Method of and Apparatus for Re-heating Compressed Air for Industrial Purposes.
Year: 1899

page_text: Date of Application, 16th May, 1899 -Accepted, 1st July, 1899
COMPLETE SPECIFICATION.
Method of and Apparatus for Re-heating Compressed Air for
Industrial Purposes.
I, CLAUDE KENNEDY MILLS, of 23, Southampton Buildings, in the County of
London, Patent Agent, do hereby declare the nature of this invention (a com-
munication to me from Thomas Alva Edison, of Orange, Essex County, New
Jersey, one of the United States of America, Inventor) and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement:-
The invention relates to a method and apparatus for restoring to compressed
air the loss by radiation of heat due to compression. The loss of this heat, as is
known, lowers the commercial efficiency of compressed air for industrial pur-
poses. By the present invention, the heat of compression lost by radiation can be
restored in part, in whole or in excess. The invention consists in deflecting a
portion of compressed air, and diverting the same into direct contact with a solid
or approximately solid burning combustible material, whereby combustion will
be maintained and heat will be absorbed directly, and in causing the portion of
compressed air thus directly heated to reunite with the other portion from which
it was deflected. Preferably, the invention also consists in heating the air (except
the deflected portion) by radiation and convection from the source of burning
combustible material and then intermixing the portions thus directly and in-
directly. heated. Preferably, the invention further consists in causing a drop in
pressure to be maintained in the conductor adjacent to the source of burning
combustible material, whereby the flow of the deflected portion will be secured
and automatic regulation will be effected. The apparatus consists generally of
a closed chamber containing a burning solid or approximately solid combustible
material with a bye-pass in the conductor for directing a portion of the com-
pressed air into the said chamber whereby combustion will be maintained and
the deflected portion will be directly heated; also, preferably, in providing a
jacket around the chamber for heating the compressed air (except the deflected
portion) by radiation and convection; also in providing the bye-pass with a valve
for regulating the proportion of air flowing through the same; and, also, in pro-
viding the air-conductor with a checking device for causing a drop in pressure
adjacent to the re-heater, to provide for the flow through the bye-pass."
In the drawings,
Figure 1, represents a diagram of the invention;' and
Figure 2, a sectional view of an improved form of re-heater.
In Figure 1, is illustrated two sources of compressed air supply, namely: a
compressor 1 and a storage tank 2,, either of which may be used. When the
compressor 1 is employed, usually a line pipe 3 connects it with the translating
device, of which two instances are illustrated, namely: a rock drill 4, and an air-

page_text: engine 5. 6 is the re-heater having a combustion chamber 7, and, preferably,
a jacket 8 interposed in the pipe line. 9 is a grid in the re-heater on which
solid or approximately solid combustible material is placed. Preferably, the
combustible material is charcoal, coke or anthracite coal in a relatively finely-
divided condition. 10 is a pipe leading into the re-heater below the grid, and 11
a pipe leading out of the re-heater whereby a bye-pass is secured from the air-
pipe through the re-heater and returning to the air-pipe. Pipe 10 is provided
with a valve 12, and pipe 11 with a valve 13. In order to provide for a drop in
pressure in the pipe adjacent to the re-heater, a retarding device, such as valve 14,
is used. As the quantity of air consumed at the translating device will deter-
mine the drop in pressure and since the volume of the flow of the compressed
air through the combustion chamber of the re-heater will depend upon the differ-
ence in pressure between the ends of the bye-pass, it follows that the device will
be substantially self-regulating since the heat developed in the re-heater will be
proportional also to the flow of air through it. The air flowing through the
bye-pass and re-heater will be heated directly and will pass, with the products
of combustion, to the air-pipe where it will be mixed with the remaining air.
Preferably, the compressed air (except the deflected portion) is heated by radia-
tion and convection in the enclosing jacket 8. In Figure 2, the chamber 7 is
separate from the jacket 8, the packing 15 being used to prevent leakage. 16
are lugs or ears carrying the grid 9. 17 is a bottom door held closed by a screw 18
working in a pivoted bridge 19 with a packing 20 above it. 21 is a screw-plug
for the introduction of burning waste to start the combustion. 22 is a fire-brick,
ásbestos or other insulating lining for the upper portion of the combustion chamber.
23 is a suitably-lined upper door secured in place by a screw 24 working in a
bridge-piece 25. 26 is a jacket-pipe enclosing pipe 11 and having ports leading
into the air-pipe. 28 is a bye-pass with valve 29 for maintaining circulation in
the jacket-pipe 20. A screen 30 may be used for preventing large particles of
ash from passing into the translating device, although this screen is not necessary
in all instances, particularly when the velocity of flow of the deflected air is very
low. Instead of a valve 14, is shown a perforated disc 31 in the air-pipe to provide
for the drop in pressure on the working side of the re-heater.
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. A method of re-heating compressed air for industrial purposes which consists
in deflecting a small portion of the air and diverting it into contact with a source of
burning combustible material to maintain combustion thereof, and to absorb
heat directly, and in causing the deflected air thus directly heated to reunite with
the air from which it was deflected.
2. The method recited in Claim 1 carried out with the additional operation of
.causing the air (except the deflected portion) to be heated by radiation and con-
vection by the same source of burning combustible material."
3. The method recited in Claim 1 or 2 carried out with the additional operation
of causing a drop in pressure in the air-pipe to provide for the flow of the deflected
portion of air, and to automatically vary the heat generated in the re-heater in
proportion to the air consumed in the translating devices.
4. An apparatus for heating air comprising a closed chamber in which a solid
or approximately solid combustible material is consumed, and a bye-pass from
the air-pipe leading through said chamber, whereby a portion of the compressed
air will be deflected into the chamber to maintain combustion and absorb heat
directly, which portion is reunited with the air from which it was deflected.
5. An apparatus as recited in Claim 4, with the addition of a jacket around the
closed chamber and interposed in the air-pipe, whereby the compressed air (except
the deflected portion) will be re-heated by radiation and convection.
6. An apparatus as recited in Claim 4 provided with a valve or other devic

page_text: in the air-pipe to secure a drop in pressure adjacent to the re-heater and to thereby
cause the flow of air through the bye-pass.
7. An apparatus as recited in Claim 4 having a valve in the bye-pass to regulate
the quantity of air in the same.
1001
1
1000
HARRIS & MILLS,
23, Southampton Buildings, London, W.C., Agents.