Ohřevné pece: validace návrhových parametrů pomocí numerického modelování

Fired heaters: validation of design parameters based on numerical modelling

conference paper

en

Fired heaters are used all over the World for refinery processes. Many of them are designed according the American Petroleum Institute Standard 560. Several facilities encounter significant deformation of tubes or other imperfection related to the tube wall heat load. This leads us to investigation of design parameters suggested by the API standard 560. The key design parameters are related to non-uniformity factors, which represent wall heat flux profile over the length and circumference of tube. Since the onsite investigation is almost impossible the numerical flow simulation is used. The present work reports parametric studies of tube deformations in a cylindrical fired heater (radially and tangentially deformed tubes). The results are reported in the form used by furnace designers, i.e. in terms of circumferential and longitudinal heat flux factor. This way, the work provides information on the effect that deformations of tubes during the lifetime of a furnace may have on heat flux non-uniformity. It is recognized, that fired heater design standards recommendations invoked in 1D design calculations of fired heaters are significantly underestimating real heat flux variability.

Ohřevné pece jsou využívány po celém světě v rafineriích. Mnohé jsou navrženy podle normy American Petroleum Institute Standard 560. Některé provozy vykazují značné deformace trubek, případně další vady vlivem zatížení trubek tepelným tokem. Tento fakt nás přiěl k ověření návrhových parametrů navržených normou API standard 560. Důležitým návrhovým parametrem je faktor nerovnoměrného rozdělení tepelnho toku po výšce a obvodu trubek. Z důvodů obtížného přístupu k trubkám za provozu byla zvolena metoda počítačového modelování proudění. Tato práce předkládá parametrickou studiji (radiálních a axiálních) deformací trubek v peci.

Fired heaters are used all over the World for refinery processes. Many of them are designed according the American Petroleum Institute Standard 560. Several facilities encounter significant deformation of tubes or other imperfection related to the tube wall heat load. This leads us to investigation of design parameters suggested by the API standard 560. The key design parameters are related to non-uniformity factors, which represent wall heat flux profile over the length and circumference of tube. Since the onsite investigation is almost impossible the numerical flow simulation is used. The present work reports parametric studies of tube deformations in a cylindrical fired heater (radially and tangentially deformed tubes). The results are reported in the form used by furnace designers, i.e. in terms of circumferential and longitudinal heat flux factor. This way, the work provides information on the effect that deformations of tubes during the lifetime of a furnace may have on heat flux non-uniformity. It is recognized, that fired heater design standards recommendations invoked in 1D design calculations of fired heaters are significantly underestimating real heat flux variability.

Fired heater, CFD, Combustion, Wall heat flux, API

2015

07.04.2015

CENERTEC

Rio Tinto, Portugal

978-972-99309-7-3

10th European Conference on Industrial Furnaces and Boilers

1–12

12