In recent years, China’s homebred paper machinesand key supporting components have achievedgreat progress in operation speed, wire width,energy saving, compactness and automation. Theoverall operation performance of China homebredpaper machine will be discussed in the next issue.In this issue, the key supporting components ofpaper machines will be clarified below.
Nowadays, the deviation of profile basis weightis usually controlled by means of regulating theconsistency with dilution water on modern highspeedpaper machines. This regulating method isfeatured with high precision and efficiency, and theability to keep the slice from deformation. Basedon the existing air-cushion headbox technology,Zhejiang Huazhang Technology (formerlyHangzhou Meichen) and Henan Dazhi PaperMachinery have developed the dilution waterhydraulic headbox with independent intellectualproperty.
The dilution water headbox (Figure 1) developedby Henan Dazhi Machinery has been applied toPM6 5600/1500 horizontal twin-wire formingpaper machine in Henan Jianghe Paper Co., Ltd.Specifications: slurry volume 1423L/s; designedslurry consistency 0.9%-1.5%; slice width:6180mm; upper slice trimmers: 61 sets; distancebetween upper slice trimmers: 102mm; distancebetween dilution white water valves: 60mm; themax. diluting water volume: 7%-12% on totalslurry volume.
The twin-wire former has a better performancecompared with that of the traditional one. Itcould realize sheet dewatering from both sides toimprove the sheet two-sideness, raise dewateringefficiency, forming quality, as well as theproductive capacity. Moreover, short and closedforming area makes it more adapted to high-speedoperation. And a more compact internal structureof the former helps to lower its space requirement.
The twin-wire former (Figure 2) developed byDazhi Machinery has been installed on PM65600/1500 paper machine in Henan Jianghe PaperCo., Ltd. It realized various dehydration methods,such as pressurized dehydration, pulse dehydration,centrifugal dehydration and vacuum dehydration.The innovative progress has been made in theregulating device for slurry jet location and jetangle, elastic pressurized dehydration shoe, arcshapeddehydration tank and air-flow interferencereducer, as well as white water collectors.Maximum vacuumdegree of various dehydrationdevices is as follow: dehydration tank: -5kPa;upside-down suction box: -7.6/-10/-20kPa; highvacuumbox: -20/-33/-65/-65kPa; vacummcouch roll: -45/-65kPa.
Shoe press technology is featured by high webdryness,good operating efficiency and improvedproduct quality, making it one of the majoreffective solutions for energy conservation of papermachine. It’s predicted that in the near future,traditional roller press will be completely replacedby shoe press that is more adapted to the mediumand high-speed paper machines (500-1500m/min).
The newly developed shoe press (Figure 3) byShandong Changhua Machiner y is of g reatinnovation. Firstly, there are four functionalareas (static pressure nip, dynamic pressure nip,oil discharging area, and oil level holding area)between shoe plate and blanket, which couldstrengthen the lubrication and form a properpressure distribution. Secondly, the sealing devicethat matches frame type oil seal with wear-resistantsleeves prolongs the lifetime and brings about goodsealing effect. Thirdly, roll shell forging technologywas applied to accommodate with the alternatingstress resulted from high linear pressure. Theinnovative achievement for shoe press facility hasbeen applied in practical production.