660MW燃煤机组宽负荷脱硝改造技术方案研究

The route reacher of wide load denitration transformation for 600 MW coalfired units

针对双碳背景下燃煤机组深度调峰时反应器入口烟温偏低限制SCR正常投运的问题,介绍了宽负荷脱硝改造的路线和方法。并以某660 MW燃煤机组为例,以20%负荷和30℃温升为目标,从技术、经济方面对多种改造方案进行了对比。研究结果表明:(1)采用烟气旁路方案,其挡板门存在卡塞风险;(2)采用省煤器水旁路方案,投资最低,但仅能提升烟温11℃,不满足改造要求;(3)采用分级省煤器方案,投资最高,且改造后反应器入口局部烟温将达450℃,超过催化剂运行温度的上限;(4)采用宽温脱硝催化剂方案,全年入炉煤硫含量的平均值约为1.92%,部分时段超过3%,长时间低温运行时易造成宽温催化剂的微孔堵塞和活性下降;(5)采用复合热水再循环方案,投资适中,因新增炉水循环泵,能有效提高锅炉的水动力,提升锅炉低负荷运行时的安全性和湿态运行后的经济性,是本项目的最佳方案。各发电企业在路线选择时应根据各厂实际情况,一机一策选择合适的技术路线;如机组需深调至锅炉湿态运行,可优先选择带有炉水循环泵的复合热水再循环工艺。

Aiming at the problem that the low inlet flue gas temperature of the reactor limits the normal operation of SCR during the deep peak regulation of coal-fired units under the background of double carbon,the route and method of wide load denitrification transformation are introduced.Taking a 660 MW coal-fired unit as an example,a variety of retrofit schemes are compared from the technical and economic aspects with the goal of 20%load and 30°C temperature rise.The results show that:(1)the baffle door has the risk of jamming when the flue gas bypass scheme is adopted;(2)The economizer water bypass scheme has the lowest investment,but it can only increase the flue gas temperature by 11°C,which does not meet the transformation requirements;(3)The investment is the highest by using the scheme of grading economizer,and the local flue gas temperature at the inlet of the reactor will reach 450°C after the transformation,exceeding the upper limit of the operating temperature of the catalyst.(4)Using the wide temperature denitration catalyst scheme,the average sulfur content of the coal in the whole year is about 1.92%,and it is more than 3%in some time periods.Long-term low-temperature operation is easy to cause micropore blockage and activity decrease of the wide temperature catalyst.(5)Using the compound hot water recirculation scheme,the investment is moderate.Because of the new boiler water circulation pump,it can effectively improve the hydrodynamic force of the boiler,improve the safety of the boiler during low load operation and the economy after wet operation.It is the best scheme of this project.Each power generation enterprise should choose the appropriate technical route according to the actual situation of each plant.If the unit needs to be adjusted to the wet operation of the boiler,the composite hot water recirculation process with furnace water circulating pump can be preferred.