US3592573A - Flame ignition system for cutting machines - Google Patents

Flame ignition system for cutting machines Download PDF

Info

Publication number
US3592573A
US3592573A US834996A US3592573DA US3592573A US 3592573 A US3592573 A US 3592573A US 834996 A US834996 A US 834996A US 3592573D A US3592573D A US 3592573DA US 3592573 A US3592573 A US 3592573A
Authority
US
United States
Prior art keywords
gas
preheat
flame
velocity
period
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US834996A
Inventor
George H Tikijian
Alexander Jordan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
L-Tec Co
Original Assignee
Union Carbide Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Union Carbide Corp filed Critical Union Carbide Corp
Application granted granted Critical
Publication of US3592573A publication Critical patent/US3592573A/en
Assigned to L-TEC COMPANY reassignment L-TEC COMPANY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: UNION CARBIDE CORPORATION
Assigned to SECURITY PACIFIC BUSINESS CREDIT INC., A DE CORP. reassignment SECURITY PACIFIC BUSINESS CREDIT INC., A DE CORP. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: L-TEC COMPANY A NY LIMITED PARTNERSHIP
Assigned to L-TEC COMPANY reassignment L-TEC COMPANY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: UNION CARBIDE CORPORATION, A CORP OF NY.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K7/00—Cutting, scarfing, or desurfacing by applying flames

Definitions

  • U.S. Cl 431/1, ABSTRACT A method of establishing a self-sustaining high- 60/39.82 P. 239/413, 266/23 R velocity oxyfuel preheat gas flame comprising pulsating the Int. Cl F23c 3/02 flow of the preheat gas while igniting same, at a rate such that Field of Search 431/1, 6; the average gas velocity is rendered nearly equal to the rate of 60/39.82 P; 239/413; 266/23 R flame propagation.
  • thermotreating processes such as metal piercing, cutting, etc. heat is applied to a workpiece by means of an oxyfuel gas flame.
  • fuel gas and a combustion-supporting gas is combined in a predetermined proportion and directed against the surface of the workpiece.
  • the mixed gas forms the preheat flame which raises the temperature of the workpiece to its sweat" temperature for performing the cutting or piercing operation.
  • fuel gases such as natural gas or propanes it is desirable to have a high exit preheat gas velocity.
  • high gas velocity is defined as being at least 100 f.p.s. (feet per second) or greater.
  • a self-sustaining preheat gas flame may be established by pulsating the flow of preheat gas during the ignition period.
  • the tendency of the flame to extinguish itself is believed to result from a flame propagation rate which is lower than that of the gas exit velocity.
  • a self-sustaining flame will be established by pulsating the preheat gas at a rate such that the average gas velocity at exit is rendered nearly equal to the rate of flame propagation.
  • FIG. 1 is a front plan view of an oxyfuel gas cutting torch or blowpipe and a spark igniter
  • FIG. 2 is a timing diagram of a complete cycle of operation
  • FIG. 3 is a schematic block diagram of the preferred system for pulsating the flow of preheat gas in accordance with the present invention.
  • FIG. 1 in which an oxyfuel gas cutting torch T sometimes referred to as a cutting blowpipe is shown diagrammatically having a nozzle portion N through which the preheat gas and cutting gas is discharged.
  • the combustionsupporting gas which in most cases is oxygen is supplied to gas conduit 12 through a solenoid valve 18 while the fuel gas to be proportionally mixed with said combustion-supporting gas is fed to gas conduit 14 through a solenoid valve 20.
  • the mixing of the fuel gas which may be for example either natural gas, propane, methane, and butane or combinations thereof and the combustion-supporting gas occurs in a conventional manner within blowpipe T, the mixture being thereafter discharged from the nozzle portion N of blowpipe T as preheat gas.”
  • the cutting gas, oxygen is supplied to gas conduit 16 through a solenoid valve 22 for performing the actual cutting or metal-piercing operation.
  • an automatic pilot igniter S which provides a pilot flame for igniting the preheat gas. Ignition gas is supplied to the pilot igniter S through a solenoid valve 24. The pilot flame is ignited by means of a spark developed from a spark plug or other high-voltage means encased within the igniter S. It is also possible to ignite the preheat gas directly from a spark rather than a pilot flame.
  • the distance between the outlet end of nozzle N and the pilot igniter S is not critical, although for practical reasons a distance of 2 to 4 inches is preferred.
  • FIGv 2 in which is shown a sequential timing diagram of a complete operating cycle.
  • a complete operating period i.e. when the torch is initially lit to where it is turned off, is depicted in FIG. 2(a
  • the ignition period is shown in FIG. 2(b
  • the preheat time period shown in FIG. 2(c begins at the termination of the ignition period.
  • the actual cutting time which extends for the greater portion of the operating period is shown in FIG. 2(d
  • the preheat solenoid valves are turned on and off during the ignition period to effect pulsing of the preheat gas as shown in FIG. 2(e
  • the average preheat gas velocity is controlled by the ratio of off time to on time for solenoid valves 18 and 20 during the ignition period in the manner to be described in connection with the system of FIG. 3.
  • FIG. 3 shows the preferred system for pulsing the preheat gas.
  • solenoid valves 18 and 20 are placed in series with conventional switching means 26 and 28 which are preferably solid-state devices such as triacs.
  • switching means 26 and 28 are turned on" solenoid valves 18 and 20 are activated supplying fuel gas and combustion-supporting gas, respectively, to torch T where the gases are appropriately mixed and discharged through nozzle N as preheat gas.
  • switching means 26 and 28 are maintained on by the output of amplifier 30 throughout the preheat and cutting periods and are simultaneously turned on and off throughout the ignition period.
  • Any conventional circuit means may be used to pulse switching means 26 and 28 during the initial ignition period.
  • One way to accomplish this is by means of a conventional relaxation oscillator 32, the output pulse frequency of which is controllable.
  • Each generated output pulse is fed to amplifier 30 to reverse bias the amplifier, i.e. turn it off for a predetermined period of time.
  • solenoid valves 18 and 20 are intermittently interrupted for producing a pulsed gas flow.
  • the input signal to relaxation oscillator 32 is applied only during the ignition period and may represent the same ignition signal applied to the pilot igniter S. Power is supplied to the system from a common power supply
  • Set forth below is a typical example illustrating the required off-on time for the preheat solenoids l8 and 20 necessary to establish a stable self-sustaining flame where:
  • Rate of flame propagation 50 f.p.s.
  • the off-on time ratio may be maintained constant if the preheat velocity as given in the example above is not to exceed 500 f.p.s. However, it is preferred to provide the operator with a variable control so that he may vary the ratio for optimum performance for any given preheat velocity.
  • the relaxation oscillator circuit is designed such that the off time can be varied in the range from about 2 seconds down to about 0.05 seconds and the on time increased from about 0.05 seconds to about 0.3 seconds.
  • a method of establishing a self-sustaining high-velocity oxyfuel preheat gas flame for treating a metal surface which comprises: discharging preheat gas at a velocity of at least feet per second from a blowpipe, said preheat gas consisting of a predetermined mixture of fuel gas and a combustion-supporting gas; igniting said high-velocity preheat gas for an ignition period to form a preheat flame, and pulsating the flow of preheat gas during said ignition period such that the preheat gas flame is repetitively turned off for a time period of between 2 to 0.5 seconds and back on for a time period of between 0.05 to 0.3 seconds, whereby a self-sustaining preheat flame is established after said ignition period has terminated.
  • the preheat gas comprises a mixture of a fuel gas selected from the'class consisting of natural gas, propane, methane and butane and a combustion-supporting gas.

