The bar angle of the curved bar plate is defined, and the two plates are used in the refining of bleached sulphate eucalyptus pulp (BSEP)
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(2) Refining Characteristics of Hardwood Pulp Using Straight- and Curved-bar Plates. 1. Introduction. angle. Therefore, the quality of fiber or pulp will be more uniform when refining with a curved or log-. The disc refiner is an important piece of equip-. arithmic spiral bar plate, and the design method,. ment for improving the properties of fiber and pulp. mathematical analysis and experimental study of. in the pulp and paper industry. During refining,. curved bar plates need to be further developed.. the pulp is fed into a groove-type rotating refining. Previous theoretical and empirical studies have. zone composed of a stator and a rotor and sub-. proposed different views on the refining charac-. jected to complex mechanical actions, such as the. teristics of the curved bar plate. The medium-. shearing and compression of bars and friction. density fiberboard (MDF) spiral plate and the. between the fibers, which induce a change in fiber. LemaxX series plate proposed by Andritz3,4) adopt a. morphology and pulp properties; finally, the. spiral-bar design to ensure the stability of the. desired properties of the target paper are achieved.. bar-interaction angle and uniformity of the pulp. The plate is the core working part of the disc. quality. Some studies have expressed that the cut-. refiner, and its bar profile directly affects the. ting effect of the curved-bar plate is weaker than. refining quality, refining efficiency, and energy. that of the straight bar,5-7) but the actual refining. consumption. Plates are usually assembled from. effect has not been tested and verified experimen-. many segments with the same bar parameters,. tally. It has been found that the pulp velocity dis-. which include the bar width, groove width, bar. tribution in the refining zone refined by the curved. 1,2). height, bar angle, and dams.. Plates with differ-. bar plate is relatively uniform, which is beneficial. ent bar parameters are used in mills, so it is. to the improvement of pulp quality, compared to. important to reveal the nature of how the bar pro-. the pulp velocity distribution associated with the. file effects the pulp and fiber properties to reason-. straight bar when studied by numerical simulation.8). ably select and design the segments.. However, Georges and Matech9) thought that it was. Many plates are involved in pulp refiners, and. doubtful that the curved bar plate could make the. broadly speaking, there are two main types of. refining quality uniform with a higher refining. plates: ones with straight bars and ones with. efficiency, which means that the refining charac-. curved bars. Currently, straight bar plates are. teristics of curved bar plates need to be studied. widely used, and the conventional bar angle of. further to clarify the difference between it and the. straight bar plates is 15° to 20°. However, there is a. straight bar plate.. disadvantage with these bars; the bar interaction. The refining characteristics of plates on pulp or. angle changes during the interaction of the rotor. fibers are directly related to the refining intensity.. and stator bars. If the straight bar plate has a bar. Studies on the refining intensities have been pub-. angle of 10°, the bar interaction angle will vary. lished,10-18) but few of them have focused on the. between 15° and 40°, with an average angle of 30°,3). curved bar plate. The specific edge load (SEL) is. which will lead to a unstable pulp flow and uniform. the most commonly used refining intensity in the. pulp quality in the refining zone. Theoretically, the. pulp and paper industry. If the value of it is 3 to 5. use of a curved bar plate in refining can solve the. J/m, it is suitable for the refining of long fiber. problem of too much change of the interaction. pulp, which has a strong cutting effect on fiber,. angle to a certain extent due to the special geo-. allowing for high intensity refining. Short fiber. metric shape, especially for the logarithmic spiral. pulp needs to be developed by a good fibrillation. bar plate, which makes a constant bar interaction. during low intensity refining with SEL values. 46. 펄프·종이기술 51(5) 2019.
