Simulation of the thermal-acoustic coupling inside an industrial hazardous waste incinerator

To analyze the coupling between combustion reactions and the natural acoustic behavior of a reactor, a transient LES based CFD code has been used. Previous transient analysis of ignition inside large process heaters, of multi-tipped elevated gas flares and waste incinerators has shown the ability of the LES based CFD code called C3d. Initially, this code was used to model pool fires [1] but more recently has been used to study wind effects on ignition of multi-point ground flares (MPGF) [2]. The LES based CFD code has also been used to investigate transient operation of incinerators and process burners [3]. The work reported in this paper extends previous work to explore the transient behavior of process equipment including burners, flares, and incinerators to consider the more complex coupling between turbulent combustion inside an incinerator with the natural acoustic behavior of the combustion chamber itself. The code used is fully compressible and capable of predicting the propagation and amplification of pressure waves in confined spaces. Results from this work show a pressure wave inside an incinerator (see Figure 1). This problem can be remedied by changing the burner location with respect to the chamber or by adding flow resistance at the exit. The left-hand plot shows gas pressures at 3 locations along the burner/furnace center line with an approximate amplitude of 1,000 Pa. The plot also shows an oscillating exit pressure with a 100 Pa magnitude.