Wood Pellet Mill Precautions For Daily Operation, Maintenance And Use (2) - page 1

Wood Pellet Mill Precautions For Daily Operation, Maintenance And Use (2)

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7. Coordination of die , roller and feeding scraper
(1) The principle of adjusting the gap between the die and the roller: to get close furthest but not to contact and abrade with each other. On the premise that the roller and the die do not abrade with each other, the extrusion force of granulation shall be maximized as far as possible. The best gap: wood material 0.3-0.5mm (animal feed: 0.1-0.3mm).
① The new die will have slight deformation due to the heat treatment, and we control the deformation of unilateral within 0.25mm at delivery. Likewise, the new roller will have slight deformation, too. Firstly, we fill the two roller assemblies with lubrication oil, so it will operate not so sensitively; then, we gradually turn down their gap according to the arrow direction of the adjustable gap wheel, and when the operator rotates the die by hand, the compression roller operates in only 5% to 10% of the time. The gap of that time is 0.3-0.5mm, which is relatively ideal (as shown in Fig. P025). In this way, not only the discharging of granulation is normal, but also their lifetime will be maximized. They hardly contact and abrade, but let the materials abrade the die hole. The bank between the die holes becomes knife mouth and the abrasion of the die holes is very uniform and beautiful (as shown in Fig. P026).


② If the operator wrongly tightens the roller and presses it on working area of the inner wall of the die, the horn mouth of the die hole will be severely crushed, resulting in the severe reduction of the production, the severe abrasion between the die and the roller, and the great shortening of lifetime (as shown in Fig. P049/P050/P051). This is the wrong operation way, and do not do in this way. If the horn of the die hole is crushed, the horn shall be expanded out again by the drilling machine and repaired (as shown in Fig.P025).
(2) The principle of the cooperative application of the die and the roller: their working faces shall be identical as far as possible and shall be abraded uniformly, making the gaps (0.3-0.5mm) of the nearest areas are almost the same (as shown in Fig. P027/P028/P029/P030). The lifetime will be maximized and this is a very good phenomenon.
① A new die usually matched two pairs of new roller assembly for equal lifetime use. The one die and
two pairs of roller assembly of each group will be marked and used in groups, and the two pairs of the roller assembly are used and maintained in turns every week. The compression roller assembly in the left (right) is always used in the left (right), and the left and the right locations can not be paired and exchanged arbitrarily for the use.
② When the roller has been used for a period, the operator has to grind off the ledges of both sides to make the surface of the roller flat and in accordance with the die working surface (as shown in Fig. P031).


③ When the die starts to be used, before the starting, the working area of the inner wall of the die shall be located and the clogged hole shall be cleaned up to guarantee a 100% discharging of the hole.
If the operator finds that some die holes have been clogged (as shown in Fig. P032), he shall clean up all the clogged holes at once and make every hole produce granules. Otherwise, the hole that does not granulate will protrude and scratch the surface of the roller to form a groove and further cause the difficult discharging and production reduction of the die holes of this round. The working area of the inner wall of the die will also be uneven (Fig. P034) and the lifetime will be shortened greatly, which is not a good phenomenon. In a word, the operator shall try his best to make every hole produce granule.
(3) The main function of the feeding scraper: to make the materials be distributed on the working area of the inner wall of the circular mould uniformly, make the amounts of the feeding materials of two rollers uniform at the same time, and maximize the production of the pellet mill.
① The large feeding scraper must be installed on the outside of the upper of the pressing plate of the main shaft (Fig. P037) to feed all the rest materials to the working area of the right roller, and the small scraper is installed on the bottom of the outside of the bottom of the pressing plate of the main shaft (as shown in Fig. P036) to feed part of the materials to the inner working area of the left roller; and the rotation force of the die cover will throw a part of materials into the middle and outer working area of the left roller. In addition, the root of the head support of the main shaft is installed with two small feeding back scrapers (No.501-0329) which are mainly used to scrape the materials accumulating on the inner empty shaft flange back to the suppressing working area of the die.


② The operator shall appropriately adjust the length, width and angle of the feeding scraper according to the attrition rate of the working surface of the die and the roller to guarantee that the die eats materials uniformly and the roller abrades uniformly. If the operator finds that the rows of the holes outside the die and near the feeding scraper are abraded slowly (Fig.P035), it means the feeding materials of these rows of holes are fewer, and the feeding scraper shall be adjusted to make the gap between these rows and it a little bigger and make these rows fed more materials (Fig.P036). If the operator finds that the rows of holes inside the circular mould are abraded slowly and discharge less, he shall lengthen the feeding scraper (Fig.P037) to make more materials be feed into the interior. In a word, the operator shall try his best to make the working surface of the die flat and abraded uniformly (Fig.P038).
③ To the small and medium-sized shavings sawdust and light materials that have poor fluidity and have not been shattered, the guide function of the feeding scraper will be weakened significantly. We shall add forced feeders. The light crude materials are thrown into the granulation working area, and at the same time, the upside feeding area of the left and right compression rollers is installed with single-end feeding scraper, and by adjusting the size and structure of the feeding scraper, the auxiliary forced feeders feed the materials to the granulation working area as uniform as possible (Fig.P039). If the die of the pellet mill is large, the upper and lower feeding areas are respectively installed with a forced feeder to feed materials directly.
④ Sometimes, the location of the main shaft can be adjusted to facilitate the entering of the materials into the granulation working area.
8. Correct cooperation of die and flange (No.521-01S5)
① The flange is used to reinforce the die and avoid the deformation and cracking of the die during the course of production. The operator shall make the contact cant of the mounting flange and the die contact uniformly along the circumference of a circle, make sure that there is a gap of 1-3mm between the end face of the die cant and the bottom face of the flange and the gap is uniform in size along the circumference of a circle (Fig.P040 and P041); in this way, the reinforced flange can indeed lock the circular mould tightly and come into play to protect the die. If the operator finds that the fixed screws of the flange become easy to fracture, it means that abrasion of the cant of the flange is greater than that of the die, there is no gap (0mm) between the their end face and bottom face which have clung to each other closely, and the old flange shall be replaced with the new one at once.
② With the flange cracking, the protective effect of the damaged flange has been reduced greatly, so please replace it with the new one. The nonuniform contact of the flange and the die (Fig.P043) is expressed in the inconformity of the gap size along the circumference of a circle. This is the wrong installation way, and the flange shall be installed correctly at once.


③ The correct installation way (Fig.P044 and P045) of the driving key of the die (No.501-0512). The operator stands before the driving wheel, and the hypotenuse of the driving key is on the left (Fig.P045) and the straight flange shall be on the right (Fig.P044).
9. Correct installation way of the coupling assembly (No.505-21SA/210A)
Copper pad wafer of 0.3-1mm can be used to put at the motor foot pedestal or the foot at the bottom of the gear case to adjust the shaft of the motor and the gear shaft of the gear case to the same horizontal line; the top and the two sides of the right and left half couplings shall be measured by leveling instrument to make sure that the right and left half couplings are at the same horizontal line, so that the shaft of the motor and the gear shaft of the gear case are at the same horizontal line (Fig.P046, P047 and P048).


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