Utilization of stack gas and kiln cooling air temperature for factory heating through heat recovery method in ceramic kilns/Iskoristavanje temperature plina dimnjaka i zraka za hladenje peci za zagrijavanje tvornice metodom regeneriranja topline u keramickim pecima

In this study an application in terms of heat recovery from stack gas temperature and waste hot air of tunnel kilns in ceramic industry was carried out. A heat exchanger was designed for the recovery of waste heat and was installed to each of the seven tunnel kilns. The heating of the closed factory area of 1 100 [m.sup.2] was provided using the hot water obtained from the heat exchangers. As a result of this study an energy recovery of 3 509 kW x h was achieved. A natural gas saving of 2 513 000 [m.sup.3] per year was generated through reuse of the obtained energy within the factory. The return period of the investment cost of this application on the current system being as short as 8,3 months has shown its usability for hot water production required especially in ceramic (vitrified) sector.