US1253667A - Process of preserving wood. - Google Patents

Description

W. A. CECIL. PROCESS FOR PRESERVING woon.

APPLICATION FILED SEPT. 25, I9I6.

7 II I I MII .I I -..I IIIIIIII III. IIIIHIIIIWII II 5 MWHHHWIIHIHIIII ATTORNEY WITNESSES W. A. CECIL.

PROCESS FOR PRESERVING woon'I APPLICATION FILED SEPT.25, 1916.

l ,.@g Patented Jan. 15, 1918.

2 SHEETS-SHEET 2- INVENTOR ATTORNEY nr sas Iranian orario,

WILLIAM A.' onen., or nvansviLLE, munita, AssIGNoR on ONE-Herr 'ro aonnnfr n.

WILLIAMS, or nvnlvsvrLLE, INDIANA. f i

PROCESS FOR RESERVING WOOD.

l Application led S)eptember 25, 1916. Serial No. 122,125. l

To all whom t may concern:

, Be it known that l, WILLIAM A. Cnam, a citizen of the United States, residing at Evansville, in the county of Vanderburg and State of Indiana, have invented'certain new and useful Improvements in Processes for Preserving Wood, of which the followin is a specification.

y invention relates to a new and improved method of preserving wood by impregnating the Ysame with preservative fluids, and especially to a new and improved process for preserving railroad cross ties, pilings, structural and mine timbers, street paving blocks, etc., in which any preservative fluids may be used either singly or in admixture regardless of di'erence of speciic gravities, while the pressureand the temperature of the fluids in the impregnating cylinder or retort are automatically controlle'd by means of a system ofjcirculating pipes, and specially constructed automatically and mechanically operated valves which are so arranged that a uniform rise of pressure of the iuid in the impregnating cyllnder is accomplished, this process being in part divisional matter from the application which eventuated into Patent No. 1,178,132, granted to me April 4, 1916,

As is well known, the heretofore generally used method of wood preservation by injecting chemical preservatives into the wood has consisted,` of placing the Wood to be treated in a .receptacle or retort capable of being closed air and liquid tight. lf the wood belnot sulhciently dry to permit of its dit thorough saturation without steaming, steam is admitted to the retort to accomplish the desired steaming and is maintained until the temperature attains the desired point, generally about 250 degrees Fah.

This temperature is fmaintained until the.

wood is heated sufficiently to permit the moisture being drawn from the pores and cells thereof in the form of vapor, and by vacuum, a vacuum pump being coupled with the retort and 'started subsequent to the closing of thev steam supply. This vacuum pump is operated until a vacuum equal to 22 to 25 inches of mercury at sea level is drawn, this vacuum being maintained for thirty minutes to one hour, or for any time that the operator judges necessary to draw a sufficient amount of moisturefrom the wood to allow injection of the required volume of the preservative fluid.

Next, without admitting air to the retort or otherwise breaking the vacuum, the preservati-ve fluid is admitted to the retort until the same is filled and all of the wood completely submerged. The `outlet valves are maintained closed and more liquid is pumped into the retort so that the hydrostatic pressure in the retort is raised and thus the liquid forced into the wood. In some cases a separate closed tank or receiver is connected by a large pipe to the retort. The general practice has been to .place this receiver so that when the retort is full of the fluid, the level of the fluid in the receiver or tank is somewhat below the top, thus leaving an empty space into which air is pumped under pressure. As the pressure of the air is increased the pressure upon the liquid is communicated from the closed tank or receiver through the connecting pipe to the fluid in the retort until the required pressure is attained in the retort; gages or recording instruments generally being provided to determine the exact Working conditions, and the pressure being maintained until a sufficient amount of the preservative is forced into the wood.

lin the use of the above outlined processes, there has never been any'circulation of the preservative fluids in the retort except for the purpose of maintaining emulsions of more orsless immiscible fluids, such as zinc, chlorid and creosote, but the liquids have in all cases been permitted to lie quiet and in a dead state in the retort while maintained under pressure; By this maintenance of the dead pressure within the retort, and through 'the consequent lack of movement and'circulation of the uid, the liquid or treating fluidvaries in its temperature in Jche various parts of the retort, and especially in eX- posed locationsl the fluid becomes too cold for proper penetration, thus causing a different absorption of the fluid by` the timber in di'erent parts of the retort even when tlie timber is of the same species.

