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宽区压榨毛毯-纸幅体系微观结构的研究(PDF/HTML)

《南京林业大学学报(自然科学版)》[ISSN:1000-2006/CN:32-1161/S]

Issue:
2017年03期
Page:
124-132
Column:
研究论文
publishdate:
2017-05-31

Article Info:/Info

Title:
Research on microstructure of felt-sheet system (FSS)in press section with the extended pressing nip
Article ID:
1000-2006(2017)03-0124-09
Author(s):
ZHU Wen1.3 YE Ping2 ZHANG Hui13*
1.Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China;
2.Jiangsu Jinni Paper-making Felt Group, Haimen 226100, China;
3.Jiangsu Co-Innovation Center for Efficient Processing and Utilization of Forest Resources, Nanjing 210037, China
Keywords:
extended nip press model experiment of pressing felt-sheet system microstructure hypothesis on the uneven compression
Classification number :
TS754; TS156
DOI:
10.3969/j.issn.1000-2006.201506043
Document Code:
-
Abstract:
【Objective】 The micro structure of felt-sheet systems(MSFSS)and its characteristics influence dewatering efficiency during pressing and is the basis upon which to develop new pressing technologies and new press felts for modern high-speed paper machines. 【Methods】The press felt and wet sheet were considered as one system, the felt-sheet system(FSS), in this study. First, a set of special experimental devices for the study was developed. Then, the change of the MSFSS in the press process was studied through a model experiment for pressing(MEP)using the device. Finally, the effects of different compressing velocities, surface structures of the press felt, and pulp types on the compressing force needed were determined. 【Results】The traditional hypothesis that the MSFSS is uniform, was incorrect. In fact, MSFSS was uneven and it appeared that, along the Z direction of the wet web and the pressure profile under the press roller’s force, the contacting area between web and felt can be divided into two parts—the ideal key pressing layer and the contact layer, in which there is a non-compressed layer with high permeability. 【Conclusion】The FSS in the direction of thickness appears uneven with stratification, and during the press process as the wet web is compressed unevenly. The non-compressed layer of FSS had advantages for the dewatering and compression process. The surface near the permeable felt was the most compact; the upper web layer would be implanted into the interspace of the FSS, which would reduce the permeability of FSS and lead to an increase in the necessary press pressure. The relationship between the pressure and compressing velocity did not conform to Darcy’s law. When the velocity exceeds a critical value, stratification will play an important part in press compression. It was also discovered that when the paper model was compressed using the wire press surface(an ideal flat permeable press surface), a peak force approximately six times higher than that for different felt surface models was required.

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Last Update: 2017-05-20