(3) Huan Liu·Jixian Dong·Xiya Guo·Xiaojun Jiang·Chong Luo·Xiaohui Tian·Ruifang Yang·Litao Zhang·Bo Wang·Yan Yan. ranging from 0.5 to 2 J/m.19) The average fiber. the pulp and paper industry, as shown in Fig. 1a,. length and width of hardwood is 0.6 to 2 mm and. using angles α+90° between AB and OB and β. 0.01 to 0.04 mm, respectively. The commonly used. between the tangent of the curved-bar end point C. SEL for hardwood is 0.6 to 0.8 J/m, which is typi-. and the radius OC to indicate the curved bar, in. 20). cal for low intensity refining.. The SEL has obvi-. which the definition of the angles at the starting. ous advantages for measuring the refining process. point B and the end point C are different. Hackl et. with different straight bar plates, while it can be. al.22) designed a non-paper used refining plate in. applied to measure the refining characteristic of. which the curved bar is represented by the angles. pulp refined by curved bar plates needs to be fur-. α and β at the starting point B and the ending point. ther studied.. C, as shown in Fig. 1b; the drawing and measuring. Based on the controversy about the different. of the tangent are complicated.. refining characteristics of curved bar and straight. Only one bar edge of the curved bar was defined. bar plates, curved bar and straight bar plates with. by the above two methods, which cannot express. the same bar parameters were designed by defining. the full arc of the curved bar. By analyzing these. the bar angle of the two plates. Additionally, the. previous studies, a new definition of the curved bar. bar edge length (BEL) of the curved bar plate was. is proposed in this paper. The arc that passes point. derived to better characterize the two plates. The. C, the intersection of the centerline of the segment. object of this article are to explore the difference in. and the center circle of the refining area are called. the refining characteristics of the straight bar and. the curved bar centerline, which is denoted by. curved bar plates mentioned above based on. angle α (the bar angle of the curved bar) and point. experiments, the SEL and the bar force.. B (the starting point of the curved bar), as represented in Fig. 2a. Therefore, the curved bar centerline was determined by the location B, which. 2. Experimental. can be described by θ and rB, and the bar angle α measuring the average radian of the curved bar.. 2.1 Bar angle of straight and curved bar plates Leider and Rihs21) designed a curved-bar plate for. The attack angle between the stator and rotor bars can be characterized by static attack angle γ, as shown in Fig. 2a, which will measure the interlac-. Fig. 1. Representation of curved bar Leider et al. (1997) (a)21) and Hackl et al. (2012) (b)22).. J. of Korea TAPPI Vol.51 No.5 Sep.-Oct. 2019. 47.
(4) Refining Characteristics of Hardwood Pulp Using Straight- and Curved-bar Plates. Fig. 2. Definitions of curved bar angle (a) and straight bar angle (b). characterization parameters and its unit, Pnet is the. ing of the bars during refining. The definitions of the straight bar angle and. net refining power (kW), n is the rotation speed. static attack angle are similar to those of the. (rpm), and A is the characterization parameter of. curved bar. The angle α between the straight bar. the refining plate.. centerline and the center axis of the segment is. The characterization parameter A comprehen-. defined as the bar angle, and the angle γ between. sively characterizes the impact of the plate on the. the straight bar centerline of the stator and that of. pulp or fiber. The characterization parameters of. the rotor is its static attack angle, as represented. the plate mainly include the BEL (bar edge length)-. in Fig. 2b. The straight bar is determined as soon. based characterization parameters and the charac-. as the angle α is fixed.. terization parameters based on the bar interaction. Under the same refining conditions, a larger value. 2.2 Characterization parameters of curved and straight bar plate Many studies have been conducted on refining intensity, which is used to characterize the. of the characterization parameter results in a smaller refining intensity, which leads to a reduction of the cutting effect of the fibers and an improvement of the fibrillation performance.. strength of the refining process. The refining. The SEL is a common way of quantifying the. intensity can be divided into the machine intensity. refining intensity, which denotes the net energy. and the fiber intensity according to the benchmark. applied to each meter of the bar crossing (J/m) and. of energy consumption,23) The machine intensity. is calculated by Eq. 2,. can be summarized by the SEL-based refining intensity, and the refining intensity based on bar 24). interaction,. which is generally defined in Eq. 1, I . SEL . Pnet n BEL. [2]. where BEL is the bar edge length (km/rev), some-. Pnet n A. [1]. times referred to as the cutting edge length (CEL), which is the SEL characterization parameter.. where I is the refining intensity (its unit depends 2. The BEL is the total bar edge length that the. on A, which is generally J/m and J/m ), which is. fibers will experience during the intersection of the. the refining energy consumption based on different. opposite bars per revolution, and the standardized. 48. 펄프·종이기술 51(5) 2019.
