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5.2.5.2 Radiant tube burner system

Radiant tubes burner system shall be suitable and allow safe operation.

Radiant tube burner systems shall be designed in accordance with the requirements for a protective system in accordance with 5.7.2 and 5.7.3.

They shall:

• be constructed of suitable materials for the thermal input rate, temperature and furnace atmosphere;
• minimise the probability of combustion products having contact with the furnace atmosphere;
• shall be equipped with an automatic burner control system according to 5.2.6. At temperatures above 750 °C no automatic burner control system is needed if a safe ignition of the air/gas mixture can take place. The temperature limit of 750 °C shall be detected at the coldest point;
• if additional burners are required to operate the IThE processes above 750°C and an automatic burner control systems is not required then they shall be isolated from the supply by automatic shut-off valves that are controlled in accordance with the requirements of a protective system (according to 5.7.2 and 5.7.3) that will not permit fuel to flow until the temperature at the ignition point within the radiant tube is above 750°C.

Because the ignition point is inside the radiant tube and the temperature inside the tube may well be much lower than in the chamber in which the radiant tube is placed this temperature difference shall be taken into consideration when designing.