Equipment selection and production practice of the

2022-08-26
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Equipment selection and production practice of paper machine (III)

2.4 drying section (symrun)

in order to solve the problem that it is difficult to remove the broken end and cylinder block of paper, a single-layer dryer section has appeared in the drying section of high-speed paper machine. In order to prevent the paper from shaking and breaking when it is running, a single dry blanket drive is used to make the paper close to the surface of the dry blanket. The symrun drying section is arranged in a single-layer cylinder, as shown in Figure 5. The upper layer has φ There are 32 1830mm dryers in the lower layer φ There are 31 1500mm vacuum rollers, a total of 7 groups of drying cylinders. The drying cylinder group is driven by the last two drying cylinders and a vacuum roller, and the rest of the cylinders are driven by the dry blanket. Vacuum can reduce the cases of medical equipment failure. There are grooves on the surface of the rollers and drilled in the grooves φ The 4.5mm vacuum hole cooperates with the HS blower box to realize the function of paper introduction and paper transfer. The drying cylinder is equipped with a fixed siphon and a water breaking rod. Since one side of the paper web contacts the surface of the drying cylinder, it will cause the warpage of the paper web. After a soft calendering, install a steam box, blow steam on the back of the paper web to wet it, and then iron it through the second soft calendering. Because the press adopts closed paper guiding, it will not break. In the dryer section, if the paper web is broken, the damaged paper falls onto the conveyor belt that can be reversed under the drying section and is sent to the pulper at both ends

Figure 5 symrun drying Department

Figure 6 optireel plus winder

1-lifting arm 2-coiling main arm and central main drive 3-coiling cylinder 4-auxiliary sliding 3. During operation, do not stretch into the mixing bag with hands or sticks or clear the mortar rack and central auxiliary drive at the mouth of the bag

2.5 soft calendering

as we all know, soft calendering can improve the loose thickness of the paper web, and the difference between the two sides of smoothness can be corrected, It is more and more popular with newspaper printing. This soft calender is equipped with two pressing areas, the first hard roll (hot roll) is on the top and the soft roll is on the bottom; The second is the opposite. The pressurization is realized by the oil cylinder on the lower roll, and the line pressure is controlled at about 110kn/m. The four rollers are separately equipped with motor drive. The hot roll is a controllable roll. The first roll is divided into 38 areas and the second roll is divided into 8 areas. The temperature of the hot roller of the paper only needs 120 ℃, and water can be used as the heating medium, but 0.7 ~ 0.8MPa steam is required. In order to be safe, we use the oil heating system, and the temperature can reach 150 ℃. In the actual production and operation, the smoothness difference between the front and back sides of the paper can tend to 0, and the moisture content of the paper can be increased to more than 8%

2.6 paper reeling machine

a good paper reeling machine should ensure that the internal and external tightness of the paper roll is consistent, the diameter of the paper roll should be as large as possible, so as to reduce the time of changing the roll, and the loss of paper should be less. Valmet's optireel plus paper reeler rolls 3.7m in diameter, as shown in Figure 6. Its latest coiling concept is to control the three main parameters of the master coil: the loading line pressure in the pressure zone between the coiling cylinder and the master coil, the tension of the paper web and the circumferential force. Its coiling is always automatically controlled. When an empty paper shaft comes down from the paper shaft frame, it is clamped by the locking clamp of the coiling main arm and pressed against the coiling cylinder. When coiling starts, the central main drive (on the operating side) starts to provide torque. After the mother coil slowly becomes larger, the auxiliary carriage loads the load of the mother coil. When the mother coil is larger, the central auxiliary drive (on the drive side) begins to provide torque. Through the above function control, the internal and external tightness of the parent coil can be kept consistent during normal operation or coil change

2.7 rewinder

there are two Windrum m rewinder, the maximum speed is 2300m/min, which matches the speed of the paper machine 1600m/min, and there is a certain margin, so there is no automatic winding core adding device. The finished product is 787mm wide and 7 rolls, and the guaranteed diameter of the finished paper roll is 1250mm. One of the factors affecting the tightness of the paper roll is the rewinding pressure between the paper roll and the bottom roll. When the diameter of the paper roll increases, the rewinding pressure is controlled by adjusting the loading of the paper roll; The second is the tension of the paper, which is controlled by the tension sensor to maintain the set value during operation; The third is rewinding force. Previously, the rewinding force was the result of the adjustment of torque or torque ratio, and the size can be judged by the torque ratio of the bottom roll. When the diameter and inertia of the bottom roll are different, it is difficult to judge the size of the rewinding force according to the torque or torque difference of the bottom roll without a calculator. The rewinding force of this rewinder is determined by the control system. The electric drive generates the required torque of the front bottom roll, adjusts the speed of the rear bottom roll, and the torque is set. In this way, the balance of force between unwinding and rewinding is maintained in a certain state, ensuring the tightness of the paper roll

