Numerical studies of mid-kiln tyre combustion

Abstract

A one-dimensional mathematical model of tyre combustion is developed and incorporated in a computational fluid dynamics (CFD) code with the objective of simulating industrial-scale cement kilns and studying the midkiln firing of whole tyres. The simulation without tyre combustion shows a high flame temperature, high NOx emission, and good quality product. Replacing 20% of the total kiln heat with tyres as fuel and dropping them in to the kiln at 50 m from the burner tip results in a reduced flame temperature, a 33% reduction of NOx emission and good clinker quality. Further investigations show that up to 30% replacement of fuel with tyres is acceptable to maintain the clinker quality with reduced NOx emissions. When the tyre replacement is 40% or more, NOx emission can be further reduced, but the clinker quality becomes poor. The tyre drop-in location is another critical parameter. For the kiln studied tyres can be dropped in within 50 m of the burner tip. Further downstream dropping-in reduces kiln efficiency and clinker quality. The actual replacement of tyre combustion and the drop-in location depends on the kiln design and operating conditions. The developed comprehensive simulation tool can be used to reach an optimised kiln design under a specified operating condition.

Sustainable transition towards biomass-based cement industry: A review

“…two-dimensional models) [25,72,97] to understand the complex thermo-chemical combustion processes. Several studies have investigated combustion dynamics in kiln [98,99] and calciner [72,97,99] that deal with various aspects such as co-firing [100,101], CCS [102], and the impact of combustion on clinker [101,103] using the Computational Fluid Dynamics modeling approach. Studies pertaining to co-firing with biomass are of particular interest as the findings revealed that biomass-based fuels provides environmental benefits to cement plants.…”

Production of rubber parts by tyre recycling without using virgin materials

“…As a further advantage, the use of TDF allows kilns to reduce NO x emissions. 15 Tyre derived fuels can also be used in cupolas, 16 or in fluidised beds for steam generating, 17 and low temperature gasification. 18 Gasification with steam and carbon dioxide was also suggested to produce activated carbons from tyres, 19 and fluidised beds can be used for this aim.…”

“…However, TDF cannot exceed 30% of the kiln fuel without adversely altering the chemistry of the cement's hardening process. As a further advantage, the use of TDF allows kilns to reduce NO x emissions 15. Tyre derived fuels can also be used in cupolas,16 or in fluidised beds for steam generating,17 and low temperature gasification 18.…”