Further than this, to accomplish the most successful treatment of the timber, the pressure in the retort is to be raised at a uniform rate and the rapidity of increase of titi till

pressure in the retort should only be such as will compensate for the increase of the resistance to the preservative fluid as the same penetrates into the wood and through the gradual filling of the pores or cells .sure is attained. To fulfil this requirement,

it has heretofore been necessary for the operator to stand at the pump almost continually during the period of raising the pressure, and, at such times as he judged proper, to increase the pressure by increasing the speed of the pump, or where pneumatic' pressure, instead of hydraulic, is used the pressure has been controlled by carefully regulating the amount of air admitted to the air receiver, and then again under some circumstances the desired rises in pressure have been accomplished by bringing the pressure up in steps of 25 poundsat a time and practically every fifteen minutes. All of these methods are unsatisfactory as they depend entirely upon vthe attention of and manual manipulation by the operator, and any neglect or failure to observe the niceties of manipulation is conducive to erratic penetration. Also, it is under some circumstances requiredathat preservative chemicals such coal-tar creosote a1id?refined coal-A tar, coal-tar creosote and water gas tar, coaltar creosote and water gas creosote, coaltar creosote and crude oil, coal-tar creosote and zinc chlorid solution, and etc. be used and except in the case of emulsions of creosote and zinc chlorid solutions, no attempt has heretofore been made to assure perfectmixture of the preservative chemicals. As the result, it is by no means certain that the different ingredients. will remain mixed in the proper solution so that' the proper proportion of each chemical will be carried into the pores of the `Wood but the natural tend.

ency is for the chemicals to separate and for one chemical to have a better penetration than the remaining chemical or chemicals of the solution, and here it might be set forth that the proper solution andan equal distribution of -all of the ingredients throughout the entire -volume of liquid which will insure a proper penetration of the solution can be attained and maintained only by circulation. r i g Again, it is not possible to entirely eX- haust the air from the cells of the wood and as the .preservative fluid is forced into the.

porcs and cells of the wood this air is liberated as is also the air which is used in the mixture of the emulsions of preservative fluid, which are fol the most part aerated mixtures, as the fluid is forced into the wood.

In all processes wherein dead pressures are maintained or circulation is accomplished by means of a closedlcircuit apparatus, air must remain in the retort and' it will of course be readilyapparent that this presence of air in the retort is detrimental to uniform absorption as it interferes with the homogeneity of mixtures of preservatives when circulation is maintained by means of closed circuit apparatus, and in some instances the volume of air may' become'sufliciently great to displace the fluid in the retort to such an extent that some of the wood on the top of the charge in the retort may not be entirely submerged at all times.

With the above in mind, it is a purpose of my invention to overcome the above named and other faults of processes heretofore used, by employing a process which contemplates an open circuit circulation of the treating fluid andthe automatic control'of the pressure of the preserving fiuid, while at the same time. permitting the use of mixtures and emulsions of preservatives of immiscible chemicals and maintain the same in the proper condition even though they be aerated mixtures, allowing the successful use of the same by permitting the airfrom the mixtures `and any air which may be forced out of the wood to escape.

It will be understood that a number of variations might be resorted to in the apparatus to be employed in accomplishing my process, but I have endeavored to illustrate only one possible form which will permit the accomplishment of the various steps of the treating action in the proper cycles and intervals.

In the drawings: Y Figure 1 is a schematic view showing the retorts together with the liquid supply tank and the circulating pipes to give the general arrangement of the parts of the apparatus, and with section. f

Fig. 2`is'a detail view to illustrate the automatic valve and to show one forni of power and gear means which might be employed in the actuation of the same.

Fig. 3 is a view in elevation to better yillustrate the structure shown in Fig. 2.

Fig. 4 is an enlarged detail sectional view to better illustrate the structureof the automatic pressureyalves.. 1

Fig. 5 is a detail .,view showing a dia,- phragm pressure switch which might be used in connection with an electric motor imparting. movement to the mechanically operated valve and which switch will automatically stop the motor when the maximum pressure as desired is attained in the retort.

.The liquid supply tank l, which is designed to contain the supply of preservative liquid which is being constantly circulated portions shown in vertical of treating timber therein, has a suitable agitator located therein to keep the supply of' liquid constantly agitated and mixed.

