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Publication numberUS2892261 A
Publication typeGrant
Publication dateJun 30, 1959
Filing dateJul 1, 1955
Priority dateJul 1, 1955
Publication numberUS 2892261 A, US 2892261A, US-A-2892261, US2892261 A, US2892261A
InventorsHutchinson Hamilton M
Original AssigneeHutchinson Hamilton M
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Process for the treatment of lumber
US 2892261 A
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Description  (OCR text may contain errors)

June 30, 1959 H. M. HUTcHlNsoN 2,892,261

PRocEss FOR THE TREATMENT oF LUMBER Filed July 1, 1955 2 Sheets-Sheet l BY TM@ June 30, 1959 H. M. HurcHlNsoN v 2,892,251

PROCESS F 0R THE TREATMENT OF LUMBER Filed July 1, 1955 2 Sheets-Shree?. 2

#pM/70N M. Marcy/fvwm INVENTOR.

United States Patent O PROCESS FOR THE TREATMENT F LUMBER Hamilton M. Hutchinson, Eugene, (lreg. y Application July 1, 1955, Serial No. `519,506

12 Claims. (Cl. S14- 9.5)

This invention relates to the treatment of Wood and wood products, and has particular reference to a process for drying and preserving lumber.

One of the principal objects of this invention is to provide a novel process for treating green lumber to dry the same.

Another object of this invention is to provide a novel process for drying lumber in substantially shorter periods of time than have heretofore been possible.

. Another object of this invention is to provide a novel process for simultaneously drying lumber and rendering the same water-resistant. Y

Yet another object of this invention is to provide a novel process for drying lumber which results in a product having physical properties superior to those of lumber dried by prior art methods. .v

A further object of this invention is to provide a drying process for the treatment of lumber and to simultaneously render the same Water-resistant, flame-resistant and resistant to pests such as termites and the like.

Other objects and advantages of this invention it is believed will be readily apparent from the following detailed description of a preferred embodiment thereof, when read in connection with the accompanying drawings.

In the drawings:

Figure 1 is a diagrammatic view illustrating an apparatus for carrying out the process of this invention.

Figure 2 is a diagrammatic side elevation, partly in section, of a treating tank utilized in carrying out the process of this invention. 1

Figure 3 is a sectional elevation taken substantially on the line 3-3 of Figure 2.

Figure 4 is a sectional elevation taken substantially on Ithe line 4-4 of Figure 2.

1 In carrying out the process of this invention, the green lumber is first placed in a conventional sticking rack so that a plurality of vertical, spaced rows of the lumber are formed. Preferably, the boards are placed horizontally, but on their edges so as to present the maximum Aareas thereof4 in a vertical position. Additionally, it is preferred to tie or strap the lumber to the rack in such manner that it is conveniently handled by conventional fork lift mechanisms.

After stacking the lumber, it is preferably treated with live steam. Although not essential, this steam treatment performs three important functions: it cleans the lumber free of sawdust and other foreign' matter; it raises the,

jected to the action of a liquid drying medium for a' length of time and at a temperature sufficient to drive 0E from the lumber the desired amount of water. have 2,892,261 Patented June 30, 1959 ICC discovered that lumber may be dried quickly and evenly by treating the same with a Water-immiscible liquid treating medium having a iinal boiling point higher than the boiling point of water. Many such liquid treating media may be used, such as, for example, carbon tetrachloride, various relatively high-boiling petroleum hydrocarbon fractions, etc. In the case of such hydrocarbon fractions, it is preferred to select those which do not contain appreciable amounts of heavy ends, i.e., components boiling above about 700 F., since such heavy ends tend to deposit on the wood itself and require excessively high treating temperatures for removal thereof. I have found that so-called naphthas or petroleum solvents, and particularly commercial aliphatic (high aniline type) solvents, such as for example, Standard Oil Thinner #410 (boiling range 360-450 F.) are especially suitable.

T he application of the liquid treating medium is preferably carried out in an enclosed tank through which the liquid treating medium may be circulated, for removal of water from and for reheating of the liquid at points exteriorly of the tank. Optimum drying times are obtained by iirst placing the lumber into the tank and then introducing the heated liquid either by spraying the same over the lumber or by ooding the lumber therewith, or both.

