U.S. patent number 3,698,378 [Application Number 04/744,582] was granted by the patent office on 1972-10-17 for smooth top gas range.
This patent grant is currently assigned to Institute of Gas Technology. Invention is credited to Esher R. Kweller, Robert B. Rosenberg, William R. Staats.
United States Patent |
3,698,378 |
Rosenberg , et al. |
October 17, 1972 |
SMOOTH TOP GAS RANGE
Abstract
A smooth top gas range which includes a hood that draws cooking
vapors and fumes and air into a regenerative type heat exchanger
for preheating prior to combustion with gas at the burner surface
unit. Each burner unit is enclosed in a separate combustion
compartment with heat being transmitted to a cooking vessel through
an air impervious compartment wall or plate by means of radiation.
The combustion products exhaust from the combustion compartment,
are cooled to a safe temperature by the heat exchanger and are
finally vented to the room.
Inventors: |
Rosenberg; Robert B. (Evergreen
Park, IL), Kweller; Esher R. (Downers Grove, IL), Staats;
William R. (Chicago, IL) |
Assignee: |
Institute of Gas Technology
(N/A)
|
Family
ID: |
24993239 |
Appl.
No.: |
04/744,582 |
Filed: |
July 12, 1968 |
Current U.S.
Class: |
126/39R; 126/39J;
165/7; 219/400; 126/299D; 165/909 |
Current CPC
Class: |
F24C
3/047 (20130101); F24C 15/2042 (20130101); Y10S
165/909 (20130101) |
Current International
Class: |
F24C
3/04 (20060101); F24C 3/00 (20060101); F24C
15/20 (20060101); F24c 003/00 (); F24c
015/20 () |
Field of
Search: |
;126/299,299A,299B,39,39H,39J,21A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Myhre; Charles J.
Claims
What is claimed is:
1. A top burner installation for removing vapors, fumes and odors
generated above said top comprising, in combination:
at least one burner;
an air impervious cooking surface over said burner forming one wall
of a burner combustion chamber;
means for drawing said vapors and air from the region above said
cooking surface and directing said vapors and air to said burner
combustion chamber, said means including a hood over said cooking
surface, and circulating means for directing said vapors and air to
said burner combustion chamber;
means for exhausting combustion products from said burner
combustion chamber; and
heat exchanger means positioned simultaneously within the path of
said vapor and air and said combustion products to preheat said
vapor and air prior to combustion in said burner combustion chamber
and to cool said combustion products subsequent to discharge from
said burner combustion chamber.
2. The installation of claim 1 wherein said burner is a gas burner
and including combustible gas supply means to provide a source of a
gas hydrocarbon fuel to said burner.
3. The installation of claim 1 wherein said heat exchanger means
comprises
a first chamber for receiving vapor and air
a second chamber for receiving said combustion products adjacent
said first chamber, and means interconnecting said chambers for
removing heat from combustion products for heating said vapor and
air mixture.
4. The installation of claim 3 wherein said means for removing heat
and heating said vapor and air comprise a regeneration wheel
revolving about an axis between said first and second chambers to
transfer heat from said second to said first chamber.
5. The installation of claim 1 wherein said burner chamber is
divided by a gas burner into two separate regions separated by said
burner such that all vapors and air pass through said burner as
primary air for combustion.
6. The installation of claim 1 wherein said circulating means
comprise ducts leading from said hood to said heat exchanger means,
said ducts including circulating fans for driving said air, vapor
and combustion products from above said surface to said heat
exchanger and thence through said burner to said heat
exchanger.
7. The installation of claim 1 including flow passage valve means
between said heat exchanger and said burner combustion chamber
adapted to open when said burner is turned to an on position
thereby allowing vapor and air to be drawn into said burner
combustion chamber for combustion.
8. The installation of claim 1 wherein said heat exchanger means
also comprises said means for drawing vapors and air from the
region above said cooking surface.
9. The installation of claim 1 wherein said heat exchanger means is
positioned in said hood.
