| In order to meet increasingly strict environmental requirements,more and more large container ships have adopted dual fuel engines.To ensure smooth operation of dual fuel engines in gas mode,a ship needs to be equipped with an LNG vaporization heat exchange system to convert the liquid LNG stored in the tank into gaseous natural gas to provide fuel for the dual fuel engine.However,the international and national common LNG vaporization heat exchange systems currently have existing problems such as complicated system design and high manufacturing costs.Therefore,this thesis takes the LNG vaporization heat exchange system as the research object,and conducts research based on the 14000 TEU dual fuel container ship project which built by a shipyard in Jiangsu Province,the specific research contents are as follows.To conduct the research on the LNG vaporization heat exchange system,including the deep research on system composition,process flow design,and six key equipment within the system;The water glycol system as the auxiliary system for LNG vaporization heat exchange system,has been innovatively designed and patented in this project,a new type single set of water glycol system design has been adopted to replace the two sets of water glycol systems on conventional dual fuel ships to meet the system use.At the same time,the design,configuration,and performance analysis of the new and conventional water glycol systems have been completed,and it is concluded that the new water glycol system can reduce manufacturing cost about 40%also can save energy consumption about 28%.The core equipment in the LNG vaporization heat exchange system,namely the LNG vaporizer,is calculated,selected,and studied.The traditional LNG vaporization and heating in the industry mostly use first stage vaporization and second stage heating methods,and the vaporization and heating processes are completed separately in two heat exchangers.The LNG vaporizer used in this system adopts a one-stage vaporization and heating method,the vaporization process and heating process are completed in one go.Through the calculations of theoretical heat transfer,logarithmic mean temperature difference,and heat transfer area to select the LNG vaporizer mode of PSHE 6LL-234/3/3 in this system.Aspen HYSYS software is applied to model and simulate the process flow of LNG vaporization heat exchange,simulation includes main engine high load condition,main engine low load condition,and LNG vaporizer.Based on the simulation result and combined with the analysis of ship’s actual testing data,the design of LNG vaporization heat exchange system and LNG vaporizer selection calculation are finally verified. |