I have found that temperatures above 212 F. must be employed in order to obtain quick and proper drying of the lumber. That is, the temperature of the treating medium at and after the time of initial contact with the wood should be above 212 F. so that the moisture is continuously driven out of the wood, thus preventing ap'- preciable absorption of the treating medium itself. While the specific treating temperature will vary, depending upon thetype of lumber, the specific treating medium ernployed, and other process variables, it has been found' that a temperature range of between about 250 and about 450 F. is satisfactory for most operations. The drying time is one of the process variables upon which the temperature is dependent, but generally from about 4 to about 12 hours is sufficient. It will be understood that, assuming constant temperature, the drying time primarily depends upon the initial Water content, size of the charge of lumber and the sizes of the individual pieces thereof.

During the drying operation, Water is continuously re-V movedfrom the lumber in the form of vapor, and to some extent it is entrained in the circulating treating medium. of water-resistance may be obtained by introducing into I have found that a superior product from the standpoint of water-resistance may be obtained by introducing into the treating medium a minor proportion of a high melting point (i.e., above about F.) Wax such as paraffin wax, a microcrystalline wax, beeswax, etc. Other treating chemicals such as insecticides, dyes, etc., may be added to the treating medium for application to the Wood during the drying operation, if desired.

After the desired drying period has passed, the treat-l ing medium is withdrawn from the tank and the lumber,

steamed free of vapor, or if desired, the lumber may be removed from the tank and the treating medium left to remain in the tank for a suicient length oftime toV permit it to lose an appreciable quantity of its heat before removal, rather thanto immediately expose the hot A lumber to the relatively cool ambient air with .theat'g'v tendant danger of checking, cracking, warping or socalled case-harding of the wood.

Referring now to the drawings, `a specific example of the process of this invention will now be described, as carried out in the apparatus shown therein. This apparatus includes a pair of identical treatment tanks and 11, substantial portions thereof being sunk below the surface of the ground, as shown in Figure 2, in order to facilitate loading and unloading of the tanks. By utilizing a pair of tanks, the process can be greatly speeded up, one of the tanks being loaded or unloaded while the other tank is being used in treating the lumber.

The tanks 10 and 11 are each `generally rectangular in shape, each of the open tops thereof being provided with a cover member 12, 13. Bracket members 14, are provided adjacent each corner of the respective ycover members 12 and 13 for removal thereof by means of a lifting assembly 16, as shown in Figure 3. inasmuch as the two tanks are identical, the remainder thereof will be described in connection with the tank 11. The tank 11 is provided with -a channel element 20 extending about the outer periphery thereof, the bottom edge 21 of the cover member 13 resting on the channel element which is filled with water or other iluid 22 to function as a vapor seal.

The tank 11 is further provided with a pair of upper spray pipes 25 connected together at one end with a transverse pipe 26, and a pair of lower spray pipes 27 connected together at one end with a transverse pipe 29. Liquid inlet lines 30 lead to each of the transverse pipes 26 in the two tanks 10 and 11, and liquid inlet lines 32 lead to each of the transverse pipes 29.

The remainder of the apparatus can best be described in connection with the following description of a preferred embodiment of the present invention: A load of 2 x 6 x 24 ft. boards of rough green common Douglas r, containing roughly 50% moisture, was first struck, steamed as described above for about 1/2 hour and then placed in the tank 11 and the cover member 13 replaced thereon. The liquid treating medium (Standard Oil Thinner #410 containing 1% by weight of Barecro Wax, melting point 200 F., produced by Barnsdale Oil Co. of Tulsa, Okla.) was pumped by means of the pump 40 from the reservoir 41 through the heat exchanger 42 wherein, by exchange with steam from the boiler 43 through line 44, the medium was heated to about 250 F. The heated treating medium was then pumped through the line 45. With the valve 46 open and the valve 47 closed, the fluid fed through the inlet lines 30 and 32 into the tank 11 and out through the apertures (not shown) in the spray pipes 25 and 29, forming the spray pattern shown in Figure 3. Inasmuch as the tank 10 was not then in use, the valves 46a and 47a were both closed. Thus the lumber was sprayed from all sides with the hot fluid, until the load of lumber was completely submerged in the treating medium, which was then continuously circulated through the tank for a period of Iabout six hours.