10. A top burner installation for removing vapors, fumes and odors
generated above said top comprising, in combination:
at least one burner;
an air impervious cooking surface over said burner forming one wall
of a burner combustion chamber;
means for drawing said vapors and air from the region above said
cooking surface and directing said vapors and air to said burner
combustion chamber;
means for exhausting combustion products from said burner
combustion chamber;
heat exchanger means positioned simultaneously within the path of
said vapor and air and said combustion products to preheat said
vapor and air prior to combustion in said burner combustion chamber
and to cool said combustion products subsequent to discharge from
said burner combustion chamber, said heat exchanger means including
a first chamber for receiving vapor and air, a second chamber for
receiving said combustion products adjacent said first chamber, and
a regeneration wheel heat exchanger revolving about an axis between
said first and second chambers to transfer heat from said second to
said first chamber.
11. The installation of claim 10 wherein said burner is a gas
burner and including combustible gas supply means to provide a
source of a gas hydrocarbon fuel to said burner.
12. The installation of claim 10 wherein said burner chamber is
divided by a gas burner into two separate regions separated by said
burner such that all vapors and air pass through said burner as
primary air for combustion.
13. The installation of claim 11 including flow passage valve means
between said heat exchanger and said burner combustion chamber
adapted to open when said burner is turned to an on position
thereby allowing vapor and air to be drawn into said burner
combustion chamber for combustion.
14. The installation of claim 10 wherein said heat exchanger means
also comprises said means for drawing vapors and air from the
region above said cooking surface.
15. The installation of claim 10 wherein said means for drawing and
directing vapors comprises
a hood over said cooking surface, and
circulating means for directing said vapor and air through said
heat exchanger to said burner combustion chamber.
16. The installation of claim 15 wherein said circulating means
comprise ducts leading from said hood to said heat exchanger means,
said ducts including circulating fans for driving said air, vapor
and combustion products from above said surface to said heat
exchanger and thence through said burner to said heat
exchanger.
17. The installation of claim 15 wherein said heat exchanger means
is positioned in said hood.
18. A top burner installation for removing vapors, fumes and odors
generated above said top comprising, in combination:
at least one burner;
an air impervious cooking surface over said burner forming one wall
of a burner combustion chamber;
means for drawing said vapors and air from the region above said
cooking surface and directing said vapors and air to said burner
combustion chamber;
means for exhausting said combustion products from said burner
combustion chamber;
heat exchanger means positioned simultaneously within the path of
said vapor and air and said combustion products to preheat said
vapor and air prior to combustion in said burner combustion chamber
and to cool said combustion products subsequent to discharge from
said burner combustion chamber; and
flow passage valve means between said heat exchanger and said
burner combustion chamber adapted to open when said burner is
turned to an on position thereby allowing vapor and air to be drawn
into said burner combustion chamber for combustion.
19. The installation of claim 18 wherein said burner is a gas
burner and including combustible gas supply means to provide a
source of gas hydrocarbon fuel to said burner.
20. The installation of claim 18 wherein said means for drawing and
directing vapors comprises
a hood over said cooking surface, and
circulating means for directing said vapor and air through said
heat exchanger to said burner combustion chamber.
21. The installation of claim 18 wherein said heat exchanger means
comprises
a first chamber for receiving vapor and air
a second chamber for receiving said combustion products adjacent
said first chamber, and means interconnecting said chambers for
removing heat from combustion products for heating said vapor and
air mixture.
22. The installation of claim 21 wherein said means for removing
heat and heating said vapor and air comprise a regeneration wheel
revolving about an axis between said first and second chambers to
transfer heat from said second to said first chamber.
23. The installation of claim 18 wherein said burner chamber is
divided by a gas burner into two separate regions separated by said
burner such that all vapors and air pass through said burner as
primary air for combustion.
24. The installation of claim 20 wherein said circulating means
comprise ducts leading from said hood to said heat exchanger means,
said ducts including circulating fans for driving said air, vapor
and combustion products from above said surface to said heat
exchanger and thence through said burner to said heat
exchanger.
25. The installation of claim 18 wherein said heat exchanger means
also comprises said means for drawing vapors and air from the
region above said cooking surface.
26. The installation of claim 20 wherein said heat exchanger means
is positioned in said hood.
Description
BACKGROUND OF THE INVENTION
This invention relates to a smooth top gas range which safely
discharges combustion products indoors, and more particularly, to a
gas fired smooth top range which draws cooking vapors and fumes
from above the cooking surface for complete combustion at the
separate burner units.
