超临界循环流化床机组深度调峰过程中除了亚临界机组面临的低负荷工况布风板的稳定流化、氮氧化物控制难题外，还涉及水动力的安全性问题。针对超临界循环流化床锅炉深度调峰面临的技术难题，通过流态重构，使临界流化风速降低，保证稳定流化所需的风量减小，同时，减少了炉膛下部燃烧份额，进而减小布风板面积，保证超低负荷流化稳定；开发了垂直管圈二次上升水冷壁工质流程，保证低负荷水动力安全性；降低床料粒度和循环物料粒径，在保证流化和燃烧的前提下，降低一次风比例，强化焦炭颗粒表面的局部还原性气氛，同时对给煤、排渣、送风等布置方式进行优化布置，保证炉内氧量和温度分布均匀，为氮氧化物控制提供保证，最终实现350 MW超临界循环流化床锅炉20% BMCR工况稳定运行，最大壁温偏差为17 ℃，炉内同层温度偏差在30 ℃以内。此外，在锅炉从启动到满负荷以及变负荷运行过程中，3个旋风分离器入口烟温的温度偏差始终在10 ℃ 以内，氮氧化物全负荷超低排放。

In the process of deep peak regulation of supercritical circulating fluidized bed units,in addition to the problems of stable fluidization of air distribution plate and nitrogen oxide control under low load conditions faced by subcritical units,the safety of hydrodynamics is also involved. In view of the technical problems of deep peak regulation of supercritical circulating fluidized bed boiler,through the reconstruction of flow pattern,the critical fluidization air velocity was reduced,the air volume needed to ensure stable fluidization was reduced,and the combustion share in the lower part of the furnace was reduced. Furthermore,the area of air distribution plate was reduced to ensure the stability of ultra-low load fluidization,and the working fluid flow of secondary rising water wall with vertical tube ring was developed to ensure the hydrodynamic safety of low load. Reduce the particle size of bed material and circulating material,on the premise of ensuring fluidization and combustion,reduce the proportion of primary air,strengthen the local reducing atmosphere on the surface of coke particles,optimize the arrangement of coal feeding,slag discharge and air supply,ensure the uniformity of oxygen and temperature distribution in the furnace,provide a guarantee for the control of nitrogen oxides,and finally realize the stable operation of 350 MW supercritical circulating fluidized bed boiler under 20% BMCR conditions. The maximum wall temperature deviation is 17 ℃,and the temperature deviation of the same layer in the furnace is less than 30 ℃. In addition,in the process of boiler operation from start-up to full load and variable load,the temperature deviation of the inlet flue gas temperature of the three cyclone separators is always within 10 ℃,and the NOx emission is ultra-low at full load.

0 引言

1 超临界CFB锅炉深度调峰关键技术

   1.1 超低负荷的流化稳定

   1.2 超低负荷氮氧化物控制

   1.3 超低负荷水动力安全性

2 350 MW超临界CFB锅炉概况

3 350 MW超临界CFB锅炉运行结果

   3.1 床温

   3.2 锅炉运行氧量

   3.3 水冷壁温度

   3.4 氮氧化物排放

4 结论