US2083445A - Device for treating wood and the like - Google Patents

Description

June 8, 1937- o. R. HELLBORG El" AL 2,083,445

DEVICE FOR TREATING WOOD AND THE LIKE Filed Sept. 21, 1954 6- w v x-"W Patented June 8, 193 7 PATENT OFFICE DEVICE FOR manure woon AND 'rnn Otto Runo Hellborg and Gunnar Arvid Nyberg, Stockholm, Sweden Application September 21, 1934, Serial No. 744,990 In Sweden September 27, 1933' 3, Claims. (Cl. 144-208) The present invention refers to a method for the treatment of wood or other material with heat in combination with cooling the same by a liquid from which heat is recovered. According to this method the material to be treated, for example wood, which is to be used in the production of wood-pulp, is continuously or discontinuously passed through a chamber to a part of which, lying between the end where thema- 10 terial enters and that where it leaves, heat is supplied, partly in order to achieve the required temperature and partly in order to replace the heat lost during the process. The temperature of the material then rises as it proceeds from the entry towards the place where the heat is applied and falls as it proceeds therefrom. The invention is characterized by the fact that a liquid medium for the conveyance of heat is caused to act upon the material under treatment in such a way that the medium in question cools the warm material which is in process of leaving the chamber and is itself simultaneously heated by said materiaLand that the heat thusabsorbed is continuously or discontinuously and directly or indirectly conveyed to the front part of the treatment chamber where it is again given oil to the cooler material which is entering the chamber, the temperature of the material being thus raised.

The treatment described may take place so that the material to be treated is either entirely or partly submerged in or floating on the liquid conveying the heat, i. e., the liquid will thus more or less completely fill the space between the logs of wood, if the material is wood, or alternatively, the liquid conveying the heat may be allowed merely to spray over the material.

However, the form of the method first mentioned involves considerable complications of .a'

40 constructional nature since the treatment-chamber must then be built so that it will retain the liquid without leakage and, in addition, so that it can withstand the pressure which is exerted by the treatment-liquid. In the latter alternative, i. e. when the liquid is sprayed over the material, it is not necessary to construct the chamberso that it will withstand the pressure of a column of liquid. This latter method of applying the invention also gives certain other advantages for the rational carryingout of the treatment, as will appear from the following description. Accordingly, in the following description only those forms of execution of the invention have been included which are in accordance with the latter method of treatment, 1. e., it is assumed that the liquid conveying the heat is sprayed over the material under treatment.

In order to achieve the best possible heat-recovery and certain other advantages it is suitable to divide the treatment-chamber into a number of imagined sections, each section receiving all or a certain part of the heat-conveying medium from a preceding section, counting from the end where the material leaves the chamber. It has proved suitable to allow the greater part of the heat-conveying medium circulate a. number of .times through the same section, before it is transferred to'the next section, while a smaller portion is continuously or discontinuously passed through the various sections.

In order to illustrate the method of procedure some examples are given below with reference to the accompanying drawing, which gives schematic representatives of forms of execution of plants for applying the method.

Theexamples refer to the case where the material to be treated is timber which is to be barked and the object of the treatment is to loosen the bark due to the fact that the resin and other adhesive materials are softened by the heat-treatment. The bark can then be removed in a suitable manner, for example by jets of liquid, by mechanical treatment with wire brushes, in a barktank etc.

Fig. 1 shows a vcrtical longitudinal section of a schematically shown plant for the purpose in question. Fig. 2 shows a vertical longitudinal section of another form of execution of such a plant.

i represents a treatment chamber through which the timber 2 is carried by means of a suitable transport organ which consists, according to the figure, of an endless transporter 3.

The timber is passed in through the funnel 4 and falls on to the continuously or discontinuously moving transporter. At a suitable dis-, tance from the end where the timber enters, for example about the middle of the room, the heat- .medium, which may consist of steam, hot water etc., is supplied at 5, when it to begin with heats the timber or the heat-conveying medium to the required temperature and, during the process, replaces the heat which is lost. At the end where the timber leaves the chamber, the heatconveying medium, for instance cold water, enters through the pipe 6 and its spraying device to. In this case the medium is water which, in a suitably finely-divided state, is sprayed over suing the transporter.

the timber. This water cools the timber, its own temperature being simultaneously raised. This warm water is collected in a receptacle-10 and then conveyed by means of a pump In. in the pipe- 5 line I to the timber in the front end of the chamber and is there caused by means of a spraying device 8 to spray over the timber. The water then gives oi! the heat it has previously absorbed to the timber, which is thus pre-heated, 10 the water being correspondingly cooled.

From the end where the timber leaves the treatment-chamber it can be carried to a watertank I from which it is later transported to the barking plant (not shown), or the timber may be transported directly to the barking plant. At

the end wherethe timber leaves the treatmentchamber there is a cutting-off device, shown in the drawing as a movable shutter iii, and, in the tunnel l where the timber enters, there is a self-closing shutter-device ii. The object of these cutting-oi! devices is to close the treatmentchamber so as to reduce the loss of heat.

In the practical application of the method it -is advisable to allow the greater part of the water to circulate a number of times through the two sections before and alter the place where the heat is supplied before being conveyed to the next section or removed from the plant. A smaller part of the water may be continuously transported to the end where the timber enters.

