JP2007183069A - Soot blower device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soot blower device that prevents erosive wear of heat transfer tubes and keeps heat transfer efficiency intact by effectively removing a wide range of heat transfer tube deposit ash even when sticky coal is burned. <P>SOLUTION: The soot blower device of a rotary moving type for removing ash and other deposits on heat transfer tubes in a boiler furnace has large and small diameter spray nozzles of different bores at a tip part of the soot blower device 1 such that the large diameter spray nozzle sprays a spray medium into a clearance (B) between adjacent heat transfer tubes 8 and the small diameter spray nozzle sprays a spray medium over tube surfaces (A) of heat transfer tubes 8. The supply and pressure of the spray medium may be regulated arbitrarily. The rotating speed and moving speed of the soot blower device having the spray nozzles may be regulated arbitrarily. The large and small diameter spray nozzles are positioned substantially at 180° intervals in the same axial position of the soot blower device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a soot blower device installed for the purpose of removing ash, dust, or the like attached to a heat transfer tube of a boiler furnace.

  In a coal-fired boiler, ash generated by the combustion of coal adheres to the boiler furnace water wall, heat transfer tubes, and the like, so that heat transfer is inhibited and the amount of heat exchange gradually decreases. For this reason, it is necessary to periodically remove the attached ash, and as shown in FIG. 6, a soot blower device capable of injecting high-pressure steam or air has been developed. Here, FIG. 6 is a system diagram showing the overall configuration of the soot blower apparatus related to the prior art. According to FIG. 6, the pressure control valve 3 is controlled by the pressure detector 2 and the control device 4, and the pressure of the high-pressure steam a is controlled and the steam is sprayed toward the heat transfer tube in the furnace.

  As shown in FIG. 2, the soot blower device 1 is installed at various places in the boiler, and is repeatedly started and stopped at regular intervals. The main specifications (spray pressure, nozzle hole diameter) of the soot blower device are determined by the properties of the coal. When coal with strong adhesion is burned in a boiler furnace, it is necessary to increase the spray pressure and the nozzle diameter.

  However, when the spray pressure or the nozzle hole diameter is increased, there arises a problem that the amount of erosion of the heat transfer tube close to the spray nozzle of the soot blower device increases.

As a conventional technique for solving this problem, for example, as shown in Patent Document 1, it has been proposed to spray a material having high wear resistance on a heat transfer tube. According to this, it is disclosed that a thermal spray coating of a special alloy is formed on the surface of the wear-resistant heat transfer steel pipe, and a bending process is performed simultaneously with a melting process by high-frequency heating. As a conventional technique, a method of installing a protector on the surface of a heat transfer tube as shown in FIG. 7 has been proposed (see, for example, Patent Document 2 and Patent Document 3). According to this, the protector 9 is installed in the surface of the heat exchanger tube 8 with respect to the spray injected from the soot blower apparatus 1. Here, FIG. 7 is a soot blower device related to the prior art and presents a technique for reducing the amount of erosion in the heat transfer tube close to the spray nozzle.
JP-A-10-170194 JP-A-11-118101 JP 2000-257804 A

  However, in the prior art as shown in Patent Documents 1, 2, and 3, in a boiler using coal with strong ash adhesion, in order to prevent erosion due to the soot blower device, a protector is installed on the heat transfer tube or sprayed. Measures such as construction are required, and there is a problem that the running cost is increased due to regular maintenance as well as the initial cost.

  The present invention is to solve such problems of the prior art. The purpose of the present invention is to prevent wear of heat transfer tubes due to erosion even in the case of coal with strong adhesion, and to transmit a wide range of heat. An object of the present invention is to provide a soot blower device that effectively removes heat pipe ash and does not reduce heat transfer efficiency.

