Improvements in Apparatus for Withering Tea Leaf, or Exposing Chemicals or other Material to Hot or Cold Air, or a Mixture of Air and Vapor, or Gases; also for Drying Yarns, Cloths, and other Substances.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Withering Tea Leaf, or Exposing
Chemicals or other Material to Hot or Cold Air, or a Mixture of
Air and Vapor, or Gases; also for Drying Yarns, Cloths, and
other Substances.
I, SAMUEL CLELAND DAVIDSON of Sirocco Engineering Works, Belfast,
Ireland, Merchant, do hereby declare the nature of this invention to be as
follows:-
:-
My improvements have reference more particularly to, and apparatus for
circulating by means of a fan air, vapor, or gases, or any admixture of same in a
room or chamber and through the material that is being exposed therein to the
action or effects thereof, when suspended, ranged in tiers, or spread on trays
or racks.
The object of my invention is to obtain such a distribution of the current of air,
vapor or gases, throughout the room that the material spread therein will be more
evenly and thoroughly affected thereby, and the operation accomplished more
economically, than by the ordinary means hitherto employed for this purpose.
To carry my invention into effect, I construct the room in which the material is
to be exposed by being suspended, ranged on tiers or spread on trays or racks
therein to the action of the air, vapor or gases, as air-tight as practicable all round,
with the exception of orifices for the inlet of a conduit pipe for the air, vapor or
gases, and another for a similar pipe or conduit for outlet of same and which
conduit pipes I preferably project across to the opposite sides of the room at about
a foot distance below the ceiling and above the floor and discharge or exhaust the
air current therefrom through adjustable openings or perforations which are
preferably arranged in the top pipe along the side which faces towards the ceiling
and in the bottom pipe towards the floor and the conduit pipes may either be so
extended as single extensions or as two or more branch extension pipes the total
cross sectional area of which should at their outset be equal to or rather greater
than that of the main conduit pipe from which they emanate, and these extension
pipes are made in, preferably about 12 feet lengths, each of which is of sufficiently
decreased diameter towards the terminal end of the extension pipes to allow of the
smaller telescoping inside the next larger for convenience of packing and economy
of freight and carriage in transit, or I may alternatively construct the room with a
grated floor, about 4 feet above the actual floor of the room, and upon this grated
floor arrange the suspending appliances or racks of trays for the material to be
spread upon, and I leave a space of preferably about 4 feet in depth between the
top of the suspending appliances or racks of trays and the air-tight ceiling of the
room, with a perforated or grated false ceiling between the said space and
the material on the racks or tiers, and connect the flow and return conduit pipes
with the top and bottom spaces thus provided and project them more or less therein
as may be found desirable.
The above described conduits with their extension or air-diffusing spaces at top
and bottom of the room act as flow and return pipes to a fan, which, for convenience

page_text: of working is preferably placed outside the compartment (though it may, if desired,
be kept inside) the flow pipe being connected to the nozzle, and the return pipe to
the eye of the fan, and when heated air is required, either the flow or return pipe
(but preferably the return pipe) may have steam pipes in it, or in a chamber
forming a continuation between it and the fan, so that the air in passing to or from
the fan, as the case may he, will pass over said steam pipes and become heated
thereby or said chamber may have a hot air stove, or arrangement of gas burners,
so placed in it out of line of the current, or protected therefrom, that the flames of
the gas burners will not be extinguished by the draft; or if dry air without
increase of temperature, is required, this chamber may be so fitted with trays of
chloride of lime or other substances for drying air without heating it, that the air
current will pass over or through the chloride of lime or other material; or gases
or vapor may be introduced or injected into the air current passing through said
chamber to or from the fan.
