为进一步提高火电机组对新能源的消纳能力，当前对火电机组调峰要求越来越高，以某电厂330 MW亚临界CFB机组宽负荷调峰运行为例，针对限制深度调峰的流化安全问题、污染物排放浓度过高及工质偏差等问题，提出了相应运行策略和技术措施。通过改变筛板限距条间距为8 mm，减小入炉煤粒径；采用“回”字形布置在风帽上加装节流环，改善了机组深度调峰下的流化状态；调整布风板面积及一二次风配比，有效降低了深度调峰状态下的最小流化风量。经调整，在流化风量380 km3/h、风温245 ℃运行工况下，布风板阻力提高了2 231 Pa。50%负荷工况下，流化床前后平均温差由126.8 ℃降至27.2 ℃。引入烟气再循环系统，采用多流态多粒度炉内脱硫技术和脱硝喷枪改造。将300～500 μm石灰石由二次风输送进炉膛，1～2 mm石灰石由给煤系统投入炉膛。在炉膛中下部及二次风口倾斜段切向安装多组脱硝喷枪，根据不同调峰负荷调整脱硝喷枪开关。实现了20%机组调峰深度运行时，SO2排放量稳定控制在5 mg/m3以内，NOx排放量降至30 mg/m3以下。在水冷屏入口处安装节流圈，将原水冷屏改造为小面积并联式，降低工质流量偏差和温度偏差。对锅炉机组进行压火试验，实现机组最大限度调峰。研究结果可为同级别燃煤锅炉的深度调峰运行提供参考。

In order to further improve the capacity of thermal power units to absorb new energy,the demand for peak load regulation of thermal power units becomes higher and higher. Taking a 330 MW subcritical circulating fluidized bed unit of a power plant as an example,the corresponding operation strategies and technical measures were put forward to solve the problems of fluidization safety,high pollutantemission concentration and working medium deviation that restricted the realization of deep peak shaving. By changing the spacing of screen plate spacer bars to 8 mm,the coal particle size entering the furnace can be reduced.A throttle ring of "return" shape was installed on the wind cap,which improved the fluidization state of the unit under deep peak shaving. By adjusting the area of the air distributor and the ratio of primary air to secondary air,the minimum fluidizing air volume during deep peak shaving can be effectively reduced. After adjustment,when the fluidizing air volume is 380 km3/h and the air temperature is 245 ℃,the resistance of the air distributor is increased by 2 231 Pa. Under 50% load,the average temperature difference before and after the fluidized bed decreases from 126.8 ℃ to 27.2 ℃. The flue gas recirculation system was introduced,which was retrofitted with multi fluid multi particle furnace desulfurization technology and denitration lance. 300-500 μm limestone was sent into the furnace by secondary air,and 1-2 mm limestone was sent into the furnace by coal feeding. The multiple groups of denitration nozzles were installed in the direction tangential to the middle and lower part of the furnace and the slope of the secondary air outlet,and the switches of the denitration nozzle were adjusted according to different peak loads. When 20% of the units are operating at the depth of peak shaving,SO2 emission can be stably controlled within 5 mg/m3,NOx emission can be reduced to below 30 mg/m3,and the original water cooling shield is transformed into a small area parallel type to reduce the flow deviation and temperature deviation of the working medium. The boiler unit shall be subject to pressure fire protection test to maximize peak load regulation. The research results can provide reference for the deep peak shaving operation of coal-fired boilers at the same level.

0 引言

1 机组初始运行状态设备参数及深度调峰运行问题

   1.1 设备参数

   1.2 深度调峰运行问题

2 深度调峰运行技术

   2.1 流态优化

   2.2 布风板面积优化

   2.3 烟气再循环系统

   2.4 污染物控制技术

   2.5 工质偏差应对措施

   2.6 周期性压火启动技术

3 结论