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【目的】了解毛毯-纸幅体系在压榨过程中的结构变化以及压缩速度、不均匀压力作用对于湿纸幅水分脱除动力学的影响。【方法】将毛毯和纸幅视作一个综合作用体系加以研究,首先研发了一套专门实验装置,通过压榨模拟实验研究压缩过程毛毯-纸幅体系微观结构上的变化,进而研究不同压缩速度、不同毛毯表面结构以及不同浆种对压缩过程所需压力的影响。【结果】(1)宽区压榨毛毯-纸幅体系微观结构为非均匀性结构;靠近渗透毛毯表面最为致密,且最上层纸幅会嵌入毛毯纸幅空隙中,使得毛毯-纸幅体系整体渗透性降低,所需压榨压力增加。(2)采用铁丝面和中网面模型压缩过程中,当加压试验速度从51 mm/min变为99 mm/min时,后者压力峰值约为前者的4倍;加压试验速度从99 mm/min变为124 mm/min时,后者压力峰值约为前者的2.3倍。但当压缩速度从124 mm/min变为99 mm/min(减小20%)时所需作用力减小了50%左右,并不符合达西定律。(3)在同一加压速度下,采用铁丝网面模拟压榨过程所需的压力是采用3种毛毯表面模型模拟压榨过程所需的压力的5倍左右。而采用3种毛毯表面模型模拟压榨过程所需的压力值几乎相同。(4)采用中网面毛毯表面模型时,当没有加入中间刚性层,试验速度从51 mm/min变为99 mm/min时,压缩过程所需的压力并没有明显的变化。当试验速度从99 mm/min变为124 mm/min(即增加25%)时,所需压力增加150%左右。在试验速度为51 mm/min时,压缩过程所需压力基本一致;当试验速度为99 mm/min时,采用中间刚性层实验组所需的压力峰值比没有采用的组大;当试验速度变成124 mm/min时,现象却相反。【结论】在压榨过程中纸幅模型在厚度方向上呈现不均匀性。纸幅模型在压缩过程中,压缩速度相同时压榨毛毯表面模型选用的不同,所需的载荷也不相同,当采用铁丝网面(即理想化平整的压榨表面)时,所需的压力最大;而压缩速度越大,所需的压力值也就越大,且压力的大小与速度的变化关系并不符合达西定律。在纸幅模型层之间加入中间刚性层之后,相同的加压试验速度下,采用理想化细密平坦的压榨表面所需压力的峰值会减小。
【Objective】 The objective of this paper is to understand the structural changes of the felt-web system during the pressing process, as well as the effects of the compression speed and the non-uniform pressure on the moisture removal kinetics of the wet web. 【Method】 Considering the blanket and the paper web as a comprehensive system, a set of special experimental equipment was developed. The squeeze simulation experiment was carried out to study the microstructure of the blanket-web system in the compression process. Then the effects of different compression speed, Effect of Different Blanket Surface Structures and Different Slurries on Compression Required Pressure. 【Result】 (1) The wide-area press felt-web system has a non-uniform microstructure. The surface near the infiltrated felt is the most compact, and the topmost web is embedded in the blank space of the felt web so that the whole felt-web system penetrates Decrease in sex, press pressure required increase. (2) In the process of compressing the wire surface and middle mesh model, the pressure peak value of the latter is about 4 times of that of the former when the compression test speed is changed from 51 mm / min to 99 mm / min. The compression test speed is from 99 mm / min to 124 mm / min, the latter peak pressure of about 2.3 times the former. However, when the compression speed is changed from 124 mm / min to 99 mm / min (20% reduction), the required force is reduced by about 50%, which is not in accordance with Darcy’s law. (3) The pressure required to simulate the pressing process using wire mesh at the same pressing speed is about 3 times the pressure required to simulate the pressing process using three kinds of felt surface models. The pressure values required to simulate the pressing process using the three felt surface models are almost the same. (4) When using the medium mesh blanket surface model, the pressure required for the compression process did not change significantly when the test speed was changed from 51 mm / min to 99 mm / min without adding an intermediate rigid layer. When the test speed is changed from 99 mm / min to 124 mm / min (ie 25% increase), the required pressure is increased by about 150%. When the test speed is 51 mm / min, the pressure required for the compression process is basically the same. When the test speed is 99 mm / min, the peak pressure required by the experimental group with the middle rigid layer is larger than that without the test group. At 124 mm / min, the opposite is true. 【Conclusion】 The paper web model shows inhomogeneity in the thickness direction during the pressing process. The required load is also different for the paper web model when the compression speed is the same, and the load required is different for the pressed felt surface model. The pressure required when using the wire mesh surface (ie, the idealized flat press surface) The greater the compression speed, the greater the pressure required, and the relationship between pressure and speed does not comply with Darcy’s law. With the addition of an intermediate rigid layer between the web pattern layers, the peak pressure required for the idealized, closely spaced press surface will be reduced at the same rate of pressurization test.