加氢裂化装置液力透平机械密封系统改造

2008年2～7月,燕山石化炼油一厂液力透平机械密封系统发生5次泄漏.对其进行改造:密封内部结构,将双端面机械密封由旋转式改为静止式；用小弹簧取代波纹管,密封“O”形圈选用全氟醚橡胶(FFKM)；动、静环材料升级为复合型碳化硅,提高了导热性能；将密封动环的镶嵌式结构改为整体加工结构,密封静环几何形状最大限度地保证了温度的均匀变化；缩小密封面宽度,以减少摩擦产生的热量；将泵送环由螺旋型更换为离心式,以增加隔离液的循环流量.密封辅助系统,在靠近大气侧的第二道密封外部通入保护氮气,防止泄漏出的少量高温隔离液与空气中的氧气接触产生积碳；氮气经过滤、减压后,用紫铜管引入密封腔体内.冷却水改造,将软化水引至液力透平,既可替代原有循环水,又无需增加额外的软化水消耗.软化水的使用,消除了隔离液冷却器盘管外部结垢隐患.改造后,液力透平的同步运行率由53.2％提高到98.0％.每年节电1.94× 106kW.h,节约资金136万元.

The Optimization of Mechanical Seal System of Hydraulic Turbine of Hydrocracking Unit

The mechanical seal system of the hydraulic turbine in Sinopec Beijing Yanshan Company′s Refinery No.1 experienced five leaks during February to July 2008.Technicians revamped the system by taking the following measures:replacing the rotary-typed double mechanical seal with static seal inside the seal structure;replacing corrugated pipes with small springs and using FFKM O-rings;upgrading the dynamic and static seal ring material to compound silicon carbide to improve their heat-conducting properties;changing the mounted-type structure of the dynamic seal ring to one-piece structure and using static seal rings with a geometry that maximizes the homogeneity of changes in temperature;reducing the width of seal surface to reduce the heat generated from friction;and replacing the spiral-shaped pumping ring with a centrifugal pumping ring to increase the circulating flow of spacer fluid.In the seal supporting system,injecting protective nitrogen outside the second seal near the atmospheric side to prevent small amounts of high-temperature spacer fluid leaked from coming into contact with the oxygen in the air to produce carbon deposits;the nitrogen,after being filtered and depressurized,is drawn into the seal cavity via a copper tube.In the revamping of the cooling water system,softened water is introduced into the hydraulic turbine.The softened water can be used to replace the original circulating water and no additional softened water is used.The use of softened water eliminates the risk of scaling outside the coiler of the spacer fluid cooler.After the optimization,the synchronous running rate of the hydraulic turbine rose to 98.0% from 53.2%.Annual electricity savings amount to 1.94×106kW·h and money saved annually reaches 1.36 million yuan.