(5) Huan Liu·Jixian Dong·Xiya Guo·Xiaojun Jiang·Chong Luo·Xiaohui Tian·Ruifang Yang·Litao Zhang·Bo Wang·Yan Yan. measure in the industry is provided by TAPPI standard TIP 0508-05 (1994), as shown in Eq. 3: BEL . r2. r1. nr n s dr cos . . [3]. where r1 is the inner radius of the plate (mm), r2 is the outer radius of the plate (mm), nr is the total number of bars for a rotor, ns is the total number of bars for a stator, and α is the bar angle of the plate (°). For calculating the BEL of the plates, the bar segments were divided into several zones, and the number of bars and their lengths for each zone were counted, so the BEL of the straight bar plate. Fig. 3. T he calculation of the BEL of the curved bar.. was calculated by Eq. 4: n n BEL 1 ri si r cos i. R x=R 0+n /(g +b ). [6]. [4] where R 0 is the radius central bar centerline of. where nri is the total number of bars for a rotor at. the plate (mm); n is the number of bars at the base. zone I , and n ri is the total number of bars for a. of the central bar, which is indicated in Fig. 3; g is. stator at zone i.. the groove width of the plate (mm); and b is the. The calculation principle of the BEL of the curved. width of the bar (mm).. bar is the same as that of the straight bar, while it. Through the analysis of the characterization. is difficult to measure the BEL by the integral form. parameters of the two different plates, the refining. due to the special shape of the curved bar. Similar. intensity under the same refining conditions can be. to Eq. 4, the refining area can be divided according. obtained.. to the r1 and r2, as well as the distribution of the curved bar, which can be found through previous 2). studies, as shown in Fig. 3. Thus, the BEL can be calculated by Eq. 5: . 2.3 Refining In this experiment, bleached sulphate eucalyptus pulp board was used as the experimental material.. BEL 1 nri nsi i. i Rx 180. It was soaked in distilled water for 4 h and then [5]. dissipated by a pulp disintegrator PD10 (TLS, San Sebastian, Spain), and its consistency was adjusted. where γ i is the center angle of the curved bar. to 3%. The MD3000 single-disc experimental. centerline at zone I, and Rx is the circle radius of. refiner (Regmed, Osasco, Brazil) was used, as. the curved bar centerline.. shown in Fig. 4a, and the refining experiments were. The circle radius Rx of the curved bar centerline. conducted using the straight and the curved bar. on the plates can be expressed by Eq. 6, according. plates at a constant speed (1,460 rpm). The two. to the design method of curved bar plates men-. plates with the same bar angle and related bar. 25). tioned earlier.. parameters were directly processed by Nantong Huayan Casting Co., Ltd. (Nantong, China) through. J. of Korea TAPPI Vol.51 No.5 Sep.-Oct. 2019. 49.
(6) Refining Characteristics of Hardwood Pulp Using Straight- and Curved-bar Plates. the computer numerical control machine tools. were collected at a constant gap of 0.1 mm during. (CNC) machine (Shenzhen Dima Co., Ltd., Shen-. different refining times. After reasonable design,. zhen, China). It should be noted that it is impossible. the pulp with a disc gap of 0.1 mm was sampled at. for both of them to have the same point B due to. intervals of 2 min. The process conditions of the. the geometry limitations of the curved bar, but their. experiment are shown in Fig. 5. The gap size was. difference is small in actual design. Table 1 shows. controlled by setting the zero gap by touching two. the detailed bar parameters.. plates together when the refiner is running and. The pulp was circulated in the refining system, as. then backing off the plates to the desired gap in 100. shown in Fig. 4b, at 1,460 rpm, and 10 pulp samples. unit increments (1 unit=0.025 mm).. Fig. 4. The MD3000 SD refiner (a) and the refining system (b) of the experiment. Table 1. The bar parameters of two plates. Straight bar. Curved bar. 276.55 m/rev. 327.58 m/rev. Plate Segment. BEL θ. 20°. 20°. rB. 55 mm. 43 mm. Common bar parameters. 50. Bar width. Groove width. Bar height. α. Inner radius. Outer radius. Center angle of segment. Number of bar. 2 mm. 3 mm. 4 mm. 42°. 82.5 mm. 203 mm. 40°. 117. 펄프·종이기술 51(5) 2019.
(7) Huan Liu·Jixian Dong·Xiya Guo·Xiaojun Jiang·Chong Luo·Xiaohui Tian·Ruifang Yang·Litao Zhang·Bo Wang·Yan Yan. 3. Results and Discussion 3.1 Refining characteristics of straight bar and curved bar plates The refining characteristics of the straight bar and curved bar plates with the same bar parameters were different during the same refining conditions through the theoretical analysis of the SEL and bar force. The refining effect on the pulp fibers and formed. Fig. 5. The process conditions of experiments.. paper was directly related to the refining intensity, which was affected by the net energy consumption, rotating speed, and characterization parameters of. The samples collected at different times were. the refining plate according to Eq. 1. In general, low. centrifuged and dried by an electric blast drying. intensity refining produces more fiber fibrillation,. oven 101 (Beijing Zhongxing Weiye Instrument Co.,. less cutting, and higher strength of the formed. Ltd., Beijing, China) to calculate the moisture con-. paper, while high refining intensity produces pulps. tent of the pulp for subsequent experiments.. with lower strength and more fiber cutting.25,27). 2.4 Measurement of properties of pulp fibers and paper. different, and the BEL of the curved bar plate was. It was clear that the BEL of the two plates were larger than that of the straight bar plate during. The mean fiber length, fiber width, external. refining, even if the bar parameters, such as bar. fibrillation and fines content of the pulp samples. width, groove width, bar angle, and number of. were analyzed by a FS5 (Valmet, Espoo, Finland). bars, were the same, as shown in Table 1. The SEL. fiber quality analyzer. The scanning electron. values of the straight bar and curved bar plates for. microscopy (SEM) analysis (TESCAN, Brno, Czech. the same refining conditions were calculated as. Republic) was conducted to observe the fiber mor-. shown in Fig. 6, which indicates that the refining. phology of the different samples. The Schopper Riegler (SR) Freeness wh ich provide a measure of the rate at which a dilute suspension of pulp may be dewatered were determined by a DFR-05 drainage freeness retention (BTG, Herrsching, Germany) according to GB/T 3332-2004. Handsheets for measuring the physical properties of paper were made and their physical properties including tensile and tear strength were measured based on TAPPI T220 (2001) using a tensile strength meter 062 (L&W, Kista, Sweden) and a paper tear strength meter (SLY-S1; Labthink, Jinan, China).. Fig. 6. T he SEL of different refining times conducted by the straight and curved bar plate.. J. of Korea TAPPI Vol.51 No.5 Sep.-Oct. 2019. 51.
