Experimental Study on Ash Deposition and Resistance Characteristics of Wet Air with Ash Particles across Finned Tube Bundles

In this paper, aiming at the problem of waste heat recovery of the gas with water vapor and ash particles, represented by the lignite dryer exhaust, the mixture of air, water vapor and ash particles was used to simulate the real gas, and an experimental system of the mixture vapors across finned tube bundle was built. The effects of the ash particle concentration, water vapor mass fraction and mainstream inlet temperature on ash deposition and resistance characteristics were obtained. The experimental results showed that, the resistance coefficient increased with the increase of the ash particle concentration and mainstream inlet temperature, and reduced with the increase of the water vapor mass fraction. Especially, the effect of the ash particle concentration was significant. When it increased from 1.5 g•m^-3 to 12.8 g•m^-3, the average resistance coefficient increased from 0.07 to 0.46, with an increase of about 536%. The ash deposition showed the same trend with the resistance coefficient. When the ash particle concentration was larger than 7.7 g•m^-3, the ash deposition was severe, even blocked the flow channel, and should be cleaned in time.