The fluid treating medium was circulated, and thus continuously maintained at a temperature of about 250 F., through the overflow line 50, and through the connecting lines 51, 52 and 53 to the reservoir 41. A portion of the iluid proceeded through the valve 55 and line 56, through the condenser 56a and to the still 57 wherein water driven off from the wood was taken olf overhead through the line 58 and pumped, by means of the pump 59, through the steam boiler 43. The liquid treating medium comprised the bottoms from the still and was fed through the line 60 to the reservoir.

After the six-hour treatment period, the valve 65 in the drainage line 66 was opened and all of the uid was drained from the tank into the reservoir, the pump 40 having been previously shut down. Dry steam at 250 F. was then blown through the lines 44, 68, valve 47 (how opened), and lines 30 and 32 into the tank to steam the wood for a period of about IAL hour, thereby driving off additional moisture. Following this, the valve 47 was closed, the valve 46 opened, and dry air blown from the blower 70 through the lines 30 and 32 into the tank for a period of about two hours, thus gradually reducing the temperature of the lumber and driving oi additional water vapor therefrom. During the steaming and blowing operation, the valves 55 and 65 were opened and the valve 71 was closed so that the water vapor was forced out through the lines 66 and 50, thence through the condenser 56a and thence into the still 57 for separation of residual treating medium.

The cover 13 was then removed and the load of lumber, which now had a moisture content of about 15%, was lifted out. The lumber so 'treated was fully equivalent to kiln-dried lumber from the standpoint of moisture content, evidencing less shrinkage than with kiln-dried lumber, and no weakening of the lumber occurred as a result of the treatment. Moreover, the product has excellent water-resistant properties due to the inclusion of the wax in the treating medium. The addition of the wax is not essential insofar as drying alone is concerned, and it may be omitted if desired, but the use of the wax is greatly desirable insofar as imparting water-resistance to the lumber is concerned.

The process of this invention has been applied to many varieties of lumber, including Douglas tir, redwood, Phillipine mahogany, oak, primavera rosa morada, Brazilian pine, cedar, spruce and aspen.

Having -fully described my invention, it is to be understood that I do not wish to be limited to the details set forth, but my invention is of the full scope of the appended claims.

I claim:

1. A process for treating green lumber which comprises stearning the lumber and then contacting the lumber with a water-immiscible liquid at a temperature i above about 212 F. and at normal atmospheric pressure for a suicient length of time to drive a substantial amount of water from the lumber, without appreciable absorption of said water-immiscible liquid in said lumber.

2. A process for treating green lumber which comprises steaming the lumber and then contacting the lumber with a water-immiscible liquid at a temperature between about 250 and about 450 F. and at normal atmospheric pressure for a sufficient length of time to drive a substantial amount of water from the lumber, without appreciable absorption of said water-immiscible liquid in said lumber.

3. A process for treating green lumber which comprises steaming the lumber and then contacting the lumber with a water-immiscible liquid containing about 1% by weight of a high-melting wax at a temperature above about 212 F. and at normal atmospheric pressure for a sucient length of time to drive a substantial amount of water from the lumber, without appreciable absorption of said water-immiscible liquid in said lumber.

4. A process for treating green lumber which comprises steaming the lumber and then contacting the lumber with a water-immiscible liquid containing about 1% by weight of a high-melting wax at a temperature between about 250 F. and about 450 F. and at normal atmospheric pressure for a suicient length of time to drive a substantial amount of water from the lumber, without appreciable absorption of said water-immiscible liquid in said lumber.

5. A process for treating green lumber which comprises steaming the lumber and then contacting the lumber with aA petroleum solvent at a temperature above about 212 F. and at a normal atmospheric pressure for a sucient length of time to drive a substantial amount of water from the lumber, without appreciable absorption of said petroleum solvent in said lumber.

6. A process for treating green lumber which comprises steaming the lumber and then contacting the lumber with a petroleum solvent at a temperature between about 250 and about 450 F. and at normal atmospheric pressure for a sufficient length of time to drive a substantial amount of water from the lumber, without appreciable absorption of said petroleum solvent in said lumber.

7. A process for treating green lumber which comprises steaming the lumber and then contacting the lumber with a petroleum solvent containing about 1% by weight of a high-melting wax at a temperature above about 212 F. and at normal atmospheric pressure or a suicient length of time to drive a substantial amount of water from the lumber, without appreciable absorption of said petroleum solvent in said lumber.

