JPS6298111A - Burner device - Google Patents

Abstract

PURPOSE:To prevent production of NOx and to enable combustion with high efficiency through reduction of an unburnt content in ash, by a method wherein a funnel-shaped collision disc (target) is situated to the outlet of an injection nozzle, and the collision surface is formed with a sloped surface formed at a specified angle with the central axis of a burner. CONSTITUTION:Fuel 2 flows in an annular manner along the outer periphery of an burner gun inner cylinder, and after the fuel is mixed with a pulverized medium, the mixture is injected in a furnace. In which case, the fuel 2 is pushed aside to the one side of an injection nozzle 6 by means of a pulverized medium 3 fed through a pulverized medium feed hole 5, and forms a liquid film on the inner wall surface of the injection nozzle. Meanwhile, the liquid film is divided at the outlet end surface of the injection nozzle 6 to produce bulky liquid drop, which, in turn, is collided with the surface of a target 10 for repulverization. The target 10 is formed with a funnel- shaped ring, spread toward the end and having a gentle spreading angle thetat with the central axis of a burner, and a spray angle thetat of 10 deg. or more, e.g., about 25-40 deg., is suitable to combustion of high concentration coal and water slurry. As noted above, spray is formed in the shape of a rounded hanging bell, and forms O2 excessive combustion at the outer edge of flame, resulting in the possibility of reducing production of NOx.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a burner device, and in particular to a burner device suitable for achieving high efficiency and low pollution combustion of slurry fuel in which finely powdered solids are suspended in liquid. It is related to the device.

(Prior Art) FIG. 10 shows an axial cross-sectional view of a so-called Y-jet type atomizer, which is most commonly used in actual C-fired boilers. As shown in the figure, this atomizer chip 1 is
It consists of an atomizing medium supply hole 5 provided at the tip of the central atomizing medium 3 passage, a mixing passage 6 connected to this, and a fuel supply hole 4 for allowing fuel to flow into the mixing passage 6. .

However, this atomizer has a high ejection speed (ignition tends to be unstable), and a liquid film is unevenly formed inside the mixing nozzle, which breaks up at the exit edge and forms coarse droplets. This results in a long flame and a considerable delay in burnout over the entire combustion process.Furthermore, even if you try to achieve low NOx '1p-4 combustion by adjusting the air register in the burner, the flame lifts and a stable reduction zone cannot be created. Therefore, this Y-jet atomizer cannot be used for combustion of CWM (high concentration coal water slurry) with the structure as it is. Can not.

FIG. 11 shows an axial cross-sectional view of an atomizer in which a collision plate (ceramic target I-) 7 is provided at the outlet of the ejection hole in order to compensate for the drawbacks of the Y-jet type atomizer.

This atomizer is expected to re-atomize coarse droplets by collision, widen the spray angle and reduce the ejection speed in the burner axis direction, improving flame stability. When testing (500 kg/b) was carried out, it was pointed out that the spray angle was too large.

In addition, in the figure, 8 is a cover made of Kinku, and 9 is a set screw. In other words, it was found that the spray droplets penetrated to the outside in the Harnazun radial direction, and in burners with strong swirling, they were tightly ignited in the mixing area with the tertiary air, resulting in an increase in NOx, contrary to what was initially expected. Ta. I also experienced a 1-rubble in which unburned spray collided with the burner throat, which was also caused by the spray angle being too large. If we try to reduce the spread angle of the spray while maintaining this target structure, that is, if we reduce the apex angle of the Couget, the surface area of the target, that is, the collision area of gas and liquid, will decrease, and the spray particle size will increase. This results in the following drawback.

In any case, the present situation is that the current collision method cannot be used to improve combustion in CWM.

(Problems to be Solved by the Invention) An object of the present invention is to solve the above-mentioned drawbacks of the prior art (particularly to improve ignitability with respect to the combustion of slurry fuel in which finely powdered solids are suspended in a medium liquid at a high concentration). and improve flame holding performance, reduce unburned matter in ash, and reduce emissions No.
It is an object of the present invention to provide a direct-acting, low-pollution burner device that also reduces heat generation.

(Means for solving the problem) In short, the present invention fixes a funnel-shaped target that gradually expands in the radial direction from the central axis to the atomizer chip from the outside, and collides the gas-liquid mixture with the funnel-shaped target to re-atomize the target. This aims to promote atomization by oxidation, and at the same time, the spray is made to form a hollow cone shape with a not very large angle. That is, in the present invention, after mixing the atomization medium and fuel supplied from each flow path in the mixing flow path,
In a burner device having a two-fluid atomizer that injects fluid from a nozzle into the furnace, a funnel-shaped collision plate is provided at the outlet of the nozzle, and the angle between the collision surface of the collision plate and the burner central axis is It is characterized by having an inclined surface having an angle of at least 10° or more.

