Increasing the reliability of high-temperature electric heaters of the radiant tube type based on graph theory methods

The analysis of the operating features of closed-type electric heaters of the radiant tube type is performed. Based on the operating experience of the radiant tubes manufactured by “PromTermoSistema” LLC (Belarus), the key aspects affecting the durability of the heaters are shown. One of the main technical problems is the dense arrangement of heating elements (metal rods) in a small volume and the associated electrical breakdowns of electrically insulating ceramic inserts. Based on graph theory, a method is proposed for analyzing the commutation of heating elements with dense packing, which made it possible to find new rational commutation schemes. The method is based on constructing numbered graphs on the holes for heating rods in the ceramic element and finding the graph with the minimum weight. According to the meaning of constructing a graph, its weight is proportional to the maximum potential difference between the rods. The found commutation schemes reduce the maximum potential difference on ceramic insulators by 35–50 %, from 70 V to 35÷45 V, and the electric field strength from 10 kV/m to 5.0÷6.5 kV/m. This allows proportionally increasing the reliability and durability of heaters, reducing the probability of electrical breakdowns of ceramics.