U.S. patent application number 14/030210 was filed with the patent office on 2014-03-20 for infrared tube heater.
This patent application is currently assigned to GOGAS GOCH GMBH & CO. KG. The applicant listed for this patent is GOGAS GOCH GMBH & CO. KG. Invention is credited to TOBIAS BOEHM.
Application Number | 20140076307 14/030210 |
Document ID | / |
Family ID | 46845641 |
Filed Date | 2014-03-20 |
United States Patent
Application |
20140076307 |
Kind Code |
A1 |
BOEHM; TOBIAS |
March 20, 2014 |
INFRARED TUBE HEATER
Abstract
An infrared tube heater includes at least one burner device and
a beam tube. The burner device includes a burner and a fan. The fan
is constructed to supply air to the burner and the burner is
constructed to emit a flame into the beam tube. The burner is
equipped with a mixer and at least one secondary air duct and the
burner is constructed in such a way that a portion of the air
supplied by the fan is supplied to the mixer and another portion of
the air is supplied to the at least one secondary air duct. The
mixer is constructed for mixing the air with a fuel, the fuel/air
mixture is burned in the flame, and the secondary air duct is
constructed to supply the portion of the air supplied to the
secondary air duct to the flame without fuel.
Inventors: |
BOEHM; TOBIAS; (MENDEN,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GOGAS GOCH GMBH & CO. KG |
DORTMUND |
|
DE |
|
|
Assignee: |
GOGAS GOCH GMBH & CO.
KG
DORTMUND
DE
|
Family ID: |
46845641 |
Appl. No.: |
14/030210 |
Filed: |
September 18, 2013 |
Current U.S.
Class: |
126/91A |
Current CPC
Class: |
F23D 14/12 20130101;
F23C 3/002 20130101; F24H 3/0488 20130101; F23D 14/36 20130101 |
Class at
Publication: |
126/91.A |
International
Class: |
F23C 3/00 20060101
F23C003/00; F24H 3/04 20060101 F24H003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 18, 2012 |
EP |
12 184 904.6 |
Claims
1. An infrared tube heater, comprising: a beam tube; a burner
device including a burner and a fan; said fan configured to supply
air to said burner; said burner having a mixer and at least one
secondary air duct, said burner configured to supply a portion of
the air supplied by said fan to said mixer, said burner configured
to supply another portion of the air supplied by said fan to said
at least one secondary air duct, and said burner configured to emit
a flame into said beam tube; said mixer configured to mix the air
with a fuel for burning a fuel/air mixture in the flame; and said
at least one secondary air duct configured to supply said portion
of the air supplied to said at least one secondary air duct to the
flame without fuel.
2. The infrared tube heater according to claim 1, wherein said at
least one secondary air duct is a plurality of secondary air ducts,
each of said secondary air ducts has a respective outlet, and said
mixer has at least one outlet for the fuel/air mixture.
3. The infrared tube heater according to claim 2, wherein said
outlets of said plurality of secondary air ducts are disposed
around said outlet of said mixer.
4. The infrared tube heater according to claim 2, wherein said
outlet of said mixer is provided with a flame tube, and said
outlets of said plurality of secondary air ducts are disposed
around said flame tube.
5. The infrared tube heater according to claim 2, wherein said
outlets are configured to cause a flow rate of the fuel/air mixture
at said at least one outlet of said mixer to be lower than a flow
rate of secondary air at least at one of said outlets of said
plurality of secondary air ducts.
6. The infrared tube heater according to claim 2, wherein said
outlets of said plurality of secondary air ducts together have a
smaller cross section than said at least one outlet of said mixer
for the fuel/air mixture.
7. The infrared tube heater according to claim 2, wherein each of
said outlets of said plurality of secondary air ducts has a smaller
cross section than said at least one outlet of said mixer for the
fuel/air mixture.
8. The infrared tube heater according to claim 2, which further
comprises a flame tube connected to said at least one outlet of
said mixer, said flame tube having a cross section being larger
than a cross section of each of said outlets of said plurality of
secondary air ducts.
9. The infrared tube heater according to claim 1, wherein said
mixer is a Venturi mixer.
10. The infrared tube heater according to claim 1, wherein said
mixer has an inlet nozzle and a mixing unit with a mixing
chamber.
11. The infrared tube heater according to claim 10, wherein said
mixing chamber has a cavity with an inlet for air and fuel and an
outlet for the fuel/air mixture, and said cavity has a cross
section increasing from said inlet to said outlet.
