JP2577177Y2 - Low NOx gas burner - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burner used as a heating source of an absorption refrigerator or a water heater, and more particularly to a low NOx gas burner in which reduction of NOx in exhaust gas is considered.

[0002]

2. Description of the Related Art Conventionally known low NOx gas burners include Japanese Utility Model Laid-Open No. 2-62223 and Japanese Utility Model Laid-Open No. 2-14.
No. 0122 and Japanese Utility Model Application Laid-Open No. Sho 62-18806. FIGS.
3 shows an example of the structure of the burner described in Japanese Patent Publication No.

[0003]

[Problems to be Solved by the Invention] Conventionally known low N
The Ox gas burner is applied when the pressure of the gas used exceeds at least 2000 mmAq, and a general low-pressure gas having a pressure of about 200 mmAq could not be used. When such a low-pressure gas is used, a booster must be separately provided to increase the pressure of the gas.

For example, in the burners described in Japanese Utility Model Laid-Open No. 2-62223 and Japanese Utility Model Laid-Open No. 2-140122, the burner air differential pressure (the differential pressure between the combustion chamber pressure and the air pressure supplied to the burner) is increased. Because of the large size, the size of the combustion blower becomes large, so that an increase in equipment costs, an increase in energy consumption, an increase in noise, and the like are inevitable. In addition, Shokai 62-
Although the burner described in Japanese Patent No. 18806 can use low-pressure gas, it has a problem that the structure is complicated.

An object of the present invention is to provide a low NOx burner which can use a low-pressure gas and has a small burner air differential pressure.

[0006]

An object of the present invention is to provide a main nozzle having a gas ejection hole for ejecting a fuel gas obliquely outward with respect to a nozzle center line, and a concentrically surrounding periphery of the main nozzle. A gas burner comprising: an inner cylinder disposed to form a primary air passage for ejecting combustion air around the main nozzle; a secondary air passage formed axially along an outer peripheral surface of the inner cylinder; A cylindrical portion which is concentrically arranged at an interval that becomes a recirculation flow passage between the outer peripheral surface of a downstream end portion of the inner cylinder and a downstream end of the cylindrical portion which is connected to the downstream end side of the cylindrical portion and has a nozzle center line. An air cone comprising a cone portion inclined to the side and configured so that secondary air ejected from the secondary air passage flows into the upstream end of the recirculation flow path;
The recirculation flow path and / or the second part is formed near the cylindrical portion of the air cone and / or the downstream end of the secondary air passage.
A low NOx gas burner comprising a recirculation opening communicating the secondary air passage with the combustion chamber.

[0007]

The secondary air ejected from the secondary air passage flows into the recirculation flow path of the air cone, and is turned in the direction of the center line of the nozzle at the cone portion of the air cone and penetrates into the burning flame. I do. Further, when the secondary air passes through the recirculation opening, the pressure near the recirculation opening decreases, and the combustion gas in the vicinity is sucked by the secondary air and flows into the recirculation passage together with the secondary air. Inflow. The combustion gas flowing into the recirculation flow path also flows into the inside of the burning flame along with the secondary air in the direction of the nozzle center line at the cone portion of the air cone, lowering the combustion temperature of the flame, and , Lowering the oxygen partial pressure of the combustion section. Due to the lowering of the combustion temperature and the lowering of the oxygen partial pressure, the generation of NOx is suppressed.

An air cone is provided at the tip of the nozzle to define a combustion gas recirculation flow path as a combustion chamber, and secondary air for driving the combustion gas recirculation passes through the passage. Thus, even if the difference between the pressure of the secondary air and the pressure of the combustion chamber is small, a sufficient amount of combustion gas is recirculated.

