JPS62242711A - Radiant tube burner - Google Patents

Abstract

PURPOSE:To provide a radiant tube burner capable of performing a stable superior combustion and accomplishing a low NOx by a method wherein a central port of a flame dispersion type nozzle is made as a water atomization nozzle and the nozzle is connected through and added water transitting pipe arranged in a gas burner to an atomized water generating unit capable of supplying pressurized gas and added water. CONSTITUTION:Fuel gas to be supplied to a gas burner 1 is injected from a flame dispersion type nozzle 3 into a combustion cylinder 2, agitated with a primary combustion air C1 circulated by primary air circulation vanes 7. After the fuel gas performs a reduction primary combustion under a high load and then is discharged from a combustion cylinder 2. In turn, a secondary air C2 distributed at a specified ratio in respect to the primary air C1 is flowed along the inside part of the tube while cooling the combustion cylinder through an annular passage between the combustion cylinder 2 and the radiant tube 8 and a secondary combustion is carried out in sequence without producing any local heating an interface part of the primary combustion gas. Atomized water got through the atomization generating unit 18 is injected into the flame from an injection nozzle 13 placed at a center of the flame dispersion type nozzle 3 to decrease a flame temperature and thus it becomes possible to make a substantial reduction of generation of NOx.

Description

Detailed Description of the Invention The present invention has a gas burner nozzle facing concentrically into a combustion tube provided in a radiant tube, and directs the fuel gas ejected from the gas burner between the gas burner and the combustion tube. The present invention relates to a radiant tube that performs primary combustion using primary air supplied through an annular space and secondary combustion using secondary air supplied through an annular space between the combustion tube and the radiant tube, and more specifically relates to a radiant tube that performs primary combustion using primary air supplied through an annular space and secondary combustion performed using secondary air supplied through an annular space between the combustion tube and the radiant tube. This relates to a water-addition type low NOx radiant tube that reduces NOx by adding atomized water to the tube, and particularly limits the type of pressurized gas and the atomization method.

[Conventional technology]

In such a radiant tube burner, NOx
According to Japanese Patent Publication No. 52-290-07, a steam pipe is provided inside the fuel gas nozzle to suppress the occurrence of
It has been proposed to reduce the flame temperature by blowing steam into the flame formed by burner combustion. Therefore, when comparing steam blowing and water spraying, water spraying is more effective in lowering the flame temperature and is also more effective in reducing NOx.

However, it was considered impossible to put it into practical use because it was predicted to have a negative effect on the radiant tube and to make the flame unstable due to the drawback that the spray particle size becomes large.

[The interlayer point that the invention attempts to solve]

The present invention achieves good and stable combustion by performing high-load combustion with a swirling flow of large air, performs soft two-stage combustion within the radiant tube, and adds atomized water to the self-combustion flame. The present invention provides a method of lowering the flame temperature by doing so, and a radiant tube burner that can achieve low NOx by blowing combustion exhaust gas as an atomization medium into the center of the fuel gas.

[Means to resolve the issue]

Therefore, according to the present invention, the center opening of the nozzle configured as a flame dispersion type nozzle is used as a water spray nozzle, and the pressurized gas and additive water are supplied to the nozzle through the additive water transfer pipe provided inside the gas burner. It is connected to a possible atomizing water generator.

Furthermore, as another advantageous measure, the atomized water generator is provided with a cylinder with a conical hole to be connected to the additive water transfer pipe and a pressurized gas and additive water blowing groove to be fitted into this. It is composed of a concave disk having a recess and a housing containing the cylinder and the disk.

In the present invention, pressurized gas (air, steam,
Inert gas) 2 kg/cm” ~ 6 kg/cm
Water addition by atomization method according to the range of 1 and low pressure gas (fuel gas, combustion exhaust gas, etc.) 300mmAq ~ 1,000
There is water addition by atomization method in the range of mmAq.

〔Example〕

Next, the present invention will be explained in more detail with reference to an embodiment of the atomization method using pressurized gas shown in FIGS. 1 to 3.

