JP2001041684A - Soot blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove ash efficiently even if the quantity of high pressure gas to be used is equal to that of a conventional soot blower. SOLUTION: In order to produce a narrow sectoral jet flow 8 of high pressure gas 4 being supplied to the lance tube 1 of a soot blower, a substantially rectangular opening having long side L1 and short side L2 is employed in each nozzle 7a, 7b. L1 and L2 are set to satisfy a relation 1.6<=L1/L2<=10.0 and the enlarging angle at each of the opening is set at 3-20 deg. between the inlet side and the outlet side. The short side L2 is directed in the widthwise direction of a heating tube 3 at the time of placing on the lance tube 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soot blower for blowing out gas from a nozzle disposed on the side of a lance tube to remove combustion ash attached to a heat transfer tube.

[0002]

2. Description of the Related Art In a combustion furnace such as a commercial boiler or an industrial boiler, various small particulate combustion ash (hereinafter, referred to as "combustion ash") is generated in a combustion process.
It is called ashes. ) Occurs. If a large amount of this ash adheres to the heat transfer section and the furnace wall, the heat transfer efficiency of the boiler decreases. Further, if a large amount of ash adheres, the flow path of the combustion gas becomes narrow, and the pressure loss in the furnace increases, which hinders the operation of the boiler. Furthermore, depending on the composition of the ash, the heat transfer tube may be corroded. Therefore, it is common practice to dispose a soot blower near the heat transfer section and periodically remove ash attached to the heat transfer section.

FIGS. 14A and 14B are views showing the structure of the tip of a conventional soot blower, wherein FIG. 14A is a front view and FIG. 14B is a longitudinal sectional view. The soot blower is configured by disposing nozzles 2a and 2b at the tip of a long lance tube (tube) 1. The cross sections of the openings of the nozzles 2a and 2b are circular, and the nozzles 2a and 2b have a circular cross section.
It is slightly displaced in the axial direction to the position of 80 °, in other words, it is arranged stepwise.

FIG. 15 is a perspective view showing an operation state of the soot blower. In the figure, 3 is a heat transfer tube. When removing the ash attached to the surface of the heat transfer tube 3, high-pressure steam or air (hereinafter, referred to as high-pressure gas 4) is supplied into the lance tube 1, and the lance tube 1 is rotated around the axis O. While moving forward or backward in the direction of the axis O.

The high-pressure gas 4 ejected from the nozzles 2a and 2b
Is a conical jet 5 that spreads radially as it goes away from the nozzles 2a, 2b. Then, when the jet 5 collides with the surface of the heat transfer tube 3, the ash attached to the heat transfer tube 3 is removed by the kinetic energy of the jet.

[0006]

In recent years, the types of liquid fuels have been diversified, and so-called inferior vacuum residual oils and ultra-heavy oils containing a large amount of minerals having low melting points of ash produced by combustion are also used. It became so. Coal containing a large amount of minerals that produce ash having a low melting point has been frequently used. Ash having a low melting point easily melts when it comes into contact with a high-temperature heat transfer surface and adheres to the heat transfer surface. Then, as the subsequent ash adheres to the molten ash one after another and gradually accumulates, bridges (bridges) are formed by the ash between the heat transfer tubes constituting the heat transfer portion.

FIG. 16 is a cross-sectional view of a heat transfer section schematically showing a state in which a bridge 6a is formed by the ash 6 attached to the heat transfer tube 3. When a large amount of ash having a low melting point is formed, the bridge 6a may be generated in a short time. Jet 5
Is conical, so that it is possible to simultaneously remove a wide range of ash while spreading. However, since the impact pressure is relatively evenly applied to the collision part of the jet 5, when a bridge 6a is formed between the heat transfer tubes 3, it is necessary to remove the bridge 6a without fail. There was a problem that it was not possible. In order to surely remove the bridge 6a, if an impact pressure is applied intensively to the site, the jet flows through the heat transfer tube group to reach the tube row behind, and the entire jet group is operated. It is believed that the attached ash can be removed in a chain.

