JP2002349840A - Pre-purge type soot blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pre-purge type soot blower used in a heat exchanger in a low temperature range such as gas-gas heaters, etc., which is so structured as to never suck pre-purge vapor containing water content into the heat exchanger from a lance pipe inserting hole. SOLUTION: The blower comprises a pressure reducing means for keeping a pre-purge box at an internal pressure lower than the gas pressure in a heat exchanger, thereby keeping the pre-purged vapor at a low pressure by the pressure reducing means enough to separate it into a gas and water content. Thus the water content is removed to prevent a much water-containing vapor or water drops from flowing into the heat exchanger during pre-purge operation, thereby getting rid of corrosion of the heat exchanger tubes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepurge type soot blower used for a heat exchanger in a low temperature gas range such as a gas gas heater.

[0002]

2. Description of the Related Art A soot blower installed in a heat exchanger in a low temperature gas region such as a gas gas heater is provided with a prepurge box in a casing portion for the purpose of preventing corrosion of a drain on the soot blower side due to blowing into the heat exchanger. Before the soot blower starts soot blowing in the purge box, high-temperature steam is sent to the feed pipe, the lance pipe, and the steam pipe to perform pre-purge to discharge drain and to perform warm pipe.In general, this apparatus is provided with a pre-purge type soot blower. Is called.

An outline of a conventional prepurge type soot blower will be described with reference to FIG. FIG. 8 is a longitudinal sectional view schematically showing a prepurge box portion of a conventional prepurge-type soot blower.

In FIG. 8, reference numeral 20 denotes a casing of a heat exchanger; 21, a circular lance pipe insertion port formed in the casing 20; 22, a prepurge box provided on the outer surface of the casing 20 eccentrically to the lance pipe insertion port 21; Reference numeral 23 denotes a lance pipe insertion port provided on the rear side of the prepurge box 22 concentrically with the lance pipe insertion port 21, and 24 denotes a prepurge box 2
Reference numeral 25 denotes a seal box provided concentrically with the insertion port 23 on the outside of the rear surface of the second box 2, and 25 denotes a seal air supply pipe connected to the seal box.

[0005] Inside the prepurge box 22, a cylindrical buffer plate 26 made of a perforated plate is provided concentrically with the lance tube insertion ports 21 and 23.
A drain tube 27 is provided at the lower part of the drain pipe.

Reference numeral 28 denotes a lance pipe (steam injection pipe) of a soot blower. The tip of the lance pipe is inserted into the prepurge box 22 from the seal box 24 side, passes through the prepurge box 22, and is connected to the heat exchanger. It is configured to reach the casing 20.

The lance tube 28 has a plurality of pairs of steam injection holes 29 in the distal end portion in the radial direction, and the position where the steam injection holes 29 are inside the seal box 24 is a stop position S at the end of the lance tube 28, The position where the hole 29 enters the prepurge box 22 beyond the insertion port 23 is the prepurge position P, and the position where the steam injection hole 29 further extends beyond the lance pipe insertion port 21 and enters the heat exchanger at the distance L1 is steam injection. Start position J,
Moves from the stop position S to the pre-purge position P in a set time cycle, temporarily stops and performs a pre-purge injection operation for a predetermined time, moves to the steam injection start position J after the end of the pre-purge injection, and starts steam injection. Then, while rotating around the axis, reciprocating in the depth direction in the heat exchanger for a required distance, removing soot from the heat exchanger tube group, and returning to the stop position S again are repeated.

[0008]

In the conventional prepurge-type soot blower configured as described above, high-temperature steam from the lance tube 28 is injected into the cylindrical buffer plate 26 and the wall surface of the prepurge box 22 during the prepurge operation. In the process, moisture in the steam is separated and discharged from the drain pipe 27, and the steam from which the moisture has been separated is released from the lance tube insertion port 21 of the casing 20 into the heat exchanger.

However, when the gas for heating the heat exchange tube in the heat exchanger is suctioned at one end of the casing by a fan or a gas pump or the like and flows through the heat exchanger, the heat exchanger has a negative pressure. By the action of this negative pressure, the steam containing moisture or the moisture separated from the steam that has been pre-purged injected into the pre-purge box 22 is sucked into the heat exchanger together with the steam through the lance pipe insertion opening 21 to generate heat. The problem of wetting the exchanger tubes and causing corrosion is of concern.

