Improvements in the Process of, and Apparatus for Preserving Wood.
Year: 1898

page_text: Date of Application, 16th July, 1898
Complete Specification Left, 30th Jan., 1899-Accepted, 20th May, 1899
PROVISIONAL SPECIFICATION.
Improvements in the Process of, and Apparatus for Preserving
Wood.
We, CARL TSCHURL, of VI Liniengasse 14, Vienna, Austria, Manufacturer, and CARL
PETRASCHEK, of I Hegelgasse 6, Vienna, aforesaid, Councillor, do hereby declare the
nature of this invention to be as follows:-
According to the usual methods of preserving wood, for the purpose of rendering it
as much as possible proof against chemical and mechanical action, and of rendering it
permanently unchangeable, the wood is first subjected to a lixiviating or leaching
operation, then to a drying operation, and is finally impregnated with antiseptic
agent such as tar. These three operations are effected successively in a vessel called
the "mummifying " boiler which is for this purpose combined with a steam boiler, a
superheater, a tar boiler, and the necessary appliances such as the air pump and
condenser to constitute the plant or apparatus.
This process has numerous drawbacks, which consist mainly in that the wood to be
preserved is not sufficently dried before being placed in the mummifying boiler,
and that, after having been preserved, the wood is brought out of the apparatus into
the open air without being previously cooled. The process of preservation is thus
considerably retarded, especially when wet or frozen wood is to be impregnated, and,
furthermore the direct bringing of the impregnated hot wood into the open air is a
great drawback.
Now this invention has for object to shorten the duration of the preserving process
as much as possible and to perfect the said process in such a manner that all injurious
effects of the moisture originally contained in the wood as also those of the atmosphere
or open air coming in contact with the impregnated wood are obviated, and to produce
a material which will be equally useful as building timber, or wood to be worked
up by tools, and which will effectively resist the influences of moisture, variation of
temperature and the like. This is effected most efficiently by a process consisting of
operations that are carried out simultaneously in three chambers, the necessary
operations for preserving the wood comprising leaching, drying and tarring, being
carried out in conjunction with a preliminary heating and a preliminary drying or
cooling of the material, whilst the said operations can be carried out, either each in
a particular one of the three chambers, or in varying succession in each of the same.
In both cases a continual working can be effected, which renders the process con-
siderably quicker and more systematic, and also in consequence of the preliminary
drying and subsequent cooling, provides the most favourable conditions for the
efficient carrying out of the preserving process.
In the former case the preliminary drying and cooling chambers are employed
alternately, the fresh wood being introduced into the one chamber and the mummified
wood into the other chamber, so that, by suitable operation of flap valves between the
chambers, an exchange of temperature and air can be effected.
In the latter case, there are provided in the place of these chambers, and in addition
to the boiler serving for the muinmifying process, two other similar boilers, and the
three boilers are worked simultaneously in such wise that the drying process takes

page_text: closing means, the several cylinders will allow of carrying out each of the three
operations of the process in succession.
The accompanying drawings illustrate by way of example apparatus for carrying
out the process with drying chambers.
Fig. 1 is a vertical cross section,
Fig. 2 a horizontal section on the line x-x and
Fig. 3 a similar section on the line y-y.
Fig. 4 is a side elevation and vertical section of the apparatus.
aa are the heating devices which serve to heat the fresh air supplied through
passages bb; the air which becomes heated therein passes through the vertical
passages e c through openings e e and el el or ff and f¹ f1 (adapted to be closed by
means of valves) into the chambers d¹ and d². By suitably setting the valves
of these openings the heated air can be passed into each of the two chambers
either only near the floor or only near the ceiling, or into the lower part of one
chamber and into the upper part of the other chamber, or it can be admitted into the
lower part of one chamber and be allowed to flow through the upper apertures
into the other chamber. Each chamber comprises two exit passages h, h, and h¹ h¹
which are each provided above the floor and below the ceiling with an outlet suction
opening and which can be closed by means of valves. The passages h h¹
deliver into funnels through which the smoke flues of the heating devices pass so
that there is thereby produced a powerful suction of the moist air contained in the
chainbers. By means of slide valves m inserted between the suction passages and
the funnels the suction passages can be entirely shut off.