In order to solve the above problems, the present invention mainly adopts the following configuration.
In a rotary moving soot blower device that removes ash etc. adhering to the heat transfer tube of a boiler furnace,
A large and small diameter spray nozzle is provided at the tip of the soot blower device.
A structure in which a spray medium from the large-diameter spray nozzle is sprayed in a gap between adjacent heat transfer tubes, and a spray medium from the small-diameter spray nozzle is sprayed on a tube surface of the heat transfer tube. And

  In the soot blower device, the supply amount and pressure of the spray medium can be arbitrarily adjusted, and the rotation speed and the moving speed of the soot blower device provided with the spray nozzle can be arbitrarily adjusted.

  In the soot blower device, the large-diameter and small-diameter spray nozzles are provided at the same position in the axial length of the soot blower device and at intervals of approximately 180 °.

  According to the present invention, even if the adhesion of ash differs depending on the coal type, heat transfer performance can be recovered by effectively removing ash without relying on cost-increasing methods such as installing a protector on the heat transfer tube or spraying. And erosion of the heat transfer tube close to the soot blower device can be prevented.

  A soot blower device according to an embodiment of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a system diagram showing the overall configuration of a soot blower device according to an embodiment of the present invention. FIG. 2 is a view showing a boiler furnace including a heat transfer tube to which the soot blower device according to the present embodiment is applied. FIG. 3 is a diagram showing the relationship between the heat transfer tube receiving pressure and the distance from the spray nozzle in the soot blower device according to the present embodiment. FIG. 4 is a diagram for explaining the state of erosion prevention and heat transfer tube ash removal by the small diameter nozzle and the large diameter nozzle in the soot blower apparatus according to the present embodiment. FIG. 5 is a diagram for explaining the state of heat transfer tube ash removal by nozzle rotation and movement in the soot blower device according to the present embodiment.

  In the drawings, 1 is a soot blower device, 2 is a pressure detector, 3 is a pressure regulating valve, 4 is a pressure regulating valve control device, 5 is a solenoid valve, 6 is a solenoid valve control device, 8 is a heat transfer tube, and 10 is a large spray nozzle. , 11 is a small spray nozzle, 12 is a boiler furnace, 13 is a furnace water wall, 14 is a bank, 15 is a suspended heat transfer tube, and a is high-pressure steam.

  In FIG. 1, a soot blower device 1 includes a steam pressure adjustment mechanism (a pressure detector 2, a pressure adjustment valve 3, a control device 4, and the like) that can adjust the pressure and amount of high-pressure steam a injected from the spray nozzles 10 and 11. Is connected). Further, as shown in FIG. 2, the soot blower device 1 is surrounded by a suspended heat transfer tube 15 provided at the upper part in the boiler furnace 12 and a bank part 14 (a rear heat transfer wall provided at the rear part of the boiler through which the combustion exhaust gas flows). Installed around the heat transfer tube. Here, the soot blower device 1 rotates a nozzle block (shown) having spray nozzles 10 and 11, a soot blower tube connected to the nozzle block (a tube through which soot blower steam flows), and the soot blower tube. 1 and a drive source (not shown) to be moved. The components 2 to 6 shown in FIG. 1 are a steam system connected to the soot blower device.

  The boiler according to this embodiment has a wide width in the state shown in FIG. 2, so the soot blower device 1 is installed in both the left and right directions (see the soot blower device 1 provided in the bank unit 14 shown in FIG. 2). Operation control can be performed independently (each soot blower device can be operated in turn). The nozzle block at the tip of the soot blower device 1 has two nozzles for spraying the spray medium, a nozzle 10 having a large injection nozzle diameter and a nozzle 11 having a small injection nozzle diameter, and the installation angle between the nozzles 10 and 11. Is 180 degrees (in the example shown in FIG. 1, the positional relationship between the nozzle 10 and the nozzle 11 in the axial direction of the soot blower device is the same). The soot blower device 1 has a structure in which the nozzle block can rotate around an axis, and moves while rotating from the furnace wall side to the center of the furnace (the solid line of the soot blower device 1 in (2) of FIG. 4). And ash adhering to the heat transfer tube 8 can be removed. Here, as a mechanism for moving the nozzle block of the soot blower device 1 to the center of the furnace while rotating, a conventional technique using a gear and a motor is generally used, and this technique may also be adopted in this embodiment. .

