Causes Leading to Formation of Shot Cokes and Measures for Its Prevention in Super Viscous Oil Delayed Coking Unit

Shot cokes are frequently formed in the delayed coking unit treating the super viscous oil at PetroChina＇s Liaohe Petrochemical Company. Considerable work has been carded out to avoid the formation of shot cokes. The test results obtained have shown that the property of super viscous oil has played a key role in the formation of shot cokes. After adjusting and optimizing the process indices the operating regime of the delayed coking unit at a throughput of 118t/h of the super viscous oil is specified as follows： a reaction temperature of 498-502℃, a reaction pressure of 0.17-0.25 MPa, a recycle ratio of 0.5-0.6 and a fractionation tower bottom temperature of 355-365 ℃. In the meantime, the delayed coking process has adopted measures to enhance pre-fractionation of the feedstock to rationally remove light fractions and maintain a steady gas velocity in order to avoid the formation of shot cokes.

风机并网与解裂对电力系统的影响及应对策略

并网型风力发电机组由于受其固有功率特性的影响,启停时会对电力系统产生较大的冲击电流,引起系统电压跌落,影响系统功率平衡。以异步风力发电机组为例,在常规研究的基础上,提出在风力发电机组出口端加延迟控制器,构建风力发电机组并网模型,分析风电机组并网与解列对电力系统的影响,合理安排各台机组的最佳并网时间,避免多台风力发电机组同时并网,减小风电启动对电力系统安全运行的影响。选取中型规模风电场为例,构建内部接线图及并网模型,并仿真验证。该研究成果对风电并网运行具有一定的工程借鉴意义。

社区治理结构“逆扁平化”层级扩张的逻辑研究

近年来,结构扁平化在一定时期内是公共治理组织架构调整的方向,在实践中出现社区治理结构层级增加的现象。通过案例研究,探讨社区治理结构"逆扁平化"层级扩张的逻辑过程中发现,在社区治理情境中,社区治理具有互动直接性和情感影响等特征,城镇化发展造成社区治理单元内的治理规模双维扩大,社区治理资源仍待进一步整合。为了实现社区治理精细化,提升社区治理实效,各地方在实践中缩小了社区治理的基本单元,在充分重组已有资源的基础上挖掘潜在资源,提升居民个体对社区治理的感受度和幸福感,在客观上形成了社区治理结构"逆扁平化"的现象。