引起两叶轮啮合位置发生改变而撞击，此种情况仅靠调整两同步齿轮相对位置无法彻底解决故障。轮毂与轴颈为1:20的圆锥带平键的设计，圆锥配合与圆柱配合相比最大的优点是可自动定心、配合自锁性好，装配体能获得较高精度的同轴度，但在实际制造中需要精确的锥度及良好的接触面积来保证。经使用红丹粉对合接触检查，接触面由小端向大端逐渐减少，据此可以得出，轮毂内孔锥度大于主轴锥度，轮毂安装后在大端配合面存在间隙。从轮毂与主轴配合的结构设计分析，两者锥面配合主要起到保证同步齿轮与叶轮主轴的同轴度作用，同时分担一部分旋转力，主要的旋转力靠平键来传递，将锥面配合的位置控制在两端可保定位的牢固，避免轮毂在冲击下发生瓢偏摆动。通过参考类似结构高速离心鼓风机设计，对轮毂的内锥孔进行改造，在通体内锥面长度中间车制一段长度80 mm的槽，将锥面打断去除中间无效区域，使两者接触面分布在两端，结合现场少量的锉配，可以使接触面达到75%以上。加工后的轮毂如图3所示。

　　1) Poor contact between the hub and the journal. After disassembling the synchronous gear hub, there are local black blocks and fine spots on the surface of the shaft neck, and the corresponding position of the inner hole surface that matches it also has the same situation. This indicates that the hub has deviated and the shaft neck has collided during operation, causing the meshing position of the two impellers to change and collide. This situation cannot be completely solved by adjusting the relative position of the two synchronous gears alone. The design of a 1:20 cone with flat keys for the hub and journal has the greatest advantage over cylindrical fitting in that it can automatically center and has good self-locking properties. The assembly can achieve high precision coaxiality, but in actual manufacturing, precise taper and good contact area are required to ensure it. After using red lead powder to check the mating contact, the contact surface gradually decreases from the small end to the large end. Based on this, it can be concluded that the taper of the inner hole of the hub is greater than that of the main shaft, and there is a gap on the mating surface of the large end after the hub is installed. From the structural design analysis of the fit between the wheel hub and the main shaft, the conical fit between the two mainly ensures the coaxiality of the synchronous gear and the impeller main shaft, while sharing a part of the rotational force. The main rotational force is transmitted through the flat key, and the position of the conical fit is controlled at both ends to ensure a firm positioning, avoiding the wheel hub from tilting and swinging under impact. By referring to the design of a high-speed centrifugal blower with a similar structure, the inner taper hole of the wheel hub was modified. A groove with a length of 80 mm was machined in the middle of the inner taper length of the whole body, and the taper was broken to remove the ineffective area in the middle, so that the contact surfaces of the two were distributed at both ends. Combined with a small amount of filing on site, the contact surface could reach more than 75%. The processed wheel hub is shown in Figure 3.

　　2）轮毂与轴圆锥配合过盈不够。圆锥配合的配合特征是通过相互结合的内、外圆锥规定的轴向位置来形成间隙或过盈[5-6]。加大两者装配过盈量可提高圆锥旋转传动力，减小平键的传动负荷，从而平衡传动受力。加大装配过盈量可采用对轮毂加热的方式来实现，同时也要考虑装配过紧对后期维修拆卸难度的影响；轮毂安装至轴上后靠锁紧螺帽进行轴向紧固，在用手将轮毂推入轴后，其前端面伸出轴台阶的长度为3.5 mm，进行热装会减小端面伸出轴台的长度，因此，轮毂增加的推进量在3 mm更为合适。

　　2) The interference fit between the wheel hub and the shaft cone is insufficient. The fitting feature of conical fit is to form a gap or interference through the axial position specified by the inner and outer cones that are combined with each other [5-6]. Increasing the interference fit between the two components can improve the cone rotation transmission force, reduce the transmission load of the flat key, and thus balance the transmission force. Increasing the interference fit during assembly can be achieved by heating the wheel hub, while also considering the impact of tight assembly on the difficulty of later maintenance and disassembly; After installing the wheel hub on the shaft, it is tightened axially with a locking nut. After pushing the wheel hub into the shaft by hand, the length of the front end surface protruding from the shaft step is 3.5 mm. Hot fitting will reduce the length of the end surface protruding from the shaft platform. Therefore, an increase in the pushing amount of the wheel hub by 3 mm is more appropriate.

　　4  结束语

　　4 Conclusion

　　从制氧罗茨风机投用后频繁发生振动联锁跳机故障起，经历2年多时间对故障点的持续查找、分析和维修装配方法的不断改进，最终无故障运行时间达到45 000 h以上，比JB/T 8941.1-2014《一般用途罗茨鼓风机 第1部分：技术条件》中要求的第一次大修前安全运行时间标准提高了2倍，检修原因转变为以涨圈和轴承部件的使用寿命为主，有利于设备大修的策划。从根源上增强了罗茨风机对变压吸附制氧装置特殊工况的适应性，有效促进了作业率和经济指标的提升。

　　Since the frequent occurrence of vibration interlock tripping faults in the oxygen producing Roots blower after its commissioning, after more than 2 years of continuous search, analysis, and improvement of maintenance and assembly methods, the final fault free operation time has reached over 45000 hours, which is twice the safety operation time standard required in JB/T 8941.1-2014 "General purpose Roots blower Part 1: Technical conditions" before the first major overhaul. The maintenance reason has shifted to the service life of the expansion ring and bearing components, which is conducive to the planning of equipment major repairs. From the root, the adaptability of Roots blower to the special working conditions of pressure swing adsorption oxygen production unit has been enhanced, effectively promoting the improvement of operation rate and economic indicators.

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