This agitator may be of any desired form but in the present instance is illustrated as an air supply pipe 3, which is run/ to the bottom of the liquid supply tank 1, and is extended along the bottom thereof where it is provided with perforations as indicated at 4, these perforations being preferably extended throughout thecentire length of the portion of the pipe which is disposed adjacent to the bottom of the supply tank andto thus discharge air through substantially the entire volume of liquid and disturb the ingredients of the greatest specific gravity which Will have settled to the bottom of this tank, thus causing these ingredients to move in an upward current through the ingredients of a least specific gravity which vhave a tendency to rise to the top of the mixture of fluid. By this arrangement of the parts, the entire body of fluid is constantly agitated and the desired mixture and homogeneity of the same is maintained. It is obvious that this agitator will only be needed when the preservative fluid is composed of two or more preservatives of a more or less immiscible nature which are to be mixed to form the preservative fluid, and l therefore desire to limit its use to the conditions under which it is needed.

The retort 2, will generally be of cylindrical form but may be of any` desired shape and of dimensions to suit the particular use, this retort being provided with one open end, and a door 5 being adapted to be closed over the open end and held liquid and air tight bysecuring bolts or clamps 6. A fill and return pipe 7 connects with the bottom of the liquid supply tank 1, and at A its opposite end is connected with the retort 2 at a point low down on the sides thereof. VA. suitable valve 8, preferably of the gate type, is provided to control the opening through this pipe 7, and the pipe is intended only to accomplish the initial filling of the retort 2 after the timber to be treated has been placed therein and the door 5 has been secured in place, and to permit the return of the preservative fluid from this retort when the treating action has ceased and it is desired to empty the retort so that the door 5 can be opened to permit the removal of the treated timber and the placing of untreated timber in the retort to be impregnated. t

A pressure pump 9 is installed as a part of the apparatus, and while 1 have herein shown one specific form of pressure pump, and more particularly 'a pump of the piston type, 1 do not Wish to limit myself to any particular pump but desire to have it understood that any kind of pump or anyother suitable means which will supply liquid under pressure may be used, the form of this part being that which appears to be more suitable for plant conditions under which it will operate. A- pipe 10 extendsy from the lower part of the liquid supply tank 1 to the pump 9, `and a pipe 11 is connected from thepump to the, retort 2, it being preferable that the pipe 11 be extended through the bottom of the retort 2 and that branch discharge pipes 12, each provided with a plurality of openings 13, be connected with this pipe 11 to extend lthroughout the lengthJ of the retort 2 and to thus insure an even discharge of the liquid to all parts of the retort. A liquid outlet pipe 14 has a plurality of branches and these branches are each connected with the retort 2 in the upper part thereof to thus permit discharge from the retort substantially uniformly from all parts thereof, an`

automatic pressure valve 15 being connected in the vdischarge from the outlet pi e 14, and a return pipe 16 being connecte with the automatic pressure valve 15 and led to the liquid supply tank 1 to thus allow discharge of the liquid from the retort through the automatic pressure valve 15 arid` back to the liquid supply tank. A branch pipe 17 is connected to the outlet pipe 14C at one end, and at the opposite end this branch pipe is connected with the return pipe 16, or the y.pipe 17 might be lconnected directly with the liquid supply tank to discharge into the bottom thereof, as local conditions might require. A mechanically operated valve 18 having a specially constructed passage therethrough is mounted in this pipe 17 to control the passage of Huid thereing constantly supplied by the pump 9, this regulation and control of the pressure being accomplished by a gradual throttling of the passage through the valve. n

A pipe 20 controlledby the valve 19 1s connected in the pipepll at `one end, and its opposite end is connected with the boiler supplying steam to the pump 9, or with any other suitable means' to 'supply steam through this pipe and through the plurality of openings 13 in the branch discharge pipe 12, the purpose ofrthis ste/am being to dry the Jsap or other smoisture out nof Jthe pores of the wood preparatory to the impregnating process. l

- A pipe 21 is. connected with the upper side of the retort F2, and a branch pipe 22 is connected with this pipe 21 and isextended to connect with any suitable source of compressed a/ir su ply, the valveA 23 being pro vided to contr l the passage of fluid through this pipe 22. A second branch pipe 24, controlled by a valve 25, is connected with a vacuum pump or other suitable means which may be set in operation to exhaust the iiid contents of the retort and to thus extract the moisture, air and steam from the retort, just prior to the introduction of the impregnating liquid thereinto.

The pressure control valve 18, as shown in detail in Figs. 2 and 3, may be a gatpv valve of the non-rising' stenf type with a passage through the same so proportioned that when opened to its full extent substantially all the fluid discharged into the retort 2 by the pump 9 will pass through the valve.

l ber will be extended over or withdrawn from'the passage. A relatively large worm gear 30 is connected on this stem 29 and a transmission shaft 31 has a worm 32 mounted thereon to mesh withv'theworm gear 30.