On the other hand, in order to increase the removal rate of the attached ash 6 and bridge 6a, the supply pressure of the high-pressure gas 4 may be increased. However, if the supply pressure is increased without changing the nozzle diameter, the consumption of the high-pressure gas 4 increases. For this reason, when air is used as the high-pressure gas 4, a blower with a large capacity is required, and when steam is used as the high-pressure gas 4, the efficiency of the boiler is reduced. On the other hand, if the injection pressure is increased by reducing the diameter of the nozzle to make the consumption amount of the high-pressure gas 4 the same, the life of the nozzle itself is shortened due to thermal stress or the like. Also, in order to prevent leakage of the high-pressure gas 4,
The structure becomes complicated such as multiple seals.

An object of the present invention is to solve the above-mentioned problems in the prior art and to provide a soot blower capable of efficiently removing ash even when the consumption of high-pressure gas is the same as that of the prior art.

[0010]

In order to solve the above-mentioned problems, the present invention provides a soot blower for blowing out gas from a nozzle disposed on a side of a lance tube to remove combustion ash attached to a heat transfer tube. The opening shape was substantially rectangular.

In this case, the long side of the substantially rectangular opening is provided in parallel with the longitudinal direction of the heat transfer tube to be removed. When the lengths of the two sides of the rectangular opening are L1 and L2, respectively, the relationship between the two is 1.6 ≦ L.
1 / L2 ≦ 10.0 range, the opening angle θ of the opening side of the two sides facing the opening with respect to the entrance side,
It is set in the range of 3 ° ≦ θ ≦ 20 °.

In addition, a plurality of small-diameter nozzles each having a circular opening shape are arranged in a direction substantially orthogonal to the longitudinal direction of the lance tube in place of the rectangular opening portion, and the shape of the jet flow ejected from the nozzle is changed from the rectangular opening portion. The small-diameter nozzle may be arranged so as to approximate a jet to be jetted. In this case, the spread angle β of the outlet of the small-diameter nozzle with respect to the inlet may be set in a range of 3 ° ≦ β ≦ 16 °.

[0013] The nozzle mounted on the lance tube and ejecting the jet is of a substantially rectangular shape, in other words, a non-circular type, and moreover, is a compromise between a substantially rectangular shape and an elliptical shape. Such an elongated opening corresponds to the arrangement of the heat transfer tube group from which the ash is to be removed. Specifically, when the heat transfer tube group is vertically suspended, the shape of the opening of the nozzle is made longer in the circumferential direction of the cylindrical lance tube.
On the other hand, when the heat transfer tube group is installed in the same direction as the advance / retreat direction of the lance tube, the opening shape of the nozzle becomes longer in the longitudinal direction of the lance tube, in other words, in the advance / retreat direction of the lance tube. To do.

Assuming that the width of such a non-circular flat opening nozzle is L1 and the length is L2, the relationship between the two is 1.6 ≦ L1 / L2 ≦ 10.0, preferably 2.1 ≦ L1. It is selected from the range of L1 / L2 ≦ 4.0. Note that the case of L1 = L2 is a circular opening nozzle conventionally used. The opening area even in the nozzle of the rectangular opening, such one is formed longer than the other as described above, for configuring the equivalent circular nozzle, holds the relationship of L1 · L2 = (π / 4 ) D 2 .

On the other hand, a flat jet can be approximately flattened by arranging nozzles having a reduced opening diameter without using a nozzle having a flat opening (one having a rectangular opening formed longer than the other). A good jet can be obtained.
In this case, since the total opening area of the nozzles is uniform, if the throat diameter of the small-diameter nozzle is Ds and the number of small-diameter nozzles in the nozzle row is n, then n (π / 4) Ds ² = (π / 4) D ² Therefore, Ds = D / √n.

When such small-diameter nozzles are employed, the small-diameter nozzles may be provided in the circumferential direction of the lance tube or in the longitudinal direction in order to prevent interference between jets ejected from the small-diameter nozzles. It is desirable that the small-diameter nozzles are arranged side by side at a predetermined distance.

