Simulation Of Integrated Automation System Of Liquid Cargo Handling Simulator Of LNG Carrier

As represent of clean and efficient energy, natural gas is favored by the world. At present, natural gas would be liquefied at low temperature (-162℃), then transported by professional liquefied natural gas carrier. Because of potential risk of extremely low temperature, inflammable and explosive, liquefied natural gas carrier is more complicated and has higher requirement of security. As one of key technologies of liquefied natural gas, Integrated Automation System (IAS) can improve the transportation capacity, and it makes sure that liquefied natural gas carrier’s operation in security.This paper analyzes the composition of IAS on LNG carrier based on LNG liquefied cargo handling simulator introduced from Norway. The control computers in the cargo control room are center of overall system. It receives cargo tank level, temperature, pressure signal, and exchanges data by field bus and valve remote control system. Further, it collects and calculates the data to control the whole system. The system is put into practice by Visual Basic6.0, and integrated with the developing LNG carrier cargo handling simulator in Dalian Maritime University.The mathematic model of cargo tank is built in this paper. It takes the gas volume above the tank as control volume. The temperature, pressure and level are monitored in real-time. Custody transfer measurement system can calculate the volume exactly, so trade could be carried out easily. Valve remote control system can control the hydromantic driving unit, valves, gather data from cursors. It can also control cargo pump and ballast pump. In cargo carrying process, cargo tank continues absorbing heat from outside, and LNG becomes into gas. This results in a higher pressure in cargo tank. The low duty compressor should be controlled to ensure safety by the system. Eventually, CTMS and valve remote control system come true in this paper. The cargo tank pressure also be kept in secure arrange during the cargo carrying process. The mechanism model is built in the paper. In loading process, cargo tank pressure is kept in certain value by using high duty compressor. At last, this paper verifies the model by using MATLAB, and plots simulation curve.