摘要
对多套乙烯装置急冷油减黏系统设计和改造进行点评,提出急冷油减黏改造的技术建议:设置减黏塔,用高温的乙烷炉裂解气作减黏塔的汽提介质。不宜用蒸汽作为减黏塔的汽提介质,因为其温度低,不能把足够多的减黏组分汽提出来。并且用大量的蒸汽汽提,会增加投资和装置能耗。减黏塔的塔顶温度宜控制在250～300℃,石脑油裂解,该温度约在260～270℃。温度太低,减黏效果不佳。防止减黏塔内"过度蒸发",保证汽提后的裂解燃料油有良好的流动性。乙烷炉的油急冷器应选用"立式溢流型"结构,可减少结焦和设备堵塞。在乙烷炉清焦的两天中,用高压蒸汽替代乙烷炉裂解气,把油急冷器中的急冷油送入减黏塔,维持操作。清焦结束后,重新投料,并把裂解气作为减黏塔的汽提介质,恢复到正常的减黏状态,急冷油的黏度也恢复到正常黏度值。急冷油黏度高的原因是工艺设计上存在缺陷,诸如把板式塔改为填料塔、加大塔的直径、增加换热器台数等措施均不能解决急冷油黏度问题。优化急冷系统的模拟计算,设置合理的模拟计算收敛精度,选用合适的热力学方法,特别是选用合适的平衡常数K值,采用二次开发的PRO/Ⅱ软件,可以得到一个适用的急冷系统模拟计算程序。
This article reviews the design and revamping of the quench oil viscosity reducing systems of several ethylene plants and puts forth technical proposals for reducing the viscosity of quench oil ：Adding a viscosity reducing column and using high-temperature cracked gas from the ethane furnace as the stripping medium.Steam is not a good option for use as the stripping medium for the viscosity reducing column as its temperature is too low to strip enough quantities of viscous components out.Using a large amount of steam for stripping also increases investment and energy consumption by production units.The ideal range of temperature at the top of the viscosity reducing column is 250-300℃ and naphtha is cracked at a temperature of around 260-270℃.Too low temperatures will result in a poor viscosity reduction effect.Excess evaporation should be prevented inside the viscosity reducing column and the cracked fuel oil from the stripping process should have good flow properties.The ethane furnace should be equipped with an oil quencher with a vertical overflow-typed structure,which is instrumental to coking and plugging control.During the two-day decoking operation for the ethane furnace,high-pressure steam is used to replace cracked gas and the quench oil in the oil quencher is guided into the viscosity reducing column to sustain operation.After the decoking operation,feedstock is fed again and the cracked gas is used as the stripping medium for the viscosity reducing col umn—a return to the normal viscosity reduction state,with the viscosity of the quench oil also returning to the normal value.High viscosity of the quench oil is a result of defective process design.For example,none of the measures such as substituting packed column for plate column,increasing column diameter and adding heat exchangers could resolve the problem of high viscosity quench oil.Optimizing analog calculations for quench systems,setting an appropriate convergence precision for analog calculations,adopting an appropriate thermodynamics method,particularly the adoption of an appropriate equilibrium constant K value,and using the PRO/ Ⅱ software for secondary development can produce an applicable quench system analog calculation procedure.
出处
《中外能源》
CAS
2013年第1期62-66,共5页
Sino-Global Energy
关键词
乙烯装置
急冷油减黏
乙烷炉
油急冷器
减黏塔
ethylene unit
quench oil viscosity reduction
ethane furnace
oil quencher
viscosity reducing column
