QB/T 1463-1992 Pulp laboratory pulping PFI grinding method

This standard specifies the method of laboratory pulping using the PFI mill. In principle, this standard is applicable to all types of pulp, but in actual use, the effect may not be good for some pulps with particularly long fibers, such as cotton linter pulp. QB/T 1463-1992 Pulp Laboratory PFI Mill Method QB/T1463-1992 Standard download decompression password: www.bzxz.net

Light Industry Standard of the People's Republic of China
PFI Mill Method for Laboratory Pulp Beating
This standard is equivalent to ISO5264/2--1979 "Pulp Laboratory Pulping-1 Subject Content and Scope of Application
This standard specifies the method of laboratory pulping using PFI mill. QB/T 1463-1992
Part 2: PFI Mill Method".
In principle, this standard is applicable to all kinds of pulp, but in actual use, the effect may not be good for some pulps with particularly long fibers, such as cotton linter pulp.
2 Reference standards
GB/T741 Determination of moisture content in pulp analysis samples GB/T5399 Rapid method for determination of pulp concentration QB/T1462 Wet dissociation in pulp laboratory
3 Principle
Measured pulp with a specified concentration is placed between a knife roller and a smooth beating cylinder. The knife roller and the beating cylinder rotate in the same direction but at different circumferential speeds. This acts on the pulp to achieve the purpose of beating. 4 Instruments and water quality
4.1 Commonly used laboratory instruments.
4.2 PFI mill: See Appendix A.
4.3 Standard dissociator: See Appendix A of QB/T1462. 4.4 Balance: Sensitivity 0.1g.
4.5 Distilled water, deionized water or water of similar quality. 5 Preparation of samples
If the sample is wet pulp or air-dried pulp, measure its moisture content according to GB/T741. If the sample is liquid pulp, measure its absolute content according to GB/T5399.
Take a sample equivalent to (30±0.5)g of absolute dry pulp. Be careful not to cut the sample and avoid using the cut edge. If the sample is a pulp board or a quick-dried pulp block, soak it in 0.5L water at room temperature for more than 4h, and tear the soaked pulp into small pieces of about 25mm×25mm. Wet pulp does not need to be soaked.
6 Steps
6.1 Dissociation
Move the wet pulp and the water used for soaking into the wet pulp dissociator (4.3), add water at (20±5)℃ [(25±5)℃ may be used if necessary according to climatic conditions, but it should be noted in the test report] until the total amount is (2000±25)mL, and the pulp concentration is about 1.5% (m/m, the same below). Adjust the revolution counter to zero, start the motor and let the dissociator run for a few seconds, turn off the motor, and start the motor again before the impeller stops running. During dissociation, the revolutions of pulp with a raw pulp dryness of more than 20% are 30,000 revolutions, and the revolutions of pulp with a raw pulp dryness of less than 20% are 10,000 revolutions. To ensure complete dissociation of the pulp, for pulps that are difficult to dissociate, such as unbleached kraft pulp, the dissociation revolutions can exceed 30,000 revolutions. 6.2 Concentration
After pulp dissociation, dehydrate in a Buchner funnel to a concentration of about 20%. To avoid fiber loss, the filtrate should be re-filtered through the fiber layer, and if necessary, it can be filtered several times. The concentrated pulp is diluted to a total weight of (300 ± 5) g, which is equivalent to a pulp concentration of 10%. 6.3 Beating
6.3.1 Beating conditions
Beating pressure: (3.33 ± 0.1) N/mm blade length. (Assuming that only one blade or tooth is in contact with the pulp cylinder at the same time) For pulps that are easy to beat (such as sulfite hardwood pulp and straw pulp), a small load can be applied to make the beating pressure only 1.77 N/mm blade length, and it should be noted in the test report.
