西南科技大学 环境与资源学院，四川 绵阳 621000
覃镜元，张宇璐，蒋佳玲，等. 气力输送中含湿量对PVC粉体起电的影响［J］. 中国粉体技术，2025，31（5）：1-8.
QIN Jingyuan， ZHANG Yulu， JIANG Jialing， et al. Effect of moisture content on electrostatic charging of PVC powder in pneumatic conveying［J］. China Powder Science and Technology，2025，31（5）：1−8.
DOI：10.13732/j.issn.1008-5548.2025.05.017
收稿日期：2024-09-30，修回日期：2025-03-12，上线日期：2025-06-27。
基金项目：国家自然科学基金项目，编号：52204286。
第一作者简介：覃镜元（1998—），男，硕士生，研究方向为气力输送。E-mail：1797183830@qq. com。
通信作者简介：林龙沅（1981—），男，教授，博士，硕士生导师，四川省学术和技术带头人后备人选，研究方向为气流粉碎、分级与除尘净化。E-mail：Lly7572@126. com。
摘要：【目的】 为了减少气力输送过程中粉体静电的产生，降低粉体静电放电风险，探究气力输送过程中聚氯乙烯（polyvinyl chloride，PVC）粉体的含湿量对粉体静电带电量的影响。【方法】 在自主搭建的气力输送实验平台上，以PVC粉体为输送对象，以荷质比为指标，研究 PVC 粉体含湿量在不同下料质量流量和不同输送速度下对粉体带电的影响。【结果】PVC 粉体含湿量相同时，粉体荷质比随下料质量流量的增大而减小，随输送速度的增大而增大；相同下料质量流量时，PVC粉体的含湿量越大，粉体荷质比越小；当下料质量流量从6. 7 g/s增大到33. 3 g/s时，粉体含湿量为0时，荷质比降幅最大，从14. 581 μC/kg减小到7. 325 μC/kg，但当粉体含湿量为3%时，下料质量流量对粉体荷质比的影响已经很小；相同输送速度时，PVC粉体的含湿量越大，粉体荷质比越小，当输送速度从7. 9 m/s增大到14. 8 m/s时，粉体含湿量为0时，荷质比增幅最大，荷质比从5. 435 μC/kg增大到34. 891 μC/kg，当粉体含湿量为2%时，输送速度对粉体荷质比影响已经很小，而当粉体含湿量增大至3%时，气力输送过程中出现输送管道堵塞现象。【结论】 气力输送过程中适当的增大PVC粉体含湿量、增大下料质量流量以及减小输送速度都能够有效抑制粉体静电电荷的积累，降低粉体静电危害风险；但粉体含湿量不宜过分增大，粉体含湿量过大易造成输送管道堵塞，当 PVC粉体含湿量为 2% 时，能够在不堵塞输送管道的同时，减小粉体静电积累，满足工程的实际应用需求。
Objective With the advancement of powder processing technology, polyvinyl chloride (PVC) powder has been widely used as a synthetic material in various fields such as plastic products, building materials, pipes, and cables. However, the electrostatic buildup risk during powder processing has gradually become apparent. During the production, transportation, processing, and storage of PVC powder, friction and collisions between particles, as well as between particles and pipelines, equipment, and containers, lead to the accumulation of electrostatic charge. When the accumulated charge reaches a certain level, electrostatic discharge can occur, potentially igniting the powder and causing fires or explosions, resulting in casualties and property damage to enterprises. The study aims to explore the impact of moisture content, feeding rate, and conveying speed on the electrostatic charge quantity in PVC powder during pneumatic conveying and to reduce the generation of electrostatic charge and the risk of electrostatic discharge.
Methods In this study, a self-built pneumatic conveying platform was used to conduct experimental research on PVC powder with different moisture contents under varying feeding and conveying speeds. First, 2 kg of PVC powder was taken, and the moisture content (d) was adjusted by changing the mass ratio of water to PVC powder. Five groups of samples with moisture contents of 0%, 1%, 2%, 3%, and 4% were prepared, labeled as S0, S1, S2, S3, and S4, respectively. After sample preparation, the effect of moisture content on the charge-to-mass ratio at different feeding rates was investigated. Based on the recommended conveying speed for PVC powder in pneumatic conveying， a conveying speed of 9. 1 m/s was selected. The 2 kg of PVC powder was then fed over durations ranging from 1 to 5 minutes. After the conveying experiments, samples were taken from the ash bunker and placed in a Faraday cup to measure the electrostatic charge. The mass of the samples was also measured, and the charge-to-mass ratio of the PVC samples was calculated. Based on the results of the previous experiments, an optimal feeding rate of 6. 7 g/s was selected as the fixed parameter for this set of experiments. The conveying speed was then adjusted by changing the speed of the induced draft fan, with five different conveying speeds of 7. 9, 9. 1, 10. 3, 11. 2, and 14. 8 m/s, to investigate the effect of moisture content on the charge-to-mass ratio at different conveying speeds.
Results and Discussion When the moisture content of the PVC powder was constant, the charge-to-mass ratio decreased with an increase in feeding rate and increased with an increase in conveying speed. When the feeding rate increased from 6. 7 g/s to 33. 3 g/s, the charge-to-mass ratio decreased the most for powder with 0% moisture content, from 14. 581 μC/kg to 7. 325 μC/kg. However, when the moisture content was 3%, the feeding rate had little effect on the charge-to-mass ratio. When the conveying speed increased from 7. 9 m/s to 14. 8 m/s, the charge-to-mass ratio increased the most for powder with 0% moisture content, from 5. 435 μC/kg to 34. 891 μC/kg. However, when the moisture content was 2%, the conveying speed had little effect on the charge-to-mass ratio. At the same feeding rate, the higher the moisture content of the PVC powder, the lower the charge-to-mass ratio. When the feeding rate was 6. 7 g/s, the charge-to-mass ratio changed the most with moisture content, decreasing from 14. 581 μC/kg to 0. 008 μC/kg as the moisture content increased from 0% to 4%. However, when the moisture content increased from 3% to 4%, the charge-to-mass ratio decreased by only 0. 029 μC/kg, indicating that further increases in moisture content beyond 3% had little effect on the charge-to-mass ratio. At the same conveying speed, the higher the moisture content of the PVC powder, the lower the charge-to-mass ratio. When the conveying speed was 14. 8 m/s, the charge-to-mass ratio changed the most with moisture content, decreasing from 34. 891 μC/kg to 0. 212 μC/kg as the moisture content increased from 0% to 2%. However, when the moisture content increased to 3%, the conveying pipeline became blocked during the pneumatic conveying experiments. Based on the charge-to-mass ratio at different conveying speeds for PVC powder with 2% moisture content, it was found that a moisture content of 2% was sufficient to meet engineering application requirements.
Conclusion During pneumatic conveying, appropriately increasing the moisture content of PVC powder, increasing the feeding rate, and reducing the conveying speed can effectively suppress the accumulation of electrostatic charge and reduce the risk of electrostatic hazards. However, the moisture content should not be excessively increased, as too much moisture can easily cause pipeline blockages. When the moisture content of PVC powder is 2%, it can meet the engineering application requirements of ensuring smooth production while reducing electrostatic charge accumulation.
Keywords：pneumatic conveying; charge-to-mass ratio; moisture content; PVC powder
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