In recent years, China’s homebred paper machines and key supporting components have achieved great progress in operation speed, wire width, energy saving, compactness and automation. The overall operation performance of China homebred paper machine will be discussed in the next issue. In this issue, the key supporting components of paper machines will be clarified below.
河南大指研发的稀释水流浆箱（见图1），应用在江河纸业PM6 5600/1500的水平夹网纸机上，主要参数：上浆量1423L/s，设计上网浓度0.9%～1.5 %，唇口宽度6180mm，上唇板微调器个数61个，上唇板微调器距离102mm，稀释白水控制阀间距60mm，稀释水量为总进浆量的7%～12%。
1. Headbox with dilution water
Nowadays, the deviation of profile basis weight is usually controlled by means of regulating the consistency with dilution water on modern highspeed paper machines. This regulating method is featured with high precision and efficiency, and the ability to keep the slice from deformation. Based on the existing air-cushion headbox technology, Zhejiang Huazhang Technology (formerly Hangzhou Meichen) and Henan Dazhi Paper Machinery have developed the dilution water hydraulic headbox with independent intellectual property.
The dilution water headbox (Figure 1) developed by Henan Dazhi Machinery has been applied to PM6 5600/1500 horizontal twin-wire forming paper machine in Henan Jianghe Paper Co., Ltd. Specifications: slurry volume 1423L/s; designed slurry consistency 0.9%-1.5%; slice width: 6180mm; upper slice trimmers: 61 sets; distance between upper slice trimmers: 102mm; distance between dilution white water valves: 60mm; the max. diluting water volume: 7%-12% on total slurry volume.
2. Twin-wire former
The twin-wire former has a better performance compared with that of the traditional one. It could realize sheet dewatering from both sides to improve the sheet two-sideness, raise dewatering efficiency, forming quality, as well as the productive capacity. Moreover, short and closed forming area makes it more adapted to high-speed operation. And a more compact internal structure of the former helps to lower its space requirement.
The twin-wire former (Figure 2) developed by Dazhi Machinery has been installed on PM6 5600/1500 paper machine in Henan Jianghe Paper Co., Ltd. It realized various dehydration methods, such as pressurized dehydration, pulse dehydration, centrifugal dehydration and vacuum dehydration. The innovative progress has been made in the regulating device for slurry jet location and jet angle, elastic pressurized dehydration shoe, arcshaped dehydration tank and air-flow interference reducer, as well as white water collectors. Maximum vacuum degree of various dehydration devices is as follow: dehydration tank: -5kPa; upside-down suction box: -7.6/-10/-20kPa; highvacuum box: -20/-33/-65/-65kPa; vacumm couch roll: -45/-65kPa.
3. Shoe press
Shoe press technology is featured by high webdryness, good operating efficiency and improved product quality, making it one of the major effective solutions for energy conservation of paper machine. It’s predicted that in the near future, traditional roller press will be completely replaced by shoe press that is more adapted to the medium and high-speed paper machines (500-1500m/min).
The newly developed shoe press (Figure 3) by Shandong Changhua Machiner y is of g reat innovation. Firstly, there are four functional areas (static pressure nip, dynamic pressure nip, oil discharging area, and oil level holding area) between shoe plate and blanket, which could strengthen the lubrication and form a proper pressure distribution. Secondly, the sealing device that matches frame type oil seal with wear-resistant sleeves prolongs the lifetime and brings about good sealing effect. Thirdly, roll shell forging technology was applied to accommodate with the alternating stress resulted from high linear pressure. The innovative achievement for shoe press facility has been applied in practical production.