Figures 1 and 213! If, gas burner l
is the combustion W installed concentrically around this burner L.
It has a flame dispersion nozzle 3 projecting into J2, to the rear end of which a gas connection pipe 4 is connected, and behind the combustion tube 2 there is a primary air supply which likewise surrounds the burner concentrically. A tube 5 is formed continuously, and four primary air inlets 6 are bored around the circumference thereof. Further, on the tip of the gas burner l, a primary air swirling vane 7 having an angle of 15 to 60' is fixed via a holding cylinder (not shown), and the outer periphery of the combustion cylinder 2 and the primary air supply pipe 5 is fixed. is provided with a radiant tube 8, the large air supply pipe and the radiant tube each being closed off at an end wall 11 via a flange 9.10, through which the gas burner l extends. Further, in the center of the flame dispersion type nozzle 3 screwed onto the tip of the gas burner l, there is a water spray nozzle 13 communicating with the added water transfer pipe 12 in the burner, and around it a plurality of gas spray nozzles communicating with the gas connecting pipe 4. A spout 14 is provided.

In addition, behind the radiant tube 8, there is an air supply pipe '1.
At the rear end of the additive water transfer ff12 is attached an atomized water generation a1g to which pressurized gas and additive water supply pipes 16.17 are connected.
9 passes through the end wall ll and one end faces the flame dispersion type nozzle 3.

Next, as shown in FIGS. 3 and 4, the atomized water generator 18 includes a disk 21 having a circular recess 20 and a central conical hole 22 whose diameter gradually decreases from the diameter corresponding to the recess. A cylinder 23 having the same diameter as the disc is integrally formed by coaxially fitting together, and this is incorporated into the housing 24. In this case, the disc 21 is inserted and inserted with a plug 25. The cylinder 23 is connected to the added water transfer pipe 12, and the atomized water generation chamber 2 is connected by fitting the disk and cylinder.
6 is formed. On the end face of the disc 21, which is closer to the cylinder 23, there are blowing grooves 27, 28 for introducing pressurized gas and added water, which lead tangentially into the circular recess 20 and into said circular recess.
is engraved on one surface perpendicular to the central axis,
These grooves are connected to a pressurized gas supply pipe 16 and an added water supply pipe 17, respectively.

Next, an embodiment of the atomization method using low pressure fuel gas and low pressure exhaust gas shown in FIGS. 7 and 8 will be described.

In FIG. 7, the gas burner 1 has a flame dispersion nozzle 3 protruding into the combustion tube 2 which is provided concentrically around the burner, and a gas connecting pipe 4 is connected to the rear end thereof. A water outflow nozzle 29 is provided in the center of the flame dispersion type nozzle, and a gas swirl vane 3 is provided in the annular space formed by these water outflow nozzles and the exhaust gas nozzle.
0 is provided, and the angle of this gas swirl vane is 15° to 40°.
It is set in the range of °.

In this way, the fuel gas G introduced into the gas burner 1 from the gas connection pipe 4 is fed in the direction of the arrow, and the gas swirl vane 30
On the other hand, the water W introduced into the additive water transfer pipe 12 connected to the additive water connection port 31 is fed in the direction of the arrow and flows out from the water outflow nozzle 29. In this case, the water flowing out from the water outflow nozzle is atomized by the injection energy of the fuel gas.

In this way, since the water is atomized by the fuel gas, the atomized water and fuel gas are well mixed, increasing the effect of adding water and lowering the flame temperature, which can significantly reduce the generation of NOx. becomes.

Next, in FIG. 8, similarly to FIG. 7, the gas burner l has a flame dispersion type nozzle 3 at its tip, and an exhaust gas introduction tube 3 for spraying water from a water outflow nozzle 29 at its center.
2.Additional water transfer pipe in the center of this introduction tube! 2, a water outflow nozzle 29 is provided in the center of the flame dispersion type nozzle, and an exhaust gas swirl vane 3 is provided in the annular space formed by these water outflow nozzles and the exhaust gas nozzle.
0', and the blade angle is set in the range of 15° to 40°.

In this way, the exhaust gas G' becomes a high-speed swirling airflow by the exhaust gas swirling vane 30', and the water W flowing out from the water outflow nozzle 29
This sprayed water is mixed with the fuel gas from the flame dispersion type nozzle 3 by the high-speed swirling airflow of the exhaust gas.
), the mixing of exhaust gas and fuel gas and the mixing of fuel gas and spray water occur rapidly, and the flame salinity decreases due to the uniformity of the flame temperature due to the combustion delay of the fuel gas and the endothermic absorption of the vapor latent heat of the spray water. This makes it possible to significantly reduce the generation of NOx.

[Effect]

Now, when the fuel gas supplied to the gas burner l via the connecting pipe 4 is ejected from the flame dispersion nozzle 3 into the combustion tube 2, the gas flows in through the inlet 6 and undergoes air swirling. It is stirred together with the primary combustion air C1 swirled by the blades 7, and after performing reduction-fire combustion under high load, it is ejected from the combustion tube 2.

