The Use of CFD for the Design and Development of Innovative Configurations in Regenerative Glass Production Furnaces

Abstract

The limitation of nitrogen oxides emissions is nowadays a challenge in several engineering fields. Recent European regulations have reduced the maximum NOx emissions and therefore forced the glass production sector to develop emission reduction strategies. Two different systems have been developed within the framework of the European LIFE project and are currently applied to glass regenerative furnaces: the Waste Gas Recirculation (WGR) and the Hybrid Air Staging (HyAS). The above systems are primary NOx reduction strategies because they both operate to control the combustion evolution. Both WGR and HyAS systems have been conceived with the extensive use of Computational Fluid Dynamics (CFD) models: design strategies for both systems have been developed based on the use of CFD and are currently under use by glass furnace designers. In the present work, the CFD procedures routinely used for the design of the above systems are described. The systems effectiveness, due to the harsh conditions in the industrial installation, can be tested with oxygen concentration measurements inside the regenerators. The oxygen concentration is correlated to the flame evolution and therefore to the nitrogen oxides formation. For the above reason, the models have been validated with experimental data from pilot furnaces using measured values of O2 mole fraction. The CFD procedures are described in the paper together with their application to different configurations.

Numerical Prediction of the Flow Structure Inside Components of Industrial Glass Furnace Systems

“…a) fluid domain -b) modified edges on the 3D geometry -c) reference brick Also in this case the commercial Ansys Fluent software has been used for the simulations, with the same finite volume approach. The so-called hot phase of the regenerative process is considered [6,8]: the exhaust gases from the combustion chamber enter the port neck and flow through the regenerative chamber to transfer their heat content to the refractory system (that will preheat the combustion air in the following "cold phase" of the regenerative process). A crucial design requirement for this system is the flow uniformity at the top surface of the checker domain in order to have a uniform distribution of gases through the regenerative part of the chamber.…”

“…In order to achieve a good effectiveness of the regenerative heat recovery system, it is necessary to provide a uniform flow distribution into the system starting from the chambers entrance [5][6][7][8].…”

“…The above situation will certainly affect the flow solution details from the CFD analysis with respect to the reference "ideal" case of a CAD design with sharp edges. The CFD approach has proven to be an effective tool for flow simulation inside components of industrial systems [5][6][7][8] and also enhanced CFD approaches with specific models for gas emissivity [6] and real gas effects [9] have been developed, especially for heat transfer or combustion applications. The paper is aimed at verifying the effects of the geometrical details of the edges on the flow structure to understand if the standard CFD approach with sharp edges is actually representative of the flow structure and if the above geometrical details need to be taken into account into the CFD based design strategy for glass production plant components.…”

Strategies for the Numerical Modelling of Regenerative Pre-heating Systems for Recycled Glass Raw Material

“…In the direct model the size of raw material (related to the porosity and consequently the porous resistance) has been varied following Eq. (8)(9). Figure 4 compares the volumetric temperature trends over time for different dimensions Lm of the raw material.…”

“…This system has been optimized to reach high efficiency values thanks to several numerical and experimental studies [2][3][4]. The research team from the University of Genoa has gained relevant experience in the simulation of regenerative glass production plants [5][6][7], but also in gas recirculation strategies for the reduction of NOx emissions [8,9].…”