U.S. patent application number 17/192428 was filed with the patent office on 2021-06-24 for gas burner system for a plurality of gas types.
This patent application is currently assigned to Gas-Fired Products Inc.. The applicant listed for this patent is Martin Brice, Stephan Richter, Tharwat Saad, Eddie Wilson. Invention is credited to Martin Brice, Stephan Richter, Tharwat Saad, Eddie Wilson.
Application Number | 20210190313 17/192428 |
Document ID | / |
Family ID | 1000005434559 |
Filed Date | 2021-06-24 |
United States Patent
Application |
20210190313 |
Kind Code |
A1 |
Brice; Martin ; et
al. |
June 24, 2021 |
GAS BURNER SYSTEM FOR A PLURALITY OF GAS TYPES
Abstract
The present invention is a system that utilizes high pressure
gas (greater than 1/2 psig) to control flow rate and gas discharge
velocity to enable interchangeability between a plurality of gases
without having to change the gas/air mixing venturi size or air
opening. A new approach is to use the available incoming higher gas
pressure to the appliance then control the volumetric flow rate
with the first orifice and then use a second orifice to change the
velocity of discharge into the gas/air mixing venturi of the burner
and therefore have adjustability of gas air mixing conditions
without having to change the burner system or air flow control even
when changing between very different fuel gases.
Inventors: |
Brice; Martin; (Charlotte,
NC) ; Richter; Stephan; (Charlotte, NC) ;
Wilson; Eddie; (Charlotte, NC) ; Saad; Tharwat;
(Huntersville, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Brice; Martin
Richter; Stephan
Wilson; Eddie
Saad; Tharwat |
Charlotte
Charlotte
Charlotte
Huntersville |
NC
NC
NC
NC |
US
US
US
US |
|
|
Assignee: |
Gas-Fired Products Inc.
Charlotte
NC
|
Family ID: |
1000005434559 |
Appl. No.: |
17/192428 |
Filed: |
March 4, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15407638 |
Jan 17, 2017 |
|
|
|
17192428 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F23D 2203/007 20130101;
F23D 14/64 20130101; F23K 5/007 20130101; F23D 14/20 20130101 |
International
Class: |
F23D 14/20 20060101
F23D014/20; F23D 14/64 20060101 F23D014/64; F23K 5/00 20060101
F23K005/00 |
Claims
1. A gas burner system for receiving a gas at a pressure higher
than 1/2 psig comprising: a first orifice including a diameter hole
of specific size to control the volumetric flow rate of a specified
fuel gas; a second orifice including a specific size to control the
discharge velocity of the gas, the first orifice fluidly connected
to the second orifice; a burner adapted to burn a gas/air mixture;
and a gas/air mixing venturi, including an air intake opening
adapted to receive the gas discharged from the second orifice and
air and adapted to uniformly mix the air and the gas for the
gas/air mixture.
2. The gas burner system of claim 1, wherein the first orifice is
connected to the outlet of a gas valve.
3. The gas burner system of claim 1, wherein the first orifice is
connected to the inlet of a gas valve.
4. The gas burner system of claim 1, wherein both the first and
second orifices each include a small opening and a larger
opening.
5. The gas burner system of claim 4, wherein the small opening of
the first orifice is smaller than the small opening of the second
orifice.
6. The gas burner system of claim 5, wherein the small opening of
the second orifice is oriented such that it is closer to the
gas/air mixing venturi than the larger opening of the second
orifice.
7. The gas burner system of claim 1, wherein the second orifice is
adapted to entrain air through the air intake opening due to the
velocity of the gas entering the gas/air mixing venturi.
8. The gas burner system of claim 1, wherein the first orifice
includes a fitting comprising a plurality of holes which are
adapted to be mechanically plugged, each of the plurality of holes
comprising a diameter for respective use with one of a plurality of
fuel gases.
9. The gas burner system of claim 1 whereby the first orifice
fitting has a plurality of holes which can be mechanically plugged
to enable use of a plurality of gas pressures for a single
fuel.
10. The gas burner system of claim 1 whereby the fuel gas
conversion is accomplished by only changing the first and second
orifices, but without alteration to the gas/air mixing venturi.
