JP2000018555A - Soot blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soot blower which enables highly hindering of cavitation damage along with excellence in performance of removing adhered matters. SOLUTION: A double tube structure is built up with an outer tube 19 provided with a main jet nozzle 13 and an inner tube 20 provided with a flashing nozzle 14. High temperature/high pressure water 11 supplied to the inner tube 20 is turned granular generating a liquid drop jet flow 15 by the flashing nozzle 14 and a fast mixed two phase jet flow of the liquid drop jet flow 15 and an accelerated steam flow 16 supplied through the inside of the outer tube 19 is jetted out of the main jet nozzle 13 thereby removing ash adhered to a heat- transfer pipe.

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 deposits deposited on a heat transfer tube of a boiler or the like, and more particularly to a technique for improving the removal capability of deposits.

[0002]

2. Description of the Related Art In a power generation boiler or an industrial boiler, since particulate matter scattered in a combustion process adheres to a heat transfer portion, the heat transfer efficiency of the boiler decreases and the pressure loss in the furnace increases. However, there is a problem that the operation rate of the boiler is reduced. Further, depending on the composition of the deposits, a trouble of corroding the heat transfer tube may occur. As a means for removing such deposits on the heat transfer tube, a soot blower device as shown in FIG. 8 is generally installed near the heat transfer tube, and steam or compressed air is injected periodically to solve the above-mentioned problem. Had been resolved. That is, a nozzle 9 is provided in a long tubular body 8 constituting a soot blower main body, and a jet gas 1 composed of steam or compressed air is jetted from the nozzle 9 to blow off attached matter.

However, recently, liquid fuels such as vacuum residue oil and ultra-heavy oil have been diversified, and the quality has been further deteriorated. Coal containing a low-melting-temperature mineral (ash) is frequently used due to the use of multiple coal types. The problem of contamination of the heat transfer tubes is becoming insignificant due to the fact that the ash particles are easily melted on the heat transfer surface of the high-temperature section, and the adhesion of the deposits tends to increase. It is in. for that reason,
In the conventional soot blower device shown in FIG. 8, it is becoming difficult to remove the adhered matter firmly attached to the heat transfer surface.
Further, in order to increase the adhering matter removal rate, the injection pressure of the injection gas may be increased. However, when the nozzle diameter is the same, the consumption of the injection gas increases, and when steam is used as the injection gas, the boiler is used. It is uneconomical because it reduces efficiency. On the other hand, if the injection pressure is increased by reducing the nozzle diameter, the steam consumption does not increase, but in this case, there is a problem that the life of the nozzle itself is shortened.

Accordingly, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 58-316.
In Japanese Patent Laid-Open No. 5 (1993), a sootblower device as shown in FIG. As shown in the drawing, an outer nozzle 4 is provided on an outer tube 3 constituting a soot blower main body, and an inner tube 5 is supported by a ring 6 inside the outer tube 3. A T-shaped powder injection nozzle 7 is provided at the tip of the inner tube 5, and the powder injection nozzle 7 is opened at the center of the outer nozzle 4. And inner pipe 5
While allowing the injection gas 2 containing fine particles to pass through,
The jet gas 1 containing no fine particles is passed from the outer tube 3 through the outer nozzle 4. As a result, the injected gas 2 containing the fine particles is injected from the powder injection nozzle 7 and the injected gas 1 is injected from the outer nozzle 4, so that the fine particles are attached by the high injection force of the two injected gases 1 and 2. It can hit the surface violently and remove strong deposits.

