Reducing temperature gradient during local heat treatment process with card furnace for large-scale hydrogenation reactor

The card furnace heating is the main way of local heat treatment for the girth weld of large hydrogenation reactor at present. However, the uneven temperature distribution is inevitably generated due to limited burner. Thus affecting the material properties and stress distribution in weld. Controlling heat treatment temperature uniformity is the key to ensure heat treatment effect. In this paper, the combination of heat treatment experiment and numerical simulation is used to analyze the evolution of temperature field in the process of local heat treatment. The influences of process, burner inlet velocity ratio, number and arrangement of entrances on the flow field and temperature field were also discussed. The results show that the symmetrical arrangement on both sides of the 16 burner inlets will improve the velocity uniformity near the wall. The diversion structure with a distance of 700 mm from the inlet and an angle of 45° with the vertical direction will divert the flue gas to the vertical direction. It is found that the overall temperature uniformity is improved, the temperature gradient is reduced by about 4 °C. It provides guidance for the implementation of local heat treatment of card furnace in engineering.