Narrow spray angle liquid fuel atomizers for combustion

• US 5,617,997 A
• Filed: 01/22/1996
• Issued: 04/08/1997
• Est. Priority Date: 06/13/1994
• Status: Expired due to Term

• Current Assignee: Praxair Technology Incorporated (Linde Plc)
• Original Assignee: Praxair Technology Incorporated (Linde Plc)
• Inventors: Kobayashi, William T., Francis, Arthur W. Jr.
• Primary Examiner(s): WELDON, KEVIN P
• Application Number:
  US08/589,429
• Time in Patent Office: 442 Days
• Field of Search: 239/416, 239/416.5, 239/423, 239/424, 239/8, 431/1, 431/9
• US Class Current: 239/8
• CPC Class Codes: F23D 11/106 medium and fuel meeting at the burner outlet

Abstract

The invention relates to an improvement in atomizing methods and apparatus useful for combusting liquid fuel, such oil. The atomizing methods and apparatus consistently produce liquid fuel streams having vary narrow spray angles. The liquid fuel streams having very narrow spray angles can be produced even when a low liquid fuel flow rate is employed and even when a liquid fuel stream is atomized outside a liquid fuel passageway. The production of the constant narrow spray angle liquid fuel stream allows the atomizing apparatus to operate for a long period without causing fouling problems even if they are sufficiently recessed from internal openings of refractory ports defined in the furnace wall.

Claims

1. An apparatus for atomizing liquid fuel for effective combustion with reduced nitrogen oxides generation, said apparatus comprising:

(a) a nozzle having interior and exterior surfaces, with said interior surface defining a liquid fuel passageway and a liquid fuel port, said liquid fuel port having an inlet for receiving liquid fuel from said liquid fuel passageway and an outlet for discharging liquid fuel; and

(b) an enclosure having interior and exterior surfaces concentrically surrounding at least a portion of said nozzle and defining an annular passageway and an annular atomizing fluid port between said interior surface of said enclosure and said exterior surface of said nozzle, with said annular passageway terminating with said annular atomizing fluid port having inlet and outlet openings, wherein both at least a portion of the interior surface of said enclosure and at least a portion of said exterior surface of said nozzle defining said annular atomizing fluid port are in the form of a cone having a diameter decreasing toward said outlet opening of said annular atomizing fluid port, at an angle in the range of about 5°

to about 30°

, measured from a longitudinal axis of said nozzle and wherein the nozzle, between the interior and exterior surfaces, converges to a sharpened annular edge at the outlet of the fuel port.

2. The apparatus according to claim 1, wherein the ratio of the outlet diameter of said liquid fuel port to the outlet diameter of said annular atomizing fluid port is in the range of about 0.35 to about 0.45.

3. The apparatus according to claim 1, wherein both said at least a portion of the interior surface of said enclosure and said at least a portion of said exterior surface of said nozzle defining said annular atomizing fluid port are in the form of a cone having a diameter decreasing toward said outlet opening of said annular atomizing fluid port, at an angle in the range of about 12°

to about 18°

, measured from a longitudinal axis of said nozzle.

4. The apparatus according to claim 1, wherein the outlet of said liquid fuel port is located at the same plane as the outlet opening of the annular atomizing fluid port.

5. The apparatus according to claim 1, wherein said apparatus for atomizing liquid fuel is located in a position recessed in a furnace wall.

6. The apparatus according to claim 1, further comprising an additional enclosure having interior and exterior surfaces concentrically surrounding at least a portion of said enclosure and defining an annular passageway between said interior surface of said additional enclosure and said exterior surface of said enclosure for supplying additional atomizing fluid.

7. The apparatus according to claim 1, wherein the liquid fuel passageway of said nozzle is comprised of at least two lengths and wherein a first length has a large cross sectional area, and a second length, which communicates with the first length, has a cross sectional area which decreases in the direction of the liquid fuel port of the nozzle.

8. The apparatus according to claim 7, wherein the liquid fuel port of said nozzle is comprised of at least three sections and wherein a first section having a cross-sectional area equal to or smaller than the cross sectional area at the end of the second length of the liquid fuel passageway communicates with a second section having a cross-sectional area decreasing in the direction of the outlet, and said second section communicates with a third section having a cross-sectional area smaller than that of the first section.

9. The apparatus according to claim 1, wherein said apparatus for atomizing liquid fuel provides a liquid fuel stream in the form of a spreading spray having an outer periphery angle of less than 15°

.

10. The apparatus according to claim 1, wherein said apparatus for atomizing liquid fuel provides a liquid fuel stream in the form of a spreading spray having an outer periphery angle of about 2°

to about 10°

.

11. The apparatus according to claim 1, wherein the ratio of the outlet diameter of said liquid fuel port to the outlet opening diameter of said annular atomizing fluid port is in the range of about 0.25 to about 0.55.

12. A process for atomizing liquid fuel to provide a liquid fuel stream in the form of a spreading spray having an outer periphery angle of less than 15°

, measured from the axis of said liquid fuel stream, thus promoting effective combustion with reduced nitrogen oxide generation, said process comprising;

(a) ejecting a liquid fuel stream from at least one first opening of a nozzle;

(b) ejecting atomizing fluid from at least one second opening annular to said at least one first opening at a velocity of about 0.5 Mach to about 1.2 Mach toward said liquid fuel stream at a converging angle in the range of about 5°

to about 30°

, measured from a longitudinal axis of said nozzle, and wherein said nozzle converges to an annular edge between said at least one first opening and said at least one second annular opening.

13. The process according to claim 12, wherein said liquid fuel is ejected at less than 50 feet per second.

14. The process according to claim 12, wherein said atomizing fluid is ejected at a velocity of at about 0.8 to about 1.1 Mach toward said liquid fuel stream at a converging angle in the range of about 12°

to about 18°

, measured from a longitudinal axis of said nozzle.

15. The process according to claim 12, wherein the rate of said atomizing fluid injected is such that the mass ratio of said atomizing fluid to said liquid fuel is maintained in the range of about 0.4 to about 0.7.

16. The process according to claim 12, wherein said atomizing fluid is selected from the group consisting of steam, nitrogen, air, oxygen-enriched air and pure oxygen.

17. The process according to claim 12, wherein said at least one first opening has a diameter in the range of about 0.02 inch to about 1 inch.