To address the issues of low reheated steam temperature and local overheating of platen superheaters (PSH) during low-load operation of a 660 MW ultra-supercritical tangentially fired once-reheat boiler, this study proposed a wall-mounted flue gas recirculation (FGR) arrangement in the burner region. The aim was to synergistically raise reheated steam temperature and suppress PSH overheating while maintaining combustion stability.
Numerical simulation was performed at 40% rated load to optimize the proposed layout. First, the baseline case and corner-mounted and wall-mounted concentrated FGR arrangements were compared. Subsequently, the feasibility of wall-mounted grouped injection was investigated.
The results indicated that: corner-mounted FGR significantly increased the ignition distance of pulverized coal jets, which adversely affected low-load combustion stability. Both fire-side and rear-side concentrated FGR increased the heat absorption of the high-temperature reheater, but neither could simultaneously mitigate PSH local overheating. Fire-side grouped FGR substantially enhanced heat absorption of the reheater but still carried a risk of PSH overheating, whereas rear-side grouped FGR reduced the overheating risk but yielded only limited reheater improvement. A combined grouped arrangement, in which flue gas was injected through the two lower layers on the fire-side wall together with the upper layer on the rear-side wall, increased the heat absorption of the reheater by 18.9%, effectively mitigated local overheating of the PSH, and maintained stable combustion.
These findings provide design and optimization references for safe, flexible, and efficient boiler operation across wide load ranges in next-generation coal-fired power plants.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |