JPH08261442A - Combustion device in furnace - Google Patents

Abstract

PURPOSE: To effect high air ratio combustion as well as low air ratio combustion excellently and restrain the generation of unburnt constituents such as NOX, CO and the like, in a furnace. CONSTITUTION: A combustion device is provided with a plurality of burner devices 4, 5, provided on the front surface of a furnace for effecting the premixing combustion of high air ratio combustion and the premixing combustion or diffusion combustion of low air ratio combustion respectively, partitioning walls 1a, 1b, provided in the furnace to burn respective burner devices independently respectively, and baffles 2a, 2b, provided at the downstream side of the partitioning walls 1a, 1b in the furnace and mixing the combustion gas of the plurality of burner devices 4, 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus in a furnace such as a gas fired boiler.

[0002]

2. Description of the Related Art FIG. 4 is a plan view of a furnace to which a conventional low NO _x gas combustion method is applied and which is provided with gas burning burner devices at four corners.
5 shows a sectional view of the gas-fired burner device installed at the four corners of the furnace.

In a conventional furnace to which a low NO _x gas combustion system is applied, a gas-fired burner device 1 installed at four corners of the furnace.
1a to 11d to low air ratio premixed flame or diffusion flame 1
3 and a plurality of high-air-ratio premixed flames 12 surrounding the premixed flames or the diffusion flames 13 are individually formed and burned (hereinafter referred to as corner firing concentrated combustion).

FIG. 6 is a plan view of another different conventional furnace to which the low NO _x gas combustion system is applied. In this furnace, a gas-fired burner device is installed on the front surface, and this burner device is adapted to perform combustion similar to that shown in FIG. In a furnace to which this low NO _x gas combustion method is applied, a high-air-ratio premixed flame 12 and a low-air-ratio premixed flame or diffusion flame 13 are individually formed from a gas-fired burner device 11 installed in front of the furnace. It employs a gas combustion method (hereinafter referred to as front firing dark and light combustion), which is characterized by burning and burning.

Any of the conventional low NO described above_xHow to burn gas
Also in the equation, NO in gas combustion shown in FIG._xCharacteristic
Are using. That is, as shown in FIG. 7, premixed combustion
Then, a convex N having an apex near the air ratio of 1.0 to 1.1
O_xCharacteristic 14 shows that with diffusion combustion, as the air ratio increases
NO_xNO increases_xCharacteristic 15 and air ratio 1.0
The following premixed combustion (point b in the figure) or diffusion combustion (a in the figure)
Point) and premixed combustion with an air ratio of 1.0 or more (point c in the figure).
NO by doing sometimes_xIs reduced (d in the figure ₁point,
d₂Point).

[0006]

The conventional low NO _x gas combustion system has the following problems.

(1) In the case of performing the corner firing density combustion in a small furnace, it is necessary to install a plurality of gas-fired burner devices at the four corners of the furnace, which increases the cost.

(2) Since the high-air-ratio premix burner device and the low-air-ratio burner device are arranged adjacent to each other and burn in one furnace, the flame of the high-air-ratio premix burner device is And low-air-ratio burner flames interfere. Therefore, at the air ratio set in each burner device, what was originally to be burned could not be realized, and flame temperature rise due to flame interference occurred to raise NO _x .

(3) Front firing When performing rich-burn combustion, surplus air supplied from a high-air-ratio premixing burner device and unburned gas generated from a low-air-ratio burner device are not sufficiently mixed and CO Fuel is generated.

The present invention is intended to provide a combustion apparatus in a furnace capable of solving the above problems.

[0011]

A combustion apparatus in a furnace according to the present invention comprises a plurality of burner devices which are provided in front of the furnace and which perform high air ratio premixed combustion and low air ratio premixed combustion or diffusion combustion, respectively. A partition wall provided in the furnace for independently performing the combustion of each of the burner devices, and a baffle provided downstream of the partition wall in the furnace for mixing the combustion gases of the plurality of burner devices. To do.

[0012]

It is difficult to avoid flame interference when simultaneously performing combustion with different air ratios in one furnace as in the conventional furnace described above. However, in the present invention, combustion of a plurality of burner devices is performed respectively. Combustion is performed in a furnace with partition walls that are designed to be operated independently so that combustion can be performed without impairing the combustion characteristics of high-air-ratio premixed combustion and low-air-ratio premixed combustion or diffusion combustion. In addition, it is possible to avoid an increase in NO _x due to flame interference.

On the other hand, since the partition wall is installed in the furnace, it is not possible to sufficiently mix the unburned gas generated from the low air ratio burner device and the surplus air supplied from the high air ratio burner device. . Therefore, a baffle is installed on the downstream side of the partition wall of the furnace to promote mixing of combustion gas,
Unburned components such as CO can be suppressed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG.

The gas fired furnace has side water cooling walls 3a, 3a.
b, two partition walls 1 provided in the furnace and arranged from the upstream side toward the downstream side so as to divide the inside of the furnace into approximately three equal parts
a, 1b and the baffles 2a, 2b having a right-angled triangular shape provided on the water cooling walls 3a, 3b so as to project into the furnace in the rear part of the furnace downstream from the partition wall 1.