A worm gear 32 is carried on the opposite p end of the transmission shaft 31 and a motor 33 has a worm 34 on the shaft thereof meshingwith this worm gear 32 so that as the motor is operated rotary motion will be transmitted to the stem 29' at aA greatly reduced speed over the speed of rotation of the motor shaft. While I have shown one form of operating means for the valve 18, it is obvious however, that many forms of gear and power may be used to operate this valve, and I do not wish to limit myself to any specific gear or power but desire to use any form dot power availa le or any geai that may be needed in any specific instance, or evenyf occasion requires, to operate valve 18 by hand.

The automatic pressure release valve shown in detail i-n Flg. 4, comprises the case Vwhich has the valve proper 26, mounted therein between the connection of pipe 14 provided to form an outlet from the impregnating cylinder or retort 2, and the pipe 16 which returns to the liquid supply tank 1, and a spring 27 is provided to bear against this valve 26 to exert pressure to oppose the opening of this valve and consequently to oppose the passage of liquid from the outlet pipe 14' to the return vpipe 16. While the spring 27 is illustrated as a simple coilspring around the stem of the valve 26 to bear. against the reverseside thereof and against the head of the case, it will be understood. that by. changing this spring and substituting therefor a spring of a lighter or heavier gage, the valve 26 can be regulated to open at varied pressures, and here it might also be stated that it might be dewilli1 sirable to, in some, uses, provide means whereby the pressure of uthe spring 27 may be adjusted to accommodate various operating conditions and to give various settings thereto without the necessity of dismantling the parts to insert a new spring.

As is hereinbefore set forth, I have provided a motor 33 to control the valve 18, and the circuit wires from this motor are led to a generator 35, or to any other suitable source of electrical energy. Not only is it desirable that the valve'18 be gradually closed to. consequently gradually increase the pressure within the retort 2, but also it is desirable that some means be provided to automatically cut out the connection to the motor so that the valve will not be given further actuation after a desired maximum pressure has been attained within the retort, and to accomplish this purpose I provide the diaphragm pressure switch, as better shown in Fig. 5, which switch 36 is connected in one of the circuit wires to the motor 33 and is designed to automatically stop the motor when the maximum retort pressure has beenaccomplished. A pipe 37 is vled from the retort chamber to*t connect with the diaphragm chamber 38, and in this way when pressure sufficiently strong to overcome the pressure of the spring 39 is accomplished in the retort, this pressure will be transferred through the pipe 37 to `the diaphragm chamber 38 and in consequence the switch arm 4:0 will be swung outwardly to break the switch connection.

In the accomplishment of the process, the

timber, ties, poles, paving blocks, etc., are

loaded on trucks and run into the retort, or are otherwise placed therein, and the doorl 5 is closed into place and is secured to make the retort 'air and liquid tight. Steam is admitted through the valve 19 and the pipe 20, passes through pipe 11 into branch pipes 12y and is uniformly distributed throughout the interior of the retort 2y through the openings 13. After the wood in the retort 2 is heatedto the proper temperature, generally about 250 degrees Fah., for the necessary time, generally from one to five hours, the valve 19 is closed to shut off the supply of steam and the steam contained in the retort 2 is blown away until the pressure in the retort is at or nearly at atmospheric pressure. The blow-oil", not shown, is then closed and valve 25 in pipe-24 which leads to the vacuum pumpf is opened, thus permitting the air, moisture, and steam within the retort to be drawn out ,of the retort 2 and passed away through the vacuum pump. This operation extracts the air and moisture from the wood leaving the cells and pores thereof open and in proper condition to absorb the preserving liquid.

After a' vacuum of from ,22 to 25I or more inches ofa mercury has. been maintained in the interior of the retort 2, for under oraaaaeev dinary working conditions, from forty minfutes to one hour, the valve 8 in the pipe 7 is opened and liquid flows from the supply tank l'into the exhausted retort 2 to entirely fill this retort and completely submerge the Wood contained therein to be treated. rllhe valve 25 in the pipe 24 is then closed to cut oli communication from the vacuum pump, valve 8 is closed to cut ofi' communication from the liquid supply tank 1 to the retort 2 through the valve 7 valve 18 is opened, and pump 9 is started in operation. The mechanical arrangement Which operates -valve 18 is then set in operation so that the valve will be' gradually closed, or `care is taken by thetoperator to manually manipulate this valve to accomplish the gradual closing of the passage therethrough. The pump 9 takes liquid through the pipe 10 from the liquid supply tank 1, and forces this liquid through pipe 11 to?be discharged through .the openings 13 into all parts of the retort. As the retort has been filled through pipe 7 the further supply of liquid thereto through the pipe 11 causes the impregnating liquid to be forced through the retort 2 out through the pluralit of `branches in the pipe 14, thence throug the pipe 17 and valve 18 back to the liquidsup ply tank 1, the pressure of the spring 'in the valve 15 acting to close comlnunication there- 'through while the valve 18 is 'still open. As the valve 18 is gradually closed, the pressurein the ret/ort is raised to the maximum pressure as desired.