It is also advisable to construct the transporter in such a manner that it slopes towards the end where the timber leaves the chamber with the object oi reducing the power necessary fordriv- In order to procure better heat recovering and also to obtain certain constructive simplifications oi the plant it is suitable to divide the treatmentchamber into a number of imagined zones to ,40 each, of which water is conveyed from a preced+ ing zone, counting from the end where the timber leaves. As a result of such a division, the diil'erencein temperature between the various zones is reduced which, in its turn, makes it possible 45 to cool the wood continuously towards the end where it leaves the chamber and to heat it continuously from the end where it enters, counting from the place wherethe heat-medium is supplied.

This form of execution of the method is shown schematically in Fig. 2.

The treatment chamber is here divided into nine (imagined) zones or sections, A, B, C, D, E. I", G, H and I, which are, however, not sepa- 5 rated by partition walls. Steam is supplied in section E through pipe 5 so as to heat the wood to the required temperature and to replace the heat lost in the process. Sections A-D and F -l? are provided at the bottom with collecting ves- 60 sels a, b, o, d and f, g, h, i respectively, in. which the water which runs of! from the respective sections is collected. There is a pipe-line ll proceeding from each of the collecting vessels, provided with a pump it and fitted with a spraying device 86 II which is situated over the wood as shown in the diagram. These pipe-lines are provided partly with the object oi keeping the water in circula- Y tion through each section and partly to convey a portion of the water to the next section.

Water at the ordinary temperature is introduced to section I through the pipe 12 and its spraying pipe is. The water collected in the vessel 1 is kept in circulation in section I by means I of the pump I4 and is sprayed over the wood in 75 this section by means of the sprayer ii, The

sprayer ii is, however, extended so that it reaches partly over section H so that a portion of the water is also sprayed in that section. The arrangement is the same with the other sections takes placejby overflow from 'one collecting vessel to another. The distribution of temperature within the treatment chamber will thus be such that the maximum temperature will be reached about the middle of section E and fall of! towards each of the ends.

The temperature in each of the sections A and I which are situated nearest the places of entrance and exit will thus be so low that no special apparatus for the prevention of loss'oi' heat will be required. A i'urther simplification may also be achieved by allowing the wood to be placed direct on the transporter or other means of conveyance such as, for example, trucks running on rails I advisable to introduce into the circulation sys- The combination of heating and cooling by' tem one (or more) organs for the removal of such solid matter, for example a screening device by means of which the solid matterseparated from the logs may be removed so that it does not re-. enter the system. It may also prove advisable to introduce into the circulation system one or more vessels in which matter dissolved from the bark or the wood, such as resins, tannic acids etc. can be removed by screening, precipitation by chemicals, skimming or in some other suitable manner.

It is-already known that certain chemicals iacilitate the loosening of the bark. The present invention makes it possible to make'use of this fact by introducing such chemicals into the system at a suitable point, whereafter they, after having assisted in the loosening of the bark, can be effectively rinsed oil in the same way as the tannic acid. It required, they can then be recovered and used again. As an example it may be mentioned that the SO: gas blown oi! irom a digester may be introduced in section E together with the heating steam. If desired, the waste liquor from the cellulose digesters, or, in the case of sulphite waste liquor, the liquor from the spirit plant may be introduced at a suitable point in the system.

Even though the method just described for the recovery of heat makes it possible that the consumption of heat in the, process may be kept very low, it may still be advantageous in many cases to derive this heat from more or less waste heat obtained in blowing-oil the sulphite or-sulphate digesters or from the waste liquor from the spirit plant if it is a sulphite mill. This heat may be introduced into the system directly in the form oi. steam or in a liquid form, as hot water for ex- 2,053,445 F 3 mitting surface isprovided between the treatment-liquid and the heating medium.

The invention is not, however, comprised tc application in the removal of bark from timber,

but may be used, for example, in the impregnae tion of wood-so as to protect it from rot, microorganisms etc.

.Weclaim:

1. An apparatus for loosening the bark of timber prior to barking by means of a liquid, consisting of a long treatment chamber, a timber transporter in the lower part of the chamber,

means for supplying heat to the middle portion of,

the treatment chamber, spraying devices in the upper part of the chamber, devices for collect-f ber prior to barking'by'means of aliq'uid; consisting of a long treatment chamber, a timber transporter in the lower part of the chamber, means for supplying heat to the middle portion of the treatment chamber, several single spraying devices in the upper part of the chamber distributed over the treatment distance, collecting devices arranged in such way underneath each two neighboring spraying devices that each collecting device is able to collect a part of the water issuing from said neighboring spraying devices, means for conductingthe water from the collecting device into the one of said two spraying devices lying nearest'to the entry side of the chamber. 3. An-apparatus for loosening the bark oi tim-'- ber prior to barking by means of a liquid, consisting of a long treatment chamber, a timber transporter in the lower part of the chamber, means for supplying heat to the middle portion of the treatment chamber, spraying devices in the upper part of the chamber, devices for collecting the liquid underneath the spraying de-' vices, means for carrying the liquid from one collecting device to the next spraying device in direction toward the entry side of the chamber, and means for carrying liquid to the first spraying device in the exit part of the chamber, said transporter. being inclined downwardly in the direction of the exit side of the chamber.

O'I'IO RUTNO HEILBORG.

I GUNNAR ARVID NYBERG.

Images