ZGM型中速磨煤机改造的模拟研究

Simulation for Improvement of ZGM Medium Speed Mill

利用FLUENT程序对ZGM95型中速磨煤机内的流场进行了模拟,并对封堵低流量区的部分风环、磨煤机入口风道改为左右对称的双入口型式、入口风道由倾斜向下进入磨煤机改为水平走向等改造进行了模拟。模拟结果显示,一次风从磨煤机一侧吹入导致不同风环处的入口静压和流量呈不均匀分布。封堵部分风环不足以在磨煤机内部得到理想的均匀流场分布,而且磨煤机的整体压降会急剧上升,将导致能耗的大幅增加。磨煤机由单入口型式改为左右对称的双入口型式时可以有效地改善磨煤机内风环流量分布极不均匀的问题,而且不会带来过多的磨煤机出入口压降,但双入口型式在工程中是否可行还需要综合考虑现场空间大小、一次风量测量装置的布置等因素。而将磨煤机入口一次风道由倾斜向下进入底部风室改为水平走向进入底部风室,能够避免一次风气流折向流动带来的压降并进一步改善磨煤机内部的流场。

The inner flow fields in the ZGM95 medium speed mill are numerically simulated by employing the commercial code of FLUENT. And the further simulations are performed for the reconstructions of blocking some nozzle rings, adopting double-inlet structure and laying the horizontal air duct before the mill. The results show that the static pressure and the flow rate at each nozzle ring is different from those of others due to the primary air entering the mill only from one side. The flow fields are still not good enough and the pressure drop increases sharply in the mill when blocking a few of the nozzle rings, which will result in the great energy consumption. The structure with double-inlet instead of single inlet can improve the distribution of the flow fields efficiently in the mill and few pressure drop of the mill appears. However, the feasibility of the double-inlet structure is also depends on the field conditions such as the space and the location of the first air measuring devices. The pressure drop will be less and the flow fields will be better when the inlet duct is modified to be the horizontal one.