JPH0617737B2 - Slurry fuel combustion device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a slurry combustion device, and particularly to a boiler device suitable for preventing generation of coarse particles at the time of spraying and reducing the amount of unburned fuel and NOx in exhaust gas. Regarding

<Prior Art and Its Problems> FIGS. 4 and 5 show an example of a conventional burner atomizer structure suitable for burning a slurry having a high viscosity. An atomizer disclosed in JP-A-60-36811 is similar to this.

FIG. 4 is a side cross-sectional view of the cylindrical burner atomizer passing through the central axis, in which the slurry 1 passes through the central passage on the axial center and the spray medium 2 passes through the annular passage on the outside thereof. The medium passage is bent at a right angle in the mixing piece 4, and a plurality of medium holes 8 are formed at the outlet of the slurry passage 9 in the first mixing chamber 3 at a right angle to the axis as shown in the sectional view taken along the line AA of FIG. It is provided to collide. Further, the slurry and atomizing spray medium discharged from the first mixing chamber 3 enter the second mixing chamber 6 in the sprayer plate 5, are mixed in the chamber, and are sprayed into the atmosphere from the outlet nozzle 7 to complete atomization.

This nozzle mixes the slurry and the medium in the two stages of the first and second mixing chambers, so that the atomization inner line ( Streaks (generation of coarse particles) hardly occur, and relatively average atomization can be efficiently obtained. However, the flow velocity of the slurry and the atomizing medium in the first mixing chamber is 2 to 50 m / m
s, 100 to 250 m / s, and the inner surface of the mixing chamber 3 at the collision portion may be greatly worn. In particular, when a plurality of medium holes 8 collide with the atomizer central axis radially toward the axial center, if there are variations in the manufacturing accuracy of the medium holes 8 and a slight deviation of the central axis of the holes, the medium at the collision part The flow collides with the wall surface of the cylindrical mixing chamber 3 by hitting the slurry flow, causing uneven flow, and the shape of the inner wall does not wear evenly, causing abnormally uneven wear and causing a mixed spray atomization function. Cause major obstacles. In the second mixing chamber 6, as shown in FIG. 4, the slurry and the medium collide with each other while colliding with the tip end side of the sprayer plate, and the slurry flows along this wall surface so that the outlet nozzle hole is crossed. There are cases in which coarse particles are jetted to the outside as they are, or when they spread in the mixing chamber and hit the inner wall on the tip side of the sprayer plate, if there is a chimney outlet nozzle 7, they will jump out to the atmosphere without hitting the wall. As described above, due to the abnormal uneven wear in the first mixing chamber and the resulting poor mixing of the slurry and the medium, the atomization performance is deteriorated, and further, the generation of the wall surface slurry flow and the insufficient ejection collision in the second mixing chamber are caused. It is possible that the atomization performance is deteriorated due to the generation of coarse particles from the ejection nozzle and the combustibility is deteriorated.

<Object of the Invention> The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art,
It is an object of the present invention to provide a burner that suppresses the generation of coarse particles during the spraying of slurry and improves the atomization performance, and at the same time reduces the abrasion of the inner wall of the atomizer in the collision mixing section.

<Summary of Means> In summary, the present invention is a device in which a spray medium is supplied and spray fuel is spray-combusted from an outlet nozzle of a second mixing chamber communicating with the first mixing chamber.
An annular medium passage 8a, which is coaxial and orthogonal to the slurry flow, is provided between the inlet end surface of the mixing section, and a cross-sectional apex angle for forming a reversal flow is formed following the surface having the outlet nozzle 7a on the inner furnace side of the second mixing section. Cone-shaped protrusion C to make an obtuse angle and an annular recess E following it
The slurry fuel combustion apparatus is characterized in that a protrusion 10 and a protrusion 10 are provided.

