Energy saving in ceramic tile kilns: Cooling gas heat recovery

• Published in: Applied thermal engineering 2014-04, Vol.65 (1-2), p.102-110
• Main Authors: Mezquita, Ana, Boix, Juan, Monfort, Eliseo, Mallol, Gustavo
• Format: Article
• Language: English
• Subjects: Applied sciences; Ceramic tile; Energy; Energy efficiency; Energy. Thermal use of fuels; Exact sciences and technology; Heat recovery; Heat transfer; Roller kiln; Theoretical studies. Data and constants. Metering
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2014.01.002

A great quantity of thermal energy is consumed in ceramic tile manufacture, mainly in the firing stage. The most widely used facilities are roller kilns, fuelled by natural gas, in which more than 50% of the energy input is lost through the flue gas and cooling gas exhaust stacks. This paper presents a calculation methodology, based on certain kiln operating parameters, for quantifying the energy saving obtained in the kiln when part of the cooling gases are recovered in the firing chamber and are not exhausted into the atmosphere. Energy savings up to 17% have been estimated in the studied case. Comparison of the theoretical results with the experimental data confirmed the validity of the proposed methodology. The study also evidenced the need to improve combustion process control, owing to the importance of the combustion process in kiln safety and energy efficiency. •Some energy input (30–35%) in ceramic roller kilns is lost through the cooling gas stack.•Cooling air is directly recovered in the combustion chamber, providing oxygen.•This energy recovery from the cooling gas stack has been quantified.•It has been proven that the proposed methodology to estimate energy savings is valid.