US20060088794A1

US20060088794A1 - Superheating burner with turbulence ring

Info

Publication number: US20060088794A1
Application number: US10/972,454
Authority: US
Inventors: James Purcell
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-10-26
Filing date: 2004-10-26
Publication date: 2006-04-27

Abstract

A device for combusting liquid fuel includes a cylinder sealed at both ends by respective annular seals. The liquid fuel is vaporized and flows through a tube extending into a sealed space between the cylinder walls. The tube is removably sealed to an end of an air mixing barrel that extends into the cylinder. The air mixing barrel has a plurality of air intake holes and a plurality of gas spray holes through which the vaporized fuel/air mixture exits. The device also includes a turbulence ring that is rotatably adjustable about a second end of the air mixing barrel. The air mixing barrel also includes an orifice that increase a pressure in the orifice to decrease carbon monoxide emissions.

Description

FIELD OF THE INVENTION

The invention relates to a device and a method for superheating a gas to reduce carbon monoxide emissions.

BRIEF SUMMARY OF THE INVENTION

An object of the invention is to provide a fuel burner that reduces carbon monoxide emissions while maintaining or reducing oxides of nitrogen (NO_x) emissions.
Another object of the invention is to provide a method of superheating a gas to reduce carbon monoxide emissions.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the invention will become more apparent after reading the following detailed description of the preferred embodiment of the invention, given with reference to the accompanying drawings, in which:
FIG. 1 is an elevation view with portions broken away and shown in section, and
FIG. 2 is a cross-sectional view taken on line 2 in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The fuel burner of FIG. 1 comprises a tubular flame cylinder 7 open at both ends. A cylindrical pre-heating chamber 4 surrounds the flame cylinder 7, such that an inner wall 6 of the pre-heating chamber defines the circumference of the flame cylinder 7. The pre-heating chamber 4 is axially aligned with the flame cylinder 7.
The pre-heating chamber 4 is closed at both extremities with annular chamber end seals 2. The end seals 2 are preferably duplicate rings. The rings are welded or otherwise pressure sealed to inner wall 6 and an outer wall 5 of the pre-heating chamber 4. The chamber end seals 2, so interposed, maintain equidistance between the inner wall 6 and the outer wall 5 as seen in FIG. 1.
In one embodiment, the pre-heating chamber 4 is approximately one foot long with an outside diameter of approximately two and one-quarter inches at the outer wall 5. The diameter of the flame cylinder 7 at the inside of the inner wall 6 is approximately one and seven-eighths inches. A suitable high-temperature metal, such as stainless steel #304, may be used for the walls and seals. A suitable thickness for the walls and seals is one-sixteenth inch. The above dimensions and the dimensions that follow are given as a preferred embodiment and to provide a sense of approximate scale only and one of ordinary skill in the art would understand that dimensions larger or smaller than those given could be used within the context of the present invention.
The flame cylinder 7 extends beyond the pre-heating chamber 4, as designated by reference numeral 15 in FIG. 1. The extended portion 15 extends in an axially direction and extends the inner wall 6, e.g., by approximately two more inches in the illustrated embodiment.
An air mixer barrel 12 is within the extended portion 15, such that the extended portion 15 encloses a majority of the air mixer barrel 12. The air mixer barrel 12 is approximately two and three-quarters inches in length in this embodiment.
A gas input pipe 1 communicates with the pre-heating chamber 4 through the chamber end seal 2 at a first extremity 16 of the pre-heating chamber 4. The gas input pipe 1 is affixed to the end seal 2 by weld or other pressure-proof seal. The gas input pipe 1 terminates within the pre-heating chamber 4 at an input pipe aperture 3.
A superheated gas tube 9 also communicates with the first extremity 16 of the pre-heating chamber 4 through the same chamber end seal 2, but on the opposite lateral side to that of the gas input pipe 1, as seen in FIG. 1. The superheated gas tube 9 may be similarly affixed to the end seal 2. The superheated gas tube 9 extends toward the second extremity 17 of the pre-heating chamber 4 and terminates near the second extremity 17 of the pre-heating chamber 4 at superheated gas tube aperture 8.
