Hybrid techology of flue gas denitrification system. Part 1—Preliminary studies of flow turbulence and pressure drop in the elements of rotary air heater baskets

Andrzej Michal Kwiczala, Robert Andrzej Wejkowski, Katarzyna Jagodzińska, Dominika Bandoła


The paper presents the results of physical and numerical tests of fluid flow through the filling of a rotary air heater (RAH). A
laboratory-scale test bench was used to measure flow resistance across a fragment of a RAH. Seven types of RAH modules
were tested - one steel and six ceramic (as catalyst carriers). The relationship between pressure drop and velocity (Re
number) of flow was used to deduce the flow characteristics for each of the RAH modules tested.
Measurements carried out on the test bench were used to create a substitute mathematical model, which in the CFD code
Ansys Fluent enables accurate mapping of pressure drop and velocity distribution full fit to the real flow conditions.
Numerical calculations were used to validate measurements for an alternative model, to create guidelines for the substitute
model of the porous zone and to optimize application checking the correctness of created guidelines for simplified calculations.
Flow simulations were performed for various turbulence models. Results were compared to the test-bench measurements to
determine the best adjustment for this specific type of reverse flow inside the air duct.
This research is part of an ongoing research project: “Hybrid Technology of Flue Gas Denitrification System in Steam and
Hot Water Boilers”. The aim of the project is to investigate the concept of using rotary air heater fillings as a carrier for catalytic
coatings to reduce nitrogen oxides. In the further part of the research project, the replacement porous zone substitute models
will make it possible to precisely calculate the entire RAH and will significantly reduce the calculation time as the basis for
further project work.


Hybrid DeNOx System, turbulence models, backward facing step, rotary air heater, CFD

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C. Directive, Directive 2010/75/eu of the european parliament and of

the council, Off. J. Eur. Union L 334 (2010) 17–119.

Decision (eu) 2017/1442 of 31 july 2017 establishing best available

techniques (bat) conclusions.

M. Kotter, H.-G. Lintz, T. Turek, Katalytische stickoxid-reduktion in

einem rotierenden wärmeübertrager, Chemie Ingenieur Technik 64 (5)

(1992) 446–448.

K. Veser, Regenerativ-wärmetauscher in der umwelttechnik, betriebserfahrungen

mit dem gasvorwärmer an nassentschwefelungsanlagen,

mit pilot-anlagen denox-gerechter luft-und gasvorwärmer an entstickungsanlagen

und anordnungskriterien für solche; entwicklungsstand

des denox-luvo/denox-gavo, VGB Kraftwerkstechnik 66 (12)

(1986) 1123–1130.

Scandenox combined sncr and scr,



von rauchgas-entstickungsanlagen mit denox-katalysatoren: Ein

übersichtsbeitrag über technologie und betriebspraxis von denoxkatalysatoren,

VGB powertech 86 (4) (2006) 72–77.

B. K. Gullett, P. W. Groff, M. L. Lin, J. M. Chen, Nox removal with combined

selective catalytic reduction and selective noncatalytic reduction:

pilot-scale test results, Air & waste 44 (10) (1994) 1188–1194.

R. Wejkowski, W. Wojnar, Selective catalytic reduction in a rotary air

heater (rah-scr), Energy 145 (2018) 367–373.

M. Kuła˙zy´ nski, M. Pronobis, A. Walewski, R. Wejkowski, W. Wojnar,

Selektywna redukcja katalityczna (scr) tlenków azotu w regeneracyjnym

obrotowym podgrzewaczu powietrza (selective catalytic reduction

scr in rotary air heater - in polish), Rynek Energii (6) (2008) 82–87.

F. A. Anwar-ul Haque, S. Yamada, S. R. Chaudhry, Assessment of turbulence

models for turbulent flow over backward facing step, in: Proceedings

of the World Congress on Engineering, Vol. 2, 2007, pp. 2–7.

P. P. Araujo, A. L. T. Rezende, Comparison of turbulence models in the

flow over a backward facing step, International Journal of Engineering

Research and Science 3 (1).

D. Jehad, G. Hashim, A. Zarzoor, C. N. Azwadi, Numerical study of turbulent

flow over backward-facing step with different turbulence models,

Journal of Advanced Research Design 4 (1) (2015) 20–27.

M. K. Isman, Investigation of inlet effects on backward-facing step flow

prediction, Transactions of the Canadian Society for Mechanical Engineering

(3) (2016) 317–329.


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