Between the passages c c
there is situated a vertically arranged fresh air passage n, which supplies cold air
into one or both chambers, through apertures s that can be closed by means of slide
valves. In each of the chambers and d², that can be closed by means of double
doors o, p, there steam is delivered by a steam pipe q.
For the purpose of preliminary heating and of cooling the wood, which operations
may be carried out alternately in the two chambers, the chamber d¹ is charged for
example with fresh wood and the chamber d² with mummified wood, which latter is
charged in the well known manner upon trucks that are run into the impregnating
boilers and that are pushed along rails into the chamber. When the double doors
and the sliding valves of the fresh air channels b have been closed, the valves of the
warm air passages c, c, are set in such a manner that the lower apertures e, e¹ are
closed and the upper apertures f f are opened. The sliding valves m for the
chamber dare closed and the slide valves for the chamber d' are opened. Further,
the valves for the suction aperture of the passage hare set so that the air passing
out of the chamber can pass through the lower apertures i into the said passages
and through the funnel k into the open air. In the fresh air passage n, the slide
valve of one opening & is open towards the chamber d², whilst the other slide valve is
closed to the chamber d¹. The chamber d² which was previously charged with wood
for preliminary heating has a temperature of about 100° C.; whilst the chamber d
which was charged with wood to be cooled is completely cooled.
In consequence of the described position of the sliding valves and dampers or flap
valves, air is drawn through and h from the chamber d, and in the latter a rare-
faction of the air will take place in consequence of which hot air will pass from
chamber d² through the upper apertures f¹, f¹, and f, f into the said chamber d¹.
Thus in the latter the wood is heated, whilst the air becomes saturated with
moisture. Cold air now enters through the fresh air passage into the chamber 2
and there produces a gradual cooling of the hot preserved wood. Thus in this pro-
cess, the heat which would otherwise be lost by the cooling is utilized for the pre-
liminary heating of the fresh wood.
When the external air or atmosphere is very cold, then, for the purpose of
preventing too rapid cooling, previously heated air from the heating devices a may

page_text: be admitted in adjustable quantities which is effected by suitably setting the slide
valves and flap valves.
The heating of one chamber and the simultaneous cooling of the other chamber
continues until the same temperature obtains in both chambers. Then the com-
munications between the two chambers are interrupted by closing the apertures f¹ fl
of the chamber d², and opening the respective slide valves m in the suction funnel k,
and also the flap valves of the apertures i, whereby the air is allowed to escape from
the chamber d into the open air. When the sliding valve s is opened, fresh air enters
into this chamber from the passage and produces the complete cooling of the pre-
served wood.
For the chamber d¹ the flap valves of the apertures e or f of the passages c, c,
are set in such a manner that either the lower openings e or the upper openings f
are opened. Correspondingly, the flaps of the apertures i¹ in the exit
passages h, h, are set in the reverse manner, so that the air passes through the
chamber from the bottom to the top or from the top to the bottom. The conse-
quence of this movement of the air is a further preliminary heating and evaporation
which is continued until the wood has reached the dryness which is necessary for the
subsequent preserving process, and a temperature of 100° C.
The chamber d' is now emptied, and its wood is placed into the cylinder for the
purpose of preserving, whilst the wood which has just been preserved in the latter, is
placed in the chamber d¹ which now becomes the cooling chamber, whilst the freshly
charged chamber d serves as the preliminary heating chamber, for which purpose
the slide valves and flaps must be correspondingly reversed. In consequence of this
alternate working in both chambers, it is possible to carry on the operation
continuously.
The preliminary heating may be accelerated by the admission of steam through
the pipes q, and a desired degree of dryness may be produced.
If, instead of the drying chambers, two impregnating boilers are employed, then
the working with the three boilers or cylinders is advantageously carried on as
follows:-
The first cylinder is charged with fresh wood which is heated preliminarily,
whilst, at the same time previously heated wood is being preserved in the second
cylinder and the wood which is already preserved is being cooled in the third
cylinder.
After complete cooling, the third cylinder is emptied, charged with fresh material,
and then acts as a preliminary heating cylinder. After the preliminary heating has
been completed in the first cylinder, the said first cylinder is employed for preserving
and the second cylinder, in which wood has been preserved now serves as a cooling
cylinder. In this way the working may be rendered continuous by a constant
suitable change in the order of using the cylinders.
