The Static And Dynamic Numerical Analysis Of Cylindrical Digester

With the rapid development of our country, the disposal of sewage becomes an important demand of most cities.While the sludge digesters are the necessary segment of the disposal of sewage in large sewage treatment factories. Although cylindrical sludge digesters have been wildly used in our country, the systemic analysis and study about the digester are scarce,especially the dynamic analysis. The main work in this paper is as follows:(1). According to the classic theory of thin shells, the model of a cylindrical sludge digester is established and the analysis of static state is done. Through calculating the model of cylindrical sludge digester under five cases of the compounding of static loads, the conclusion that the temperature and hydrostatic are the controlled loads in the phase of designing vertical bars is obtained.(2). In the mode-frequency analysis, the hydrodynamic pressure is simulated by the added-mass which is calculated by virtually equating the hydrodynamic pressure to the equivalent acceleration force acting on the sludge digester. Then the natural frequency in the condition of wet modes is attained, and the conclusion that the natural frequency of the digester full of liquids is lower than the empty digester. However, the influence of liquids on the natural frequency is neglected while the liquid is less equal than half cubage of the digester.(3). In the seismic analysis, we separately analyze the dynamic response of a sludge digester under the artifical wave and Taft wave. The hydrodynamic pressure changing with time about a certain seismic wave can be obtained by analytical method. With the APDL language, we make the hydrodynamic pressure and the seismic wave synchronously apply on the structure, and then the time-history analysis is realized by programming. We can come to the conclusion that the shape of the seismic wave has an apparent influence on the values of hydrodynamic pressure and internal forces.