12. The infrared tube heater according to claim 11, wherein said
inlet of said mixing chamber has an annular gap formed by said
inlet nozzle and configured to introduce fuel therethrough.
13. The infrared tube heater according to claim 12, wherein said
inlet nozzle has a tubular element configured to introduce the air
into said mixing chamber, said tubular element being surrounded by
said annular gap.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority, under 35 U.S.C.
.sctn.119, of European Patent Application EP 12 184 904.6, filed
Sep. 18, 2012; the prior application is herewith incorporated by
reference in its entirety.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to an infrared tube heater
including a beam tube and a burner device having a burner and a
fan. The fan is configured to supply air to the burner and the
burner is configured to emit a flame into the beam tube.
[0003] In the commercial/industrial sector, infrared tube heaters
are frequently used, in particular, for heating production, storage
and sports halls or facilities. Infrared tube heaters generate heat
by burning a preferably gaseous or liquid fuel. For that purpose,
infrared tube heaters include burners with beam tubes. The burning
is therefore invisible, hence the name infrared tube heater or dark
radiator. The hot gases which are produced heat the surface of the
beam tubes which emit the heat predominantly in the form of
radiation, in particular in the infrared range. The fuel being used
is, for example, natural and liquid gas with ambient air added
in.
[0004] In terms of construction, infrared tube heaters are
themselves formed substantially of the burner, the beam tube (with
and without a reflector) and the exhaust gas system as main
components. The flame is formed within the beam tubes which are
attached subsequently. The beam tubes are connected linearly or in
a U-shaped manner generally continuously downstream of the burner
and are intended to radiate the heat generated as uniformly as
possible over the entire length of the tube. The burner technology
used is restricted in the case of infrared tube heaters exclusively
to what are referred to as free-flame burners which produce a long
diffusion flame in the beam tube and are preferably operated in one
or two stages or within narrow limits with a sliding modulation of
the burner power.
[0005] The burner and the beam tube have to be coordinated with
each other in the construction of the infrared tube heaters.
Ideally, the flame extends over the entire length of the beam tube
so that, ultimately, the beam tube can also be identically heated
overall. In particular, in the case of comparatively long beam
tubes or beam tubes twisted in a meandering manner, that
requirement, of course, cannot be met, and therefore at least one
flame which is as long as possible or a flame which fills the beam
tube as fully as possible is intended to be achieved.
[0006] However, the formation of the flame or the length of the
flame has a direct effect on pollutants, in particular nitrogen
oxides, released by the combustion of the fuel. The following
relationship can thus be produced, at least approximately.
[0007] Short flames generally have a high burning temperature,
which may result in high emissions due to the temperature
dependency of the formation of nitrogen oxide. By contrast, too
cold a burning results in high carbon monoxide emissions. In
particular, completely premixing Venturi burners, as are frequently
used in gas boilers and thermal springs, are therefore not suitable
for use on infrared tube heaters because of the short flame
formation since, due to the structural shape, in particular of the
beam tube, there is no possibility in that case of reducing the
flame temperature, for example by using recirculation of exhaust
gases or by construction as a surface burner.
SUMMARY OF THE INVENTION
[0008] It is accordingly an object of the invention to provide an
improved infrared tube heater, which overcomes the
hereinafore-mentioned disadvantages of the heretofore-known devices
of this general type, in particular to provide an infrared tube
heater in which a flame is as long as possible or a beam tube is
charged with a flame over as great a length as possible, with as
little an emission of nitrogen oxides as possible being
produced.
[0009] With the foregoing and other objects in view there is
provided, in accordance with the invention, an infrared tube
heater, comprising a beam tube and a burner device including a
burner and a fan. The fan is configured to supply air to the
burner. The burner has a mixer and at least one secondary air duct,
the burner is configured to supply a portion of the air supplied by
the fan to the mixer, the burner is configured to supply another
portion of the air supplied by the fan to the at least one
secondary air duct, and the burner is configured to emit a flame
into the beam tube. The mixer is configured to mix the air with a
fuel for burning a fuel/air mixture in the flame and the at least
one secondary air duct is configured to supply the portion of the
air supplied to the at least one secondary air duct to the flame
without fuel.
[0010] A comparatively long flame with little emission of nitrogen
oxides can be achieved, in comparison to a burner without a
secondary air duct, due to the fact that the burner is equipped
with a mixer and with at least one secondary air duct, the burner
is constructed in such a way that a portion of the air supplied by
the fan is supplied to the mixer and another portion of the air is
supplied to the at least one secondary air duct, the mixer is
constructed for mixing the air with a fuel, the fuel/air mixture is
burned in the flame, and the secondary air duct is constructed to
supply the portion of the air supplied to the secondary air duct to
the flame without fuel.
