Analysis on the Vibration and Cracking Failure of Feeder Pipeline in Ammonia Synthesis Tower
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TECHNICAL ARTICLE—PEER-REVIEWED
Analysis on the Vibration and Cracking Failure of Feeder Pipeline in Ammonia Synthesis Tower Yuqi Ding · Feng Qiu · Jubao Liu · Zengtao Chen
Submitted: 19 October 2016 / in revised form: 3 December 2016 / Published online: 17 January 2017 © ASM International 2017
Abstract Feeder pipeline of synthetic ammonia power is usually located at a high position. Due to the defects in design and construction, vibration and cracking failure of the connecting pipe are not uncommon. Vibration testing and finite element method (FEM) were applied to the phenomenon of cracking failure of the weld seam at the junction between the feeder pipeline and ammonia synthesis tower. Stress concentration of the weld seam due to the dead weight of the newly added connecting pipe and that of the liquid inside and uncoordinated deformation of the pipeline and tower are the reasons underlying the cracking of the weld seam. The pipeline supporting structure was improved by using FEM. The support frames were arranged vertically to relieve the stress concentration of the weld seam, and as a result, the maximum stress declined by 23.6% at the weld seam. Horizontal supports were installed to the connecting pipe and the elbow, respectively, and the uncoordinated deformation of the pipeline and tower was reduced. The maximum vibration amplitude of the pipeline was reduced by 46.8%. Vibration testing was then performed on the modified structure. The result showed that Y. Ding (&) · F. Qiu · J. Liu (&) School of Mechanical Science and Engineering, Northeast Petroleum University, Daqing 163318, Heilongjiang, China e-mail: [email protected] F. Qiu e-mail: [email protected] J. Liu e-mail: [email protected] Z. Chen Department of Mechanical Engineering, University of Alberta, 10-219 Donadeo ICE Building, Edmonton, AB T6G 1H9, Canada e-mail: [email protected]
the vibration of the weld seam was coordinated after improvement, which was favorable for preventing the vibration and cracking failure of the weld seam. Keywords Ammonia synthesis tower · Feeder pipeline · Cracking failure of the weld seam · Stress concentration · Vibration
Introduction Ammonia is an important inorganic chemistry product and also a widely used raw material in the chemistry industry. Ammonia synthesis tower is the main equipment for manufacturing ammonia. The production capacity of the synthesis tower has been improving constantly, from the previous 80–100 thousand tons/year to 180–240 thousand tons/year per set [1]. To adapt to this need, the diameter of the feeder pipeline and the reaction time of the liquid should be increased, and the mode of entry of the liquid into the tower be optimized. However, since the feeder pipeline is located at a high position, it is susceptible to wind loads, which may cause considerable vibration of the pipeline. As a result, the connections between the pipeline and the towers and between different segments of the pipeline will be worn and loosened. Under some extreme situations, the pipelines will crack open, ca
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