JPS5995308A - Low nox burner - Google Patents

Abstract

PURPOSE:To obtain a low NOX burner whose mixture of after-air and fuel is favorable at all times irrespective of a load variation of the burner, by mounting an injection cylinder in a variable state of an injection direction with respect to an after-air port. CONSTITUTION:An after-air injection cylinder 23 is arranged to an after-air port 15 formed on a wall 22 of a furnace so as to enable to change an injecting direction centering around the pivot 25. After-air in a wind box 17 flows into the injection cylinder 23 set in a predetermined injecting direction after turning force has been given to the after-air by an air resistor 21, and burns unburnt fuel by mixing the unburnt fuel, which has been asecended within a fire furnace 1, with the after-air by injecting it in a predetermined direction. In the meanwhile, the after-air to be injected from a space part 27 formed on the circumference of the injection cylinder 23 is injected and fed evenly close to the injection cylinder 23, through which burning of the unburnt fuel is performed effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low NOx combustion device that improves after-air mixing.

Nitrogen oxides (hereinafter referred to as “NOx”) are one of the air pollutants.
The following methods are used to reduce the amount of carbon dioxide (hereinafter abbreviated as ) at the stage of combustion within a combustion device. Among these, the two-stage combustion method involves forming the main combustion zone with less than the theoretical air amount, the exhaust gas recirculation method involves recirculating the exhaust gas to the main combustion zone to perform low 02 combustion, and the in-furnace denitrification method. creates a combustion zone with an extremely low air ratio in a part of the combustion zone, producing reducing intermediate products, and the resulting N
It reduces Ox in the gas phase. Since all of these combustion methods achieve low NOx by performing low-oxygen combustion or low-humidity combustion, there is a risk of generating a considerable amount of unburned matter, and the emission of unburned matter will result in There is also the possibility of secondary pollution. For this reason, in each method, afterair is supplied in order to burn the unburned components downstream of the main combustion zone. Here, the supply of afterair should be kept at an amount necessary and sufficient for the combustion of unburned matter; supplying a large amount of afterair will instead increase the amount of NOx produced.

Conventionally, in combustion equipment such as large boilers for business use, an after-air port is formed downstream of the main combustion zone, that is, at the top of the boiler furnace, and after-air is injected and mixed into the unburned components that have risen inside the furnace. It was configured to allow In this case, the injection direction of the afterair is predetermined in a fixed direction, and if the flow of gas in the furnace changes, the mixing of the afterair and unburned matter tends to become poor. Specifically, there is a problem with the after-air jetting force.

An object of the present invention is to provide a low NOx combustion device which is constructed in view of the above-mentioned problems, and in which after air is always mixed well regardless of load fluctuations of the combustion device.

In short, the present invention provides a low-pressure fuel tank configured to always maintain a good mix of after-air and unburned matter by arranging a substantially cylindrical injection cylinder relative to the after-air port and making the injection direction of this injection cylinder variable. This is a NOx combustion device.

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

Figures 1 and 2 show a human boiler for industrial use that performs low NOx combustion. In the figure, on the front wall of the furnace 1, there are a plurality of front lower burners 3. Front middle burner 4
．． A front upper stage burner 5 is arranged, and a rear lower stage burner 6, a rear middle stage burner 7, and a rear upper stage burner 8 are respectively arranged against the rear wall of the furnace. For each burner group, each wind box 9, 10.11
and 12.13. '14 are arranged so that the air ratio of the burners trr in each stage can be controlled.

Next, numerals 15 and 16 are after air ports with low NO.
x Burn the unburned matter generated by combustion.

Taking the after air port 15 as an example, the after air port 15 is formed and arranged on the furnace wall 22 in FIGS. 3 and 4. Reference numeral 23 denotes after-air injection oil that is arranged through a certain annular space 27 with respect to the after-air port 15, and the injection direction is moved up and down by a drive device (not shown) around a rotating shaft 25 that is arranged almost horizontally. It is configured so that it can be changed to Although the illustrated example shows a vertical change, the rotation axis can be arranged vertically to change the injection direction to the left or right, or in some cases, the injection direction can be changed freely using a universal joint. 611f may also be configured. Note that the air port 16 formed in the rear wall has the same structure as this air port 15. Note that the reference numeral 18 in the figure is a wind box placed with respect to the airport 16.

In the above t41j configuration device, the after air in the wind box 17 is given a swirling force by the air register 21, and then flows into the injection cylinder 23 set in a predetermined injection direction, and is injected in the predetermined direction to the furnace. The inside is mixed with the unburned matter that has been converted to -H, and the unburned matter is combusted. On the other hand, a portion of the afterair is also injected from the space 27 formed around the injection cylinder 23. While the after air injected from the injection tube 23 flows toward the center of the furnace, this after air is injected near the furnace wall and evenly supplied, thereby effectively burning unburned matter.

By implementing this invention, low N in the main combustion zone can be achieved.
Unburned matter generated by Ox combustion can be almost completely combusted by good mixing with after air, and there is no risk of secondary pollution caused by discharge of unburned matter.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the low NOx combustion device according to the present invention, Fig. 2 is a main view taken along line A-A in Fig. 1, Fig. 3 is a sectional view taken along B gP:J+ in Fig. 2, and Fig. 4 is a sectional view taken along line A-A in Fig. 1. The figure is C- in Figure 3.
It is a parent figure by C line. 1... Furnace 15.16... After Airport 17.18.
... Wind box 23 ... After air injection tube 25 ... Rotation +l1lI+

Claims (1)

[Claims] 1. In systems where unburned matter generated in the main combustion zone is combusted by after-air supplied from an after-air port, an injection cylinder is attached to the after-air port formed on the furnace wall so that the injection direction can be changed, thereby reducing fluctuations in the gas flow within the furnace. 1. A low NOx combustion device characterized in that the after air injection direction can be changed in accordance with the following.