燃煤电厂磨煤制粉系统能量耗散机理及节能降耗对策

Mechanism of energy dissipation of coal pulverizing system of coal-fired power plant and energy conservation and consumption reduction measures

为研究导致燃煤电厂制粉系统效率偏低、能耗较高的影响因素,实现制粉系统节能提效,对燃煤电厂MPS型中速磨煤机进行了开孔采样试验,结果表明:磨机待磨物料中循环负荷占比接近90%,且灰分较原煤高20个百分点。通过设计多组混合破碎试验,模拟分析了循环负荷及其控制对粗颗粒破碎行为和能耗的影响,得出:减少料层中细颗粒含量及其灰分,可增加粗颗粒所分配的单位破碎能量,提高其破碎能量效率。此外,还通过数值模拟和采样数据分析,明确了风速、挡板角度和液压加载力对分离效率和内部流场的影响,提出通过改变一次热风风速、流态或喷射角的方法,使部分高密度矿物成为石子煤,进而优化物料破碎环境,提高破碎和分级效率,降低破碎能耗。

In order to find out the factors underlying the low efficiency and high energy consumption of the plant＇s coal pulverizing system and make it possible to operate efficiently in an energy-saving manner, test is made with the samples collected through opening holes on the MPS vertical spindle pulverizer. Test result indicates that the proportion of the circulating load in the material to be ground is up to 90% and its ash is 20 percentage points higher than that of raw coal. Tests on milling of mixed materials is also conducted for analyzing through simulation the effect of circulating load and its control on breaking behavior of coarse particles and the energy consumption involved. As evidenced by test result, with decrease of proportion and ash of finer particles in material bed, more specific energy can be distributed to the crushing of coarser particles, raising as a result the efficiency of the energy in crushing operation. Based on the result of numerical simulation and analysis of sampling data, the effect of airflow velocity, angle of baffle plate and hydraulic loading force on separation efficiency and internal flow field has been brought to light. It is proposed to change part of high-density minerals to stone-like coal for discharge as rejects for improvement of milling environment, increase of crushing and sizing efficiency and reduction of energy consumption.