<Embodiment> FIGS. 1 and 2 show an embodiment of the present invention. The mixing piece 4a of the cylindrical burner atomizer has a slurry passage 9 as a passage for the slurry 1 and a concentric annular passage 8 for the atomizing medium 2 in the axial center portion. Next, the mixing piece 4b, which is in contact with this piece on a disk-shaped surface, has a space of the first mixing portion 3 of the slurry and the medium on the coaxial center, and the upstream portion thereof has a space as shown in the front view of FIG. There is an annular medium passage 8a of narrow width orthogonal to the slurry flow. The outlet of the first mixing section spreads out into a mortar-shaped space and is further connected to and integrated with the second mixing section 6a formed by the sprayer plate 5 which is in contact with the disk-shaped surface. At the outlet of this space, there are a plurality of outlet nozzles 7a having a spread with respect to the axis of the atomizer. Inside the pitch circle, the front portion of the sprayer plate (on the furnace side)
The inner wall side is a cone-shaped protrusion 10 with an apex at the axis and an apex angle of obtuse angle.
Have.

An annular recess E is provided between the bottom of the conical protrusion and the inlet end of the outlet nozzle 7a to turn the fuel mixed with the atomizing medium into a reverse flow.

In the mixing part of the slurry and the spray medium, the cross section of the slurry has a circular flow, whereas the spray medium flows in a slit-like uniform manner from the circumferential part, and since it collides with the flow of the slurry, mixing is performed from the entire circumference of the slurry. Is spotless and does not cause local drift. In this way, the atomization necessary for combustion is performed, so that the first-stage mixing is performed sufficiently to obtain good combustion. Further, by spraying the spray medium at a right angle to the flow direction of the slurry and making the mixing distance about twice the inner diameter of the mixing portion (l / d≈2 in FIG. 1), the mixing of both fluids does not hinder the slurry flow and the efficiency is improved. It can be performed well, and at the same time, since the spray medium flows along the inner wall surface of the cylindrical space of the mixing section, it is possible to prevent the slurry from hitting the inner wall surface and prevent the wall material from being worn.

Next, in the second mixing section, it is necessary to mix the slurry and the medium as uniformly as possible before being injected from the outlet nozzle 7a, which prevents uneven generation of coarse particles at the time of injection into the atmosphere at the final stage. Fine spray particles can be formed as a whole. For this reason, as shown in FIG. 1, the second mixing portion is not chamfered in the conventional square or pentagonal shape, but the corner portion is chamfered at about 45 °, and the slurry jet on the front side of the sprayer plate is formed. A recess E is provided on the inner surface of the collision with. This shape has a protrusion on the axial center of the slurry jet and has a mortar-like recess F and a recess E.
The corner portion on the furnace side (excluding the intersection point C described later) in the second mixing portion is chamfered like the other corner portions of the mixing chamber. That is, by making the corners, which are the connecting parts with the curved surface, a gentle shape (round-off), and by arranging the center position of the protrusions for clarity, as shown in FIG. A circulating flow of the slurry medium mixture 12 which is axisymmetric with respect to the axis can be formed. If the outlet nozzle 7a to the atmosphere is provided at a position other than the hollow portion in the mixing portion, a part of the circulating flow can be taken out to the outside air as a uniform mixed slurry with the medium, and a good spray can be obtained.

Here, the important point is that the cylindrical inner surface G of the mortar-like recess F in FIGS. 1 and 3 is made parallel to the atomizer center axis and the intersection C with the inner wall surface of the mixing portion at the location where the outlet nozzle is provided is chamfered ( Round off). This prevents the slurry flow from colliding with the surface including the depression E and the protrusion 10 and then turning around 180 ° along the inner wall surface of the cylinder, and from flowing out from the intersection C to the outlet nozzle in the state of the slurry liquid film. Then, it is circulated toward the inside of the mixing chamber. For this reason, the slurry liquid film is broken in the mixing section and the uneven flow of density is eliminated, and only the slurry that has been sufficiently mixed with the atomizing medium is ejected and atomized as the slurry that emerges from the outlet nozzle. To more fully fulfill these features,
As what should be further improved, when the space size (depth size) a in the atomizer axial direction of the second mixing section and the size in the direction orthogonal to this (b) are b, the size ratio of a / b is 1: 1 to 1: 2. It is preferable that When this dimension ratio is 3rd
Two circular circulation flows are formed above and below the center axis (called radial or line-symmetrical when viewed from the front of the atomizer), and good mixing of the slurry and medium in the mixing section is obtained. To be Further, the inner diameter of the hollow portion E is the spread angle α of the slurry jet with respect to the dimension a in the axial direction in the mixing portion in FIG.
It is preferable that the spread of the jet flow in the case of (see FIG. 1) can be caught in the depression, so that the liquid film-like flow colliding with the inner wall of the front surface of the sprayer plate of the slurry can be more completely generated. It is possible to prevent discharge from the outlet nozzle directly to the atmosphere and improve atomization of the jet.