Huebler et al., in an application filed Nov. 23, 1966, Ser. No.
596,521, now U.S. Pat. No. 3,416,509, discloses a self-cleaning gas
oven. Hurko in U.S. Pat. No. 3,121,158, had earlier disclosed a
self-cleaning electric oven. While very useful for their intended
purpose, these inventions do not provide a solution to the problems
of dirty surface burner units or fumes, odors and vapors emanating
from foods cooking on surface burner units. Since most cooking is
done on the top surface of the family range or stove, keeping the
top burner units clean as well as keeping the kitchen free from
odors and fumes are more frequent as well as more serious problems
than the cleanliness of the oven.
Generally the surface units of a range heat the cooking vessel
directly by conduction and convection. Thus, a gas flame impinges
on the bottom of a pan. When cooking, not only are fumes, etc.
released to the kitchen by such an arrangement, but also spilled
food, etc. tends to collect at or in the burner units thereby
providing much additional cleaning work for the housewife, and also
providing a potential hazard to safety and health.
To eliminate dirty burners, engineers have designed burner units
which can be easily removed for cleaning, drip pans, etc. These do
alleviate somewhat the tedious cleaning chore. Nevertheless, the
problem of dirty burner units still plague most homemakers.
To cope with fumes, hoods are often installed. This is an expensive
solution and also requires filter systems and external venting.
Moreover, many housewives neglect to turn the hood on when cooking
or refuse to do so because hoods are often noisy.
Hess U.S. Pat. No. 2,908,267 teaches another method of controlling
cooking vapors. Hess circulates the vapors by means of ducts
leading from above the burner surface to a combustion chamber
housing the surface burner. The drawback of Hess results from
cooking vapors which tend to cool before entering the burner
combustion chamber. They may condense and collect on the duct walls
providing a potential ignition hazard which may also clog the duct
work and burners. Finally Hess must discharge combustion products
outdoors to insure complete safety without indoor odors. This
provides an additional expense.
The present invention presents as a solution to these problems a
novel gas range which essentially eliminates dirty burners and
cooking vapors by providing for circulation of cooking vapors
through a heat exchanger prior to combustion in a burner combustion
chamber beneath the air-impervious surface of each burner unit. The
range is thus a smooth top gas range having an air-impervious plate
between the heating element or flame and the vessel being heated.
The present invention also reduces the amount of heat discharged to
the room by means of the same heat exchanger used to heat the
cooking vapors. By virtue of the heat exchanger, less fuel is
required to perform the same cooking operation as compared to prior
art ranges without a heat exchanger.
SUMMARY OF THE INVENTION
In a principal aspect the present invention of a smooth top gas
range comprises at least one smooth top gas burner with means for
drawing vapors from the region above the cooking surface and
directing the vapors along with air to combust at the burner below
the cooking surface. The vapor and air mixture passing into the
burner is preheated by passage through a heat exchanger prior to
combustion. Exhaust products are expelled from the burner and
cooled by passage through the same heat exchanger.
It is thus an object of the present invention to provide a
self-cleaning smooth top gas range.
It is a further object of the present invention to provide a
self-cleaning smooth top gas burner installation in which the
combustion products are discharged indoors with full assurance of
complete and safe combustion.
Another object is to provide a smooth top gas range which inhibits
formation of vapor and dirt deposits at the burner surfaces and
which also can be easily cleaned at the burner surfaces.
Still another object of the present invention is to provide a
self-cleaning smooth top gas range which may be economically
manufactured.
Another object is to provide a self-cleaning smooth top gas range
which is more economical to operate than prior art ranges.
Another object of the present invention is to provide a
self-cleaning smooth top gas range with a minimum of moving parts
that provides complete combustion at the burners of vapors drawn
from above the smooth top surface of the range.
Another object is to provide a self-cleaning smooth top gas range
that discharges less heat to the kitchen than prior art ranges.