[0005]

As described above, FIG.
The conventional soot blower device shown in FIG.
The jet gas 2 containing fine particles is passed through the outer nozzle 4 of the outer tube 3 and the fine particles and the jet gas 1 are jetted from the outer nozzle 4. Therefore, as in the prior art shown in FIG. Without increasing or increasing the number of actuations,
It is possible to remove the adhered matter firmly adhered to the adhered surface. However, when soft solid particles are used as fine particles, the efficiency of removing adhering substances cannot be increased, and since solid particles generally have a low melting point, solid particles that are melted and blown in a furnace are newly added. Ash may be produced. For this reason, in the prior art shown in FIG. 9, hard solid particles having a high melting point such as silica sand or ceramic are used. However, such hard solid particles squirt at a high speed and directly collide with the attached matter. However, there is a problem that the heat transfer tube, which is an object to be sprayed, is eroded, and furthermore, a special facility for transporting the solid particles to the powder injection nozzle 7 is required, and thus there is a problem that the cost is increased.

[0006]

According to the present invention, high-temperature and high-pressure water supplied to an inner pipe having a double pipe structure is atomized as a group of sprayed water droplets with a flushing nozzle, and the sprayed water droplets and a main jet gas (steam or compressed gas) are atomized. ) Is jetted from the main jet nozzle of the outer tube. With this configuration, the initial velocity of the spray water droplets generated by the flushing nozzle is not high, but it is jetted at high speed as a high-speed mixed two-phase jet with the main jet gas, so that the apparent density is large and the momentum is large . Therefore, even solid deposits that are difficult to remove can be efficiently removed, and the use of fine water droplets generated by flushing can suppress the progress of erosion on a jetting object such as a heat transfer tube. .

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the soot blower device of the present invention,
An outer pipe provided with a main ejection nozzle, an inner pipe arranged inside the outer pipe, and a flushing nozzle provided in the inner pipe, wherein the high-temperature high-pressure water supplied into the inner pipe is flushed The nozzle is atomized as a group of sprayed water droplets, and a mixture of the group of sprayed water droplets and the main jet gas supplied into the outer tube is jetted from the main jet nozzle.

Further, in the soot blower device of the present invention, a plurality of the main ejection nozzles are provided so as to be shifted in the axial direction of the outer tube, and the inner tube is bent so as to avoid these main ejection nozzles.

Further, in the soot blower device of the present invention, the outlet of the flushing nozzle is shifted toward the central axis of the outer tube with respect to the inlet of the main jet nozzle.

In the soot blower of the present invention, when the length of the ejection hole of the flushing nozzle is L and the diameter of the ejection hole is D, the slenderness ratio L / D is 4.0 ≦ L / D <.
The range was set to 20.

Further, in the soot blower device of the present invention, the temperature of the high-pressure high-temperature water is set to 115 ° C. or more, and the pressure is set to the saturated steam pressure of the water temperature or more.

[0012]

Embodiments will be described with reference to the drawings.
FIG. 1 is a sectional view of a main part of a soot blower device according to a first embodiment of the present invention, FIG. 2 is a view taken in the direction of arrows AA in FIG. 1, FIG. 3 is a sectional view of a flushing nozzle, and FIG. FIG. 5 is an explanatory view schematically showing a high-speed mixed two-phase jet ejected from a main ejection nozzle.

As shown in FIG. 1, two main jet nozzles 13 are provided at the end of an outer pipe 19 constituting a main body of a soot blower device.
These main ejection nozzles 13 are arranged on a line orthogonal to the central axis of the outer tube 19 so as to face each other. Steam 12 (or compressed gas), which is the main jet gas, is supplied through the inside of the outer pipe 19, and the steam 12
Is injected from the main jet nozzle 13 into the furnace. The main ejection nozzle 13 has a contraction portion 13α on the inlet side and an enlarged portion 13β on the exit side, has a structure having a throat portion 13 ′ as a whole (see FIG. 5), and has a vapor 12 as a main ejection gas. Are ejected as an accelerated steam flow 16 at the throat portion 13 '.