The present invention solves such a problem in the conventional prepurge type soot blower, and prevents the prepurge vapor containing water in the prepurge box from being sucked into the heat exchanger from the lance tube insertion port. It is an object of the present invention to provide a prepurge-type soot blower.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. As a first means, a prepurge box is arranged around a lance tube insertion opening formed in a heat exchanger casing. A pre-purge type soot blower in which a lance pipe is inserted and withdrawn through the same pre-purge box, wherein the pre-purge is provided with a pressure reducing means for maintaining the internal pressure of the pre-purge box lower than the gas pressure in the heat exchanger during the pre-purge operation. The present invention provides a soot blower.

That is, according to the first means, since the pressure reducing means for maintaining the internal pressure of the prepurge box lower than the gas pressure in the heat exchanger at the time of the prepurge operation is provided, the prepurged steam is reduced in pressure by the pressure reduction. Water is removed by maintaining water at a low pressure by means of water and water is removed, preventing vapor streams and water droplets with a high water content from flowing into the heat exchanger during the prepurge operation, and causing corrosion in the heat exchanger tube. Is to be resolved.

Further, the present invention provides, as a second means, the first means.
Means, wherein the pressure reducing means provides a prepurge-type soot blower constituted by an exhaust pipe with a check valve connected to the prepurge box, and ejector means for applying a predetermined suction force to the exhaust pipe. It is.

That is, according to the second means, a check valve connected to the prepurge box is provided as pressure reducing means for maintaining the internal pressure of the prepurge box during the prepurge operation at a pressure lower than the gas pressure in the heat exchanger. Since this is constituted by an exhaust pipe and ejector means for applying a predetermined suction force to the exhaust pipe, the inside of the prepurge box is maintained at a lower pressure than the inside of the heat exchanger by suction by the ejector means. In order to eliminate the occurrence of corrosion in the heat exchanger tube by preventing the steam flow and water droplets with a high moisture content from flowing into the heat exchanger during the prepurge operation, by separating the steam from the steam and water. It was made.

Further, the present invention provides, as a third means, the second means.
In the above means, the ejector means provides a prepurge-type soot blower configured to be driven by ejector steam branched from a prepurge steam supply pipe system of the soot blower during a prepurge operation.

That is, according to the third means, the ejector means as pressure reducing means for maintaining the internal pressure of the prepurge box at a pressure lower than the gas pressure in the heat exchanger during the prepurge operation is branched from the prepurge steam supply pipe system. Since it is configured to be driven by the ejector steam, the steam source is not provided separately for the ejector means, but the steam source originally provided as a soot blower is used to eliminate the equipment. Things.

Further, the present invention provides, as fourth means, the second means.
In the above means, the ejector means is provided with a prepurge-type soot blower which is connected to a steam supply source different from the prepurge steam and is configured to operate or stop in synchronization with the prepurge steam during a prepurge operation.

That is, according to the fourth means, the ejector means as the pressure reducing means for maintaining the internal pressure of the pre-purge box at a pressure lower than the gas pressure in the heat exchanger during the pre-purge operation is different from the pre-purge steam and the steam supply means. Since it is connected to the source, it is possible to use steam at a higher pressure than the prepurge steam, it is possible to generate a large suction force in the ejector means, and it is possible to easily and reliably reduce the pressure in the prepurge box. It is like that.

The present invention provides, as a fifth means, the first means.
In the means, the decompression means extends from the prepurge box to the downstream side of the heat exchanger along the outer surface of the casing of the heat exchanger, and the tip side penetrates the wall surface of the casing and is located downstream of the heat exchange tube group. An object of the present invention is to provide a prepurge soot blower constituted by a bypass exhaust pipe having an opening.