[0011] Further advantageous refinements of the present invention
emerge, in particular, from the dependent claims. The features of
the dependent claims can, in principle, be combined with one
another.
[0012] In an advantageous refinement of the invention, provision
can be made for the outlets of the secondary air ducts to be
disposed around the outlet of the mixer. In this way, the flame can
be encased to a certain extent by the secondary air. The radial
configuration of the secondary air ducts in this case ensures a
uniform distribution of the secondary air around the flame. This
measure substantially contributes to achieving a comparatively long
flame with little emission of nitrogen oxides.
[0013] In a further advantageous refinement of the invention,
provision can be made for the outlet of the mixer to be provided
with a flame tube, wherein the outlets of the secondary air ducts
are disposed around the flame tube. Ultimately, the same effect as
above is achieved by this measure. However, the reference point for
the configuration of the secondary air outlets is directed in this
case at the flame tube as the reference point.
[0014] In a further advantageous refinement of the invention,
provision can be made for the outlets to be constructed in such a
manner that the flow rate of the fuel/air mixture at the outlet or
the outlets is lower than the flow rate of the secondary air at the
outlet or the outlets of the secondary air duct or of the secondary
air ducts. The effect which can be achieved by using this measure
is that the secondary air can be entered a good distance into the
flame tube. This measure contributes substantially to achieving a
comparatively long flame with little emission of nitrogen
oxide.
[0015] In a further advantageous refinement of the invention,
provision can be made for the outlet of the at least one secondary
air duct to have a smaller cross section than the outlet of the
fuel/air mixture. The respective configuration of the cross section
of the corresponding outlets constitutes a measure in order to
obtain the above-desired outlet rates of the secondary air or of
the fuel/air mixture. The outlet rates can be set in a particularly
simple manner by the corresponding selection of the relevant cross
sections.
[0016] In a further advantageous refinement of the invention,
provision can be made for the mixer to be configured as a Venturi
mixer. A "Venturi" mixer is particularly readily suitable for
setting the substoichiometric burning of the fuel/air mixture
initially prevailing after the mixer outlet or directly at the
flame tube.
[0017] In a further advantageous refinement of the invention,
provision can be made for the mixing chamber to be provided with a
cavity having an inlet for air and fuel and having an outlet for
the fuel/air mixture, wherein the cross section of the cavity
increases from its inlet to its outlet, and/or for the inlet of the
mixing chamber to have an annular gap which is formed by the inlet
nozzle and through which the fuel is introduced, and/or for the
inlet nozzle to have a tubular element for introducing the air into
the mixing chamber, with that element being surrounded by the
annular gap. Such a configuration of the mixing chamber is
particularly advantageously suitable for providing a fuel/air
mixture which is intended to be burnt initially in
substoichiometric burning.
[0018] Other features which are considered as characteristic for
the invention are set forth in the appended claims.
[0019] Although the invention is illustrated and described herein
as embodied in an infrared tube heater, it is nevertheless not
intended to be limited to the details shown, since various
modifications and structural changes may be made therein without
departing from the spirit of the invention and within the scope and
range of equivalents of the claims.
[0020] The construction and method of operation of the invention,
however, together with additional objects and advantages thereof
will be best understood from the following description of specific
embodiments when read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0021] FIG. 1 is a diagrammatic, longitudinal-sectional view of an
infrared tube heater according to the invention;
[0022] FIG. 2 is an enlarged, fragmentary, longitudinal-sectional
view of a burner device of an infrared tube heater according to the
invention;
[0023] FIG. 3 includes a longitudinal-sectional view and an
end-elevational view taken along a line A-A of FIG. 3 in the
direction of the arrows, illustrating a mixing unit of a burner of
an infrared tube heater according to the invention; and
[0024] FIG. 4 includes views similar to FIG. 3 illustrating an
inlet nozzle of a burner of an infrared tube heater according to
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Referring now to the figures of the drawings in detail and
first, particularly, to FIG. 1 thereof, there is seen an infrared
tube heater according to the invention which substantially includes
a burner device B and beam tube S. The infrared tube heater
according to the invention is preferably provided with an exhaust
gas system A and/or a reflector R.
[0026] The beam tube S is preferably configured in the shape of a
hollow cylinder. As viewed over the length, the beam tube S is
preferably laid rectilinearly or in a meandering manner.