Inside the outer tube 19, an inner tube 20 for supplying the high-temperature and high-pressure water 11 is arranged, and the center axes of the outer tube 19 and the inner tube 20 coincide. This high-temperature high-pressure water 11
Conditions that do not cause boiling in the high-temperature and high-pressure water supply flow path 10 of the inner pipe 20, that is, the water temperature is set to a saturation temperature or less corresponding to the pressure. The tip of the inner pipe 20 is formed in a T-shape, and the high-temperature and high-pressure water supply flow path 10 which is a supply path of the high-temperature and high-pressure water 11 is branched in two directions at this portion to form a high-temperature and high-pressure water supply flow path branching section. The flushing nozzles 14 are provided at the respective ends to boil the high-temperature and high-pressure water 11 under reduced pressure to atomize the water. As shown in FIG. 2, the flushing nozzle 14 and the main ejection nozzle 13 are located on the same axis, and the tip (outlet) of the flushing nozzle 14 is closer to the outer tube 1 than the inlet of the main ejection nozzle 13.
9 is slightly retracted in the central axis direction. This is to prevent the tip of the flushing nozzle 14 from hitting the inlet of the main jet nozzle 13 and being damaged when the inner tube 20 thermally contracts (at the start of operation, at the start of high-temperature water supply, etc.).
By doing so, the droplet jet 15 composed of fine water droplets generated at the flushing nozzle 14 is jetted into the furnace at a high speed by the accelerated steam flow 16 which is the main jet gas.

The inner tube 20 is positioned so as to be coaxial with the outer tube 19 by the spacer 17 on the way and the inner tube stopper 18 at the tip. The inner stopper 18 is fixed at two points inside the tip of the outer tube 19 so as to be shifted from the center axis.
The flushing nozzle 14 is positioned by the internal stopper 18 and the spacer 17 without rotating with respect to the main ejection nozzle 13. In order to absorb the movement of the inner tube 20 due to the thermal contraction, the spacer 17 and the stopper 20 are provided with a slight clearance (clearance). The flushing nozzle 14 is moved by the heat shrinkage of the inner tube 20.
Flushing nozzle ejection hole 14 ′ and main ejection nozzle 13
Although there is a possibility that the center of the droplet jet is slightly displaced, the droplet jet 1 immediately after jetting from the flushing nozzle jet hole 14 ′
5 is fine and the surrounding area is the accelerated steam flow 1 which is the main jet gas.
6 flows, the droplet jet 15 does not collide with the throat 13 ′ of the main jet nozzle 13.

Here, as shown in FIG. 3, when the length of the flushing nozzle ejection hole 14 'is L and the diameter of the flushing nozzle ejection hole 14' is D, the slenderness ratio L / L to the hole diameter D is expressed as D is set in the range of 4.0 ≦ L / D <20 (1). Flushing nozzle outlet 1
If the slenderness ratio L / D of 4 ′ is set in a range that satisfies the above equation (1), the pressure loss is reduced and the atomization is performed well, and as a result, the above equation (1) is Can be said to be the optimum conditions for boiling under reduced pressure (flashing). On the other hand, when the length L of the flushing nozzle ejection hole 14 ′ is too short, that is, when 0 ≦ L / D <4.0,
Since the superheated water boils after being ejected, atomization becomes insufficient, and coarse droplets may be generated. On the contrary,
When the length L of the flushing nozzle ejection hole 14 'is too long, that is, when L / D ≧ 20, boiling is activated in the flushing nozzle ejection hole 14', so that a so-called vapor lock phenomenon in which bubbles are filled in the narrow tube. Occurs. When the vapor lock occurs, the pressure loss increases, so that there is also a problem that the water flow rate becomes lower than a predetermined water injection amount.

As is apparent from the relationship between pressure and temperature shown in FIG. 4, water is in a liquid phase under high pressure even at high temperatures. As described above, since the high-temperature and high-pressure water 11 pressurized at a high temperature is used as the water in the inner pipe 20, the sub-cooling state is established with respect to the internal pressure of the inner pipe 20, and the high-temperature and high-pressure water supply flow path 10 Then do not boil. Then, when the high-temperature and high-pressure water 11 is jetted from the flushing nozzle 14, the water temperature does not immediately decrease but the pressure drops sharply, so that the water becomes a superheat state and boils explosively, resulting in a liquid composed of fine water droplets. It is ejected as a drop jet 15. Since the droplet jet 15 is generated in the throat 13 ′ of the main jet nozzle 13, it is rapidly accelerated by the steam 12 jetted from the main jet nozzle 13 and jetted from the main jet nozzle 13 into the furnace of the boiler to collide with the attached ash. I do.