For the purpose of passing steam and hot air from one cylinder into the other, the
cylinders are connected together by pipes and are arranged to be shut off from one
another, by means of slide valves and flap valves, or other closing devices, so that the
heat is most favourably utilized. The air required for the preliminary heating and
for the drying may be heated either in a steam superheater or in a special heating
apparatus, and may be introduced by means of fans or natural draught into
the cylinders. The spent air can be exhausted from the cylinders by means of
the existing ejectors, air pumps, or by specially provided exhaustors. The steam
generator and the superheater are preferably combined in one apparatus in such a
imanner that the boiler furnace gases give up their heat, either to the boiler only or
to the superheater only, or first to the steam boiler, and then to the super-
heater.
When using three cylinders, the vapours escaping during the preserving operation
may be led into the cylinder that serves to effect the preliminary heating, whereby a
further more advantageous utilization of the fuel is effected.
In both arrangements of apparatus, it is advantageous to provide the preserving
cylinder, or it may be the three cylinders, with a double jacket, into which air or

page_text: superheated steam can be admitted, whereby it is rendered very easy to maintain
constant the temperature necessary for the several processes that take place which is
of great importance, especially as regards the emptying of the cylinder which takes
place prior to the tarring operation.
1000
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in the Process of, and Apparatus for Preserving
Wood.
We, CARL TSCHURL, of VI Liniengasse 14, Vienna, Austria, Manufacturer, and
CARL PETRASCHEK, of 1 Hegelgasse 6, Vienna, aforesaid, Councillor, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
According to the usual methods of preserving wood for the purpose of rendering
it as much as possible proof against chemical and mechanical action, and of
rendering it permanently unchangeable, the wood is first subjected to a lixiviating
or leaching operation, then to a drying operation, and is finally impregnated with
antiseptic agents such as tar. These three operations are effected successively in a
vessel called the "mummifying" boiler which is for this purpose combined with a
steam boiler, a superheater, a tar boiler, and other appliances (such as the air pump
and condenser) necessary to constitute the plant or apparatus.
This process has numerous drawbacks, which consist mainly in that the wood
to be preserved is not sufficiently dried before being placed in the mummifying
boiler, and that, after having been preserved, the wood is brought out of the
apparatus into the open air without being previously cooled. The process of
preservation is thus considerably retarded, especially when wet or frozen wood is to
be impregnated, and, furthermore, the direct bringing of the impregnated hot
wood into the open air is a great drawback.
.
Now this invention has for object to shorten the duration of the preserving
process as much as possible and to perfect the said process in such a manner as
to obviate all injurious effects of the moisture originally contained in the wood
as also those of the atmosphere or open air coming in contact with the impregnated
wood, and to produce a material which will be equally useful as building timber,
or wood to be worked up by tools, and which will effectively resist the influences
of moisture, variation of temperature and the like.
This is effected most efficiently by a process consisting of operations that are carried
out simultaneously in three chambers, the necessary operations for preserving the
wood, comprising leaching, drying and tarring, being carried out in conjunction with
a preliminary heating and a preliminary drying or cooling of the material, whilst the
said operations can be carried out, either each in a particular one of the three
chambers, or in varying succession in each of the same. In both cases a continual
working can be effected, which renders the process considerably quicker and more
systematic, and also in consequence of the preliminary drying and subsequent
cooling, provides the most favourable conditions for the efficient carrying out of the
preserving process.
In the former case the preliminary drying and cooling chambers are employed
alternately, the fresh wood being introduced into the one chamber and the muminified

page_text: wood into the other chamber, so that, by the suitable operation of flap valves het ween
the chambers, an exchange of temperature and air can be effected.
In the latter case, there are provide in the place of these chambers, and in addition
to the boiler serving for the mummifying process, two other similar boilers, and the
three boilers are worked simultaneously in such wise that the drying process takes
place in one boiler, the preserving process proper in the second boiler, and the cooling
in the third boiler, the arrangement being such that, by reversing the valves, or other
closing means, the several cylinders will allow of carrying out each of the three
operations of the process in succession.
The drawings accompanying the Provisional Specification illustrate, by way of
example, apparatus for carrying out the process with drying chambers.
Fig. 1 is a vertical cross section.