The combustion device is a gas-fired burner device 4 for performing premixed combustion with an air ratio of 1.0 or more, preferably a high air ratio of 1.2 to 1.6, and an air ratio of 1.0 or less, preferably 0.5. ~
It is composed of a gas-fired burner device 5 that performs premixed combustion or diffusion combustion with a low air ratio of 0.9. The burner units 4 and 5 are provided on the front surface (upstream side) of the furnace, the burner unit 5 is arranged in the center, and the two burner units 4 are arranged on both sides of the burner unit 5. The high-air-ratio premixed flames 4a and 4b are formed between the water cooling wall 3a and the partition wall 1a and between the water cooling wall 3b and the partition wall 1b, and the low air ratio flame 5a in the burner device 5 is located between the partition wall 1a and the partition wall 1b. It is formed and burned.

In this embodiment, the high air ratio premixed flame 4a,
4b and the low air ratio flame 5a are burned by the partition wall 1
It is performed independently in the part divided by a and 1b,
Mixing of these combustion gases starts from the outlets of the partition walls 1a and 1b, and mixing is promoted by the baffles 2a and 2b to complete combustion.

As described above, the combustion by the burner units 4 and 5 is independently performed in the interior of the furnace divided by the partition walls 1a and 1b, so that the air ratios set by the burner units 4 and 5 are different from each other. the combustion characteristics is performed efficient combustion without loss, and can suppress the NO _x increases by flame interference.

Further, since the combustion gases from the burner units 4 and 5 are promoted to be mixed by the baffles 2a and 2b, the surplus air supplied from the burner unit 4 with a high air ratio is burned with a burner with a low air ratio. It is possible to suppress unburned substances such as CO by mixing with the combustion gas from the device 5.

The low-air-ratio burner device 5 having an air ratio of 1.0 or less may be either a device for performing premixed combustion or a device for performing diffusion combustion as described above, and the partition wall 1
As a, 1b and baffles 2a, 2b, a refractory material or a water pipe structure can be used.

In the first embodiment, the partition walls 1a, 1b
A second embodiment of the present invention in which a baffle 2c is installed also in the center of FIG. 2 is shown, and a gas-fired high-air-ratio premixing burner device 4 and a gas-fired low-air-ratio burner device 5 are each provided. A third embodiment of the invention as a set is shown in FIG.

Also in these embodiments, the same operation and effect as those of the first embodiment can be obtained.

The combination of the high-air-ratio premix burner 4 and the low-air-ratio burner 5 can be selected as appropriate, such as one pair to one pair, two pairs to one pair, and two pairs to two pairs.

Although the first to third embodiments relate to a combustion apparatus in a gas fired furnace, the present invention relates to a combustion apparatus in a liquid fuel fired furnace such as heavy oil and a solid fuel fired furnace such as pulverized coal. Can be applied.

[0025]

According to the present invention, the following effects can be obtained by installing the burner device, the partition wall and the baffle described in the claims in a furnace.

(1) By installing partition walls in the furnace for independently performing combustion by each burner device, high-air-ratio premixed combustion and low-air-ratio premixed combustion or diffusion combustion can be independently performed by the partition walls. Therefore, efficient combustion can be realized with the air ratio set in each burner device, and the flame temperature rise due to flame interference can be suppressed, and NO _x can be reduced. .

(2) The baffle installed downstream of the partition wall in the furnace separates the combustion gas from the low air ratio burner unit and the combustion gas from the high air ratio burner unit starting from the partition wall outlet. Mixing can be promoted and unburned components such as CO can be suppressed.

(3) By installing the partition wall and the baffle in the furnace, CO is also generated in the front firing combustion.
Since it becomes possible to suppress equal unburned components and reduce NO _x , cost reduction can be achieved as compared with the conventional corner firing combustion.

[Brief description of drawings]

FIG. 1 is a plan view of a first embodiment of the present invention.

FIG. 2 is a plan view of a second embodiment of the present invention.

FIG. 3 is a plan view of a third embodiment of the present invention.

FIG. 4 is a plan view of a conventional corner firing type furnace.

FIG. 5 is a cross-sectional view of a gas-fired burner device used in the conventional corner firing dark and lean combustion type furnace.

FIG. 6 is a plan view of a conventional front-fired dark / light combustion type furnace.

FIG. 7 is a diagram showing a relationship between an air ratio and NO _x in gas combustion.

[Explanation of symbols]

1a, 1b Partition wall 2a, 2b, 2c Baffle 3a, 3b Water cooling wall 4 High air ratio gas-fired burner device 4a, 4b High air ratio premixed flame 5 Low air ratio gas-fired burner device 5a Low air ratio flame 11 Gas fired NO _x characteristic in NO _x characteristic 15 diffusion combustion in the burner apparatus 11a~11d gas fired burner unit 12 high air ratio premixed flame 13 low air ratio flame 14 premixed combustion

Claims (1)

[Claims] 1. A plurality of burner devices provided in front of a furnace for performing premixed combustion with a high air ratio and premixed combustion or diffusion combustion with a low air ratio respectively, and combustion of each of the burner devices provided in a furnace. A combustion apparatus in a furnace, comprising: a partition wall that is independently operated; and a baffle that is provided on the downstream side of the partition wall in the furnace and that mixes combustion gases of the plurality of burner devices.