燃煤电站一次风加热流程优化的高效集成系统性能分析

Performance Analysis of the Efficient Integrated System of Coal-fired Power Plant Based on Optimized Primary Air Heating Process

在常规燃煤电站机组中,一次风加热流程和尾部烟道低温烟气换热流程存在数量可观的可用能损失和较大的优化利用空间,为减小系统换热过程的不可逆损失,该文提出基于一次风加热流程优化的高效集成系统,预干燥进入制粉系统的较高水分原煤,降低一次风的吸热量,在此基础上利用两级蒸汽加热器分级加热一次风,同时优化低温烟气换热流程,回收低温烟气余热,可大幅提高机组出功。该文以国内某典型1000MW超超临界燃煤机组为案例,针对一次风加热流程优化的高效集成系统的换热过程以及能量分配进行了热力计算,并对系统做了技术经济性分析。研究结果表明,原煤水分由18.1%干燥至8%的情况下,一次风流程-损失大幅下降,锅炉有效利用热量显著提高,机组功率增加27.6MW,发电煤耗率降低6.7g/(k W·h),烟气的酸露点温度和空气预热器的换热面积均有一定程度下降,机组运行经济性与安全性均得到一定的提升,年增加净收益可达1129.4万元。

In the conventional coal-fired power plant, there is a considerable amount of available energy loss and large optimized utilization space in the primary air heating process and the low-temperature heat transfer process in rear smoke channel. In order to reduce the irreversible loss of heat transfer process, in this paper, an efficient integrated system based on optimized primary air heating process was proposed. By pre-drying the high moisture raw coal entering the milling system, the heat absorption of the primary air was reduced. On this basis, the use of the two-stage steam heater heating the primary air, while optimizing the low-temperature flue gas heat transfer process and recovering of low-temperature flue gas waste heat, can significantly improve the power 6~the unit. A typical 1000MW ultra-supercritical coal-fired unit was taken as the case to study the thermodynamic calculation, energy distribution and technical economy of the efficient integrated system based on the optimization of the primary air heating process. Results show that, the exergy loss of the primary air drops sharply and the heat output of the boiler increases significantly when the moisture of raw coal is pre-dried from 18.1% to 8%. The power of unit increases 27.6MW, and the coal consumption rate decreases 6.Tg/（kW-h）. Acid dew point temperature of the flue gas and heat exchange area of the air preheater have a certain degree of decline. The operational economy and safety of the unit get ascend, and the increase of net income per year can reach 11.294 million yuan.