Experimental study of the fouling characteristics in a pilot‐scale facility: Influence of the fouling surface

Abstract

Fouling on the heat transfer tube is one of the most serious problems in the boiler for its low thermal conductivity. The fouling characteristics in a pilot‐scale facility were investigated, including the influence of the fouling surface. The digital image technique was utilized to study the growth characteristic of the fouling deposit. Meanwhile, the heat flux through the heat exchange tube was calculated. The X‐ray diffraction and scanning electron microscopy (SEM) were applied to investigate the mineralogy and microstructure of the deposits. The results showed that the modified surface could inhibit the fouling and promoted the shedding processing of fouling deposit. The average thicknesses of the fouling deposits decreased as the deposition surface was modified with ceramic coating. In addition, the average heat fluxes of the two cases were 183.15 and 226.35 kW/m2 for two cases (noncoating and ceramic coating), respectively. The reduction mechanisms of the fouling deposit were studied. We observed that the modified surface had negative impacts on the content of alkalis, which strongly affected the adhesion behavior. According to the SEM images, the deposition presented a more porous structure with the ceramic coating. This research provides the guidance for mitigation of the fouling in boilers.