Fig. 2 a horizontal section, on the line x-x, and
Fig. 3 a similar section on the line y-y.
Fig. 4 is a side elevation of the apparatus, one half of the figure being a vertical
section.
a, a are the heating devices which serve to heat the fresh air supplied through
passages b, b; the air which becomes heated therein passes through the vertical
passages c, c through openings e, e and el, el or f, f and f, f (adapted to be closed by
ineans of valves or dampers) into the chambers and d². By suitably setting the
valves of these openings the heated air can be passed into each of the two chambers
either only near the floor or only near the ceiling, or into the lower part of one
chamber and into the upper part of the other chamber, or it can be admitted into the
lower part of one chamber and be allowed to flow through the upper apertures into
the other chamber. Each chamber comprises two exit passages h, h and h¹, h¹ which
are each provided above the floor and below the ceiling with an outlet suction
opening, and ¹, which can be closed by means of valves or dampers. The
passages h, h¹ deliver into funnels through which the smoke flues of the heating
devices pass so that there is thereby produced a powerful suction of the moist air
contained in the chambers. By means of slide valves or dampers m inserted between
the suction passages of the funnels, the suction passages can be entirely shut off.
Between the passages c, c there is situated a vertically arranged fresh air passagen,
which supplies cold air into one or both chambers, through apertures 8 that can be
closed by means of slide valves or dampers. In each of the chambers and d²
which can be closed by means of double doors o, p, steam is delivered by a steam
pipe q.
For the purpose of preliminary heating and of cooling the wood, which operations
may be carried out alternately in the two chambers, the chamber is charged for
example with fresh wood and the chamber d² with mummified wood, which latter is
charged in the well-known manner upon trucks that are run into the impregnating
boilers and that are pushed along rails into the chamber. When the double doors
and the sliding valves of the fresh air channels b have been closed, the valves of the
warm air passages c, e are set in such a manner that the lower apertures e, e¹ are
closed and the upper apertures f, f¹ are opened. The sliding valves m for the
chamber d² are closed and the slide valves for the chamber are opened. Further,
the valves for the suction apertures i, i¹ of the passages h are set so that the air
passing out of the chamber d¹ can pass through the lower apertures into the said
passages and through the funnel : into the open air. In the fresh air passage n, the
slide valve of one opening 8 is open towards the chamber d, whilst the other slide
valve is closed to the chamber d. The chamber d¹ which was previously charged
with wood for preliminary heating has a temperature of about 100° C.; whilst the
chamber which was charged with wood to be cooled is completely cooled.
In consequence of the described position of the sliding valves and dampers or flap
valves, air is drawn through and h from the chamber d¹, and in the latter a rare-
faction of the air will take place in consequence of which hot air will pass from the
chamber through the upper apertures f, f, and f, f, into the said chamber d
Thus in the latter the wood is heated, whilst the air becomes saturated with moisture

page_text: Cold air now enters through the fresh air passage into the chamber and there
produces a gradual cooling of the hot preserved wood. Thus in this process, the heat
which would otherwise be lost by the cooling is utilized for the preliminary heating
of the fresh wood.
When the external air or atmosphere is very cold, then, for the purpose of pre-
venting too rapid cooling, previously heated air from the heating devices may be
admitted in adjustable quantities which is effected by suitably setting the slide valves
and flap valves.
The heating of one chamber and the simultaneous cooling of the other chamber
continues until the same temperature obtains in both chambers. Then the communi-
cations between the two chambers are interrupted by closing the apertures f¹, fl of
the chamber d², and opening the respective slide valves m in the suction funnel k,
and also the flap valves of the apertures i¹, whereby the air is allowed to escape from
the chamber into the open air. When the sliding valve s is opened, fresh air
enters into this chamber from the passage n and produces the complete cooling of
the preserved wood.
For the chamber d¹ the flap valves of the apertures e orf of the passages c, c
are set in such a manner that either the lower openings e or the upper openings fare
opened. Correspondingly, the flaps of the apertures i, in the exit passages h, h
are set in the reverse manner, so that the air passes through the chamber from the
bottom to the top or 'from the top to the bottom. The consequence of this move-
ment of the air is a further preliminary heating and evaporation which is continued
until the wood has reached the dryness which is necessary for the subsequent
preserving process, and a temperature of 100° C.
