Energy and Environmental Assessment of Cogeneration in Ceramic Tiles Industry

Ceramic tile manufacturing is a highly energy-intensive process. Concerns about carbon emissions and energy costs make energy management crucial for this sector, which holds a leading role in Italian industry. The paper discusses the energetic and environmental performance of cogeneration (CHP) in the ceramic industry, where prime mover exhaust heat is supplied to a spray-dryer system, contributing to the satisfaction of the thermal demand and decreasing natural gas consumption. A thermodynamic model of a dryer unit, validated against real data, has been set-up to provide a detailed representation of the thermal fluxes involved in the process. Then, the thermal integration with two types of CHP prime movers of similar electric size (4 MW) is investigated. Energetic results show that the gas turbine can contribute up to 81% of dryer thermal consumption, whilst internal combustion engine contribution is limited to 26%. A methodology was ad-hoc defined for the environmental assessment of CHP, accounting for global (CO2) and local (CO and NOX) emissions. Results confirm that CHP units guarantee reduction of CO2 and NOx compared to separate generation, with maximum values equal to 81 g/kWhth and 173 mg/kWhth, respectively; CO emission is decreased only in the case of gas turbine operation, with savings equal to 185 mg/kWhth.