11. The gas burner system of claim 1, wherein there is no draft
inducer for combustion air.
12. The gas burner system of claim 1, further comprising a draft
inducer for combustion air.
13. The gas burner system of claim 1, further comprising a
plurality burners, each of the plurality of burners including a
second orifice fluidly connected with the first orifice.
14. A gas burner system for receiving a gas with a pressure higher
than 1/2 psig, comprising: a fitting including a first orifice, the
first orifice including a first end and a second end, the second
end including a diameter hole of specific size to control the
volumetric flow rate of a specified fuel gas; a burner assembly
comprising: a gas connection device spaced apart and separate from
the first orifice; a second orifice positioned within the gas
connection device and fluidly connected to the first orifice, the
second orifice including a specific size to control the discharge
velocity of the gas passing therethrough; a gas/air mixing venturi
including an air intake opening positioned to receive the gas
discharged from the second orifice and air, the gas/air mixing
venturi adapted to uniformly mix the air and the gas; and a burner,
wherein the second orifice is positioned within the gas connection
device, the second orifice is a specific size to control the
discharge velocity of the gas into the gas/air mixing venturi; a
hollow tube (3) including a first end engaging the first orifice
and a second end engaging the gas connection device, the first end
of the first orifice is in fluid communication with the gas flow
into the system, wherein the second end of the hollow tube is
positioned within the gas connection device and wherein the hollow
tube physically separates the first orifice and the gas connection
device.
15. The gas burner system according to claim 14, wherein the first
orifice has a small opening and a larger opening.
16. The gas burner system according to claim 14, wherein the second
orifice has a small opening and a larger opening.
17. The gas burner system according to claim 14, further comprising
a gas valve, wherein the first orifice is connected to the gas
valve.
18. The gas burner system according to claim 14, wherein the
fitting comprises a single disc which is mechanically held in place
in one of before and after a gas valve.
19. The gas burner system according to claim 14, wherein the
fitting comprises a plurality of first orifices and each of the
plurality of first orifices is sized to control the volumetric flow
rate of a respective fuel gas.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/407,638 entitled "GAS BURNER SYSTEM FOR A
PLURALITY OF GAS TYPES," filed on Jan. 17, 2017, which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention is a system that utilizes high
pressure gas (greater than 1/2 psig) to control flow rate and gas
discharge velocity to enable interchangeability between a plurality
of gases without having to change the gas/air mixing venturi size
or air opening.
BACKGROUND
[0003] Gas burner systems are typically designed for different
individual gas types ie. Propane, Butane, Natural Gas and in Europe
blended gases such as G25 which is a mixture of Natural Gas and
Nitrogen. Low pressure (under 14'' w.c.) atmospheric burners with
and without draft inducers are dependent on the velocity of gas
leaving the orifice to entrain the air for combustion. Because the
different gases have different physical properties the volume of
air to fuel ratio referred to as the flammability limits for gases
is different for each gas type.
[0004] Commonly in order to achieve the combustion characteristics
desired for each of these fuels it is necessary to make an
adjustment between the air openings in the burner, the burner
venturi diameter (or throat diameter) and the discharge gas
pressure from the orifice. The effect of these changes is to make
each of the designs potentially unique to the gas type supplied.
For example Propane C.sub.3H.sub.8 fuel has a specific gravity of
1.562 and requires 23.8 times the volume of air to fuel for perfect
combustion whereas Methane CH.sub.4 (Natural Gas) has a specific
gravity of 0.554 and requires 9.53 times the volume of air to fuel
for perfect combustion. Typically, in low pressure atmospheric
burners Propane is discharged at a pressure of 10.0'' w.c. or
greater whereas Natural gas is discharged between 2.5'' and 6.0''
w.c.
