JP2000257843A - Soot blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noble soot blower capable of simultaneously achieving an improvement of ash removal performance and an improvement of durability. SOLUTION: A soot blower is adapted such that ash deposited on a combustion furnace or a heat recovery apparatus is removed by supplying high pressure gas into a lance 1 of a long cylinder, blowing off gas from a nozzle 2 provided in the vicinity of the tip end of the lance, and bringing a blown jet 4 into collision. In the soot blower, an annular recessed portion 2Ac is provided on an outer periphery of a jet outlet of the nozzle 2 for blowing gas out, and the jet outlet and the outer shell configuration of the annular recessed portion are brought into coincident with the outer surface configuration of the lance. Further, the cross section of the annular recessed portion of the nozzle is formed into a substantially circular arc shape, and the annular recessed portion is changed in its depth of the recessed portion such that it is equal at an opposite position of substantially 180 degree but is different at an adjacent position of about 90 degree, and the jet stream is prevented from having a turning composition.

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 removing ash adhering to a heat transfer portion of a boiler or the like or a furnace wall by blowing off the ash with a jet, and more particularly to a structure of a nozzle portion of the soot blower.

[0002]

2. Description of the Related Art In a facility having a combustion furnace such as a commercial boiler or an industrial boiler, if a large amount of small particulate matter melted in a combustion process adheres to a heat transfer portion or a furnace wall, the heat transfer efficiency of the boiler is reduced. I do. Furthermore, the pressure loss inside the furnace increases,
The operation of the boiler will be hindered. This is because the rise in pressure loss in the furnace causes ash to form a bridge (bridge) in the gap between the tubes, which hinders the flow through the heat transfer tube group. Further, depending on the composition of the molten ash deposits, it may lead to a problem of corroding the heat transfer tube.

[0003] Therefore, as means for removing the deposits on the heat transfer tube, a soot blower provided with a nozzle, which is a member for injecting an air flow into a long tube (called a lance tube), is generally installed near the heat transfer tube. Steam or compressed air is periodically injected to blow off the deposits.

[0004] Recently, however, liquid fuels such as vacuum residual oil and ultra-heavy oil have become more diversified and are being degraded. Also, in the case of coal firing, a coal type operation is performed, and coal containing a lot of minerals (ash) having a low melting temperature is frequently used, so that the problem of contamination of the heat transfer tube cannot be ignored. Especially on the heat transfer surface of the high temperature part,
The ash particles are melted, and the adhesion of the deposits is strong. Therefore, it has become difficult to remove ash strongly adhered to the heat transfer surface in the conventional soot blower.

In order to improve the removal rate of deposits, it is necessary to increase the injection pressure of the injection gas. However, when the nozzle outlet diameter is the same, the consumption of the injection gas increases. In some cases, the efficiency of the boiler is reduced, which is uneconomical. On the other hand, if the injection pressure is increased by reducing the nozzle diameter, the steam consumption does not increase, but there is a problem that the life of the soot blower nozzle itself is shortened due to the repetitive action of thermal stress. Structure) must be multiplexed and complicated.

[0006]

FIG. 10 illustrates a nozzle portion of a soot blower according to the prior art. The problem with this structure is that the jet diffuses quickly, in other words, the penetration force in the axial direction or the power at the time of collision rapidly declines. Therefore, the power of the jet does not reach the deep part of the tube bank, and as a result, the ash removing effect is insufficient.

On the other hand, (1) and (2) of FIG. 11 are axial sectional views or views from the outside of the furnace, respectively, and illustrate a nozzle portion of a soot blower according to the prior art. It has a structure that solves the problem of the nozzle shown in FIG. Since the turbulence of the jet is suppressed, the penetration force in the axial direction is large, and the power of the jet reaches the deep part of the tube bank.
On the other hand, this technique has a problem regarding durability. Since the tip portion of the nozzle, that is, the annular extending portion 2d is cylindrical and protrudes from the lance main body, it cannot be pulled out to a deep position of the wall box (storage space provided on the furnace wall).
Accordingly, there is a problem that the furnace is exposed to heat from the inside of the furnace, and a crack may be generated by a thermal shock, so that the life is short and the cost for preventive maintenance is high.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a novel soot blower capable of simultaneously improving ash removal performance and durability.