(8) Refining Characteristics of Hardwood Pulp Using Straight- and Curved-bar Plates. intensity of the curved bar plate, 0.13 to 0.26 J/m,. obtained when the SEL of them was similar, while. was lower compared to the straight bar plate, 0.15. the bar profile of them was the same and the cut-. to 0.29 J/m. Therefore, more fibrillation and less. ting effect of the curved bar plate was weaker.. cutting can be achieved during refining with the. Compared to the results obtained by Kerekes, the. curved bar plate through the theoretical analysis,. bar force of straight bar plate calculated here is. which was strongly consistent with the conclusions. large, and more fiber will be cut, as shown in Fig. 8.. of the experiments conducted in this project and in. Through the analysis of SEL and bar force of two. 26-29). previous studies.. However, SEL of straight bar. plates, it can be concluded the bar force proposed. plate is slightly higher than that of curved bar. by Kerekes would be a better indicator of fiber. which means that their refining effect would be. cutting compared to SEL.. similar during the same refining process. The key variable for fiber shorting is force, not. 3.2 The drainage of pulp suspension. energy, as proposed by Kerekes et al.30) It would be. The SR freeness reflects the difficulty of draining. more effective to characterize the change of fiber. the pulp suspension and comprehensively charac-. and pulp properties in refining by the bar force. terizes the fiber cutting, fibrillation, and swelling.. applied by the plates compared to the SEL which. Through the analysis of process conditions, the. can be obtained by this bar force F multiplied by. initial time zero point was regarded as the time. the distance of movement during which force is. when the gap was adjusted to 0.1 mm, and samples. exerted, s. Thus F=SEL/s and the detail calculation. were continuously collected during refining.. method can seen in the study of Kerekes. As shown. Fig. 7 shows the SR freeness changes of the pulp. in Fig. 6, the bar force of two different refining. obtained from the two different plates as a func-. plate decreases with the shorting of fibers. Mean-. tion of refining time. The SR freeness of the pulp. while, the bar force of the curved bar plate is. gradually increased with time. However, the. smaller compared to the straight bar plate and a. change rate decreased with increased refining. larger difference of bar force of two plates was. time, and it finally stabilized at a certain constant. Fig. 7. The changing of pulp SR Freeness obtained from straight and curved bar plates as a function of time.. Fig. 8. T he length-weighted average fiber length L l of different samples collected with different refining time which refined by straight and curved bar plate.. 52. 펄프·종이기술 51(5) 2019.
