INDUSTRIAL WASTE HEAT RECOVERY

Keros Cerámica S.A. – Nules (Spain)

Abstract

Keros Cerámica incorporates a Rank® HT1 machine to improve the energy efficiency of its facilities in Nules (Castellón, Spain). The waste heat is recovered from the exhaust gases of the kilns, and it is used for the generation of electricity.

Waste heat valorisation in the ceramic industry

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

Within the ceramic production process, 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 from the exhaust gases of the furnace, being able to differentiate between combustion and cooling gases.

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, it the heat recovery of the furnace for use in drying rooms also highlights.

A novel alternative with great added value consists in the recovery of waste heat from ceramic furnaces for the generation of electrical energy.

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 has currently two manufacturing plants. The first one is in Nules, Castellón (Spain), the 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 machine that uses of 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, being able to be 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. The ceramic industry is characterised for a high number of operation, and hence, when the ORC is included in their processes, the final viability is improved and the payback period significantly reduced.