[0009]

In order to solve the above problems, the present invention mainly employs the following configuration.

[0010] A high-pressure gas is supplied to the inside of a lance, which is a long cylindrical body, and the gas is blown from a nozzle provided near the tip of the lance, and the blown jet collide with the gas to adhere to a combustion furnace or a heat recovery device. In the soot blower for removing the ash, an annular recess is provided on the outer periphery of the outlet of the nozzle that blows out the gas, and the outer shell shape of the outlet and the annular recess matches the outer surface shape of the lance. Soot blower to do.

Further, in the soot blower, a cross section of the annular concave portion of the nozzle has a substantially circular arc shape.

In the soot blower, the depth of the concave portion is changed so that the annular concave portion is equal at an approximately 180-degree facing position and different at an approximately 90-degree adjacent position to generate a swirl component in the jet flow. Soot blower to not.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A soot blower according to an embodiment of the present invention will be described below with reference to the drawings. Where 1
Is a lance, 2 is a nozzle, 2Ac is an annular concave portion, 2Acs is an annular shallow concave portion, 2Acd is an annular deep concave portion, 2a is a steam inflow portion, 2b is an ejection portion, 2d is a cylindrical extension portion, 3 is steam,
Represents a jet flow, 6s represents an inflow of air from a shallow recess, 6d represents an inflow of air from a deep recess, α represents a rotation / forward (and retreat) motion, and δ represents a depth length of the ash removing unit.

FIG. 1 is a sectional view showing a structure of a soot blower tip according to an embodiment of the present invention. Two nozzles 2 are provided in a lance 1 which is an elongated cylindrical body whose tip is sealed. 1 for circumferential direction of lance 1
The lance 1 is disposed at a position 80 degrees away from the lance 1 and is shifted forward and backward with respect to the axial direction of the lance 1.

The medium for removing ash is steam 3 and lance 1
And a high-speed jet 4 from both nozzles 2
Blow out as When operating, the lance 1 moves forward or backward while rotating, and blows a steam jet on a heat transfer tube in the boiler. When not operating, the lance 1 is pulled out into the furnace, and the nozzle portion at the tip is housed in a wall box provided on the furnace wall of the boiler.

FIG. 2A shows the nozzle structure, which is a feature of the present embodiment, as a radial cross-sectional view of the lance 1. FIG. 2B shows the structure of the nozzle as an axial cross-sectional view of the lance 1.
In the nozzle 2A according to the present embodiment, first, an annular concave portion 2Ac is provided around the ejection portion 2b. The cross-sectional shape of the annular recess is substantially arc-shaped.

Prior art (1) and (2) of FIG.
In the above, the cylindrical extension 2d (indicated by a broken line in this figure) is provided on the outer periphery of the annular concave portion 2A. However, in the present invention, the cylindrical extension is formed by the shape of the outer surface of the lance 1, that is, the cylindrical body. The shape is "cut" to match the side shape. Therefore, apparently, the depth of the annular recess 2A is smaller than that of the prior art. In this way, the lance 1
In this case, since the protrusion of the nozzle portion is eliminated, the storage in the wall box becomes easy.

FIG. 3 illustrates the lance with the nozzle portion viewed from the furnace side. The annular concave portion 2Ac becomes relatively deep in the axial direction of the lance 1 (denoted by an arrow in the drawing), and also in the circumferential direction of the lance 1 (denoted by an arrow in the drawing).
Is relatively shallow. As described above, in the annular concave portion 2Ac, a shallow concave portion and a deep concave portion are alternately arranged at a pitch of 90 ° with respect to the circumferential direction of the nozzle 2A.

FIG. 5 shows a nozzle portion as a radial (lateral) cross section of the lance 1 and schematically shows a flow form in the nozzle portion. Since the annular recess becomes shallower as it goes in the circumferential direction of the lance 1, the annular shallow recess 2Acs is used here.
It was written. Bubble inflow 6s from the shallow concave portion flowing into the jet 4 through the annular shallow concave portion has a small bend because the concave portion is shallow. Therefore, near the outlet of the nozzle 2A, the flow into the jet 4 through the interface becomes relatively steep. That is, as a comparison target, “jet 4” as shown in FIG.
It flows differently from the “flowing in parallel with” state.