The working of the apparatus is as follows :-
:-
When it is being employed for withering tea leaf, in accordance with the
principle described in the Specification of previous Letters Patent granted to me,
and dated 22nd May 1894 No. 9965 by subjecting the leaf to the action of moist
warm air, or mixture of air and vapor, without letting any evaporation of moisture
from the leaf take place, beyond what is requisite to keep the circulating air
charged with vapor, the same air is used over and over again and by my herein
described improvements is circulated through the chamber or room containing the
leaf, by the action of the fan drawing it in, preferably from below the grated floor,
or from the lower part of the room, by the conduit return pipe leading to the
re-heating chamber and thence to the fan, which then delivers it back through the
conduit flow and extension pipe into the upper part of the room, as hereinbefore
described, and no arrangement is provided for introduction of fresh air into the
circulating current, or allowing any escape of the saturated air or vapor therefrom,
beyond what in practical working is inevitable through crevices in and around the
doors and windows, &c., and the hereinbefore described method of distributing and
withdrawing the air equally and evenly over the whole area of the ceiling or floor,
produces a more equal and satisfactory action of the circulating current on the leaf
being exposed to its operation, than when same is performed in accordance with the
method described in my above referred to previous Specification.
When my herein described improved apparatus is used for drying yarns, cloths
or other substances, a door or valve is provided for inlet of fresh air to the heating
chamber, connected with the eye of the fan, and of sufficient size to give when
full open, as much air as the fan is capable of taking; and a ventilator or its
equivalent is provided of similar dimensions in the top of the room or compartment
if the return pipe to the fan is taken therefrom, or in the lowest part of the 'room,
if the return pipe lead from thence, for escape of the saturated air at the
commencement of the drying operation, at which time material, such as yarn is so
damp, that the hot air, by only passing once through it, gets so completely charged
with moisture that it should be allowed to escape entirely into the atmosphere,
without any of it being drawn back through the fan to be re-heated and circulated
again through the drying room; but when the material gets more than half dried,
one circulation of the air through it does not then effect its complete saturation,
and this is more and more the case as the material approaches complete dryness,
and to let this only partially saturated air escape, would be an equivalent waste of
heat in proportion as its saturation is less completely effected as the material gets
more and more dried.
Accordingly as the material becomes drier, I gradually bring the return pipe
circulation into operation by correspondingly from time to time closing the valve
or door which admits the fresh outside atmosphere to the heating chamber, to
which the eye of the fan is connected and by thus diminishing the fresh air supply
to the fan, a partial vacuum is produced in the return pipe, whereby a return
current from the drying room is created through it, of gradually increasing strength

page_text: as the fresh air inlet door or valve is more and more closed, until wheu completely
closed, the fan must necessarily draw its entire air supply through the return pipe
out of the drying room and when this is the case practically no exhaust or escape
of air takes place through the ventilator, even although it be kept as full open to
the finish as at the start, and accordingly the regulation of this fresh air supply
valve or door in the heating chamber leading to the eye of the fan, automatically
governs the retention of the air in the room or its escape therefrom to the outside
atmosphere, through said ventilator, without same requiring to be fitted with any
valve or door, and accordingly this ventilator may ordinarily be left open.
The regulation of the temperature of the air passing into the drying room is
controlled by the amount of steam admitted to the multitubular air heater, which
when using the exhaust steam from the engine can be reduced in quantity to any
extent by the employment of a two way cock in the exhaust pipe between the
engine and the multitubular heater whereby all or part of the exhaust steam can
either be directed into the air heater, or to the outside air as may be required; and
when a high temperature is required, more or less live steam may also be turned
into the multitubular heater, or a stove or gas burners, may be employed in place
of the steam heater, as hereinbefore already referred to, in which case I preferably
so place the stove and the chamber containing it in respect of the fan that the air
from the fan is propelled through the chamber instead of being sucked or drawn
through it, as would be the case if it were in the return pipe leading to the eye of
the fan, as in all stoves small crevices are liable to exist in the furnace sides and
the smoke flues and through which if a strong suction draft were induced in the
chamber containing the stove, smoke would be drawu from the smoke flues into the
air passing to the fan, but by having the enclosing chamber of the stove forming a
part of the flow pipe, the pressure blast from the fan causes the current to blow
through said crevices from the air chamber into the smoke flues, and consequently
no smoke can get into the air passing over or through the heating chambers of the
stove into the flow pipe.
