Reasons for vibration in the reforming hydrogen booster

This post was last edited by Zhongyuanren on 2025-12-10 at 18:47. Analysis of the Causes and Countermeasures for Excessive Vibration in Reforming Hydrogen Boosters (Recontact) Boosters. I. Introduction 1.1 Research Background and Significance In the petrochemical industry, reforming hydrogen boosters (recontact) boosters play a crucial role. It not only enables the recycling of reforming hydrogen to the recontact tank, thereby facilitating efficient reforming reactions, but also plays a key role in processes such as hydrocracking and hydrorefining by ensuring thorough mixing of feed oil with hydrogen, thus creating favorable conditions for subsequent reactions. However, when severe vibration problems occur, it poses a serious threat to production safety; it can lead to equipment damage and production disruptions, and even cause major accidents such as fires and explosions. This results in huge economic losses for the enterprise, as well as posing a serious threat to the surrounding environment and the safety of people. Therefore, it is of great practical significance to conduct an in-depth analysis of the reasons for the excessive vibration in the reforming hydrogen booster (recontact) booster and to develop effective countermeasures. II. Analysis of the reasons for excessive vibration in the hydrogen repressurization compressor 2.1 Causes of surging Surging is an abnormal vibration phenomenon that occurs in centrifugal compressors under certain operating conditions. To obtain the surge curve of a centrifugal compressor, it can be done through experiments or simulation calculations. During the tests, it is necessary to gradually reduce the inlet flow rate of the compressor at different rotational speeds, while recording parameters such as the compressor’s outlet pressure and inlet flow rate, until surge occurs in the compressor. By connecting the data corresponding to the surge points at each rotational speed, the surge limit line can be obtained; the points on this line represent the surge points. Simulation calculations involve using mathematical models of the compressor and piping system, along with numerical methods, to determine the surge curve. Surge has a very significant impact on vibration. When the compressor enters a surge condition, gas flow undergoes intense periodic oscillations, resulting in significant fluctuations in pressure and flow rate inside the compressor. Such fluctuations affect components such as impellers and diffusers, subjecting the rotor to alternating loads and causing severe vibrations. Vibration not only accelerates equipment wear and reduces the service life of components, but it can also lead to serious consequences such as damaged seals and failed bearings, and may even cause the equipment to stop operating, resulting in significant losses for production. 2.2 Causes of airflow pulsation Airflow pulsation is one of the important factors that induce mechanical vibrations in pipelines. In the reformer hydrogen booster system, gas flow pulsations are primarily caused by the compressor’s periodic suction and discharge, as well as the unstable flow of the fluid within the pipes. When the compressor speed changes or the flow rate is not adjusted properly, the air flow velocity and pressure in the pipeline also fluctuate, resulting in pulsating pressure. Under different operating conditions, the effect of airflow pulsation on vibration varies. Under low-flow conditions, compressors are prone to rotational stall; at this time, the airflow pulsation frequency is low, but the amplitude is high, which can cause low-frequency, high-amplitude vibrations in the pipes, exerting significant stress on pipe supports and connection points. Under conditions of high flow rate or high rotational speed, the frequency of airflow fluctuations increases. Although the amplitude is relatively small, these high-frequency vibrations can cause fatigue stresses in the pipes, and over time this may lead to safety issues such as pipe cracks and leaks, thereby affecting the stable operation of the entire system. 2.3 Equipment Structure and Reasons for Installation The dynamic balance of the equipment’s moving mechanism is crucial for vibration control. Taking the rotor of a reforming hydrogen booster as an example, if the center of gravity of the rotor does not coincide with its center of rotation, unbalanced forces will be generated during rotation. Even if the mass eccentricity is small, high centrifugal forces can arise at high speeds, leading to vibration. Imbalance is a common cause of failures in rotating machinery, accounting for over 75% of all failures. Basic design is equally important. The vibration characteristics of power machine foundations are related to factors such as disturbing forces, mass, stiffness, and damping. During design, the vibration characteristics under the effect of steady-state disturbances must be taken into account; by adjusting the natural frequencies of the basis set to be different from the frequency of the disturbances, resonance can be avoided. If the foundation stiffness is insufficient or the damping design is inadequate, significant vibrations will occur in the foundation during equipment operation, which are then transmitted to the equipment. The horizontal alignment during installation cannot be ignored either. If the axis of the equipment is not aligned during installation, it will create additional forces between the rotor and the bearings, resulting in unstable rotor operation and vibration. If the equipment is not installed levelly, its center of gravity will shift, resulting in unbalanced forces that further increase vibration and pose a threat to the proper operation of the equipment. III. Countermeasures to Address High Vibration in the Reformation Hydrogen Booster 3.1 Countermeasures against surge Adjusting the operating point is an effective way to avoid surge. To ensure that the operating point is to the right of the surge limit line, this can be achieved by adjusting parameters such as inlet flow rate and outlet pressure, so that the compressor operates under stable conditions at all times. When the inlet flow rate is too low, the anti-surge valve can be opened appropriately to increase the backflow and maintain flow balance inside the compressor. Conducting performance tests is crucial for preventing surge. Through experiments, the surge curve of the compressor can be accurately obtained, allowing for an understanding of the surge boundaries at different speeds and flow rates. After the installation or modification of new equipment, comprehensive performance tests should be conducted to verify whether it meets the design requirements. Operational parameters should be adjusted in a timely manner based on the test data during actual operation, in order to avoid entering a surge condition. It is also possible to install surge monitoring and alarm devices to monitor the operating condition of the compressor in real time. Once signals indicating a approach to surge conditions, such as abnormal fluctuations in pressure or flow, are detected, an alarm is immediately issued to alert operators to take timely action, such as adjusting the load or activating surge valves, in order to prevent surge from occurring and ensure the safe and stable operation of the equipment. 