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With the continuously increasing proportion of installed capacity from new energy sources, higher flexibility demands are imposed on coal-fired power generation units, including supercritical circulating fluidized bed (CFB) boilers. By taking a 350 MW supercritical CFB boiler as the research object, the computational particle fluid dynamics (CPFD) method was employed to simulate the furnace response characteristics under variable load conditions, focusing on parameters such as furnace temperature, near-wall particle concentration, and average heat flux density on heating surfaces. The effects of combustion and circulation interventions on the rate of load change were also explored. The results indicate that, during load ramp-up operation, the response rate of average heat flux density in low load range (30%~50% of the unit rated load) decreases by about 38% compared with that in high load range (above 50% of the rated load). Focusing only on the high load range, the heat flux density responds faster during load ramp-down, with the rate of change about 31% higher than that during ramp-up. Under varying load amplitudes, the particle suspension concentration and convective heat transfer intensity inside the furnace can respond rapidly, while temperature changes lag slightly, indicating that CFB boilers rely more on variations in the heat transfer coefficient for rapid thermal regulation. Through combustion interventions, such as substituting 40% of the original coal feedstock with fine coal particles sized several hundred microns, the change in furnace temperature can be effectively accelerated, with the response rate of average heat flux density during ramp-up in the high load range increasing by about 43%, and by nearly 16% in the low load range. Additionally, implementing circulation interventions, such as adding a certain amount of fine bed material during ramp-up, can rapidly increase the particle suspension concentration in a short time and thus effectively improve the response rate of the heat transfer coefficient on the heating surface. If hot fine material is further added (for example, through a hot circulating ash storage and return system), the response rate of the average heat flux density during ramp-up in the high load range can be improved by approximately 31%, and by about 13% in the low load range. The study elucidates the internal response mechanisms of CFB boilers under variable loading conditions, confirms the feasibility of improving load change rates through circulation and combustion interventions, and provides a reference for further tapping the flexibility potential of supercritical CFB boilers and improving their variable load capability.
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| 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 |
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