It is preferable that the passage through valve 18 be made of triangular shape, as shown in Fig. 2, for the reason that when the pump is started, cir ulation begins gud the full opening throu h'the valve 18 allows the full volume o liquid sup lied to the retort 2 to pass freely through t e valve 18. As the area of outlet through valve.A

18 is gradually restricted due to the mecharical closing of the valve 18, there is `a corresponding rise of pressure in the retort 2, since the velocity of the How of theliquid is increased about as the square of its pressure. Therefore, to obviate the necessity of changing the speed of the gearing from the motor at frequent intervals to render the raising of the pressure in the retort 2 uniform and automatic, it is necessary that the valve moving ata uniform speed, re-

strict a relatively larger' area of opening atv the beginning of the operation and a gradually decreasing area as the velocity of liquid How increases, due t the increasing pressure in the retort 2, an hence I make use of the triangular outlet.

'When the maximum pressure in the retort 2 is attained, the liquid pressure acting on the diaphragm of the automatic switch 36 forces the switch arm 40 open, breaking the ttf circuit contact, and the motor is thus automatically stopped. VrIhe valve 18 will, by

matic switch has been set.

The pressure release valve 15 is set to discharge at or near the maximum pressure at which the retort 2 is operated, and thus act as a safety valve to relieve any excess of Huid over the lvolume that ,will be discharged through the restricted opening of the valve 18, which increases in the' volume of fluid `mayxat times be caused by variations in the speed of operation of the pump 9, and thus all danger of excessive or over pressure is obviated.

While I have herein shown one specific form of apparatus which is adaptable for the accomplishment of the process, and an apparatus which Will carry out the steps thereof in proper order, it willbe understood that changesv in the apparatus may be made and may even be desirable under-,various operating conditions, therefore, I do not Wish to limit myself to any particular arrangement of the apparatus, and further do not Wish to be limited.A in so far as the process is concerned, except for such limitations as the claims may impart.

I claim: t

1. rl`he method of preserving Wood which consists in treating the Wood by the circula,- tion of a preservative fluid in and through a retort in which the wood is placed and in and through an open circuit piping system to thus provide for elimination of free air from the retort.

2. The method of impregnating Wood which consists in placing the Wood in a container, filling the container With preservative li uid, injectingv liquid into the container to e equally supplied in all parts, and discharging liquld from\-the container at diderent oints to secure a flow through and circulation in all parts of the retort.

3. rllfhe method of impregnating Wood which consists in placing the Wood in a container, injecting liquid into the container at the bottom thereofto be equally supplied in all parts, discharging liquid from the container at the top thereof and at different points to secure an equal flow through and circulation in all parts of the container, and constricting the dischargeV to raise the pressure of liquid Within the container. w

4. rIlhe method of impregnating Wood which consists in placing the wood in a retort, filling the retort with preservative 'liquid taken4 from a liquid supply, maintalning a constant supply and flow of liquid sure Will be maintained substantially con-A stant at the maximum forl which the auto under pressure into all parts of the retort, discharging liquid from the retort at dif- 'ferent points to secure an equal How through and circulation in all parts of the retort, conductingthe discharge liquid to the liquid supply, and agitating the liquid at the supply to be reinjected into the retort.

5. The method of impregnating'vvood -Which consists in placing the Wood in a retort, filling the retort With preservative liquid taken from a liquid supply, maintaining a constant supply and flow of liquid under pressure into all parts of the retort,

discharging liquid from the retort at`dif-I pressure within the retort to a maximum, and maintaining this maximum pressure within .the retort for a period of time to securevproper penetration of the liquid into the Wood. f

6. The method of-preserving Wood by the use of a preservative fluid constituting a plurality of chemical lngredients, which consists in submerging the Wood in the iuid mixture and maintaining. a continuous iow of the fluid mixture from and to a fluid supply, and constantly mixing the preservative iuid at the fluid supply.

In testimony whereof I affix my signature in presence of two Witnesses.

, vv. A. cEoIL.

Witnesses:

ALLEN DEAN, l RAYMOND MEYER.

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