Analysis of the reasons for high vibration levels in diaphragm compressors and solutions

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Diaphragm compressors are important gas compression devices that are widely used in industries such as chemicals, petroleum, and pharmaceuticals. However, in actual operation, high vibration levels in diaphragm compressors are a common problem; they not only affect the normal operation of the equipment but can also lead to equipment damage and production accidents. Therefore, analyzing the reasons for the high vibration levels in diaphragm compressors and proposing corresponding solutions is of great significance for ensuring the safe operation of the equipment and improving production efficiency. I. Analysis of the reasons for high vibration levels in diaphragm compressors 1. Mechanical aspects 1) Installation issues: Loose or improperly tightened foundation bolts: Foundation bolts are the components that secure the compressor; if they are loose or not tightened properly, it can cause vibration during the compressor’s operation. The levelness of the fuselage does not meet the requirements: If the levelness of the fuselage is not proper, it can lead to weak connections between the moving parts, which in turn causes vibration. Coupling installation deviation: If the radial and axial deviations of the coupling exceed the allowable values, it will result in an abnormal mechanical connection between the motor and the compressor, thereby causing vibration. Improper pipeline installation: When installing pipes, too small a bending radius, or pipes that are too loose or damaged can cause vibrations in the pipes, which in turn affects the vibration of the compressor. 2) Component wear or loosening, and deformation of the valve stem cylinder: Deformation of the valve stem cylinder due to stress affects its proper functioning, which in turn causes vibration. Loose piston compression nut: If the compression nut of the piston is loose, knocking and vibration will occur. Loosening or breaking of the fastening bolts in the middle section: If these bolts become loose or break, it can lead to loosening of the cylinder head bolts as well as welding failures in the lower support part of the middle section, which in turn causes vibration. 3) Rotor imbalance and missing rotor parts: Scars on the rotor cause excessive uneven shedding, which leads to periodic, step-like imbalances as the rotor rotates at high speeds, thereby resulting in high vibration levels. Rotor bending: Intermittent local contact between the rotor and stator causes uneven heating of the rotor, resulting in temporary thermal deformation ； Or, due to collision or improper placement, the rotor may suffer permanent deformation. Inherent imbalance: Although each rotor has been dynamically balanced before assembly, imbalance may still occur during the connection of the rotors. 2. In terms of fluid mechanics: 1) Airflow pulsation: Airflow pulsation generates excitation forces that cause pipeline vibration, which in turn affects the vibration of the compressor. 2) Excessively small cylinder clearance: When the cylinder clearance is too small, the piston collides with the inner end face of the cylinder at the top and bottom dead centers, resulting in severe impact and vibration. II. Solutions for high vibration levels in diaphragm compressors 1. Mechanical aspects 1) Installation and adjustment: Tighten the foot bolts: Check and tighten the foot bolts to ensure they are all tightened evenly. Adjust the level of the fuselage: Recheck the level of the fuselage and adjust it again if necessary to ensure it is level. Calibrate the coupling: Recheck the installation deviation of the coupling and recalibrate its coaxiality. Optimize pipeline installation: Avoid overly tight bends during pipeline installation, secure the pipe clamps properly, hang the support or vibration sections on elastic mounts as much as possible, and place wooden or rubber pads between the pipes in the vibration sections and the mounts. 2) Component maintenance and replacement of deformed parts: Replace the deformed valve pressure cylinder. Tighten the piston nut: Check and tighten the compression nut of the piston. Check the fastening bolts: Inspect the bolts that secure the middle section; if they are loose or broken, replace them promptly. 3) Rotor balancing and repair: In the case of missing parts on the rotor, the rotor is disassembled for welding, precision machining, and grinding, followed by high-speed dynamic balancing. Correcting rotor bending: For temporary bending, it is possible to avoid contact between the rotor and stator by adjusting operating parameters ； For permanent bending, the rotor needs to be replaced. Adjust rotor connections: For inherent imbalance, it is necessary to readjust the connections between the rotors to ensure balance. 2. In terms of fluid mechanics: 1) Optimizing airflow pulsations: By establishing models for analyzing airflow pulsations and vibration modes, the pulsating forces within the pipeline as well as the modal properties of the pipeline structure are analyzed, thereby optimizing the pipeline design and reducing vibrations caused by airflow pulsations. 2) Adjust the cylinder clearance: Check and adjust the cylinder clearance to ensure it meets the design requirements. IV. In summary, the operating mode of diaphragm compressors is a reciprocating process from low pressure to high pressure. After the tube truck has been filled, once it switches from a loaded state to an unloaded state, the pressure in the secondary exhaust system, due to its direct connection to the tube truck’s tank, drops to almost the same level as the pressure inside the tank. At this point, the pressure of the primary exhaust is higher than the pressure inside the tank of the tube bundle vehicle; the secondary cylinder does not need to perform any work, which instead increases the workload on the primary cylinder. The equipment is no longer in a state of symmetric balance, which leads to an increase in the vibration levels of the primary cylinder. Equipment maintenance personnel can consider addressing this issue of excessive vibration starting from this point.