Research On Electrostatic Distribution Law In Large Steel Storage Tank By Finite Difference Method

Since the demand for oil is steadily on the increase with the rapid growth of global economy, sizes of storage tank and tank field become larger and larger in the past few decades. At the meantime, the problem of electrostatic prevention caused more and more attention for various electrostatic fire and explosion of storage tank happened frequently.The work presented in this thesis focuses on the problem of electrostatic potential distribution in large steel storage tank by the finite difference method combined with structural characteristics of storage tank. Five good results were obtained as follows, (1) According to electrostatic theory, characteristics and jeopardize of oil static electricity were analyzed, the approach to study the problem of electrostatic potential distribution in storage tank were discussed, and analytical solution of electrostatic potential distribution in storage tank was deduced using separation of variables. (2)Mathematical model of electrostatic potential distribution in storage tank was built, numerical calculation formula was deduced with the finite difference method and over-relaxation iterative method and Matlab calculation program was written whose validity was verified by the analytical solution. (3) Numerical calculation on electrostatic potential distribution in vertical cylindrical large steel storage tank was made, the condition of electrostatic distribution in storage tank was analyzed quantitatively in terms of electrostatic potential distribution and influence of storage tank and oil parameter on electrostatic potential distribution. (4) Dispersion and accumulation law of electrostatic charges in storage tank was studied during the process of oil being filled into storage tank. (5) Dangerous conditions of static electricity in storage tank were analyzed. Elimination techniques and protective measures of static electricity in storage tank were discussed, including controlling criticality of environment, controlling the process, grounding, increasing relative humidity, adding antistatic agent, using static electricity neutralizing implement and so on. These electrostatic distribution theories on storage tank, which were obtained by numerical calculation with the finite difference method, would further deepen the understanding of electrostatic distribution condition and provide theoretical basis for electrostatic safety protection of storage tank.