US2061662A - Pulp refining apparatus - Google Patents

Description

Nov. 24, 193.. W. v. KNOLL ,MLfiG PULP REFINING APPARATUS Filed March 14, 1955 a Sheets-Sheet 1 W. V. KNOLL PULP REFINING APPARATUS Nov. 24, 1936,

Filed March 14, 1935 2 Sheets-Sheet 2 Patented Nov. 24, 1936 UNITED STATES PATENT OFFICE PULP REFINING APPARATUS William VrKnoll, Dayton, Ohio, assignor to Mid- West-Fulton Machine Company, Dayton, Ohio Application March 14, 1935, Serial No. 11,093

3 Claims.

This invention relates to improvements in pulp refining apparatus and particularly to apparatus it to the inlet for further refining.

These commercial beater engines usually comprise a large blade-d roll of great weight, the blades of which'rotate in proximity to the bladed bedplate over which the pulp passes. Adjustment is provided for letting the roll downward toward the bedplate to compensate for wear, but there is nothing except the weight of the roll to prevent it from moving upward.

The number of cutting blades which may be 30 employed in the bedplate, and consequently the an overcome its resistance to rotation.

In refining apparatus of the aforesaid character the beater engine must not only serve the purpose of cutting and dis-integrating the stock but must serve also as a pumping means capable 3.3 of raising the beaten pulp over a relatively high backfall, thereby to provide a sufiicient head to cause the pulp to move away from the beater outlet through the storage and conveying trough back to the inlet. Inasmuch as a beater engine,

ll) properly constructed to be efficient as such, is

highly inefficient as a pumping means for raising a fluid to a higher level a large amount of power is thus wasted.

Another disadvantage, in apparatus of this kind,

45 is that the pulp returns to the beater inlet and is brought into contact with the revolving beater roll at substantially no pressure, the result being that the spaces between the roll blades do not fill except when the roll is revolved at a slow in- 50 efficient speed. Furthermore, the pulp in contact with the roll at the beater inlet is under substantially zero velocity until brought into motion by the roll itself. The result is that each time a volume of the material enters the space be- 55 tween two blades of the roll, this volume must be raised almost instantly from a state of rest to the peripheral speed of the roll. Except in cases where engines of this class are revolved at a slow inefficient speed, the power consumed in thus overcoming the inertia of the material at the inlet is extremely high.

It has, however, been heretofore proposed to employ, in combination with a tank and a beater engine, a separate pump for circulating the fluid mass through the system, these efforts having mainly for their object the provision of means to relieve the beater engine of the burden of discharging the pulp over the relatively high backfall, which at the best provides a very small head, and providing instead a greater fall capable of moving the beaten pulp away from the heater 1 outlet more rapidly.

In my U. S. Patent No. 1,793,095 of February 17, 1931, the apparatus shown contemplates, among other features, the use of a small high speed beater roll and a separate pump, the pump being arranged to not only relieve the beater of the burden of raising the fluid mass over a backfall, but also to deliver it to the beater inlet under pressure, the object being to cause the pressure so applied to more thoroughlyv fill the pockets between adjacent blades of the roll even when the roll is being operated at exceptionally high speed and thereby to increase the capacity of the beater engine.

But while thus delivering the pulp under pressure to the beater inlet has its advantages over common practice in more completely filling the spaces between the blades of a roll operating at high speed, thereby enabling a smaller roll to disintegrate a greater amount of stock in a given time, it will be found that a considerable portion of this gain is again lost due to the fact that the pressure is radially applied to the beater roll, and to that extent results in greater unit pressure being applied to the roll bearings creating higher friction losses, this effect being, of course, greater as the pressure at the inlet is made higher.

Furthermore, in my U. S. patent, supra, no provision was made or contemplated to insure that the incoming material shall be moving at a velocity substantially equal to the peripheral speed of the roll before it is permitted to come in contact with, and enter into the spaces between the roll blades.

Now the prime consideration in the design of a heater roll is its capacity to cut and disintegrate the fibrous material, whereas its ability as'a pump to move the fluid, and as an engine capable of being acted upon by the fluid is necessarily of secondary importance. But while the beater roll of common practice, as employed to raise the material over the backfall to a higher head is highly inefficient as a pump, using power for this purpose out of all proportion to the head created, this type of roll when designed with full consideration of its disintegrating capacity has been found to be relatively efficient as a turbine wheel when fluid under velocity has been applied thereto.

