二次再热机组烟气余热利用与抽汽参数优化研究

对某1 000 MW二次再热机组应用遗传算法进行余热利用和抽汽的整体优化。余热利用方式选择两种:方案1,低压回热加热器之间引入低温烟水换热器;方案2,采用空气预热器分级布置,在水侧高温烟水换热器与1~#高压加热器并联在烟气侧高温烟水换热器与高温空气预热器并联,出口烟气汇合后进入低温空气预热器。结果表明,机组在余热利用后对最佳抽汽口位置有很大影响;采用方案2整体优化后发电功率增加最明显,可以使机组发电功率增大21 170 kW,发电效率比单独优化提升明显。此外,研究表明,在锅炉烟气余热利用时需要余热和回热同步优化。

Optimization Study on Utilizing Waste Heat of Flue Gas and Extraction Parameters for Secondary Reheat Unit

The genetic algorithm is applied to optimize the overall optimization of waste heat utilization and steam extraction for 1000 MW secondary reheat unit.Among them,two waste heat utilization options are slected.In Option 1,a low-temperature flue-water heat exchanger is introduced between the low-pressure regenerative heaters.In Option 2,air preheaters are arranged hierarchically.High-temperature flue-water heat exchanger and 1# high-pressure heater are arranged in parallel on the water side and the high-temperature flue-water heat exchanger and high-temperature air preheater are arranged in parallel on the flue gas side.Finally,the outlet flue gas merges into the low-temperature air preheater.The results show that the waste heat utilization of the unit has a great influence on the optimal steam extraction port position; the overall optimization of the power generation by using Option 2 can increase the power generation power of the unit most significantly,which can increase the power generation power of the unit by 21 170 kW,and the power generation efficiency is significantly improved compared to the optimization alone.Waste heat and regenerative heat optimize simultaneously is necessarily in utilization of boiler flue gas waste heat.