By adopting the above dimensional ratio and shape and applying a ceramic lining-like fitting material to the inner wall surface of the atomizer after mixing, it is possible to maintain wear resistance and durability against collision of a high-speed slurry medium mixed flow. Becomes

Further, the outlet nozzle 7a is symmetrical with respect to the axis (for example, 5 pieces).
Alternatively, it may be provided on the object or on a plurality of sides.

In addition, the NOx reduction effect due to the imbalance in the amount of spray may be obtained by making the outlet nozzle 7a a plurality of hole diameters.

<Example 2> Although a slurry was shown as the object of the atomizing fluid in the above example, if it is a two-fluid atomizing method using air or steam as the atomizing medium, the atomized fluid may be oil or other fluids. Similar effects can be achieved.

The final outlet nozzle 7a for the slurry and the medium is written on the assumption that it is a circular perforation on the same pitch circle in the figure, but it should be appropriately arranged in a combination with different divergence angles, pitch circles, hole diameters, etc. This makes it possible to optimize the mixing with combustion air and reduce unburned components and NOx.

Further, the corner portion of the mixing chamber has a chamfered planar shape in consideration of the labor in working in the embodiment, but it is ideally a circular cross section for forming the circulation flow of the medium-slurry mixture. In this case, the circulation flow can be formed more smoothly.

<Effects of the Invention> The effects of the implementation of the present invention are as follows: (1) uneven distribution of the slurry and the medium is achieved by supplying the medium in the form of a disk slit from the outer periphery of the slurry in the first mixing section of the slurry and the medium. And the abrasion of the inner wall surface of the mixing portion can be prevented.

(2) It is easy to disassemble, inspect and clean the collision area.

(3) The ratio E of the second mixing chamber axial direction distance to the inner diameter direction distance is set to 1: 2, and the depression E is provided on the inner surface of the front wall of the sprayer plate.
Moreover, the chamfered shape of the corner portion of the mixing chamber prevents the generation of a rough flow due to the liquid film of the slurry ejected from the outlet nozzle and improves the atomization performance.

(4) Unburned content and NOx at the time of combustion can be reduced.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a burner atomizer showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line BB in FIG. 1, and FIG. 3 is a sectional view inside a second mixing chamber in FIG. Drawing which shows a slurry flow typically, Drawing 4 is a longitudinal section of a conventional burner atomizer,
FIG. 5 is a sectional view taken along the line AA of FIG. 1 ... slurry 2 ... spraying medium 3 ... first mixing part 8a ... medium passage 5 ... sprayer plate 6a ... second mixing part 7a ... exit nozzle 11 ... ceramics E ... annular recess

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masato Nozawa Masato Nozawa 2-6-2 Otemachi, Chiyoda-ku, Tokyo Inside Babkotuk Hitachi Co., Ltd. (56) Reference JP-A-58-168806 (JP, A) Showa 48-37844 (JP, U)

Claims (3)

[Claims] Claim: What is claimed is: 1. In a spray-combustion method in which a slurry medium is spray-combusted from an outlet nozzle of a second mixing chamber communicating with the first mixing chamber, the end surface of the slurry passage is located between the end surface of the slurry passage and the inlet end surface of the first mixing portion. An annular medium passage (8a) coaxial with and orthogonal to the slurry flow is provided on the inner surface of the second mixing section, which has an outlet nozzle (7a) on the inner furnace side, and has an obtuse cross-section apex angle for forming a reversal flow. A slurry fuel combustion device comprising a conical protrusion (C), an annular recess (E) following the conical protrusion (C), and a protrusion (10). 2. The slurry fuel combustion apparatus according to claim 1, wherein the plurality of outlet nozzles of the second mixing section have the same diameter. 3. The slurry fuel combustion apparatus according to claim 1, wherein the plurality of outlet nozzles of the second mixing portion are nozzles having a plurality of diameters.