Further, even when a low-pressure gas having a pressure of about 200 mmAq is burned by installing an air cone, NOx
Generation amount decreases.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. The gas burner of the present embodiment has a disk-shaped nozzle pipe holder 5 having a through hole in the center, a nozzle pipe 4 inserted through the through hole and fixed to the nozzle pipe holder 5, and mounted on the tip of the nozzle pipe 4. Frustoconical main nozzle 10a and the main nozzle 10
a plurality of gas ejection holes 10b formed on the inclined surface portion of FIG.
An annular flame holding plate 12 mounted on the outer periphery of the main nozzle 10a, a plurality of small holes 15 formed on a circumferential line concentric with the main nozzle 10a of the flame holding plate 12, An inner cylinder 20 having one end fixed to the holder 5 and concentrically covering the outer periphery of the nozzle pipe 4 and the main nozzle 10a; a disk-shaped back plate 2 fixed to the outer peripheral surface of the nozzle pipe holder 5; 2, a cylindrical wind box 1 with a flange that forms an annular air passage 1a with the outer peripheral surface of the inner cylinder 20, and one end fixed to the inner peripheral surface of the flange of the wind box 1 and the other end. To the inner cylinder 2 via the annular end plate 21a.
0, an outer cylinder 21 fixed to the outer peripheral surface, a secondary air ejection hole 8 formed in the end plate 21a, and an outer peripheral surface at the distal end of the inner cylinder 20. An air cone 9 comprising a cylindrical portion formed and mounted in a circulation flow path 24, a cone portion connected to the downstream end of the cylindrical portion and having a cross section whose tip is narrowed toward the center, and an outer peripheral surface of the nozzle pipe holder 5; The spark rod 6, the frame rod 7, the pilot burner 11, and the inner cylinder 2 of the air passage 1a
And an annular portion 16 formed between the outer peripheral edge of the flame holding plate 12 and the inner peripheral surface of the inner cylinder 20.
It is comprised including. A primary air passage 22 is provided between the inner peripheral surface of the inner cylinder 20 and the outer peripheral surface of the nozzle pipe 4, and a secondary air passage 23 is provided between the outer peripheral surface of the inner cylinder 20 and the inner peripheral surface of the outer cylinder 21. , Respectively. In addition, a gap in the burner axial direction is formed between the rear end of the air cone 9 and the front end of the outer cylinder 21, and forms a clearance annular portion 14 which is a recirculation opening (a flow path of combustion gas).

Next, the combustion of the gas burner having the above configuration will be described. The fuel gas is ejected from the gas ejection holes 10b of the main nozzle 10a obliquely outside the nozzle center through the nozzle pipe 4. The wind blower 30 is connected to the wind box 1.
After entering the air passage 1a, the combustion air supplied through the primary air hole 3 is divided into primary air flowing through the primary air passage 22 and secondary air flowing through the secondary air passage 23.
The primary air is further divided into one passing through the small holes 15 of the flame holding plate 12 and one passing through the annular portion 16.

The gas ejected from the gas ejection holes 10 b is held in the small holes 15 of the flame holding plate 12 and the outer edge of the flame holding plate 12. The flame formed in the vicinity of the main nozzle 10a becomes fuel-excessive low-oxygen combustion, and the flame temperature decreases and the oxygen partial pressure decreases, so that the generation of thermal NOx is reduced.

On the other hand, the secondary air is ejected from the secondary air ejection hole 8 through the secondary air passage 23, and flows into the air cone 9 through the recirculation passage 24. At this time, the combustion gas in the furnace is sucked by the flow of the secondary air passing through the inside of the gap 14 to the low pressure formed near the gap 14, and is recirculated together with the secondary air to the recirculation passage 24. A self-recirculation that flows through the air cone 9 through the air. The flow of the self-recirculating flow in which the secondary air and the combustion gas are mixed is bent toward the center of the nozzle by the cone portion, and penetrates into the inside of the burning flame. This infiltration lowers the flame combustion temperature and the oxygen partial pressure in the combustion section, so that the thermal N
Ox generation is suppressed.

