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ABSTRACT
A numerical simulation coupled with the user-defined function (UDF) is conducted on a cyclone-fired boiler. The thermal boundary condition is established for the cyclone barrel. The effects of the temperature of critical viscosity and the refractory material thickness on slag behavior are investigated. The results show that the temperature of critical viscosity is closely related to the location where the slag begins to form in the cyclone barrel. The refractory material thickness remarkably influences the surface temperature of the refractory material, and the solid slag thickness adapts to the variation of the refractory material thickness.
Nomenclature
| g | = | gravity acceleration, m/s2 |
| krm | = | thermal conductivity of the refractory material, W/(m · K) |
| ks | = | thermal conductivity of the solid slag, W/(m · K) |
| kw | = | thermal conductivity of the wall, W/(m · K) |
| = | mass flow rate of the liquid slag, kg/(m2 · s) | |
| = | mass flow rate of the trapped particles, kg/(m2 · s) | |
| qin | = | heat transfer rate per unit area, W/m2 |
| qloss | = | heat flux to the coolant, W/m2 |
| = | heat transfer rate per unit length, W/m | |
| T0 | = | water coolant temperature, K |
| Tcv | = | temperature of critical viscosity, K |
| Trm | = | surface temperature of the refractory material, K |
| Ts | = | surface temperature of the liquid slag, K |
| Tw | = | surface temperature of the wall, K |
| u | = | slag velocity, m/s |
| UDF | = | user-defined function |
| UDMs | = | user-defined memories |
| vl | = | flow velocity of the liquid slag, m/s |
| VOF | = | volume of the fluid |
| Greek symbols | = | |
| δl | = | liquid slag thickness, m |
| δs | = | solid slag thickness, m |
| δrm | = | refractory material thickness, m |
| δw | = | wall thickness, m |
| μ | = | slag viscosity, Pa/s |
| ρ | = | slag density, kg/m3 |
| τ | = | shearing stress on the liquid slag surface, Pa |
Nomenclature
| g | = | gravity acceleration, m/s2 |
| krm | = | thermal conductivity of the refractory material, W/(m · K) |
| ks | = | thermal conductivity of the solid slag, W/(m · K) |
| kw | = | thermal conductivity of the wall, W/(m · K) |
| = | mass flow rate of the liquid slag, kg/(m2 · s) | |
| = | mass flow rate of the trapped particles, kg/(m2 · s) | |
| qin | = | heat transfer rate per unit area, W/m2 |
| qloss | = | heat flux to the coolant, W/m2 |
| = | heat transfer rate per unit length, W/m | |
| T0 | = | water coolant temperature, K |
| Tcv | = | temperature of critical viscosity, K |
| Trm | = | surface temperature of the refractory material, K |
| Ts | = | surface temperature of the liquid slag, K |
| Tw | = | surface temperature of the wall, K |
| u | = | slag velocity, m/s |
| UDF | = | user-defined function |
| UDMs | = | user-defined memories |
| vl | = | flow velocity of the liquid slag, m/s |
| VOF | = | volume of the fluid |
| Greek symbols | = | |
| δl | = | liquid slag thickness, m |
| δs | = | solid slag thickness, m |
| δrm | = | refractory material thickness, m |
| δw | = | wall thickness, m |
| μ | = | slag viscosity, Pa/s |
| ρ | = | slag density, kg/m3 |
| τ | = | shearing stress on the liquid slag surface, Pa |