[0027] The exhaust gas system A can be constructed as a simple
chimney which is fitted on that side of the beam tube S which faces
away from the burner device or the burner B.
[0028] The reflector R can be configured, for example, as a
correspondingly tilted, hood-shaped sheet which is fitted along the
beam tube S and, in an installation position of the infrared tube
heater, substantially reflects infrared radiation in the direction
of a hall floor.
[0029] The burner device substantially includes a burner B and a
fan G.
[0030] As is seen in FIG. 2, the fan G substantially includes a
housing 10 and a ventilator 9. The fan G or the fan housing 10 has
a fan outlet 11 and a connecting flange 12 for connecting to the
burner B.
[0031] The burner B substantially includes a housing 13, a mixing
unit 1 with a mixing chamber 3, an inlet nozzle 2, an annular gap 5
for supplying fuel, a flashback guard 4, a flame tube 8 and at
least one secondary air duct 7.
[0032] The burner housing 13 is preferably configured in a
cylindrical manner and accommodates the above-mentioned components
of the burner B. Furthermore, the burner housing 13 is provided
with a connecting flange 14 for connecting the fan G and with a
connecting flange 18 for connection to the beam tube S.
[0033] Further alternative structural forms of the infrared tube
heater according to the invention that cannot be enumerated herein
are also conceivable. For example, provision can be made for the
burner housing 13 and fan housing 10 to be configured as a single
part and therefore, for example, the flanges can be dispensed with.
The beam tube S can also have a multi-part configuration, or the
fan G, with its suction side on the end side of the beam tube S,
can be fitted on the side of the exhaust gas system A.
[0034] Further details of the present invention emerge in
particular from a description of the function of the infrared tube
heater according to the invention.
[0035] The fan G conveys air out of its outlet 11 into the burner
B, in particular into a burner air inlet 15. In this respect, a
direction of flow of air from an input side of the burner toward a
side on which a flame emerges is produced. For the sake of
simplicity, the direction of flow of the air and of a subsequent
air/fuel mixture is indicated schematically by an arrow 19.
[0036] As seen in the direction of flow of the air or of the
air/gas mixture, the burner B is constructed as follows: inlet
nozzle 2, mixing unit 1 with mixing chamber 3, flashback guard 4
and flame tube 8.
[0037] The inlet nozzle 2 and the mixing unit 1 with the mixing
chamber 3 substantially form a mixer for mixing air and fuel.
[0038] In principle, the mixing unit 1 has a cylindrical outer
construction, for example in the form of a round cylinder or a
cylinder with a rectangular or square cross section.
[0039] The mixing chamber 3 is preferably configured as a
funnel-shaped cavity with a mixing chamber inlet 16 and a mixing
chamber outlet 17. The cross section of the cavity increases from
the inlet to the outlet, i.e. in the direction of flow. The cavity
could also take on other shapes.
[0040] The inlet nozzle 2 is configured approximately as a plate 23
with a central opening 20, as is seen in particular in FIG. 4. The
opening 20 can be configured so as to be slightly tapered in the
direction of flow. The opening is adjoined in the direction of flow
by a tubular element 21 which partially projects from the inlet
side 16 of the mixing chamber 3 into the mixing chamber 3.
[0041] The annular gap 5 for supplying fuel is provided between the
tubular element 21 and the mixing unit 1. In order to form a
chamber between the mixing unit 1 and the inlet nozzle 2, in
particular the plate 23 of the inlet nozzle 2, the above-mentioned
elements can be fitted at a small distance from one another. A
likewise annular seal 6, through which the inlet nozzle 2 can be
spaced apart from the mixing unit 1, is provided between the mixing
unit 1 and the inlet nozzle 2, in particular the plate 23 of the
inlet nozzle 2. Finally, this forms a chamber through which the
annular gap 5 can be supplied with fuel. Fuel can be introduced
into the chamber through a connection Br seen in FIG. 3 and the
fuel, in turn, is output into the mixing chamber 3 through the
annular gap 5.
[0042] The combination of the mixing chamber 3 and the annular gap
5 can function according to the Venturi principle, i.e. the air
flowing past the annular gap 5 generates a negative pressure,
through the use of which, in turn, the fuel is sucked out of the
annular gap 5. However, it is alternatively also conceivable for
the fuel to be blown out of the annular gap 5 by using positive
pressure, and therefore the Venturi effect is not used or is not
required.
