656 / 2019-04-22 14:26:31

Experimental Research on Effective Thermal Conductivity of Ash Particles in Coal-fired Boiler

effective thermal conductivity, ash deposited, ammonium bisulfate (ABS), Waste Heat Recovery System (WHRS), denitrification

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The ash deposited is the major concern when evaluating the performance and reliability of tail heat exchanger of coal-fired boiler. Wherein, the effective thermal conductivity of ash particles is one of the most important parameters determining the heat transfer through deposit. In this paper, experiments and analyses have been carried out to investigate the influence of denitrification and flue gas Waste Heat Recovery System (WHRS) on effective thermal conductivity of ash particles by parallel hot-wire method. The results show that with use of SCR/SNCR, ammonium bisulfate (ABS) produced contributes to the increase of effective thermal conductivity of ash particles, which can be divided into two zones according to the action mechanism of ABS. With use of WHRS, effective thermal conductivity of ash particles goes up with the increase of SO3 content when the flue gas temperature is lower than the Acid Dew Temperature (ADT), and the higher SO3 content has a stronger effect on it. Furthermore, the formation of liquid sulfuric acid and ammonium bisulfate promote the accumulation between particles, and then increase the particle size, which in turn enhances the effective thermal conductivity.