US1402138A - Method and apparatus for loosening bark from pulp wood - Google Patents

Description

.G. P BERKEY. METHOD-AND APPARATUS FOR LOOSENING BARK FROM PULP WOOD.

APPLICATION FILED MAR. 271 1920.

Pat ente d Jan. 3,1922.

' INVENTOR a niran srrs area rates.

GEORGE PHELPS IBERKEY, F 'APPLETON, WISCONSIN.

Specification of Letters Patent.

Patented Jan. 3, 1922.

Application filed March 27,1920. Serial No. 369,170.

T 0 all whom it may concern:

Be it known that I, GEORGE P. Banner, a citizen of the United States, and resident of Appleton, Outagamie County, Wisconsin, have invented new and useful Improvements in Methods and Apparatus for Loosening Bark from Pulp Wood, of which the following is a description, reference being had to the accompanying drawings, which are a part of this specification.

The invention relates to a method and apparatus for loosening bark from pulp wood preparatory to passing the wood through the drum or tumbling barkers in order to facilitate the removal of the bark.

In the process of drum barking, as used in paper and pulp mills, it is very difficult to satisfactorily and economically remove the bark from a large amount of wood used during the year. Fresh cut or green wood is the only kind that barks easily, and this sort of wood is available to the average mill only a short time during each year. As the green wood dries out in storage, the sap and resinous matters between the bark and the wood dry out and cement the bark tightly to the wood, making removal very difiicult in comparison with fresh green wood, also, in cold weather the bark is frozen to the wood and an even more diflicult barking problem is encountered.

In an endeavor to overcome these difficulties the wood is floated from the storage to the mill whenever possible and the wetting which each stick of wood receives in this way helps to some degree in subsequent removal of bark, varying with the length of time the wood remains in the water. But this method is not complete or thorough and cannot be made practically so as the wood must remain in ordinary river water of 4:0 to F. for days or weeks to effectively loosen the bark and such a large water storage for the logs as would be required for this purpose is not possessed by the average mill. Furthermore, another difliculty is encountered due to the extreme buoyancy of the wood which will float only one-third or onehalf submerged and the wood piled on top will not be submerged at all, consequently a large portion of the'wood is only partially subjected to the action of the relatively cold, and therefore slow acting, water and such a method must be completely abandoned during the winter months when the rivers and water-ways adjoining the mills are frozen. During such months a mill may resort to the hot pond where a small area of water close to the mill is kept from freezing by the use of steam. But the cost of such a hot pond is large as there is such a large surface for evaporation or loss of heat and the wood has such a short time to remain in the necessarily small pond that very little is accomplished, and in addition the same drawbacks occur as in the river water during the summer months, that is, the comparatively low temperature of the water in the hot pond and the buoyancy of the wood are factors which prevent the effective loos: ening of the bark.

By the present method the bark covered wood or logs are subjected to the action of a relatively small heated body of water while the logs are submerged therein by a comparatively inexpensive apparatus useable throughout the year. Preferably this method is carried out'in a continuous process of conveying the logs under the surface of a heated body of water so that the soaking which they receive in the heated water dur ing the time they are being conveyed through the tank will be sufficient to loosen the bark from the wood so that the bark will come off easily as the sticks or logs pound against each other in the revolving cylinders known as barking drums.

The following method, together with the apparatus, gives a comparatively low cost of installation, continuous, positive operation, low cost of handling and maintaining, complete submersion of wood, low cost of heating and as a consequence of these factors a complete and very effective treatment of all the wood, as has been demonstrated on a commercial scale by the use of the apparatus hereinafter described in carrying out the method hereinafter described.

The invention further consists in the method and apparatus for loosening bark rom pulp wood as hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In' the drawing, Fig. 1 is a vertical sectional view of an apparatus for carryingout the method of embodying the invention.

In'the drawing the numeral 3 refers to a relatively long,narrow tank of concrete or wood for containing warm water which is preferably heated by means of steam or other heating agent introduced therein in any suitable manner, as by means of pipes 3. It is preferred to keep the water in this tank heated to a relatively higher temperature than that of river water in summer, though it will be understood that .the temperatures may vary, depending upon the length of time that the wood is subjected to the action of the heated water and the condition and character of the wood.

Within the tank I have shown an endless conveyor l and an endless conveyor 5, the delivery end of conveyor 5 overlapping the receiving end of conveyor 4:.

Conveyor 4: is a standard type of flat conveyor with or without flights 6, the conveyor being so inclined to the surface of the water in the tank 3 that asthe wood floats under it it is carried down and submerged and finally as it reaches the end of the conveyor the wood bobs upward, due to its buoyancy, and strikes conveyor 5.