Systems employing this turbine principle have been proposed in several instances, yet in none of them have structures been provided which have their disintegrating and turbine elements arranged in a relation to each other which gives best results.

It is therefore an object of this invention to greatly increase the capacity of a pulp refining unit of a given size, by providing a beater engine having a power driven roll with means extraneous to the beater roll for delivering the pulp through the beater inlet to the periphery of the roll at high velocity, and causing it to impinge on the roll blades substantially tangential thereto after the manner of a turbine and at a point immediately adjacent the bedplate, the speed of the pulp being preferably at least equal to the peripheral speed at which the roll is being power driven, to the end that the pulp, which for eflicient operation must necessarily move through the beater at great speed, will, in doing so, preferably relieve the power means of as much driving effort as would otherwise be consumed in the circulating function, and further, by including means not dependent on rotation of the beater roll to move the pulp away from the beater outlet so as to relieve the beater roll of the burden of raising the pulp over a backfall to a higher level, whereby the power applied to the beater roll shaft is such only as is required for cutting and disintegrating the material.

Another object is to provide a beater roll of given dimensions with a large bedplate having more than the usual number of cutting edges, and. positive adjusting means for holding the roll at all times in substantial contact with the bedplate.

That these and other objects and meritorious features of the invention are attained will become apparent upon consideration of the description, reference being had to the drawings, wherein,

Fig. 1 is a vertical section through the improved beater engine showing the means employed to produce a turbine effect.

Fig. 2 is an elevation of a complete refining system including the improved beater engine.

Fig. 3 is a vertical section through the roll adjusting means.

Fig. 4 is a modification of the system shown in Fig. 2.

Similar numerals refer to throughout the several views.

Referring now to the drawings, the beater engine, which may be broadly designated by the numeral I0, comprises a roll II supported by a shaft I2 rotatable in roller bearings I4. The bearings I4 are held in bearing blocks I6 vertically slidable in the end frames I8. Adjusting screws (see Fig. 3) are nonrotatably secured to the. top of the blocks I6 and extend upwardly, fitting into internally threaded worm wheels 22. The worm wheels are contained within the worm wheel housings 24 and are held thereby against vertical movement. Worms 26 both secured to the worm shaft 28 are simultaneously rotatable similar parts by the hand wheel 30 which is secured to one end of the shaft, whereby the blocks I6 always movetogether thereby maintaining the roll shaft always in horizontal position. Secured to the periphery of the roll I I are a plurality of blades 3 I. End shrouds 33 are secured to the ends of the roll and to the ends of the blades to prevent the pulp which is being carried in the pockets 35 between the blades from spreading endwise, thereby providing a somewhat greater turbine effect.

Mounted on the base 32 intermediate the end frames I8 is the bed plate 34 which in turn supports the roll housing 36, (see Fig. 1). The bed plate 34 is considerably wider and contains a much greater number of bed plate bars 38 than is found in common practice, this advantage being attainable because of the fact that the roll is always positively held against upward movement.

The discharge housing 40 is secured to the roll housing 36 at the flanges 44. It will be noticed that the discharge housing contains no backfall, but instead is extended upwardly as at 46, Fig. 1, so as to provide a wide opening 48 preferably equal to substantially one fourth of the roll circumference. This wider opening gives a longer period of time within which the pulp within the pockets 35 may be discharged therefrom by the centrifugal force generated at the high speed at which the roll is operating.

The inlet housing 50 is secured to the roll housing 36 at the flange 52. The opening 54, Fig. 1, within the inlet housing tapers toward the roll, terminating in a narrow nozzle 56 at the point where it enters the roll housing. The nozzle 56 is preferably not much wider than the radial depth of a pocket 35, the direction of movement of pulp being discharged from the nozzle being preferably substantially at a tangent to the periphery of the roll midway of the height of the blades.

Now it will be observed that the bottom edge of the nozzle 56 is located at the point on the inner circumference of the roll housing where the bedplate begins. This is important for the reason that as soon as a pocket 35 has been filled with pulp, the high speed at which the roll rotates causes that pulp to be thrown radially outward with a force substantially equal to the force with which the pulp impinged upon the roll blades. This is not objectionable where the edge of the nozzle is at the edge of the bed-plate, for it is desirable to have the pulp forced radially outward toward the bed-plate bars to aid disintegration. Where, however, a nozzle opening is located farther around the circumference at a point in advance of the bed-plate, most of the gain due to the turbine effect is lost because centrifugal force creates a tendency of movement of the pulp in the pockets in a radial direction, producing pressure on the inside of the roll housing, thereby offering a resistance against which the pulp in the pockets must be moved circumferentially from the nozzle around to the bed plate.