In other words, according to the fifth means, the pressure reducing means for maintaining the internal pressure of the prepurge box at a lower pressure than the gas pressure in the heat exchanger during the prepurge operation makes the prepurge box evacuate the casing of the heat exchanger. Since it is constituted by a bypass exhaust pipe opening downstream from the heat exchange tube group, the heat exchanger enters the prepurge box through the lance pipe insertion port, and further passes through the bypass exhaust pipe to the heat exchanger. A bypass flow returning to the inner and downstream areas is generated, and the steam injected into the prepurge box during the prepurge operation is moved by this bypass flow, so that the corrosion problem due to the prepurge steam is eliminated without being mixed with the heat exchange tube group. It is designed to work.

The present invention also provides, as a sixth means, the first means.
In any one of the means (4) to (4), a lance tube insertion opening formed in the heat exchanger casing is provided with a short cylindrical wall into which the lance tube is inserted with a small gap between the lance tube and the lance tube.
An object of the present invention is to provide a prepurge-type soot blower provided with an extension at the tip of the lance tube which is inserted into the short cylindrical wall at a prepurge operation position.

According to the sixth means, a short cylindrical wall into which the lance tube is inserted is provided at the lance tube insertion opening with a small gap between the lance tube and the lance tube insertion end. Is provided with an extension inserted into the short cylinder wall at the prepurge operation position, so that the short cylinder wall and the extension of the tip of the lance tube overlap with a small gap therebetween, and the short cylinder wall opening is formed. The opening area is reduced, so that the prepurge steam is not drawn into the heat exchanger from the lance tube insertion port, thereby eliminating the corrosion problem of the heat exchange tube group due to the prepurge steam.

Further, the present invention provides, as a seventh means, the first means.
In any one of the means (4) to (4), the lance tube insertion opening formed in the heat exchanger casing is engaged with the lance tube entering and retreating into the heat exchanger casing to open or cover the lance tube insertion opening. The present invention provides a prepurge-type soot blower provided with a shielding plate that is opened and closed as described above.

According to the seventh means, since the lance pipe insertion port is provided with the shielding plate for opening and closing the lance pipe insertion port by the lance pipe, the lance pipe is in the prepurge box during the prepurge operation. In the above, the shield plate is kept under its own weight so as to cover the lance tube insertion port, and the steam flow from the prepurge box to the heat exchanger via the lance tube insertion port is reduced.

Further, as an eighth means, the present invention provides a prepurge-type soot blower according to the seventh means, wherein the shielding plate is a hinge-type open-close type.

That is, according to the eighth means, since the shield plate for opening and closing the lance tube insertion opening by the lance tube is configured as a hinged type of its own weight, it is easily opened when the lance tube enters. Further, when the lance tube is retracted, the lance tube is reliably closed, so that the steam flow from the prepurge box to the heat exchanger via the lance tube insertion port can be more reliably minimized.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is an overall side view of a prepurge soot blower according to the present embodiment.

In the present embodiment, a pressure reducing means for lowering the pressure in the prepurge box to a pressure lower than the gas pressure in the heat exchanger is added to the conventional prepurge type soot blower described above. The same parts as those of the related art described with reference to FIG. 8 are denoted by the same reference numerals in the drawings so as to avoid duplication of description as much as possible, and the matters unique to the present embodiment will be omitted. Will be explained with emphasis.

That is, in the present embodiment, reference numeral 30 denotes a pull-out soot blower main body having the lance tube 28 as a main component.

The soot blower main body 30 includes a feed pipe 31 inserted into and removed from the lance pipe 28,
The head valve 32 is connected to a base end of the soot blowing pipe 33. The head valve 32 is connected to a soot blowing steam supply pipe 33 that supplies steam as an injection medium.

A prepurge steam pipe 35 having a prepurge valve 34 that bypasses the head valve 32 and connects the steam supply pipe 33 to the base end of the feed pipe 31 is provided.

Reference numeral 36 denotes a pressure reducing means connected to the prepurge box 22 for reducing the pressure inside the prepurge box 22 to a gas pressure lower than the gas pressure in the heat exchanger. , A check valve 38 on the exhaust pipe 37, and an ejector means 39 connected to the other end of the exhaust pipe 37.

The ejector means 39 includes an ejector 40 connected to the outlet of the exhaust pipe 37, an ejector vapor supply pipe 41 connected to the inlet of the ejector 40 and the outlet of the prepurge valve 34, and an outlet of the ejector 40. It is composed of a silencer 42 connected.

