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Патент USA US3019016

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Jan. 30, 1962
A. W~ LILLIENBERG
3,019,006
MULTIPLE ZONE HEATING FURNACE
2 Sheets-Sheet 1
Filed July 28, 1958
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Jan. 30, 1962
3,019,006
A. w. LILI_u-:NBERG
MULTIPLE ZONE HEATING FURNACE
2 Sheets-Sheet 2
Filed July 28, 1958
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/NVENTOR.'
ATTORNEYS.
United States Patent Giifiee
3,1ll9ß06
Patented Jan. 30, 1962
2
1
tubes arranged in different sets corresponding in number
3,019,006
to the zones. In the furnace as illustrated wherein there
August W. Lillienberg, Chicago, Ill., assignor to Lind
berg Engineering Company, a corporation of Illinois
Filed July 28, 1958, Ser. No. 751,325
4 Claims. (Cl. 263-42)
are two Zones there are two sets of tubes, one indicated
the tubes 17 are arranged alternately with tubes 13 in an
annular series adjacent to the furnace wall so that they
This invention relates to a multiple Zone heating fur
furnace as shown. Each of the tubes carries a burner 19
MULTWLE ZONE HEATHNG FURNACE
nace and more particularly to a furnace heated by com
bustion tubes and having `a plurality of zones therein.
lt is desirable in many cases to provide two or more
heating zones in a furnace which are individually heated
so that different temperatures can be maintained therein
or so that one zone can be used for heating a partial load.
In furnaces heated by combustion tubes this has hereto
fore been possible only by using different sets of tubes
mounted at different heights in the side wall of the fur
nace.
Such tubes must be assembled in the furnace at
at '17 and the other at `13.
As best seen in FIGURE 2,
will surround the charge when it is placed centrally in the
adjacent to its lower end which extends upward into the
10 lower end of the tube to a level above the bottom of the
tube and preferably adjacent to the inner floor of the fur
nace chamber.
The burners for the tubes 17 are sup
plied with a primary fuel such as gas or an overrich
mixture of gas and air incapable of complete combustion
15 from a manifold 21.
rl`he burners in the tubes lâ are
similarly supplied with primary fuel from a manifold 22.
The two manifolds are separately controllable so that
either or both sets of tubes may be tired simultaneously.
In order to produce effective combustion in the tubes in
the time it is made and require substantially complete
disassembly and rebuilding of the furnace for replace 20 different zones the tubes 17 are of smooth cylindrical
configuration throughout approximately the lower half of
ment. Furthermore, in Such installations the tubes are
their lengths and are formed with a series of inwardly
necessarily curved so that hot spots develop at the bends
projecting dimples or baffle means 23 spaced longitudi
therein which cause the tubes to burn out more rapidly
nally and circumferentially around the tubes. ln similar
and which interfere with proper distribution of heat 'to
the furnace charge. lt is one of the objects of the present 25 manner the tubes 18 are formed with a series of inwardly
extending dimples or baffle means 24 spaced longitudi
invention to provide a multiple Zone heating furnace in
which a plurality of zones in the furnace are effectively
nally and circumferentially thereof throughout approxi
heated individually by straight tubes extending continu
ously through the furnace.
smooth cylindrical configuration throughout the upper
mately the lower one-half of their lengths and are of
Another object is to provide a heating furnace in which 30 half of their lengths.
The tubes may be mounted in the furnace by inserting
them through openings in the furnace top with the lower
are supplied with parallel separate streams of primary
straight tubes extending vertically through the furnace
,AM
ends thereof extending through openings in the furnace
fuel and `air and are provided with dimples or baille means
bottom. Suitable sealing means indicated at 25 may be
in different vertical Zones of different tubes to create effec
tive combustion in different Zones of the different tubes 35 provided at the tops of the tubes to seal them tightly
against the furnace top and to support the tubes and limit
thereby to heat different zones in the furnace.
vertical downward movement thereof into and through
According to a feature of the invention the furnace
the furnace.
may be provided with a tubular liner having openings in
In operation, assuming that the upper zone of the fur
its central portion for air circulation and with upper and
lower circulating fans for producing upper `and lower gas 40 nace only is to be heated, primarily fuel will be supplied
through the manifold Z1 to the burners 19 and the tubes
circulating streams.
