Scanners are familiar tools for rotary kiln operators. They have become standard across many industries and help operators monitor the temperature of the shell, providing real-time information and warnings about hot spots, excessive coating inside the oven, insufficient tire slip, and more.
Kilnscan scanners offer a unique feature to preserve equipment life and increase production efficiency: Thermal Bias calculation. This function evaluates in real time the tendency of the shell to warp due to thermal inhomogeneities on the shell surface.
Combined with the rotation and load of the furnace, the tendency to bend causes cyclic bends and loads that reduce the long-term reliability of the furnace. This creates unsymmetrical load fluctuations on the tires and rollers and can cause the tires to warp. Periodic bending of the shell, even if their amplitude is small, creates local oval distortions that put pressure on the inner coating, reducing its life. In addition, the drive system of the furnace is also subjected to cyclic stresses that can cause excessive fatigue loads.
If not detected and corrected in time, Thermal Stretch can develop into permanent damage and shell deformations that can only be diagnosed during furnace alignment operations performed every few years. It also accelerates the aging and wear of the entire furnace drive mechanisms and support structure.
KILNSCAN scanners detect regions of thermal inhomogeneity because they precisely measure the temperature at each point. This enables HGH's Thermal Bias Monitoring algorithm to provide real-time information about the tilting tendency of the crustal axis. The operator is presented with a graph showing the amplitude of potential lateral movement of the shell along with an animated view of the furnace axis. The operator can take quick corrective actions, such as adjusting the rotation speed, changing the geometry of the flame, or adjusting the raw material mixture to ensure uniform coating.
With Thermal Bias Monitoring, KILNSCAN's contribution goes beyond just real-time refractory and process monitoring; It also supports short-term actions to prevent long-term wear and damage to the furnace.
The medium- and long-term evolution of Thermal Bias data provides information on process evolution within the furnace; This includes processes such as the development of coatings, unburned material thrust and flame adjustment. It can also be a valuable indicator of the mechanical and thermal stresses on the shell and tires, as well as the load fluctuation that each foot supports.
When combined with Tire Slip Monitoring, i.e. measuring the gap between the furnace shell and the support tires, Thermal Slip monitoring helps evaluate shell geometry, degree of deviation (ovacity), eccentricity and misalignment.