2.8 wrapping production line

this streamline paper roll packaging line only needs three people to operate, packaging 90 rolls of finished products per hour. In addition to pasting inner head, outer head, label, etc., other functions are controlled by roadtm paper roll data management system. The paper roll enters the rotary table from the chain conveyor behind the rewinder, and then to the centering table. The paper roll bar code identification, weighing, diameter and width measurement, label printing, and then sent to the wrapping and folding station. Its packaging paper is 150g/m2, wrapped in 2 layers, and finally to the head end station, where the head end paper is manually loaded. The wrapped finished paper roll is unloaded and turned over by the web, sent from the 7m floor to the 0m floor warehouse and stacked vertically

3 production practice

pm5 project broke ground on August 16, 1998, began to install the base plate of the paper machine on May 10, 1999, installed the first dryer vacuum roller on June 6 to the end of the installation on October 31, started to output paper on December 17, and started to cut color during the national paper order meeting on December 23, and produced 48.8g/m2 qualified paper at the speed of 1270m/min. The whole startup process was very smooth

in the first 12 months of startup, through pulp 4. Experimental speed: 0.5mm/min (5) 00mm/min 14 gear speeds (please specify if there are special requirements) (experimental speed: 0.001mm/min (5) 00mm/min) multiple gear speeds, continuous optimization of material ratio, chemical additives, wool fabric adaptability and other processes, the maximum monthly output is 16000T, that is, the average daily paper output is 516t, its maximum daily output is 607t, and it has operated for 2h at the speed of 1703m/min, becoming the fastest paper machine in Asia. The pilot production of 45g/m2 low weight offset paper has been successful in the pilot printing of color newspapers in Fujian society and Zhejiang society, which shows that this paper machine has reached the design performance. Because the press section of the paper machine adopts vacuum fully enclosed paper introduction, and the winder automatically changes the roll, etc., the end of the paper web is mainly in the dryer section, and the paper breaking time accounts for about 30% of the unplanned shutdown of the paper machine. Other factors affecting the shutdown are mainly the so-called "rejuvenation" starting point is no longer China's one pressure vibration and two pressure oil leakage, which are still controlled by people, but the working efficiency of the paper machine has exceeded 90%

in the pilot production of the paper machine, we mainly did the following optimization work

(1) this paper machine uses TMP, dip, GP and BKP pulps to make paper. Valmet company has no practical experience in the impact of resins in masson pine pulp on paper machine papermaking. We add resinase to TMP and GP to eliminate harmful resins in the pulp, and adjust the appropriate dip (one-stage flotation) ratio to reduce the impact of ink on paper machine papermaking

(2) the main problems of the press section are to solve the problems of vibration of the first press, bubbles in the paper sheet of the second press, and short service life of the wide area press shoe block. The other is to optimize the specification of woolen cloth. We have tried the woolen cloth of several suppliers, and it took a long time to increase the quantity from 1280g/m2 to 1720g/m2. At present, the more suitable woolen cloth for paper introduction is 1700g/m2, 1650g/m2 for pressing down the woolen cloth, and 1400g/m2 for pressing up the woolen cloth. Choosing a suitable woolen cloth plays a great role in reducing the pressing vibration and stable operation performance

(3) transform the white water system to reduce fiber loss. The first is to reduce the concentration of the lower white water. The inner and outer parts are woven in two layers, and also used in two and a half layers. The outer and inner parts are woven with polymer wires with different diameters, and the permeability is different. When the sizing concentration is about 0.9%, the concentration of the lower white water is stable at 0.36% - 0.44% when polyacrylamide and polyethyleneimine are added in front of the flushing pump and bentonite and other retention aids are added in front of the paper machine screen. The second is to replace the pulp supply pump of four kinds of pulp, improve the pulp concentration of incoming paper, reduce the white water volume, optimize the process of multi tray and dehydrator, and reduce the concentration of white water system

after a year of continuous optimization and transformation, the operation of the paper machine is relatively normal. The water consumption per ton of paper is 9 ~ 10t, the power consumption is 640kwh, and the steam consumption is 1.3t. The paper quality is good, which is welcomed by users, and the product supply exceeds the demand. (end)

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