对冲直流锅炉水冷壁壁温偏差研究及治理

Study and treatment of wall temperature deviation of water wall of opposed once through boiler

对冲直流锅炉磨煤机出口各粉管内煤粉量分配不均使得炉膛宽度方向上同层燃烧器的燃烧强度出现偏差,进而引起壁温偏差,导致汽温受限、壁温超温或应力集中,从而引发的爆管等问题。本文以某典型超超临界3000 t/h对冲直流锅炉为例,试验研究了启炉过程中水冷壁壁温最大偏差的变化规律,考察了煤质、磨煤机投运方式、配风方式等变量对低负荷下壁温分布规律的影响,指出造成对冲直流锅炉深度调峰中水冷壁壁温偏差大的根本原因是磨煤机出口各粉管内的煤粉量分配偏差过大,对此提出在磨煤机出口加装煤粉分配器等治理方案,实施后可将煤粉量分配偏差降低至±10%以内,锅炉运行安全性、经济性及深度调峰能力提高。

Uneven distribution of pulverized coal in each pulverized coal tube at outlet of the pulverizer of opposedfired once through boiler makes the combustion intensity of the same layer burners deviate in the width direction of the furnace,which is easy to cause wall temperature deviation,leading to steam temperature limitation and tube burst due to wall temperature over temperature or stress concentration.By taking a typical ultra supercritical 3000 t/h opposed-fired once through boiler as an example,the variation law of the maximum deviation of water wall temperature in the process of boiler start-up was experimentally studied,the influences of coal quality,operation mode of coal mill and air distribution mode on the distribution of wall temperature at low load were investigated.It was pointed out that,the main reason for the large deviation of water wall temperature during deep peak shaving of the once through boiler was excessive deviation of coal powder distribution in each pulverized coal tube at the outlet of the pulverizer.In this regard,the treatment plan of adding pulverized coal distributor at the outlet of coal mill was put forward.After the implementation,the distribution deviation of pulverized coal was reduced to±10%,and the operation safety,economy and deep peak shaving capacity of the boiler was improved.