Research On Key Technologies Of LNG Fuel Supply System For 16300DWT Dual Fuel Power Chemical Tanker

The Annex VI of the Anti-fouling Convention promulgated by the International Maritime Organization clearly requires that the NO_x emission standards for marine engines be increased from Tier II to Tier III.Therefore,the current marine power fuel gradually uses liquefied natural gas?Liquid Natural Gas referred to as LNG?,and LNG fuel can be reduced.10%²0%of CO₂ emissions,90%of NO_x emissions,100%of sulphide and particulate emissions.The demand for LNG/diesel dual-fuel powered ships at home and abroad has increased year by year,and has increased by about 60%in the past three years.The gas supply mode of dual-fuel powered ships is mainly divided into two types:low-pressure gas supply and high-pressure gas supply.The fuel gas supply system is mainly composed of a storage module,a transport module,a booster module,and a heating vaporization module.The disadvantages of the high-pressure fuel gas supply system are high inlet pressure requirements,complex systems,and high construction costs.The low pressure fuel gas supply system is simple in operation and low in maintenance cost.The storage device,equipment has compactness and good protection performance,reducing the area occupied by the entire system on dual fuel ships.This article takes the 16300 DWT dual-fuel chemical tanker as the research object,according to the gas supply requirements of the ship's dual-fuel main engine model,theoretically design and calculate the storage module,transport module and heating vaporazation module of the low-pressure fuel gas supply system,and study the corresponding construction process.The LNG storage module is mainly an independent C type LNG storage tank,and the container capacity and geometrical size of the storage tank are calculated.According to the29-day long duration of the ship's life,the volume of the LNG storage tank is calculated to be300m³×2.The total depth of the head of the inner container of the LNG tank is 1315mm,the height of the straight edge of the head is 115mm,the length of the inner tube is 70m,the wall thickness of the inner container is 14mm,and the wall thickness of the elliptical head is also14mm.The total head depth of the LNG tank shell is 1390mm,the height of the straight edge of the head is 40mm,the inner diameter is 5378mm,the cylinder length is 16976mm,the wall thickness is 14mm,and the elliptical head wall thickness is also 14mm.The LNG transport module is mainly a LNG low pressure booster pump and a water glycol transfer pump.The mass flow rate of LNG under rated conditions is calculated to be864 kg/h,the LNG pump shaft power is 5.09 kW,and the rated power of the associated motor is 15 kW;the mass flow rate of water glycol is 24874 kg/h.The diol pump shaft power is4.96kW and the rated motor power is 6.2kW.LNG heating vaporization module is mainly LNG vaporizer and water glycol plate heat exchanger.The power calculated by the design was calculated to be 228kW for the LNG vaporizer,292kW for thewater glycol heat exchanger,and 1.052×10⁶kJ/h for the water glycol heat exchanger.According to the theoretical calculation results,the equipment selection for the low-pressure fuel gas supply system is complete,and the design and description of the system schematic diagram of each auxiliary system are connected with the LNG fuel gas supply system.In addition,the design,manufacture and installation process of the LNG double-wall pipe ventilation pipe system and LNG filling system are described in detail.The basic operation flow of the fuel gas supply system is outlined.The process simulation simulation of the forced vaporization module is based on Aspen HYSYS.The heat exchange area of the LNG shell and tube heat exchanger is calculated and calculated to be26.38 m².Then the effect of changing the water concentration of ethylene glycol in the intermediate medium is studied.The inlet flow rate and inlet temperature of water glycol,cooling water inlet temperature and inlet flow rate of the liner,and the effect on the temperature change after vaporization of LNG,simulation results show that:when 50%concentration of water glycol is used,the inlet temperature is 25°C,the inlet flow rate is20000kg/h,and the temperature is-162.5°C.The LNG vaporization is heated to-17.74°C,and the NG heater is heated to 25°C twice to meet the main engine inlet temperature and inlet pressure requirements for the 16300 DWT dual fuel power chemical vessel.This article is based on the example of 16300 dwt chemical tanker,combining theoretical analysis with simulation experiments and real ship verification to complete the design of fuel gas supply system.It has great application in other types of dual fuel ships such as bulk carriers,cruise ships and passenger ships.Prospects and technology for reference.