In the present invention, it is preferable that the outer periphery of the collision plate is provided with a rim having an angle of 0° or more with respect to the central axis of the burner and smaller than the inclination of the collision plate.

Also, on the circumference coaxial with the mixing nozzle holes, at least one or more holes for injecting only the atomization medium between each mixing nozzle hole,
It is preferable that the angle of incidence with respect to the surface of the collision plate is at least O'' or more.The hole through which only the atomization medium is injected is provided through an orifice-like restriction having an inner diameter smaller than that of the atomization medium flow path. It is preferable that the atomizing medium supply hole is connected to the atomizing medium chamber. Furthermore, it is preferable that the diameter of the atomizing medium supply hole is smaller than the diameter of the mixing jet hole.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

(Example) FIG. 1 is a front view of a burner device (collision two-fluid atomizer) according to the present invention, and FIG. 2 is a sectional view taken in the A direction and B direction of FIG. 1.

In this burner device, the atomizer chip 1 has a passage 18 for the atomized medium 3 provided on its central axis, two passages for the fuel 2 provided annularly on the outer circumferential side of the medium passage 18, and two passages for the fuel 2 provided at the tip thereof. It consists of a fuel supply hole 4 provided, mixing injection holes 6 through which the atomization medium and fuel flow and mix, and atomization medium injection holes 15 provided alternately between the mixing injection holes 6. The mixing nozzles 6 are arranged such that their outlets are spaced at equal intervals on the circumference of the furnace-side outer surface of the atomizer chip.

In addition, the spreading angle (
(one-sided swing) is set as θi.

An orifice 13 for the atomization medium is provided at the tip of the atomization medium passage 18, and an atomization medium chamber 14 is provided at the end (downstream side) of the atomization medium passage 18, and furthermore, from the side wall of the atomization medium chamber 14, an atomization medium chamber 14 is provided.
Atomization medium holes 15 are installed in the direction of zero. This atomization medium hole 15 is provided for the purpose of injecting only the atomization medium onto the target 10 and removing the interference portion of the outer edge quantum of the spray that spreads in a fan shape on the target. Since the atomization medium chamber 14 is essentially an integral part of the atomizer chip 1, it is provided by drilling a hole with the same diameter from the furnace side, inserting a blind lid 14A, and sealing it by welding. Good. The diameter of the orifice 13 is determined to match the total cross-sectional area of the atomization medium supply holes 5. Furthermore, if the diameter of the atomizing medium outlet hole 15 is smaller than the diameter of the mixing outlet hole, for example, 1/2, the pressure inside the atomizing medium chamber 14 will become high, and the atomizing medium will be directed toward the atomizing medium hole 15 more than necessary. It will no longer flow away. The atomizing medium holes 15 are arranged on the circumference of the furnace-side surface of the atomizer chip 1 through the mixing nozzle holes 6.
The exit is placed between the two.

The target 10 is formed of wear-resistant ceramics, and consists of a funnel-shaped ring that widens toward the end and has a gentle expansion angle θt with respect to the burner central axis, and is fixed to the target fixing tube 11 with a camp nut 12. The camp nut 12 is provided to prevent fragments from falling even if the target 10 is damaged. Since the spray angle is defined by θt, targets with θt varied as necessary are used.

From the experimental results so far, it has been found that θt = about 25 to 40'' is suitable for CWM combustion. θt
must be smaller than the angle θi of the mixing nozzle with respect to the burner central axis (θt<θi). △θ=θi−
θt becomes the collision angle (so-called incident angle) of the gas-liquid mixture (atomization medium and fuel) with respect to the target surface. It is preferable to provide a protruding tab IOA on the outer peripheral edge of the target. This dented IOA was provided for the purpose of stripping off the fuel liquid film that spreads on the target nod, but the fuel adheres to the periphery of the target (debosito).
It also has the effect of preventing The angle θe of the tabbed IOA with respect to the burner center needs to be θe>0°. θ
When 6<0'', the flow pattern collapses and tends to result in a non-uniform spray flow.Mixing nozzle 6 and Couget 10
The positional relationship may be such that the extension of the central axis of the mixing nozzle 6 reaches the surface of the target 10 or the edge 10A.

