低温BOG压缩机活塞杆运动件预紧力的研究  

Preload Analysis of Piston Rod Bolted Joints on BOG Compressor in Low Temperature

作　　者：燕翌 杨其文 李云[1] 

机构地区：[1]西安交通大学,陕西西安710049 [2]中石化洛阳工程有限公司,河南洛阳471003

出　　处：《流体机械》2016年第5期26-30,共5页Fluid Machinery

摘　　要：BOG压缩机是对LNG储罐中蒸发出的气体进行加压的设备,其主要特点是工作在低于-100℃的超低温下。在如此低温下工作,压缩机的螺纹连接件预紧力状况会和常温预紧时产生很大变化。本文以BOG压缩机活塞杆螺栓连接为研究对象,提出了一种能预测螺栓低温预紧力变化的理论公式并进行了精度修正,通过有限元模型验证了理论公式在计算活塞杆螺栓预紧力变化的有效性,结果表明,通过理论公式与有限元模型的对比,表明结构即使不完全符合理论公式的要求,理论公式与有限元计算仍然较为吻合。在螺栓连接材料为304不锈钢和SIC815合金钢组合下,常温下预紧至60%屈服应力的螺栓连接,在-125℃低温下预紧力会产生30%的松弛。此外,本文对往复活塞力以及应力集中对活塞杆螺栓应力状态的影响进行了分析,并以理论公式为基础,将应力集中、工作温度范围、外部静载等因素考虑在内,提出了针对不同状况的螺栓常温预紧力取值范围,可满足较广范围螺栓连接预紧力取值的需求。BOG（ Boil Off Gas） compressor compresses the gas boiled off from the LNG storage tank. Its main characteristic is that it works in ultra low temperature lower than- 100℃. In such a low temperature,the preload condition of bolted joints in BOG compressor will change a lot comparing with the pre-tightening condition in ambient temperature. In this paper,the bolted joint on piston rod is treated as research object. The validity of theoretical evaluation of preload change is certificated using Finite Element Method. The result shows that the error of theoretical estimation is relatively low even if the dimension of bolted joints is not completely typical. For the bolted joints with the combination of 304 SIC815 and pre-tightened to 60% yield point,its preload will lose more than 30% in- 125℃. Additionally,the effect of the reciprocating piston force and the stress concentration on the bolted joint is discussed and taking these factors into consideration,a set of preload selection recommendation formula is presented in this paper. It will help decided the preload of a wide range of bolted joints in ambient temperature.

关 键 词：BOG压缩机 预紧力 预测公式 

分 类 号：TH45[机械工程—机械制造及自动化]