These and other objects, advantages and features of the invention
will be more fully understood and appreciated by reference to the
following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
In the detailed description which follows, reference will be made
to the drawings comprised of the following figures:
FIG. 1A is a schematic, cross sectional view of a first preferred
embodiment of the self-cleaning smooth top gas burner installation
of the present invention;
FIG. 1B is a schematic, cross sectional view of a second embodiment
of the self-cleaning smooth top gas burner installation of the
present invention showing an alternate location of the regenerator
assembly described below;
FIG. 2 is a cross sectional view showing the regeneration wheel of
the heat exchanger as utilized in the invention taken substantially
along the line 2--2 of FIG. 1B;
FIG. 3 is a schematic, perspective view of an embodiment of the
invention showing the combination of the heat exchanger with the
smooth top gas burners; and
FIG. 4 is a schematic, cross sectional view of an alternative
embodiment of a smooth top gas burner in combination with a heat
exchanger as contemplated by the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 1A and 1B illustrate two embodiments of the invention, and
the apparatus illustrated in these two FIGURES is substantially
similar. Therefore numeration of these FIGURES is identical except
where differences in construction are evident. Where the FIGURES
have non-identical numeration, the differences in construction are
explained.
FIG. 1A illustrates, in a schematic, cross sectional view the
preferred embodiment of a typical hood 7 and a smooth top gas range
8 combination utilizing the principles of the present invention.
FIG. 1B illustrates a second embodiment. For purposes of
illustration, only one burner unit is illustrated in FIGS. 1A and
1B. The invention is, however, not limited to the single burner
construction shown in these FIGURES and described below. Rather, it
is contemplated that a plurality of burner units will be used in
combination with each smooth top gas range and hood. FIG. 3
illustrates a possible configuration in a four burner unit
range.
The gas range 8 includes a top burner section, generally shown at
9, having a smooth top surface 10. An air impervious burner plate
12 is shown in FIGS. 1A and 1B over each burner unit position. This
plate 12 is not a limiting feature of the invention. The plate 12
or its equivalent or substitute must, however, be air impervious
and, as described below, form the top wall of a combustion chamber
or compartment for the burner units. Pots, pans or other cooking
vessels are placed on the burner plate 12 and heated by energy
passing through the plate 12. Heat passes through the burner plate
12 by means of conduction and, primarily, radiation. The amount of
heat passing through the plate and the speed with which it passes
may be enhanced and predicted by the use of materials and methods
well known by those skilled in the art of gas cooking devices.
Preferably, the plate 12 is insulated by a plate insulating ring 13
to prevent conduction of heat to top surface 10.
The burner plate 12 is heated by the combustion of gas (a
hydrocarbon fuel) and air in a burner unit 14 positioned in a
burner chamber 16 defined beneath plate 12. Gas is provided through
a conduit 18 to the burner 14 whenever the control valve 20 is
turned to an open position by movement of the control knob 22. Gas
is supplied through the valve 20 to the conduit 18 by a main gas
supply line 24. When the control valve 20 is turned on, gas
pressure closes a pressure switch 26. When the pressure switch 26
is closed, a gas solenoid valve 28 opens permitting gas to flow
through the conduit 18 to the burner 14 for combustion; at the same
time a valve as schematically shown at 42 in FIGS. 1A, 1B or 3
(solenoid or bimetal operated) at the inlet air supply duct as at
68 in FIG. 3 is raised allowing air to pass into compartment or
chamber 16. Therefore air is supplied only to those burners which
are turned on. Simultaneously, as described below, the motors and
valves used in combination with the heat exchanger regeneration
unit described below are turned on. Thus, by turning on a single
burner, all of the components in the range are activated to insure
complete and safe combustion of all gas and air.
Various other safety features may also be included to insure that
the gas burner ignites or turns off if not properly ignited. For
example, a flame prover may be used when the surface 10 is opaque
and ignition of the burner 14 is not visually observable. A flame
prover comprises a rod placed above the flame in the burner 14. The
rod includes a bimetallic strip which deactivates a safety switch
when heated within a certain specified time. Failure of the flame
to ignite and heat the rod will result in activation of a lockout
switch which closes solenoid 28 and conduit 18 thus closing off the
supply of gas to the burner 14. Other flame proving devices are
available. For example, a spark ignition system may be utilized
wherein electrical impedance is used to monitor the presence of a
flame.
