RH真空槽高效顶枪烘烤技术的研究与应用

在烘烤盖+多功能顶枪的RH真空槽烘烤工艺中,多功能顶枪烘烤时存在诸多问题:燃气比例匹配失调、燃气流量控制系统PID参数整定困难、定枪位烘烤且枪位不合理和氮气保护气体使用不当。这时常导致安全事故、耐材烧损与开裂严重、燃气耗费量较大、设备机械性能下降、维修率提高等不利现象发生。为此,中国重型机械研究院股份公司从燃气混合技术、PID流量调节技术、多串级闭环烘烤控制技术、变时长变流量多枪位循环加热技术和氮气保护技术等多方面进行研究,总结出新型RH真空槽高效顶枪烘烤技术。并应用于国内某钢厂的120 t RH真空槽烘烤工艺,生产顺利,作业率高,成本低,使用效果良好。

Numerical simulation for explosion wave propagation of combustible mixture gas

A two-dimensional multi-material code was indigenously developed to investigate the effects of duct boundary conditions and ignition positions on the propagation law of explosion wave for hydrogen and methane-based combustible mixture gas. In the code,Young's technique was employed to track the interface between the explosion products and air,and combustible function model was adopted to simulate ignition process. The code was employed to study explosion flow field inside and outside the duct and to obtain peak pressures in different boundary conditions and ignition positions. Numerical results suggest that during the propagation in a duct,for point initiation,the curvature of spherical wave front gradually decreases and evolves into plane wave. Due to the multiple reflections on the duct wall,multi-peak values appear on pressure-time curve,and peak pressure strongly relies on the duct boundary conditions and ignition position. When explosive wave reaches the exit of the duct,explosion products expand outward and forms shock wave in air. Multiple rarefaction waves also occur and propagate upstream along the duct to decrease the pressure in the duct. The results are in agreement with one-dimensional isentropic gas flow theory of the explosion products,and indicate that the ignition model and multi-material interface treatment method are feasible.

On the Controlling Factor of Catalyst Temperature in C_3H_8-Air Mixture

Catalytic combustion of propane-air mixture was investigated. Platinum catalysts over a flat stainless steel with γ- alumina washcoat were employed. The employed burner has three catalysts set parallel to the mixture flow, spaced at an interval of 5, 10 and 15 mm. Both experiment and numerical simulation were made at inlet temperature of 553 K, inlet velocity of 3 to 7 m/s and equivalence ratio of 0.3 to 0.5. In the numerical simulation, two-dimensional,. steady state model was developed to calculate the temperature and species concentration in gas-phase. In this model, chemical reaction on the catalyst surface and that in the gas phase were assumed to occur in three-steps. The numerical results show good agreement with experimental results. It was found that the properties of the catalyst strongly affect the catalyst surface temperature. Especially, the thermal conductivity of catalysthas a great effect, while the emissivity of catalyst has less effect.