When the apparatus is in operation, the flow current is projected into the top
part of the room through the graduated openings or perforations which are so
placed in the flow pipe or pipes that they deliver the air in the opposite direction
to where the return pipe is situated in the room, so that the air on escaping from
the flow pipe, first strikes against the air-tight ceiling or floor of the room, as the
case may be, and reverberating off same, passes in an even flow through the room
to the return pipe or to the ventilator or partly to both, and thereby operates on
the material spread in the room in an even and satisfactory manner.
It is obvious also that for the purpose of rapidly cooling the material in the
room (which in yarn drying is also desirable at the finish of the operation) it is
only necessary to fully open the door or valve inlet to the heating chamber, and
cut off the steam or other form of heat supply, whereupon nothing but cold air will
be passed through the room, which will efficiently and rapidly cool the material
therein.
I generally employ two withering or drying rooms arranged as aforesaid with
one circulating fan and I arrange stop or cut off valves in the flow or return pipes
to act in unison so that in closing off the return pipes in one room to the circulating
action of the fan and re-heating chamber the flow and return pipes of the other
room are simultaneously opened without requiring any stoppage of the fan.
Dated this 5th day of February 1895.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.

page_text: Improvements in Apparatus for Withering Tea Leaf, or Exposing
Chemicals or other Material to Hot or Cold Air, or a Mixture of
Air and Vapor, or Gases; also for Drying Yarns, Cloths, and
other Substances.
I, SAMUEL CLELAND DAVIDSON of Sirocco Engineering Works, Belfast,
Ireland, Merchaut, 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 :-
My improvements have reference more particularly to apparatus for circulating
by means of a fan air, vapor, or gases, or any admixture of same in a room or
chamber and through the material that is being exposed therein to the action or
effects thereof when suspended, ranged in tiers, or spread on trays or racks.
The object of my invention is to obtain such a distribution of the current of air,
vapor or gases, throughout the room that the material spread therein will be more
evenly and thoroughly affected thereby, and the operation accomplished more
economically, than by the ordinary means hitherto employed for this purpose.
To carry my invention into effect, I construct the room in which the material is
to be exposed by being suspended, ranged on tiers or spread on trays or racks
therein to the action of the air, vapor, or gases, as air-tight as practicable all
round, with the exception of orifices for the inlet of a conduit pipe for the air,
vapor, or gases, and another for a similar pipe or conduit for outlet of same and
which conduit pipes I preferably project across to the opposite sides of the room
at about a foot distance below the ceiling and above the floor and discharge or
exhaust the air current therefrom through adjustable openings or perforations
which are preferably arranged in the top pipe along the side which faces towards
the ceiling and in the bottom pipe towards the floor and the conduit pipes may
either be so extended as single extensions or as two or more branch extension
pipes the total cross sectional area of which should at their outset be equal to or
rather greater than that of the main conduit pipe from which they einanate, and
these extension pipes are made in preferably about 12 feet lengths, each of which
is of sufficiently decreased diameter towards the terminal end of the extension
pipes to allow of the smaller telescoping inside the next larger for convenience of
packing and economy of freight and carriage in transit, or may alternatively
construct the room with a grated floor, about 4 feet above the actual floor of the
room, and upon this grated floor arrange the suspending appliances or racks of
trays for the material to be spread upon, and I leave a space of preferably about
4 feet in depth between the top of the suspending appliances or racks of trays and
the air-tight ceiling of the room with a perforated or grated false ceiling between
the said space and the material on the racks or tiers, and connect the flow and
return conduit pipes with the top and bottom spaces thus provided and project
them more or less therein as may be found desirable.