3.2 Countermeasures against airflow pulsations Changing the volume of the buffer tank can significantly reduce airflow pulsations. Increasing the volume of the buffer tank appropriately can provide more space for gas buffering, thereby effectively reducing the amplitude of gas pressure fluctuations. When the compressor discharges, the buffer tank can absorb some of the pressure fluctuations ； When the compressor draws in air, it can also release some gas to compensate for the insufficient flow rate, thereby making the airflow within the pipeline more stable and reducing the impact on the pipeline as well as the vibrations. Increasing the diameter of the export collector pipe is also one of the common measures. A larger diameter of the outlet collector tube can reduce the airflow velocity, decrease the turbulence of the airflow within the pipe, and lower the pulsating pressure. At the same time, it can also increase the flow capacity of the pipeline, enabling smoother gas flow, reducing vibrations caused by changes in gas flow velocity, and enhancing the stability of the entire system. When designing or modifying pipeline systems, the diameter of the outlet manifold should be carefully considered to ensure it meets the requirement of reducing airflow pulsations. 3.3 Strategies for equipment structure and installation: Optimizing the design of the equipment structure can be approached from various aspects. For the rotor, its manufacturing precision must be strictly controlled to ensure that the dynamic balance meets the requirements. During the design phase, advanced dynamic analysis software is used to perform modal analysis on the rotor, predict its vibration characteristics during operation, and optimize structural parameters such as the shape and size of the impeller in order to reduce unbalanced forces. Strengthening the basic design is equally crucial. When designing the foundation, factors such as the equipment’s weight, rotational speed, and disturbances must be fully considered to appropriately select the type and size of the foundation. For large-scale equipment such as reformer hydrogen boosters, a frame foundation can be used to ensure the stiffness and stability of the foundation. Through calculation and analysis, the natural frequency of the foundation is made to be far away from the disturbing frequencies of the equipment, thereby avoiding resonance. Ensuring installation accuracy is an important step in reducing vibration. During installation, it is essential to accurately align the axis of the equipment, using high-precision measuring instruments for inspection and adjustment to ensure that its levelness and perpendicularity meet the required standards. Strict control must also be exercised over the elevation and center distance of the anchor bolts, to ensure that the equipment is firmly fixed and to prevent vibrations caused by improper installation, thus laying a foundation for the stable operation of the equipment. IV. Case Analysis 4.1 Case Study of Vibration Problems in a Reforming Hydrogen Booster Pump At a certain factory, the reforming hydrogen booster pump experienced excessive vibration during operation, which severely affected the safety and stability of production. The vibration of this unit is mainly characterized by abnormally high vibration values at the two measurement points of the radial bearings at the coupling end, while the parameters of the compressor other than those at the coupling end and those of the turbine are within normal ranges. After careful analysis and diagnosis, the technicians determined that the problem was caused by imbalance at the coupling. After shutting down the machine for inspection, it was found that two of the coupling bolts had not been installed properly during reinstallation; it was this oversight that caused imbalance in the machine’s shafting, thereby leading to vibration. To address this issue, the technicians reinstalled the coupling bolts as required. After reinstalling and restarting the device, all parameters returned to normal, and the vibration problem was effectively resolved. This case demonstrates that for the vibration problems of reformer hydrogen boosters, accurate diagnosis and targeted corrective measures are crucial. During the daily maintenance and repair of equipment, it is essential to pay close attention to every step, ensuring that all components are installed correctly and operate properly. This is necessary to maintain the stable operation of the entire production system and to avoid production losses and safety risks caused by vibration issues. V. Conclusions 5.1 Summary of research findings The main reasons for the high vibration in reformed hydrogen boosters include surge, airflow pulsation, as well as equipment structure and installation issues. Surge can be addressed by adjusting the operating point position, conducting performance tests, and other measures ； Changing the volume of the buffer tank and increasing the diameter of the outlet manifold can alleviate airflow pulsations ； Optimizing the equipment structure, strengthening the basic design, and ensuring installation accuracy address the issues related to the equipment structure and installation. These research findings are of great significance for ensuring production safety, stable operation, and reducing economic losses, and can effectively guide the resolution of problems in actual production. 5.2 Future research directions In future research on the vibration issues of reformer hydrogen boosters, advanced vibration data acquisition and processing techniques can be utilized, in combination with methods such as finite element analysis, to analyze vibration characteristics more accurately. It is also possible to explore new materials and technologies to enhance the wear resistance and vibration resistance of equipment components, thereby reducing vibrations at the source. Meanwhile, intelligent analysis and control of vibration-related faults should be strengthened.