Short answer questions about papermaking basics

　　1. The purpose of beating?

　　Answer: According to the quality requirements of the paper or cardboard and the types and characteristics of the pulp used, physical methods are used to improve the shape and properties of the fiber under controlled conditions, so that the manufactured paper or cardboard meets the expected quality requirements.

　　2. The main task of beating?

　　Answer: (1) Use physical methods to mechanically treat the fiber suspension in the water to subject the fiber to shearing force, change the shape of the fiber, and make the pulp obtain certain characteristics (such as mechanical strength and physical properties) to ensure that it is copied The products achieve the expected quality requirements. (2) Through grinding and beating, the water filtering performance of the paper material on the net is controlled to meet the needs of paper machine production, so that the paper web can be formed well, and the uniformity and strength of the paper sheet can be improved.

　　3. What changes have taken place in the fiber beating process?

　　Answer: (1) Displacement and deformation of the cell wall. (2) The rupture of the outer layer of the primary wall and the secondary wall. (3) Water swelling. (4) Thin fibrillation. (5) Cut horizontally.

　　4. What are the factors that affect beating?

　　Answer: (1) Beating specific pressure. (2) Beating concentration. (3) Beating temperature. (4) Throughput.

　　5. What are the advantages of neutral sizing?

　　Answer: (1) It can reduce the corrosion of the equipment and extend the service life of the equipment. (2) It can improve the strength of the paper, prevent aging, and extend the use and storage time of the paper. (3) Calcium carbonate with high whiteness and good opacity can be used as filler to improve the softness, bulk and printing adaptability of the paper. (4) The white water has high pH and no sulfate radical accumulation, which can increase the white water reuse rate, easily realize the closed white water cycle, and reduce pollution.

　　6. What are the factors that affect sizing?

　　Answer: (1) The types and properties of the slurry (2) The tapping degree of the slurry (3) The washing of the slurry (4) Water for sizing (5) The pH value of the slurry (6) Ambient temperature, etc.

　　7. Flow aid and filter aid effect?

　　Answer: (1) Improve the retention of fillers and fine fibers, reduce loss, improve white water circulation, and reduce pollution. (2) Improve both sides of the paper and improve the printing performance of the paper. (3) Improve the dehydration capacity of the wire section, thereby increasing the speed of the paper machine.

　　8. What are the factors affecting dyeing?

　　Answer: (1) Variety of raw materials (2) Pulp beating degree (3) Pulp PH value (4) Sizing (5) Temperature (6) Dye dilution water (7) Filler (8) Production conditions of paper machine .

　　9. What are the reasons why the slurry pump is not sizing?

　　Answer: (1) Sundries are mixed into the slurry and block the slurry pump.

　　(2) Air is mixed into the slurry pump or slurry.

　　(3) The slurry concentration at the bottom of the slurry tank is high, and the slurry inlet resistance is large.

　　(4) The slurry inlet pipe has a small diameter, many elbows, and a long distance, resulting in large slurry inlet resistance.

　　(5) There is slurry in the pipeline, which blocks the pipeline.

　　(6) The liquid level in the slurry tank is low, and the slurry entrains air into the slurry pump.

　　(7) After the newly installed slurry pump or the slurry pump motor is overhauled, the motor wiring is wrong, and the pump reverses and does not sizing.

　　10. What are the factors that affect the purification efficiency of the desander?

　　Answer: (1) inlet and outlet pressure difference (2) slurry concentration (3) properties of slurry (4) relative density and thickness of impurities to be removed (5) diameter of degreasing nozzle (6) smoothness of the inner wall of degreasing device degree

　　11. The role of paper degassing?

　　Answer: (1) Avoid foaming in the headbox of the paper machine, and spray the non-foamed paper material to the forming part, so as to improve the forming of the paper sheet, and solve the foam spots and pinholes in the paper sheet. (2) Since there are no bubbles and fibers combined, the flocculation of the paper material in the headbox is easily dispersed, which helps to improve the uniformity of the paper. (3) The amplitude of the pulsation of the pipeline system is lower, which makes the basis weight of the paper more stable. (4) Speed ??up the dehydration of the forming part and increase the dehydration capacity of the forming part.

　　12. What is the role of the paper online system?

　　Answer: In accordance with the speed of the paper machine and the quality requirements of the product, the large paper stream sent by the paper material flow system is processed by the online system, and is uniformly and stably sent to the Internet along the full width of the paper machine banner.

　　13. What is the main function of the headbox?

　　Answer: (1) Distribute the paper evenly and stably along the full width of the paper machine to ensure the controllability and uniformity of uniform pressure, uniform flow, uniform density, and fiber orientation. And send the net jet paper stream to the most suitable position of the forming part at the most appropriate angle. (2) Disperse fibers effectively and prevent flocculation. The fibers, fiber fragments and non-fiber fillers are evenly distributed in the net paper stream. (3) According to the process requirements, provide and maintain a stable relationship between the pressure head of the on-line paper flow and the speed of the pulp net, and it is easy to control and adjust.

　　14. What are the tasks and requirements of the forming section (net section)?

　　Answer: The main task of the net department is to keep the paper on the net as much as possible, remove more water and form a uniform wet paper web. It is required that the paper material should be evenly dispersed on the net, so that the basis weight, thickness, and uniformity of the whole paper page should be uniform, so as to lay a solid foundation for forming a good quality wet paper.

