Analytical models for heat transfer in the tube bundle of convection section in a steam cracking furnace. (25th December 2019)

• Record Type: Journal Article
• Authors: Yuan, Benfeng; Zhang, Yu; Hu, Guihua; Zhong, Weimin; Qian, Feng
• Is Part Of: Applied thermal engineering. Volume 163(2019)
• Publication Date: 2019-12-25
• Subjects: Convection section -- Tube bundle -- Heat transfer analysis -- Computational fluid dynamics -- Convective heat transfer -- Radiative heat transfer; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2019.113947
• Languages: English
• ISSNs: 1359-4311

Abstract

Graphical abstract: Highlights: A heat transfer analysis model for the tube bundle is developed. The HTA model considers the convective and radiative heat transfer and is validated by the CFD method. The coupled simulation of a steam cracker convection section is performed. The fin enhances the convective heat transfer at the top of the convection section. The radiative heat transfer is larger than the convective heat transfer at the bottom of the convection section. Abstract: In steam cracking furnaces, about 45% of the heat released from fuel combustion is recovered by preheating cracking feedstock and high pressure steam. This is achieved mainly by indirect convective heat transfer from flue gas to feedstock and steam in a series of tube bundles located in the so-called convection section. Radiation also plays in an important role in lower bundles where flue gas temperature is high. Thus, accurate heat transfer simulation of the convection section is crucial for operation optimization and control of steam cracking furnace. This paper aims to develop a heat transfer analysis (HTA) model for combined convective and radiative heat transfer calculation in tube bundles with both inline and staggered layouts. Computational fluid dynamics (CFD) was employed to validate the HTA model in the first stage. Based on the HTA model, coupled steady-state simulations of the convection section were performed for an industrial steam cracking furnace with naphtha feed capacity of 30 t/h. The predictions of the HTA model are in good agreement with the design data. The study shows that convective heat transfer is significantly enhance by fins in the tube bundles where the flue gas temperatures are too low to effectively heat up the feedstock. Radiative heat transfer at the bottom of the convection chamber is much larger than the convective heat transfer and thus cannot be ignored in heat transfer calculation.