According to this structure, the jets ejected from the nozzles having the rectangular openings or the small-diameter nozzles arranged side by side are fan-shaped and flat, and collide intensively between the tubes of the heat transfer tube group. The impact pressure is intensively applied to the bridge formed between them, and the bridge is broken. Further, since the jet flow is flat, when the bridge is broken, the jet easily passes through the space between the pipes and reaches the inner side more easily, colliding with the heat transfer pipe, and losing less energy, so that the ash removal ability at a portion away from the nozzle is also improved. That is, since the jet does not spread radially axisymmetrically, the energy continues to the downstream region, and ash attached to the deep portion of the heat transfer tube group far away from the nozzle can be removed.

As described above, the conventional soot blower uses an axially symmetric jet, so that the impingement pressure is applied irrespective of the arrangement of the tube rows. On the other hand, the soot blower according to the present invention employs the transmission pressure. Since the direction of the ash adhering between the heat tube row and the tube (the direction of continuous bridging) is parallel, the impact pressure is intensively applied using a flat jet that spreads along the parallel direction It is.

[0019]

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

FIG. 1 is a front view showing the structure of the tip of a soot blower according to a first embodiment of the present invention, and FIG.
FIG. 3 is a cross-sectional view of FIG.
The same reference numerals are given to the same portions as 6 and the description is omitted. 1 and 2, two nozzles 7a and 7b are arranged at a position 180 ° from each other with respect to the axis O of the lance tube 1 and slightly shifted in the axial direction.
The openings of the nozzles 7a and 7b are substantially rectangular, and are opened such that a direction perpendicular to the longitudinal direction of the lance tube 1 is a long side and a direction parallel to the short side is a short side. The four corners are rounded. In addition, the long side L1 and the short side L
The ratio of 2 (L1 / L2) is set in the range of 2.1 ≦ L1 / L2 ≦ 4.0. Further, the spread angle θ of the opening exit side with respect to the entrance side is set in the range of 5 ° ≦ θ ≦ 15 °.

FIG. 4 is a cross-sectional view of the heat transfer section showing a state when the high-pressure gas 4 starts jetting from the nozzles 7a and 7b.
FIG. 6 is a perspective view showing a state in which high-pressure gas 4 is ejected, FIG. 6 is a cross-sectional view of a heat transfer unit showing a state of removal of ash 6, and FIG.

Since the cross sections of the openings of the nozzles 7a and 7b are substantially rectangular, the cross section of the jet 8 blown out from the nozzles 7a and 7b is flat, and the side shape is a fan shape as shown in FIG. Then, while rotating the lance tube 1, the axis O
When the jet 8 reaches the intermediate portion between the adjacent heat transfer tubes 3, the jet 8
The whole hits the bridge 6a and penetrates the bridge 6a.
As a result, the bridge 6a can be removed as if the bridge 6a had been cut off with a knife. In addition, the jet 8 is generated by the nozzles 7a, 7
When the bridge 6a of the heat transfer tube 3 opposed to b is removed, as shown in FIG. 6, the bridge 6a of the rear heat transfer tube row 3a and the rear heat transfer tube row 3b are also removed.

FIG. 8 shows a conventional soot blower of nozzles 2a and 2b having the same internal pressure and supply volume of the high-pressure gas 4 supplied to the soot blower, and a long side L1 to which the present invention is applied. Nozzles 7a, 7 whose short sides are L2
It is the result of having compared the pressure loss at the time of removing the ash of each heat transfer pipe part by the soot blower of b. Note that L
1, L2 and D are in the relationship of ^{L1 · L2 = π · D 2} /4, is 2.1 ≦ L1 / L2 ≦ 4.0.

As shown in the figure, the ratio Δ of the pressure loss ΔP in the present invention to the pressure loss ΔP1 in the prior art is shown.
P / ΔP1 is 0.37, which indicates that the ash removal performance is excellent. As a result, in the present invention, the number of ash removal operations can be reduced, and the operating efficiency of the boiler can be improved.

