燃煤机组烟羽治理中温度选择与防腐措施

Temperature Selection and Anti-corrosion Measures in Plume Control of Coal-fired Units

对烟羽治理模型进行研究,并利用数值方法求解不同烟羽治理技术终端确定的温度。研究表明:直接加热法和冷凝再热法确定的终端温度随环境温度升高而降低,近似呈指数分布;直接冷凝法确定的终端温度与环境温度近似呈线性正相关。在给定25%,50%和75%环境相对湿度时,直接加热法确定的终端温度为7.5,9.5和12.4℃;冷凝再热法确定的终端温度分别为1.0,2.9和5.6℃直接冷凝法确定的终端温度分别为28.7,30.8和33.7℃;在相应的终端温度之上,烟羽治理具有可行性;腐蚀问题贯穿烟羽治理整个过程,设计阶段应充分考虑换热元件耐腐蚀性、烟囱结构形式、烟道正压区腐蚀、烟道经济性和脱硝催化剂选用等;运行阶段应注意煤质管控、燃烧配风和终端温度等;检修阶段应注意检查漏点和涂刷防腐涂料,必要时加装辅助蒸汽加热系统。

Based on the study of a plume control model, a numerical method is proposed to solve the terminal temperature determined by different plume control technologies.The research shows the terminal temperature determined by the direct heating method and the condensing reheating method decreases with the increase of ambient temperature, which appears an exponential distribution approximately.The terminal temperature determined by the direct condensation method is approximately linearly correlated with the ambient temperature.Under the relative humidity of 25%,50% and 75%,the terminal temperature determined by the direct heating method is 7.5 ℃,9.5 ℃ and 12.4 ℃,respectively.Also, the terminal temperature determined by the condensation reheating method is 1.0 ℃,2.9 ℃ and 5.6 ℃,and those determined by the direct condensation method is 28.7 ℃,30.8 ℃ and 33.7 ℃,respectively.According to the results, the plume control is technically feasible above the corresponding terminal temperatures.The corrosion problem runs through the whole process of plume treatment.In the design stage, the corrosion resistance of heat exchange elements, the structure of the chimney, the corrosion of the positive pressure zone of the flue, the economy of the flue and the selection of denitration catalyst should be fully considered.During the operation, attention should be paid to coal quality control, combustion air distribution and terminal temperature, etc.During the maintenance, attention should be paid to check the leakage points, paint the anti-corrosion coating, and install the auxiliary steam heating system when necessary.