Analysis of Crack Growth in the Wall of an Electrolyser Compartment

Abstract

Electrolysis units are widely used in different branches of industry. They are high-pressure tanks, each having a chamber and electrodes placed therein, which are arranged in assemblies, a cover as well as an inlet and outlet pipes. High requirements are imposed on their technical characteristics, confirming the urgency of the problem of improving calculation methods. To simulate the kinetics of the thermally stressed state in elements of power plants with complex rheological characteristics of the material and taking into account its damageability, a special technique and software complex have been developed on the basis of the finite element method, which allow solving a wide class of nonlinear nonstationary problems in a three-dimensional formulation with simultaneous consideration of all operating factors. The kinetics of the crack was studied using the method of calculating the survivability of structural elements, which is based on the principles of brittle fracture mechanics, while the plastic zone at the crack tip is assumed to be small compared to the crack size, and the crack kinetics is determined by the stress intensity factors at crack tips. The technique is based on calculating the kinetics of the crack to its critical dimensions, when an avalanche-like destruction of a structural element occurs, or a crack grows through the thickness of the element. The kinetics of a semi-elliptical crack emerging on the inner surface of the cell wall was studied under the action of static and cyclic loading. With the use of the developed technique, computational studies of the thermal stress state of the upper part of the electrolyser cell were carried out. The results obtained show that the cylindrical part of the cover is the most loaded. There have been carried out studies of the development of an internal surface semi-elliptical crack, which originated in this zone. It was found that with a small number of cycles per year, the crack will grow for a long time to a certain depth, then the rate of its growth from static loading will increase so quickly that the growth of the crack from cyclic loading can be neglected.