8. A process for treating green lumber which comprises steaming the lumber and then contacting the lumber with a petroleum solvent containing about 1% by weight of a high-melting wax at a temperature between about 250 F. and about 450 F. and at normal atmospheric pressure for a suflicient length of time to drive a substantial amount of water from the lumber, without appreciable absorption of said petroleum solvent in said lumber.

9. A process for treating green lumber which comprises steaming the lumber and then contacting the lumber with a petroleum solvent having a boiling range of 360- 450 F. at a temperature above about 212 F. and at normal atmospheric pressure for a sucient length of time to drive a substantial amount of Water from the lumber, without appreciable absorption of said pertoleum solvent in said lumber.

l0. A process for treating green lumber which comprises steaming the lumber, contacting the lumber at a temperature above about 212 F. with a petroleum solvent having a boiling range of S60-450 F., containing 6 about 1% by weight of a high-melting wax, and at normal atmospheric pressure for a suicient length of time to drive a substantial amount of water from the lumber, Without appreciable absorption of said petroleum solvent in said lumber.

1l. A process for treating green lumber which comprises steaming the lumber, then contacting the lumber with a water-immiscible liquid at a temperature above about 212 F. and at normal atmospheric pressure for a suticient length of time to drive a substantial amount of water from the lumber, without appreciable absorption of said water-immiscible liquid in said lumber removing said liquid, and steaming the lumber to remove residual vapors therefrom.

12. A process for treating .green lumber which comprises steaming the lumber, then contacting the lumber with a Water-immiscible liquid at a temperature above about 212 F. and at normal atmospheric pressure for a sucient length of time to drive a substantial amount of water from the lumber, without appreciable absorption of said water-immiscible liquid in said lumber, removing said liquid, steaming the lumber and then blowing air thereover to remove residual water vapors therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 686,582 Brinkerhoff Nov. 12, 1901 990,246 Fetterman Apr. 25, 1911 1,648,294 Coolidge Nov. 8, 1927 1,967,990 Edwards July 24, 1934 2,060,902 Stamm Nov. 17, 1936 2,137,404 Hollerer Nov. 22, 1938 2,507,190 Barksdale May 9, 1950

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US686582 *Aug 28, 1901Nov 12, 1901Henry R BrinkerhoffWaterproofed wood and method of making same.
US990246 *May 18, 1910Apr 25, 1911John L FettermanMethod of seasoning wood.
US1648294 *Jan 26, 1926Nov 8, 1927Montan IncProcess of impregnating wood
US1967990 *Mar 30, 1933Jul 24, 1934Peter C ReillyOil impregnation of wood
US2060902 *May 9, 1934Nov 17, 1936Stamm Alfred JoaquinMethod for simultaneously seasoning and treating water-swollen fibrous materials
US2137404 *Jan 13, 1937Nov 22, 1938Wacker Chemie GmbhDrying process
US2507190 *Jan 18, 1946May 9, 1950Barksdale Sr Beverly EProcess for drying lumber
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3199211 *Feb 16, 1962Aug 10, 1965Koppers Co IncMethod of preseasoning green or partially seasoned wood
US3205589 *Sep 27, 1961Sep 14, 1965West Wood Proc CorpProcess of drying wood by oil immersion and vacuum treatment to selected moisture content with oil recovery
US3278377 *Mar 12, 1964Oct 11, 1966Shell Oil CoWood preservative composition
US4464848 *Sep 22, 1982Aug 14, 1984Kenogard AbProcess for treating wood
US5176475 *Jan 12, 1990Jan 5, 1993Abb Stal AbTransfer chambers for the conveyor in a pneumatic transport system
US7963048 *Sep 25, 2006Jun 21, 2011Pollard Levi ADual path kiln
US8201501Sep 4, 2009Jun 19, 2012Tinsley Douglas MDual path kiln improvement
US8342102May 9, 2012Jan 1, 2013Douglas M TinsleyDual path kiln improvement
US8637089Sep 26, 2006Jan 28, 2014Osmose, Inc.Micronized wood preservative formulations
Classifications
U.S. Classification34/351
International ClassificationF26B5/00
Cooperative ClassificationF26B5/005
European ClassificationF26B5/00B