The pressure reducing means 36 is not limited to the above-described ejector means 39, but may be provided in any other suitable configuration. In addition, a high-temperature gas other than steam can be used as the injection medium. Of course, there is.

In the present embodiment configured as described above, the operation of moving the lance tube 28 of the soot blower 30 from the stop position S → the prepurge position P → the steam injection start position J → the stop position S, and the steam injection start position The soot removal operation that starts steam injection from J and reciprocates in the heat exchanger in the depth direction while rotating the lance tube 28 may be the same as the conventional one described above. Omitted.

That is, in this embodiment, after moving the lance pipe 28 from the stop position S to the prepurge position P at a set time cycle, when the prepurge valve 34 is opened, the prepurge steam pipe 35 → the feed pipe 31 → the lance pipe 28 Then, the injection of the prepurge steam starts in the prepurge box 22 through the injection hole 29, and at the same time, the steam injection of the ejector 40 through the prepurge steam pipe 35 → the ejector steam supply pipe 41 starts.

The pre-purge box 22 passes through the check valve 38 and the exhaust pipe 37 by the steam injection force of the ejector 40.
The pre-purge jet vapor in the inside is sucked into the exhaust pipe 37 side, and the pre-purge box 2 is adjusted by adjusting the suction force on the ejector 40 side.
2 can be maintained at a lower pressure than in the heat exchanger.

Under this operation, according to the present embodiment, in the prepurge box 22, the steam pre-purged from the lance pipe 28 separates steam and water while forming a flow toward the exhaust pipe 37. , Water is dripped and drain is drained 2
7, the steam passes through the exhaust pipe 37, merges with the jet steam of the ejector 40, and is discharged to the silencer 42 side.

For this reason, a steam flow or water droplets containing a large amount of water during the prepurge operation does not flow into the heat exchanger from the lance tube insertion opening 21 of the casing 20, and the heat exchange tube is corroded by the inflow of the prepurge steam into the heat exchanger. Is eliminated.

Further, the steam supplied to the ejector 40 via the ejector steam supply pipe 41 branches off from the pre-purge steam supply pipe system (soot blowing steam supply pipe 33), so that the steam source for the ejector 40 is shared. In addition, the equipment could be saved.

Next, a second embodiment of the present invention will be described with reference to FIG.
It will be described based on. FIG. 2 is an overall side view of the prepurge type soot blower according to the present embodiment.

In the present embodiment, the ejector means 36 in the first embodiment is configured to be energized by a steam supply source different from the steam supply pipe 33 for soot blowing. Since the second embodiment is the same as the first embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals in the drawings so that the description will not be redundant, and redundant description will be omitted. The points specific to the present embodiment will be mainly described.

That is, in the present embodiment, reference numeral 43 denotes a steam supply source different from the steam supply pipe 33 for soot blowing, and reference numeral 41a denotes an ejector steam pipe in which the inlet side of the ejector 40 is connected between the other steam supply sources 43. , 44 are ejector steam pipes 41a
The upper ejector valve 45 is a remote control unit that controls the ejector valve 44 and the prepurge valve 34 in conjunction with each other.

Since the present embodiment is configured as described above, the remote control unit 45 controls the pre-purge valve 34 and the ejector valve 44 to be opened and closed in synchronization with each other, so that the pre-purge operation and the operation of the ejector 40 of the pressure reducing means 36 are performed. Parallel.

At this time, the ejector means 39 can use steam having a higher pressure than the prepurge steam by using the steam supply source 43 different from the prepurge steam supplied through the soot blowing steam supply pipe 33. it can.

Thus, according to the present embodiment, it is possible to generate a large suction force from the pre-purge box 22 to the exhaust pipe 37 and the ejector 40, and the advantage that the pressure in the pre-purge box 22 can be easily reduced is obtained. . Needless to say, the rest is the same as in the above embodiment.

Next, a third embodiment of the present invention will be described with reference to FIG.
It will be described based on. FIG. 3 is an explanatory diagram of a prepurge soot blower according to the present embodiment.

