액화천연가스 운반선의 저용량 압축기와 강제 기화기의 병렬운전 제어시스템

Abstract

Natural Boil-Off Gas (NBOG) generation during laden voyage of the LNG (Liquefied Natural Gas) Carrier is inevitable because Natural Gas (NG) generally liquefied below –160℃ in the atmospheric state and continuously evaporated by small heat ingress from relatively hot outside. The generated NBOG affects the cargo tank pressure increase, and the Gas Management System (GMS) for LNG Carriers is closely related to the maintenance of the cargo tank pressure and the fuel gas supply system for the main boiler. One of the main problems with LNG Carriers is the handling of NBOG from cargo tanks, but NBOG is generally used as the main boiler fuel for steam production in steam turbine propulsion systems to save cost. In order to save the CAPEX (CAPital EXpenditures) of the natural fuel gas supply system of the main boiler, a system optimization design was conducted to reduce the number of equipment and reduce the capacity of the equipment. In this paper, newly developed GMS were developed to achieve the unmanned automatic operation control system, Unmanned GMS Control System (UGCS), including the parallel operation control system between the LD (Low Duty) compressor and the forcing vaporizer, the parallel operation control system between the LD compressors, and the cargo tank pressure control system.