The above described conduits with their extension or air diffusing spaces at top
and bottom of the room act as flow and return pipes to a fan, which for con-
venience of working, is preferably placed outside the compartment (though it
may, if desired, be kept inside) the flow pipe being connected to the nozzle, and
the return pipe to the eye of the fan, and when heated air is required, either the
flow or return pipe (but preferably the return pipe) may have steam pipes in it,
or in a chamber forming a continuation between it and the fan, so that the air in
passing to or from the fan, as the case may be, will pass over said steam pipes, and
become heated thereby; or said chamber may have a hot air stove, or arrangement

page_text: o gas burners, so placed in it out of line of the current, or protected therefrom,
that the flames of the gas burners will not be extinguished by the draft; or if dry
air, without increase of temperature, is required, this chamber may be so fitted
with trays of chloride of lime or other substances for drying air without heating
it, that the air current will pass over or through the chloride of lime or other
material or gases or vapor may be introduced or injected int the air current
passing through said chamber to or from the fan.
The working of the apparatus is as follows:-
When it is being employed for withering tea leaf, in accordance with the
principle described in the Specification of previous Letters Patent dated
22nd May 1894, No. 9965 by subjecting the leaf to the action of moist warm air,
or mixture of air and vapor, without letting any evaporation of moisture from the
leaf take place, beyond what is requisite to keep the circulating air charged with
vapor, the same air is used over and over again and by my herein described
improvements is circulated through the chamber or room containing the leaf, by
the action of the fan drawing it in, preferably from below the grated floor, or from
the lower part of the room, by the conduit return pipe leading to the reheating
chamber and thence to the fan, which then delivers it back through the conduit
flow and extension pipe into the upper part of the room, as hereinbefore described,
and no arrangement is provided for introduction of fresh air into the circulating
current, or allowing any escape of the saturated air or vapor therefrom, beyond
what in practical working is inevitable through crevices in and around the doors
and windows, &c., and the herein before described method of distributing and with-
drawing the air equally aud evenly over the whole area of the ceiling or floor,
produces a more equal, and satisfactory action of the circulating current on the
leaf being exposed to its operation, than when same is performed in accordance
with the method described in my above referred to previous Specification.
When my herein described improved apparatus is used for drying yarns, cloths,
or other substances, a door or valve is provided for inlet of fresh air to the heating
chamber, connected with the eye of the fan, and of sufficient size to give, when
fully open, as much air as the fan is capable of taking; and a ventilator or its
equivalent is provided of similar dimensions in the top of the room or compartment
if the return pipe to the fan is taken therefrom, or in the lowest part of the room,
if the return pipe lead from thence, for escape of the saturated air at the com-
mencement of the drying operation, at which time material, such as yarn is
so damp, that the hot air, by only passing once through it, gets so completely
charged with moisture that it should be allowed to escape entirely into the
atmosphere, without any of it being drawn back through the fan to be reheated
and circulated again through the drying room; but when the material gets more
than half dried, one circulation of the air through it does not then effect its
complete saturation, and this is more and more the case as the material approaches
complete dryness, and to let this only partially saturated air escape, would be an
equivalent waste of heat in proportion as its saturation is less completely effected
as the material gets more and more dried.
Accordingly as the material becomes drier, I gradually bring the return pipe
circulation into operation by correspondingly from time to time closing the valve
or door which admits the fresh outside atmosphere to the heating chamber, to which
the eye of the fan is connected and by thus diminishing the fresh air supply to the
fan, a partial vacuum is produced in the return pipe, whereby a return current
from the drying room is created through it, of gradually increasing strength as the
fresh air inlet door or valve is more and more closed, until when completely closed,
the fan must necessarily draw its entire air supply through the returu pipe out of
the drying room and when this is the case practically no exhaust or escape of
air takes place through the ventilator, even although it be kept as full open to the
finish as at the start, and accordingly the regulation of this fresh air supply valve
or door in the heating chamber leading to the eye of the fan, automatically governs
the retention of the air in the room or its escape therefrom to the outside

page_text: atmosphere, through said ventilator, without same requiring to be fitted with any
valve or door, and accordingly this ventilator may, ordinarily, be left open.