In this embodiment, an exhaust pipe connected to the prepurge box 22 of the soot blower is used as a pressure reducing means for maintaining the internal pressure of the prepurge box 22 at a lower pressure than the gas pressure in the heat exchanger during the prepurge operation. The heating gas pump suction side downstream from the heat exchange tube group in the heat exchanger is opened and opened, and the pre-purge vapor is bypass-exhausted through the exhaust pipe by the suction force of the heating gas flow.

In order to avoid redundant description, the same parts as those in the above-described conventional and the first and second embodiments are denoted by the same reference numerals in the drawings, and redundant description will be omitted. The following description focuses on features specific to the present embodiment.

That is, in this embodiment, in order to make it easy to understand the relationship between the heat exchanger and the soot blower, the heat exchanger is shown in a plan view and the prepurge type soot blower is shown in a side view in FIG. In the figure, 47 is a heat exchanger, 20 is a casing of the heat exchanger 47, 48 is a tube group for heat exchange arranged inside the heat exchanger 47, and an arrow 49.
A heating-side gas flow sucked and moved inside the heat exchanger 47 by a fan or a gas pump (not shown). A heat-exchange tube group 50 extends horizontally from the prepurge box 22 along the outside of the casing and the tip side penetrates the casing 20. 48
The exhaust pipe is expanded in the heat exchanger 47 in the downstream area of the exhaust pipe.

Here, the exhaust pipe 50 is connected to the first and second embodiments.
Although corresponding to the exhaust pipe 37 in the embodiment, the exhaust pipe 50 in the present embodiment is desirably configured to have a larger diameter than the exhaust pipe 37.

In the present embodiment configured as described above, the exhaust pipe 5 is heated by the heated gas flow 49 in the heat exchanger 47.
A suction force toward the open end is generated in the inside of the cylinder, and this suction force acts to reduce the pressure inside the prepurge box 22.

As a result, arrows 49a, 4a
As shown by 9b and 49c, the heat exchanger 47 enters the prepurge box 22 through the lance tube insertion port 21 and enters the prepurge box 22.
Further, a bypass flow returning to the downstream area inside the heat exchanger 47 through the exhaust pipe 50 is generated.

Thus, according to the present embodiment, the steam injected into the prepurge box 22 during the prepurge operation joins the downstream region in the heat exchanger 47 through the exhaust pipe 50 on this bypass flow. As a result, the lance tube insertion port 2
Thus, the problem of corrosion of the heat exchange tube group 48 due to the prepurge vapor is eliminated.

Therefore, as in the first and second embodiments described above, the pressure inside the prepurge box 22 is reduced by a simple structure without using the independent pressure reducing means 36, and the pressure reducing means 36 is used. Similar functions and effects can be obtained.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
A description will be given based on FIG. FIG. 4 is a vertical sectional side view of a prepurge box and a lance tube tip portion when the prepurge type soot blower according to the present embodiment is stopped, and FIG. 5 is a longitudinal sectional side view during a prepurge operation corresponding to FIG.

In the present embodiment, the prepurge box 22
The lance pipe insertion port 21 and the lance pipe tip are configured so that the prepurge steam is not easily sucked into the heat exchanger through the lance pipe insertion port 21 from the inside.

In order to avoid redundant description, the same parts as those of the above-described conventional device and the first to third embodiments are denoted by the same reference numerals in the drawings, and redundant description will be omitted. The following description focuses on features specific to the present embodiment.

That is, in this embodiment, reference numeral 51 denotes a short cylindrical wall which is fixed to the circumferential portion of the lance tube insertion opening 21 of the casing 20 in a direction perpendicular to the casing 20.
Reference numeral 52 denotes a soot-adhering eave provided at the inner end of the heat exchanger 47 of the short cylindrical wall 51, and reference numeral 53 denotes a lance tube tip extension portion formed to extend from the steam injection port 29 of the lance tube 28 to the tip side. The soot adhesion preventing eaves 52 may be omitted).

The short cylindrical wall 51 and the lance tube tip extension 53 are moved to the prepurge position P shown by a solid line in FIG.
The short cylindrical wall 51 and the lance tube tip extension 53 are configured to overlap each other with a small gap therebetween in the radial direction.

According to the present embodiment configured as described above, the short cylindrical wall 51 and the lance tube tip extension 53 are fitted with an annular gap therebetween during the prepurge operation, and the short lance tube insertion opening 21 is shorted. The cylindrical wall opening is changed to a small-width annular opening due to the small gap, and the opening area (that is, the gas passage area) is significantly reduced.

