Municipal solid waste (MSW)'s 40–60 % carbon content makes it a feedstock for biofuel production via pyrolysis. One challenge in the conversion process is MSW fouling due to thermal decomposition. The accumulated deposit on the injection screw often leads to plugging and constriction. This study examined the morphology and composition of the MSW fouling deposit and conducted a thermal simulation to understand the temperature gradience of the injection screw. Surface modifications including smoothening and anti-adhesion coating were proposed for the injection screw to address the deposit problem. For evaluating the candidate mitigations, a bench-scale fouling test was developed with the gas environment, temperature, and sliding speed relevant to the contact interface between the MSW particles and the screw. Results suggested that a smoother screw surface could reduce the grip and a non-metallic coating with a lower surface energy could decrease adhesion, consequently leading to less fouling. Specifically, reducing the roughness from 2 to 0.6 and then to 0.2 μm proportionally decreased the amount of deposit, and the diamond-like-carbon, CrN, and NiCr–CrC composite coatings effectively hindered the fouling process. This study provides fundamental insights into the MSW fouling and proof-of-concept of potential mitigations through the screw surface modification.

中文翻译：

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通过螺杆表面改性减轻生物燃料转化中的城市固体废物污染


城市固体废物 (MSW) 的碳含量为 40-60%，使其成为通过热解生产生物燃料的原料。转化过程中的一项挑战是城市固体废弃物因热分解而结垢。注射螺杆上积累的沉积物通常会导致堵塞和收缩。本研究检查了城市固体废弃物污垢沉积物的形态和成分，并进行了热模拟以了解注射螺杆的温度梯度。建议对注射螺杆进行表面改性，包括平滑化和抗粘附涂层，以解决沉积问题。为了评估候选缓解措施，开发了一种小型污垢测试，其中包括与城市固体废弃物颗粒和螺杆之间的接触界面相关的气体环境、温度和滑动速度。结果表明，更光滑的螺杆表面可以减少抓力，而具有较低表面能的非金属涂层可以降低粘附力，从而减少污垢。具体来说，将粗糙度从2μm降低到0.6μm，然后降低到0.2μm，沉积物量按比例减少，类金刚石碳、CrN和NiCr-CrC复合涂层有效地阻碍了结垢过程。这项研究提供了对城市固体废弃物污染的基本见解，并通过螺杆表面改性进行了潜在缓解措施的概念验证。