The Effect of Variable Air–Fuel Ratio on Thermal NOx Emissions and Numerical Flow Stability in Rotary Kilns Using Non-Premixed Combustion

One of the quickest ways to influence both the wall temperature and thermal NOx emissions in rotary kilns is to change the air–fuel ratio (AFR). The normalized counterpart of the AFR, the equivalence ratio, is usually associated with premixed flames and studies of its influence on diffusion flames are inconsistent, depending on the application....

Mitigating Thermal NOx by Changing the Secondary Air Injection Channel: A Case Study in the Cement Industry

This work studies how non-premixed turbulent combustion in a rotary kiln depends on the<br/>geometry of the secondary air inlet channel. We target a kiln in which temperatures can reach values above 1800 degrees Kelvin. Monitoring and possible mitigation of the thermal nitric-oxide (NOx) formation is of utmost importance. The performed reactive...

The Manufacture of Lightweight Aggregates from Recycled Masonry Rubble

At present, heterogeneous and fine-grained masonry rubble can only be recycled at very low level. To overcome this limitation, the material was employed as feedstock for the production of lightweight aggregates in a thermal process similar to that used in the manufacture of expanded clay and expanded slate. To that end, the fundamental...

Modelling Turbulent Non-Premixed Combustion in Industrial Furnaces

Measuring the temperature distribution inside the rotary kilns, using thermocouples for instance has proven to be difficult due to the harsh operating conditions of the kiln. Numerical modelling of turbulent combustion and the associated physical phenomenon thus proves to be an indispensable tool towards predicting the kiln operating conditions....

Numerical Modeling of Rotary Kiln Productivity Increase

Rotary kilns are used in many industrial processes ranging from cement manufacturing to waste incineration. The operating conditions vary widely depending on the process. While there are many models available within the literature and industry, the wide range of operating conditions justifies further modeling work to improve the understanding of...

Numerical Modeling of Granular Beds in Rotary Kilns

In process engineering applications numerical models are needed to make extensive analysis for the design and operation of unit operations. In the present work, a transversal granular flow model and two numerical models for the description of the granular bed of a rotary kiln are developed for the analysis of a Calcium Aluminate rotary kiln from...