FIG. 6 schematically illustrates a flow form in the nozzle portion as an axial (longitudinal) cross section of the lance 1. Since the annular recess is relatively deep in the axial direction of the lance 1 (compared with FIG. 5), here the annular deep recess 2
It is described as Acc. The flow passing through the annular deep recess 2Acd, that is, the airflow inflow 6d from the deep recess has a large bend, has an apparent U-turn shape, and flows near the outlet of the nozzle 2A almost in parallel with the jet flow 4. This flow is significantly different from the embodiment shown in FIG.

FIG. 7 illustrates the phenomena shown in FIGS. 5 and 6 when the nozzle outlet is viewed from the furnace side. Bubble inflow from deep recess 6d in the circumferential direction of nozzle 2A
And 6 s of air bubbles flowing from the shallow concave portion are alternately arranged at a pitch of 90 °. When such a flow is realized at the ejection port of the nozzle 2A, the axial inertial force of the jet 4 is strongly maintained to the downstream, and the ash removing effect is enhanced.

In the horizontal pipe group 5 of a heavy oil-fired boiler to which a large amount of ash which is relatively difficult to remove tends to adhere, evaluation is made based on the depth length δ of the ash removing portion as shown in FIG. It is determined that the greater the depth length δ, the higher the ash removal effect.

FIG. 9 shows ash removal of each soot blower in comparison with the prior art (FIG. 10), the prior art ((1) and (2) of FIG. 11) and the embodiment of the present invention (FIGS. 1 to 3). It is a comparison of performance. Depth length δ of ash removal part on vertical axis
Is the depth length δ ^* of the ash removing part in the prior art (FIG. 10).
Divided by to make it infinite. The result of the prior art (FIG. 10) is δ / δ ^* = 1.

On the other hand, in the prior art in which the cylindrical extension is provided at the nozzle outlet, δ / δ ^* = 4.20, which indicates that the ash removing effect is greatly improved. In the case of the present invention, δ / δ ^* = 4.17, which indicates that there is no grandchild color as compared with the prior art showing high performance. Compared with the prior art and the embodiment of the present invention, if the ash removal performance is the same, the cylindrical extension part is eliminated, and the structure is protected from thermal shock while retaining the structure and function of the minimum annular concave portion. It can be said that the embodiment of the present invention in which is increased is more advantageous.

In the embodiment shown in FIG. 2, since the inlet portion of the nozzle protrudes into the medium (steam) flowing portion in the lance and is further stepped, stagnation and vortex are easily generated at the inlet portion. This vortex is strongly involved in the turbulence and diffusion of the jet ejected from the nozzle.

FIG. 4 shows another embodiment of the present invention. The step at the nozzle inlet is eliminated, so that the medium for the soot blower flows smoothly into the nozzle. In this embodiment, the pressure loss at the nozzle is reduced by 3% compared to the embodiment of FIGS.

As described above, the present invention includes those having the following configuration examples and functions or functions.

An annular recess is provided on the outer periphery of the outlet of the nozzle for jetting the jet, and the outside of the recess is extended so as to protrude in the jet ejection direction. In the case of a simple extension, this extension has a shape protruding cylindrically with respect to the axis of the lance, but this cylindrical opening is cut into the shape of a lance which is also cylindrical. I do. Thus, the annular recess is relatively deep at the axial end of the lance. On the other hand, the annular recess at the circumferential end of the lance becomes relatively shallow.

By doing so, firstly, the swirling of the jet is suppressed by the action of the annular recess, and the inertial force of the jet in the axial direction is increased. Also, by improving the shape,
Since the protrusion of the cylindrical extension of the nozzle is eliminated, the tip of the lance can be drawn into the back of the wall box.

In addition, the depth of the annular recess around the outlet of the nozzle differs in the circumferential direction of the nozzle, and the depth of the recess is two patterns, which are equal at the facing position (180 ° pitch). Matching position (90 °
(Pitch), a jet swirling component is not generated when blowing out from the nozzle, and the diffusion of the jet is suppressed even when the jet reaches downstream in the axial direction. In this way, since the passing force is maintained to the downstream, the jet force acts strongly to the deep portion of the heat transfer tube row, and ash can be removed.