Since the inside of the furnace of the boiler is almost at atmospheric pressure,
When the water temperature exceeds 100 ° C., the high-temperature and high-pressure water 11 becomes overheated. However, when the water temperature of the high-temperature and high-pressure water 11 exceeds 100 ° C., boiling occurs, but 115 ° C. (superheat = 1
At a water temperature of 15 ° C.−100 ° C. = 15 ° C. or less, the power of boiling is poor, atomization is poor, and water droplets are coarse, so that it is not suitable for practical use as a soot blower. Desirably, the water temperature of the high-temperature high-pressure water 11 is raised to 160 ° C. or more (superheat degree is 60 ° C. or more), and the feed pressure in the inner pipe 20 is reduced to about 10 ° C.
When the pressure is set to １５15 kgf / cm ² (1.0 to 1.5 MPa), extremely intense boiling atomization occurs, and fine water droplets can be generated. As an example, when the high-temperature high-pressure water 11 pressurized to 10 kgf / cm ² (1 MPa) at a water temperature of 160 ° C. is used, the high-temperature high-pressure water supply flow path 1 of the inner pipe 20 is used.
At 0, it does not boil, and a superheating potential of 60 ° C. is obtained at the time of injection by the flushing nozzle 14.
A droplet jet 15 consisting of a group of fine water droplets of about 50 μm can be obtained. This kind of fine water droplets is
6, the water droplet jet 15 is supersaturated as a whole and collides with the object (ash on the heat transfer surface), and the water droplet does not evaporate on the way. Further, since the water droplet jet 15 has small water droplets, even if it collides directly with the heat transfer tube as an object, a large thermal stress does not act on the heat transfer tube, and it is possible to suppress the progress of erosion in the heat transfer tube.

According to the soot blower device according to the first embodiment, as shown in FIG. 5, the high-temperature and high-pressure water 11 fed to the inner pipe 20 is guided through the high-temperature and high-pressure water supply passage 10 '.
The pressure is rapidly reduced by the depressurization accelerating part 21 which is a squeezing part, and the superheated state is reached, and the boiling starts in the flushing nozzle 14 (see FIG. 3A). Although the flushing nozzle orifice 14 'is a pore, the inside of the flushing nozzle orifice 14' is filled with boiling bubbles that have grown rapidly, so that a large number of boiling bubbles burst in the flushing nozzle orifice 14 'and atomize the surrounding water. (See FIG. 2B). In this way, a water jet 15 is created. On the other hand, the main ejection nozzle 13 has a throat portion 13 '.
In this throat portion 13 ', the outer tube 1
9 which is the main jet gas supplied through the interior of
Is accelerated to the maximum, and becomes an accelerated steam flow 16 as shown by a white arrow in FIG. Since the outlet of the flushing nozzle 14 is set so as to be located at the throat portion 13 ′ of the main jet nozzle 13, the water droplet jet 15 generated by the flushing nozzle 14 is accelerated by the accelerated steam flow 16 which is the main jet gas.
Accordingly, the fuel is rapidly accelerated and ejected from the main ejection nozzle 13 as a high-speed mixed two-phase jet with the accelerated steam flow 16. At that time, since the high-speed mixed two-phase jet passes through the throat portion 13 'of the main ejection nozzle 13, the critical flow velocity (= sonic speed) of the accelerated steam flow 16 in the throat portion 13' is a gas single-phase flow through which only steam passes. And naturally, the speed of collision with the object also decreases. However, the high-speed mixing two-phase jet contains a large amount of fine water droplets and has an increased apparent density (weight ratio of the entire jet to the volume of the entire jet). If the condition is assumed to occupy about 10%, the apparent density is increased about 20 times, so that the momentum can be sufficiently increased, and the hardly removable ash adhering to the heat transfer tube, which is the object, can be removed. It can be easily removed.