Abstract

A method of establishing a self-sustaining high-velocity oxyfuel preheat gas flame comprising pulsating the flow of the preheat gas while igniting same, at a rate such that the average gas velocity is rendered nearly equal to the rate of flame propagation.

Description

United States Patent inventors George l-LTikijian {56] References Cited Maplewwd= UNITED STATES PATENTS AlexanderJordamCraniord,both oi,N.J. 1 376 828 5/1921 penis 239/413 QI J- 23:52: 1.912,243 5/1933 Andrews I A 431/1 d N 133971 2,480,626 8/1949 Bodine,Jr 60/208 2929,210 3/1960 Howes v 1 60/39.82P Assgnee Unmncarbmecmpmm 3,171,465 3/1965 Rydberg. 431 1 New 3,194,295 7/1965 Marchaletal 431 1 Primary Examiner-Frederick L. Matteson Assistant Examiner- Robert A. Dua
FLAME IGNITION SYSTEM FOR CUTTING Att0rneys Paul A. R086, Thomas I. OBrien, Dominic J.
MACHINES Terminello and Eugene Lieberstein 2 Claims, 3 Drawing Figs.
U.S. Cl 431/1, ABSTRACT: A method of establishing a self-sustaining high- 60/39.82 P. 239/413, 266/23 R velocity oxyfuel preheat gas flame comprising pulsating the Int. Cl F23c 3/02 flow of the preheat gas while igniting same, at a rate such that Field of Search 431/1, 6; the average gas velocity is rendered nearly equal to the rate of 60/39.82 P; 239/413; 266/23 R flame propagation.
FUEL 04s 7 COMBUSTION CUTTING 6A5 j?- supeom'me GAS IGNITION GAS SPARK SIGNAL PILOT IGNITEQ PATENTED JIIII 3 IIIII v 3592-57 3 SHEET 1 0F 2 FUEL GAS 78 ,I COMBUSTION SUPPORTING GAs 24 IGNITION I A GAS V SPARK SIGNAL PILOT IGNITER TIMING DIAGRAM Complete Cycle Torch Operahng Cycle I F! l lgmhon PerIod I Energizahon of I Pret1e)af Valves Preh af Time I Period (d) Guthng TIme Period @1 INVENTORS 42912 ALEXANDER JORDAN GEORGE H. IKIJIAN ATTORN EY FLAME IGNITION SYSTEM FOR CUTTING MACHINES This invention relates to thermotreating operations and more particularly to a method of establishing a self-sustaining high-velocity oxyfuel preheat gas flame.
In thermotreating processes such as metal piercing, cutting, etc. heat is applied to a workpiece by means of an oxyfuel gas flame. Initially, fuel gas and a combustion-supporting gas is combined in a predetermined proportion and directed against the surface of the workpiece. When ignited the mixed gas forms the preheat flame which raises the temperature of the workpiece to its sweat" temperature for performing the cutting or piercing operation. For fuel gases such as natural gas or propanes it is desirable to have a high exit preheat gas velocity. However, with high gas velocity the flame has a tendency to blow itself out. It has heretofore been difficult to establish a high-velocity preheat flame which would sustain itself after removing the pilot igniter. For purposes of the present disclosure high gas velocity is defined as being at least 100 f.p.s. (feet per second) or greater.
It is therefore the principal object of the present invention to provide a method of establishing a self-sustaining highvelocity oxyfuel preheat gas flame.
Other objects, features and advantages of the present invention will be apparent from the following detailed description.
It has been discovered in accordance with the present invention that a self-sustaining preheat gas flame may be established by pulsating the flow of preheat gas during the ignition period. The tendency of the flame to extinguish itself is believed to result from a flame propagation rate which is lower than that of the gas exit velocity. In accordance with this theory a self-sustaining flame will be established by pulsating the preheat gas at a rate such that the average gas velocity at exit is rendered nearly equal to the rate of flame propagation.
In the drawings:
FIG. 1 is a front plan view of an oxyfuel gas cutting torch or blowpipe and a spark igniter;
FIG. 2 is a timing diagram of a complete cycle of operation;
FIG. 3 is a schematic block diagram of the preferred system for pulsating the flow of preheat gas in accordance with the present invention.
Referring now to FIG. 1 in which an oxyfuel gas cutting torch T sometimes referred to as a cutting blowpipe is shown diagrammatically having a nozzle portion N through which the preheat gas and cutting gas is discharged. The combustionsupporting gas which in most cases is oxygen is supplied to gas conduit 12 through a solenoid valve 18 while the fuel gas to be proportionally mixed with said combustion-supporting gas is fed to gas conduit 14 through a solenoid valve 20. The mixing of the fuel gas, which may be for example either natural gas, propane, methane, and butane or combinations thereof and the combustion-supporting gas occurs in a conventional manner within blowpipe T, the mixture being thereafter discharged from the nozzle portion N of blowpipe T as preheat gas." The cutting gas, oxygen, is supplied to gas conduit 16 through a solenoid valve 22 for performing the actual cutting or metal-piercing operation.
