超大型液化石油气船再液化装置控制设计

Design of the Control System for Reliquefaction Plant on Very Large Liquefied Petroleum Gas Carrier

以当前85 000m3超大型液化石油气船采用的再液化装置为研究对象,从该型船的预期用途和装卸运载需求出发,对再液化装置的基本概念、工作原理、设备配置和工作模式进行阐释。结合国外石油气压缩再液化冷却系统的工艺流程理念,基于设备运作的安全性和可靠性原则,着重对组成该装置的蒸气抽吸分离器、压缩机、冷凝器、冷却器和集液器等主要部件进行分析,阐述这些部件在工艺流程中发挥的作用、相应的控制监测手段及其实现的报警联锁功能等。以再液化装置的货物冷凝强制回罐模式为例,说明超大型液化石油气船上商业丙烷(液态下含有8mol%乙烷)的液化循环过程,为国内再液化装置的控制设计提供参考。

Taking the reliquefaction plant installed on an 85000 m3 Very Large Liquefied Petroleum Gas Carrier(VLGC)as the research subject,this paper elaborates the basic concept,the operational principles,the equipment configuration and the operating modes of the reliquefaction plant in accordance with the intended purpose of the ship and the requirements of handling and transportation.According to the foreign process principles for compression,liquefaction and cooling of petroleum gas,this study analyses the major components of the reliquefaction plant,such as vapor suction separator,compressor,condenser,cooler and accumulator,with the emphasis on safe operation and reliability of the system.It elaborates the functions of the components in the reliquefaction process,the corresponding means of control and monitoring,and the alarm and interlock performance.Then the liquefaction cycle of cargo propane(8 mol%ethane in liquid phase)on the VLGC is explained based on the cargo condensation and the forced reflux of the reliquefaction plant,which provides references for the design of the control system for reliquefaction plant in China.