The chamber is now emptied, and its wood is placed into the cylinder for the
purpose of preserving, whilst the wood which has just been preserved in the latter, is
placed in the chamber d', which now becomes the cooling chamber, whilst the freshly
charged chamber (72 serves as the preliminary beating chamber, for which purpose the
slide valves and flaps must be correspondingly reversed. In consequence of this
alternative working in both chambers, it is possible to carry on the operation
continuously.
The preliminary heating may be accelerated by the admission of steam through the
pipes q, and a desired degree of dryness may be produced.
If, instead of the drying chambers, two impregnating chambers are employed, then
the working with the three boilers or cylinders is advantageously carried on as
follows:-
The first cylinder is charged with fresh wood to be heated preliminarily, whilst, at
the same time previously heated wood is being preserved in the second cylinder, and
the wood which is already preserved is being cooled in the third cylinder. After
complete cooling, the third cylinder is emptied, charged with fresh material, and then
acts as a preliminary heating cylinder. After the preliminary heating has been
completed in the first cylinder, the said first cylinder is employed for preserving, and the
second cylinder in which wood has been preserved now serves as a cooling cylinder.
In this way the working may be rendered continuous by a constant suitable change
in the order, of using the cylinders.
For the purpose of passing steam and hot air from one cylinder into the other, the
cylinders are connected together by pipes and are arranged to be shut off from one
another by means of slide valves and flap valves, or other closing devices, so that the heat
is most favourably utilized. The air required for the preliminary heating and for the
drying may be heated either in a steam superheater or in a special heating apparatus,
and may be introduced by means of fans or natural draught into the cylinders. The
spent air can be exhausted from the cylinders by means of the existing ejectors, air
pumps, or by specially provided exhaustors. The steam generator and the super-
heater are preferably combined in one apparatus in such a manner that the boiler
furnace gases give up their heat, either to the boiler only or to the super-heater
only, or first to the steam boiler, and then to the super-heater. When using three
cylinders, the vapours escaping during the preserving operation may be led into the

page_text: cylinder that serves to effect the preliminary heating, whereby a further more
advantageous utilization of the fuel is effected.
In both arrangements of apparatus, it is advantageous to provide the preserving
cylinder, or it may be the three cylinders, with a double jacket, into which air or
super-heated steam can be admitted, whereby it is rendered very easy to maintain
constant the temperature necessary for the several processes that take place which is
of great importance, especially as regards the emptying of the cylinder which takes
place prior to the tarring operation.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
1. In preserving wood, a process for drying fresh, wet, or frozen wood, in which the
heat of the previously impregnated hot wood is utilized, with simultaneous cooling of
the latter, consisting in charging fresh wood alternately into one of two drying
chambers d, d², adapted to be brought into communication, to be suitably controiled,
and shut off from one another, and charging into the other of the two chambers thie
hot wood from the impregnating boiler, the arrangement being such that by suitably
reversing the valves or dampers an exchange of temperature and air is effected
between the two chambers, the heat of the preserved wood being employed
for preliminary heating and drying the fresh wood which has been charged into the
chamber which was previously employed for cooling, the chamber that is being used
for cooling being shut off from the preliminary heating chamber and placed in com-
munication with the outer air for the purpose of complete cooling.
2. A modification of the process specified in the preceding claim, in which, instead
of the two drying chambers, two boilers are provided which are capable of being
brought into or put out of communication with the impregnating boiler and in which
three boilers, the preliminary heating, preserving, and cooling operations, take place
alternately, in such a manner that the preliminary heating is effected in one boiler,
the preserving in the next following boiler, and the cooling in the last boiler, and then
the working is changed by suitably reversing the closing devices.
3. For carrying out the process specified in Claim 1, an apparatus comprising two
chambers d', d2 arranged side by side, and heated by devices a, a arranged below
said chambers, said chambers communicating with hot air passages c, c by means of
apertures e, e¹ and ƒ, ƒ¹ provided at the floor and ceiling respectively, and which are
capable of being closed by means of suitable valves, the said chambers also com-
municating with a common fresh air passage n which can be closed by means of
a sliding valve s, and also communicating by means of openings i, (that can be
closed by means of suitable valves) with suction passages h, h¹ that deliver into outlet
funnels k.
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.