17. The lower ends of the tubes are open so that air will
The above and other objects and features of the inven
rise through the annular space between the burners 19
tion will be more readily apparent from the following
and the inner walls of the tubes to pass in an annular
description when read in connection with the accompany
ing drawings, in which:
45 stream around the stream of primary fuel issuing from
the burner. Due to the smooth configuration of the lower
FIGURE l is a vertical section through a multiple zone
halves of the tubes the primary fuel and air will mix to
heating furnace embodying the invention;
,
FlGURE 2 is a partial section on the line 2_2 of FIG
URE l; and
a very limited extent as they flow upward through the
lower tube halves so that combustion will occur at a very
FEGURE 3 is a view similar to FlGURE 1 of an alter 50 slow rate, and the lower halves of the tubes 17 will be
heated to a very limited extent. However, as the stream-s
of primary fuel and air reach the dimpled upper portion
The furnace as shown in FÍGURE l comprises a ver
native construction.
tically elongated tubular body indicated generally at 1li
which may be formed by an outer shell 11 of sheet metal
of the tubes the dimples will cause progressive mixing and
agitation of the primary fuel and air to increase the com
having a refractory lining 12 therein. The bottom of the 55 bustion at a rate determined by the size and spacing of
the dimples. The upper Áhalves of the tubes in which the
furnace may be closed by a removable cover 13 or could,
dimples occur will, therefore, be heated to a maximum
temperature and will radiate maximum heat on to the
load in the upper basket 16.
In the the same manner when the tubes 1S are ñred
if desired, be closed by a permanent cover and the top
is preferably closed by -a removable cover 14 through
which the charge may be inserted in the furnace. The
furnace may be charged with a plurality of loads indi
cated by the dot-dash lines 15 and 16 in different levels
by admitting fuel thereto from the manifold 22, the pri
as, for example, by placing baskets containing parts to
mary fuel and air will be mixed by the dimples or baffle
be heated in the furnace one above the other.
means 24 in the lower half of the tubes so that maximum
combustion will occur in the lower tube halves. The
The furnace is heated by a plurality of combustion
3,019,006
3
á
ldimples are so related to the fuel and air flow and to
and air in separate streams to a combustion tube and
the tube diameters that combustion will be completed by
‘the time the fuel and air reach the upper smooth halves»
of the tubes so that the upper halves of the tubes 31‘8
will be heated only by the residual heat remaining in the
combustion gases and will achieve a temperature sub
stantially lower than that of the lower halves of the
tubes. In this way the lower halves of the tubes 18
may be heated to maximum temperature to provide maxi
mum heat radiation on a charge in the lower basket 15
and minimum radiation on a charge in the upper basket
15. By properly controlling the supply of fuel to the
different sets of tubes the temperatures in the upper and
lower zones of the furnace chamber may be accurately
controlled to maintain the same temperature very closely
or to maintain different temperatures as desired.
FIGURE 3 illustrates an alternative arrangement com
prising an elongated tubular furnace body 26 having a
removable top closure 27 for insertion of the load and
obtaining progressive combustion thereof by means of
dimples in the tube, this concept being more particularly
disclosed and claimed in the copending application of
John R. Duffy and August W. Lillienberg, Serial No.
382,686, filed September 23, 1953, now matured into
Patent No. 2,849,220.
While two embodiments of the invention have been
shown and described in detail, it will be understood that
these are illustrative only and are not to be taken as a
definition of the scope of the invention, reference being
had for this purpose to the appended claims.
What is claimed is:
l. In a multiple zone heating furnace, a plurality of
straight vertical combustion tubes for radiantly heating
the interior of the furnace extending through the top
and bottom walls of the furnace, each of the tubes being
open at one end for ilow of secondary air thereinto a
burner mounted within said one end of each of the tubes
and defining with the tube coaxial passages for a pri
mary fuel stream and a secondary air stream so that the
a bottom closure 28. A series of tubes 29 dimpled
throughout their upper halves and a second series of
tubes 31 dimpled throughout their lower halves are diS
posed in annular series alternating with each other around
the interior of the furnace in the same manner as the
tubes 17 and 1S of FIGURES 1 and 2. The tubes 29
primary fuel and secondary air will enter the tube in
separate parallel streams, means for supplying the burner
with a primary fuel containing insulllcient air for com
plete combustion, baille means in the tubes spaced longi
and 31 are separately supplied with primary fuel from
manifolds 32 and 33 through burners 34 positioned above
tudinally thereof for progressively agitating and promot
ting mixing of the primary fuel and air to effect progres
the open bottoms of the tubes in the same manner as the
sive combustion in the tubes, the baille means in certain
of the tubes spanning certain vertical zones only of the
burners 19 of FIGURE 1.
In this furnace a tubular liner 35 is provided in the
furnace radially inward from the series of tubes and the
charge is adapted to be placed within the liner as, for
example, in baskets, indicated by the dotted lines 36 and
3.7, stacked one above the other. For circulation of air
lthe liner 35 is supported above the bottom of the furnace
or may be formed with air circulating openings 3S there
through as shown, and is formed in its central portion
»With additional air circulating openings 39.
tubes corresponding to one vertical zone in the furnace
and the baille means in others of the tubes spanning dif
ferent vertical zones only therein corresponding to a dif
ferent vertical zone in the furnace whereby the differ
ent tubes will effectively heat said different vertical zones
in the furnace.
