JPS6347490B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dewatering device in a paper machine or a waste treatment plant.

For example, in a paper machine, after pulp is made into fibers, it is pressed with press rolls to form a sheet and dehydrated, and then the dehydrated sheet is sent to a drying process. However, if the amount of moisture in the pressurized and dehydrated sheet is large, the dryer energy consumed in the drying process will increase proportionally, and the time required for drying will also become longer.

For this reason, conventionally, as shown in FIG.
The water in the sheet f is transferred to the felt d to dehydrate it, and the felt that has absorbed the water is forcedly dried using heated air or the like and is circulated for use.

However, since this uses a small-diameter pressure roll g, the nip width is narrow and a relatively high pressure can be obtained, but at the same time, the time required for the wet paper to pass through the nip is shortened.
Moisture pushed out from the wet paper by pressure transfers to felt d, but when the pressure is released, the moisture soaks into the dehydrated sheet f again before it soaks into felt d (this is called rewetting). ) Sufficient dehydration effect cannot be obtained.

In order to improve this drawback, as shown in Fig. 2, a fixed shoe b is pressurized by a hydraulic piston a to a top roll e uniformly in the width direction via a moving belt c and a felt d, and the water in the sheet f is removed. The water is dehydrated by transferring it to felt d.

According to this, since the width of the fixed shoe b can be made wider, the nip width can also be made wider, the time taken for the wet paper to pass through the nip becomes longer, and effective dewatering can be carried out.

However, in order to alleviate the frictional resistance caused by direct contact between the fixed shoe b and the moving belt c, shoe lubrication oil is supplied to the fixed shoe b to generate an oil film between the fixed shoe b and the moving belt c. Direct contact with other people should be avoided. Therefore,
A lubrication device (g) is required, making the dehydration device as a whole expensive. Further, since the width of the fixed shoe b is wide, a very large pressing force is required to increase the surface pressure, and therefore, in practice, sufficient surface pressure is not always obtained.

The present invention was made for the purpose of eliminating the drawbacks of the conventional dewatering apparatus described above, and involves intervening two small-diameter rolls between a pair of main rolls to dewater a sheet sandwiched between upper and lower felts. Furthermore, the present invention relates to a dewatering device that can obtain a high actual line pressure by suctioning the moisture in the upper and lower felts toward the side opposite to the sheet, improve dewatering efficiency, and extend the life of the felt by simplifying the device.

Embodiments of the present invention will be described below with reference to the drawings.

3 and 4 show an embodiment of the present invention, in which 1 is a metal upper roll, and a large number of small holes 2 are bored on the outer periphery of the roll to connect the inside and outside of the upper roll 1. A hole 4 is formed in the center of the shaft 3 at both ends, a long shaft 5 is inserted into each hole 4, and a small hole 2 provided on the outer periphery of the upper roll 1 is inserted into the long shaft 5 at a predetermined position. A hood 6 is attached to cover the upper roll 1 from inside the upper roll 1, so that the long shaft 5 and the hood 6 are fixed so as not to rotate even when the upper roll 1 rotates, and one end of the long shaft 5 A suction hole 7 is bored in the hood 6 so that the space covered by the hood 6 can be evacuated by a suction device (not shown).

A small diameter metal roll 8 is placed below the upper roll 1.
A lower roll 10 such as a metal roll or a rubber cover roll is disposed between the upper roll 1 and the small diameter rolls 8 and 9 so as to be movable in the vertical direction. An upper felt 12 that circulates around the upper felt 1 and a lower felt 13 that circulates around the small diameter rolls 8 and 9 and the lower roll 10 guided by the guide roll 11 are disposed, and the upper felt
The sheet 14 is sandwiched between the lower felts 12 and 13 and passed between the upper roll 1 and the small diameter rolls 8 and 9.

Furthermore, upper and lower rolls 1, 10 and small diameter rolls 8,
Side plates 15 are provided at both ends of the roll 9, and the air in the space surrounded by the upper and lower rolls 1, 10 and the small diameter rolls 8, 9 can be exhausted from one side of the side plate 15 by a suction device (not shown). be.

The range in which the hood 6 in the upper roll 1 covers the small holes 2 is between the contact points P ₁ and P ₂ between the upper roll 1 and the two small diameter rolls 8 and 9. In the figure,
16 is a bracket for fixing the hood 6, and 20 is a bearing.

