Abstract:

The design lifespan of wind turbines is 20—25 years. The wind turbines put into operation around the year 2000 are about to be retired in China. With the increasing installed capacity of wind turbines year by year, the demand for resource utilization of retired turbines will surge in subsequent years. Due to the long length, light weight, and high strength characteristics, suitable scale recycle methods have not been found for wind turbine blades. Based on the assumptions of the current installed capacity of 440 million kilowatts and a composite material consumption of 16kg per kilowatt, the national wind turbine blade composite material market is approximately 7.04 million tons. The stacking density of wind turbine blades broken to the centimeter level is relatively small, only 39% of that of coal powder, and the transportation cost is relatively high. Based on a transportation distance of 200 kilometers, the transportation cost per ton of blades has reached 1200—1500CNY (excluding costs such as dismantling, cutting, and crushing). From an economic perspective, coupling with coal-fired boilers for co-firing is a promising large-scale recycle route. Wind turbine blades have good ignition and burn out characteristics. Starting at 224℃, weight loss occurs, and the characteristic temperatures during the ignition and burnout stages are 264℃ and 504℃, respectively. The ignition and burnout performance are better than those of coal. The residue of the burned blades is mainly glass fiber, and the elemental composition is mainly silicon, aluminum, calcium, and magnesium in the form of oxides. Wind turbine blades have the characteristics of high nitrogen, and low calorific value. A typical wind turbine blade has a dry nitrogen content of 0.82%, and an air-dry calorific value of 1849kcal/kg. There is a significant difference in the nitrogen structure between coal and wind turbine blades. Coal nitrogen mainly exists in the form of pyrrole nitrogen, accounting for 85%, while wind turbine blade nitrogen is mainly composed of amide structure, accounting for 90.6%. After being heated, amide structure nitrogen is more easily released into gas-phase nitrogen. The results of the co-firing experiment show that there is no significant change in pollutant NO emissions within a 10% co-firing ratio (weight ratio). According to a 10% co-firing ratio, a 300MW coal-fired boiler can tackle with the blade composite materials produced by 3052MW retired wind turbines annually. This means that the current coal-fired boiler can fully tackle with the solid waste generated by future retired wind turbines.

Key words: wind turbine blade, drop tube experiments, coal, co-firing, nitric oxide, resource utilization of solid waste

摘要：

风电机组设计寿命在20~25年之间。我国在2000年前后投运的风电机组即将迎来第一波退役潮，随着风电机组新增装机容量逐年增加，后续年退役机组的资源化利用需求将激增。风电叶片由于长度较长、质量轻、强度大等特点，一直未能找到合适的规模处置办法。按目前4.4×10⁸kW的装机，每千瓦装机复合材料用量16kg测算，全国风电叶片复合材料市场约704×10⁴t。风电叶片破碎到厘米量级后，堆积密度较小，仅为煤粉的39%，运输成本较高，按200km运距测算，每吨叶片仅运输成本一项就已达1200~1500CNY（这还不包括拆除、切割、破碎等费用），从经济角度看，与燃煤锅炉耦合掺烧是一项较有潜力的规模处置路线。风电叶片具有极易着火、极易燃尽的特点。在224℃开始失重，着火和燃尽阶段特征温度分别为264℃和504℃，着火性能和燃尽性能均优于煤，燃尽后的叶片剩余物主要是玻璃纤维，元素成分主要是以氧化物形态存在的硅、铝、钙、镁元素。风电叶片具有高氮、低热值的特点。典型叶片干燥基氮为0.82%，空干基热值1849kcal/kg。煤与风电叶片的氮结构形态差异较大，煤氮主要以吡咯氮形式存在，占比达到了85%，而风电叶片氮主要为酰胺结构，占比为90.6%，酰胺结构氮受热后更易向气相氮释放。沉降炉耦合掺烧实验结果表明，在10%掺烧比例内（质量比），对污染物NO排放没有明显变化。按10%掺烧比例测算，一台300MW燃煤锅炉，每年可以消纳3052MW退役风电机组所产生的叶片复合材料，这意味着现役的燃煤锅炉已完全可以消纳将来待退役的风电机组所产生的叶片固体废弃物。

关键词: 风机叶片, 沉降炉, 煤, 掺烧, 一氧化氮, 固废资源化利用