ANSYS Fluent for Modeling Sootblower Jets Shahed Doroudi 1 , Markus Bussmann 1 , Danny Tandra 1 and Honghi Tran 2 1 Department of Mechanical & Industrial Engineering 2 Department of Chemical Engineering & Applied Chemistry University of Toronto Email: shahed.doroudi@mail.utoronto.ca ABSTRACT Sootblower jet effectiveness is a strong function of the force exerted by a jet on a fireside deposit, that depends strongly on the local deposit and tube geometries. In the superheater section of a recovery boiler, the spacing between platens is generous and so sootblower jets have easier access to deposits. Tubes in the generating bank and economizer sections are much more closely spaced, and so jet access to deposits on tubes beyond the first row is limited. In either case, the interaction of a supersonic steam jet with tubes and deposits is a complex phenomenon. Research at the University of Toronto over the past decade has examined the dynamics of sootblower jet interaction with tube geometries characteristic of a recovery boiler. The work has involved both experiments and CFD (computational fluid dynamics) analyses. The early CFD studies employed a research code that was difficult to apply to more complex geometries. Recently, turbulence model corrections that were developed during that time have been incorporated into ANSYS Fluent version 14.5, allowing us to examine more complex jet/tube interactions in the generating bank and economizer sections. This paper presents an overview of our latest work on developing those models, and in particular how to specify an inlet boundary condition at the sootblower jet nozzle that will yield both Mach number and pressure distributions within an off- design jet that agree well with experimental data. 1. INTRODUCTION Sootblowers operate within a kraft recovery boiler to knock deposits off of heat transfer tubes. A sootblower is a lance tube with two radially opposed nozzles producing two supersonic steam jets capable of exerting enough force to dislodge and erode deposits and keep them from building up. These jets can consume 10% or more of the steam generated by a boiler, and thus represent a significant cost to the operators. The supersonic nozzles on the lance tube are intended to operate at a certain design pressure, creating a fully expanded jet. However, fluctuations in the supply pressure will cause the nozzle to produce an underexpanded/overexpanded jet. An important characteristic of these “off-design” jets is the formation of multi-cell shock structures in the jet core. Figure 2 illustrates an underexpanded jet adapting to the ambient pressure. Figure 1. The lance tube rotates in between tube platens; the supersonic sootblower jets attempt to remove accumulated deposits. Figure 2. Multi-cell shock structure of an underexpanded jet [12].