US2432008A - Process and device for full-cell treatment of timber and similar material - Google Patents

Description

PROCESS AND DEVICE FOR FULL CELL TREATMENT OF TIMB'ER AND SIMILAR MATERIA Filed Feb. 20, 1943 Dec. 2, 1947. B. o. HGl-:R ETAL 2,432008 Patented Dec. 2, 1947 PROCESS TREATMENT OF TI MATERIA AND DEVICE FOR FULL-(DELL MBER AND SIMILAR Bror Olof Hger-and Stig Bertilsson Kjellstrm,

Stockholm, Sweden,

assignors to Bolidcns Gruvaktiebolag, Stockholm, Sweden, company of Sweden.

a joint-stock Application February 20. 1943, Serial No. 476,592, In Sweden February 7, 1942 11. Claims.

Thev impregnation ofl timber and similar material is effected in practice mainly-in accordance withv the empty-cellor the full-cell process.` The empty-cell process is adoptedwhen the preservative is an oil, thefull-cell' process when the preservative is dissolved.` or emulsifiedin some cheap liqlfd such as for instance-'waten In principle, the empty-cell process proceeds the followingr manner. The material. to be treated is first exposed in an impregnating cylinder to an initial air pressure above the atmospherc'pressure after which the cylinder is fille'd With the preservativefoil; while the same pressure is maintained. The pressure in the cylinderiis then increased,'. whereby the preservative oil .is'introduccd into thematerial. Afterl some time the cyl'nder 'isemptied ofithe preservatve oilanrl the material is subjected to avacuum,

whereby part of thefpreservative oil is expelled` from the cell-cavitiesV of the material by the' internal air pressure'which prevails there. The consumpti'on of the preservative oil is'thus considerably reduced, as the cell cavities will be only partially filled with the preservative oil, whilst" a uniformdistribution' of the preservative oil'in the' material is nevertheless: obtained; When treatingtim'ber with preservative oils it is necessary touse the empty-'cell process foreconomic.

reasons;

By full-cell processthe material to be treated is su'b'jected in a cylinder` toavacuum; after which the cylinder, whilev the vacuum is maintained, is filled witha solution* or an emulsion of'v the preservative; The solution or emulsion' is then introduced 'into the material by pressure, so that the cell-cavities are filled with solution or emulsion. When treating with solutions or 'emulsions' the amount of preservative absorbed by the material is controlled'by regulating the concentration' of the solution or emulsion', so.that the comparatively complicated empty-cell treatmentneed not be resorted to.

The present 'inventionirelates' to a.. process and device for effecting full-cell'treatment of timber and similar material. A device in accordance with this invention consists of a container for the solution cr emulsion of preservative, a chamber or a cylinder in which the treatment takes place, a smaller container designed for vacuum and pressure and an air pump or air pumps for effecting Vacuum andpressure, as well as piping for the connection of the different parts of the device and the requisite valves. A process according to the invention for' eifectingv full-cell treatment of timber with'a preservative solution or emulsion includes the feature of subjecting to vacuum a charge-of timber disposed in a treating zone communicating with a smaller zone; introducing preservative from a supply zone into said treating zone and said smaller zone with the aid of the vacuum until the charge of timber is substantially completelyv immersed in preservative and also the smaller zone is filled with preservatve and, after closing the communication between the treating zone and supply zone, discontinuing the vacuum and applying superatmospheric pressure to the preservatlve in the smaller zone thus causing the cellsof the timber in said treating zone to absorb preservative, this absorbed preservative being supplied from the smaller zone so that the timber in the treating zone remains completely immersed in-the preservative throughout the entire treatment; opening the communication between the treating zone and the supply zone 'for removing from said-smallerv Zone and from the treatingzone'the preservative notabsorbed by the timber and removing the-impregnated charge-of timber from thetreating zone.-

An example of a device in accordance with this invention is shown in Figures 1 and 2 of the accompanying drawing. The-device'is used` in the following manner: The impregnating chamber or cylinder A-is filled with the material to be treated and is then' closed, whereupon theair pump B creates aV partial vacuum in the smaller con'tainer C and in the cylinder A', while the Valve D is'closed; After the been maintained-for the required time, thevalve D is opened and solution or emulsion fromY container E -is sucked into A and C, while the vacuum is maintained. When the leve1`indicator F shows that the container C has been filled with solutionor emulsion, the -valve D is closed. An automatic valve G1 prevents the solution or emulsion from entering the pump B, thus acting as a safety device. The'pump B is then caused to produce pressure, whereupon the material to be treated rapidly absorbs the solution or emulsion.v The container C mustbe large enough to hold the maximum amount of solution or emulsion which the material can absorb. This container may also take the form of a dome on the cyl'nder A, this'modification being shownmore fully in Figure 2. When the material has absorbed the'requisite'quantity of the solution or absorbed or held within the cells or interstces of: the material being treated'is di'iven back to thev container whereupon theval've D'is-closed. If

partial vacuum has' needed supplementary compressed air may be delivered during this period by the pump B. After this treatment the material if desired mayfor a short time be subjected to a vacuum. In this way small amounts of the solution or emulsion are sucked out from the oter layers of the material, which reduces the dripping from the material of the solution or emulsion after treatment. The material, when completely impregnated, is removed from the cylinder and is allowed to dry.