(9) Huan Liu·Jixian Dong·Xiya Guo·Xiaojun Jiang·Chong Luo·Xiaohui Tian·Ruifang Yang·Litao Zhang·Bo Wang·Yan Yan. value. The same change trend of SR freeness. 3.3 The properties of fiber. obtained by the two plates was observed when. The fiber length and external fibrillation are two. t <14.5 min. The straight bar plate had a higher. important parameters that measure the quality of. increasing rate for the SR freeness than the curved. fiber. They reflect the cutting effect and the fibril-. bar, but the opposite trend was observed when the. lation of the refining plates on fibers and further. refining time was greater than 14.5 min. It was. affect the bonding ability among fibers.. obvious that the final stable SR freeness obtained by the curved bar plate was slightly higher than. 3.3.1 Fiber length and fines. that of the straight bar, which indicated that the. The average fiber length is one of the commonly. curved bar plate had a slightly higher increasing. used indicators for measuring the fiber length, and. ability for pulp SR freeness beyond the critical. common methods include the arithmetic average. refining time compared to the straight bar plate. fiber length Ln, the length-weighted average fiber. under the same refining conditions and the oppo-. length L l , and the weighted-weighted average. site conclusion was reached when the refining time. fiber length Lw. To analyze the cutting effect of the. was shorter than the critical refining time. It can. two different refining plates, the length-weighted. be concluded that the reason why the SR of pulp. average fiber length Ll was used. As shown in Fig.. samples refined by curved bar plate is higher when. 8, the Ll of the fibers was gradually reduced due to. t＞14.5 min maybe the longer fiber length, higher. the complex mechanical effects of the plates and. internal fibrillation and higher external fibrillation. finally stabilized to a certain fiber length through. of pulp samples refined by it through the analysis. the analysis of data obtained from the straight bar. of SR freeness, fiber average length, fines and. plate. It can be concluded that the fiber length will. external fibrillation of the pulp samples refined by. remain constant when the refining time is long. two plates, as shown in Figs. 7-10.. enough. If the pulp was treated by the refining plate for 22 min, the fiber length refined by the straight bar plate was shortened to 0.564 mm, and. Fig. 9. Fiber fines content of different samples collected with different refining time which refined by straight and curved bar plate.. Fig. 10. Fiber fibrillation of different samples collected in different refining time which refined by straight and curved bar plate.. J. of Korea TAPPI Vol.51 No.5 Sep.-Oct. 2019. 53.
(10) Refining Characteristics of Hardwood Pulp Using Straight- and Curved-bar Plates. the fiber cutting rate, which is the ratio of the. external fibril is cut. It can be concluded that the. length change and the average fiber length of raw. additional fines from refining by the straight bar. fibers, was 39.74%. However, the average fiber. plate were produced by fiber cutting not by exter-. length treated by the curved bar plate was changed. nal fibrillation because the external fibrillation was. from 0.942 mm to 0.796 mm, and the fiber cutting. almost the same in the two refining processes, as. rate was 15.50%. Therefore, the cutting ability of. shown in Fig. 10.. the curved bar plate was weaker than that of the straight bar plate, which could retain the fiber. 3.3.2 External fibrillation of fibers. length of the pulp effectively under the same. Fibrillation, which includes external fibrillation. refining process parameters. The strength of the. and internal fibrillation, is an indispensable refining. formed paper made by the pulp refined by the. effect in conventional refiners with the concomi-. curved bar plate would be better than that of the. tant occurrence of structural changes, such as. paper made with the straight bar plate.. fines and fiber cutting. The fiber strength and. The amount of fiber fines, which are particles. paper properties are sensitive to changes of fibril-. with a length of less than 0.2 mm and known as. lation, and the strength of the paper may change. flake-lake fines, is an important index of pulp or. noticeably when the fibrillation changes even to a. fibers that is influenced by the type of wood, the. small extent.1) It has been indicated that external. refining process conditions, and the refining. fibrillation can be defined as a peeling off of fibrils. equipment, and it will seriously affect the perfor-. from the fiber surface and leaving them attached. mance of fibers and formed paper. The fiber fines. to the fiber surface.31,32) In this study, external. content is usually determined by a gravimetric. fibrillation was measured to indicate the projection. analysis, and in this study, a fiber quality analyzer. area of the fibrils in relation to the projection area. was used to quantitatively analyze the fiber fines. of the entire object, scaled into a percentage. Based. of different pulp samples during refining. The per-. on previous studies, the role of external fibrillation. centage of the fiber fines of the different samples. is controversial, but there has been no doubt about. refined by the curved bar and straight bar plates is. the role of internal fibrillation, which can improve. shown in Fig. 9. The fiber fines of the pulp samples. the interfiber bonding strength. Strachan33,34). refined by the straight bar plate for 2 to 20 min. emphasized that external fibrils play an essential. was 26.53% to 46.97% and was higher than that of. role in the cohesion between fiber surfaces. Mean-. the curved bar plate, which was 20.37% to 34.13%.. while, some studies have taken microscopic images. The fines content of the unrefined fiber was. of external fibrils, which are believed to contribute. 13.23%, and the increasing rate of fiber fines con-. to the paper strength by spanning between. tent of the samples collected by the different plates. fibers.35-38) Taegeun Kang39) pointed out that pro-. over time was calculated. It can be concluded that. moting the degree of external fibrillation contrib-. the change rate of fiber fines refined by the curved. uted to strengthening the bonding layer between. bar plate, which was 1.69% per minute, was less. fibers, resulting in improved tensile strength and. than that of the straight bar plate at 1.045% per. internal bond strength; however, the opposite view. minute. Two sources of fines exist in refining, one. that external fibrillation decreases the tensile. is fiber cutting while another is the peeling of fiber. strength due to a possible loss of fiber strength. wall material, which is usually referred to as. was put forward by Tasman.40) Therefore, the. external fibrillation, and it can be fines when the. measurement of external fibrillation is very. 54. 펄프·종이기술 51(5) 2019.
