350 MW对冲燃烧锅炉燃用高钠煤掺配试验及应用

Analysis and application of combustion of high Na coal in 350 MW counter-fired boiler

新疆高钠煤具有强结渣,沾污特点,严重影响了锅炉的安全稳定运行,掺配低钠煤运行是一种有效的手段。通过对五彩湾高钠煤与乌东低钠煤质对比,进行五彩湾高钠煤与乌东低钠煤按照质量比为9∶1、8∶2、7∶3、6∶4、5∶5掺配的煤质常规分析数据理论计算,在一维试验台上进行掺配的着火、结渣验证。最后,在350 MW对冲燃烧煤粉锅炉对制粉及燃烧系统优化摸底调整后,进行80%、60%的掺配五彩湾高钠煤实炉试验。形成结论如下:五彩湾高钠煤与乌东煤均为易着火、易燃尽煤种,混煤也是着火和燃尽性能优良,乌东低钠煤掺配比例越高,结渣性越弱;本次实炉试验中五彩湾高钠煤与乌东低钠煤质量比为8∶2,混煤煤灰中氧化钠含量控制在3.57%,能够实现机组长期75%以上负荷掺配80%高钠煤的目标;针对本次试验350 MW对冲燃烧煤粉锅炉,建议采用分磨掺配方式,且前墙上层D磨作为备用磨;每个班全面吹灰一次,再根据实际情况选择性吹灰,及时排渣;运行氧量控制在3%~3.5%之间;同层层风开度最大偏差不大于15%。燃烧五彩湾高钠煤的过程中,可以根据实际结渣情况,进行负荷扰动来使炉膛水冷壁及过热器和再热器管壁的结渣层脱落,或者间歇性掺入低钠煤,可使炉内原有结渣脱落。

Xinjiang high Na coal has the characteristics of strong slagging and contamination,which seriously affects the safe and stable operation of boilers.It is an effective way to mix low Na coal.This paper compares the quality of Wucaiwan high Na coal with Wudong low Na coal,according to the conventional analysis and calculation of 9∶1,8∶2,7∶3,6∶4,5∶5 blending coal,and carrying out on a one-dimensional test rig for ignition and slagging.Finally,after the optimization and adjustment of pulverizin g and combustion system of 350 MW opposed firing pulverized coal boiler,80%and 60%of Wucaiwan high Na coal were mixed into the boiler.The main conclusion:Wucaiwan high Na coal and Wudong low Na coal,are easy to ignite and inflammable,blended coal has excellent ignition and burnout performance,as the higher the blending ratio of Wudong low Na low,Slagging weaken.The mass ratio of Wucaiwan high Na coal to Wudong low Na coal is 8∶2,the content of sodium oxide in mixed coal ash should be controlled at 3.57%,it can achieve the goal of burning 80%high Na coal with more than 75%load for long time.For this 350 MW boiler,suggesting different coal feed to a boiler with separated mills,mill D on the upper front wall is used as standby mills,blow away dust once a team and selectivity number of times,the operating oxygen content is controlled between 3%~3.5%,the maximum deviation of damper opening on the same floor shall not be greater than 15%.In the process of burning Wucaiwan high Na coal,according to the actual slagging situation,carrying out load disturbance or mix low sodium coal,Make the original slagging fall off in the furnace.