Numerical Simulation And Analysis Of Energy Consumption Of GHA_70A Type Tanker Heating Unloading

With the rapid development of China's polyester industry, p-xylene market demand will continue to increase, GHA_70A tanker become PX terrestrial transmission and transported to the main traffic tools so as to fulfill the efficient operation of the PX transportation and storage. At low ambient temperatures, the viscosity of PX becomes larger and the crystal is produced. When the tanker arrived at the company warehouse for unloading, in order to make the PX melt and viscosity reduction, accelerate the speed of unloading and turnover of tanker, it must be heated to satisfy the unloading requirements of PX tanker. Taking the heating unloading of GHA_70A type p-xylene tanker as the research subjects, carried out field experiments and numerical simulation of the heating process.Some problems in traditional heating calculation theory, such as the calculation that the thickness and quality of the solidified layer is not accurate, low temperature unloading. Based on the actual situation of the tanker, the traditional heating calculation theory was modified and improved. Determine the reasonable heating calculation theory, used to guide the field heating operation and provide theoretical basis.In the condition that steam pressure is 0.3MPa and steam flow is 476.5kg/h, the tank car heating process is simulated by using numerical simulation software ANSYS and compare with antipyretic experiments in the field. Turn out that the average temperature of the numerical and experimental is basic equal and the maximum relative error is 2.87%. The average temperature has a linear relationship with time. There is no difference in the average temperature between the two and three dimensional numerical simulation, but the temperature and speed is not the same at any moment during the heating process. So it is necessary to use the three-dimensional model to observe the flow behavior of PX during the heating process. The temperature of the experimental temperature measuring point is equal to the temperature of the simulated characteristic point and the maximum temperature difference is 3.84 C°, which illustrates the correctness of the model selection and calculation method. The PX melting liquid fraction is linearly related with the heating time, and it can be used to predict the heating time required for the melting of PX with different thickness.Under different conditions, the temperature rise rate, the change of temperature distribution with time and energy efficiency are studied. The results indicate that the temperature distribution along the axle of the tank is not uniform, and the temperature near to the heat source is higher and the temperature next to the end of the tank is lower, which indicates that the thermal conductivity of PX is poor. The temperature should be the most disadvantageous section as the control points of heating process of unloading, which overtook PX the freezing point temperature and has been completely melted can stop heating. The average temperature of PX in the tank has a linearly relationship with the heating time, and the average temperature of the working condition 1?steam pressure is 0.25 MPa, steam flow rate is 420kg/h? to 4?steam pressure is 0.40 MPa, steam flow rate is 580kg/h? is gradually increased at the same heating time. The average temperature of PX in the tank is fitted by linear fitting, and the temperature rise rate which is increased from condition1 to condition4 is obtained. The above variables are related to the operating conditions, the greater the steam pressure and steam flow, the greater the value of the variable. Condition 3?steam pressure is 0.35 MPa, steam flow rate is 532kg/h? is the best heating condition which is the highest energy efficiency, good energy-saving effect and relatively shorter heating time.According to the above research conclusion that can predict the time required for each stage of heating, the reasonable control of the steam pressure and steam flow so as to reduce energy consumption and the cost of heating, and lay the theoretical foundation for the further research.