Numerical Investigation of Ash Particles Deposition and Distribution in a Refining and Chemical Wastewater Incineration Equipment

In this paper, numerical investigation has been performed to predict ash particles impaction and distribution tendencies in a heat recovery steam generator (HRSG) of an industrial refining and chemical wastewater incineration plant. A two-dimensional mathematical model with a six-row staggered arrangement has been built in order to study gas-particle two-phase flow in the HRSG, and the effects of ash particle size, flue gas velocity, longitudinal tube pitch and spanwise tube pitch on ash particle impaction efficiency were investigated. Overall, all parameters played important roles in ash particle impaction performance except longitudinal tube pitch. The results showed that large particles mainly impacted on the windward side of the first two rows of tubes, while small particles impacted on both windward and leeward sides forming a uniform distribution. Enhancing the particle size and flue gas velocity contributed more ash particles to impact on the heat transfer surfaces, moreover, 20 μm particles were much more sensitive to fluid velocity compared with 0.2 μm particles. As for spanwise tube pitch, the results indicated that it had an obvious effect on decreasing the impaction efficiency with an increase of spanwise tube pitch, while with the increase of longitudinal tube pitch, the impaction efficiency declined slightly.