In the apparatus shown in FIGS. 1 and 2, the atomization medium (e.g. steam, compressed air, etc.) 3 is supplied from the atomization medium flow path 18, and after being squeezed through the atomization medium supply hole 5 of the atomizer chip 1. It enters the mixing nozzle 6. The fuel 2 flows annularly around the outer circumference of the burner gun inner cylinder, is supplied to the mixing nozzle 6 from the fuel supply hole 4 having an outlet on the side wall of the mixing nozzle 6, and is injected into the furnace after being mixed with the atomization medium. . At this time, the fuel 2 is supplied to the atomization medium supply hole 5 as shown in FIG.
The atomizing medium 3 supplied by the atomizing medium 3 pushes the liquid to one side of the ejection hole 6, and forms a liquid film on the inner wall surface of the ejection hole. The surface of the liquid film is shaped aerodynamically by the atomizing medium, causing minute droplets to break up from the surface. On the other hand, the liquid film splits at the exit end face of the jet hole 6 and becomes coarse droplets, which then hit the surface of the target 10 and become re-atomized. promoted.

The collision also causes the spray to spread and slow down, resulting in a rounded, bell-shaped spray flow pattern. The penetration power of the spray droplets in the radial direction decreases and they do not fly to the outer periphery of the flame. Therefore, at the outer edge of the flame, there is 0□excessive combustion, and N
Ox can be reduced.

FIG. 4 is a diagram schematically showing the effect of injecting the atomizing medium 3 from the atomizing medium injection hole 15 in FIG. 3 and preventing interference between the outer edges of the fan-shaped spray. In this way, in addition to the effect of the case shown in FIG. 3, it is possible to prevent the atomized droplets from coalescing and maintain good atomization.

5 and 6 are front views showing examples of the positional relationship between the mixing jet hole 6 and the atomizing medium hole 15, respectively. Fig. 5 shows a case in which mixing ejection holes 6 and atomizing medium holes 15 are arranged alternately and at equal intervals on the circumference of the furnace side surface of the atomizer chip, and Fig. 6 shows an example in which the mixing ejection holes 6 are arranged in two ways. They are arranged so as to be sandwiched between the atomizing medium holes 15, and are designed to further suppress interference between sprays than in the case shown in FIG. In this way, when the number of atomizing media holes is increased, the diameter in FIG. 6 needs to be smaller than the diameter in FIG. 5.

Figures 7 to 9 show experimental data when using the present invention with conventional two types of cheek atomizers (Figures 10 and 11).
This is shown in comparison. In both cases, conditions other than the gas-liquid ratio were not changed because we were trying to find out the performance of the atomizer.

FIG. 7 shows the average spray particle size 132. This shows the changes in In contrast to the conventional collisional two-fluid atomizer (Fig. 11) with a cone-shaped target atomizer (Fig. 1O), the 3λ is smaller due to the re-atomization effect caused by collision. However, when the atomizer of the present invention (Figures 1 and 2) is used, Jxz is further reduced and atomization is promoted.This means that even if the collision surface (target) is the same, the atomizer of the present invention It is thought that the re-atomization effect was carried out efficiently because the gas-liquid collision area was large.

Next, Figure 8 shows each at? N for gas-liquid ratio in isa
It shows the change in Ox. The figure shows that the atomizer of the present invention has the lowest NOx. This is because a stable reducing atmosphere was created in the vicinity of the burner because the atomization was improved and ignition was promoted. In the present invention, the conventional colliding two-fluid 71-miser (FIG. 11) is improved so that the spray angle can be made small, so that the spray becomes bell-shaped. Therefore, the spray droplets do not advance to the outer periphery of the burner, and 02 excessive combustion occurs in the secondary combustion region, thereby reducing NOx. In this way, NOx can be reduced to, for example, 15 Qppm or less with a single burner. This can be said to be the greatest achievement of the present invention.

FIG. 9 shows the change in the unburned fraction in ash with respect to the gas-liquid ratio for each atomizer. As described above, since the atomizer of the present invention has good atomization, ignition is significantly promoted, and coal particles in the spray liquid layer are burned out fairly quickly. Therefore, the percentage of unburned matter in the ash decreases, and the combustion efficiency increases.

Furthermore, since the impact surface (target) is made of ceramic, which has excellent wear resistance, the spray combustion characteristics did not deteriorate even after long-term combustion tests, and it was confirmed that the spray combustion characteristics were highly reliable. .

