延迟焦化装置焦炭塔安全评估与剩余寿命预测方法

Safety evaluation and residual lifetime prediction of coke drums in delayed coking plant

关键词:  有限单元法  延迟焦化  焦炭塔  安全评估  寿命预测 

Key words:  finite element method  delayed coking  coke drum  safety evaluation  lifetime prediction

摘要:

延迟焦化装置中的焦炭塔长期受到温差和机械载荷的共同作用,在这些交变载荷的作用下,焦炭塔体中部易产生鼓胀变形,裙座角焊缝也容易萌生裂纹。因此,如何评估焦炭塔的安全性,并对其疲劳寿命进行预测一直是工程界和学术界的研究难点。运用有限元技术,针对焦炭塔容易产生失效的两个部位,分别位于塔体中部鼓胀位置和塔体下部裙座焊接接头位置进行风险评估,得到整个周期内焦炭塔出现最大应力的危险时间点,再运用ASME VIII-2中相关技术校核危险部位的安定性,最后运用Manson-Coffin公式和S-N曲线方法分别预测焦炭塔的剩余寿命。方法 的建立为炼油装置中类似设备的风险评估和寿命预测工作提供了技术支撑。

Abstract:

Coke drums in delayed coking plant are usually subjected to long-term combined loads caused by high temperature gradient and mechanical forces during the normal operating period. Under these long-term alternating loads, the coke drums may generate increasing gourd-shaped deformations locating in the middle height of tower, and cause crack initiation near the welding joint connecting the skirt and coke drum body. Therefore, how to predict the safety performance and residual lifetime of coke drum is always a difficult issue in academic and engineering fields. In this paper, a comprehensive evaluation method including risk assessment, stability analysis, and residual lifetime prediction of coke drum body is finally established using finite element method, and the critical positions are located in the mid height of the tower and the welding joint near the skirt. Particularly, the lifetime of coke drum is calculated by the methods of Manson-Coffin and S-N curves, respectively. This paper can provide fundamental supports for the risk assessment and life prediction of similar equipment in the oil refining unit.