Located directly below blowpipe T in close proximity to the stream of emerging gas is an automatic pilot igniter S which provides a pilot flame for igniting the preheat gas. Ignition gas is supplied to the pilot igniter S through a solenoid valve 24. The pilot flame is ignited by means of a spark developed from a spark plug or other high-voltage means encased within the igniter S. It is also possible to ignite the preheat gas directly from a spark rather than a pilot flame.
In carrying out the present invention, the distance between the outlet end of nozzle N and the pilot igniter S is not critical, although for practical reasons a distance of 2 to 4 inches is preferred.
Referring now-to FIGv 2 in which is shown a sequential timing diagram of a complete operating cycle. A complete operating period, i.e. when the torch is initially lit to where it is turned off, is depicted in FIG. 2(a The ignition period is shown in FIG. 2(b The preheat time period shown in FIG. 2(c begins at the termination of the ignition period. The actual cutting time which extends for the greater portion of the operating period is shown in FIG. 2(d The preheat solenoid valves are turned on and off during the ignition period to effect pulsing of the preheat gas as shown in FIG. 2(e The average preheat gas velocity is controlled by the ratio of off time to on time for solenoid valves 18 and 20 during the ignition period in the manner to be described in connection with the system of FIG. 3.
FIG. 3 shows the preferred system for pulsing the preheat gas. In this system solenoid valves 18 and 20 are placed in series with conventional switching means 26 and 28 which are preferably solid-state devices such as triacs. When the switching means 26 and 28 are turned on" solenoid valves 18 and 20 are activated supplying fuel gas and combustion-supporting gas, respectively, to torch T where the gases are appropriately mixed and discharged through nozzle N as preheat gas.
In the present operation switching means 26 and 28 are maintained on by the output of amplifier 30 throughout the preheat and cutting periods and are simultaneously turned on and off throughout the ignition period. Any conventional circuit means may be used to pulse switching means 26 and 28 during the initial ignition period. One way to accomplish this is by means of a conventional relaxation oscillator 32, the output pulse frequency of which is controllable. Each generated output pulse is fed to amplifier 30 to reverse bias the amplifier, i.e. turn it off for a predetermined period of time. Hence, solenoid valves 18 and 20 are intermittently interrupted for producing a pulsed gas flow. The input signal to relaxation oscillator 32 is applied only during the ignition period and may represent the same ignition signal applied to the pilot igniter S. Power is supplied to the system from a common power supply Set forth below is a typical example illustrating the required off-on time for the preheat solenoids l8 and 20 necessary to establish a stable self-sustaining flame where:
Fuel gas =natural gas Preheat velocity =500 f.p.s.
Rate of flame propagation =50 f.p.s.
Repetitive during ignition period: Off time: 1.35 see;
on time=.05 see. g M p M Offtime" to on time ratio 2711 The exit gas velocity during the ignition period falls to an effective average exit velocity which is low enough to maintain a stable self-sustaining flame without the occurrence of flashback.
The off-on time ratio may be maintained constant if the preheat velocity as given in the example above is not to exceed 500 f.p.s. However, it is preferred to provide the operator with a variable control so that he may vary the ratio for optimum performance for any given preheat velocity. In the system shown in FIG. 3 the relaxation oscillator circuit is designed such that the off time can be varied in the range from about 2 seconds down to about 0.05 seconds and the on time increased from about 0.05 seconds to about 0.3 seconds.
What we claim is: I
l. A method of establishing a self-sustaining high-velocity oxyfuel preheat gas flame for treating a metal surface which comprises: discharging preheat gas at a velocity of at least feet per second from a blowpipe, said preheat gas consisting of a predetermined mixture of fuel gas and a combustion-supporting gas; igniting said high-velocity preheat gas for an ignition period to form a preheat flame, and pulsating the flow of preheat gas during said ignition period such that the preheat gas flame is repetitively turned off for a time period of between 2 to 0.5 seconds and back on for a time period of between 0.05 to 0.3 seconds, whereby a self-sustaining preheat flame is established after said ignition period has terminated.
2. A method as defined in claim 1 wherein the preheat gas comprises a mixture of a fuel gas selected from the'class consisting of natural gas, propane, methane and butane and a combustion-supporting gas.