The superheated gas tube 9 also extends beyond the first extremity 16 of the pre-heating chamber 4, parallel to the extended portion 15 of the inner wall 6 of the flame cylinder 7. As seen in FIG. 1, the superheated gas tube 9 extends beyond the flame cylinder 7 and curves into a U-shaped bend. The U-shaped bend portion of the superheated gas tube 9 is connected to a hex nut. The U-Shaped bend portion is affixed to the hex nut by weld or other pressure-proof seal. The hex nut includes or may have therein an orifice 10. In the illustrated embodiment, based on the other relative sizes, the orifice 10 is 0.052 inches in diameter.
The end of the air mixer barrel 12 that extends beyond extended portion 15, is threadedly, or otherwise, affixed by a pressure proof seal to the hex nut. This end of the air mixer barrel 12 is open. Accordingly, the orifice 10 extends within this open end so that the air mixer barrel 12 surrounds and confines the orifice 10.
In the embodiment shown, the air mixer barrel 12 has four air mixer intake holes 11. The air mixer intake holes 11 are positioned adjacent to the extended portion 15 of the flame cylinder 7 at a position farthest away from the first extremity 16 of the pre-heating chamber 4. In this embodiment, the mixer intake holes 11 are each 0.265 inches in diameter.
An outer surface of the portion of the air mixer barrel 12 that extends into the extended portion 15 of the flame cylinder is threaded. A vertically adjustable, disk-shaped, turbulence ring 13 having a mating thread is connected to the air mixer barrel 12. An outside edge of the turbulence ring 13 is back-beveled, as shown, from the top of a horizontal plane of the turbulence ring 13. The turbulence ring 13 is approximately one and one-eighth inches in outside diameter.
The end of the air mixer barrel 12 that is opposite to the hex nut connection terminates with a beveled outer edge. The bevel slopes inwardly, as shown, at an acute angle from the horizontal plane of the top of the turbulence ring 13 to form a spray head. The bevel of the air mixer barrel has approximately a one-eighth inch edge.
In the embodiment of FIG. 2, the spray head has twelve spray head holes 14. Each of the holes are approximately 0.103 inches in diameter and are positioned equidistantly along the middle of the bevel of the outer edge of the spray head. Each spray head hole 14 communicates with the air mixer barrel 12 at substantially a ninety-degree angle vertical to the surface of the bevel on the outer edge of the spray head. As appreciated by one of ordinary skill in the art, the number of spray head holes is exemplary and the number of holes could be more or less.
The spray head is at the forward end of the air mixer barrel 12, in the direction of discharge of the spray, and extends into the mouth of the flame cylinder 7 at a distance selected to maintain a circular flame pattern projecting toward the second extremity 17 of the pre-heating chamber 4.
The operation of the present invention will now be discussed with respect to FIGS. 1 and 2. In operation of the present invention, numerous low-carbon fuels or gases may be burned. Propane is selected for simplification of the discussion of operation and combustion in the embodiment chosen for illustration.
Propane gas is commonly supplied in liquid state in a pressurized tank (not shown). Various fuel supply-regulating valves, which may be employed, such as throttling or pressure valves are not shown, as they are not part of the invention. Propane can also be supplied through a source regulator, in the direction illustrated in FIG. 1, through a low-temperature hose (not shown) appropriately connected to the gas input pipe 1. As the propane arrives at the input pipe aperture 3, it is typically changed to its gas state, i.e., vaporized. Upon being introduced into the preheating chamber 4, the vaporized gas is confined by the outer wall 5, the chamber end seals 2, and the inner wall 6.
As fuel fills the preheating chamber 4, it enters the superheated gas tube aperture 8. Through expansion pressure in the preheating chamber 4, the gas continues to flow through the superheated gas pipe 9 in the illustrated direction until it reaches the orifice 10. At this point, the gas has displaced all oxygen previously inside the preheating chamber 4. The orifice 10 supplies the gas to the air mixer barrel 12. Then, primary air from the air mixer intake holes 11 combines with the gas for initial combustion.