Rated number of revolutions of the beating knife roller is (24.3 ± 0.5) s-1. The difference between the linear speed of the blade roll and the pulp cylinder is (6.0 ± 0.2) m/s. 6.3.2 Pulping operation
Check whether the pulping conditions are correct, so that the pulping elements of the PFI mill and the pulp suspension are at (20 ± 5) ℃. Move the pulp suspension prepared according to 6.2 into the pulp cylinder, and distribute it as evenly as possible on the entire cylinder wall, ensuring that no pulp remains in the area corresponding to the bottom of the pulping cylinder and the cross-section of the blade roller. Put the blade roller into the pulping cylinder and cover it accurately. Start the pulp cylinder to throw the pulp onto the wall of the pulping cylinder, and then start the blade roller. When these two parts reach full speed rotation, apply the pulping pressure, that is, pressurize at a constant speed for 4 seconds. When the predetermined pressure is fully applied, immediately release the horizontal arm of the revolution counter to start the counter. When the number of revolutions of the blade roller reaches the requirement, stop pressurizing and end the pulping. Turn off the motor, and open the cover to remove the blade roller after the blade roller and pulp cylinder stop. Transfer the pulp to a measuring cylinder with a capacity of not less than 2L, rinse the cylinder wall with water, add washing water to the measuring cylinder, dilute to a pulp volume of (2000 ± 25) mL, and then fully dissociate the pulp suspension in a standard push dissociator at an impeller speed of 10,000 revolutions. 6.3.3 If required, the water filterability test should be carried out as soon as possible. 6.3.4 After beating, wash the mill thoroughly with water. If necessary, it can be cleaned with resin solvent after water washing. 7 Test report
The test report should include the following:
The number of this standard;
All necessary items for comprehensive identification of the sample; the number of revolutions used for the initial dissociation of the pulp;
The number of revolutions or time used for beating;
If the water filterability is measured, report the test results; any other abnormal phenomena found in the experiment. 592
QB/T 1463—1992
Appendix A
PFI mill
(reference)
The PFI mill consists of a beating knife roller, a beating cylinder with a cover and a pressurizing device for applying beating pressure. The knife roller and the beating cylinder rotate on a vertical axis. There are 33 blades on the knife roller, each of which is 50mm long and 5mm wide. All blades are arranged radially and parallel to the knife roller axis. The diameter of the knife roller is 200mm (including the blades), and the depth of the groove between the blades is 30mm. The knife roller is driven by a 1kW motor and runs clockwise. The rated speed when no pressure is applied is (24.3±0.5)s-1, and the speed of the knife roller is displayed by a tachometer. The inner diameter of the beating cylinder is 250mm and it is driven by a 400W motor. When determining the rotation speed of the beating cylinder, the predetermined circumferential speed difference of the beating element should be (6.0 ± 0.2) m/s at zero load, and the rated speed of the knife roller is (24.3 ± 0.5) s-1. The knife roller and the beating cylinder are both driven by belts.
The beating pressure is applied by levers, which press the knife roller against the wall of the beating cylinder. In addition, the grinding wheel is equipped with a distance adjustment screw to adjust the distance between the knife roller and the beating cylinder during feeding and adjustment. The beating element is made of stainless steel or bronze. In order to ensure the repeatability of the beating results, the following conditions must be met: a. The knife roller and the beating cylinder must run at the correct speed; b. The belt cannot slip. When applying pressure, the rated speed of the knife roller should generally be reduced by (0.3~~0.6)s-1, while the speed of the pulp cylinder should be slightly increased;
All parts should move smoothly so that all the applied pressure is transmitted as pulping pressure; c.
The pitch screw should be loosened during the pulping process; d.
The knife roller and the pulping cylinder should be clean and free of sediment. The resin sediment should be removed with a non-corrosive solvent; The working condition of the PFI mill should be checked frequently by pulping with standard pulp. A certain amount of standard pulp should be stored. In order to avoid further changes in the pulp, the standard pulp should be stored for a long enough time. It is best that the standard pulp is the same as the pulp type that is often pulped in this equipment. The water filter value of the standard pulp when it is beaten to about 50°SR or 200CSF should not differ by more than ±5% from the standard water filter value specified at the same speed. Appendix BwwW.bzxz.Net
Maintenance of the PFI mill
(reference)
Under normal conditions, the beating efficiency of the PFI mill must remain unchanged. If the beating surface has been damaged, the test results will be incorrect when beating the standard pulp. The PFI mill should be ground and adjusted according to the following conditions. B1 Reverse the motor of the beating cylinder.
Adjust the distance adjustment screw so that the distance between the beating elements is 0.5 mm. B2
B3 Fill the beating cylinder with 15 g of corundum powder, which should pass through a 90 μm sieve, prepared as a suspension with 50 mL of soluble cutting oil and diluted with 50 mL of water.
B4 Start the beating cylinder so that the corundum powder is thrown onto the wall of the pulp cylinder, make sure that the cover is in place on the bracket and insert the knife roller into the beating cylinder. Stop the rotation of the beating cylinder and press the cover into its position. Start the two beating elements and apply pressure. Carefully reduce the gap between the two elements with the help of the adjusting screw until a grinding sound can be heard. Let the mill run until the sound is significantly reduced. Then reduce the gap further, but each time not more than half a division equivalent (about 0.03mm). Continue grinding in this way until the damage is repaired. B5 Wash the beating element and cover with detergent and water, making sure that no corundum powder remains. B6 After rough grinding, fine grind with corundum powder that passes through a 45μm sieve as described in B3 and B4. Clean as described in B5.
B8 File off the burrs on the blade edge.
Clean the force roller thoroughly to remove the filings.
QB/T1463-1992
B10 Reverse the beating cylinder motor. If the surface of the pulp is still too rough after grinding with corundum powder that passes through a 45μm sieve, beat the pulp mixed with about 15g of corundum powder that passes through a 45um sieve to polish it to the required level. The distance between the knife roller and the beating cylinder should be slightly greater than the thickness of the fiber layer (for example: when grinding mixed bleached coniferous sulfite pulp, a distance of 2mm is more appropriate).
B11 Clean the knife roller and the beating cylinder thoroughly.
B12 Loosen the pitch screw.
To stabilize the beating surface, it is recommended to perform a series of beating operations so that the beating time is between 50,000 and 100,000 revolutions of the knife roller.
Additional remarks:
This standard was proposed by the Paper Industry Department of the Ministry of Light Industry. This standard is under the jurisdiction of the National Paper Standardization Center. This standard was drafted by the Shanghai Paper Research Institute. The main drafter of this standard is Sun Xiuyi.
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