Claims (2)

1. A method of establishing a self-sustaining high-velocity oxyfuel preheat gas flame for treating a metal surface which comprises: discharging preheat gas at a velocity of at least 100 feet per second from a blowpipe, said preheat gas consisting of a predetermined mixture of fuel gas and a combustion-supporting gas; igniting said high-velocity preheat gas for an ignition period to form a preheat flame, and pulsating the flow of preheat gas during said ignition period such that the preheat gas flame is repetitively turned off for a time period of between 2 to 0.5 seconds and back on for a time period of between 0.05 to 0.3 seconds, whereby a self-sustaining preheat flame is established after said ignition period has terminated.
2. A method as defined in claim 1 wherein the preheat gas comprises a mixture of a fuel gas selected from the class consisting of natural gas, propane, methane and butane and a combustion-supporting gas.
US834996A 1969-06-20 1969-06-20 Flame ignition system for cutting machines Expired - Lifetime US3592573A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US83499669A 1969-06-20 1969-06-20

Publications (1)

Publication Number Publication Date
US3592573A true US3592573A (en) 1971-07-13

Family

ID=25268304

Family Applications (1)

Application Number Title Priority Date Filing Date
US834996A Expired - Lifetime US3592573A (en) 1969-06-20 1969-06-20 Flame ignition system for cutting machines

Country Status (2)

Country Link
US (1) US3592573A (en)
CA (1) CA924235A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5069186A (en) * 1989-01-19 1991-12-03 Mario Illien Fuel injection assembly for internal combustion engine

