Study On Heat Transfer Mechanism Of Heating And Heat Preservation Processes In Oil Tanker

Oil is the life line of the economy,and the steady development of economy and the steady of social are based on the oil.In the transportation of oil,because of the large viscidity,the pour point is high,which causes the problem of taking the oil off,so the oil needs warming when been taken off.The mean of warming is vapor nowadays. Considering the economy,if the time of warming is too early or the temperature is too high,the economy of the ship is low;and if the time of warming is too late or the temperature is too low,it is difficult to take the oil off.So according to the equipments and loading condition of every ship to grope for a heating method which is safe, conveniently operated,time saving and fuels saving is very important.An oil heating method of the double hull oil tanker is studied by means of combination of theoretical analysis,experimental validation and application verification. This method is fit for twenty-four kinds of crude oil which are transported by the 68000DWT,72000DWT and 159000DWT double hull oil tankers in DALIAN OCEAN SHIPPING COMPANY.The oil tanker heating model is established and the software is developed based on transient heat conduction gathered parameter method.The validity of heat transfer model used in the software is proved by experiment.Theoretical analysis and experimental study show that in the oil heating process,natural convection is the dominant heat transfer style.The application shows that the max deviation of calculated heating time is 8%.The relationship between vapor parameter and heating economy is discussed.The rule is that:When heating the oil,the temperature increasing degree has relationship with the inherent character of the oil.The oil temperature will increase smaller than before if the value of density or specific heat at constant pressure becomes higher.It varies directly as heat transfer coefficient.In this article dynamical viscidity and heat expand coefficient have little influence on the increase of fuel oil temperature.So they are ignored.The temperature of sea water and atmosphere do not have direct influence on the increase of fuel oil temperature.The function of the boiler evaporation and the heating time,the optimized vapor flow rate at different pressure are established,which supply the theory basis for the ship transportation.When the vapor parameters are follows,the optimized vapor flow rate is:0.4MPa,144℃,controllable vapor flow rate,below 4000(kg/h);0.5MPa,152℃,controllable vapor flow rate, 4000---5000(kg/h);0.6MPa,159℃,controllable vapor flow rate,about 5000(kg/h); 0.8MPa,170℃,controllable vapor flow rate,below 4000(kg/h).