Conveyor 5 is a standard type of flat or apron conveyor with or without flights, with either iron or wooden slats, and soplaced that the lower or carrying portion is submerged in the water of the tank.

These two conveyors are continued in the long tank, which may be of wood or concrete, and extend across the entire width of the tank. Water in the tank may be heated to any desired temperature.

. For green wood or on occasions where a minimum of soaking is desired or necessary conveyor 4, or the submerging conveyor, 'need not necessarily be used as conveyor 5 is so constructed and placed with reference to the surface of the water, as will beapparent from the drawings, that wood may be floated along the front end 7 and carried along and submerged, usually to the depth of one layer of wood only. The extreme buoyancy of the wood causes it to press tightly against the submerged portion 'of the conveyor and it is so carried along in the water of the tank until it eventually bobs to the surface at the end of conveyor 5 and is ready to be removed from the tank and taken to the barking apparatus. 1

When it is desired to increase the capacity,

of the apparatus or give a longer soaking time submerging conveyor 4. is used with conveyor 5. This conveyor runs at a greater speed thanconveyor 5 and consequently will pilethe wood up several layers deep under conveyor 5, the number oflayers of wood being regulatedby the speed of conveyor conveyor 5 under such circumstances conveying several layers of wood to the delivery endof the apparatus. When the twoiconveyors are used a clamor stop 8 is provided between the conveyors'to prevent the wood from floating up to the surface of the water. In a vat 8 wide 'by long, with the conveyor 5-yrunning at a speed 'of 6 per minute with onelayer of woodtherewillbe a delivery or ten 1 cordsper hour at the end of the conveyoren0ugh capacity for the average mill. Running in this manner the wood has 15 minutes of soaking while completely submerged in water. This is sulfr cient to thoroughly loosen the bark on certain kinds of wood but experience hasshown that themost complete treatment of average storage wood takes place with 20 to 30 minutes in water to F. The action of water at this temperature effects a thorough softening of the binding agent between the wood and the bark and the combination of complete submersion and the warm water treatment is more effective after 80 minutes treatment than many days of soaking in ordinary river water'at 40 to 50 F incompletely submerged. The problem has been solved by thepresent apparatus due to the use of warm water and complete submersion, which factors .rapidlyisoften the binding agent. a

The practical results of using this method and apparatus,as proven by several months experience with all lands of wood, are:

1. 20 to 50%. increase in capacity of barking drums, thereby requiring fewer drums (which are very expensive), less power and maintenance and less labor in operating.

2. No brooming of wood at ends of the log or stick. Usually when a large part of the wood comes out of the drums unbarked, as it does without this treatment, the wood has to be picked out and thrown back to go through the drums again. The extra pounding so received causes the ends of the sticks to splinter with a resulting loss of wood and, what is more serious, pounding of fine wood and v dirt into the broomed ends of the sticks where it cannot be removed later and so goes into the process and causes aserious deterioration of value of the pulp and paper.

3. Prior to this process by far the best results have been obtained by running the barking drums wet, that is, passing the carried suspended with the bark that the value of the bark as fuel isseriously impaired and its disposition made difficult and expensive. By the present process the bark is so thoroughly softened before going to the drums that itcan be run through the drums dry, that is, without the use of water, thereby greatly increasinglits value as fuel.

4. The-method and apparatus may be used throughout the year witha relatively small steam consumption required to heat the water because of the small amount of steam necessary tobe used andthe small area or surface exposed' to radiation losses.

5, The method and apparatus .provides a positive continuous operation with small amount of labor required and at a less expense for power, maintenance and original cost than prior processes.

What I claim as new and desire to secure by Letters Patent, is:

1. In an apparatus for preparing pulp wood for the barking process, the combination of a tank containing Warm water, a conveyor for carrying the wood in a submerged condition through said tank, and a. feeding conveyor having its delivery end disposed at a distance from the under side of the first conveyor and moving at a greater speed to deliver a plurality of layers of wood to the first conveyor.

2. In an apparatus for preparing pulp wood for the barking process, the combination of a tank containing warm water, a conveyor for carrying the wood in a submerged condition through the tank, and an inclined submerging conveyor under the upper end of which the Wood is floated and from the lower end of which the wood floats up onto the receiving end of the first conveyor.

3. In an apparatus for preparing pulp wood for the barking process, the combination of a tank containing warm water, a conveyor for carrying the wood in a submerged condition through the tank, a submerging conveyor in said tank having its delivery end overlapping the receiving end of the first named conveyor, and a dam between the overlapping ends of the conveyors.

In testimony whereof, I aflix my signature. 35

GEORGE PHELPS BERKEY.

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