The regulation of the temperature of the air passing into the drying room is
controlled by the amount of steam admitted to the multitubular air heater, which
when using the exhaust steam from the engine can be reduced in quantity to any
extent by the employment of a two-way cock in the exhaust pipe between the
engine and the multitubular heater whereby all or part of the exhaust steam can
either be directed into the air heater, or to the outside air as may be required; and
when a high temperature is required, more or less live steam may also be turned
into the multitubular heater, or a stove, or gas burners, may be employed in place
of the steam heater, as herein before already referred to, in which case I preferably
so place the stove and the chamber containing it in respect of the fan that the air
from the fan is propelled through the chamber instead of being sucked or drawn
through it, as would be the case if it were in the return pipe leading to the
eye of the fan, as in all stoves small crevices are liable to exist in the furnace
sides and the smoke flues and through which if a strong suction draft were
induced in the chamber containing the stove, smoke would be drawn from the
smoke flues into the air passing to the fan, but by having the enclosing chamber of
the stove forming a part of the flow pipe, the pressure blast from the fan causes
the current to blow through said crevices from the air chamber into the smoke
flues, and consequently no smoke can get into the air passing over or through the
heating chambers of the stove into the flow pipe.
When the apparatus is in operation, the flow current is projected into the top
part of the room through the graduated openings or perforations which are so
placed in the flow pipe or pipes that they deliver the air in the opposite direction
to where the return pipe is situated in the room, so that the air on escaping from
the flow pipe, first strikes against the air-tight ceiling or floor of the room, as the
case may be, and reverberating off the same, passes in an even flow through the
room to the return pipe or to the ventilator or partly to both and thereby operates
on the material spread in the room in an even and satisfactory manner.
It is obvious also that for the purpose of rapidly cooling the material in the
room (which in yarn drying is also desirable at the finish of the operation) it is only
necessary to fully open the door or valve inlet to the heating chamber, and cut off
the steam or other form of heat supply, whereupon nothing but cold air will be
passed through the room, which will efficiently and rapidly cool the material
therein.
I generally employ two withering or drying rooms arranged as aforesaid with
one circulating fan and I arrange stop, or cut off valves in the flow or return pipes
to act in unison so that in closing off the flow and return pipes in one room to the
circulating action of the fan and re-heating chamber the How and return pipes of
the other room are simultaneously opened without requiring any stoppage of
the fan.
The apparatus is obviously also applicable for the purpose of exposing chemicals
or other materials to the action of currents of hot or cold air or a mixture of air
and vapor or gases.
The accompanying drawings fully illustrate my invention and how same is carried
into effect:
Figures 1, 2 and 3 show respectively in longitudinal, transverse and horizontal
section an arrangement of the apparatus to which two tea leaf withering chambers or
rooms are fitted with stationary racks for carrying the leaf upon trays or webs with
the circulating fau engine and air heater situated between the two rooms and the
main conduit pipes projected into and extended nearly the full length of the room.
Figures 4, 5 and 6 show an arrangement of the apparatus similar to that shown in
Figures 1, 2 and 3 applied to withering rooms constructed on an upper floor of a
tea factory by having the suction pipes suspended or supported underneath the
floor of the withering rooms and branch pipes from close to the floor of the room
leading into them through orifices in the floor.

page_text: Figures 7, 8 and 9 represent another modification of the system applied to leat
withering rooms, but in which the ends of the conduit pipes are merely led into.
chambers formed above and below the leaf racks there being a false perforated or
grated ceiling at a short distance beneath the actual ceiling and a perforated or
grated floor at a short distance above the actual floor of the rooms.
Figures 10, 11 and 12 illustrate another modified arrangement of the apparatus
for leaf withering rooms when situated on both the upper and ground floors of a
building. In this modification the circulating fan with engine and air heater are
preferably placed as shown in an adjoining room or compartment outside of the
withering rooms.
Figures 13, 14, 15 and 16 represent the application of the apparatus to a yarn
drying room in which the yarns are exposed to the heated air by being suspended
on bars carried on frames or racks and having the circulating fan with engine and
air heater in an adjoining room as in Figures 10, 11 and 12 delivering the freshly
heated air through the How pipe therefrom into the top part of the room with
ventilating shafts to carry off excess of the moisture laden air from a rather lower
level in the room than that of the return pipe to the fan.
