Abstract:

At present, there are more and more low-load operations of coal-fired units. The study on the deNO_x control technology of low-load operation can effectively reduce the NO_x emission of coal-fired units. The established real-time flue gas pollutant removal pilot test platform with 20000m³/h was used to analyze the performance indexes, in which the whole modules of the low-temperature denitration catalysts were installed into the SCR system. The NH₃ slip concentration and SO₂/SO₃ conversion rate were sampled on-site and analyzed, the NH₃ slip distribution characteristics were observed. The results show that when the low-temperature catalyst range is 290—250℃, the denitration efficiency is about 80%, and the NO_x at the SCR outlet can be controlled within 50mg/m³, even within 20mg/m³, meanwhile, the maximum NH₃ slip is 1.68mg/m³, which is less than 2.28mg/m³, required by the criterion. The maximum SO₂/SO₃ conversion rate is 0.73%, which is less than 1%, required by the criterion. All these indexes meet the operation requirements. The distribution of NH₃ slip along the pollution control process is further studied. The results show that the NH₃ slip concentration is continuously decreased along the way. The NH₃ slip concentration at ESP inlet is decreased by 32.2% and 65.5% at the ESP outlet, respectively.

Key words: low temperature SCR catalyst, NH₃-slip distribution characteristics, SO₂/SO₃ conversion rate, real coal-fired flue gas, pilot platform

摘要：

目前燃煤机组低负荷运行的情况越来越多，研究机组低负荷运行时NO_x控制技术可有效降低燃煤机组的NO_x排放浓度。本文利用已建成的20000m³/h的实际燃煤烟气的污染物脱除试验平台，安装低温段脱硝催化剂整体模块，测试该催化剂的性能指标，现场取样并重点分析氨逃逸和转化率指标，得出实际烟气条件下氨逃逸分布特征。结果表明：该低温脱硝催化剂的低温段在290~250℃范围内，脱硝效率可达到80%，脱硝出口NO_x可控制在50mg/m³（标准）以内，甚至20mg/m³以内，氨逃逸最高为1.68mg/m³，小于标准要求值2.28mg/m³，SO₂/SO₃转化率最高为0.73%，小于标准要求值1%，满足运行要求。文中进一步研究了氨逃逸浓度沿程分布情况，经测试表明，290℃时沿程氨逃逸浓度不断降低，除尘器前降低32.2%，除尘器后降低65.5%。

关键词: 选择性催化还原低温催化剂, 氨逃逸分布特征, SO₂/SO₃转化率, 实际燃煤烟气, 中试平台