本文選題：低溫管系 + 動態(tài)分析�。� 參考：《蘭州理工大學(xué)》2017年碩士論文

【摘要】：在低溫領(lǐng)域,低溫管系用以輸送流體介質(zhì)、傳遞流體動力及信息。與低溫管系相連的各種動力設(shè)備(如往復(fù)式壓縮機(jī)、泵)工作時存在一定的間隙性與周期性,動力設(shè)備對管內(nèi)流體提供一定的激發(fā),使管內(nèi)流體呈脈動狀態(tài)。脈動流體對管系彎頭、異徑管、閥門等元件集中施加一定周期的脈動激振力,引發(fā)管系振動。管系振動會使管系連接部位發(fā)生磨損、松動,使管系支吊架發(fā)生疲勞斷裂。若管系持續(xù)振動,會造成儀器儀表精度下降,接管、三通及彎頭損壞進(jìn)而引起整個管線的破壞,造成嚴(yán)重事故。結(jié)合國內(nèi)外管系振動標(biāo)準(zhǔn),以藍(lán)科高新2萬方低溫貯罐配套管系(低溫乙烯液體輸送管系)為研究對象,對低溫管系中動力設(shè)備引起的振動問題進(jìn)行研究,分析引起低溫管系振動的原因及影響管系振動的因素,并應(yīng)用CADWorx或CAESARII軟件建立低溫管系物理模型,針對不同工況下低溫管系進(jìn)行靜力學(xué)與動力學(xué)響應(yīng)分析,根據(jù)計算結(jié)果提出了相應(yīng)的改造措施。具體工作包括:1.進(jìn)行低溫管系靜力學(xué)分析,校核了低溫管系的一次應(yīng)力、二次應(yīng)力及管系位移水平,驗證了現(xiàn)行設(shè)計的可行性,并介紹了不同類型的低溫管系支吊架建模注意事項及其使用方法。利用CAESARII軟件對管系進(jìn)行了應(yīng)力、位移、約束分析,結(jié)果表明管系最大應(yīng)力比均小于1,管系線位移偏大,管系橫向、縱向受力較大。因此,管系與設(shè)備連接管口因承受設(shè)備重量、基礎(chǔ)沉降等受力過大;管系中因固定支撐與導(dǎo)向不足,管系穩(wěn)定性不夠。據(jù)此提出了相應(yīng)的改造措施,優(yōu)化管系設(shè)計。2.以低溫潛液泵出口管系為例,應(yīng)用CAESARII軟件進(jìn)行諧響應(yīng)分析,獲得了潛液泵軸頻激勵下流體壓力脈動激發(fā)的管線諧響應(yīng)結(jié)果。表明:原管系基頻過低,應(yīng)力超標(biāo),壓力脈動下管系振動劇烈,需采取一定的防護(hù)措施以消弱管系振動。通過改變管系支撐結(jié)構(gòu)與布置,減小管口附加位移,調(diào)整閥門等附件在管系中的位置,一次應(yīng)力比降低了38.8%,二次應(yīng)力比為原來的3倍,基頻提高了219.5%。管系固有頻率避開了共振區(qū),最大振幅從22mm減小到不到2mm,管系振動趨勢明顯減弱。3.應(yīng)用CAESARII軟件對某低溫乙烯液體輸送管系進(jìn)行動態(tài)分析,校核了在泄放閥泄放反力作用下管系的位移、應(yīng)力是否符合規(guī)范,并對管系結(jié)構(gòu)進(jìn)行了優(yōu)化。結(jié)果表明:原管系基頻過低、應(yīng)力超標(biāo),距離泄放閥最近端管系彎頭縱向振幅較大,泄放閥泄放反力作用彎頭位置橫向振動劇烈,須重新對管系進(jìn)行改進(jìn)。據(jù)此提出改進(jìn)方案:(1)將管系中間位置約束改為固定支撐,以增大管系剛度;(2)將距離泄放閥最近彎頭處承重支撐改為彈簧支撐,以承擔(dān)豎直方向的反沖力;(3)在泄放閥進(jìn)口管段設(shè)置阻尼約束,泄放閥出口管彎頭位置加設(shè)承重支撐與限位,并調(diào)整限位與管系之間的間隙,找到最佳間隙為6.63 mm。據(jù)改進(jìn)后的方案重新建模并分析,管系在X、Y、Z向的最大振幅分別減弱了88.12%、76.02%、99.86%。
[Abstract]:In the cryogenic field, cryogenic pipes are used to transport fluid media and transfer fluid dynamics and information. All kinds of power equipment (such as reciprocating compressors and pumps) connected with the low temperature pipe system have certain gap and periodicity when working. The power equipment provides a certain excitation to the fluid in the pipe and makes the fluid pulsate in the pipe. The pulsating fluid exerts a certain period of pulsating excitation force on the pipe elbows, diameters, valves and so on, which causes the pipe system to vibrate. The vibration of the pipe system will make the connection part of the pipe system wear and loosen, and make the support and hanger of the pipe system fatigue fracture. If the pipe system continues to vibrate, it will cause the instrument precision to decline, the pipe, the three way and the elbow damage, then causes the entire pipeline destruction, causes the serious accident. The vibration problem caused by power equipment in low temperature pipe system is studied by taking Lanke hi-tech 20 thousand square cryogenic tank system (cryogenic ethylene liquid conveying pipe system) as the research object in combination with the vibration standard of domestic and foreign pipe system. The causes of low temperature tube system vibration and the factors influencing the low temperature tube system vibration are analyzed. The physical model of low temperature pipe system is established by using CADWorx or CAESARII software. The static and dynamic responses of low temperature tube system under different working conditions are analyzed. According to the result of calculation, the corresponding measures are put forward. Specific tasks include: 1. The static analysis of the low temperature pipe system is carried out, and the primary stress, secondary stress and displacement level of the low temperature pipe system