圆形蓄热式熔铝炉内非稳态多场耦合数值模拟与参数优化

Transient multi-field coupled simulation and parameters optimization of cylindrical regenerative aluminum melting furnace

以圆形蓄热式熔铝炉为研究对象,根据熔铝炉的运行特点,应用标准k—ε湍流模型、涡耗散模型、P-1辐射模型描述湍流燃烧过程,应用等效比热法描述铝料的熔化过程,对熔铝炉内进口与出口边界交替变化的热工过程进行非稳态多场耦合数值模拟研究。蓄热式熔铝炉基准工况下的数值模拟结果表明:与传统单一烧嘴工作相比较,两个烧嘴快速切换,铝料温度分布更为均匀,其平均温度在前3 h升温较快,随后由于熔化吸热升温速率逐渐减小。以缩短铝料熔化时间为目标,采用正交试验方案,对影响熔铝炉热工过程的5个参数进行数值模拟优化,其优化工况为烧嘴高度657 mm、烧嘴倾角25°、烧嘴夹角90°、过剩空气系数1.1、空气预热温度800℃。与设计工况相比,优化工况能缩短铝料熔化时间1 h,可降低能源约20%。

A numerical model of a cylindrical regenerative aluminum melting furnace was developed according to its operation characteristics. By including the standard κ-ε model, the species transport model and the P-1 radiation model to describe the turbulent combustion process in the furnace, and applying the equivalent specific heat method to describe the aluminum melting process, a transient and multi-fields coupled simulation was carried out to investigate the thermal alternation processes in the inlet and outlet areas of the furnace. The simulation results of the standard operation case show that, compared with the traditional operation with one burner, a more uniform temperature distribution can be achieved in the switch operation of two burners. In particular, the temperature rises quickly in the in,st three hours, followed by a slower rising due to heat absorbed by the melting alumina in the furnace. More simulations were carried out based on the orthogonal design to optimize the main five parameters that have significant influences on the process. The results indicate that an optimal operation condition can be achieved with the burner height of 657 ram, the vertical burner angle of 25°, the horizontal angle between two burners of 90°, the excess air coefficient of 1.1 and the air preheating temperature of 800 ℃. Compared with the result of the standard operation case, one hour can be reduced in the melting time of the alumina in the optimal condition, which is equivalent to 20% reduction in the energy consumption.