Another safety device may be used to insure that air for combustion
is flowing into the burner 14. For example, a sail switch may be
placed in the path of air leading to the burner 14. When air is
being provided as required (in a manner to be more fully described
below) to the burner 14, the sail switch would be forced to close
and not prevent gas flow through conduit 18. If, however,
combustion air were lacking, a sail switch would open
simultaneously closing off conduit 18.
Referring now to FIG. 1A, there is shown the preferred arrangement
of a heat exchanger 41a in combination with a hood 7a positioned
above the top surface 10 of the range 8. Here the construction of
the range in FIG. 1A differs from that in FIG. 1B described below.
The heat exchanger 41a is positioned in the hood 7a and serves to
heat incoming vapors and air and cool exiting combustion products.
This results in reduction of vapors, etc. to the room and also
increases the efficiency of the range. Thus cooking vapors and air
entering through a filter 32 are driven by a fan 38a into a lower
or first regeneration chamber 40a where they are heated and finally
into an input duct 36a leading to the combustion chamber 16. The
direction of flow is denoted by arrows.
The heated vapor and air mixture combusts with gas in chamber 16.
Combustion products from the combustion chamber 16 then exit
through a duct 47a to a second or upper regeneration chamber 44a
where they are cooled. These combustion products are drawn through
duct 47a and chamber 44a by a fan 46a. The cooled combustion
products finally exit to the room at a safe, low temperature.
The entering cooking vapors and air are heated and the exiting
combustion products are cooled by means of the rotating
regeneration wheel 48, more fully described below. The wheel 48 is
driven by a motor 50.
The embodiment of FIG. 1A is preferred because vapor and
grease-laden air entering through the filter 32 is immediately
preheated by the heat exchanger 41a. By contrast, the embodiment
shown in FIG. 1B, described below, includes a heat exchanger 41b
which is positioned in the main body of the range 8 rather than in
a hood 7b. Thus in the embodiment of FIG. 1A, vapor will not
condense in the duct 36a since it is heated by heat exchanger 41 as
before entering the duct 36a. Also duct 36a is shown flush with
duct 47a resulting in some heat transfer. However this heat
transfer is not a requisite to prevent condensation. The exterior
surface of ducts 36a and 47a are preferably insulated however.
Positioned above the top surface 10 of the range 8 is the hood 7b.
The hood 7b is typical of those well known in the art, as compared
to the hood 7a in FIG. 1A, which is modified to include the heat
exchanger 41a. The hood 7b extends over the entire top surface 10
and may or may not include a filter screen, as at 32. A squirrel
cage fan 34 driven by an electric motor (not shown) draws the air
and vapors given off by cooked foods and other materials over the
top surface 10, through the filter 32 and into a duct 36b. Note
that the fan 34 is an additional required part of the range shown
in FIG. 1B as compared to the range shown in FIG. 1A.
The air and vapor mixture is directed as shown by the arrows down
the duct 36b to the back of the range 8. An electrical powered fan
38b assists in drawing the air and vapor down the duct 36b. The fan
38b directs the air and vapor mixture into a first or lower
regeneration chamber 40b of a heat exchanger 41b. The air and vapor
mixture is heated in the first regeneration chamber 40b and
directed through an air solenoid valve 42 into the burner chamber
16 of burner 14. There the air and vapor mixture passes upward
through the chamber 16 and the burner 14 to combine with gas at the
surface of the burner 14 for ignition and combustion.
The combustion products exit from the upper part of the burner
chamber 16 into an upper or second regeneration chamber 44b of the
heat exchanger 41b positioned directly above the first regeneration
chamber 40. A second electrically driven fan 46b assists in drawing
the combustion products from the burner chamber 16 and through the
upper chamber 44b. When the combustion products are in the second
chamber 44b, heat is withdrawn therefrom and utilized to heat the
incoming air and vapor mixture in the first chamber 40.
Finally the cooled combustion products are exhausted to the
atmosphere indoors. Rather than being directly exhausted into the
indoor atmosphere, the cooled combustion products may be made to
pass through a duct 47b which in combination with duct 36b defines
an annular space about the incoming duct 36b. Preferably the outer
duct 47b exhausts above the hood 7b to prevent unnecessary
recirculation of the combustion products. Such an annular
configuration further serves to preheat the incoming air and vapor
mixture and simultaneously cool the exiting or exhausting
combustion products.
