Abstract:

Coal-fired power plants' coal handling systems generate substantial dust during operation. Improper purification treatment will cause severe environmental pollution. On the basis of research on water bath dust removal technology and spray string grid dust removal technology, this paper proposes a novel combined water bath dust collector integrating impingement water bath and spray string grid. The factors influencing the dust removal efficiency are analyzed by conducting numerical simulations on each dust removal stage. The results indicate that for the cross-section of the impingement water bath section, the higher the wind speeds and the deeper the initial immersion water depth of the air duct, the more intense the liquid fluctuation, correspondingly increasing dust removal resistance. In terms of spraying, the particle size of the ejected liquid droplets decreases with the increase of atomization pressure; however, an excessively high pressure leads to droplet agglomeration and an increase in particle size, resulting in a decline in dust removal efficiency. For the string grid, a local double-row string grid model is established to simulate the velocity and pressure field. The resistance loss is concentrated in the front and rear areas of the double-row string grids, and the high and low wind speed areas of the airflow are alternately distributed, forming a negative pressure zone. With the increase of wind speed, the negative pressure range expands accordingly, which is conducive to the formation of a water film on the string grids but also causes an increase in dust removal resistance at the same time. The combined design proposed in this paper integrates multiple purification mechanisms such as impingement water bath and spray string grid, and features high efficiency, low energy consumption and easy maintenance. It is particularly suitable for the dust environment with high-concentration and multi-particle size in the coal handling system, solving the problem of low removal efficiency of micron-sized dust by traditional mechanical dust collectors, and providing a modular solution for dust removal in coal handling system.

Key words: wet de-dusting, impingement water bath, spray string grid, numerical simulation, coal handling system