FIG. 9 compares the volumes of the high-pressure gas 4 (here, steam was used) required to remove the ash to the same degree by setting the pressure of the high-pressure gas 4 supplied to the soot blower to be the same. The result.

As shown in the figure, the ratio QS / QS1 of the used steam amount QS in the present invention to the used steam amount QS1 in the prior art is 0.52, which indicates that the ash removal performance is excellent. As a result, in the present invention, the same ash removal operation as in the past can be performed with a small amount of steam, and the operation efficiency of the boiler can be improved.

From the above results, when the opening area of the nozzle and the supply amount of the high-pressure gas are made the same as in the conventional case, the supply pressure of the high-pressure gas can be reduced, and the leakage of the high-pressure gas can be prevented. The seal structure can be simplified. Further, when the ash removal rate and the supply pressure of the high-pressure gas are made the same as those in the related art, the opening area of the nozzle can be reduced, and the life of the nozzle can be extended.

FIG. 10 is a view showing the relationship between the soot blower and the heat transfer tube group according to the second embodiment. The nozzle arrangement direction when the moving direction of the lance tube 1 and the axial direction of the heat transfer tube 3 are parallel. Is shown. As shown in the figure, when the moving direction of the lance tube 1 and the axial direction of the heat transfer tube 3 are parallel,
The nozzles 7a and 7b are arranged such that the short sides are in the width direction of the heat transfer tube 3. In this way, with the movement of the lance tube 1 in the direction of the axis O, the jet 8 penetrates the bridge 6a formed between the heat transfer tubes 3 and the bridge 6a as if it were cut off with a knife. 6a can be removed.

In these embodiments, the ratio L1
/ L2 and the spread angle θ are respectively 2.1 ≦ L1
/L2≦4.0 and 5 ° ≦ θ ≦ 15 °, the jet 8 can be made into an ideal shape that is thin and fan-shaped, but the ratio L1 / L2 and the spread angle θ are
It was confirmed that good results could be obtained even when the range was expanded to 1.6 ≦ K ≦ 10.0 and 3 ° ≦ θ ≦ 20 °.

FIG. 11 is a front view of a soot blower showing a third embodiment according to the present invention, FIG. 12 is a side sectional view, and FIG.
Is a diagram for explaining the operation.

11 to 13, a plurality of nozzles 10 each having a circular opening are provided on the mount 11 (three nozzles in FIG. 11).
Is arranged. Then, L1 and L2 are referred to in FIG.
When the corresponding dimensions, the inner diameter d of the nozzle 10 is ^{3πd 2/4 = L1 · L2} , the spread angle beta is 3 ° ≦ β ≦ 16 °. The nozzles 10 are separated from each other by a predetermined distance and the angle of the jet direction is shifted so that the jets ejected from each other do not interfere with each other. The mount 11 is fixed to the lance tube 1 by bolts not shown. The spread angle β is set to 3 to 16 ° in order to reduce the spread of the jets 12 and minimize interference between the adjacent jets 12.

In the third embodiment, an opening substantially equal to the nozzle 7a (or the nozzle 7b) is approximately formed by three small-diameter nozzles 10. With this configuration, one flat jet can be formed approximately by the three jets 12, so that the ash removal ability can be given substantially the same as when the opening is made rectangular. When the small-diameter nozzles 10 are arranged, the pressure loss at the nozzle portion is slightly larger than when the nozzles are rectangular. However, when it is necessary to change the opening area of the nozzle, if the mount 11 provided with the nozzle having a different opening area is prepared in advance, the opening area of the nozzle can be changed in a short time.

The operation is substantially the same as in the case where the opening is rectangular, and a description thereof will be omitted.