Further, since the opening end of the cylindrical extension around the nozzle ejection hole has substantially the same shape as the surface of the lance,
Since the tube of the lance can be easily stored in the back of the wall box provided on the furnace wall, thermal shock is reduced, and the structural integrity of the soot blower can be maintained for a long time.

[0032]

When a soot blower embodying the present invention is applied to a boiler, the effects produced are as follows.

(1) The efficiency of ash removal is improved.

(2) In connection with the effect of the above (1), the amount of steam used for the soot blower can be reduced, which can contribute to maintaining the efficiency of the boiler.

(3) In connection with the effect of the above (1), the number of times of operating the soot blower can be reduced, so that the thermal fatigue of the soot blower can be reduced.

(4) The nozzle portion of the soot blower can be drawn deeper into the wall box provided on the furnace wall of the boiler. This can reduce the thermal shock. Therefore, the structural integrity of the nozzle portion of the soot blower can be maintained for a long time.

(5) In connection with the effect of (1), the number of soot blowers can be reduced. In short, the operation of the boiler plant is simplified.

(6) In connection with the effect of the above (1), as a medium for soot blower, even low-pressure steam can sufficiently be used, which can contribute to maintaining the efficiency of the boiler.

[Brief description of the drawings]

FIG. 1 is a sectional view of a soot blower on which a nozzle according to an embodiment of the present invention is mounted.

FIG. 2 is a sectional view of a nozzle portion of the soot blower.

FIG. 3 is a diagram showing a structure of a nozzle portion of the present soot blower.

FIG. 4 is a sectional view of a soot blower on which a nozzle according to another embodiment of the present invention is mounted.

FIG. 5 is a diagram for explaining a flow phenomenon of a jet and an air flow in a nozzle portion of the soot blower according to the embodiment of the present invention.

FIG. 6 is a diagram for explaining a flow phenomenon of a jet and an airflow in a nozzle portion of a soot blower according to the embodiment of the present invention.

FIG. 7 is a diagram for explaining a jet and airflow phenomena in a nozzle portion of the soot blower according to the embodiment of the present invention.

FIG. 8 is a diagram illustrating an effect obtained by implementing the present invention.

FIG. 9 is a diagram illustrating an effect obtained by implementing the present invention.

FIG. 10 is a structural diagram of a soot blower according to the related art.

FIG. 11 is a structural view of a soot blower according to the prior art.

[Explanation of symbols]

 1 Lance 2 Nozzle 2Ac Annular recess 2Acs Annular shallow recess 2Acd Annular deep recess 2a Steam inlet 2b Spout 2d Cylindrical extension 3 Steam 4 Jet 6s Air flow in from shallow recess 6d Air flow in from deep recess α (And retreat) Exercise δ Depth length of ash removing part

Continued on the front page (72) Inventor Takeo Noya 6-9 Takara-cho, Kure-shi, Hiroshima Bab Hitachi Kiko Co., Ltd. F-term (reference) 3K061 QC02 QC03 QC05 QC36 QC38

Claims (4)

[Claims] 1. A combustion furnace or a heat recovery device by supplying a high-pressure gas into a lance which is a long cylindrical body, blowing the gas from a nozzle provided near a tip of the lance, and colliding the blown jet. In a soot blower that removes ash attached to a nozzle, an annular recess is provided on an outer periphery of an outlet of a nozzle that blows out the gas, and an outer shell shape of the outlet and the annular recess matches an outer surface shape of the lance. A soot blower characterized by comprising: 2. The soot blower according to claim 1, wherein a cross section of the annular concave portion of the nozzle has a substantially arc shape. 3. The soot blower according to claim 1, wherein the depth of the concave portion is changed so that the annular concave portions are equal at substantially 180 ° opposed positions and different at approximately 90 ° adjacent positions. A soot blower characterized in that no swirl component is generated in the soot blower. 4. The soot blower according to claim 1, 2 or 3, wherein at a position near a tip of the lance, the soot blower is separated by 180 ° with respect to a circumferential direction of the lance and is positioned with respect to a longitudinal direction of the lance. A soot blower, wherein the nozzle is displaced.