焦炭塔运行过程热应力有限元分析

摘要

焦炭塔作为延迟焦化装置的关键设备,在其运行过程中承受着巨大的周期交变温度和循环载荷.研究焦炭塔不同部位应力及同一部位不同时刻应力对焦炭塔安全运行具有重要意义.本研究运用热-结构耦合有限元计算方法,以热分析结果、焦炭塔自重、操作内压、水压等作为载荷对焦炭塔进行了结构场数值计算.研究结果表明:温度梯度所产生的热应力远大于介质重量、自重所产生应力对焦炭塔安全的影响;过渡段热应力变化最复杂,热应力最大;除油气预热阶段外,都有焦炭塔应力最值超过塔体材料的屈服极限从而导致塑性应变的情况;蒸汽冷焦阶段塔体应力变化量最小,给水冷焦阶段对塔体安全运行影响最大.%As the key equipment of delayed coking unit, the coke drum suffers tremendous periodic alternating temperature and cyclic load during operation. The research of stresses on coke drum's different parts and the same part at different time has great significance to the safe operation of coke drum. This study used thermal-structure coupling finite element method, with thermal analysis results, the weight of the coke drum, internal pressure of operation and the water pressure as the loads to conduct structure field numerical calculation of coke drum. The results show that the thermal stress produced by temperature gradient has greater impact on the safety of coke drum than the stress caused by medium weight and gravity. Transition section has the most complex thermal stress change and the largest thermal stress. Besides the oil and gas preheating stage, all exist the stress peaks of coke drum which exceed the material yield limit of drum body that results in the plastic strain. Steam coke-cooling stage has the minimum variation of stress on the drum body, and water coke-cooling process has the biggest impact on the safe operation of coke drum.