  In this embodiment, as shown in (2) of FIG. 4, the rotation speed of the soot blower device (nozzle block) is t seconds / rotation, and the feed speed is t seconds / between pipes (transmission in (2) of FIG. 4). The time for moving the center portion <2> between the heat tube center <1> and the heat transfer tube is 0.5 tsec), so that the portion of the heat transfer tube 8 is pressurized from the nozzle 11 having a small nozzle diameter. Steam is sprayed, and high-pressure steam from the nozzle 10 having a large nozzle diameter circulates between the heat transfer tubes 8 and 8. In the present embodiment, since the thickness of the bank portion 14 in the combustion gas flow direction is different for each part, the nozzle diameter and the spray pressure are different for each part, but the ratio of the hole area of the large diameter nozzle to the small diameter nozzle is 1.2. Within the range of ~ 1.5.

  Next, the relationship between the jet fluid receiving pressure on the heat transfer tube surface, the generation of erosion, and the removal of attached ash in the soot blower device according to the embodiment of the present invention will be described below with reference to FIGS. (1) in FIG. 3 represents the state of the heat transfer tube receiving pressure when the nozzle diameter is small and (2) in FIG. 3 is the large nozzle diameter.

  As shown in FIG. 3, the distribution of pressure receiving pressure on the front surface of the heat transfer tube varies depending on the positional relationship between the spray nozzle position of the soot blower device 1 and the heat transfer tube 8. That is, the spray medium sprayed at the position <1> where the center of the spray nozzle and the heat transfer tube coincide (see <1> shown in (2) of FIG. 4) collides with the front surface of the heat transfer tube in the front row, Is the maximum (solid line in FIG. 3), but the spray medium sprayed at the position <2> (see <2> shown in (2) of FIG. 4) where the spray nozzle coincides with the center between the adjacent heat transfer tubes Does not collide with the heat transfer tube in the foremost row, but collides with the heat transfer tube on the downstream side of the combustion gas, and the receiving pressure becomes maximum (the chain line in FIG. 3).

  Here, the maximum receiving pressures of the solid line graph and the one-dot chain line graph of FIG. 3 are different, and the former is about 2 to 3 times larger than the latter. This is because the center velocity of the jet is attenuated in inverse proportion to the square of the distance. Thus, the heat transfer tubes in the front row are in the most severe environment against erosion. FIG. 3 also shows a lower limit value at which erosion occurs and a minimum pressure value required to remove adhering ash, depending on the pressure receiving pressure on the heat transfer tube surface.

  As shown in (1) and (2) of FIG. 3, the pressure receiving pressure on the front surface of the heat transfer tube is greatly changed by changing the nozzle hole diameter from large to small. That is, referring to the one-dot chain line graph of (2) in FIG. 3, the high-pressure steam sprayed from the large-diameter nozzle passes through the position <2> that coincides with the center between the adjacent heat transfer tubes. High pressure receiving pressure can be maintained up to the heat transfer tube, and ash can be removed effectively. On the other hand, the pressure receiving pressure on the front surface of the heat transfer tube is small, and the heat transfer tube is not worn by erosion. Further, referring to the solid line graph of (1) in FIG. 3, the high-pressure steam sprayed from the small diameter nozzle passes through the position <1> where the center of the spray nozzle and the heat transfer tube coincide with each other. Is small and does not cause wear due to erosion.

