Water vapor distribution and particle condensation growth in turbulent pipe flow

Abstract

Heterogeneous condensation is a potential particle size-increasing technology that is progressively used in dust removal. In this paper, the condensation growth of fine particles under turbulent pipe flow was investigated. A numerical model was established and verified in terms of gas flow field, relative humidity, and particle size. Results showed that the particles in the center were larger than those in the near-wall area at the outlet of pipe. The mechanism for such improvement was analyzed. The relative humidity in the pipe was nonuniformly distributed, and this was because the low diffusion coefficient of the central water vapor could not effectively supplement the water vapor consumption caused by wall condensation. Furthermore, to achieve superior particle growth, three different spoilers were used to change the gas flow field and water vapor in the pipe. The results indicated that when the spoiler was in the middle, the average particle size increased and the standard deviation decreased, demonstrating an improvement for particle growth. In this case, the changed effective diffusion coefficient of water vapor in the central region can make up for the wall condensation loss without excessive transmission. Consequently, better particle growth was achieved, which was more favorable to particle removal by subsequent equipment. These findings establish theoretical guidance for the treatment of fine particles in the industrial process.