After ignition, the flame propelled from the tip of the air mixer barrel 12 spray head holes 14 spreads across the mouth of the flame cylinder 7 in a circular dispersion projected toward the inner wall 6. Additional fuel entering the preheating chamber 4 is subjected to increasing heat based on the proximity of the fuel to the inner wall 6 of the flame cylinder 7. This increasing heat increases the pressure within the preheating chamber 4. In the absence of oxygen in the preheating chamber 4, as flame temperature continues increasing; the vapor becomes superheated to a more excited state.
The superheated vapor consequently exits the orifice 10 at temperatures and velocities greater than the typical feed of gas to an open-air flame. The temperature and velocity of the flame continues to increase inside the flame cylinder 7. A forced air or chimney effect within the flame cylinder 7 thus develops, drawing a flow of secondary air into the flame cylinder 7 extended portion 15 as a combustion catalyst.
In addition, the orifice 10 increases the pressure of the superheated vapor so as to reduce the amount of carbon monoxide present in the super heated gas. As the pressure is increased above about 7 psi, preferably 8-10 psi, the amount of carbon monoxide (CO) decreases. However, as the temperature of the superheated vapor increases above about 1400° K, the amount of nitrogen oxides (NO_x) increases. Accordingly, a balance must be struck between the CO emissions and the NO_xemissions.
The presence of the turbulence ring 13 creates two zones of pressure differential within the flame cylinder 7. One zone is below (upstream of the turbulence ring in the direction of the flame) and the other zone is above the turbulence ring 13. Although the inventor does not wish to be bound thereto, it would appear that the randomly turbulent secondary combustion air jet is subjected to a strong, non-axial pattern of turbulence above the turbulence ring 13, upstream from the area of ignition at the air mixer barrel 12 spray head holes 14. The resulting pattern of jet flow asymmetries of the secondary combustion air create greater entrainment or mixing with the gas in the area of ignition. This results in ideal combustion efficiency with superior heat radiance or flame emissivity, but with extremely low CO and NOx production.
The turbulence ring 13 is adjusted up or down on the air mixer barrel 12 to regulate the distance of the zones of pressure differential from the super-heated gas streams ignited at the spray head holes 14. The position of the turbulence ring 13 is adjustable to achieve perfect flame characteristics and combustion. Turbulence ring 13 adjustments eliminate any yellow flamelets flickering within the flame. Adjustment also produces the shortest, widest flame with minimum flame distance or lift-off from the top of the air mixer barrel spray head holes 14. The ideal flame is also characterized by a blue region at the base of the flame, and high flame luminosity blending to transparency.
Commercially available “Barber” type jet burner air mixers with threaded flame caps, in an appropriate scale, can be substituted for the illustrated air mixer barrel 12 and spray head holes 14. The turbulence ring 13 in that alternative is placed below the flame cap. “Barber” type jet burner air mixer holes are positioned fully up or inside the flame cylinder 7. These commercial air mixers have orifice diameters and flame cap holes that are typically established by various manufacturers for propane supplied at ½ to 10 p.s.i. The diameters specified for the orifice 10, the air mixer intake holes 11 and the spray head holes 14 illustrated here, will produce, for a supply pressure of ½ p.s.i., approximately 13,000 B.t.u. The output will increase, as supply p.s.i. is raised.
While one embodiment of the present invention has been illustrated in the dimensions specified, it should be understood that the invention is subject to modification and different sizes and scales without changing its nature or scope. The nature of the present invention is comprised of the structure of its proportional design elements. Similarly, one fuel has been chosen to illustrate one manner of operation, without any intent to limit the use of different fuels in the invention. Where less volatile fuels are chosen, the volume of the preheating chamber 4 and the orifice 10 diameter, air mixer intake holes 11 and spray head holes 14 would be appropriately adjusted in related sizes. Accordingly, the scope of invention should not be limited to the aforementioned embodiment, but rather by the appended claims.