In the arrangement shown in FIG. 1-B, condensation in the duct 36b
is prevented by transferring heat from combustion products flowing
through duct 47b to the wall of duct 36b and then to the incoming
air in duct 36b. To do this a higher exhaust temperature from the
heat exchanger 41b is required in the range of FIG. 1B than from
the exchanger 41a in the range of FIG. 1A with a resultant decrease
in efficiency of heat transfer for the regenerator wheel 48. For
this reason the range of FIG. 1A is preferred. In this arrangement
shown in FIG. 1B heat transfer between the ducts 36b and 47b is
desirable. Therefore, 36b is surrounded by 47b to obtain greater
heat transfer surface area.
Preferably the vapor and air mixture is preheated and the
combustion products are simultaneously cooled by means of a
regenerative type heat exchanger and more particularly a heat
exchanger which includes a regeneration wheel 48. Wheel 48 is
pivotally mounted on a shaft 49 to rotate between the first and the
second regeneration chambers 40 and 44 respectively. An electric
motor 50 drives the shaft 49 and attached wheel 48 to provide for
the exchange of heat between chambers 40a and 44a or 40 b and 44b.
Heat is absorbed by the vapor and air mixture in the first chamber
40a or 40b whereas heat is given off by the combustion products to
the regeneration wheel in the second chamber 44a or 44b. The
construction of the wheel 48 and its mode of operation is described
in the copending U.S. application, Ser. No. 596,521, filed Nov. 23,
1966 by Huebler et al., now U.S. Pat. No. 3,416,509.
Briefly, as an example of a typical installation, the regeneration
wheel has an effective cross section of about 6 inches in diameter
and a thickness of 3 inches. The wheel is made of asbestos
impregnated with sodium silicate. As illustrated in FIG. 2 the
cross sectional configuration of the wheel corresponds to layers of
corrugated paper annularly positioned one on top of the other about
the central shaft 49. Whereas the cross sectional configuration of
the wheel 48 shown in FIG. 2 comprises corrugations, other designs
may be used as long as a plurality of small axial passages are
provided parallel to the shaft 49 for the flow of combustion
products or an air and vapor mixture as the case may be. The
regeneration wheel 48 may be made of any heat-resistent material,
preferably one that has a high heat capacity such as asbestos,
asbestos impregnated with sodium silicate or a ceramic or refactory
material such as Corning's Cercor.
Typically, the wheel 48 rotates about shaft 49 at 5 r.p.m. The hot
exiting exhaust or flue gases pass through the upper half of the
wheel 48 in chamber 44a or 44b giving up heat to the wheel 48. The
wheel 48 rotates continuously so that the hot half of the wheel 48
is then exposed at its lower half in chamber 40a or 40b to incoming
vapor and air mixture which cools the wheel 48 and heats the
mixture. It is to be understood that the dimensions of the
regeneration wheel and its rate of rotation are not critical and
are functions of burner size, number of burners and temperature
requirements. Those skilled in the art will recognize that the
parameters can be adjusted within the skill of the art to provide
the cooling effect desired for any combination and size of
burners.
As disclosed in the copending application by Huebler referred to
above, the chambers 40a and 44a or 40b and 44b are sealed from one
another even though the wheel 48 is made to rotate. This is to
prevent leakage of the gases between the chambers 40a and 44a or
40b and 44b. The sealing means consists of a pair of flanged rings
54 and 56 which are adapted to fit into annular grooves 55 and 57
respectively defined in the wheel 48. The rings 54 and 56 are
securely connected to the walls of the regeneration chambers 40a
and 44a or 40b and 44b so that the wheel 48 may rotate without
interfering with the rings 54 and 56. The grooves 55 and 57 in the
wheel are formed by pressing the flange of a ring 54 or 56 into the
relatively soft asbestos material of the wheel 48 and rotating the
wheel 48 about the shaft 49 until a suitable clearance is obtained.
Alternative methods of sealing may also be utilized.
Also along each face of the wheel 48 there are provided wipers 60
and 62 of tubular or flat configuration, for example, a roll of
glass fiber material. The wipers 60 and 62 serve to prevent flow of
gas between the first 40a or 40b and second 44a or 44b chambers
across the face of the wheel 48. FIG. 2 shows how wiper 60 fits
across the face of regeneration wheel 48.