Figures 17, 18 19 and 20 show a similar application of the apparatus to yarn
drying rooms, but with the flow pipe from the fan delivering the freshly heated air
below the perforated or grated floor of the room and ventilating shafts to carry off
the excess of the moisture laden air from an air space formed in the apex of the
roof of the drying room by a perforated or grated ceiling above the return pipe
leading from the upper part of the room back to the fan.
The same letters of reference indicate the same or corresponding parts in all the
figures.
A A are tiers, trays or racks for the leaf trays or suspending bars for the yarn,
B is the inflow conduit pipe and C the return conduit pipe, D D are the openings
or perforations in the conduit pipes, E (Figure 7) is the grated floor and F the
grated or false ceiling, G is the air tight ceiling, H is the fan, J the air heater
and K the engine, L is the adjustable valve or door for inlet of fresh air into air
heater, M M (Figures 13 to 20) are the ventilators for allowing of the escape of
saturated air, N N are valves for changing the flow and return air current from
one withering room to another in the arrangements shown in Figures 1 to 12. As
already hereinbefore stated the valves N N for the flow and return pipes of the
two rooms respectively are preferably arranged to act in unison so that in shutting
off the flow and return pipes in une room to the circulating action of the fan H
the flow and return pipes of the other room are simultaneously opened. The
two valves N N are for this purpose connected together in any suitable manner as
will be well understood. OO are doors to the withering or drying rooms.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is :-
1. In apparatus for withering tea leaf or treating other substances and consisting
of rooms made as air-tight as practicable with the exception of orifices for inlet
and outlet of conduit pipes for the air or mixture of air and vapor to be circulated
through the room, with racks or tiers of trays on which the leaf to be withered or
substance to be treated is spread, so as to be subjected to the action of a fan-
circulated current of warm air or vapor in which the vapor arising out of the leaf
or substance is so far as practicable retained, in accordance with the principle
described in my said previous Specification, with fresh air only admitted as
required through an adjustable valve or door in the air heater chamber or return
pipe to the fan, the employment of inflow pipes at top, and exhaust pipes at
bottom of room, or vice versa, in which pipes there are perforations or openings
at suitable distances for distribution of the air current, and for its withdrawal or
exhaust to effect an even flowing circulation and current thereof through the
whole room from the inflow to the exhaust pipe; or alternatively the combined

page_text: employment of a flow pipe and a return pipe communicating respectively with air
spaces above and below said racks or tiers of trays, with a perforated or latticed
false ceiling and false floor dividing same from the body of the room containing
the racks or tiers of trays, so that when the inflow air is blown into either space
from the circulating fan it may flow in an even current to the other space, from
whence it is withdrawn by the exhaust or return pipe to the circulating fan, all
substantially as herein before described and represented in the accompanying
drawings.
2. In apparatus for withering tea leaf, or drying yarns, cloths or other
substances or subjecting materials to the action of currents of air, vapor or
gases and consisting of rooms made as referred to in Claim 1 with racks or
suitable appliances for suspending or exposing the leaf to be withered or the
material to be dried or treated to the action of the air, vapor or gas passing
through said room, the employment of pipes with perforations or adjustable
openings as referred to in Claim 1, made in lengths so as to telescope into one
another for convenience and economy of carriage in transit, freight, &c. all
substantially as herein before described and represented in the accompanying
drawings.
3. In apparatus for drying or otherwise treating yarns, cloths or other
substances or materials and consisting of rooms made as referred to in Claim 1,
the employment of an inlet valve or door for admitting fresh air from the
outside atmosphere into the heating chamber or other part of the return pipe or
conduit to the fan, in combination with a ventilator or the equivalent thereof
communicating with the outside atmosphere from approximately the same part of
the drying room as the return pipe to the fan leads from, whereby the operation
of said ventilator even when left continuously open is automatically controlled and
regulated by the operation of said fresh air inlet valve or door in the heating
chamber, the full opening of which causes the full discharge or exhaust action of
the ventilator, and its closure an equivalent diminution of same all substantially as
hereinbefore described and represented in the accompanying drawings.
Dated this 28th day of October 1895
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.