Stress And Vibration Analysis Of Reciprocating Pump Piping Systems

During the operation process of reciprocating pump in oil stations, due to the cyclical movement of the piston or plunger, liquid can generate pressure pulsation, leading to piping vibration, severe vibration may cause the pipe pipeline failure, instrument distortion, equipment damage, staff health and other issues, which is the key to safe operation of pipeline and has a great threat to the normal operations. Therefore, the reciprocating pump and piping system vibration stress research has important theoretical and practical significance. This article is aiming at the reciprocating pump pipe stress and vibration problems, the main work are as follows:(1) This article starts from the reciprocating pump pipe pressure fluctuation caused by fluid. Based on the theory of pipeline vibration, pressure pulsation in the piping system and the excitation force is calculated under the action of the reciprocating pump. Based on the beam model, numerical simulation method of reciprocating pump pipeline stress and vibration was established. Take a designed simple pipe as an example, to do stress and vibration analysis using CAESAR ? software. In order to verify whether the established numerical simulation method is practicable, an experiment platform according to the designed pipe was built, and the compare between experimental results and numerical simulation results has proved that numerical simulation method is of good feasibility.(2) Based on the lab experiments, four factors, the pressure, flow, constraints and bend angle had been analyzed to study their influence to pipe stress and vibration. And it can lay the foundation for stress reduction and damping measures proposed later. Results showed that adding constraints near the bend, and change the bend angle can effectively reduce the pipe stress and vibration amplitude.(3) In order to put the numerical simulation method into practical engineering, FC oil station reciprocating pump piping system numerical model was established. Stress analysis, modal analysis and vibration analysis were done (Single pump operation and the double pump). It has determined the pipeline with large stress and vibration amplitude in the system. And it is concluded that the influence of pipe stress and vibration amplitude can be caused by number of pump. That is,1) Excitation force is produced in the bend or tee joint, and it can also influence the straight pipe in different levels; 2) In this pipeline system, the pump discharge pipe has a larger stress, vibration amplitude and lower natural frequency,3) Pump running number has a certain impact to pipe stress and vibration amplitude.(4) According to the actual situation of oil station, influencing factors like flow rate, pressure, fulcrum settlement, crude oil density have been analyzed, and the corresponding results were obtained. That is,1) Reciprocating pump pipe stress and the vibration amplitude increases with the increase of pressure; 2) The stress and vibration amplitude increases with the density of crude oil, while pipeline natural frequency decreases with the increase of density of crude oil; 3) The stress and vibration amplitude increases with the pipe thermal stress, and when the oil temperature is higher than 85?, it had a greater influence on the vertical vibration amplitude of the pipe. Through the stress distribution diagrams of FC oil station pipe, this summarizes the current issue exists in stress distribution expression in the three-dimension pipeline, and a new stress distribution expression is designed in this paper.(5) Stress and vibration reduction measures have been put forward, mainly including adding constrains, enlarging the pipe diameter, changing bending angle, etc. Meanwhile, there has been come up with a new concept, stress decreasing coefficient, as a parameter to measure stress reduction effect. Through the analysis, it comes to:1) To add jack and clump weight on the horizontal pipe section which is near the bend can effectively reduce the pipe stress; 2) Replacing the 90° bend with 60° bend can effectively reduce the stress of the bend; 3) the method of adding air chamber at the pump import and export can effectively reduce pressure pulsation.