A study on the adaptability of cyclone barrel to slag film in a cyclone-fired boiler

Abstract

The behavior of slag film inside the cyclone barrel is closely related to its design and operation. In this paper, a multilayer wall model considering the heat transfer from flame to working fluid in the water-cooled tubes was proposed and a judgment criterion was established to evaluate the adaptability of cyclone barrel to slag film. Furthermore, parametric investigation was carried out systematically to analyze the influencing factors of the adaptability, including design parameters (barrel diameter, thickness of refractory lining), operating conditions (excess air ratio, temperature of preheated air) and coal properties (ash content, coal slag temperature of critical viscosity). The results indicate that the molten slag can plug the slag tap at low loads while erode and corrode the refractory lining severely at high loads for a cyclone barrel. There is a load range within which the cyclone barrel operates safely and steadily. The thickness of refractory lining and coal slag temperature of critical viscosity are the key factors affecting the adaptability significantly. The adaptability descends as the thickness of refractory lining increases and a lower coal slag temperature of critical viscosity leads to a decrease in the adaptability. The effects of other factors are relatively small. Especially for barrel diameter, its impact can be disregarded. The conclusions in the present study are helpful to the optimization design and safety operation of cyclone barrels.