Abstract: The slag deposited on the wall tubes of furnaces/boilers seriously reduces the heat transfer from the furnace to tubes and degrades the tubes by corrosion. During boiler operation, slag deposits are removed by sootblowers that blast the deposits with steam or air jets. In this study, we develop a novel numerical model using the cohesive zone method (CZM) and coupled Eulerian– Lagrangian (CEL) analysis to investigate the dynamics and mechanism of deposit fracture during sootblowing. Cohesive elements subject to the softening traction–separation relationship and evolution laws are embedded into the deposit model to describe crack formation during deposit breaking. The deposit cracking status is evaluated by extracting the scalar stiffness degradation variable from damaged cohesive elements. The dynamic process and mechanism of deposit fracture are analyzed and revealed in detail, particularly in terms of the destructive degree and fracture rate of the deposit model. The effects of the sootblowing steam pressure (0.9–1.8 MPa) on slag breaking, wall tube stress, and steam consumption are also investigated. Sootblowing steam pressures over 1.2 MPa do not further benefit the sootblowing effect but adversely affect the wall tube lifetime.

Key words: Sootblowing; Boiler; Numerical model; Cohesive zone method (CZM); Deposit fracture

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