As described above, according to the present embodiment, the prepurge steam during the prepurge operation is supplied to the prepurge box 22.
The lance tube insertion port 2
Thus, the problem of corrosion of the heat exchange tube group 48 due to the prepurge vapor is eliminated.

The present embodiment is not limited to functioning alone, but can be used in combination with the first to third embodiments, and the combined use promotes depressurization in the prepurge box 22. Further, the effect of further preventing corrosion of the heat exchange tube by the prepurge steam is obtained.

Next, a fifth embodiment of the present invention will be described with reference to FIG.
A description will be given based on FIG. 6 is a longitudinal sectional side view of a prepurge box and a lance tube tip portion of the prepurge-type soot blower according to the present embodiment, and FIG. 7 is a view taken along the line VII-VII of FIG. In the present embodiment, the heat exchanger casing 20
And a conventional lance tube insertion port 21 and a conventional lance tube 28 without a tip extension in the soot blower, and a self-opening / closing type shield plate 55 that covers the lance tube insertion port 21 is provided inside the casing 20. This constitutes a prepurge-type soot blower.

In order to avoid redundant description, the same parts as those of the above-described conventional one and the first to fourth embodiments are denoted by the same reference numerals in the drawings, and redundant description will be omitted. The following description focuses on features specific to the present embodiment.

That is, in the present embodiment, the shielding plate 55 is provided on the upper end of the apron-shaped thin plate 56 covering the lance tube insertion opening 21 as shown in FIG.
And a sled-shaped portion 56a
The two ends of the shaft 57 are hingedly provided by bearings 58 provided on the inner surface of the casing 20 above the lance tube insertion port 21, and are pushed open by the lance tube 28 entering the lance tube insertion port 21. Then, the lance tube 28 is closed by its own weight by retreating into the prepurge box 22.

The shielding plate 55 is not limited to the apron shape, the shaft structure at the upper end, and the like, but may be provided in another suitable opening / closing structure by changing its shape and structure. is there.

According to the present embodiment configured as described above, since the shielding plate 55 can be provided as a thin plate and lightweight, the shielding plate 55 enters the heat exchanger from the lance tube insertion opening 21. The lance tube 28 opens and closes lightly in contact with the retreating lance tube 28, the operation is easy and accurate, and the weight of the shielding plate 55 applied on the lance tube 28 that has entered the heat exchanger is within the lance tube 28 heat exchanger. There is no impediment to the steam injection.

When the lance tube 28 is in the prepurge box 22 during the prepurge operation, the shielding plate 55 keeps the state of covering the lance tube insertion opening 21 by its own weight, and the lance tube is inserted from the prepurge box 22 during the prepurge operation. It is possible to structurally prevent the steam flow toward the heat exchanger via the port 21 from being reduced to the minimum.

Although the present invention has been described with reference to the illustrated embodiments, the present invention is not limited to such embodiments.
It goes without saying that various changes may be made to the specific structure within the scope of the present invention.

[0071]

As described above, according to the first aspect of the present invention, a prepurge box is disposed around the lance tube insertion opening formed in the heat exchanger casing, and the lance tube is passed through the prepurge box. The pre-purge soot blower has a pressure-reducing means for maintaining the internal pressure of the pre-purge box at a pressure lower than the gas pressure in the heat exchanger during the pre-purge operation. The steam thus removed is kept at a low pressure by the pressure reducing means to separate water and water to remove water, and prevent a steam flow and water droplets having a large amount of water from flowing into the heat exchanger during the pre-purge operation, thereby generating heat. Obtain a reliable prepurge sootblower that eliminates the source of corrosion in exchanger tubes and eliminates the need to worry about corrosion problems It is those that can.

According to a second aspect of the present invention, in the first aspect of the present invention, the pressure reducing means includes an exhaust pipe with a check valve connected to the prepurge box; The pre-purge soot blower is constituted by ejector means for applying a predetermined suction force to the pre-purge box, so that the inside of the pre-purge box is maintained at a lower pressure than the inside of the heat exchanger by suction by the ejector means, whereby the pre-purge is performed. The steam is separated into water and water to remove water, preventing the flow of watery steam and water droplets from flowing into the heat exchanger during the prepurge operation, eliminating the problem of corrosion occurring in the heat exchanger tube, and corroding. A highly reliable prepurge-type soot blower without having to worry about problems was obtained.

