US3630651A

US3630651A - Dual vortex burner

Info

Publication number: US3630651A
Application number: US37230A
Authority: US
Inventors: Richard J Fay; James P Kottenstette
Original assignee: United States Department of the Air Force
Current assignee: United States Department of the Air Force
Priority date: 1970-05-14
Filing date: 1970-05-14
Publication date: 1971-12-28
Anticipated expiration: 1988-12-28

Abstract

A dual vortex gaseous burner having a vortex tube, a separator tube, a pair of vortex chambers and an igniter. An oxidizer is injected tangentially through a jet in one of the vortex chambers forming a primary vortex between the separator tube and the vortex tube wall, while a fuel is injected tangentially through a jet in the other vortex chamber forming a secondary vortex between the igniter and the separator tube. An electric spark from the igniter produces ignition of the oxidizer and fuel at the boundary between the two vortices.

Description

O Umted States Patent 1111 3,

[72] Inventors Richard J. Fay; [56] References Cited ,arres P- Kottenstette, both of Denver, UNITED STATES PATENTS 3,221,796 12/1965 Nesbitt 431/285 3 Q 3 1970 2,486,137 10/1949 Evans 431/010. 95 E gf 1971 3,511,587 5/1970 Jansen et al. 431/160 Assignee The United sums of America 1,618,808 2/1927 Burg 431/173 m b th Secretary of thg U i d Primary Examiner- Edward G. Favors states Ai Force Attorneys-Harry A. Herbert, Jr. and Jacob N. Erlich 54 L O TE U NE ABSTRACT: A dual vortex gaseous burner having a vortex 9 Claims, 6 Drawing Figs. tube, :separgtor tube, a pair of vane); chambers and an igniter. n oxi izer is injecte tangential yt rough a jet in one [52] 11.8. C1 till/1:533, of the vortex chambers forming a primary vortex between the Fzacls l8 separator tube and the vortex tube wall, while a fuel is injected [51] CI}. 239 4G4 tangentially through aid in the other vortex chamber forming [50] F d o 1 I 173 35 3 157 9 6 a secondary vortex between the igniter and the separator tube.

An electric spark from the igniter produces ignition of the oxidizer and fuel at the boundary between the two vortices.

DUAL VORTEX BURNER BACKGROUND OF THE INVENTION This invention relates generally to gaseous fuel burners and, more particularly to a gaseous fuel burner utilizing a dual vortex for the purpose of heating tubes used as infrared radiators.

Heretofore, gaseous fuel burners utilized an axial combustion system. Such a system, although dependable had many drawbacks in use. For example, the heat release per unit volume inthe axial combustion system was insufficiently high for many of the present day requirements in gaseous fuel burners. Also, heat transfer to the tube walls of an axial combustion system falls short of the standards set forth in today's operating environment. Many attempts have been made to increase the efficiency of such axial combustion burners; however, to date none have proved to be successful.

SUMMARY OF THE INVENTION The dual vortex gaseous burner of this invention overcomes all the problems heretofore encountered and as set forth hereinabove.

The gaseous fuel burner of this invention employs a dual vortex changer which has been developed for-the purpose of heating tubes used as infrared radiators. The burner of this invention combines a high heat release per unit volume with a high rate of heat transfer to the tube surface, thus making it possible to heat tubes to very high temperatures. Surface temperatures in excess of 2,000 C. have been attained with beryllium oxide tubes fired with propane and oxygen.

In this invention the oxidizer gas is injected tangentially through a jet and forms a primary vortex which flows in the annulus formed by a vortex tube on the outside and a separator tube on the inside. The fuel gas is injected tangentially through a jet forming a secondary vortex which flows inside the separator tube. The fuel and oxidizer vortices rotate in the same direction. An electric spark from spark igniter produces ignition of the combustion reaction which takes place at the boundary between the two vortices. A conical end restriction is required to prevent the influx of products of combustion and surrounding air into the negative pressure region at the axis of the tube. The energy in the products of combustion is transferred to the tube wall by forced convection.

The heat release per unit volume of the vortex tube of this invention and the heat transfer to the tube wall are roughly 10 times as great as can normally be expected with an axial combustion system using the same fuel and oxidizer. Heating densities of 18.75 M btuh/ft. are achieved with propane and air as compared to l to 2 M btuh/ft. normally achieved with an axial combustion system. Heat released on the order of 40 M btuh/ft. have been achieved with propane and oxygen and higher heat released are possible.

The only limitation on the vortex gaseous burner of this invention is the ability of the tube material to withstand the high temperatures and heat fluxes. Heat transfer to the tube wall by the products of combustion is very effective in the instant invention because the flow is concentrated at the tube wall and the relative velocities between the products and the tube wall are high (on the order of several hundred feet per second). Also because of the spiral path of the flow, the residence time of the gas in the tube is much higher for a given relative velocity than could be obtained with axial flow through the tube. Heat transfer coefficients between the vortex and the tube wall on the order of I btuh/ft. /F. are indicated. The coefficient for the same level of output in an axial flow mode would be on the order of btuh/ft. /F. Furthermore, the burner of this invention has good stability over a wide range of inputs. It has been fired with fuel and oxidizer pressures of from 1 to 30'p.s.i.g. and wider ranges are believed possible. Also, the burner can be used in any application requiring a compact high performance burner which can operate on a gaseous fuel.