[0043] The flashback guard 4 is fitted on the outlet side 17 of the
mixing chamber 3. The flashback guard 4 is substantially configured
as a circular or square plate which covers the outlet 17 of the
mixing chamber 3. The mixing chamber 3 can also have a number of
outlets. The flashback guard 4 has a suitable perforation which can
be penetrated by the fuel/air mixture produced in the mixing
chamber 3, but with it being ensured that the flame produced in the
direction of flow downstream of the flashback guard 4 does not
ignite the fuel/air mixture in the mixing chamber 3. The flashback
guard 4 can be configured, for example, as a perforated ceramic
plate or as a metal mesh.
[0044] Furthermore, the flame tube 8, which is preferably
configured as a cylindrical tube with a round cross section, can be
fitted further in the direction of flow. The walls of the flame
tube 8 can be provided with openings.
[0045] Provision is made for the burner, in particular the mixing
unit 1, to be provided with at least one, preferably with a
plurality of, secondary air ducts 7. It is assumed below by way of
example that there is a plurality of secondary air ducts 7.
[0046] The secondary air ducts 7 can be configured, for example, as
secondary air bores. The secondary air ducts 7 can run parallel to
the direction of flow or longitudinal direction of the mixing
chamber 3. The secondary air ducts have outlets 24. The secondary
air ducts 7 or outlets 24 can be disposed, preferably at the same
distance, in the circumferential direction of the mixing unit 1, as
is seen particularly in FIG. 3. If a longitudinal axis 22 of the
mixing unit is taken as the starting point and it is assumed that
the secondary air bores or the outlets 24 thereof are disposed on a
circle, that circle has a greater circumference or diameter than
the generally circular outlet of the mixing chamber or of the flame
tube. Even if the outlet of the mixing chamber is intended to be
composed of a number of outlets, the outlets of the secondary air
ducts are disposed to a certain extent around the outlets of the
mixing chamber. In other words, those outlets of the secondary air
bores which face the flame are always disposed radially outside the
mixing chamber outlet or the flame tube. Through the use of the
secondary air ducts, a portion of the air flowing into the burner
air inlet 15 is supplied past the mixing chamber 3 to the flame
burning in or behind the flame tube 8. Approximately in other
words, the secondary ducts take away some of the air from the
burner air inlet 15, conduct the air past the mixing chamber 3 and
supply the air again to the burning fuel/air mixture, i.e. the
flame, behind the mixing chamber outlet 17. Expressed in very
typically ideal terms, the air emerging from the secondary air
ducts 7 encases the flame over a certain length.
[0047] Furthermore, some of the air supplied by the secondary air
ducts 7 flows along the inner wall of the beam tube S. Due to the
secondary air being guided annularly at the outer regions of the
beam tube, a flame bearing against the tube wall can likewise be
avoided. Furthermore, tube cooling can be obtained and a premature
mixing with the substoichiometric fuel/air mixture can be
prevented.
[0048] Through the use of the at least one secondary air duct 7,
the burning of the fuel/air mixture, i.e. the flame of the burner,
is divided into substantially two main regions. There is firstly a
substoichiometric premixing of fuel and air. The substoichiometric
premixing takes place in the mixing chamber, which subsequently
leads to a flame burning substoichiometrically in the first region.
The air ratio downstream of the mixing chamber is preferably 0.5 to
0.9. In this respect, a premixing chamber can also be mentioned for
the mixing chamber 3, since only some of the air supplied by the
fan G is mixed in this case with fuel. To a certain extent, further
air is "admixed" with the actual flame by using the secondary air
ducts. The substoichiometric burning is substantially caused by the
fact that a quantity of air actually required for stoichiometric
burning (lambda=1) is partially conducted away through the
secondary air ducts and is only supplied again later on.
[0049] Secondly, the secondary air ducts or the supplied secondary
air result in the formation of a long diffusion flame because of
delayed and specific supplying of the secondary air. Through the
use of the configuration of the secondary air ducts, for example,
in the form of bores, the secondary air can be introduced into the
burner tube at relatively high speeds, and therefore relatively
high throwing ranges can be achieved. The position and
configuration of the secondary air ducts is therefore important for
the function of the burner. The radial configuration of the
secondary air ducts ensures a uniform distribution in this case of
the secondary air around the flame.
[0050] The higher speed of the secondary air at the outlet of the
secondary air duct in relation to the outlet for the fuel/air
mixture at the outlet of the mixing chamber can be realized, for
example, by using a corresponding configuration of the cross
sections. It can thus be provided, for example, that the cross
section of the outlet of the at least one secondary air duct is
smaller than the cross section of the at least one outlet of the
mixing chamber.
