Central Steam Pipelines Analysis

In many big enterprises such as electric power and pentrifaction ones, there are lots of high temperature and pressure pipelines conveying steam. Because of improper design, collocation and adjustment of the supporting and suspending nogs, pipelines often vibrate, which affects natural life, threatens safe production and even leads to grave accident.On the basis of consulting lots of home and overseas data, this dissertation comprehends profoundly the causes of vibration, the ways of reducing vibration and the measures of eliminating vibration, In NO.803 plat, there are four central stream pipelines, in order to solve their vibration problems, this dissertation brings forward corresponding calculation model. According to results of calculations and experiments, main causes that contribute to vibration are founded, then puts forward improving measures of adding deflexed supporting and suspending nogs and making pipelines shunt-wound, finally completes improvement tasks Following is the main works completed in this thesis:(1)This thesis sets up a mathematic model of steam pipelines , using ANSYS5.6 limited-unit analyzing software, calculates the ten phase inherent frequency and the foregoing eight phases vibration types of four steam pipelines of the unit before dealt with.(2)Practical measures the frequency spectrum and wave form at five different kind of steam flux were done. The results of calculation and measures show that the low frequency of steam pipelines vibration fastens on 4.3 to 4.5 Hz and 9.5Hz, the low modes fastens on one-steps curl in vertical plane and its plane of each steam pipeline and one-rotation along with the line connecting the port circling main steam gate and the horizontal port of unit. The modes of #3 and #4 main steam conduits occupy the majority of low steps modes (the five of the first eight phases), except for the first phase rotation vibration, the maximal distortion of other low steps vibration modes are all caused by the vibration of erect pipelines of cylinder. The both results of calculations and experiments are consistent.(3)By spot reconnaissances, according to the results of calculations and measures, the problem of vibration is solved by adding deflexed supporting and suspending nogs , making pipelines shunt-wound and without changing the previous design andcollocation, which can also measure up nationally. To complete the improving program successfully, the improving project is demonstrated using ANSYS5.6 limited-unit analyzing software, the results of it show that the project put forward can resolve the problem of transmitting steam pipelines.(4)The practical measures show that: Stress of pipelines accords with national demand and peak value of vibration decreases from 1mm to 0.2mm, whereas the inherent frequency of each phase increased generally. There is no vibration in the course of six months' moving. The effect of improving is all right.