are checked, which verifies the feasibility of the current design. The paper also introduces the matters needing attention in modeling of different types of low-temperature pipe suspension and their application methods. The stress, displacement and constraint of the pipe system are analyzed by CAESARII software. The results show that the maximum stress ratio of the pipe system is less than 1, the line displacement of the pipe system is larger than that of the pipe system, the transverse and longitudinal stress of the pipe system is larger. Therefore, because of bearing the weight of the equipment and the settlement of the foundation, the pipe system and the connecting nozzle of the equipment are subjected to too much force, and the stability of the pipe system is not enough because of the insufficient fixed support and guidance in the pipe system. Based on this, the corresponding measures are put forward to optimize the design of pipe system. Taking the outlet pipe system of cryogenic submersible pump as an example, the harmonic response of pipeline excited by axial frequency excitation of submersible pump is obtained by using CAESARII software. The results show that the vibration of the original pipe system is too low, the stress is over the standard, and the vibration of the pipe system is intense under the pressure pulsation. Some protective measures should be taken to reduce the vibration of the pipe system. By changing the support structure and arrangement of the pipe system, reducing the additional displacement of the pipe opening and adjusting the position of the valve and other accessories in the pipe system, the primary stress ratio is reduced by 38.8 times, the secondary stress ratio is 3 times that of the original one, and the fundamental frequency is increased by 219.55. The natural frequency of the tube system avoids the resonance region, the maximum amplitude decreases from 22mm to less than 2 mm, and the vibration trend of the tube system obviously weakens by .3. The dynamic analysis of a cryogenic ethylene liquid conveying pipe system was carried out by using CAESARII software, and the displacement and stress of the pipe system under the action of the releasing reaction force of the release valve were checked, and the structure of the pipe system was optimized. The results show that the base frequency of the original pipe system is too low, the stress exceeds the standard, the longitudinal amplitude of the elbow of the nearest end of the discharge valve is larger, and the lateral vibration of the elbow position of the relief valve acting on the releasing reaction force is intense, so the pipe system should be improved again. Accordingly, an improved scheme: 1) to change the middle position constraint of the pipe system to a fixed support to increase the stiffness of the pipe system is put forward. (2) the load-bearing support at the nearest elbow of the relief valve is replaced by a spring support. The damping constraint is set in the inlet section of the outlet valve, the load bearing support and limit position are added at the elbow position of the outlet pipe of the discharge valve, and the clearance between the limit position and the pipe system is adjusted, and the optimum clearance is found to be 6.63 mm. According to the remodel and analysis of the improved scheme, the maximum amplitude of the tube system in the direction of XNY _ (Z) is reduced by 88.128.12 / 76.02 / 99.86, respectively.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ055.81

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