Abstract The heating performance of empty fruit bunch pellets (EFBPs) has been limited by its low energy density, high moisture, and ash content. Hence, microwave co-torrefaction (MCT) was performed with microwave heating unto waste oil mixed EFBP to produce high-energy biofuel. However, the non-homogeneous electromagnetic fields distribution in the microwave cavity results in an uneven heating behavior, producing the hot and cold spots. Hence, MCT coupled with helical lift was examined for its potential to improve heat distribution. The effect of temperature and types of waste oil on the proximate analysis and surface properties were studied. In comparison to the conventional torrefaction using a furnace (>30 min), MCT provided rapid heating (50–80°C·min−1) and a shorter process time (10 min). The use of helical lift with 2-dimensional movement – rotational (24 rpm·min−1) and vertical motion (5 cm·min−1) simultaneously, distributed microwave radiation uniformly for rapid heating. The proximate analysis demonstrated that the ash content was reduced from 8 to 3 wt%, and the highest fuel ratio of 2.0 was achieved. Additionally, the highly porous structure of EFBP biochar can act as an activated carbon precursor. MCT coupled with helical lift represents a promising approach to prevent hot spots during microwave heating.

中文翻译：

---

用于颗粒燃料生产的微波联合烘焙与螺旋提升的集成

摘要 空果串颗粒（EFBPs）的加热性能受到其低能量密度、高水分和灰分含量的限制。因此，利用微波加热对废油混合 EFBP 进行微波联合烘焙 (MCT) 以生产高能生物燃料。然而，微波腔中的非均匀电磁场分布导致加热行为不均匀，产生热点和冷点。因此，研究了 MCT 与螺旋升力相结合的改进热分布的潜力。研究了温度和废油类型对近似分析和表面性质的影响。与使用炉子的传统烘焙（>30 分钟）相比，MCT 提供快速加热（50–80°C·min-1）和更短的处理时间（10 分钟）。使用具有二维运动的螺旋升力 - 同时旋转 (24 rpm·min-1) 和垂直运动 (5 cm·min-1)，均匀分布微波辐射以实现快速加热。近似分析表明，灰分含量从 8 wt% 降低到 3 wt%，并且达到了 2.0 的最高燃料比。此外，EFBP 生物炭的高度多孔结构可以作为活性炭前体。MCT 与螺旋升力相结合代表了一种很有前途的方法来防止微波加热过程中的热点。EFBP 生物炭的高度多孔结构可以作为活性炭前体。MCT 与螺旋升力相结合代表了一种很有前途的方法来防止微波加热过程中的热点。EFBP 生物炭的高度多孔结构可以作为活性炭前体。MCT 与螺旋升力相结合代表了一种很有前途的方法来防止微波加热过程中的热点。