Abstract:

This study investigated factors influencing carbon emissions of coal-fired combined heat and power (CHP) units, taking as the research object a 50MW condensing-extraction steam turbine generator set equipped with a 440t/h circulating fluidized bed (CFB) boiler at a certain enterprise. A systematic analysis was conducted on the effects of variations in boiler fuel composition, boiler thermal efficiency, and overall unit thermal efficiency on carbon emissions and on changes in the unit's specific operating costs. The results indicated that actual unit carbon emissions were directly proportional to the proportion of petroleum coke blended in the boiler and inversely proportional to the proportion of gas blended; as boiler thermal efficiency or overall unit thermal efficiency increased, the deficit in the unit's carbon emission allowances gradually diminished until a surplus was achieved; and with rising carbon allowance trading prices, the impact of optimizing boiler fuel composition and enhancing both boiler and overall unit thermal efficiencies on reducing the unit's specific operating costs became significantly stronger. Under varying overall unit thermal efficiencies and operating loads, the influence of adjusting external heat supply versus power generation on the unit's specific operating costs exhibited a threshold characteristic: increasing power generation beyond the unit's operational equilibrium condition yielded greater cost advantages, and this equilibrium point shifted toward lower efficiency regions as carbon allowance trading prices rise. This research provided a reference for enterprises to optimize unit operations, dynamically implement carbon reduction measures, and enhance the economic performance of unit operation.

Key words: combined heat and power, fuel structure, carbon emission, thermal efficiency, carbon trading

摘要：

针对燃煤型热电联产机组碳排放关联影响因素，以某企业440t/h循环流化床锅炉配套50MW抽凝汽轮发电机组为研究对象，系统分析了锅炉燃料结构、锅炉热效率以及机组综合热效率的变化，对机组碳排放的关联影响和机组单位运行成本的变化情况。研究结果表明，机组碳排放实际量与锅炉石油焦掺烧量成正比、与瓦斯气掺烧量成反比；随着锅炉热效率或机组综合热效率提升，机组碳排放配额缺口逐步减少直至盈余；随着碳排放配额交易价格上涨，锅炉燃料结构优化、锅炉热效率和机组综合热效率提升对降低机组单位运行成本的作用显著增强。在不同机组综合热效率与运行负荷下，调整对外供热量与发电量对机组单位运行成本的影响具有分界特性，超过机组运行平衡工况，增加发电量更具成本优势，且该平衡工况随着碳排放配额交易价格上涨向机组低效率区间偏移。上述研究为企业优化机组运行、动态开展碳减排、提高机组运行的经济性提供了参考。

关键词: 热电联产, 燃料结构, 碳排放, 热效率, 碳交易