The atomizer according to the present invention can be used not only for CWM but also for almost all other liquid fuels, and has similar effects. In other words, in addition to C heavy oil, which is a normal boiler fuel, other slurry fuels that are said to be N-flammable (coal/methanol slurry, oil coke/water slurry, pitch/water slurry, COM, high fuel ratio coal (fuel ratio = Even for slurries using fixed carbon/volatile matter) and poor quality residues (asphalt, etc.), the atomization is extremely good, so flammability (ignitability and burnout performance) is slightly improved, making combustion easier. Increased efficiency. Furthermore, even for such a fuel with a high N content, as described above, a stable reduction zone is created near the burner, and the outer periphery of the flame becomes 0□ excessive combustion, making it possible to reduce NOx.

Furthermore, even when used as an atomizer for an ignition torch that uses light oil, smoke generation ( It is possible to prevent the generation of soot.

(Effect of the invention) The effects of implementing the present invention are as follows.

(1) Since a flame with good flame stability can be formed, a stable reduction zone is created near the burner, and since the spray is bell-shaped, the spray does not penetrate to the secondary combustion area, so 02 excessive combustion occurs. achieved, the extrusion of NOx can be suppressed.

(2) In conjunction with the above-mentioned improvement in flame stability, high efficiency combustion can be achieved because the amount of unburned matter in the ash is reduced.

(3) Since the consumption amount of the atomization medium can be reduced, less auxiliary power is required.

As described above, implementing the present invention is effective for energy saving and environmental protection measures, and a very large combustion improvement effect can be obtained.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of the burner device of the present invention, FIG. 2 is a sectional view taken in the direction of arrows A and B in FIG. 1, and FIG. 3 is a front view of an embodiment of the burner device of the present invention. FIG. 4 is a partial cross-sectional view showing the principle of promoting atomization, and FIG. 4 is a diagram schematically showing the effect of removing the interference part of the spray by injecting the atomization medium. FIGS. Figures 7, 8, and 9 show the arrangement of mixing nozzles and atomizing medium injection holes in the burner device of the present invention, and compare the experimental results using the burner device of the present invention with the conventional device. 10 is a sectional view showing a conventional intermediate mixing type two-fluid atomizer (Y-jet type atomizer).
FIG. 1 is a sectional view showing a conventional collision-type two-fluid atomizer in which a collision plate (target) is attached to the device shown in FIG. 10. DESCRIPTION OF SYMBOLS 1... Atomizer chip, 2... Fuel, 3... Atomization medium, 4... Fuel supply hole, 5... Atomization medium supply hole, 6... Mixing ejection hole, 7...・Ceramic collision plate (target), 10... collision plate (target),
11...Target fixing tube, 12...Kinkure cover,
13... Orifice for atomization medium, 14... Atomization medium chamber, 15... Atomization medium injection hole, 16... Spray flow, 17... Flow of atomization medium, 18... Atomization media passage. Agent Patent Attorney Takeshi Kawakita Diagram 1 Gas-liquid ratio Wa/W? (-) Figure 8 Gas-liquid ratio Wa/W! (-) Gas-liquid ratio Wa/W! (-) Figure 10 Figure 1I

Claims (6)

[Claims] (1) In a burner device having a two-fluid atomizer that mixes the atomized medium and fuel supplied from each flow path in a mixing flow path and then injects the fuel into the furnace from a nozzle hole, a funnel-shaped collision occurs at the outlet of the nozzle hole. A plate (target) is provided, and the angle between the collision surface of the collision plate and the burner center axis is at least 10
A burner device characterized by comprising an inclined surface having an angle of at least . (2) Claim (1) is characterized in that the outer periphery of the collision plate is provided with a rim having an angle of 0° or more with respect to the central axis of the burner and smaller than the inclination of the collision plate. Burner device. (3) The burner device according to claim (1) or (2), wherein the collision plate is fixed to the atomizer body from the radially outer surface of the burner with a metal cover. (4) In any one of claims (1) to (3), a hole that injects only at least one atomizing medium between each mixing nozzle on a circumference coaxial with the mixing nozzle. , the angle of incidence with respect to the collision plate surface is at least 0°
A burner device characterized by being provided as described above. (5) In claim (4), the hole that injects only the atomization medium is connected to the atomization medium chamber provided through an orifice-like restriction having an inner diameter smaller than the atomization medium flow path. A burner device characterized by: (6) A burner device according to claim (4) or (5), characterized in that the diameter of the atomization medium supply hole is smaller than the diameter of the mixing jet hole.