[0034]

As described above, according to the present invention,
In a soot blower that blows gas from a nozzle disposed on the side of a lance tube to remove combustion ash attached to the heat transfer tube, the shape of the opening of the nozzle is substantially rectangular, so that the ash bridged between the heat transfer tube and the heat transfer tube. Not only can be efficiently removed, but also ash attached to the heat transfer tube on the rear side away from the nozzle can be removed. As a result, when the amount of the high-pressure gas used is the same as that in the related art, the number of times the soot blower is operated can be reduced, and not only the working efficiency can be improved, but also the thermal fatigue can be reduced and the life of the soot blower can be extended. Also, if the number of soot blower operations is the same as before, the amount of high pressure gas used can be reduced,
When compressed air is used as the high-pressure gas, the capacity of the blower can be reduced, and when steam from the boiler is used as the high-pressure gas, the operating efficiency of the boiler can be increased. Also,
Since the injection pressure of the high-pressure gas can be reduced, the structure of the seal portion can be simplified.

[Brief description of the drawings]

FIG. 1 is a front view showing a structure of a soot blower tip according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a cross-sectional view of a heat transfer section for explaining an operation of the soot blower according to the first embodiment of the present invention.

FIG. 5 is a perspective view showing a state in which high-pressure gas is ejected from the soot blower according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view of the heat transfer unit showing a state of ash removal in the soot blower according to the first embodiment of the present invention.

FIG. 7 is a perspective view showing an operation state of the soot blower according to the first embodiment of the present invention.

FIG. 8 is a result of comparing the pressure loss of the present invention with that of the prior art.

FIG. 9 is a result of comparing required amounts of high-pressure gas according to the present invention and the prior art.

FIG. 10 is a diagram illustrating a moving direction of a soot blower, a direction of a heat transfer tube, and an arrangement direction of a nozzle according to a second embodiment of the present invention.

FIG. 11 is a front view of a soot blower according to a third embodiment of the present invention.

FIG. 12 is a side sectional view of a soot blower according to a third embodiment of the present invention.

FIG. 13 is a diagram illustrating an operation of a soot blower according to a third embodiment of the present invention.

FIG. 14 is a diagram showing a structure of a conventional soot blower tip.

FIG. 15 is a perspective view showing an operation state of a conventional soot blower.

FIG. 16 is a cross-sectional view of the heat transfer section schematically showing a state in which ash attached to the heat transfer tube is deposited.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lance tube 3 Heat transfer tube 4 High pressure gas 7a, 7b Nozzle L1 Long side L2 Short side

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takeo Noya 6-9 Takara-cho, Kure-shi, Hiroshima Fab term in Bab Hitachi Kiko Co., Ltd. (reference) 3K061 QC02 QC03 QC23 QC38 4F033 AA04 BA02 CA05 DA01 EA01 LA03 NA01

Claims (6)

[Claims] 1. A soot blower for blowing gas from a nozzle disposed on a side surface of a lance tube to remove combustion ash attached to a heat transfer tube, wherein the opening of the nozzle has a substantially rectangular shape. 2. The soot blower according to claim 1, wherein a long side of the substantially rectangular opening is provided in a direction parallel to a longitudinal direction of the heat transfer tube to be removed. 3. When the lengths of two sides of the rectangular opening are L1 and L2, respectively, the relationship between the two is set to 1.6 ≦ L1 / L2 ≦ 10.0. The soot blower according to claim 1 or 2, wherein: 4. The soot blower according to claim 1, wherein a spreading angle θ of the two sides of the opening opposite to the outlet side with respect to the inlet side is set to 3 ° ≦ θ ≦ 20 °. . 5. A plurality of small-diameter nozzles having circular openings instead of the rectangular openings are arranged in a direction substantially perpendicular to the longitudinal direction of the lance tube, and the jet shape ejected from the nozzles is the rectangular opening. 2. The small-diameter nozzle is arranged so as to approximate a jet flowing out of the nozzle.
The described soot blower. 6. The soot blower according to claim 5, wherein a spreading angle β of the outlet side of the small diameter nozzle with respect to the inlet side is set to 3 ° ≦ β ≦ 16 °.