Fig. 2, which shows a preferred embodiment of the invention, comprises a heater engine Ill, as hereinbefore described together with a tank 58 and a pump 60, the pump being operated by the motor 62. A pipe 64 connects the bottom of the tank 58 at the inlet 66 of the pump. A second pipe 68 connects the outlet III of the pump to the inlet housing 50 of the beater engine III. A second motor 12 is provided to rotate the beater roll II, preferably through a silent chain I4.

In proportioning the several elements of the system shown, a heater engine may first be pro-' vided of a size having the required stock moving capacity when operated at the highest practicable speed. The peripheral speed of the beater roll I I being thus determined, a pump 60 and motor 62 are provided of such capacity as will maintain a constant discharge of material fromthe nozzle 56 at a velocity in feet per minute equal-to or greater than the selected peripheral speed of the roll. The pump and its motor should be able to maintain the aforesaid rate of discharge through the nozzle56 when the nozzle is without back pressure such as when the roll I I is removed from the beater engine. The cross sectional area of the pipe 68 is greatly in excess of the cross sectional area of the end of the nozzle 56 being preferably of a diameter equal to the width of the roll. The velocity, therefore, at which the material must be moved through the pipe 68 is much less than the nozzle velocity. This, of course, reduces the total friction to be overcome. The motor I2 for driving the beater roll I I may then be selected, it having a capacity sufiicient to maintain the first determined beater r011 revolution speed against the resistance which the cutting and disintegrating function imposes. Where the velocity of the material is in excess of the speed at whichthe roll is being revolved by the motor I2, the impact of the incoming material against the blades relieves the motor I2 of a corresponding portion of the disintegrating load.

Although the applied power and revolution speeds have been fixed as above indicated with a view of harmonizing the beater nozzle discharge velocity with the peripheral velocity of the beater roll, it is still possible to vary this relationship by altering the velocity of nozzle discharge. This may be done by maintaining a higher or lower static head in the tank 58'whereby the ability of the pump 60 to maintain the given discharge at the nozzle 56 is altered.

In the modification shown in Fig. 4 the beater engine II] is placed intermediate the bottom of the tank I6 and the pump 60. In this installation the velocity of discharge at the beater nozzle 56 is dependent wholly on the static head in the tank. The pump 60 is required to return the pulp to the top of the tank through the pipe I8'to maintain the desired head, and to keep the discharge housing 4 0 clear so that there will be no back pressure against which the beater roll is required to operate.

While in the embodiment of the invention herein shown the pulp is conveyed to the beater inlet housing through a relatively large pipe, and the inlet housing itself is then constricted to provide a nozzle of greatly decreased area, it will be understood that it is entirely feasible under certain circumstances to restrict the pipe which conveys the pulp to the beater engine to the size of the nozzle for its entire length. For instance, the

pipe 80 in Fig. 4 could well be of a cross sectional area and contour corresponding to the nozzle 56 for the entire length between the bottom of the tank I6 and the end of the nozzle at the beater roll, the object being merely the provision of means which will harmonize the velocity of the material as it comes in contact with the roll and the peripheral speed of the roll and to direct the moving material against the periphery of the roll tangentially.

Having this view of the scope of the invention, I claim 1. The method of refining pulp in a beater engine having a rotatable bladed roll and a stationary bladed bedplate, which comprises raising a stream of said pulp to a velocity substantially as high as the peripheral speed of said roll then di- 2. In a beater engine of the character described,

the combination of a bladed beater roll, a bedplate, means enclosing said roll having a circumferentially wide outlet and a circumferentially narrow inlet opening for the pulp, the bottom edge of the said inlet opening being at one edge of the bed-plate, and means to direct a stream of pulp thru said opening at a. velocity substantially that of the peripheral speed of said roll and in a direction substantially tangential to said roll at the said edge of the said bed-plate.

3. The structure defined in claim 2 in which the inlet opening is substantially as wide circumferentially as the depth of the blades of the roll.

WILLIAM V. KNOLL.

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