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1376828A (en) * 1919-09-18 1921-05-03 Pettis John Gray Torch
US1912243A (en) * 1926-12-31 1933-05-30 Andrews Richard Henry Process and apparatus for firing furnaces
US2480626A (en) * 1947-11-03 1949-08-30 Jr Albert G Bodine Resonant wave pulse engine and process
US2929210A (en) * 1957-12-27 1960-03-22 Garrett Corp Pulsating ignition torch means
US3171465A (en) * 1960-09-22 1965-03-02 Gustavsbergs Fabriker Ab Furnace for intermittent combustion
US3194295A (en) * 1962-06-09 1965-07-13 Snecma Hot gas generating installation

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1376828A (en) * 1919-09-18 1921-05-03 Pettis John Gray Torch
US1912243A (en) * 1926-12-31 1933-05-30 Andrews Richard Henry Process and apparatus for firing furnaces
US2480626A (en) * 1947-11-03 1949-08-30 Jr Albert G Bodine Resonant wave pulse engine and process
US2929210A (en) * 1957-12-27 1960-03-22 Garrett Corp Pulsating ignition torch means
US3171465A (en) * 1960-09-22 1965-03-02 Gustavsbergs Fabriker Ab Furnace for intermittent combustion
US3194295A (en) * 1962-06-09 1965-07-13 Snecma Hot gas generating installation

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5069186A (en) * 1989-01-19 1991-12-03 Mario Illien Fuel injection assembly for internal combustion engine

Also Published As

Publication number Publication date
CA924235A (en) 1973-04-10

Similar Documents

Publication Publication Date Title
US5109669A (en) Passive self-contained auto ignition system
ATE170967T1 (en) COMBUSTION METHOD AND FUEL BURNER APPARATUS WITH DIVERGENT NOZZLE
DK0612306T3 (en) Oxygen / fuel firing of low speed solid turbulent flames
US3635644A (en) Infrared burner and method of increasing the heat flux radiated therefrom
US3592573A (en) Flame ignition system for cutting machines
US2938577A (en) Method and apparatus for preventing backfire in gas burner systems
EP0643267A4 (en) Premixed gas burning method and combustor.
DE3777053D1 (en) METHOD FOR OPERATING PRE-MIXING BURNERS AND DEVICE FOR CARRYING OUT THIS METHOD.
ATE191381T1 (en) BURNER METHOD AND DEVICE FOR TREATING BUILDING MATERIALS
US3224486A (en) Method and apparatus for producing air-fuel flames of sonic and supersonic velocities
US3404939A (en) Fuel burner ignitor
DE19641843A1 (en) Stabilization of pressure vibrations in combustion devices and methods therefor
ES2133550T3 (en) APPARATUS AND METHOD FOR BURNING FUEL GASES.
ES451490A1 (en) High energy arc ignitor for burner
US2604937A (en) Method of effecting combustion of paraffinic hydrocarbon gases and vapors
RU2251579C2 (en) Method for torch fluidic-air heating of articles and apparatus for performing the same
JPS57202402A (en) Combustion device for pulverized coal
JPS5245741A (en) Waste gas combustion burner
ES535346A0 (en) IMPROVEMENT AND MULTI-FLAME TORCH FOR HEATING OR PARTIAL HEATING OF METAL PIECES
US1782872A (en) Torch
US2715940A (en) Oven lighting system
US2870825A (en) Blow torches
US3136126A (en) Ignitor
GB1234682A (en)
SU1199948A1 (en) Inert gas generator

Legal Events

Date Code Title Description
AS Assignment

Owner name: L-TEC COMPANY, NEW YORK

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:UNION CARBIDE CORPORATION;REEL/FRAME:004436/0460

Effective date: 19850712

Owner name: L-TEC COMPANY, 666 THIRD AVENUE, NEW YORK, NY 100

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:UNION CARBIDE CORPORATION;REEL/FRAME:004436/0460

Effective date: 19850712

AS Assignment

Owner name: SECURITY PACIFIC BUSINESS CREDIT INC., A DE CORP.

Free format text: SECURITY INTEREST;ASSIGNOR:L-TEC COMPANY A NY LIMITED PARTNERSHIP;REEL/FRAME:004445/0860

Effective date: 19850716

AS Assignment

Owner name: L-TEC COMPANY, SOUTH CAROLINA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:UNION CARBIDE CORPORATION, A CORP OF NY.;REEL/FRAME:004610/0384

Effective date: 19860828

Owner name: L-TEC COMPANY, EBENEEZER ROAD, POST OFFICE BOX F-6

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:UNION CARBIDE CORPORATION, A CORP OF NY.;REEL/FRAME:004610/0384

Effective date: 19860828