Waste heat valorisation in the ceramic industry

The ceramic sector is considered an energy-intensive industry, mainly because of the consumption of natural gas fuel for the kilns. Thus, energy costs can reach 30% of the total production costs. Therefore, any strategy aimed to improve energy efficiency can represent an advantage in this competitive sector.

More than 50% of the energy is used in the tile preparation stage. However, at this stage, we also find the most important waste heat sources, mainly within the exhaust gases of the kiln.

Among the most common energy-saving actions, the regulation of burners and insulation improvements in furnaces stand out. On the other hand, when technically viable, the heat recovery of the furnace is also used in drying rooms.

A novel alternative with great added value is recovering waste heat from ceramic furnaces to generate renewable electricity.

Keros Cerámica S.A.

Keros Cerámica S.A. manufactures and commercialises ceramic flooring and tiling. It has more than 40 years of experience in the ceramic sector and distributes to around 100 countries.

Keros Cerámica currently has two manufacturing plants. The first one is in Nules, Castellón (Spain), in the geographical centre of Spanish ceramic tradition. The second one is in Ruse, Bulgaria, which facilitates direct access to Central and East Europe.

The installation

Keros Cerámica has integrated a Rank® HT1 unit that uses the fumes from its furnaces. Thus, it is included in their set of advanced environmentally respectful technologies.

The exhaust gases of the ceramic furnace are initially at 290 °C. Then, a heat exchanger transfers the heat to the thermal oil circuit and reduces the temperature to 165 °C, connected to the ORC system.

Therefore, Rank® HT1 equipment is a suitable solution for the generation of electricity from small-scale waste heat. In this case, it is capable of generating electric power of up to 20 kWe. A high number of operations characterises the ceramic industry, and hence, when the ORC is included in their processes, the final viability is improved and the payback period significantly reduced.