Claims

1. A device for combusting liquid fuel, comprising:

a cylinder having an inner wall and an outer wall with a sealed space therebetween, said cylinder being sealed at both ends by respective annular seals;

a first tube adjacent a first end of said cylinder and extending into said space through one of said respective annular seals;

a second tube having a first end adjacent an opposing second end of said cylinder and a second end adjacent said first end of said cylinder, said second tube extending out of the space through said one of said respective annular seals;

an air mixing barrel extending into said cylinder and having a plurality of air intake holes and a plurality of gas spray holes, said second end of said second tube being removably connected to a first end of said air mixing barrel; and

a turbulence ring rotatably adjustable about a second end of said air mixing barrel.

2. The device as claimed in claim 1, wherein said inner wall extends beyond said second end of said cylinder and said air mixing barrel extends only into an area defined by said inner wall.

3. The device as claimed in claim 2, wherein said air intake holes are outside of said area defined by said inner wall.

4. The device as claimed in claim 2, wherein said inner wall extends beyond said second end of said cylinder by approximately two inches.

5. The device as claimed in claim 1, wherein said turbulence ring has a beveled edge.

6. The device as claimed in claim 5, wherein a widest part of said beveled edge is closest to said plural gas spray holes.

7. The device as claimed in claim 1, wherein said air mixing barrel has a beveled edge at a first end, said plural gas spray holes being in said beveled edge.

8. The device as claimed in claim 7, wherein said plural gas spray holes are substantially perpendicular to said beveled edge.

9. The device as claimed in claim 1, further comprising an orifice connected between said second end of said second tube and said mixing barrel that creates pressure in said mixing barrel when said superheated gas flows therethrough.

10. The device as claimed in claim 1, wherein the cylinder is approximately one foot long and has an outside diameter of approximately two and one-quarter inches.

11. A device for combusting liquid fuel, comprising:

a cylinder having an inner wall and an outer wall with a sealed space therebetween, said inner wall defining a heating chamber separate from said space;

a first pipe supplying gas to said space;

an air mixing barrel having a first end extending into said cylinder and having a plurality of air intake holes between said first end and an opposing second end, a plurality of gas spray holes being at said first end;

a second pipe extending from said space to said second end of said air mixing barrel for supplying said gas, as superheated gas, to said air mixing barrel; and

a turbulence ring adjacent said first end and rotatably adjustable about said air mixing barrel.

12. The device as claimed in claim 11, wherein said mixing barrel further comprises an orifice.

13. A method of superheating a gas to reduce carbon monoxide emissions, comprising the steps of:

delivering a liquid to a first end of a first tube;

vaporizing said liquid to form a combustible gas;

discharging said gas from a second end of the first tube adjacent a first end of a double walled cylinder;

heating said double walled cylinder;

flowing the gas between walls of the double walled cylinder from the first end of the cylinder toward a second end of the cylinder, so that the gas enters a second tube at the second end of the cylinder as a superheated gas;

passing the superheated gas through the second tube, so that the superheated gas flows through the second tube from the second end of the cylinder back toward the first end of the cylinder, on a side of the cylinder opposite that of the first tube;

mixing the superheated gas with air in an air mixing barrel that partially extends into the cylinder;

igniting the air/superheated gas mixture in the air mixing barrel at a temperature that reduces carbon monoxide level;

ejecting the ignited air/gas mixture from a plurality of spray holes on an end of the air mixing barrel into the cylinder to develop a secondary flow of air into the first end of the cylinder.

14. The method according to claim 14, further comprising the step of adjusting a turbulence ring around the air mixing barrel to regulate zones of pressure differential upstream and downstream of the turbulence ring in a direction of the secondary flow of air.

15. The method according to claim 13, further comprising the step of increasing a pressure of the superheated gas to reduce the carbon monoxide level.

16. The method according to claim 15, wherein the pressure of the superheated gas is increased using an orifice.

17. The method according to claim 16, wherein the pressure is increase above 7 psi.

18. The method according to claim 16, wherein the pressure is increased to between 8 and 10 psi.

19. The method according to claim 18, wherein the gas is propane.

20. The method according to claim 13, wherein the gas is propane.