2. The furnace of claim l in which the burners for
tubes in which the baille means lie in different vertical
zones are supplied with fuel from separate means where
by heating of the different furnace zones can be separate
For circulating the air or gas within the furnace two
fans or blowers are provided. As shown, one fan 4l is 40 ly controlled.
carried by the lower closure plate 28 and is of the radial
3. A multiple zone . eating furnace comprising a tubu
vaned blower type to draw air downwardly through the
kliner 35 and the lower portion of the charge 36, circulate
the air outwardly through the openings 38, upwardly
around the tubes and in through the openings 39. A
similar blower 42 is carried by the upper cover plate 27
to draw airupwardly through the liner 35, outwardly and
downwardly over the tubes and inwardly through the
openings 39. To assist in minimizing intermingling of
lar vertical furnace body having top and bottom walls,
a plurality ofrstraight vertical combustion tubes extend
ing through the top and bottom walls and distributed
within the furnace body adjacent to the side walls there
of, each of the tubes being open at its bottom for flow
of secondary air thereinto a burner mounted within the
lower end of each tube and defining therewith coaxial
passages for a primary fuel stream and a secondary air
the streams of air an annular baille 43 may be mounted 50 stream, means for supplying the burners with a primary
in the furnace chamber. The baffle is preferably of V
section, as shown, with its narrow point lying centrally
adjacent to the openings 39 and is formed with openings
fuel containing insutllcient air for complete combustion,
certain of the tubes having baille means in their lower
portions only and others of the tubes having baflle means
therein through which the tubes 29 and 3i extend.
in their upper portions only for progressively agitating
In operation with the furnace charged and with both Crt U1 and promoting mixing of the primary fuel and air to
fans 4l and 42 running, air will be circulated in the
effect progressive combustion in said portions of the tubes
manner described and as indicated by the arrows. The
thereby to effectively heat lower and upper lzones in the
air circulated by the lower fan 41 will be heated pri
furnace, a tubular liner in the furnace lying within the
marily by the lower sections of the tubes 31 which are
ser-ies of tubes and having openings for gas circulation
`the hot sections thereof, and will primarily circulate 60 centrally of its length, and gas circulating units at the top
downwardly over the charge in the lower basket 36 so
and bottom ofthe furnace to create circulating gas streams
that its temperature is controlled mainly by the lower
through the liner and opening therein and respectively
heated sections of the tubes 31. At the same time the
upwardly and downwardly over the tubes.
air circulated by the fan 42 will be primarily heated by
4. In a multiple zone heating furnace, a plurality of
the upper hot sections of the tubes 29 and will return
straight vertical combustion tubes for radiantly heating
upwardly after entering the liner through the openings
the interior of the furnace extending through the top and
39 to heat the charge in the upper basket 37. While
bottom walls of the furnace, each of the tubes being open
there will inevitably be some intermingling of the air
at its bottom for flow of secondary air thereinto a burner
streams the effects will primarily be as described so that
mounted within the lower end of each of the tubes and
70
the charges in the different baskets can be heated by cir
dellning with the tube coaxial passages for a primary fuel
culating air or gas at different temperatures or at the
-sarne temperature as desired.
Applicant makes no claim to the broad concept of con
trolling the combustion rate -by supplying primary fuel
stream and a secondary air stream so that the primary
fuel and secondary air will enter the tube in separate
parallel streams, means for supplying the burner with a
primary fuel containing insufficient air for complete com
3,019,006
5
bustion, means in the lower ends only of certain of the
tubes for progressively agitating and promoting mixing
of the primary fuel and air to e?‘ect progressive combus
tion which will be completed in the lower ends only of
said tubes, means in the upper ends of others of the
tubes and at an elevation above the last named means
for progressively agitating and promoting mixing of the
primary fuel and air in the upper ends of said other
tubes, the lower ends of said other tubes being smooth
10
and unobstructed to minimize combustion therein.
6
References Cited in the ñle of this patent
UNITED STATES PATENTS
1,244,864
1,891,981
2,068,477
2,137,870
2,619,451
2,781,188
2,822,798
2,910,285
Kemp et al. __________ __ Oct. 30, 1917
Herbst ______________ __ Dec. 27, 1932
Woodson ____________ .__ Jan. 19, 1937
Woodson ____________ __ Nov. 22, 1938
Ogorzaly etal _________ __ Nov. 25, 1952
McKeown ___________ __ iFeb. 12, 1957
Ipsen _______________ __ Feb. 11, 1958
Harris _______________ _.. Oct. 27, 1959
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