Analysis of Flow-induced Noise Characteristics of Ethylene Cracking Furnace Tubes before and after Coking

Abstract

This paper presents a comprehensive investigation of flow-induced noise characteristics in ethylene cracking furnace tubes, covering both pre- and post-coking conditions. Large-eddy simulation (LES) was employed in conjunction with a generalized Lighthill’s acoustic analogy model. The results indicate that noise sources can be classified as dipole acoustic sources, with energy primarily concentrated ranged from 300 to 1500 Hz, in comparison to standard conditions. The primary location of the acoustic source was identified in the region commonly referred to as the “necking” of the furnace tube, demonstrating a strong correlation with turbulence intensity near the tube wall. As the coke layer thickness in the furnace tube increased from 5 mm to 15 mm, both the sound power level and turbulence intensity exhibited significant growth. Specifically, the sound power level increased by 60.5% while the turbulence intensity increased by 58.5%. Variations in the overall sound pressure level (OASPL) curve measured within the tube could be utilized to assess coking levels. Significant peaks in the OASPL curve were observed as the furnace tube underwent substantial coking, with coke layer thicknesses of 10 mm and 15 mm. The corresponding OASPL values recorded were 79.25 dB and 119.08 dB, respectively. The findings of this work offer significant insights that may contribute to enhanced safety measures in the operation of ethylene cracking furnace tubes.

Keywords

• coke deposition
• flow-induced noise characteristics
• numerical simulation
• pressure pulsation
• turbulence intensity