Simulation research on the slag control tube during energy recovery from steel industry

In the process of steel smelting, a large amount of liquid slag with temperature from 1400°C to 1550°C is produced. The sensible heat contained per ton of blast furnace slag is equivalent to the calorific value of 60 kg standard coal. In 2017, China's crude iron production reached 710 million tons, producing 213 million tons of blast furnace slag, whose sensible heat is equivalent to 12.84 million tons of standard coal. Thus, recovery of waste heat from high temperature liquid slag has great energy conservation potential. To resolve the contradiction between the discontinuity of slag discharge and the continuity of waste heat recovery system, this paper carried out numerical simulation research on high-temperature liquid slag buffer and flow control process. The variations of flow rate with time and liquid level were obtained by numerical simulation of slag discharge in the slag control tube. The main conclusions are as follows: A critical liquid level of 1.65 m was found and confirmed. As the liquid level fell to the critical level, the flow rate decreased rapidly and approached zero in a short time. When the internal diameter was 27 mm and the slag temperature was 1450°C, the rate change of the slag met the system requirements of 6 t·h^-1~7 t·h^-1, and the relational expression of the flow level could be fitted. This study has essential guiding significance for liquid level control in actual operation.