焦炭塔的安全性分析及寿命评价——焦炭塔的结构强度分析

【作者】 张同；

【导师】 王正；

【作者基本信息】 大连理工大学 ， 动力机械及工程， 2004， 硕士

【摘要】 工程实际中的强度问题牵涉范围十分广泛，可归结为考虑限制结构承载能力的各种因素，包括：塑性变形引起的零件形状的显著变化、载荷超过额定值时材料的破坏和结构稳定性的丧失等。材料在高温下的应力状况更加复杂，温差应力和机械应力的耦合作用，对设备的强度造成巨大影响，分析结构在高温下的强度问题具有重要意义。 焦炭塔是石化行业延迟焦化工艺的重要设备，由于操作条件的苛刻，容易出现强度问题引起的多种失效，对它进行全面的结构强度分析具有很大的实际意义和经济价值。 为对实际操作的焦炭塔进行结构强度分析，本文着重对塔壁的热变形和热应力进行了研究。根据有限单元法理论，建立瞬态温度场分析模型，利用功能强大的有限元分析软件ANSYS对塔壁进行各主要操作阶段的温度场和热应力场分析。同时对改进的裙座结构进行计算，比较两种结构型式对设备受力的影响。分析焦炭塔在机械载荷，如内压、自重、风载和地震载荷作用下的应力情况，其中塔体的模态分析、风载的函数加载和地震载荷的时程分析是本文的创新。 分析结果表明焦炭塔塔壁的温度场存在径向和轴向温度梯度，产生的热应力在塔壁组合应力中占主要成分，采用安定性准则进行评价，得出焦炭塔满足安定性条件的结论。对裙座所受轴向压应力进行校核，可知裙座满足稳定性条件。数值计算所得结果理论合理，与实际吻合良好，从而可以为焦炭塔的事故分析及结构改进提供依据。更多还原

【Abstract】 Strength problem in practical engineering contains extensive range, and usually comes down to considering many factors relating to structural bearing capacity, such as obvious shape variation due to plastic deformation, material damage due to load over nominal scale and stability loss, etc. The stress state of material under high temperature is more complex, where temperature stress combines with mechanical stress, which produces huge effects on strength of device. So researching their strengths under high temperature has important value.Coke drum is the key device of delayed coking in petrochemical industry. But due to the severe service conditions, it’s easy to raise some kinds of failure relating to structural strength. So analyzing its strength completely has great practical meaning and economic value.In order to study structural strength of the coke drum in working, paper emphasizes the study on the thermal deformations and thermal stresses of the wall. Sets up analytic models for the transient temperature field, based on theory of finite element. Makes good use of the powerful software ANSYS to calculate the temperature fields and thermal stress fields on different stages in its operation. In order to compare the effect of different structural patterns to structural strength, the improved skirt structure is studied.All mechanical loads are considered, including internal pressure, gravity, wind load and earthquake load, in which the modal analysis of the drum, functional wind load and temporal analysis for earthquake are the innovations of this paper.The analysis results indicate that not only radial temperature gradient but also a major axial one exist in temperature field of the drum wall, and the thermal stresses generated by them are the essential components of the combined stress onthe wall. Comparing the combined stress of mechanical and thermal stress with the stability criterion, conclusion is drawn that the structure of coke drum contents the qualification of stability. Checking the axial compressive stress of the skirt, deduces that it is stable. The simulation results got in this study are reasonable and match the practical perfectly. So the methods employed in this paper is useful for the failure analysis and structural improvement of coke drum.更多还原