Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
49
SPECIFICATION
TO ALL WHOM IT MAY CONCERNo
Be it known that I, Rolf Viktor Cederstrom, a subject of
the King of Sweden, and resident of the city of Stockholm, Sweden,
have invented certain new and useful improvmements in
"METHOD AND MEANS FOR Dl~YING"
and I do hereby declare that the following is a full, clear and
exact description of the same, reference being had to the
accompanying sheets of drawing and to the numerals of reference0 marked thereon, which form a part of this specification.
BACKGROUND OF THE INVENTION
Field of the Invention:
This invention relates to method and means for drying, and
more precisely method and means of the class which operates with
combustion of gas and which are adapted for removal of moisture
from the surface of objects.
Prior art:
Previously known drying apparatuses which operate with
combustion of gas may, simply stated, be said to constitute gas
burners for heating of the surface, which should be dried, to such
a temperature that water or moisture on the surface is removed
essentially by vaporization and evaporation due to the rize of
the surface temperature. However, it should be noted that a
comparatively large amount of heat energy is required to heat
the surface to such an extent that evaporation takes place Further,
it should be noted that by the combustion of gas, such as bottled
gas, there are also generated large quantities of water steam,
viz. of the order of about 2 cubic meters water steam per kilogram
-- 1 --
~ \
of gas. In one way or another also that water steam must be
removed to reach an effective drying. Therefore, the efficiency
of the known drying apparatuses is normally very low.
SUMMARY OF THE INVENTION
The method of drying a surface while blowing a gaseous
medium on to the surface according to the present invention
comprises blowing on to the surface in question a gaseous
pressurized drying medium, preferably compressed air, the
relative humidity of which is essentially lower than that of the
natural air layer immediately adjacent the surface, which shall be
dried, and heating the drying medium or parts thereof to such an
elevated temperature that the surface is permitted to ~uickly
attain a temperature above the dew point, preferably above
about 70 C but below the temperature at which the surface
in question is adversely affected.
For a fuller understanding of the invention, reference may
be had to the following description o~ preferred embodiments
illustrated on the accompanying drawing.
ON THF DR~WING
FIG. 1 shows an axial longitudinal section through a somewhat
gun-shaped drying apparatus according ~o the invention;
FIG. 2 shows an axial longitudinal section through a lance-
shaped drying apparatus according to the invention;
FIG. 3 shows an axial longitudinal section through the front
portion of a drying apparatus according to the invention having
a slightly modified gas combustion means.
AS SHOWN ON THE DRAWING
The drying apparatus in FIG. 1 comprises a hollow casing 10
-- 2 --
which serves as a handle and has a closed end 11 wherein
compressed air is admitted through an air hose 12 with an air
valve 13. In its other, foremost end the casing is provided
with an air nozzle 13A which may be designed in such a manner
that a conical air stream is rormed. Alternatively, the nozzle
may be designed in such a manner that a comparatively thin and
flat air stream is formed.
At its foremost end the hollow casing 10 is surrounded by
a ring hood 14 wherein a ring burner 15 for gas is disposed.
The burner 15 is fed with gas from a channel 16 which extends
through the casing 10 and is provided with a gas valve 17.
The valves 13 and 17 may be built together so that they are
manipulated simultaneously, and it is possible to design the
apparatus in such a manner, that a small pilot flame Is always
15 kept burning~ It would also be possible to design the valves
in such a manner that they operate in accordance wi~h the
principles of a so called "dead man's grip".
As shown the ring hood 14 is entirely open rearwardly and
it is designed in such a manner that an air slot 18 is formed
~0 between the same and the outer surface of the casing 10.
Although not shown in the drawing it would also be possible
to design the ring hood 14 in such a manner that the air flow
area thereof may be controlled, and also in such a manner that
the hood is axially adjustable in relation to both the nozzle
13A and the ring burner 15 which latter, of course, may also be
axially adjustable in relation to the nozzle 13A.
The embodiment of FIG. 2 differs from the one of FIG. 1
only in that the hollow casing 10 of FIG~ 2 is designed as an
-- 3 --
elongated tubular lance.
The embodiment of FIG. 3 differs from the one of FIG. 2
essentially in that the air nozzle 13B is slightly extended
forwardly and in that the gas burner opening are disposed more
closely to the air nozzle.
Within the scope of the inventive idea the apparatus accord-
ing to the invention may be completed by suitable means for
surfaceooating or the like of the surface which is being dried.
Such means may take the shape of spraynozzles for paint or the
li~e, arranged adjacent the air nozzle 13A or 13B, or within
or round about the same.
The apparatus according to the invention operates in the
followi~g manner:
In operation compressed air of a rather high pressure, such
as of a pressure of 5 - 7 atmospheres super pressure and with
a flow of about 0,5 cubic meters/min,. is fed to the nozzle 13A
and is blown in the shape of a cone or a flat stream against
the surface which is to be dried.
By ejector effect also some air is also sucked in from
behind through the slot inside the hood. The compressed air and
the ambient air which has been sucked in is heated by means
of the gas burner 15. Thereby there is formed a cone or
flow of hot air which ensures a quick pick up of moisture from
the surface which is being dried. The air of the air cone from
the nozzlè results in that the very humid air is quickly
moved away sidewardly, and at the same time it is ensured
that no overheating occurs. Thus, it has proven possible to
take upp moisture from wet paper without lighting the paper or
even damaging the same by miscoloring.
The drying technique according to the invention makes use
of the circumstance that moisture movements inwardly of a mater-
ial may be reducea or even preventea if the heat transport within
the material may be reduced and/or the speed of evaporation may
be increased. Thus, if it is possible to prevent that the moisture
before the evaporation first goes the way inwardly of the material
and then returns back to the surface is it possible,to increase
the drying effect materially. Moreover, this may take place at
a smaller consumption of energy than with normal methods. As
it is moreover possible so to say to "suck" up the water from the
surface the drying effect may be still further increased.
In other words, the technioal solution may be said to
involve ~lowing over a surface hot air at a high velocity and
a relative humidity which is materially below that of the natural
air layer immediately adjacent the surface which is being dried.
This results in
.. a "suction effect" which increases the speed of evaporation
due to the difference in relative humidity;
.. increased evaporation due to high air velocity along the
surface;
.. reduced heat transport into the material because of the
rapid evaporation (and the possibility to work at lower
temperatures than bv the normal techniques);
.. possibility to control the surface temperature to the
proper value with respect to type of material, the medium
which isto be evaporated, the drying speed etc;
.. the drying operation may be carried out practically entirely
independent of environmental conditions~
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