Pre-vaporizing liquid fuel burner

• US 4,606,720 A
• Filed: 09/17/1984
• Issued: 08/19/1986
• Est. Priority Date: 09/17/1984
• Status: Expired due to Fees

• Current Assignee: Foster-Miller Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: Foster-Miller Incorporated (Thermo Fisher Scientific Incorporated)
• Inventors: Harvey, Andrew C.
• Primary Examiner(s): Dority, Jr., Carroll B.
• Application Number:
  US06/651,172
• Time in Patent Office: 701 Days
• Field of Search: 431/115, 431/116, 431/351, 431/9
• US Class Current: 431/115
• CPC Class Codes: F23D 11/005 with combinations of different spraying or vaporising means

Abstract

A pre-vaporizing liquid fuel burner with an eductor mounted to the end of a burner housing having an internal chamber. The eductor has air ducts disposed in a throat of the eductor through which combustion gas and air flow. A perforated flameholder is contiguous with the gas inlet of the eductor throat. The air flowing from the ducts creates a suction at the downstream side of the eductor throat which, in turn, draws the combustion gas from the center of the flame into the throat. The streams of air and gas flow from the eductor in interleaving streams to a mixing zone and then to the chamber downstream of the eductor. The interleaving streams are non-parallel to the burner axis but flow in an axisymmetric pattern to produce turbulent secondary eddies or flow patterns for complete mixing of air and combustion gas in a short distance. Liquid fuel is sprayed into the axisymmetric flow of the air-gas mixture where it evaporates. The combined air-gas-fuel vapor mixture is then fed to the flameholder and ignited.

Claims

1. A burner comprising:

(a) a housing formed with an internal chamber;

(b) eductor means mounted to said housing at a forward end of said chamber, said eductor means formed with a passageway having an inlet and an outlet, a plurality of air ducts disposed within said passageway, said air ducts arranged to direct air flowing therein into a path toward the longitudinal axis of said chamber from said forward end of said chamber to a rear end thereof;

(c) first means for introducing air into said chamber through said air ducts, recirculated combustion gas being drawn into said eductor means inlet, through said passageway and out said eductor means outlet by air flowing through said ducts, said gas and air entering said chamber in interleaving streams of gas and air, said gas and air mixing in said chamber;

(d) second means for introducing fuel into the rear of said chamber in the flow path of said streams of gas and air, said fuel mixing with said mixture of combustion gas and air in the rear portion of said chamber to form a mixture of combustion gas, fuel, and air; and

(e) flameholder means for supporting a flame, said flameholder means positioned at said eductor means inlet, said combustion gas being drawn from the flame on said flameholder means into said eductor means inlet, and means for delivering the mixture of combustion gas, fuel and air to said flameholder means about said eductor means.

2. The burner as claimed in claim 1 wherein said air ducts are offset relative to the longitudinal axis of said housing, said path of said air flowing in said air ducts being non-parallel to the longitudinal axis of said chamber.

3. The burner as claimed in claim 2 wherein said first means is a blower mounted to said housing, said air exiting said ducts creating a suction at the outlet of said passageway and drawing said recirculated combustion gas from the center of said flame into said inlet.

4. A fuel burner comprising:

(a) a housing formed with a central chamber having front, intermediate and rear zones;

(b) means for introducing a liquid fuel into said chamber at said rear zone;

(c) eductor means mounted to said housing in said front zone, said eductor means formed with a passageway having an inlet and an outlet, a plurality of air ducts disposed within said passageway, said air ducts arranged to direct air into said chamber in a path toward the longitudinal axis of said chamber from said forward zone to said rear zone;

(d) means for feeding air into said chamber through said air ducts, said combustion gas drawn into said eductor means inlet by said air passing through said air ducts, said air and said combustion gas being mixed in said intermediate zone, said combustion gas and air entering said forward zone in interleaving streams and mixing in said intermediate zone; and

(e) flameholder means mounted to said housing about said eductor means inlet, means for supplying said mixture of combustion gas, air, and fuel from said rear zone to said flameholder means about said eductor means.

5. The fuel burner as claimed in claim 4 wherein said air ducts project into said passageway, said air ducts being offset from the longitudinal axis of said housing.

6. The fuel burner as claimed in claim 5 wherein said combustion gas is drawn through said inlet by said air flowing through said air ducts which creates a suction at said outlet, said combustion gas being drawn from the center of said flameholder means.

7. The fuel burner as claimed in claim 6 wherein said liquid fuel is oil and said combustion gas drawn into said chamber is at a sufficiently high temperature to vaporize said oil sprayed into said rear zone of said chamber, said vaporized oil and combustion gas and air being mixed in said rear zone.

8. The fuel burner as claimed in claim 7 wherein said flameholder means is a screen formed into a dome-shaped structure having a plurality of holes with a diameter in the range of 0.01 of an inch to 0.1 of an inch, said dome-shaped structure substantially surrounding said inlet.

9. A burner comprising:

(a) a housing formed with a central chamber having a front zone, an intermediate zone and a rear zone;

(b) eductor means mounted to said housing at said front zone of said chamber, said eductor means formed with a passageway having an inlet and an outlet, a plurality of ducts disposed within said passageway;

(c) first means for introducing air into said front zone of said chamber through said ducts, said ducts directing air inwardly toward the longitudinal axis of said chamber from said front zone to said rear zone;

(d) second means for drawing combustion gas into said inlet at said front zone of said chamber through said passageway, said combustion gas flowing from said outlet, said combustion gas and said air flowing from said ducts entering said intermediate zone of said chamber in interleaving streams and mixing in said intermediate zone;

(e) third means for introducing fuel into said chamber at said rear zone, said mixture of combustion gas and air mixing with said fuel in said rear zone to form a mixture of combustion gas, fuel, and air;

(f) flameholder means mounted to said housing in front of said eductor means, said flameholder means contiguous with said inlet; and

(g) conduit means for guiding said mixture of combustion gas, fuel, and air from said rear zone within said housing to said flameholder means at said front zone.