FIG. 6A shows a test result in which the number of times of operation of the soot blower is compared between the present embodiment and the prior art shown in FIG. 8. The number of times N of operation of the soot blower is N ^{* the} number of times of operation of the soot blower in the prior art ^. It is expressed as a relative value by dividing by. As can be seen from the figure, according to the present embodiment, the number of operations can be significantly reduced to 20% or less as compared with the prior art. This example is a test result in the case of burning ultra-heavy oil to which ash, which is considerably difficult to remove, adheres, but a similar effect of reducing the number of operations can be obtained in the case of burning coal.

FIG. 6B shows a test result in which the injection flow rate of water (steam) is compared between the present embodiment and the prior art shown in FIG. 8, and the injection flow rate Qw (in this embodiment, the main injection gas is used). The sum of steam and water) is expressed as dimensionless by dividing by the injection flow rate Q ^* in the prior art. As can be seen from the figure, in this embodiment, the total amount of use is smaller than that of the prior art despite the use of high-temperature and high-pressure water for flushing in one injection. This is because, as shown in FIG. 6A, the number of times of operating the soot blower is significantly reduced.

As is clear from the above test results, by applying the soot blower device according to the present embodiment, not only the number of operations can be reduced, but also the amount of water used (which may include compressed air) can be reduced. The effect was also confirmed.

FIG. 7 is a sectional view of a main part of a soot blower device according to a second embodiment of the present invention, and portions corresponding to FIG. 1 are denoted by the same reference numerals.

The difference between the soot blower device according to the present embodiment and the first embodiment described above is that the two main ejection nozzles 13
a is shifted in the axial direction of the outer pipe 19, and the inner pipe 20 is bent to a shape avoiding the main ejection nozzle 13a, and the other configuration is basically the same. That is, the inner pipe 20 is bent so as to avoid each of the main ejection nozzles 13a, and the flushing nozzles 14 are provided at the tip of the inner pipe 20 and at two places in the middle thereof. It is installed facing the inlet of the jet nozzle 13a. The inlet of the main jet nozzle 13a protrudes into the outer pipe 19, and its throat 1
The length of 3a 'is set to be approximately equal to the inner diameter of the outer tube 19.

When assembling the soot blower device thus constructed, the inner tube 20 is inserted into the outer tube 19 with the main jet nozzle 13a removed, and the inner tube 20 is connected to the annular spacer 17 and the projection. After positioning inside the outer tube 19 by the body-shaped spacer 17 ′, the main ejection nozzle 13 a may be attached to the outer tube 19.

According to the present embodiment, in addition to the effect of the first embodiment, there is an effect that the diameter of the outer tube 19 can be reduced to make the soot blower device compact. Further, since the throat portion 13a 'of the main ejection nozzle 13a can be lengthened, the droplet jet 15 can be sufficiently accelerated, and the power of the droplet jet 15 penetrating can be increased. Further, since the re-atomization of the droplet by the accelerated steam flow 16 as the main jet gas is promoted, the erosion of the heat transfer tube can be almost prevented from progressing.

[0027]

The present invention is embodied in the form described above and has the following effects.

The high-temperature and high-pressure water supplied to the inner tube is atomized as a group of sprayed water droplets by a flushing nozzle, and a high-speed mixed two-phase jet of the group of sprayed water droplets and the main jet gas supplied to the outer tube is discharged from the main jet nozzle of the outer tube. When jetted, the initial velocity of the spray droplets generated by the flushing nozzle is not large, but it is jetted at high speed as a high-speed mixed two-phase jet with the main jet gas,
Since the apparent density is large and the momentum is large, even solid deposits that are difficult to remove can be efficiently removed.In addition, since fine water droplets generated by flushing are used, objects to be sprayed such as heat transfer tubes It is possible to suppress the progress of erosion in the object.