According to a third aspect of the present invention, in the second aspect of the invention, the ejector means is driven by ejector steam branched from a prepurge steam supply pipe system of a soot blower during a prepurge operation. And a prepurge-type soot blower, so that a steam source originally provided as a soot blower is used as it is without providing a separate steam source for the ejector means, and the equipment is omitted, so that heat is eliminated. It is possible to obtain a suitable prepurge-type soot blower with high reliability without having to worry about the problem of occurrence of corrosion in the exchanger tube.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the ejector is connected to a separate steam supply source from the prepurge steam, and is connected to the prepurge steam during the prepurge operation. Since the pre-purge soot blower is configured to start or stop in synchronization with the pre-purge type soot blower, steam having a higher pressure than the pre-purge steam can be used by another steam source, and as a result, a large suction force is applied to the ejector means. A reliable and suitable prepurge-type soot blower that achieves easy and reliable depressurization in the prepurge box without having to worry about the problem of corrosion occurrence in the heat exchanger tube. That's what we got.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the pressure reducing means is provided downstream of the heat exchanger along the casing outer surface of the heat exchanger from the prepurge box. Side, the front end side penetrates the wall surface of the casing, and is constituted by a bypass exhaust pipe which is opened downstream from the heat exchange tube group. , A bypass flow is generated that passes through the bypass exhaust pipe and returns to the downstream area of the heat exchanger through the bypass exhaust pipe, and the steam injected into the prepurge box during the prepurge operation is moved by the bypass flow. Therefore, it is necessary to eliminate the corrosion problem caused by the prepurge steam and to be concerned about the occurrence of corrosion in the heat exchanger tubes without being confused with the heat exchange tube group. One in which it was possible to obtain a suitable pre-purge type sootblower rich nor reliable.

According to the invention described in claim 6, in the invention described in any one of claims 1 to 4, between the lance pipe insertion opening formed in the heat exchanger casing and the lance pipe, The lance tube is inserted with a small gap in the lance tube, and the lance tube tip is provided with an extension inserted into the short cylinder wall at the prepurge operation position to constitute a prepurge soot blower. In the pre-purge operation position, the short cylindrical wall and the extension of the lance tube tip overlap each other with a small gap therebetween, the opening area of the short cylindrical wall opening decreases, and the short lance tube insertion opening into the heat exchanger. Prepurge vapor is eliminated, eliminating the corrosion problem of the heat exchange tube group due to the prepurge vapor, and a reliable and suitable preparator that does not need to worry about the occurrence of corrosion in the heat exchanger tubes. One in which it was possible to obtain an expression soot blower.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the lance tube insertion opening formed in the heat exchanger casing is provided with the same heat exchanger casing. The pre-purge type soot blower is configured by providing a shielding plate that is opened and closed so as to engage with the lance pipe that enters and retreats and opens or covers the lance pipe insertion port. During a certain prepurge operation, the shield plate keeps the lance tube insertion port under its own weight, reducing the steam flow from the prepurge box to the heat exchanger through the lance tube insertion port, and using a simple structure. Eliminates corrosion problems caused by prepurge steam,
It is possible to obtain a suitable prepurge type soot blower with high reliability without having to worry about the occurrence of corrosion in the heat exchanger tube.

Further, according to the invention described in claim 8, in the invention described in claim 7, the shielding plate is configured as a hinge type of a self-weight opening / closing type to form a prepurge-type soot blower. Therefore, the shield plate that opens and closes the lance tube insertion port is easily opened when the lance tube enters, and is securely closed when the lance tube retreats. The steam flow toward the hopper was more reliably minimized, the corrosion problem due to the prepurge steam was eliminated, and a reliable and suitable prepurge type soot blower without having to worry about the occurrence of corrosion in the heat exchanger tube was obtained. Things.

[Brief description of the drawings]

FIG. 1 is an overall side view of a prepurge-type soot blower according to a first embodiment of the present invention.