[0005] The fuels also have different calorific values where Propane
C.sub.3H.sub.8 fuel has a gross calorific value of 2524
Btu/ft.sup.3 and Methane CH.sub.4 (Natural Gas) has a gross
calorific value of 1012 Btu/ft.sup.3. The difference in the
calorific values of the fuels requires that the orifice sizes are
fixed to a certain diameter at a set pressure to give a specific
volumetric flow rate which determines the total heat input to the
burner system. The orifice diameter and setting pressure combine to
give a fixed velocity of discharge from the orifice of the gas
which cannot be adjusted without changing both the diameter and
pressure to give the same volumetric flow rate.
[0006] The combination of specific gravity and calorific value is
given by the Wobbe Index values which is the indices used to
determine the interchangeability of fuels. The Wobbe Index value
I.sub.W of a fuel gas is calculated by
I W = V C G S ##EQU00001##
where V.sub.C is the gross calorific value, G.sub.S is the specific
gravity of the fuel gas. If two fuels have identical Wobbe indices
then they are theoretically interchangeable at the same pressure to
give the same heat input. The interchangeability of fuels will
become even more challenging if LNG (Liquid Natural Gas) and CNG
(Compressed Natural Gas) are distributed with a wider tolerance of
Wobbe Index values than the traditional supplied Natural Gas that
appliances are currently designed for.
[0007] In the event that different value gases are used in the same
burners systems adjustments are necessary to not only maintain heat
input rate but also flame stability where the discharge speed from
the burner port must be controlled so that it is not too fast which
will cause a flame to lift from the port and extinguish or too slow
that the flame can light back inside the burner causing incomplete
combustion.
[0008] The interchangeability becomes a challenge in the event that
burners need to be converted between fuel types retrospectively.
This is particularly common where an existing application is
designed for Propane and in the future Natural Gas becomes
available at which point the unit will need to be converted. It is
common in this case to change the orifice size and have a means to
adjust the gas pressure to the orifice by means of a pressure
regulator. It becomes more complicated for field retrofit if the
actual gas/air mixing venturi system has to be replaced or
mechanically modified to enable interchangeability. In certain
instances, the entire gas train has to be replaced with a gas train
suitable for the fuel if the pressure regulator is not adjustable
to the pressure desired. The future challenge with wider range of
Wobbe index gas types is that the adjustment necessary to maintain
good flame stability and maintain heat input rates with current
burner technology will require the use of an air control device
(such as a shutter) or different venturi diameter or burner
dimensions.
[0009] This invention makes use of the fact that gas supply
distribution systems are at higher pressures than the pressure used
at the appliance from 2 psi upwards and typically when the gas is
distributed within the building it is reduced by a regulator
externally to 1/2 psig (14'' w.c.). The system disclosed takes
advantage of the availability of higher pressure gas where gas can
be distributed within the building at the available higher pressure
to the appliance.
[0010] Gas burner systems that incorporate heat exchangers and/or
are to be vented outdoors may have to employ a draft inducer to
move the combustion air and combustion gasses through the system. A
draft inducer is designed to overcome the flow resistance of the
combustion gasses inside a heat exchanger and/or overcome the
resistance of a chimney.
SUMMARY OF THE INVENTION
[0011] A new approach is to use the available incoming higher gas
pressure to the appliance then control the volumetric flow rate
with the first orifice and then use a second orifice to change the
velocity of discharge into the gas mixing venturi of the burner and
therefore have adjustability of gas air mixing conditions without
having to change the burner system or air flow control even when
changing between very different fuel gases.
[0012] With the present invention, the gas is supplied to the
appliance at a regulated pressure higher than the pressure it will
operate at. Typically, 2 psig or greater supply pressure. The
present system incorporates combination of a first orifice where
the diameter is specific to give a fixed volumetric flow rate for a
specific fuel at a specific supply pressure communicating with gas
shut off device to isolate the gas when the appliance is not in
operation and a second orifice with a larger diameter that is the
specific diameter to control the discharge speed for a specific
fuel gas into the gas mixing venturi of the burner system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The drawings are to help illustrate the concepts of the
present invention but are not intended to be an accurate
dimensional representation of the gas burner system.
[0014] FIG. 1 is a partial sectional view of the gas burner system
of the invention.
[0015] FIG. 2 is an enlarged sectional view of the first orifice
(2) shown in FIG. 1.
