Analysis of the Benefits of TPP’s Three-Barrel Smokestacks

The structures of three- and four-barrel smokestacks are compared using the method of total discounted costs. It was revealed that three-barrel stacks are more profitable than four-barrel ones in almost the entire range of used smokestack characteristics with modern cost ratios. Formulas are given for calculating the diameter of the smokestack casing with two identical bores and a third, different in size. A technique has been developed for calculating the diameter of the casing of a three-barrel stack with bores of various diameters. In all compared variants, the same distances were laid between adjacent bores and the barrel and casing. For the first time, a methodology has been proposed for choosing the optimal dimensions of a three-barrel smokestack taking into account the individual conditions of gas transport along each barrel, allowing one to find the optimal distribution of gas velocities over bores of a three-barrel stack and to calculate the minimum total discounted costs for smokestacks with bores of different diameters, flow rates, and gas temperatures in them. It is shown that taking into account the hydrodynamic features in the bores with different gas velocities allows us to propose solutions that reduce the total reduced costs by 7–8% compared to traditional solutions. In the event that the optimal solution is to provide different speeds in the bores, then it is necessary to install confusers on each bore with individual and sufficient small angles of narrowing in order to prevent uneven velocity fields at the mouth of the smokestack and possible vortex formation when the flue gas flows from different bores merge when the stack is operating at maximum load.