FIG. 2 is an overall side view of a prepurge-type soot blower according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a prepurge-type soot blower according to a third embodiment of the present invention.

FIG. 4 is a longitudinal sectional side view of a prepurge box and a lance tube tip when a prepurge type soot blower according to a fourth embodiment of the present invention is stopped.

FIG. 5 is a vertical sectional side view at the time of a prepurge operation corresponding to FIG. 4;

FIG. 6 is a longitudinal sectional side view of a prepurge box and a lance tube tip portion of a prepurge-type soot blower according to a fifth embodiment of the present invention.

FIG. 7 is a view taken along arrow VII-VII in FIG. 6;

FIG. 8 is a longitudinal sectional view schematically showing a prepurge box portion of a conventional prepurge soot blower.

[Explanation of symbols]

 Reference Signs List 20 heat exchanger casing 21, 23 lance pipe insertion port 22 prepurge box 24 seal box 25 seal air supply pipe 26 buffer plate 27 drain removal pipe 28 lance pipe 29 steam injection hole 30 soot blower 31 feed pipe 32 head valve 33 soot blowing steam supply Pipe 34 prepurge valve 35 prepurge steam pipe 36 pressure reducing means 37 exhaust pipe 38 check valve 39 ejector means 40 ejector 41, 41a ejector steam supply pipe 42 silencer 43 steam supply source 44 ejector valve 45 remote control unit 47 heat exchanger 48 heat exchange Tube group for heating 49 Gas flow on heating side 50 Bypass exhaust pipe 49a-49c Bypass gas flow 51 Short cylindrical wall 52 Eaves for preventing soot adhesion 53 Lance tube tip extension 55 Shielding plate 56 Thin plate 56a Sledge-shaped portion 57 Shaft 58 Shaft

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsuaki Hoshi 5007 Itozakicho, Mihara City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd.Mihara Machinery & Transportation Systems Plant (72) Inventor Shigeo Hasegawa 1-20 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture No. 24 F-term in Ryomei Giken Co., Ltd. (Reference) 3K061 QC02 QC03 QC21 QC34

Claims (8)

[Claims] A prepurge box is provided around a lance pipe insertion opening formed in a heat exchanger casing, and a prepurge type soot blower which operates to pull out and insert a lance pipe through the prepurge box is provided during a prepurge operation. A prepurge-type soot blower comprising a pressure reducing means for maintaining an internal pressure of a prepurge box lower than a gas pressure in a heat exchanger. 2. The pressure reducing means comprises an exhaust pipe with a check valve connected to the pre-purge box, and an ejector means for applying a predetermined suction force to the exhaust pipe. Item 2. A prepurge-type soot blower according to Item 1. 3. The pre-purge soot blower according to claim 2, wherein said ejector means is configured to be driven by ejector steam branched from a pre-purge steam supply pipe system of the soot blower during a pre-purge operation. 4. The apparatus according to claim 2, wherein the ejector means is connected to a steam supply source different from the prepurge steam, and is configured to operate or stop in synchronization with the prepurge steam during a prepurge operation. The described prepurge type soot blower. 5. The decompression means extends from the prepurge box to a downstream side of the heat exchanger along an outer surface of a casing of the heat exchanger, and a leading end penetrates a wall surface of the casing and is located downstream of the heat exchange tube group. 2. A pre-purge type soot blower according to claim 1, wherein the pre-purge type soot blower is constituted by a bypass exhaust pipe that opens to the inside. 6. A lance tube insertion opening formed in the heat exchanger casing is provided with a short cylindrical wall into which the lance tube is inserted with a small gap between the lance tube and the lance tube tip. 5. A prepurge soot blower according to claim 1, further comprising an extension inserted into the short cylindrical wall at a prepurge operation position. 7. A lance tube insertion opening formed in the heat exchanger casing is engaged with a lance tube which enters and retreats from the heat exchanger casing, and is opened and closed to open or cover the lance tube insertion opening. 5. A prepurge-type soot blower according to claim 1, further comprising a shielding plate. 8. The prepurge-type soot blower according to claim 7, wherein the shielding plate is configured as a hinge type of a self-weight opening / closing type.