燃气轮机与燃煤机组SCR脱硝催化剂特性比较

Comparison of Characteristics of SCR-DeNO_(x) Catalyst for Gas-Turbine Units and Coal-Fired Units

通过对燃气轮机组(以下简称“燃气机组”)与燃煤机组在NOx排放政策要求及SCR工艺中催化剂特性方面的对比,论述了在燃气机组应用SCR脱硝技术的必要性,分析了燃气与燃煤机组SCR脱硝工艺在催化剂布置、结构、成分及脱硝效率等方面的特性差异。研究结果表明,燃气机组因SCR工艺烟气温度低、基准氧含量高,入口烟气中NO_(x)、SO_(2)和粉尘含量少,催化剂通常布置于余热锅炉内部中压蒸发器之后,设计脱硝效率一般为30%~70%,适应于宽松的氨逃逸控制策略。燃气机组脱硝催化剂通常单元孔数高于40×40、长度短于350 mm,活性组分(V_(2)O_(5))与助催化剂成分(WO_(3))含量常规显著高于燃煤烟气脱硝催化剂,并且燃气机组SCR工艺中催化剂的化学失活与机械受损速率较慢,具有较长的使用寿命。此外,燃气机组脱硝催化剂的检测方法应有别于现行标准中对于燃煤机组脱硝催化剂的常规检测要求。

Based on the comparison between gas-turbine units and coal-fired units in terms of the NOx emission policy requirements and the characteristics of catalysts in SCR process,this paper expounds the importance of SCR-DeNO_(x) application in gas turbine units and analyses the difference in the features of SCR-DeNOx catalyst,such as layout,structure,composition and DeNO_(x) efficiency.The study results show that due to the low flue gas temperature,high baseline oxygen content,low NO_(x),SO_(2) and dust contents in the inlet flue gas,the catalysts are generally arranged in the waste heat boiler after the medium pressure evaporator in the gas turbine units with the designed DeNO_(x) efficiency between 30%and 70%,suitable for the implementation of loose ammonia escape control strategies.Their pore quantities per unit are generally higher than 40×40 and shorter than 350 mm.The contents of active components(V_(2)O_(5))and promoter components(WO_(3))are significantly higher than that of coal-fired flue gas DeNOx catalysts.Moreover,due to the slow decay rate of chemical deactivation and mechanical damage of the catalysts in gas turbine SCR process,a longer service life is expected for the catalysts.At last,the detection methods for the catalyst of gas turbine SCR process shall be different from the traditional methods for the catalyst in coal-fired unit SCR process under current standards.