JPS6157961B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention deals with nitrogen oxides (hereinafter referred to as NOx) in exhaust gas.
This invention relates to a burner device suitable for reducing

Recently, since NOx in exhaust gas emitted from boilers and other combustion devices contributes to air pollution, various methods have been attempted to reduce NOx. Examples of such reduction measures include exhaust gas recirculation,
There is a two-stage combustion system, but the exhaust gas recirculation system requires a blower for exhaust gas recirculation and special power for the blower. In addition, the two-stage combustion method requires equipment such as a duct for introducing secondary air and a secondary air fan, and both methods have the drawback of increasing the size and complexity of the equipment.

An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a burner device that can reduce NOx in exhaust gas without installing special devices such as ducts and blowers.

In short, this invention disposes a sleeve at the tip of the burner that supplies secondary combustion air to the furnace at a large angle with respect to the central axis of the burner, and uses this secondary air flow to create a negative pressure in the center of the burner flame so that the combustion exhaust gas This is to reduce the generation of NOx.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Reference numeral 1 denotes a fuel atomizer, and the burner tip 2 and flame holding plate 3 provided on the burner tip 2 are located at the center of the burner throat 5 of the furnace 18. Reference numeral 6 denotes a primary air sleeve, which is arranged concentrically around the atomizer 1 so that one side opens to the wind box 4 side and the other side opens to the burner throat 5 side. A sleeve 7 is provided near the furnace side end of the primary air sleeve 6 so as to come into contact with and slide on the outer peripheral surface of the sleeve 6. The base of this sleeve 7 that comes into contact with the primary air sleeve 6 is cylindrical, or in other words, has the same shape as the outer periphery of the primary air sleeve 6, but its tip expands into a conical shape toward the furnace 18 side. It's on. This widening angle is set to be approximately the same as or slightly smaller than the furnace side opening slope 5a of the burner throat 5, which is widened in the shape of a truncated cone. Reference numeral 19 denotes an operating rod having one end fixed to the sleeve 7 and the other end protruding outside the window box 4 and provided with a handle 10. A pipe 9 is provided at the window box insertion portion of the operating rod 19, and the operating rod 19 is configured to slide within the pipe 9. Reference numerals 11a and 11b are stops provided inside and outside the window box 4 with the pipe 9 in between, and 8 is a bolt for fixing the operating rod 19.

In the above configuration, the combustion air 14 sent from the blower (not shown) flows into the primary air sleeve 6 at the wind box 4.
2 and the sleeve 7 from the outer periphery of the primary air sleeve 6.
and secondary air 13 passing through the gap of the burner throat 5. Among these, the flow rate of the primary air 12 is preferably about 10 to 40% of the theoretical air amount at maximum combustion of the burner, so the gap between the primary air sleeve and the flame holding plate 3 allows the above amount of primary air to pass through. Flame holding plate 3 and primary air sleeve 6
Determine the location and fix it.

A part of this primary air 12 is used for flame stabilization by forming a high temperature recirculation area downstream of the flame stabilizing plate 3, and the rest is used to continue combustion in the burner until it comes into contact with the secondary air 13. used for.
On the other hand, the secondary air 13 is accelerated from the outer peripheral part of the primary air sleeve 6 to the parallel part 5b of the burner throat 5, that is, the narrowest part of the air passage area, and is accelerated by the furnace side opening slope 5a of the burner throat 5 and the sleeve 7. It is ejected from an annular gap opening in the diffusion direction with respect to 18. As a result, the secondary air 13 is diffused in the furnace 18 at a constant angle with respect to the burner central axis, and is further attracted by the flow of the primary air 12 and this secondary air 13 and diffused.
Therefore, the flame 17 spreads widely within the furnace and burns as shown in the figure. As a result, flame 1 spread in a funnel shape.
The center of the combustion chamber 7 becomes a negative pressure, and a part of the combustion exhaust gas 15 that has been completely combusted is recirculated as a recirculation gas 16 toward the burner ignition point. This recirculated gas 16
When the combustion air reaches near the burner ignition point, it is sucked in and mixed with the primary combustion air 12 and secondary combustion air 13 that are about to spread outward, thereby reducing the oxygen concentration in the combustion air and suppressing the generation of NOx. It should be noted that, as shown by the arrows in the drawing, a portion of the primary air flowing between the flame stabilizing plate 3 and the sleeve 7 flows inside the flame stabilizing plate 3, forming a small vortex, and This will maintain the flame and ensure stable combustion.

Particularly at low loads, the width of the primary air flow path between the flame stabilizing plate 3 and the sleeve 7 is adjusted to stabilize low load operation with stable flame stabilization. In the above combustion process, the operator slides the sleeve 7 using the operation stick 19 and appropriately fills the gap formed between the sleeve 7 and the furnace-side opening slope 5a of the burner throat 5 to prevent recirculation gas. 16 circulation volume can be adjusted.

According to this invention, exhaust gas recirculation is performed by creating a negative pressure at the center of the flame, which eliminates the need for a blower for exhaust gas recirculation and a duct for recirculation, making it possible to downsize the device. This eliminates the need for power costs, making it possible to reduce NOx extremely economically.

In addition, the amount of recirculated gas can be adjusted simply by sliding the sleeve, and it has various effects such as excellent operability.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a combustion device equipped with a burner device according to the present invention. 1... Fuel atomizer, 3... Flame holding plate, 4...
Wind Box, 5... Burnus Throat, 5a
... Burner throat furnace side opening slope, 6 ... Primary air sleeve, 7 ... Sleeve, 9 ... Pipe,
10...Handle, 11a, 11b...Stopper, 12...Primary air, 13...Secondary air, 15
... Combustion exhaust gas, 16 ... Recirculation gas, 18 ...
Furnace.

Claims (1)

[Scope of Claims] 1. A fuel atomizer having a flame stabilizing plate in the burner throat and a primary air sleeve arranged concentrically around the outer periphery of the fuel atomizer to suppress the generation of NOx, wherein a furnace is attached to the tip of the primary sleeve. A NOx burner characterized by having a sleeve with an enlarged truncated conical opening toward the side. 2. Claims characterized in that a sleeve provided at the furnace side end of the primary air sleeve is slidable relative to the primary air sleeve, and an operating rod for sliding the sleeve is provided on the sleeve. The low NOx burner described in item 1.