  In addition, according to (1) of FIG. 3, when the nozzle diameter is small and the positions of the center between the nozzles and the nozzle coincide with each other (see the one-dot chain line graph), the attached ash cannot be removed on the rearmost side of the heat transfer tube. Further, according to (2) of FIG. 3, it is shown that erosion can occur on the head tube side when the nozzle diameter is large and the positions of the tube center and the nozzle coincide (refer to the solid line graph). ing.

  Therefore, in the embodiment of the present invention, as shown in FIG. 4, the nozzle center and the heat transfer tube center coincide with each other when the injection nozzle is small, and the nozzle center and the heat transfer tube center coincide with each other when the injection nozzle is large. It is one of the features that it is configured so as to make it. In this way, even when coal with strong adhesion is burned, ash adhering to the heat transfer tube away from the soot blower device can be efficiently removed and erosion of the heat transfer tube close to the soot blower device can be prevented. .

  Here, the soot blower device 1 moves while rotating, but as shown in FIG. 5 (2), compared to the case where high-pressure steam is sprayed from a large-diameter nozzle at the center position (a) between the pipes, for example, Assuming that the high-pressure steam from the large-diameter nozzle is sprayed at the center position between the tubes at the position (b) rotated by 45 degrees, the resistance of the tube is small and the high-pressure steam reaches the position (c). Is sprayed at a position slightly displaced from the center position between the tubes at the position (b) rotated by 45 degrees, so that the reach distance is shortened by the resistance of the tubes and reaches the position (b). It can be seen that even at the position (b), the radius (the ash removal effective range in the figure) from which the ash can be removed hardly changes compared to (a).

  Further, when removing the ash from the upstream and downstream banks of the soot blower device with a single soot blower device, it is necessary to shift the upstream and downstream heat transfer tube tube pitch by a half pitch. That is, when the large-diameter nozzle of one soot blower device is positioned opposite to the center between the tubes of the downstream heat transfer tubes, the small-diameter nozzle disposed 180 ° away from the large-diameter nozzle is the tube of the upstream heat transfer tube. Must be opposite the center. This situation corresponds to the tube pitch of the heat transfer tubes being shifted by a half pitch.

  Furthermore, when the upstream and downstream heat transfer tube tube pitches are not shifted, the axial length direction positions of the two nozzle holes (large diameter and small diameter nozzle holes) are shifted by a half pitch of the heat transfer tube tube pitch. May be. In this case, providing a small-diameter hole on the distal end side of the soot blower device 1 is effective in suppressing the shake of the soot blower device 1 based on the difference in the injection amount between the large-diameter and small-diameter nozzles.

  As described above, the soot blower device according to the embodiment of the present invention is characterized by having the following configuration and functions or actions. That is, in a rotary moving soot blower device that removes ash and the like adhering to a heat transfer tube of a boiler furnace, a spray nozzle having a large hole diameter and a small hole diameter are provided, and a gap space between adjacent heat transfer tubes is provided. The spray medium is sprayed from the large-diameter nozzle, and the spray medium from the small-diameter nozzle is sprayed on the heat transfer tube.

  Further, in this soot blower device, the supply amount and pressure of the spray medium can be arbitrarily adjusted in consideration of the degree of ash adhesion and the tube surface material of the heat transfer tube, and the arrangement relationship between the heat transfer tubes is In consideration of this, the rotational speed and moving speed of the soot blower can be arbitrarily adjusted. In detail, a combustion test is performed for each type and property of coal before the start of the facility, and this is done by observing the degree of ash adhesion to the heat transfer tube for each type and property of coal. The observation results are applied during the actual combustion of coal to adjust the supply amount and pressure of the spray medium. Similarly, the rotational speed and moving speed of the soot blower device are adjusted in accordance with the diameter and pitch of the heat transfer tubes installed in the facility.