(11) Huan Liu·Jixian Dong·Xiya Guo·Xiaojun Jiang·Chong Luo·Xiaohui Tian·Ruifang Yang·Litao Zhang·Bo Wang·Yan Yan. important to clarify how it effects the physical. refined by the two plates was not very large, there. properties of paper.. may have been a large influence on the paper. Fig. 10 shows the degree of external fibrillation of. properties.1) It can be concluded that the external. the different samples refined by the two refining. fibrillation increased with the refining time, while. plates and reveals that the external fibrillation of. the external fibrillation ability of the curved bar. the samples treated by the curved bar plates was. plate on the fibers was stronger, resulting in better. slightly higher than that of the samples treated by. physical properties of the fibers or formed paper.. the straight bar plate. The external fibrillation of. The external fibrillation can be displayed through. the samples treated by the straight bar plate. the fiber morphology of the pulp samples refined. changed from 1.82% to 2.42% as the refining time. by the two plates, and the combination of the two. increased, and the change rate over time was. is more effective in explaining the actual refining. 0.030%. However, the external fibrillation of the. effect. In this project, the fiber morphology of the. samples obtained by the curved bar plate was. samples refined for 14 min and 20 min was ana-. 0.036%. Although the gap of fiber fibrillation. lyzed, as shown in Figs. 11 and 12. It was not diffi-. Fig. 11. Fiber morphology (10 kx) of two samples refined by the straight (a) and curved bar plates (b) with a refining time of 14 min.. Fig. 12. Fiber morphology (×4,000) of two samples refined by the straight (a) and curved bar plates (b) with a refining time of 20 min.. J. of Korea TAPPI Vol.51 No.5 Sep.-Oct. 2019. 55.
(12) Refining Characteristics of Hardwood Pulp Using Straight- and Curved-bar Plates. cult to find that the fiber morphology of the pulp. result in more interaction area among the fibers. refined by the two plates was similar when the. and increase the paper strength. Therefore, the. refining time was 14 min, and the external fibrilla-. conclusion can be drawn that the fibers refined by. tion values of the pulp samples refined by the two. the curved bar plate had a larger bonding area. plates were the same, as shown in Fig. 10. Mean-. compared to those refined by the straight bar plate. while, more external fibrillation on the surface of. for the same refining process.. the fibers refined by the curved bar plate for a refining time of 20 min was observed through. 3.4 Physical properties of paper. analysis of SEM images of the fiber morphology,. The properties of the fibers and pulp had a. which is strongly consistent with result of Fig. 10.. noticeable impact on the performance of the. External fibrillation will affect the properties of. formed paper. The paper strength is different for. paper together with fiber length.. different types of paper applied to different occa-. The ratio of the fiber length to the width strongly. sions. Hardwood or short fiber pulp is usually. affected the amount of interaction points among. refined at a low intensity or with a small bar force. the fibers per unit area, which affected the density. to reduce the fiber cutting effect and maintain the. of the fiber distribution and paper strength.. fiber length, which could lead to a better strength. During refining, fibrillation will affect the fiber. of the fibers and the paper.. width due to internal fibrillation, external fibrilla-. The tensile index and tear index are two main. tion, and the shedding of the fiber layer. As shown. physical properties of paper, and they were. in Fig. 13, the minimum ratio of the fiber length to. obtained by analyzing handsheets made by differ-. the width for the fiber refined by the straight bar. ent pulp samples refined by the straight and curved. plate was 46.15 and was substantially lower than. bar plates. As shown in Fig. 14, the same trend. that of the curved bar plate at 63.68. The ratio of. was observed for the paper tensile index obtained. the fiber length to the width was quite different. from the different plates, which indicated that the. for the two plates, and a relatively large ratio will. tensile index of the formed paper gradually. Fig. 13. The ratio of fiber length to width of different samples with different refining times and refined by the straight and curved bar plates.. Fig. 14. The tensile index of handsheets made by different pulp samples refined by straight and curved bar plate.. 56. 펄프·종이기술 51(5) 2019.
