300MW烟煤/高炉煤气混燃锅炉掺烧褐煤燃烧特性的数值模拟及经济性分析

Numerical Simulation on Combustion Characteristics of a 300 MW Bituminous Coal/BFG Co-firing Boiler Mixed with Lignite and the Economic Analysis

对某300MW烟煤/高炉煤气混燃锅炉掺烧褐煤的燃烧特性进行数值模拟和经济性分析,分析了褐煤完全取代烟煤、部分掺烧褐煤和不同高炉煤气掺烧比例等因素对炉内温度场和CO摩尔分数分布的影响.结果表明:褐煤完全取代烟煤后,炉内温度显著降低而炉膛出口烟气温度明显升高,影响了锅炉运行的安全性;褐煤取代部分烟煤后,随着褐煤掺烧比例的增大,炉内温度逐渐下降,炉膛出口烟气温度升高但CO摩尔分数变化不大;在褐煤掺烧比例一定时,随着高炉煤气掺烧比例的增大,炉膛最高温度明显降低且炉膛出口温度升高,CO摩尔分数的峰值逐渐减小;纯烧烟煤的发电成本为117 090元/h,当掺烧40%褐煤和20%高炉煤气时,发电成本降为80 107元/h,发电成本比纯烧烟煤降低了31.59%.

Numerical simulation was carried out on a 300 MW bituminous coal/BFG co-firing boiler mixed with lignite, while economic analysis performed to the boiler unit, during which the influence of blending ratio on the in-furnace temperature and CO concentration distribution was analyzed under cases that the bi- tuminous coal was completely/partially replaced with lignite and different ratios of blast furnace gas （BFG） was blended. Results show that when the bituminous coal was completely replaced with lignite, the in-furnace temperature reduces obviously while the outlet temperature rises significantly, which may affect safety operation of the boiler~ whereas when the bituminous coal was partially replaced with lignite, with the rise of blending ratio, the in-furnace temperature reduces gradually while the outlet temperature rises, but the CO concentration basically keeps the same; for a fixed blending ratio of lignite, with the rise of blend- ing ratio of BFG, the in-furnace temperature reduces obviously, the outlet temperature rises, and the highest CO concentration reduces gradually. The power generation cost with pure bituminous coal is 117 090 RMB/h, which drops to 80 107 RMB/h when 40% lignite and 20% BFG are blended, indicating a reduction of power generation cost by 31.59%.