  Then, this embodiment adopts the configuration described above as a result of experimentally finding that the distribution of pressure receiving pressure on the front surface of the heat transfer tube varies depending on the positional relationship between the spray nozzle position of the soot blower device and the heat transfer tube. . That is, the spray medium sprayed at the position where the center of the spray nozzle and the heat transfer tube coincides collides with the front surface of the heat transfer tube in the front row, and the maximum pressure is received, but the spray nozzle matches the center between adjacent heat transfer tubes. The spray medium sprayed at the position where the spray medium does not collide with the heat transfer tube in the foremost row collides with the heat transfer tube on the downstream side of the spray medium, and the receiving pressure becomes maximum. The maximum receiving pressures of the two are different, and the former (nozzle and tube center coincide) has a value about two to three times larger than the latter. This is because the center velocity of the jet is attenuated in inverse proportion to the square of the distance. Thus, the heat transfer tubes in the front row are in the most severe environment against erosion. On the other hand, it was experimentally found that the pressure received on the front surface of the heat transfer tube greatly changes by changing the nozzle hole diameter.

  Accordingly, in the embodiment of the present invention, nozzles having different spray nozzle hole diameters (large diameter nozzle and small diameter nozzle) are provided in the soot blower device, and the spray medium from the large diameter nozzle is placed in the gap between adjacent heat transfer tubes. By spraying and spraying the spray medium from the small-diameter nozzle onto the heat transfer tube, it is possible to achieve the removal of ash adhering to the heat transfer tube away from the soot blower device even with highly adherent coal. Erosion of the heat transfer tube close to the soot blower device can be prevented.

It is a distribution diagram showing the whole composition of the soot blower device concerning the embodiment of the present invention. It is a figure showing a boiler furnace provided with a heat exchanger tube to which a soot blower device concerning this embodiment is applied. It is a figure showing the relationship between the heat exchanger tube receiving pressure in the soot blower apparatus which concerns on this embodiment, and the distance from a spray nozzle. It is a figure explaining the erosion generation | occurrence | production prevention by the small diameter nozzle and large diameter nozzle in the soot blower apparatus which concerns on this embodiment, and the condition of heat exchanger tube ash removal. It is a figure explaining the situation of the heat transfer tube ash removal by nozzle rotation in the soot blower device concerning this embodiment. It is a systematic diagram which shows the whole structure of the soot blower apparatus regarding a prior art. It is a soot blower apparatus regarding a prior art, and is a figure presenting a technique for reducing the amount of erosion in a heat transfer tube close to the soot blower apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Soot blower apparatus 2 Pressure detector 3 Pressure regulating valve 4 Pressure regulating valve control apparatus 5 Electromagnetic valve 6 Electromagnetic valve control apparatus 8 Heat transfer tube 9 Protector 10 Spray nozzle large 11 Spray nozzle small 12 Boiler furnace 13 Furnace water wall part 14 Bank part 15 Hanging heat transfer tube a High-pressure steam

Claims (5)

In a rotary moving soot blower device that removes ash etc. adhering to the heat transfer tube of a boiler furnace,
A large and small diameter spray nozzle is provided at the tip of the soot blower device.
Spraying the spray medium from the large-diameter spray nozzle in the gap between adjacent heat transfer tubes, and spraying the spray medium from the small-diameter spray nozzle to the tube surface of the heat transfer tube. A soot blower device. In claim 1,
The soot blower device characterized in that the supply amount and pressure of the spray medium can be arbitrarily adjusted. In claim 1 or 2,
The soot blower device, wherein the rotation speed and the moving speed of the soot blower device provided with the spray nozzle can be arbitrarily adjusted. In claim 1, 2 or 3,
The soot blower device is characterized in that the large diameter and small diameter spray nozzles are provided at the same position in the axial length of the soot blower device and at an interval of approximately 180 °. In claim 1, 2 or 3,
Heat transfer tubes are arranged on the upstream and downstream sides of the combustion gas so as to face the soot blower device,
The soot blower device is characterized in that the large diameter and small diameter spray nozzles are provided with their axial length positions shifted by a half pitch of the arrangement pitch of the heat transfer tubes.

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