　　15. What is the function of the lead roller between the flat roller and the first press?

　　Answer: One is to ensure that the wet paper sheet runs in accordance with the optimal curve to reduce tension. The second is to control the wet paper web so that it does not produce large jitter between the flat roller and the first press. The third is to guide the wet paper to achieve a large peel angle, and at the same time, make the self-balancing mechanism more effective.

　　16. The main function of the press section of the paper machine?

　　Answer: (1) Use mechanical pressure to remove as much moisture from the wet paper web as possible. (2) Reduce steam consumption in the drying section. (3) Increase the binding force of fibers in the paper web and improve the tightness and strength of the paper. (4) Transfer the wet paper web from the wire section to the dryer section for drying. (5) Eliminate the net marks on the paper web, improve the smoothness of the paper and reduce the double-sidedness of the paper.

　　17. Advantages of vacuum pressing?

　　Answer: (1) High dehydration efficiency. The dryness of the paper web can be increased by 1%-2% compared with the ordinary press. (2) The dryness of the paper is more uniform. (3) Less broken ends during pressing. (4) Vacuum pressing has a cleaning effect on the blankets and can extend the service life of the blankets.

　　18. What is the role of pressing blankets?

　　Answer: (1) Pass wet paper. (2) Absorb the water squeezed out of the wet paper to help dehydration. (3) Distribute the pressure evenly on the wet paper. (4) Support wet paper to prevent embossing. (5) Change the surface properties of the paper web. (6) In the vacuum pressure roller, groove pressure roller and blind hole pressure roller, it can balance the pressure on the solid part and the eye hole part, thereby eliminating or reducing the shadow marks on the paper. (7) Drive the driven roller of the press section to rotate.

　　19. The advantages of double blanket press?

　　Answer: (1) There is a wider nip to increase dehydration efficiency. (2) Because the nip is wider and the pressure is lower, it can reduce the risk of wet paper being crushed and improve the bulk of paper and cardboard. (3) Reduce the two sides of the paper. (4) Increase the dewatering capacity of the press, and improve the dryness of the pressed paper At the same time, the wet paper breaks are reduced, the running performance of the paper machine is improved, and the production capacity of the paper machine is increased. (5) The dryness of the pressed paper is higher, and the amount of steam consumed by the dryer section is correspondingly reduced. (6) It is especially suitable for high-quantity cardboard made from high-beaten pulp. (7) Increase the press line pressure to reduce the risk of wet paper crushing.

　　20. The role of the dryer blanket?

　　Answer: The first is to pass the paper through the dryer section. The second is to drive the blanket dryer and the blanket roll, cloth adjustment roll, and tight cloth roll in the dryer section to rotate. The third is to press the paper on the drying cylinder to enhance the contact between the paper and the cylinder surface and improve the heat transfer efficiency. In addition, the dry blanket can also absorb the water vapor evaporated when the wet paper is dried and the moisture on the surface of the wet paper, increase the evaporation area and improve the drying efficiency. At the same time, the dry blanket can also prevent the paper from wrinkling and wrinkles during drying.

　　twenty one. The purpose of the surface treatment of the paper?

　　Answer: (1) Improve the surface properties of paper and cardboard. (2) Improve the void structure and absorption performance of the paper. (3) Improve the liquid increasing performance of paper and cardboard. (4) Improve the physical strength of paper and cardboard. (5) Improve the printing performance of paper and cardboard (6) Reduce the two-sided difference and deformability of the paper. (7) Smaller investment to achieve higher benefits

　　22. The influence of pulp-to-net speed ratio on forming quality:

　　Answer: (1) When R=1, that is, when the pulp speed is equal to the wire speed, the relative speed between the pulp speed and the wire speed is 0, and the turbulence intensity of the pulp flow is small, which makes the dispersed fibers re-flocculate and cause the paper Cloud flowers are easy to form, and the formation uniformity is poor. (2) When R>1, that is, when the pulp speed is greater than the net speed, the fibers are arranged horizontally on the net. When the net pulp is relatively free and the water filtration speed on the net is faster, it is easy to cause the fiber to curl or the fiber is perpendicular to the net surface. The phenomenon of alignment causes the paper to appear wavy. (3) When R<1, that is, the pulp speed is less than the wire speed, the paper material is accelerated by the net after going online, which reduces the phenomenon of fiber re-flocculation, and the formed paper industry has a better uniformity.

　　23. What are the effects of calendering on paper performance?

　　Answer: (1) The tightness is increased, the thickness is reduced and more uniform, and the adaptability of the paper is good.

　　(2) The air permeability of the paper decreases, the transparency increases, and the whiteness decreases.

　　(3) The net marks of the paper are reduced, the gloss and smoothness are improved, and the two-sided difference is reduced.

　　(4) The sizing degree of the paper decreases.

　　(5) Due to compression and deformation, the fiber bond in the paper is destroyed, so various physical indicators are reduced to varying degrees

　　24. What are the factors that affect the calendering effect?

　　Answer: (1) Number of passes through the nip (2) Calender line pressure (3) Vehicle speed (4) Moisture (5) Nip temperature (6) Calender type (7) Paper properties