[0016] FIG. 3 is a sectional side view of an optional first orifice
(2).
[0017] FIG. 4 is sectional side view of another optional first
orifice (2) with multiple outlet openings.
[0018] FIG. 5 is an enlarged sectional view of the second orifice
(5) as shown in FIG. 1.
[0019] FIG. 6 is a partial sectional view of the gas burner system
of the invention incorporating a draft inducer.
DESCRIPTION OF THE GAS BURNER SYSTEM
[0020] The system of the present invention has a gas valve to
isolate the gas when the appliance is not in operation, a first
small diameter precise drilled orifice that controls the volumetric
flow rate of the gas. The first orifice can be one of many
different diameters depending on the fuel gas and pressure supplied
to the appliance. The gas is transported to the second larger
diameter precise drilled orifice which controls the discharge
velocity of the gas into a gas/air mixing venturi device.
[0021] The system can be adapted to interchange between any
plurality of fuel gases such as Natural Gas, Propane and Butane
without the need to change any of components in the system other
than the first and second orifice. The fitting for the first
orifice can be arranged to have multiple diameter holes where the
holes can be plugged to make the change between gases possible with
only changing the second orifice.
[0022] In viewing FIG. 1 of the drawing the gas burner system of
the present invention is indicated by reference numeral 10. A gas
valve 1 is connected to a gas source, not shown. A first orifice 2
may be connected to either the inlet or the outlet of gas valve 1
or may be positioned anywhere in the assembly prior to a second
orifice 5, as long as it is fluidly connected with the gas flow. As
shown in FIG. 2 the first orifice (2) has a small opening 11 at one
end communicating with the controlled volumetric flow side and can
have a larger opening 12 at the other end communicating with the
supply pressure, it could be positioned either with the small
opening towards the gas valve or away from the gas valve. As shown
in FIG. 3 the orifice (2) may optionally be a small hole 13 in a
single disc 14 which is mechanically held in place either before or
after the gas valve 1. Optionally first orifice 2 may have the
configuration shown in FIG. 4, wherein the first orifice 2, can be
a single fitting 15, having a plurality of holes 16 and 17 wherein
one or more of the individual holes 16 and 17 can be plugged 18, if
desired, to enable a single fitting 15 to be suitable for a
plurality of fuel gases or supply pressures. The function of the
first orifice is to control the volumetric flow rate of the fuel
gas supplied at a pressure higher than 1/2 psig.
[0023] As shown in FIG. 1, a hollow tube 3 fluidly communicating
with the first orifice 2 and the burner assembly 8. The burner
assembly 8 has a gas connection device 4 fluidly connected to tube
3, thus capable of supplying gas to the burner assembly. Positioned
within the connection device 4 is a second orifice 5 that delivers
the gas to the gas/air mixing venturi 6. As illustrated in FIG. 5,
the second orifice 5 has a small opening 19 and a larger opening
20. The size of the small opening 19 of the second orifice 5 is
larger than the small opening 11 of the first orifice 2. As shown
in FIG. 3 the second orifice 5 may optionally be a small hole 13 in
a single disc 14 which is mechanically held in place immediately
prior to the gas/air mixing venturi 6. The function of the second
orifice is to control the discharge velocity for a specific
gas.
[0024] The gas/air mixing venturi 6 has an air intake opening 9
sized to permit proper mixing of the gas (from second orifice 5)
with the air. The flow of air into the gas/air mixing venturi
occurs because the air is entrained or induced into the mixing
apparatus due to the flow of gas out of the second orifice 5. The
gas/air mixing venturi 6 is fluidly connected to burner 7. The
details of the burner 7 do not constitute any specific part of the
present invention, other than the requirement of a burner. Thus,
the burner assembly 8 constitutes the gas connection device 4, the
gas/air mixing venturi 6, the second orifice 5, air intake opening
9 and the burner 7.
[0025] As shown in FIG. 6 is an alternate gas burner assembly
incorporating a draft inducer 21.
[0026] Thus, in accordance with the details and scope of the
present invention, all features, details and obvious variations of
the present invention are within the scope of the present
invention.
* * * * *