[0051] As a result, with the at least one secondary air duct, the
nitrogen oxide emissions of the burner and therefore of the
infrared tube heater can be reduced in comparison to an infrared
tube heater or burner without secondary air ducts.
[0052] The at least one secondary air duct also makes it possible
to provide a burner with lower nitrogen emissions, which burner can
operate in a sliding modulating manner. The sliding modulating
manner of operation can be achieved, inter alia, by what is
referred to as an air/fuel coupling (gas/air composite); in this
case, the pressure generated by the burner fan can be used for
activating the supply of gas. The gas pressure in this case
operates proportionally to the fan pressure. Through the use of
control of the rotational speed of the fan, the pressure which is
built up can therefore be changed and hence the air and supply of
gas adapted to the required output. The use of the secondary air
ducts also functions in this manner of operation, since the
premixing continues to take place substoichiometrically and the
secondary air can be conveyed a long way into the beam tube. A
further possibility constitutes the use of electronically
controllable gas valves for adapting the gas pressure and therefore
the burner output.
[0053] Furthermore, through the use of the at least one secondary
air duct, what are referred to as "hot spots," i.e. regions which
are untypically hot for the infrared tube heater and which are
locally limited and burn generally red to yellow, can be avoided on
and in the region of the beam tube in the vicinity of the burner.
The specific supplying of the secondary air over the outer region
of the beam tube effectively cools the latter and prevents the
possible resting of the flame against the inner wall of the tube.
The resting of the flame against the latter leads, in particular in
the case of burners of higher power, to burning tube points which
rapidly become worn because of the high thermal loading.
Furthermore, the flame temperature is reduced by the burning, which
initially proceeds substoichiometrically, and therefore, through
the reduction in the flame radiation in this region and stretching
of the burning zone, the thermal loading is more uniform over the
radiation tube.
[0054] Furthermore, the burner permits the production of an
ignitable fuel/air mixture under virtually all operating and
loading states due to partial premixing. The premixing takes place
in the mixing chamber. The secondary air ducts in this case do not
have any effect on the gas/air composition in the direct outlet
region downstream of the mixing chamber.
[0055] The secondary air is introduced at increased speed a long
way into the radiation tube through the secondary air ducts, which
are ideally constructed as a bore or nozzle, and therefore the
region of further mixing with the gas/air mixture can be delayed by
using flame diffusion. Due to this measure, complete burn-up can be
achieved by using diffusion through a graduated supply of the
secondary air during the further course of the flame.
[0056] The mixing unit 1 and the inlet nozzle 2 can be configured
in a solid monolithic construction in order to reduce sound
emissions from the burner and from the subsequent beam tube. The
complete mixer can be manufactured from two main parts, the inlet
nozzle and the mixing unit. These are fixedly connected to each
other and form a solid unit filling the full cross section of the
burner. Of course, the suppression of the sound emissions
originates firstly from the laminar flame. However, it can be
assumed that a reduction is achieved by using the construction and
the damping material properties.
[0057] As already indicated above, the fan G can also be disposed
downstream of the mixing unit 1 in the direction of flow.
Accordingly, the air would be sucked into the air inlet 15 of the
burner B.
[0058] An embodiment of the exhaust gas system as what is referred
to as a common exhaust gas system is also possible. What is
referred to as a common exhaust gas system denotes the parallel
exhaust gas convergence of two or more infrared tube heaters to
form an exhaust gas collecting line. The collecting line normally
contains a central exhaust gas fan for generating a negative
pressure at the burners, and also for removing the exhaust gases. A
burner fan is generally not used in exhaust gas collecting
systems.
[0059] The burner of the infrared tube heater according to the
invention also permits prevention of flame failure by using partial
premixing. The premixing produces an ignitable mixture, and should
the gas/air quantity be greatly reduced by using a low power
setting, the flame is withdrawn at maximum to the flashback guard.
Due to the low flow rate in the flame tube, the flame is not
extinguished.
[0060] The burner of the infrared tube heater according to the
invention also makes it possible to prevent lifting-off of the
flame by using partial premixing. At high power settings, an
ignitable gas/air mixture is likewise produced by the premixing.
The mixture burns shortly downstream of the flame tube. In the case
of systems without premixing, because of insufficient mixing, the
flame may lift off at high powers and associated high flow rates
and ignite only during the further course of the beam tube. In this
case, the burning flame is no longer detected by a flame monitoring
device integrated in the burner and the burner is automatically
switched off by an electronic control system.
* * * * *