It has been found desirable to supply air to the burner in an
amount in excess of the stoichiometric amount required for complete
combustion to carbon dioxide and water vapor of the gas and vapors
introduced at the burner 14. By way of example but not by way of
restriction the following temperatures and flow rates are presently
preferred with four burners operating at rated input to the
burners:
Gas input 34,000 Btu/hr Air input 6,000 cubic feet per hour (100
cfm) Exhaust temp. 200.degree. F.
the exhaust temperature of 200.degree. F. for the smooth-top gas
range is much lower than the exhaust gas temperature of a
conventional open-top gas burner. For example, a conventional top
burner operating with the usual 50 percent efficiency (50 percent
of burner input transferred to the pot and its contents) loses 50
percent of its rated input to the kitchen by way of the hot exhaust
gases. Four conventional top burners operating at total rated input
of 42,000 Btu/hr discharges 21,000 Btu/hr to the kitchen by the
exhaust. The smooth top gas range discharges approximately 13,000
Btu/hr to the kitchen by the exhaust. A gas savings of 8,000 Btu/hr
results and is reflected in a reduced gas input for the smooth-top
gas burners.
The types of burners that may be used in practicing the invention
are not limited. There is illustrated in FIG. 1 a burner 14 which
divides the burner chamber 16 into two portions. The incoming air
and vapor mixture all pass through the burner 14 as primary air.
FIG. 3 illustrates a burner 64 of the type wherein the air and
vapor mixture may pass around the sides of the burner 64 to combust
with the gas as secondary air as well as through the burner 64 as
primary air. It is important, however, that the burner chamber as
at 16 in FIG. 1 be sealed against the smooth top surface 10 of the
range to insure that the incoming air and vapor mixture and the
exhaust gases are properly directed and do not leak or stray from
their described paths. This burner chamber 16 provides the only gas
flow pathway from the lower heat exchanger chamber 40a or 40b to
the upper heat exchanger chamber 44a or 44b respectively.
FIG. 3 also illustrates the construction of a multiburner, smooth
top, gas range utilizing the present invention. In FIG. 3 the
incoming air and vapor mixture from a hood passes through the
regeneration wheel 63 and into a central regeneration chamber 66
whenever a burner, as at 64, is turned on. The air vapor mixture
then passes in through a duct, as at 68, and into the burner
chamber 70 for burner 64. The combustion products of burner 64 are
directed to an exit duct defined by duct halves 71 and 72, duct
half 72 being attached to the bottom of top surface 74. The
combustion or exhaust products then pass through the top half of
regeneration wheel 63 and into the atmosphere.
FIG. 4 illustrates an alternative embodiment of the burner
construction for a smooth top gas range installation of the present
invention. An incoming air and vapor mixture passes from a hood
(not shown), through a duct 75 and the top half of a regeneration
wheel 76. The mixture is then directed through a duct 77 to a
burner chamber 78 beneath the burner surface 79. There the vapor
and air mixture is ignited with gas coming in through the burner
80. The combustion products are then drawn down through a porous
plate or screen 82 into an exit duct 84. Finally the exhaust
products are cooled by regenerator wheel 76 in the manner
previously described and discharged to the atmosphere. The
combustion of the gas vapor and air mixture heats the surface 78 by
radiation and conduction. The flow of gases has been reversed in
the embodiment shown in FIG. 4 in relation to those previously
described.
Thus, it can be seen that by utilizing the construction of the
present invention, cooking vapors which often fill a kitchen with
obnoxious or bothersome odors and fumes may be drawn from above the
cooking surface and directed to the burner which is responsible for
the cooking operation. There the fumes are completely combusted
into carbon dioxide and water vapor. The combustion products may
then be safely discharged into an indoor room. Substantial savings
are realized by doing away with the need for costly outside
venting. Such applications will have special economic importance in
commercial installations. Increased safety factors are also
exhibited by the presently claimed invention since turning the
burner control knob handle simultaneously activates the motors and
valves providing a path for the gas which is to be combusted as
well as the incoming air and vapor mixture and exhaust
products.
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