Influence of wind on seepage of gases through the shell of smoke stacks

Abstract

The effect of wind on the distribution of static pressure at the outer surface of thermal power station smoke stacks is considered. It is shown that the wind velocity and direction are the main factors influencing on the seepage of gases through the shell of smoke stacks when no excess static pressure is exerted from the side of flue gases. A procedure for determining the wind influence zone on the seepage processes in smoke stacks is proposed. This procedure supplements the previously adopted approach for estimating the operating modes of smoke stacks taking the influence of wind into account. The proposed procedure is used for determining if seepage of flue gases is possible and for finding the wind influence lower boundary for different operating conditions. The described procedure can be used in designing new smoke stacks and in repairing and retrofitting existing ones, and also in developing new techniques for revealing through flaws in smoke stack shells during their examination by means of an infrared imager. As an example, the results from infrared flaw detection of a smoke stack are presented, which testify that a change occur in the direction of seepage processes taking place in a reinforced-concrete shell when a change occurs in the wind effect pattern.