(13) Huan Liu·Jixian Dong·Xiya Guo·Xiaojun Jiang·Chong Luo·Xiaohui Tian·Ruifang Yang·Litao Zhang·Bo Wang·Yan Yan. increased to a peak value and then decreased as. 4.42 mNm2/g, but the peak value of another plate. the refining time increased. It was found that the. was 7.78 mNm2/g.. tensile index of paper depends on the fiber strength. The pulp samples refined by the two plates shared. to some extent but mainly on the fiber bonding. almost the same SR freeness, but the physical. force and fiber length.41,42) In the early stage of. properties of the formed paper of the two plates. refining, the fibers quickly swelled and fibrillated,. were substantially different. Therefore, it can be. 1). which led to a higher fiber bonding force. That. concluded that the physical properties of paper. was why the tensile index rapidly increased in that. were not only related to the SR freeness but also. stage and reached the maximum value when the. strongly affected by the fiber average length. By. refining time was 14 min with the SR freeness of. analyzing the SEM image of the pulp samples after. bleached sulphate eucalyptus pulp (BSEP) of 70°. 14 min of refining by two refining plates, as shown. SR. In the following refining stage, the fiber bond-. in Fig. 16, it can be found that the number of long. ing force continued to increase, but the fiber average length, which was the main factor affecting the tensile index in the latter section, decreased, and thus, overrefining would lead to a decrease of the tensile index.1) It can be seen from Fig. 14 that the maximum tensile index of the formed paper obtained from the curved bar plate was 44.44 N·m/ g, which was higher than that of the straight bar plate at 36.63 N·m/g. As shown in Fig. 15, the tear index of the formed papers obtained by the two plates was quite different, and the change trend was almost consistent with that of the tensile index, which shared the same turning point. Furthermore, the maximum tear index of the formed paper obtained from the straight bar plate was. Fig. 15. The tear index of handsheets made by different pulp samples refined by straight and curved bar plate.. Fig. 16. Fiber morphology (×800) of two samples refined by straight (a) and curved bar plate (b) with a refining time of 14 min.. J. of Korea TAPPI Vol.51 No.5 Sep.-Oct. 2019. 57.
(14) Refining Characteristics of Hardwood Pulp Using Straight- and Curved-bar Plates. fibers in the sample refined by the curved bar plate. (4) The formed paper made from pulp samples. was greater than that of the straight bar plate, and. refined by the curved bar plate had good physical. the bonding of fibers was similar. Meanwhile, the. properties, such as the tensile index and tear. curved bar plate effectively reduced the generation. index, due to the low cutting effect on the fibers. of fines, retained the fiber length, and ensured a. under the same refining conditions with the. sufficient bonding force between the different. straight bar plate.. fibers, and their synergistic effect led to better paper properties.. Acknowledgement 4. Conclusions. The authors gratefully acknowledge the funding by the National Natural Science Foundation (Grant. A low consistency refiner equipped with straight. No. 50745048), Shaanxi Provincial Technology. bar and curved bar plates that shared the same bar. Innovation Guidance Project (Fund) (Grant No.. parameters showed quite different refining char-. 2018HJCG-10) and Research Project of Shaanxi. acteristics under the same refining conditions, and. Provincial Department of Education (Grant No.. there were large differences of the refining effects. 19JK0374). The authors give a special thanks to. on the fibers, pulp, and formed paper.. Henan Cigarette Industry Sheet Co., Ltd. and. (1) The characteristic parameter BEL of the. Nantong Huayan Casting Co., Ltd. (especially Yan. straight bar plates was lower than that of the. Ying, Tian Yangyuan) for the manufacturing the. curved bar plates with the same bar parameters.. experimental refining plates and the guidance of. Therefore, the refining intensity of the process. experiments.. with the curved bar plate was relatively lower compared to the refining intensity with the straight bar plate under the same refining conditions, and. Literature Cited. the calculated bar force shared the same change trend as the refining intensity. (2) The overall change trends of the pulp SR freeness refined by the two plates were almost the. 1. He, B., Refining, In Papermaking Principle and Engineering, He, B. (ed.), China Light Industry Press, Beijing, China, pp. 32-34 (2010).. same, but the curved bar plate had a slightly. 2. Lönnberg, B. (ed.), Mechanical Pulping,. higher increasing capacity for the SR freeness of. Paperi ja Puu Oy, Helsinki, Finland, pp. 138-. BSEP than the straight bar plate.. 142 (2009).. (3) The refining characteristics of the two plates. 3. Ito, K., Takeshita, Y., and Antensteiner, P.,. on pulp and fiber were different. It was concluded. Low consistency refining technology: LemaxX. that the curved bar plate led to weak fiber cutting,. spiral-nature applied, Journal of the Japanese. a reduction in the fines generation, an increase of. Technical Association of the Pulp and Paper. the ratio of fiber length to width, and a promotion. Industry 60(5):718-723 (2006).. of fiber external fibrillation, which is consistent. 4. Mikko, P., Rethinking the art of refining:. with the SEL and bar force prediction results. All. Improving the efficiency and quality of refin-. of these synergistically promote the fiber bonding. ing, International Mechanical Pulping Confer-. area and result in better paper properties.. ence, Beijing, China, pp. 227-224 (2015).. 58. 펄프·종이기술 51(5) 2019.