Impregnating in the device shown in the drawing may also proceed in the following manner. The cylinder A is filled with the material to bc treated and is then closed, whereupon the pump B creates a vacuum in the container C and in the cylinder A, while the valve D is open. In this way solution or emulsion from the container E is sucked into the cylinder A. When the cylinder A has been entirely or partially filled with the solution or emulsion the valve D is closed. The pump B continues for some time to create a vacuum, after which the valve D is reopened. When the level indicator F shows that the container C' has been filled with the solution or emulsion, the valve D is closed. The pump B is then caused to produce pressure, whereupon the treating process is continued in the same way as previously described.

An impregnating plant in accordance with the present invention can of course be provided vwith usual arrangements for drying, steaming and so on, of the material to be treated as well as for heating of the solution o r emulsion. The container E may also be placed at a lower level than the rest of the plant, which will facilitate the driving back of the solution or emulsion from the cylinder A to the container E.

Owing to the simplicity of the apparatus, the management of an impregnating plant according to the present invention will be very easy. The initial and Operating costs will also below. Moreover, the course of the treatment can be well Controlled as the amount of solution or emulsion absorbed by the material can easily be followed on the level indicator F.

An impregnating plant according to the present invention may be adopted for treatment of timbers and similar material with preservative solutions or emulsions containing an arsenic compound or arsenic compounds (such as 'preservatives according to the U. S. Patent No. 2,139,747).

Having thus described our invention, we declare that what we claim is:

l. A device for the full-cell treatment of timber comprising an impregnating Chamber, a vented container for liquid preservative, means establishing communication between the lower portions of said chamber and container, a supplemental container having its bottom in communication with the top of said impregnating chamber, and pump means connected to said supplemental container at a point above the bottom thereof for creating vacuum or pressure.

2. A device as claimed in claim 1, characterized by the feature that said supplemental container is capable of holding at least the maximum amount of solution or emulsion of preservative which a normal charge of the material undergoing full-cell treatment can absorb.

3. A device as claimed in claim 1, in which the supplemental container takes the form of a dome on the impregnating Chamber in which the fullcell treatment takes place.

4. A process for elfecting full-cell treatment of timber by means of a preservative which comprises subjecting to vacuum a charge of timber disposed in a treating zone, introducing preservative from a suppy zone into said treating zone with the aid of the vacuum until the charge of timber is substantially completely immersed in preservative, ccntinuing the application of vacuum to the timber in said treating zone while causing a smaller zone communicating with said treating zone to become substantially filled with preservative from said supply zone, discontinuing the vacuum and applying superatmospheric pressure to the charge of timber to cause the cells of the latter to absorb preservative, removing from the treating zone excess preservative not absorbed by the timber, and removing the impregnated charge of timber from the treating zone.

5. A process as in claim 4, wherein the charge of timber after impregnation with the preservative is subjected to a short vacuum treatment prior to its removal from the treating zone.

6. A process as in claim 4, wherein the said smaller zone is of a capacity sufiicient to hold at least the maximum quantity of preservative that the charge of timber can absorb.

7. A process as in claim 4, wherein the preservative contains an arsenic compound.

8. A process for eifecting full-cell treatment of timber by means of a preservative, which comprises subjecting to vacuum a charge of timber disposed in a treating zone communicating with a smaller zone; introducing preservative from a supply zone into said treating zone and said smaller zone with the aid of the vacuum until the liO charge of timber is substantially'completely immersed in preservative and also the smaller zone is filled with preservative and, after closing the communication between the treating zone and supply zone, discontinuing the vacuum and applying super atmospheric pressure to the preservative in the smaller zone thus causing the cells of the timber in said treating zone to absorb preservative, this absorbed preservative being supplied from the smaller zone so that the timber in the treating zone remains completely immersed in the preservative throughout the entire treatment; opening the communication between the treating zone and the supply zone for removing from said smaller zone and from the treating zone the preservative not absorbed by the timber and removing the impregnated charge of timber from the treating zone.

9. A process as in claim 8, wherein the charge of timber after impregnation with the preservative is subiected to a short vacuum treatment prior to its removal from the treating zone.

10. A process as in claim 8, wherein the said smaller zone is of a capacity suflicient to hold at least the maximum quantity of preservative that the charge of timber can absorb.

11. A process as in claim 8, wherein the preservative contains an arsenic compound.

BROR oLor` HGER. s'HG BERTILssoN KJELLs'rRM.

REFEREN CES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,135,463 Coolidge Nov. 1, 1938 1,,76j797 Rawson Apr. 29, 1930

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