Further, a plurality of the main ejection nozzles are provided so as to be shifted in the axial direction of the outer tube, and the inner tube is bent to a shape avoiding these main ejection nozzles. In addition, it is possible to increase the throat portion of the main ejection nozzle to increase the penetration force of the droplet jet.

When the outlet of the flushing nozzle is shifted toward the central axis of the outer pipe with respect to the inlet of the main jet nozzle, the inner pipe thermally contracts at the start of operation or at the start of high-temperature water supply. In addition, it is possible to prevent the tip of the flushing nozzle from hitting the entrance of the main ejection nozzle and being damaged.

When the length of the ejection hole of the flushing nozzle is L and the diameter of the ejection hole is D, the slenderness ratio L / L
When D is set to be in the range of 4.0 ≦ L / D <20, the pressure loss is reduced, and a child having good atomization can be obtained.

The high-pressure and high-temperature water may be set to a condition that does not cause boiling in the inner tube. If the temperature of the high-temperature and high-pressure water is set to 115 ° C. or more, preferably 160 ° C. or more, Remarkably intense boiling atomization occurs, and fine water droplets can be generated.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a soot blower device according to a first embodiment of the present invention.

FIG. 2 is a view in the direction of arrows AA in FIG. 1;

FIG. 3 is a sectional view of a flushing nozzle.

FIG. 4 is an explanatory diagram showing an operation principle of flushing.

FIG. 5 is an explanatory view schematically showing a high-speed mixed two-phase jet ejected from a main ejection nozzle.

FIG. 6 is an explanatory diagram showing a test result of the number of times of operation of a soot blower and an injection flow rate.

FIG. 7 is a sectional view of a main part of a soot blower device according to a second embodiment of the present invention.

FIG. 8 is a sectional view of a main part of a soot blower device according to a conventional example.

FIG. 9 is a sectional view of a main part of a soot blower device according to another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 High-temperature and high-pressure water supply channel 10 'High-temperature and high-pressure water supply channel branch part 11 High-temperature and high-pressure water 12 Steam (main jet gas) 13, 13a Main jet nozzle 13', 13a 'Throat portion 14 Flushing nozzle 14' Flushing nozzle jet hole 15 Droplet jet 16 Accelerated vapor flow 17, 17 'Spacer 18 Internal stopper 19 Outer tube 20 Inner tube 21 Decompression accelerating unit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takeo Noya 6-9 Takara-cho, Kure-shi, Hiroshima F-term in Babcock-Hitachi Kure Factory (reference) 3K061 QC22 QC23 QC34 QC38 4F033 QA09 QB03X QB15X QB15Y QC04 QD02 QD15 QD23 QE14 QE23 QE30 QK18X QK22X

Claims (5)

[Claims] 1. An inner pipe provided with a main ejection nozzle, an inner pipe disposed inside the outer pipe, and a flushing nozzle provided in the inner pipe, wherein a high temperature supplied to the inner pipe is provided. A soot blower device wherein high-pressure water is atomized as spray water droplets by the flushing nozzle, and a mixture of the spray water droplets and the main jet gas supplied into the outer tube is jetted from the main jet nozzle. 2. The method according to claim 1, wherein a plurality of the main ejection nozzles are provided so as to be shifted in an axial direction of the outer tube, and the inner tube is bent to a shape avoiding the main ejection nozzles. Soot blower device. 3. The soot blower device according to claim 1, wherein an outlet of the flushing nozzle is shifted to a center axis side of the outer pipe with respect to an inlet of the main ejection nozzle. 4. The slenderness ratio L / D is set to 4.0 ≦ L, wherein the length of the ejection hole of the flushing nozzle is L, and the diameter of the ejection hole is D. A soot blower device wherein L / D is set in a range of <20. 5. The soot blower device according to claim 1, wherein the temperature of the high-pressure high-temperature water is at least 115 ° C., and the pressure is at least the saturated steam pressure of the water temperature.