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(16) Refining Characteristics of Hardwood Pulp Using Straight- and Curved-bar Plates. ties, Paperi Ja Puu [Paper and Timber] 73(1):. electronmicrographs. Das Papier 11:140-145. 62-69 (1991).. (1957).. 27. Muhić, D., Huhtanen, J. P., Sundström, L.,. 36. Jayme, G. and Hunger, G., Electron micro-. Sandberg, C., Ullmar, M., Petteri, V., and. scope 2- and 3-dimensional classification of. Engstrand, P., Energy efficiency in double disc. fibre bonding, Formation and Structure of. refining - Influence of intensity by segment. Paper, Transactions of the 2nd Fundamental. design, 7th International Seminar on Funda-. Research Symposium, Vol. 1, Oxford, U.K.,. mental Mechanical Pulp Research, Nanjing, China, pp. 109-117 (2010).. pp. 135-170 (1962). 37. Page, D. H. and Sargent J. W., The fine. 28. Stationwala, M. I., Miles, K. B., and Karnis,. structure of fibre bonding, Formation and. A., The effect of first stage refining conditions. Structure of Paper, Transactions of the 2nd. on pulp properties and energy consumption,. Fundamental Research Symposium, Oxford,. 1991 International Mechanical Pulping Confer-. U.K., pp. 195-200 (1961).. ence, Minneapolis, USA, pp. 321-327 (1991).. 38. Buchanan, J. G. and Lindsay, R. A., A note on. 29. Li, B., Li, H., Zha, Q., Bandekar, R., Alsaggaf,. structure of paper as revealed by the scanning. A., and Ni, Y., Review: Effects of wood quality. electron microscope, Formation and Structure. and refining process on TMP pulp and paper. of Paper, Transactions of the 2nd Fundamental. quality, BioResources 6(3):3569-3584 (2011).. Research Symposium, Oxford, U.K., pp. 101-108. 30. Kerekes, R. J. and Meltzer, F., The influence. (1961).. of bar width on bar forces and fibre shortening. 39. Kang, T., Role of external fibrillation in pulp. in low consistency pulp refining, Nord. Pulp. and paper properties, Doctoral Thesis, Helsinki. Pap. Res. J. 33(2):220-225 (2018).. Univeristy of Technology, Helsinki, Finland. 31. Ebeling, K., A critical review of current theo-. (2007).. ries for the refining of chemical pulps, Inter-. 40. Tasman, J. E., Pulp and Paper Manufacture. national Symposium of Fundamental Concepts. Vol. II: Control, Secondary Fiber, Structural. of Refining: Institute of Paper Chemistry,. Board, Coating, Joint Textbook Committee of. Appleton, USA, pp. 1-36 (1980).. the Paper Industry and Macdonal, R. G. (eds.). 32. Page, D. H., Beating of chemical pulps – The action and the effects, Papermaking Raw. McGraw-Hill Book Company, New York, USA, pp. 132-186 (1969).. Materials, Transactions of the 9th Fundamental. 41. Seth, R. S., Fibre quality factors in paper-. Research Symposium, Cambridge, U.K., pp.. making - I The importance of fibre length and. 1-37 (1989).. strength, Proceedings Material Research Sym-. 33. Strachan, J., Further notes on the hydration. posium, Caulfield, D. F., Passaretti, D., and. of cellulose in papermaking, Proceedings of the. Sobczynski S. F. (eds.), Vol. 197, pp. 125-142. Technical Section, London, U.K., pp. 61-81 (1932).. (1990).. 34. Strachan, J., Some physical aspects of beat-. 42. Paavilainen, L. Importance of cross-dimen-. ing. Proceedings of the Technical Section,. sional fibre properties and coarseness for the. Manchester, U.K., pp. 171-194 (1938).. characterisation of softwood sulphate pulp,. 35. Jayme, G. and Hunger, G., The fiber-to-fiber bonding in paper handsheets seen by means of. 60. 펄프·종이기술 51(5) 2019. Paperi ja Puu [Paper and Timber] 75(5):343351 (1993)..
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기업 차원에서도 원자재 가격 급등에 대한 자구 노력을 지속해야 한다 기업 차원에서도 원자재 가격 급등에 대한 자구 노력을 지속해야 한다 기업 차원에서도 원자재
If both these adjustments are considered, the resulting approach is called a bootstrap-BC a -method (bias- corrected-accelerated). A description of this approach
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③ A student who attended Korean course at KNU Korean Language Program and holds TOPIK Level 3 or a student who completed Korean course Level 4 at the KNU Korean Language
Five days later, on 15 January 1975, the Portuguese government signed an agreement with the MPLA, FNLA and UNITA providing for Angola to receive its independence on 11