It is therefore an object of this invention to provide a dual vortex gaseous fuel burner which releases extremely high heat perunit volume.

It is another object of this invention to provide a dual vortex gaseous fuel burner which exhibits very effective heat transfer to the tube wall.

It is still another object of this invention to provide a-dual vortex gaseous fuel burnerwhich has extremely good stability.

It is a further object of thisinvention to provide a dual vortex gaseous fuel burner which is economical to produce and which utilizes conventional, currently available components that lend themselves to standard mass-producing manufacturing techniques.

For a better understanding of the present invention,

'together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

DESCRIPTION OF THE DRAWING FIG. 1 represents a side elevational view of the dual vortex gaseous fuel'burner of this invention partially in cross section and placing specific emphasis on the location of the vortex chambers, with the proportions of the vortex burner elements being enlarged for clarity;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is a side elevational view of a modified end restriction of this invention shown in cross section;

FIG. 5 is a side elevational view of the oxidizer injector vortex chamber of this invention drawn substantially to scale; and

FIG. 6 is a side elevational view of the fuel injector vortex chamber of this invention drawn substantially to scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference is now made to FIG. 1 of the drawing wherein a side elevational view of the dual vortex gaseous burner or radiator 10 of this invention is shown in cross section. It should be noted that the elements making up the gaseous burner 10 of this invention as shown in FIGS. 1-3 are drawn in an enlarged manner in order to better display their specific relationship with one another.

The gaseous burner 10 of the present invention utilizes a dual injection system 12 made up of a pair of concentric vortex chambers 11 and 13 which are clearly shown in FIGS. 5 and 6. The vortex chambers 11 and 13 inject a fuel and oxidizer respectively, into a vortex tube 14 made of any suitable material such as inconel, LT-l or beryllium oxide such that they form concentric vortices which merge together inside the vortex tube 14. A small tube l6 called the separatortube, keeps the two vortices separated until well inside the tube 14.

As shown in FIGS. l-3 an oxidizer such as air'or pure oxygen is injected by any conventional injectionsystem tangentially through a jet or line 18 (see FIG. 5) and forms theprimary vortex 19 which flows in'the annulus formed by the vortex tube 14 on the outside and the separator tube 16 formed on the inside. The fuel such as propane, acetylene or hydrogen is injected by any conventional injection system through tangen tial jet or line 20 (see FIG. '2) forming a secondary vortex 21 flowing inside the separator tube 16. At the end of the separator tube the two vortices l9 and 21 merge together gradually.

Still referring to FIG. I, an igniter 22 is mounted within the vortex chamber 11 and is used to ignite-the oxidizer and fuel at the point where they merge. The igniter 22 may be in the form of a flame; however, better results are obtained with an' electrical igniter 22 made up of an electrode 24 and a Tesla coil 26. The igniter electrode 24 is made of any suitable Nichrome wire cemented into an alumina tube with the Tesla coil 36 capable of puttingout a 25,000volt 60-cycle spark.

A conical end restriction 28 is required and mounted at the end of the vortex tube 14. This end restriction 28 prevents the influx of products of combustion and surrounding air into the negative pressure region'at the axis of the tube 14. FIG. 4 discloses a modified-end restriction 30 which is liquid cooled.

mmmm 3630.651

INVENTORJ mum Far

Claims

1. A dual vortex gaseous burner comprising a vortex tube, a pair of concentric vortex chambers mounted at one end of said vortex tube, a separator tube mounted between said pair of chambers, an igniter mounted within said separator tube and an end restriction mounted in the other end of said tube, means for injecting an oxidizer tangentially through one of said pair of vortex chambers forming a primary vortex in said vortex tube, means for injecting a fuel tangentially through the other of said vortex chambers forming a secondary vortex in said vortex tube, said separator tube initially separating said primary vortex from said secondary vortex before ignition.

2. A dual vortex gaseous burner as defined in claim 1 wherein each of said vortex chambers has a plurality of slots therein.

3. A dual vortex gaseous burner as defined in claim 2 wherein said igniter is an electric igniter comprising an electrode and a Tesla coil.

4. A dual vortex gaseous burner as defined in claim 3 wherein said end restriction is of a conical configuration.

5. A dual vortex gaseous burner as defined in claim 4 wherein said conical end restriction has a liquid coolant running therethrough.

6. A dual vortex gaseous burner as defined in claim 5 wherein said vortex tube is made of beryllium oxide.

7. A dual vortex gaseous burner as defined in claim 5 wherein said oxidizer is pure oxygen and said fuel is propane.

8. A dual vortex gaseous burner as defined in claim 5 wherein said vortex tube is made of inconel.

9. A dual vortex gaseous burner as defined in claim 5 wherein said vortex tube is made of LT-1.