According to this embodiment, the recirculation of the combustion gas is promoted by the secondary air flowing into the air cone, and the flame combustion temperature and the oxygen partial pressure of the combustion section are increased by the combustion gas penetrating into the flame together with the secondary air. Thermal NO
Since the generation of x is suppressed and the downstream side of the air cone 9 is narrowed toward the center, the secondary air can sufficiently penetrate into the incomplete combustion area inside the flame, and Generation of carbon oxide and the like is prevented. Also, since the recirculation is performed effectively, the pressure of the fuel gas is reduced to 200 mmA.
Even at a low pressure of about q, sufficient low NOx combustion is performed.

In the above embodiment, the combustion gas is recirculated through the annular gap 14, but the cylindrical portion of the air cone 9 and the outer cylinder 21 are formed as a continuous cylinder, and a plurality of independent openings are formed in the cylindrical surface. May be provided to communicate the secondary air passage 23 or the recirculation flow path 24 with the combustion chamber, and the combustion gas may be recirculated through these openings. Furthermore, if the shape of the opening is an ejector shape using secondary air as a driving fluid, it is possible to further promote the recirculation of the combustion gas.

[0016]

According to the present invention, an air cone is provided at the tip of the nozzle to separate the combustion chamber from the base of the flame, and secondary air is ejected through the air cone to regenerate the combustion gas. Since circulation is performed, low-pressure gas can be used for the gas burner, and the burner air differential pressure can be reduced, so that the conventional gas pipe and combustion blower can be used without being changed, and the combustion exhaust gas can be used. Low NO
x conversion is easy. In addition, since the structure is simple and the combustion blower is small, the equipment cost is low, the noise is low, and the energy consumption is small.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line II-II of the embodiment shown in FIG.

FIG. 3 is a longitudinal sectional view showing an example of the prior art.

4 is a IV-IV line arrow cross-sectional view of an example of a prior art shown in FIG.

[Explanation of symbols]

Reference Signs List 1 wind box 1a air passage 2 back plate 3 primary air hole 4 nozzle pipe 5 nozzle pipe holder 6 spark rod 7 frame rod 8 secondary air ejection hole 9 air cone 10a main nozzle 10b gas ejection hole 11 pilot burner 12 flame stabilizing plate 14 Skimmer annular portion 15 Small hole 16 Annular portion 20 Inner cylinder 21 Outer cylinder 21a End plate 22 Primary air passage 23 Secondary air passage 24 Recirculation passage 30 Blower for combustion

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Showa 50-55232 (JP, U) Japanese Utility Model Showa 58-1808 (JP, Y2) (58) Fields surveyed (Int.Cl. ⁶ , DB name) F23D 14/22 F23C 11/00 320

Claims (1)

(57) [Scope of request for utility model registration] 1. A main nozzle having a gas ejection hole for ejecting a fuel gas obliquely outward with respect to a nozzle center line, and a fuel nozzle arranged to concentrically cover the periphery of the main nozzle and burn around the main nozzle. In a gas burner including an inner cylinder forming a primary air passage for ejecting air, a secondary air passage formed axially along an outer peripheral surface of the inner cylinder, and a downstream end of the inner cylinder A cylindrical portion concentrically arranged at a distance that becomes a recirculation flow path between the outer peripheral surface and a cone portion connected to the downstream end of the cylindrical portion and having a tip inclined toward the nozzle center line. An air cone configured to allow the secondary air ejected from the secondary air passage to flow into the upstream end of the recirculation flow path, and formed near the cylindrical portion of the air cone and / or the downstream end of the secondary air passage. And said recirculation channel and / or Comprises a recirculation opening which communicates with the combustion chamber through the secondary air passage, the cone portion is the re循
Flow direction of the mixed gas of secondary air and combustion gas that has exited the circulation channel
To change the direction of the burning flame toward the nozzle center line
Low NOx gas burner characterized by being arranged in a place .