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The article presents the main aspects of the implementation, use and pilot and industrial experiments of some self-contained recovery burners. The results of pilot and industrial experiments of these burners have argued and quantified their energy efficiency. This efficiency consists mainly in an economy of specific fuel consumption (natural gas and / or coke gas) of approx. 25-35%. Other advantages of using recuperative burners are: ensuring a higher temperature in the hearth, reducing the duration of the processing cycle and thus increasing labor productivity. All these advantages of using recuperative burners are based on their operating principle, which consists in preheating the oxidizer (combustion air) by recovering an important part of the enthalpy of its own flue gases. This recovery is done in an energy recuperator designed right in the body of the recuperative burner. Due to this important aspect, the recovery burner is part of the Primary Energy Recovery (REP) category.

This article presents the main aspects of the conception, design and construction of selfdesigned recuperative burners. The starting point of the article is the operating principle of this specific type of combustion plant. This operating principle is based on the preheating of the combustor (combustion air) by taking over an important part of the enthalpy of its own combustion gases. Based on this principle, the recuperative burner of our own design has an energy efficiency that consists in reducing the specific consumption of fuel (natural gas) by about 25-35%. Also, the use of this specific type of combustion plant provides other functional advantages such as: a higher temperature in the hearth (due to a complete combustion), reduction of technological cycle times for the realization of various processes. The article also presents some functional parameters of a type-dimensional range of recuperative burners of our own design.

A glass foam with good thermal insulation characteristics (apparent density of 0.38 g/cm3, porosity of 81.9% and thermal conductivity of 0.089 W/m·K), high compressive strength (3.9 MPa) and a satisfactory microstructural homogeneity with pore size between 0.6–1.0 mm was obtained by sintering at 927 °C of flat glass waste, a glass waste usually not used in the manufacture of glass foam. The manufacturing recipe has been improved by the simultaneous use of two microwave susceptible foaming agents (SiC and Si3N4) and the addition of coal fly ash and an oxygen-supplying agent (MnO2). The originality of the work was the simultaneous use of the two foaming agents and also the application of the technique of predominantly direct microwave heating, compared to the conventional heating methods commonly used in the manufacture of glass foam. The remarkable energy efficiency of the microwave heating technique led to high average heating rates without affecting the structural homogeneity and very low specific energy consumption.