On the other hand, secondary air C is distributed at a constant ratio to the primary air C by an air adjustment damper (not shown). The gas flows through the annular passage between the combustion tube 2 and the radiant tube 8 along the inside of the tube while cooling the combustion tube, and is sequentially subjected to secondary combustion without local heating at the interface between the combustion gas and the combustion gas.

The flame is ejected from the injection nozzle 13 located at the center of the mold nozzle 3 to lower the temperature of the flame and suppress the generation of NOx. The foam expands rapidly and bursts due to the difference in pressure between the pressure inside the combustion cylinder and the foam, but since the thickness of the foam is extremely thin, for example 0.1 μm or more, the fragments of the burst foam become extremely fine. These fine water particles remove the latent heat of vaporization from the flame and lower the flame temperature, thereby making it possible to significantly reduce the generation of NOx. 4 [Effects of the Invention] The NOx fl reduction rate by adding water with the radiant tube according to the present invention is shown in the relationship between the amount of added water and the NOx reduction rate in FIG.

Operating conditions of the radiant tube burner of the present invention are as follows: Fuel COC: 4,500 kcal/Nd combustion 1j
: 145 s 000 kc aJ
! /h Combustion air temperature: 400℃ Remaining in exhaust gas: 4% Radiant tube: Finch W type, gradually increasing the amount of added water to reduce NOx a reduction rate (%
) saw.

As is clear from these results, the addition of water in the radiant tube burner of the present invention has the effect of reducing NOx, and also lowers the maximum tube temperature, making the life of the radiant tube sustainable for long periods of use. It became possible.

[Brief explanation of drawings]

Fig. 1 is an axial sectional view of a radiant tube burner according to the present invention, Fig. 2 is a longitudinal sectional view of a flame dispersion type nozzle in this burner, and Figs. 3 and 4 are an atomized water generator similar to the previous one. Figure 5 is a diagram explaining the generation of atomized water, Figure 6 is a diagram showing the amount of added water and NOx reduction rate, and Figure 7 is a diagram showing the atomization method using low-pressure fuel gas. FIG. 8 is an axial sectional view showing the main parts of another embodiment of the present invention that employs an atomization method using low-pressure combustion exhaust gas. It is. l...Gas burner, 2...Combustion tube, 3...Flame dispersion type nozzle, 8...Radiant tube, 12...
Added water transfer pipe, 13... Water spray nozzle, 16... Pressurized gas supply pipe, 17... Added water supply pipe, 18... Atomized water generator, 20... Circular recess, 21...disk, 2
2... Conical hole, 23... Cylinder, 24... Housing, 26... Atomized water generation chamber, 27... Pressurized gas blowing groove, 28... Added water blowing groove, 29 ...Water outflow nozzle, 30...Gas swirl vane, 30'...
Combustion exhaust gas swirl vane, 31...Additional water connection port, 32.
・・Exhaust gas introduction pipe, Cz ・−Next air, C 鴬・・
・Secondary air. Patent applicant: Japan Combustion System Co., Ltd. Mitsubishi Heavy Industries, Ltd. Added water volume and NOx reduction rate wA1m water volume Htg / io, 0OOkcat')
Figure 7

Claims (1)

[Claims] 1. A nozzle of a gas burner is arranged concentrically facing a combustion tube provided in a radiant tube, and fuel gas ejected from the gas burner is supplied through an annular space between the gas burner and the combustion tube. In a burner of the type that performs primary combustion using primary air and secondary combustion using secondary air supplied through an annular space between the combustion tube and the radiant tube, the center opening of the nozzle configured as a flame dispersion type nozzle is A radiant tube burner comprising a water spray nozzle connected to an atomized water generator capable of supplying pressurized gas and added water via an added water transfer pipe provided inside the gas burner. 2. A cylinder having a conical hole to which the atomized water generator is to be connected to the additive water transfer pipe, a recess disk having a pressurized gas and additive water blowing groove to be fitted into the cylinder, and these cylinders. Radiant tube burner according to claim 1, comprising: and a housing containing an inner plate. 3. The method according to claim 1, characterized in that the water outflow nozzle is installed in the center of the flame dispersion type nozzle in order to spray water from the added water transfer pipe using the injection energy of the fuel gas. Radiant tube burner. 4. Claims characterized in that the exhaust gas introduction pipe and the water outflow nozzle are installed in the center of the flame dispersion type nozzle in order to spray water from the added water transfer pipe using the injection energy of the pressurized combustion exhaust gas. Radiant tube burner according to item 1.