When pressurized by the lower roll 10, the small-diameter rolls 8 and 9 are pressed against the upper roll 1, and the lower felts 12 and 13 are pressed between the upper roll 1 and the small-diameter rolls 8 and 9 while sandwiching the sheet 14. be pressured. Here, since the upper and lower felts 12 and 13 and the sheet 14 are in close contact between the contact point P ₁ of the small diameter roll 8 and the upper roll 1 to the contact point P ₂ of the small diameter roll 9 and the upper roll 1, Small diameter roll 8 and upper roll 1
The water dehydrated by the pressure can be sufficiently transferred to the upper and lower felts 12 and 13, where it is dehydrated.

In addition, when a suction device (not shown) is activated to exhaust air from the space covered by the hood 6 fixed to the non-rotating long shaft 5 inside the upper roll 1, the contact point _P1 and the contact point _P2 are Moisture is sucked from the upper felt 12 which is in close contact with the sheet 14 between the two, and the water dehydrated from the sheet 14 is easily transferred to the upper felt 12.

Further, when the space surrounded by the upper and lower rolls 1, 10, small-diameter rolls 8, 9, and side plate 15 is evacuated by a suction device, the space is in close contact with the sheet 14 between the contact point _P1 and the contact point _P2 . Moisture is sucked from the lower felt 13 and the water dehydrated from the sheet 14 can be easily transferred to the lower felt 13 in the same way as described above.

In this way, by dehydrating under pressure while operating the suction device, the wet sheet 14 can be dehydrated extremely efficiently, and rewetting after dehydration can be prevented.

Furthermore, since the small-diameter rolls 8 and 9 are used, a high actual line pressure can be obtained, and since the small-diameter rolls 8 and 9 can rotate, there is no need for a lubricating device or belt like in conventional dewatering equipment. 12 and 13 will also have a longer lifespan.

FIG. 5 shows another embodiment of the present invention, in which a single lower roll 10 is provided in substantially the same configuration as the embodiment described above.
The two small-diameter rolls 8 and 9 were pressurized by three relatively small-diameter back-up rolls 1.
This is an example in which pressure is applied at points 7, 18, and 19. Components having the same reference numerals as those in the previous embodiment indicate the same components, and this embodiment is also equipped with a suction system as in the previous embodiment.

In this embodiment, as in the previous embodiment, the upper and lower felts 12 and 13 and the sheet 1 have a relatively wide width.
4 and the upper and lower felts 1 by suction.
Since the water is sucked from 2 and 13, it is possible to effectively dehydrate while preventing rewetting after dehydration. In particular, the three back-up rolls 17,1
Since the two small-diameter rolls 8 and 9 are pressurized at steps 8 and 19, the small-diameter rolls 8 and 9, which have relatively small diameters,
9, it becomes possible to apply high pressure without causing the small diameter rolls 8, 9 to bend.

It should be noted that the dewatering apparatus of the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

As described above, according to the dewatering apparatus of the present invention, (i) the sheet between the upper and lower felts is dehydrated by being pressed against the upper roll by two small-diameter rolls, so that the upper and lower felts and the sheet are separated; The contact area becomes wider, and the pressure-dehydrated moisture is ensured to transfer to the felt.

(ii) Since the upper and lower felts in close contact with the sheet are dehydrated by suction, the water dehydrated from the sheet can easily be transferred to the felt, and rewetting after dehydration can be prevented.

(iii) Since the rolls that press the sheet and felt have small diameters, high actual line pressure can be achieved.

(iv) Since the small diameter roll that presses the sheet and felt rotates smoothly, there is no need for a lubricating device or belt required in conventional dewatering equipment, and the life of the felt can be extended. Therefore, it can be manufactured at low cost and maintenance costs are also low.

(v) If the two small diameter rolls are pressurized by three back up rolls, it becomes possible to dewater at even higher pressure without causing any deflection of the small diameter rolls.

etc., exhibits various excellent effects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional dehydrating device, FIG. 2 is an explanatory diagram of another example of the conventional dehydrating device, FIG. 3 is an explanatory diagram of the dehydrating device of the present invention, and FIG. 4 is an explanatory diagram of the dehydrating device of the present invention. The direction arrow view and FIG. 5 are explanatory views of another example of the dewatering device of the present invention. In the figure, 1 is the upper roll, 2 is the small hole, 6 is the hood,
8 and 9 are small diameter rolls, 10 is a lower roll, 12 is an upper felt, 13 is a lower felt, 14 is a sheet, 1
7, 18, and 19 indicate backup rolls.

Claims (1)

[Claims] 1. A top roll having a large number of small holes on the roll surface has two small diameter rolls supported by a back up roll facing each other so as to sandwich two circulating strips of felt, and the contact point between the top roll and the two small diameter rolls is A dewatering device characterized in that the moisture in each of the felts in between is sucked from the inside of the top roll through small holes, and can be sucked from a space surrounded by the two small diameter rolls and the back up roll.